Highly efficient biodiesel production by a whole-cell biocatalyst employing a system with high lipase expression in Aspergillus oryzae

In the present study, a system with high lipase expression in Aspergillus oryzae was developed using an improved enolase promoter (P- enoA 124) and the 5′ untranslated region of a heat-shock protein (Hsp-UTR). P- enoA 142 enhanced the transcriptional level of a heterologous lipase gene and Hsp-UTR improved its translational efficiency. Fusarium heterosporum lipase (FHL) was inserted into a pSENSU-FHL expression vector harboring P- enoA 142 and Hsp-UTR and was transformed into an A. oryzae NS4 strain. Transformants possessing pSENSU-FHL in single (pSENSU-FHL#1) and double copies (pSENSU-FHL#2) were selected to evaluate the lipase activity of the whole-cell biocatalyst. The two strains, pSENSU-FHL#1 and #2, showed excellent lipase activity in hydrolysis compared with the strain transformed with conventional expression vector pNAN8142-FHL. Furthermore, by using pSENSU-FHL#2, methanolysis could proceed much more effectively without deactivation, which allowed a swift addition of methanol to the reaction mixture, thereby reducing reaction time.