人工湿地中抗生素抗性大肠杆菌和抗性基因的去除与分布

抗生素的滥用导致抗生素抗性菌和抗性基因随生活污水和养殖废水的排放在环境中肆意散播,其去除及环境行为越来越受到关注。采用K-B纸片法测定了9套不同工艺构型模拟人工湿地中大肠杆菌对7种抗生素的抗性率,并应用多重PCR检测磺胺类sul1、2、3与四环素tetA、B、C、D抗性基因,探究人工湿地对抗性菌的去除效率及抗性菌、抗性基因的分布规律。结果显示,人工湿地能有效去除污水中70%左右的抗性大肠杆菌,有效降低了细菌抗性的传播风险;共计分离出535株大肠肝菌中有378株对一种以上抗生素有抗性性,以四环素、磺胺类和氨苄西林抗性率最高,达到25%以上,其他4种抗性率较低,不足20%;2种抗性基因的检出率都在70%以上;对不同采样点大肠杆菌的抗性性及抗性基因的比较发现,各部分大肠杆菌的抗性水平、多重抗性指数(MRI)以及抗性基因(sul、tet)检出率和组合数表现出:基质≥出水>进水,推测抗性菌被湿地基质截留,在基质生物膜上发生抗性基因的重组,并释放抗性菌,提高了出水中抗性水平和抗性基因检出率。

Removal and distribution of antibiotic resistance E.coli and antibiotic resistance genes in constructed wetlands

Antibiotic resistance bacteria (ARBs) and antibiotic resistance genes (ARGs) are poured into environment with discharge of domestic sewage and husbandry wastewater due to misuse of antibiotics, which has been a public health concern. This study was aimed to investigate removal efficiency of antibiotic resistance E.coli and figure out distribution profile of antibiotics resistance of E.coli and resistance genes harbored in 9 different constructed wetlands. Totally, 535 strains were isolated from influent, biofilms and effluents, and all strains were tested for antimicrobial susceptibility to 7 antibiotics according to K-B Method. Multiplex PCR were applied to detect sul (sul1, sul2, sul3) and tet (tetA, tetB, tetC, tetD) in resistance E. coli strains. Against the antibiotics, E.coli exhibited different resistance levels, ampicillin,sulfamethoxazole trimethoprim and tetracycline were over 25%, higher than the other four antibiotics, which were even less than 20%. While for the two sorts of ARGs, both were above 70%. Comparing resistance levels, multiple resistance index and detection ratios of the two ARGs in various sites, we found a high to low order : biofilms>effluents>influent, which suggested that biofilms maybe play as retainer facilitating recombination of ARGs, releasing antibiotic resistance of E. coli and ARGs to vicinity flowing water, resulting in higher resistance levels and ratios of ARGs in effluents.