Exploring the effects of oil inducer on whole cell-mediated methanolysis for biodiesel production

Whole cell-mediated methanolysis of renewable oils for biodiesel production has drawn much attention in recent years since it can avoid the complex preparation procedures of traditional immobilized lipase. During the cultivation of Rhizopus oryzae whole cell catalyst, plant oils are usually added into the medium as inducer for lipase synthesis. It was found that oil inducer not only influenced lipase production, but also led to varied whole cell's catalytic performance. In this paper, the related mechanisms were explored and it was found that the higher unsaturated fatty acid (UFA) was contained in oil inducer, the higher intracellular lipase could be obtained. Different oil inducers also resulted in varied compositions of cell membrane, which was further found to be responsible for the operational stability of the catalyst. Cells with membrane enriched with saturated fatty acid (SFA) exhibited better stability than those enriched with UFA. And further study showed that after glutaraldehyde cross-linking treatment, the operational stability of both UFA enriched cells and SFA enriched cells were enhanced greatly and no loss in cell's catalytic activity was detected after being repeatedly used for 15 batches.