磺胺甲(口恶)唑对海水养殖废水处理过程中抗性细菌及抗性基因的富集作用

Enrichment of Antibiotic Resistant Bacteria and Antibiotic Resistance Genes by Sulfamethoxazole in the Biological Treatment System of Mariculture Wastewater

抗生素在海水养殖过程中大量使用,但仅有少部分被生物体利用,含有抗生素的废水进入水处理系统后,抗生素、抗性菌和抗性基因的响应过程尚不完全清楚.应用缺氧/好氧移动床生物膜反应器(A/O-MBBR)处理含磺胺甲(口恶)唑(SMX)的海水养殖废水,探究在SMX选择压力下,反应器内抗生素和抗性基因丰度的变化规律,以及微生物群落和可培养的抗性细菌种群的响应.结果表明,在进水SMX浓度为500μg·L^(-1),水力停留时间为8 h,SMX加入初期会对NH_(4)^(+)-N和NO_(2)^(-)-N的去除率有轻微影响,随后逐步恢复;同时去除约32%的SMX,且78%以上SMX在缺氧区完成;抗性基因在缺氧区富集明显高于好氧区,在缺氧区磺胺类抗性基因(sul1)绝对丰度上升2.43 log,磺胺类抗性基因(sul2)上升1.71 log;而在好氧区,sul1绝对丰度上升1.17 log,sul2上升0.91 log.抗性平板培养结合高通量测序表明,假交替单胞菌属(Pseudoalteromonas)在反应器可培养抗性细菌中占最优势.高通量测序分析发现可培养的抗性细菌假单胞菌属(Pseudomonas)在反应器内占比最高.表明含SMX的海水养殖废水可促进水中抗性基因的富集,部分抗性细菌的数量显著增加.

Although antibiotics are heavily used in mariculture,only a small portion of the added antibiotics is absorbed.Little is known about the response process of antibiotics,antibiotic resistant bacteria,and antibiotic resistance genes to antibiotic-containing wastewater entering a wastewater treatment system.In this study,an anoxic/aerobic moving bed biofilm reactor(A/O-MBBR) was used to treat marine aquaculture wastewater containing sulfamethoxazole(SMX).The antibiotics and resistance genes in the reactor were then evaluated under selective SMX pressure,and the changing abundance patterns and the response of microbial communities and cultivable resistant bacterial populations were further explored.The results show that with an influent SMX concentration of 500 μg·L^(-1) and a hydraulic retention time of 8 h,SMX had a slight effect on the removal rate of NH_(4)^(+)-N and NO_(2)^(-)-N,following which the performance gradually recovered.During this stage,SMX removal reached approximately 32%,with more than 78% of SMX removed from the hypoxic zone.The resistance gene was more significantly enriched in the hypoxic zone than in the aerobic zone.In the hypoxic zone,the absolute abundance of gene sul1 increased by 2.43 log,whereas that of gene sul2 increased by 1.71 log.In the region,the absolute abundance of sul1 increased by 1.17 log,whereas that of sul2 increased by 0.91 log.Resistant plate culture and highthroughput sequencing showed that the genus Pseudoalteromonas was the most dominant culturable resistant bacteria in the reactor.The genus Pseudomonas predominated in the uncultured resistant bacteria in the reactor.This study showed that marine aquaculture wastewater containing SMX promotes the enrichment of resistance genes,causing the abundance of some resistant bacteria to increase significantly.