Role of plasmid pJL1 of Arthrobacter oxydans 317 in the degradation of β‐sitosterol

Abstract

AbstractArthrobacter oxydans 317 is a plasmid (pJL1)‐harbouring organism capable of complete degradation of β‐sitosterol, 4‐androstene‐3,17‐dione (AD) and 1,4‐androstadiene‐3,17‐dione (ADD). Plasmid‐cured strain A. oxydans 317 A1 obtained by treatment of A. oxydans 317 with sodium dodecylsulphate (DUTTA et al. 1989) is capable of only partial degradation of β‐sitosterol side chain and incapable of utilizing AD and ADD. Conjugation experiments were carried out using A. oxydans 317 A1 as the recipient and A. oxydans 317 as the donor of pJL1 plasmid. A transconjugant strain A. oxydans 317 TC containing pJL1 plasmid was obtained. The transconjugant was able to form 9 α‐hydroxy‐4‐androstene‐3,17‐dione (9α‐hydroxy AD) from β‐sitosterol and AD, and to utilize ADD for growth but it could not convert AD to ADD. It was proposed that pJL1 is involved in the conversion of 3‐oxochol‐4‐en‐24‐oic acid to AD and in the 9α‐hydroxylation of the steroid nucleus but it is not connected with 1,2‐dehydrogenation, a critical reaction step in steroid ring opening.