海洋巨大芽孢杆菌产脂肽的培养基优化

Medium optimization for production of lipopeptide by marine Bacillus megaterium

该课题组分离得到一株对黄曲霉有良好抑制作用的海洋巨大芽孢杆菌,对其产抗菌脂肽的发酵培养基进行优化。结果表明,5种基础发酵培养基中的Landy修饰培养基为最佳培养基;PB实验结果表明葡萄糖(P=0.0004)对抗菌脂肽的产量为正效应,影响程度大,且为发酵培养基的唯一碳源。由于葡萄糖的添加量过大,将导致发酵物过于黏稠,不利于离心去除菌体及抗菌物质的分离纯化,因此只选取酵母浸膏(P<0.0001)、KH2PO4(P<0.0001)、MgSO4(P=0.0005)及CuSO4(P=0.0035)作为影响产量的关键因子。在此基础上,通过BBD响应曲面法确定了关键因子的最佳水平及交互作用并建立了产抗菌脂肽的二次多项数学模型,之后对最佳发酵工艺进行了预测,利用回归方程得到抗菌脂肽产量最高时各关键因子的最优组合:MgSO40.78g/L、酵母浸膏0.05g/L、KH2PO41.50g/L、CuSO40.39mg/L。利用优化后的发酵培养基产生的抗菌脂肽含量为(571.26±9.72)mg/L,为优化前产量的1.82倍。研究结果为产抑制黄曲霉的抗菌脂肽大规模生产奠定基础。

In this study,we isolated a strain of marine Bacillus megaterium,which had a good inhibitory effect against Aspergillus flavus.The fermentation medium was optimized to produce lipopeptide.The results showed that Landy modified medium was the best medium as fermentation medium among five basic media;the results of PB experiments showed that the glucose concentration(P=0.0004)had positive effect on the production of lipopeptides as the only carbon source in fermentation medium.The large amount of glucose would lead to viscous medium which was not conducive to remove bacteria and separate and purify antimicrobial substances.Thus,only yeast extract(P<0.0001),KH2PO4(P<0.0001),MgSO4(P=0.0005)and CuSO4(P=0.0035)were selected as the key factors of production of lipopeptide.On this basis,the best level of the key factors and interactions were determined and mathematical model of quadratic multinomial was established through the BBD response surface method.The optimal combination of the key factors with the highest lipopeptide production was obtained using the regression equation.The concentration of lipopeptide in optimized fermentation medium was(571.26±9.72)mg/L,which was 1.82 times than that in original Landy modified medium.This is the basis for the large-scale production of antimicrobial lipopeptides that inhibit the growth of Aspergillus flavus.