STUDIES ON BIODEGRADATION OF AROMATIC POLLUTANTS BY TRICHOSRORON CUTANEUM YEAST STRAIN

Abstract

Yeast strain Trihosporon cutaneum R57 was studied for its abilities to grow and utilize some organic compounds ( phenol and phenol derivatives, acetophenone, acetone, �.-methylstyrene, benzoic acid, dimethyl phenyl carbinol, methanole and izopropylbenzene) as a sole carbon and energy source. The degradation and development abilities of T. cutaneum R57 applied to some of enumerated aromatic compounds are presented in this work. It was established that the strain could degrade and assimilate completely up to 1gl -1 phenol for a period of 18 h, 0.4 gl -1 �. -methylstyrene, acetophenone and p-cresol were degraded for 24-27h. The intracellular specific activities of phenol hydroxylase (EC 1.14.13.7) and catechol 1,2-dioxygenase (EC 1.13.11.1) in Trichosporon cutaneum R57 strain and its mutants are measured. The comparison of data for phenol hydroxylase and catechol 1,2-dioxygenase activities in cell free extracts obtained by ultrasonication and in permeabilized cells showed that the method of cell permeabilization was more favorable for enzyme analyses. The obtained specific activity of phenol hydroxylase in Trichosporon cutaneum R57 was 0.8 Umg -1 protein while those in 2R and 4R mutant strains were 1.47 Umg -1 protein and 1.28 Umg -1 protein respectively. The value of catechol 1,2-dioxygenase activity showed quite less variability and was kept about 0.2 Umg -1 protein in all investigated strains. The results received in these experiments demonstrated that the increased rate of the initial phenol degradation reaction enhanced phenol utilization by cells and vice versa. We present some preliminary data for enzyme activities in the process of degradation of hydroxyl phenol derivatives.