1. Write the names of these 9 possible bacteria under the correct group: Escheri

Question

1. Write the names of these 9 possible bacteria under the correct group: Escherichia coli, Staphylococcus epidermidis, Staphylococcus aureus, Proteus vulgaris, Shigella flexneri, Enterococcus faecalis, Micrococcus uteus, Serratia marcescens, Salmonella typhimurium Gram Bacillus 2. How do you determine if bacteria are catalase (+) or ()? 3. For the Gram (+) Coccus bacteria, list which are Catalase(+) and which are Catalase Catalase (+ Catalase (- 4. How do you determine if bacteria are Sulfur reducers or not? 5. For the Gram (-) Bacillus bacteria, list which are+) for Sulfur Reduction and which are (-). Sulfur Reduction(+) Sulfur Reduction 6. How do you determine if bacteria are Indole (+) or (-)? 7. For the Gram (-) Bacillus bacteria, determine which are Indole (+) and which are Indole (-). Indole (+) Indole

Explanation / Answer

Ans 1)

Gram(+) Coccus – Staphyloccus Epidermis, Staphylococcus aureus, Enterococcus faecalis, Micrococcus luteus,

Gram (-) Bacillus – Escherichia Coli, Proteus Vulgaris, Shigella flexneri, Serratia marcescens, Salmonella Typhimurium

Ans 2) Due to the production of the catalase it leads to rapid degradation of the hydrogen peroxide. It can be determined by adding hydrogen peroxide to an incubated TSA slant culture. If there is catalase, it will create bubbles due to free oxygen gas and if it is catalase negative, no bubbles will be formed.

Ans 3) Staphyloccus Epidermis, Staphylococcus aureus and Micrococcus luteus is catalase (+) and Enterococcus faecalis is catalase (-).

Ans 4) The sulphur reducing bacteria is able to reduce the sulfates to sulfides and we can know if the bacteria is sulphur reducer or not by finding its mode of energy use. The reducers use sulphur as their primary source of energy.

Ans 5) Escherichia Coli, Serratia marcescens and Salmonella Typhimurium are (+) sulphur reducing and Proteus Vulgaris, Shigella flexneri is (-) sulphur reducing.

Ans 6) Indole test is to determine if an organism is able to split the amino acid or not. The Indole(+) test is when the indole is cleaved from tryptophan on addition of five drops of Kovac’s reagent ad it shows red or red-violet color. The negative result shows yellow color.

Ans 7) Escherichia Coli, Proteus Vulgaris and Salmonella Typhimurium are Indole (+) while Shigella flexneri, Serratia marcescens is indole (-) negative.

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