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

Abstract

<i>Bacillus cereus</i> 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 <i>B. cereus</i> strains as hosts and were comprehensively characterized. Both phages formed clear plaques with halos and exhibited siphovirus morphology. Host range analysis against 172 <i>B. cereus</i> 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 <i>Lwoffvirus</i>. Biofilm assays demonstrated significant inhibition of <i>B. cereus</i> biofilm formation and reduction of pre-established biofilms. Overall, this study expands knowledge of <i>B. cereus</i> phage diversity and highlights the importance of genomic characterization in phage-based biocontrol research.