To improve the production of a recombinant α-galactosidase in Pichia pastoris, the hac1 gene from P. pastoris GS115 constructed in pPic9K vector was coexpressed withα-galactosidase gene in P. pastoris X33. Results showed that the HAC1 protein under control of AOX1 promoter increased the expression level ofα-galactosidase protein in P. pastoris. Theα-galactosidase activity superexpressed with the HAC1 protein was up to 2.2 times than that of constitutive expression of HAC1. hac1 gene integrated into the genome of the P.pastoris was proved by PCR. The galactosidase activity of Gal-HAC1-4#, after 168 h methanol induction in 50 L high-density fermentation, reached the highest value of 6 560 U/mL, and increased by 27%compared with Gal-21#. The crude protein concentration of Gal-HAC1-4# was higher than the strain Gal-21# after methanol induced. These results showed that the galactosidase expression ability of Pichia pastoris was inproved by co-expressing protein HAC1.%为提高毕氏酵母（Pichia pastoris）中重组α-半乳糖苷酶的表达，将来源于P. pastoris GS115的hac1基因构建至pPIC9K表达载体中，转化到重组P. pastoris中与α-半乳糖苷酶共表达。研究结果表明，在AOX1启动子控制下，HAC1过表达提高了重组P. pastoris中α-半乳糖苷酶蛋白表达含量，使α-半乳糖苷酶活性提高了2.2倍。经PCR产物鉴定，结果表明重组P. pastoris基因组中插入hac1基因。经50 L发酵罐甲醇诱导168 h，Gal-HAC1-4#工程菌最终酶活达到6560 U/mL，比Gal-21#工程菌提高了27%。甲醇诱导后Gal-HAC1-4#发酵液中粗蛋白浓度均高于Gal-21#工程菌。表明共表达HAC1蛋白可提高毕氏酵母产α-半乳糖苷酶蛋白的能力。
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