Concentrations Of Norfloxacin Research Articles

Conserved Evolutionary Trajectory Can Be Perturbed to Prevent Resistance Evolution under Norfloxacin Pressure by Forcing Mycobacterium smegmatis on Alternate Evolutionary Paths.

Antibiotic resistance is a pressing health issue, with the emergence of resistance in bacteria outcompeting the discovery of novel drug candidates. While many studies have used Adaptive Laboratory Evolution (ALE) to understand the determinants of resistance, the influence of the drug dosing profile on the evolutionary trajectory remains understudied. In this study, we employed ALE on Mycobacterium smegmatis exposed to various concentrations of Norfloxacin using both cyclic constant and stepwise increasing drug dosages to examine their impact on the resistance mechanisms selected. Mutations in an efflux pump regulator, LfrR, were found in all of the evolved populations irrespective of the drug profile and population bottleneck, indicating a conserved efflux-based resistance mechanism. This mutation appeared early in the evolutionary trajectory, providing low-level resistance when present alone, with a further increase in resistance resulting from successive accumulation of other mutations. Notably, drug target mutations, similar to those observed in clinical isolates, were only seen above a threshold of greater than 4× the minimum inhibitory concentration (MIC). A combination of three mutations in the genes, lfrR, MSMEG_1959, and MSMEG_5045, was conserved across multiple lineages, leading to high-level resistance and preceding the appearance of drug target mutations. Interestingly, in populations evolved from parental strains lacking the lfrA efflux pump, the primary target of the lfrR regulator, no lfrR gene mutations are selected. Furthermore, evolutional trajectories originating from the ΔlfrA strain displayed early arrest in some lineages and the absence of target gene mutations in those that evolved, albeit delayed. Thus, blocking or inhibiting the expression of efflux pumps can arrest or delay the fixation of drug target mutations, potentially limiting the maximum attainable resistance levels.

Norfloxacin affects inorganic nitrogen compound transformation in tailwater containing Corbicula fluminea

The Asian clam, Corbicula fluminea, commonly used in engineered wetlands receiving tailwater, affects nitrogen compound transformation in water. This study investigates how a commonly observed antibiotic in tailwater, norfloxacin, impact nitrogen compound transformation in tailwater containing C. fluminea. The clam was exposed to artificial tailwater with norfloxacin (0, 0.2, 20, and 2000 μg/L) for 15 days. Water properties, C. fluminea ecotoxicity responses, microorganism composition and nitrification- or denitrification-related enzyme activities were measured. Results revealed norfloxacin-induced increases and reductions in tailwater NH4+ and NO2− concentrations, respectively, along with antioxidant system inhibition, organ histopathological damage and disruption of water filtering and digestion system. Microorganism composition, especially biodiversity indices, varied with medium (clam organs and exposure water) and norfloxacin concentrations. Norfloxacin reduced NO2− content by lowering the ratio between microbial nitrifying enzyme (decreased hydroxylamine oxidoreductase and nitrite oxidoreductase activity) and denitrifying enzyme (increased nitrate reductase and nitrite reductase activity) in tailwater. Elevated NH4+ content resulted from upregulated ammonification and inhibited nitrification of microorganisms in tailwater, as well as increased ammonia emission from C. fluminea due to organ damage and metabolic disruption of the digestion system. Overall, this study offers insights into using benthic organisms to treat tailwater with antibiotic residues, especially regarding nitrogen treatment. Environmental ImplicationsNorfloxacin, a common antibiotic found in surface water, poses substantial environmental hazards. High concentrations of norfloxacin persist in wastewater treatment plant tailwater due to limited water purification capacity. This research examines the impact of norfloxacin residues in tailwater on Corbicula fluminea, a bivalve often found in engineered wetlands that receive such effluents. Specifically, this study investigates two environmental issues: the potential ecotoxicity of norfloxacin and its adverse effects on the ecological role of C. fluminea in regulating the transformation of inorganic nitrogen compounds.

