含有聚酮合酶 (Pks) 岛的大肠杆菌菌株编码基因毒素 colibactin，这是一种次级代谢产物，据报道对人类健康和结直肠癌的进展具有严重影响。本研究涉及对含有大肠杆菌分离株的 pks 进行全基因组比较和系统发育分析，以深入了解这些生物体的分布和进化。对从溃疡性结肠炎患者体内分离出的 15 株大肠杆菌菌株进行了测序，其中 13 株含有 pks 岛。此外，还对公共数据库中的 2,654 个基因组进行了含有大肠杆菌基因组的 pks 筛选，其中 158 个是 pks 阳性分离株。全基因组比较和系统发育分析表明，171 (158 13) 个 pks 阳性分离株属于系统群 B2，并且大多数分离株与序列类型 ST73 和 ST95 相关。来自溃疡性结肠炎 (UC) 患者的一种分离株的序列类型为 ST8303。基于 pks 阳性分离株核心基因组的最大似然树揭示了跨序列类型和血清型的水平基因转移。病毒组和抗药性组分析揭示了 Pks 阳性分离株中毒力基因的优势和抗菌基因数量的减少。这项研究极大地有助于了解大肠杆菌中 pks 岛的进化。

The E. coli strain harboring the polyketide synthase ( Pks) island encodes the genotoxin colibactin, a secondary metabolite reported to have severe implications for human health and for the progression of colorectal cancer. The present study involved whole-genome-wide comparison and phylogenetic analysis of pks harboring E. coli isolates to gain insight into the distribution and evolution of these organism. Fifteen E. coli strains isolated from patients with ulcerative colitis were sequenced, 13 of which harbored pks islands. In addition, 2,654 genomes from the public database were also screened for pks harboring E. coli genomes, 158 of which were pks -positive isolates. Whole-genome-wide comparison and phylogenetic analysis revealed that 171 (158+13) pks -positive isolates belonged to phylogroup B2, and most of the isolates associated to sequence types ST73 and ST95. One isolate from an ulcerative colitis (UC) patient was of the sequence type ST8303. The maximum likelihood tree based on the core genome of pks -positive isolates revealed horizontal gene transfer across sequence types and serotypes. Virulome and resistome analyses revealed the preponderance of virulence genes and a reduced number of antimicrobial genes in Pks -positive isolates. This study strongly contributes to understanding the evolution of pks islands in E. coli .