Transformation of steroids by Bacillus strains isolated from the foregut of water beetles (Coleoptera: Dytiscidae): II. Metabolism of 3 beta-hydroxypregn-5-en-20-one (pregnenolone).
The in vitro metabolism of pregnenolone by two Bacillus strains (HA-V6-3 and HA-V6-11) isolated from the foregut of the water beetle Agabus affinis (Payk.) was examined in the course of our studies about a possible participation of gut micro-organisms in the biosynthesis of prothoracic defensive steroids of dytiscids. The transformation products were identified by EI GC--MS of culture extracts after derivatization. The dominating reactions were hydroxylations, with 7 alpha-hydroxypregnenolone as the major product. With considerably lower yields, 7 beta- and 15xi-hydroxypregenolone were formed by both strains, while 11, 17 and 16 alpha-hydroxypregnenolone were produced only by HA-V6-3. The occurrence of 7, 11 alpha- and 7 beta, 11 alpha-dihydroxypregnenolone as well as several minor products containing a 17 alpha-OH group proved the capability of HA-V6-11 to hydroxylate pregenenolone at C(11) and C(17) as well. The monohydroxylated 7-OH-pregnenolones were partly oxidized to 7-oxopregnenolone by both strains. In trace amounts, HA-V6-3 performed 3 beta-acetylation of pregnenolone.
Schaaf
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Universität Bayreuth, Lehrstuhl für Tierökologie II, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
Dettner
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D000818:Animals; D001407:Bacillus / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001711:Biotransformation; D001517:Coleoptera / Q000382:microbiology*; D004064:Digestive System / Q000737:chemistry / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D006900:Hydroxylation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011284:Pregnenolone / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*
D011284:Pregnenolone