Culture Media LAB 3 A L NOOR AMEER

Culture Media LAB. 3 A. L. NOOR AMEER

consist of nutrients which support the growth and multiplication of bacteria. Any medium for the cultivation of bacteria must provide certain basic nutritional requirements, which include: 1 - A carbon source that may also serve as an energy source. 2 - Water 3 - A nitrogen source 4 - A phosphate source 5 - Various mineral nutrient such as iron and magnesium

Pure culture: culture consists of medium containing the growth of a single species of microorganisms. Mixed culture: culture consists of medium containing the growth of 2 or more species of M. O.

Agar: Is a complex carbohydrate extracted from sea weed Gelidium an ideal solidifying agent for microbiological media because of : 1 - It has melting properties (solid agar melts at 90 -100 Co , liquid agar solidified at about 42 Co) 2 - Because it has no nutritive value for majority of bacteria.

Kinds of culture media: A) According to their consistency: 1 - Broth or liquid media: without solidifying agent (agar), used for inoculums preparation, profuse growth and blood culture for example: nutrient broth (N. b. ) 2 - Solid media: contain (2 -3% agar). Used for colony morphology, isolation of bacteria as a pure culture or for pigmentation For ex. Nutrient agar. 3 - Semi-solid media: as the solid media but the proportion of agar is 0. 5 %. Such motility medium.

B) According to their constituent / ingredient 1 - Natural media: (non- synthetic media): is a medium whose exact concentration of ingredients is not known, ex. Milk, blood. 2 - Defined media : ( synthetic media): it’s a media that exact chemical composition is known, this medium consisting of a single carbon source (glucose), A nitrogen source (ammonium salts) and inorganic salts (phosphate). 3 - Semi -synthetic media: composed of synthetic medium with natural substances, for ex. Nutrient agar with blood = blood agar.

4 - Living media: consist of living tissue, used for growing viruses and cancer cells for ex. Tissue culture and Volunteers. 5 - Enrichment media: it’s a medium that consist of specific substances were added to basic medium such as blood, plasma, egg, yeast extract to support the growth of fastidious type of microorganism , ex: blood agar , chocolate agar.

6 - Selective media: allows the growth of certain type of microorganisms, while inhibiting the growth of other types. for ex. (Mac. Conkey agar). 7 - Differential media: permit the recognition of specific types of M. O. that grow on the same medium, for ex. (Mac. Conkey agar). 8 - Transport media: used for transporting the samples, ex: Stuart’s medium.