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Currently, oxytetracycline and streptomycin are being applied to citrus groves in Florida for the control of citrus greening disease caused by the unculturable bacterium Candidatus Liberibacter asiaticus. Here, the closest cultured relative, L. crescens, was used to estimate the frequency of spontaneous antimicrobial resistance of Liberibacter spp. Results yielded thirteen streptomycin and zero oxytetracycline mutants after exposing 13 billion cells to the antimicrobials. These low rates, alongside the restrictive habitats of the vector and pathogen, suggest resistance may develop very slowly, if at all. Thus, the treatments will likely remain useful long enough before pathogen-resistant or -tolerant genotypes are deployed.

AbstractMiniaturized procedures for chemical analysis give the possibility of a significant reduction in quantities of organic solvents used during isolation and determination processes. Liquid-liquid microextraction (LLME) using butanol as an extractant was investigated to selectively isolate oxytetracycline (OTC) antibiotic residues from dairy products. The optimal conditions of LLME were established after deproteinization of the samples. The isolation procedure for OTC was performed using 700 µL of butanol. The extracts were analysed by HPLC-UV and LC-MS/MS. A satisfactory analyte recovery was achieved in the range 97.6%–98.9%. The concentration of the linearity range of the studied antibiotic should allow its determination at the level of MRL values. The limit of detection during HPLC-UV and LC-MS/MS determination of OTC in milk samples was 9.9·10−8 mol L−1 (47.85 µg kg−1) and 5.7·10−9 mol L−1 (2.75 µg kg−1), respectively. The precision (1.7%–8.6%) of the methods using LLME isolation of OTC varied depending on the kind of sample and the chromatographic technique used. The developed methods were applied to the analysis of milk and cottage cheese to estimate the presence and detection of OTC content. [ABSTRACT FROM AUTHOR]

The abuse of antibiotics has caused severe environmental issues. Photocatalytic treatment technology has the advantages of high efficiency, strong effectiveness and no secondary pollution, which presents great potential for degrading or removing many kinds of environment pollutants. However, the intermediate products formed during the photocatalytic degradation process of antibiotics may possess greater toxicity than the antibiotics themselves, and the toxicity of most of these intermediates still remains unclear. Therefore, understanding the photocatalytic degradation pathways of antibiotics and obtaining qualitative and quantitative information about the main degradation products are of vital importance for the large-scale application of photocatalytic technology in the removal of antibiotics and other pollutants. Probe electrospray ionization mass spectrometry (PESI-MS) technology, adopting a solid probe as the electrospray ionization emitter, has the advantages of rapid response, low sample consumption, high salt tolerance, and strong resistance to suspended particles. These features make PESI-MS to be an ideal technique for direct analysis of complex systems, such as biological and chemical reactions. In this study, PESI-MS was used to perform continuous real-time in situ monitoring and analysis of the photocatalytic degradation of oxytetracycline (OTC), which photocatalyzed by TiO2 under UV irradiation for 160 min, with spectra collected at a resolution of 1 spectrum per second. The results showed that the intensity of protonated OTC ions decreases progressively during the reaction, and forms product ions at various stages of degradation. 35 Kinds of key degradation products are identified by high time-resolved spectra. Based on the changes in the extracted ion chromatograms (EIC) of these products, 7 major degradation products are screened out and 10 possible degradation pathways are proposed, two of which can lead to the degradation of OTC into lower molecular weight products. Although complete photocatalytic degradation of OTC is not achieved in the experimental conditions, the amount of degradation products observed in this study is significantly higher than those previously reported using various high performance liquid chromatography mass spectrometry (HPLC-MS). Furthermore, in the early stages of the photocatalytic process, products of combined ethyl radicals and ethoxy radicals are detected, which likely are contributed by the ethanol added intentionally in the reaction. The use of organic solvents to reduce solution surface tension during PESI operation at atmospheric pressure is inevitable. In the future, we aim to develop a high-pressure PESI ionization source to resolve this issue, which is expected to reveal a more accurate photocatalytic reaction mechanism and pathway. The findings of this study provide valuable data for understanding the kinetics of photocatalytic reactions and developing new photocatalysts, helping researchers gain a more comprehensive understanding of photocatalytic mechanisms. [ABSTRACT FROM AUTHOR]

Nitrogen-doped silicon quantum dots (N-SiQDs) with a quantum yield of up to 37.8% were simply synthesized using inexpensive and readily available silica as the silicon source. Based on the internal filter effect (IFE), both oxytetracycline (OTC) and tetracycline (TC) can effectively and rapidly quench the fluorescence of N-SiQDs at 380 nm. However, interestingly, the accompanied formation of a new complex of OTC with N-SiQDs could emit fluorescence at 505 nm, resulting in a gradual color change of the sensor from blue to yellow under the irradiation of 365 nm UV lamp. Thus, a visual semi-quantitative detection of OTC was realized. In contrast, based on the aggregation-induced luminescence (AIE) effect, chlortetracycline (CTC) linearly enhanced the fluorescence intensity of N-SiQDs, which can effectively reduce other interfering signals, and can significantly improve the sensitivity and selectivity. Hence, a low limit of detection of 47 nM for CTC was obtained. On account of the three distinctly different phenomena and mechanisms of N-SiQDs sensor exhibited towards OTC, TC, and CTC, a novel sensing method for discriminating and selectively measuring OTC, TC, and CTC in food was developed. [ABSTRACT FROM AUTHOR]

A two-dimensional porphyrin-MOF nanolayer was developed to construct an electrochemical aptasensor for monitoring oxytetracycline from 0.01 pg mL−1 to 0.1 ng mL−1. This aptasensor exhibited high sensitivity, outstanding selectivity, good stability, fine reproducibility, and quantitative detection ability in real samples. [ABSTRACT FROM AUTHOR]

The excessive presence of antibiotics such as Oxytetracycline (OTC) in the wastewater has increased health problems due to their toxic impact on the aquatic ecosystem. Therefore, their removal has become an important topic. This study aims to produce high surface area-activated carbon derived from low-cost and environmentally friendly barley lignocellulosic wastes to remove OTC from aqueous solutions. The synthesized barley wastes-activated carbon (BW-AC) was characterized using Fourier-Transform Infrared spectroscopy, Thermal Gravimetric Analysis, X-ray diffraction analysis, N2 adsorption/desorption isotherms, and Scanning Electron Microscopy. A Central Composite Design under the Response Surface Methodology (CCD-RSM) was applied to optimize the operational parameters (adsorbent dosage, pH, OTC initial concentration, and contact time) affecting the adsorption capacity as the response factor. The optimum condition of OTC adsorption by BW-AC was the adsorbent dosage of 16.25 mg, pH of 8.25, initial concentration of 62.50 mg/L, and contact time of 23.46 min. An analysis of variance (ANOVA) was performed to investigate the significance of the designed quadratic model and evaluate the parameters interactions. The linear regression coefficient (R2) of 0.975 shows a good correlation between predicted and actual results. The adsorption isotherms were used to determine the contaminant distribution over the adsorbent surface, and the equilibrium data was best described by the Freundlich isotherm due to the R2 value of 0.99 compared to other isotherms and β parameter of 0.23 in Redlich-Peterson equation. Moreover, the n value of 1.25 in Freundlich equation and E value of 0.31 in Dubinin–Radushkevich equation indicates a physical nature of adsorption process. According to the equations results, the maximum adsorption capacity of BW-AC for OTC removal was 500 mg/g, based on the Langmuir isotherm equation. In addition, the thermodynamic studies indicated an endothermic process based on the 0.31 value of ΔH° and spontaneous nature due to the negative amount of ΔG° within the temperature range of 288–318 K. Consequently, the prepared BW-AC can be deemed as a highly effective adsorbent with a large surface area, resulting in significant capacity for removing OTC. This synthesized BW-AC can serve as an environmentally friendly adsorbent for affordable wastewater treatment and is poised to make valuable contributions to future research in this field. [ABSTRACT FROM AUTHOR]