S-scheme BiOBr/Bi2WO6 with oxygen vacancies for synergistic photodegradation and hydrogen generation: Mechanisms insight and DFT calculations

An S-type heterojunction photocatalyst Bi2WO6/BiOBr (BWO/BiOBr) with an interlaced band structure and abundant oxygen vacancies (Ov) was synthesized using a hydrothermal method and high-temperature calcination. The surface was modified with carbon quantum dots (CQDs) to create a 0D/2D/2D structure. The resulting photocatalyst exhibited superior performance, with a degradation rate for Norfloxacin (NOR) antibiotics surpassing Bi2WO6 with oxygen vacancies (BWO-Ov) and BiOBr by 6.55 and 3.96 times, respectively. Notably, it achieved a high hydrogen generation rate of 459.49 μmol·g−1·h−1 under visible light. The enhanced carrier transfer and solar absorption were attributed to the synergistic effect of CQDs and S-type heterojunctions. The face-to-face 2D/2D structure provided abundant reaction sites. The influence of initial NOR concentration and photocatalyst dosage on photocatalytic activity was investigated in our study. Incorporating CQDs improved solar absorption, as confirmed by NOR degradation under various wavelengths. Electron spin resonance (ESR) analysis indicated the generation of reactive oxygen species. Density functional theory (DFT) calculations and characterization explored charge transfer mechanisms and degradation pathways. These findings contribute to the design of efficient S-type heterogeneous photocatalysts for sustainable energy and environmental applications.

Enhanced norfloxacin removal from sludge by dielectric barrier discharge plasma synthesis with Fe3O4/g-C3N4

The excess sludge adsorbed with antibiotics poses a huge threat to the ecological environment and human health, and the removal of antibiotics from sludge was focused on. The dielectric barrier discharge (DBD) coupled with Fe3O4/g-C3N4 to degrade norfloxacin (NOR) in excess sludge of wastewater treatment plant was studied, where Fe3O4/g-C3N4 was prepared through high-temperature calcination. At an input voltage of 90 V and at a current of 0.5 A, NOR concentration of 100 mg/kg total suspended solids (TSS), Fe3O4/g-C3N4 dosing of 100 mg/g TSS, and pH 6.94, the NOR degradation efficiency was 89.2 %, the energy yield was 1.98 mg/kWh, and the synergy factor of DBD with Fe3O4/g-C3N4 was 1.85. In this system, •OH, •O2−, h+, H2O2 and O3 played an important role in the degradation of NOR in sludge, and Fe3O4/g-C3N4 induced Fenton-like reactions using H2O2 generated by DBD and facilitated photocatalytic reactions with ultraviolet and visible light. There was a positive correlation between the NOR degradation efficiency and the sludge disintegration, and the sludge disintegration process released NOR from the solid phase to the liquid phase. Three possible degradation pathways and the toxicity evaluation of the intermediates were proposed based on the results of DFT and HPLC-MS. Additionally, the DBD/Fe3O4/g-C3N4 system improved the sludge disintegration and dewatering performance effectively.

Effects of two typical quinolone antibiotics in the marine environment on Skeletonema costatum

This study investigated the effects of levofloxacin (LEV) and norfloxacin (NOR) on Skeletonema costatum, focusing on cell growth, chlorophyll a (Chla) content, maximal quantum yield of PSII (Fv/Fm), protein content, enzyme activities of superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GSH-PX), and the membrane lipid peroxidation product malondialdehyde (MDA) content were conducted to analyze the responses of S. costatum under LEV and NOR exposure. Cell growth, Chla content, Fv/Fm, protein content, enzyme activities, and MDA content were assessed to elucidate physiological changes. Both LEV and NOR inhibited S. costatum growth, except for 10 mg/L NOR, which promoted growth. Algal cells exhibited higher sensitivity to LEV, with 96h-IC50 values of 14.770 mg/L for LEV and 44.250 mg/L for NOR. Low NOR concentration (10 mg/L) increased Chla content, while high antibiotic concentrations (>20 mg/L for LEV, >100 mg/L for NOR) decreased Chla content and Fv/Fm, indicating an impact on photosynthesis. Elevated LEV and NOR levels reduced protein and MDA content but increased GR, SOD, and GSH activities, indicating induced oxidative stress. The study provides a comprehensive analysis of LEV and NOR effects on marine microalgae growth and underlying physiological mechanisms, shedding light on potential ecological risks posed by antibiotics in marine ecosystems.

