GROWTH CHARACTERUSTICS

1-      For biochemical differentiation activity of amino acid Decarboxylase, pattern of carbohydrate fermentation and other enzymes are used.

2-      Indole production from Tryptophan is also used in rapid identification.

3-      Production of Acetylmethylcarbinol from dextrose which is termed as Voges-Proskauer reaction is less used.

4-      Lactose fermenting and non lactose fermenting enteric bacteria are differentiating by growing them on “diferrential” media which contains special dyes and carbohydrates. Examples are

a)      Eosin-methylene blue (EMB)

b)      MacConkey agar

c)      Deoxycholate media

5-      Triple Sugar Iron (TSI) media is a complex media which used in the differentiation between Salmonellae and Shigellae in stool culture.

TSI contains 0.1% Glucose, 1% Sucrose, 1% Lactose, Ferrous Sulfate, Tissue extract and pH indicator.

6-      Ferrous sulfate is used for detection H2S production.

7-      Tissue extract is protein growth substrate.

8-      Phenol red is used as ph indicator.

TSI poured in test tube by making a slant with deep but and bacterial growth inoculated stabbing into butt. In initial stage butt and slant turn yellow due to fermentation of glucose and acid production. When co2 and h2o produced in the result of oxidation of fermentation products and amines are formed from Decarboxylation protein slant turns to alkaline (red). Due to production of much acid from the fermentation of lactose and sucrose fermentation slant and butt remains yellow. Salmonellae and Shigellae yield an acid butt and alkaline butt. (Monica2000)