What happens on the catalase test?

Answer 1

Catalse Test Catalase (also known as peroxidase) is an enzyme that catalyses the breakdown of hydrogen peroxide to oxygen and water. Most higher organisms produce catalase, but in bacteriology this test is usually used to differentiate staphylococci (Catalase positive) from streptococci (Catalase negative). Chemical equation for the breakdown of hydrogen peroxide:2H2O2 → 2H2O + O2 In this test a drop of hydrogen peroxide is emulsified with the bacterial growth, if the organism is catalase positive active bubbling is seen (formation of oxygen) In catalase negative reactions no active bubbling is seen

Answer 2

ome bacteria contain flavoproteins that reduce oxygen (O2), resulting in the production of hydrogen peroxide (H2O2) and, in some cases, an extremely toxic superoxide (O2-). Accumulation of these substances will result in death of the organism as they are powerful oxidizing agents and destroy cellular constituents very rapidly unless they can be enzymatically degraded. These substances are produced when aerobes, facultative anaerobes, and microaerophiles use the aerobic respiratory pathway, in which oxygen is the final electron acceptor, during degradation of carbohydrates for energy production.

A bacterium must be able to protect itself against such O2 products or it will be killed. Many bacteria possess enzymes that afford protection against toxic O2 products. Facultative anaerobes and Obligate aerobes usually contain the enzymes superoxide dismutase, which has the ability to catalyze the destruction of superoxide, and either catalase or peroxidase, which catalyze the destruction of hydrogen peroxide as follows:

The inability of strict anaerobes to synthesize catalase, peroxidase, or superoxide dismutase may explain why oxygen is poisonous to these microorganisms. In the absence of these enzymes, the toxic concentration of H2O2 cannot be degraded when these organisms are cultivated in the presence of oxygen.

Organisms capable of producing catalase rapidly degrade hydrogen peroxide which is a tetramer containing four polypeptide chains, which are usually 500 amino acids long. It also contains four porphyrin heme groups(ie., iron groups) that will allow the enzyme to react with the hydrogen peroxide.

The enzyme catalase is present in most cytochrome-containing aerobic and facultative anaerobic bacteria. Catalase is the enzyme which has one of the highest turnover numbers compared to all other enzymes; one molecule of catalase has the ability to convert millions of molecules of hydrogen peroxide to water and oxygen in each second.

Catalase production and activity can be detected by adding the substrate H2O2 to an appropriately incubated (18- to 24-hour) tryptic soy agar slant culture. Organisms which produce the enzyme break down the hydrogen peroxide, and the resulting O2 production produces bubbles in the reagent drop, indicating a positive test. Organisms lacking the cytochrome system also lack the catalase enzyme and are unable to break down hydrogen peroxide, into O2 and water and are catalase negative.

Catalase activity is very useful in differentiating between groups of bacteria. For example, the morphologically similar Enterococcus(catalase negative) and Staphylococcus(catalase positive) can be differentiated using the catalase test

Answer 3

To determine whether the bacterial species has cytochrome C in its electron transport chain hence enabling it to utilise the oxygen and thus creating energy.

Answer 4

Well, first you must find a lazy cat...