Abstract: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 IgA 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.
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