Biotransformation of methyl-β-d-glucopyranoside to higher chain alkyl glucosides by cell bound β-glucosidase of Pichia etchellsii

In the present study, we have investigated the use of Pichia etchellsii whole cells for synthesis of long-chain alkyl glucosides. Methyl-β-d-glucopyranoside (MG) was used in reaction with fatty alcohols, n-hexanol, n-octanol, n-decanol and n-dodecanol to synthesize the respective alkyl glucosides. The initial reaction conditions were first optimized at 2.5 ml scale for synthesis of octyl glucoside (OG) and were 8% water content, 100 mM MG and 6 h of reaction time and this resulted in ∼53% yield. A maximum transglucosylation/hydrolysis ratio of 2.79 was obtained at 100 mM MG favoring high product yield. Based on the optimized conditions, a reactor was operated at 50 ml level which resulted in ∼60% conversion of MG to OG. A simple high performance liquid chromatography method was developed for quantitation of higher chain glucosides using a refractive index detector. A maximum of 27% and 13% yield was obtained for decyl-, and dodecyl-β-d-glucopyranoside, respectively.