Characterization of Hydrocortisone Biometabolites and 18S rRNA Gene in Chlamydomonas reinhardtii Cultures

Abstract: A unicellular microalga, Chlamydomonas reinhardtii , was isolated from rice paddy-field soil and water samples and used in the biotransformation of hydrocortisone ( 1 ). This strain has not been previously tested for steroid bioconversion. Fermentation was carried out in BG-11 medium supplemented with 0.05% substrate at 25oC for 14 days of incubation. The products obtained were chromatographically purified and characterized using spectroscopic methods. 11β,17β-Dihydroxyandrost-4-en-3-one ( 2 ), 11β-hydroxyandrost-4-en-3,17-dione ( 3 ), 11β,17α,20β,21-tetrahydroxypregn-4-en-3-one ( 4 ) and prednisolone ( 5 ) were the main products of the bioconversion. The observed bioreaction features were the side chain degradation of the substrate to give compounds 2 and 3 and the 20-ketone reduction and 1,2-dehydrogenation affording compounds 4 and 5 , respectively. A time course study showed the accumulation of product 2 from the second day of the fermentation and of compounds 3 , 4 and 5