西藏地区发酵牛乳中产细菌素乳酸菌的筛选及鉴定

从西藏地区藏族传统发酵乳中分离乳酸菌,采用生理生化特性和16S基因序列同源性分析对其进行鉴定,通过双层琼脂平板扩散法筛选具有抑菌活性的菌株。结果表明,共分离37株乳酸菌,其中,乳杆菌属(Lactobacillus)35株、明串珠菌属(Leuconostoc)2株;35株乳酸杆菌为Lactobacillus casei 16株、Lactobacillus paracasei 7株、Lactobacillus plantarum 4株、Lactobacillus fermentum 2株、L.delbrueckii subsp.bulgaricus 2株、Lactobacillus helveti-cus 1株、Lactobacillus diolivorans 3株;7株L.casei和L.paracasei的发酵上清液对3株细菌指示菌表现出明显抑制作用,所有菌株对真菌无抑菌活性;在排除有机酸、H2O2等的干扰和经蛋白酶K处理后,初步确定7株乳酸菌发酵上清液中的抑菌物质为细菌素。

Screening and Identification of Bacteriocin-producing Lactic Acid Bacteria from Tibet Fermented Milk Products

Thirty seven lactic acid bacterial strains were isolated from Tibet traditional fermented milk products,and were identified to species level through physiological and biochemical characterization,as well as 16S rRNA sequence analysis method.The result showed that out of 39 isolates,37 were assigned to lactobacillus genus,including Lactobacillus casei(16),Lactobacillus paracasei(7),Lactobacillus plantarum(4),Lactobacillus fermentum(2),L.delbrueckii subsp.bulgaricus(2),Lactobacillus helveticus(1),and Lactobacillus diolivorans(3).Two strains were assigned to Leuconostoc genus.Cell free supernatant of seven L.casei and L.paracasei strains showed significant antimicrobial activity against 3 indicator pathogenic bacteria.All isolated strains had no antimicrobial activity against fungi.The possibility of organic acid or H2O2 action as antimicrobial components was eliminated by experiments.The antimicrobial components were inferred to be bacteriocin because the antimicrobial activity disappeared after cell free supernatant was treated with proteinase.