Survey of Tetracyclines, Sulfonamides, Sulfamethazine, and Quinolones in UHT Milk in China Market

This study surveyed 180 samples of ultra high temperature （UHT） milk of four top Chinese dairy brands collected in the 25 cities in China in June 2011, and assessed their contamination with antibiotics, using the ELISA method. The percentages of tetracyclines, sulfonamides, sulfamethazine, and quinolones detected in the samples were 0, 16.7, 40.6, and 100%, respectively. The maximum concentrations of the tetracyclines, sulfonamides, sulfamethazine and quinolones in UHT milk samples were 〈1.5, 26.2, 22.6, and 58.8 μg kg-1, respectively. None of the samples exceeded the maximum residue levels （MRLs） for these four veterinary drugs, according to the regulations set by China, the European Union （EU） and the Codex Alimentarius Commission （CAC）.

Bioaccumulation and Biodegradation of Sulfamethazine in Chlorella pyrenoidosa

Intensive use of sulfamethazine(SM_2) in aquaculture has resulted in some detrimental effects to non-targeted organisms. In order to assess its potential ecological risk, it is crucial to have a good understanding on the bioaccumulation and biodegradation of SM_2 in Chlorella pyrenoidosa. The microalgae were treated with 2, 4, and 8 mg L^(-1) of sulfamethazine for 13 days, respectively, showing that the inhibition effects of sulfamethazine on the growth of Chlorella pyrenoidosa increased progressively as the concentrations of sulfamethazine increasing from 2 to 8 mg L^(-1). The peak concentrations of sulfamethazine accumulated in C. pyrenoidosa were 0.225, 0.325, and 0.596 ng per mg FW on day 13 for three treatment groups, respectively, showing a great ability to deplete sulfamethazine from the culture media. On day 13, the percentages of biotic degradation were 48.45%, 60.21% and 69.93%, respectively. The EC_(50) of 10.05 mg L^(-1) was derived which showed no significant risk for C. pyrenoidosa with a calculated risk quotient < 1. The activities of superoxide dismutase and catalase increased progressively in response to sulfamethazine and showed a positive correlation to the treatment concentrations. The highest superoxide dismutase activity was achieved at the concentration of 8 mg L^(-1) after 2 d of exposure, which was 1.89 folds higher than that of the control. The activity of catalase has a similar pattern to that of superoxide dismutase with the maximum activity achieved at day 2, which was 3.11 folds higher compared to that of the control. In contrast to superoxide dismutase and catalase, the maximum glutathione S-transferase activity was observed at day 6, showing 2.2 folds higher than that of the control.

Preparation and Characteristic Identification of Monoclonal Antibody Against Sulfamethazine

Two artificial antigens were synthesized successfully by diazotizing method, sulfamethazine（SM2）-human serum albumin （HSA） was used for the immunogen, and SM2-ovalbumin（OVA） was used for the coating antigen. The coupled reaction was successful by confirmation of the ultraviolet scanning spectrometer, and the conjugation ratio of SM2 with HSA and OVA was 9：1 and 15：1, respectively. Using cell-fusion and limiting dilution method to reclone 5 times to get 3 hybridoma strains, which could stably secret monoclonal antibody （Mab）, named CBT, BC4 and BB12. The subtype of BC4 Mab was IgG1 and chain, the molecular weight was 162 ku, the numbers of chromosomal were about 90, the affinity constant was 6.1 × 10^12 M^-1. No cross reactivity was seen between the Mab and the other 4 sulfonamides, as well as the 2 carries proteins. The Mab antibody had excellent stability.

Removal of Sulfamethazine by Corn Biochars from Aqueous Solution:Sorption Mechanisms and Efficiency

Sorption mechanisms of sulfamethazine(SMT)in different pH solutions are complicated.It has not been sufficiently investigated to enhance removal of SMT from alkalescent aqueous solution.In this study,sorption isotherms and kinetics of SMT by corn biochars pyrolyzed at 300℃ and 600℃(300C,600C)under diverse pH conditions were compared.In order to improve the sorption efficiency of SMT from alkalescent aqueous solution,the biochar 300C was modified by acid or base.Different mathematic models were used to describe sorption driving force and sorption process.Results showed that the biochar 300C possessed more amorphous organic carbon and polar functional groups,which led to a higher sorption capacity than biochar 600C.The sorption rate of biochar 300C was greater than 600C under diverse pH as the physisorption of 300C outweighed 600C.The SMT presented stronger hydrophobicity at pH 5 and higher electrostatic repulsion at pH 1 or 8,which resulted in a higher combining capacity of SMT with both biochars at pH 5 than other pH values.In addition,the acid modified biochar had better removal effect on SMT than alkali at pH solution around 8.The research provides a theoretical basis for the removal of SMT from alkalescent aqueous solution.

