The microalgae Chlorella vulgaris and Chlorella VT-1 were compared with their growth in the presence of phenol (0-400 mg l(-1), 4.24 mM). Both algae could tolerate phenol but Chlorella VT-1 was more tolerant being able to grow albeit slowly in the presence of 400 mg l(-1) phenol whereas this concentration inhibited the growth of C. vulgaris. Phenol was not removed from the medium in the light by Chlorella VT-1 but it was capable of growth on phenol in the dark where phenol was removed from the medium. (c) 2006 Elsevier Inc. All rights reserved.