Addition Of Oxytetracycline Research Articles

Insights into the response of anammox process to oxytetracycline: Impacts of static magnetic field

The long-term effects of oxytetracycline (OTC) with a high concentration on the anaerobic ammonium oxidation (Anammox) process were evaluated, and the role of static magnetic field (SMF) was further explored. The stress of OTC at 50 mg/L had little effect on the nitrogen removal of anammox process at the first 16 days. With the continuous addition of OTC and the increase of nitrogen loading, the OTC inhibited the nitrogen removal and anammox activity severely. During the 32 days of recovery period without OTC addition, the nitrogen removal was further deteriorated, indicating the inhibition of OTC on anammox activity was irreversible and persistent. The application of SMF alleviated the inhibition of OTC on anammox to some extent, and the specific anammox activity was enhanced by 47.1% compared to the system without SMF during the OTC stress stage. Antibiotic efflux was the major resistance mechanism in the anammox process, and tetA, tetG and rpsJ were the main functional antibiotic resistance genes. The addition of OTC weakened the metabolic interactions between the anammox bacteria and the symbiotic bacteria involved in the metabolism of cofactors and secondary metabolites, leading to the poor anammox activity. The adaptability of microbes to the OTC stress was improved by the application of SMF, which can enhance the metabolic pathways related to bacterial growth and resistance to environmental stress.

Dual-responsive carbon dots-based luminophore for ratiometric fluorescence and room-temperature phosphorescence detection of oxytetracycline

Dual-responsive probes emitting both fluorescence and phosphorescence signals are greatly advantageous to sensing. Here, we present a carbon dots-based luminophore (CDs@LP) with blue fluorescence and ultra-long yellow room-temperature phosphorescence (RTP) with lifetime of 1.33 s (that was visible to the naked eye for ∼ 13 s) for ratiometric detection of oxytetracycline (OTC). The CDs@LP was prepared by molten salt method through one-step treatment of 2, 6-diaminopyridine, KNO3, MgCl2, and KH2PO4. Upon the addition of OTC into CDs@LP aqueous solution, the fluorescence at 386 nm and RTP at 538 nm of CDs@LP were quenched as a result of the inner filter effect (IEF), while the fluorescence at 522 nm of OTC steadily enhanced due to the molecular restriction through the formation of OTC-Mg2+ complexes. Both fluorescence and RTP signals have excellent linear relationships with OTC concentration. The CDs@LP had a low detection limit of 3.2 nM (fluorescence) and 0.27 μM (phosphorescence), which also exhibited satisfactory selectivity and anti-interference performance towards other antibiotics. Moreover, the CDs@LP was successfully loaded on a filter paper and used for OTC sensing. Thus, it is a promising tool for OTC detection and can act as a foundation for producing dual-signal sensing tools.

Induced development of oxytetracycline tolerance in bacterial communities from soil amended with well-aged cow manure.

The use of animal manure as organic fertilizer is a common agricultural practice that can improve soil health and crop yield. However, antibiotics and their metabolites are often present in animal manure and, hence, in manure-amended soil. The aim of this study was to assess the induced development of oxytetracycline (OTC) tolerance in soil bacterial communities as a result of the addition of OTC to soil amended with well-aged cow manure. To this purpose, soil amended with well-aged cow manure was repeatedly - three times - spiked with different OTC concentrations (0, 2, 20, 60, 150, and 500 mg OTC kg-1 dry weight soil, each time) according to a pollution-induced community tolerance (PICT) assay. The PICT detection phase was conducted in Biolog EcoPlatesTM in the presence of the following OTC concentration gradient in the wells: 0, 5, 20, 40, 60, and 100 mg L-1. For all treatments, the application of OTC in the PICT selection phase resulted in lower values of bacterial metabolic activity (i.e., lower values of average well color development) in the PICT detection phase. A significant increase in OTC tolerance was observed in soil bacterial communities that had been exposed three times to ≥ 20 mg OTC kg-1 DW soil during the PICT selection phase. In general, higher levels of OTC exposure during the PICT selection phase resulted in bacterial tolerance to higher OTC concentrations during the PICT detection phase, pointing to a dose-dependent induced tolerance. It is important to (i) rationalize the amount of antibiotics administered to livestock, and (ii) treat properly the antibiotic-containing manure before its application to agricultural soil as fertilizer.

