Characterization and quantification of class 1 integrons and associated gene cassettes in sewage treatment plants
Characterization and quantification of class 1 integrons and associated gene cassettes in sewage treatment plants
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DOI：
10.1007/s00253-009-1886-y
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发表时间：
2009-04-01
影响因子：
5
通讯作者：
Cheng, Shu-Pei
中科院分区：
文献类型：
--
作者：
Zhang, Xu-Xiang;Zhang, Tong;Cheng, Shu-Pei
本研究采用聚合酶链式反应（PCR）、测序和实时荧光定量PCR （qRT-PCR）技术对5个不同污水处理厂（STPs）中含有抗生素耐药基因（ARGs）的1类整合子和基因盒进行了表征和定量。1类整合酶基因（intI1）普遍存在于五个污水处理厂的所有活性污泥样本中，以及香港两个污水处理厂的进水和流出物中。从沙田绿化厂活性污泥中分离到酵母菌科（LFE） 109株。其中36株（33.0%）携带1类整合子。PCR分析表明，在36株携带inti1的分离株中，有11株在1类整合子上含有约1,600 bps的通用型基因盒阵列，以及静态基因（sulI和qacE Delta 1）。该基因盒阵列在系统发育上与耐药基因dfr17和aadA5接近，分别编码对甲氧苄氨嘧啶耐药的二氢叶酸还原酶和对大霉素/链霉素耐药的腺苷基转移酶。药敏分析表明，携带基因盒的11株lfe均具有多重耐药，特别是对甲氧苄氨嘧啶和链霉素具有共同耐药。qRT-PCR分析显示，在不同stp、不同时间点或不同处理步骤取样的活性污泥中，1类整合子和基因盒的基因拷贝数存在显著差异。两个STP的活性污泥法去除了90%以上的1类整合子和基因盒，而一个STP的消毒法去除了94%的整合子和77%的基因盒。
Class 1 integrons and gene cassettes containing antibiotic resistance genes (ARGs) in five different sewage treatment plants (STPs) were characterized and quantified using polymerase chain reaction (PCR), sequencing, and quantitative real-time PCR (qRT-PCR) in this study. Class 1 integronase gene (intI1) was found commonly occurring in all of activated sludge samples from the five STPs, as well as in influent and effluent of two STPs at Hong Kong. One hundred and nine lactose-fermenting Enterobacteriaceae (LFE) strains were isolated from activated sludge of Shatin STP. Among them, 36 strains (33.0%) were found to carry class 1 integrons. PCR assays showed that 11 of the 36 intI1-carrying isolates harbored a common type of gene cassette array of about 1,600 bps, as well as the static genes (sulI and qacE Delta 1) on class 1 integrons. This gene cassette array was found phylogenetically close to antibiotic resistance genes dfr17 and aadA5, encoding dihydrofolate reductase conferring resistance to trimethoprim and adenylyltransferase conferring resistance to spectinomycin/streptomycin, respectively. Antimicrobial susceptibility analysis demonstrated that all the 11 LFEs carrying gene cassette were multi-resistant, especially having common resistance to trimethoprim and streptomycin. qRT-PCR assay showed that genes copies of both class 1 integron and the gene cassette varied significantly among the activated sludge sampled from different STPs, at different time points or different treatment steps. More than 90% of class 1 integrons and the gene cassette were removed by activated sludge processes in two STPs, while the disinfection process removed 94% integron and 77% gene cassette in one STP.