Bioconversion of Hydrocortisone by Unicellular Microalga Oocystis pusilla

• Published in: Biotechnology (Faisalābād, Pakistan) Vol. 7; no. 2; pp. 293 - 298
• Main Authors: Ghasemi, Younes, Rasoul-Ami, Sara, Morowvat, Mohammad Hossein, Azam, Seyed Bagher Mosavi, Shokravi, Shadman, Mohagheghz, Abdolali, Ghoshoon, Mohammad Bagher, Raee, Mohammad Javad
• Format: Journal Article
• Language: English
• Published: 01-06-2008
• Subjects: Oocystis pusilla
• ISSN: 1682-296X
• DOI: 10.3923/biotech.2008.293.298

A unicellular microalga, Oocystis pusilla, was isolated from paddy-field and applied in the biotransformation experiment 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 25 degree C for 14 days incubation. The products obtained were chromatographically purified followed by their characterization using spectroscopic methods, 11 beta , 17 alpha , 20 beta , 21-tetrahydroxypregn-4-en-3-one(2), 11 beta , 17 beta -dihydroxyandrost-4-en-3-one (3) and 11 beta -hydroxyandrost-4-en-3, 17-dione (4) were the main byproducts in the hydrocortisone bioconversion. Bioreaction characteristics observed were 20-ketone reduction for accumulation of compound 2 and side chain degradation of the substrate to prepare compounds 3 and 4. Time course study showed the accumulation of the product 2 from the second day of the fermentation and 3 as well as 4 from the third day. All the metabolites reached their maximum concentration in seven days. Optimum concentration of the substrate, which gave maximum bioconversion efficiency, was 0.5 mg mL super(-1) in one batch. Growth was not influenced by the addition of steroid substrate. Biotransformation was completely inhibited in a concentration above 2.0 mg mL super(-1).