The presence of antibiotic residues in milk and kareish cheese poses potential risks to human health, attributed to the improper use of antibiotics in veterinary practices. To assess oxytetracycline residues by double-beam UV spectrophotometer, a total of 90 random samples were collected from markets in Assiut City, Egypt. These samples included raw and UHT milk, and kareish cheese. The results showed that oxytetracycline residues were detected in 100% of the analyzed milk samples and in 96.67% of kareish cheese. The means of oxytetracycline residue in raw milk, UHT milk, kareish cheese were 38.68 ± 2.15, 35.15 ± 3.05 and 40.98 ± 3.54 μg/kg, respectively. Also, the results showed that all analyzed milk were below the codex alimentarius maximum residual limit for oxytetracycline. Thermal treatments (boiling and freezing) of raw milk were followed by a determination of the content of oxytetracycline, and the results revealed that thermal treatment was effective in lowering such content. The reduction percentage of OTC residue after boiling and freezing of milk ranged from 8.32 to 68.28% and 2.58 to 81.63%, respectively, the antibacterial activities of some essential oils were studied against selected reference pathogenic bacteria (Escherichia coli O157, Staphylococcus aureus, and Salmonella typhimurium). The obtained results indicated that the used oils had high antibacterial activity. So, this research suggests that essential oils should be used as feed additives for livestock as they are effective antibacterial agents and safer than antibiotics. [ABSTRACT FROM AUTHOR]

We evaluated the effectiveness of three different treatment groups at managing apple shoot blight, and the resulting canker incidence and canker length on wood caused by Erwinia amylovora. Preventative foliar sprays or trunk injections of giant knotweed extract (Regalia), oxytetracycline (Arbor-OTC or FireLine + Regulaid), or streptomycin (Agri-mycin/FireWall + Regulaid) were applied to mature 'Fuji' trees. Regalia and oxytetracycline were ineffective at reducing shoot blight severity, showing poor disease reductions of 18.2% and 24.3% compared to untreated controls across both years. Streptomycin was effective at controlling shoot blight severity when applied as a spray application, reducing necrosis by up to 93.9% across both years. Canker incidence was also poorly reduced by Regalia and oxytetracycline with an average decrease of 33.3% and 52.4%, respectively. Again, spray applications of streptomycin were most effective at reducing canker incidence (95.2%). When present, canker length was best controlled by spray applications of streptomycin, showing an average reduction of 95.7%. The effectiveness of Regalia and oxytetracycline was poor, reducing canker length by only 30.4% and 43.5%, respectively. Trunk injections of Regalia were consistently less effective than spray applications. Compared to their spray application counterpart, Regalia injections were, on average, 12.5%, 26.3%, and 25.1% less effective at reducing shoot blight severity, canker incidence, and canker length, respectively. Injected Arbor-OTC was more effective than spray applications of oxytetracycline. On average, Arbor-OTC injections were up to 28.3%, 40.1%, and 30% more effective at reducing shoot blight severity, canker incidence, and canker length compared to spray applications. Overall, Regalia and oxytetracycline were not as effective as streptomycin at controlling fire blight. The search for organic antibiotic alternatives for shoot blight and canker control continues, as cankers are increasing in economic importance by causing bearing wood and young tree death. [ABSTRACT FROM AUTHOR]

Tetracyclines family is considered as the first-line antibiotic drugs for food animals. Formulating bromhexine (BR) with oxytetracycline (OTC) improved the antibacterial activity of OTC, besides it is considered as a mucolytic agent. Four precise, rapid, and simple spectrophotometric methods were successfully developed for resolution of the overlapped spectra of OTC and BR in their pure form and in their pharmaceutical formulation. The proposed methods are absorption correction (AC), dual wavelength (DW), induced dual wavelength (IDW), and spectrum subtraction (SS) spectrophotometric methods. The developed methods were used for the determination of OTC and BR in the ranges of 2–50 µg/mL and 1–30 µg/mL, respectively for all methods. For (AC) and (SS) methods, OTC and BR were determined at 380 nm and 245.6 nm, respectively after spectral resolution steps. While for (DW) method, the absorbance difference between λ (271.8 –287.6 nm) and λ (245.6 –283.2 nm) were used for the determination of OTC and BR, in order. For IDW, it depended on using the absorbance difference between 271.8 nm and 245.6 nm as well as the equality factor (F) calculated for each drug at the selected wavelengths. In all methods, HCl was used as a solvent and they are validated according to ICH guidelines. Several green metric tools have been developed to evaluate the greenness of the analytical methods like National Environmental Methods Index (NEMI), Modified NEMI, Analytical Eco-scale, Green Analytical Procedure Index (GAPI) and Analytical GREEnness calculator (AGREE), and all ensured the low impact of the suggested approaches on health and environment. The proposed methods are highly selective, robust and precise. Additionally they are time and money effective and can be used in any analytical laboratory. [ABSTRACT FROM AUTHOR]

Whether advanced biological waste treatment technologies, such as hydrothermal pretreatment (HTP) integrated anaerobic digestion (AD), could enhance the removal of different antibiotics remains unclear. This study investigated the outcome of antibiotics and methane productivity during pig manure treatment via HTP, AD, and HTP + AD. Results showed improved removal efficiency of sulfadiazine (SDZ), oxytetracycline (OTC), and enrofloxacin (ENR) with increased HTP temperatures (70, 90, 120, 150, and 170 °C). OTC achieved the highest removal efficiency of 86.8% at 170 °C because of its high sensitivity to heat treatment. For AD, SDZ exhibited resistance with a removal efficiency of 52.8%. However, OTC and ENR could be removed completely within 30 days. When HTP was used prior to AD, OTC and ENR could achieve complete removal. However, residual SDZ levels reduced to 20% and 16% at 150 and 170 °C, respectively. The methanogenic potential showed an overall upward trend as the HTP temperature increased. Microbial analysis revealed the antibiotics-induced enrichment of specific microorganisms during AD. Firmicutes were the dominant bacterial phylum, with their abundance positively correlated with the addition of antibiotics. Methanobacterium and Methanosarcina emerged as the dominant archaea that drove methane production during AD. Thus, HTP can be a potential pretreatment before AD to reduce antibiotic-related risks in manure waste handling. [ABSTRACT FROM AUTHOR]

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Nanosorbent NiFe2O4@g-C3N4 was produced via green and ultrasonication methods to remove oxytetracycline (OTC) from aqueous solutions. The prepared material was analyzed using powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The adsorption capacity of the NiFe2O4@g-C3N4 nanosorbent for OTC decontamination was studied using a batch experiment under various parameters. The adsorption capacity was notably increased to 1634 mg g−1 under fixed experimental conditions. The kinetic and isothermal analyses were conducted using several optimal pH and temperature models. The adsorption kinetics graphs aligned with the pseudo-second-order model, suggesting chemical adsorption via electrostatic interactions. The adsorption isotherm curves aligned more closely with the Langmuir model than the Temkin and Freundlich models, suggesting a monolayer adsorption mechanism. The adsorption mechanism was clearly elucidated using FTIR investigations. The results of the study indicate that NiFe2O4@g-C3N4 nanosorbent is a promising candidate for specific elimination of OTC on many different levels for the treatment of wastewater. [ABSTRACT FROM AUTHOR]

The abuse of antibiotics has caused severe environmental issues. Photocatalytic treatment technology has the advantages of high efficiency, strong effectiveness and no secondary pollution, which presents great potential for degrading or removing many kinds of environment pollutants. However, the intermediate products formed during the photocatalytic degradation process of antibiotics may possess greater toxicity than the antibiotics themselves, and the toxicity of most of these intermediates still remains unclear. Therefore, understanding the photocatalytic degradation pathways of antibiotics and obtaining qualitative and quantitative information about the main degradation products are of vital importance for the large-scale application of photocatalytic technology in the removal of antibiotics and other pollutants. Probe electrospray ionization mass spectrometry (PESI-MS) technology, adopting a solid probe as the electrospray ionization emitter, has the advantages of rapid response, low sample consumption, high salt tolerance, and strong resistance to suspended particles. These features make PESI-MS to be an ideal technique for direct analysis of complex systems, such as biological and chemical reactions. In this study, PESI-MS was used to perform continuous real-time in situ monitoring and analysis of the photocatalytic degradation of oxytetracycline (OTC), which photocatalyzed by TiO2 under UV irradiation for 160 min, with spectra collected at a resolution of 1 spectrum per second. The results showed that the intensity of protonated OTC ions decreases progressively during the reaction, and forms product ions at various stages of degradation. 35 Kinds of key degradation products are identified by high time-resolved spectra. Based on the changes in the extracted ion chromatograms (EIC) of these products, 7 major degradation products are screened out and 10 possible degradation pathways are proposed, two of which can lead to the degradation of OTC into lower molecular weight products. Although complete photocatalytic degradation of OTC is not achieved in the experimental conditions, the amount of degradation products observed in this study is significantly higher than those previously reported using various high performance liquid chromatography mass spectrometry (HPLC-MS). Furthermore, in the early stages of the photocatalytic process, products of combined ethyl radicals and ethoxy radicals are detected, which likely are contributed by the ethanol added intentionally in the reaction. The use of organic solvents to reduce solution surface tension during PESI operation at atmospheric pressure is inevitable. In the future, we aim to develop a high-pressure PESI ionization source to resolve this issue, which is expected to reveal a more accurate photocatalytic reaction mechanism and pathway. The findings of this study provide valuable data for understanding the kinetics of photocatalytic reactions and developing new photocatalysts, helping researchers gain a more comprehensive understanding of photocatalytic mechanisms.

