Produce H2 O2 Research Articles

Clinical concentrations of peroxidases cause dysbiosis in invitro oral biofilms.

Little is known about the initiation of dysbiosis in oral biofilms, a topic of prime importance for understanding the etiology of, and preventing, periodontitis. The aim of this study was to evaluate the effect of different concentrations of crevicular and salivary peroxidase and catalase on dysbiosis in multispecies biofilms in vitro. The spotting technique was used to identify the effect of different concentrations of myeloperoxidase, lactoperoxidase, erythrocyte catalase, and horseradish peroxidase in salivary and crevicular fluid on the inhibitory effect of commensals on pathobiont growth. Vitality-quantitative real-time PCR was performed to quantify the dysbiotic effect of the peroxidases (adjusted to concentrations found in periodontal health, gingivitis, and periodontitis) on multispecies microbial communities. Agar plate and multispecies ecology experiments showed that production of hydrogen peroxide (H2 O2 ) by commensal bacteria decreases pathobiont growth and colonization. Peroxidases at concentrations found in crevicular fluid and saliva neutralized this inhibitory effect. In multispecies communities, myeloperoxidase, at the crevicular fluid concentrations found in periodontitis, resulted in a 1-3 Log increase in pathobionts when compared with the crevicular fluid concentrations found in periodontal health. The effect of salivary lactoperoxidase and salivary myeloperoxidase concentrations was, in general, similar to the effect of crevicular myeloperoxidase concentrations. Commensal species suppress pathobionts by producing H2 O2 . Catalase and peroxidases, at clinically relevant concentrations, can neutralize this effect and thereby can contribute to dysbiosis by allowing the outgrowth of pathobionts.

Glucose biosensor based on immobilization of glucose oxidase on a carbon paste electrode modified with microsphere-attached l-glycine.

In the present study, a novel biosensor that is sensitive to glucose was prepared using the microspheres modified with (4-formyl-3-methoxyphenoxymethyl)polystyrene (FMPS) with l-glycine. Polymeric microspheres having Schiff bases were prepared from FMPS using the glycine condensation method. Glucose oxidase enzyme was immobilized onto modified carbon paste electrode by cross-linking with glutaraldehyde. Oxidation of enzymatically produced H2 O2 (+0.5 V vs. Ag/AgCl) was used for determination of glucose. Optimal temperature and pH were found as 50°C and 8.0, respectively. The glucose biosensor showed a linear working range from 5.0 × 10-4 to 1.0 × 10-2 M, R2 = 0.999. Storage and operational stability of the biosensor were also investigated. The biosensor gave perfect reproducible results after 20 measurements with 3.3% relative standard deviation. It also had good storage stability.

Chlamydomonas carries out fatty acid β-oxidation in ancestral peroxisomes using a bona fide acyl-CoA oxidase.

Peroxisomes are thought to have played a key role in the evolution of metabolic networks of photosynthetic organisms by connecting oxidative and biosynthetic routes operating in different compartments. While the various oxidative pathways operating in the peroxisomes of higher plants are fairly well characterized, the reactions present in the primitive peroxisomes (microbodies) of algae are poorly understood. Screening of a Chlamydomonas insertional mutant library identified a strain strongly impaired in oil remobilization and defective in Cre05.g232002 (CrACX2), a gene encoding a member of the acyl-CoA oxidase/dehydrogenase superfamily. The purified recombinant CrACX2 expressed in Escherichia coli catalyzed the oxidation of fatty acyl-CoAs into trans-2-enoyl-CoA and produced H2 O2 . This result demonstrated that CrACX2 is a genuine acyl-CoA oxidase, which is responsible for the first step of the peroxisomal fatty acid (FA) β-oxidation spiral. A fluorescent protein-tagging study pointed to a peroxisomal location of CrACX2. The importance of peroxisomal FA β-oxidation in algal physiology was shown by the impact of the mutation on FA turnover during day/night cycles. Moreover, under nitrogen depletion the mutant accumulated 20% more oil than the wild type, illustrating the potential of β-oxidation mutants for algal biotechnology. This study provides experimental evidence that a plant-type FA β-oxidation involving H2 O2 -producing acyl-CoA oxidation activity has already evolved in the microbodies of the unicellular green alga Chlamydomonas reinhardtii.

