Genome Characterization of Temperate Bacteriophages and Associated Genetic Features in Avian Pathogenic Escherichia...

To characterize the ecological and genomic architecture of temperate bacteriophages in Escherichia coli isolated from Brazilian broiler chickens, we analyzed 63 femur-derived genomes, most fulfilling molecular avian pathogenic E. coli (APEC) criteria, and tested whether temperate phage regions are enriched for antimicrobial resistance genes (ARGs), virulence factors, plasmid markers, and other mobilome components. Diversity was summarized using incidence-based richness estimators and bootstrap confidence intervals, and positional enrichment was assessed using permutation-based statistical analysis. We detected 1164 phage-like elements, including 188 medium- and high-quality phages, of which 93.6% were temperate. Median temperate diversity per genome was three phage genera and three temperate regions. At the population level, 19 temperate genera were observed, with a Chao2 estimate of 21.2, indicating near-saturated genus-level diversity. Positional mobilome analysis showed significant enrichment of insertion sequences within temperate regions (p < 0.05), while ARGs, virulence factors, and plasmid markers were not significantly enriched inside temperate phage coordinates (p > 0.05). The surrounding genomic neighborhood (±20 kb) accumulated mobile elements but showed no significant enrichment. CRISPR spacer matches further supported ongoing host-phage interactions. Overall, temperate phages are widespread and ecologically structured in Brazilian broiler-associated E. coli, but they are not preferential hotspots for ARG, virulence, or plasmid gene enrichment; instead, they are chiefly associated with insertion-sequence enrichment.