Bioremediation of phenol by halotolerant yeast Trichosporon cutaneum in saline culture

Phenol and its derivatives are environmental pollutants commonly found in many industrial influents. Despite being toxic, phenol can be utilized by some microorganisms as sole carbon and energy sources.
In this research, halotolerant phenol biodegrading yeasts were isolated in GPY and MA media containing 250 ppm phenol and 5% NaCl. Among isolated strains, the best strain that was able to utilize phenol in presence of 5% NaCl was selected and identified by PCR of ITS gene. The resistance of the yeast isolate to different phenol concentrations and its toxicity besides phenol degradation at saline culture were investigated by spectroscopic measurement of residual phenol and cell dry weight.
In this research, 15 strains were isolated. Based on their ability for growth in different concentration of phenol and salt, ADH8 was selected as best strain. An inhibitory effect of phenol was observed at concentrations higher than 1250 ppm in presence of 5% NaCl, resulting in significant reduction of growth rates and phenol degradation. At concentration 750 ppm and 1000 ppm of phenol, all of the phenol was consumed after 24 h. Our results revealed that at the concentration of 1250 ppm of phenol, because of phenol toxicity on T. cutaneum, growth rate and phenol degradation was different. Higher lag phase and incubation time were observed in this concentration and total removal was detected after 48 h.
Discussion and The results indicate that the highly phenol-resistant halotolerant yeast represents a potentially promising means for biodegrading phenol pollution in wastewater treatment effluent and contaminated soil containing salt.