Drebes Dörr Natália C, Lemopoulos Alexandre, Blokesch Melanie
Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Genome Biol Evol. 2025 Apr 30;17(5). doi: 10.1093/gbe/evaf079.
Members of the bacterial species Vibrio cholerae are known both as prominent constituents of marine environments and as the causative agents of cholera, a severe diarrheal disease. While strains responsible for cholera have been extensively studied over the past century, less is known about their environmental counterparts, despite their contributions to the species' pangenome. This study analyzed the genome compositions of 46 V. cholerae strains, including pandemic and nonpandemic, toxigenic, and environmental variants, to investigate the diversity of mobile genetic elements (MGEs), embedded bacterial defense systems, and phage-associated signatures. Our findings include both conserved and novel MGEs across strains, pointing to shared evolutionary pathways and ecological niches. The defensome analysis revealed a wide array of antiphage/antiplasmid mechanisms, extending well beyond the traditional CRISPR-Cas and restriction-modification systems. This underscores the dynamic arms race between V. cholerae and MGEs and suggests that nonpandemic strains may act as reservoirs for emerging defense strategies. Moreover, the study showed that MGEs are integrated into genomic hotspots, which may serve as critical platforms for the exchange of defense systems, thereby enhancing V. cholerae's adaptive capabilities against phage attacks and other invading MGEs. Overall, this research offers new insights into V. cholerae's genetic complexity and potential adaptive strategies, offering a better understanding of the differences between environmental strains and their pandemic counterparts, as well as the possible evolutionary pathways that led to the emergence of pandemic strains.
霍乱弧菌这一细菌物种的成员,既被认为是海洋环境中的重要组成部分,也是霍乱(一种严重腹泻疾病)的病原体。尽管在过去一个世纪里,引发霍乱的菌株已得到广泛研究,但对于它们在环境中的对应菌株却知之甚少,尽管这些环境菌株对该物种的泛基因组有贡献。本研究分析了46株霍乱弧菌的基因组组成,包括大流行和非大流行、产毒和环境变体,以研究移动遗传元件(MGEs)、嵌入式细菌防御系统和噬菌体相关特征的多样性。我们的发现包括各菌株间保守和新颖的MGEs,这表明存在共同的进化途径和生态位。防御组分析揭示了广泛的抗噬菌体/抗质粒机制,远远超出了传统的CRISPR-Cas和限制修饰系统。这突出了霍乱弧菌与MGEs之间动态的军备竞赛,并表明非大流行菌株可能充当新兴防御策略的储存库。此外,该研究表明MGEs整合到基因组热点中,这些热点可能作为防御系统交换的关键平台,从而增强霍乱弧菌对噬菌体攻击和其他入侵MGEs的适应能力。总体而言,这项研究为霍乱弧菌的遗传复杂性和潜在适应策略提供了新的见解,有助于更好地理解环境菌株与其大流行对应菌株之间的差异,以及导致大流行菌株出现的可能进化途径。