Bacillus Phage vB_BtS_B83 Previously Designated as a Plasmid May Represent a New Siphoviridae Genus

Abstract

The Bacillus cereus group of bacteria includes, inter alia, the species known to be associated with human diseases and food poisoning. Here, we describe the Bacillus phage vB_BtS_B83 (abbreviated as B83) infecting the species of this group. Transmission electron microscopy (TEM) micrographs indicate that B83 belongs to the Siphoviridae family. B83 is a temperate phage using an arbitrium system for the regulation of the lysis–lysogeny switch, and is probably capable of forming a circular plasmid prophage. Comparative analysis shows that it has been previously sequenced, but was mistaken for a plasmid. B83 shares common genome organization and >46% of proteins with other the Bacillus phage, BMBtp14. Phylograms constructed using large terminase subunits and a pan-genome presence–absence matrix show that these phages form a clade distinct from the closest viruses. Based on the above, we propose the creation of a new genus named Bembunaquatrovirus that includes B83 and BMBtp14.

Paving the Way to Unveil the Diversity and Evolution of Phage Genomes

“…The phages in Bacillus were not only capable of inserting into the bacterial genome, they were also capable of remaining in the cytoplasm as plasmids. This was shown by Piligrimova et al who show that the vB_Bts_B83 phage, which was previously thought to be a plasmid, actually represents a new member of the Siphoviridae family, confirmed by electron microscopy and different molecular validation tools [20].…”

Bacillus-infecting bacteriophage Izhevsk harbors thermostable endolysin with broad range specificity

“…Phage purification, propagation and PEG 8000 (polyethylene glycol) precipitation were performed as described previously [ 13 ]. Then 3 ml of the high-titer preparation were used for CsCl centrifugation in a preformed CsCl density gradient (1.3 g/ml, 1.4 g/ml, 1.5 g/ml, 1.6 g/ml, 1.7 g/ml) to prepare the final purified phage suspension, which was used later on for transmission electron microscopy.…”

“…Host range test was performed as described previously [ 13 ] using 34 strains of the B . cereus group as well as five other Bacillus strains and one Enterococcus strain.…”

“…Phage purification, propagation and PEG 8000 (polyethylene glycol) precipitation were performed as described previously [13]. Then 3 ml of the high-titer preparation were used for PLOS ONE and analysis, decision to publish, or preparation of the manuscript.…”

“…Host range test was performed as described previously [13] using 34 strains of the B. cereus group as well as five other Bacillus strains and one Enterococcus strain. 2 μL of phage suspension (�10 6 p.f.u./mL) was dripped onto agar plate with each tested strain.…”