types of culture media

media for bacterial growth

1. TYPES OF CULTURE MEDIA I . Based on consistency a)solid media b)liquid media c)semi solid media II . Based on constituents a) simple media b)complex media c)synthetic media

2. III . Special media a)enriched media b)Enrichment media c)selective media d)indicator media e)differential media f)sugar media g)transport media IV . Based on oxygen requirement a) Aerobic media b) Anerobic media

3. Physical state : Liquid media Solid media semi solid media LIQUID MEDIA : Ex : nutrient broth Generally it is carried in tubes , bottles, flask In liquid media , bacteria grow uniformly produces turbidity No agar added Inoculum are prepared SOLID MEDIA : Ex: nutrient agar Agar plate is a petri dish contain 2% of agar Agar is solidifying agent SEMI SOLID MEDIA Useful for demonstrating bacteria motility Ex : hugh & lefison’s oxidation fermentation

4. Based upon nutrient components : SIMPLE MEDIA : also known as BASAL MEDIA It supports mostly non fastidious bacteria Ex: nutrient broth , nutrient agar – peptone , yeast extract & Nacl when 2% of agar is added to nutrient broth and nutrient agar COMPLEX MEDIA : other than basal media are called complwx media Special ingredients are required for growth of bacteria Ex : yeast and casein SYNTHETIC MEDIA : It is used for research purpose Composition of every is well known It is generally prepared from pure chemical substances Ex : peptone water

5. Based upon functional group ENRICHED MEDIA : This media is for fastidious microorganisms It includes like blood , serum , egg to basal media Ex : blood agar ( streptococcus ) chocolate agar ( nessiaria )

6. ENRICHMENT MEDIA : In this media nutrients are adjusted in such away that it inhibits the growth of unwanted bacteria But permits required bacteria to grow It is liquid media Ex : tetrathionate broth – for the isolation of salmonella selenite broth – to inhibit coliforms alkaline peptone water – for vibrio cholera

7. SELECTIVE MEDIA : It is same as enrichment media but it exists in solid form In this media nutrients are adjusted in such away that it inhibits the growth of unwanted bacteria in the form of colonies Here physical conditions are included such as temperature , pH , gaseous requirements are adjusted and made selective for growth of specific micro organisms Ex : Mac Conkey’s media – gram negative bacteria

8. INDICATOR MEDIA : In this media contains indicator which changes color when bacterial species grow in them Ex : Wilson and blair medium :- Salmonella typhi reduces sulphite to sulphate in the presence of glucose ( black metallic shine colonies )

9. DIFFERENTIAL MEDIA : It distinguish between different types of bacteria based on some characteristic reaction towards medium like hemolysis or biochemical reactions So, that bacteria utilizes them appear as differently colored colonies which can be distinguished from each other Ex : Mac Conkey’s media It is designed to grow gram negative bacteria and differentiate them for lactose fermentation . Lactose fermenters – pink colonies Non lactose fermenters – colorless colonies

10. SUGAR MEDIA : In this we use 1% sugar + peptone water with suitable indicator In this DURHAM’S tube is used it is kept inverted in the tube containing medium to detech gas production Fermentation is carried out which is important for identification of micro organisms

11. TRANSPORT MEDIA : Media derived specially for transport of delicate micro organisms Ex : Nessieria gonorrhoeae ( this may not survive the time takes it may overgrow non pathogen e.coli and pathogens like salmonella sp & shigella Ex : stuart’s transport medium , amines transport media

12. IV . Based on oxygen requirement : AERBOIC MEDIA : used for growing aerobic organisms Ex : Mac conkeys broth ANEROBIC MEDIA : Use for growing anaerobic organisms ex : thioglycolate broth