Inhibition of norfloxacin on fermentative hydrogen production: Performance evaluation and metagenomic analysis

Toxic chemicals can inhibit the dark fermentation process for renewable biohydrogen production. Norfloxacin (NOR), a typical antibiotic, is present in various feedstocks of dark fermentation, which has excellent antibacterial properties. It is hypothesized that NOR could cause adverse effects on fermentative hydrogen production, while current understanding of this subject is scare. This study investigated the potential inhibitory effect of NOR on dark hydrogen fermentation, and explored the underlying mechanisms from the perspectives of bacterial community structure and functional gene abundance. The results showed that NOR significantly reduced the hydrogen-producing capacity upon exposure to concentrations exceeding 10 mg/L. The hydrogen yield decreased from 1.56 to 0.27 H2/mol-glucose at NOR concentrations of 50 mg/L. NOR also prolonged the hydrogen-producing lag period. Bacterial community analysis revealed that NOR reduced the abundance of high-yielding H2-generating bacteria, such as Clostridium sp., while increasing the abundance of H2-consuming bacteria (e.g. Enterococcus sp.). Metagenomic analysis further indicated that crucial genes involved in glycolysis (e.g. HK, tal-pgi, pfk and PK) and hydrogen formation (e.g. por and E1.12.7.2) were remarkably downregulated under NOR exposure, essentially causing the inhibition of hydrogen production. This study contributes to a better understanding of how antibiotics inhibit dark hydrogen fermentation and provides a theoretical basis for reducing potential inhibitory effects.

Fluorescence turn off-on continuous response of dual lanthanide metal organic frameworks for selective detecting fluoroquinolone antibiotics

Eu3+ and Tb3+ as central ions and 1,4-phthalic acid (H2BDC) as ligand, a dual lanthanide metal-organic framework, Eu-Tb(BDC), was synthesized by co-precipitation method. The products performed stable crystal structure and adjustable fluorescence color. Eu0.15Tb2.85 (BDC) 3.0 was selected as an optimized probe to detect norfloxacin (NFX) in urine, and the fluorescence color was found to transfer from bright yellow to dark cyan and then to strong green with increasing NFX concentration. Mechanism analysis revealed that NFX with low concentration (10−6-10−3 M) stimulated light competition with BDC ligand due to internal filtration effect (IFE), resulting in the gradual fluorescence shutdown of Eu3+and Tb3+. While further increasing concentration of NFX to 10−3-10−2 M, the antibiotic molecules coordinated with lanthanide ions and transitioned their role from competitor to assistant. Where the energy transfer due to antenna effect overwhelmed IFE, the exciting light energy were retransferred to Eu3+ or Tb3+, and the probe's fluorescence restored. Generally, the Eu-Tb(BDC) probe performed fluorescence turn off-on response to norfloxacin with continuous concentration changing. Additionally, when detecting other fluoroquinolone antibiotics, the fluorescence of Eu0.15Tb2.85(BDC)3.0 changed from bright yellow to bright blue and eventually to dark red, which was attributed to the different coordination degrees of various antibiotic molecule with Tb3+ and Eu3+. It can be used to distinguish norfloxacin from other fluoroquinolone antibiotics.

