Extracellular vesicles are produced by species across all domains of life, suggesting that vesiculation represents a fundamental principle of living matter. In Gram-negative bacteria, membrane vesicles (MVs) can originate either from blebs of the outer membrane or from endolysin-triggered explosive cell lysis, which is often induced by genotoxic stress. Although less is known about the mechanisms of vesiculation in Gram-positive and Gram-neutral bacteria, recent research has shown that both lysis and blebbing mechanisms also exist in these organisms. Evidence has accumulated over the past years that different biogenesis routes lead to distinct types of MV with varied structure and composition. In this Review, we discuss the different types of MV and their potential cargo packaging mechanisms. We summarize current knowledge regarding how MV composition determines their various functions including support of bacterial growth via the disposal of waste material, nutrient scavenging, export of bioactive molecules, DNA transfer, neutralization of phages, antibiotics and bactericidal functions, delivery of virulence factors and toxins to host cells and inflammatory and immunomodulatory effects. We also discuss the advantages of MV-mediated secretion compared with classic bacterial secretion systems and we introduce the concept of quantal secretion.

细胞外囊泡由生命各个领域的物种产生，这表明囊泡形成代表了生命物质的基本原理。在革兰氏阴性细菌中，膜囊泡 (MV) 可能源自外膜气泡，也可能源自内溶素触发的爆炸性细胞裂解，这通常是由基因毒性应激引起的。尽管人们对革兰氏阳性和革兰氏中性细菌中的囊泡形成机制知之甚少，但最近的研究表明，这些生物体中也存在裂解和起泡机制。过去几年积累的证据表明，不同的生物发生途径导致不同类型的MV具有不同的结构和组成。在这篇评论中，我们讨论了不同类型的 MV 及其潜在的货物包装机制。我们总结了有关 MV 组成如何决定其各种功能的当前知识，包括通过废物处理支持细菌生长、营养物清除、生物活性分子输出、DNA 转移、噬菌体中和、抗生素和杀菌功能、毒力因子和毒素的传递对宿主细胞以及炎症和免疫调节作用。我们还讨论了 MV 介导的分泌与经典细菌分泌系统相比的优势，并引入了量子分泌的概念。将毒力因子和毒素递送至宿主细胞以及炎症和免疫调节作用。我们还讨论了 MV 介导的分泌与经典细菌分泌系统相比的优势，并引入了量子分泌的概念。将毒力因子和毒素递送至宿主细胞以及炎症和免疫调节作用。我们还讨论了 MV 介导的分泌与经典细菌分泌系统相比的优势，并引入了量子分泌的概念。