thermodynamic prediction of growth temperature dependence in the adhesion of pseudomonas aeruginosa...

Thermodynamic Prediction of Growth Temperature Dependencein the Adhesion of Pseudomonas aeruginosa and Staphylococcus

aureus to Stainless Steel and Polycarbonate

MARWAN ABDALLAH12 CORINNE BENOLIEL2 CHARAFEDDINE JAMA3 DJAMEL DRIDER1 PASCAL DHULSTER1

AND NOUR-EDDINE CHIHIB1

1Laboratoire de Procedes Biologiques Genie Enzymatique et Microbien (ProBioGEM) IUT APolytechrsquoLille Universite de Lille Science et Technologies

Avenue Paul Langevin F-59655 Villeneuve drsquoAscq Cedex France 2Laboratoire SCIENTIS Parc Biocitech - 102 Avenue Gaston Roussel 93230

Romainville France and 3Laboratoire UMET UMR-CNRS 8207 Ecole Nationale Superieure de Chimie de Lille Universite Lille 1 Avenue DimitriMendeleıev 59655 Villeneuve drsquoAscq France

MS 13-365 Received 6 September 2013Accepted 16 January 2014

ABSTRACT

This study investigated the effect of growth temperature changes (20 30 and 37uC) on the adhesion behavior of

Pseudomonas aeruginosa and Staphylococcus aureus to stainless steel and polycarbonate Adhesion assays were performed

under static conditions at 20uC In addition the validity of the thermodynamic and extended Derjaguin Landau Verwey and

Overbeek theories as predictive tools of bacterial adhesion were studied The surface properties of the bacterial cells and the

substrates of attachment were characterized and atomic force microscopy was used to analyze the surface topography The results

indicated that the highest adhesion rate of P aeruginosa and S aureus on both surfaces was observed when the cells were grown

at 37uC The bacterial adhesion to stainless steel was found to be two times higher than to polycarbonate for both bacteria

whatever the condition used The present study underlined that the thermodynamic and the extended Derjaguin Landau Verwey

and Overbeek theories were able to partially predict the empirical results of P aeruginosa adhesion However these theories

failed to predict the adhesion behavior of S aureus to both surfaces when the growth temperature was changed The results of the

microbial adhesion to solvent indicated that the adhesion rate to abiotic surfaces may correlate with the hydrophobicity of

bacterial surfaces The effect of surface topography on bacterial adhesion showed that surface roughness even on the very low

nanometer scale has a significant effect on bacterial adhesion behavior

The ability of bacteria to adhere to abiotic surfaces is a

major concern in the food industry biofilms may create a

persistent source of contamination and may lead to food

spoilage or food poisoning Moreover when contamination

of food products occurs evidence suggests that microor-

ganisms on the surface of food processing equipment are a

major source (9 20 37) These contaminants are mainly

associated with water and raw foods Food handlers have

also been identified as a significant source of contaminants

Thus microorganisms emerge in the food sector from

different ecosystems and these cells have been exposed to

different conditions such as temperature water activity (aw)

and pH (ie they have been exposed to specific background

conditions) (35) Therefore study of bacterial adhesion that

takes into account the background exposure of the bacterial

cells is important because it can help to reduce the micro-

biological risk associated with food contact surfaces

It is now established that bacterial adhesion to abiotic

surfaces is influenced by various factors such as microbial

growth phase culture conditions temperature ionic

strength and variability of strains (23 25 41 43)Previous studies have also reported that the physicochem-

ical properties of surfaces such as hydrophobicity play a

crucial role in bacterial attachment to abiotic surfaces (1213 22) However other studies have indicated that

physicochemical properties have only a minor role and

that the correlations between surface properties and

bacterial adhesion were poor (34) This discrepancy seems

to be related to the method used to characterize the surface

properties of bacterial cells In fact Hamadi and Latrache

(11) failed to establish a correlation between the microbial

adhesion to solvent and the contact angle outcomes To

predict bacterial adhesion the Derjaguin Verwey Landau

and Overbeek (DLVO) theory has been used in several

studies According to this theory as the bacterial cell

approaches a surface of interest the entire cell will be

exposed to nonspecific physicochemical forces such as

Lifshitzndashvan der Waals (LW) and electrostatic (EL) forces

The extended DLVO (XDLVO) theory added short-range

Lewis acid-base (AB) interactions in microbial adhesion (438) However the validation of this theory as a predictive

physicochemical model to study bacterial adhesion is still

under investigation Author for correspondence Tel z33 320417567 Fax z33 328767356

E-mail nour-eddinechihibuniv-lille1fr

1116

Journal of Food Protection Vol 77 No 7 2014 Pages 1116ndash1126doi1043150362-028XJFP-13-365Copyright G International Association for Food Protection

The present work was carried out on Pseudomonasaeruginosa and Staphylococcus aureus which are involved

in food spoilage and food poisoning The purpose of the

current work was to study the effect of growth temperature

on bacterial adhesion to stainless steel and polycarbonate

two surfaces frequently used in food processing equipment

Adhesion assays were performed under static conditions at

20uC In order to characterize the mechanisms of bacterial

adhesion cell surface properties were studied using contact

angle measurements (CAMs) and microbial adhesion to

organic solvent (MATS) In addition CAMs and atomic

force microscopy (AFM) were used to study the surface

properties and topography of both stainless steel and

polycarbonate respectively CAM outcomes were also used

to predict bacterial adhesion using the LW-AB and the

XDLVO theories Subsequently empirical adhesion data of

bacteria cultivated on surfaces at different temperatures (20

30 and 37uC) were compared with theoretical predictions

This study aimed to unravel the relationship between

environmental factors and bacterial adhesion to surfaces

This data contributes to the understanding of and therefore

prevention of bacterial adhesion to surfaces and subsequent

biofilm formation

MATERIALS AND METHODS

Bacterial strains and culture conditions The bacterial

strains used for this study were P aeruginosa CIP 103467 and Saureus CIP 483 The strains were stored at 280uC in tryptic soy

broth (TSB Biokar Diagnostics Pantin France) containing 40

(volvol) glycerol To prepare precultures 100 ml from frozen stock

cultures was inoculated into 5 ml of TSB and then incubated at the

culture temperature (ie 20 30 or 37uC) The preculture at 20uCwas incubated for 48 h whereas those at 30 and 37uC were

incubated for 24 h The cultures used in each experiment were then

prepared by inoculating 5 | 104 CFUml from the preculture

broths into 50 ml of TSB in sterile 500-ml flasks Cultures were

incubated under shaking (160 rpm) at 20 30 or 37uC and were

stopped at the late exponential phase

Bacterial standardization and cell inoculum preparationP aeruginosa and S aureus grown at 20 30 and 37uC as described

previously were harvested by centrifugation for 10 min at 3500 | g(20uC) Bacteria were washed twice with 20 ml of 100 mM

potassium phosphate buffer (PB pH 7) and finally were resuspended

in 20 ml of PB The cells were dispersed by sonication at 37 kHz for

5 min at 25uC (Elmasonic S60H Elma Singen Germany)

Subsequently bacteria were resuspended in the PB to a cell

concentration of 1 | 108 CFUml by adjusting the optical density

to OD620 nm ~ 0110 iexcl 0005 (108 CFUml) using an Ultrospec

1100 pro UV-visible light spectrophotometer (GE Healthcare

Waukesha WI) Standardized cell suspensions were diluted 10-fold

for use in the bacterial adhesion assays (107 CFUml)

Slide preparation and adhesion assays The stainless steel

and polycarbonate surfaces were cleaned by soaking in ethanol

95 (Fluka Sigma-Aldrich St Louis MO) overnight to remove

grease Next slides were rinsed in water and soaked in 500 ml of

TDF4 detergent (5 Franklab SA Billancourt France) for 20 min

at 50uC under agitation The slides were then thoroughly rinsed

five times for 1 min with agitation in 500 ml of distilled water at

room temperature to eliminate detergent followed by three washes

with ultrapure water (Milli-Q Academic Millipore Molsheim

France) The clean stainless steel slides were air dried and sterilized

by autoclaving at 121uC for 15 min Polycarbonate slides were

sterilized for 10 min with absolute ethanol (Fluka Sigma-Aldrich)

The sterile slides were placed in a horizontal position in petri

dishes The upper face of each slide was covered with 3 ml of cell

inoculum (107 CFUml) and incubated statically at 20uC for 60 min

for the bacterial adhesion assays After attachment the coupons

were removed using sterile forceps and were rinsed by gentle

dipping into 30 ml of PB to remove excess liquid droplets and

loosely attached cells Cells were then stained for 10 min in the

dark using acridine orange stain 001 (wtvol) followed by

gentle dipping in 30 ml of ultrapure water The attached cells were

quantified using epifluorescence microscopy (Nikon Optiphot-2

EFD3 Nikon Inc Melville NY) A total of 50 fields per coupon

were scanned and the fluorescent cells were enumerated Counts

were presented as number of bacteria in the microscopy field The

results present the average of three independent experiments and

two coupons were studied for each experiment

CAMs The contact angles of the bacterial cell surfaces were

measured using the sessile drop method Bacterial suspensions

prepared as described above were adjusted to an OD620 nm of 10

using either PB or ultrapure water To evaluate the cell surface

hydrophobicity and hydrophilicity cells harvested by centrifuga-

tion were washed once with ultrapure water and were resuspended

in the same water to an OD620 nm of 10 The cells suspended in

ultrapure water or PB were vacuum filtered through a 045-mm-

pore-size nitrocellulose membrane filter (type HA Millipore

Bedford MA) to create a bacterial lawn The bacterial cell filters

were attached to glass slides using double-sided adhesive tape and

were dried for 30 min at 37uC The contact angles of water

diiodomethane and formamide were measured immediately

after drop deposition on the bacterial lawn with a digital camera

using WinDrop software (20uC) (Digidrop goniometer GBX-

Instruments France) At least five drops of each probe liquid were

deposited onto each filter For stainless steel and polycarbonate

surfaces five drops of the probe liquid were also measured CAM

results present the average of the measurements taken on three

independently bacterial or solid surfaces

MATS The MATS method described by Bellon-Fontaine

et al (3) based on the comparison of microbial cell affinity to both

monopolar and apolar solvents was used to determine the

hydrophobicity and the electron donor (basic) or acceptor (acidic)

properties of microbial cells Experimentally bacteria were

suspended to an optical density of 09 at 405 nm (A0)

