Diversity and evolution of an abundant ICE family of integrative and conjugative elements in .

Microbial populations swiftly adapt to changing environments through horizontal gene transfer. While the mechanisms of gene transfer are well known, the impact of environmental conditions on the selection of transferred gene functions remains less clear. We investigated ICEs, specifically the ICE-type, in clinical isolates. Our findings revealed co-evolution between ICEs and their hosts, with ICE transfers occurring within strains. Gene functions carried by ICEs are positively selected, including potential virulence factors and heavy metal resistance. Comparison to publicly available genomes unveiled widespread antibiotic-resistance determinants within ICE clades. Thus, the ubiquitous ICE family significantly contributes to 's adaptation and fitness in diverse environments.