Study On The Response Of Short-cut Nitrification And Denitrification Microbial Community To Salinity And Tetracycline Stress Based On Metagenomics

Nowadays,with the rapid development of economy and society and the high-quality production and life of human beings,the hidden dangers of water environment safety and the increasing types of pollutants in water,the problem of sudden changes in water quality has gradually become an urgent problem to be solved in the field of water treatment.In this experiment,the short-cut nitrification and denitrification process,which is one of the current new biological denitrification technologies,has outstanding advantages compared with traditional processes.In addition,salinity and antibiotics can also promote the operation of short-cut nitrification and denitrification processes to a certain extent.Therefore,this paper is mainly based on metagenomics to study the response of short-cut nitrifying and denitrifying microbial communities to salinity and tetracycline concentration stress.The SBR reactor was used in this experiment,under the premise of 0.5～1.0 mg/L DO,p H=7.5～8.0,and 30℃,the initial operation of the process was completed after 30cycles.After the process operation effect and denitrification effect are stable,Na Cl is added to the SBR reactor according to the gradient.After each addition of Na Cl is completed,the removal rate of COD,NH3-N and TN and the accumulation rate of NO2~--N are measured.Through careful comparison,10.8 g/L is the optimal salinity,and the four indicators tested all recovered quickly or even higher than the previous level.It can be seen that the inhibitory effect of Na Cl on microbial activity is not irreversible.The dosage of Na Cl can be increased to the minimum limit of microbial activity,and then the microbial activity can be gradually recovered by reducing the dosage of Na Cl,thereby improving short-cut nitrification.Salt tolerance and denitrification efficiency of microorganisms in denitrification systems.Tetracycline was added to the restabilized SBR reactor,and the removal rate of COD,NH3-N and TN and the accumulation rate of NO2~--N were measured.The removal rate of TN was most affected by tetracycline,and the accumulation rate of NO2~--N was the least affected by tetracycline and remained basically stable.This shows that due to the self-protection mechanism of microorganisms,the content of antibiotics in sludge is getting higher and higher.The reason may be that there is only an accumulation process without metabolic process.Therefore,it is a process of continuous inhibition of microbial activity and the inhibition effect is getting better and better.Metagenome sequencing using DNA extraction followed by retrieval from genomic databases to study the distribution of bacteria,compare abundances through sequences,construct graphs to compare associations,and use metagenomics methods to study their microbes in different samples community distribution.The analysis results show that almost every process contains dominant bacteria such as Actinobacteria,Proteobacteria and Bacteroidetes,which have high sequence similarity.Short-cut nitrification and denitrification can promote the process of nitrification,and Proteobacteria may also play an important role in wastewater treatment.The metagenomic sequencing method was used to study whether salinity and tetracycline would have an impact on the short-cut nitrification and denitrification process mentioned in this paper.and change.When studying the microbial community distribution of salt-containing antibiotic wastewater in the process of short-cut nitrification and denitrification,it is found that salts and antibiotics can be appropriately put into the growth environment of microorganisms,thereby improving the efficiency of short-cut nitrification and denitrification and the accumulation rate of NO2~--N,so that the process can have a very ideal treatment effect under extremely harsh conditions.Due to the increase of salinity,the abundance of AOB genus also increased,with the largest proportion at 10.8 g/L salinity.It can be found by observing the species clustering heat map and PCo A that the changes in salinity and tetracycline concentration also increased.Affecting the dynamic change law of microbial community,the samples all have obvious changes and successions with salinity and tetracycline concentration,that is,the samples with salinity of 10.8 g/L and tetracycline concentration of 10 mg/L have obvious clustering phenomenon.Therefore,by studying the community distribution of microorganisms,we can gradually increase the salinity within the range of microbial salt tolerance,so as to reduce the adverse effect of tetracycline on microorganisms,and then reduce the salinity to improve the treatment effect of wastewater and improve the salt tolerance of microorganisms in the process.