Kinetic aspects of the growth of Klebsiella aerogenes with some benzenoid carbon sources.

Abstract

SUMMARY The aerobic growth of Klebsiella aerogenes was studied in chemically defined media consisting of mineral salts (ammonium as N source) and various benzenoid compounds singly as sole source of carbon+energy. A strain adapted to a defined glucose mineral salts (ammonium as N source) medium grew readily in concentrations of benzaldehyde, benzoate, p-hydroxybenzoate or phenylacetate of the order 10–3 m to 10–2 m. The initial growth rate in benzoate, p-hydroxybenzoate or phenylacetate increased and then decreased with increasing concentration of benzenoid compound, according to a relationship which is interpreted by analogy with enzyme inhibition by excess substrate. The kinetics of growth inhibition by the above compounds in glucose salts medium were similar to those in the simplest case of inhibition of an enzyme or heterogeneous catalyst. During repeated subculture in benzoate, p-hydroxybenzoate or phenylacetate as sole carbon source, the bacteria showed various adaptive responses which include an immediate decrease in the lag and an increase in the growth rate. As the concentration of benzoate to which the bacteria had become adapted to utilize as sole carbon+energy source was increased, the molar growth yield and the growth rate changed in a related manner and the inhibitory action of benzoate in glucose salts medium decreased.