Tailoring Microbial Electrochemical Cells for Production of Hydrogen Peroxide at High Concentrations and Efficiencies.

A microbial peroxide producing cell (MPPC) for H2 O2 production at the cathode was systematically optimized with minimal energy input. First, the stability of H2 O2 was evaluated using different catholytes, membranes, and catalyst materials. On the basis of these results, a flat-plate MPPC fed continuously using 200 mm NaCl catholyte at a 4 h hydraulic retention time was designed and operated, producing H2 O2 for 18 days. H2 O2 concentration of 3.1 g L-1 H2 O2 with 1.1 Wh g-1 H2 O2 power input was achieved in the MPPC. The high H2 O2 concentration was a result of the optimum materials selected. The small energy input was largely the result of the 0.5 cm distance between the anode and cathode, which reduced ionic transport losses. However, >50 % of operational overpotentials were due to the 4.5-5 pH unit difference between the anode and cathode chambers. The results demonstrate that a MPPC can continuously produce H2 O2 at high concentration by selecting compatible materials and appropriate operating conditions.

Catalytic Hydroxylation of Benzene to Phenol by Dioxygen with an NADH Analogue.

Hydroxylation of benzene by molecular oxygen (O2 ) occurs efficiently with 10-methyl-9,10-dihydroacridine (AcrH2 ) as an NADH analogue in the presence of a catalytic amount of Fe(ClO4 )3 or Fe(ClO4 )2 with excess trifluoroacetic acid in a solvent mixture of benzene and acetonitrile (1:1 v/v) to produce phenol, 10-methylacridinium ion and hydrogen peroxide (H2 O2 ) at 298 K. The catalytic oxidation of benzene by O2 with AcrH2 in the presence of a catalytic amount of Fe(ClO4 )3 is started by the formation of H2 O2 from AcrH2 , O2 , and H(+) . Hydroperoxyl radical (HO2 (.) ) is produced from H2 O2 with the redox pair of Fe(3+) /Fe(2+) by a Fenton type reaction. The rate-determining step in the initiation is the proton-coupled electron transfer from Fe(2+) to H2 O2 to produce HO(.) and H2 O. HO(.) abstracts hydrogen rapidly from H2 O2 to produce HO2 (.) and H2 O. The Fe(3+) produced was reduced back to Fe(2+) by H2 O2 . HO2 (.) reacts with benzene to produce the radical adduct, which abstracts hydrogen from AcrH2 to give the corresponding hydroperoxide, accompanied by generation of acridinyl radical (AcrH(.) ) to constitute the radical chain reaction. Hydroperoxyl radical (HO2 (.) ), which was detected by using the spin trap method with EPR analysis, acts as a chain carrier for the two radical chain pathways: one is the benzene hydroxylation with O2 and the second is oxidation of an NADH analogue with O2 to produce H2 O2 .

Nox4 supports proper capillary growth in exercise and retina neo-vascularization.