(approximately 108 CFUml cell density) in 100 mM PB A

volume (24 ml) of each bacterial suspension was vortexed for 90 s

with 04 ml of solvent The mixture was allowed to stand for 15 min

to ensure complete separation of the two phases The optical

density of the water phase was then measured using a

spectrophotometer The affinity of cells for each solvent was

subsequently calculated by the following equation

Affinity~ 1 A=A0eth THORNfrac12 eth1THORNwhere A0 is the absorbance measured at 405 nm of the bacterial

suspension before mixing and A is the absorbance after mixing

The following pairs of solvents as described by Bellon-Fontaine

et al (3) were used chloroform (an electron acceptor solvent)

hexadecane (a nonpolar solvent) ethyl acetate (an electron donor

solvent) and decane (a nonpolar solvent) Owing to the similar LW

components of the surface tension in each pair of solvents

differences between the affinities to solvents would indicate the

electron donor and electron acceptor character of the bacterial

J Food Prot Vol 77 No 7 ENVIRONMENTAL AND THERMODYNAMIC PREDICTIONS OF BACTERIAL ADHESION 1117

surface The affinity of cells to hexadecane was used as a measure

of cell surface hydrophobicity

Measurement of zeta potential The electrical properties of

bacteria were measured by microelectrophoresis using a Zeta

Compact zetameter (CAD Instruments Les Essarts-le-Roi France)

by tracking bacteria with a coupled device camera The

electrophoretic mobility of bacteria suspended in PB was converted

to apparent zeta potentials according to the Helmotz-Smolu-

chowski equation (2) Bacteria were suspended in each 50 ml of

PB to obtain approximately 70 bacteria per reading The zeta

potential of stainless steel and polycarbonate was measured using

an electrokinetic analyzer (SurPASS Anton Paar GmbH Graz

Austria) as described elsewhere (14) The rectangular slides were

placed in clamping cells and the zeta potential was determined

from the Smoluchowski equation by measuring the change in

streaming current versus the applied differential pressure For the

electrolyte 1 mM KCl solution was used and 01 M HCl and 01 M

NaOH were used to adjust the pH to 7

AFM An atomic force microscope (Dimension 3100

microscope Bruker Santa Barbara CA) was used to analyze the

nanometer scale surface roughness of stainless steel and polycar-

bonate slides The cantilever was a NCHV-A (Bruker) typically

125 mm with an apex curvature radius on the order of 10 nm and

the cantilever spring constant was 42 Nm Root mean square

roughness was determined over an area of 1 mm2 using WSXM

software (Nanotec Electronica Madrid Spain)

Surface energies of bacteria and substrata The surface

energy characteristics of the bacteria and materials were calculated

according to Youngrsquos equation (21 40) expressed as

cos h~1z2

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffifficLW

S cLWl

qcl

z

ffiffiffiffiffiffiffiffiffiffiffiffifficz

S cl

pcl

z

ffiffiffiffiffiffiffiffiffiffiffiffiffic

S czl

pcl

0

1A eth2THORN

where h is the contact angle and cl is the surface tension (mJm2) of

the liquid used for the measurement The subscript S refers to the

solid surface or bacteria and l refers to the liquid used for contact

angle measurement By using three different liquids with known cl

cLWl cz

l and cl values (water formamide and diiodomethane)

the unknown surface tension components can be estimated (solid

surfaces cLWS cz

S and cS bacterial surfaces cLW

b czb and c

b )

The bacterial and the substrata surface tensions are calculated

using the following equation

c~cLWzcAB~cLWz2ffiffiffiffiffiffiffiffiffiffiffiffifficzc

peth3THORN

where c is the surface tension and cAB the polar component of the

surface tension

LW-AB theory In the thermodynamic theory related to the

bacterial attachment (4) the derived free energies of adhesion do

not account for a distance dependence of the interaction energy

According to this theory the free energy of adhesion at contact

(DGtotadh) is the summation of these two components

DGtotadh~DGLW

adhzDGABadh eth4THORN

The LW DGLWadh and the AB DGAB

adh interactions at contact between a

bacterial surface (b) and a substratum surface (S) immersed in a

liquid medium (l) can be calculated according to equations 5 and 6

DGLWadh~2

ffiffiffiffiffiffiffifficLW

b

q


l

q ffiffiffiffiffiffiffifficLW

Sl

q


l

q eth5THORN

DGABadh~2

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffifficz

b czS

q ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffic

b cS

p


b czl

q

|ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffic

b cl

p


S czl


S cl

p eth6THORN

The XDLVO theory According to the XDLVO theory the

interaction energy between the bacterial cell surface and the

substratum (separated by a distance d) is the sum of LW (DGLW

(d)) Lewis AB (DGAB (d)) and EL (DGEL (d)) interaction

energies The total XDLVO interaction energy is given as Bayoudh

et al (1)

DGtot deth THORN~DGLW deth THORNzDGAB deth THORNzDGEL(d) eth7THORNThe interaction energies for each individual component LW

AB and EL as a function of separation distance are given as in

Bos et al (4)

DGLW deth THORN~A

6

2r dzreth THORNd 1z2reth THORNln

dz2r

d

eth8THORN

where d is the separation distance r is the radius of the bacterium

and A is the Hamaker constant which can be calculated from

equation 7 (4)

A~12pd20DGLW(d0) eth9THORN

where DGLWadh is calculated as described above and d0 ~ 0157 nm

is the minimum separation distance between the outermost cell

surface and the substratum surface (41)

The distance dependence of the AB interaction energies is

given by Bos et al (4)

DGAB deth THORN~2prDGABadhexp

d0dleth THORN eth10THORN

where DGABadh is calculated as described above (from the ther-

modynamic theory) and l is the correlation length of molecules in

the liquid medium (estimated to be 06 nm for hydrophilic bacteria

and 13 nm for hydrophobic bacteria) (39)

EL interaction energies as a function of separation distance

are also calculated according to Bos et al (4)

DGEL deth THORN~pee0r f2bzf2

S

|

2fbfs

f2bzf2

S

ln1ze kdeth THORN

1e kdeth THORN

zln 1ze 2kdeth THORN

h i( )eth11THORN

where ee0 is the dielectric permittivity of the medium fb and fs are

the surface zeta potentials of the bacterial surface and collector

surface in the surrounding liquid respectively and k is the

reciprocal Debye length

Statistics The results are presented as mean values and their

standard error of mean Data analysis was performed using Sigma

Plot 110 (Systat Software Inc San Jose CA) using one-way

analysis of variance (Tukeyrsquos method) to determine the significance

of differences Results were considered significant at P 005

RESULTS

Bacterial and substrata surfaces properties No

matter which theories are used to predict bacterial adhesion

LW AB components and surface charge are needed to

calculate the LW AB and EL interaction energies between

bacteria and surfaces CAMs were then performed and the

data related to hd hw and hF were used to calculate the

surface energy components of substrates and bacterial cells

(Table 1)

1118 ABDALLAH ET AL J Food Prot Vol 77 No 7

Surface properties of stainless steel and polycar-bonate The calculation of the surface tension indicated that

stainless steel is more hydrophilic (471 mJm2) than

polycarbonate (434 mJm2) (Table 1) In addition the two

surfaces presented a greater electron donor component than

the electron acceptor component (c2 118 and cz 38 mJ

m2 for the stainless steel and c2 72 and cz 01 mJm2 for

the polycarbonate) Zeta potential measurement results

indicate that the stainless steel had more than twofold

greater negative charge than the polycarbonate (Table 1)

Surface properties of bacteria grown at differenttemperatures The results show that the growth tempera-

ture has a significant effect on the bacterial surface

properties (Table 1) When the growth temperature in-

creased from 20 to 37uC our findings showed that LW

component of P aeruginosa surface tension increased from

293 to 367 mJm2 and the electron donor component

decreased from 521 to 413 mJm2 (Table 1) The electron

acceptor component was 02 22 and 21 mJm2

respectively when P aeruginosa was grown at 20 30

and 37uC (Table 1) The LW component of S aureussurface tension decreased from 385 to 285 mJm2 whereas

the electron donor component increased from 342 to

643 mJm2 when the growth temperature increased from

20 to 37uC (Table 1) When S aureus was grown at 20 and

30uC the electron acceptor component was 05 mJm2 This

value increased to 26 mJm2 when S aureus was cultivated

at 37uC (Table 1) The results related to zeta potential

measurements indicated that P aeruginosa and S aureuscells were negatively charged whatever the growth temper-

ature The results presented in Table 2 indicate that the

growth temperature had no significant effect (P 005) on

the zeta potential (ca 213 mV) of P aeruginosa However

the zeta potential of S aureus cells decreased from 2169 to

293 mV when growth temperature of this bacterium

increased from 20 to 37uC (Table 1)

