Biodegradation characterisation and kinetics of m-cresol by Lysinibacillus cresolivorans

A novel strain of m-cresol-degrading bacterium, named as Lysinibacillus cresolivorans, was isolated from aerobic sludge from a coking wastewater treatment plant. This bacterium is able to utilise m-cresol as its sole source of carbon and energy. The optimal pH for growth is 6.8 similar to 7.3 and the optimal temperature is 35 degrees C. Compared to organic nitrogen sources, inorganic nitrogen sources were easily utilised for the m-cresol biodegradation. The degradation rate of m-cresol at different starting concentrations was analysed with zero-order kinetic characteristics. When the initial concentration of m-cresol was 224.2 mg.l(-1), the reaction rate reached a maximum at 46.80 mg.(l.h)(-1). The cell growth kinetics was also investigated with initial m-cresol concentrations varying from 0 to 1 200 mg.l(-1). The growth kinetics was well described by the Haldane kinetic models. The parameter values of m-cresol on cell growth were mu(max) = 0.89 h(-1), K-s = 426.25 mg.l(-1), K-i = 51.26 mg.l(-1). Experiments supplementing growth with glucose indicated that this substrate increased the biomass, and also induced the biodegradation of m-cresol. From the results, it can be concluded that Lysinibacillus cresolivorans is an efficient m-cresol-degrading bacterium and that glucose plays multiple roles in the co-substrate condition.