To date, the phylum Bacteroidetes comprises more than 1,500 described species with diverse ecological roles. However, there is little understanding of archetypal Bacteroidetes traits at a genomic level. In this study, a representative set of 89 Bacteroidetes genomes was compiled, and pairwise reciprocal best-match gene comparisons and gene syntenies were used to identify common traits that allowed Bacteroidetes evolution and adaptive radiation to be traced. The type IX secretion system (T9SS) was highly conserved among all studied Bacteroidetes. Class-level comparisons furthermore suggested that the ACIII-caa₃COX super-complex evolved in the ancestral aerobic bacteroidetal lineage, and was secondarily lost in extant anaerobic Bacteroidetes. Another Bacteroidetes-specific respiratory chain adaptation was the sodium-pumping Nqr complex I that replaced the ancestral proton-pumping complex I in marine species. T9SS plays a role in gliding motility and the acquisition of complex macro-molecular organic compounds, and the ACIII-caa₃COX super-complex allows effective control of electron flux during respiration. This combination likely provided ancestral Bacteroidetes with a decisive competitive advantage to effectively scavenge, uptake and degrade complex organic molecules, and therefore has played a pivotal role in the successful adaptive radiation of the phylum.

迄今为止，拟杆菌门包括超过1,500个具有不同生态作用的所述物种。但是，在基因组水平上对原型拟杆菌的性状了解甚少。在这项研究中，汇编了代表性的89个拟杆菌属基因组，并使用成对的互惠最佳匹配基因比较和基因同义性来鉴定允许追踪拟杆菌的进化和适应性辐射的共同特征。在所有研究的拟杆菌属中， IX型分泌系统（T9SS）是高度保守的。班级比较进一步表明，ACIII-caa ₃COX超复合物在祖先有氧细菌理想谱系中进化，其次在现存的厌氧拟杆菌中丢失。另一种拟杆菌特异的呼吸链适应性是钠泵浦的Nqr复合物I取代了海洋物种中的祖先质子泵浦的复合物I。T9SS在滑行运动和复杂的高分子有机化合物的获取中发挥作用，而ACIII-caa ₃ COX超复合物可有效控制呼吸过程中的电子通量。这种组合可能提供了祖先的拟杆菌 具有决定性的竞争优势，可以有效地清除，吸收和降解复杂的有机分子，因此在门的成功适应性辐射中发挥了关键作用。