Prediction of bacterial adhesion according to LW-AB theory Several theories have been proposed to predict

bacterial adhesion to surfaces (4) The van Oss LW-AB

theory was followed here because it was found to give

consistent results with the microbial adhesion In this

theory the surface free energy of adhesion (DGtotadh) was

divided in two parts the LW acid and AB components

(equation 2) From a thermodynamic point of view

adhesion or attraction between two surfaces occurs when

DGtotadh is negative and the adhesion is thermodynamically

unfavorable when it is positive

The theoretical prediction underline that the adhesion of

P aeruginosa is favorable with negative values of DGtotadh

whatever the conditions studied (Table 2) When the growth

temperature increased from 20 to 37uC the DGtotadh of this

bacterium to stainless steel and to polycarbonate decreased

from 227 to 265 mJm2 (P 005) and from 235

to 297 (P 005) respectively (Table 2) On the other

hand this theory predicted higher interactions with the

stainless steel than the polycarbonate whatever the growth

temperatureTA

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For S aureus the calculation of DGtotadh shows that the

increase of growth temperature has a negative effect on its

adhesion on both stainless steel and polycarbonate (Ta-

ble 2) In addition LW-AB theory predicted an important

adhesion to polycarbonate in comparison to stainless steel

when S aureus is cultivated at 20 by contrast to 37uC(Table 2) When the growth temperature was 30uC the

DGtotadh between S aureus and stainless steel or polycarbon-

ate were similar (P 005) (Table 2)

Prediction of bacterial adhesion according toXDLVO theory In the XDLVO theory calculation of AB

interactions between bacteria and surfaces varies when

bacteria are either hydrophobic or hydrophilic In order to

assess the hydrophobicity and hydrophilicity of bacteria the

free energy of cohesion was calculated for bacteria

immersed in water (Table 3) Under the conditions used

P aeruginosa and S aureus present a hydrophilic character

with positive values of free energy of cohesion When the

growth temperature increased from 20 to 37uC Paeruginosa became more hydrophobic and the free energy

of cohesion decreased from 349 to 126 mJm2 (Table 3)

However the hydrophilic character of S aureus increased

when growth temperature increased The results indicated

that the free energy of cohesion increased from 36 to

382 mJm2 when the growth temperature increased from 20

to 37uC (Table 3)

The XDLVO theory relates to the origin of hydropho-

bic interactions in microbial adhesion and considers the

fundamental noncovalent interactions LW EL and Lewis

AB forces (4) In this theory the adhesion energies are

calculated at the closest approach and as a function of the

separation distance (Figs 1A through 1F and 2A through

2F)

P aeruginosa and the XDLVO prediction The results

shown in Figure 1A through 1D reveal that DGLW and

DGAB between P aeruginosa and surfaces were negative

whatever the conditions used indicating attractive LW and

AB interactions between P aeruginosa and both stainless

steel and polycarbonate In addition when growth temper-

ature increased from 20 to 37uC LW and AB interactions

between P aeruginosa and both studied surfaces increased

significantly (P 005) (Fig 1A through 1D) Figure 1C

and 1D shows that the AB interactions between P

aeruginosa and surfaces in a distance less than 3 nm were

much higher (two to six times higher) than LW interactions

Moreover XDLVO predicted higher AB interactions with

polycarbonate than stainless steel when P aeruginosa was

grown at 30 and 37uC Figure 1E and 1F shows that the

repulsive EL interactions between surfaces and P aerugi-nosa were not significantly different with the growth

temperature changes The summation of WL AB and EL

interactions as a function of separation distance predicted a

greater adhesion of P aeruginosa grown at 37uC to stainless

steel and polycarbonate when compared with the cells

grown at 30 and 20uC (P 005) (Fig 1G and 1H)

Moreover XDLVO predicted a greater adhesion to

polycarbonate than to stainless steel when P aeruginosawas cultivated at 30 and 37uC (P 005)

S aureus and the XDLVO prediction The results

shown in Figure 2A and 2B reveal that the DGLW between

S aureus and surfaces are favorable with negative values

whatever the conditions of growth In addition the predicted

results indicated that LW interactions between surfaces and

S aureus grown at 20uC are stronger than those grown at 30

and 37uC (Fig 2A and 2B) The DGLW between S aureusgrown at 30 and 37uC are not significantly different

whatever the surfaces used (P 005) Attractive AB

interactions between surfaces and S aureus are found only

when bacteria were cultivated at 20uC (Fig 2C and 2D)

However XDLVO theory predicted repulsive AB interac-

tions between S aureus grown at 37uC and the studied

surfaces S aureus cells grown at 37uC have higher

repulsive AB interactions with polycarbonate than with

stainless steel (P 005) Nevertheless the cells grown at

20uC showed higher attractive AB interactions with the

polycarbonate than with the stainless steel The theoretical

prediction results show that the repulsive EL interactions

between S aureus and surfaces significantly decreased

when growth temperature increased from 20 to 37uC(Fig 2E and 2F) The summation of LW AB and EL

interactions between S aureus and surfaces reveals that the

adhesion prediction followed the tendency of AB interac-

tions results (Fig 2G and 2H)

Effect of growth temperature on the adhesion of Paeruginosa and S aureus to stainless steel and polycar-bonate In the current work bacterial adhesion was

TABLE 2 Interaction energy at contact between bacterial strains and stainless steel according to the LW-AB theory

Stainless steel (mJm2) Polycarbonate (mJm2)

Strains T (uC) DGLWadh DGAB

adhDGtot

adh DGLWadh DGAB

adhDGtot

adh

Pseudomonasaeruginosa

20 217 iexcl 03 211 iexcl 08 227 iexcl 08 229 iexcl 05 205 iexcl 02 235 iexcl 05



Staphylococcusaureus




a Immersed in 100 mM phosphate buffer (pH 7) T bacterial growth temperature DGLWadh DGAB

adh and DGtotadh van der Waals acid-base

and thermodynamic interaction energy respectively at contact between bacterial and substrata surfaces


performed on stainless steel and polycarbonate in order

to study the correlation between the thermodynamic

prediction and the empirical results Our findings show

that the bacterial adhesion on the two surfaces increased

when the growth temperature increased (Fig 3) The

adhesion of P aeruginosa on stainless steel increased

significantly (by 19-fold) when the growth temperature

increased from 20 to 37uC (P 005) and by 16-fold

when growth temperature increased from 30 to 37uC (P

005) (Fig 3A) Our results indicated also that the

adhesion of P aeruginosa onto polycarbonate significant-

ly increased (by 18-fold) when growth temperature


(P 005) when the temperature increased from 30 to

37uC (Fig 3B) These experimental results indicate that

the adhesion rate of P aeruginosa was two times higher

on stainless steel than on polycarbonate whatever the

growth temperature (Fig 3)

As seen in Figure 3 the adhesion of S aureus to

stainless steel and polycarbonate increased 16 and 12 times

when growth temperature increased respectively from 20

to 37uC and from 30 to 37uC In addition the adhesion of Saureus on stainless steel was two times higher than on

polycarbonate whatever the surface used (Fig 3B)

Bacterial surface properties according to MATS In

order to check the outcomes derived from the contact angle

measurements the MATS technique was used to character-

ize the bacterial surfaces properties of both P aeruginosaand S aureus The results of Table 4 indicate that the

hydrophobic character of P aeruginosa and S aureusincreased when the growth temperature increased The

affinity of P aeruginosa to hexadecane increased 18-fold

(P 005) when growth temperature increased from 20 to

37uC P aeruginosa grown at 30 and 37uC has the same

affinity to hexadecane The affinity of S aureus cells to

hexadecane increased about 21-fold (P 005) when the

growth temperature increased from 20 to 37uC and 14-fold

(P 005) when the temperature increased from 30 to 37uC

P aeruginosa decreased the electron donor character from

035 to 018 (P 005) when growth temperature increased

from 20 to 37uC The electron acceptor character increased

from 002 to 014 (P 005) S aureus decreased the

electron donor character from 035 to 051 (P 005) and

increased the electron acceptor character from 2016 to

2027 when the growth temperature increased from 20 to

37uC (Table 4)

