Unraveling the Sources and Influencing Mechanism of Soil Antibiotic Resistance Genes in Urban Micro Green Spaces

Abstract

Characterized by the small size and extensive distribution, micro green spaces are vital for urban environmental quality and resident well-being. Yet, they are increasingly recognized as hotspots for the convergence of antibiotic resistance genes (ARGs); systematic research on ARGs pollution in these areas remains limited. This study investigated the distribution and sources of ARGs in soils from 21 micro green spaces in Tianjin, China. The results indicated a high prevalence of ARGs, with a predominance of aminoglycoside, β-lactam, fluoroquinolone and multidrug. Their dissemination was primarily facilitated by protection mechanisms and horizontal gene transfer (HGT) mediated by mobile genetic elements (MGEs). Source analysis indicated that in intra-urban areas, ARGs were mainly contributed by trash (46.9%), followed by irrigation water (37.3%) and pet/bird feces (15.8%). In extra-urban areas, irrigation water was the dominant source (72.8%), demonstrating considerable spatial heterogeneity. Mechanistic analysis revealed soil total phosphorus (TP) as the strongest driver of ARGs enrichment (p < 0.001). Furthermore, specific phyla like Cloacimonadota and Myxococcota were linked to ARGs diffusion through their correlation with MGEs. This study fills a key knowledge gap on ARGs in micro green spaces, providing a scientific basis for interventions aimed at safeguarding urban ecological security and public health.