High-level expression of lipase from Galactomyces geotrichum mafic-0601 by codon optimization in Pichia pastoris and its application in hydrolysis of various oils.

Abstract

A Galactomyces geotrichum strain with lipolytic activity was isolated and identified by the analysis of internal transcribed spacer (ITS) sequence of 18s rDNA. Full-length lipase gene of this stain is composed of 1692 base pairs (bp) without intron, which encodes a 563-amino-acid protein. A catalytic triad (Ser217-Glu354-His463) was found by constructing the three-dimensional structure of the lipase. In shake flasks, the lipase (LIP) catalytic activity in the supernatant of the recombinant Pichia pastoris increased 48.7% by codon optimization. LIP purified by anion exchange column showed a single protein band on 12% SDS-PAGE. The molecular weight (MW) of LIP was approximately 62kDa. The specific activity of purified LIP reached 1257.9U/mg. The optimum temperature and pH of LIP catalysis were 45°C and pH 8.2, respectively. LIP was stable over the pH range of 4.2-11.2. LIP maintained its activity constantly at 40°C and 50°C for 120min. Zn2+ inhibited LIP activity; Ba2+, Mn2+, Ca2+ and EDTA increased the enzyme activity. Referring the amount of hydrolyzed olive oil by LIP as 100%, various oils including lard, peanut oil, rapeseed oil, sunflower oil, soybean oil and linseed oil were efficiently hydrolyzed by 17.24 ± 1.34%, 40.34 ± 2.56%, 105.86 ± 2.78%, 115.51 ± 2.32%, 116.21 ± 2.15%, 120.69 ± 1.98%, respectively. The characteristics allow LIP as a potential biocatalyst in various fields of industry.