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Sample records for bacterial metal respiration

  1. New Insights into the Mechanism of Bacterial Metal Respiration

    SciTech Connect

    DiChristina, Thomas J.

    2004-04-17

    This project goal is to identify genes and gene products required for microbial metal reduction: reductive dissolution of iron; reductive dissolution of manganese; reductive precipitation of selenium; reductive precipitation of uranium; and reductive precipitation of technetium.

  2. Bacterial respiration of arsenic and selenium

    USGS Publications Warehouse

    Stolz, J.F.; Oremland, R.S.

    1999-01-01

    Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature. Although the bacterial species that have been isolated and characterized are still few in number, they are scattered throughout the bacterial domain and include Gram- positive bacteria, beta, gamma and epsilon Proteobacteria and the sole member of a deeply branching lineage of the bacteria, Chrysiogenes arsenatus. The oxidation of a number of organic substrates (i.e. acetate, lactate, pyruvate, glycerol, ethanol) or hydrogen can be coupled to the reduction of arsenate and selenate, but the actual donor used varies from species to species. Both periplasmic and membrane-associated arsenate and selenate reductases have been characterized. Although the number of subunits and molecular masses differs, they all contain molybdenum. The extent of the environmental impact on the transformation and mobilization of arsenic and selenium by microbial dissimilatory processes is only now being fully appreciated.

  3. Molecular Characterization of Bacterial Respiration on Minerals

    SciTech Connect

    Blake, Robert C.

    2013-04-26

    anomalous dispersion (MAD) phasing; 4. An acid-stable red cytochrome with a novel absorbance peak at 579 nm was purified from cell-free extracts of L. ferriphilum. Functional studies demonstrated that this cytochrome was an important component of the aerobic iron respiratory chain in this organism; 5. The specific adhesion of At. ferrooxidans to pyrite is mediated by an extracellular protein that was identified as aporusticyanin. The adhesion of At. ferrooxidans to minerals was characterized by high affinity binding that exhibited a high specificity for pyrite over other sulfide minerals. The principal biopolymer involved in this high-affinity adhesion to pyrite was isolated by mineral affinity chromatography and identified as aporusticyanin. The adhesion of purified aporusticyanin to minerals was observed to adhere to different mineral with a pattern of reactivity identical to that observed with the intact bacterium. Further, preincubation of pyrite with excess exogenous aporusticyanin served to inhibit the adherence of intact cells to the surface of the mineral, indicating that the protein and the cells adhered to the pyrite in a mutually exclusive manner. Taken together, these observations support a model where aporusticyanin located on the surface of the bacterial cell acts as a mineral-specific receptor for the initial adherence of At. ferrooxidans to solid pyrite; 6. The specific adhesion of L. ferriphilum to pyrite was mediated by a different acid-stable extracellular protein than aporusticyanin; and 7. A prototype integrating cavity absorption meter (ICAM) was assembled to determine whether this novel spectrophotometer could be used to study cellular respiration in situ.

  4. Antibiotic efficacy is linked to bacterial cellular respiration

    PubMed Central

    Lobritz, Michael A.; Belenky, Peter; Porter, Caroline B. M.; Gutierrez, Arnaud; Yang, Jason H.; Schwarz, Eric G.; Dwyer, Daniel J.; Khalil, Ahmad S.; Collins, James J.

    2015-01-01

    Bacteriostatic and bactericidal antibiotic treatments result in two fundamentally different phenotypic outcomes—the inhibition of bacterial growth or, alternatively, cell death. Most antibiotics inhibit processes that are major consumers of cellular energy output, suggesting that antibiotic treatment may have important downstream consequences on bacterial metabolism. We hypothesized that the specific metabolic effects of bacteriostatic and bactericidal antibiotics contribute to their overall efficacy. We leveraged the opposing phenotypes of bacteriostatic and bactericidal drugs in combination to investigate their activity. Growth inhibition from bacteriostatic antibiotics was associated with suppressed cellular respiration whereas cell death from most bactericidal antibiotics was associated with accelerated respiration. In combination, suppression of cellular respiration by the bacteriostatic antibiotic was the dominant effect, blocking bactericidal killing. Global metabolic profiling of bacteriostatic antibiotic treatment revealed that accumulation of metabolites involved in specific drug target activity was linked to the buildup of energy metabolites that feed the electron transport chain. Inhibition of cellular respiration by knockout of the cytochrome oxidases was sufficient to attenuate bactericidal lethality whereas acceleration of basal respiration by genetically uncoupling ATP synthesis from electron transport resulted in potentiation of the killing effect of bactericidal antibiotics. This work identifies a link between antibiotic-induced cellular respiration and bactericidal lethality and demonstrates that bactericidal activity can be arrested by attenuated respiration and potentiated by accelerated respiration. Our data collectively show that antibiotics perturb the metabolic state of bacteria and that the metabolic state of bacteria impacts antibiotic efficacy. PMID:26100898

  5. Antibiotic efficacy is linked to bacterial cellular respiration.

    PubMed

    Lobritz, Michael A; Belenky, Peter; Porter, Caroline B M; Gutierrez, Arnaud; Yang, Jason H; Schwarz, Eric G; Dwyer, Daniel J; Khalil, Ahmad S; Collins, James J

    2015-07-01

    Bacteriostatic and bactericidal antibiotic treatments result in two fundamentally different phenotypic outcomes--the inhibition of bacterial growth or, alternatively, cell death. Most antibiotics inhibit processes that are major consumers of cellular energy output, suggesting that antibiotic treatment may have important downstream consequences on bacterial metabolism. We hypothesized that the specific metabolic effects of bacteriostatic and bactericidal antibiotics contribute to their overall efficacy. We leveraged the opposing phenotypes of bacteriostatic and bactericidal drugs in combination to investigate their activity. Growth inhibition from bacteriostatic antibiotics was associated with suppressed cellular respiration whereas cell death from most bactericidal antibiotics was associated with accelerated respiration. In combination, suppression of cellular respiration by the bacteriostatic antibiotic was the dominant effect, blocking bactericidal killing. Global metabolic profiling of bacteriostatic antibiotic treatment revealed that accumulation of metabolites involved in specific drug target activity was linked to the buildup of energy metabolites that feed the electron transport chain. Inhibition of cellular respiration by knockout of the cytochrome oxidases was sufficient to attenuate bactericidal lethality whereas acceleration of basal respiration by genetically uncoupling ATP synthesis from electron transport resulted in potentiation of the killing effect of bactericidal antibiotics. This work identifies a link between antibiotic-induced cellular respiration and bactericidal lethality and demonstrates that bactericidal activity can be arrested by attenuated respiration and potentiated by accelerated respiration. Our data collectively show that antibiotics perturb the metabolic state of bacteria and that the metabolic state of bacteria impacts antibiotic efficacy.

  6. Respirable dust levels in coal, metal, and nonmetal mines

    SciTech Connect

    Watts, W.F. Jr.; Parker, D.R.

    1987-01-01

    The Bureau of Mines developed the Mine Inspection Data Analysis system (MIDAS). MIDAS is a computerized, industrial hygiene data base capable of statistically analyzing environmental data collected in coal and noncoal mines and mills by Mine Safety and Health Administration (MSHA) inspectors or mine operators. The objectives of this report are to describe the current contents of MIDAS, to report analyses of coal and noncoal mine respirable dust samples collected by MSHA inspectors, and to evaluate the proposed change in the metal and nonmetal respirable dust standard from a formula based upon the percentage of quartz identified in the sample to 100 ..mu..g/m/sup 3/ of respirable quartz.

