Ciprofloxacin Stress Research Articles

Mechanism of biochar in alleviating the inhibition of anaerobic digestion under ciprofloxacin press

The antibiotic ciprofloxacin (CIP), detected in various aqueous environments, has broad-spectrum antimicrobial properties that can severely affect methanogenic performance in anaerobic systems. In this study, a novel strategy to alleviate the inhibition of AD performance under CIP press with the direct addition of biochar (BC) prepared from corn stover was proposed and the corresponding alleviation mechanism was investigated. When the dosage of BC was 5 and 20 g/L, the cumulative methane production in AD could reach 317.9 and 303.0 mL/g COD, and the CIP degradation efficiencies reached 94.1 % and 96.6 %, significantly higher than those of 123.0 mL/g COD and 81.2 % in the Control system. BC avoided excessive reactive oxygen species in anaerobic systems and induced severe oxidative stress response, while protecting the cell membrane and cell wall of microorganisms. Microorganisms could consume and utilize more organic extracellular polymeric substances for their growth and metabolism. When BC was involved in AD, fewer toxic intermediates were generated during CIP biodegradation, reducing acute and chronic toxicity in anaerobic systems. Microbial diversity suggested that BC could enrich functional microorganisms involved in direct interspecies electron transfer like Methanosaeta, norank_f_Bacteroidetes_vadinHA17, JGI-0000079-D21 and Syntrophomonas, thus facilitating the methanogenic process and CIP degradation. Genetic analyses showed that BC could effectively upregulate functional genes related to the conversion of butyrate-to-acetate and acetyl-to-methane under CIP stress, while functional gene abundance associated with CIP degradation enhanced partially, about encoding translocases, oxidoreductases, lyases, and ligases. Therefore, BC can be added to AD under CIP press to address its inhibited methanogenic performance.

Microbial response and recovery strategy of the anammox process under ciprofloxacin stress from pure strain and consortia perspectives

Ciprofloxacin (CIP) poses a high risk of resistance development in water environments. Therefore, comprehensive effects and recovery strategies of CIP in anaerobic ammonia oxidation (anammox) process were systematically elucidated from consortia and pure strains perspectives. The anammox consortia was not significantly affected by the stress of 10 mg L-1 CIP, while the higher concentration (20 mg L-1) of CIP caused a dramatic reduction in the nitrogen removal performance of anammox system. Simultaneously, the abundances of dominant functional bacteria and corresponding genes also significantly decreased. Such inhibition could not be mitigated by the recovery strategy of adding hydrazine and hydroxylamine. Reducing nitrogen load rate from 5.1 to 1.4 kg N m-3 d-1 promoted the restoration of three reactors. In addition, the robustness and recovery of anammox systems was evaluated using starvation and shock strategies. Simultaneously, antibiotic resistance genes and key metabolic pathways of anammox consortia were upregulated, such as carbohydrate and energy metabolisms. In addition, 11 pure stains were isolated from the anammox system and identified through phylogenetic analysis, 40 % of which showed multidrug resistance, especially Pseudomonas. These findings provide deep insights into the responding mechanism of anammox consortia to CIP stress and promote the application of anammox process for treating wastewater containing antibiotics.

Insights into the molecular network underlying phytotoxicity and phytoaccumulation of ciprofloxacin

Ciprofloxacin (CIP) is frequently detected in agricultural soils and can be accumulated by crops, causing phytotoxicities and food safety concerns. However, the molecular basis of its phytotoxicity and phytoaccumulation is hardly known. Here, we analyzed physiological and molecular responses of choysum (Brassica parachinensis) to CIP stress by comparing low CIP accumulation variety (LAV) and high accumulation variety (HAV). Results showed that the LAV suffered more severe inhibition of growth and photosynthesis than the HAV, exhibiting a lower tolerance to CIP toxicity. Integrated transcriptome and proteome analyses suggested that more differentially expressed genes/proteins (DEGs/DEPs) involved in basic metabolic processes were downregulated to a larger extent in the LAV, explaining its lower CIP tolerance at molecular level. By contrast, more DEGs/DEPs involved in defense responses were upregulated to a larger extent in the HAV, showing the molecular basis of its stronger CIP tolerance. Further, a CIP phytotoxicity-responsive molecular network was constructed for the two varieties to better understand the molecular mechanisms underlying the variety-specific CIP tolerance and accumulation. The results present the first comprehensive molecular profile of plant response to CIP stress for molecular-assisted breeding to improve CIP tolerance and minimize CIP accumulation in crops.

