College of Life Sciences and Food Engineering, Inner Mongolia Minzu University, Tongliao, 028042, People's Republic of China.
College of Agriculture, Inner Mongolia Minzu University, Tongliao, 028042, People's Republic of China.
Folia Microbiol (Praha). 2023 Dec;68(6):855-866. doi: 10.1007/s12223-023-01060-0. Epub 2023 May 9.
Lactobacillus plantarum NMD-17 separated from koumiss could produce a bacteriocin named plantaricin MX against Gram-positive bacteria and Gram-negative bacteria. The bacteriocin synthesis of L. plantarum NMD-17 was remarkably induced in co-cultivation with Lactobacillus reuteri NMD-86 as the increase of cell numbers and AI-2 activity, and the expressions of luxS encoding signal AI-2 synthetase, plnB encoding histidine protein kinase, plnD encoding response regulator, and plnE and plnF encoding structural genes of bacteriocin were significantly upregulated in co-cultivation, showing that the bacteriocin synthesis of L. plantarum NMD-17 in co-cultivation may be regulated by LuxS/AI-2-mediated quorum sensing system. In order to further demonstrate the role of LuxS/AI-2-mediated quorum sensing system in the bacteriocin synthesis of L. plantarum NMD-17, plasmids pUC18 and pMD18-T simple were used as the skeleton to construct the suicide plasmids pUC18-UF-tet-DF and pMD18-T simple-plnB-tet-plnD for luxS and plnB-plnD gene deletion, respectively. luxS and plnB-plnD gene knockout mutants were successfully obtained by homologous recombination. luxS gene knockout mutant lost its AI-2 synthesis ability, suggesting that LuxS protein encoded by luxS gene is key enzyme for AI-2 synthesis. plnB-plnD gene knockout mutant lost the ability to synthesize bacteriocin against Salmonella typhimurium ATCC14028, indicating that plnB-plnD gene was a necessary gene for bacteriocin synthesis of L. plantarum NMD-17. Bacteriocin synthesis, cell numbers, and AI-2 activity of luxS or plnB-plnD gene knockout mutants in co-cultivation with L. reuteri NMD-86 were obviously lower than those of wild-type strain in co-cultivation at 6-9 h (P < 0.01). The results showed that LuxS/AI-2-mediated quorum sensing system played an important role in the bacteriocin synthesis of L. plantarum NMD-17 in co-cultivation.
从马奶酒中分离出的植物乳杆菌 NMD-17 可以产生一种针对革兰氏阳性菌和革兰氏阴性菌的细菌素，命名为植物乳杆菌素 MX。在与乳酸乳球菌 NMD-86 共培养时，植物乳杆菌 NMD-17 的细菌素合成显著增加，细胞数量和 AI-2 活性增加，并且 luxS 编码信号 AI-2 合成酶、plnB 编码组氨酸蛋白激酶、plnD 编码反应调节蛋白、plnE 和 plnF 编码细菌素结构基因的表达显著上调，表明共培养时植物乳杆菌 NMD-17 的细菌素合成可能受 LuxS/AI-2 介导的群体感应系统调控。为了进一步证明 LuxS/AI-2 介导的群体感应系统在植物乳杆菌 NMD-17 细菌素合成中的作用，将 pUC18 和 pMD18-T simple 质粒分别作为骨架构建自杀质粒 pUC18-UF-tet-DF 和 pMD18-T simple-plnB-tet-plnD，用于 luxS 和 plnB-plnD 基因缺失。通过同源重组成功获得 luxS 和 plnB-plnD 基因敲除突变体。luxS 基因敲除突变体失去 AI-2 合成能力，表明 luxS 基因编码的 LuxS 蛋白是 AI-2 合成的关键酶。plnB-plnD 基因敲除突变体失去了对鼠伤寒沙门氏菌 ATCC14028 的抑菌素合成能力，表明 plnB-plnD 基因是植物乳杆菌 NMD-17 抑菌素合成的必需基因。在与乳酸乳球菌 NMD-86 共培养时，luxS 或 plnB-plnD 基因敲除突变体的抑菌素合成、细胞数量和 AI-2 活性在 6-9 h 时明显低于野生型菌株（P < 0.01）。结果表明，LuxS/AI-2 介导的群体感应系统在植物乳杆菌 NMD-17 的共培养中对抑菌素合成起着重要作用。
