Dynamic evolution of antibiotic resistance risk in sewage sludge-amended soil during crop growth: a field-based...

Sewage sludge, a ubiquitous by-product of wastewater treatment, accumulates globally. Land application, a prominent waste valorization strategy, inadvertently disseminates the sludge antibiotic resistome into ecosystems, threatening ecological security and public health. Risk assessment of antibiotic resistance (AR) during sludge land application is urgently needed. Herein, we conducted a field study by planting three crops in sludge-amended soil, and monitoring the dynamic evolution of AR risk throughout their growth cycles. Metagenomic sequencing assessed antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), virulence factors (VFs), and their co-occurrence. Sludge amendment exerted persistent, yet largely recoverable, impacts on soil microbial community and the resistome. The resulting AR risk evolution was nonlinear and fluctuating, dominated by soil microbial community reconstruction. Given the differences in crop edible parts, growth periods of crops, complex AR risk dynamics, and external factors like weather, we propose a time-sensitive control strategy targeting critical risk windows. This strategy aims to mitigate AR risk under the "One Health" paradigm for sustainable sludge land application.