The aim of this work was to study the influence of media components and physico-chemical parameters on the growth and reductase production by Geotrichum candidum. Under optimized conditions, the conversion of the substrate increased to > 93%, while specific growth rate and enzyme activity were increased by 200% and 29%, respectively. The rate of conversion of the substrate was very high in the cells grown in optimized medium. The volumetric productivity of the biotransformation process was much higher (0.27 g/l h) with the cells grown in the optimized medium compared to that of grown in un-optimized medium (0. 16 g/l h). The cells were highly stable in the operational condition, indicating the feasibility of their use in multiple batches of reaction. (c) 2006 Elsevier Ltd. All rights reserved.