Question

2.What is the basis of the catalase test?

a.How do you identify a facultative anaerobe from an aerotolerant anaerobe using this test?

Answer 1

QUESTION- 2.What is the basis of the catalase test?

  

SOLUTION- Catalase is an enzyme which breaks hydrogen per oxide (a potent oxidizing agent) to water and Oxygen.

2H2O2 CATALASE→ 2H2 + O2 (Gas bubble)

This reaction use as principle for identifying catalase producing bacteria (Staphylococcus, Enterics etc) and non-catalase (Streptococcus) producing bacteria. A small amount of inoculums is introduced to a test tube containing H2O2 if air bubble comes out, that means inoculums containing bacteria is catalase positive if no air bubble then non-catalse producing bacteria. As H2O2 is a potent oxidising agent it harms to organism, to prevent that organism breaks H2O2 to water and oxygen.

QUESTION-   a.How do you identify a facultative anaerobe from an aerotolerant anaerobe using this test?

SOLUTION- Facultative anaerobes- Example- Enterics. In general facultative anaerobes is catalase positive because they are the species those oxygen not require for growth but utilize when oxygen available, that means they have the mechanism of transforming oxidising agent like hydrogen per oxide, so it produce gas bubbles.

            In other hand aerotolerant anaerobes like Streptococci, for them oxygen are not require and they do not utilized also, so there is no question of mechanism require to neutralize hydrogen per oxide, no formation of oxygen and finally no air bubble.

CONCLUSION- Facultative anaerobes- Catalse positive.

                                   Aerotolerant anaerobes- Catalase negative.