Identification of the biological properties of three novel lytic bacteriophages capable of infecting Bacillus anthracis: Novel members of the class Caudoviricetes

Abstract

Bacillus anthracis spores can remain viable for many years in regions where anthrax cases are reported or where deceased animals are buried. Anthrax occurrences may be more common in areas where livestock farming is a primary source of livelihood. In this study, 43 Bacillus anthracis isolates were used, which were isolated from samples collected in different provinces of Türkiye. Three lytic bacteriophages(BaTR8, BaTR13, and BaTR16) were isolated from environmental soil samples. These three lytic bacteriophages' biological properties (host range, burst size, and phage morphology) were defined, and molecular methods were used to determine their genomic structures. It was determined that three lytic phages were able to infect 84.1 % of the host bacteria and formed clear phage plaques. Transmission electron microscopy (TEM) analysis identified them as siphoviruses. Bacteriophage genome lengths ranged from 35587 to 37369 kb, and the GC content was approximately 35 %. The genome structures of the three phages were analyzed, determining that they contained 58–62 ORFs and did not encode any tRNA genes. Phylogenetic analyses of the bacteriophages were performed based on whole-genome sequences and conserved signature genes (major capsid, portal, and terminase large subunit proteins), and the phages were taxonomically classified within the class Caudoviricetes. The three phages isolated in this study, together with the Athena phage, which infects Bacillus anthracis, were determined to form a new cluster distinct from the Wbetavirus and Hubeivirus genera. Our study presents, for the first time, the results of a detailed evaluation of Bacillus anthracis phages isolated from Türkiye.