We provide evidence for two distinct functions of the NADPH oxidase Nox4 in angiogenesis using Nox4 knockout mice. First, Nox4 maintains vascular endothelial growth factor expression and prevents an increase in angiopoietin1 expression, thereby contributing to angiogenesis in exercise. Second, deletion of Nox4, via an enhanced angiopoietin1 expression, contributes to stabilization of new formed vessels and prevents an exacerbated neo-angiogenesis in oxygen-induced retinopathy. By contrast, Nox4 does not influence developmental angiogenesis. By producing H2 O2 , the NADPH oxidase Nox4 is involved in hypoxia-induced angiogenesis, as present in vascular remodelling of the hypertrophic heart or blood flow recovery after hind limb ischaemia. In the present study, we hypothesized that Nox4 contributes to proper capillary growth in the retina and in exercised muscles and investigated this in wild-type and Nox4(-/-) mice. Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill, stimulated capillary growth in wild-type but not Nox4(-/-) mice. As an underlying mechanism, we identified both vascular endothelial growth factor (VEGF) expression to be reduced and angiopoietin1 (Ang1) expression to be increased in response to Nox4 knockout. To differentiate the two factors, oxygen-induced retinopathy was investigated. In this model, deletion of Nox4 protected from neo-angiogenesis and stabilized the network of regrown vessels, which is a typical feature of Ang1. However the angiogenesis in the developing retina was similar between Nox4(-/-) and wild-type mice. Thus, Nox4 contributes to exercise- and hypoxia-induced angiogenesis through a dual mechanism of maintaining VEGF and preventing Ang-1 expression, whereas the developmental angiogenesis is Nox4 independent.

Screening of Lactobacillus strains of domestic goose origin against bacterial poultry pathogens for use as probiotics

Lactobacilli are natural inhabitants of human and animal mucous membranes, including the avian gastrointestinal tract. Recently, increasing attention has been given to their probiotic, health-promoting capacities, among which their antagonistic potential against pathogens plays a key role. A study was conducted to evaluate probiotic properties of Lactobacillus strains isolated from feces or cloacae of domestic geese. Among the 104 examined isolates, previously identified to the species level by whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and analysis of 16S-23S regions of rDNA, dominated Lactobacillus salivarius (35%), followed by Lactobacillus johnsonii (18%) and Lactobacillus ingluviei (11%). All lactobacilli were screened for antimicrobial activity toward Salmonella Enteritidis, Escherichia coli, Clostridium perfringens, Staphylococcus aureus, Pasteurella multocida, and Riemerella anatipestifer using the agar slab method and the well diffusion method. Lactobacillus salivarius and Lactobacillus plantarum exhibited particularly strong antagonism toward all of the indicator strains. In the agar slab method, the highest sensitivity to Lactobacillus was observed in R. anatipestifer and P. multocida, and the lowest in E. coli and S. aureus. The ability to produce H2 O2 was exhibited by 92% of isolates, but there was no correlation between the rate of production of this reactive oxygen species and the antimicrobial activity of Lactobacillus sp. All lactobacilli showed resistance to pH 3.0 and 3.5 and to 2% bile. The data demonstrate that Lactobacillus isolates from geese may have probiotic potential in reducing bacterial infections. The antibacterial activity of the selected lactobacilli is mainly due to lactic acid production by these bacteria. The selected Lactobacillus strains that strongly inhibited the growth of pathogenic bacteria, and were also resistant to low pH and bile salts, can potentially restore the balance of intestinal microflora in geese and could offer an alternative to antibiotic therapy.

Drinking Water Purification by Electrosynthesis of Hydrogen Peroxide in a Power‐Producing PEM Fuel Cell

The industrial anthraquinone auto-oxidation process produces most of the world's supply of hydrogen peroxide. For applications that require small amounts of H2 O2 or have economically difficult transportation means, an alternate, on-site H2 O2 production method is needed. Advanced drinking water purification technologies use neutral-pH H2 O2 in combination with UV treatment to reach the desired water purity targets. To produce neutral H2 O2 on-site and on-demand for drinking water purification, the electroreduction of oxygen at the cathode of a proton exchange membrane (PEM) fuel cell operated in either electrolysis (power consuming) or fuel cell (power generating) mode could be a possible solution. The work presented here focuses on the H2 /O2 fuel cell mode to produce H2 O2 . The fuel cell reactor is operated with a continuous flow of carrier water through the cathode to remove the product H2 O2 . The impact of the cobalt-carbon composite cathode catalyst loading, Teflon content in the cathode gas diffusion layer, and cathode carrier water flowrate on the production of H2 O2 are examined. H2 O2 production rates of up to 200 μmol h(-1) cmgeometric (-2) are achieved using a continuous flow of carrier water operating at 30 % current efficiency. Operation times of more than 24 h have shown consistent H2 O2 and power production, with no degradation of the cobalt catalyst.

