Community Diversity And Resistence Mechanism Of The Chlorine-resistant Bacteria In Drinking Water Distribution System

The microbial safety is one of the important contents of drinking water quality and safety.However, bacterium chlorine-resistant, which has a high tolerance to chlorine in drinking water distribution system, is a threat to the drinking water quality.From the perspective of Microbiology, we study on the water and biofilm in water supply pipeline.The population diversity of chlorine-resistant bacterium in water supply network were analyzed.And then we studied the disinfection characteristics of several strains of chlorine-resistant bacteria isolated from real distribution systems, explored the mechanism of disinfection of the bacteria.Great changes in microbial community structure before and after chlorination of water. Before adding chlorine disinfectant,microbial mainly belong to gamma proteobacteria microorganisms and after adding chlorine disinfectant,microbial mainly belong to Beta Proteobacteria.Before and after adding chlorine disinfectant,the dominant bacteria were Pseudomonas sp. and Acidovorax sp.respectively.The dominant bacteria in the beginning of the water supply network are Acidovorax sp.which belong to Beta Proteobacteria.The dominant bacteria in the middle of the water supply network are Sphingomonas sp.which belong to Alpha Proteobacteria.The dominant bacteria in the termina of the water supply network are Pseudomonas sp.which belong to Beta Proteobacteria.The Proteobacteria is the dominant bacteria in whole water supply,and the proportion of chlorine-resistant bacteria which belong to Alpha Proteobacteria,Beta Proteobacteria and gamma proteobacteria is 52.6%,36.8% and 10.6%.Sphingomonas sp.which belongs to Alpha Proteobacteria is dominant bacteria in the water and Sphingomonas sp.,Sphingopyxis sp.,Brevundimonas sp.,Acidovorax sp.are dominant bacteria in the biofilm. For the water supply pipe network,the difference of the bacterial community structure between the beginning and the middle of the pipe network was little,but there was a big difference in the structure of bacteria community in the middle and distal part of the terminal.The biological diversity of resistance to chloride in water supply network are:the beginning <the middle<the terminal.We studied the disinfection characteristics of several strains of chlorine-resistant bacteria isolated from real distribution systems, the chlorine resistant ability of Sphingomonas sp. and Acidovorax sp. is better than Pseudomonas sp.In the process of chlorine disinfection, chlorine decay associated with bacterial concentration, little relation with temperature.PH is basically unchanged during the process of chlorine disinfection.Finally, this paper studies the effect of the characteristics of the bacteria on thechlorine resistance.Three chlorine-resistant bacterium have hydrophobic nature,which can prevent the chlorine disinfectant from entering into the cell.Three chlorine-resistant bacterium have certain adsorption characteristics, which can be adsorbed on the inner wall of the pipe to form biofilms to reduce the disinfection effect.The content of saturated fatty acids of acidovorax sp. is relatively high, and the barrier function of cells of acidovorax sp. is strong, so it has good resistance to chlorine disinfectant.