Isolation, Characterization and Genomic Analysis of PBC_MG88 and PBC_MG99 Bacteriophages and Their Antibiofilm Activity Against the Bacillus cereus Groups

Bacillus cereus is a major foodborne pathogen responsible for food spoilage and foodborne illness, including strains producing emetic toxins. In this study, two bacteriophages, PBC_MG88 and PBC_MG99, were isolated from wastewater using emetic B. cereus strains as hosts and were comprehensively characterized. Both phages formed clear plaques with halos and exhibited siphovirus morphology. Host range analysis against 172 B. cereus strains showed that PBC_MG88 and PBC_MG99 infected 50 and 60 strains, respectively. One-step growth experiments revealed efficient lytic activity, with latent periods of 20–25 min and burst sizes of 59–63 PFU per infected cell. More than 90% of phage particles adsorbed to host cells within 15 min. Both phages were stable across a wide temperature range (4–55 °C) and pH values (4–11). Genome sequencing revealed ~37 kb double-stranded DNA genomes lacking antibiotic resistance or virulence genes; however, the presence of lysogeny-related genes suggests a temperate lifestyle. Comparative genomic analyses indicated that both phages represent novel species within the genus Lwoffvirus. Biofilm assays demonstrated significant inhibition of B. cereus biofilm formation and reduction of pre-established biofilms. Overall, this study expands knowledge of B. cereus phage diversity and highlights the importance of genomic characterization in phage-based biocontrol research.