Ratiometric Fluorescence Probe Based on Deep-Red Emissive CdTe Quantum Dots and Eu3+ Hybrid for Oxytetracycline Detection

Oxytetracycline (OTC) is an environmental pollutant caused by the abuse of antibiotics, and its content in water is closely related to human health. Therefore, the development of a simple, rapid, and accurate method to detect OTC has become desirable. In this work, a ratiometric fluorescence probe based on deep red emissive CdTe quantum dots (QDs) modified by mercaptopropionic acid and Eu3+ is developed to accurately and rapidly detect OTC in water. After the addition of OTC, the photoluminescence intensity of CdTe QDs at 698 nm remains almost unchanged, while the peak at 617 nm intensifies within 40 s due to the coordination of Eu3+ with OTC. An excellent linear relationship is present between the photoluminescence intensity ratio of I617/I698 and the concentration of OTC. The limit of detection of the probe towards OCT is 5.4 nM. In addition, the probe shows good selectivity and anti-interference ability for OTC in the presence of other antibiotics, including other antibiotics, ions, and amino acids. The probe has been successfully applied to detect OTC in actual samples, demonstrating its potential for environmental application.

A Highly Sensitive and Selective Nano-Fluorescent Probe for Ratiometric and Visual Detection of Oxytetracycline Benefiting from Dual Roles of Nitrogen-Doped Carbon Dots

The specific detection of oxytetracycline (OTC) residues is significant for food safety and environmental monitoring. However, rapid specific determination of OTC from various tetracyclines is still challenging due to their similar chemical structures. Here, nitrogen-doped carbon dots (NCDs) with excitation and pH-dependent optical properties and a high-fluorescence quantum yield were successfully synthesized, which were directly employed to fabricate a dual-response fluorescence probe by self-assembly with Eu3+ (NCDs/Eu3+) for the ratiometric determination of OTC. The addition of OTC into the probe greatly enhances the characteristic emission of Eu3+ due to the "antenna effect", and the incorporation of NCDs into the probe further improves the Eu3+ fluorescence by remarkably weakening the quenching effect caused by H2O molecules and efficiently shortening the distance of energy transfer from OTC to Eu3+. Meanwhile, the fluorescence of NCDs apparently decreases due to aggregation-caused quenching. The results demonstrate that a ratiometric detection of OTC (0.1-25 µM) with a detection limit of 29 nM based on the double response signals is achieved. Additionally, visual semi-quantitative assay of OTC can be realized with the naked eye under a 365 nm UV lamp according to the fluorescence color change of the as-fabricated probe. This probe exhibits acceptable specificity and anti-interference for OTC assay, holding promise for the fast detection of OTC in real water and milk samples.

Effects of Oxytetracycline/Lead Pollution Alone and in the Combined Form on Antibiotic Resistance Genes, Mobile Genetic Elements, and Microbial Communities in the Soil.

The application of livestock manure is the leading cause of antibiotic and heavy metal pollution in agricultural soil. However, the effects of oxytetracycline (OTC) and lead (Pb) pollution in the single or combined form on antibiotic resistance genes (ARGs) in the soil need to be further studied. This study was planned to investigate the effects of OTC and Pb application on ARGs, mobile genetic elements (MGEs), and bacterial abundance in the soil. The relative abundance of ARGs and MGEs increased by 0.31-fold and 0.03-fold after the addition of 80 mg kg-1 Pb to the soil, and by 0.49-fold and 0.03-fold after the addition of 160 mg kg-1 Pb. In addition, under the premise of the existence of OTC, the inhibitory effect of a low concentration of Pb on ARG is stronger than that of a high concentration of Pb, resulting in a lower abundance of ARGs. The abundance of ARGs and MGEs increased by 0.11-fold and 0.17-fold after the addition of OTC (30 mg kg-1) to the soil at a Pb concentration of 80 mg kg-1 and by 0.18-fold and 0.04-fold at a Pb concentration of 160 mg kg-1. The addition of OTC and Pb in the soil also decreased the many bacterial communities such as Bacteroidetes, Proteobacteria, Acidobacteria, and Firmicutes. Redundancy analysis (RDA) showed that organic matter content and pH were positively correlated with the abundance of ARGs and MGEs. At the same time, electrical conductivity (EC) had a negative correlation with the abundance of ARGs and MGEs in the soil. Intl1 was significantly associated with tetB, sul1, tetQ, sul2, and sul3. Network analysis illustrated that Actinobacteria, Bacteroidetes, and Proteobacteria were the main host bacteria causing changes in the abundance of ARGs and MGEs, and they were also predominant phylum in the culture environment. This conclusion can provide a reference for the related research of ARGs in soil.