Imaging Array SPR Biosensor Immunoassays for Sulfamethoxazole and Sulfamethazine

A homemade array surface plasmon resonance （SPR）-based imaging biosensor was used to develop sensitive and fast immunoassays to determine sulfamethoxazole （SMOZ） and sulfamethazine （SMT） in buffer. Two conjugations of sulfonamide-bovine serum albumin （BSA） were separately immobilized on two different rows of the array chip with one row as reference. The immobilization was carried out in the instrument to monitor the quantity of the conjugations immobilized. The antibody mixed with the sulfonamide in the buffer was injected over the surface of the chip to get a relative response which was inversely proportional to the concentration of the sulfonamide in the PBS buffer. Two calibration curves were constructed and the limit of detection for sufamethoxazole in buffer was 3.5 ng/mL and for sulfamethazine 0.6 ng/mL. The stability and specificity of the antibody were also studied. The monoclonal antibody did not bind with BSA.

Study on ELISA for detection of sulfamethazine residues

In this study, various factors of ELISA for detection of sulfamethazine residues were explored, the coating antigen was diluted to 1：400, the best coating condition was at 4℃ overnight, the working concentration of HRP-IgG enzyme conjugate was 1 ： 7 000. The pre-incubation time and incubation time was 30 min and 120 min, respectively, the substrate solution working time was 20 min. Two moL · L^-1 H2SO4 was used to stop the reaction and checked. A standard curve of direct competitive ELISA had been established to detect the sulfamethazine residues in milk. The detection limit of this method was 1.97 ng · mL^-1. The mean concentration of sulfamethazine required to inhibit 30% antibody was 7.1 ng · mL^-1. The linear range of the detection was 5-200 ng · mL^-1. The recovery ratio was between 73.20% and 91.16%. The CV% of within array and between arrays was less than 10%.

Boron promoted Fe^(3+)/peracetic acid process for sulfamethazine degradation:Efficiency,role of boron,and identification of the reactive species

In this work,boron(B)was used to promote Fe^(3+)/peracetic acid(Fe^(3+)/PAA)for the degradation of sulfamethazine(SMT).An SMT degradation efficiency of 9.1%was observed in the Fe^(3+)/PAA system over 60 min,which was significantly increased to 99.3%in the B/Fe^(3+)/PAA system over 10 min.The B/Fe^(3+)/PAA process also exhibited superior resistance to natural substances,excellent adaptability to different harmful substances,and good removal of antibiotics in natural fresh water samples.The mechanism of action of boron for Fe^(3+)reduction was determined using scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared(FT-IR)spectroscopy,density functional theory(DFT)calculations,and electrochemical tests.The dominant role of^(·)OH was confirmed using quenching experiments,electron spin resonance(EPR)spectroscopy,and quantitative tests.Organic radicals(R-O^(·))and Fe(IV)also significantly contribute to the removal of SMT.DFT calculations on the reaction between Fe^(2+)and the PAA were conducted to further determine the contribution from ^(·)OH,R-O^(·),and Fe(IV)from the perspective of thermodynamics and the reaction pathways.Different boron dosages,Fe^(3+)dosages,and initial pH values were also investigated in the B/Fe^(3+)/PAA system to study their effect of SMT removal and the production of the reactive species.Fe(IV)production determined the k_(R-O·+Fe(IV))value suggesting that Fe(IV)may play a more important role than R-O^(·).A comparison of the results with other processes has also proved that the procedure described in this study(B/Fe^(3+)/PAA)is an effective method for the degradation of antibiotics.

