Fate of dissolved organic matter affected by oxytetracycline tolerant microorganisms during chicken manure composting

This study explored the interaction among the components of dissolved organic matter (DOM), environmental factors and oxytetracycline (OTC) tolerant bacteria during chicken manure composting using Parallel Factor Analysis (PARAFAC) and 16S rRNA sequencing analysis. The results revealed that the OTC residues in chicken manure may affect the transformation between the protein-like component (C1) and humus-like component (C2 and C3) during composting. The transformation of DOM components under the OTC stress was indirect by affecting the microbial community activity. The OTC tolerant bacteria that still exist after the high temperature period of composting had a significant positive correlation between the humification process. The correlations of the dissolved organic carbon (DOC), total nitrogen (TN), and core OTC tolerant bacteria with DOM components, which enhanced the cooperative function of DOM component transformation. To clarify the influence of OTC residue on the humification process can promote the composting carbon fixation and improve composting quality.

Toxicity of emerging contaminant antibiotics in soil to Capsicum annuum L. growth and their effects on it accumulating copper

Antibiotics are a kind of emerging contaminant in soil. Tetracycline (TC) and oxytetracycline (OTC) in soil are often detected, even with very high concentration in the soils of facility agriculture due to their good effect, low price and large usage. Copper (Cu) is common heavy metal pollutant in soil. The toxicity roles of TC, OTC and/or Cu in soil on a commonly consumed vegetable Capsicum annuum L. and its Cu accumulation were not clear till now. The results of pot experiment showed that the TC or OTC added in soil alone didn't produce poison effects for C. annuum after 6 weeks and 12 weeks growth reflected by some physiological index like SOD, CAT and APX activities changes, while the biomass changes affirmed them either. Cu contaminated soil significantly inhibited the growth of C. annuum. Furthermore, combined pollution of Cu with TC or OTC was with more serious suppression of C. annuum growth. The suppression role of OTC was heavier than TC in Cu and TC or OTC contaminated soil. Such phenomenon was relevant with the role of TC or OTC increased Cu concentration in C. annuum. The improvement role of TC or OTC on Cu accumulation in C. annuum caused by the increased extractable Cu concentration in soil. The study demonstrated that TC or OTC added in soil alone was without any toxicity to C. annuum. But they may aggravate the hurt of C. annuum caused by Cu through increased its accumulation from soil. Thus, such combine pollution should be avoided in safe agricultural product.

The enhanced degradation behavior of oxytetracycline by black soldier fly larvae with tetracycline resistance genes in the larval gut: Kinetic process and mechanism

Black soldier fly larvae (larvae) can digest organic wastes and degrade contaminants such as oxytetracycline (OTC). However, compared to the kinetic processes and enhanced mechanisms used in the traditional microbial degradation of OTC, those employed by larvae are largely uncharacterized. To obtain further details, a combined analysis of larval development, larval nutritional values (crude protein, crude fat and the composition of fatty acids) and the expression of tetracycline resistance genes (TRGs) in the larval gut was performed for the degradation of OTC added to substrates and for oxytetracycline bacterial residue (OBR). When the larvae were exposed to the substrates, the degradation processes were enhanced significantly (P < 0.01), with a 4.74-7.86-fold decrease in the degradation half-life (day^-1) and a 3.34-5.74-fold increase in the final degradation efficiencies. This result was attributed to the abundant TRGs (with a detection rate of 35.90%∼52.14%) in the larval gut. The TRGs presented the resistance mechanisms of cellular protection and efflux pumps, which ensured that the larvae could tolerate elevated OTC concentrations. Investigation of the TRGs indicated that enzymatic inactivation enhanced OTC degradation by larvae. These findings demonstrate that the larval degradation of antibiotic contaminants is an efficient method based on abundant TRGs in the larval gut, even though OTC degradation results in OBR. In addition, a more optimized system for higher reductions in antibiotic levels and the expansion of larval bioremediation to other fields is necessary.

