摘要

       乳品废水在农业土壤中的应用是一种广泛应用的灌溉作物和养分循环利用的方法。本研究以乳品废水（100%）、灌溉（渠）水稀释至50%的废水、硫酸铜（50 mg Cu L-1）作为对照，对小型农田进行每月6次灌溉。此外，一半的土地要么种上小麦，要么留作裸土。在此期间，每两周采集一次土壤样本，通过定量实时PCR（qPCR）测定抗生素抗性基因（blaCTX-M-1、erm（B）、sul1、tet（B）、tet（M）和tet（X））和1类整合子整合酶基因（intI1）的发生率和丰度。污水处理前，土壤中仅检测到sul1和tet（X），32份样品中有3份。然而，在整个研究期间，污水灌溉后，大多数基因（erm（B）、intI1、sul1和tet（M））的发生率和相对丰度（标准化为16srrna基因拷贝数）显著增加，并且水平保持不变。blaCTX-M-1是废水处理土壤中唯一未检测到的基因，这可能与乳品废水中blaCTX-M-1的缺失有关。在大多数情况下，土壤中的相关基因水平在统计学上是相似的，无论废水的使用率和植物的存在与否。本研究的主要结果是，乳品废水灌溉显著增加了土壤中ARGs和intI1的蓄积量，而仅用渠水灌溉的土壤中很少检测到这些基因。此外，废水和处理过的土壤中铜含量的升高并不会导致ARGs含量的增加。

       The application of dairy wastewater to agricultural soils is a widely used practice to irrigate crops and recycle nutrients. 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 processed to determine the occurrence and abundance of antibiotic resistance genes [bla_CTX-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. bla_CTX-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?via%3Dihub