Antimicrobial activity of n-butyl lactate obtained via enzymatic esterification of lactic acid with n-butanol in supercritical trifluoromethane

Abstract

The lipase-catalyzed synthesis of n-butyl lactate by esterification was performed in supercritical trifluoromethane. Immobilized lipase B from Candida antarctica (Novozym 435) was used as a biocatalyst. Process conditions (pressure and temperature) were optimized performing experiments in a high-pressure batch stirred-tank reactor. Experiments were carried out in the operative pressure ranges from 7.5 to 30MPa and at temperatures 35°C and 55°C. For this purpose phase behavior for d,l-lactic acid/n-butanol/Novozym 435/supercritical fluid system at temperature 55°C and different pressures was studied. The highest conversion of lactic acid after 26h of reaction performance was obtained in supercritical trifluoromethane at 30MPa and 55°C.The n-butyl lactate (standard and enzymatically synthesized) and d,l-lactic acid were tested against four food-borne fungi: Saccharomyces cerevisiae, Aspergillus niger, Trichoderma viride and Penicillium cyclopium and three health-damaging bacteria: Escherichia coli, Pseudomonas fluorescens and Bacillus cereus by the agar well diffusion.