Characteristics of oxytetracycline stress-sensitive microbe-dissolved organic matter component interactions during composting

Dissolved organic matter (DOM) has important impacts on the transportation of antibiotics through chemical and biological processes in composting. The interaction between DOM and antibiotics is reciprocal. The interaction between DOM ligands and antibiotics could be characterized based on a technique combining parallel factor analysis (PARAFAC) and microbial community structure analysis. However, PARAFAC cannot reveal the dynamic changes in each DOM peak in one PARAFAC component under antibiotic stress. In this study, two-dimensional correlation spectroscopy (2DCOS) combined with PARAFAC and bacterial community diversity analyses were employed to reveal the effects of oxytetracycline (OTC) stress and the key microorganisms on the transformation of different fluorescent peaks from DOM PARAFAC components during chicken manure composting. The results showed that OTC inhibits the transformation between DOM PARAFAC components by inhibiting the core microbial activities involved in the transformation of DOM components. Protein-like components (C1 and C2) were more sensitive to OTC residue, and components with a high humification degree promoted the degradation of OTC. The interaction between special DOM PARAFAC components and certain bacteria affects the degradation of OTC. The DOM PARAFAC components A2(C1), B1(C2), B2(C2) and Z1(C4) enhanced OTC degradation by stimulating the genera Pseudomonas, Glycomyces and Hyphomicrobium. With these promising results, the true effect of DOM PARAFAC components on the degradation of OTC can be revealed, which is helpful for addressing antibiotic contamination to improve the bioavailability of compost products.

Stress response to oxytetracycline and microplastic-polyethylene in wheat (Triticum aestivum L.) during seed germination and seedling growth stages

Much efforts have been devoted to clarify the phytotoxicity of individual contaminants in plants, such as individual antibiotic and microplastic; however, little is known about the phytotoxicity of their combined exposure. Here, we investigated the effects of individual and combined exposure of wheat (Triticum aestivum L.) (Xiaoyan 22) to oxytetracycline (OTC) and polyethylene (PE) microplastics using physiological and metabolic profilings. During the seed germination stage, OTC induced phytotoxicity, as observed through the changes of root elongation, sprout length, fresh weight and the vitality index, with significant effect at the 50 and 150 mg·L^-1 levels; the effect of PE microplastics depended on the OTC level in the combined exposure groups. During seedling cultivation, catalase (CAT) and ascorbate peroxidase (APX), as antioxidant enzyme indices, were sensitive to OTC exposure stress, although OTC was not determined in leaves. Untargeted metabolomics of wheat leaves revealed OTC concentration-, metabolite class- and PE-dependent metabolic responses. Dominant metabolites included carboxylic acids, alcohols, and amines in the control group and all treatment groups. Compared to only OTC treatment, PE reprogrammed carboxylic acid and alcohol profiles in combined exposure groups with obvious separation in PLS-DA. Combined exposure induced fewer metabolites than OTC exposure alone at the 5 and 50 mg·L^-1 levels. The shared metabolite numbers were higher in the OTC groups than in the PE-OTC groups. Pathway enrichment analysis showed a drift in metabolic pathways between individual and combined exposure to OTC and PE, which included glyoxylate and dicarboxylate metabolism, amino acid metabolism and isoquinoline alkaloid biosynthesis. Among metabolites, aromatic acids and amino acids were more sensitive to combined exposure than individual exposure. These results contribute to clarifying the underlying mechanisms of phytotoxicity of individual and combined exposure to OTC and PE.

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.

Dynamic evolution of electrochemical and biological features in microbial fuel cells upon chronic exposure to increasing oxytetracycline dosage

Dynamic changes in power generation and electrochemical properties were compared between the control microbial fuel cells (C-MFC) and an oxytetracycline (OTC)-treated MFC (O-MFC) on days 84, 139, 174, 224, 295, 307 and 353. The results showed that a high concentration of OTC (>5 mg·L^-1) could inhibit microbial activity and result in a decline of voltage output and power density compared with the same C-MFC. However, with the prolongation of incubation time, the inhibitory effect was gradually weakened. Electrochemical analyses demonstrated that long-term OTC acclimation reduced the ohmic and polarisation resistance of the anode, which was conducive to the recovery of electrochemical performance. More than 99% of 10 mg·L^-1 OTC could be removed within 48 h, and the antibacterial activity of the MFC effluent on Escherichia coli DH5α was conclusively eliminated. High-throughput sequencing analysis revealed that the diversity and richness of the microbial community decreased significantly after long-term OTC enrichment. Acinetobacter, Petrimonas, Spirochaetaceae and Delftia were enriched and played a dominant role in C-MFC stability and power generation. The promotion by Cupriavidus, Geobacter and Stenotrophomonas in simultaneous OTC degradation and bioelectricity generation in the O-MFC was demonstrated.

