Comparative morphological, genomic, and functional characterization of two newly isolated lytic caudoviricetes phages targeting Escherichia coli and Salmonella

Foodborne Salmonella enterica and pathogenic Escherichia coli remain major hazards across the farm-to-fork continuum, motivating targeted bacteriophage biocontrol. We isolated two lytic, contractile-tailed phages in Ajman, UAE, CF01 from camel feces and SW01 from municipal sewage and characterized their host range, replication kinetics, and genomes. SW01 lysed only its Salmonella host, whereas CF01 infected multiple E. coli strains and several Salmonella isolates, with efficiency of plating (EOP) indicating high infectivity on E. coli and variable but generally reduced efficiency on Salmonella. One-step growth assays showed SW01 had short latent period (10–20 min), large burst (8–10 × 103 PFU/infected cell), and plateau 3 × 109 PFU/mL at 70–80 min, with an optimal MOI of 0.01. CF01 displayed a 20–30 min latent period, burst 2–3 × 102, plateau 2 × 108 PFU/mL, and optimal MOI 0.1; adsorption was faster than SW01. Illumina MiSeq/Unicycler assemblies yielded single-contig genomes: CF01, 142,427 bp (43.29% GC); SW01, 84,506 bp (44.74% GC). No rRNA genes, CRISPR arrays, integrase/repressor markers, or antimicrobial-resistance determinants were detected under the applied thresholds. Phylogenomic analysis placed CF01 within Salmonella-infecting myoviruses, whereas SW01 formed a distinct lineage more closely related to Erwinia-infecting phages. These results indicate complementary utility: high productivity and low-MOI efficacy of SW01 favor rapid clearance, while CF01 showed broader host range and fast adsorption support inclusion in cocktails. Strictly lytic genomes and favorable kinetics motivate further development of SW01 and CF01 for food-safety applications.