Question

Clostridium buttercup does not appear to have superoxide dismisses (SOD) and catalase enzymes. How would growth of C. Butyricum in oxic conditions compare to its growth in anoxic conditions? On this basis what is aerotolerance category of C. Butyricum?

Answer 1

• Inside cell or within the intracellular fluid, electrons are shuttled within different carrier molecules or electro transporters.
• If these electron carriers come in vicinity or contact to oxygen, electrons may be transferred to oxygen molecule, making reactive oxygen.
• Oxygen may be converted to dangerous substances like superoxide, hydrogen peroxides, which are toxic to the cells or organelles.
• Also, hydrogen peroxides may be converted by free iron ions in intracellular fluids, to hydroxyl radicals that can damage and mutate DNA.
• Catalase and superoxide dismutase enzymes act as protective factors against oxidative damages, and thus is indispensable in aerobic organisms, cells and organelles with oxygen abundancies, like peroxisomes, mitochondria.
• Obligate anaerobes like genus of Clostridium, lack these enzymes and cannot survive in oxygenic condition.
• However certain strains of Clostridium are considered aerotolerant.
• Butyric acid strains of Clostridium like Clostridium butyricum can survive in presence of oxygen, as well as absorb oxygen.
• These bacteria can absorb oxygen in its lag phase or prior to developmental phase.
• Oxygen consumption by these bacteria, are also observed post addition of NADPH/ NADH, due to presence of NAD(P) oxidases.