Anderson Orlagh H, Chong James P J, Thomas Gavin H
Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
Microb Genom. 2025 Aug;11(8). doi: 10.1099/mgen.0.001477.
Bacteria from the species encompass a diverse range of phenotypes. While some strains are used as probiotics, others have been isolated from cases of botulism and necrotizing enterocolitis (NEC) in preterm neonates. We identify a unique genomic feature of this species, namely a highly conserved extrachromosomal element of ~0.8 Mb. This replicon satisfies the three principal criteria used to define a chromid, which include the possession of core genes that are encoded on the main chromosome in other species. Although is the type species of , we find that the possession of a chromid is not a typical feature of members of this genus and represents a unique genomic fingerprint of the species . Furthermore, we show that pathogenic strains from the sequenced examples are not monophyletic, which suggests that virulence has evolved multiple times from related non-pathogenic ancestors. However, we were able to identify common genes which are found exclusively in these pathogenic strains. In addition to the botulinum neurotoxin genes, these include a novel set of genes involved in the biosynthesis of a capsular polysaccharide (CPS), and genes that confer the ability to utilize the mucin-derived sugar l-fucose, which may provide a competitive advantage for growth in the colon. Moreover, by identifying NEC strain-associated virulence factors, we are able to further the understanding of these particularly harmful strains.
该物种的细菌具有多种不同的表型。虽然一些菌株被用作益生菌，但其他菌株已从早产儿肉毒中毒和坏死性小肠结肠炎（NEC）病例中分离出来。我们鉴定出该物种的一个独特基因组特征，即一个约0.8 Mb的高度保守的染色体外元件。这个复制子满足用于定义染色体外基因座的三个主要标准，其中包括拥有在其他物种的主要染色体上编码的核心基因。虽然[具体物种名称1]是[具体物种名称2]的模式种，但我们发现拥有染色体外基因座并非该属成员的典型特征，而是[具体物种名称1]物种独特的基因组指纹。此外，我们表明，来自已测序实例的致病性[具体物种名称1]菌株并非单系的，这表明毒力已从相关的非致病性祖先多次进化而来。然而，我们能够鉴定出仅在这些致病菌株中发现的共同基因。除了肉毒杆菌神经毒素基因外，这些基因还包括一组参与荚膜多糖（CPS）生物合成的新基因，以及赋予利用粘蛋白衍生糖L-岩藻糖能力的基因，这可能为在结肠中生长提供竞争优势。此外，通过鉴定与NEC菌株相关的毒力因子，我们能够进一步了解这些特别有害的菌株。
