Remediating sulfadimethoxine-contaminated aquaculture wastewater using ZVI-activated persulfate in a flow-through system

Antibiotic resistant bacteria can result from the improper discharge of water from the aquaculture farming industry. This calls for the development of a low-cost remediation technology. Our research verified the use of ZVI-activated persulfate (PS) to treat antibiotic-contaminated aquaculture discharge water in a flow-through system. We selected sulfadimethoxine (SDM) as a representative antibiotic residual and tested SDM degradation under varying parameters: activator dose, initial pH, chloride concentration, activator dose and timing. The results demonstrated that increasing the ZVI dosage significantly decreased SDM degradation due to the scavenging effects for the persulfate radical (SO₄⁻). SDM decomposition occurred when SO₄⁻ attacked the aniline moiety via electron transfer prior to undergoing hydrogen abstraction/addition on the sulfonamide. A high pH produced the fastest degradation with reaction rates following the order pH 11 > > pH 9 > pH 3 > pH 5. A high Cl⁻ concentration (>100 mM) enhanced SDM degradation because of the production of chlorine radicals. The experiment results from ZVI sequential addition indicated that only a small continual input of ZVI was sufficient to generate SO₄⁻ to react with SDM. We used a flow-through concept for the real discharge water that was spiked with SDM prior to treating with PS/ZVI. The results showed that our system was able to remove approximately 68% of SDM from filtered and 74% from unfiltered discharge water. These results provide proof-of-concept that our PS/ZVI system could potentially be developed to remediate antibiotic-contaminated aquaculture wastewater.     

Veterinary antibiotics at environmentally relevant concentrations inhibit soil iron reduction and nitrification

Veterinary antibiotics used in food animal production, subsequently entering the agroecosystem through land application of animal manure, constitute a growing concern. Previous studies have reported inhibitory effects of antibiotics on soil microbial activities, however, treatment concentrations in these studies were often many times greater than the ranges typically found in the environment. When spiked into manure and mixed with soil at environmentally relevant concentrations in a laboratory study, sulfadimethoxine and monensin blocked soil iron reduction over periods extending from a few days to the entire 50-Day experiment. Sulfadimethoxine also had an inhibitory effect on soil nitrification periodically over the course of the study. Respiration and community-level physiological profile parameters were not inhibited by sulfadimethoxine, monensin, or chlortetracycline. We conclude that antibiotics at environmentally relevant concentrations can disrupt soil microbial processes, although the detection of such impact may be antibiotic and/or process specific.     

磺胺间二甲氧嘧啶人工抗原的合成与鉴定

用重氮化方法将SDM偶联于载体蛋白BSA和OVA上,合成免疫抗原BSA-SDM和包被抗原OVA-SDM,通过紫外扫描(UV)、SDS-PAGE凝胶电泳试验。结果显示:BSA-SDM和OVA-SDM的UV与BSA、SDM的相比均发生了改变,出现了明显的特征峰。这表明半抗原和载体偶联成功。用BSA-SDM免疫BALB/C小鼠,间接ELISA测定多抗上清(pAb)效价。结果表明,获得了高效价的pAb,为SDM残留免疫学检测方法的建立奠定了基础。     

磺胺二甲氧嘧啶免疫小鼠抗体重链可变区基因的克隆及序列分析

应用RT-PCR方法从磺胺二甲氧嘧啶免疫小鼠B细胞扩增和克隆抗SDM抗体VH基因。测序结果表明:抗SDM抗体VH基因为339 bp,编码113个氨基酸。用NCBI GenBank分析表明,抗SDM抗体VH基因符合小鼠抗体重链可变区特征,隶属于小鼠抗体重链SM7家族,由胚系基因VHSM7.a3.93-DSP2.9-JH1功能性重排形成。抗SDM抗体VH基因的克隆为抗SDM单链抗体的构建与表达奠定了基础。     

四种抗菌促长药物在团头鲂饲料中适宜添加量的初步研究

用正交法设计了九种不同配方的团头鲂鱼种饲料。饲养结果表明,团头鲂鱼种配合饲料中磺胺二甲嘧啶的适宜添加量为50×10-6,黄霉素为2×10-6,碘化酪蛋白为20×10-6,痢特灵为100×10-6。