Engineering of industrial Aspergillus ochraceus strains for improved steroid 11α-hydroxylation efficiency via overexpression of the 11α-hydroxylase gene CYP68J5

Abstract

The steroid 11α-hydroxylase encoded by CYP68J5 in Aspergillus ochraceus TCCC41060 is involved in the 11α-hydroxylation of 16,17α-epoxyprogesterone. To increase the steroid 11α-hydroxylation efficiency of the production strain Aspergillus ochraceus TCCC41060, recombinant strains of A. ochraceus over-expressing CYP68J5 were constructed. Using 16,17α-epoxyprogesterone as substrate (20 g/l) under optimized conditions, recombinant strain CYP68J5-TrpC-2 exhibited conversion rates of 92% compared with 80% for the control strain TCCC41060. Moreover, the time required for the recombinant strain CYP68J5-TrpC-2 to achieve the highest conversion rates (92%) was reduced by 12 h compared with that of the control strain to achieve 80% conversion. It is concluded that recombinant A. ochraceus strains over-expressing the CYP68J5 gene significantly increased conversion rates and dramatically shortened the transformation time, thus improving process efficiency of 11α-hydroxylation of 16,17α-epoxyprogesterone.