Response of denitrifying community, denitrification genes and antibiotic resistance genes to oxytetracycline stress in polycaprolactone supported solid-phase denitrification reactor

The coexistence of nitrate and antibiotics in wastewater is a common problem. The study aimed to explore the response of denitrifying community, denitrification genes and antibiotic resistance genes (ARGs) to oxytetracycline (OTC) stress in polycaprolactone (PCL) supported solid-phase denitrification (SPD) reactors. Complete nitrate reduction (greater than99%) was achieved in SPD system with OTC stress of 0, 0.05, 0.25 and 1 mg L^-1 during three-month operation, while it significantly declined by about 5% at a further increased OTC level of 5 mg L^-1. The efficient denitrification strongly related with a rich diversity of denitrifiers, while the abundances of which dramatically reduced as the OTC concentration reached ≥0.25 mg L^-1, which caused significant decline of denitrification genes, especially for narH, narJ, narI nirD, nosZ, and norB. Tetracycline resistance genes were a major type of promoted ARGs by different OTC stress, mainly related with the increase of tet36, tetG, tetA, tetM and tetC.

The key factors and removal mechanisms of sulfadimethoxazole and oxytetracycline by coagulation

The effects of coagulant dosage, alkalinity, turbidity, ionic strength, and dissolved organic matter (DOM) on the removal of sulfadimethoxazole (SMZ) and oxytetracycline (OTC) by coagulation were studied and the reaction mechanisms of the coagulation process were revealed in this research. From our results, alkalinity, turbidity, ionic strength, and DOM had different effects on the removal of antibiotics. The SMZ and OTC removals were improved with increase in poly-aluminum chloride (PACl) dosage, whereas the turbidity had less influence on the removal of SMZ and OTC because the adsorption of SMZ and OTC to kaolin was low, confirmed by a control when no PACl added. The hydrolysate of PACl played a more important role than turbidity in SMZ and OTC removals. The SMZ and OTC removals were significantly increased with the increase in alkalinity, which provided a suitable condition in situ for coagulant to form more optimal species of hydrolysate. The ionic strength, which was adjusted by NaNO₃, also had a positive effect on the removal of SMZ but no obvious effect on the OTC removal. Furthermore, DOM had a higher effect on the removal of SMZ than that of OTC. In another word, if a water plant wants to improve the removal of SMZ and OTC by coagulation unit, PACl hydrolysate, alkalinity, and DOM are the three key factors to be considered primarily. Moreover, an experiment for the recovery of antibiotics from the flocs was done and the results showed that OTC and SMZ were removed by different mechanisms. The OTC was removed via complexation formed through the reaction between OTC and coagulant while the SMZ was removed through the pathway of adsorption and inter-particle bridging to the surface of coagulant hydrolysate.

Calcium Ions Turn on the Fluorescence of Oxytetracycline for Sensitive and Selective Detection

Herein, we report an interesting finding about the new application of oxytetracycline (OTC), as a fluorescent probe for the detection of calcium ion (Ca²⁺), which proved that it can offer an expeditious, highly sensitive, and selective detection method for Ca²⁺. Upon the addition of Ca²⁺, the fluorescence of OTC could be significantly enhanced with rapid response and high sensitivity, and achieved a good limit of detection as low as 125 nM in aqueous solution. The complex formed via Ca²⁺ coordinating to the hydroxyl group of OTC contributes to the fluorescence enhancement, which has been proved by several characterization methods including UV-vis analysis, binding constant determination, and fluorescence titration. The method avoided complexity for EDTA measurement of Ca²⁺ in running water as proposed previously. Taking advantage of good availability, stability and operability, the OTC was further successfully applied to the detection of Ca²⁺ in a real environment. Graphical Abstract.

