To express the porcine antibacterial peptide Cecropin P 1 in Pichia pastoris and analyze the bio-logical activity of the expressed product , Cecropin P1 gene was designed and synthesized to include the partiality codons of P.pastoris based on the gene sequences encoding swine antibacterial Cecropin P 1.The linearized recombinant was shocked into P.pastoris X-33 by electroporation , and the high copy transfor-mants were screened with Zection and PCR .After being pured , Tricine -SDS-PAGE showed a single bright band .Agar diffusion method was used to analyze the biological activity of the purified antimicrobial peptides under the thermal , different pH , trypsin and pepsin .The results indicated that the cecropin P 1 had a strong thermal stability , acid stability and pepsin stability .However , in alkaline environment and pancreatin , the antibacterial activity of cecropin P 1 decreased significantly .%为了在毕赤酵母Pichia pastoris表达系统中表达猪源Cecropin P1并分析其生物活性，根据Cecropin P1的氨基酸序列和毕赤酵母的密码子偏嗜性设计引物，通过SOEing法合成全基因片段载入到PpicZαA质粒中，酶切线性化重组质粒PpicZαA-cecropin P1后电穿孔导入毕赤酵母X-33中进行整合，经Zection筛选和PCR检测获得高拷贝的转化子。发酵表达后将表达产物经加热预处理和Sephadex G-25层析及冻干浓缩后，Tricine-SDS-PAGE显示明亮单一条带。采用琼脂扩散法对纯化后的抗菌肽的热稳定性、酸碱稳定性、耐胰酶和胃蛋白酶稳定性进行了生物活性分析，结果表明Cecropin P1具有较强的热稳定性、酸稳定性及胃蛋白酶稳定性，但是在碱性环境下和胰酶作用下抑菌活性明显下降。
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