Effect Of Nalidixic Acid Research Articles

Chemically Stressed Bacterial Communities in Anaerobic Digesters Exhibit Resilience and Ecological Flexibility.

Anaerobic digestion is a technology known for its potential in terms of methane production. During the digestion process, multiple metabolites of high value are synthesized. However, recent works have demonstrated the high robustness and resilience of the involved microbiomes; these attributes make it difficult to manipulate them in such a way that a specific metabolite is predominantly produced. Therefore, an exact understanding of the manipulability of anaerobic microbiomes may open up a treasure box for bio-based industries. In the present work, the effect of nalidixic acid, γ-aminobutyric acid (GABA), and sodium phosphate on the microbiome of digested sewage sludge from a water treatment plant fed with glucose was investigated. Despite of the induced process perturbations, high stability was observed at the phylum level. However, strong variations were observed at the genus level, especially for the genera Trichococcus, Candidatus Caldatribacterium, and Phascolarctobacterium. Ecological interactions were analyzed based on the Lotka–Volterra model for Trichococcus, Rikenellaceae DMER64, Sedimentibacter, Candidatus Cloacimonas, Smithella, Cloacimonadaceae W5 and Longilinea. These genera dynamically shifted among positive, negative or no correlation, depending on the applied stressor, which indicates a surprisingly dynamic behavior. Globally, the presented work suggests a massive resilience and stability of the methanogenic communities coupled with a surprising flexibility of the particular microbial key players involved in the process.

An investigation of antigenotoxic properties of plant extracts of Chelidonium majus L., Plantago major L. and Tussilago farfara L.

The antigenotoxic properties of the sap from three medicinal plants, the greater celandine (Chelidonium majus L.), the greater plantain (Plantago major L.), and coltsfoot (Tussilago farfara L.), were studied using two bacterial test systems (SOS chromotest and Rec assay). It was determined using the combined effect of the plant sap and model genotoxicants on the cells of test strains that the plant sap of the greater celandine reveals a dismutagenic effect decreasing the genotoxic effect of nalidixic acid in the SOS chromotest and furacilin in the Rec assay. The plants sap of the greater celandine and coltsfoot (in 1: 10 and 1: 100 dilutions) demonstrated a bioantimutagenic effect in the SOS chromotest because pre-incubation of the E. coli PQ37 cells test strain with the sap of these plants resulted in a significant decrease of the genotoxic effect of nalidixic acid. The antigenotoxic effect of the greater plantain sap was not statistically significant in both test systems. Possible mechanisms of determining the antigenotoxic properties of the plant sap from greater celandine and coltsfoot are discussed.

Effect of Nalidixic Acid on Bacteria Possessing Mutations in the RECA and Lexa Genes

Effect of Nalidixic Acid on Bacteria Possessing Mutations in the <u>RECA</u> and <u>Lexa</u> Genes

The effect of nalidixic acid on growth and reproductive events in nucleocytosolic and chloroplast compartments in the algaScenedesmus quadricauda

The courses of rRNA accumulation, DNA replication, and nuclear division were followed both in the chloroplast and the nucleocytosolic compartments during the cell cycle in synchronized populations of the chlorococcal alga Scenedesmus quadricauda. Control and nalidixic acid-treated cultures were compared. Nalidixic acid (150 mg/L) was added either at the beginning of the cell cycle or consecutively during the cell cycle to subcultures transferred into the dark. If the inhibitor was applied at the beginning of the cell cycle, chloroplast DNA did not replicate and nucleoids did not divide. Chloroplast division, however, was coordinated in a timely fashion with cytokinesis even under conditions of blocked chloroplast DNA replication. While the growth rate was slowed down, the courses of reproductive processes in the nucleocytosolic compartment were not affected and their timing and the number of rounds were coordinated with growth rate as in the control culture. The rate of cytosolic rRNA synthesis was lower but no apparent effect was seen on the amount of rRNA that accumulated during the cell cycle. In contrast, lower levels of chloroplast rRNA were found at the end of the cell cycle compared with the control culture. Experiments in which cells were transferred to the dark during the cell cycle showed that the inhibitor affected none of the reproductive events in the nucleocytosolic compartment. In the chloroplast compartment, DNA replication was inhibited in inhibitor-treated cultures, but was unaffected in controls. The chloroplast nucleoids themselves divided even in the presence of the inhibitor, reducing their DNA content to a level which corresponded to that in freshly formed control daughter cells.

