Effects of the coexistence of antibiotics and heavy metals on the fate of antibiotic resistance genes in chicken manure and surrounding soils

• Published in: Ecotoxicology and environmental safety Vol. 263; p. 115367
• Main Authors: Shen, Cong, He, Mengyuan, Zhang, Junhua, Liu, Jili, Su, Jianyu, Dai, Jinxia
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.09.2023; Elsevier
• Subjects: Antibiotic resistance genes; Antibiotics; Co-selection; Heavy metals; Horizontal gene transfer; Mobile genetic elements; Co-selection; Antibiotics; Antibiotic resistance genes; Heavy metals; Mobile genetic elements; Horizontal gene transfer
• ISSN: 0147-6513; 1090-2414; 1090-2414
• DOI: 10.1016/j.ecoenv.2023.115367

Both heavy metals and antibiotics exert selection pressure on bacterial resistance, and as they are commonly co-contaminated in the environment, they may play a larger role in bacterial resistance. This study examined how breeding cycles affect antibiotic resistance genes (ARGs) in chicken manure and the surrounding topsoils at 20, 50, 100, 200, and 300 m from twelve typical laying hen farms in the Ningxia Hui Autonomous Region of northwest China. Six antibiotics, seven heavy metals, ten mobile genetic elements (MGEs), and microbial community affected the ARGs profile in chicken dung and soil samples. Tetracycline antibiotic residues were prevalent in chicken manure, as were relatively high content of aureomycin during each culture period. Zinc (Zn) content was highest among the seven heavy metals in chicken feces. Chicken dung also enriched aminoglycosides, MLSB, and tetracycline ARGs, notably during brooding and high production. The farm had a minimal influence on antibiotics in the surrounding soil, but its effect on ARGs and MGEs closer to the farm (50 m) was stronger, and several ARGs and MGEs increased with distance. Manure microbial composition differed dramatically throughout breeding cycles and sampling distances. ARGs were more strongly related with antibiotics and heavy metals in manure than soil, whereas MGEs were the reverse. Antibiotics, heavy metals, MGEs, and bacteria in manure accounted 12.28%, 22.25%, 0.74%, and 0.19% of ARGs composition variance, respectively, according to RDA and VPA. Bacteria (2.89%) and MGEs (2.82%) only affected soil ARGs composition. These findings showed that heavy metals and antibiotics are the main factors affecting faecal ARGs and bacteria and MGEs soil ARGs. This paper includes antibiotic resistance data for large-scale laying hen husbandry in northwest China and a theoretical framework for decreasing antibiotic resistance. [Display omitted] •The distribution of antibiotics and heavy metals in chicken manure and surrounding soil.•Chicken farms have a larger effect on ARGs in soils closer to the surrounding area (≤50 m).•Antibiotics and heavy metals were more closely associated with ARGs in chicken manure than in soil.•The pattern of co-occurrence between MGEs and ARGs was significantly stronger in soil than in chicken manure.•Heavy metals and antibiotics were the main factors influencing the composition of ARGs in chicken manure.