Data from: Progressive genome-wide introgression in agricultural Campylobacter coli

Hybridization between distantly related organisms can facilitate rapid adaptation to novel environments, but is potentially constrained by epistatic fitness interactions among cell components. The zoonotic pathogens Campylobacter coli and C. jejuni differ from each other by around 15% at the nucleotide level, corresponding to an average of nearly 40 amino acids per protein-coding gene. Using whole genome sequencing, we show that a single C. coli lineage, which has successfully colonized an agricultural niche, has been progressively accumulating C. jejuni DNA. Members of this lineage belong to two groups, the ST-828 and ST-1150 clonal complexes. The ST-1150 complex is less frequently isolated and has undergone a substantially greater amount of introgression leading to replacement of up to 23% of the C. coli core genome as well as import of novel DNA. By contrast, the more commonly isolated ST-828 complex bacteria have 10–11% introgressed DNA, and C. jejuni and nonagricultural C. coli lineages each have <2%. Thus, the C. coli that colonize agriculture, and consequently cause most human disease, have hybrid origin, but this cross-species exchange has so far not had a substantial impact on the gene pools of either C. jejuni or nonagricultural C. coli. These findings also indicate remarkable interchangeability of basic cellular machinery after a prolonged period of independent evolution.远缘生物间的杂交可助力其快速适应全新环境，但细胞组分间的上位性适合度相互作用（epistatic fitness interactions）可能会限制这一过程。人畜共患病原体（zoonotic pathogen）结肠弯曲杆菌（Campylobacter coli）与空肠弯曲杆菌（Campylobacter jejuni）在核苷酸水平上的差异约为15%，对应每个蛋白质编码基因平均存在近40个氨基酸的差异。本研究借助全基因组测序（whole genome sequencing）技术证实，某一成功定殖于农业生态位的结肠弯曲杆菌谱系，正持续获得空肠弯曲杆菌的基因组DNA片段。该谱系包含两个类群，即ST-828克隆复合体（clonal complex）与ST-1150克隆复合体。其中ST-1150克隆复合体的分离率较低，但其经历的基因渐渗（introgression）程度显著更高，其基因组中多达23%的结肠弯曲杆菌核心基因组（core genome）序列被替换，同时还导入了全新的外源DNA。与之形成对照的是，分离更为普遍的ST-828克隆复合体菌株仅携带10%~11%的渐渗DNA，而空肠弯曲杆菌与非农业定殖的结肠弯曲杆菌谱系的渐渗DNA占比均低于2%。由此可见，那些定殖于农业环境并因此引发绝大多数人类感染病例的结肠弯曲杆菌菌株，其基因组起源具有杂交特性；但截至目前，这种跨物种的基因交流并未对空肠弯曲杆菌或非农业定殖结肠弯曲杆菌的基因库造成显著影响。本研究结果同时还表明，即便经历了长期的独立进化，细胞的基础功能装置仍具有显著的互换性。