PYRUVATE METABOLISM IN CAMPYLOBACTER SPP

The metabolism of pyruvate by Campylobacter spp. was investigated empl oying one- and two-dimensional H-1, C-13 and P-31 nuclear magnetic res onance spectroscopy. Metabolically competent cells incubated aerobical ly with pyruvate yielded acetate, acetolactate, alanine, formate, lact ate, and succinate. The production of acetolactate, alanine and lactat e indicated the presence of acetohydroxy acid synthase, alanine transa minase and lactate dehydrogenase activities, respectively. Accumulatio n of acetate and formate as metabolic products provided evidence for t he existence of a mixed acid fermentation pathway in the microorganism . Formation of succinate suggested the incorporation of the pyruvate c arbon skeleton to the Kreb's cycle, and the observation of pyruvate de hydrogenase activities in bacterial lysates supported this interpretat ion. Generation of pyruvate from L-serine in incubations with intact c ells and lysates indicated the presence of serine dehydratase activity in the bacterium. Pyruvate was also formed in cell suspensions and ly sates from phosphoenol pyruvate. The existence of anaplerotic sequence s involving phosphoenol pyruvate carboxykinase and a malic enzyme were established in bacterial lysates. The activities of enzymes involved in the biosynthesis of isoleucine and valine were measured. Addition o f pyruvate to different solid culture media inhibited bacterial growth , and the inhibition was attributed to the accumulation of acetate and formate. The variety of products formed using pyruvate as the sole su bstrate and the existence of anaplerotic sequences and anabolic pathwa ys which employ pyruvate, showed the important role of this metabolite in the energy and biosynthesis metabolism of Campylobacter spp.