AEROBIC GROWTH OF AND ACTIVITIES OF NADH OXIDASE AND NADH PEROXIDASE IN LACTIC-ACID BACTERIA

Aerobic growth of 22 strains of lactic acid bacteria of the genera Lac tobacillus, Pediococcus, Leuconostoc, Streptococcus, and Enterococcus was investigated. Most strains grew well under aerobic conditions in p arallel with an increase in the growth yield. Homofermentatives and he terofermentatives produced acetic acid under aerobic conditions with a decrease in lactic acid or ethanol in the culture medium. NADH oxidas e and NADH peroxidase activities were detected in a wide variety of th e bacteria. Most strains showed the activity of NADH oxidase that prod uced water, acid some strains showed the activity of NADH oxidase that produced hydrogen peroxide. L. delbrueckii subsp. delbrueckii NRIC 10 53 and L. fermentum H3 and Y6 accumulated hydrogen peroxide in the cul ture medium, and these strains grew poorly under aerobic conditions, w hich might have been due to hydrogen peroxide toxicity. The hydrogen p eroxide was eliminated by the addition of catalase to the culture medi um. The activities of NADH oxidase and NADH peroxidase were enhanced b y the addition of FAD to the reaction mixture. A possible role of FAD in the reaction was discussed.