【作者】 赵娜；

【导师】 乌云达来； 郭军；

【作者基本信息】 内蒙古农业大学 ， 食品科学， 2013， 硕士

【摘要】 为获得应用潜力较高的抗菌活性菌株，对内蒙古地区传统乳制品中分离的63株乳酸菌进行抗菌活性菌株筛选，获得了一株具有广谱抗菌活性的菌株（编号为AJT）。通过16SrDNA序列分析和API50CHL糖发酵试验鉴定为瑞士乳杆菌，16SrDNA基因序列的GenBank登录号为JQ775393。菌株AJT培养至6h无菌发酵液开始具有抗菌活性，20h达到最高活性；初步排除了酸性产物和过氧化氢的抗菌干扰作用，抗菌物质粗提液对蜡状芽孢杆菌、金黄色葡萄球菌、大肠杆菌、荧光假单胞杆菌等6株革兰氏阳性和阴性细菌，以及扩展青霉、黑曲霉和黄色镰孢等8株霉菌具有显著的抑制作用；在pH2.0～pH5.0范围内有抑菌活性；对热稳定；经胰蛋白酶、胃蛋白酶、蛋白酶K和木瓜蛋白酶处理后抗菌活性下降，表明菌株AJT所产抗菌物质中含有蛋白类物质。用有机溶剂、固相萃取及高效液相色谱法进行纯化，得到具有抑菌活性的单峰物质。通过单因素试验和正交试验确定的菌株AJT抗菌效果最优的培养基成分为：乳糖15.0g/L、酵母浸出粉7.0g/L、胰蛋白胨6.0g/L、牛肉浸膏12.0g/L、乙酸钠7.0g/L、柠檬酸钠7.0g/L、磷酸氢二钾2.0g/L、硫酸镁200mg/L、硫酸锰40mg/L，吐温-801.0g/L，起始pH6.5；最佳培养条件为：接种量2.0%，37℃培养20h。与未优化发酵条件相比，抗菌活性提高31.8%。更多还原

【Abstract】 To obtain high promising antibacterial activity strain, a total63lactic acid bacteria strains that had been isolated from traditional dairy products in Inner Mongolia region were screened according to their antibacterial activity. A strain labeled AJT was chosen and identified as Lactobacillus helveticus by API50carbohydrate fermentation test and16S rDNA sequence analysis, its16S rDNA sequence that uploaded to GenBank was recorded asJQ775393.The fermentation broth of strain AJT started to show antibacterial activity after6h incubation and reach the maximum at20h’s incubation. The interference of organic acids and hydrogen peroxide were preliminarily eliminated, and six gram positive and negative indicator strains such as Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas Jluorescens, and eight fungi strains such as Penicillium expansum, Streptomyces macrosporeus and Fusarium culmorum as well all showed susceptible to the antibacterial substance extract. The antibacterial activity of the extract was still stable after heat treatment while the adequate pH for inhibition was ranging from pH2.0to5.0. However, the antibacterial extract was sensitive to proteases such as trypsin, pepsin, protease K and papain, and it implies the antibacterial substance may contain protein or peptide. The organic solvents extract was purified by solid phase extraction column and high performance liquid chromatography, obtained a purified peak and it has antibacterial activity.Single factor and orthogonal tests were conducted to determine the media for optimum antibacterial activity culture, and the optimized ingredient was:lactose15.0g/L, yeast extract7.0g/L, peptone6.0g/L, beef extract12.0g/L, sodium citrate hydrate7.0g/L, sodium acetate7.0g/L, K2HPO42.0g/L, MgSO4-7H2O200mg/L, MnSO4-5H2O39mg/L and tween-801.0g/L, with initial pH at6.5, the optimum incubation parameters were: incubate at37℃for20h with2%(v/v) concentration. The antibacterial activity increased31.8%compared to the unoptimized fermentation condition.更多还原