Survival Of E. Coli O157:h7 In Urban Water Bodies For Aesthetical And Recreational Uses In Changchun

The main urban water bodies for aesthetical and recreational uses in Changchun include Nanhu Lake,Beihu Lake and Jingyuetan Lake.There are many hydrophilic recreational activities in Nanhu Lake,Beihu Lake and Jingyuetan Lake.In spring,summer and autumn,there are many tourists splashing,swimming,fishing and rowing.Tourists may cause symptoms such as acute gastrointestinal diseases,respiratory diseases,ear discomfort,and eye discomfort after performing these hydrophilic entertainment projects.E.coli O157:H7 is a new pathogenic E.coli that can cause severe circulatory and gastrointestinal diseases in humans.Therefore,it is of practical urgency and practical significance to carry out research on the influence of E.coli O157 on the survival of major recreational water bodies in Changchun City,and to propose an effective risk management strategy based on this.This experiment takes three major recreational water bodies in Changchun as the research object,and takes enterohemorrhagic E.coli O157:H7 as the target pathogen.In the laboratory,the survival law of E.coli O157:H7 is mainly investigated to find out the key influencing factor of E.coli O157:H7 survival in Changchun recreational water body.In this experiment,48 water samples from three major recreational water bodies in Changchun were collected in two batches in spring and autumn.The physical and chemical properties were determined,16S rRNA high-throughput sequencing,and the target pathogen E.coli O157:H7 was inoculated for survival experiments.Finally,the key factors affecting the survival time of E.coli O157:H7were analyzed.The main conclusions are:?1?The number of E.coli O157:H7 gradually decreased with the increase of culture time,and the survival curves were concave?p<1?except for individual samples.E.coli O157:H7 has the shortest time to fall to the first order of magnitude,and the overall decline trend is fast first and then slow.The average survival time of E.coli O157:H7 in spring was longer than that in autumn.The survival time of E.coli O157:H7 in spring is between 35-135 days,with an average of 67 days;the survival time of E.coli O157:H7 in autumn is between 31-106 days,with an average of 59days.E.coli O157:H7 has the longest survival time in water samples from Beihu Lake,followed by Nanhu Lake,and the shortest survival time is in Jingyuetan Lake.The survival time of E.coli O157:H7 in Nanhu Lake ranges from 31 to 107 days,with an average of 65 days;the survival time of E.coli O157:H7 in Jingyuetan Lake ranges from 35 to 74 days,with an average of 50 days;E.coli O157:H7 survived in Beihu for 38-130 days,with an average of 77 days.?2?According to the 16S rRNA high-throughput sequencing data,it was concluded that the sample complexity?Alpha Diversity?of the three major recreational water bodies in Changchun was different.Based on principal component analysis and microbial community network analysis,it is concluded that the Beta Diversity of the three major recreational water bodies in Changchun City are different.The community structure stability and diversity of Nanhu Lake are weaker than that of Beihu Lake and Jingyue Lake.Based on Mental test results and canonical correspondence analysis,it can be seen that the composition and diversity of microbial community structure are mainly affected by water such as EC?p<0.0001?,NH₄⁺-N?p<0.05?,TN?p<0.0001?,TOC?p<0.0001?Factors.The dominant bacteria in the three major recreational water bodies of Changchun are:Proteobacteria?33.57%?,Actinobacteria?29.45%?,Bacteroidetes?20.89%?,Cyanobacteria?11.78%?,and Verrucomicrobia?1.96%?.The results of community function prediction analysis showed that the community functions were different in amino acid transport and metabolism,nucleotide transport and metabolism,energy production and transformation,defense mechanism,and nuclear structure.?3?According to the linear correlation fitting results,it is known that the survival of E.coli O157:H7 is affected by recreational water environmental factors,including physical and chemical properties and the stability and diversity of the composition of the microbial community structure.In spring and autumn,the survival time of E.coli O157:H7 was positively correlated with EC content?p<0.05?,the survival time of E.coli O157:H7 was positively correlated with TOC content in water samples,and the total nitrogen content was survival with E.coli O157:H7.Time was positively correlated?P<0.05?,ammonia nitrogen content was negatively correlated with the survival time of E.coli O157:H7,and the survival time of E.coli O157:H7 was affected by seasonal changes.The survival of E.coli O157:H7 may also be indirectly affected by the structural stability and diversity of microbial communities in recreational waters.At present,there are few studies on the microbial risk of landscape recreational water bodies in China.The results of the research on the survival behavior of E.coli O157:H7 in recreational water bodies at room temperature can predict the environmental behavior of pathogenic bacteria,evaluate their environmental ecology and health risks,and control Large-scale outbreaks of E.coli O157:H7 infectious diseases provide background informations,and provide rich background information for establishing a healthy and stable aquatic ecosystem.