Members of lactic acid bacteria group are known to produce various antimicrobial substances. Cyclic lipopeptides are one such potent class of amphipathic natural biosurfactants that exhibit bactericidal and immunomodulatory properties. In this study, we aimed to investigate antimicrobial and immunomodulatory activities of a lipopeptide secreted by a LAB isolate strain M31 identified as a member of the genus Lactobacillus. The lipopeptide that was purified using a combination of chromatographic techniques and matrix-assisted laser desorption/ionization-time of flight of pure lipopeptide displayed a molecular weight of 1002 Da. MS/MS analysis confirmed the presence of 7 amino acids (Asp-Tyr-Asp-Val-Pro-Asp-Ser) and a C13 beta-hydroxy fatty acid. The amino acid composition assigned lipopeptide to iturin class. However, the replacement of Gln with Val revealed it to represent a novel iturin named as iturin V. Iturin V showed antibacterial activity and did not cause hemolysis or cytotoxicity upto 125 µg/mL. It induced secretion of pro-inflammatory cytokines TNF-alpha and IL-12 in murine dendritic cells. Probiotic features of strain M31 coupled with notable activity of iturin V against species of the genera Pseudomonas and Vibrio suggest that strain M31 has potential application for pathogen intervention treatments in processing of aquatic food products.

众所周知，乳酸菌群的成员会产生各种抗菌物质。环状脂肽是一类有效的两亲性天然生物表面活性剂，具有杀菌和免疫调节特性。在这项研究中，我们旨在研究被鉴定为乳酸杆菌属成员的 LAB 分离菌株 M31 分泌的脂肽的抗菌和免疫调节活性. 使用色谱技术和基质辅助激光解吸/电离-纯脂肽飞行时间的组合纯化的脂肽显示出 1002 Da 的分子量。MS/MS 分析证实存在 7 个氨基酸 (Asp-Tyr-Asp-Val-Pro-Asp-Ser) 和 C13 β-羟基脂肪酸。氨基酸组成将脂肽归为伊图林类。然而，用 Val 替代 Gln 表明它代表了一种名为 iturin V 的新型伊图林。伊图林 V 显示出抗菌活性，并且在高达 125 µg/mL 时不会引起溶血或细胞毒性。它在鼠树突状细胞中诱导促炎细胞因子 TNF-α 和 IL-12 的分泌。菌株 M31 的益生菌特征与伊图林 V 对假单胞菌属和Vibrio表明菌株 M31 在水产品加工中的病原体干预治疗中具有潜在应用。