枯草芽孢杆菌源抗菌肽发酵条件优化及其对雏鸡的抗炎作用

Optimization of fermentation conditions of antibacterial peptide from Bacillus subtilis and its anti-inflammatory effect on chickens

研究旨在优化枯草芽孢杆菌源抗菌肽发酵条件并探究其对雏鸡的抗炎作用。试验采用单因素方法筛选出适合枯草芽孢杆菌K4发酵的最佳氮源、碳源及初始pH值、温度、接种量。用筛选出的最佳发酵培养基和条件在50 L发酵罐内发酵1株能产抗菌肽的枯草芽孢杆菌K4,并将最终发酵液添加20%水溶性淀粉进行喷雾干燥。喷干后的菌粉使用大肠杆菌O2作为指示菌进行体外抑菌试验和雏鸡抗炎试验。结果显示,试验筛选出的最佳氮源为蛋白胨,最佳碳源为葡萄糖,培养基初始pH值为7.0,发酵温度为37℃,接种量为5%。喷干后的菌粉活菌数为4.60×10^(10)CFU/g。体外抑菌试验结果显示喷干菌粉对O2的抑菌圈为30 mm。雏鸡抗炎试验结果显示,大肠杆菌感染后的雏鸡灌服抗菌肽K4后的存活率为65%,比药物对照组高18.18%,说明枯草芽孢杆菌K4具有抑制大肠杆菌、降低雏鸡感染大肠杆菌后的死亡率的作用。

The purpose of this study was to optimize the fermentation conditions of antimicrobial peptides derived from Bacillus subtilis and explore its anti-inflammatory effect on chickens.The best nitrogen source,carbon source,initial pH value,temperature and inoculation amount for Bacillus subtilis K4 fermentation were screened out by single factor method.A strain of Bacillus subtilis K4,which can produce antimicrobial peptides,was fermented in a 50 L fermentor with the best fermentation medium and conditions,and the final fermentation broth was sprayed and dried with 20%water-soluble starch.Escherichia coli O2 was used as indicator bacteria for bacteriostatic test in vitro and anti-inflammatory test in chickens.The results showed that the best nitrogen source was peptone,the best carbon source was glucose,the initial pH value of culture medium was 7.0,the fermentation temperature was 37℃,and the inoculation amount was 5%.The number of viable bacteria in spray-dried bacteria powder was 4.60×10^(10) CFU/g.The bacteriostatic test in vitro showed that the bacteriostatic circle of spray-dried bacteria powder to O2 was 30 mm.The results of anti-inflammatory test showed that the survival rate of chickens infected with Escherichia coli was 65%,which was 18.18%higher than that of the drug control group,indicating that Bacillus subtilis K4 had the effect of inhibiting Escherichia coli and reducing the mortality after Escherichia coli infection.