scholarly journals Escherichia coli cytochrome c peroxidase is a respiratory oxidase that enables the use of hydrogen peroxide as a terminal electron acceptor

2017 ◽  
Vol 114 (33) ◽  
pp. E6922-E6931 ◽  
Author(s):  
Maryam Khademian ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Carbon Source ◽  
Electron Acceptor ◽  
Electron Acceptors ◽  
Flux Rate ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Nonfermentable Carbon Source ◽  
Quinone Pool

Microbial cytochrome c peroxidases (Ccp) have been studied for 75 years, but their physiological roles are unclear. Ccps are located in the periplasms of bacteria and the mitochondrial intermembrane spaces of fungi. In this study, Ccp is demonstrated to be a significant degrader of hydrogen peroxide in anoxic Escherichia coli. Intriguingly, ccp transcription requires both the presence of H2O2 and the absence of O2. Experiments show that Ccp lacks enough activity to shield the cytoplasm from exogenous H2O2. However, it receives electrons from the quinone pool, and its flux rate approximates flow to other anaerobic electron acceptors. Indeed, Ccp enabled E. coli to grow on a nonfermentable carbon source when H2O2 was supplied. Salmonella behaved similarly. This role rationalizes ccp repression in oxic environments. We speculate that micromolar H2O2 is created both biologically and abiotically at natural oxic/anoxic interfaces. The OxyR response appears to exploit this H2O2 as a terminal oxidant while simultaneously defending the cell against its toxicity.

scholarly journals The fixA and fixB Genes Are Necessary for Anaerobic Carnitine Reduction in Escherichia coli

2002 ◽  
Vol 184 (14) ◽  
pp. 4044-4047 ◽  
Author(s):  
Angelique Walt ◽  
Michael L. Kahn
Keyword(s):  
Escherichia Coli ◽  
Electron Acceptor ◽  
Anaerobic Conditions ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Carnitine Metabolism

ABSTRACT In Escherichia coli, the use of carnitine as a terminal electron acceptor depends on a functional caiTABCDE operon. It had been suggested that the adjacent but divergent fixABCX operon is also required for carnitine metabolism, perhaps to provide electrons for carnitine reduction. We have constructed E. coli fixA and fixB mutants and find that they are unable to reduce carnitine to γ-butyrobetaine under anaerobic conditions.

scholarly journals Functional anaerobic electron transport linked to the reduction of nitrate and fumarate in membranes from Escherichia coli as demonstrated by quenching of atebrin fluorescence

1975 ◽  
Vol 152 (3) ◽  
pp. 655-659 ◽  
Author(s):  
B A Haddock ◽  
M W Kendall-Tobias
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Carbon Source ◽  
Electron Acceptor ◽  
Functional Organization ◽  
Terminal Electron Acceptor ◽  
Membrane Particles ◽  
Electron Transport Chains ◽  
Anaerobic Electron Transport ◽  
Energy Dependent

Measurements were made of energy-dependent quenching of atebrin fluorescence in membrane particles prepared from Escherichia coli grown anaerobically with glycerol as carbon source in the presence of either nitrate or fumarate. It is concluded that this technique can be used to study the functional organization of the anaerobic proton-translocating electron-transport chains that use nitrate or fumarate as terminal electron acceptor.

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.

Inactivation of Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, and Listeria monocytogenes on Lettuce by Hydrogen Peroxide and Lactic Acid and by Hydrogen Peroxide with Mild Heat

2002 ◽  
Vol 65 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
CHIA-MIN LIN ◽  
SARAH S. MOON ◽  
MICHAEL P. DOYLE ◽  
KAY H. McWATTERS
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Sensory Characteristics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40°C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22°C for 5 min, and 2% H2O2 at 50°C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50°C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A ≤4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50°C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

Effect of ascorbate on oxygen uptake and growth of Escherichia coli B

1988 ◽  
Vol 34 (6) ◽  
pp. 822-824 ◽  
Author(s):  
Holly E. Richter ◽  
Jacek Switala ◽  
Peter C. Loewen
Keyword(s):  
Escherichia Coli ◽  
Oxygen Uptake ◽  
Electron Acceptor ◽  
Minimal Medium ◽  
Anaerobic Growth ◽  
Rich Medium ◽  
Terminal Electron Acceptor ◽  
Subsequent Change ◽  
Escherichia Coli B

The addition of ascorbate to aerobically growing cultures of Escherichia coli B caused only a short pause in growth and no subsequent change in the rate or extent of growth. The effect of ascorbate on oxygen uptake varied from inhibition in minimal medium to stimulation in rich medium. Cyanide-resistant growth and oxygen uptake were stimulated by ascorbate. Both the rate and extent of anaerobic growth were stimulated in proportion to the amount of ascorbate added when fumarate was the terminal electron acceptor. Ascorbate had no effect on any aspect of anaerobic growth in the absence of a terminal electron acceptor or in the presence of nitrate.

scholarly journals Heterologous Production of 6-Deoxyerythronolide B in Escherichia coli through the Wood Werkman Cycle

Metabolites ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 228
Author(s):  
R. Axayacatl Gonzalez-Garcia ◽  
Lars K. Nielsen ◽  
Esteban Marcellin
Keyword(s):  
Escherichia Coli ◽  
Natural Products ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Structural Diversity ◽  
Heterologous Production ◽  
E Coli ◽  
Anticancer Properties ◽  
Defined Media ◽  
Extender Unit

