Investigating The Potentiality Of Indigenous Bacteria Strain And Algae Co-culture To Remove Tetracycline From Synthetic Wastewater

At present,tetracycline has been detected in a variety of environmental media,especially high concentrations of tetracycline are frequently detected in aquaculture wastewater.Tetracycline that remains in the environment,even in small concentrations,can have a significant negative impact on the environment.Although a large number of reports of non-microbial degradation of antibiotics have been reported,they all have certain limitations due to the problems of secondary pollution and high cost.Therefore,it is particularly important to find an efficient,green,economical,and sustainable method to remove tetracycline from water.In this study,a microalgae-bacteria co-cultivation system was proposed to remove tetracycline from water,which can provide a method reference for the practical application of antibiotic removal.In this study,indigenous degrading-bacteria that can efficiently degrade tetracycline was screened from pig manure,and its degradation ability was stabilized after domestication,and the biodegradation characteristics of the degrading bacteria were explored.The use of sole microalgae is limited by slow growth rates and low resistance to pollutants.Through nutrient exchange,signal transduction and gene transfer between bacteria and microalgae,antibiotics undergo hydroxylation,acetylation,nitration,oxidation,and substitution,and tetracycline was transformed or mineralized by the non-specific enzyme system of the co-culture themselves.Investigating the removal of tetracycline from water by co-culture.The screened high-efficiency tetracycline-degrading bacteria were identified as Klebsiella pneumoniae DUT-XJR-t-1.2 after 16S r RNA homology analysis.Biological experiments were used to study the biodegradation characteristics of the degrading bacteria by single-factor analysis,from the initial tetracycline concentration,temperature,p H,inoculum amount,and other factors.The optimal biodegradation conditions of tetracycline for this strain were that the initial tetracycline concentration was 100 mg L^-1,the temperature was 25°C,and the p H of the solution was 7.The amount of inoculum had no significant effect on the degradation of tetracycline,and temperature and p H were the key factors for the degradation of tetracycline.At the same time,toxicity experiments were performed on two microalgae（Desmodesmus sp.and Chlorella）,and it was determined that tetracycline was less toxic to Desmodesmus sp.And it construction of microalgae-bacteria co-culture system together with degrading bacteria.Desmodesmus sp.:Klebsiella pneumoniae（DUT-XJR-t-1.2）co-culture was optimized to remove tetracycline from synthetic wastewater.To enhance the tetracycline removal performance,the effect of microalgae-bacterial co-culture ratio,maximum tetracycline concentration,effective inoculum amount,growth temperature,and p H were studied.The optimized ratio 1:2 of Desmodesmus sp.:K.pneumoniae showed the optimal removal percentage at the temperature of 25℃,p H 7,and 10%inoculum amount;and the removal of tetracycline was recorded as 95%.Moreover,this study explored the Desmodesmus sp.:K.pneumoniae（1:2）symbiotic tetracycline removal of nutrients to determine the COD,NH4⁺,and PO4^3-removal percentages as well as algal biomass change.According to the results of this study,Desmodesmus sp.:K.pneumoniae co-culture could be a green option for bio-removal of tetracycline from wastewater.