QUANTITATIVE ANALYSIS OF PHAGE MVB AGAINST LISTERIA MONOCYTOGENES STRAINS ISOLATED FROM CONTAMINATED FOOD.

Listeria monocytogenes (LM) is a bacterium widely known for contaminating food products and causing infections in humans, leading to severe gastroenteritis. Phages are viruses that infect host-specific bacteria and can serve as alternative therapeutics to combat these infections. The purpose of the present study is to evaluate the MVB phage activity against Listeria monocytogenes (LM) isolates from contaminated foods. L. monocytogenes was isolated from contaminated food in the Bagalkot district using specific media. Bacteriophages against L. monocytogenes was isolated from municipal sewage wastewater in Bagalkot city using the double-layer plate method. The propagation and purification of the phage were carried out. The spot test was performed against L. monocytogenes and the characterization of the phage was conducted by using electron microscopy, phage DNA extraction, restriction digestion and SDS-PAGE. Three bacteriophages were isolated from wastewater sources and assessed for their ability to lyse L. monocytogenes. The phages showed optimal proliferation at pH 7 and 37°C after 36 hours of incubation. The most effective lytic activity was observed at a bacterial cell to phage ratio of 10:1 with a phage concentration of 9 × 10⁹ PFU/mL. The SDS-PAGE phage protein analysis showed major head proteins of 74 kDa and 37 kDa. The size of the phage DNA was 21 kb and restriction digestion with HindIII showed 5 fragments, while EcoRII showed 4 fragments. Study with transmission electron microscopy (TEM) revealed that the isolated phage belongs to the Inoviridae family. These findings suggesting that the isolated phages are from L. monocytogenes could potentially be utilized to combat this pathogen in various contexts, including dairy based food, agriculture based food, wastewater and related infections. [ABSTRACT FROM AUTHOR]