Isolation Of Quorum Quenching Bacteria And Its Characteristics Of Controlled Sludge Mixture

The phenomenon of quorum sensing（QS）,which is widely used in activated sludge,has been verified to participate in the regulation of group behaviors such as EPS secretion,biofilm formation and biodegradation,and has positive or negative effects in different biological wastewater treatment processes.By disturbing,destroying and degrading the structural function of AHLs,the mechanism of quorum quenching（QQ）,which regulates the concentration of AHLs,can meet the need of artificially regulating the characteristics of sludge mixture to enhance the operation of different biological wastewater treatment processes.In this study,the problem of sludge mixing characteristics controlled by quorum induction quenching was focused on.By screening new QQ strains,in situ continuous exogenous addition group induction hardening to control sludge mixture SMP,EPS,and exploring quorum quenching.The effect of the elimination on the microbial community structure succession of the activated sludge mixture provides a theoretical basis and experimental basis for the subsequent application of quorum quenching mechanism to control the biological pollution of the MBR membrane.The main findings are as follows:（1）Three new QQ strains,one QS strains were identified by directed separation,which were identified as Serratia sp.Z4,Lysinibacillus sp.z6,Serratia sp.Z7 and Klebsiella sp.Z2.The Genbank receiving numbers are MK431391,MK431392,MK431393,MK431390,respectively.Among them,the degradation rate of 44μM C8-HSL by Serratia sp.Z4 is as high as 93.7%,far exceeding the quenching effect of other known QQ strains,genetic search and HPLC-MS mass spectrometry product analysis revealed that it may have a novel unreported degradation of the C8-HSL pathway.（2）The optimal degradation system was established by single factor and response surface methodology optimization experiments:temperature31.38℃,p H 7.162,inoculum 5.037%,modified Gompertz equation fitting the degradation curve of Serratia sp.Z4 strain under different C8-HSL concentration The maximum degradation rate(₈))of the substrate increased with the increase of concentration,but the lag time（λ）and the degradation rate were negatively correlated.（3）In situ continuous exogenous addition of group induction quenching Serratia sp.Z4 strains control sludge mixture characteristics.Experimental results show that the addition of Serratia sp.Z4 bacteria can effectively reduce the actual domestic sewage treatment activated sludge mixture 8.47%～30.07%SMP concentration,1.84%～10.91%EPS concentration,and no effect on removal rate of COD,NH₄⁺-N,TN,TP.（4）16S rDNA high-throughput sequencing technology to examine the effect of QQ mechanism on the microbial community structure succession of activated sludge mixture.It was found that the in-situ continuous addition of Serratia sp.Z4 changed the microorganisms in the sludge mixture.Structural composition and succession changes,mainly in the increase of the species abundance of Proteobacteria,Cyanobacteria,and Firmicutes at the level of the gate,and specific increased in the level of Pseudomonas and Staphylococcus.At the same time,the compositional abundance of QQ bacteria is reduced.