Role of phage \u03d51 in two strains of Salmonella Rissen, sensitive and resistant to phage \u03d51

Marina Papaianni,Massimo Delledonne,Luca Marcolungo,Andrea Fulgione,Felice Contaldi,Rosanna Capparelli,Marzia Rossato,Ermenegilda Parrilli,Domenico Iannelli,Maria Michela Corsaro,Sheridan L Woo,Marianna Garonzi,Angela Casillo

doi:10.1186/s12866-018-1360-z

Abstract

BackgroundThe study describes the Salmonella Rissen phage ϕ1 isolated from the ϕ1-sensitive Salmonella Rissen strain RW. The same phage was then used to select the resistant strain RRϕ1+, which can harbour or not ϕ1.ResultsFollowing this approach, we found that ϕ1, upon excision from RW cells with mitomycin, behaves as a temperate phage: lyses host cells and generates phage particles; instead, upon spontaneous excision from RRϕ1+ cells, it does not generate phage particles; causes loss of phage resistance; switches the O-antigen from the smooth to the rough phenotype, and favors the transition of Salmonella Rissen from the planktonic to the biofilm growth.The RW and RRϕ1+ strains differ by 10 genes; of these, only two (phosphomannomutase_1 and phosphomannomutase_2; both involved in the mannose synthesis pathway) display significant differences at the expression levels. This result suggests that phage resistance is associated with these two genes.ConclusionsPhage ϕ1 displays the unusual property of behaving as template as well as lytic phage. This feature was used by the phage to modulate several phases of Salmonella Rissen lifestyle.

Highlights

The study describes the Salmonella Rissen phage φ1 isolated from the φ1-sensitive Salmonella Rissen strain RW
Phage φ1 displays the unusual property of behaving as template as well as lytic phage
Rissen bacteria (RW) yielded phage φ1 and release of φ1 particles was followed by host cell lysis

Summary

Introduction

The study describes the Salmonella Rissen phage φ1 isolated from the φ1-sensitive Salmonella Rissen strain RW. The RW and RRφ1+ strains differ by 10 genes; of these, only two (phosphomannomutase_1 and phosphomannomutase_ 2; both involved in the mannose synthesis pathway) display significant differences at the expression levels This result suggests that phage resistance is associated with these two genes. Bacteria are under constant attack by bacteriophages (phages), the most abundant life forms in the biosphere [1]. Bacteria can promote a temporary change of the phage receptor specificity They do it through a mechanism known as phase variation. The above examples well explain how the role of phase variation in the Papaianni et al BMC Microbiology (2018) 18:208 bacterial world is to rapidly generate diversity and enable bacteria to colonize different hosts and survive in changing environments [8]

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Conclusion