Comparative Genomics of Bacillus subtilis Phages Related to phiNIT1 from Desert Soils of the Southwest United States

Background: Bacillus subtilis is a Gram-positive bacterium commonly found in soil. Phages infecting B. subtilis have diverse genomes and may be used in therapeutics against pathogenic Bacillus species.Materials and Methods: Phages were isolated and purified on B. subtilis. Comparative genomics was performed to determine taxonomy, a liquid-culture lysis assay was used to determine host range, and virion structure was observed for a representative phage by transmission electron microscopy.Results: Five phages were found to have high sequence similarity to each other and known phages, including phiNIT1. Annotation shows a conserved genome structure and protein families unique to this group. Repeated sequences are concentrated in intergenic regions at the ends of the genomes. Capsid structure and tail length suggest these phages are myoviruses.Conclusions: The phages described here share sequence similarity and genomic structure with known Bacillus phages. This study expands our understanding of the genetic diversity of Bacillus phages.