Burns Nicola, James Chloe E, Harrison Ellie
Department of Biology, University of York York, UK.
Biomedical Science Research Center, University of Salford Salford, UK.
Evol Appl. 2015 Apr;8(4):346-51. doi: 10.1111/eva.12243. Epub 2015 Feb 27.
The rise of next generation sequencing is revealing a hidden diversity of temperate phages within the microbial community. While a handful of these phages have been well characterized, for the vast majority, the role of phage carriage, and especially multiple phage carriage, is poorly understood. The Liverpool epidemic strain of Pseudomonas aeruginosa is an aggressive pathogen in cystic fibrosis lung infections that has recently been found to contain several unique prophages within its genome. Here, we experimentally investigate the role of two of these phages in vivo, using an insect model of infection. We find that while no benefit is conferred by phage carriage in single bacterial infections, phages confer a large fitness advantage during mixed infections by mediating bacteria-bacteria competition. Differences between the two phages appeared to be associated with the rate at which the competitor acquired the phage, and therefore resistance. However, the advantage was greatest in the polylysogen, carrying both phages. These findings suggest that the LES phages may play an important role in host invasions and more generally show that the carriage of multiple phages may itself be beneficial by hindering the spread of resistance in rival bacterial populations.
新一代测序技术的兴起揭示了微生物群落中温带噬菌体隐藏的多样性。虽然其中少数噬菌体已得到充分表征，但对于绝大多数噬菌体而言，噬菌体携带尤其是多重噬菌体携带的作用却知之甚少。铜绿假单胞菌的利物浦流行菌株是囊性纤维化肺部感染中的一种侵袭性病原体，最近发现其基因组中含有几种独特的前噬菌体。在此，我们使用昆虫感染模型对其中两种噬菌体在体内的作用进行了实验研究。我们发现，在单一细菌感染中，携带噬菌体并无益处，但在混合感染期间，噬菌体通过介导细菌间竞争赋予了很大的适应性优势。两种噬菌体之间的差异似乎与竞争者获得噬菌体的速率相关，进而与抗性相关。然而，在携带两种噬菌体的多溶原菌中优势最大。这些发现表明，LES噬菌体可能在宿主入侵中发挥重要作用，更普遍地表明，携带多重噬菌体本身可能通过阻碍抗性在竞争细菌群体中的传播而有益。
