Genomic and physiochemical characterization of two lysogenic bacteriophages, ΦCP5(17) and ΦCP17(i), infecting Clostridium perfringens

Group A Clostridium perfringens is a major poultry pathogen that causes necrotic enteritis. The molecular similarity of its toxins to those of other bacterial species suggests the involvement of horizontal gene transfer through mobile genetic elements or bacteriophages. Lysogenic bacteriophages play an important role in bacterial evolution through horizontal gene transfer. In the present study, we examined and compared the physiochemical characteristics, genome sequences, and tail fiber proteins of two lysogenic bacteriophages infecting C. perfringens. Bacteriophages ΦCP5(17) and ΦCP17(i) were isolated from a sewage sample and tested for their stability at different temperatures and pH conditions, and in simulated gastric fluids. The genomes of these phages were sequenced, and their morphology was examined by electron microscopy. Both phages produced circular, hazy plaques on their host bacteria and were stable up to 60°C, exhibiting optimal activity at pH 7–8. Both bacteriophages were found to have a very narrow host range, with ΦCP17(i) exhibiting a slightly broader host range than ΦCP5(17). Both phages exhibited podovirus morphology and a genome size of 17.8 kb and 17.9 kb for ΦCP5(17) and ΦCP17(i), respectively. According to the ICTV classification system, ΦCP5(17) and ΦCP17(i) belong to the genus Brucesealvirus, family Guelinviridae, and class Caudoviricetes. These phages share 95.6% genomic nucleotide sequence identity, suggesting that they belong to the same species but differ at the subspecies level. Although ΦCP5(17) and ΦCP17(i) have similar morphological and genomic features, their tail fiber proteins differ in their predicted folding patterns. Nucleotide sequence analysis indicated the absence of toxin and antibiotic resistance genes. Both phages encode a SpoVG protein, whose functional role requires further investigation.