摘要

食品中腐败菌和食源性致病菌的多药耐药菌株急需有效的生物防腐剂控制。本研究从Jiangshui分离得到XN8菌株，并根据16S rRNA基因序列鉴定其为棒状乳酸杆菌。通过硫酸铵沉淀和一系列色谱柱纯化XN8产生的细菌素，并命名为乳霉素XN-A（LXA）。用MALDI-TOF MS测定LXA的分子量为3100.0242 Da，LXA表现出良好的热、pH和贮存稳定性。然而，它对蛋白酶是敏感的。发现LXA在Gram阳性和革兰氏阴性菌（包括多药耐药菌株和单核细胞增生李斯特氏菌）上具有广泛的抗菌谱。大肠杆菌和金黄色葡萄球菌的最小抑菌浓度（MIC）为6.85μg/ml，LXA具有生长曲线和时间杀伤试验的无细胞裂解的杀菌模式。电镜结果显示，LXA破坏了靶细胞的膜通透性，诱导了孔的形成。此外，LXA诱导细胞周期阻滞在G1和G2/M期的细胞周期分析。研究表明，LXA在食品工业中具有潜在的生物防腐剂潜力。

The multidrug-resistant strains of food spoilage bacteria and foodborne pathogenic bacteria in food are badly in need of being controlled by effective bio-preservatives. In this study, the XN8 strain was isolated from Jiangshui and identified as Lactobacillus coryniformisaccording to 16S rRNA gene sequence. One of the bacteriocins produced by XN8 was purified by ammonium sulfate precipitation and a series of chromatographic column, and designated as lactocin XN8-A (LXA). The molecular mass of LXA was 3100.0242 Da by MALDI-TOF MS. The LXA showed good heat, pH and storage stabilities. However, it was sensitive to proteases. The LXA was found to have a broad antimicrobial spectrum on both Gram-positive and Gram-negative bacteria including multidrug-resistant strains and Listeria monocytogenes. Its minimum inhibitory concentration (MIC) for both Escherichia coli andStaphylococcus aureus was 6.85 μg/mL. The LXA had a bactericidal mode without cell lysis by the growth curve and time-kill assay. The results of electron microscope showed that the LXA destroyed membrane permeability and induced pore-formation of target cells. Furthermore, the LXA induced cell cycle arrest at both G1 and G2/M phase by cell cycle analysis. This research suggests that the LXA has promising potential as bio-preservative in food industry.

https://www.sciencedirect.com/science/article/pii/S0956713516300548