Abstract The excessive presence of antibiotics such as Oxytetracycline (OTC) in the wastewater has increased health problems due to their toxic impact on the aquatic ecosystem. Therefore, their removal has become an important topic. This study aims to produce high surface area-activated carbon derived from low-cost and environmentally friendly barley lignocellulosic wastes to remove OTC from aqueous solutions. The synthesized barley wastes-activated carbon (BW-AC) was characterized using Fourier-Transform Infrared spectroscopy, Thermal Gravimetric Analysis, X-ray diffraction analysis, N2 adsorption/desorption isotherms, and Scanning Electron Microscopy. A Central Composite Design under the Response Surface Methodology (CCD-RSM) was applied to optimize the operational parameters (adsorbent dosage, pH, OTC initial concentration, and contact time) affecting the adsorption capacity as the response factor. The optimum condition of OTC adsorption by BW-AC was the adsorbent dosage of 16.25 mg, pH of 8.25, initial concentration of 62.50 mg/L, and contact time of 23.46 min. An analysis of variance (ANOVA) was performed to investigate the significance of the designed quadratic model and evaluate the parameters interactions. The linear regression coefficient (R2) of 0.975 shows a good correlation between predicted and actual results. The adsorption isotherms were used to determine the contaminant distribution over the adsorbent surface, and the equilibrium data was best described by the Freundlich isotherm due to the R2 value of 0.99 compared to other isotherms and β parameter of 0.23 in Redlich-Peterson equation. Moreover, the n value of 1.25 in Freundlich equation and E value of 0.31 in Dubinin–Radushkevich equation indicates a physical nature of adsorption process. According to the equations results, the maximum adsorption capacity of BW-AC for OTC removal was 500 mg/g, based on the Langmuir isotherm equation. In addition, the thermodynamic studies indicated an endothermic process based on the 0.31 value of ΔH° and spontaneous nature due to the negative amount of ΔG° within the temperature range of 288–318 K. Consequently, the prepared BW-AC can be deemed as a highly effective adsorbent with a large surface area, resulting in significant capacity for removing OTC. This synthesized BW-AC can serve as an environmentally friendly adsorbent for affordable wastewater treatment and is poised to make valuable contributions to future research in this field.

Abstract Tetracyclines family is considered as the first-line antibiotic drugs for food animals. Formulating bromhexine (BR) with oxytetracycline (OTC) improved the antibacterial activity of OTC, besides it is considered as a mucolytic agent. Four precise, rapid, and simple spectrophotometric methods were successfully developed for resolution of the overlapped spectra of OTC and BR in their pure form and in their pharmaceutical formulation. The proposed methods are absorption correction (AC), dual wavelength (DW), induced dual wavelength (IDW), and spectrum subtraction (SS) spectrophotometric methods. The developed methods were used for the determination of OTC and BR in the ranges of 2–50 µg/mL and 1–30 µg/mL, respectively for all methods. For (AC) and (SS) methods, OTC and BR were determined at 380 nm and 245.6 nm, respectively after spectral resolution steps. While for (DW) method, the absorbance difference between λ (271.8 –287.6 nm) and λ (245.6 –283.2 nm) were used for the determination of OTC and BR, in order. For IDW, it depended on using the absorbance difference between 271.8 nm and 245.6 nm as well as the equality factor (F) calculated for each drug at the selected wavelengths. In all methods, HCl was used as a solvent and they are validated according to ICH guidelines. Several green metric tools have been developed to evaluate the greenness of the analytical methods like National Environmental Methods Index (NEMI), Modified NEMI, Analytical Eco-scale, Green Analytical Procedure Index (GAPI) and Analytical GREEnness calculator (AGREE), and all ensured the low impact of the suggested approaches on health and environment. The proposed methods are highly selective, robust and precise. Additionally they are time and money effective and can be used in any analytical laboratory.

[Display omitted] • OTC was significantly removed in Cu0-F-MoS 2 /air system. • 1O 2 played crucial roles Cu0-F-MoS 2 /air system. • The Cu site on the surface of Cu0-F-MoS 2 absorbs and activates oxygen. • Cu0-F-MoS 2 has good cycling stability and the degradation efficiency of OTC still reaches 80% in five cycles. Molecular oxygen (O 2), a green oxidant, is applied in advanced oxidation processes, which represents one of the current focal points in water treatment research. However, achieving efficient and economical activation of O 2 remains a formidable challenge because of its spin-restricted nature. Herein, zero-valent copper (Cu0) modified molybdenum disulfide (MoS 2) materials were applied as O 2 activators to degrade organic pollutants. The results showed that Cu0-MoS 2 could significantly enhance the activation of O 2 and thus accelerate the removal of oxytetracycline (OTC). Notably, 90.0 % of OTC was eliminated within 20 min in the Cu0-F-MoS 2 (Cu0-Flower-MoS 2) /air system. Quenching experiments, XPS spectra, and DFT calculations confirmed •O 2 − and 1O 2 were pivotal reactive species, with both Mo and Cu playing essential roles. Specially, O 2 was activated by Cu0/Cu+ to generate •O 2 −, then •O 2 − was oxidized by Mo6+ of MoS 2 into 1O 2. This research offers an eco-friendly approach for eliminating organic substances by activating O 2. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the adsorption of Oxytetracycline (OTC) from pharmaceutical wastewater using a kappa carrageenan based hydrogel (KPB). The aim of the present study was to explore the potential of KPB for long-term pharmaceutical wastewater treatment. A sustainable adsorbent was developed to address oxytetracycline (OTC) contamination. The hydrogel’s structural and adsorption characteristics were examined using various techniques like Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), X-ray powder diffraction (XRD), and kinetic models. The results revealed considerable changes in the vibrational modes and adsorption bands of the hydrogel, suggesting the effective functionalization of Bentonite nano-clay. Kappa carrageenan based hydrogel achieved the maximum removal (98.5%) of OTC at concerntration of 40 mg/L, pH 8, cotact time of 140 min and adsorbent dose of 0.1 g (KPB-3). Adsorption of OTC increased up to 99% with increasing initial concentrations. The study achieved 95% adsorption capacity for OTC using a KPB film at a concentration of 20 mg/L and a 0.1 g adsorbent dose within 60 min. It also revealed that chemisorptions processes outperform physical adsorption. The Pseudo-Second-Order model, which emphasized the importance of chemical adsorption in the removal process, is better suited to represent the adsorption behavior. Excellent matches were found that R2 = 0.99 for KPB-3, R2 = 0.984 for KPB-2 and R2 = 0.989 for KPB-1 indicated strong chemical bonding interactions. Statisctical analysis (ANOVA) was performed using SPSS (version 25) and it was found that pH and concentration had significant influence on OTC adsorption by the hydrogel, with p-values less than 0.05. The study identified that a Kappa carrageenan-based hydrogel with bentonite nano-clay and polyvinyl alcohol (PVA) can efficiently remove OTC from pharmaceutical effluent, with a p-value of 0.054, but weak positive linear associations with pH, temperature, and contact time. This research contributed to sustainable wastewater treatment and environmental engineering.

