Enzymatic biodiesel synthesis from yeast oil using immobilized recombinant Rhizopus oryzae lipase

• The yeast Candida sp. LEB-M3 may be a suitable feedstock for biodiesel production.
• The recombinant Rhizopus oryzae lipase immobilized was used as biocatalyst.
• Methanol stepwise addition showed to be a strategy to maintain lipase activity.

The recombinant Rhizopus oryzae lipase (1–3 positional selective), immobilized on Relizyme OD403, has been applied to the production of biodiesel using single cell oil from Candida sp. LEB-M3 growing on glycerol from biodiesel process. The composition of microbial oil is quite similar in terms of saponifiable lipids than olive oil, although with a higher amount of saturated fatty acids. The reaction was carried out in a solvent system, and n-hexane showed the best performance in terms of yield and easy recovery. The strategy selected for acyl acceptor addition was a stepwise methanol addition using crude and neutralized single cell oil, olive oil and oleic acid as substrates. A FAMEs yield of 40.6% was obtained with microbial oils lower than olive oil 54.3%. Finally in terms of stability, only a lost about 30% after 6 reutilizations were achieved.