Biodegradation of phenol-contaminated soils using Corynebacterium glutamicum. was optimized in this study. Phenol degradation by C. glutamicum was observed in soil supplemented with 1% yeast extract as a substrate. We determined the optimal inoculation size of C. glutamicum (7.4 log(10) CFU mL(-1)) for the degradation of phenol-contaminated soil. Under optimal conditions (1% yeast extract and 7.4 log(10) CFU mL(-1) of C. glutamicum), the efficiency of phenol degradation in soil was greater than 94% at three days after treatment. The degradation of phenol-contaminated soil by C. glutamicum was evaluated using acute toxicity assays with Daphnia magna. Based on the acute toxicity assays, we found that the residual toxicity of contaminated soil was removed completely after three days of C. glutamicum treatment. Crown Copyright (c) 2010 Published by Elsevier B.V. All rights reserved.