Distribution pattern of antibiotic resistance genes and bacterial community in agricultural soil samples of Wuliangsuhai watershed. China

The occurrence and dissemination of antibiotic resistance genes (ARGs) constitute a major concern worldwide, and pose crucial threats to public health. The current study focused on this issue in the agricultural soils of Wuliangsuhai watershed in China. A total of 33 ARGs, belonging to 8 major types, were identified in the soil samples, mexF, bla(TEM), vanD, selI, sulII, and oprJ being the predominant ones. The abundance of ARGs ranged from 2.18 x 10(-6)-1.9 x 10(-2) copies/16S rRNA gene copies. Results of correlation analyses confirmed that intI1 significantly correlated with ARGs (aadA1, aadA2, mphA, adI, and sulII), indicating the potential horizontal transfer capability of these genes in soil. Based on the proximity of different sampling sites with urban areas, we found the abundance of bacterial community and ARGs to significantly increase in the sites proximal to urban area, which indicated the agricultural activities and industrial pollution might alter the bacterial community structure and spatial distribution of ARGs. In addition, the correlation between ARGs and environmental factors confirmed the association of microbial community distribution with environmental factors, such as soil organic matter (SOM), available phosphorus (AP), and total nitrogen (TN). The co-occurrence pattern of ARGs and bacterial taxa indicated the succession of Firmicutes and Proteobacteria to possibly be the potential driver for variation in ARGs in the different sampling sites examined. These findings are expected to improve the current understanding of ARG distribution and their relationship with microbial community succession.