Selective and efficient removal of ciprofloxacin from water by bimetallic MOF beads: Mechanism quantitative analysis and dynamic adsorption

MOFs play an important role in the adsorption of antibiotics, but the drawbacks of MOF powders limit their practical applications. Moreover, the dominant adsorption mechanism and the quantitative assessment of MOF powders are less studied. Herein, bimetallic ZIF particles were embedded in chitosan beads via an in-situ growth process (ZnCo-ZIF@CS beads), which could selectively remove ciprofloxacin (CIP) from a complex environment. The maximum adsorption capacity was 348.90 mg/g, superior to that of other advanced adsorbents. ZnCo-ZIF@CS performed efficiently in various actual water samples and showed excellent anti-interference and recycling abilities (only a decrease of 12.74 % after 9 cycles). CIP adsorption could still reach 85.30 % after continuous flow treatment for 600 min. Interestingly, ZnCo-ZIF@CS had a good protective effect on rice seedling growth and alleviated CIP stress in rice seedlings due to the low metal leaching at pH 4.0–11.0. Macroscopic experiments, XPS, 2D-FTIR-COS and DFT results revealed that hydrogen bonding (HB), complexation (CB), electrostatic attraction (EA) and π-π interactions were involved in CIP adsorption. Different interactions dominated CIP adsorption in different pH regions. At pH < 5.0, EA and CB were the main driving forces, accounting for 42–52 % and 27–57 % of the total adsorption; at 5.0 < pH < 9.0, the contribution of EA decreased to < 15 % while CB was still dominant, accounting for ∼ 50 % of the total adsorption, and other effects (HB and π-π) increased to approximately 29–39 %; at pH > 9.0, EA, CB, HB together with π-π caused 1–27 %, 9–31 % and 66–72 % of the total adsorption, respectively. The reaction sequence of functional groups in different CIP solutions and at various pH values was also probed by 2D-FTIR-COS. This study further provides clear evidence for developing robust MOF-based adsorbents and for the mechanism quantitative analysis of pollutant adsorption by MOFs.

Enhancement of anaerobic digestion of ciprofloxacin wastewater by nano zero-valent iron immobilized onto biochar

The commonly used antibiotic ciprofloxacin (CIP) can significantly inhibit and interfere with the anaerobic digestion (AD) performance. This work was developed to explore the effectiveness and feasibility of nano iron-carbon composites to simultaneously enhance methane production and CIP removal during AD under CIP stress. The results demonstrated that when the nano-zero-valent iron (nZVI) content immobilized on biochar (BC) was 33% (nZVI/BC-33), the CIP degradation efficiency reached 87% and the methanogenesis reached 143 mL/g COD, both higher than Control. Reactive oxygen species analysis demonstrated that nZVI/BC-33 could effectively mitigate microorganisms subjected to the dual redox pressure from CIP and nZVI, and reduce a series of oxidative stress reactions. The microbial community depicted that nZVI/BC-33 enriched functional microorganisms related to CIP degradation and methane production and facilitated direct electron transfer processes. Nano iron-carbon composites can effectively alleviate the stress of CIP on AD and enhance methanogenesis.

Stress responses of partial denitrification system under long-term ciprofloxacin exposure in an anaerobic sequencing batch reactor

This study evaluated the stress response of partial denitrification (PD) sludge system under ciprofloxacin (CIP) exposure. The results showed that the nitrite accumulation rate (NAR) decreased from 77.41 % to 28.39 % under CIP stress of 200 µg/L, and after adapting to CIP stress, the NAR of PD system recovered to 61.56 % even the CIP increased to 1000 µg/L. The average COD removal efficiency increased from 69.08 ± 2.01 % to 73.33 ± 2.33 %, and the average removal efficiency of CIP increased from 9.83 % ± 0.71 % in phase II (CIP=50 µg /L) to 30.15 % ± 1.63 % in phase V (CIP=1000 µg /L). Under CIP stress, the protein (PN) in Tightly Bound-extracellular polymeric substances (TB-EPS) increased from 77.60 mg/(g-SS) in phase I to 135.58 mg/(g-SS) in phase Ⅲ (influent CIP=200 µg /L). FTIR revealed that functional groups (CO, C-H, C-O-C) in EPS of PD sludge could bind to CIP to protect microbial cells from damage. The results of principal co-ordinates analysis (PCoA) showed that the addition of CIP had a significant effect on the microbial community structure, CIP exposure led to an increase in biodiversity of PD system. At genus level, Thauera genus abundance decreased, while OLB12 and Denitratisoma genus abundances increased under CIP stress. This was consistent with the result that the conversion of NO3--N to NO2--N was inhibited while NO2--N reduction was promoted. The findings of this study provided insight into the stress-responses of PD system under long-term CIP exposure and provided useful guidance for the risk assessment and control strategy of wastewater treatment plants (WWTPs).

