Correlation of oxygen utilization and hydrogen peroxide accumulation with oxygen induced enzymes in Lactobacillus plantarum cultures.

Two strains of Lactobacillus plantarum accumulated H2O2 when grown aerobically in a complex glucose based medium. The H2O2 accumulation did not occur immediately on exposure of the culture to O2 but was delayed for a time which, in the case of one strain, was dependent on the amount of inoculum used to seed the culture. The accumulation was always preceded by an increase in the rate of O2 utilization by the cultures. The latter coincided approximately with an increase in specific activity of NADH oxidase, pyruvate oxidase and NADH peroxidase. H2O2 was not a product of NADH oxidase in vitro but was formed in substantial quantities from O2 during oxidation of pyruvate. The three enzymes were induced by O2 and H2O2; the induction of NADH oxidase responded to lower levels of O2 (but not of H2O2) than the pyruvate oxidase or the NADH peroxidase.