Abstract The generic term “Gill disease” refers to a wide range of disorders that affect the gills and severely impact salmonid aquaculture systems worldwide. In rainbow trout freshwater aquaculture, various etiological agents causing gill diseases have been described, particularly Flavobacterium and Amoeba species, but research studies suggest a more complex and multifactorial aetiology. Here, a cohort of rainbow trout affected by gill disease is monitored both through standard laboratory techniques and 16S rRNA Next-Generation Sequencing (NGS) analysis during a natural disease outbreak and subsequent antibiotic treatment with Oxytetracycline. NGS results show a clear clustering of the samples between pre- and post-treatment based on the microbial community of the gills. Interestingly, the three main pathogenic bacteria species in rainbow trout (Yersinia ruckeri, Flavobacterium psychrophilum, and Flavobacterium branchiophilum) appear to be weak descriptors of the diversity between pre-treatment and post-treatment groups. In this study, the dynamics of the gill microbiome during the outbreak and subsequent treatment are far more complex than previously reported in the literature, and environmental factors seem of the utmost importance in determining gill disease. These findings present a potential novel perspective on the diagnosis and management of gill diseases, showing the limitations of conventional laboratory methodologies in elucidating the complexity of this disease in rainbow trout. To the authors’ knowledge, this work is the first to describe the microbiome of rainbow trout gills during a natural outbreak and subsequent antibiotic treatment. The results of this study suggest that NGS can play a critical role in the analysis and comprehension of gill pathology. Using NGS in future research is highly recommended to gain deeper insights into such diseases correlating gill’s microbiome with other possible cofactors and establish strong prevention guidelines.

Taking chicken manure containing antibiotic oxytetracycline (OTC) as the research object, nano-Fe2O3 with a concentration of 300 mg/kg TS and nano-C60 with a concentration of 100 mg/kg TS as carriers were used for a 55-day sequential batch mesophilic anaerobic digestion experiment. The gas production performance, chemical parameters, antibiotic content, enzyme concentration, and resistance gene changes during anaerobic digestion were analyzed to clarify the effect of nanoparticles on anaerobic systems containing antibiotic chicken manure and provide a reliable basis for pollution reduction capacity of livestock and poultry manure. The results showed that (1) adding nano-Fe2O3 and nano-C60 promoted anaerobic gas production in chicken manure with different concentrations of OTC. The cumulative gas production from days 1 to 10 was 2,234(T5) > 2,163(T4) > 1,445(T2) > 1,289(T3) > 1,220(T1) > 1,216(CK) mL. The cumulative gas production of T4 and T5 increased by 77.29 and 83.11%, respectively. The final cumulative gas production for each group was 3,712(CK), 3,993(T1), 4,344(T2), 4,447(T3), 4,671(T4), and 4,849(T5) mL. The final OTC residue concentrations were 15.25, 20.40, 56.56, 17.67, and 16.89 μg/L, with degradation rates of 98.31, 98.80, 98.29, 99.07, and 99.11% respectively; (2) antibiotic OTC increased the activities of dehydrogenase, amylase, protease, and urease, while adding nanoparticles increased the activities of dehydrogenase and amylase, with no significant impact on cellulase, urease, and protease activities; (3) antibiotic resistance gene (ARGs) of various types were found in groups T2, T4, and T5, with the multidrug resistance gene (ARGs)-Multidrug accounting for a high proportion of 33.54, 35.63, and 37.43%, respectively, while the proportions of the other four types MLS, tetracycline, glycopeptide, and peptide ranged from 8.18 to 12.98%.

The influence of talc microparticles on metabolism and morphology of S. rimosus at various initial organic nitrogen concentrations was investigated. The shake flask cultivations were conducted in the media with yeast extract (nitrogen source) concentration equal to 1 g YE L− 1 and 20 g YE L− 1. Two talc microparticle concentrations of 5 g TALC L− 1 and 10 g TALC L− 1 were tested in microparticle-enhanced cultivation (MPEC) runs. A high nitrogen concentration of 20 g YE L− 1 promoted the development of small agglomerates (pellets) of projected area lower than 105 µm2 and dispersed pseudohyphae. A low nitrogen concentration of 1 g YE L− 1 led to the limitation of S. rimosus growth and, in consequence, the development of the smaller number of large pseudohyphal agglomerates (pellets) of projected area higher than 105 µm2 compared to the culture containing a high amount of nitrogen source. In both cases talc microparticles were embedded into pellets and caused the decrease in their sizes. The lower amount of talc (5 g TALC L− 1) usually caused the weaker effect on S. rimosus morphology and metabolite production than the higher one. This correlation between the microparticles effect on morphology and metabolism of S. rimosus was especially noticeable in the biosynthesis of oxytetracycline, 2-acetyl-2-dicarboxamide oxytetracycline (ADOTC) and spinoxazine A. Compared to the control run, in MPEC their levels increased 4-fold, 5-fold and 1.6-fold respectively. The addition of talc also improved the production of 2-methylthio-cis-zeatin, lorneic acid J and milbemycin A3. [ABSTRACT FROM AUTHOR]

Oxytetracycline (OTC) is a widely employed antibiotic in veterinary treatment and in the prevention of infections, potentially leaving residues in animal-derived food products, such as milk, that are consumed by humans. Given the detrimental effects of prolonged human exposure to antibiotics, it has become imperative to develop precise and sensitive methods for monitoring the presence of OTC in food. Herein, we describe the development and results of a preliminary label-free electrochemical aptasensor with antifouling properties designed to detect OTC in milk samples. The sensor was realized by modifying a gold screen-printed electrode with α-lipoic acid–NHS and an amine-terminated aptamer. Different electrochemical techniques were used to study the steps of the fabrication process and to quantify OTC in the presence of the Fe(CN)64−/Fe(CN)63− redox couple The detectable range of concentrations satisfy the maximum residue limits set by the European Union, with an limit of detection (LOD) of 14 ng/mL in phosphate buffer (BP) and 10 ng/mL in the milk matrix, and a dynamic range of up to 500 ng/mL This study is a steppingstone towards the implementation of a sensitive monitoring method for OTC in dairy products. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the plasma pharmacokinetics of oxytetracycline (OTC) in rainbow trout (Oncorhynchus mykiss) of different body sizes. Methods: The research was carried out on three groups as small (30–50 g), medium (90–110 g) and large (185–215 g) body sizes at 8 ± 0.5 °C. OTC was administered orally at a dose of 60 mg/kg to all groups. Blood samples were taken at 19 different sampling times until the 384 h after oxytetracycline administration. The plasma concentrations of OTC were measured using high pressure liquid chromatography-ultraviolet and pharmacokinetic parameters were evaluated using non-compartmental analysis. Results: OTC was detected in small-body sized fish until the 336 h and in medium and large-body sized fish until the 384 h. The elimination half-life of OTC was 85.46, 87.24 and 86.98 h in the small, medium and large body size groups, respectively. The peak plasma concentration increased from 0.66 to 1.11 µg/mL, and the area under the plasma concentration-versus time curve from zero (0) h to infinity (∞) increased from 87.86 to 151.52 h*µg/mL, in tandem with the increase in fish body size. As fish body size increased, volume of distribution and total body clearance decreased. Conclusion: These results show that the pharmacokinetics of OTC vary depending on fish size. Therefore, there is a need to reveal the pharmacodynamic activity of OTC in rainbow trout of different body sizes. [ABSTRACT FROM AUTHOR]

Tetracyclines (TCs) are among the most widely used antibiotics worldwide for treating bacterial infections (both Gram-positive and Gram-negative) in humans and animals. In Brazil, chicken is one of the most produced and traded meats, with TCs being the primary antibiotics used in its production. This study applied two experimental designs to optimize the QuEChERS method for simultaneous quantitative analysis by HPLC–DAD of three TCs (tetracycline, chlortetracycline, and oxytetracycline) in chicken. The optimized conditions of the QuEChERS method for the preconcentration of TCs were 500 mg of sample, 1000 mg of Na2SO4, 700 mg of NaCl, 100 mg C18, 100 mg of PSA in 10 mL of the extracting solvent, vortex for 1 min, and centrifugation 4000 rpm for 5 min with a total run time of 10 min. LOQ values were lower than the MRL for all antibiotics established by ANVISA, precision in intra-day and inter-day ranged from 0.1 to 5.0%, and recovery ranged from 80 to 101%, greatly improving the work efficiency. The analytical method was applied to four commercial chicken breast samples and other proteins, one for beef and one for pork, of which no residues were found. The "GREEnness" of the optimized method demonstrated that the proposed approach made it possible to develop a "greener" method than traditional methods. [ABSTRACT FROM AUTHOR]