  7. Molecular AND logic gate based on bacterial anaerobic respiration.

    PubMed

    Arugula, Mary Anitha; Shroff, Namita; Katz, Evgeny; He, Zhen

    2012-10-21

    Enzyme coding genes that integrate information for anaerobic respiration in Shewanella oneidensis MR-1 were used as input for constructing an AND logic gate. The absence of one or both genes inhibited electrochemically-controlled anaerobic respiration, while wild type bacteria were capable of accepting electrons from an electrode for DMSO reduction.

  8. BACTERIAL RESPIRATION OF ARSENIC AND SELENIUM. (R826105)

    EPA Science Inventory

    Abstract

    Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichme...

  9. Bacterial sorption of heavy metals.

    PubMed Central

    Mullen, M D; Wolf, D C; Ferris, F G; Beveridge, T J; Flemming, C A; Bailey, G W

    1989-01-01

    Four bacteria, Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa, were examined for the ability to remove Ag+, Cd2+, Cu2+, and La3+ from solution by batch equilibration methods. Cd and Cu sorption over the concentration range 0.001 to 1 mM was described by Freundlich isotherms. At 1 mM concentrations of both Cd2+ and Cu2+, P. aeruginosa and B. cereus were the most and least efficient at metal removal, respectively. Freundlich K constants indicated that E. coli was most efficient at Cd2+ removal and B. subtilis removed the most Cu2+. Removal of Ag+ from solution by bacteria was very efficient; an average of 89% of the total Ag+ was removed from the 1 mM solution, while only 12, 29, and 27% of the total Cd2+, Cu2+, and La3+, respectively, were sorbed from 1 mM solutions. Electron microscopy indicated that La3+ accumulated at the cell surface as needlelike, crystalline precipitates. Silver precipitated as discrete colloidal aggregates at the cell surface and occasionally in the cytoplasm. Neither Cd2+ nor Cu2+ provided enough electron scattering to identify the location of sorption. The affinity series for bacterial removal of these metals decreased in the order Ag greater than La greater than Cu greater than Cd. The results indicate that bacterial cells are capable of binding large quantities of different metals. Adsorption equations may be useful for describing bacterium-metal interactions with metals such as Cd and Cu; however, this approach may not be adequate when precipitation of metals occurs. Images PMID:2515800

  10. Dynamic subcellular localization of a respiratory complex controls bacterial respiration.

    PubMed

    Alberge, François; Espinosa, Leon; Seduk, Farida; Sylvi, Léa; Toci, René; Walburger, Anne; Magalon, Axel

    2015-01-01

    Respiration, an essential process for most organisms, has to optimally respond to changes in the metabolic demand or the environmental conditions. The branched character of their respiratory chains allows bacteria to do so by providing a great metabolic and regulatory flexibility. Here, we show that the native localization of the nitrate reductase, a major respiratory complex under anaerobiosis in Escherichia coli, is submitted to tight spatiotemporal regulation in response to metabolic conditions via a mechanism using the transmembrane proton gradient as a cue for polar localization. These dynamics are critical for controlling the activity of nitrate reductase, as the formation of polar assemblies potentiates the electron flux through the complex. Thus, dynamic subcellular localization emerges as a critical factor in the control of respiration in bacteria.

  11. Dynamic subcellular localization of a respiratory complex controls bacterial respiration

    PubMed Central

    Alberge, François; Espinosa, Leon; Seduk, Farida; Sylvi, Léa; Toci, René; Walburger, Anne; Magalon, Axel

    2015-01-01

    Respiration, an essential process for most organisms, has to optimally respond to changes in the metabolic demand or the environmental conditions. The branched character of their respiratory chains allows bacteria to do so by providing a great metabolic and regulatory flexibility. Here, we show that the native localization of the nitrate reductase, a major respiratory complex under anaerobiosis in Escherichia coli, is submitted to tight spatiotemporal regulation in response to metabolic conditions via a mechanism using the transmembrane proton gradient as a cue for polar localization. These dynamics are critical for controlling the activity of nitrate reductase, as the formation of polar assemblies potentiates the electron flux through the complex. Thus, dynamic subcellular localization emerges as a critical factor in the control of respiration in bacteria. DOI: http://dx.doi.org/10.7554/eLife.05357.001 PMID:26077726

  12. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth.

    PubMed

    Forte, Elena; Borisov, Vitaliy B; Falabella, Micol; Colaço, Henrique G; Tinajero-Trejo, Mariana; Poole, Robert K; Vicente, João B; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  13. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

    PubMed Central

    Forte, Elena; Borisov, Vitaliy B.; Falabella, Micol; Colaço, Henrique G.; Tinajero-Trejo, Mariana; Poole, Robert K.; Vicente, João B.; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  14. Effect of heavy metals on bacterial transport

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Olson, M. S.

    2010-12-01

    Adsorption of metals onto bacteria and soil takes place as stormwater runoff infiltrates into the subsurface. Changes in both bacterial surfaces and soil elemental content have been observed, and may alter the attachment of bacteria to soil surfaces. In this study, scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS) analyses were performed on soil samples equilibrated with synthetic stormwater amended with copper, lead and zinc. The results demonstrate the presence of copper and zinc on soil surfaces. To investigate bacterial attachment behavior, sets of batch sorption experiments were conducted on Escherichia Coli (E. coli) under different chemical conditions by varying solution compositions (nutrient solution vs synthetic stormwater). The adsorption data is best described using theoretical linear isotherms. The equilibrium coefficient (Kd) of E. coli is higher in synthetic stormwater than in nutrient solution without heavy metals. The adsorption of heavy metals onto bacterial surfaces significantly decreases their negative surface charge as determined via zeta potential measurements (-17.0±5.96mv for E. coli equilibrated with synthetic stormwater vs -21.6±5.45mv for E. coli equilibrated with nutrient solution), indicating that bacterial attachment may increase due to the attachment of metals onto bacterial surfaces and their subsequent change in surface charge. The attachment efficiency (α) of bacteria was also calculated and compared for both solution chemistries. Bacterial attachment efficiency (α) in synthetic stormwater is 0.997, which is twice as high as that in nutrient solution(α 0.465). The ratio of bacterial diameter : collector diameter suggests minimal soil straining during bacterial transport. Results suggest that the presence of metals in synthetic stormwater leads to an increase in bacterial attachment to soil surfaces. In terms of designing stormwater infiltration basins, the presence of heavy metals seems to

  15. Bioremoval of heavy metals by bacterial biomass.

    PubMed

    Aryal, Mahendra; Liakopoulou-Kyriakides, Maria

    2015-01-01

    Heavy metals are among the most common pollutants found in the environment. Health problems due to the heavy metal pollution become a major concern throughout the world, and therefore, various treatment technologies such as reverse osmosis, ion exchange, solvent extraction, chemical precipitation, and adsorption are adopted to reduce or eliminate their concentration in the environment. Biosorption is a cost-effective and environmental friendly technique, and it can be used for detoxification of heavy metals in industrial effluents as an alternative treatment technology. Biosorption characteristics of various bacterial species are reviewed here with respect to the results reported so far. The role of physical, chemical, and biological modification of bacterial cells for heavy metal removal is presented. The paper evaluates the different kinetic, equilibrium, and thermodynamic models used in bacterial sorption of heavy metals. Biomass characterization and sorption mechanisms as well as elution of metal ions and regeneration of biomass are also discussed. PMID:25471624

  16. Soil respiration and bacterial structure and function after 17 years of a reciprocal soil transplant experiment

    DOE PAGES

    Bond-Lamberty, Benjamin; Bolton, Harvey; Fansler, Sarah J.; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeff L.; Bailey, Vanessa L.

