Castledine Meaghan, Padfield Daniel, Lewis Rai, Buckling Angus
College of Life and Environmental Sciences, Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9EZ, United Kingdom.
FEMS Microbiol Ecol. 2025 Mar 18;101(4). doi: 10.1093/femsec/fiaf027.
Lytic bacteriophages ('phages') can limit bacterial densities and shape community structure, either directly through lysis or indirectly through costs to resistance. However, phages have also been reported to have no, and in some cases even positive, effects on host densities. Here, we investigate the mechanisms behind an increase in host density in Variovorax sp. populations following a fixation of resistance that was maintained after phage extinction. Our results demonstrate that the density increase was a genetic trait coinciding with resistance emergence. Growth curves showed that phage resistance shifted population growth curves such that density was higher in the death phase. This density-increasing effect of resistance had important implications for community structure with phage-resistant Variovorax decreasing the density of a conspecific. That resistance to lytic phage can increase host densities has implications for wider ecology and phage therapy, where lytic phages are presumed to have negative effects on their hosts.
裂解性噬菌体（“噬菌体”）可以直接通过裂解或间接通过抗性代价来限制细菌密度并塑造群落结构。然而，也有报道称噬菌体对宿主密度没有影响，在某些情况下甚至有积极影响。在这里，我们研究了在噬菌体灭绝后抗性固定下来的食酸菌属种群中宿主密度增加背后的机制。我们的结果表明，密度增加是与抗性出现同时出现的一种遗传特征。生长曲线表明，噬菌体抗性使种群生长曲线发生了变化，从而在死亡阶段密度更高。这种抗性的密度增加效应对于群落结构具有重要意义，因为抗噬菌体的食酸菌会降低同种生物的密度。对裂解性噬菌体的抗性能够增加宿主密度，这对更广泛的生态学和噬菌体疗法具有启示意义，因为在这些领域中，裂解性噬菌体被认为会对其宿主产生负面影响。
