Induction mechanisms and strategies underlying interprophage competition during polylysogeny
Justin E. Silpe, Olivia P. Duddy, Bonnie L. Bassler
Abstract
Phages play central roles in shaping bacterial community biology. For example, lytic phages, by eliminating particular subpopulations of bacteria, control the composition of bacterial biofilm communities Temperate phages can infect and persist in bacteria, a state called lysogeny As inhabitants, lysogenic phages drive bacterial genome evolution via the introduction of viral genes that endow the hosts with new capabilities or that regulate host biochemical or signaling pathways. For instance, some cyanophages encode photosystem components that enhance host light harvesting ability In Shigella flexneri, phage-encoded enzymes modify O-antigen sugars enabling serotype conversion Similarly, phage enzymes hydrolyze the polysaccharide in the Acinetobacter baumannii capsule, altering biofilm formation Underscoring their importance to human health, temperate phages supply their bacterial hosts with the toxin-encoding genes responsible for diseases including cholera (caused by phage CTX of Vibrio cholerae), dysentery (caused by STX phages of Escherichia coli), diphtheria (caused by phage beta of Corynebacterium diphtheriae), and botulism (caused by neurotoxin-encoding phages of Clostridium botulinum) These and other examples highlight fascinating connections between phage biology and bacterial biology. In some cases, phage infection confers benefits to the host bacterium, for example, enhancing colonization or dissemination from eukaryotic hosts. Phages are also frequently bacterial parasites, and, consequently, bacteria are under the pervasive threat of infection by phages that can exploit resources for continued propagation and, moreover, that can kill host bacteria in response to particular conditions.