Phenol and cresol mixture degradation by the yeast Trichosporon cutaneum

Most industrial wastes contain different organic mixtures, making important the investigation on the microbial destruction of composite substrates. The capability of microbes to remove harmful chemicals from polluted environments strongly depends on the presence of other carbon and energy substrates. The effect of mixtures of phenol- and methyl-substituted phenols (o-, m-, p-cresol) on the growth behaviour and degradation capacity of Trichosporon cutaneum strain was investigated. The cell-free supernatants were analysed by HPLC. It was established that the presence of o-, m- and p- cresol has not prevented complete phenol assimilation but had significant delaying effect on the phenol degradation dynamics. The mutual influence of phenol and p-cresol was investigated. We developed the kinetic model on the basis of Haldane kinetics, which used model parameters from single-substrate experiments to predict the outcome of the two-substrate mixture experiment. The interaction coefficients indicating the degree to which phenol affects the biodegradation of p-cresol and vice versa were estimated. Quantitative estimation of interaction parameters is essential to facilitate the application of single or mixed cultures to the bio-treatment of hazardous compounds.