Biodegradation characterisation and kinetics of m-cresol by Lysinibacillus cresolivorans

Abstract

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 ~ 7.3 and the optimal temperature is 35°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 μmax = 0.89 h-1, Ks = 426.25 mg·ℓ-1, Ki = 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-cresoldegrading bacterium and that glucose plays multiple roles in the co-substrate condition.