Uber die Abhängigkeit der bakteriziden Wirkung von Mitomycin C auf E. coli B und B/M C von der Temperatur und dem Nährmeium

1962 ◽  
Vol 17 (10) ◽  
pp. 670-675 ◽  
Author(s):  
Ulrich Winkler
Keyword(s):  
Temperature Coefficient ◽  
Mitomycin C ◽  
Resistant Mutant ◽  
Bactericidal Effect ◽  
E Coli ◽  
Physical Reasons ◽  
Kinetics Of

The bactericidal effect of Mitomycin C on E. coli B and the partial reactivability of MC induced cell-inactivations depends on the genotype, the composition of the plating medium and the postincubation temperature in a way rather similar to that found in corresponding UV-experiments. This indicates that at least one type of MC-induced damage in E. coli must be identical or similar with lesions produced by UV. The kinetics of MC-bindung to the cells is the same for the wildtype and an MC-resistant mutant. The temperature coefficient Q10 for binding of MC is between 2 and 4 in the range from 20 °C to 45 °C ; this shows that the MC-uptake is propably not limited by physical reasons. The results have been discussed considering the hypothesis that MC acts by activating the cellular DNase.

Antibacterial silver-diatomite nanocomposite ceramic with low silver release

2019 ◽  
Vol 20 (2) ◽  
pp. 633-643
Author(s):  
Xiaopeng Qi ◽  
Junwei Chen ◽  
Qian Li ◽  
Hui Yang ◽  
Honghui Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Water Treatment ◽  
Photoelectron Spectroscopy ◽  
Bactericidal Effect ◽  
Ceramic Filter ◽  
Ceramic Filters ◽  
X Ray ◽  
E Coli ◽  
Point Of Use ◽  
Silver Release

Abstract There is an urgent need for an effective and long-lasting ceramic filter for point-of-use water treatment. In this study, silver-diatomite nanocomposite ceramic filters were developed by an easy and effective method. The ceramic filters have a three-dimensional interconnected pore structure and porosity of 50.85%. Characterizations of the silver-diatomite nanocomposite ceramic filters were performed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Silver nanoparticles were confirmed to be formed in situ in the ceramic filter. The highest silver concentration in water was 0.24 μg/L and 2.1 μg/L in short- and long-term experiments, indicating very low silver-release properties of silver-diatomite nanocomposite ceramic filter. The nanocomposite ceramics show strong bactericidal activity. When contact time with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of 105 colony forming units (CFU)/mL exceeded 3 h, the bactericidal rates of the four different silver content ceramics against E. coli and S. aureus were all 100%. Strong bactericidal effect against E. coli with initial concentration of 109 CFU/mL were also observed in ceramic newly obtained and ceramic immersed in water for 270 days, demonstrating its high stability. The silver-diatomite nanocomposite ceramic filters could be a promising candidate for point-of-use water treatment.

scholarly journals Evaluation of the Antimicrobial Activity of Some Components of the Essential Oils of Plants Used in the Traditional Medicine of the Tehuacán-Cuicatlán Valley, Puebla, México

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 295
Author(s):  
Sebastián Candelaria-Dueñas ◽  
Rocío Serrano-Parrales ◽  
Marisol Ávila-Romero ◽  
Samuel Meraz-Martínez ◽  
Julieta Orozco-Martínez ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oils ◽  
Qualitative Evaluation ◽  
Bactericidal Effect ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Diffusion Technique ◽  
Agar Dilution

In Tehuacán-Cuicatlán valley (Mexico), studies have been carried out on the essential oils of medicinal plants with antimicrobial activity and it was found that they present compounds in common such as: α-pinene, β-pinene, carvacrol, eugenol, limonene, myrcene, ocimene, cineole, methyl salicylate, farnesene, and thymol. The goal of this study was to assess the antimicrobial activity of essential oils’ compounds. The qualitative evaluation was carried out by the Kirby Baüer agar diffusion technique in Gram-positive bacteria (11 strains), Gram-negative bacteria (18 strains), and yeasts (8 strains). For the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the agar dilution method was used. All the evaluated compounds presented antimicrobial activity. The compounds eugenol and carvacrol showed the largest inhibition zones. Regarding yeasts, the compounds ocimene, cineole, and farnesene did not show any activity. The compounds eugenol, carvacrol, and thymol presented the lowest MIC; bactericidal effect was observed at MIC level for S. aureus 75MR, E. coli 128 MR, and C albicans CUSI, for different compounds, eugenol, carvacrol, and thymol. Finally, this study shows that the essential oils of plants used by the population of Tehuacán-Cuicatlán valley share compounds and some of them have antibacterial and fungicidal activity.

scholarly journals In VitroAntibacterial Activity of NB-003 against Propionibacterium acnes