The Impact of Chicken Manure Biochar on Antibiotic Resistance Genes in Chicken Manure Composting

One way to increase yields in agriculture using organic alternative methods is the introduction of manure-based composts into the soil. However, the use of such composts carries a risk of soil contamination with antibiotic resistance genes (ARG) from the gut and manure of the livestock. The contamination of the composts with heavy metals or antibiotics can increase this risk, while the addition of porous materials, such as biochar, to the composts has the potential to decrease it. This study is devoted to revealing the fate of ARGs in bedding chicken manure composted with the addition of oxytetracycline (OTC), heavy metals, and chicken manure biochar. It was revealed that the additives did not affect the physicochemical parameters of the compost. The bacterial communities in different composting mixtures had similar structures and dynamics. It was revealed that the shifts of the bacterial compositions of the composting mixtures were mainly determined by the duration of the process. However, some minor differences in the OTU (operational taxonomic unit) levels were observed between the variants. The addition of biochar and metals led to 26.7% and 34.5% decreases, respectively, in the number of tet(A) gene copies, while the addition of oxytetracycline led to a 43.7% increase. The number of copies of the int1 gene increased by 45.9% after the addition of oxytetracycline. The correlation between the abundance levels of different bacterial OTU and ARG contents was estimated, and biochar’s impact on those OTUs was analyzed. It was assumed that some OTUs might be carriers of ARGs (such as Natronobacillus, Luteimonas, and Trichococcus), and their abundance in the presence of the biochar decreased due to competitive exclusion by noncarriers (such as Corynebacterium, Clostridia, and Halorhodospira). The use of biochar in composting can be considered a way to reduce the contamination of the final composts with ARGs.

Carbon Dots and Eu3+ Hybrid-Based Ratiometric Fluorescent Probe for Oxytetracycline Detection

Overuse of oxytetracycline (OTC) in livestock farming can cause environmental water pollution, risking human health. It is essential to exploit efficient, fast, and sensitive measures to sense OTC in environmental water samples. In this study, a ratiometric fluorescence probe consisted of blue-fluorescent carbon dots (CDs) and Eu3+ was constructed to detect OTC sensitively and selectively. Upon the addition of OTC, bright red fluorescence was generated due to the aggregation of Eu3+, and the intensity of blue fluorescence of CDs reduced because of the inner filter effect between OTC and CDs. Under 365 nm UV light irradiation, the increasing of OTC concentration from 0 to 10 μM resulted a transformation of probe solution fluorescence color from blue to pick. This CDs–Eu3+ hybrid probe also performed a high selectivity for OTC with minimal interference containing various antibiotics, cations, and amino acids. Importantly, the probe demonstrated a low detection limit of 9.6 nM and a satisfactory recovery efficiency for OTC detection in river and tap water.

The Effect of Exogenous Oxytetracycline on High-Temperature Anaerobic Digestion of Elements in Swine Wastewater

Tetracycline antibiotics (TCs) are a common type of antibiotic found in swine wastewater. Oxytetracycline (OTC) is a significant type of TC. This study mainly examined the influence of OTC on high-temperature anaerobic digestion by adding OTC to collections of swine wastewater at different times during the digestion process. The results showed that high-temperature anaerobic digestion was suitable for the removal of TCs, with an 87% OTC removal efficiency achieved by day 20. Additionally, OTC added from external sources was found to inhibit the chlortetracycline degradation process and affect the first-order degradation kinetic model of TCs. Complexation reactions were the main ways in which OTC affected the heavy metal content of the water. The exogenous addition of OTC was found to inhibit the activity of some digester microbial strains, reduce the proportion of dominant strains, such as MBA03, and kill certain specific strains. This performance alteration was most obvious when OTC was added in the middle of the reaction.

Characteristics of microbial community in EGSB system treating with oxytetracycline production wastewater

In order to realize the efficient and stable operation of anaerobic digestion for oxytetracycline (OTC) production wastewater which contains high concentration refractory organic matters and antibiotic residues, two laboratory-scale EGSB reactors (the experimental reactor and the control reactor) were constructed for pre-treating OTC production wastewater and the complex characteristics and connections among anaerobic fermentative bacteria, methanogens and fungi were analyzed. The experimental reactor gradually increased OTC doses of 0–200 mg/L by four phases compared with the control reactor which was fed without OTC addition during 280 days’ operation. The average COD removal efficiency of 91.44% with the average OTC removal efficiency of 27.90% was achieved at OTC concentration of 200 mg/L. The addition of OTC did not affect the preponderant methanogen type, and Methanosaeta, a strict aceticlastic methanogen genus, was dominant both in working and controlling reactors on day 280. Redundancy analysis revealed that OTC and VFAs were the main environmental factors affecting the microbial communities and molecular ecological networks analysis indicated that the key genera principally belonged to Methanosaeta, Proteobacteria and Apiotrichum. Additionally, the fungi genus Apiotrichum might be related to the degradation of complex organic contaminants in OTC production wastewater treatment system.

