Antimicrobial resistance in Arctic soils is mediated by competition and facilitation

Antimicrobial resistance (AMR) is widespread in terrestrial ecosystems. However, the natural processes shaping the spatial and temporal dissemination of AMR in soils are not well understood. We aimed to determine whether, how, and why AMR varies in recently deglaciated pioneer and developing Arctic soils. We showed that antibiotic-resistant genes (ARGs), mobile genetic elements (MGEs), and antibiotic-resistant bacteria (ARB) are abundant, exhibit a non-uniform distribution, and generally increase with soil age. Our analyses suggest a strong positive relationship between soil age and ARG and ARB, which we attribute to increased competition between microbes in older soils. We also observed a weak negative relationship between soil age and ARG diversity mediated by soil organic matter, suggesting facilitation due to the alleviation of nutrient limitation. The microbial processes regulating the spread of AMR in Arctic soils may be further susceptible to the effects of future climate change and human activities. ### Competing Interest Statement The authors have declared no competing interest.