Biogeographical patterns of antibiotic resistomes in soil biocrusts from urban green spaces at the continental scale

The distribution patterns of antibiotic resistomes in biological soil crusts (biocrusts) and the underlying factors influencing them remain poorly understood. Here, metagenomic sequencing was used to profile antibiotic resistomes in biocrusts of urban green space soils in 54 cities across China. The biocrust samples harbored ARGs associated with resistance against 21 classes of antibiotics such as betalactams, quinolones, aminoglycosides, and tetracyclines. Total ARG abundance was positively correlated with total phosphorus, available phosphorus, and lignin concentrations in biocrusts. The geographic factors, environmental factors, and DOM components only explained 18.1 % of the total variation of resistome in 54 samples, whereas the bacterial and mobile genetic element (MGE) communities explained 59.3 % of the total variation. In contrast with deterministic processes, stochastic processes played a more dominant role in shaping the resistomes across different samples (average stochasticity: 81.2 %) and were correlated with MGE communities. Findings of the present study demonstrate the ecological distribution of antibiotic resistomes in biocrusts of urban green spaces under different biotic and abiotic conditions over a continental scale.