SUMMARY Approximately 10% of bacterial genomes are split between two or more large DNA fragments, a genome architecture referred to as a multipartite genome. This multipartite organization is found in many important organisms, including plant symbionts, such as the nitrogen-fixing rhizobia, and plant, animal, and human pathogens, including the genera Brucella, Vibrio, and Burkholderia. The availability of many complete bacterial genome sequences means that we can now examine on a broad scale the characteristics of the different types of DNA molecules in a genome. Recent work has begun to shed light on the unique properties of each class of replicon, the unique functional role of chromosomal and nonchromosomal DNA molecules, and how the exploitation of novel niches may have driven the evolution of the multipartite genome. The aims of this review are to (i) outline the literature regarding bacterial genomes that are divided into multiple fragments, (ii) provide a meta-analysis of completed bacterial genomes from 1,708 species as a way of reviewing the abundant information present in these genome sequences, and (iii) provide an encompassing model to explain the evolution and function of the multipartite genome structure. This review covers, among other topics, salient genome terminology; mechanisms of multipartite genome formation; the phylogenetic distribution of multipartite genomes; how each part of a genome differs with respect to genomic signatures, genetic variability, and gene functional annotation; how each DNA molecule may interact; as well as the costs and benefits of this genome structure.

发明内容大约10％的细菌基因组被分成两个或更多个大的DNA片段，该基因组架构被称为多部分基因组。这种多方组织存在于许多重要生物中，包括植物共生体，例如固氮根瘤菌，以及植物，动物和人类病原体，包括布鲁氏菌属，弧菌和伯克霍尔德氏菌。。许多完整的细菌基因组序列的可用性意味着我们现在可以大规模检查基因组中不同类型DNA分子的特征。最近的工作已开始阐明每种复制子的独特性质，染色体和非染色体DNA分子的独特功能作用，以及对新型小生境的开发如何驱动多部分基因组的进化。这篇综述的目的是（i）概述有关被分成多个片段的细菌基因组的文献，（ii）对来自1,708个物种的完整细菌基因组进行荟萃分析，以此作为综述这些基因组中大量信息的一种方式（iii）提供了一个涵盖模型，以解释多部分基因组结构的进化和功能。除其他主题外，本综述涵盖了显着的基因组术语；多方基因组形成的机制；多部分基因组的系统发育分布；基因组的每个部分在基因组特征，遗传变异性和基因功能注释方面如何不同；每个DNA分子可能如何相互作用；以及这种基因组结构的成本和收益。