This study investigated the adsorption of Oxytetracycline (OTC) from pharmaceutical wastewater using a kappa carrageenan based hydrogel (KPB). The aim of the present study was to explore the potential of KPB for long-term pharmaceutical wastewater treatment. A sustainable adsorbent was developed to address oxytetracycline (OTC) contamination. The hydrogel's structural and adsorption characteristics were examined using various techniques like Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), X-ray powder diffraction (XRD), and kinetic models. The results revealed considerable changes in the vibrational modes and adsorption bands of the hydrogel, suggesting the effective functionalization of Bentonite nano-clay. Kappa carrageenan based hydrogel achieved the maximum removal (98.5%) of OTC at concerntration of 40 mg/L, pH 8, cotact time of 140 min and adsorbent dose of 0.1 g (KPB-3). Adsorption of OTC increased up to 99% with increasing initial concentrations. The study achieved 95% adsorption capacity for OTC using a KPB film at a concentration of 20 mg/L and a 0.1 g adsorbent dose within 60 min. It also revealed that chemisorptions processes outperform physical adsorption. The Pseudo-Second-Order model, which emphasized the importance of chemical adsorption in the removal process, is better suited to represent the adsorption behavior. Excellent matches were found that R2 = 0.99 for KPB-3, R2 = 0.984 for KPB-2 and R2 = 0.989 for KPB-1 indicated strong chemical bonding interactions. Statisctical analysis (ANOVA) was performed using SPSS (version 25) and it was found that pH and concentration had significant influence on OTC adsorption by the hydrogel, with p-values less than 0.05. The study identified that a Kappa carrageenan-based hydrogel with bentonite nano-clay and polyvinyl alcohol (PVA) can efficiently remove OTC from pharmaceutical effluent, with a p-value of 0.054, but weak positive linear associations with pH, temperature, and contact time. This research contributed to sustainable wastewater treatment and environmental engineering. [ABSTRACT FROM AUTHOR]

A ternary composite (KB/BMO-GO) consisting of graphene oxide, Bi 2 MoO 6 and crosslinked benzene polymer was prepared by solvothermal and in-situ deposition methods, which were used to promote the synergistic adsorption-photocatalytic degradation of the refractory pollutant oxytetracycline (OTC). A cycle involving the simultaneous adsorption and photocatalytic enhances the degradation performance of oxytetracycline. The 15% KB/BMO-GO sample exhibited the best synergistic adsorption-photocatalytic degradation performance, which has great potential in practical applications for low concentration refractory pollutants removal of water. [Display omitted] Antibiotics are refractory degradable organic pollutants that present a significant hazard to water environments. In this work, a ternary composite (KB/BMO-GO) comprising of graphene oxide (GO), Bi 2 MoO 6 (BMO), and a cross-linked benzene polymer (KB) was synthesized and applied to promote the synergistic adsorption-photocatalytic degradation of the refractory pollutant, oxytetracycline (OTC). The inclusion of GO and KB in the composite enhanced the OTC adsorption performance of the catalysts, and the construction of Z-scheme heterojunction promoted the photogenerated charge separation efficiency and broadened the range of light absorption, thereby enhancing the photocatalytic performance. Moreover, we compared the performance of catalysts loaded with different mass ratios of KB (x% KB/BMO-GO). Among them, the 15 % KB/BMO-GO catalyst sample had the best OTC degradation performance. Specifically, 15 % KB/BMO-GO could adsorb 69.7 % of OTC in 30 min, reaching an OTC degradation rate of 93.3 % under visible light irradiation. h+ and 1O 2 are the main active substances in the photocatalytic process. In addition, the catalysts are acid-alkali and salt-resistant, as well as good reusability. This study provides a valuable reference for the preparation of highly efficient photocatalysts for synergistic adsorption-photodegradation processes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oxytetracycline (OTC) is frequently detected in groundwater and soil, posing substantial risks to the subsurface environment via persistence, phytotoxicity, changing bacterial communities, and antibiotic resistance. In situ chemical oxidation (ISCO) is one of the best alternatives for removing OTC from groundwater. However, its feasibility has rarely been investigated using columns for which optimal conditions can be obtained for practical applications. Thus, a system consisting of oxygen-doped graphitic carbon nitride (OgCN) and peroxymonosulfate (PMS) (OgCN/PMS) was tested for OTC removal using continuous-flow experiments with columns packed with sand and glass beads (GBs). The sand column exhibited better adsorption and degradation of OTC than the GB column in pulse injection experiments, regardless of whether OgCN was packed. Additional experiments were performed using a column saturated with the OTC solution and another filled with deionized water to simulate ISCO, using GB as the medium, to evaluate the net OTC removal by catalytic oxidation, excluding adsorption. Performance improved with increased OgCN packing, PMS dosage, retention time, and pH. Anions slightly affected the performance due to scavenging and propagation of radicals. These findings indicate the high potential of OgCN/PMS for ISCO and the usefulness of column experiments in field applications. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in water sources is a significant concern due to their potential environmental impact and the risks to human health. In the present research, hierarchically mesoporous UiO-66 (HP-UiO-66) with a high surface area (1011 m2/g) and large pore volume was synthesized using the reflux method on the liter scale. The successful synthesis was confirmed by FT-IR, XRD, FESEM/EDS, N2-adsorption/desorption, and zeta potential techniques. The HP-UiO-66 was utilized to remove two large structure antibiotics, chlortetracycline hydrochloride (CTC), and oxytetracycline (OTC). Box Behnken design was used to investigate the factors affecting the removal process and the interactions between them. The maximum adsorption capacities for OTC and CTC antibiotics were 252.9 mg/g and 234.2 mg/g at 35 °C, respectively. The sum of the normalized error method was applied to the analysis of various error functions in the nonlinear fitting of equilibrium and kinetic data. The CTC and OTC adsorption kinetic followed a fractal-like pseudo-second-order model. The Langmuir isotherm fitted well to adsorption data. The results demonstrate that HP-UiO-66 can be used as a recyclable and efficient adsorbent for large molecule antibiotics removal. [ABSTRACT FROM AUTHOR]

Antibiotics are crucial in the control of bacterial infections on fish farms. However, the influence of licensed antibiotics on DNA damage, histological changes, and protein differentiation in some farmed fish species is unidentified. The current study aimed to investigate the effect of therapeutic (80 mg/kg body weight/day) and high doses (160 mg/kg body weight/day) of oxytetracycline (OTC) on some biological indices, protein differentiation, histological changes, and DNA damage in Oreochromis niloticus (n = 360; 40 ± 3.5 g) and the potential positive effects of dietary ascorbic acid (AA) and whether it is capable of reducing the deleterious impacts of OTC and working synergistically to increase fish disease resistance and decrease morbidity and mortality rates. In the current study, fish were fed diets with or without OTC (80 or 160 mg/kg body weight/day) and AA (100 mg/kg diet/day) for 28 days, followed by a bacterial stress test with two different virulent strains for 14 days. Treatments include CTR (control; without additives), AA, OTC80, OTC160, OTC80 + AA, and OTC160 + AA. The results revealed that the AA group had the best antioxidative (significant increase in SOD, CAT, and GPx) and immunomodulatory effects (an increase in IgM, nitroblue tetrazolium, and total leucocytic count). Furthermore, the hematological parameters, immune indices (NBT), and antioxidant enzymes were significantly reduced by OTC160 (p ≤ 0.05). The results also showed that OTC160 notably augmented the activity of liver (ALT, AST, and LDH) and kidney (creatinine and urea) damage markers (p ≤ 0.05). OTC160 revealed considerable hepatic and renal tissue damage and significantly higher hepatocyte DNA damage. Pathological changes and DNA damage were directly correlated to the dosage of OTC exposure, where they were more severe in OTC160. OTC80 showed insignificant changes in most parameters. Compared to CTR, the inclusion of AA in the O. niloticus diet significantly restored the biological indices, histological changes, and DNA damage in OTC-treated groups. The morbidity and mortality percentages after bacterial challenge were significantly lower in the OTC80 + AA group, followed by the OTC160 + AA group than in the CTR. These results corroborate the use of AA as a potent antioxidant and immune stimulant and a potential co-adjuvant to OTC in the diet of O. niloticus to reach optimal resistance to disease. [ABSTRACT FROM AUTHOR]

