Correlations Between Bacteriophage And Bacterial Communities And Sludge Settling Performances In The Sewage Treatment Systems

Bacteriophages are the microorganisms that infect and splitting bacteria,the abundance of which is obviously higher than the abundance of bacteria.Therefore,bacteriophage plays a regulatory role of bacterial communities and the function of sewage treatment system.And yet,the study on the distribution and function of bacteriophage as well as the relationship between bacteriophage and bacteria is little in wastewater treatment system.In this work,we choose two wastewater treatment plants around Xinxiang city as the research objects and took activated sludges samples at the state of sludge bulking and the normal activated sludge(in May and October).We conducted the study on the community relationship between bacteriophage and bacteria at the state of sludge bulking and the normal activated sludge(in May and October)through fluorescence staining technique,high-throughout sequencing technology of bacteria,fractionation separation of phages and the metagenome sequencing technology of phage.The innovative points of the thesis include:(1)Through measuring the physicochemical properties of waste water,we found that activated sludge in May was at a state of sludge bulking while in October was the opposite.The abundance of virus in sewage is over 108 /m L in both May and October.At the state of sludge bulking,the abundance of bacteria was higher than the abundance of bacteriophage.Meanwhile,the abundance of bacteriophage was higher than the abundance of bacteria.The variance analysis demonstrated that the abundance of the bacteria showed significant difference and the abundance of phages didn’t reveal significantly different between sludge bulking and normal sludge at 5 % level.Correlation analyses also showed that there was significant correlation between the abundance of phages and bacteria.Meanwhile,the abundance of bacteriophages was significantly correlated with SS,TP,SV,MLSS and that of bacteria also significantly correlated with TN.In addition,wastewater treatment process had notable correlation with SVI,MLSS.(2)The study on high-throughout sequencing technology of bacteria reveals: At class,family and genus level,we could come to the conclusion that the community structure of activated sludge microbes had great difference between sludge bulking and normal sludge.The high abundance of the genus of filamentous bacterium included Candidatus Microthrix,Gordonia,Haliscomenobacte at the state of sludgebulking in May.The high abundance of the genus of bacterium included Hyphomicrobium,Pseudomonas,Thauera,Streptococcus,Corynebacterium,Methyloversatilis at the state of normal sludge in October.The PCA analysis of the activated sludge samples revealed that three sewage water samples get together respectively during the state of sludge bulking and normal sludge and the three sewage samples have significant difference during the state of sludge bulking and normal sludge.(3)The research on metagenome sequencing technology of phage shows : From the level of family,the abundance of different bacteriophages was remarkably different for the samples from the state of sludge bulking and normal sludge.The result also showed that the most abundant family was Caudovirales.The high abundance of the genus of virus included P22 likevirus,Hpunalikevirus,Lambdalikevirus,N4 likevirus,Betabaculovirus,Bcep78 likevirus at the state of sludge bulking in May.The high abundance of the genus of virus included Cytomegalovirus,Lymphocryptovirus,Polyomaviridae,Lentivirus,Deltaretrovirus,Alphapapillomavirus,T4 likevirus at the state of normal sludge in October.The community structure of three sewage samples at the state of sludge bulking in May have high similarity degree and the same result was as the samples at the state of normal sludge in October.