Polyketides are a remarkable class of natural products with diverse functional and structural diversity. The class includes many medicinally important molecules with antiviral, antimicrobial, antifungal and anticancer properties. Native bacterial, fungal and plant hosts are often difficult to cultivate and coax into producing the desired product. As a result, Escherichia coli has been used for the heterologous production of polyketides, with the production of 6-deoxyerythronolide B (6-dEB) being the first example. Current strategies for production in E. coli require feeding of exogenous propionate as a source for the precursors propionyl-CoA and S-methylmalonyl-CoA. Here, we show that heterologous polyketide production is possible from glucose as the sole carbon source. The heterologous expression of eight genes from the Wood-Werkman cycle found in Propionibacteria, in combination with expression of the 6-dEB synthases DEBS1, DEBS2 and DEBS3 resulted in 6-dEB formation from glucose as the sole carbon source. Our results show that the Wood-Werkman cycle provides the required propionyl-CoA and the extender unit S-methylmalonyl-CoA to produce up to 0.81 mg/L of 6-dEB in a chemically defined media.

scholarly journals Impact of Probiotic on the Number of Lactic Acid Rods Forming Hydrogen Peroxide Isolated From Porkers and on Changes in Drug Resistance of Selected Escherichia Coli Isolates

2012 ◽  
Vol 56 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Marek Selwet ◽  
Mariola Galbas ◽  
Piotr Dullin
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Drug Resistance ◽  
Lactic Acid ◽  
Control Group ◽  
Large White ◽  
E Coli ◽  
Probiotic Preparation ◽  
Hydrogen Oxide

Abstract The presented investigations were conducted on a group of 60 porkers of crossbreed Polish Landrace x Large White Polish. The animals were divided into two equal experimental groups. The control group (K) was fed diets without supplementation with probiotics, group (P) - diets with the addition of probiotic (0.2 kg t-1 feed). The aim of the study was to determine the effect of probiotic preparation on total numberof lactic acid rods from the Lactobacillus genus and those forming hydrogen oxide. The second part of experiment concerned the influence of probiotic preparation on the number, haemolytic ability and changes in drug resistance of Escherichia coli isolated from animal faeces. The significantly highest number of Lactobacillus sp. were determined in the saliva of porkers fed diets with the addition of probiotic, while the lowest in the control group. Lactobacillus sp. rods capable of forming hydrogen peroxide were isolated from 17 animals in group K and from three animals in group P. E. coli was determined in each examined sample of faeces. In groups K and P, counts of these bacteria were similar and did not differ statistically. High numbers of haemolytic isolates (haemolysis β) were found in faeces of animals fed diets with the addition of probiotic. Number and proportions of resistant isolates in groups K and P were different. Gentamicin was characterised by exceptionally high in vitro effectiveness. The used probiotic increased drug resistance of E. coli and increased frequency of incidence of haemolysis β.

Utilization of chymotrypsin as a sole carbon and (or) nitrogen source by Escherichia coli

1992 ◽  
Vol 38 (4) ◽  
pp. 290-295 ◽  
Author(s):  
Arthur S. Brecher ◽  
Timothy A. Moehlman ◽  
William D. Hann
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Nitrogen Source ◽  
Degradation Products ◽  
Defined Medium ◽  
Host Protein ◽  
Mammalian Host ◽  
Sole Nitrogen Source ◽  
E Coli ◽  
Nitrogen Nutrients

α-Chymotrypsin serves as a sole carbon source, sole nitrogen source, and as sole carbon plus nitrogen source for wild-type Escherichia coli in a totally defined medium. Hence, a mammalian host for E. coli may supply the necessary carbon and nitrogen nutrients for the microorganism. Growth is most rapid when chymotrypsin is a sole nitrogen source,and least rapid with chymotrypsin as a carbon source. The approximate doubling times for E. coli utilizing chymotrypsin as a nitrogen source, carbon plus nitrogen source, and carbon source are 1.6, 4.6, and 11.3 h, respectively. The activity of the residual enzyme in the culture supernates falls off asymptotically over the course of time, as followed by cleavage of glutaryl-L-phenylalanine-p-nitroanilide. Chymotrypsin hydrolyzes succinyl-L-ala-L-ala-L-ala-p-nitroanilide, the elastase substrate, to some extent. Peptidases do not appear to be secreted that hydrolyze such model substrates as benzoyl-DL-arginine-p-nitroanilide, the tryptic and cathepsin B substrate, L-leucine-p-nitroanilide, the leucine aminopeptidase substrate, or L-lysine-p-nitroanilide, the aminopeptidase B substrate. Growth of E. coli is generally directly related to the loss of chymotryptic activity in the medium. Hence, autolysis of chymotrypsin, i.e., self-degradation, is an important factor for the availability of degradation products of the enzyme to the bacterium for growth purposes. Accordingly, the degradation of a host protein by autolysis presents an opportunity for E. coli to survive during periods of host nutritional crisis by utilization of the degradation peptides that are produced during autolysis. Key words: chymotrypsin, Escherichia coli, growth, nutrition, peptide source.

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