Citric acid and glycine reduce the uptake and accumulation of Fe2O3 nanoparticles and oxytetracycline in rice seedlings upon individual and combined exposure

Uptake of nanoparticles and antibiotics by plants is root exudates-dependent, however, the underlying influence processes and mechanisms from different root exudates are rarely investigated. A hydroponic experiment was conducted to investigate the accumulation of Fe₂O₃ nanoparticle (NP) and oxytetracycline (OTC) in rice seedlings, in the absence or presence of citric acid or glycine, acting as components of root exudates. Irrespective of individual or combined exposure of Fe₂O₃ NP and OTC, citric acid and glycine both reduced surface-Fe, surface-OTC, root-OTC, shoot-OTC accumulations with dose-effect relationship. Two exudates increased |ζ| values of NP, which weakened the interactive attraction between NP and root surface and then decreased surface-Fe accumulation. Citric acid and glycine binding with OTC in solution decreased surface-OTC accumulation, and further decreased root-OTC and shoot-OTC accumulations. Combined exposure of two pollutants alleviated the reduction effect of citric acid and glycine on surface-Fe/surface-OTC/root-OTC accumulations due to their high accumulations in combined exposure compared to individual exposure. Although citric acid and glycine promoted TF_root-shoot and TF_surface-root of two pollutants, respectively, they always decreased total rice-Fe and rice-OTC accumulations. Therefore, the presence of root exudates decreased the bioaccumulation of Fe₂O₃ NP and OTC in rice upon their individual and combined exposure through changing their environmental behaviors in rhizosphere.

Microbial community evolution and fate of antibiotic resistance genes in anammox process under oxytetracycline and sulfamethoxazole stresses

The microbial community characteristics, functional and antibiotic resistance genes (ARGs), anammox performance under individual and combined oxytetracycline (OTC) and sulfamethoxazole (SMX) were tested under environmentally relevant levels. The results showed that anammox performance was inhibited when the OTC or SMX concentration increased from 0.5 to 1.0 mg L^-1. The absolute abundance of tetX in OTC (3.03 × 10⁶ copies mg^-1), SMX (2.80 × 10⁶ copies mg^-1) and OTC + SMX (2.03 × 10⁶ copies mg^-1) was the highest and one more order of magnitude higher than that of tetG, tetM, intI1, or sul2. The anammox performance in the presence of OTC or SMX was lower than that sum of their independent effects. The enrichment of sludge resistomes with prolonged exposure time and increasing OTC and SMX doses might be due to succession of bacterial hosts and potential elevation of ARGs by horizontal transfer.

Aptamer-based thin film gold electrode modified with gold nanoparticles and carboxylated multi-walled carbon nanotubes for detecting oxytetracycline in chicken samples

In this work, a disposable and portable aptasensor for the fast and sensitive detection of oxytetracycline (OTC) using gold nanoparticles (AuNPs)/carboxylated multi-walled carbon nanotubes (cMWCNTs)@thionine connecting complementary strand of aptamer (cDNA) as signal tags was constructed. The substrate electrode of the aptasensor was thin film gold electrode (TFGE), which have the advantages of portable and uniform performance. In the presence of OTC, OTC competed with cDNA to combine with aptamer. The bioconjugate (AuNPs/cMWCNTs/cDNA@thionine) was released from the TFGE. Thus, the electrochemical signal declined. Under optimized conditions, the aptasensor exhibited good stability, high selectivity and high sensitivity. Furthermore, the developed electrochemical aptamer-based TFGE had a wide dynamic range of 1 × 10^-13-1 × 10^-5 g mL^-1 for target OTC with a low detection limit of 3.1 × 10^-14 g mL^-1 and was successfully used for the determination of OTC in chicken sample.