Surface topography of stainless steel and polycar-bonate The topography of stainless steel and polycarbonate

was characterized using AFM in order to study the

relationship between the surface roughness and the bacterial

adhesion The results of AFM reveal that the two studied

surfaces present a different surface topography (Fig 4A

through 4D) Our results indicated also that the surface

of the stainless steel appears to be almost 10-fold rougher

than the polycarbonate The root mean square values were

20 and 2 nm for stainless steel and polycarbonate

respectivelyTA

BL

E3

C

ell

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ing

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DISCUSSION

The contamination of processing equipment surfaces

and the cross-contamination of food products with food-

borne pathogens is a major public health concern To

prevent infections related to these contaminants and to

reduce the microbiological risk more knowledge is needed

on the influence of environmental conditions and bacterial

ecological history at the first stage of biofilm formation (ie

initial adhesion) When the growth temperature increased

from 20 to 37uC the ability of both P aeruginosa and Saureus to attach to stainless steel and polycarbonate surfaces

increased Our results seem to be consistent with what has

been reported on the effect of growth temperature on the

adhesion of P aeruginosa (5) Listeria monocytogenes (10)and Escherichia coli to different abiotic surfaces (36) In

addition our work highlights the need to pay more attention

to the ecological background and origins of the bacteria of

interest which significantly influences bacterial adhesion to

abiotic surfaces

To control biofilm formation in food processing many

studies have investigated the first step in biofilm formation

and different models have been proposed to describe and to

predict bacterial adhesion to surfaces However it has been

reported that the thermodynamic theory cannot fully explain

initial bacterial adhesion to surfaces which is consistent with

our results The inability may be the result of an inadequate

description of EL interactions in the thermodynamic theory

(32) Because this theory may not be able to fully explain

microbial adhesion we predicted that bacterial adhesion of

cells cultivated at different temperatures would better follow

the XDLVO theory This model was found to be an effective

and useful tool to predict and to explain the bacterial adhesion

of different strains to abiotic surfaces (19 31 32)For P aeruginosa the XDLVO theory was able

to correctly predict the adhesion of this bacterium on

both studied surfaces when the growth temperature was

increased This correlation was mainly due to the increase of

attractive LW and AB interactions with the rise of growth

FIGURE 1 Lifshitzndashvan der Waals (LW)acid-base (AB) electrostatic (EL) andXDLVO (tot) interactions between P aer-

uginosa and stainless steel or polycarbon-ate as a function of separation distance (AC E and G) Interactions with stainlesssteel (B D F and H) Interactionswith polycarbonate


temperature The effect of repulsive EL interactions on the

total energy of XDLVO theory appeared to be minor

compared to the other interactions In fact the high ionic

strength of PB may decrease the magnitude and the effect of

EL interactions on the theoretical prediction (4) However

the XDLVO theory failed to predict the highest adhesion

rate to stainless steel whatever the growth temperature

studied Our results also show a higher absolute value in a

FIGURE 2 Lifshitzndashvan der Waals (LW)acid-base (AB) electrostatic (EL) andXDLVO (tot) interactions between S

aureus and stainless steel or polycarbon-ate as a function of separation distance(A C E and G) Interactions with stainlesssteel (B D F and H) Interactionswith polycarbonate

FIGURE 3 Effect of growth temperature on the adhesion of P aeruginosa and S aureus to stainless steel and polycarbonate (A)Adhesion of P aeruginosa to stainless steel and polycarbonate (B) adhesion of S aureus to stainless steel and polycarbonate


distance less than 3 nm of AB as compared with LW and

EL interactions This is in agreement with previous studies

that showed that the AB interactions are the most important

interactions in bacterial adhesion to surfaces (28 30) The

XDLVO theory predicted greater attractive AB interactions

between P aeruginosa and polycarbonate in comparison to

stainless steel this was the theoryrsquos main failure for this

bacterium

For S aureus our experimental results show an

increase in cell adhesion to stainless steel and polycarbonate

with the rise of growth temperature In this case the XDLVO

theory completely failed to predict the adhesion of S aureusto either surface and at any growth temperature studied In

fact the XDLVO theory predicted the opposite of the

empirical results obtained for the S aureus adhesion These

results agree with studies that stated that in some cases the

XDLVO theory is unable to predict bacterial adhesion to

abiotic surfaces (6 18 28) This discrepancy was mainly

due to the influence of AB interactions on the XDLVO

predictions of S aureus adhesion

The calculation of AB interactions between bacteria

and surfaces is based on electron acceptor and electron

donor components of bacterial cells which can be obtained

from CAM outcomes Previous studies have shown a lack of

correlation between the outcomes of CAMs and other

techniques such as MATS especially in the AB compo-

nents (11) However our results reveal that the electron

donor property of bacterial surfaces using MATS correlated

with the CAM results These results are in agreement with

the finding of Bellon-Fontaine et al (3) who found a

correlation between MATS and CAM outcomes The

decrease of the electron donor character and the increase

of the electron acceptor character of P aeruginosa when the

growth temperature increased could explain the increase of

adhesion onto both stainless steel and polycarbonate This is

promoted by the increase of attractive AB interactions

TABLE 4 Effect of growth temperature on bacterial surface properties according to MATSa

Bacterium T (uC) Chloroform Ethyl acetate Decane Hexadecane Electron donor Electron acceptor









a MATS microbial adhesion to organic solvent T growth temperature The difference between chloroform and hexadecane affinities of

cells suspended in 100 mM phosphate buffer (PB pH 7) determines the electron donor properties The difference between ethyl acetate

and decane affinities of cells suspended in 100 mM PB (pH 7) determines the electron acceptor properties

FIGURE 4 The AFM characterization ofstainless steel and polycarbonate (A and C)Top and three-dimensional views of thestainless steel topography (B and D) Topand three-dimensional views of the polycar-bonate topography


between P aeruginosa cells and the two surfaces By

contrast the AB character of S aureus according to the

MATS measurement did not explain the differences found

in the experimental results The MATS result indicated that

the increase in bacterial hydrophobicity with increasing

bacterial growth temperature may have resulted in increas-

ing of bacterial adhesion of P aeruginosa and S aureus

However this result is not in agreement with what has been

reported on the involvement of hydrophobicity in the

adhesion of L monocytogenes (26)In general studies on the prediction of bacterial

adhesion to abiotic surfaces were made in optimal culture

conditions when strains are tested However bacteria in

natural ecosystems and or in man-made ones are subjected

to various environmental stresses and this could influence

the physicochemical properties of cell surfaces and then the

behavior of bacterial adhesion Presumably intrinsic factors

related to the cell envelope such as adhesins cell wall

proteins extracellular polymers flagellar motility pili are

involved in bacterial attachment to surfaces (17) In turn

these structures are reportedly influenced by the growth

temperature (7 15 24 29) The discrepancy between

empirical and theoretical results is probably due to the

failure of the XDLVO to detect the molecular changes in

bacterial surface that can take place with the change of

growth conditions This discrepancy could be also related to

the surface roughness of abiotic surfaces Although surface

roughness is not included in the XDLVO theory it may also

have an effect on bacterial adhesion as previously reported

(16 33 42) Mitik-Dineva et al (27) underlined that the

adhesion levels of P aeruginosa and S aureus appeared to

be inversely correlated with surface roughness However

our results indicated that stainless steel was 10 times

rougher than polycarbonate and that bacterial adhesion was

two times higher on stainless steel Our results suggest that

nanoscale surface roughness might exert a significant effect

on the bacterial adhesion as previously described Therefore

it should be considered as a parameter of primary interest

alongside other well-recognized factors that control initial

bacterial attachment

In conclusion our results underlined that the bacterial

ecological background in which the bacterium is found

plays a role in the adhesion of bacteria to abiotic surfaces

Moreover growth temperatures close to that of the human

body seemed to increase the adhesion rate to food contact

surfaces This highlighted the important role that food

handlers may play as a reservoir of potential biofilm-

forming pathogens such as S aureus Thus food handlers

should ensure personal hygiene and use the appropriate

personal protective equipment in order to reduce this

microbiological risk in the food area The use of smooth

surfaces in food processing equipment may also reduce the

microbial contamination of surfaces Our findings also

underlined that physicochemical properties of bacteria and

surfaces are equally important and are involved in bacterial

adhesion However our results pointed out that neither the

XDLVO nor the thermodynamic theory can fully predict

experimental bacterial adhesion More studies should

consider the effect of environmental conditions and bacterial

background on the bacterial adhesion to abiotic surfaces It

should be noted that other techniques such as AFM and

chemical force microscopy have recently emerged as

powerful approaches in bacterial adhesion studies (8 10)Further experiments will focus on the quantification of

bacterial adhesion forces using AFM in order to extend the

knowledge of the mechanisms mediating bacterial adhesion

to abiotic surfaces

ACKNOWLEDGMENTS

The authors are grateful to French Agency for Research and

Technology (ANRT) and SCIENTIS laboratory for the CIFRE grant

supporting this work (CIFRE 20100205)