Nature of Solar Radiation as Encouraged to Produce an Increment of Dissolved Oxygen and Hydrogen Peroxide in Oxidation Ponds for Community Wastewater Treatment at H.M.The King’s LERD Project Site in Phetchaburi Province, Thailand

H.M.The King’s initiative nature by nature process for community wastewater treatment has been conducted since 1990 at Laem Phak Bia sub district, Ban Laem district, Phetchaburi province, Thailand on UTM 1442240 to 1443480 N and 0619271 to 0619271 E. The fresh food markets and households were the point sources of Phetchaburi municipal wastewater that flowing newly construction sewage system in order to receive them to four sub stations on both sides of Phetchaburi river before pumping to Klongyang collection pond. The storage wastewater has been pumped about 3,600 cu.m./day through the 18.5 km. HPDE pipe and putting into sedimentation pond 1 and another four consecutive ponds (oxidation ponds 2, 3, 4, and 5) before the effluent flowing into the mangrove forest. However, the results of experiment found the values of BOD that showing drastic decreasing from Klongyang collection pond through the tip of 18.5 km. HPDE pipe to the sedimentation pond 1 then after it was gradually decreased from one oxidation pond to the next one. Highlight was placed on the obtained effluent after treated wastewater flowed over weir crest that finding BOD under standard and also the decreasing of total coliform bacteria and fecal coliform bacteria, particularly the pathogenic bacteria decreasing down to almost zero MPN/100mL. The question came up how total coliform bacteria and fecal coliform bacteria disappeared after the treated wastewater flowing over weir crest of the oxidation pond 3. The hypothesis was set on the effect of solar radiation to DO and H2O2 which were employed for bacterial organic digestion process in wastewater treatment ponds by taking the measurement randomly on 19 May 2011 that solar radiation showing the solar energy between 0-750 W/m2 all together with UV-A, UV-B, spectrum and net radiation. In order to accomplish the objectives of study, the wastewater quality indicators were found BOD in sedimentation pond 1 67.5 mg/L and oxidation pond 3 16.6 mg/L for 13 hours measurement. In the same manner, the values of DO and H2O2 for 13 hours measurement found in oxidation pond 3 greater than sedimentation pond 1 in respect to 8.9 and 7.6 mg/L for DO and 2.27 and 0.31 µg/L for H2O2. Moreover, the polynomial correlation was studied in order to determine the relationship between net radiation and DO and found very high correlation coefficients in both sedimentation pond 1 and oxidation pond 3. For the quantity of H2O2, it was obtained the relationship between net radiation and H2O2 in higher correlation coefficient in sedimentation pond 1 than oxidation pond 3 because of smaller amount of dissolved organic and inorganic matters in oxidation pond 3. It would be the reason that oxygen which occurred from phytoplankton and algae photosynthesis were not employed by organic digestion and respiration of bacteria. Therefore, it had to exist DO and accumulation only in water instead of producing H2O2 in oxidation pond 3 during daylight time. This is why H2O2 in oxidation pond 3 was not varied directly to net radiation, and also causing an indication on the relationship between net radiation and H2O2 in oxidation pond 3 lower than sedimentation pond 1. Summarily speaking, the nature of solar radiation plays vital role in encouraging producing DO and H2O2 which are the important factors in bacterial organic digestion for community wastewater treatment with high efficiency.

