makalah micro
TRANSCRIPT
9/1/2009
GROWTH MEDIUM- selective media growth -
- -2nd Group:
à Erwin A. P. (10) à Masrifa I. I. (12)
à Rio H. D. C. (24) à Shinta K. (26)
à Trimah W. (30) à Yeni A. (34)
SMK NEGERI 1 (STM PEMBANGUNAN) TEMANGGUNGPROGRAM KEAHLIAN TEKNIK KIMIA
Jl. Kadar Maron, Kotak Pos 104, Phone (0293)4901639 Temanggung 56221
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CONTENTS
COVER PAGE …………………………………………………………………… i
CONTENTS ………………………………………………………………………ii
I. GROWTH MEDIA …………………………………………………………1
1. The Meaning of a Growth Media ………………………………………………1
2. The Types Growth Media………………………………………………………2
3. The Table of Growth Media ……………………………………………………3
II. SELECTIVE MEDIA GROWTH …………………………………………4
1. The Definition …………………………………………………………………4
2. The Funtion of Selective Medium……………………………………………...4
3. Some Examples of Selective Media ……………………………………………5
4. Some Pictures of Selective Media ……………………………………………7
SOURCE …………………………………………………………………………8
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GROWTH MEDIA
1. The Meaning of a Growth Media
A growth medium or culture medium is
a liquid or gel designed to support the growth of microorganisms or cells, or small
plants like the moss Physcomitrella patens
a mixture of nutrients, moisture and other chemicals that bacteria need for growth
in a laboratory environment.
An Agar Plate -- an example of a bacterial growth
medium. Specifically, it is a streak plate; the orange lines
and dots are formed by bacterial colonies.
This invention relates to media which support the
growth of some microbes but are designed to inhibit the growth of other types of microbes
for culturing microbes in a sample containing a mixture of species. Such media are termed
selective media. This invention comprises a novel type of selective media. The preferred
embodiment provides a selective media for the detection of target Salmonella species,
which allows Salmonella species to survive and grow whilst inhibiting the growth of many
other commensal bacteria.
Media can be solid, such as Jell-o-like agar that is poured into the bottom half of a
Petri dish, or media can be liquid to allow for bacterial growth suspended in test tubes.
Media aren’t used to examine individual bacteria, but rather to grow bacterial colonies
There are two major types of growth media: those used for cell culture, which use
specific cell types derived from plants or animals, and microbiological culture, which are
used for growing microorganisms, such as bacteria or yeast. The most common growth
media for microorganisms are nutrient broths and agar plates; specialized media are
sometimes required for microorganism and cell culture growth. Some organisms, termed
fastidious organisms, require specialized environments due to complex nutritional
requirements. Viruses, for example, are obligate intracellular parasites and require a
growth medium composed of living cells.
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2. The Types Growth Media
The most common growth media for microorganisms are nutrient broths (liquid
nutrient medium) or Luria Bertani medium (LB medium or Lysogeny Broth). Liquid media
are often mixed with agar and poured into petri dishes to solidify. These agar plates
provide a solid medium on which microbes may be cultured. They remain solid, as very
few bacteria are able to decompose agar. Bacteria grown in liquid cultures often form
colloidal suspensions.
The differences between growth media used for cell culture and those used for
microbiological culture are because cells derived from whole organisms and grown in
culture often cannot grow without the addition of, for instance, hormones or growth factors
which usually occur in vivo.[4] In the case of animal cells, this difficulty is often addressed
by the addition of blood serum to the medium. In the case of microorganisms, there are no
such limitations, as they are often unicellular organisms. One other major difference is that
animal cells in culture are often grown on a flat surface to which they attach, and the
medium is provided in a liquid form, which covers the cells. In contrast, bacteria such as
Escherichia coli may be grown on solid media or in liquid media.
An important distinction between growth media types is that of defined versus
undefined media. A defined medium will have known quantities of all ingredients. For
microorganisms, they consist of providing trace elements and vitamins required by the
microbe and especially a defined carbon source and nitrogen source. Glucose or glycerol
are often used as carbon sources, and ammonium salts or nitrates as inorganic nitrogen
sources. An undefined medium has some complex ingredients, such as yeast extract or
casein hydrolysate, which consist of a mixture of many, many chemical species in
unknown proportions. Undefined media are sometimes chosen based on price and
sometimes by necessity - some microorganisms have never been cultured on defined
media.