REFERENCES

1 Bayoudh S A Othmane F Bettaieb A Bakhrouf H B Ouada

and L Ponsonnet 2006 Quantification of the adhesion free energy

between bacteria and hydrophobic and hydrophilic substrata Mater

Sci Eng C 26300ndash305

2 Bayoudh S A Othmane L Mora and H Ben Ouada 2009

Assessing bacterial adhesion using DLVO and XDLVO theories and

the jet impingement technique Colloids Surf B Biointerfaces 731ndash9

3 Bellon-Fontaine M N J Rault and C J van Oss 1996 Microbial

adhesion to solvents a novel method to determine the electron-donor

electron-acceptor or Lewis acid-base properties of microbial cells

Colloids Surf B Biointerfaces 747ndash53

4 Bos R H C van der Mei and H J Busscher 1999 Physico-

chemistry of initial microbial adhesive interactionsmdashits mechanisms

and methods for study FEMS Microbiol Rev 23179ndash230

5 Cappello S and S P P Guglielmino 2006 Effects of growth

temperature on polystyrene adhesion of Pseudomonas aeruginosa

ATCC 27853 Braz J Microbiol 37205ndash207

6 Chia T W R V T Nguyen T McMeekin N Fegan and G A

Dykes 2011 Stochasticity of bacterial attachment and its predict-

ability by the extended Derjaguin-Landau-Verwey-Overbeek theory

Appl Environ Microbiol 773757ndash3764

7 Dehus O M Pfitzenmaier G Stuebs N Fischer W Schwaeble

S Morath T Hartung A Geyer and C Hermann 2011 Growth

temperature-dependent expression of structural variants of Listeria

monocytogenes lipoteichoic acid Immunobiology 21624ndash31

8 Dorobantu L S and M R Gray 2010 Application of atomic force

microscopy in bacterial research Scanning 3274ndash96

9 Flint S H P J Bremer and J D Brooks 1997 Biofilms in dairy

manufacturing plantmdashdescription current concerns and methods of

control Biofouling 1181ndash97

10 Gordesli F P and N I Abu-Lail 2011 The role of growth

temperature in the adhesion and mechanics of pathogenic L

monocytogenes an AFM study Langmuir 281360ndash1373

11 Hamadi F and H Latrache 2008 Comparison of contact angle

measurement and microbial adhesion to solvents for assaying electron

donorndashelectron acceptor (acidndashbase) properties of bacterial surface


12 Hamadi F H Latrache M Mabrrouki A Elghmari A Outzourhit

M Ellouali and A Chtaini 2005 Effect of pH on distribution and

adhesion of Staphylococcus aureus to glass J Adhes Sci Technol

1973ndash85

13 Harimawan A A Rajasekar and Y-P Ting 2011 Bacteria

attachment to surfacesmdashAFM force spectroscopy and physicochem-

ical analyses J Colloid Interface Sci 364213ndash218

14 Hedberg Y X Wang J Hedberg M Lundin E Blomberg and

I Odnevall Wallinder 2013 Surface-protein interactions on different

stainless steel grades effects of protein adsorption surface changes

and metal release J Mater Sci Mater Med 241015ndash1033

15 Hemery G S Chevalier M N Bellon-Fontaine D Haras and N

Orange 2007 Growth temperature and OprF porin affect cell surface

physicochemical properties and adhesive capacities of Pseudomonas

fluorescens MF37 J Ind Microbiol Biotechnol 3449ndash54


16 Hilbert L R D Bagge-Ravn J Kold and L Gram 2003 Influence

of surface roughness of stainless steel on microbial adhesion and

corrosion resistance Int Biodeterior Biodegrad 52175ndash185

17 Hori K and S Matsumoto 2010 Bacterial adhesion from

mechanism to control Biochem Eng J 48424ndash434

18 Hwang G S Kang M G El-Din and Y Liu 2012 Impact of

conditioning films on the initial adhesion of Burkholderia cepaciaColloids Surf B Biointerfaces 91181ndash188

19 Hwang G C-H Lee I-S Ahn and B J Mhin 2010 Analysis of

the adhesion of Pseudomonas putida NCIB 9816-4 to a silica gel as a

model soil using extended DLVO theory J Hazard Mater 179983ndash

988

20 Kim S H and C I Wei 2007 Antibiotic resistance and Caco-2 cell

invasion of Pseudomonas aeruginosa isolates from farm environ-

ments and retail products Int J Food Microbiol 115356ndash363

21 Korenevsky A and T J Beveridge 2007 The surface physico-

chemistry and adhesiveness of Shewanella are affected by their

surface polysaccharides Microbiology 1531872ndash1883

22 Li B and B E Logan 2004 Bacterial adhesion to glass and metal-

oxide surfaces Colloids Surf B Biointerfaces 3681ndash90

23 Mafu A A C Plumety L Deschenes and J Goulet 2011

Adhesion of pathogenic bacteria to food contact surfaces influence of

pH of culture Int J Microbiol 2011972494

24 Makin S A and T J Beveridge 1996 Pseudomonas aeruginosa

PAO1 ceases to express serotype-specific lipopolysaccharide at 45

degrees C J Bacteriol 1783350ndash3352

25 McEldowney S and M Fletcher 1988 Effect of pH temperature

and growth conditions on the adhesion of a gliding bacterium and

three nongliding bacteria to polystyrene Microb Ecol 16183ndash195

26 Min S C H Schraft L T Hansen and R Mackereth 2006 Effects

of physicochemical surface characteristics of Listeria monocytogenes

strains on attachment to glass Food Microbiol 23250ndash259

27 Mitik-Dineva N J Wang V K Truong P Stoddart F Malherbe

R J Crawford and E P Ivanova 2009 Escherichia coli

Pseudomonas aeruginosa and Staphylococcus aureus attachment

patterns on glass surfaces with nanoscale roughness Curr Microbiol

58268ndash273

28 Nguyen V T T W R Chia M S Turner N Fegan and G A

Dykes 2011 Quantification of acidndashbase interactions based on

contact angle measurement allows XDLVO predictions to attachment

of Campylobacter jejuni but not Salmonella J Microbiol Methods8689ndash96

29 Padilla D F Acosta J A Garcıa F Real and J Vivas 2009

Temperature influences the expression of fimbriae and flagella in

Hafnia alvei strains an immunofluorescence study Arch Microbiol191191ndash198

30 Roosjen A H J Busscher W Norde and H C van der Mei 2006

Bacterial factors influencing adhesion of Pseudomonas aeruginosa

strains to a poly(ethylene oxide) brush Microbiology 1522673ndash

2682

31 Shao W and Q Zhao 2010 Effect of corrosion rate and surface

energy of silver coatings on bacterial adhesion Colloids Surf B

Biointerfaces 7698ndash103

32 Sharma P K and K Hanumantha Rao 2003 Adhesion of

Paenibacillus polymyxa on chalcopyrite and pyrite surface thermo-

dynamics and extended DLVO theory Colloids Surf B Biointerfaces

2921ndash38

33 Singh A V V Vyas R Patil V Sharma P E Scopelliti G

Bongiorno A Podesta C Lenardi W N Gade and P Milani 2011

Quantitative characterization of the influence of the nanoscale

morphology of nanostructured surfaces on bacterial adhesion and

biofilm formation PLoS ONE 6e25029

34 Teixeira P J Lima J Azeredo and R Oliveira 2008 Adhesion of

Listeria monocytogenes to materials commonly found in domestic

kitchens Int J Food Sci Technol 431239ndash1244

35 Todd E C J D Greig C A Bartleson and B S Michaels 2009

Outbreaks where food workers have been implicated in the spread of

foodborne disease Part 6 Transmission and survival of pathogens in

the food processing and preparation environment J Food Prot 72

202ndash219

36 Tsuji M and K Yokoigawa 2012 Attachment of Escherichia coli

O157H7 to abiotic surfaces of cooking utensils J Food Sci 77

M194ndashM199

37 Van Houdt R and C W Michiels 2010 Biofilm formation and the

food industry a focus on the bacterial outer surface J Appl

Microbiol 1091117ndash1131

38 Van Oss C J 1993 Acid-base interfacial interactions in aqueous

media Colloids Surf A Physicochem Eng Asp 781ndash49

39 Van Oss C J 1994 Interfacial forces in aqueous media Marcel

Dekker New York

40 Van Oss C J R J Good and M K Chaudhury 1988 Additive and

nonadditive surface tension components and the interpretation of

contact angles Langmuir 4884ndash891

41 Walker S L J E Hill J A Redman and M Elimelech 2005

Influence of growth phase on adhesion kinetics of Escherichia coli

D21g Appl Environ Microbiol 713093ndash3099

42 Whitehead K A J Colligon and J Verran 2005 Retention of

microbial cells in substratum surface features of micrometer and sub-

micrometer dimensions Colloids Surf B Biointerfaces 41129ndash138

43 Zita A and M Hermansson 1994 Effects of ionic strength on

bacterial adhesion and stability of flocs in a wastewater activated

sludge system Appl Environ Microbiol 603041ndash3048


The present work was carried out on Pseudomonasaeruginosa and Staphylococcus aureus which are involved

in food spoilage and food poisoning The purpose of the

current work was to study the effect of growth temperature

on bacterial adhesion to stainless steel and polycarbonate

two surfaces frequently used in food processing equipment

Adhesion assays were performed under static conditions at

20uC In order to characterize the mechanisms of bacterial

adhesion cell surface properties were studied using contact

angle measurements (CAMs) and microbial adhesion to

organic solvent (MATS) In addition CAMs and atomic

force microscopy (AFM) were used to study the surface

properties and topography of both stainless steel and

polycarbonate respectively CAM outcomes were also used

to predict bacterial adhesion using the LW-AB and the

XDLVO theories Subsequently empirical adhesion data of

bacteria cultivated on surfaces at different temperatures (20

30 and 37uC) were compared with theoretical predictions

This study aimed to unravel the relationship between

environmental factors and bacterial adhesion to surfaces

This data contributes to the understanding of and therefore

prevention of bacterial adhesion to surfaces and subsequent

biofilm formation

MATERIALS AND METHODS

Bacterial strains and culture conditions The bacterial

strains used for this study were P aeruginosa CIP 103467 and Saureus CIP 483 The strains were stored at 280uC in tryptic soy

broth (TSB Biokar Diagnostics Pantin France) containing 40

(volvol) glycerol To prepare precultures 100 ml from frozen stock

cultures was inoculated into 5 ml of TSB and then incubated at the

culture temperature (ie 20 30 or 37uC) The preculture at 20uCwas incubated for 48 h whereas those at 30 and 37uC were

incubated for 24 h The cultures used in each experiment were then

prepared by inoculating 5 | 104 CFUml from the preculture

broths into 50 ml of TSB in sterile 500-ml flasks Cultures were

incubated under shaking (160 rpm) at 20 30 or 37uC and were

stopped at the late exponential phase

Bacterial standardization and cell inoculum preparationP aeruginosa and S aureus grown at 20 30 and 37uC as described

previously were harvested by centrifugation for 10 min at 3500 | g(20uC) Bacteria were washed twice with 20 ml of 100 mM

potassium phosphate buffer (PB pH 7) and finally were resuspended

in 20 ml of PB The cells were dispersed by sonication at 37 kHz for

5 min at 25uC (Elmasonic S60H Elma Singen Germany)

