Biotechnology Program, Environment and Life Sciences Research Center, Kuwait Institute for Scientific Research, PO Box 24885, Safat, 13109 Kuwait.
Biotechnology Program, Environment and Life Sciences Research Center, Kuwait Institute for Scientific Research, PO Box 24885, Safat, 13109 Kuwait.
J Dairy Sci. 2018 Jun;101(6):4944-4952. doi: 10.3168/jds.2017-13996. Epub 2018 Mar 7.
Food safety has become an issue of great interest worldwide. Listeria monocytogenes is a food-borne pathogen that causes listeriosis and is difficult to control in the dairy industry. The use of lactic acid bacteria (LAB) and their antimicrobial substances against Listeria is promising in food applications. Here, we report the isolation from raw camel milk of LAB displaying antilisterial activity. Two isolates were selected for their secretion of bacteriocin(s) and identified by 16S rRNA sequencing as Enterococcus faecium S6 and R9. The produced bacteriocins were partially purified by ammonium sulfate precipitation and then biochemically characterized. Antimicrobial activity was estimated to be 6,400 and 400 AU (arbitrary units)/mL for E. faecium S6 and R9, respectively. The proteinaceous nature of the bacteriocins was confirmed via enzymatic reactions. Moreover, lipolytic and glycolytic enzymes completely inactivated the antimicrobial effect of the bacteriocins. These bacteriocins were heat-resistant and stable over a wide range of pH (2.0 to 10.0). To confirm its inactivation by lipolytic and glycolytic enzymes, the bacteriocin of E. faecium S6 was further purified by gel filtration, which suggested the existence of carbohydrate and lipid moieties. In addition, enterocin-coding genes were identified by PCR, showing DNA fragments corresponding in size to enterocins A, B, and P for E. faecium S6 and to enterocins B and P for E. faecium R9. In conclusion, these results indicate that partially purified bacteriocins from E. faecium S6 and R9 may be beneficial in controlling Listeria in the dairy industry.
食品安全已成为全球关注的热点问题。单核细胞增生李斯特菌是一种食源性病原体，可引起李斯特菌病，在乳制品行业难以控制。利用乳酸菌（LAB）及其抗菌物质对抗李斯特菌在食品应用中具有广阔前景。在此，我们从生骆驼奶中分离出具有抗李斯特菌活性的 LAB。选择了两个分离物用于其细菌素的分泌，并通过 16S rRNA 测序鉴定为屎肠球菌 S6 和 R9。细菌素通过硫酸铵沉淀部分纯化，然后进行生化特性分析。屎肠球菌 S6 和 R9 的抑菌活性分别估计为 6400 和 400 AU/ml。通过酶反应证实了细菌素的蛋白性质。此外，脂解酶和糖酵解酶可完全使细菌素的抑菌作用失活。这些细菌素具有耐热性和广泛 pH 值（2.0 至 10.0）稳定性。为了确认脂解酶和糖酵解酶对细菌素的失活作用，屎肠球菌 S6 的细菌素进一步通过凝胶过滤进行纯化，这表明存在碳水化合物和脂质部分。此外，通过 PCR 鉴定了肠球菌编码基因，显示出与屎肠球菌 S6 的肠球菌 A、B 和 P 以及屎肠球菌 R9 的肠球菌 B 和 P 大小相对应的 DNA 片段。综上所述，这些结果表明，屎肠球菌 S6 和 R9 的部分纯化细菌素可能有益于控制乳制品行业的李斯特菌。