Effects of ciprofloxacin on Eichhornia crassipes phytoremediation performance and physiology under hydroponic conditions.

Antibiotics can be absorbed by aquatic plants, but they seriously affect the health of aquatic plants and threaten the steady state of aquatic ecosystem. The phytoremediation performance and physiology of floating macrophyte (Eichhornia crassipes) under antibiotic ciprofloxacin (CIP) hydroponic conditions were investigated. It was found that CIP absorption of E. crassipes was up to 84.38% and the root was the main absorption tissue. Hydrolysis and microbial degradation were the second removal pathway of CIP followed the plant absorption. After 7 days of CIP exposure, the photosynthesis efficiency of E. crassipes remained stable, and the presence of CIP did not inhibit the growth of the plant. On the 14th day, the superoxide dismutase and catalase activities were increased in response to the CIP stress. However, the tender leaves of E. crassipes turned white and shrivel, attributed to a decrease in chlorophyll content and chlorophyll fluorescence parameters after 21 days of CIP exposure. These findings will have significant implications for E. crassipes to absorb CIP on a limited time-scale and provide a phytoremediation technology for antibiotics in water.

Ciprofloxacin stress changes key enzymes and intracellular metabolites of Lactobacillus plantarum DNZ-4

Ciprofloxacin (CIP) is an antibiotic used to treat infections caused by bacteria. In this experiment, key enzymes and intracellular metabolites of Lactobacillus plantarum DNZ-4 was researched under CIP stress. The results showed that the activities of hexokinase, pyruvate kinase, β-galactosidase and Na+, K+-ATPase after 1/2 minimum bacteriostatic concentration (MIC) CIP treatment were significantly decreased (P<0.01). Gas chromatography-mass spectrometry was used to analysis the changes of main metabolites in the cells and principal component analysis and partial least square model were constructed. The results indicated that CIP could cause changes in intracellular fatty acids, carbohydrates and amino acids, and the mechanism of amino acid metabolism under CIP stress was significantly inhibited. L. plantarum DNZ-4 made stress response to CIP by regulating the ratio of saturated fatty acids and unsaturated fats. This experiment revealed the changes of growth and metabolism mechanism of L. plantarum DNZ-4 under CIP stress, which help to provide technical means for the development of effective probiotics preparation products.

Nitrate supply decreases uptake and accumulation of ciprofloxacin in Brassica parachinensis

How nitrate (NO3−) fertilization influences ciprofloxacin (CIP) uptake by crops remains unsolved. Here, two Brassica parachinensis cultivars differing in CIP accumulation were cultivated to investigate the effects of NO3− supply on CIP uptake and the underlying mechanism. The results showed that NO3− supply effectively reduced CIP toxicity and accumulation in the two cultivars, especially in the low CIP cultivar. Moreover, NO3− supply induced different mechanisms of coping with CIP stress in the two cultivars through influencing subcellular distribution of CIP. The uptake of CIP by root was demonstrated to be a carrier-mediated, energy-consuming, and proton motive force-dependent influx process. Consequently, a mechanism of nitrate supply decreasing CIP uptake was proposed that uptake of CIP and NO3- into root cell would compete for the proton motive force and share a common energy source provided by plasma membrane H+-ATPase. Besides, regulating the concentration balances of cytoplasmic NO3- and proton by inhibiting the activities of NRase and two tonoplast proton pumps (V-ATPase and V-PPase) led to opposite effect on CIP uptake, further supporting this inference. Our results provide a novel insight into CIP uptake by plant roots, and improve the strategy of minimizing CIP accumulation in crops for food safety by fertilization management.

Ecotoxicological effects and accumulation of ciprofloxacin in Eichhornia crassipes under hydroponic conditions.

