Nutrient Media Second Lab PDF

What are nutrient media? Culture which are designed to provide all the essential nutrients in solution for bacterial growth. The general composition of a medium is as follows: H-donors and acceptors, C-source, N-source, Other inorganic nutrients e.g. S, P, Trace elements , Growth fa...

What are nutrient media? Culture which are designed to provide all the essential nutrients in solution for bacterial growth. The general composition of a medium is as follows: H-donors and acceptors, C-source, N-source, Other inorganic nutrients e.g. S, P, Trace elements , Growth factors (amino acids, purines, pyrimidines, vitamins) Solidifying agent (e.g. agar), Buffer chemicals dissolved in a Solvent (usually distilled water).  Nutrient media Uses 1. Enrichement of microbial cultures.. 2. Studying different characteristics of microorganisms 3. Studying the effect of microbial growth on media components. 4. Production of importance end products such as Amino acids Alcohols Antibiotics Organic acids Enzymes 2 Media Types  Depending on its composition Synthetic Routine Defined media These are classified into six types: (1) Basal media, These are chemically defined (2) Enriched media, media prepared from pure (3) Selective media, chemical substances. It is used in (4) Indicator media, research work. (5) Transport media, (6) Storage media.  Depending on its constancy Solid media Liquid media It has a solid state at room It has a liquid state at room temperature. Solid media is used for temperature.. It is used for profuse the isolation of bacteria as pure growth, e.g. blood culture in liquid culture. 'Agar' is most commonly used media. Mixed organisms cannot be to prepare solid media. separated. ROUTINE LABORATORY MEDIA 1- Basal media It is used for: growth (culture) of bacteria that do not need enrichment of the media. Examples: Nutrient broth, nutrient agar and peptone water. Staphylococcus and Enterobacteriaceae grow in these media. 2- ENRICHED MEDIA are enriched usually by adding blood, serum or egg. Examples: Enriched media are blood agar. Streptococci grow in blood agar media. 3- SELECTIVE MEDIA These media favour the growth of a particular bacterium by inhibiting the growth of all undesired bacteria and allowing growth of only desirable bacteria. Examples: MacConkey agar, tellurite media (Tellurite inhibits the growth of most of the throat organisms except diphtheria bacilli). Antibiotic may be added to a medium for inhibition. 4- INDICATOR (DIFFERENTIAL) MEDIA An indicator is included in the medium to support the growth of more than one microbial group. A particular organism causes change in the indicator, e.g. blood, neutral red, tellurite. Examples: Blood agar and MacConkey agar are indicator media. 5- TRANSPORT MEDIA These media are used when specie-men cannot be cultured soon after collection. Examples: Cary-Blair medium, Amies medium, Stuart medium. 6- STORAGE MEDIA Media used for storing the bacteria for a long period of time. Examples: Egg saline medium, chalk cooked meat broth.