Transformation of steroids by Bacillus strains isolated from the foregut of water beetles (Coleoptera: Dytiscidae):: I.: Metabolism of androst-4-en-3,17-dione (AD)

Two Bacillus strains were isolated from the foregut of the water beetle Agabus affinis (Payk.) and tested for their steroid transforming ability. After incubation with androst-4-en-3,17-dione (AD), 13 different transformation products were detected. AD was hydroxylated at C-6, C-7, C-11 and C-14, resulting in formation of 6 beta-, 7 alpha-, 11 alpha- and 14 alpha-hydroxy-AD. One strain also produced small amounts of 6 beta,14 alpha-dihydroxy-AD. Partly, the 6 beta-hydroxy group was further oxidized to the corresponding 6-oxo steroids. In addition, a specific reduction of the Delta(4)-double bond was observed, leading to the formation of 5 alpha-androstane derivatives. In minor yields the carbonyl functions at C-3 and C-17 were reduced leading to the formation of 3 xi-OH or 17 beta-OH steroids. EI mass spectra of the trimethylsilyl and O-methyloxime trimethylsilyl ether derivatives of some transformation products are presented for the first time. (C) 1999 Elsevier Science Ltd. All rights reserved.