Question

Please answer 1-4

1 Discuss some difficulties one might encounter in differentiating bacteria on the basis of physiological tests 2. Hopefully, you noticed all the reminders to incubate the test tubes with loose Gaps. Why is this important? 3. How would you determine whether an organism can ferment other carbohydrates, such as mannitol? 4. What enzymes are involved in the following reactions: Urea hydrolysis- Hydrogen sulfide production- Casein hydrolysis- Indole production- Catalase-

Answer 1

1, Physiological tests is used to identify bacteria based on the biochemical characters and enzyme production which is a traditional method of identification where dozens of tests are done.

the difficulties one could face while differentiating bacteria accprding to physiological tests are

1, False results due to contamination

2, Improper method of performing the tests can also result in false negative

3, One should perform many tests inorder to find few differences in between 2 bacteria.

2, generally the caps are left loose inorder to maintain aerobic environment inside the tubes

3, We are suppose to inoculate the culture in to a basal media which has one carbohydrate like say mannitol and a acid base indicator- phenol red. If the bacteria ferments the provided carbohydrate, the media will change acidic indicated by the yellow colour change of phenol red.

4. Urea hdrolysis- urease enzyme (It splits the urea molecule in the media into carbon dioxide and ammonia)

H2S production-   cysteine desulfurase (reduction of sulphur to H2S)

casein production- caseinase (breaks casein into amino acids )

Indole- tryphtophanase

Catalase- catalase enzyme (breaks H2O2 into H2O and O2)