The localization and induction of bile acid dehydrogenases in Pseudomonas N.C.I.B. 10590 [proceedings].

The induction of activity of several steroid dehydrogenases during adaptive growth of Pseudomonas testosteroni on testosterone (1 7p-hydroxyandrost-4-en-3-one) has been described by Talalay (1965), and Michel-Briand (1969) has carried out a detailed study of the induction of 3a-hydroxy steroid-NAD+ oxidoreductase in the same organism. Watanabe et al. (1973~) have demonstrated the presence of these enzymes, together with specific steroid-binding proteins, in osmotic-shock-fluid preparations from induced cells. Degradation by aerobic micro-organisms of bile acids to 4-en-3-one and 1,4-dien-3-one structures has been reviewed by Hayakawa (1973), and Hill (1974) has demonstrated the anaerobic dehydrogenation of deoxycholate (3a, 12cx-dihydroxy-5,8-cholanic acid) by Clostridium paraputrijhm. We have isolated a number of metabolites from deoxycholate-grown cultures of Pseudomonas N.C.I.B. 10590 (Barnes et al., 1976). The major products, which accumulated under both aerobic and anoxic conditions, were 12ahydroxy-3-oxopregna-I ,4-diene-20-carboxylic acid and 12~-hydroxyandrosta-l,4-diene3,17-dione. Analysis of anoxic cultures revealed a coupling between steroid dehydrogenation and nitrate reduction (Barnes eta[ . , 1975). Here we report on the induction, by three potential intermediates in deoxycholate breakdown, of oxygen uptake in washed-