Antibiotic residues pose a threat to the health of aquatic organisms. The effects and accumulation of antibiotic ciprofloxacin (CIP) in a floating macrophyte (Eichhornia crassipes) under hydroponic conditions were investigated. It was found that E. crassipes exposure to CIP (< 1000 μg L-1) could maintain a stable photosynthesis efficiency. In response to CIP stress, catalase and peroxidase activities of leaves were 7.24-37.51 nmol min-1 g-1 and 98.46-173.16 U g-1, respectively. The presence of CIP did not inhibit the growth of the plant. After 14 days of exposure, tender leaves became white and withered, ascribed to the decline of chlorophyll content and chlorophyll fluorescence parameters. The CIP concentrations, absorbed by E. crassipes, were highest in the roots, followed by white aerial parts and green aerial parts at CIP concentrations of 100 and 1000 μg L-1. These findings demonstrated that E. crassipes could absorb and tolerate CIP in a limited time-scale and imply an alternative solution for phytoremediation in water bodies contaminated with antibiotics.

Evaluation of the taxonomic and functional variation of freshwater plankton communities induced by trace amounts of the antibiotic ciprofloxacin

Ciprofloxacin (CIP), one of the most frequently detected antibiotics in water systems, has become an aquatic contaminant because of improper disposal and excretion by humans and animals. It is still unknown how trace amounts of CIP affect the aquatic microbial community diversity and function. We therefore investigated the effects of CIP on the structure and function of freshwater microbial communities via 16S/18S rRNA gene sequencing and metatranscriptomic analyses. CIP treatment (7 μg/L) did not significantly alter the physical and chemical condition of the water body as well as the composition of the main species in the community, but slightly increased the relative abundance of cyanobacteria and decreased the relative abundance of eukaryotes. Metatranscriptomic results showed that bacteria enhanced their phosphorus transport and photosynthesis after CIP exposure. The replication, transcription, translation and cell proliferation were all suppressed in eukaryotes, while the bacteria were not affected in any of these aspects. This interesting phenomenon was the exact opposite to both the antibacterial property of CIP and its safety for eukaryotes. We hypothesize that reciprocal and antagonistic interactions in the microcosm both contribute to this result: cyanobacteria may enhance their tolerance to CIP through benefiting from cross-feeding and some secreted substances that withstand bacterial CIP stress would also affect eukaryotic growth. The present study thus indicates that a detailed assessment of the aquatic ecotoxicity of CIP is essential, as the effects of CIP are much more complicated in microbial communities than in monocultures. CIP will continue to be an environmental contaminant due to its wide usage and production and more attention should be given to the negative effects of antibiotics as well as other bioactive pollutants on aquatic environments.

Systematically integrated metabonomic-proteomic studies of Escherichia coli under ciprofloxacin stress

Many antibiotics are used to kill pathogenic Escherichia coli each year, resulting in an increase in the number of antibiotic-resistant strains. In this study, an integrated metabonomic-proteomic method was performed to systematically compare the profiles of metabolites and proteins with or without ciprofloxacin (CFLX) treatment. Proteomics identified 290 altered proteins including 143 with decreased and 147 increased expression, respectively. Metabonomics identified 65 altered metabolites including 58 and 7 with decreased and increased expression, respectively. The integrated analysis showed that the CFLX inhibited the DNA replication and increased the expression of DNA gyrase and DNA topoisomerase 1, while causing a sharp decrease in metabolic activity such as the alanine, aspartate and glutamate metabolism. Moreover, CFLX affected the biosynthesis of aminoacyl- transfer RNAs (tRNAs), leading to an increase in aminoacyl-tRNAs ligases, but limited the aminoacyl-tRNAs-mediated-biosynthesis of related amino acids. In this study, we identified the metabolite and protein profiles under CFLX stress, indicating the mode of action of antibiotics in E. coli. Furthermore, the decreasing metabolic activity in E. coli may be an effective strategy to escape killing by antimicrobials or toxic compounds. The results of this study will advance our understanding of the mechanisms underlying the resistance of bacteria to antibiotics. Biological significanceTo investigate the biological impact of antibiotics stress on Escherichia coli, we applied an integrated metabonomic-proteomic method to systematically compare the profiles of metabolites and proteins between with and without antibiotics ciprofloxacin (CFLX) treatment. Following bioinformatics analysis showed that CFLX inhibited the DNA replication and increased the expression of DNA gyrase and DNA topoisomerase, while causing a sharp increase in the alanine, aspartate and glutamate metabolism. Moreover, CFLX affected the biosynthesis of tRNAs and limited the generation of related amino acids metabolites. In a summary, our results will provide the metabolite and protein profiles under CFLX stress, indicating the mode of action of antibiotics in E. coli. The results of this study will advance our understanding of the mechanisms underlying the resistance of bacteria to antibiotics.