Magnetic catalysts of MnFe2O4-AC activated peroxydisulfate for high-efficient treatment of norfloxacin wastewater

Norfloxacin (NOR) wastewater with a significant corrosive effect on human tissues requires deep treatment before discharge. Peroxydisulfate (PDS) activation with catalysts is an effective advanced method for wastewater treatment, and the key to its success lies in the design, synthesis, and preparation of efficient, stable, and easily prepared catalysts. In this study, magnetic catalysts of MnFe2O4-AC were synthesized through the hydrothermal method as the basic material activated PDS. The crystal structures were characterized using various techniques, including SEM-EDS, XRD, FT-IR, and XPS. The high magnetic properties of the prepared catalysts made them easily recoverable after wastewater treatment. In addition, the study investigated the effects of operating conditions on the treatment of NOR wastewater within the Electrochemistry/MnFe2O4-AC/PDS (EC/MnFe2O4-AC/PDS) system. Under the optimal conditions of current intensity of 0.15 A, catalyst dosage of 0.100 g/L, PDS concentration of 10 mmol/L, and NOR concentration of 5 mg/L, the removal rate of NOR was 97.33 %. The increased specific surface area of MnFe2O4-AC catalysts, when compared to MnFe2O4 catalysts, benefited the activation of PDS. MnFe2O4-AC catalysts showed a good stability in activating PDS for NOR wastewater treatment without causing secondary pollution in repeated use experiments. Finally, the NOR degradation was attributed to both the generation of free radicals (SO4•- and ‧OH radicals) and non-radical processes (electrode oxidation).

Effects of two pharmaceuticals: Doxycycline and norfloxacin on plant and animal organisms living in the freshwater

The main reason for the appearance of pharmaceutical compounds in the aquatic environment is their regular excretion by humans and animals in an unchanged form or slightly metabolized. Pharmaceuticals limit the habitable living environment for aquatic organisms, because they can be toxic not only to bacteria but also to non-target organisms. Plants of the Lemnoideae subfamily and crustaceans Daphniindae family are widely used as bioindicators in freshwater environmental risk assessments. This study aimed to use biotests (Lemna test and Daphtoxkit) to determine the effect of two pharmaceuticals: antibiotic – Doxycycline (DOX) and semi-synthetic chemotherapeutic drug – Norfloxacin (NOR) on plants Lemna minor and crustaceans Daphnia magna. Standard Lemna test was extended to include pharmaceutical effects on plant chlorophyll content (LCC) and fluorescence (Fo, Fm, and Fv/Fm), and the confirmation of drug toxicity was the biotest Daphtoxkit assessing the immobilization (IM) of organisms. Studies have shown that DOX was more toxic than NOR on tested aquatic organisms: plants and crustaceans. The lowest observed effect concentration (EC20) of DOX and NOR reduced by 20 % LCC and Iy of L. minor was 2.14 and 8.11 mg × L−1, respectively. The LCC was an early and sensitive indicator of the phytotoxic effects of DOX in L. minor before morphological changes were observed. Confirmation of drug toxicity was the Daphtoxkit. The EC20 (180. min) of DOX and NOR, IM of daphnia by 20 % was 117.18 and 215.42 mg × L−1, respectively. In conclusion, DOX and NOR in aquatic environments may have significant implications for tested organisms and their ecosystems.

Electrophoretic Mobility Assay to Separate Supercoiled, Catenated, and Knotted DNA Molecules.

Two-dimensional (2D) agarose gel electrophoresis is the method of choice to analyze DNA topology. The possibility to use E. coli strains with different genetic backgrounds in combination with nicking enzymes and different concentrations of norfloxacin improves the resolution of 2D gels to study the electrophoretic behavior of three different families of DNA topoisomers: supercoiled DNA molecules, post-replicative catenanes, and knotted DNA molecules. Here, we describe the materials and procedures required to optimize their separation by 2D gels. Understanding the differences in their electrophoretic behavior can help explain some important physical characteristics of these different types of DNA topoisomers. Key features • Preparative method to enrich DNA samples of supercoiled, catenated, and knotted families of topoisomers, later analyzed by 2D gels (or other techniques, e.g., microscopy). • 2D gels facilitate the separation of the topoisomers of any given circular DNA molecule. • Separation of DNA molecules with the same molecular masses but different shapes can be optimized by modifying the conditions of 2D gels. • Evaluating the roles of electric field and agarose concentration on the electrophoretic mobility of DNA topoisomers sheds light on their physical characteristics.

