characterization and genome sequencing of two novel lytic phages against Infantis isolated from poultry feces.

INTRODUCTION

spp. is the second most common bacteria associated with foodborne gastrointestinal outbreaks in humans, with the highest contamination levels in meat, especially poultry. subsp. serovar Infantis is the primary serovar isolated from broilers, without causing any symptomatic disease. Conversely, certain human strains can result in symptomatic illness (fever, headache, and diarrhoea). Therefore, reducing colonization in broilers is important before slaughter, to prevent this pathogen carryover along the food chain.

METHODS

Here, we report the characterization of two virulent phages, isolated from broiler feces. Isolates were phenotypically and genetically characterized.

RESULTS AND DISCUSSION

Phages (ɸ) SaI_NFG_5581 and SaI_NFG_5577 were characterized as strictly lytic versus but with different bacteriolytic activities and genetic features. They both belong to the Caudoviricetes class, but ɸSaI_NFG_5581 (genome length 112,970 bp) belongs to the Demerecviridae family while ɸSaI_NFG_5577 (genome length 42,481 bp) to the Guernseyvirinae family. Genomic analysis excluded the presence of lysogeny, toxin, or antimicrobial resistance genes, and for those reasons, the two phages could be considered safe. Phages are stable under a broad range of pH (4-10) and temperature (4°C-50°C) conditions. , both ɸSaI_NFG_5581 and ɸSaI_NFG_5577 were able to lower counts of about 2.2 LOG/mL and 3.4 LOG CFU/mL respectively, at MOI 0.1 after 2 h of treatment. After 24 h, counts treated with both phages remained lower than the control (non-phage-treated ). These newly isolated phages have promising features, which could be exploited and further studied for potential application.