The biodegradation of phenol at high initial concentration by the yeast Candida tropicalis

Strain Candida tropicalis was isolated from acclimated activated sludge, and was identified as a member of the genus Candida. Phenol biodegradation using a pure culture of C. tropicalis was studied. The results showed that C. tropicalis has pretty high phenol degradation potential, which could thoroughly degrade the phenol of 2000 mg l−1 in the mineral salt medium within 66 h. High inoculum volume lessened phenol toxic property for the cells and increased phenol biodegradation velocity. However, for a certain starting inoculum, with the step increase of phenol concentration, substrate inhibition was obviously enhanced, and more phenol consumption was not assimilated by cell for growth, but was used to counteract strong substrate inhibition. In addition, the cell growth and phenol degradation intrinsic kinetics of C. tropicalis in batch cultures were also investigated over a wide range of initial phenol concentrations (0-2000 mg l−1) using Haldane model. The results received in these experiments demonstrated that the Haldane kinetic model adequately described the dynamic behavior of the phenol biodegradation by the strain of C. tropicalis.