Abstract: Compared with five commercial lipases, the whole-cell lipase of Rhizopus chinensis CCTCC M201021 (RCL) showed high catalytic ability in the transesterification of soybean oil to fatty acid methyl ester (biodiesel) in the solvent-free system. The effect of reaction parameters including methanol content, water content, lipase amount, and reaction temperature on transesterification was investigated. The biodiesel yield was more than 86.0% in the solvent-free system under the optimal reaction conditions. The effect of different organic solvents on the transesterification indicated that the best one was n-heptane with higher log P values(4.0-4.5). The whole-cell lipase was also proved to be an efficient and potential biocatalyst for biodiesel production from oleic acid and simulant high acid value oil in the solvent-free system.

Key words: Rhizopus chinensis, whole-cell lipase, transesterification, biodiesel, fatty acid methyl ester, solvent-free system, high acid value oil