Enantioconvergent Biohydrolysis of Racemic Styrene Oxide to R-phenyl-1, 2-ethanediol by a Newly Isolated Filamentous Fungus Aspergillus tubingensis TF1

• Published in: Applied biochemistry and biotechnology 2013-08, Vol.170 (8), p.1965-1973
• Main Authors: Duarah, Aparajita, Goswami, Amrit, Bora, Tarun C., Talukdar, Madhumita, Gogoi, Binod K.
• Format: Article
• Language: English
• Subjects: Aspergillus - classification; Aspergillus - isolation & purification; Aspergillus - metabolism; Aspergillus tubingensis; Biocatalysts; Biochemistry; Biodiversity; Biodiversity hot spots; Biological and medical sciences; Biotechnology; Chemistry; Chemistry and Materials Science; Epoxide Hydrolases - metabolism; Epoxy Compounds - metabolism; Ethylene Glycols - chemical synthesis; Fundamental and applied biological sciences. Psychology; Fungi; Hydrolysis; Isomerism; Microorganisms; Species Specificity; Styrene
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-013-0324-x

An effort was made to isolate biocatalysts hydrolyzing epoxides from various ecological niches of northeast India, a biodiversity hot spot zone of the world and screened for epoxide hydrolase activity to convert different racemic epoxides to the corresponding 1, 2-vicinal diols. Screening of a total of 450 microorganisms isolated was carried out using NBP colorimetric assay. One of the strains TF1, after internal transcribed spacer sequence analysis, identified as Aspergillus tubingensis , showed promising enantioconvergent epoxide hydrolase activity. The hydrolysis of unsubstituted styrene oxide (1) occurred to give 97 % ee of R-(−)-1-phenylethane-1, 2-diol (6) with more than 99 % conversion within 45 min incubation. It is shown to be a cheap and practical biocatalyst for one step asymmetric synthesis of chiral R-diol. The other representative substrates (2–5), although underwent hydrolysis with more than 99 % conversion beyond 15 h, exhibited poor enantioselectivity.