产细菌素乳酸菌的筛选及体外抑菌试验

从健康鸡、兔、仔猪肠道内容物及新鲜粪便中分离到4l株乳酸菌，通过单层琼脂平板扩散实验，筛选出5株有明显抑菌活性代谢产物的乳酸菌，其中4株属于乳杆菌属，l株属于链球菌属。排除酸的干扰后，离心发酵液对指示菌仍有抑菌活性，用胰蛋白酶和本瓜蛋白酶处理后抑菌活性明显降低，用过氧化氢酶作用上清液，抑菌效果不变，说明过氧化氢未起作用，从而得知抑菌物质中有蛋白质类细菌素。将离心发酵液分别调pH值为2．0、3．0、4．0、5．0、6．0、7．0，做抑菌试验，试验结果证明：所分离的5株乳酸菌在pH2．0，3．0，4．0时均有较强的抑菌活性，且MD菌株在pH7．0时抑菌活性亦较强，这进一步排除了酸的作用。每周重复一次，抑菌结果完全一致，但至第5周时，抑菌现象完全消失，说明抑菌物质随时间的延长而失活，起抑菌作用的物质不是有机酸。

SCREENING OF BACTERIOCIN-PRODUCING LACTIC ACID BACTERIA AND INHIBITING BACTERIA TEST

41 LAB were isolated from small intestinal material and fresh feces of chickens?habits and pigs.Through AWDA test,5 LAB which had bacteriostatic products were selected.Among them four were identified as Lactobacillus ,while one was identified as Streptococcus .The supernatants of fermented liquor without the organic acids showed to have inhibition activity to indicator strain.But the inhibition activity was lost after the treatment of pancreatinum and papain.While they were not sensitive to catalase,that is,hydrogen peroxide had no inhibition ability.These experiments proved that there are bacteriocins in the bacteriostatic products.Through inhibiting Strain Test in different pH(2 0,3 0,4 0,5 0,6 0,7 0),the supernatants of fermented liquor of 5 LAB were active in pH2 0,3 0,4 0,and MD strain was active in pH7 0 After four weeks,the inhibition activity was lost.These more showed that the bacteriostatic products were not organic acids.