Abstract Thermokarst lakes are biogeochemical hotspots and reservoirs of antibiotic resistance genes (ARGs), yet their vertical organization remains poorly understood. Here, we investigated the vertical stratification of ARGs in sediment cores from thermokarst lakes on the Qinghai-Xizang Plateau, quantifying their distribution and associations with mobile genetic elements (MGEs) and carbohydrate-active enzymes (CAZymes). The results revealed pronounced vertical differentiation, with ARG richness decreasing but β-diversity increasing with depth. A total of 386 ARGs were identified, of which 39% increased and 22% decreased significantly along the depth gradient. Multidrug and glycopeptide resistance genes dominated the profiles, while macrolide, tetracycline, and fluoroquinolone resistance were most abundant overall. MGEs, primarily transposase and recombinase genes, were strongly correlated with ARGs, underscoring horizontal gene transfer as a key mechanism for their persistence and dispersal. Co-occurrence analyses further revealed both positive and negative associations between ARGs and CAZymes, indicating synergistic and antagonistic couplings between antibiotic resistance and microbial carbon metabolism. Genes involved in energy-efficient carbon degradation (e.g., glycoside hydrolases and glycosyltransferases) were positively correlated with resistance genes enhancing stress tolerance, whereas negative interactions reflected trade-offs between carbon utilization and resistance maintenance. These findings demonstrate that ARGs are vertically structured and functionally integrated within microbial metabolic networks, providing new insights into their ecological roles in thermokarst lakes.
Ren et al. (Thu,) studied this question.
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