Intraspecific variability of ciprofloxacin accumulation, tolerance, and metabolism in Chinese flowering cabbage (Brassica parachinensis)

To investigate the mechanism of genotype differences in ciprofloxacin (CIP) accumulation, this study was designed to compare the tolerance and metabolic responses to CIP exposure between low (Cutai) and high (Sijiu) CIP-accumulation cultivars of Brassica parachinensis. Decreases in biomass and chlorophyll content were significantly greater (p < 0.05) and toxicities were more severe within cell ultrastructures of Cutai compared to Sijiu. A sequential growth test also revealed that Sijiu was more tolerant to CIP stress compared to Cutai. Meanwhile, significantly higher (p < 0.05) root parameters and higher areas of the stele and xylem may be responsible for the increased uptake and transport of CIP in Sijiu. Ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC–ESI-MS/MS) analysis revealed that CIP was metabolized to three major metabolites by the hydroxylation and breakdown of the piperazinyl substituent in the CIP molecule. The enhanced metabolic transformation of CIP in Sijiu indicated a more efficient capacity to detoxify, which in turn favored an increased accumulation of CIP in this cultivar. Thus, the present study demonstrated that the stronger tolerance and metabolism of Sijiu to CIP were responsible for its high CIP accumulation, suggesting an evolutionary mechanism for adaptation to environmental stress.

Variations in microbial community and ciprofloxacin removal in rhizospheric soils between two cultivars of Brassica parachinensis L.

Ciprofloxacin (CIP) is one of most used quinolone antibiotics detected frequently in agricultural soils and vegetables. In the present study, variations in microbial community and CIP removal in rhizospheric soils between two cultivars of Brassica parachinensis L. that accumulate higher and lower CIP (Sijiu and Cutai, respectively) were investigated under CIP stress (0mg/kg in CK, 2.94mg/kg in T1, and 67.11mg/kg in T2). The removal rates of CIP in rhizospheric soils of cultivar Sijiu were higher than those of cultivar Cutai, with a significant difference in T2 (48.7%>39.4%, P<0.05). The pyrosequencing of 16S rRNA and ITS gene indicated that the microbial diversity and community structure in rhizospheric soils of the two cultivars varied significantly. Spirochaeta and Trichosporon might be associated with CIP degradation, and higher relative abundances of Trichosporon in rhizoshperic soils of cultivar Sijiu might be responsible for higher CIP removal. Fourteen bacterial genera and ten fungal genera were screened as potential biomarkers for CIP removal process. The community level physiological profiling in rhizospheric soils of the two cultivars under CIP stress differed significantly, and more C substrates that favored CIP removal were observed in rhizoshperic soils of cultivar Sijiu. Our results demonstrate that variations in microbial community and the utilization of C substrates played important roles in differring the CIP removal in rhizospheric soils between the two cultivars.

Ciprofloxacin toxicity and its co-metabolic removal by a freshwater microalga Chlamydomonas mexicana

This study evaluated the toxicity and cellular stresses of ciprofloxacin (CIP) and its co-metabolic removal in a freshwater microalga Chlamydomonas mexicana. The toxicological effects of CIP on C. mexicana were assessed by studying the growth and biochemical characteristics of the microalga including total chlorophyll, carotenoid content, malondialdehyde (MDA) and superoxide dismutase (SOD) activity. The calculated effective concentration (EC50) of CIP on C. mexicana was 65±4mgL−1 at 96h. The growth of C. mexicana was significantly inhibited at increased concentrations of CIP, showing 36±1, 75±3. and 88±3% inhibition at 40, 60 and 100mgL−1 CIP, respectively, compared to the control after 11days of cultivation. The total chlorophyll, carotenoid, MDA and SOD activity were significantly increased as a result of relatively high concentrations of CIP stress. C. mexicana showed 13±1% removal of CIP (2mgL−1) after 11days of cultivation; however, the addition of an electron donor (sodium acetate, 4gL−1) highly enhanced the removal of CIP (2mgL−1) by>3-fold after 11days. Kinetic studies showed that removal of CIP followed a first-order model (R2 0.94–0.97) with the apparent rate constants (k) ranging from 0.0121 to 0.079 d−1.