Bioprospecting of whole-cell biocatalysts for cholesterol biotransformation.

Microorganisms were isolated from industrial wool scouring effluents and from the soil adjacent to the wastewater treatment lagoon, both sterols-rich environments, in order to search for novel biocatalysts able to transform cholesterol. The isolates were identified on the basis of morphological and biochemical characteristics and phylogenetic analysis. Furthermore, a rapid and accurate bacteria identification by matrix assisted laser desorption/ionization-time-of-flight mass spectrometry was carried out. Bacteria and fungi including representatives of the genera Fusarium, Talaromyces, Trichoderma, Mucor, Aspergillus, Citrobacter, Proteus, Klebsiella, Exiguobacterium, Acinetobacter, Tsukamurella, Bacillus, and Streptomyces were found and evaluated for their ability to biotransform cholesterol by whole-cell treatment system. The results show that a Trichoderma koningiopsis strain, as well as two strains of Mucor circinelloides were able to transform cholesterol into value-added products. The major products were characterized as 7β-hydroxycholesterol, 4-cholesten-3-one, 5α,6α-epoxycholestan-3β-ol and 5β,6β-epoxycholestan-3β-ol. To the best of our knowledge, the present study is the first report of cholesterol biotransformation by representatives of Trichoderma and Mucor genera.