Production of biodiesel from plant oil hydrolysates using an Aspergillus oryzae whole-cell biocatalyst highly expressing Candida antarctica lipase B

For enzymatic biodiesel production from plant oil hydrolysates, an Aspergillus oryzae whole-cell biocatalyst that expresses Candida antarctica lipase B (r-CALB) with high esterification activity was developed. Each of soybean and palm oils was hydrolyzed using Candida rugosa lipase, and the resultant hydrolysates were subjected to esterification where immobilized r-CALB was used as a catalyst. In esterification, r-CALB afforded a methyl ester content of more than 90% after 6 h with the addition of 1.5 M equivalents of methanol. Favorably, stepwise additions of methanol and a little water were unnecessary for maintaining the lipase stability of r-CALB during esterification. During long-term esterification in a rotator, r-CALB can be recycled for 20 cycles without a significant loss of lipase activity, resulting in a methyl ester content of more than 90% even after the 20th batch. Therefore, the presented reaction system using r-CALB shows promise for biodiesel production from plant oil hydrolysates.