Abstract

Utilization of dibenzothiophene and flocculation of this compound from environment by yeast was studied. The yeast was isolated from phenol-contaminated waste and identified as Trichosporon sp. This strain used phenol and dibenzothiophene as the only sources of carbon and sulfur, respectively. However it had better growth when glucose and yeast extract was added to basal medium containing dibenzothiophene. When the yeast was grown on dibenzothiophene in basal medium almost 100% of dibenzothiophene was reduced in 14 days, but in the present of glucose, only 77% was reduced.. The results showed that glucose produced more biomass for dibenzothiophene utilization without any sign of 2-hydroxybiphenyl (2-HBP) production. However the yeast utilized phenol and biphenyl such that there was no accumulation of biphenyl in media. The results showed that Trichosporon sp. have the capacity to transform biphenyl and dibenzothiophene, and therefore could be used for removal of these toxic compounds.

Key words: Trichosporon, yeast, dibenzothiophene, phenol,  2-hydroxybiphenyl, transformation,  flocculation.