Production of alkyl polyglucoside using pichia pastoris GS115 displaying Aspergillus aculeatus β-glucosidase I

Abstract

Pichia pastoris GS115 displaying Aspergillus aculeatus β-glucosidase I was used as whole-cell biocatalyst catalyzing the synthesis of 1-hexyl glucoside, 1-octyl glucoside, and 1-decyl glucoside through reverse hydrolysis in water–alcohol two-phase system, while glucose and primary alcohols were used as substrate. In this study, factors affecting the synthetic yield were optimized in our study, including water content, glucose concentration, whole-cell biocatalyst content, the pH value of sodium acetate buffer, and the reaction temperature. In 5 mL reaction volume, the optimal reaction conditions of HG were: 10% pH 3.0 buffer, 0.2 mol/L glucose, 10 g/L whole-cell biocatalyst; the optimal reaction conditions of DG: 15% pH 3.0 buffer, 0.6 mol/L glucose, 10 g/L whole-cell biocatalyst; the optimal reaction conditions of DG: 20% pH 2.0 buffer, 0.2 mol/L glucose, 40 g/L whole-cell biocatalyst; three reactions were conducted under 55 °C. After 72 h the maximum yield of HG was 11.5%, that of OG and DG were 5.3 and 3.2% after 96 h, respectively. The reutilization experiments inducted that the whole-cell biocatalyst could be used at least for five times without obvious decrease in synthesis ability.