Effects of carbon dioxide on germination of Clostridium botulinum spores

Abstract

Clostridium botulinum is a Gram -positive, strict anaerobic, rod -shaped, spore -forming, SOD -positive and catalase -negative bacterium. Its antioxidant defenses are not suited to chronic oxidative stress. H₂O₂ and reactive oxygen species have deleterious effects on C. botulinum. Spore germination is one of the key steps in its development. However, the mechanisms that trigger this germination have yet to be described. To manage C. botulinum growth, it is essential to understand the mechanisms that underlie the germination process. In this article, a series of complementary cascade reactions with water -dissolved CO₂ as an initiating germinant, and bicarbonate is suggested. It seems clear that ATP production is achieved through the use of various anaplerotic reactions with dissolved CO₂ as the carbon source. In addition to the production of oxaloacetate, an intermediate metabolite pyruvate would also be synthesized. Pyruvate would initiate the second phase of germination by producing hydrogen, which is a powerful reducing agent, via two enzymes (pyruvate -ferredoxin oxidoreductase and ferredoxin hydrogenase). These conditions would activate proteolytic enzymes and would reduce and would break the disulfide bridges of the proteins that make up the spore coats, thereby opening them. Thus, the phosphoenolpyruvate -pyruvate -acetyl -CoA pathway, in the presence of CO₂, would play a major role in the germination of spores of C. botulinum.