城市污水处理厂二级出水中抗生素抗性基因分布特性及相关性分析

Analysis of distributive features and correlation of antibiotic resistance genes in secondary effluent of urban sewage treating plants

采用相对分子质量分级试验,对城市污水处理厂二级出水中的抗生素抗性基因(Antibiotic Resistance Genes,ARGs)和溶解性有机物(DOC)相对分子质量分布、ARGs与16S rRNA、Ⅰ类整合子(intⅠ1)和DOC相关性进行研究。结果表明,二级出水中试验所选的5种ARGs和转移原件Ⅰ类整合子intⅠ1均被检出,tet X和sulⅠ含量最高,分别为1. 28×10^7copies/L和5. 01×10^7copies/L;另外各ARGs的相对分子质量主要分布在大于100 kDa范围,且100 kDa、3 kDa膜片上的截留ARGs浓度明显高于30 kDa和10 kDa膜片;二级出水中游离态各类ARGs均多于细胞态的ARGs;通过相关性分析方法发现,除tet X的其他ARGs均与16S rRNA、intⅠ1和DOC有很高的相关性,可为考察水中ARGs的存在状况及更有效地去除ARGs提供基本理论支撑。

In this paper,the author intends to conduct tests for the molecular weight fractionation by using 4 kinds of ultrafiltration membranes with the molecular weight cut-offs of 100 kDa,30 kDa,10 kDa and 3 kDa. The analysis has been made to test the molecular weight distributions of the antibiotic resistance gene (ARG) and the dissolved organic matters (DOC) in the secondary effluent for the Convenience to discuss the surviving forms of the ARGs in the secondary effluent so as to work out the correlation among the ARGs,16S rRNA,the class I integrant (intI 1) and the DOC. The results of our analysis have finally demonstrated that it would be possible to detect 6 kinds of ARGs and intI 1 in the secondary effluent,with the highest levels of tet X and sulI,exactly accounting for 1. 28 × 10~7 copies/L and5. 01 × 10~7 copies/L,respectively,with tet A and tet C. The concentration range of tet G,tet X and sulI I stands for 105-10~6 copies/mL,which indicates that it won’t be possible for ARGs to be effectively removed in the urban sewage treating plant. The molecular weights of all the ARGs are mainly distributed within the range of over 100 kDa. What is more,the proportions of tet A,tet C tet G,sulI and sulI I have been found respectively to be equal about to 97. 2%, 90. 8%, 86. 8%, 92. 7%, and85. 1 %. And,furthermore,the results of ARGs in the currently existing forms of the ARGs suggest that the ARGs in the secondary effluent prove mainly to be existing in the free state,with the contents of various ARGs,intI 1 and 16S rRNA being equal to 1. 42 × 10^6 copies/L,4. 30 × 10^4 copies/L,1. 01 × 10^6 copies/L,2. 30 × 10^7 copies/L,1. 28× 10^7 copies/L,2. 25 × 10^8 copies/L,3. 23 × 10^8 copies/L and1. 02 × 109 copies/mL,in which the intracellular and extracellular contents of tet G and sulI turn out quite different. And,what is more,when the correlation test has been made by the linear fitting method analysis,all the other ARGs have been found in the positive correlation (p < 0. 05) with 16S rRNA,intI 1 and DOC,which imply that controlling the concentration rates of the elements involved in the transfer,the resistant bacteria and the organic matters in the urban sewage treatment plants serve as the key contributive factors to the ARGs removal. In addition to tet X,the participating contents of the experiment we have adopted can provide the basic theoretical support to examine the existence of ARGs in the water and more effective removal of ARGs.