Interactions between benzene, toluene, and p‐xylene (BTX) during their biodegradation

A microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p ‐xylene under aeorbic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene following inhibitory (Andrews) kinetics, whereas neither could grow on P ‐xylene. Benzene and toluene mixtures were removed under cross‐inhibitory (competitive inhibition) kinetics. In the presence of benzene and/or toluene, p ‐xylene was cometabolically utilized by both cultures, but was not completely mineralized. Metabolic intermediates of p ‐xylene accumulated in the medium and were identified. Benzene and toluene were completely mineralized. Cometabolic removal of p ‐xylene reduced the yields on both benzene and toluene. Except for cometabolism, kinetic constants were determined from data analysis and are compared with values published recently by other researchers. © 1994 John Wiley & Sons, Inc.