Alkaline Growth pH-Dependent Increase of Respiratory and NADH-Oxidation Activities of the Facultatively Alkaliphilic Strain Bacillus lentus C-125

Abstract

Respiration of a facultative alkaliphile, Bacillus lentus C-125, was increased around alkaline pH near the upper pH-limit for growth of the organism. O2-Uptake rates of the cells grown in a complex medium at pH 7–9 and 9.5–10 were 0.98–1.4 and 2.4 μmol O atom/min/mg cell protein, respectively. Membrane vesicles from the cells grown at pH 7–9 and 9.9 incorporated O2 at rates of 1.1–1.4 and 2.5 μmol O atom/min/mg envelope protein, respectively, using exogenous NADH as an electron donor. In the presence of menadione as an exogenous electron acceptor, the membrane vesicles from the cells grown at pH 7–8.5 and 9.9 oxidized NADH at rates of 1.4–1.7 and 6.3 μmol NADH/min/mg envelope protein, respectively. Levels of respiratory and NADH-oxidation activities of the organism are dependent on the growth pH, and higher than those reported previously in alkaliphilic Bacillus spp. © 1996, Taylor & Francis Group, LLC. All rights reserved.