文摘
Pichia pastoris has been used to produce various recombinant proteins under high oxygen demand conditions. To improve the heterologous production of ¦Â-galactosidase, the vgb gene encoding Vitreoscilla hemoglobin (VHb) was co-expressed in the P. pastoris cytoplasm under the control of the methanol-inducible promoter. Co-expression of VHb under different aeration conditions improved cell performance in terms of growth, viability, respiratory rate, and ¦Â-galactosidase production. Under limiting aeration conditions, the VHb+ strain produced 28.2 % more biomass but 31.2 % less total ¦Â-galactosidase activity than the VHb?/sup> strain. Under non-limiting aeration conditions, the VHb+ strain showed 20.3 % higher cell growth and 9.9 % more total ¦Â-galactosidase activity than the VHb?/sup> strain. Moreover, under these conditions, the VHb+ strain was 7.7 % more viable and had a 28.2 % higher oxygen uptake rate (OUR) than the VHb?/sup> strain. Evidently, VHb can enhance the OUR and promote methanol metabolism, thereby improving cell performance and ¦Â-galactosidase production.