Study On Antibiotic Resistance Genes In Microbial Fuel Cell Coupled With Constructed Wetlands

Antibiotics are widely used in worldwide due to they can improve the quality of life. Most of antibiotics cannot be metabolized completely, they will be excreted outside in the form of original or active metabolite. After they enter the environment, Antibiotic Resistance Genes(ARG)will be induced. Antibiotic induce ARGs and ARGs transfer to pathogenic microorganisms will threat human health directly.Microbial Fuel Cell(MFC) and Constructed Wetland(CW) both have good property in removing refractory organics. Potential of purification and favorable condition on structure, this study built new MFC coupled with CW (MFC-CW). Sul ARGs and tet ARGs are selected as research object. Main research achievements are as followings:3 types of sul ARGs(sul 1?sul 2?sul 3) and 5 types of tet ARGs(tet A?tet C?tet O? tet Q?tet W) were detected in water samples and filter samples in MFC-CWs and CWs. The orders of relative abundance of sul ARGs in water samples in both MFC-CWs and CWs were sul 1>sul 2>sul 3, while let ARGs is tet A>tet C>tet Q>tet O>tet W. In MFC-CW filter samples, the order of relative abundance of sul ARGs was as same as water samples, while for tet ARGs was tet A>tet C>tet W, tet 0 and tet Q is lower.Relative abundance of 8 types of ARGs in water samples in MFC-CW was lower than CW in the same group(P<0.05, except for tet O). Electron flows in MFC-CW could accelerate microbials degradation rate of antibiotics and eliminate some resistance plasmids.In the effluent of MFC-CWs and CWs, the concentration of Sulfamethoxazole (SMX) had no significant correlation with 3 types of sul ARGs. Relative abundance of sul ARGs could be influenced by other factors rather than concentration of antibiotics, for instance, cross-selectrion, ratio of plankton-creature and biofilm-creature in effluent and difference between relative abundance of ARGs in influent. The concentration of Tetracycline (TC) had significant correlation with tet ARGs in CW, while in MFC-CW, significant correlation between concentration of TC and tet ARGs only observed in high initial concentration group in tet O and tet Q.8 types of ARGs and 16S rRNA showed significant correlation in effluent of CWs, while the same results only show in sul 1 and let W in effluent of MFC-CW. Replication and transmission of ARGs were affected by concentration of background bacteria in environment. Electron flows in MFC-CW might affect expression of regulatory elements and membrane potential during horizontal transmission, which changed the correlation between ARGs and 16S rRNA.Researches on relative abundance of ARGs in microbials adsorbed on filters found a significant positive correlation between concentration of SMX and 3 types of sul ARGs and a significant positive correlation between concentration of TC and 5 types of tet ARGs. Total sul ARGs and total tet ARGs showed high relative abundance in two polars and low in middle in each MFC-CW.When HRT was 5 days, relative abundance of total sul ARGs and total tet ARGs were lower than HRT was 2.5days. Longer HRT is benefit to reduce relative abundance of total sul ARGs and total tet ARGs in MFC-CW.Research on influence of coexistence carbon resource concentration showed that the higher concentration of glucose in influent, the lower relative abundance of total sul ARGs and total tet ARGs in MFC-CW filters.