Removal Of Nalidixic Acid Research Articles

Removal of nalidixic acid from aqueous solutions using a cathode containing three-dimensional graphene

Herein three-dimensional graphene (3DG) was synthesized by solution combustion method. A nanostructured 3DG modified carbon paper as the cathode was employed in the homogeneous electro-Fenton method for degradation of nalidixic acid from aqueous solutions and as an anode electrode, graphite was used. The physic-chemical properties of 3DG powder and modified carbon paper were studied by the SEM, XRD, AFM, FTIR, CV and BET analyses. The ability of the resultant 3DG modified carbon paper cathode for hydrogen peroxide production was investigated in solution fed with air. Results showed that the value of hydrogen peroxide that was electrogenerated by using 3DG electrode is 4 times more than bare carbon paper and graphene oxide modified electrode. The consequence of running parameters including current intensity (mA), initial solution pH, initial concentration of nalidixic acid (mg L−1) and process time were investigated comprehensively in a series of batch experiments which were optimized by response surface method (RSM) and the optimized amounts of each parameter were respectively 300 mA, 3.5, 15 mg L−1 and 300 min. The pharmaceutical removal efficiency was 90% under these optimum conditions. The total organic carbon (TOC) measurements showed 87.3% mineralization of 15 mg L−1 drug at 7 h. The gas chromatography (GC) linked to a mass spectrometry (MS) was used to recognize the generated intermediates through the nalidixic acid degradation.

Kinetic modeling of nalidixic acid degradation by clinoptilolite nanorod-catalyzed ozonation process

The removal of nalidixic acid (NAD) through the clinoptilolite nanorod (CN)-catalyzed ozonation process was modeled by three types of kinetic approaches.

Removal of nalidixic acid and its degradation products by an integrated MBR-ozonation system

Chemical–biological degradation of a widely spread antibacterial (nalidixic acid) was successfully obtained by an integrated membrane bioreactor (MBR)-ozonation process. The composition of the treated solution simulated the wastewater from the production of the target pharmaceutical, featuring high salinity and a relevant concentration of sodium acetate. Aim of treatment integration was to exploit the synergistic effects of chemical oxidation and bioprocesses, by adopting the latter to remove most of the COD and the ozonation biodegradable products. Integration was achieved by placing ozonation in the recirculation stream of the bioreactor effluent. The recirculation flow rate was three-fold the MBR feed, and the performance of the integrated system was compared to the standard polishing configuration (single ozonation step after the MBR). Results showed that the introduction of the ozonation step did not cause relevant drawbacks to both biological and filtration processes. nalidixic acid passed undegraded through the MBR and was completely removed in the ozonation step. Complete degradation of most of the detected ozonation products was better achieved with the integrated MBR-ozonation process than using the sequential treatment configuration, i.e. ozone polishing after MBR, given the same ozone dosage.

Reversible Induction of ATP Synthesis by DNA Damage and Repair in Escherichia coli: IN VIVO NMR STUDIES

Early metabolic events in Escherichia coli exposed to nalidixic acid, a topoisomerase II inhibitor and an inducer of the SOS system, were investigated by in vivo NMR spectroscopy, a technique that permits monitoring of bacteria under controlled physiological conditions. The energetics of AB1157 (wild type) and of its isogenic, SOS-defective mutants, recBC, lexA, and DeltarecA, were studied by 31P and 19F NMR before, during, and after exposure to nalidixic acid. The content of the NTP in E. coli embedded in agarose beads and perfused at 36 degreesC was found to be 4.3 +/- 1.1 x 10(-18) mol/cell, yielding a concentration of approximately 2.7 +/- 0.7 mM. Nalidixic acid induced in the wild type and mutants a rapid 2-fold increase in the content of the NTP, predominantly ATP. This induction did not involve synthesis of uracil derivatives or breakdown of RNA and caused cell proliferation to stop. Removal of nalidixic acid after 40 min of treatment rescued the cells and resulted in a decrease of ATP to control levels and resumption of proliferation. However, in DeltarecA cells, which were more sensitive to the activity of the drug, ATP elevation could not be reversed, and ATP content continued to increase faster than in control cells. The results ruled out association between the elevation of ATP and the induction of the SOS system and suggested involvement of a process reminiscent of apoptosis in the stimulation of ATP synthesis. Thus, the presence of the RecA protein was found to be essential for reversing the ATP increase and cell rescue, possibly by its function in repair of DNA damage.

The effect of nalidixic acid on the cell cycle of synchronous Rhodopseudomonas palustris cultures.

The influence of the DNA synthesis inhibitor, nalidixic acid, on the properties of synchronous cultures of selected Rhodopseudomonas palustris swarmer cells was examined. There was little alteration in the changes in morphology, extinction, volume distribution and leucine incorporation up to bud development, and photosynthetic membrane lamellae were still synthesized de novo in the bud. However, there was no subsequent division, or flagellum or holdfast synthesis. Instead cells elongated by continued outgrowth of the abortive bud. Since DNA synthesis was also inhibited, this suggested a dependence of cell division, and flagellum and holdfast synthesis, on the completion of chromosome replication. By addition or removal of nalidixic acid at various times in the cell cycle, periods were demonstrated when the organism was insensitive to the antibiotic indicating that there was a pre-synthetic and post-synthetic gap in the pattern of DNA synthesis in R. palustris swarmers.

Stability of DNA in dark-repair mutants of Escherichia coli B treated with nalidixic acid.

SUMMARY: Breakdown of DNA to acid-soluble fragments induced in strains of Escherichia coli b by nalidixic acid (10 μg./ml.) differed in linear rate according to the ability of the strain to repair DNA lesions. Strains which were exr (bs-2) and exr, uvr (bs-i) exhibited excessive DNA breakdown following nalidixic add treatment. The excision-defective uvr strains, bs-8, bs-12 and wwp-2 her, also degraded their DNA to acid-soluble fragments at a rate which initially was greater than that of the parental strain (E. coli b). This degradation was unaffected by the rad mutation. Removal of nalidixic acid from the system considerably lowered the rate of DNA breakdown. The responses to nalidixic acid and other agents potentiating DNA breakdown are compared.