Millennial-scale microbiome analysis reveals ancient antimicrobial resistance conserved despite modern selection pressures

Antibiotic resistance has existed throughout microbial evolution and will likely persist, as microbes have the capacity to develop and retain resistance genes through evolutionary processes. The classes of antimicrobial resistance genes profiled and the function of antibiotic-inactivating enzymes from ancient permafrost microbiomes do not seem to be very different from the genes found in the antibiotic era. Additionally, we retrieved 359 putative complete viruses from ancient microbiomes and none of them harboured any ARGs.