Bacterial membrane vesicles (MVs) have attracted strong interest in recent years as novel nanoparticle delivery platforms. Glycine is known to induce morphological changes in the outer layer of bacteria. We report here that glycine dramatically facilitates MV production in a flagella‐deficient mutant of the non‐pathogenic probiotic Escherichia coli strain Nissle 1917. Supplementation of culture medium with 1.0% glycine induced cell deformation at the early exponential phase, eventually followed by quasi‐lysis during the late exponential to stationary phase. Glycine supplementation also significantly increased the number of MVs with enlarged particle size and altered the protein profile with an increase in the inner membrane and cytoplasmic protein contents as compared to non‐induced MVs. Of note, the endotoxin activity of glycine‐induced MVs was approximately eightfold or sixfold lower than that of non‐induced MVs when compared at equal protein or lipid concentrations respectively. Nevertheless, glycine‐induced MVs efficiently induced both immune responses in a mouse macrophage‐like cell line and adjuvanticity in an intranasal vaccine mouse model, comparable to those of non‐induced MVs. We propose that the present method of inducing MV production with glycine can be used for emerging biotechnological applications of MVs that have immunomodulatory activities, while dramatically reducing the presence of endotoxins.

中文翻译：

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甘氨酸显着增强细菌膜囊泡的产生：一种分离LPS减少的益生菌大肠杆菌膜囊泡的有力方法。

近年来，细菌膜囊泡（MVs）作为新型纳米颗粒递送平台引起了人们的强烈兴趣。已知甘氨酸可诱导细菌外层的形态变化。我们在这里报告，甘氨酸极大地促进了非致病性益生菌大肠杆菌的鞭毛缺陷突变体中的MV生产。Nissle菌株1917。在指数初期，向培养基中添加1.0％甘氨酸诱导细胞变形，最后在指数后期至固定期进行准裂解。与未诱导的MV相比，补充甘氨酸还显着增加了MV的数量，并增加了粒径，并随着内膜和细胞质蛋白含量的增加而改变了蛋白质谱。值得注意的是，当分别在相同的蛋白质或脂质浓度下进行比较时，甘氨酸诱导的MV的内毒素活性比未诱导的MV低约八倍或六倍。然而，与未诱导的MV相当，甘氨酸诱导的MV可有效诱导小鼠巨噬细胞样细胞系的免疫反应和鼻内疫苗小鼠模型的佐剂性。