Transient DNA relaxation in Escherichia coli induced by nalidixic acid.

We report here the transient relaxation of plasmid DNA by inhibitors of DNA gyrase in Escherichia coli. Relaxation of plasmid DNA in the presence of nalidixic acid, an inhibitor of the A subunit of DNA gyrase, lasted less than 60 min. The effect of nalidixic acid was not observed in a nalA26 mutant, a strain resistant to nalidixic acid due to a mutation in the gyrA gene. Novobiocin, whose target is the B subunit of DNA gyrase, also caused transient DNA relaxation. Resupercoiling of relaxed DNA in the presence of nalidixic acid was inhibited by pretreatment of the cells with chloramphenicol. As mutations of both the rpoH and recA genes did not affect the resupercoiling reaction, this step seems to require protein synthesis that is independent of both heat shock and SOS responses.

Sister-chromatid exchanges (SCE) induction by inhibitors of DNA topoisomerases in cultured human lymphocytes

The induction of sister-chromatid exchanges (SCE) in cultured human lymphocytes by four inhibitors of DNA topoisomerases: m-amsacrine, camptothecin, etoposide and nalidixic acid has been evaluated. Although the four compounds apparently increase the frequency of SCE, the effect of nalidixic acid is weak because only a statistically significant positive response was found in one donor at the highest concentration (500 μM). The other compounds tested act as SCE inducers in both donors, camptothecin being the most effective. In addition, the influence of these four topoisomerase inhibitors on the SCE frequency induced by MMC was also analysed. The results reveal that less than additive SCE effect was induced by the combined treatments which could suggest that the process leading to SCE induction by MMC and the four inhibitors of DNA topoisomerases are not totally independent.

Comparison of isopropyl cinodine with nalidixic acid in the direct viable count

Isopropyl cinodine and nalidixic acid were compared in the direct viable count. With raw water and biofilms, elongated cells were seen in the presence of isopropyl cinodine. Increased incubation time led to an increased direct viable count. Individual bacteria responded differently to isopropyl cinodine. Five organisms grew in the presence of 0.01 μg ml‐1 of isopropyl cinodine but were inhibited by 0.1 μg ml‐1. These values for a sixth organism were 0.1 μg ml‐1 and 1.0 μg ml‐1 respectively. The direct viable count was done with inocula taken when the cells were in either lag, log or stationary phases of growth. No differences were seen in the percentage of elongated cells within an experiment but there was variation between experiments. The effect of nalidixic acid and isopropyl cinodine appeared to be additive with respect to inhibition of growth, but little or no additive effect was seen upon the percent of nutrient responsive cells.

The effect of nalidixic acid,cinoxacin,and β–cyanoalanine on cultures chondrocytes

The effect of nalidixic acid,cinoxacin,and β–cyanoalanine on cultures chondrocytes

Modulation of cell wall synthesis by DNA replication in Escherichia coli during initiation of cell growth.

Resting cells of Escherichia coli are able to initiate growth and murein biosynthesis in the presence of beta-lactam antibiotics binding to penicillin-binding proteins (PBPs) 1a and 1b (E. J. de la Rosa, M. A. de Pedro, and D. Vázquez, Proc. Natl. Acad. Sci. USA 82:5632-5635, 1985). Under these conditions, cells elongate normally until they approach the first doubling in mass, the time at which cell lysis starts. Assuming that coupling between DNA replication and cell division both in cells starting growth and in growing cells is essentially similar, triggering of the lytic response in the beta-lactam-treated cells coincides with the termination of the first round of DNA replication. This coincidence suggests that both events are interrelated. We investigated this possibility by studying the initiation of growth in cultures of wild-type strains and in cell division mutants treated with beta-lactams inhibiting PBPs 1a and 1b and with the DNA replication inhibitor nalidixic acid. Addition of nalidixic acid, even late in the first cell cycle, prevented the lytic response of the cells to the blockade of PBPs 1a and 1b. The effect of nalidixic acid is more likely due to its action on DNA replication itself than to its indirect inhibitory effect on cell division or to its ability to induce the SOS system of the cell. These observations favor the idea that the cell wall biosynthetic machinery might be modulated by DNA replication at precise periods during cell growth.

