No abstract

A large number of microorganisms including various microalgal strains are able to convert steroid compounds into useful metabolites. In the present study, the ability of Microchaete tenera, a rice paddy field-isolated microalga, was investigated for biotransformation of progesterone. The incubation was carried out at 25°C under continuous illumination in the present of 0.25 gL −1 of progesterone. After 5 days incubation of the microalga in BG-11 liquid medium, the broth was extracted and the products were purified by the aid of chromatographic methods. Structure elucidation of the metabolites was performed by spectral data ( 13 C NMR, 1 H NMR, FTIR, and MS) and physical constants (melting points and optical rotations). Eventually, four major steroids including 20β-hydroxypregn-4-en-3-one, 20α-hydroxypregn-4-en-3-one, 6β-hydroxypregn-4-en-3,20-dione and 6α-hydroxypregn-4-en-3,20-dione were the results of this biotransformation. The study also showed that the best concentration of starting material, temperature, photoregime, and the influence of CO 2 partial pressure on the production of bioconverted metabolites were 0.25 gL −1 , 25°C, continuous light and 2.0±0.1% (v/v), respectively. Highest concentrations of all biotransformed metabolites were obtained in the 5th day.