Simultaneous photoactivation of a fluoroquinolone antibiotic and nitric oxide with fluorescence reporting.

The achievement of smart pharmaceuticals whose bioactivity can be spatiotemporally controlled by light stimuli is known as photopharmacology, an emerging area aimed at improving the therapeutic outcome and minimizing side effects. This is especially attractive for antibiotics, for which the inevitable development of multidrug resistance and the dwindling of new clinically approved drugs represent the main drawbacks. Here, we show that nitrosation of the fluoroquinolone norfloxacin (NF), a broad-spectrum antibiotic, leads to the nitrosated bioconjugate NF-NO, which is inactive at the typical minimum inhibitory concentration of NF. Irradiation of NF-NO with visible blue light triggers the simultaneous release of NF and nitric oxide (NO). The photouncaging process is accompanied by the revival of the typical fluorescence emission of NF, quenched in NF-NO, which acts as an optical reporter. This permits the real-time monitoring of the photouncaging process, even within bacteria cells where antibacterial activity is switched on exclusively upon light irradiation. The mechanism of photorelease seems to occur through a two-step hopping electron transfer mediated by the lowest triplet state of NF-NO and the phosphate buffer ions or aminoacids such as tyrosine. Considering the well-known role of NO as an "unconventional" antibacterial, the NF-NO conjugate may represent a potential bimodal antibacterial weapon activatable on demand with high spatio-temporal control.

Sensitive visual detection of norfloxacin in water by smartphone assisted colorimetric method based on peroxidase-like active cobalt-doped Fe3O4 nanozyme

Norfloxacin is widely used owing to its strong bactericidal effect on Gram-negative bacteria. However, the residual norfloxacin in the environment can be biomagnified via food chain and may damage the human liver and delay the bone development of minors. Present work described a reliable and sensitive smartphone colorimetric sensing system based on cobalt-doped Fe3O4 magnetic nanoparticles (Co-Fe3O4 MNPs) for the visual detection of norfloxacin. Compared with Fe3O4, Co-Fe3O4 MNPs earned more remarkably peroxidase-like activity and TMB (colorless) was rapidly oxidized to oxTMB (blue) with the presence of H2O2. Interestingly, the addition of low concentration of norfloxacin can accelerate the color reaction process of TMB, and blue deepening of the solution can be observed with the naked eye. However, after adding high concentration of norfloxacin, the activity of nanozyme was inhibited, resulting in the gradual fading of the solution. Based on this principle, a colorimetric sensor integrated with smartphone RGB mode was established. The visual sensor exhibited good linearity for norfloxacin monitoring in the range of 0.13-2.51 µmol/L and 17.5-100 µmol/L. The limit of visual detection was 0.08 µmol/L. In the actual water sample analysis, the spiked recoveries of norfloxacin were over the range of 95.7%-104.7 %. These results demonstrated that the visual sensor was a convenient and fast method for the efficient and accurate detection of norfloxacin in water, which may have broad application prospect.

