牦牛乳中乳链菌肽产生菌的定向筛选及抗菌活性研究

Oriented screening and identification of nisin-producing Lactococcus lactis with antibacterial activity from yak milk

以新鲜牦牛乳为原料,采用选择培养基及抑菌圈法定向筛选、富集微生物,通过生理生化指标检测及16S rDNA鉴定乳链菌肽产生菌,并采用滤纸片扩散法检测其抗菌活性.结果表明,共筛选出4株乳链菌肽产生菌,4株菌均符合乳酸乳球菌生理生化特征,且其16S rDNA与乳酸乳球菌的测序结果完全一致,确认为乳酸乳球菌;这4株菌只对G^+菌产生抑菌圈,对G^-菌没有抑菌活性,其中菌株Lac4对藤黄微球菌和金黄色葡萄球菌都体现出强抑制作用,菌株Lac1对藤黄微球菌有强抑制作用,对金黄色葡萄球菌是弱抑制作用,而菌株Lac2和Lac3对藤黄微球菌和金黄色葡萄球菌都是弱抑制作用.

With fresh yak milk as material,the selective culture medium and the antibacterial ring method were used to screen and enrich the bacteria. Physiological and biochemical index and 16S rDNA sequence analysis were used to identify nisin-producing strains,and the antimicrobial activity of nisin-producing Lactococcus lactis was detected by the method of filter paper diffusion. Four strains of nisin-producing Lactococcus lactis were selected from yak milk. The physiological and biochemical characteristics,and their sequence of 16S rDNA proved that the 4 strains were Lactococcus lactis. All strains displayed antibacterial activities against Gram-positive bacteria,but not against interested Gram-negative bacteria. It also showed that the Lac4 strain exhibited very strong antibacterial activity against Micrococcus flovus and Staphylococcus aureus. Stain Lac1 owned strong antibacterial activity against Micrococcus flovus and weak antibacterial activity against Staphylococcus aureus,but the antibacterial activities of Lac2 and Lac3 against Micrococcus flovus and Staphylococcus aureus were very weak.