Bacteria that belong to the family Roseobacteraceae in the Alphaproteobacteria class are widely distributed in marine environments with remarkable physiological diversity, which is considered to be attributed to their genomic plasticity. In this study, a novel isolate of the genus Sagittula within Roseobacteraceae, strain MA-2, was obtained from a coastal marine bacterial consortium enriched with aromatic hydrocarbons, and its complete genome was sequenced. The genome with a total size of 5.69 Mbp was revealed to consist of a 4.67-Mbp circular chromosome and eight circular plasmids ranging in size from 19.5 to 361.5 kbp. Further analyses of functional genes in the strain MA-2 genome identified homologous genes responsible for the biotransformation of gentisic acid, which were located on one of its plasmids and were not found in genomes of other Sagittula strains available from databases. This suggested that strain MA-2 had acquired these genes via horizontal gene transfers that enabled them to degrade and utilize gentisic acid as a growth substrate. This study provided the second complete genome sequence of the genus Sagittula and supports the hypothesis that acquisition of ecologically relevant genes in extrachromosomal replicons allows Roseobacteraceae to be highly adaptable to diverse lifestyles.

属于阿尔法变形菌纲玫瑰杆菌科的细菌广泛分布在海洋环境中，具有显着的生理多样性，这被认为归因于其基因组可塑性。在这项研究中，从富含芳香烃的沿海海洋细菌群落中获得了玫瑰杆菌科射手属的一个新分离株，即MA-2菌株，并对其完整基因组进行了测序。总大小为 5.69 Mbp 的基因组由一条 4.67 Mbp 的环状染色体和 8 个大小从 19.5 kbp 到 361.5 kbp 不等的环状质粒组成。对菌株 MA-2 基因组中功能基因的进一步分析确定了负责龙胆酸生物转化的同源基因，这些基因位于其质粒之一上，并且在数据库中提供的其他Sagittula菌株的基因组中没有发现。这表明菌株 MA-2 通过水平基因转移获得了这些基因，使它们能够降解并利用龙胆酸作为生长底物。这项研究提供了箭属的第二个完整基因组序列，并支持了这样的假设：在染色体外复制子中获得生态相关基因使玫瑰杆菌科能够高度适应不同的生活方式。