Engemann Christina A, Keen Patricia L, Knapp Charles W, Hall Kenneth J, Graham David W
Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, Kansas 66045, USA.
Environ Sci Technol. 2008 Jul 15;42(14):5131-6. doi: 10.1021/es800238e.
Antibiotic resistance genes (ARGs) are emerging contaminants that are being found at elevated levels in sediments and other aquatic compartments in areas of intensive agricultural and urban activity. However, little quantitative data exist on the migration and attenuation of ARGs in natural ecosystems, which is central to predicting their fate after release into receiving waters. Here we examined the fate of tetracycline-resistance genes in bacterial hosts released in cattle feedlot wastewater using field-scale mesocosms to quantify ARG attenuation rate in the water column and also the migration of ARGs into peripheral biofilms. Feedlot wastewater was added to fifteen cylindrical 11.3-m3 mesocosms (some of which had artificial substrates) simulating five different receiving water conditions (in triplicate), and the abundance of six resistance genes (tet(O), tet(W), tet(M), tet(Q), tet(B), and tet(L)) and 16S-rRNA genes was monitored for 14 days. Mesocosm treatments were varied according to light supply, microbial supplements (via river water additions), and oxytetracycline (OTC) level. First-order water column disappearance coefficients (kd) for the sum of the six genes (tetR) were always higher in sunlight than in the dark (-0.72 d(-1) and -0.51 d(-1), respectively). However, water column kd varied among genes (tet(O) < tet(W) < tet(M) < tet(Q); tet(B) and tet(L) were below detection) and some genes, particularly tet(W), readily migrated into biofilms, suggesting that different genes be considered separately and peripheral compartments be included in future fate models. This work provides the first quantitative field data for modeling ARG fate in aquatic systems.
抗生素抗性基因（ARGs）是新出现的污染物，在农业和城市活动密集地区的沉积物及其他水体环境中，其含量正不断升高。然而，关于ARGs在自然生态系统中的迁移和衰减，目前几乎没有定量数据，而这对于预测其排放到受纳水体后的归宿至关重要。在此，我们利用野外尺度的中型生态系统，研究了牛饲养场废水中释放的细菌宿主内四环素抗性基因的归宿，以量化水柱中ARGs的衰减速率以及ARGs向周边生物膜的迁移。将饲养场废水添加到15个圆柱形的11.3立方米中型生态系统（其中一些带有人工基质）中，模拟5种不同的受纳水体条件（每组3个重复），并监测6种抗性基因（tet(O)、tet(W)、tet(M)、tet(Q)、tet(B)和tet(L)）以及16S - rRNA基因的丰度，为期14天。中型生态系统的处理根据光照供应、微生物补充（通过添加河水）和土霉素（OTC）水平而有所不同。6种基因总和（tetR）在阳光下的一级水柱消失系数（kd）始终高于黑暗条件下（分别为-0.72 d⁻¹和-0.51 d⁻¹）。然而，水柱kd在不同基因间存在差异（tet(O) < tet(W) < tet(M) < tet(Q)；tet(B)和tet(L)低于检测限），并且一些基因，特别是tet(W)，很容易迁移到生物膜中，这表明不同基因应分别考虑，且未来的归宿模型应纳入周边环境。这项工作为水生系统中ARGs归宿建模提供了首批定量野外数据。
