Abstract

A purified thermo-tolerant lipase of Streptomyces STL-D8 was immobilized onto the natural fibres namely ‘Bombax’. Hydrolytic activity of this fibre-bound lipase was determined for hydrolysis of p-NPP in a 0.05 M Tris buffer (pH 8.5) at 55°C. This fibre-bound lipase was used to synthesize methyl succinate using methanol and succinic acid as reactants in DMSO at 55°C under shaking. Although a low yield of methyl succinate was observed in reaction mixture at 16 h (14.3 mM) yet the yield of methyl succinate was improved by optimizing molar ratio of reactants to 75 mM: 100 mM (succinic acid: methanol) in DMSO. Molecular sieves added to the reaction system at a concentration of 30 mg/2 mL increased the synthesis of methyl succinate from 30.0 mM to 31.4 mM. The volumetric scale up of the reaction system to 10 and 50 mL produced more or less a similar yield (29.1 mM to 27.9 mM) of methyl succinate after 16 h of reaction. Methyl succinate is a therapeutic molecule that has insulin sensitizing property comparable to that of glucose.

Keywords: Streptomyces sp. STL-D8, lipase, natural fibres, methyl succinate, immobilized biocatalyst, DMSO.

Graphical Abstract