Pretreatment of immobilized Candida sp. 99-125 lipase to improve its methanol tolerance for biodiesel production

Candida sp. 99-125 lipase immobilized on textile membrane was pretreated with several methods to improve its activity and methanol tolerance for biodiesel production. Lipase pretreatments with short chain alcohols from n-propyl alcohol to isobutyl alcohol did not have any positive effect on the lipase activity and methanol tolerance. While lipase treated with methanol solutions from 10 to 20% volume concentrations did enhance the enzyme activity and methanol tolerance, and this lipase activation effect did not exist when methanol volume concentration was 40%. 1 mM salt solutions of (NH4)2SO4, CaCl2, KCl, K2SO4 and MgCl2 pretreatments were the useful tools to improve the lipase activity and methanol tolerance. The reason might be that salts could incorporate with the protein molecular to form a more stable molecular to resist conformation change induced by high methanol concentration. The operational stability of pretreated lipase was improved dramatically for biodiesel production during batch reactions.