    2016-03-02

    The effects of climate change on soil organic matter—its structure, microbial community, carbon storage, and respiration response—remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampledmore » the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5 °C monthly maximum air temperature, +50 mm yr-1precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. Lastly, these results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even

  17. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment

    PubMed Central

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter—its structure, microbial community, carbon storage, and respiration response—remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  18. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    PubMed

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeffrey; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  19. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    PubMed

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeffrey; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  20. Effects of viral enrichment on bacterial production, respiration and growth efficiency

    NASA Astrophysics Data System (ADS)

    Bonilla-Findji, O.; Rochelle-Newall, E.; Weinbauer, M. G.; Gattuso, J.-P.

    2003-04-01

    Viruses are the most common biological agents in the sea. They can influence many ecological processes such as nutrient and carbon cycling, particle size distribution, algal bloom control, species diversity and gene transfer. As they are mainly bacteriophages they not only influence bacterial abundances but also potentially, the bacterial respiration and production, as has been suggested in by Fuhrman’s model in 1992 and a few recent experimental studies. Through their lytic action viruses can influence biogeochemical cycles and so affect the functioning of the whole marine ecosystem. In order to explore this hypothesis and provide some quantitative data we: (1) studied the effects of viruses on bacterial respiration (BR), production (BP) and growth efficiency (BGE) and (2) investigated whether these effects change over time. A viral enrichment experiment was performed in April and May 2002, where the bacterial community isolated from the Bay of Villefranche was exposed to three treatments: Vo (no viral addition), Vm (enrichment of 1-1.5 fold inactivated viruses) and V+ (enrichment of 1-1.5 fold active viruses). No virally induced effects on bacterial metabolism were observed in April but in May after 24 h of incubation, BR was stimulated by ca. 39% in V+ compared to Vo and by 20% relative to Vm. In the presence of active viruses, BP was repressed by ca. 40% compared to Vo and BGE was reduced by 48%. In May, viruses increased the total bacterial carbon demand (17% in V+ compared to Vo, and by 11% relative to Vm). Our results suggest that viruses seem to induce a shift in the specific role of bacterioplankton by reducing the carbon flow to the higher trophic levels and by stimulating the DOM ‡ bacteria ‡ CO2, N, P, Fe pathway.

  1. Physiological and electrochemical effects of different electron acceptors on bacterial anode respiration in bioelectrochemical systems.

    PubMed

    Yang, Yonggang; Xiang, Yinbo; Xia, Chunyu; Wu, Wei-Min; Sun, Guoping; Xu, Meiying

    2014-07-01

    To understand the interactions between bacterial electrode respiration and the other ambient bacterial electron acceptor reductions, alternative electron acceptors (nitrate, Fe2O3, fumarate, azo dye MB17) were added singly or multiply into Shewanella decolorationis microbial fuel cells (MFCs). All the added electron acceptors were reduced simultaneously with current generation. Adding nitrate or MB17 resulted in more rapid cell growth, higher flavin concentration and higher biofilm metabolic viability, but lower columbic efficiency (CE) and normalized energy recovery (NER) while the CE and NER were enhanced by Fe2O3 or fumarate. The added electron acceptors also significantly influenced the cyclic voltammetry profile of anode biofilm probably via altering the cytochrome c expression. The highest power density was observed in MFCs added with MB17 due to the electron shuttle role of the naphthols from MB17 reduction. The results provided important information for MFCs applied in practical environments where contains various electron acceptors.

  2. Bacterial Respiration and Growth Rates Affect the Feeding Preferences, Brood Size and Lifespan of Caenorhabditis elegans

    PubMed Central

    Yu, Li; Yan, Xiaomei; Ye, Chenglong; Zhao, Haiyan; Chen, Xiaoyun; Hu, Feng; Li, Huixin

    2015-01-01

    Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. PMID:26222828

  3. Are the actively respiring cells (CTC+) those responsible for bacterial production in aquatic environments?

    PubMed

    Servais, P; Agogué, H; Courties, C; Joux, F; Lebaron, P

    2001-04-01

    The 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) staining method is commonly and increasingly used to detect and to enumerate actively respiring cells (CTC+ cells) in aquatic systems. However, this method remains controversial since some authors promote this technique while others pointed out several drawbacks of the method. Using flow cytometry (FCM), we showed that CTC staining kinetics vary greatly from one sample to another. Therefore, there is no universal staining protocol that can be applied to aquatic bacterial communities. Furthermore, using (3)H-leucine incorporation, it was shown that the CTC dye has a rapid toxic effect on bacterial cells by inhibiting protein synthesis, a key physiological function. The coupling of radioactive labelling with cell sorting by FCM suggested that CTC+ cells contribute to less than 60% of the whole bacterial activity determined at the community level. From these results, it is clearly demonstrated that the CTC method is not valid to detect active bacteria, i.e. cells responsible for bacterial production.

  4. Effect of humic substance photodegradation on bacterial growth and respiration in lake water

    USGS Publications Warehouse

    Anesio, A.M.; Graneli, W.; Aiken, G.R.; Kieber, D.J.; Mopper, K.

    2005-01-01

    This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-??m-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H 2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by ???18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed ???10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates. Copyright ?? 2005, American Society for Microbiology. All Rights Reserved.

  5. Bacterial Diversity, Sediment Age and Organic Respiration in the Marine Sedimentary Environment

    NASA Astrophysics Data System (ADS)

    Walsh, E. A.; Kirkpatrick, J. B.; Pockalny, R. A.; Sauvage, J.; Sogin, M. L.; D'Hondt, S.

    2014-12-01

    Subseafloor sediment hosts to a large1, taxonomically rich2 and metabolically diverse3 microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here we show that subseafloor bacterial richness varies directly with sediment age and net rate of organic-fueled respiration. We examined three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), with sediment depths to 404 meters below seafloor. At all locations, taxonomic richness decreases exponentially with increasing sediment age. Richness declines most rapidly for a few hundred thousand years after sediment deposition. This profile generally matches the canonical relationship between rates of organic oxidation and sediment age 4. To examine the potential link between organic oxidation and taxonomic richness we used pore-water chemical profiles to quantify net rates of organic respiration at the three open-ocean sites (the chemical profiles of the ocean-margin site are not in diffusive steady state). Taxonomic richness and total rate of organic-fueled respiration are highest at the high productivity Bering Sea site and lower at the moderate productivity equatorial Pacific sites. At each of these sites, organic-fueled respiration rate and taxonomic richness are highest at the surface and decline together as sediment depth and age increase. To our knowledge, this is the first evidence that taxonomic richness is closely linked to organic-fueled respiration rate and sediment age in subseafloor sediment. References1. Kallmeyer, J., Pockalny, R., Adhikari, R. R., Smith, D. C. & D'Hondt, S. Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1203849109 (2012). 2. Inagaki, F. et al. Proceedings of the National Academy of Sciences 103, 2815-2820 (2006). 3. D'Hondt, S. et al. Science 306, 2216-2221, doi:10.1126/science.1101155 (2004). 4. Middelburg, J. J. Geochimica et Cosmochimica Acta 53

