The production of immobilized whole-cell lipase from Aspergillus nomius ST57 and the enhancement of the synthesis of fatty acid methyl esters using a two-step reaction

Abstract

The production of immobilized whole-cell lipase from Aspergillus nomius ST57 was optimized by cultivation in 50mL of growth medium with the addition of 100, 0.5×0.5×0.5cm3 pieces of biomass support particles at 150rpm, 30°C for 84h. The hydrolytic activity of the immobilized whole-cell lipase was 30.77% higher than the activity obtained from free biomass (based on 1mg dry cell weight). Response surface methodology with a central composite design, which consisted of three parameters: the amount of the immobilized whole-cell lipase, the reaction temperature and the water content, was applied to optimize the synthesis of fatty acid methyl esters (FAME) from palm oil in a solvent-free system by the transesterification reaction using the immobilized whole-cell lipase from A. nomius ST57 as a biocatalyst. The highest percentage of FAME (78.23%) was obtained from a reaction mixture containing 1g palm oil, 1:4 molar ratio of oil to methanol, 23% (w/w of palm oil) of 50mM sodium acetate buffer pH 5 and 16 pieces of immobilized whole-cell lipase at 40°C and 1200rpm for 4h. The water-free transesterified palm oil mixture was then esterified using the immobilized whole-cell lipase. The highest percentage of FAME (94.77%) was obtained at 1g transesterified palm oil mixture, 16 pieces of immobilized whole-cell lipase and 0.06g of methanol for 2h. The immobilized whole-cell lipase retained 90.95% transesterification activity and 100% esterification activity after use for 10 batches.