Anti‐Microbial Activity and Composition of Manuka and Portobello Honey

Recently renewed interest in the therapeutic properties of honey has led to the search for new antimicrobial honeys. This study was undertaken to assess the antimicrobial activity and composition of a locally produced Portobello honey (PBH) on three bacteria known to infect wounds. Manuka honey (MH) was used for comparative purposes. Broth culture and agar disc diffusion assays were used to investigate the antimicrobial properties of honey. The honeys were tested at four concentrations: 75%, 50%, 10% and 1% (v/v) and compared with an untreated control. The composition of honey was determined by measuring: polyphenol content by Folin Ciocalteau method, antioxidant capacity by ferric ion reducing power assay, hydrogen peroxide (H2 O2 ) by catalase test, pH and sugar content by pH strips and refractometer, respectively. Both honeys at 75% and 50% inhibited the majority of the three bacteria tested. 10% PBH exhibited antimicrobial activity to the lesser extent than 10% MH. The difference was very significant (p ≤ 0.001). Both honeys were acidic with pH 4, and both produced H2 O2 . The sugar content of PBH was higher than MH, but the difference was not significant. The MH had significantly higher levels of the polyphenols and antioxidant activity than PBH.

Amyloid β−Cu2+Complexes in both Monomeric and Fibrillar Forms Do Not Generate H2O2Catalytically but Quench Hydroxyl Radicals

Oxidative stress plays a key role in Alzheimer's disease (AD). In addition, the abnormally high Cu(2+) ion concentrations present in senile plaques has provoked a substantial interest in the relationship between the amyloid beta peptide (Abeta) found within plaques and redox-active copper ions. There have been a number of studies monitoring reactive oxygen species (ROS) generation by copper and ascorbate that suggest that Abeta acts as a prooxidant producing H2O2. However, others have indicated Abeta acts as an antioxidant, but to date most cell-free studies directly monitoring ROS have not supported this hypothesis. We therefore chose to look again at ROS generation by both monomeric and fibrillar forms of Abeta under aerobic conditions in the presence of Cu(2+) with/without the biological reductant ascorbate in a cell-free system. We used a variety of fluorescence and absorption based assays to monitor the production of ROS, as well as Cu(2+) reduction. In contrast to previous studies, we show here that Abeta does not generate any more ROS than controls of Cu(2+) and ascorbate. Abeta does not silence the redox activity of Cu(2+/+) via chelation, but rather hydroxyl radicals produced as a result of Fenton-Haber Weiss reactions of ascorbate and Cu(2+) rapidly react with Abeta; thus the potentially harmful radicals are quenched. In support of this, chemical modification of the Abeta peptide was examined using (1)H NMR, and specific oxidation sites within the peptide were identified at the histidine and methionine residues. Our studies add significant weight to a modified amyloid cascade hypothesis in which sporadic AD is the result of Abeta being upregulated as a response to oxidative stress. However, our results do not preclude the possibility that Abeta in an oligomeric form may concentrate the redox-active copper at neuronal membranes and so cause lipid peroxidation.

High levels of catalase in sod mutants of Saccharomyces cerevisiae in high aeration conditions

Saccharomyces cerevisiae mutants deficient in superoxide dismutase genes (sod1Δ, sod2Δ and sod1Δsod2Δ mutants) in a stationary phase of growth under high aeration conditions were subjected to H2O2 stress. All the mutants were sensitive after H2O2 treatment. Glutathione peroxidase levels were significantly lower in sod1Δ and sod2Δ single mutants than in the wild-type without treatment. After exposure to H2O2 concentrations, glutathione peroxidase levels were increased in sod1Δsod2Δ double mutants and the sod2Δ single mutant, while sod1Δ maintained lower gluthatione peroxidase activities. The sod2Δ mutant demonstrated a similar catalase activity to that of the wild-type without treatment, whilst decreased catalase activity was observed in conditions of low aeration. Untreated sod1Δsod2Δ double mutant cells presented a lower catalase activity. Catalase levels were higher under high aeration conditions than under microaerophilic conditions, including in sod1Δsod2Δ cells that contain less H2O2, since SOD catalyzes the cleavage of superoxide producing H2O2 and oxygen. We suggest that catalase is not essential for sod mutants under normal conditions, but plays an important role in the acquisition of tolerance to oxidative stress induced by high aeration.

Local Detection of Photoelectrochemically Produced H2O2 with a "Wired" Horseradish Peroxidase Microsensor

Local Detection of Photoelectrochemically Produced H2O2 with a "Wired" Horseradish Peroxidase Microsensor