Assembling S-scheme heterojunction between basic bismuth nitrate and bismuth tungstate with promoting charges’separation for accelerated photocatalytic sulfamethazine degradation

The S-scheme heterojunction has garnered increasing attention due to its remarkable oxidation capacity and efficient separation of photogenerated carriers.In this study,a one-pot glycerol-assisted hydrothermal process was utilized to successfully synthesize S-scheme heterojunction photocatalysts comprising basic bismuth nitrate(BBN)and bismuth tungstate(BWO).Interestingly,the BBN/BWO heterogeneous photo-catalysts exhibited the highest photocatalytic properties.The optimized product achieved the degradation of sulfamethazine(SMZ)within 1 h,with a kinetic constant(k)value of 0.05818 min^(−1).The degradation process was influenced significantly by·O^(2)−and h^(+)species.To determine the degradation pathway of SMZ in the presence of BBN/BWO-0.6,liquid chromatography-mass spectrometry(LC-MS)analysis was performed,which revealed a decrease in the toxicity of intermediates and products.The enhanced pho-tocatalytic activity can be attributed to the internal electric field(IEF)of the S-scheme heterojunction between BBN and BWO,effectively promoting the separation of photogenerated carriers.This research presents a viable approach for developing S-scheme heterojunctions in SMZ photodegradation and other environmental applications.

Effect of sulfamethazine on the horizontal transfer of plasmid-mediated antibiotic resistance genes and its mechanism of action

As a new type of environmental pollutant,antibiotic resistance genes(ARGs)pose a huge challenge to global health.Horizontal gene transfer(HGT)represents an important route for the spread of ARGs.The widespread use of sulfamethazine(SM2)as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment,thereby increasing the spread of ARGs.Therefore,we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli(E.coli)HB101 to E.coli NK5449 as well as its mechanism of action.The results showed that compared with the control group,SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs,but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L.The transfer frequency at 200 mg/L was 3.04×10^(−5),which was 1.34-fold of the control group.The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes(trbBP,trfAP)and oxidative stress genes,inhibition of the mRNA expression of vertical transfer genes,up regulation of the outer membrane protein genes(ompC,ompA),promotion of the formation of cell pores,and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4.The results of this study provide theoretical support for studying the spread of ARGs in the environment.

Removal of sulfamethazine antibiotics by aerobic sludge and an isolated Achromobacter sp.S-3

Removal characteristics of sulfamethazine （SMZ） by sludge and a bacterial strain using an aerobic sequence batch reactor （ASBR） were studied. Operating conditions were optimized by varying the reaction time and sludge retention time （SRT）. AnAchromobacter sp. （S-3） with the ability to remove SMZ was isolated from the ASBR. The effects of different operating parameters （pH and temperature） on the biodegradation of SMZ by S-3 were determined. The results indicate that, between 0.5 and 4 hr, reaction time of the ASBR had a significant effect on the SMZ removal efficiency in the system. The SMZ removal efficiency also increased from 45% to 80% when SRT was prolonged from 5 to 25 days, although longer SRT had no impact on SMZ removal. The SMZ adsorption rate decreased with increasing temperature, which fitted Freundiich isotherm well. The removal of SMZ in the ASBR was due to the combined effects of adsorption and degradation, and degradation played a leading role.

Transformation of sulfamethazine during the chlorination disinfection process: Transformation,kinetics, and toxicology assessment

Various disinfection byproducts(DBPs) form during the process of chlorination disinfection,posing potential threats to drinking water safety and human health. Sulfamethazine(SMT),the most commonly used and frequently detected veterinary antibiotic, was investigated in detail with regard to its transformation and kinetics in reactions with free available chlorine(FAC). Using liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry, several DBPs were identified based on different confidence levels, and a variety of reaction types, including desulfonation, S–N cleavage, hydroxylation, and chlorine substitution, were proposed. The kinetic experiments indicated that the reaction rate was FAC-and pH-dependent, and SMT exhibits low reactivity toward FAC in alkaline conditions. The DBPs exhibited a much higher acute toxicity than SMT, as estimated by quantitative structure activity relationship models. More importantly, we observed that the FAC-treated SMT reaction solution might increase the genotoxic potential due to the generation of DBPs. This investigation provides substantial new details related to the transformation of SMT in the chlorination disinfection process.

A stable and efficient La-doped MIL-53(Al)/ZnO photocatalyst for sulfamethazine degradation

Photocatalytic technology can solve various environmental pollution problems,especially antibiotic pollution.A novel La-doped MIL-53(Al)/ZnO composite material was successfully synthesized by a combination of hydrothermal method and calcination,showing high photocatalytic degradation percent of sulfamethazine(SMT).The 2 mol%La MIL-53(Al)/ZnO photocatalyst shows the highest degradation efficiency toward SMT(92%)within 120 min,which is 4.1 times higher than pure ZnO(increased from 18%to 92%).In addition,the degradation analysis of SMT by high performance liquid chromatography proves that the products are CO_(2) and H_(2)O.The improved photocatalytic activity is mostly caused by the following factors.(1)Doping La ions can decrease the band gap of ZnO,enhance light response,and effectively enhance the separation rate of photo-generated holes and electrons.(2)MIL-53(Al)can adsorb SMT and promote the separation of electron.This work shows that the synthesized La-doped MIL-53(Al)/ZnO photocatalyst is expected to be used as a green and effective method for treatment of environment water pollution.