Facile synthesis of oxygen-deficient BiOBrxCl1−x solid solutions for efficient photocatalytic degradation of organic pollutants

In this study, a series of oxygen-deficient BiOBrxCl1−x (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid solution photocatalysts by the microwave hydrothermal method. By changing the Br/Cl molar ratio, the light absorption edge of BiOBrxCl1−x was effectively red-shifted from 345 to 430 nm. The performance of BiOBr0.3Cl0.7 solid solution catalyst showed the best photocatalytic duty for the degradation of norfloxacin (NOR) and methyl orange (MO). The degradation rate of NOR reached 90.2% within 50 min (catalyst dosage: 20 mg), whereas that of MO reached 82.7% within 30 min (catalyst dosage: 5 mg). Environmental factors affecting the degradation of NOR by BiOBr0.3Cl0.7 (such as pH, type of inorganic anions, amount of catalyst, and concentration of NOR) were discussed in detail. The presence of oxygen vacancies (OVs) was confirmed by electron spin resonance (ESR) experiments. Furthermore, free radical capture and ESR experiments identified the main active free radicals involved in the degradation of NOR over BiOBr0.3Cl0.7. Finally, a possible photocatalytic degradation mechanism was proposed.

Design and construction of a novel immobilized Z-scheme-Type II-heterojunction ZnO/ZnCo2O4–Co3O4|Co photocatalyst composite film for efficient norfloxacin degradation with simultaneous hydrogen evolution

The Z-scheme-Type II-heterojunction ZnO/ZnCo2O4–Co3O4 photocatalyst composite film (PCF) was prepared on the cobalt foil by using spin-coating and incomplete solid-state chemical reaction method, which solves the problems that the powder photocatalyst is difficult to recover and reuse and realizes the separation of CO2 and H2. In PCF, ZnO and ZnCo2O4 form a Z-scheme photocatalytic system and ZnCo2O4 and Co3O4 constitute a Type II-heterojunction photocatalytic system. The used cobalt foil acts as both a carrier of photocatalyst and a cathode. The structures and properties of PCF were studied by XRD, SEM, TEM, EDX, XPS, PL, TPR and EIS. Through photocatalytic norfloxacin degradation and hydrogen evolution, the effects of cobalt foil thickness, the coating Zn(OH)2 precipitation layer number, calcination temperature and calcination time on the photocatalytic performance of the Z-scheme-Type II-heterojunction ZnO/ZnCo2O4–Co3O4|Co PCFs were investigated. When the cobalt foil thickness is 0.10 mm, coating Zn(OH)2 precipitation layer number is 2, composite film is calcined under 500 °C for 3.0 h and norfloxacin concentration is 10 mg/L and 50 mg/L, norfloxacin degradation ratio and H2 evolution amount reach 80.70 % and 357.12 μmol/dm2, respectively. In addition, a possible mechanism of norfloxacin degradation with simultaneous H2 evolution caused by immobilized Z-scheme-Type II-heterojunction ZnO/ZnCo2O4–Co3O4|Co PCF was proposed. It is hoped that the work has certain guiding significance to design an immobilized PCF for organic pollutants degradation with synchronous large-scale hydrogen evolution.

RNA-sequencing analysis reveals the co-biodegradation performance of crude oil by marine Chlorella vulgaris under norfloxacin stress

In this study, the microalgal growth and crude oil (CRO) biodegradation by marine Chlorella vulgaris (C. vulgaris) were assessed under norfloxacin (NFX) stress. The presence of NFX negatively affected the bio-removal of CRO within 5 days, as the NFX concentration increased from 100 to 1600 μg/L, due to its toxicity as an antibiotic. However, its negative impact on the final degradation capabilities of C. vulgaris was less significant (P-value <0.05). After 9 days of cultivation, CRO bio-removal efficiencies still exceeded 90 %, while NFX bio-removal efficiencies maintained over 47 %. RNA-seq analysis revealed that the degradation of CRO and NFX was attributed to the combined action of functional genes involved in scavenging reactive oxygen species. The production of pigments and the bio-removal performance of C. vulgaris in CRO, NFX, and CRO & NFX coexistence media were consistent with the changes in the number of differentially expressed genes in these samples.

