Table_1_Comparative Genomics Reveals Evidence of Genome Reduction and High Extracellular Protein Degradation Potential in Kangiella.XLS

The genus Kangiella has recently been proposed within the family Kangiellaceae, belonging to order Oceanospirillales. Here, we report the complete genome sequence of a novel strain, Kangiella profundi FT102, which is the only Kangiella species isolated from a deep sea sediment sample. Furthermore, gaps in the publicly available genome scaffold of K. aquimarina DSM 16071 (NCBI Reference Sequence: NZ_ARFE00000000.1) were also filled using polymerase chain reaction (PCR) and Sanger sequencing. A comparative genomic analysis of five Kangiella and 18 non-Kangiella strains revealed insights into their metabolic potential. It was shown that low genomic redundancy and Kangiella-lineage-specific gene loss are the key reasons behind the genome reduction in Kangiella compared to that in any other free-living Oceanospirillales strain. The occurrence of relatively diverse and more frequent extracellular protease-coding genes along with the incomplete carbohydrate metabolic pathways in the genome suggests that Kangiella has high extracellular protein degradation potential. Growth of Kangiella strains has been observed using amino acids as the only carbon and nitrogen source and tends to increase with additional tryptone. Here, we propose that extracellular protein degradation and amino acid utilization are significant and prominent features of Kangiella. Our study provides more insight into the genomic traits and proteolytic metabolic capabilities of Kangiella.

坎吉拉菌属（Kangiella）最近被归入坎吉拉菌科（Kangiellaceae），隶属于海洋螺菌目（Oceanospirillales）。本研究报道了一株新菌株深海坎吉拉菌（Kangiella profundi）FT102的完整基因组序列，该菌株是目前唯一一株从深海沉积物样品中分离得到的Kangiella属物种。此外，本研究通过聚合酶链式反应（PCR）与桑格测序（Sanger sequencing）填补了已公开的海生坎吉拉菌（K. aquimarina）DSM 16071基因组支架（NCBI参考序列：NZ_ARFE00000000.1）中的序列缺口。本研究对5株Kangiella属菌株与18株非Kangiella属菌株开展比较基因组分析，揭示了该类群的代谢潜能特征。分析表明，相较于其他自由生活的海洋螺菌目菌株，坎吉拉菌属的基因组缩减主要源于较低的基因组冗余度以及属谱系特异性基因丢失这两个关键因素。基因组中存在相对多样且丰度更高的胞外蛋白酶编码基因，同时伴随不完整的碳水化合物代谢通路，这表明坎吉拉菌属具备较强的胞外蛋白质降解能力。实验证实，坎吉拉菌属菌株可仅以氨基酸作为唯一碳源与氮源完成生长，且额外添加胰蛋白胨可促进其生长。据此，本研究提出胞外蛋白质降解与氨基酸利用是坎吉拉菌属的核心且显著的生理特征。本研究进一步深化了对坎吉拉菌属基因组特征与蛋白水解代谢能力的认知。