Culture Media&

Culture Methods

Presented byJunaid Gabol

Need for Culture Media

• Medium• Nutrient • Support growthBacteria mixed population in natureBy appropriate procedures they have to be

grown separately (isolated) on culture media and obtained as pure culture study

Liquid medium Two type of culture medium Solid medium

Liquid & Solid Medium

• Liquid MediumDiffused growthNo characteristics for identificationDifficult to isolate

• Solid MediumDistinct colony morphologyCharacteristics___ easy to identifyColony___ microscopically visible collection of millions of bacteria originating

from a single bacteria cell

Types of Culture Media

• Simple Medium • Complex Medium• Synthetic Medium• Special Medium(Enriched Media, Enrichment Media, Selective

Media, Indicator Media, Differential Media, Sugar Media)• Based on oxygen requirement Aerobic Media

Anaerobic Media

Types of Culture Media

• Simple Media (Most common in routine tests, e.g. Nutrient Broth, Nutrient Agar)Consists of peptone, Meat extract, NaCl, Water, 0.5% Glucose, 2% Agar

• Complex MediaThey have added complex ingredients such as yeast extract, casein

hydrolysate provide special nutrients

• Synthetic Media Media prepaid from pure chemical substances Used for special studies e.g. metabolic requirementse.g. peptone water (1% peptone+0.5% NaCl in water)

Types of Culture Media

• Enriched MediaSubstances like blood, serum, egg are added to the basal medium.Used to grow bacteria that are exacting in their nutritional needs e.g. Blood Agar Chocolate

Agar.

• Enrichment Media Liquid media used to isolate pathogens from a mixed culture.Inhibit growth of unwanted bacterium increase in numbers of desired bacteria

• Selective MediaThe inhibitory substances is added to a solid mediaIncrease in number of colonies of desired bacterium e.g. Mac Conkey’s Medium ( for gram negative bacteria)Lj Medium ( for M.tuberculosis)

Types of Culture Media

• Indicator MediaContain an indicator which changes its color when a bacterium grows in them

• Differential Media Distinguish between lactose fermenters and non lactose fermenters bacteria's e.g. Mac Conkey’s Medium

• Sugar Media Media containing any fermentable substances e.g. glucose, arabinose, lactose, starch etc1% of the sugar in peptone water+ indicatorContain a small tube(Durham’s tube) for the detection of gas by the bacteria

Types of Culture Media

• Anaerobic bacteria These bacteria are used to grow anaerobic organisms.

Culture Methods include:Streak cultureLawn culturestroke cultureStab culturePour plate methodLiquid cultureAnaerobic culture methods

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