Action of oxytetracycline (OTC) degrading bacterium and its application in Moving Bed Biofilm Reactor (MBBR) for aquaculture wastewater pre-treatment

In this study, the characteristics of biodegradation of oxytetracycline (OTC) by strain Ochrobactrum sp. KSS10 were studied under various environmental conditions, including initial OTC concentrations, variable temperature, initial pH, and diverse carbon sources. The capability of this bacterial strain for performing simultaneous OTC degradation and nitrate reduction was also explored under aerobic conditions. An OTC degradation ratio of 63.33% and a nitrate removal ratio of 98.64% were obtained within 96 h. In addition, removal of OTC and ammonia from synthetic aquaculture wastewater by a Moving Bed Biofilm Reactor (MBBR) and changes in the resistant genes of microbial communities were also investigated. The results demonstrated that the strain KSS10 was the dominant contributor in OTC and ammonia removal in the MBBR chamber. It removed almost all ammonia and approximately 76.42% of OTC. The abundances of genes tetL, tetX and intI1 were reduced by the MBBR, but the abundance of tetG and tetM were increased due to horizontal and vertical gene transfers. Such a result can potentially be used by the strain KSS10 for removing antibiotics and nitrogen from aquaculture wastewater during pre-treatment.

Bacterial community shift and antibiotics resistant genes analysis in response to biodegradation of oxytetracycline in dual graphene modified bioelectrode microbial fuel cell

This study explored the biodegradation mechanisms of oxytetracycline (OTC/O) and electrochemical characteristics from the perspective of bacterial community shift and OTC resistance genes in dual graphene modified bioelectrode microbial fuel cell (O-D-GM-BE MFC). In phylum level, Proteobacteria was accounted to 95.04% in O-GM-BA, Proteobacteria and Bacteroidetes were accounted to 59.13% and 20.52% in O-GM-BC, which were beneficial for extracellular electron transport (EET) process and OTC biodegradation. In genus level, the most dominant bacteria in O-GM-BA were Salmonella and Trabulsiella, accounting up to 83.04%, moreover, representative exoelectrogens (Geobacter) were enriched, which contributed to OTC biodegradation and electrochemical performances; abundant degrading bacteria (Moheibacter, Comamonas, Pseudomonas, Dechloromonas, Nitrospira, Methylomicrobium, Pseudorhodoferax, Thiobacillus, Mycobacterium) were enriched in O-GM-BC, which contributed to the maximum removal efficiency of OTC; coding resistance genes of efflux pump, ribosome protective protein and modifying or passivating were all found in O-GM-BE, and this explained the OTC removal mechanisms from gene level.

Influence of the root plaque formation with different species on oxytetracycline accumulation in rice (Oryza sativa L.) and its elimination in culture solution

Hydroponic experiments were conducted to investigate the role of different root plaque formation on oxytetracycline (OTC) uptake/translocation by rice seedlings (Oryza sativa L.) and solution-OTC elimination at two initial OTC concentrations (10 and 30 mg L^-1). The results indicated OTC accumulation in rice was always in the order root surface > shoot > inside root whether plaques were formed or not. It demonstrated that Fe-Mn-Mt (montmorillonite) treatment was easier to promote significantly (p < 0.05) OTC accumulation in the underground part (root surface and inside root) and decrease significantly (p < 0.05) OTC translocation from the root to the shoot in rice compared to no plaque treatments (CK), especially for OTC 30 mg L^-1 level with the lowest shoot-OTC accumulation in Fe-Mn-Mt treatment. Plaque treatments increased half-life of solution-OTC elimination in the order Fe-Mn-Mt > Fe-Mn > Fe > CK, which was caused mainly by OTC degradation from Fe²⁺-binding influence in solution, not by the enhancement of OTC accumulation on the root surface and inside root. And solution-OTC elimination increased with decreasing initial OTC concentrations, the drop of Fe²⁺ and the increment of Fe³⁺ and pH during the experiment. These findings are useful for reducing OTC accumulation and translocation in rice aboveground parts and eliminating OTC contamination in agricultural environment simultaneously through complicated plaque formation under higher OTC concentration exposure (30 mg L^-1) in the future design.

