南山牧场牛乳中具有抑菌活性乳酸菌的筛选及鉴定

Screening and identification of lactic acid bacteria with antibacterial activity in the milk of Nanshan pasture

该研究采用湖南南山高山牧场的鲜牛奶为原料,李斯特菌为指示菌,抑菌圈直径为评价指标,从中筛选抑菌特性较高的乳酸菌,通过形态观察和分子生物技术对其进行鉴定。同时,对菌株所产的抑菌物质的成分进行初步分析,并研究pH、温度及NaCl对其抑菌效果的影响。结果表明,从湖南南山高山牧场的鲜牛奶中共分离出28株乳酸菌,其中7株对李斯特菌具有抑菌活性,且菌株C15的抑菌能力最强,抑菌圈直径为6.17 mm。菌株C15被鉴定为乳酸乳球菌(Lactococcal lactis),初步判定其所产的抑菌物质成分为蛋白类或多肽类物质,该抑菌物质在酸性及中性条件下稳定,且具有较好的热稳定性和耐盐性,经80 ℃处理20 min后,抑菌活性保留54.35%;经10%NaCl(1 mol/L)处理2 h后,抑菌活性保留86.76%。

Using fresh milk from Nanshan pasture in Hunan province as raw material, Listeria as indicator bacteria, and inhibition zone diameter as evaluation indicator, the lactic acid bacteria with higher antibacterial properties were screened and identified by morphological observation and molecular biotechnology. At the same time, the components of the bacteriostatic substances produced by the strain were preliminary analyzed. The effects of pH, temperature and NaCl on the antibacterial effect were studied. The results showed that 28 strains of lactic acid bacteria were isolated from the fresh milk of Nanshan pasture in Hunan province, 7 of which had antibacterial activity against Listeria, strain C15 had the strongest antibacterial activity, and the inhibition zone diameter was 6.17 mm. The strain C15 was identified as Lactococcal lactis, and the antibacterial substance was protein or polypeptide substance. The bacteriostatic substance was stable under acidic and neutral conditions, and had good thermal stability and salt tolerance. After treatment at 80 ℃ for 20 min, the bacteriostatic substance activity retained 54.35%, after treated with 10% NaCl (1 mol/L) for 2 h, the antibacterial activity was 86.76%.