7α,15α-diOH-DHEA is a key precursor of the novel oral contraceptive Yasmin. Colletotrichum lini could catalyze dehydroepiandrosterone (DHEA) at the 7α and 15α positions. In this work, C. lini resting cells were applied in the bioconversion of DHEA to 7α,15α-diOH-DHEA. In the presence of 2 % (w/v) Tween-80, the conversion efficiency of DHEA increased drastically. The DHEA conversion and the 7α,15α-diOH-DHEA yield increased by 34.6 and 87.0 %, respectively, at the DHEA concentration of 10 g/L. Furthermore, the effects of Tween-80 on substrate solubility and C. lini physiological properties were studied. Results showed that the DHEA solubility with 2 % Tween-80 increased by 7.8 times. Meanwhile, the mycelia were integrated and full in the presence of 2 % Tween-80. The analysis on fatty acid profile of the C. lini cell membrane indicated that Tween-80 increases the content of unsaturated fatty acid. All above results suggested that the enhanced product yield caused by Tween-80 was mainly associated with easier substrate-molecule transportation across the cell membrane of C. lini.
Keywords: Bioconversion; Colletotrichum lini; DHEA; Hydroxylation; Resting cells.