Substrate Inhibition of the Growth of Bacterium NCIB 8250 by Phenol

Abstract

SUMMARY: Examination of the growth kinetics of Bacterium NCIB 8250 in a two-stage continuous culture showed that growth of this organism on phenol could be accounted for by the Haldane function for substrate inhibition. The magnitude of the constants (K s < 1 mg/l; and K i, 110 mg/l) was such that inhibition was the dominant factor governing the growth of the organism even at substrate concentrations less than 10 mg/l. The maintenance requirement of the organism was high (0.24 to 0.28 g/g h), probably owing to the energy requirement for rupture of the aromatic nucleus of the substrate. The influence of such kinetics on the treatment of inhibitory wastes by the activated-sludge process is discussed. Extreme sensitivity of the experimental system to slight changes in operating conditions was explicable by a mathematical model using constants found in the investigations.