Biofiltration of the antibacterial drug sulfamethazine by the species Chenopodium quinoa and its further biodegradation through anaerobic digestion

The biofiltering capacity, distribution patterns and degradation of the antimicrobial sulfamethazine(SMT) by halophyte Chenopodium quinoa under hydroponic conditions and its further biodegradation through anaerobic digestion were evaluated. C. quinoa was cultivated for a complete life cycle under different concentrations of SMT(0, 2 and 5 mg/L) and sodium chloride(0 and 15 g/L). C. quinoa is able to uptake and partially degrade SMT. The higher the SMT concentration in the culture medium, the higher the SMT content in the plant tissue. SMT has different distribution patterns within the plant organs, and no SMT is found in the seeds.Dry crop residues containing SMT have a great potential to produce methane through anaerobic digestion and, in addition, SMT is further biodegraded. The highest specific methane yields are obtained using crop residues of the plants cultivated in the presence of salt and SMT with concentrations between 0 and 2 mg/L.

The performance and degradation mechanism of sulfamethazine from wastewater using IFAS-MBR

Sulfamethazine(SMZ) is an important sulfonamide antibiotic.Although the concentration in the environment is small,it is harmful.The drug residues can be transferred,transformed or accumulated,affecting the growth of animals and plants.In this study,the integrated fixed-film activated sludge membrane bioreactor(IFAS-MB R) were constructed to investigate the performance and degradation mechanism of SMZ.The addition of SMZ had a significant impact on the removal of the chemical oxygen demand(COD) and ammonia nitrogen(NH_4^+-N).The optimal operating conditions were hydraulic retention time(HRT) at 10 h and solid retention time(SRT) at 80 d,respectively.On this basis,the effects of different SMZ concentrations on nutrient removal,degradation,and sludge characteristics were compared.The removal efficiency of SMZ increased with the increase of SMZ concentration.The maximum removal rate was as high as 87%.The SMZ dosage also had an obvious effect on sludge characteristics.As the SMZ concentration increased,the extracellular polymer substances(EPS) concentration and the membrane resistance both decreased,which were beneficial for the reduction of membrane fouling.Finally,seven kinds of SMZ biodegradation intermediates were identified,and the possible degradation pathways were speculated.The microbial community results showed that the microbial diversity and richness in the reactor decreased after adding SMZ to the influent.The relative abundance of Bacteroidetes,Actinobacteria,Saccharibacteria and Nitro spirae increased at the phylum level.Sphingobacteria and Betaproteobacteria became dominant species at the class level.The relative abundance of norankp-Saccharibacteria and Nitrospirae increased significantly,and norank-p-Saccharibacteria may be the dominant bacteria for SMZ degradation.

Degradation of sulfonamides and formation of trihalomethanes by chlorination after pre-oxidation with Fe(Ⅵ)

Sulfonamides are used in human therapy, animal husbandry and agriculture but are not easily biodegradable, and are often detected in surface water. Sulfamethazine （SMZ） and sulfadiazine （SDZ） are two widely used sulfonamide antibiotics that are used heavily in agriculture. In this study, they were degraded in an aqueous system by chlorination after pre-oxidation with ferrate（VI） （FeVIO2-, Fe（VI））, an environmentally friendly oxidation technique that has been shown to be effective in degrading various organics. The kinetics of the degradation were determined as a function of Fe（VI） （0-1.5 mg/L）, free chlorine （0-1.8 mg/L） and temperature （15- 35℃）. According to the experimental results, SMZ chlorination followed second-order kinetics with increasing Fe（VI） dosage, and the effect of the initial free chlorine concentration on the reaction kinetics with pre-oxidation by Fe（VI） fitted a pseudo-first order model. The rate constants of SDZ and SMZ chlorination at different temperatures were related to the Arrhenius equation. Fe（VI） could reduce the levels of THMs formed and the toxicity of the sulfonamide degradation systems with Fe（VI） doses of 0.5-1.5 mg/L, which provides a reference for ensuring water quality in drinking water systems.