Characterization and antibacterial activity of a novel exopolysaccharide produced by Lactobacillus kefiranofaciens DN1 isolated from kefir
Characterization and antibacterial activity of a novel exopolysaccharide produced by Lactobacillus kefiranofaciens DN1 isolated from kefir
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DOI：
10.1016/j.foodcont.2017.02.033
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发表时间：
2017-08-01
期刊：
影响因子：
6
通讯作者：
Seo, Kun-Ho
中科院分区：
文献类型：
--
作者：
Jeong, Dana;Kim, Dong-Hyeon;Seo, Kun-Ho
开菲尔是由乳酸菌、醋酸菌和酵母菌共同培养而成的发酵乳，这些乳酸菌、醋酸菌和酵母菌被一种名为开菲尔兰的胞外多糖（EPS）包裹。益生菌开菲尔提供了许多好处，包括对许多病原体的抗菌作用。然而，这些影响的机制尚未完全了解。从开菲尔中分离得到22株乳酸菌，其中开菲尔乳杆菌8株，开菲尔乳杆菌2株，乳酸乳球菌7株，肠膜明串珠菌5株。测定了各菌株产生EPS的能力，发现开菲尔诺产乳杆菌DN 1在所有菌株中具有最高的EPS产量。开菲尔诺产乳杆菌DN 1使用葡萄糖和乳糖产生EPS，并且EPS产量在改良的MRS肉汤（60 g/L葡萄糖）中上升到2.2 g/L。采用生长曲线法研究了开氏乳杆菌DN 1胞外多糖（EPS_DN1）对单核细胞增多性李斯特菌（Listeria monocytogenes）和肠道沙门氏菌（Salmonella enteritrium）的抑菌活性。我们发现EPS_DN1在至少1%的浓度下能够对两种病原体发挥杀菌作用。值得注意的是，高效尺寸排阻色谱（HPSEC）分析的结果表明，EPS_DN1不是开菲尔，开菲尔颗粒的主要EPS，这表明EPS_DN1代表开菲尔中的一种新的生物活性化合物。(C)2017爱思唯尔有限公司版权所有。
Kefir is fermented milk produced by co-cultures of lactic and acetic acid bacteria and yeast that are encapsulated by an exopolysaccharide (EPS) called kefiran. Probiotic kefir provides many benefits, including antimicrobial effects against many pathogens. The mechanisms underlying these effects, however, are not yet completely understood. In this study, a total of 22 strains of lactic acid bacteria (LAB), including eight strains of Lactobacillus kefiranofaciens, two strains of Lactobacillus kefiri, seven strains of Lactococcus lactis, and five strains of Leuconostoc mesenteroides, were isolated from kefir and classified by 165 ribosomal RNA gene sequencing. The ability of each strain to produce EPS was determined, and Lactobacillus kefiranofaciens DN1 was found to have the highest EPS yield among all isolates. Lactobacillus kefiranofaciens DN1 produced EPS, using glucose and lactose, and EPS yield rose to 2.2 g/L in modified MRS broth (60 g/L glucose). The antimicrobial activities of the EPS produced by Lactobacillus kefiranofaciens DN1 (EPS_DN1) against Listeria monocytogenes and Salmonella Enteritidis were assessed by growth curve analysis. We found that EPS_DN1 at a concentration of at least 1% was able to exert bactericidal effects against both pathogens. Notably, results of high-performance size-exclusion chromatography (HPSEC) analysis indicated that EPS_DN1 was not kefiran, the major EPS of kefir grains, suggesting that EPS_DN1 represents a novel bioactive compound in kefir. (C) 2017 Elsevier Ltd. All rights reserved.