International Journal of Current Microbiology and Applied Sciences

ISSN: 2319-7706 Volume 2 Number 9 (2013) pp. 188-197

Biocatalyst activity of entomogenous fungi: stereoselective reduction of carbonyl compounds using tochukaso and related species

K. Ishihara1*, H. Fujimoto1 , M. Kodani1 , K. Mouri1 , T. Yamamoto1 , M.Ishida1 , K. Maruike1 , H. Hamada1 , N. Nakajima2 and N. Masuoka

1Department of Life Science, Okayama University of Science, Okayama, Japan 2Department of Nutritional Science, Okayama Prefectural University, Soja, Okayama, Japan *Corresponding author e-mail: ishihara@dls.ous.ac.jp

ABSTRACT

To investigate the potential ability of tochukaso and related species to act as biocatalysts, we screened 13 entomogenous fungal strains. Two recommended media (potato-dextrose broth and 889 media) and a modified medium (PGO medium) were tested for liquid culture of these entomogenous fungi. Six strains (NBRC100741, 100742, 101754, 106941, 106945, and 106950) cultured using the PGO medium showed a good growth. The stereoselective reduction of -keto esters and aromatic -keto amide using these six strains was investigated. It was found that these strains possess a reducing activity toward various -keto esters. Among them, the reduction of -keto esters by Isaria takamizusanesis NBRC100741 in the presence of L -glycine as an additive gave the corresponding -hydroxy esters with a high conversion ratio and excellent enantioselectivity. Furthermore, it was found that the NBRC100742 strain reduced 2- chlorobenzoylforamide to (R)-2-chloromandelamide with excellent enantiomeric excess even at a high substrate concentration (75.0 mM). Thus, we found that tochukaso and related species have great potential to be used as biocatalysts for the stereoselective reduction of carbonyl compounds.

Keywords

Tohchukaso and related species; Entomogenous fungi; Biocatalyst; Stereoselective reduction; Chiral alcohol.