Tectivirus-mediated ecological adaptation of Bacillus cereus group members
(2011) XIII International Congress of Bacteriology and Applied Microbiology-IUMS 2011 — Location: Sapporo, Japan (6.September.2011)
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- The Bacillus cereus group includes several species displaying distinct virulence spectra as diverse as mammal anthrax caused by Bacillus anthracis, food toxi-infection due to B. cereus or the entomopathogenic activity of Bacillus thuringiensis. Many of these differences are associated with Mobile Genetic Elements (MGE), including plasmids, insertion sequences or transposons. However, little is known about the potential contribution of MGE, and particularly phages, to the adaptation of the B. cereus group to diverse niches. Tectiviridae, one of the phage families preying on the B. cereus group, includes tail-less temperate bacteriophages where the dsDNA is located within a lipid-containing membrane, covered by an icosahedral protein capsid. For instance, GIL01, GIL16 and Bam35 are tectiviruses infecting B. thuringiensis, while AP50 has been reported to infect B. anthracis. Additionally, GIL01, GIL16 and Bam35 exhibit a strong similarity to the B. cereus linear plasmid pBClin15. Since these tectiviruses are able to reside as linear plasmid into their host cells, establishing long-term relationships, it is important to understand the selective pressures displayed by bacteria when facing these bacteriophages. Therefore, the aim of this work was to study the different bacterial resistance phenotypes shown against GIL01 and GIL16 tectiviruses. Several B. thuringiensis strains were subjected to a selection pressure after repeated propagation with GIL01 and GIL16 clear plaque (CP) mutants. These CP mutants elicited an elevated killing efficiency since they propagate exclusively lytically. Bacterial mutants, displaying complete resistance to the CP phages, were found at low frequency. They exhibited various colony morphotypes and showed distinct adaptation features, as illustrated by their biofilm formation and exopolysaccharide production, sporulation rate and long-term survival capacity. These observations indicate that phages can drive the ecological adaptation of the B. cereus group members. These results will shed new light on bacteriophages receptor(s) and on the bacterial adaptation strategies to virus life-styles.
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Gillis, A., & Mahillon, J. (2011). Tectivirus-mediated ecological adaptation of Bacillus cereus group members. XIII International Congress of Bacteriology and Applied Microbiology-IUMS 2011, Sapporo, Japan. https://hdl.handle.net/2078.5/194959