粪源环丙沙星对潮土中抗生素抗性基因的影响

Impacts of ciprofloxacin in duck feces on antibiotic resistance genes in ustic cambosols

为了探究粪源环丙沙星(Ciprofloxacin, CIP)对潮土中抗生素抗性基因(Antibiotic resistance genes,ARGs)的影响,布置培养试验(81 d),设置5个处理,分别为Ⅰ:CK(对照),Ⅱ:CIP(外源添加CIP),Ⅲ:DF(不含CIP的鸭粪),Ⅳ:DF+CIP(Ⅲ基础上外源添加CIP),Ⅴ:DF(CIP)(粪源CIP)。采用PCR技术分析土壤中6大类27种抗生素抗性基因和4种可移动遗传元件的检出情况,并利用荧光定量PCR技术对检出频率较高的目的基因及总细菌基因(16S rRNA)的绝对丰度进行检测。结果表明:不同处理土壤中共检出6种ARGs(tet G、sulⅠ、qnr A、qnr S、aad A2、aad D)和1种可移动遗传元件(intⅠ),且检测到的目的基因基本一致。DF(CIP)和DF+CIP处理对土壤中细菌和不同种类ARGs的影响不同。DF(CIP)、DF+CIP处理均显著降低了土壤中16S rRNA、tet G的绝对丰度;DF(CIP)处理显著增加了土壤中sulⅠ、aad A2的绝对丰度;DF+CIP处理显著增加了土壤中qnr A的绝对丰度。不同种类的ARGs与intⅠ、土壤理化性质的偏相关性分析表明,土壤中intⅠ与sulⅠ、aad A2呈正相关,与qnr A呈负相关,qnr A与CIP残留量呈正相关,tet G与有机质呈正相关。研究结果可为科学地评价氟喹诺酮类抗生素的环境风险以及粪肥的合理施用提供一定的理论依据。

In order to explore the impacts of ciprofloxacin in duck feces on antibiotic resistance genes(ARGs)in ustic cambosols,an81-d soil culture experiment was conducted with five treatments:CK(control),CIP(ciprofloxacin),DF(duck feces),DF+CIP(DF with added CIP),and DF(CIP)(DF containing CIP).Twenty-seven kinds of ARGs and four kinds of mobile genetic elements(MGEs)were detected by polymerase chain reaction(PCR)testing.Absolute abundance of target genes with relatively high detection rates and total bacterial gene(16S rRNA)were determined by quantitative real time PCR testing.The results showed that six ARGs(tetG,sulⅠ,qnrA,qnrS,aadA2,and aadD)and one MEG(intⅠ)were found in different treatments,and these genes were essentially identical.The effects of DF(CIP)and DF+CIP on ARGs and bacteria in soil were different.Compared with DF,DF(CIP)and DF+CIP significantly reduced the absolute abundance of tetG and16S rRNA.DF(CIP)enhanced the absolute abundance of sulⅠand aadA2,and DF+CIP enhanced the absolute abundance of qnrA.Partial correlation analysis among ARGs,MGEs and soil physicochemical properties,showed that intⅠwas significantly positive correlated with sulⅠand aadA2,but was significantly negatively correlated with qnrA.The positive correlation was observed between qnrA and residual contents of ciprofloxacin,and between tetG and soil organic matter.The results of this study provide a theoretical basis for scientific assessment of environmental risks posed by fluoroquinolones and suitable application of manure.