Fish Microbiology and Quality Assurance (2+2)

8. Catalase test

This test is useful in differentiating certain groups of bacteria based on their ability to grow in presence of oxygen. Most aerobes and facultative anaerobes during aerobic respiration produce hydrogen peroxide which is extremely toxic to their enzyme systems. But organisms producing catalase rapidly degrade hydrogen peroxide to oxygen and water enabling their survival.

Procedure
To the trypicase soy agar slants containing test culture, a few drops of 3% hydrogen peroxide is added covering the culture surface and observed for release of free oxygen as bubbles or effervescence. Absence of effervescence is negative for catalse.