A good example of a growth medium is the wort used to make beer. The wort contains
all the nutrients required for yeast growth, and under anaerobic conditions, alcohol is
produced. When the fermentation process is complete, the combination of medium and
dormant microbes, now beer, is ready for consumption.
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3. The Table of Growth Media
GROWTH MEDIA / AGAR PLATES
Selective media
Gram
positive
ActinobacteriaMycobacterium tuberculosis (Lowenstein-Jensen medium) ·
Mycoplasma pneumoniae (Eaton's agar)
Firmicutes
Corynebacterium diphtheriae (Hoyle's agar) · Enterococcus (Bile
esculin agar) · Lactobacillus (MRS agar) · Staphylococcus
(Mannitol salt agar)
Gram
negative
Alphaproteobacteria Brucella abortus (Brucella agar)
Betaproteobacteria Neisseria (Thayer-Martin agar)
Gammaproteobacteria
Bordetella (Bordet-Gengou agar) · Enterobacteriaceae (VRBD
agar) · Haemophilus influenzae/Legionella pneumophila
(Buffered charcoal yeast extract agar) · Pseudomonas aeruginosa
(Cetrimide agar) · Salmonella (XLT agar) · DCA agar ·
Salmonella/Shigella (XLD agar)
Differential media
Lactose fermenting gram negative (MacConkey agar/Sorbitol-MacConkey agar, Eosin methylene blue) ·
Hektoen enteric agar · sulfur (Bismuth sulfite agar)
Fungal media
Dermatophyte test medium · Potato dextrose agar · Sabouraud agar
Nonselective media
Chocolate agar · Nutrient agar · Plate count agar
Other/ un-grouped media
Cysteine lactose electrolyte deficient agar · Cystine tryptic agar · Endo agar · Müller-Hinton agar/PNP
agar · R2a agar · Simmons' citrate agar · Trypticase soy agar · TSI agar
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SELECTIVE MEDIA GROWTH
1. The Definition
A growth medium is selective if it allows only certain types of bacteria to grow, while
inhibiting the growth of others.
For example, if a microorganism is resistant to a certain antibiotic, such as ampicillin
or tetracycline, then that antibiotic can be added to the medium in order to prevent other
cells, which do not possess the resistance, from growing. Media lacking an amino acid
such as proline in conjunction with E. coli unable to synthesize it were commonly used by
geneticists before the emergence of genomics to map bacterial chromosomes.
2. The Funtion of Selective Medium
Selective media are used for:
support the growth of some microbes but are designed to inhibit the growth of other
types of microbes for culturing microbes in a sample containing a mixture of species.
providing general information regarding the bacteria that are able to grow on these
specialized types of agar.
For example, organisms that can utilize a given sugar are easily screened by making
that sugar the only carbon source in the medium. On the other hand, selective inhibition of
some types of microorganisms can be achieved by adding dyes, antibiotics, salts or specific
inhibitors which affect the metabolism or enzyme systems of the organisms.
Another example, media containing potassium tellurite, sodium azide or thallium
acetate (at concentrations of 0.1 - 0.5 g/l) will inhibit the growth of Gram-negative
bacteria. Media supplemented with penicillin (5-50 units/ml) or crystal violet (2 mg/l) will
inhibit the growth of Gram-positive bacteria. Tellurite agar, therefore, is used to select for
Gram-positive organisms, and nutrient agar supplemented with penicillin can be used to
select for Gram-negative organisms.
Selective growth media are also used in cell culture to ensure the survival or
proliferation of cells with certain properties, such as antibiotic resistance or the ability to
synthesize a certain metabolite. Normally, the presence of a specific gene or an allele of a
gene confers upon the cell the ability to grow in the selective medium. In such cases, the
gene is termed a marker.
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Selective growth media for eukaryotic cells commonly contain neomycin to select
cells that have been successfully transfected with a plasmid carrying the neomycin
resistance gene as a marker. Gancyclovir is an exception to the rule as it is used to
specifically kill cells that carry its respective marker, the Herpes simplex virus thymidine
kinase (HSV TK).
3. Some Examples of Selective Media
Some examples of selective media include:
a) Eosin-Methylene Blue Agar (EMB)
This agar medium is both selective and differential. The combination of the two dyes
eosin and methylene blue inhibits most Gram positive bacteria but allows many Gram
negative organisms to grow.
