Dual substrates biodegradation kinetics of m-cresol and pyridine by Lysinibacillus cresolivorans

Phenols and N-heterocyclic compounds are found to co-exist in actual wastewater, especially in petrochemical and coking wastewater. Lysinibacillus cresolivorans, a bacterium capable of phenol-biodegradation was used to study the substrate interactions of m-cresol and pyridine as single and dual substrates. The cell growth and substrate biodegradation kinetics were also investigated with initial m-cresol concentrations varying from 0 to 1200 mg/L and pyridine concentrations varying from 0 to 150 mg/L. The single substrate kinetics was well described by the Haldane kinetic models. The single-substrate parameter values of m-cresol on cell growth were μmax = 0.89 h−1, Ks = 426.25 mg/L, Ki = 51.26 mg/L and μmax = 0.0925 h−1, Ks = 60.28 mg/L, Ki = 16.17 mg/L for cell growth on pyridine. Inhibitory effects of substrates were observed when cells were grown on the mixed substrates. The interaction parameter Im,p (0.76) was greater than Im,p (0.11), which indicated that m-cresol inhibited the utilization of pyridine much more than pyridine inhibited the biodegradation of m-cresol. The study showed a good potential of L. cresolivorans in degrading mixed substrates of m-cresol and pyridine.