An LC–Orbitrap–HRMS method was developed and validated for the simultaneous determination of four tetracyclines—oxytetracycline (OTC), tetracycline (TC), doxycycline (DC), and chlortetracycline (CTC)—in milk. This method involves sample extraction with McIlvaine–EDTA buffer solution (pH 4) and solid-phase extraction (SPE) with Oasis HLB cartridges, followed by the evaporation of the extract and its reconstitution with a 14% methanol aqueous solution before injection into the instrumental system. This method has been validated in terms of linearity, sensitivity, selectivity, precision, and accuracy, in accordance with Commission Decision 2002/657/EC requirements. Compared to existing methods, this approach optimally combines a quantitative procedure for extracting analytes from the milk of different species, including sheep, bovines, and goats, with a very short LC–Orbitrap–HRMS instrumental analysis time (only 8 min), simultaneously ensuring high precision, sensitivity, and applicability as a rapid confirmation method in official food control laboratories. The proposed method was applied to determine the concentration levels of OTC in milk samples derived from healthy Sardinian sheep and those naturally infected with Streptococcus uberis, after the intramuscular administration of an antibiotic, in order to evaluate how much of the drug was "subtracted" during penetration from blood into milk, with a potential effect of reducing its therapeutic efficacy. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oxytetracycline (OTC) and ciprofloxacin (CIP) contamination have caused serious risks to human health, and modified biochar is considered as a potential adsorbent for their removal. The typical agricultural waste of cotton husk was used as the feedstock, then was combined with γ-Fe2O3 and ball milling to innovatively synthesize nano zero-valent iron (nZVI) supporting magnetic cotton hush-derived biochar (Fe2O3@BMBC) by reductive calcination. Fe2O3@BMBC performed excellent adsorption performance with a maximum adsorption capacity for OTC (266.7 mg·g−1) and CIP (83.36 mg·g−1), and its adsorption capacity was 1.6 and 2.3 times that of cotton husk biochar (BC). Characterization analysis showed that Fe2O3@BMBC contained abundant oxygenated functional groups (e.g., -OH, C = O and Fe–O) and its surface was covered by diverse iron oxides. The high magnetization sensitivity of Fe2O3@BMBC guaranteed that it was easily to be separated by a magnet. Oxygenated functional groups (e.g., -OH, C = O and Fe–O) participated in the adsorption process, and solution pH significantly affected the adsorption behaviour, and pseudo-second-order model and Freundlich model better fitting the kinetics and isotherms data. These results confirmed that π-π conjugation, H-bonding, Fe–O complexation and electrostatic interactions contributed to the greater adsorption capacity of Fe2O3@BMBC. Ethanol + ultrasound could efficiently regenerate the used Fe2O3@BMBC and maintain its sustainable adsorption performance for OTC and CIP. Additionally, Fe2O3@BMBC performed a good environmental security in a wide pH range (from 3 to 11) in view of the low leaching risk of Fe. Highlights: • Fe2O3@BMBC was synthesized from cotton hush and γ-Fe2O3 by reductive calcination and ball milling. • Fe2O3@BMBC showed the excellent adsorption performance for OTC and CIP. • Multiple physicochemical forces contributed to OTC and CIP removal by Fe2O3@BMBC. • Ethanol + ultrasound could efficiently regenerate the used Fe2O3@BMBC. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to remove Oxytetracycline (Oxy), one of the pharmaceutical wastes, with the powder of pine tree (Pinus nigra Arn.) needle waste (Pn-nw). Experimental data obtained from batch adsorption studies carried out at pH 5.0 ±0.5 and temperature of 23±2 0C were tested with Pseudo first order, Pseudo second order and Intraparticle diffusion kinetic models and Freundlich, Langmuir and Temkin isotherm models and also error functions (Error Sum of Squares (SSE), Sum of Absolute Errors (SAE) and Average relative errors (ARE)). Furthermore, to support the adsorption of Oxy onto Pn-nw's, the characterization of both raw and Oxy charged particles was done by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyses. The most appropriate kinetic model in the study was determined to be the Pseudo second order with an R2 value of 0.999 and the Freundlich isotherm model with an R2 value of 0.991. Additionally, the amount of Oxy removed per unit Pn-nw (qmax) was calculated as 30.35 mgOxy/gPn-nw. The results show that Pn-nw is a very promising and environmentally friendly adsorbent for Oxy removal. [ABSTRACT FROM AUTHOR]

The direct equalizing ray method was employed to design three groups of mixtures of oxytetracycline(OTC) and norfloxacin(NOR) with varying proportions(Group R1 had a higher proportion of OTC, while R2 had similar concentrations of both antibiotics, and R3 had a higher proportion of NOR).The effects of these mixtures on the content and properties of extracellular polymeric substances (EPS) in the biological denitrification process were investigated using an sequencing batch reactor activated sludge reactor (SBR). The results revealed that the removal rates of ammonia nitrogen(NH 3 -N) decreased in all three groups with the addition of antibiotics. As the antibiotic concentration increased, the EPS content decreased by 68.46%, 55.53%, and 65.03% in R1, R2, and R3, respectively. To understand the interaction mechanism of mixed antibiotics on EPS in activated sludge, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques were employed. The findings demonstrated significant effects of mixed antibiotics on functional groups such as C-O, C O, and C-O-C. Specifically, hydrogen bonding was found to be the primary influencing factor in the R1 ratio, while Π-Π conjugation played a major role in the R3 ratio. [Display omitted] • High-concentration mixture of OTC and NOR inhibitory nitrogen removal performance of SBR. • High-concentration mixture of OTC and NOR reduced the production of extracellular polymeric substances. • High proportion of OTC, the EPS characteristics are mainly affected by hydrogen bonding interactions. • High proportion of NOR, the EPS characteristics are mainly affected by hydrogen bonding interactions and π-π conjugation. [ABSTRACT FROM AUTHOR]

[Display omitted] In the work, Bi 2 WO 6 /C-TiO 2 photocatalyst was successfully synthesized for the first time by loading narrow bandgap semiconductor Bi 2 WO 6 on MOF-derived carboxyl modified TiO 2. The phase structure, morphology, photoelectric properties, surface chemical states and photocatalytic performance of the prepared photocatalysts were systematically investigated using various characterization tools. The degradation efficiency of oxytetracycline by 6BT Z-scheme heterojunction photocatalyst under visible light could reach 93.6 % within 100 min, which was related to the high light harvesting and effective separation and transfer of photo-generated carriers. Furthermore, the effects of various environmental factors in actual wastewater were further investigated, and the results showed that 6BT exhibited good adaptability, durability and resistance to interference. Unlike most works, the degradation system with a different single active species were designed and constructed based on their formation mechanism. In addition, for the first time, a positive study was conducted on the priority attack sites, intermediate products, and degradation pathways for the photocatalytic degradation of oxytetracycline by a single active species through HPLC-MS and Fukui index calculations. The toxicity changes of intermediate products produced in three different single active species oxidation systems were evaluated using toxicity assessment software tools (T.E.S.T.), Escherichia coli growth experiments, and wheat growth experiments. Among them, the intermediate products formed through O 2 – oxidation had the lowest toxicity and the main active sites it attacked were the 20C, 38O, 18C, 41O, and 55O atoms with high f+ values in the oxytetracycline molecular structure. This work provided the insight into the role of each active species in the degradation of antibiotics and offered new ideas for the design and synthesis of efficient and eco-friendly photocatalysts. [ABSTRACT FROM AUTHOR]

