Cloning of the Lipase Gene of Aspergillus Niger ZF34 and Its Expression in Pichia Pastoris

The main purpose of this study was to express the lipase gene of Aspergillus niger (A. niger) in Pichia pastoris and to produce lipase by high density fermentation. The lipase gene LipA was amplified from A. niger genomic DNA, the coding region contained 894 bp in length and encoded 297 amino acids. The similarity of LipA gene sequence with other lipase genes of A. niger was 99%. The LipA gene was successfully ligated with the plasmid pPIC9K to construct the recombinant vector pPIC9K-LipA, which was subsequently transformed into Pichia pastoris GS115. After induced by methanol, LipA gene was expressed in yeast cells, and the enzyme could be secreted to the outside of yeast cells. The recombinant strain GS115/pPIC9K-LipA was fermented in a 100 L fermentor for 144 hours, and then the wet weight of thallus was 100.5 g/L, and the enzyme activity in the fermentation broth reached 1 950 U/mL. This study lays a foundation for the high-efficiency industrial fermentation of A. niger lipase by using the characteristics of high-density fermentation of Pichia pastoris, which has a great application prospect.