  6. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

    2010-09-28

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  7. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R.; O'Neill, Hugh M.; Jansen, Valerie Malyvanh; Woodward, Jonathan

    2011-06-07

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  8. Exploring the biochemistry at the extracellular redox frontier of bacterial mineral Fe(III) respiration

    SciTech Connect

    Richardson, David J.; Edwards, Marcus; White, Gaye F.; Baiden, Nanakow; Hartshorne, Robert S.; Fredrickson, Jim K.; Shi, Liang; Zachara, John M.; Gates, Andrew J.; Butt, Julea N.; Clarke, Thomas

    2012-06-01

    Many species of the bacterial Shewanella genus are notable for their ability to respire in anoxic environments utilizing insoluble minerals of Fe(III) and Mn(IV) as extracellular electron acceptors. In Shewanella oneidensis, the process is dependent on the decahaem electron-transport proteins that lie at the extracellular face of the outer membrane where they can contact the insoluble mineral substrates. These extracellular proteins are charged with electrons provided by an inter-membrane electron-transfer pathway that links the extracellular face of the outer membrane with the inner cytoplasmic membrane and thereby intracellular electron sources. In the present paper, we consider the common structural features of two of these outermembrane decahaem cytochromes, MtrC and MtrF, and bring this together with biochemical, spectroscopic and voltammetric data to identify common and distinct properties of these prototypical members of different clades of the outer-membrane decahaem cytochrome superfamily.

  9. Bacterial Adaptation of Respiration from Oxic to Microoxic and Anoxic Conditions: Redox Control

    PubMed Central

    Bueno, Emilio; Mesa, Socorro; Bedmar, Eulogio J.; Richardson, David J.

    2012-01-01

    Abstract Under a shortage of oxygen, bacterial growth can be faced mainly by two ATP-generating mechanisms: (i) by synthesis of specific high-affinity terminal oxidases that allow bacteria to use traces of oxygen or (ii) by utilizing other substrates as final electron acceptors such as nitrate, which can be reduced to dinitrogen gas through denitrification or to ammonium. This bacterial respiratory shift from oxic to microoxic and anoxic conditions requires a regulatory strategy which ensures that cells can sense and respond to changes in oxygen tension and to the availability of other electron acceptors. Bacteria can sense oxygen by direct interaction of this molecule with a membrane protein receptor (e.g., FixL) or by interaction with a cytoplasmic transcriptional factor (e.g., Fnr). A third type of oxygen perception is based on sensing changes in redox state of molecules within the cell. Redox-responsive regulatory systems (e.g., ArcBA, RegBA/PrrBA, RoxSR, RegSR, ActSR, ResDE, and Rex) integrate the response to multiple signals (e.g., ubiquinone, menaquinone, redox active cysteine, electron transport to terminal oxidases, and NAD/NADH) and activate or repress target genes to coordinate the adaptation of bacterial respiration from oxic to anoxic conditions. Here, we provide a compilation of the current knowledge about proteins and regulatory networks involved in the redox control of the respiratory adaptation of different bacterial species to microxic and anoxic environments. Antioxid. Redox Signal. 16, 819–852. PMID:22098259

  10. The impact of dissolved organic carbon and bacterial respiration on pCO2 in experimental sea ice

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Kotovitch, M.; Kaartokallio, H.; Moreau, S.; Tison, J.-L.; Kattner, G.; Dieckmann, G.; Thomas, D. N.; Delille, B.

    2016-02-01

    Previous observations have shown that the partial pressure of carbon dioxide (pCO2) in sea ice brines is generally higher in Arctic sea ice compared to those from the Antarctic sea ice, especially in winter and early spring. We hypothesized that these differences result from the higher dissolved organic carbon (DOC) content in Arctic seawater: Higher concentrations of DOC in seawater would be reflected in a greater DOC incorporation into sea ice, enhancing bacterial respiration, which in turn would increase the pCO2 in the ice. To verify this hypothesis, we performed an experiment using two series of mesocosms: one was filled with seawater (SW) and the other one with seawater with an addition of filtered humic-rich river water (SWR). The addition of river water increased the DOC concentration of the water from a median of 142 μmol Lwater-1 in SW to 249 μmol Lwater-1 in SWR. Sea ice was grown in these mesocosms under the same physical conditions over 19 days. Microalgae and protists were absent, and only bacterial activity has been detected. We measured the DOC concentration, bacterial respiration, total alkalinity and pCO2 in sea ice and the underlying seawater, and we calculated the changes in dissolved inorganic carbon (DIC) in both media. We found that bacterial respiration in ice was higher in SWR: median bacterial respiration was 25 nmol C Lice-1 h-1 compared to 10 nmol C Lice-1 h-1 in SW. pCO2 in ice was also higher in SWR with a median of 430 ppm compared to 356 ppm in SW. However, the differences in pCO2 were larger within the ice interiors than at the surfaces or the bottom layers of the ice, where exchanges at the air-ice and ice-water interfaces might have reduced the differences. In addition, we used a model to simulate the differences of pCO2 and DIC based on bacterial respiration. The model simulations support the experimental findings and further suggest that bacterial growth efficiency in the ice might approach 0.15 and 0.2. It is thus credible

  11. Pharmaceuticals suppress algal growth and microbial respiration and alter bacterial communities in stream biofilms.

    PubMed

    Rosi-Marshall, Emma J; Kincaid, Dustin W; Bechtold, Heather A; Royer, Todd V; Rojas, Miguel; Kelly, John J

    2013-04-01

    Pharmaceutical and personal care products are ubiquitous in surface waters but their effects on aquatic biofilms and associated ecosystem properties are not well understood. We measured in situ responses of stream biofilms to six common pharmaceutical compounds (caffeine, cimetidine, ciprofloxacin, diphenhydramine, metformin, ranitidine, and a mixture of each) by deploying pharmaceutical-diffusing substrates in streams in Indiana, Maryland, and New York. Results were consistent across seasons and geographic locations. On average, algal biomass was suppressed by 22%, 4%, 22%, and 18% relative to controls by caffeine, ciprofloxacin, diphenhydramine, and the mixed treatment, respectively. Biofilm respiration was significantly suppressed by caffeine (53%), cimetidine (51%), ciprofloxacin (91%), diphenhydramine (63%), and the mixed treatment (40%). In autumn in New York, photosynthesis was also significantly suppressed by diphenhydramine (99%) and the mixed treatment (88%). Pyrosequencing of 16S rRNA genes was used to examine the effects of caffeine and diphenhydramine on biofilm bacterial community composition at the three sites. Relative to the controls, diphenhydramine exposure significantly altered bacterial community composition and resulted in significant relative increases in Pseudomonas sp. and decreases in Flavobacterium sp. in all three streams. These ubiquitous pharmaceuticals, alone or in combination, influenced stream biofilms, which could have consequences for higher trophic levels and important ecosystem processes.

  12. Contrasting short-term antibiotic effects on respiration and bacterial growth compromises the validity of the selective respiratory inhibition technique to distinguish fungi and bacteria.