Potential geographical distribution of harmful algal blooms caused by the toxic dinoflagellate Karenia mikimotoi in the China Sea

The fish-killing dinoflagellate Karenia mikimotoi frequently blooms in China and poses a threat to food safety and human health. To better understand harmful algal blooms (HABs) caused by K. mikimotoi and predict the risk of HABs under climate change, the combined effect of nitrate and norfloxacin (NOR) on the growth of K. mikimotoi was tested. A growth model was used to test the effects of nutrients and pollutants on the carrying capacity of the unicellular algae. The carrying capacity increased with increasing concentrations of nitrate and NOR, reaching a maximum at 62.2 μmol L−1 of nitrate and 9.03 mg L−1 of NOR. The calculated carrying capacity of K. mikimotoi in the China Sea showed a declining trend from nearshore to offshore, with a value >30 × 106 cells L−1 in the estuary of the Changjiang River and Hangzhou Bay. The HAB index proposed in this study as a measurement of HAB risk was constructed using the carrying capacity and relative abundance from the MaxEnt (maximum entropy) model. The index showed that HABs caused by K. mikimotoi consecutively occurred in Zhejiang and Fujian coastal waters and predicted that they will continue until 2100, regardless of the greenhouse gas emission scenario. The center of the integrated area moved northward, with a range of 120–900 km. The HAB index integrates the characteristics of the carrying capacity and suitability of habitats, and expresses the information contained in the intensive and extensive variables that affect HAB occurrence. This index is a promising predictor of HAB risk in coastal waters.

Impacts of norfloxacin on sewage sludge anaerobic digestion: Bioenergy generation and potential environmental risks

Norfloxacin is a broad-spectrum antibiotic which has been frequently detected in the sewage sludge. However, whether norfloxacin in sewage sludge would affect the anaerobic digestion for bioenergy generation and induce environmental risks remained unclear. Therefore, this study investigated the impact of norfloxacin on sewage sludge anaerobic digestion and evaluated potential environmental risks by exploring related antibiotic resistance genes (ARGs) and norfloxacin transformation pathways. The results showed that norfloxacin at environmental relevant concentration ranges would not significantly affect methane production (p < 0.05) during the sludge anaerobic digestion, as the sludge solubilization and hydrolysis is unaffected. However, the individual methanogenesis process was enhanced with the increase of Methanosaeta abundances. Meanwhile, the increase of norfloxacin concentration will not decrease the removal efficiencies of fluoroquinolones-family ARGs by the anaerobic digestion process. However, the norfloxacin concentration is found to be increased during the anaerobic digestion process, which could probably be due to the desorption from the sludge due to cell lysis. In addition, 13 norfloxacin transformation metabolites were identified with 5 potential norfloxacin degradation pathways being constructed. The metabolites of levofloxacin/ofloxacin could be generated through Eschweiler-Clarke reaction, which may be more toxic than norfloxacin. Thus, the results of this study suggested that although norfloxacin would not affect the bioenergy generation and ARG removal during sludge anaerobic digestion, measures should be taken to deal with the potential environmental risks caused by norfloxacin release and formation of more toxic metabolites.

Coupling of submerged macrophytes and epiphytic biofilms reduced methane emissions from wetlands: Evidenced by an antibiotic inhibition experiment

