State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau/College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China.
The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia.
Environ Sci Pollut Res Int. 2024 Mar;31(15):22663-22678. doi: 10.1007/s11356-024-32578-6. Epub 2024 Feb 27.
Antibiotic contamination in soil has become a major concern worldwide. At present, it is not clear how two co-existed antibiotics with environmentally relevant concentrations would affect soil bacterial community structure, the abundances of antibiotic resistance genes (ARGs) and functional genes, and whether the effects of antibiotics would differ between rhizosphere and bulk soil. We conducted a greenhouse pot experiment to grow maize in a loess soil treated with oxytetracycline (OTC) or sulfadiazine (SDZ) or both at an environmentally relevant concentration (1 mg kg) to investigate the effects of OTC and SDZ on the rhizosphere and bulk soil bacterial communities, abundances of ARGs and carbon (C)-, nitrogen (N)-, and phosphorus (P)-cycling functional genes, and on plant growth and plant N and P nutrition. The results show that the effects of environmentally relevant concentrations of OTC and SDZ on bacterial communities and abundances of ARGs and functional genes differ between maize rhizosphere and bulk soil. The effects of two antibiotics resulted in a higher absolute abundances of accA, tet(34), tnpA-04, and sul2 in the rhizosphere soil than in the bulk soil and different bacterial community compositions and biomarkers in the rhizosphere soil and the bulk soil. However, OTC had a stronger inhibitory effect on the abundances of a few functional genes in the bulk soil than SDZ did, and their combination had no synergistic effect on plant growth, ARGs, and functional genes. The role of co-existed OTC and SDZ decreased shoot height and increased root N concentration. The results demonstrate that environmentally relevant concentrations of antibiotics shift soil microbial community structure, increase the abundances of ARGs, and reduce the abundances of functional genes. Furthermore, soil contamination with antibiotics can diminish agricultural production via phytotoxic effects on crops, and combined effects of antibiotics on plant growth and nutrient uptake should be considered.
土壤中的抗生素污染已成为全球关注的主要问题。目前尚不清楚两种共存的具有环境相关性浓度的抗生素将如何影响土壤细菌群落结构、抗生素抗性基因（ARGs）和功能基因的丰度，以及抗生素的作用是否会在根际和非根际土壤之间存在差异。我们进行了一项温室盆栽实验，在黄土中种植玉米，用土霉素（OTC）或磺胺嘧啶（SDZ）或两者以环境相关浓度（1mgkg）处理，以研究 OTC 和 SDZ 对根际和非根际土壤细菌群落、ARGs 和碳（C）、氮（N）和磷（P）循环功能基因的丰度，以及对植物生长和植物 N 和 P 营养的影响。结果表明，OTC 和 SDZ 的环境相关浓度对玉米根际和非根际土壤细菌群落以及 ARGs 和功能基因的丰度的影响不同。两种抗生素的作用导致根际土壤中 accA、tet(34)、tnpA-04 和 sul2 的绝对丰度高于非根际土壤，且根际土壤和非根际土壤的细菌群落组成和生物标志物不同。然而，OTC 对非根际土壤中少数功能基因的丰度的抑制作用强于 SDZ，且两者组合对植物生长、ARGs 和功能基因没有协同作用。共存的 OTC 和 SDZ 的作用降低了株高，增加了根 N 浓度。结果表明，环境相关浓度的抗生素改变了土壤微生物群落结构，增加了 ARGs 的丰度，降低了功能基因的丰度。此外，抗生素对土壤的污染会通过对作物的植物毒性作用来减少农业生产，并且应该考虑抗生素对植物生长和养分吸收的联合作用。