    PubMed

    Rousk, Johannes; Demoling, Louise Aldén; Bååth, Erland

    2009-07-01

    The selective inhibition (SI) technique has been widely used to resolve fungal and bacterial biomass. By studying bacterial growth (leucine/thymidine incorporation) and respiration simultaneously, this study demonstrates that the inhibitors the SI technique is based on do not efficiently or specifically resolve fungal and bacterial contributions to respiration. At concentrations that completely inhibited bacterial growth, the bactericide streptomycin had no influence on the SI technique's respiration measurement, and complete inhibition of bacterial growth using oxytetracycline resulted in marginal respiration reductions. The fungicides captan and benomyl severely inhibited non-target bacterial growth. Cycloheximide did not reduce bacterial growth at moderate concentrations, but the cycloheximide respiration reduction was no higher in a soil with more fungal biomass, casting doubt on its ability to discriminate fungal respiration contribution. Conclusions regarding bacteria and fungi based on the SI technique using these inhibitors are thus compromised. The inhibition of glucose-activated respiration by the bactericide bronopol appeared to correlate with bacterial growth inhibition, however. Bronopol, combined with growth-based techniques, could aid development of a new framework to resolve decomposer ecology in soil.

  13. Bacterial drug tolerance under clinical conditions is governed by anaerobic adaptation but not anaerobic respiration.

    PubMed

    Hemsley, Claudia M; Luo, Jamie X; Andreae, Clio A; Butler, Clive S; Soyer, Orkun S; Titball, Richard W

    2014-10-01

    Noninherited antibiotic resistance is a phenomenon whereby a subpopulation of genetically identical bacteria displays phenotypic tolerance to antibiotics. We show here that compared to Escherichia coli, the clinically relevant genus Burkholderia displays much higher levels of cells that tolerate ceftazidime. By measuring the dynamics of the formation of drug-tolerant cells under conditions that mimic in vivo infections, we show that in Burkholderia bacteria, oxygen levels affect the formation of these cells. The drug-tolerant cells are characterized by an anaerobic metabolic signature and can be eliminated by oxygenating the system or adding nitrate. The transcriptome profile suggests that these cells are not dormant persister cells and are likely to be drug tolerant as a consequence of the upregulation of anaerobic nitrate respiration, efflux pumps, β-lactamases, and stress response proteins. These findings have important implications for the treatment of chronic bacterial infections and the methodologies and conditions that are used to study drug-tolerant and persister cells in vitro.

  14. Effective inhibition of bacterial respiration and growth by CuO microspheres composed of thin nanosheets.

    PubMed

    Wahab, Rizwan; Khan, Shams Tabrez; Dwivedi, Sourabh; Ahamed, Maqusood; Musarrat, Javed; Al-Khedhairy, Abdulaziz A

    2013-11-01

    This study describes the synthesis, characterization and biocidal potential of copper oxide micro-spheres composed of thin sheets (CuOMSs-Ths). Microscopic observations of synthesized CuOMSs-Ths revealed the clusters of thin sheets arranged in small flower like micro-spheres. Diameter of each micro-sphere was determined in the range of 2-3 μm, whereas the size of each sheet was ∼ 80 nm. These micro-flowers like nanostructures were synthesized using copper nitrate hexahydrate and sodium hydroxide via solution process. The CuOMSs-Ths exhibited a broad-spectrum anti-bacterial activity involving significant growth inhibition of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus. The IC50 values of these engineered NPs against E. coli, P. aeruginosa, S. aureus and M. luteus were determined to be 195, 200, 131 and 184 μg/ml, respectively. Also, the respiration of Gram+ ve organisms (M. luteus and S. aureus) was inhibited significantly (p value < 0.005) at relatively lower concentrations of 12.5 and 50 μg/ml, respectively, as compared to the Gram- ve bacteria (E. coli and P. aeruginosa), where the growth inhibition occurred at a much greater concentration of 100 μg/ml. The results explicitly demonstrated anti-microbial activity of CuOMSs-Ths with a higher level of toxicity against the Gram+ ve vis-a-vis Gram- ve bacteria.

  15. Effective inhibition of bacterial respiration and growth by CuO microspheres composed of thin nanosheets.

    PubMed

    Wahab, Rizwan; Khan, Shams Tabrez; Dwivedi, Sourabh; Ahamed, Maqusood; Musarrat, Javed; Al-Khedhairy, Abdulaziz A

    2013-11-01

    This study describes the synthesis, characterization and biocidal potential of copper oxide micro-spheres composed of thin sheets (CuOMSs-Ths). Microscopic observations of synthesized CuOMSs-Ths revealed the clusters of thin sheets arranged in small flower like micro-spheres. Diameter of each micro-sphere was determined in the range of 2-3 μm, whereas the size of each sheet was ∼ 80 nm. These micro-flowers like nanostructures were synthesized using copper nitrate hexahydrate and sodium hydroxide via solution process. The CuOMSs-Ths exhibited a broad-spectrum anti-bacterial activity involving significant growth inhibition of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus. The IC50 values of these engineered NPs against E. coli, P. aeruginosa, S. aureus and M. luteus were determined to be 195, 200, 131 and 184 μg/ml, respectively. Also, the respiration of Gram+ ve organisms (M. luteus and S. aureus) was inhibited significantly (p value < 0.005) at relatively lower concentrations of 12.5 and 50 μg/ml, respectively, as compared to the Gram- ve bacteria (E. coli and P. aeruginosa), where the growth inhibition occurred at a much greater concentration of 100 μg/ml. The results explicitly demonstrated anti-microbial activity of CuOMSs-Ths with a higher level of toxicity against the Gram+ ve vis-a-vis Gram- ve bacteria. PMID:23816782

  16. Using Reactive Transport Modeling to Understand Changes in Electrical Conductivity Associated with Bacterial Growth and Respiration

    NASA Astrophysics Data System (ADS)

    Regberg, A. B.; Singha, K.; Picardal, F.; Brantley, S. L.

    2011-12-01

    Previous research has linked measured changes in the bulk electrical conductivity (σb) of water-saturated sediments to the respiration and growth of anaerobic bacteria. If the mechanism causing this signal is understood and characterized it could be used to identify and monitor zones of bacterial activity in the subsurface. The 1-D reactive transport model PHREEQC was used to understand σb signals by modeling chemical gradients within two column reactors and corresponding changes in effluent chemistry. The flow-through column reactors were packed with Fe(III)-bearing sediment from Oyster, VA and inoculated with an environmental consortia of microorganisms. Influent in the first reactor was amended with 1mM Na-acetate to encourage the growth of iron-reducing bacteria. Influent in the second reactor was amended with 0.1mM Na-Acetate and 2mM NaNO3 to encourage the growth of nitrate-reducing bacteria. While effluent concentrations of acetate, Fe(II), NO3-, NO2-, and NH4+ remained at steady state, we measured a 3-fold increase (0.055 S/m - 0.2 S/m) in σb in the iron-reducing column and a 10-fold increase in σb (0.07 S/m - 0.8 S/m) in the nitrate-reducing column over 198 days. The ionic strength in both reactors remained constant through time indicating that the measured increases in σb were not caused by changing effluent concentrations. PHREEQC successfully matched the measured changes in effluent concentrations for both columns when the reaction database was modified in the following manner. For the iron-reducing column, kinetic expressions governing the rate of iron reduction, the rate of bacterial growth, and the production of methane were added to the reaction database. Additionally, surface adsorption and cation exchange reactions were added so that the model was consistent with measured effluent chemistry. For the nitrate-reducing column, kinetic expressions governing nitrate reduction and bacterial growth were added to the reaction database. Additionally

  17. Vegetation affects the relative abundances of dominant soil bacterial taxa and soil respiration rates in an upland grassland soil.