Wetlands are the largest natural methane source, but how submerged macrophytes affect methane emission remains controversial. In this study, the impacts of submerged macrophytes on methane fluxes, water purification, and epiphytic microbial community dynamics were investigated in simulated wetlands (with and without Hydrilla verticillata) treated with norfloxacin (NOR) for 24 days. Mean methane fluxes were significantly lower in treatments with Hydrilla verticillata (56.84–90.94 mg/m2/h) than bulks (65.96–113.21 mg/m2/h) (p < 0.05) during the experiment regardless of NOR. The relative conductivity (REC) values, H2O2, and malondialdehyde (MDA) contents increased in plant leaves, while water nutrients removal rates decreased with increasing NOR concentration at the same sampling time. The partial least squares path model analysis revealed that plant physiological indices and water nutrients positively affected methane fluxes (0.72 and 0.49, p < 0.001). According to illumina sequencing results of 16S rRNA and pmoA genes, α-proteobacteria (type II) and γ-proteobacteria (type I) were the dominant methanotroph classes in all epiphytic biofilms. The ratio of type I/type II methanotrophs and pmoA gene abundance in epiphytic biofilm was considerably lower in treatment with 16 mg/L NOR than without it (p < 0.05). pmoA gene abundance was negatively correlated with methane fluxes (p < 0.05). Additionally, the assembly of epiphytic bacterial community was mainly governed by deterministic processes, while stochastic dispersal limitation was the primary assembly process in the epiphytic methanotrophic community under NOR stress. The deterministic process gained more importance with time both in bacterial and methanotrophic community assembly. Network analysis revealed that relationships among bacteria in epiphytic biofilms weakened with time but associations among methanotrophic members were enhanced under NOR stress over time. It could be concluded that submerged macrophytes-epiphytic biofilms symbiotic system exhibited potential prospects to reduce methane emissions from wetlands under reasonable management.

Electrospun nanofiber-based indicatorpaper sensing platform for fluorescence and visualization detection of norfloxacin

Norfloxacin (NOR) residues in water pose a serious threat to human health via the food chain, necessitating the development of a rapid on-site antibiotic detection technique. In this work, we utilize electrostatic spinning technology that combines polyacrylonitrile (PAN) fibers and adenosine triphosphate (ATP)-rare earth metal Tb3+ complexes (ATP/Tb) to construct a new ternary film-based sensor for sensitive, quick, and convenient field testing of NOR in water. The operating mechanism is that the ternary system produces gradually enhanced bright green fluorescence at increasing concentrations of NOR. The unique fluorescence property of the ternary systems is attributed to the use of ATP, rather than the commonly used adenosine monophosphate (AMP), to coordinate with Tb3+, which avoided the possible fluorescence quenching from competitive water binding. Benefiting from the PAN nanofiber's superior stability, acid, and alkali resistance, and flexibility as support, the ternary system exhibited a good linear response to NOR in a wide dynamic range of 0.04–30 μM at the detection limit of 16 nM. Additionally, the combination of a smartphone color recognition app allows for quick on-scene NOR detection. This film sensing strategy is instructive for the development of smart and portable sensing platforms for real-time detection of analytes such as antibiotics, pesticide residues, and hazardous materials in water bodies.

Pharmacokinetic Profile of Norfloxacin in Pigeons

Through this work, the pharmacokinetics of Norfloxacin in pigeons were explored by using six healthy male pigeons as the subjects for this study. The pharmacokinetic indices of orally administered Norfloxacin were obtained by microbiological assay and then the data were fitted to the two-compartment pharmacokinetic open model to evaluate the distribution and excretion parameters. In the achieved results, the calculated absorption rate constant (Kab) was 1.26 h-1, the maximum achieved concentration of Norfloxacin was 2.75 μg/ml at 1.34 hr., the volume of distribution (Vd/F) was 3.15 L/kg. The half-life (t1/2β) was 4.9 hrs., the calculated area under the curve of Norfloxacin (AUC0-t) was 16.75 (h*μg)/ml, while the clearance of Norfloxacin (Cl/F) was 0.49 L/hr/kg. In conclusion, the pharmacokinetic parameters of Norfloxacin in pigeons are not far away from other birds like chickens, considering the differences among them. Norfloxacin is a valuable antibacterial agent against susceptible bacterial infections depending on the obtained pharmacokinetic profile. In conclusion, pharmacokinetic parameters of Norfloxacin in pigeons are not far away from other birds like chicken considering the differences in species, moreover Norfloxacin is a valuable antibacterial agent against susceptible bacterial infections depending on the obtained pharmacokinetic profile.