Fei Ge

Composting agricultural waste is a cornerstone of circular agriculture but carries the risk of disseminating antibiotic resistance genes (ARGs). While persistent free radicals (PFRs) are known to continuously suppress ARGs, their natural yield in compost is often insufficient. Here, we demonstrate that hydroxamate siderophores (HDS) can capture Fe(III) to form stable redox-active complexes that act as potent electron shuttles, driving the generation of semiquinone radicals (SQ^•–) to inhibit ARG proliferation while promoting the humification process. In a 40 day cocomposting experiment with rice straw and pig manure, HDS amendment accelerated humification by 24.7% and enriched the quinone moieties within the humic matrix by 22.3%. HDS–Fe(III) complexes were predominantly reduced via microbial activity to HDS–Fe(II), which then served as a potent electron donor due to its significantly lowered redox potential. This drove spontaneous electron transfer to quinone moieties, increasing SQ^•– production by 2.1–7.4 times. The sustained oxidative pressure imposed by SQ^•– significantly inhibited plasmid-mediated conjugative transfer frequency by 65.3–84.4% via inducing membrane damage of critical host bacteria (such as Streptomyces). Consequently, mid- to high-risk ARGs in HDS-treated compost products were reduced by 11.6–26.6%. Application of HDS-treated compost products to paddy soil confirmed the persistent mitigation of ARG propagation risks. Overall, this HDS-based approach achieves the dual goals of compost valorization and biosafety, advancing the sustainability of circular agriculture within the “One Health” framework.

Sequestration of cadmium (Cd) in rice phytolith can effectively restrict its migration to the grains, but how hydroxamate siderophore (HDS) affects phytolith formation within rice plants especially the fate of Cd and silicon (Si) remains poorly understood. Here, we found that the addition of HDS increased the content of dissolved Si and Cd in soil pore water as well as its absorption by the rice roots during the reproductive growth stage. HDS effectively trapped orthosilicic acid and Cd ions at the third stem nodes of rice plants via hydrogen bonds and chelation interactions, which then rapidly deposited on the xylem cell wall through hydrophobic interactions. Ultimately, Cd was immobilized as phytolith-like particulates in the form of CdSiO₃. Field experiments verified that Cd accumulation was significantly reduced by 46.4% in rice grains but increased by 41.2% in rice stems after HDS addition. Overall, this study advances our understanding of microbial metabolites enhancing the instinctive physiological barriers within rice plants.

Water pollution is the main cause of global ecological degradation and seriously affects people’s water supply. In order to respond to the water environmental protection policy and provide management departments with a basis for refining water quality, this paper uses the environmental Gini coefficient (EGC) method based on four indicators, such as water environmental capacity, population, land area, and gross domestic production (GDP), to represent social, economic, and environmental factors, respectively. After the optimization, for COD, the EGC based on the land area was 0.30, EGC based on population was 0.21, EGC based on environment capacity was 0.02, and the EGC based on GDP was 0.45, and the sum of EGC was 0.962. From this result, we can observe that the change in the Gini coefficient of each indicator is not very considerable. Hence, the most significant change in the Gini coefficient was that of GDP, with a higher rate than the other criteria. Then, the COD, AND, and TP discharge allocation models were constructed to obtain the total allocated discharge permit for the Lushui Basin. The results show that the total discharge permit allocations of COD, AN, and TP for the Lushui Basin are 51,483.304, 843.119, and 340.926 tons/year, respectively. Based on GIS spatial analysis technology, the distribution of unfair factors that cause pollution inequity is investigated. Finally, reduction measures were proposed to implement environmental supervision and improve water environmental management.