Tetracyclines are a class of commonly used four‐ringed antibiotics. A series of DNA aptamers were recently obtained using the capture‐SELEX (systematic evolution of ligands by exponential enrichment) method to bind to oxytetracycline, and one of the aptamers can bind to a few other tetracycline antibiotics as well. Upon binding to the aptamers, the intrinsic fluorescence of tetracycline antibiotics can be enhanced. At least 10 different DNA aptamers were isolated from the previous selection experiment. In this work, a systematic characterization of these ten aptamers was performed. Each of these aptamers shows a different degree of fluorescence enhancement ranging from around 1‐fold to over 20‐fold. Fluorescence enhancement was boosted in the presence of Mg2+. Isothermal titration calorimetry (ITC) studies were done and showed a great variety in dissociation constant (Kd) from 62 nM to 1.6 μM. Steady‐state fluorescence spectroscopy and fluorescence lifetime studies showed a correlation between fluorescence lifetime and degree of fluorescence enhancement. A few aptamers showed slow binding kinetics, although no correlation was found between the kinetics of fluorescence change and degree of fluorescence enhancement. This is the first study of ten different aptamers for the same target, providing fundamental insights into aptamer binding and bioanalytical applications. [ABSTRACT FROM AUTHOR]

Importance: Over the past decade, catfish farming has increased in Southeast Asia. However, there has been no existing for pharmacokinetic data in the hybrid catfish ( Clarias macrocephalus x C. gariepinus). Objective: This study was designed to evaluate the pharmacokinetic characteristics of oxytetracycline (OTC) in the hybrid catfish, following single intravascular (IV) or oral (PO) administration at a single dosage of 50 mg/kg body weight (BW). Methods: In total, 140 catfish (each about 100-120 g BW) were divided into two groups (n = 70). Blood samples (0.6-0.8 mL) were collected from ventral caudal vein at pre-assigned times up to 144 h (sparse samples design). OTC plasma concentrations were analyzed using high-performance liquid chromatography-photodiode array detector. Results: The pharmacokinetic parameter of OTC was evaluated using a non-compartment model. OTC plasma concentrations were detectable for up to 144 and 120 h after IV and PO, respectively. The elimination half-life value of OTC was long with slow clearance after IV administration in hybrid catfish. The average maximum concentration value of OTC was 2.72 µg/mL with a time at the maximum concentration of 8 h. The absolute PO bioavailability was low (2.47%). Conclusions and Relevance: These results showed that PO administration of OTC at a dosage of 50 mg/kg BW was unlikely to be effective for clinical use in catfish. The pharmacodynamic properties and clinical efficacy of OTC after multiple medicated feed are warranted. [ABSTRACT FROM AUTHOR]

Recently, many efforts have been dedicated to construct artificial catalysts with enzyme-like activity. However, it is still a big challenge to endow artificial catalysts with specific substrate selectivity. In this study, we developed a facile strategy to construct a MIL-53(Fe)-based nanocatalyst with designable selectivity in the degradation of oxytetracycline (OTC). Through the Fe–O–P conjunction, oxytetracycline aptamer (OA) can be easily anchored on MIL-53(Fe) to provide the specific site for OTC binding. We verified that the obtained MIL-53(Fe)-Apt nanocatalyst displayed enhanced catalytic ability in the degradation of OTC, whereas obvious suppression toward other substrate analogues. This performance therefore brings about an anticipated selectivity toward OTC. Moreover, we highlighted that the configuration of aptamers on MIL-53(Fe) can be modulated through varying conjunction mode. Structure–function analysis revealed that aptamer configuration affects the local concentration of substrate around catalytic site, which thus decides the catalytic performance toward OTC. This work presented a facile and promising strategy for developing artificial catalysts with designable selectivity. [ABSTRACT FROM AUTHOR]

Water-soluble and highly yellow fluorescent carbon dots were synthesized by using sucrose as a carbon source and phosphoric acid as a dehydrating agent. Instrumental techniques such as fourier transform infrared spectroscopy, ultraviolet absorption and fluorescence spectroscopy, and transmission electron microscopy have been employed to characterize the carbon dots. The results indicated that the synthesized carbon dots have spherical shape with mean diameter of 7 nm. The distribution of carbon dots is uniform which emit yellow fluorescence. Fourier transform infrared spectroscopy study revealed the presence of high amount of –OH groups on carbon dots surface. Oxytetracycline quenched the fluorescence of carbon dots via static quenching mechanism. The reduction in fluorescence intensity of carbon dots permitted to design a fluorometric assay for oxytetracycline. The calibration curve (change in fluorescence intensity vs. concentration of oxytetracycline) was linear in the concentration range of 1.0 μg/mL–10.0 μg/mL with a detection limit of 0.33 μg/mL and correlation coefficient of 0.9981. The method was tested to quantify the oxytetracycline in spiked wastewater, milk, and meat samples and gave satisfactory recoveries. [ABSTRACT FROM AUTHOR]

In the present study, the degradation of oxytetracycline (OTC) under ultraviolet (UV) light in the presence of ZnO catalyst was investigated, and optimum parameters for degradation efficiency were determined. Different pH values, ZnO dosages, reaction times, OTC concentrations, and UV lights were used in this study. The optimum conditions found were as follows: pH 4, ZnO 1 g L−1, reaction time 25 min, and OTC concentration 10 mg L−1. Degradation efficiency was 42.1%, 76%, 70.7%, and 61.7% for ZnO and photocatalytic (for UV‐A, UV‐B, and UV‐C) degradation at optimal conditions, respectively. The resulting products after the photocatalytic oxidation of OTC were determined in the study. To identify the toxicity of degradation products and OTC, the lowest LC 50 (50% lethal concentration) and EC 50 (50% effective concentration) values were found. The resulting ethanamine, 2‐(2,6‐dimethylphenoxy)‐N‐methyl‐ by‐products were observed to be more toxic than OTC. Furthermore, it was seen that isopropoxy carbamic acid, ethyl ester by‐products were formed, whose presence is environmentally risky for aquatic environments due to their low EC50 values. [ABSTRACT FROM AUTHOR]

Soil pollution from antibiotics has become increasingly severe, posing significant environmental and human health threats. Many soil organisms can survive and sustain their roles in maintaining soil ecosystems, even in polluted conditions. Exploring the life-sustaining mechanisms of these organisms in contaminated environments is scientifically significant. This study used Eisenia fetida as the test organism and antibiotics (oxytetracycline hydrochloride) as exogenous stress substances. Oxidative stress response experiments were conducted using the artificial soil method to examine the response of earthworms to oxidative stress. Additionally, 16S rRNA technology was employed to analyze the succession of microbial community structures inside and outside the earthworms. A screening canonical correlation analysis (SCCA) model was developed to investigate the relationship between microbial communities and earthworm oxidative stress system under oxytetracycline stress, revealing survival strategies in antibiotic-contaminated soil. The results showed that Proteobacteria and Bacteriodetes were the dominant phyla of microbial communities in earthworms under oxytetracycline stress, while Proteobacteria and Firmicutes were dominant bacterial phyla in soil. Bacteriodetes and Firmicutes in earthworms worked synergistically with catalase (CAT) and glutathione peroxidase (GPX) in oxidative stress responses. In soil, Actinobacteria, Verrucomicrobia, and Spirochaeta synergistically resisted oxytetracycline stress alongside peroxidase (POD) and glutathione S-transferase (GST). Earthworm mucus played a crucial role in this synergistic resistance. These findings provide a scientific and experimental basis for assessing the ecological safety risks of antibiotic-contaminated soil.

Streptomycin (Str) and oxytetracycline (Otc) are widely used antibiotics to manage bacterial diseases in citrus and other crops. However, their impacts on the rhizosphere bacterial assembly and plant physiology are poorly understood. The aim of this study was to examine the effects of Str and Otc on the physiology (assimilation, transpiration rate, intracellular CO2, and stomatal conductance to water vapor), rhizosphere bacterial assemblages (16S rRNA gene high-throughput amplicon sequencing), and rhizosphere metabolite profiles in healthy Citrus reticulata trees. The results indicated a reduction in photosynthesis after Str and Otc treatments, whereas CO2 outflow stayed constant. Both antibiotics decreased the culturable numbers of bacteria. Analysis of the microbiome showed changes in relative abundance of bacterial groups, specifically Pseudomonas, Agrobacterium, and Streptomyces, in response to the antibiotics. Metabolite profiles changed in streptomycin- and oxytetracycline-treated citrus plants suggesting response to microbe targets or induction of stress responses. This study advances knowledge of antibiotic-driven effects on the rhizosphere microbiome, rhizosphere metabolome, and plant physiology, which is essential for managing plant diseases while safeguarding rhizosphere ecology and long-term plant health.

