农田土壤抗生素抗性基因与重金属分布状况
Distribution of Antibiotic Resistance Genes and Heavy Metals in Agricultural Soil
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摘要:
目的 研究农田土壤抗生素抗性基因(ARGs)及重金属的分布状况。 方法 在河南省某地工业区附近农田(观察区)及对照地区共9个采样区(观察区7个,对照区2个),收集16个土壤混合样本(观察区14个,对照区2个),经腐殖酸脱除剂处理后试剂盒提取土壤总DNA。通过聚合酶链反应(PCR)检测土壤中5类15种ARGs (sulⅠ、sulⅡ、 tetA、tetC、tetE、tetM、tetQ、tetW、CTX-M-1、bla-TEM、SHV、strA、qnrA、qnrB、qnrS)。PCR检测阳性结果送公司测序,并通过GenBank数据库采用BLAST软件进行同源性比对。采用原子吸收分光光度法测定土壤中总汞含量;原子荧光光谱法测定土壤中总砷含量;电感耦合等离子体发射光谱法测定土壤中铅、锌含量;电感耦合等离子体质谱法测定土壤中镉、铬、镍、铜的含量。 结果 观察区土壤共检测出sulⅠ、sulⅡ、tetC、tetA、tetM、bla-TEM、tetE、tetW、strA 9种ARGs;除铬外,余7种重金属存在不同程度超标,其中镉和铅最大超标倍数达72.7和6.5。对照区农田土壤中未检测到ARGs,且无一重金属含量超标。ARGs阳性土壤中镉含量超标率为100%;而ARGs阴性土壤中各种重金属均未超标。 结论 河南某地工业区附近农田土壤中抗生素抗性基因tetC、bla-TEM的分布广泛,同时主要存在重金属镉、铅污染。 Abstract:Objective To describe the distribution of antibiotic resistance genes (ARGs) and heavy metals in soil of selected agricultural areas. Methods Sixteen mixed soil samples were collected from seven observation farmlands near an industrial zone (14 samples) and two control farmlands (2 samples). Total DNA in soil samples was extracted by soil DNA kit after pretreated with humic acid removal agent. Fifteen kinds of ARGs (sulⅠ, sulⅡ, tetA, tetC, tetE, tetM, tetQ, tetW, CTX-M-1, bla-TEM, SHV, strA, qnrA, qnrB, and qnrS) were detected by polymerase chain reaction (PCR). Positive productions of PCR were out-sourced to be sequenced and using BLAST to compare sequences to Genbank. Mercury in soil samples was determined by atomic absorption spectrophotometry, arsenic by atomic fluorescence spectrometry, lead and zinc by inductively coupled plasma atomic emission spectrometry, as well as cadmium, chromium, nickel, and copper by inductively coupled plasma mass spectrometry. Results Nine kinds of ARGs (sulⅠ, sulⅡ, tetC, tetA, tetM, bla-TEM, tetE, tetW, and strA) were found positive in the soil samples from the observation farmlands. Besides, the concentrations of seven heavy metals, except chromium, in the soil samples from the observation farmlands exceeded the relevant standard values by varied degrees; specifically, the maxmium concentrations of cadmium and lead were 72.7 and 6.5 times of the corresponding standard values respectively. In control area soil samples, no ARGs or heavy metals with any concentration exceeding standard were found. The exceeding-standard rate of cadmium was 100% in the ARGs positive soil samples, whereas none of the heavy metals was found exceeding standard in the ARGs negative soil samples. Conclusion ARGs such as tetC and bla-TEM are prevalent in the agricultural soil near the industrial zone in Henan where cadmium and lead are the dominant heavy metal pollutants.
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