Prophages in Salmonella enterica: a driving force in reshaping the genome and physiology of their bacterial host?

Astrid Wahl,Mireille Ansaldi,Aurélia Battesti

doi:10.1111/mmi.14167

Astrid Wahl, Mireille Ansaldi + Show 1 more

Open Access

https://doi.org/10.1111/mmi.14167

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Abstract

SummaryThanks to the exponentially increasing number of publicly available bacterial genome sequences, one can now estimate the important contribution of integrated viral sequences to the diversity of bacterial genomes. Indeed, temperate bacteriophages are able to stably integrate the genome of their host through site‐specific recombination and transmit vertically to the host siblings. Lysogenic conversion has been long acknowledged to provide additional functions to the host, and particularly to bacterial pathogen genomes where prophages contribute important virulence factors. This review aims particularly at highlighting the current knowledge and questions about lysogeny in Salmonella genomes where functional prophages are abundant, and where genetic interactions between host and prophages are of particular importance for human health considerations.

Highlights

Bacteriophages are recognized as the most abundant biological entities on earth, participating to numerous biological cycles and constantly reshaping bacterial communities (Suttle, 2007; Brussaard et al, 2008)
There is no doubt about the extensive repression of prophage genes involved in lytic functions, we argue that it may have occulted the expression of those genes involved in lysogenic conversion and for which no obvious function in metabolic or pathogenic pathways have been identified
What is striking whenever considering and comparing different Salmonella genomes is the diversity of the prophage content as well as the diverse relationships these prophages engage with the host strains

Summary

Thanks to the exponentially increasing number of publicly available bacterial genome sequences, one can estimate the important contribution of integrated viral sequences to the diversity of bacterial genomes. Lysogenic conversion has been long acknowledged to provide additional functions to the host, and to bacterial pathogen genomes where prophages contribute important virulence factors. This review aims at highlighting the current knowledge and questions about lysogeny in Salmonella genomes where functional prophages are abundant, and where genetic interactions between host and prophages are of particular importance for human health considerations. As it becomes clearer that bacterial genomes contain large amounts of DNA from (pro)phage origin, we want to stress that these horizontally acquired genes are important contributors to the genomes evolution and provide discrete adaptive physiological contributions such as increasing fitness under certain environmental conditions or providing non-obvious metabolic or signaling functions (D’Ari and Casadesús, 1998). We chose to focus on Salmonella enterica prophages for the following reasons: (i) it is a widespread enterobacteria displaying a broad host range, frequently carried by wild and domestic birds as well as rodents, and an animal and human pathogen, (ii) host-prophages interactions have been studied for many years and still lead to amazing pieces of work encompassing many topics, such as host-phage interactions, virulence, ecology and genome evolution

Introduction

Interactions bacteria – prophage and prophage – bacteria

Findings

Conclusions