Biocontrol of Bacillus Licheniformis in Dairy Products Using a Novel Lytic Bacteriophage BLp-YZU29: Characterisation and Genomic Analysis

Background Bacillus licheniformis spoils dairy products and poses safety risks, while traditional control methods have limitations. Lytic bacteriophages are promising biocontrol agents, but specific, efficient ones against this bacterium in dairy environments are lacking.Aim This study isolated a novel lytic phage BLp-YZU29 targeting B. licheniformis, and characterised its biological traits, genome features and biocontrol potential in dairy products.Methods Phage BLp-YZU29 biological characteristics, including phage morphology, host range, optimal multiplicity of infection (MOI), pH and temperature stability, genomic features and biocontrol potential in dairy products, were determined.Major Findings Phage BLp-YZU29 (Caudoviricetes class) displayed a latent period of 20 min, burst size of 24.52 PFU/host cell, burst period of 140 min and an optimal MOI of 0.01. It specifically lysed 40 out of 46 B. licheniformis isolates (86.96%) and showed superior stability under varying pH conditions (pH 3-12) and at a temperature of 60 degrees C for 60 min. The genomic sequence showed that 76 ORFs out of 220 ORFs of phage BLp-YZU29 were functionally annotated but did not have genes for virulence, lysogeny and antibiotic resistance. Phage BLp-YZU29 exhibited strong inhibitory effects against B. licheniformis in a phage-dosage and temperature-dependent way.Scientific Implications BLp-YZU29 provides a safe biocontrol agent for the dairy industry, enriches phage resources and lays a theoretical foundation for phage-based biocontrol technology application.