通过Miseq高通量测序分析和荧光定量PCR技术,研究某纳污河流中四环素类与磺胺类抗性基因(ARGs)的分布特征、传播情况及微生物群落结构相关性.结果表明:在河流地表水与沉积物中均检测到四环素类抗性基因tetA和tetB与磺胺类抗性基因sul1和...通过Miseq高通量测序分析和荧光定量PCR技术,研究某纳污河流中四环素类与磺胺类抗性基因(ARGs)的分布特征、传播情况及微生物群落结构相关性.结果表明:在河流地表水与沉积物中均检测到四环素类抗性基因tetA和tetB与磺胺类抗性基因sul1和sul2,四环素类抗性基因和磺胺类抗性基因的绝对丰度分别为5.09×10^3~1.26×10^7,3.94×10^5~1.32×10^9copics/L,磺胺sul1抗生素抗性基因丰度显著高于其它基因;河流主要优势菌门为Proteobacteria,Bacteroidetes,Firmicutes,Actinobacteria和Cyanobacteria,其平均总相对丰度占总比例的95.62%,且总体差异较小.抗性基因与微生物群落冗余分析显示, Methylotenera菌属是影响tetA抗性基因分布丰度的主要因素, Dechloromonas和Clostridium sensu stricto 1菌属是影响tetB抗性基因分布丰度的主要因素,Dechloromonas、Clostridium sensu stricto 1和Methylotenera菌属是影响sul1、sul2抗性基因分布丰度的主要因素.展开更多
The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the ...The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the volt- age/current on the Q235 were observed using real-time imaging during the PEC/N. The microstructure and element distribution of the carbonitriding layer were examined using scanning electron microscope （SEM） equipped with energy dispersive spectroscope （EDS）. The effect of microdischarge on roughness, thickness and microhardness was evalua- ted. The formation of the carbonitriding layer was discussed. Research shows that it is similar in the microstructure and properties between the plasma electrolytic carbonitriding and the traditional gas carbonitriding. The formation of the carbonitriding layer results from the carbon and nitrogen fluctuation in PEC/N process. The microhardness and thickness can be up to HV 779 and 0. 360 mm in 180 s, respectively, which is close to the results of the gas carboni- triding in the microhardness. Therefore, the plasma electrolytic carbonit^riding has a potential to substitute the gas carbonitriding.展开更多
文摘通过Miseq高通量测序分析和荧光定量PCR技术,研究某纳污河流中四环素类与磺胺类抗性基因(ARGs)的分布特征、传播情况及微生物群落结构相关性.结果表明:在河流地表水与沉积物中均检测到四环素类抗性基因tetA和tetB与磺胺类抗性基因sul1和sul2,四环素类抗性基因和磺胺类抗性基因的绝对丰度分别为5.09×10^3~1.26×10^7,3.94×10^5~1.32×10^9copics/L,磺胺sul1抗生素抗性基因丰度显著高于其它基因;河流主要优势菌门为Proteobacteria,Bacteroidetes,Firmicutes,Actinobacteria和Cyanobacteria,其平均总相对丰度占总比例的95.62%,且总体差异较小.抗性基因与微生物群落冗余分析显示, Methylotenera菌属是影响tetA抗性基因分布丰度的主要因素, Dechloromonas和Clostridium sensu stricto 1菌属是影响tetB抗性基因分布丰度的主要因素,Dechloromonas、Clostridium sensu stricto 1和Methylotenera菌属是影响sul1、sul2抗性基因分布丰度的主要因素.
基金Item Sponsored by National Natural Science Foundation of China(50901031)Fundamental Research Funds for Central Universities of China(2012B07414)
文摘The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the volt- age/current on the Q235 were observed using real-time imaging during the PEC/N. The microstructure and element distribution of the carbonitriding layer were examined using scanning electron microscope （SEM） equipped with energy dispersive spectroscope （EDS）. The effect of microdischarge on roughness, thickness and microhardness was evalua- ted. The formation of the carbonitriding layer was discussed. Research shows that it is similar in the microstructure and properties between the plasma electrolytic carbonitriding and the traditional gas carbonitriding. The formation of the carbonitriding layer results from the carbon and nitrogen fluctuation in PEC/N process. The microhardness and thickness can be up to HV 779 and 0. 360 mm in 180 s, respectively, which is close to the results of the gas carboni- triding in the microhardness. Therefore, the plasma electrolytic carbonit^riding has a potential to substitute the gas carbonitriding.
