Types of media &Requirements

Prepared by:

Maryam Abdulwahid

Hawar HarjisHedi Hameed

Supervised by:Dr.Vian

Subjects included;• Cultivation• Medium• Inoculation of media• The Requirements for

Growth• Preparation• Classification• Eplanation of types of media

functionally.

Cultivation;

The propagation of living organisms, applied especially to the growth of microorganisms or other cells in artificial media.

Medium Any preparation that contains nutrients essential for microorganisms growth. Culture medium: A nutrient substance that is used to grow micro-organisms .

Inoculation of media Introduction of infected material to the medium ,for cultivation of organisms.

Agar Is Complex polysaccharide, Used as solidifying agent for culture media in Petri plates, slants, and deeps. Generally not metabolized by microbes Liquefies at 100°C Solidifies at ~40°C

The Requirements for Growth

1.CHEMICAL REQUIREMENTS (NUTRITIONAL FACTORS) • Carbon • Nitrogen, sulfur, and phosphorous • Trace elements • Organic growth factor • Vitamins (e.g. folic acid, vitamin B-12,

vitamin K) • Oxygen

2.PHYSICAL REQUIREMENTS

• Temperature • PH • Hydrostatic Pressure • Osmotic pressure

Preparation• Wash hands & wear gloves • Sterilize all equipments • Pour D/W in glassware (required

amount) • Add powder ingredients (required

amount) • Heat to dissolve completely • Autoclave • Dispense the medium into

tubes ,bottles &plates

• Store at required temperature • Sterilizing Culture Media

Classification 1. Consistency 2. Nutritional 3. Functional

1.Consistency

a ) Solid e.g nutrient agar

b ) Semi-solid e.g peptone water.

c ) Liquid medium e.g nutrient broth.

2.Nutritional

b ) Complex e.g blood agar a ) Simple e.g peptone water

c ) Synthetic e.g Davis /mingioli medium

3.Functional

a) Basic media b) Selective media c ) Differential media d ) Enriched media e ) Enrichment media f ) Transport media

Basic media• This is an undefined medium

because the amino acid source contains a variety of compounds with the exact composition being unknown.

• Nutrient media contain all the elements that most bacteria need for growth and are non-selective, so they are used for the general cultivation and maintenance of bacteria kept in laboratory culture collections.

Basic media

• This media contains; 1.A carbon source such as glucose for

bacterial growth 2.Water 3.Various salts needed for bacterial

growth

1. nutrient broth which is liquid media

There are two types:

2. nutrient agar which is solid media

Selective media• culture medium that allows the

growth of certain types of organisms, while inhibiting the growth of other organisms

• Any agar media can be made selective by addition of certain inhibitory agents that

don’t affect the pathogen.• Various approaches to make a

medium selective include addition ofantibiotics, dyes, chemicals, alteration of pH or a combination of these medium

Selective media• Thiosulphate citrate bile salt

sucrose (TCBS) which is selective for Vibrio cholerae

• MacConkey agar contain bile salt which is selective for Enterobacteriaceae

Differential media

• distinguishs one microorganism type from another based on a difference in colony appearance includes (color, shape, or growth pattern) on the media.

• uses the biochemical characteristics of a microorganism growing in the presence of specific nutrients or indicators (such as neutral red, phenol red , or methylene blue) added to the medium to visibly indicate the defining characteristics of a microorganism.

Differential media

• is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria.

• Examples; Mannitol salt agar Eosin methylene blue MacConkey agar

• Mannitol salt agar which is differential for mannitol fermentation Like Staphylococcus aureus change the color of agar from pink to yellow

• Eosin methylene blue which is differential for lactose and sucrose fermentation

• MacConkey agar which is differential for lactose fermentation Ex:

E.coli From non lactose fermentersEx:

salmonella,shigella

Enriched media

• Enriched with Blood,serum,extrapeptones,egg& vitamins

• Used for: cultivation of all fastidious

organisms, (haemophilus

influenza&Streptococcus spp.)• Examples:• Blood agar &chocolate agar

1.agar powders

2.Weighing out the ingredients 

3.Measuring the desired volume of water for the medium

4.Adding the contentstobottle

5.Autoclaving

6.Adding blood to blood agar base medium

7.Mixing the blood with molten medium at 45 c 8.Pouring

plates

9.Laying out plates to set

Preparation of bloodmedia

Chocolate agar

• Originally, red blood cells were added to a melted nutrient base and heated to approximately 75°C which lysed the red blood cells

 

fastidious respiratory bacteria, such as Haemophilus influenzae need growth factors, like NAD and hemin, which are inside red blood cells; thus, a prerequisite to growth is lysis of the red blood cells. The agar is named for the color and contains no actual chocolate.

Enrichment media• A liquid culture medium promotes

the growth of a particular organism and prevent the growth of normal competitors.

• Prevent non pathogenic bacteria from overgrowing the pathogenic bacteria

• Example: selenite-Fbroth alkaline-peptone water

• Intended Use :is used for the selective enrichment of Salmonella spp.

• Prepared Appearance: Prepared medium is clear, with no to light precipitate and very pale yellow.

SELENITE –F BROTH

ALKALINE PEPTONE WATER

• Intended use: is used for the enrichment of Vibrio

cholera and Vibrio species from food, water, feces and clinical studies.

• Prepared appearance: The color is amber

Transport media• Preserve viability and ratio of

microbes during its transportation over 24_48 hours.

• Example: CARY-BLAIR MEDIUMSTUART TRANSPORT MEDIUM

CARY-BLAIR MEDIUM• Intended use; • for the collection and transport of fecal and

rectal samples, maintaining viability of Salmonella and Shigella.

• Survival depends upon: 1. bacterial type &concentration , transport

medium formulation, transport temperature and duration.

• the color is white opalescent

• Intended use: is a semisolid medium used in the

transport and preservation of specimens for the cultivation of diverse organisms such as gonococci, streptococci, Enterobacteria

The color : is blue in surface.

STUART TRANSPORT MEDIUM

http://www.condalab.com/pdf/1518.pdfhttp://www.condalab.com/pdf/1529.pdfhttp://www.neogen.com/Acumedia/pdf/ProdInfo/7155_PI.pdfhttp://www.condalab.com/pdf/1407.pdfhttp://www.neogen.com/Acumedia/pdf/ProdInfo/7102_PI.pdf

REFERENCES

Thank you