Microbial community dynamics during composting of animal manures contaminated with arsenic, copper, and oxytetracycline

Effects of the heavy metal copper (Cu), the metalloid arsenic (As), and the antibiotic oxytetracycline (OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight treatments were applied, four to each manure type, namely cow manure with: (1) no additives (control), (2) addition of heavy metal and metalloid, (3) addition of OTC and (4) addition of OTC with heavy metal and metalloid; and pig manure with: (5) no additives (control), (6) addition of heavy metal and metalloid, (7) addition of OTC and (8) addition of OTC with heavy metal and metalloid. After 35 days of composting, according to the alpha diversity indices, the combination treatment (OTC with heavy metal and metalloid) in pig manure was less harmful to microbial diversity than the control or heavy metal and metalloid treatments. In cow manure, the treatment with heavy metal and metalloid was the most harmful to the microbial community, followed by the combination and OTC treatments. The OTC and combination treatments had negative effects on the relative abundance of microbes in cow manure composts. The dominant phyla in both manure composts included Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The microbial diversity relative abundance transformation was dependent on the composting time. Redundancy analysis (RDA) revealed that environmental parameters had the most influence on the bacterial communities. In conclusion, the composting process is the most sustainable technology for reducing heavy metal and metalloid impacts and antibiotic contamination in cow and pig manure. The physicochemical property variations in the manures had a significant effect on the microbial community during the composting process. This study provides an improved understanding of bacterial community composition and its changes during the composting process.

Effects of oxytetracycline on plant growth, phosphorus uptake, and carboxylates in the rhizosheath of alfalfa

Residues of antibiotics such as oxytetracycline (OTC) in soil can affect microbial compositions and activities, thus affecting soil P availability, and consequently plant P uptake and growth. A pot experiment was performed to grow alfalfa in a loess soil with different doses of P (0, 25, 50, and 100 mg kg−1) and OTC (0, 25, 50, and 100 mg kg−1). Plant dry mass, shoot and root P concentrations, bulk soil and rhizosheath pH, rhizosheath carboxylates, and bulk soil alkaline phosphatase activity were determined. Shoot dry mass and root dry mass increased with increasing P dose, while shoot dry mass decreased with increasing OTC dose, especially at lower P doses (0 and 25 mg kg−1). Addition of OTC slightly reduced P concentrations in shoots and roots, but did not reduce plant P content consistently. Increasing OTC dose significantly reduced bulk soil alkaline phosphatase activity at 0P and strongly reduced rhizosheath tartrate amount at all P doses. The effects of OTC on plant growth and P uptake depended on both OTC and P doses in soil. High OTC dose had negative effects on shoot P uptake and growth, especially at lower P doses, while it had a positive effect on root growth at higher P doses.

Dynamics of denitrification performance and denitrifying community under high-dose acute oxytetracycline exposure and various biorecovery strategies in polycaprolactone-supported solid-phase denitrification

Solid-phase denitrification (SPD) is a promising technology for nitrate-rich water purification. This study aimed to examine the variation in denitrification performance and denitrifying community under high-dose acute oxytetracycline (OTC) exposure and various biorecovery strategies. The denitrification performance was impaired significantly after one-day OTC shock at 50 mg L−1 in a continuous-flow SPD system supported by a polycaprolactone (PCL) carrier but could rapidly recover without the addition of OTC. When 50 mg L−1 OTC stress was applied for a longer time in the batch tests, a natural recovery period of more than 20 days was required to reach more than 95% nitrate reduction. Under the same conditions, the addition of both mature biofilm-attached PCL carrier and fresh biofilm-free PCL carrier significantly shortened the recovery time for efficient nitrate reduction, mainly due to the increase in organic availability from the PCL carriers. However, the composition of the microbial community notably changed due to the effects of OTC according to high-throughput sequencing and metagenomic analysis. Genes encoding NAR and NIR were much more sensitive than those encoding NOR and NOS to OTC shock. Tetracycline resistance gene (TRG) enrichment was 15.86% higher in the biofilm that experienced short-term OTC shock than in the control biofilm in the continuous-flow SPD system.