2011 ◽  
Vol 55 (9) ◽  
pp. 4211-4217 ◽  
Author(s):  
J. Pannu ◽  
A. McCarthy ◽  
A. Martin ◽  
T. Hamouda ◽  
S. Ciotti ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Propionibacterium Acnes ◽  
Resistant Mutant ◽  
Microtiter Plate ◽  
Content Type ◽  
Oil In Water ◽  
Complete Disruption ◽  
Kinetics Of ◽  
Gel Formulations

ABSTRACTNB-003 and NB-003 gel formulations are oil-in-water nanoemulsions designed for use in bacterial infections.In vitrosusceptibility ofPropionibacterium acnesto NB-003 formulations and comparator drugs was evaluated. Both NB-003 formulations were bactericidal against allP. acnesisolates, including those that were erythromycin, clindamycin, and/or tetracycline resistant. In the absence of sebum, the MIC90s/minimum bactericidal concentrations (MBC90s) for NB-003, NB-003 gel, salicylic acid (SA), and benzoyl peroxide (BPO) were 0.5/2.0, 1.0/2.0, 1,000/2,000, and 50/200 μg/ml, respectively. In the presence of 50% sebum, the MIC90s/MBC90s of NB003 and BPOs increased to 128/1,024 and 400/1,600 μg/ml, respectively. The MIC90s/MBC90s of SA were not significantly impacted by the presence of sebum. A reduction in the MBC90s for NB-003 and BPO was observed when 2% SA or 0.5% BPO was integrated into the formulation, resulting in MIC90s/MBC90s of 128/256 μg/ml for NB003 and 214/428 μg/ml for BPO. The addition of EDTA enhanced thein vitroefficacy of 0.5% NB-003 in the presence or absence of 25% sebum. The addition of 5 mM EDTA to each well of the microtiter plate resulted in a >16- and >256-fold decrease in MIC90and MBC90, yielding a more potent MIC90/MBC90of ≤1/<1 μg/ml. The kinetics of bactericidal activity of NB-003 againstP. acneswere compared to those of a commercially available product of BPO. Electron micrographs ofP. acnestreated with NB-003 showed complete disruption of bacteria. Assessment of spontaneous resistance ofP. acnesrevealed no stably resistant mutant strains.

A STUDY OF THE MECHANISM AND KINETICS OF THE SULPHITE PROCESS

1939 ◽  
Vol 17b (4) ◽  
pp. 121-132 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Temperature Coefficient ◽  
Arrhenius Equation ◽  
Practical Interest ◽  
Effect Of Temperature ◽  
Wood Meal ◽  
Spruce Wood ◽  
Mechanism And Kinetics ◽  
Kinetics Of

The rate of delignification of resin extracted spruce wood-meal has been determined in calcium-base sulphite liquor at temperatures from 130 °C. down to 50 °C. No break was found in the temperature coefficient curve at the lower temperatures, the reaction following the Arrhenius equation closely. Possible mechanisms of the reaction are discussed in the light of existing theories, and the effect of temperature on the yield of pulp is pointed out for its practical interest.

scholarly journals Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

2015 ◽  
Vol 59 (6) ◽  
pp. 3059-3065 ◽  
Author(s):  
C. Pitart ◽  
F. Marco ◽  
T. A. Keating ◽  
W. W. Nichols ◽  
J. Vila
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistant Mutant ◽  
Fluoroquinolone Resistance ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Impact

ABSTRACTCeftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200Enterobacteriaceaeand 25Pseudomonas aeruginosastrains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistantEnterobacteriaceaestrains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBLEscherichia coli(MIC90of 0.25 mg/liter), ESBLKlebsiella pneumoniae(MIC90of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90of 1 mg/liter), non-ESBLE. coli(MIC90of ≤0.125 mg/liter), non-ESBLK. pneumoniae(MIC90of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistantP. aeruginosastrains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtainedin vitrofrom two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains ofEnterobacteriaceaeandP. aeruginosawere ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affectEnterobacteriaceaeandP. aeruginosasusceptibility to ceftazidime-avibactam; that is, there is no cross-resistance.

High Pressure Inactivation of Escherichia coli, Campylobacter jejuni, and Spoilage Microbiota on Poultry Meat

2012 ◽  
Vol 75 (3) ◽  
pp. 497-503 ◽  
Author(s):  
YANG LIU ◽  
MIRKO BETTI ◽  
MICHAEL G. GÄNZLE
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Campylobacter Jejuni ◽  
Resistant Mutant ◽  
Poultry Meat ◽  
E Coli ◽  
Cell Counts ◽  
Meat Spoilage ◽  
Brochothrix Thermosphacta ◽  
Pressure Resistance