Subsequently bacteria were resuspended in the PB to a cell

concentration of 1 | 108 CFUml by adjusting the optical density

to OD620 nm ~ 0110 iexcl 0005 (108 CFUml) using an Ultrospec

1100 pro UV-visible light spectrophotometer (GE Healthcare

Waukesha WI) Standardized cell suspensions were diluted 10-fold

for use in the bacterial adhesion assays (107 CFUml)

Slide preparation and adhesion assays The stainless steel

and polycarbonate surfaces were cleaned by soaking in ethanol

95 (Fluka Sigma-Aldrich St Louis MO) overnight to remove

grease Next slides were rinsed in water and soaked in 500 ml of

TDF4 detergent (5 Franklab SA Billancourt France) for 20 min

at 50uC under agitation The slides were then thoroughly rinsed

five times for 1 min with agitation in 500 ml of distilled water at

room temperature to eliminate detergent followed by three washes

with ultrapure water (Milli-Q Academic Millipore Molsheim

France) The clean stainless steel slides were air dried and sterilized

by autoclaving at 121uC for 15 min Polycarbonate slides were

sterilized for 10 min with absolute ethanol (Fluka Sigma-Aldrich)

The sterile slides were placed in a horizontal position in petri

dishes The upper face of each slide was covered with 3 ml of cell

inoculum (107 CFUml) and incubated statically at 20uC for 60 min

for the bacterial adhesion assays After attachment the coupons

were removed using sterile forceps and were rinsed by gentle

dipping into 30 ml of PB to remove excess liquid droplets and

loosely attached cells Cells were then stained for 10 min in the

dark using acridine orange stain 001 (wtvol) followed by

gentle dipping in 30 ml of ultrapure water The attached cells were

quantified using epifluorescence microscopy (Nikon Optiphot-2

EFD3 Nikon Inc Melville NY) A total of 50 fields per coupon

were scanned and the fluorescent cells were enumerated Counts

were presented as number of bacteria in the microscopy field The

results present the average of three independent experiments and

two coupons were studied for each experiment

CAMs The contact angles of the bacterial cell surfaces were

measured using the sessile drop method Bacterial suspensions

prepared as described above were adjusted to an OD620 nm of 10

using either PB or ultrapure water To evaluate the cell surface

hydrophobicity and hydrophilicity cells harvested by centrifuga-

tion were washed once with ultrapure water and were resuspended

in the same water to an OD620 nm of 10 The cells suspended in

ultrapure water or PB were vacuum filtered through a 045-mm-

pore-size nitrocellulose membrane filter (type HA Millipore

Bedford MA) to create a bacterial lawn The bacterial cell filters

were attached to glass slides using double-sided adhesive tape and

were dried for 30 min at 37uC The contact angles of water

diiodomethane and formamide were measured immediately

after drop deposition on the bacterial lawn with a digital camera

using WinDrop software (20uC) (Digidrop goniometer GBX-

Instruments France) At least five drops of each probe liquid were

deposited onto each filter For stainless steel and polycarbonate

surfaces five drops of the probe liquid were also measured CAM

results present the average of the measurements taken on three

independently bacterial or solid surfaces

MATS The MATS method described by Bellon-Fontaine

et al (3) based on the comparison of microbial cell affinity to both

monopolar and apolar solvents was used to determine the

hydrophobicity and the electron donor (basic) or acceptor (acidic)

properties of microbial cells Experimentally bacteria were

suspended to an optical density of 09 at 405 nm (A0)

(approximately 108 CFUml cell density) in 100 mM PB A

volume (24 ml) of each bacterial suspension was vortexed for 90 s

with 04 ml of solvent The mixture was allowed to stand for 15 min

to ensure complete separation of the two phases The optical

density of the water phase was then measured using a

spectrophotometer The affinity of cells for each solvent was

subsequently calculated by the following equation

Affinity~ 1 A=A0eth THORNfrac12 eth1THORNwhere A0 is the absorbance measured at 405 nm of the bacterial

suspension before mixing and A is the absorbance after mixing

The following pairs of solvents as described by Bellon-Fontaine

et al (3) were used chloroform (an electron acceptor solvent)

hexadecane (a nonpolar solvent) ethyl acetate (an electron donor

solvent) and decane (a nonpolar solvent) Owing to the similar LW

components of the surface tension in each pair of solvents

differences between the affinities to solvents would indicate the

electron donor and electron acceptor character of the bacterial































cos h~1z2


S cLWl

qcl

z


S cl

pcl

z


S czl

pcl

0

1A eth2THORN





cLWl cz



surfaces cLWS cz


b czb and c

b )




peth3THORN


surface tension






DGtotadh~DGLW






DGLWadh~2


b

q


l


Sl

q


l

q eth5THORN

DGABadh~2


b czS


b cS

p


b czl

q


b cl

p


S czl


S cl

p eth6THORN






et al (1)



Bos et al (4)

DGLW deth THORN~A

6


dz2r

d

eth8THORN



equation 7 (4)
















S

|

2fbfs

f2bzf2

S

ln1ze kdeth THORN

1e kdeth THORN


h i( )eth11THORN










RESULTS








(Table 1)





















































temperatureTA

BL

E1

B

acte

rial

and

subs

trat

umsu

rfac

ech

arac

teri

stic

sa

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

f

Pse

udom

onas

aeru

gino

sa2

05

87

iexcl2

85

13

iexcl1

36

41

iexcl0

62

93

iexcl1

65

21

iexcl2

60

2iexcl

01

69

iexcl1

83

71

iexcl2

02

12

1iexcl

10

30

55

7iexcl

12

30

1iexcl

15

29

3iexcl

20

30

9iexcl

07

46

4iexcl

31

22

iexcl0

51

99

iexcl1

75

08

iexcl1

12

13

4iexcl

08

37

45

6iexcl

06

29

8iexcl

14

18

2iexcl

22

36

7iexcl

04

41

3iexcl

11

21

iexcl0

21

84

iexcl1

15

51

iexcl0

82

14

2iexcl

12

Stap

hylo

cocc

usau

reus

20

42

5iexcl

15

60

7iexcl

18

60

9iexcl

16

38

5iexcl

08

34

2iexcl

16

05

iexcl0

28

4iexcl

16

46

9iexcl

10

21

69

iexcl0

6

30

50

9iexcl

28

50

4iexcl

24

61

4iexcl

24

34

7iexcl

08

51

4iexcl

31

05

iexcl0

39

8iexcl

31

43

2iexcl

19

21

42

iexcl0

7

37

59

7iexcl

15

54

9iexcl

15

76

5iexcl

11

28

5iexcl

05

64

3iexcl

17

26

iexcl0

32

57

iexcl1

95

42

iexcl2

32

93

iexcl1

6

Sta

inle

ssst

eel

50

9iexcl

17

60

6iexcl

21

33

8iexcl

04

33

7iexcl

09

11

8iexcl

21

38

iexcl0

61

33

iexcl1

24

71

iexcl0

32

40

5iexcl

07

Poly

carb

onat

e555

iexcl2

37

93

iexcl1

43

35

iexcl0

24

33

iexcl0

57

2iexcl

06

01

iexcl0

11

1iexcl

07

43

4iexcl

05

21

85

iexcl1

3

aIm

mer

sed

in1

00

mM

ph

osp

hat

eb

uff

er(P

B

pH

7)

T

bac

teri

alg

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ents

(in

deg

rees

)o

nla

wn

so

fb

acte

rial

cell

san

dsu

bst

rata

imm

erse

din

PB

c

LW

c

zc

2

andc

AB

the

van

der

Waa

ls

elec

tro

nac

cep

tor

elec

tro

nd

on

or

and

po

lar

com

po

nen

tso

fsu

rfac

ete

nsi

on

(c

mJ

m2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

PB

and

sub

stra

ta

imm

erse

din

the

sam

eb

uff

erf

the

zeta

po

ten

tial

(mV

)o

fb

acte

rial

and

sub

stra

tasu

rfac

es
























to 37uC (Table 3)







