Over-expression of active Candida rugosa lip1 in Pichia pastoris via high cell-density fermentation and its application to resolve racemic ibuprofen

To improve the productivity of Candida rugosa lipase (CRL) and alleviate respiration limitations during high cell-density fermentation, codon-optimized CRL LIP1, and Vitreoscilla hemoglobin (VHb) were co-expressed in Pichia pastoris. The activity of the recombinant strain that expressed LIP1 and VHb from dual promoters, named GS115/9Klip1FZvgb-lip1 ^#1, toward olive oil reached 620?U/mL, which was 1.69-fold greater than that of the recombinant strain GS115/9Klip1 ^#139 (365?U/mL) which only expressed LIP1 from a single promoter, and 1.37-fold greater than that of the recombinant strain GS115/9Klip1FZlip1 ^#39 (450?U/mL), which only expressed LIP1 from two promoters, in shaking flasks. With FM22 as the basic medium and methanol/D-sorbitol (1:1, v/v) as an inducer, the maximum activity of GS115/9Klip1FZvgb-lip1 ^#1 reached 7490?±?379.5?U/mL, which was 2.65-fold greater than that of GS115/9Klip1 ^#139 (2820?±?112?U/mL) and 1.82-fold greater than that of GS115/9Klip1FZlip1 ^#39 (4100?±?205?U/mL) in 10?L fermenters. The conversion ratio (C) and enantiomeric excess (ee_s) of racemic ibuprofen by immobilized CRL LIP1 reached 35.10 and 31.63%, respectively.