    PubMed

    Thomson, Bruce C; Ostle, Nick; McNamara, Niall; Bailey, Mark J; Whiteley, Andrew S; Griffiths, Robert I

    2010-02-01

    Plant-derived organic matter inputs are thought to be a key driver of soil bacterial community composition and associated soil processes. We sought to investigate the role of acid grassland vegetation on soil bacterial community structure by assessing bacterial diversity in combination with other soil variables in temporally and spatially distinct samples taken from a field-based plant removal experiment. Removal of aboveground vegetation resulted in reproducible differences in soil properties, soil respiration and bacterial diversity. Vegetated soils had significantly increased carbon and nitrogen concentrations and exhibited higher rates of respiration. Molecular analyses revealed that the soils were broadly dominated by Alphaproteobacterial and Acidobacterial lineages, with increased abundances of Alphaproteobacteria in vegetated soils and more Acidobacteria in bare soils. This field-based study contributes to a growing body of evidence documenting the effect of soil nutrient status on the relative abundances of dominant soil bacterial taxa, with Proteobacterial taxa dominating over Acidobacteria in soils exhibiting higher rates of C turnover. Furthermore, we highlight the role of aboveground vegetation in mediating this effect by demonstrating that plant removal can alter the relative abundances of dominant soil taxa with concomitant changes in soil CO(2)-C efflux.

  18. Respirable-dust levels in coal, metal, and nonmetal mines. Information Circular/1987

    SciTech Connect

    Watts, W.F.; Parker, D.R.

    1987-01-01

    The objectives of this report are to describe the current contents of Mine Inspection Data Analysis System (MIDAS), to report analyses of coal and noncoal mine respirable-dust samples collected by Mine Health and Safety Administration (MSHA) inspectors, and to evaluate the proposed change in the metal and nonmetal respirable dust standard from a formula based upon the percentage of quartz identified in the sample to 100 micrograms/cu m of respirable quartz. Based on samples collected by MSHA inspectors, changing the noncoal respirable-dust standard would result in 4% fewer samples with dust concentrations exceeding the standard. Analysis of respirable-coal-dust data collected by MSHA inspectors showed that mines with longwall plows or shears had the highest geometric mean concentrations (1.64 and 1.29mg/cu m, respectively). Mine operations using continuous rippers outnumbered longwall mine operations about 10 to 1 and had a geometric mean concentration of 0.66 mg/cu m.

  19. Microbial metal reduction by members of the genus Shewanella: novel strategies for anaerobic respiration

    SciTech Connect

    Dichristina, Thomas; Bates, David J.; Burns, Justin L.; Dale, Jason R.; Payne, Amanda N.

    2006-01-01

    Metal-reducing members of the genus Shewanella are important components of the microbial community residing in redox-stratified freshwater and marine environments. Metal-reducing gram-negative bacteria such as Shewanella, however, are presented with a unique physiological challenge: they are required to respire anaerobically on terminal electron acceptors which are either highly insoluble (Fe(III)- and Mn(IV)-oxides) and reduced to soluble end-products or highly soluble (U(VI) and Tc(VII)) and reduced to insoluble end-products. To overcome physiological problems associated with metal solubility, metal-respiring Shewanella are postulated to employ a variety of novel respiratory strategies not found in other gram-negative bacteria which respire on soluble electron acceptors such as O2, NO3 and SO4. The following chapter highlights the latest findings on the molecular mechanism of Fe(III), U(VI) and Tc(VII) reduction by Shewanella, with particular emphasis on electron transport chain physiology.

  20. EDTA addition enhances bacterial respiration activities and hydrocarbon degradation in bioaugmented and non-bioaugmented oil-contaminated desert soils.

    PubMed

    Al Kharusi, Samiha; Abed, Raeid M M; Dobretsov, Sergey

    2016-03-01

    The low number and activity of hydrocarbon-degrading bacteria and the low solubility and availability of hydrocarbons hamper bioremediation of oil-contaminated soils in arid deserts, thus bioremediation treatments that circumvent these limitations are required. We tested the effect of Ethylenediaminetetraacetic acid (EDTA) addition, at different concentrations (i.e. 0.1, 1 and 10 mM), on bacterial respiration and biodegradation of Arabian light oil in bioaugmented (i.e. with the addition of exogenous alkane-degrading consortium) and non-bioaugmented oil-contaminated desert soils. Post-treatment shifts in the soils' bacterial community structure were monitored using MiSeq sequencing. Bacterial respiration, indicated by the amount of evolved CO2, was highest at 10 mM EDTA in bioaugmented and non-bioaugmented soils, reaching an amount of 2.2 ± 0.08 and 1.6 ± 0.02 mg-CO2 g(-1) after 14 days of incubation, respectively. GC-MS revealed that 91.5% of the C14-C30 alkanes were degraded after 42 days when 10 mM EDTA and the bacterial consortium were added together. MiSeq sequencing showed that 78-91% of retrieved sequences in the original soil belonged to Deinococci, Alphaproteobacteria, Gammaproteobacteia and Bacilli. The same bacterial classes were detected in the 10 mM EDTA-treated soils, however with slight differences in their relative abundances. In the bioaugmented soils, only Alcanivorax sp. MH3 and Parvibaculum sp. MH21 from the exogenous bacterial consortium could survive until the end of the experiment. We conclude that the addition of EDTA at appropriate concentrations could facilitate biodegradation processes by increasing hydrocarbon availability to microbes. The addition of exogenous oil-degrading bacteria along with EDTA could serve as an ideal solution for the decontamination of oil-contaminated desert soils.

  1. Influences of Mn(II) and V(IV) on Bacterial Surface Chemistry and Metal Reactivity

    NASA Astrophysics Data System (ADS)

    French, S.; Fakra, S.; Glasauer, S.

    2009-05-01

    Microorganisms in terrestrial and marine environments are typically bathed in solutions that contain a range of metal ions, toxic and beneficial. Bacteria such as Shewanella putrefaciens CN32 are metabolically versatile in their respiration, and the reductive dissolution of widely dispersed metals such as Fe(III), Mn(IV), or V(V) can present unique challenges if nearby bodies of water are used for irrigation or drinking. In redox transition zones, dissimilatory metal reduction (DMR) by bacteria can lead to generation of high concentrations of soluble metals. It has been shown that metals will associate with negatively charged bacterial membranes, and the mechanisms of metal reduction are well defined for many species of bacteria. The interaction of metals with the cell wall during DMR is, however, not well documented; very little is known about the interaction of respired transition metals with membrane lipids. Furthermore, bacterial surfaces tend to change in response to their immediate environments. Variations in conditions such as oxygen or metal presence may affect surface component composition, including availability of metal reactive sites. Our research seeks to characterize the biochemical nature of metal-membrane interactions, as well as identify the unique changes at the cell surface that arise as a result of metal presence in their environments. We have utilized scanning transmission X-ray microscopy (STXM) to examine the dynamics of soluble Mn(II) and V(IV) interactions with purified bacterial membranes rather than whole cells. This prevents intracellular interferences, and allows for near edge X-ray absorption fine structure (NEXAFS) spectroscopic analyses of cell surface and surface-associated components. NEXAFS spectra for carbon, nitrogen, and oxygen edges indicate that Mn(II) and V(IV) induce biological modifications of the cell membrane in both aerobic and anaerobic conditions. These changes depend not only on the metal, but also on the presence of