The study assessed the efficiency of in-vitro oxytetracycline (OTC) exposure on antimicrobial resistance (AMR) development in aquatic bacteria. Aeromonas hydrophila ATCC 49140 and Edwardsiella tarda ATCC 15947 were serially passaged to OTC for short and long durations. Short duration OTC exposure (30 min) at 0, 0.097 (0.25× Minimum Inhibitory Concentration: MIC), 0.195 (0.5× MIC) and 0.39 µg mL−1 (1× MIC) elicited high mutation rate in A. hydrophila (10−4) and E. tarda (10−2). Serial passage exposure to inhibitory concentration of OTC (0.39 µg mL−1) reduced the zone of inhibition of nitrofurantoin (NIT) for A. hydrophila and of tetracycline, NIT and gentamicin for E. tarda to a clinically significant level. The upsurge in MICs of OTC was 4-folds (1.56 µg mL−1) and 8-folds (3.12 µg mL−1) in A. hydrophila and E. tarda, respectively during serial passage exposure to 0.097, 0.195 and 0.39 µg mL−1 OTC. OTC exposure also increased the MICs of biocide triclosan (TCS) >4-folds (>100 µg mL−1) in A. hydrophila without any concentration-dependent pattern. This study shows that environmental OTC levels can drive bacterial mutation and AMR, potentially leading to cross-resistance to biocides like TCS. Reducing OTC use and improving disposal could help limit AMR spread through better antimicrobial management.

The abuse of oxytetracycline (OTC) leaves serious environmental residues and triggers accumulation in organisms, constituting a threat to human health. Constructing an effective platform based on dual-functional materials for monitoring and removing OTC residues is a preferable solution. Herein, we proposed a novel composite material by doping carbon dots (CDs) into melamine–formaldehyde microsphere (MFM) through a one-pot method and named CDs@MFM, which inherited the fluorescence property of CDs and porous structure of MFM simultaneously. CDs@MFM demonstrated dual functions for the detection and removal of OTC concurrently within a few minutes, with its performance compared in detail with bare CDs and MFM as controls. By virtue of the pre-enrichment effect attributed to its porous structure, CDs@MFM exhibited a lower detection limit for OTC than bare CDs (0.027 mg/L vs 0.067 mg/L) and a higher adsorption capacity than MFM (73.01 mg/g vs 68.76 mg/g) resulting from more affiliated functional groups available for OTC provided by the CDs. Overall, CDs@MFM has proven to be an efficient and convenient candidate capable of monitoring and removing OTC synchronously, and this work offers an avenue for the design of dual-functional materials in the field of environmental science.

BackgroundTilapia is a primary aquaculture fish in Thailand, but little is known about the occurrence of antimicrobial resistance (AMR) in Aeromonas hydrophila, Salmonella spp., and Vibrio cholerae colonizing healthy tilapia intended for human consumption and the co-occurrence of these AMR bacteria in the cultivation water.MethodsThis study determined the phenotype and genotype of AMR, extended-spectrum β-lactamase (ESBL) production, and virulence factors of A. hydrophila, Salmonella spp., and V. cholerae isolated from hybrid red tilapia and cultivation water in Thailand. Standard culture methods such as USFDA's BAM or ISO procedures were used for the original isolation, with all isolates confirmed by biochemical tests, serotyping, and species-specific gene detection based on PCR.ResultsA total of 278 isolates consisting of 15 A. hydrophila, 188 Salmonella spp., and 75 V. cholerae isolates were retrieved from a previous study. All isolates of A. hydrophila and Salmonella isolates were resistance to at least one antimicrobial, with 26.7% and 72.3% of the isolates being multidrug resistant (MDR), respectively. All A. hydrophila isolates were resistant to ampicillin (100%), followed by oxytetracycline (26.7%), tetracycline (26.7%), trimethoprim (26.7%), and oxolinic acid (20.0%). The predominant resistance genes in A. hydrophila were mcr-3 (20.0%), followed by 13.3% of isolates having floR, qnrS, sul1, sul2, and dfrA1. Salmonella isolates also exhibited a high prevalence of resistance to ampicillin (79.3%), oxolinic acid (75.5%), oxytetracycline (71.8%), chloramphenicol (62.8%), and florfenicol (55.3%). The most common resistance genes in these Salmonella isolates were qnrS (65.4%), tetA (64.9%), bla TEM (63.8%), and floR (55.9%). All V. cholerae isolates were susceptible to all antimicrobials tested, while the most common resistance gene was sul1 (12.0%). One isolate of A. hydrophila was positive for int1, while all isolates of Salmonella and V. cholerae isolates were negative for integrons and int SXT. None of the bacterial isolates in this study were producing ESBL. The occurrence of mcr-3 (20.0%) in these isolates from tilapia aquaculture may signify a serious occupational and consumer health risk given that colistin is a last resort antimicrobial for treatment of Gram-negative bacteria infections.ConclusionsFindings from this study on AMR bacteria in hybrid red tilapia suggest that aquaculture as practiced in Thailand can select for ubiquitous AMR pathogens, mobile genetic elements, and an emerging reservoir of mcr and colistin-resistant bacteria. Resistant and pathogenic bacteria, such as resistance to ampicillin and tetracycline, or MDR Salmonella circulating in aquaculture, together highlight the public health concerns and foodborne risks of zoonotic pathogens in humans from cultured freshwater fish.

Introduction: The administration of antibiotics can expose the digestive microbiota of humans and animals to sub-inhibitory concentrations, potentially favouring the selection of resistant bacteria. The minimal selective concentration (MSC) is a key indicator to understand this process. The MSC is defined as the lowest concentration of an antibiotic that promotes the growth of a resistant strain over a susceptible isogenic strain. It represents the lower limit of the sub-minimal inhibitory concentration (MIC) selective window, where resistant mutants can be selected. Previous studies focused on determining the MSC under standard culture conditions, whereas our research aimed to determine the MSC in a model that approximates in vivo conditions. Methods: We investigated the MSC of oxytetracycline (OTC) in Mueller-Hinton broth (MHB) and sterilised intestinal contents (SIC) from the jejunum, caecum and rectum (faeces) of pigs, using two isogenic strains of Escherichia coli (one susceptible and one resistant to OTC). Additionally, the MIC of OTC against the susceptible strain was determined to assess the upper limit of the sub-MIC selective window. Results: Our study took a novel approach, and the results indicated that MIC and MSC values were lower in MHB than in SIC. In the latter, these values varied depending on the intestinal segment, with distal compartments exhibiting higher MIC and MSC values. Moreover, the sub-MIC selective window of OTC in SIC narrowed from the jejunum to the rectum, with a significantly closer MSC to MIC in faecal SIC. Discussion: The results suggest that OTC binds to digestive contents, reducing the fraction of free OTC. However, binding alone does not fully explain our results, and interactions between bacteria and intestinal contents may play a role. Furthermore, our findings provide initial estimates of low concentrations facilitating resistance selection in the gut. Finally, this research enhances the understanding of antimicrobial resistance selection, emphasising the intricate interplay between antibiotics and intestinal content composition in assessing the risk of resistance development in the gut. [ABSTRACT FROM AUTHOR]

The present study used CeO2-Co3O4 quantum dots@porous carbon/multiwalled carbon nanotube (CeO2-Co3O4 QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO2-Co3O4 QDs@PC/MWCNT/GE, with a peak current density of 1.276 mA/cm2. Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO2-Co3O4 QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm2, almost seven times that of the bare graphite electrode (0.079 cm2). The results showed that the CeO2-Co3O4 QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10−8 to 2.04 × 10−7 M (i.e., 0.005–0.1 ppm) and 1.007 × 10−6 to 1.209 × 10−4 M (i.e., 0.5–60 ppm). The limit of detection and limit of quantification were 1.23 nM (0.61 ppb) and 4.09 nM (2.03 ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7 weeks. This method provides a new way to prepare electrochemical sensors for OTC detection. [ABSTRACT FROM AUTHOR]