Effect Of Sulfanilamide Antibiotics On Anaerobic Fermentation Of Swine Manure And The Biodegradation Mechanism Of Sulfanilamide

As a kind of common antibiotics,sulfanilamide(SAs)are often used in livestock and poultry breeding industry,and can be discharged into fecal sewage in the form of parent compounds and metabolites,which have an impact on anaerobic fermentation of fecal sewage.In this study,the effects of 4 kinds of common animal SAs(sulfaquinoxaline/SQX,sulfamethoxazole/SMX,sulfamethoxine/SMD,sulfathiazole/STZ)on the anaerobic fermentation performance of swine manure were investigated,the kinetic characteristics of the anaerobic biodegradation of SAs were discussed,and the degradation mechanism of SAs was revealed.It can be obtained from the research that biogas production and the degradation rate of organic matter were decreased with the increase of SAs concentration.SAs,especially SQX and STZ,can cause VFAs accumulation and pH value reduction.According to the correlation analysis of microbial community and environmental factors,Ignatzschineria,Tepidimicrobium and Fastidiosipila could promote the methane production process,while Clostridium III,Anaerococcus and Proteiniphelum were affected by SAs,which could inhibit the methane production process.The dissolved organic matter(DOM)in biogas slurry was analyzed by three-dimensional fluorescence analysis.DOM in biogas slurry was mainly from land,which was related to the metabolic secretion of microorganism.With the increase of SAs concentration,the concentration of metabolic secretion of microorganism decreased.Four characteristic components were obtained by parallel factor analysis,among which tryptophan-like substance was positively correlated with the abundance of Firmicutes and Proteobacteria;Proteobacteria were negatively correlated with degradable protein-like substance.The degradable protein-like substance was the precursor of methane.The degradation rate of degradable protein-like substance was reduced by the addition of SAs,which led to the decrease of methane production.The anaerobic fermentation group can effectively degrade SAs,and the degradation rate of SAs was related to the type,concentration and organic matter concentration.The abundance and diversity of anaerobic microbial community were affected by the type of SAs and the concentration of organic matter in the environment.Typical correlation analysis showed that the degradation rate of SAs was positively correlated with the abundance of Proteobacteria and Bacteroidetes,and negatively correlated with the abundance of Firmicutes.The degradation rate of SAs in inorganic salt medium and fermentation substrate supernatant was related to the abundance of specific microbial species.The products of anaerobic degradation of SAs were analyzed by liquid chromatography-tandem mass spectrometry.The basic functional group of SAs-aminobenzenesulfonamide was decomposed into NH4+,SO42-and mineral acid by the fracture of C-N bond S-N,S-C and C-N bond,as well as ring opening reaction.The degradation paths of quinoxaline,methoxazole,pyrimidine and thiazole rings were different in SAs.In the process of SAs biodegradation,some substitution reactions might take place at the N1 and N4 amino sites,including acetylation,hydroxylation,glucuronization and sulfonamide derivative substitution.This study provided the theoretical basis for anaerobic fermentation of swine manure containing SAs,and provided a reference for the study of the mechanism of biodegradation of SAs.