中文摘要：

为提高重组菌丝霉素（Plectasin）抗菌肽表达水平,评估其在动物生产上的应用前景,本研究采用30 L液体发酵罐对毕赤酵母（Pichia pastoris）基因工程菌PPle进行高密度诱导培养,采用分批-补料式发酵工艺和甘油基础盐培养基,研究了毕赤酵母工程菌生长及重组蛋白表达规律,并考察了重组菌丝霉素对金黄色葡萄球菌（Staphylococcus aureus）感染大鼠（Rattus norvegicus）肠道健康和免疫功能的影响。结果表明,在30℃下,经甲醇连续诱导72 h,其最大菌体质量浓度为402 g/L,最高培养上清蛋白浓度为3.9 g/L;动物实验表明,金黄色葡萄球感染对大鼠免疫器官指数和血清免疫球蛋白无显著影响（P〉0.05）,但导致大鼠十二指肠和空肠肠绒毛萎缩、粘膜分泌型免疫球蛋白A（secretory immunoglobulin A,sIgA）含量下降,注射重组菌丝霉素能显著改善大鼠肠道健康,提高小肠绒毛高度和粘膜sIgA含量（P〈0.05）;此外,重组菌丝霉素可显著降低大鼠盲肠金黄色葡萄球菌和总细菌数量（P〈0.05）。该研究结果证实,重组菌丝霉素在动物生产上具有潜在应用前景,有望替代抗生素用于金黄色葡萄球菌感染的预防和治疗。

英文摘要：

The experiment was conducted to improve recombinant plectasin production, and evaluate its prospect in animal production. For optimal production of recombinant plectasin, the high-density fermentation of engineered Pichia pastoris（PPle） was performed in a 30- L fermenter. Through feed- batch fermentation process and glycerol basal salts medium, recombinant plectasin was prepared and its effects on immune function and intestinal health in rats（Rattus norvegicus） challenged with Staphylococcus aureus were investigated. After methanol induction at 30 ℃ for 72 h, the highest cell density and the maximal total protein concentration of the supernatant were achieved to 402 and 3.9 g/L, respectively. Animal experiment indicated that Staphylococcus aureus challenge did not affect the immune organ index and serum immune globulin（P〈0.05）, but decreased duodenum and jejunum villus height and secretory immunoglobulin A（sIgA）concentration, however a higher villus height and secretory Ig A in the small intestine were observed when injected with recombinant plectasin（P〈0.05）. In addition, recombinant plectasin can decreased the total bacteria and Staphylococcus aureus of cecum（P〈0.05）. The results indicate that the recombinant plectasin has a great potential in animal production, and it may be an ideal replacement for antibiotics in preventing and curing Staphylococcus aureus.