Abstract：
Limited attention has been given to the interaction between antibiotics and arsenic in the soil-plant system. In this investigation, Medicago sativa seedlings were grown in soil treated with cow manure containing oxytetracycline (OTC) or sulfadiazine (SD), as well as arsenic (introduced through roxarsone, referred to as ROX treatment). The study revealed a notable increase in As(III) and dimethylarsinic acid (DMA(V)) levels in rhizosphere soils and plant root tissues as arsenic contamination intensified in the presence of antibiotics, while concentrations of As(V) and monomethylarsonic acid (MMA(V)) decreased. Conversely, elevated antibiotic presence resulted in higher levels of As(V) but reduced DMA concentrations in both rhizosphere soils and plant root tissues in the presence of arsenic. The arsenic biotransformation gene aioA was inhibited by arsenic contamination when antibiotics were present, and suppressed by antibiotic contamination in the presence of arsenic, especially in SD treatments, resulting in reduced expression levels at higher SD concentrations. Conversely, the arsM gene exhibited consistent upregulation under all conditions. However, its expression was found to increase with higher concentrations of ROX in the presence of antibiotics, decrease with increasing SD concentrations, and initially rise before declining with higher levels of OTC in the presence of arsenic. Bacterial genera within the Proteobacteria phylum, such as Geobacter, Lusitaniella, Mesorhizobium, and Methylovirgula, showed significant co-occurrence with both aioA and arsM genes. Correlation analysis demonstrated associations between the four arsenic species and the two arsenic biotransformation genes, emphasizing pH as a critical factor influencing the transformation and uptake of different arsenic species in the soil-plant system. The combined stress of antibiotics and arsenic has the potential to modify arsenic behavior and associated risks in soil-plant systems, highlighting the necessity of considering this interaction in future research endeavors.
摘要：
土壤-植物系统中抗生素与砷之间的相互作用受到的关注有限。在这次调查中,紫花苜蓿幼苗在用含有土霉素（OTC）或磺胺嘧啶（SD）的牛粪处理的土壤中生长，以及砷（通过roxarsone引入，称为ROX治疗)。研究表明，随着砷污染在抗生素存在下加剧，根际土壤和植物根组织中的As（III）和二甲基亚麻酸（DMA（V））水平显着增加，而As（V）和单甲基arsonic酸（MMA（V））的浓度降低。相反，在砷存在的情况下，抗生素的存在升高会导致As（V）的含量升高，但根际土壤和植物根组织中的DMA浓度降低。当存在抗生素时，砷生物转化基因aioA被砷污染抑制，在砷的存在下被抗生素污染抑制，尤其是在SD治疗中，导致在较高的SD浓度下表达水平降低。相反，在所有条件下，arsM基因均表现出一致的上调。然而,在抗生素的存在下，随着ROX浓度的增加，其表达增加，随着SD浓度的增加而降低，在砷存在下，随着OTC水平的升高，最初上升，然后下降。变形杆菌门内的细菌属，比如Geobacter,Lusitaniella,中根瘤菌,和甲基维古拉，与aioA和arsM基因均显示出显着的共现。相关分析表明四种砷物种与两种砷生物转化基因之间存在关联，强调pH是影响土壤-植物系统中不同砷物种转化和吸收的关键因素。抗生素和砷的联合胁迫有可能改变土壤-植物系统中的砷行为和相关风险，强调在未来的研究工作中考虑这种相互作用的必要性。