2F)



















































adhDGtot

adh DGLWadh DGAB

adhDGtot

adh























































37uC (Table 4)










respectivelyTA

BL

E3

C

ell

surf

ace

hydr

opho

bici

tyor

hydr

ophi

lici

tyac

cord

ing

toth

eth

erm

odyn

amic

theo

rya

Bac

teri

um

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

DG

SW

S

Pse

udom

onas

aeru

gino

sa2

06

02

iexcl0

75

47

iexcl0

36

77

iexcl0

52

85

iexcl0

45

01

iexcl1

00

4iexcl

01

90

9iexcl

11

37

6iexcl

15

34

9iexcl

06

30

57

0iexcl

06

35

3iexcl

08

33

2iexcl

05

30

3iexcl

04

43

7iexcl

11

20

iexcl0

21

86

8iexcl

08

49

0iexcl

04

20

8iexcl

12

37

44

0iexcl

07

32

5iexcl

08

18

4iexcl

08

37

5iexcl

03

38

6iexcl

09

20

iexcl0

11

75

5iexcl

03

55

1iexcl

02

12

6iexcl

10

Stap

hylo

cocc

usau

reus

20

42

4iexcl

16

62

7iexcl

06

62

6iexcl

05

38

4iexcl

08

30

6iexcl

15

05

iexcl0

18

21

iexcl1

04

66

iexcl1

63

6iexcl

18

30

50

9iexcl

06

52

9iexcl

03

59

8iexcl

12

33

8iexcl

03

43

7iexcl

20

02

iexcl0

15

71

iexcl2

03

95

iexcl2

22

62

iexcl1

5

37

58

9iexcl

10

54

4iexcl

09

72

4iexcl

07

29

2iexcl

06

57

6iexcl

17

14

iexcl0

11

79

iexcl0

84

71

iexcl1

13

82

iexcl1

7

aT

g

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ent

(deg

rees

)o

nla

wn

so

fb

acte

rial

cell

ssu

spen

ded

inw

ater

c

LW

cz

c

2

andc

AB

th

ev

and

erW

aals

el

ectr

on

acce

pto

rel

ectr

on

do

no

ran

dp

ola

rco

mp

on

ents

of

surf

ace

ten

sio

n(c

m

Jm

2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

wat

erD

GS

WS

the

free

ener

gy

of

coh

esio

n(m

Jm

2)

bet

wee

ntw

oid

enti

cal

surf

aces

imm

erse

din

wat

er


DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York











































cos h~1z2


S cLWl

qcl

z


S cl

pcl

z


S czl

pcl

0

1A eth2THORN





cLWl cz



surfaces cLWS cz


b czb and c

b )




peth3THORN


surface tension






DGtotadh~DGLW






DGLWadh~2


b

q


l


Sl

q


l

q eth5THORN

DGABadh~2


b czS


b cS

p


b czl

q


b cl

p


S czl


S cl

p eth6THORN






et al (1)



Bos et al (4)

DGLW deth THORN~A

6


dz2r

d

eth8THORN



equation 7 (4)
















S

|

2fbfs

f2bzf2

S

ln1ze kdeth THORN

1e kdeth THORN


h i( )eth11THORN










RESULTS








(Table 1)





















































temperatureTA

BL

E1

B

acte

rial

and

subs

trat

umsu

rfac

ech

arac

teri

stic

sa

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

f

Pse

udom

onas

aeru

gino

sa2

05

87

iexcl2

85

13

iexcl1

36

41

iexcl0

62

93

iexcl1

65

21

iexcl2

60

2iexcl

01

69

iexcl1

83

71

iexcl2

02

12

1iexcl

10

30

55

7iexcl

12

30

1iexcl

15

29

3iexcl

20

30

9iexcl

07

46

4iexcl

31

22

iexcl0

51

99

iexcl1

75

08

iexcl1

12

13

4iexcl

08

37

45

6iexcl

06

29

8iexcl

14

18

2iexcl

22

36

7iexcl

04

41

3iexcl

11

21

iexcl0

21

84

iexcl1

15

51

iexcl0

82

14

2iexcl

12

Stap

hylo

cocc

usau

reus

20

42

5iexcl

15

60

7iexcl

18

60

9iexcl

16

38

5iexcl

08

34

2iexcl

16

05

iexcl0

28

4iexcl

16

46

9iexcl

10

21

69

iexcl0

6

30

50

9iexcl

28

50

4iexcl

24

61

4iexcl

24

34

7iexcl

08

51

4iexcl

31

05

iexcl0

39

8iexcl

31

43

2iexcl

19

21

42

iexcl0

7

37

59

7iexcl

15

54

9iexcl

15

76

5iexcl

11

28

5iexcl

05

64

3iexcl

17

26

iexcl0

32

57

iexcl1

95

42

iexcl2

32

93

iexcl1

6

Sta

inle

ssst

eel

50

9iexcl

17

60

6iexcl

21

33

8iexcl

04

33

7iexcl

09

11

8iexcl

21

38

iexcl0

61

33

iexcl1

24

71

iexcl0

32

40

5iexcl

07

Poly

carb

onat

e555

iexcl2

37

93

iexcl1

43

35

iexcl0

24

33

iexcl0

57

2iexcl

06

01

iexcl0

11

1iexcl

07

43

4iexcl

05

21

85

iexcl1

3

aIm

mer

sed

in1

00

mM

ph

osp

hat

eb

uff

er(P

B

pH

7)

T

bac

teri

alg

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ents

(in

deg

rees

)o

nla

wn

so

fb

acte

rial

cell

san

dsu

bst

rata

imm

erse

din

PB

c

LW

c

zc

2

andc

AB

the

van

der

Waa

ls

elec

tro

nac

cep

tor

elec

tro

nd

on

or

and

po

lar

com

po

nen

tso

fsu

rfac

ete

nsi

on

(c

mJ

m2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

PB

and

sub

stra

ta

imm

erse

din

the

sam

eb

uff

erf

the

zeta

po

ten

tial

(mV

)o

fb

acte

rial

and

sub

stra

tasu

rfac

es
























to 37uC (Table 3)







2F)



















































adhDGtot

adh DGLWadh DGAB

adhDGtot

adh























































37uC (Table 4)










respectivelyTA

BL

E3

C

ell

surf

ace

hydr

opho

bici

tyor

hydr

ophi

lici

tyac

cord

ing

toth

eth

erm

odyn

amic

theo

rya

Bac

teri

um

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

DG

SW

S

Pse

udom

onas

aeru

gino

sa2

06

02

iexcl0

75

47

iexcl0

36

77

iexcl0

52

85

iexcl0

45

01

iexcl1

00

4iexcl

01

90

9iexcl

11

37

6iexcl

15

34

9iexcl

06

30

57

0iexcl

06

35

3iexcl

08

33

2iexcl

05

30

3iexcl

04

43

7iexcl

11

20

iexcl0

21

86

8iexcl

08

49

0iexcl

04

20

8iexcl

12

37

44

0iexcl

07

32

5iexcl

08

18

4iexcl

08

37

5iexcl

03

38

6iexcl

09

20

iexcl0

11

75

5iexcl

03

55

1iexcl

02

12

6iexcl

10

Stap

hylo

cocc

usau

reus

20

42

4iexcl

16

62

7iexcl

06

62

6iexcl

05

38

4iexcl

08

30

6iexcl

15

05

iexcl0

18

21

iexcl1

04

66

iexcl1

63

6iexcl

18

30

50

9iexcl

06

52

9iexcl

03

59

8iexcl

12

33

8iexcl

03

43

7iexcl

20

02

iexcl0

15

71

iexcl2

03

95

iexcl2

22

62

iexcl1

5

37

58

9iexcl

10

54

4iexcl

09

72

4iexcl

07

29

2iexcl

06

57

6iexcl

17

14

iexcl0

11

79

iexcl0

84

71

iexcl1

13

82

iexcl1

7

aT

g

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ent

(deg

rees

)o

nla

wn

so

fb

acte

rial

cell

ssu

spen

ded

inw

ater

c

LW

cz

c

2

andc

AB

th

ev

and

erW

aals

el

ectr

on

acce

pto

rel

ectr

on

do

no

ran

dp

ola

rco

mp

on

ents

of

surf

ace

ten

sio

n(c

m

Jm

2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

wat

erD

GS

WS

the

free

ener

gy

of

coh

esio

n(m

Jm

2)

bet

wee

ntw

oid

enti

cal

surf

aces

imm

erse

din

wat

er


DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York

































































temperatureTA

BL

E1

B

acte

rial

and

subs

trat

umsu

rfac

ech

arac

teri

stic

sa

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

f

Pse

udom

onas

aeru

gino

sa2

05

87

iexcl2

85

13

iexcl1

36

41

iexcl0

62

93

iexcl1

65

21

iexcl2

60

2iexcl

01

69

iexcl1

83

71

iexcl2

02

12

1iexcl

10

30

55

7iexcl

12

30

1iexcl

15

29

3iexcl

20

30

9iexcl

07

46

4iexcl

31

22

iexcl0

51

99

iexcl1

75

08

iexcl1

12

13

4iexcl

08

37

45

6iexcl

06

29

8iexcl

14

18

2iexcl

22

36

7iexcl

04

41

3iexcl

11

21

iexcl0

21

84

iexcl1

15

51

iexcl0

82

14

2iexcl

12

Stap

hylo

cocc

usau

reus

20

42

5iexcl

15

60

7iexcl

18

60

9iexcl

16

38

5iexcl

08

34

2iexcl

16

05

iexcl0

28

4iexcl

16

46

9iexcl

10

21

69

iexcl0

6

30

50

9iexcl

28

50

4iexcl

24

61

4iexcl

24

34

7iexcl

08

51

4iexcl

31

05

iexcl0

39

8iexcl

31

43

2iexcl

19

21

42

iexcl0

7

37

59

7iexcl

15

54

9iexcl

15

76

5iexcl

11

28

5iexcl

05

64

3iexcl

17

26

iexcl0

32

57

iexcl1

95

42

iexcl2

32

93

iexcl1

6

Sta

inle

ssst

eel

50

9iexcl

17

60

6iexcl

21

33

8iexcl

04

33

7iexcl

09

11

8iexcl

21

38

iexcl0

61

33

iexcl1

24

71

iexcl0

32

40

5iexcl

07

Poly

carb

onat

e555

iexcl2

37

93

iexcl1

43

35

iexcl0

24

33

iexcl0

57

2iexcl

06

01

iexcl0

11

1iexcl

07

43

4iexcl

05

21

85

iexcl1

3

aIm

mer

sed

in1

00

mM

ph

osp

hat

eb

uff

er(P

B

pH

7)