  2. Comparative Genomics Analysis and Phenotypic Characterization of Shewanella putrefaciens W3-18-1: Anaerobic Respiration, Bacterial Microcompartments, and Lateral Flagella

    SciTech Connect

    Qiu, D.; Tu, Q.; He, Zhili; Zhou, Jizhong

    2010-05-17

    Respiratory versatility and psychrophily are the hallmarks of Shewanella. The ability to utilize a wide range of electron acceptors for respiration is due to the large number of c-type cytochrome genes present in the genome of Shewanella strains. More recently the dissimilatory metal reduction of Shewanella species has been extensively and intensively studied for potential applications in the bioremediation of radioactive wastes of groundwater and subsurface environments. Multiple Shewanella genome sequences are now available in the public databases (Fredrickson et al., 2008). Most of the sequenced Shewanella strains were isolated from marine environments and this genus was believed to be of marine origin (Hau and Gralnick, 2007). However, the well-characterized model strain, S. oneidensis MR-1, was isolated from the freshwater lake sediment of Lake Oneida, New York (Myers and Nealson, 1988) and similar bacteria have also been isolated from other freshwater environments (Venkateswaran et al., 1999). Here we comparatively analyzed the genome sequence and physiological characteristics of S. putrefaciens W3-18-1 and S. oneidensis MR-1, isolated from the marine and freshwater lake sediments, respectively. The anaerobic respirations, carbon source utilization, and cell motility have been experimentally investigated. Large scale horizontal gene transfers have been revealed and the genetic divergence between these two strains was considered to be critical to the bacterial adaptation to specific habitats, freshwater or marine sediments.

  3. Carbon fluxes in the Canadian Arctic: patterns and drivers of bacterial abundance, production and respiration on the Beaufort Sea margin

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Jeffrey, W. H.; Babin, M.; Bélanger, S.; Benner, R.; Marie, D.; Matsuoka, A.; Raimbault, P.; Joux, F.

    2012-05-01

    During August 2009, measurements of bacterial abundance and nucleic acid content were made along with production and respiration in coastal waters of the Beaufort Sea (Arctic Ocean), an area influenced by the Mackenzie River inflow. The main purpose was to evaluate bacterial organic carbon processing with respect to local sources, mainly primary production and river inputs. Bacterial production and abundance generally decreased from river to offshore waters and from surface to deep waters. In contrast, the percentage of high nucleic acid bacteria was higher in deep waters rather than in surface or river waters. Statistical analyses indicated that bacterial production was primarily controlled by temperature and the availability of labile organic matter, as indicated by total dissolved amino acid concentrations. Direct comparisons of bacterial carbon demand and primary production indicated net heterotrophy was common in shelf waters. Net autotrophy was observed at stations in the Mackenzie River plume, suggesting that the carbon fixed in plume waters helped fuel net heterotrophy in the Beaufort Sea margin.

  4. Carbon fluxes in the Canadian Arctic: patterns and drivers of bacterial abundance, production and respiration on the Beaufort Sea margin

    NASA Astrophysics Data System (ADS)

    Ortega-Retuerta, E.; Jeffrey, W. H.; Babin, M.; Bélanger, S.; Benner, R.; Marie, D.; Matsuoka, A.; Raimbault, P.; Joux, F.

    2012-09-01

    During August 2009, measurements of bacterial abundance and nucleic acid content were made along with production and respiration in coastal waters of the Beaufort Sea (Arctic Ocean), an area influenced by the Mackenzie River inflow. The main purpose was to evaluate bacterial organic carbon processing with respect to local sources, mainly primary production and river inputs. Bacterial production and abundance generally decreased from river to offshore waters and from surface to deep waters. In contrast, the percentage of high nucleic acid bacteria was higher in deep waters rather than in surface or river waters. Statistical analyses indicated that bacterial production was primarily controlled by temperature and the availability of labile organic matter, as indicated by total dissolved amino acid concentrations. Direct comparisons of bacterial carbon demand and primary production indicated net heterotrophy was common in shelf waters. Net autotrophy was observed at stations in the Mackenzie River plume, suggesting that the carbon fixed in plume waters helped fuel net heterotrophy in the Beaufort Sea margin.

  5. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R.; O'Neill, Hugh M.; Jansen, Valerie Malyvanh; Woodward, Jonathan

    2006-01-17

    The employment of metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The fuel cell includes an electrolyte membrane comprising a membrane support structure comprising bacterial cellulose, an anode disposed on one side of the electrolyte membrane, and a cathode disposed on an opposite side of the electrolyte membrane. At least one of the anode and the cathode comprises an electrode support structure comprising bacterial cellulose, and a catalyst disposed in or on the electrode support structure.

  6. Molecular characterization of bacterial respiration of minerals. Final technical report, March 1, 1985--February 29, 1996

    SciTech Connect

    Blake, R. II

    1996-08-01

    The goals of this project were to continue the identification, separation, and characterization of the cellular components necessary for aerobic respiration on iron, and to initiate an investigation of the molecular principles whereby these bacteria recognize and adhere to their insoluble inorganic substrates. Progress is described.

  7. A Diverse Community of Metal(loid) Oxide Respiring Bacteria Is Associated with Tube Worms in the Vicinity of the Juan de Fuca Ridge Black Smoker Field.

    PubMed

    Maltman, Chris; Walter, Graham; Yurkov, Vladimir

    2016-01-01

    Epibiotic bacteria associated with tube worms living in the vicinity of deep sea hydrothermal vents of the Juan de Fuca Ridge in the Pacific Ocean were investigated for the ability to respire anaerobically on tellurite, tellurate, selenite, selenate, metavanadate and orthovanadate as terminal electron acceptors. Out of 107 isolates tested, 106 were capable of respiration on one or more of these oxides, indicating that metal(loid) oxide based respiration is not only much more prevalent in nature than is generally believed, but also is an important mode of energy generation in the habitat. Partial 16S rRNA gene sequencing revealed the bacterial community to be rich and highly diverse, containing many potentially new species. Furthermore, it appears that the worms not only possess a close symbiotic relationship with chemolithotrophic sulfide-oxidizing bacteria, but also with the metal(loid) oxide transformers. Possibly they protect the worms through reduction of the toxic compounds that would otherwise be harmful to the host.

  8. A Diverse Community of Metal(loid) Oxide Respiring Bacteria Is Associated with Tube Worms in the Vicinity of the Juan de Fuca Ridge Black Smoker Field

    PubMed Central

    Maltman, Chris; Walter, Graham; Yurkov, Vladimir

    2016-01-01

    Epibiotic bacteria associated with tube worms living in the vicinity of deep sea hydrothermal vents of the Juan de Fuca Ridge in the Pacific Ocean were investigated for the ability to respire anaerobically on tellurite, tellurate, selenite, selenate, metavanadate and orthovanadate as terminal electron acceptors. Out of 107 isolates tested, 106 were capable of respiration on one or more of these oxides, indicating that metal(loid) oxide based respiration is not only much more prevalent in nature than is generally believed, but also is an important mode of energy generation in the habitat. Partial 16S rRNA gene sequencing revealed the bacterial community to be rich and highly diverse, containing many potentially new species. Furthermore, it appears that the worms not only possess a close symbiotic relationship with chemolithotrophic sulfide-oxidizing bacteria, but also with the metal(loid) oxide transformers. Possibly they protect the worms through reduction of the toxic compounds that would otherwise be harmful to the host. PMID:26914590

  9. A Diverse Community of Metal(loid) Oxide Respiring Bacteria Is Associated with Tube Worms in the Vicinity of the Juan de Fuca Ridge Black Smoker Field.

