Question

why obligate anerobe die in the prescence of oxygen

Answer 1

Obligate anaerobes are those microorganisms which can not survive in the presence of oxygen but can generate ATP and grow well in the absence of oxygen. They die in presence of oxygen because they lack some defense mechanism which aerobic microorganisms' posses when they react with oxygen present in air it gets converted into superoxide ion which then forms H2O2 when superoxide ion reacts with water.H2O2 is highly reactive and cause real damages to the cell. In the case of aerobic microorganisms, they contain catalase, peroxidase, and superoxide dismutase. Catalase prevents the formation of H2O2.On the other hand, superoxide dismutase prevents the formation of oxygen radicals which is formed by oxidation of superoxide ion and prevents the cell from oxidative damage of oxygen radicals. That is why aerobic microorganisms survive in the presence of oxygen because they have peroxidases, catalase, and superoxide dismutase.