In addition to peptones, EMB contains lactose (it may also contain sucrose). Gram
negative bacteria that ferment the lactose produce acid which turns the colonies dark
purple as the acid acts upon the dyes. In addition, certain lactose-fermenting bacteria
produce flat, dark colonies with a green metallic sheen. Other lactose fermenters produce
larger, mucoid colonies, often purple only in their center. Lactose non-fermenters are either
colorless or light lavender.
b) YM (Yeast And Mold)
A medium that promotes the growth of fungi (yeast and molds) which has a low pH,
deterring bacterial growth.
c) Blood Agar (Used In Strep Tests)
Which contains bouvine heart blood that becomes transparent in the presence of
hemolytic Streptococcus.
d) MacConkey’s Agar (MAC)
MacConkey's agar is a differential plating medium selective for Gram negative
organisms, used primarily for detection and isolation of enteric bacteria (dysentery,
typhoid and paratyphoid organisms). It is generally used for differentiating strains of
Salmonella typhosa from members of the coliform group; however, the medium supports
the growth of all Salmonella and Shigella strains and gives good differentiation between
these enteric pathogens and the coliform group.
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When grown on MacConkey’s medium, The growth of gram-positive organisms are
generally inhibited by crystal violet in the medium and bile salts in the medium. Isolated
colonies of lactose-fermenting bacteria are brick-red in color and are surrounded by a zone
of precipitated bile. These reactions are due to the acids, produced by the fermentation of
lactose, upon bile salts present in the medium, and subsequent absorption of neutral red.
The acid end-products act on bile salts, and neutral red is absorbed by the precipitated
salts. Dysentery, typhoid and paratyphoid bacilli do not ferment lactose but give an
alkaline reaction when grown on the medium. Colonies of these organisms are noncolored
and transparent.
e) Hektoen Enteric Agar (HE)
Which is selective for Gram-negative bacteria.
f) Mannitol Salt Agar (MSA)
This is a selective medium that favors the growth of pathogenic staphylococci and for
differentiation between pathogenic and non-pathogenic types, which is selective for gram-
positive bacteria and differential for mannitol.
The medium contains the sugar-alcohol mannitol, a phenol red indicator, and 7.5%
sodium chloride (NaCl). The staphylococci are characteristically able to tolerate this high
salt concentration. The high salt concentration inhibits the growth of most bacteria other
than staphylococci. Generally pathogenic staphylococci are able to ferment the mannitol,
lowering the pH, and thereby turning the indicator yellow. The non-pathogenic
staphylococci do not ferment mannitol and the medium remains pink in their vicinity.
On MSA, pathogenic Staphylococcus aureus produces small colonies surrounded by
yellow zones. The reason for this change in color is that S. aureus ferments the mannitol,
producing an acid, which, in turn, changes the indicator from red to yellow. The growth of
other types of bacteria is generally inhibited.
g) Terrific Broth (Tb)
Is used with glycerol in cultivating recombinant strains of Escherichia coli.
h) Xylose Lysine Desoxyscholate (XLD)
Which is selective for Gram-negative bacteria.
i) Buffered Charcoal Yeast Extract Agar
Which is selective for certain gram-negative bacteria, especially Legionella
pneumophila.
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4. Some Pictures of Selective Media
Four types of agar plates demonstrating
differential growth depending on bacterial
metabolism.
Blood-free, charcoal-based selective
medium agar (CSM) for isolation of
Campylobacter.
Blood agar plates are often used
to diagnose infection. On the
right is a positive Streptococcus
culture; on the left a positive
Staphylococcus culture.
Selective Bacterial Media Top
Two (MAC and MSA)
Mannitol Salt Agar: Yellow Side
Pathogenic Staph
Gram- Bacteria Growing on
MacConkey's Agar
Pink Lactose Fermenters on
MacConkeys
Mannitol Salt Agar with Staph
epi and aureus
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SOURCES
http://www.toodoc.com
http://www.wikipedia.com
http://fire.biol.wwu.edu/brodham/biol346_s07/labman_week6.pdf
http://www.suite101.com
http://www.googletranslator.com
http://biosci.usc.edu/courses/2002-fall/documents/bisc300-lab_media.pdf
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