Aerobic and anaerobic respiratory systems in Campylobacter fetus subsp. jejuni grown in atmospheres containing hydrogen

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Abstract
Maximum growth of C. fetus ssp. jejuni, strain C-61, occurred when the cultures were incubated with shaking in atmospheres containing .apprx. 30% H2, 5% O2 and 10% CO2. Suspensions of cells grown under these conditions consumed O2 with formate as the substrate in the presence of 0.33 mM cyanide, which completely inhibited respiration with ascorbate-N,N,N'',N''-tetramethyl-p-phenylenediamine and with lactate. Spectroscopic evidence with intact cells suggested that a form of cytochrome c, reducible with formate but not with lactate or ascorbate-N,N,N'',N''-tetramethyl-p-phenylenediamine, can be reoxidized by a cyanide-insensitive system. Analysis of membranes from the cells showed high- and low-potential forms of cytochrome c, cytochrome b and various enzymes, including hydrogenase, formate dehydrogenase and fumarate reductase. The predominant CO-binding pigment appeared to be a form of cytochrome c, but the spectra also showed evidence of cytochrome o. The membrane cytochromes were reduced by H2 in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide at concentrations which prevented the reduction of cytochrome c with succinate as the electron donor. Reoxidation of the substrate-reduced cytochromes by O2 was apparently mediated by cyanide-sensitive and cyanide-insensitive systems. The membranes also had hydrogen-fumarate oxidoreductase activity mediated by cytochrome b. C. fetus ssp. jejuni has high- and low-potential forms of cytochrome which are associated with a complex terminal oxidase system.