The Microbial Characteristics Of Tea Polyphenols As Disinfectant After Ultrafiltration Process

Disinfection is an important measure to ensure the biological safety of drinking water.With the continuous improvement of drinking water quality standards in China,people's requirements for water quality continue to improve from health,safety to health.Disinfectants are also developing in the direction of non-toxic to human body,no side effects,good performance and economic applicability.Tea polyphenols,as a renewable green resource,have been widely used in the field of human health.Based on the research results of tea polyphenols used in drinking water disinfection,the disinfection effect and microbial characteristics of ultrafiltration effluent treated by tea polyphenols were studied.This paper discusses the disinfection effect of tea polyphenols in ultrafiltration effluent by static test,including the bacteriostatic test of tea polyphenols and the chemical kinetic test of tea polyphenol decay.At the same time,through the study of macrogenomics of microorganisms in the water after disinfection of tea polyphenols,the community structure,community functional characteristics and changes after disinfection were discussed,and the principle of disinfection of tea polyphenols was revealed,so as to provide a theoretical basis for better control of microbial growth of tea polyphenols as a disinfectant.The main role of tea polyphenols as a disinfectant in treating ultrafiltration water is to inhibit bacterial growth.The antibacterial effect of tea polyphenols in ultrafiltration water was explored by heterotrophic bacteria plate counting method,and the optimal dosage of tea polyphenols was determined to be 5 mg/L in combination with the redox potential measurement.After 48 h,the concentration of tea polyphenols is 2.11 mg/L,which can meet the sanitary standards for drinking water.The decay of tea polyphenols during the disinfection process conforms to the second-order kinetic equation.Both temperature and initial concentration of tea polyphenols significantly affect the decay rate of tea polyphenols.In order to ensure the disinfection effect of tea polyphenols,set 2 mg/L as the minimum concentration of tea polyphenols in 48 hours.Conditions below this value should increase the amount of tea polyphenols,such as water plants that use surface water as the water source in summer.The analysis results of microbial diversity and community structure characteristics after tea polyphenols disinfection showed that tea polyphenols disinfection would significantly reduce the microbial diversity in the water,and the structure of the flora changed to some extent.After disinfection of tea polyphenols,the relative abundance of Alphaproteobacteria and Betaproteobacteria increased significantly,while Gammaproteobacteria decreased.At the genus level,the sterilized bacteria of tea polyphenols are Sphingomonadaceae(46.85 %),Oxalobacteraceae(22.01 %),Burkholderiaceae(11.10 %),Pseudomonadaceae(7.82 %)and Methylophilaceae(2.85%).And it has obvious inhibitory effect on three chlorine-resistant potential pathogens.The microorganisms at risk were detected and analyzed by the method of indicating microorganisms in the national standard and the method of directly detecting pathogens by metagenomics.The results showed that the relevant indicator microorganisms in the national standard were not detected.Metagenome direct detection of pathogenic bacteria further revealed that after tea polyphenols were disinfected,the diversity and abundance of detectable virulence factors decreased.This may be related to the selectivity of tea polyphenol disinfection and the disinfection strategy to inhibit the growth of microorganisms.However,the relative abundance of some pathogenic bacteria's virulence factors has slightly increased,which may be caused by the horizontal transfer of pathogenic bacteria carrying virulence factors in order to adapt to the environment and enhance their competitiveness.Through hierarchical cluster analysis,it was found that the disinfection of tea polyphenols had a significant inhibitory effect on the functional modules of microbial metabolism,environmental information processing,and genetic information processing.In particular,it has a greater impact on enzymes,energy metabolism,cofactor vitamin metabolism,amino acid metabolism,and sugar chain biosynthesis and metabolism.Tea polyphenols significantly reduce the membrane transport function of microorganisms and the ability to translate and replicate genetic information,which greatly reduces the ability of microorganisms to process environmental information and genetic information.Tea polyphenols also reduce the relative abundance of functional genes that can generate and die cells to slow down the cell cycle process.The above tea polyphenols can inhibit the growth and reproduction of microorganisms by selecting the microorganisms in the water and changing the characteristics of the microbial community,so as to achieve the bacteriostatic effect.At the same time,tea polyphenols can reduce the microbial abundance of gene functions related to human diseases by inhibiting the growth of waterborne pathogens.After sterilization of tea polyphenols,the relative abundance of various nucleotide and amino acid metabolism modules of microorganisms was significantly reduced.The glutamate metabolism is the most reduced metabolic process after tea polyphenols act on microorganisms,which is related to the obvious inhibition of the tricarboxylic acid cycle(TCA).Tea polyphenols are used for water disinfection.By inhibiting the tricarboxylic acid cycle(TCA)involved in cell energy metabolism,various metabolic processes such as glutamate metabolism of microorganisms in water are reduced,so that the growth of microorganisms in water appears to inhibit growth,so as to achieve disinfection.At the same time,tea polyphenols have a greater inhibitory effect on various nucleotide metabolism processes of microorganisms or related processes,including purine metabolism,pyrimidine metabolism,lysine metabolism,etc.,which will affect the synthesis of essential substances for cell growth and reproduction.While,it will produce transcription repression,attenuation mechanism,feedforward activation and feedback inhibition.The relative abundance of genes related to microbial stress response is significantly increased,which is related to the massive production of glutathione.Disinfection of tea polyphenols can cause stress in microorganisms in water.Mainly through the production of glutathione synthetase and glutathione reductase to improve glutathione metabolic function,the formation of microbial self-protection mechanism.