T

bac

teri

alg

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ents

(in

deg

rees

)o

nla

wn

so

fb

acte

rial

cell

san

dsu

bst

rata

imm

erse

din

PB

c

LW

c

zc

2

andc

AB

the

van

der

Waa

ls

elec

tro

nac

cep

tor

elec

tro

nd

on

or

and

po

lar

com

po

nen

tso

fsu

rfac

ete

nsi

on

(c

mJ

m2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

PB

and

sub

stra

ta

imm

erse

din

the

sam

eb

uff

erf

the

zeta

po

ten

tial

(mV

)o

fb

acte

rial

and

sub

stra

tasu

rfac

es
























to 37uC (Table 3)







2F)



















































adhDGtot

adh DGLWadh DGAB

adhDGtot

adh























































37uC (Table 4)










respectivelyTA

BL

E3

C

ell

surf

ace

hydr

opho

bici

tyor

hydr

ophi

lici

tyac

cord

ing

toth

eth

erm

odyn

amic

theo

rya

Bac

teri

um

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

DG

SW

S

Pse

udom

onas

aeru

gino

sa2

06

02

iexcl0

75

47

iexcl0

36

77

iexcl0

52

85

iexcl0

45

01

iexcl1

00

4iexcl

01

90

9iexcl

11

37

6iexcl

15

34

9iexcl

06

30

57

0iexcl

06

35

3iexcl

08

33

2iexcl

05

30

3iexcl

04

43

7iexcl

11

20

iexcl0

21

86

8iexcl

08

49

0iexcl

04

20

8iexcl

12

37

44

0iexcl

07

32

5iexcl

08

18

4iexcl

08

37

5iexcl

03

38

6iexcl

09

20

iexcl0

11

75

5iexcl

03

55

1iexcl

02

12

6iexcl

10

Stap

hylo

cocc

usau

reus

20

42

4iexcl

16

62

7iexcl

06

62

6iexcl

05

38

4iexcl

08

30

6iexcl

15

05

iexcl0

18

21

iexcl1

04

66

iexcl1

63

6iexcl

18

30

50

9iexcl

06

52

9iexcl

03

59

8iexcl

12

33

8iexcl

03

43

7iexcl

20

02

iexcl0

15

71

iexcl2

03

95

iexcl2

22

62

iexcl1

5

37

58

9iexcl

10

54

4iexcl

09

72

4iexcl

07

29

2iexcl

06

57

6iexcl

17

14

iexcl0

11

79

iexcl0

84

71

iexcl1

13

82

iexcl1

7

aT

g

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ent

(deg

rees

)o

nla

wn

so

fb

acte

rial

cell

ssu

spen

ded

inw

ater

c

LW

cz

c

2

andc

AB

th

ev

and

erW

aals

el

ectr

on

acce

pto

rel

ectr

on

do

no

ran

dp

ola

rco

mp

on

ents

of

surf

ace

ten

sio

n(c

m

Jm

2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

wat

erD

GS

WS

the

free

ener

gy

of

coh

esio

n(m

Jm

2)

bet

wee

ntw

oid

enti

cal

surf

aces

imm

erse

din

wat

er


DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York




































to 37uC (Table 3)







2F)



















































adhDGtot

adh DGLWadh DGAB

adhDGtot

adh























































37uC (Table 4)










respectivelyTA

BL

E3

C

ell

surf

ace

hydr

opho

bici

tyor

hydr

ophi

lici

tyac

cord

ing

toth

eth

erm

odyn

amic

theo

rya

Bac

teri

um

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

DG

SW

S

Pse

udom

onas

aeru

gino

sa2

06

02

iexcl0

75

47

iexcl0

36

77

iexcl0

52

85

iexcl0

45

01

iexcl1

00

4iexcl

01

90

9iexcl

11

37

6iexcl

15

34

9iexcl

06

30

57

0iexcl

06

35

3iexcl

08

33

2iexcl

05

30

3iexcl

04

43

7iexcl

11

20

iexcl0

21

86

8iexcl

08

49

0iexcl

04

20

8iexcl

12

37

44

0iexcl

07

32

5iexcl

08

18

4iexcl

08

37

5iexcl

03

38

6iexcl

09

20

iexcl0

11

75

5iexcl

03

55

1iexcl

02

12

6iexcl

10

Stap

hylo

cocc

usau

reus

20

42

4iexcl

16

62

7iexcl

06

62

6iexcl

05

38

4iexcl

08

30

6iexcl

15

05

iexcl0

18

21

iexcl1

04

66

iexcl1

63

6iexcl

18

30

50

9iexcl

06

52

9iexcl

03

59

8iexcl

12

33

8iexcl

03

43

7iexcl

20

02

iexcl0

15

71

iexcl2

03

95

iexcl2

22

62

iexcl1

5

37

58

9iexcl

10

54

4iexcl

09

72

4iexcl

07

29

2iexcl

06

57

6iexcl

17

14

iexcl0

11

79

iexcl0

84

71

iexcl1

13

82

iexcl1

7

aT

g

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ent

(deg

rees

)o

nla

wn

so

fb

acte

rial

cell

ssu

spen

ded

inw

ater

c

LW

cz

c

2

andc

AB

th

ev

and

erW

aals

el

ectr

on

acce

pto

rel

ectr

on

do

no

ran

dp

ola

rco

mp

on

ents

of

surf

ace

ten

sio

n(c

m

Jm

2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

wat

erD

GS

WS

the

free

ener

gy

of

coh

esio

n(m

Jm

2)

bet

wee

ntw

oid

enti

cal

surf

aces

imm

erse

din

wat

er


DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York
























































37uC (Table 4)










respectivelyTA

BL

E3

C

ell

surf

ace

hydr

opho

bici

tyor

hydr

ophi

lici

tyac

cord

ing

toth

eth

erm

odyn

amic

theo

rya

Bac

teri

um

T(u

C)

hd

hW

hF

cL

Wc

2cz

cA

Bc

DG

SW

S

Pse

udom

onas

aeru

gino

sa2

06

02

iexcl0

75

47

iexcl0

36

77

iexcl0

52

85

iexcl0

45

01

iexcl1

00

4iexcl

01

90

9iexcl

11

37

6iexcl

15

34

9iexcl

06

30

57

0iexcl

06

35

3iexcl

08

33

2iexcl

05

30

3iexcl

04

43

7iexcl

11

20

iexcl0

21

86

8iexcl

08

49

0iexcl

04

20

8iexcl

12

37

44

0iexcl

07

32

5iexcl

08

18

4iexcl

08

37

5iexcl

03

38

6iexcl

09

20

iexcl0

11

75

5iexcl

03

55

1iexcl

02

12

6iexcl

10

Stap

hylo

cocc

usau

reus

20

42

4iexcl

16

62

7iexcl

06

62

6iexcl

05

38

4iexcl

08

30

6iexcl

15

05

iexcl0

18

21

iexcl1

04

66

iexcl1

63

6iexcl

18

30

50

9iexcl

06

52

9iexcl

03

59

8iexcl

12

33

8iexcl

03

43

7iexcl

20

02

iexcl0

15

71

iexcl2

03

95

iexcl2

22

62

iexcl1

5

37

58

9iexcl

10

54

4iexcl

09

72

4iexcl

07

29

2iexcl

06

57

6iexcl

17

14

iexcl0

11

79

iexcl0

84

71

iexcl1

13

82

iexcl1

7

aT

g

row

thte

mp

erat

ure

h

dh

F

andh

W

con

tact

ang

lem

easu

rem

ent

(deg

rees

)o

nla

wn

so

fb

acte

rial

cell

ssu

spen

ded

inw

ater

c

LW

cz

c

2

andc

AB

th

ev

and

erW

aals

el

ectr

on

acce

pto

rel

ectr

on

do

no

ran

dp

ola

rco

mp

on

ents

of

surf

ace

ten

sio

n(c

m

Jm

2)

resp

ecti

vel

y

of

bac

teri

alce

lls

susp

end

edin

wat

erD

GS

WS

the

free

ener

gy

of

coh

esio

n(m

Jm

2)

bet

wee

ntw

oid

enti

cal

surf

aces

imm

erse

din

wat

er


DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York














DISCUSSION
















abiotic surfaces









































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York

































bacterium











































































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York














































































to abiotic surfaces

ACKNOWLEDGMENTS




REFERENCES









































1973ndash85























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York
























988

























58268ndash273











2682







2921ndash38













202ndash219



M194ndashM199







Dekker New York














thermodynamic prediction of growth temperature dependence in the adhesion of pseudomonas aeruginosa...

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