The effect of nalidixic acid on expression from related [formula omitted] promoters

The effect of the DNA gyrase inhibitor, nalidixic acid, on expression from E. coli promoters was studied using the pKO-1, galactokinase expression vector system. Expression from a series of related hybrid promoters, tet promoter variants and the trp promoter flanked by oligonucleotide blocks was measured after incubation with nalidixic acid. Expression from the pBR322 tet promoter and tet promoter mutants within the −10 region was reduced after the drug treatment. The lac UV5, trp , and tettrp promoters were essentially unaffected while the trplac and the trptet promoters were stimulated. Studies of the trp promoter flanked by upstream or downstream oligonucleotide blocks revealed similar responses to the trp promoter parent control plasmids.

Effect of nalidixic acid and novobiocine on the metabolism of suspension cultured carrot cells

Suspension cells of Daucus carota L. cv. Lunga di Amsterdam are extremely sensitive to both nalidixic acid and novobiocine. The synthesis of DNA, RNA and protein are inhibited within minutes of exposure even at concentrations less than 0.1 mM of both drugs. Moreover, uptake of deoxythymidine by cells is impaired more severely than by sodium azide. Reduction of oxygen consumption caused by the two drugs is slower than in the case of NaN3 and occurs a few minutes after the inhibition of macromolecular biosynthesis. This excludes the possibility that the block in oxidation is the primary cause of the observed inhibition of cellular functions and suggests that the inhibition of ATP synthesis, which is immediately affected in both cases, may be responsible for these effects. A possible interaction with other cellular targets may be secondary to the uncoupling effect. Cell growth is completely inhibited by 0.3 mM concentration of both drugs, but this inhibition is irreversible only in the case of novobiocine. The irreversibility of cell growth inhibition by novobiocine can be explained by the total disappearance of ATP from the cell.

Induction of the manganese-containing superoxide dismutase inEscherichia coliby nalidixic acid and by iron chelators

Nalidixic acid caused a significant increase in the Mn-containing superoxide dismutase (MnSOD) of Escherichia coli. The maximum stimulatory effect of nalidixic acid on MnSOD biosynthesis was observed at 0.1 mM. The stimulatory effect of nalidixic acid was not due to increases in the intracellular flux of O−2, but rather to its ability to chelate Fe2+. Furthermore, 2,2′-dipyridyl and 1,10-phenanthroline were shown to cause a 7- to 20-fold increase in the MnSOD of E. coli. It is proposed that the repressor for MnSOD is an iron-containing protein.

Changed properties of the A subunit in DNA gyrase with a B subunit mutation

To investigate the interaction of subunits A and B of DNA gyrase during DNA supercoiling, a Cour mutant of Escherichia coli was obtained and the effect of nalidixic acid on the supercoiling of DNA by wild-type and mutant enzymes was assayed. The enzyme of the Cour strain proved to be more sensitive to nalidixic acid than the wild-type DNA gyrase. Hence the mutation affecting the B subunit can also change the properties of the A subunit, which fact suggests that the two subunits of DNA gyrase are in contact during DNA supercoiling.

EFFECT OF DNA GYRASE INHIBITORS ON GENE EXPRESSION OF THE CYSTEINE REGULON

Nalidixic acid inhibits the expression of those cysteine genes which are regulated by the cysB product, it has no affect, however, on the constitutively expressed cysE gene. The expression of cysteine genes in a strain carrying a mutation in the nalA locus is resistant to this drug. Novobiocin affects the expression of cysteine genes similarly to nalidixic acid. The effect of nalidixic acid on the expression of genes in a cysteine constitutive mutant was studied.

