Phages are generally described as species specific or even strain specific, implying an inherent limitation for some to be maintained and spread in diverse bacterial communities. Moreover, phage isolation and host range determination rarely consider the phage ecological context, likely biasing our notion on phage specificity. Here we isolated and characterized a novel group of six promiscuous phages, named Atoyac, existing in rivers and sewage by using a diverse collection of over 600 bacteria retrieved from the same environments as potential hosts. These podophages isolated from different regions in Mexico display a remarkably broad host range, infecting bacteria from six genera: Aeromonas, Pseudomonas, Yersinia, Hafnia, Escherichia, and Serratia. Atoyac phage genomes are ∼42 kb long and highly similar to each other, but not to those currently available in genome and metagenome public databases. Detailed comparison of the phages’ efficiency of plating (EOP) revealed variation among bacterial genera, implying a cost associated with infection of distant hosts, and between phages, despite their sequence similarity. We show, through experimental evolution in single or alternate hosts of different genera, that efficiency of plaque production is highly dynamic and tends toward optimization in hosts rendering low plaque formation. However, adaptation to distinct hosts differed between similar phages; whereas one phage optimized its EOP in all tested hosts, the other reduced plaque production in one host, suggesting that propagation in multiple bacteria may be key to maintain promiscuity in some viruses. Our study expands our knowledge of the virosphere and uncovers bacterium-phage interactions overlooked in natural systems.

中文翻译：

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一组新的混杂足噬菌体感染河流群落中不同的γ-变形菌表现出动态的属间宿主适应

噬菌体通常被描述为物种特异性甚至菌株特异性，这意味着一些在不同细菌群落中维持和传播的固有限制。此外，噬菌体分离和宿主范围确定很少考虑噬菌体的生态环境，这可能会影响我们对噬菌体特异性的看法。在这里，我们通过使用从与潜在宿主相同的环境中检索到的 600 多种细菌的多样化集合，分离并表征了存在于河流和污水中的一组新的六种混杂噬菌体，称为 Atoyac。这些从墨西哥不同地区分离出来的噬菌体表现出非常广泛的宿主范围，感染了六个属的细菌：气单胞菌属、假单胞菌属、耶尔森菌属、哈夫尼亚属、大肠杆菌和沙雷氏菌. Atoyac 噬菌体基因组长约 42 kb，彼此高度相似，但与目前在基因组和宏基因组公共数据库中可用的基因组不同。对噬菌体电镀效率 (EOP) 的详细比较揭示了细菌属之间的差异，这意味着与远距离宿主感染相关的成本，以及噬菌体之间的差异，尽管它们的序列相似。我们通过在不同属的单个或交替宿主中的实验进化表明，斑块产生的效率是高度动态的，并且倾向于在宿主中优化，从而呈现低斑块形成。然而，相似噬菌体对不同宿主的适应不同；而一种噬菌体在所有测试宿主中优化了其 EOP，而另一种噬菌体在一个宿主中减少了噬菌斑的产生，表明在多种细菌中的繁殖可能是维持某些病毒混杂的关键。我们的研究扩展了我们对病毒圈的了解，并揭示了在自然系统中被忽视的细菌-噬菌体相互作用。