Plasmid persistence in bacterial populations is strongly influenced by the fitness effects associated with plasmid carriage. However, plasmid fitness effects in wild-type bacterial hosts remain largely unexplored. In this study, we determined the distribution of fitness effects (DFE) for the major antibiotic resistance plasmid pOXA-48 in wild-type, ecologically compatible enterobacterial isolates from the human gut microbiota. Our results show that although pOXA-48 produced an overall reduction in bacterial fitness, the DFE was dominated by quasi-neutral effects, and beneficial effects were observed in several isolates. Incorporating these data into a simple population dynamics model revealed a new set of conditions for plasmid stability in bacterial communities, with plasmid persistence increasing with bacterial diversity and becoming less dependent on conjugation. Moreover, genomic results showed a link between plasmid fitness effects and bacterial phylogeny, helping to explain pOXA-48 epidemiology. Our results provide a simple and general explanation for plasmid persistence in natural bacterial communities.

中文翻译：

---

质粒适应性效应的分布可解释质粒在细菌群落中的持久性

质粒在细菌种群中的持久性受到与质粒运输相关的适应性影响的强烈影响。但是，在野生型细菌宿主中质粒适应性的影响仍未开发。在这项研究中，我们确定了主要的抗生素抗性质粒pOXA-48在人类肠道菌群的野生型，生态相容性肠细菌分离物中的适应性效应（DFE）的分布。我们的结果表明，尽管pOXA-48导致细菌适应性总体降低，但DFE主要受准中性作用的影响，并且在几种分离物中都观察到了有益作用。将这些数据整合到简单的种群动态模型中，揭示了细菌群落中质粒稳定性的一组新条件，质粒的持久性随着细菌多样性的增加而增加，而对缀合的依赖性降低。此外，基因组结果显示质粒适应性效应和细菌系统发育之间的联系，有助于解释pOXA-48流行病学。我们的结果为质粒在天然细菌群落中的持久性提供了简单而通用的解释。