This study evaluated the high pressure inactivation of Campylobacter jejuni, Escherichia coli, and poultry meat spoilage organisms. All treatments were performed in aseptically prepared minced poultry meat. Treatment of 19 strains of C. jejuni at 300 MPa and 30°C revealed a large variation of pressure resistance. The recovery of pressure-induced sublethally injured C. jejuni depended on the availability of iron. The addition of iron content to enumeration media was required for resuscitation of sublethally injured cells. Survival of C. jejuni during storage of refrigerated poultry meat was analyzed in fresh and pressure-treated poultry meat, and in the presence or absence of spoilage microbiota. The presence of spoilage microbiota did not significantly influence the survival of C. jejuni. Pressure treatment at 400 MPa and 40°C reduced cell counts of Brochothrix thermosphacta, Carnobacterium divergens, C. jejuni, and Pseudomonas fluorescens to levels below the detection limit. Cell counts of E. coli AW1.7, however, were reduced by only 3.5 log (CFU/g) and remained stable during subsequent refrigerated storage. The resistance to treatment at 600 MPa and 40°Cof E. coli AW1.7 was compared with Salmonella enterica, Shiga toxin–producing E. coli and nonpathogenic E. coli strains, and Staphylococcus spp. Cell counts of all organisms except E. coli AW 1.7 were reduced by more than 6 log CFU/g. Cell counts of E. coli AW1.7 were reduced by 4.5 log CFU/g only. Moreover, the ability of E. coli AW1.7 to resist pressure was comparable to the pressure-resistant mutant E. coli LMM1030. Our results indicate that preservation of fresh meat requires a combination of high pressure with high temperature (40 to 60°C) or other antimicrobial hurdles.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

Antimicrobial Effects of Novel H2O2-Ag+ Complex on Membrane Damage to Staphylococcus aureus,Escherichia coli and Salmonella typhimurium

2021 ◽  
Author(s):  
Bing Han ◽  
Xiaoyu Han ◽  
Mengmeng Ren ◽  
Yilin You ◽  
Jicheng Zhan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Salmonella Typhimurium ◽  
Membrane Damage ◽  
Bactericidal Effect ◽  
E Coli ◽  
Bacterial Cell Membrane ◽  
Time Kill ◽  
Environmental Disinfection

Diseases caused by harmful microorganisms pose a serious threat to human health. Safe and environment-friendly disinfectants are, therefore, essential in preventing and controlling such pathogens. This study aimed to investigate the antimicrobial activity and mechanism of a novel hydrogen peroxide and silver (H 2 O 2 -Ag + ) complex (HSC) in combatting Staphylococcus aureus ATCC 29213, Escherichia coli O157:H7 NCTC 12900 and Salmonella typhimurium SL 1344. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against S. aureus were found to be 0.014 % H 2 O 2 -3.125 mg/L Ag + , while 0.028 % H 2 O 2 -6.25 mg/L Ag + for both E. coli and S. typhimurium . Results of the growth curve assay and time-kill trial suggest that the HSC could inhibit the growth of the tested bacteria, as 99.9 % of viable cells were killed following treatment at the 1 MIC for 3 h. Compared with Oxytech D10 disinfectant (0.25 % H 2 O 2 -5 mg/L Ag + ), the HSC exhibited better antibacterial efficacy at a lower concentration (0.045 % H 2 O 2 -10 mg/L Ag + ). The mechanism of antibacterial action of HSC was found including the disruption of the bacterial cell membrane, followed by entry into the bacteria cell to reduce intracellular adenosine triphosphate (ATP) concentration, and inhibit the activity of antioxidases, superoxide dismutase (SOD) and catalase (CAT). The enhanced bactericidal effect of hydrogen peroxide combined with silver indicates a potential for its application in environmental disinfection, particularly in the food industry.

scholarly journals Effect of DNA-interacting drugs on phage T7 RNA polymerase.

1998 ◽  
Vol 45 (1) ◽  
pp. 127-132 ◽  
Author(s):  
M Piestrzeniewicz ◽  
K Studzian ◽  
D Wilmańska ◽  
G Płucienniczak ◽  
M Gniazdowski
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
T7 Rna Polymerase ◽  
Distamycin A ◽  
E Coli ◽  
Phage T7 ◽  
Drug Dependent ◽  
Dna Complex ◽  
Kinetics Of

9-Aminoacridine carboxamide derivatives studied here form with DNA intercalative complexes which differ in the kinetics of dissociation. Inhibition of total RNA synthesis catalyzed by phage T7 and Escherichia coli DNA-dependent RNA polymerases correlates with the formation of slowly dissociating acridine-DNA complex of time constant of 0.4-2.3 s. Their effect on RNA synthesis is compared with other ligands which form with DNA stable complexes of different steric properties. T7 RNA polymerase is more sensitive to distamycin A and netropsin than the E. coli enzyme while less sensitive to actinomycin D. Actinomycin induces terminations in the transcript synthesized by T7 RNA polymerase. Despite low dissociation rates of DNA complexes with acridines and pyrrole antibiotics no drug dependent terminations are observed with these ligands.

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