CONICET | Buscador de Institutos y Recursos Humanos

Esterases, particularly the organic-solvent-stable ones, have attracted great interest due to their potential for the synthesis of high commercial value compounds, such as short-chain esters for food and cosmetic industries. Among these esters, flavor acetates from primary alcohols constitute compounds with a great application mainly in food industries due to their characteristic fragrance and flavor. Considering this approach, the aims of our work was to characterize the organic-solvent-stable type II esterase purified from Bacillus licheniformis S-86 and its ability to synthesize valuable esters. The esterase type II displayed extremely high stability at alkaline pH retaining 100% of its activity at pH 10-11, and but the highest activity was found at pH 8.0. Furthermore, the esterase showed high stability in detergents (86% residual activity in 10% SDS) and ionic and nonionic detergent-induced activation (0.1% detergent concentration). This enzyme was also moderate thermostable (half-life of 1h at 50°C) and optimum temperature between 60-65°C. PMSF, a serine protease inhibitor, did not show any effect on the activity, whereas 90% and 50% inhibition were observed in the presence of AgNO3 and HgCl2 (histidine-specific and thiol group inhibitors), respectively. The immobilized type II esterase was able to synthesize isoamyl acetate from isoamyl alcohol and p-nitrophenyl acetate (acyl donor) in n-hexane. The resulting ester yield (42.8%), obtained at a low temperature (28°C) and with a very low amount of enzyme (4.6·10-5 mg/ml), indicates a high potential for type II esterase in isoamyl acetate synthesis for production purposes.