Abstract
With a view to utilizing Rhizopus oryzae cells immobilized within biomass support particles (BSPs) as a whole-cell biocatalyst for biodiesel fuel production, an investigation was made of the effect of cross-linking treatment with glutaraldehyde on the stability of lipase activity. Although the lipase activity of the BSP-immobilized cells decreased considerably in the presence of the methyl esters produced by methanolysis, the activity of cells treated with 0.1% glutaraldehyde solution showed no significant decrease during twenty batch cycles, with the methyl ester content of the reaction mixture reaching 60-83% in each cycle. We also constructed a novel cell-surface display system using as a new type of cell-wall anchor the 3297-bp of the 3' region of the FLO1 gene, and in this system the N-terminus of the Rhizopus oryzae lipase (ROL) was fused to the FLO1 protein. In the use of Saccharomyces cerevisiae cells displaying FLO1 gene as a whole-cell biocatalyst methyl ester content synthesized reached 78.3% after 72 h. These findings indicate that, given the simplicity of the lipase production process, the use of whole cell biocatalysts using either R. oryzae cells immobilized within BSPs or S. cerevisiae cells displaying ROL offers a promising means of biodiesel fuel production for industrial application.