Effect of DNA gyrase inhibitors on gene expression of the cysteine regulon

Nalidixic acid inhibits the expression of those cysteine genes which are regulated by the cysB product, it has no affect, however, on the constitutively-expressed cysE gene. The expression of cysteine genes in a strain carrying a mutation in the nalA locus is resistant to this drug. Novobiocin affects the expression of cysteine genes similarly to nalidixic acid. The effect of nalidixic acid on the expression of genes in a cysteine constitutive mutant was studied.

Loss of Hfr DNA from Escherichia coli merozygotes during inhibition of conjugation by nalidixic acid.

SUMMARYThe effect of nalidixic acid on conjugal recombination was studied in matings with recipient strains carryingrecA200, a mutation which confers a thermosensitive Rec−phenotype. Addition of nalidixic acid to Hfr Nals× F−NalRrecA200matings at low temperature (35 °C) caused a sharp 10- to 20-fold decline in the yield of recombinants if plating on selective agar was delayed. Two separate processes were identified as being responsible for this decline. Those merozygotes in which the transferred DNA was free of the donor cell lost the ability to form recombinants through inactivation of this DNA, an effect which could be prevented by using exonuclease deficient (recB sbcB) recipients or by prior growth of exonuclease proficient recipients in medium containing 0·25 M sodium chloride. No more than 50% of the observed loss of recombinants could be attributed to this effect. The remaining merozygotes lost their ability for recombinant formation provided mating pairs, and presumably the displaced donor DNA strand, remained intact. This process was thought to involve withdrawal of transferred DNA (DeHaan &amp; Gross, 1962) and was studied in isolation in matings withrecA+, orrecA200 recB sbcBrecipients. A mechanism involving re-annealing of the displaced Hfr DNA to the donor molecule as a result of nalidixic inhibition of gyrase activity in the donor causing relaxation of DNA supercoils is proposed to account for this withdrawal event.

Changes in sporulation potential during the growth cycle of Bacillus subtilis.

The sporulation potential of Bacillus subtilis as a function of position in the cell cycle was determined by transferring cells from growth medium to sporulation medium at various times during growth. Growth was induced by incubating heat-activated spores in rich medium or by diluting stationary phase vegetative cultures with fresh growth medium. The results supported earlier observations that sporulation potential is cell cycle dependent. The rise in sporulation potential was studied by exposing cultures to the inhibitors of cell wall and protein synthesis, vancomycin and chloramphenicol. The delay in the appearance of the peak of sporulation potential caused by these inhibitors compared with the reported lack of effect of nalidixic acid, indicates that the appearance of sporulation potential requires synthesis of a macromolecular component other than deoxyribonucleic acid. The effect of nalidixic acid in preventing the decline of the sporulation potential was compared with the effect of high temperature on a mutant temperature sensitive for the initiation of DNA replication. It was found that prevention of chromosome completion with nalidixic acid maintained a high sporulation potential, whereas prevention of chromosome re-initiation in the temperature sensitive mutant did not affect the decline in sporulation potential as the cells enter stationary phase.

Plasmid replication in Salmonella typhimurium LT2 and Escherichia coli K-12: A differential effect of nalidixic acid

Plasmid replication in Salmonella typhimurium LT2 and Escherichia coli K-12: A differential effect of nalidixic acid

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C in Bacillus cereus.

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C (EC 3.1.4.3) has been studied in washed Bacillus cereus cells resuspended in nutrient broth. In the absence of inhibitors, the synthesis showed a biphasic pattern. No synthesis of release of enzyme was found in the presence of chloramphenicol. When rifampicin was added, phospholipase C synthesis continued for 10-15 min. Nalidixic acid, at concentrations which inhibited DNA synthesis completely, permitted the synthesis of phospholipase C at the same rate and for a similar length of time as rifampicin.

Nalidixic Acid-Induced Protein Alterations in Escherichia coli

The effect of nalidixic acid on pulse-labeled protein patterns was analyzed by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis. The drug was found to alter protein patterns in a drug-sensitive strain but not in the isogenic drug-resistant strain of Escherichia coli. The drug-induced alteration of protein patterns was demonstrated by the appearance of some and the disappearance of other pulse-labeled peptides elicited by the drug.