Study On Antibiotic Resistance Of Heterotrophic Bacteria And Microbial Community Structure In The Landscape Lake Filled With Reclaimed Water

The community structure and biochemical characteristics of microorganisms in the landscape lake will be changed with the supply of reclaimed water, however, the study on this topic is rarely. According to the technical route of field sampling investigation and vitro simulated experiments, the antibiotic resistance of heterotrophic bacteria and the change of the microbial community structure in the landscape lake which was supplied by the effluent of A2O-MBR treatment process were studied by biochemical analysis, molecular biological detection and analysis technique. This study is significant to evaluate the safe and effective control technology of the landscape lake supplied with reclaimed water.The results showed that: the physical and chemical characteristics including NH3-N, TOC, p H, turbidity, and chromaticity except TP in the effluent of A2O- MBR process could meet the standard of landscape water. The resistance rate of heterotrophic bacteria in reclaimed water to sulfamethoxazole, ampicillin, tetracycline, ciprofloxacin and cefotaxime were 11.53%, 8.11%, 5.42%, 0.047% and 0.14%, respectively. The resistance rates of heterotrophic bacteria to five kinds of antibiotics were significantly decreased to less than 0.5% when the reclaimed water entered into the lake landscape. There was not significant correlation between resistance rates and the concentration of heterotrophic bacteria to physical and chemical indicators, indicating that physical and chemical indicators couldn’t represent bacteria contamination of landscape water. The structure of microbial communities was affected when reclaimed water was supplied for landscape water, which caused the disappearance of some original speciesand the occurrence of pathogenic bacteria or conditional pathogenic bacteria.The dynamic process of reclaimed water supplied for landscape water was simulated according to the replacement period of artificial lake in Siyuan College. The resistance rate of heterotrophic bacteria, resistance genes and the change of community structure were studied during the supply. The results showed that: the resistance rates of heterotrophic bacteria were continuously reduced in the process of simulation. The tetracycline resistant genes were mainly tet A and tet C and the sulfamethoxazole resistant gene of HPB was mainly sul2. The ARGs which do not exist originally in landscape lake were introduced into water with the replenishment of landscape lake using reclaimed water. The dominant bacteria in different microbial community which was resistant to tetracycline, ampicillin and sulfamethoxazole were Enterobacter amnigenus and Pseudomonas sp, Acinetobacter sp and Pseudomonas sp, respectively. The microbial community structure of resistance to antibiotics of heterotrophic bacteria was basically stable with the rise of similarity matrix in late simulation process. The involving of reclaimed water to landscape water caused the disappearance of some original pathogenic bacteria, while this involving could provide a suitable environment for the conditional pathogenic bacteria.