Exploring the synthetic potential of cell bound β-glycosidase of Pichia etchellsii

Enzymatic synthesis of oligosaccharides with absolute stereo-selectivity and regio-selectivity provides an economical alternative to classical chemical methods. Here we demonstrate, for the first time, that whole cells of P. etchellsii are highly efficient biocatalysts and can be used for oligosaccharide synthesis using p-nitrophenyl-β-d-glucopyranoside, o-nitrophenyl-β-d-glucopyranoside and p-nitrophenyl-β-d-xylopyranoside as both donors and acceptors. Auto-condensation of p-nitrophenyl-β-d-glucopyranoside and o-nitrophenyl-β-d-glucopyranoside resulted in formation of β-(1 → 6) linked disaccharide as major products in 4 and 12% yield respectively. By contrast, auto condensation of p-nitrophenyl-β-d-xylopyranoside exclusively lead to formation of β-(1 → 4) linked disaccharide in 24% yield.

► Enzymatic synthesis of aryl-oligosaccharides using Pichia etchellsii whole cells as biocatalysts.
► Absolute stereo-selectivity and regio-selectivity using the whole cell biocatalyst approach in buffer.
► Auto-condensation of p-nitrophenyl-β-d-glucopyranoside leading to formation of a β-(1 → 6) linked disaccharide in 4% yield.
► Auto-condensation of o-nitrophenyl-β-d-glucopyranoside resulting in formation of a β-(1 → 6) linked disaccharide in 12% yield.
► Auto condensation of p-nitrophenyl-β-d-xylopyranoside resulting in formation of β-(1 → 4) linked disaccharide in 24% yield.