Cloning and overexpression of lipase gene from Geotrichum candidum Y162
白地霉Y162脂肪酶基因克隆及其在毕赤酵母中的高效表达

By means of bioinformatics, we aligned nucleotide sequence of reported lipase gene from Geotrichum. Primers were designed based on the conservative nucleotide sequence, and the lipase gene of G. candidum Y162 was cloned for the first time in China. Nucleotide sequencing revealed that the open reading frame has 1692 nucleotides without any introns, encoding 563 amino acid residues including a signal sequence of 19 amino acid residues, which is 86% identical to lipase I of G. fermentans. Subsequently, we cloned the lipase gene into expression vector pPIC9K, and then transformed into Pichia pastoris GS115. Cultures of recombined P. pastoris accumulated active enzyme in the supernatant to levels of 55 U/mL after induction for 96 hours in shake flasks. The purified lipase exhibited maximum activity at 50°C and pH 8.0, and was stable between pH 6.0 and 10.0 and below 60°C. Lipase activity was compatible with the presence of organic solvents such as methanol, n-heptane, hexane, cyclohexane, glycerol, benzene and diethyl ether. Lipase showed hydrolysis prefer-ence for triacylglycerol substrates containing cis-9 unsaturated fatty acid. The results suggest that the lipase could be a candidate for industrial applications.