Oxytetracycline stress reconstruct the core microbial community related to nitrogen transformation during composting

This study investigated oxytetracycline (OTC) effects on nitrogen (N) transformation and bacterial community diversity during chicken manure composting. The addition of OTC inhibited nitrifying bacteria, resulted in a decrease in the transformation of NH4+-N to NO3−-N during composting, and affected in the order T3 (32.76%) > T2 (28.76%) > T1 (17.02%) > CK. The OTC could act as an inhibitor against core microbial growth, leading to a delay effect during composting. 16S rRNA sequencing was employed for the functional prediction, and results indicated the bacterial community related to N transformation reconstructed under OTC stress. The core microorganisms were changed after OTC addition, with the emergence of Bacillus and Thermobifida, which could inhibit the N transformation by network analysis. Therefore, core microorganisms could be regulated to reduce the negative of OTC impacts on N transformation and thus reduce N loss during composting.

A carbon dot-based fluorometric probe for oxytetracycline detection utilizing a Förster resonance energy transfer mechanism.

A carbon dot (CD)-based fluorometric probe for oxytetracycline (OTC) detection utilizing a Förster resonance energy transfer (FRET) mechanism was firstly developed. Upon addition of OTC, the blue fluorescence of the CDs peaked at 405nm was quickly quenched, with a new fluorescence peaked at 505nm attributed to OTC was observed within 30s. A visual fluorescent color change of the CDs solution from blue to green was discerned under a 365nm UV light irradiation. The CDs displayed a high sensitivity and selectivity toward OTC with a low detection limit of 0.41μM. Furthermore, the probe was applied to detect OTC in water, milk, and pork samples with a satisfied recovery.

Impacts of cadmium addition on the alteration of microbial community and transport of antibiotic resistance genes in oxytetracycline contaminated soil

The large-scale development in livestock feed industry has increased the chances of antibiotics and heavy metals contamination in the soil. The fate of antibiotic resistance genes (ARGs) and microbial community in heavy metals and antibiotic contaminated soil is still unclear. In this study, we investigated the effect of cadmium (Cd) addition on the transport of ARGs, microbial community and human pathogenic bacteria in oxytetracycline (OTC) contaminated soil. Results showed that the addition of OTC significantly increased the abundance of ARGs and intI1 in the soil and lettuce tissues. The addition of Cd to OTC treated soil further increased the abundance and translocation of ARGs and intI1. Moreover, Cd promoted the transfer of potential human pathogenic bacteria (HPB) into lettuce tissues. Compared with O10 treatment, the addition of Cd decreased the concentration of OTC in soil and lettuce tissue, but slightly increased the fresh weight of lettuce tissues. Redundancy analysis indicated that bacterial community succession is a major factor in ARGs variation. Network analysis indicated that the main host bacteria of ARGs were mainly derived from Proteobacteria. Correlation analysis showed that intI1 was significantly correlated with tetG, tetC, sul1, sul2, ermX, and ermQ. Meanwhile, potential HPB (Clostridium, and Burkholderia) was significantly correlated with intI1 and eight ARGs (tetG, tetC, tetW, tetX, sul1, sul2, ermX, and ermQ.). The findings of this study suggest that the addition of heavy metals to agricultural fields must be considered in order to reduce the transfer of ARGs in the soil and crops.

Veterinary antibiotic oxytetracycline\u2019s effect on the soil microbial community

BackgroundAntibiotics are widely used to treat animals from infections. After fertilizing, antibacterials can remain in the soil while adversely affecting the soil microorganisms. The concentration of oxytetracycline (OTC) in the soil and its effect on the soil microbial community was assessed. To assess the impact of OTC on the soil microbial community, it was added to the soil at concentrations of 50, 150, and 300 mg kg–1 and incubated for 35 days.ResultsThe concentration of OTC added to the soil decreased from 150 to 7.6 mg kg–1 during 30 days of incubation, as revealed by LC-MS. The deviations from the control values in the level of substrate-induced respiration on the 5th day of the experiment were, on average, 26, 68, and 90%, with OTC concentrations at 50, 150, and 300 mg kg–1, respectively. In samples with 150 and 300 mg kg–1 of OTC, the number of bacteria from the 3rd to 14th day was 2–3 orders of magnitude lower than in the control. The addition of OTC did not affect the fungal counts in samples except on the 7th and 14th days for the 150 and 300 mg kg–1 contaminated samples. Genes tet(M) and tet(X) were found in samples containing 50, 150, and 300 mg kg–1 OTC, with no significant differences in the number of copies of tet(M) and tet(X) genes from the OTC concentration.ConclusionsOur results showed that even after a decrease in antibiotic availability, its influence on the soil microbial community remains.

