352 lactic acid bacterial strains were isolated from fermented Chinese cabbage juice, cucumber juice,barley juice, corn juice, fresh milk, traditional cheese, and red tea. One strain against Listeria monocytogenes and Escherichia coli was selected by double-agar diffusion method. After eliminating some interference factors, such as the organic acid and hydrogen peroxidex, the supernatant of the strain exhibited inhibitory effect against the indicator strain. However,when treated with trypsin, pepsin and papain, the inhibitory activity lost totally. Therefore, the inhibitory material which has the features of protein, could be considered as bacteriocin. The bacteriocin was independent of heat, and the inhibitory activity of which was kept over 90％ after treated at pH 6. 5, 121 ℃ for 15 min. According to the characteristics of bacteria, the bacteriocin was classified into class Ⅱ a. The strain was identified and named Enterococcusfaecium BC-3 on the base of physiological and biochemical tests and 16S rRNA gene sequence homology analysis.%从自制的发酵肉、酸菜汁、黄瓜汁、大麦汁、玉米汁等以及市售鲜奶、传统干酪、红茶中分离出352株乳酸菌,通过琼脂平板扩散法筛选到l株对单核细胞增生李斯特菌和大肠杆菌有明显抑制作用的乳酸菌菌株.排除有机酸、过氧化氢等的干扰后,乳酸菌发酵液离心后的上清液仍有抑菌活性,用胰蛋白酶、胃蛋白酶、木瓜蛋白酶处理后失去抑菌活性,从而确定产生的抑菌物质具有蛋白质性质,是一种细菌素.该细菌素具有热稳定性,在pH6.5,121℃热处理15 min时,抑菌活性仍保持90%以上.经过生理生化试验和16S rRNA基因序列相似性分析,鉴定BC-3菌株为屎肠球菌,命名.Enterococcus.faecium BC-3.其产生的细菌素对单核细胞增生李斯特菌有特异活性,并且具有热稳定性,根据细菌素的分类特征,该细菌素属于Ⅱa类细菌素.
展开▼
