The Ability of Edible Mushrooms to Act as Biocatalysts: Preparation of Chiral Alcohols Using Basidiomycete Strains

Abstract

To examine the potential ability of edible mushrooms to act as biocatalysts, 19 basidiomycete strains were screened. Modified media (PG, O, and PGO medium) for liquid cultivation of these basidiomycete strains were designed and tested. Wet cells (>10 g) of 4 basidiomycete strains ( Pleurotus salmoneostramineus H7, P. salmoneostramineus H13, Ganoderma lucidum NBRC31863, Flammulina velutipes NBRC31862) were harvested from PGO medium for 7 days. The stereoselective reduction of α -keto esters using the 4 strains was tested. It was found that each of these strains had a reducing activity toward 6 aliphatic α -keto esters. In the presence of L-alanine as an additive, the reduction of ethyl 2-oxobutanoate and ethyl 2-oxopentanoete by P. salmoneostramineus H7 produced the corresponding alcohol with a high conversion ratio and with excellent enantiomeric excess (>99% e.e. ( R )). Furthermore, ethyl pyruvate, ethyl 2-oxobutanoate, and ethyl 2-oxopentanoate were predominantly reduced to the corresponding ( R )-hydroxy ester (>99% e.e.) by G. lucidum . Thus, we found that these edible mushrooms have great potential to be used as biocatalysts for the stereoselective reduction of carbonyl compounds.