Biodegradation of oxytetracycline and electricity generation in microbial fuel cell with in situ dual graphene modified bioelectrode

A three-step method to prepare dual graphene modified bioelectrode (D-GM-BE) in microbial fuel cell (MFC) in previous studies. This study explored the biodegradation of oxytetracycline (OTC) and electricity generation in O-D-GM-BE MFC. The OTC removal efficiency of graphene modified biocathode and bioanode (O-GM-BC, O-GM-BA) was 95.0% and 91.8% in eight days. The maximum power density generated by O-D-GM-BE MFC was 86.6 ± 5.1 mW m^-2, which was 2.1 times of that in OTC control bioelectrode (O-C-BE) MFC. The Rct of O-GM-BA and O-GM-BC were decreased significantly by 78.3% and 76.3%. OTC was biodegraded to monocyclic benzene compounds by bacteria. O-GM-BA was affected strongly by OTC, and Salmonella and Trabulsiella were accounted for 83.0%, while typical exoelectrogens (Geobacter) were still enriched after the maturity of biofilm. In O-GM-BC, bacteria related with OTC biodegradation (Comamonas, Ensifer, Sphingopyxis, Pseudomonas, Dechloromonas, etc.) were enriched, which contributed to the high removal efficiency of OTC.

Residue depletion of oxytetracycline (OTC) and 4-epi-oxytetracycline (4-epi-OTC) in broiler chicken's claws by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Antibiotics are widely used in poultry production for the treatment of bacterial diseases. However, residues may remain in products and by-products destined for human consumption or animal feeding. The claws of chickens, which are a by-product of the poultry industry, can directly or indirectly enter the food chain as meals destined to feed other productive animals. Thus, it becomes necessary to determine and quantify antimicrobial residues present in this matrix. The objective of the study was to assess the depletion of oxytetracycline (OTC) and its metabolite 4-epi-OTC in broiler chicken's claws. Claws of 32 broilers treated with a therapeutic dosage of 10% OTC during 7 days were analysed. Samples were taken at days 3, 9, 15 and 19 post-treatment. As for the control group, eight broiler chickens were raised under the same conditions. Extraction was carried out through EDTA-McIlvaine buffer, and clean-up employed a SPE C-18 Sep-Pak®. Instrumental analysis was performed through LC-MS/MS. The concentrations of both analytes were determined in claw samples until day 19 post-treatment. Average concentrations were within the LOD (20 μg kg^-1) and LOQ (22 µg kg^-1) for OTC and 84 μg kg^-1 for 4-epi-OTC. Withdrawal times (WDTs) of 39 days for OTC and 54 days for 4-epi-OTC were established in claws based on 95% confidence. These findings demonstrate that claws can be a source of antimicrobial residue entry into the food chain, since the results showed that OTC and its metabolite can be found in chicken's claws for long periods, even exceeding the average lifespan of a broiler chicken.

A sensitive electrochemical aptasensor for multiplex antibiotics detection based on high-capacity magnetic hollow porous nanotracers coupling exonuclease-assisted cascade target recycling

A multiplex electrochemical aptasensor was developed for simultaneous detection of two antibiotics such as chloramphenicol (CAP) and oxytetracycline (OTC), and high-capacity magnetic hollow porous nanotracers coupling exonuclease-assisted target recycling was used to improve sensitivity. The cascade amplification process consists of the exonuclease-assisted target recycling amplification and metal ions encoded magnetic hollow porous nanoparticles (MHPs) to produce voltammetry signals. Upon the specific recognition of aptamers to targets (CAP and OTC), exonuclease I (Exo I) selectively digested the aptamers which were bound with CAP and OTC, then the released CAP and OTC participated new cycling to produce more single DNA, which can act as trigger strands to hybrid with nanotracers to generate further signal amplification. MHPs were used as carriers to load more amounts of metal ions and coupling with Exo I assisted cascade target recycling can amplify the signal for about 12 folds compared with silica based nanotracers. Owing to the dual signal amplification, the linear range between signals and the concentrations of CAP and OTC were obtained in the range of 0.0005-50 ng mL(-1). The detection limits of CAP and OTC were 0.15 and 0.10 ng mL(-1) (S/N=3) which is more than 2 orders lower than commercial enzyme-linked immunosorbent immunoassay (ELISA) method, respectively. The proposed method was successfully applied to simultaneously detection of CAP and OTC in milk samples. Besides, this aptasensor can be applied to other antibiotics detection by changing the corresponding aptamer. The whole scheme is facile, selective and sensitive enough for antibiotics screening in food safety.