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productc is provided by the action of lithium aluminurn hydride on this intermediate \r.7 Acknowledgment.--The authors are grateful to Dr. H. T. Openshaw for a sample of isoemetine hydrobromide. Financial support was provided by the research committee of the Graduate School. f r o n s ) and similar ( c j . ref. 4) systems, catalytic reduction also afford? t h e more stable 3,15,20-cis-fvans product (E. E . van Tarnelen, 11. Shamma and P. E. Aldrich, TIIIS JCXJRXAI., 78, 4628 (195G). ( 7 ) I t is pertinent t h a t in t h e case of t h e A3-dehydroyohimbane (D-E

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SummarySome results of our studies on transformation of steroids by mixed culture fermentation are presented in this paper. Arthrobacter simplex was paired in turn with each of the following: Streptomyces roseochromogenes, Curvularia lunata, Absidia coerulea, and Aspergillus ochraceus. The steroid substrates examined for multiple transformation were 16cr-hydroxy-costexolone, 16a-hydroxycortexolone 16,17-acetonide, 9a-fluorohydrocortisone, 9a-fluorohydrocortisone 21-acetate, and 9a-fluorohydrocortisone 21-hemisuccinate. The effects of media, steroid substrate, and microbial interaction in a mixed culture on the induction and repression of steroid transforming enzymes were unique to each case studied. The reaction mechanism of the multiple steroid transformation waa also found to vary from one mixed culture system to another. Two different reaction mechanisms were observed, namely, consecutive and parallel. In the former, one of the two enzymatic reactions always preceded the other, while in the latter, two different enzyme reactions occurred simultaneously, thereby giving rise to two different intermediates. Multiple transformation of steroids by a single step mixed culture fermentation has potential economic advantages.