副干酪乳杆菌Q-1-4的筛选鉴定及抗菌物质特性分析

为获得应用潜力较高的抗菌菌株,对内蒙古地区传统乳制品中分离的8株乳酸杆菌进行抗菌菌株筛选,获得了一株具有广谱抗菌活性的菌株(编号为Q-1-4)。经常规生理生化及分子生物学实验,鉴定该菌为副干酪乳杆菌(Lactobacillus paracasei)。通过实验排除有机酸和过氧化氢干扰后,L.paracasei Q-1-4发酵离心后的无细胞发酵上清液(cell-free fermentation supernatant,CFS)对鼠伤寒沙门氏菌Salmonella typhimurium CMCC50115仍具有抑制作用,且经蛋白酶处理后抗菌活性下降,说明L.paracasei Q-1-4所产抗菌物质中含有蛋白类物质。其在pH 2.0~5.5范围内对鼠伤寒沙门氏菌有抑制作用,且在此pH值范围内该抗菌物质对热稳定,对紫外线不敏感;与十二烷基硫酸钠、乙二胺四乙酸共同作用效果好于单一作用,而其他的表面活性剂、有机溶剂、金属离子对其无明显影响;该抗菌物质具有一定的贮藏稳定性且抑菌谱较广。

Screening and Identification of Lactobacillus paracasei Q-1-4 and Analysis of Antimicrobial Substances Produced by It

To isolate Lactobacillus with great application potential from traditional homemade dairy products in Inner Mongolia, eight strains of Lactobacillus were screened for their antimicrobial activity. Strain Q-1-4 was found to have a broad spectrum of antimicrobial activity and was identified as Lactobacillus paracasei by physiological and biochemical characterization and 16S rDNA sequencing analysis. The antimicrobial activity of the cell-free culture supernatant (CFS) of L. paracasei Q-1-4 against Salmonella typhimurium CMCC50115 still existed after eliminating the interference factors such as lactic acid, acetic acid, and hydrogen peroxides. However, the CFS of L. paracasei Q-1-4 was inactivated after treatment with proteolytic enzymes. Inhibitory activity of the CFS against S. typhimurium CMCC50115 was observed in the pH range from 2.0 to 5.5. The antimicrobial substance had good thermal stability in this pH range and was not sensitive to ultraviolet. SDS and EDTA could enhance the antimicrobial activity, but surfactants, organic solvents and metal ions had no effect on the antimicrobial activity. In addition, the antibacterial activity had good storage stability with a broad inhibitory spectrum.