Direct production of a genetically-encoded immobilized biodiesel catalyst

The use of immobilized enzymes as biocatalysts has great potential to improve the efficiency and environmental sustainability of many industrial processes. Here, we report a novel approach that allows for the direct production of a highly active immobilized lipase within the bacterium Bacillus thuringiensis. Cry3Aa-lipA crystals were generated by genetically fusing Bacillus subtilis lipase A to Cry3Aa, a protein that naturally forms crystals in the bacteria. The crystal framework significantly stabilized the lipase against denaturation in organic solvents and high temperatures, resulting in a highly efficient fusion crystal that could catalyze the conversion of triacylglycerols to fatty acid methyl ester biodiesel to near-completion over 10 cycles. The simplicity and robustness of the Cry-fusion crystal (CFC) immobilization system could make it an appealing platform for generating industrial biocatalysts for multiple bioprocesses.