Hydrophobic immobilization of Burkholderia cepacia lipase onto octyl-silica for synthesis of flavors esters

Abstract

Burkholderia cepacia lipase (BCL) was immobilized onto silica modified with octyl groups (OS) and the biocatalyst (BCL-OS) was evaluated as its performance in the synthesis in organic medium (synthesis of flavor esters as a model). The maximum support loading was 0.375 g enzyme /g support , yielding a biocatalyst with an activity of 1197 U/g support at pH 7.0 and 50 °C in the hydrolysis of olive oil. The biocatalyst BCL-OS showed to be 9-fold more stable than the free lipase at 60°C in buffer solution (absence of substrates), with an increase of half-life from 16 to 144 h. The physical-chemical characterization of silica, octyl silica, and BCL-OS biocatalyst allowed confirming the immobilization of BCL onto the modified silica. The biocatalyst had an excellent performance in the synthesis of flavor esters, yielding more than 85% esterification yield (based on acid consumption) for acetic and butyric acids as acyl donors, and ethanol, butanol and hexanol as acyl acceptors. The biocatalyst could be recycled by ten 5 h-cycles of butyl butyrate syntheses at 37°C in heptane, retaining around 80% of its initial activity. Therefore, these results indicate that the BCL immobilized onto silica modified with octyl groups is a promising biocatalyst for application in organic syntheses.