摘要

乳制品废水在农业土壤中的应用是灌溉作物和回收农业的一种广泛使用的做法。在这项研究中，小规模田间每月灌溉（6次）乳制品废水（100％），废水用灌溉（渠道）水稀释至50％，稀释废水加入硫酸铜（50 mg Cu L-1） ），而控制地块用运河水灌溉。此外，所有地块的一半都是种植小麦或留下裸土。在此期间收集双周土壤样本并进行处理以确定抗生素抗性基因[blaCTX-M-1，erm（B），sul1，tet（B），tet（M）和tet（X）的发生和丰度通过定量实时PCR（qPCR）检测1类整合子 - 整合酶基因（intI1）。在应用废水处理之前，在土壤中检测到只有sul1和tet（X）（32个样品中的3个）。但是，大多数基因[erm（B），intI1，sul1和tet（M）]的发生和相对丰度（标准化为16S rRNA基因拷贝）在废水灌溉后显着增加，并且在整个研究期间保持水平。 blaCTX-M-1是废水处理土壤中唯一未检测到的基因，这可能与其在乳品废水中的缺失有关。无论施用的废水百分比和植物的存在与否，在大多数情况下，在处理之间发现土壤中的相对基因水平在统计学上是相似的。这项研究的关键结果是，乳品污水灌溉显着扩大了土壤中ARGs和intI1的储存量，而这些基因的检测很少发生在仅用运河水灌溉的土壤中。此外，废水和处理过的土壤中Cu含量的升高不会同时产生ARG水平的增加。

The application of dairy wastewater to agricultural soils is a widely used practice to irrigate crops and recycle nu-trients. In this study, small-scale field plots were irrigated monthly (6 times) with dairy wastewater (100%),wastewater diluted to 50% with irrigation (canal) water, and diluted wastewater spiked with copper sulfate (50 mg Cu L−1), while control plots were irrigated with canal water. In addition, half of all plots were either planted with wheat or were left as bare soil. Biweekly soil samples were collected during this period and proc-essed to determine the occurrence and abundance of antibiotic resistance genes [blaCTX-M-1, erm(B), sul1, tet(B), tet(M), and tet(X)] and a class 1 integron-integrase gene (intI1) via quantitative real-time PCR (qPCR).Only sul1 and tet(X) were detected in soil (3 out of 32 samples) before the wastewater treatments were applied.However, the occurrence and relative abundance (normalized to 16S rRNA gene copies) of most genes [erm(B),intI1, sul1, and tet(M)] increased dramatically after wastewater irrigation and levels were maintained during the entire study period. blaCTX-M-1 was the only gene not detected in wastewater-treated soils, which is likely related to its absence in the dairy wastewater. Relative gene levels in soil were found to be statistically similar among the treatments in most cases, regardless of the wastewater percentage applied and presence or absence of plants. The key result from this study is that dairy wastewater irrigation significantly enlarges the reservoir of ARGs and intI1 in soils, while detection of these genes rarely occurred in soil irrigated only with canal water. In addition, elevated levels of Cu in the wastewater and treated soil did not produce a concomitant increase of the ARG levels.

https://www.sciencedirect.com/science/article/pii/S0048969718311562