Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang, 310018, People's Republic of China.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
Appl Microbiol Biotechnol. 2020 Jun;104(12):5283-5292. doi: 10.1007/s00253-020-10503-4. Epub 2020 Apr 19.
Salmonella is a serious foodborne pathogen responsible for more than 90 million cases of gastroenteritis worldwide annually. Due to the gradual increase in antibiotic-resistant Salmonella strains, the identification of natural antibacterial substances is urgently needed. Herein, we purified natural L-phenyl lactic acid (L-PLA) from Lactobacillus plantarum ZJ316 and revealed its antimicrobial mode against Salmonella enterica subsp. enterica ATCC 14028. L-PLA (98.14% pure) was obtained using the macroporous resin XAD-16, solid-phase extraction (SPE), reverse-phase high-performance liquid chromatography (RP-HPLC), and chiral chromatography. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that the cell morphology was severely compromised. Transmembrane electrical potential (ΔΨ), transmembrane pH gradient (ΔpH), intracellular ATP level, extracellular electrical conductivity (EC), and genomic DNA analyses were employed to evaluate the antibacterial mode of action of L-PLA. The proton motive force (PMF) and ATP of Salmonella cells rapidly dissipated, and the EC markedly increased. The gel retardation assay demonstrated that L-PLA could bind to genomic DNA and intercalate into the nucleic acids. The anti-Salmonella mode of action of L-PLA was attributed to the destruction of the cell membrane and genomic DNA binding. This research suggests that L-PLA has potential applications as an antimicrobial agent in food, medicine, and other fields. KEY POINTS: • Natural L-PLA was purified from L. plantarum ZJ316 with a purity of 98.14%. • L-PLA effectively inhibited Salmonella strains by antibacterial activities and MICs. • Membrane destruction and binding with DNA are the anti-Salmonella modes of L-PLA.
沙门氏菌是一种严重的食源性病原体，每年在全球导致超过 9000 万例肠胃炎。由于对抗生素耐药性沙门氏菌菌株的逐渐增加，迫切需要鉴定天然抗菌物质。在此，我们从植物乳杆菌 ZJ316 中纯化了天然 L-苯乳酸（L-PLA），并揭示了其对肠炎沙门氏菌亚种。肠沙门氏菌 ATCC 14028 的抗菌模式。使用大孔树脂 XAD-16、固相萃取（SPE）、反相高效液相色谱（RP-HPLC）和手性色谱法获得纯度为 98.14%的 L-PLA。扫描电子显微镜（SEM）和透射电子显微镜（TEM）结果表明细胞形态严重受损。跨膜电势（ΔΨ）、跨膜 pH 梯度（ΔpH）、细胞内 ATP 水平、细胞外电导率（EC）和基因组 DNA 分析用于评估 L-PLA 的抗菌作用模式。沙门氏菌细胞的质子动力势（PMF）和 ATP 迅速耗散，EC 明显增加。凝胶阻滞实验表明 L-PLA 可以与基因组 DNA 结合并嵌入核酸。L-PLA 对沙门氏菌的作用模式归因于细胞膜的破坏和与基因组 DNA 的结合。这项研究表明，L-PLA 有可能作为一种抗菌剂应用于食品、医药和其他领域。关键点： • 从 L. plantarum ZJ316 中纯化出天然 L-PLA，纯度为 98.14%。 • L-PLA 通过抗菌活性和 MIC 有效抑制沙门氏菌菌株。 • 膜破坏和与 DNA 的结合是 L-PLA 的抗沙门氏菌模式。
