产乳酸菌素菌株的筛选鉴定及其特性分析

本实验对广西巴马村天然发酵米粉中的乳酸菌进行分离鉴定,筛选出一株具有抑菌活性的植物乳杆菌M44,并研究了其所产乳酸菌素的基本性质。采用微生物形态学和16S r DNA序列分析法鉴定菌株M44为植物乳杆菌,其发酵上清液具有抑菌活性,抑菌物质确定为蛋白类。采用盐析法粗提所产乳酸菌素,确定最佳硫酸铵沉淀浓度为60%。由乳酸菌素产量与菌株生长的关系实验得出乳酸菌素的最佳收获时间为发酵培养12 h。管碟法抑菌实验表明,该乳酸菌素在p H范围2~8时有良好的抑菌活性;121℃处理15 min后仍具有抑菌活性;胃蛋白酶、胰蛋白酶处理后抑菌性消失;对单核增生李斯特细菌、大肠杆菌、沙门氏菌,金黄色葡萄球菌均有抑制作用。该乳酸菌素为天然生物防腐剂的开发与应用提供了研究基础。 

Identification and antimicrobial characters of a strain producing lactobacillin

The extraction,purification and functional characterization of the bacteriocin produced by Lactobacillus plantarum M44 selected from rice noodles products of Guangxi province were studied.It was identified as Lactobacillus plantarum via using microbial morphology identification and 16 S r DNA gene sequence homology analysis.The fermentation supernatant of strain M44 have antibacterial activity,and antibacterial substances was identified as protein.The bacteriocin was purified by protein salting- out method and the optimal concentration of60% ammonium sulfate precipitation was determined.The most appropriate harvest time of the bacteriocin was 12 h by studying production of bacteriocin during the growth of strain M44.The results indicated that the lactobacillin M44 still had antibacterial activity at 121 ℃ for 15 min,and had strong antibacterial activity in the range of p H2.0~8.0,but had no antibacterial activity after pepsin and trypsin treatment,whatever lactobacillin M44 proved its good inhibitory effect on proliferation of Listeria monocytogenes,Escherichia coli,Salmonella typhimurium,and Staphylococcus aureus by the oxford cup method.In this paper a preliminary study on the bacteriocin produced by Lactobacillus plantarum M44 had been made to lay the basis for the development of natural biological preservatives.