Characteristics of microbial communities and antibiotic resistance genes in typical rivers of the western Qinghai Lake basin

Environmental factors and anthropogenic activity are key factors that shape the distribution of bacteria and antibiotic resistance genes (ARGs) in natural environments. However, few studies have focused on the occurrence of bacteria and ARGs in remote and pristine environments. In this study, the distribution of bacteria and ARGs in two typical rivers of the western Qinghai Lake basin was investigated. Results showed that cold-resistant Planomicrobium sp. was the predominant genus due to the low temperature, followed by unclassified_f_Planococcaceae. High nitrogen nutrients increased the abundance and diversity of the bacteria community and denitrification was the dominant means of bacterial nitrate reduction. Tetracycline resistance genes including tetA, tetB, and tetC were the dominant ARGs in the western Qinghai Lake basin, ranging from 2.30 × 103 to 1.91 × 108 copies/L, while the low abundances of intI1, and ARGs such as sul1 indicated low anthropogenic activity in the western Qinghai Lake basin. Finally, the strong positive correlation between ARGs and intI1 highlights the potential transmission risk of ARGs through cross- or co-selection by horizontal gene transfer. Our study emphasized the adaptation of bacteria to the environment and the facilitation of anthropogenic activity in the propagation of ARGs in natural environments.