1Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland.
2Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Québec City, QC Canada.
Commun Biol. 2019 Nov 4;2:405. doi: 10.1038/s42003-019-0633-x. eCollection 2019.
Bacterial viruses, or phage, are key members of natural microbial communities. Yet much research on bacterial-phage interactions has been conducted in liquid cultures involving single bacterial strains. Here we explored how bacterial diversity affects the success of lytic phage in structured communities. We infected a sensitive strain PAO1 with a lytic phage Pseudomonas 352 in the presence versus absence of an insensitive strain PA14, in liquid culture versus colonies on agar. We found that both in liquid and in colonies, inter-strain competition reduced resistance evolution in the susceptible strain and decreased phage population size. However, while all sensitive bacteria died in liquid, bacteria in colonies could remain sensitive yet escape phage infection, due mainly to reduced growth in colony centers. In sum, spatial structure can protect bacteria against phage infection, while the presence of competing strains reduces the evolution of resistance to phage.
细菌病毒，又称噬菌体，是自然微生物群落的关键成员。然而，许多关于细菌-噬菌体相互作用的研究都是在涉及单一细菌株的液体培养中进行的。在这里，我们探讨了细菌多样性如何影响裂解噬菌体在结构化群落中的成功。我们在有和没有不敏感菌株 PA14 的情况下，在液体培养和琼脂培养的条件下，用裂解噬菌体 Pseudomonas 352 感染敏感菌株 PAO1。我们发现，在液体和菌落中，种间竞争都降低了敏感菌株的抗性进化速度，并减少了噬菌体种群数量。然而，虽然所有敏感细菌在液体中都死亡，但由于菌落中心的生长减少，菌落中的细菌可以保持敏感性但逃避噬菌体感染。总之，空间结构可以保护细菌免受噬菌体感染，而竞争菌株的存在则降低了细菌对噬菌体的抗性进化速度。
