Metagenomic Insights into Potential Impacts of Antibacterial Biosynthesis and Anthropogenic Activity on Nationwide Soil Resistome.

ABSTRACT

The presence of antibiotic resistance genes (ARGs) in soils has received extensive attention regarding its impacts on environmental, animal, and human systems under One Health. However, the health risks of soil ARGs and microbial determinants of soil resistomes remain poorly understood. Here, a nationwide metagenomic investigation of ARGs in cropland and forest soils in China was conducted. The findings indicated that the abundance and richness of high-risk (i.e., mobilizable, pathogen-carriable and clinically relevant) ARGs in cropland soils were 25.7 times and 8.4 times higher, respectively, compared to those identified in forest soils, suggesting the contribution of agricultural practices to the elevated risk level of soil resistomes. The biosynthetic potential of antibacterials best explained the total ARG abundance (Mantel's r = 0.52, p < 0.001) when compared with environmental variables and anthropogenic disturbance. Both microbial producers' self-resistance and antagonistic interactions contributed to the ARG abundance, of which self-resistance ARGs account for 14.1 %- 35.1 % in abundance. With the increased biosynthetic potential of antibacterials, the antagonistic interactions within the microbial community were greatly enhanced, leading to a significant increase in ARG abundance. Overall, these findings advance our understanding of the emergence and dissemination of soil ARGs and provide critical implications for the risk control of soil resistomes.