以日常生活中常见的也是深受人们喜爱的酸奶和下饭菜（酸菜、泡菜）等富含乳酸菌的食品为原材料，通过MRS分离培养基等选择性培养基分离出若干株乳酸菌，进一步纯化分离得到单一的乳酸菌种保存待用，并对乳酸菌的生长条件进行测定。以大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌等病原菌作为指示菌，通过抑菌实验、蛋白酶处理实验等系列实验来检测乳酸菌具有较好抑制病原菌生长能力的内在物质——某种多肽类物质，称之为乳酸菌素。对筛选出的菌株进行相应的生理生化实验，鉴定出有乳杆菌属、链球菌属、片球菌属和明串珠菌属等多个属的乳酸菌株。%By using yogurt and sour pickled cabbage in our daily life as raw materials which is rich in lactic acid bacteria through the MRS selective medium, several strains of lactic acid bacteria can be isolated from among them, and these lactic acid bacteria are further purified to obtain the absolute pure bacteria which are saved to be used, then experiments are taken for the growth conditions of lactic acid bacteria. A certain internal substance--a kind of polypeptide, called lactein, is tested by taking these pathogensescherichia coli, bacillus subtilis,andstaphylococcus aureus as indicator bacteria, bacteriostatic experiment, and protease treatment, which has the bacteriostatic ability. Moreover, after corresponding physiological and biochemical experiments are conducted,lactobacillus, streptococcus, pediococcus and leuconostocect are identified.
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