A fluorometric assay for oxytetracycline based on the use of its europium(III) complex and aptamer-modified silver nanoparticles

An ultrasensitive assay is described for the determination of oxytetracycline (OTC) at nanomolar levels. The method is using silver nanoparticles (AgNPs) that were first modified with OTC-binding aptamer and then exposed to the OTC-Eu(III) complex. The pink fluorescence of the OTC-Eu(III) complex on the AgNPs is almost completely quenched. On addition of OTC, it will compete with the OTC-Eu(III) complex for binding to the aptamer on the AgNPs. The OTC-Eu(III) complex is released and becomes strongly fluorescent, with excitation/emission peaks at 385/620nm. The resulting assay was validated in terms of linearity and linear range, sensitivity, selectivity, detection limit and accuracy. Under optimum conditions, response is linear in the 10 to 500nM OTC concentration range, and the limit of detection is 1.9nM. The method was applied to the determination of OTC in spiked milk and tablets samples, and it gave satisfactory results. Graphical abstract Schematic presentation of the assay. In the presence of oxytetracycline (OTC), it will compete with the OTC-europium(III) complex for binding to the silver nanoparticles (AgNPs)-aptamer conjugate. The OTC-Eu(III) complex is released and strong pinkfluorescence is observed.

Bioelectrical power generation coupled with high-strength nitrogen removal using a photo-bioelectrochemical fuel cell under oxytetracycline stress

Photo-bioelectrochemical fuel cell shows great potential as an environmental-friendly technology for converting solar energy and bioenergy into electricity with simultaneous wastewater treatment. The present work aims to assess the performance of an algal-bacterial biocathode photo-bioelectrochemical fuel cell (ABPBFC) operated with daily light/dark cycle for simultaneous bioelectrical power generation and high-strength nitrogen removal under oxytetracycline (OTC) stress by adding different concentrations of OTC into the biocathode. The results showed that the power generation of the ABPBFCs was significantly enhanced by the presence of OTC at all levels tested (5–50 mg/L) due to enhanced electron transfer from cathode to oxygen and nitrate mediated by degradation products of OTC, but the enhancement was not proportional to the rise in OTC concentration. The largest maximum power density of 54 mW/m2 was achieved at 5 mg/L OTC during light period and 8.5 mW/m2 was produced at 20 mg/L OTC during dark period, corresponding to a 1.8 and 7.5 fold increases compared to that of the ABPBFC without addition of OTC. The removal of nitrate was obviously accelerated by the addition of OTC with an initial OTC concentration lower than 20 mg/L. Increases in the concentration of OTC added to the biocathode did not result in continuous enhancement in power generation and nitrate removal due to the toxicity of OTC to biocathodic microbial community. Cathodic bioelectrochemical process enhanced photolysis of OTC, which was attributed to its contribution to basification of catholyte. The growth of some dominated genus related to biocathodic electron transfer, nitrogen removal and OTC degradation were stimulated at OTC concentrations less than 20 mg/L but inhibited at 50 mg/L, except for some OTC-resistant bacteria.

Impact of oxytetracycline and bacterial bioaugmentation on the efficiency and microbial community structure of a pesticide-degrading biomixture.

An experimental study evaluating the effect of bioaugmentation and antibiotic (oxytetracycline) application on pesticide degradation and microbial community structure of a biomixture used in a biopurification system (BPR) was conducted. The bioaugmentation employed a carbofuran-degrading bacterial consortium. The non-bioaugmented biomixture showed excellent performance for removal of atrazine (t1/2: 9.9days), carbendazim (t1/2: 3.0days), carbofuran (t1/2: 2.8days), and metalaxyl (t1/2: 2.7days). Neither the addition of oxytetracycline nor bioaugmentation affected the efficiency of pesticide removal or microbial community (bacterial and fungal) structure, as determined by DGGE analysis. Instead, biomixture aging was mainly responsible for microbial population shifts. Even though the bioaugmentation did not enhance the biomixtures' performance, this matrix showed a high capability to sustain initial stresses related to antibiotic addition; therefore, simultaneous elimination of this particular mixture of pesticides together with oxytetracycline residues is not discouraged.