Impacts of anthropogenic disturbances on antibiotic resistomes in biological soil crusts on the Qinghai-Tibetan Plateau.

Biological soil crusts (BSCs) are the main landscape on the Qinghai-Tibetan Plateau and an ecological indicator of human disturbance. Information about antibiotic resistomes in BSCs on the Qinghai-Tibetan Plateau can provide baseline for the risk assessment and management of resistomes and yet to be explored. This work investigated the profiles and geographic patterns of antibiotic resistomes in BSCs along the Lhasa River and their response to anthropogenic activities for the first time. Various antibiotic resistance genes (ARGs) were widely distributed in BSCs, but had relatively lower detection frequency and abundance comparing to soils from human disturbed sites. ARGs profiles in BSCs were separated by altitude from 3860 to 3880 m, possibly attributing to the difference in anthropogenic activities. Above 3860 m, resistomes exhibited lower abundance including total ARGs, aadA, blaSFO and tnpA-04 owing to the rare human activities; at human disturbed sites with altitude <3860 m, the detection frequency and relative abundance of tetG02, oprJ, qacEdelta1-01, and ARGs with the mechanism of efflux pump were higher and viewed as potential indicators of human activities. Anthropogenic activities potentially promoted the horizontal gene transfer of ARGs in BSCs at human disturbed sites from co-occurrence network analysis. Our findings provided fundamental information of antibiotic resistomes in BSCs on the Qinghai-Tibetan Plateau, and unraveled possible mechanisms of human disturbance in shaping antibiotic resistomes.