Question

yo isolate an organism from a wound abscess on a patient using thioglycollate and find it is growing equally throughout the tube. upon completion of a catalase test you observe slow steady bubbling upon the addition of hydrogen peroxide. what is the oxygen classification of the organism and explain how you came to that conclusion.

Answer 1

Answer: An aerotolerant anaerobe

Step-by-step explanation:

Thioglycolate is utilized then differential media for determining oxygen requirements of microorganisms. In this experiment the organisms are equally spread throughout the medium this means that they don’t need oxygen for energy metabolism (as the final electron acceptor). Furthermore, these organisms are not poisoned by oxygen, because they are present equally throughout and never surface of the medium. Thus they are all aerotolerant anaerobes. These organisms produce energy in the form of ATP via the fermentation process; while they do not require oxygen, they can readily protect themselves from damage by reactive oxygen species. This protection is usually via detoxification pathways that include superoxide dismutase found in most organisms; and peroxidase found in only some organisms. Both catalyze hydrogen peroxide’s breakdown into gaseous oxygen and water.

Furthermore, in the catalase tests a solution of hydrogen peroxide is added to a bacterial suspension. A positive result is typically the production of oxygen bubbles as effervescence; in this experiment,
`H_(2)O_(2)`'s decomposition was slow, thus this does not count as a positive result- other organisms make enzymes other than catalase which can break down
`H_(2)O_(2)`.