PATHWAYS OF PYRUVATE METABOLISM AND ENERGETICS OF GROWTH OF BROCHOTHRIX-THERMOSPHACTA

Brochothrix thermosphacta, a psychrophilic, facultative anaerobe, exhi bited homolactic fermentation under anaerobic conditions in the presen ce of excess glucose. In glucose-limited chemostat culture (on synthet ic medium), ethanol, acetate, formate and lactate were formed. Formati on of ethanol and acetate was accounted for by the formate concentrati ons in culture filtrates. Acetate, formate and ethanol formation was e nhanced at low growth rates in chemostat culture. O2-limited chemostat studies indicated that formate formation was inhibited by oxygen (< 0 .2 muM) and studies with a variant, strain 301, which lacked pyruvate dehydrogenase activity, showed that cell culture in basal medium did n ot occur at O2 tensions greater than that preventing formate productio n in the wild-type strain. The data are consistent with stimulation of pyruvate formate lyase activity by glucose limitation, possibly becau se of decreased concentrations of glycolytic intermediates.