Tectiviruses preying on the Bacillus cereus group: prevalence and phage-host interactions
(2012) Viruses of Microbes II — Location: Brussels, Belgium (16.July.2012)
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- Abstract
- Tectiviridae is an interesting phage family infecting the B. cereus group, comprising non-enveloped tail-less phages with a double-layer capsid where the ~15kb linear dsDNA is located within a lipid-containing membrane covered by a rigid icosahedral protein capsid. This family contains two groups of phages: the lytic PRD1 infecting Gram-negative bacteria and the temperate ones preying on Gram-positive bacteria belonging to the Bacillus cereus sensu lato (s.l.) group. Phages Bam35/GIL01, GIL16 and AP50 are representatives of the latter tectivirus group. The aim of this work is to characterize the interactions between tectiviruses and their B. cereus s.l. host cells. Due to the fact that temperate tectiviruses are able to reside as linear plasmid, the occurrence of tectiviral elements was addressed in a B. cereus s.l. collection. PCR and propagation tests revealed that tectiviral elements occurred in less than 5% of the examined strains. Despite this limited distribution, some novel tectivirus were found, and DNA sequencing of variable regions indicated that a greater diversity exist within the Tectiviridae. Interestingly, host range experiments for GIL01, GIL16 and their new cousins showed that some strains were susceptible to both GIL01 and GIL16, whereas others could be infected only by one representative. These results strongly suggest that more than one molecule can act as tectivirus receptor on the bacterial surface. For studying adsorption properties and identification of tectivirus receptors, bacterial mutant libraries were obtained and mutants displaying either complete or specific phage resistances were obtained. Bacterial mutants displaying complete resistance to tectivirus exhibited various colony morphotypes and showed distinct adaptation features, as illustrated by their biofilm formation and exopolysaccharide production, changes in conjugation frequency of some B. thuringiensis plasmids, sporulation rate and long-term survival capacity. These observations indicate that tectiviruses may drive life-trait changes and ecological adaptations in the B. cereus group members.
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Gillis, A., & Mahillon, J. (2012). Tectiviruses preying on the Bacillus cereus group: prevalence and phage-host interactions. Viruses of Microbes II, Brussels, Belgium. https://hdl.handle.net/2078.5/194963