In this study, the presence of plasmids responsible for carbohydrate fermentation and antibiotic resistance and the stability of these plasmids in artificial gastric juice were investigated in 20 Lactobacillus plantarum strains with probiotic properties. Plasmid curing was performed with novobiocin, acriflavine and elevated incubation temperature to identify plasmids encoded with carbohydrate fermentation and antibiotic resistance genes and to compare them with artificial gastric juice. Plasmid profiling of the strains revealed that 100% of the strains were harbouring plasmids in varying sizes and numbers. The plasmid number of the potential probiotic strains ranged between 1 and 4, and the plasmid size ranged between 5.779 and 16.138 kb. The potential probiotic strains could not survive in the artificial gastric juice at pH 2.0. Although the strains maintained their viability in an artificial gastric juice at pH 2.5 and 3.0, and their derivatives lost their plasmids at a high rate (100%). Similarly, high levels of cured derivatives were obtained with 8 µg/mL novobiocin and 100 µg/mL acriflavine applications, and 24 h incubation at 43 °C. All the experiments were also performed to compare with two L. plantarum -type strains containing plasmids responsible for tetracycline and tetracycline + erythromycin resistances. Artificial gastric juice and other plasmid curing treatments caused a high-frequency loss in the antibiotic resistances of type strains. Determining plasmid stability in artificial gastric juice is a novel approach. Plasmid stability in the gastrointestinal tract is important for maintaining the plasmid-encoded probiotic properties.

中文翻译：

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潜在益生菌植物乳杆菌菌株在人造胃液中的质粒稳定性，在升高的温度下，在新生霉素和吖啶黄的存在下

在这项研究中，在 20 种具有益生菌特性的植物乳杆菌菌株中研究了负责碳水化合物发酵和抗生素抗性的质粒的存在以及这些质粒在人工胃液中的稳定性。用新生霉素、吖啶黄和升高的孵育温度进行质粒固化，以鉴定由碳水化合物发酵和抗生素抗性基因编码的质粒，并将它们与人工胃液进行比较。菌株的质粒分析表明，100% 的菌株含有不同大小和数量的质粒。潜在益生菌菌株的质粒数介于 1 和 4 之间，质粒大小介于 5.779 和 16.138 kb 之间。潜在的益生菌菌株无法在 pH 2.0 的人工胃液中存活。尽管这些菌株在 pH 2.5 和 3.0 的人工胃液中保持其活力，但它们的衍生物以高速率 (100%) 丢失质粒。同样，应用 8 µg/mL 新生霉素和 100 µg/mL 吖啶黄并在 43 °C 下孵育 24 小时，获得了高水平的固化衍生物。还进行了所有实验以与包含负责四环素和四环素+红霉素抗性的质粒的两种植物乳杆菌型菌株进行比较。人工胃液和其他质粒治疗导致典型菌株抗生素耐药性的高频丢失。确定人工胃液中质粒的稳定性是一种新方法。胃肠道中的质粒稳定性对于维持质粒编码的益生菌特性很重要。