| Owing to the development and application of steroid drugs, and the importance of biotransformation in steroid industry, this research work focus on screening new transformation strain from endophytes and development of their application in steroid industry. .After screening, 71 of 500 strains showed transformation activities to substrate 4AD. Through purification, 17 different products by 14 strains were identified, of which 11α-OH-17-oxo-homo-AD was first reported. 28 endophytes producing useful intermediates were identified by traditional morphological taxonomy. Strain Gonatobotrys sp., Diplosporium sp., and Myceliophthora sp., which were rarely used in biotransformation, were found to be able to produce 11α-OH-17-oxo-homo-AD, 17-oxo-homo-ADD and 11α. 15α-OH-AD respectively.Strain HCCB00304 was studied for its ability of C11 hydroxylation. The conditions for cultivation and biotransformation were optimized. Ultimately, transformation efficiency was reached 90% when 1% 4AD or ADD was added as substrate, and reached 70% when the concentration of substrate was increased to 2%. This process was scaled up, and the qualified products were obtained and had been used for further research on synthesis of useful compounds.Some parameters and conditions for biotransformation and the induction and inhibition of transformation were studied in detail. It was found that the oxidase in strain HCCB00304 could be induced by some compounds such as deoxycholic acid, and inhibited by metapyrone and so on. After further analysis, the possible model of oxidation was presumed, which might be useful for better understanding of oxidation mechanism.Experiments were made to study the oxidase gene and its expression. The proteinome data obtained revealed that the addition of substrate not only induced the expression of oxidase, but also influenced the whole metabolic flux. Meanwhile, five proteins that were also induced, were proved to be the enzymes involved in the process for glycolysis or gluconeogenesis.
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