Ž . Biochimica et Biophysica Acta 1334 1997 291–302 Pyruvate metabolism in Campylobacter spp. George L. Mendz a, ) , Graham E. Ball b , David J. Meek a a School of Biochemistry and Molecular Genetics, The UniÕersity of New South Wales, Sydney, N.S.W. 2052, Australia b School of Chemistry, The UniÕersity of New South Wales, Sydney, N.S.W. 2052, Australia Received 18 September 1996; accepted 26 September 1996 Abstract The metabolism of pyruvate by Campylobacter spp. was investigated employing one- and two-dimensional 1 H, 13 C and 31 P nuclear magnetic resonance spectroscopy. Metabolically competent cells incubated aerobically with pyruvate yielded acetate, acetolactate, alanine, formate, lactate, and succinate. The production of acetolactate, alanine and lactate indicated the presence of acetohydroxy acid synthase, alanine transaminase and lactate dehydrogenase activities, respectively. Accumulation of acetate and formate as metabolic products provided evidence for the existence of a mixed acid fermentation pathway in the microorganism. Formation of succinate suggested the incorporation of the pyruvate carbon skeleton to the Kreb’s cycle, and the observation of pyruvate dehydrogenase activities in bacterial lysates supported this interpretation. Generation of pyruvate from L-serine in incubations with intact cells and lysates indicated the presence of serine dehydratase activity in the bacterium. Pyruvate was also formed in cell suspensions and lysates from phosphoenol pyruvate. The existence of anaplerotic sequences 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 of 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 substrate and the existence of anaplerotic sequences and anabolic pathways which employ pyruvate, showed the important role of this metabolite in the energy and biosynthesis metabolism of Campylobacter spp. Ž . Keywords: Pyruvate metabolism; NMR spectroscopy; Anaplerotic sequence; Campylobacter spp. 1. Introduction The genus Campylobacter comprises Gram-nega- tive, microaerophilic, vibrioid bacteria commonly found in the gut. Species such as C. coli and C. jejuni are found asymptomatically in farm animals and poultry, but they produce enteritis in humans w x 1,2 . Other species are pathogenic to animals, e.g., C. fetus is a cause of abortion in sheep and abortion w x and infertility in cattle 3,4 ; and C. hyointestinalis ) Corresponding author. Fax: q61 2 3851483; E-mail: g.mendz@unsw.edu.au and C. hyoilei cause proliferative gastritis in pigs w x 5,6 . Many aspects of the metabolism of this impor- tant group of microorganisms remain largely un- known. Since the sources of carbon and energy em- ployed by the organism have not been identified fully w x 7–10 , investigation of the intermediary metabolism of Campylobacter spp. will contribute to understand- ing the ways in which these bacteria store and gener- ate energy and use it in the biosynthesis of low molecular weight metabolites. Pyruvate is a major metabolic junction linking carbohydrate or amino acid utilization to energy gen- eration and biosynthetic pathways. Several amino 0304-4165r97r$17.00 Copyright q 1997 Elsevier Science B.V. All rights reserved. Ž . PII S0304-4165 96 00107-9