    PubMed

    Maltman, Chris; Walter, Graham; Yurkov, Vladimir

    2016-01-01

    Epibiotic bacteria associated with tube worms living in the vicinity of deep sea hydrothermal vents of the Juan de Fuca Ridge in the Pacific Ocean were investigated for the ability to respire anaerobically on tellurite, tellurate, selenite, selenate, metavanadate and orthovanadate as terminal electron acceptors. Out of 107 isolates tested, 106 were capable of respiration on one or more of these oxides, indicating that metal(loid) oxide based respiration is not only much more prevalent in nature than is generally believed, but also is an important mode of energy generation in the habitat. Partial 16S rRNA gene sequencing revealed the bacterial community to be rich and highly diverse, containing many potentially new species. Furthermore, it appears that the worms not only possess a close symbiotic relationship with chemolithotrophic sulfide-oxidizing bacteria, but also with the metal(loid) oxide transformers. Possibly they protect the worms through reduction of the toxic compounds that would otherwise be harmful to the host. PMID:26914590

  10. An annual survey of bacterial production, respiration and ectoenzyme activity in coastal NW Mediterranean waters: temperature and resource controls.

    PubMed

    Céa, B; Lefèvre, D; Chirurgien, L; Raimbault, P; Garcia, N; Charrière, B; Grégori, G; Ghiglione, J F; Barani, A; Lafont, M; Van Wambeke, F

    2015-09-01

    We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm(-3), NO3 = 0.55 μmol dm(-3) and PO4 = 0.04 μmol dm(-3)). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm-(3) h-(1) and bacterial growth efficiency varied from 1 to 39%, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem.

  11. Bacterial community structure and function along a heavy metal gradient

    SciTech Connect

    Dean-Ross, D. ); Mills, A.L. )

    1989-08-01

    The response to the planktonic, sediment, and epilithic bacterial communities to increasing concentrations of heavy metals was determined in a polluted river. None of the communities demonstrated a pollution-related effect on bacterial numbers (viable and total), heterotrophic activity, resistance to Pb or Cu, or species diversity as determined by either the Shannon-Wiener diversity index or rarefaction. The lack of correlation between concentrations of heavy metals and resistance in the sediment bacterial community was investigated and found to be due at least in part to the high pH of the river water and the resultant reduction in heavy metal toxicity. The three different communities demonstrated characteristic profiles based on the relative abundances of bacterial strains grouped according to functional similarities.

  12. The environmental controls that govern the end product of bacterial nitrate respiration

    SciTech Connect

    Kraft, Beate; Tegetmeyer, Halina E.; Sharma, Ritin; Klotz, Martin G.; Ferdelman, Timothy G.; Hettich, Robert L.; Geelhoed, Jeanine S.; Strous, Marc

    2014-08-08

    In the biogeochemical nitrogen cycle, microbial respiration processes compete for nitrate as an electron acceptor. Denitrification converts nitrate into nitrogenous gas and thus removes fixed nitrogen from the biosphere, whereas ammonification converts nitrate into ammonium, which is directly reusable by primary producers. In this paper, we combined multiple parallel long-term incubations of marine microbial nitrate-respiring communities with isotope labeling and metagenomics to unravel how specific environmental conditions select for either process. Microbial generation time, supply of nitrite relative to nitrate, and the carbon/nitrogen ratio were identified as key environmental controls that determine whether nitrite will be reduced to nitrogenous gas or ammonium. Finally, our results define the microbial ecophysiology of a biogeochemical feedback loop that is key to global change, eutrophication, and wastewater treatment.

  13. The environmental controls that govern the end product of bacterial nitrate respiration

    DOE PAGES

    Kraft, Beate; Tegetmeyer, Halina E.; Sharma, Ritin; Klotz, Martin G.; Ferdelman, Timothy G.; Hettich, Robert L.; Geelhoed, Jeanine S.; Strous, Marc

    2014-08-08

    In the biogeochemical nitrogen cycle, microbial respiration processes compete for nitrate as an electron acceptor. Denitrification converts nitrate into nitrogenous gas and thus removes fixed nitrogen from the biosphere, whereas ammonification converts nitrate into ammonium, which is directly reusable by primary producers. In this paper, we combined multiple parallel long-term incubations of marine microbial nitrate-respiring communities with isotope labeling and metagenomics to unravel how specific environmental conditions select for either process. Microbial generation time, supply of nitrite relative to nitrate, and the carbon/nitrogen ratio were identified as key environmental controls that determine whether nitrite will be reduced to nitrogenous gasmore » or ammonium. Finally, our results define the microbial ecophysiology of a biogeochemical feedback loop that is key to global change, eutrophication, and wastewater treatment.« less

  14. Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.

    PubMed

    Ilyas, A; Persson, K M; Persson, M

    2015-09-01

    A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse.

  15. Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.

    PubMed

    Ilyas, A; Persson, K M; Persson, M

    2015-09-01

    A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse. PMID:25999368

  16. Key respiratory genes elucidate bacterial community respiration in a seasonally anoxic estuary.

    PubMed

    Eggleston, Erin M; Lee, Dong Y; Owens, Michael S; Cornwell, Jeffrey C; Crump, Byron C; Hewson, Ian

    2015-07-01

    Intense annual spring phytoplankton blooms and thermohaline stratification lead to anoxia in Chesapeake Bay bottom waters. Once oxygen becomes depleted in the system, microbial communities use energetically favourable alternative electron acceptors for respiration. The extent to which changes in respiration are reflected in community gene expression have only recently been investigated. Metatranscriptomes prepared from near-bottom water plankton over a 4-month time series in central Chesapeake Bay demonstrated changes consistent with terminal electron acceptor availability. The frequency of respiration-related genes in metatranscriptomes was examined by BLASTx against curated databases of genes intimately and exclusively involved in specific electron acceptor utilization pathways. The relative expression of genes involved in denitrification and dissimilatory nitrate reduction to ammonium were coincident with changes in nitrate, nitrite and ammonium concentrations. Dissimilatory iron and manganese reduction transcript ratios increase during anoxic conditions and corresponded with the highest soluble reactive phosphate and manganese concentrations. The sulfide concentration peaked in late July and early August and also matched dissimilatory sulfate reduction transcript ratios. We show that rather than abrupt transitions between terminal electron acceptors, there is substantial overlap in time and space of these various anaerobic respiratory processes in Chesapeake Bay.

  17. Key respiratory genes elucidate bacterial community respiration in a seasonally anoxic estuary.

    PubMed

    Eggleston, Erin M; Lee, Dong Y; Owens, Michael S; Cornwell, Jeffrey C; Crump, Byron C; Hewson, Ian

    2015-07-01

    Intense annual spring phytoplankton blooms and thermohaline stratification lead to anoxia in Chesapeake Bay bottom waters. Once oxygen becomes depleted in the system, microbial communities use energetically favourable alternative electron acceptors for respiration. The extent to which changes in respiration are reflected in community gene expression have only recently been investigated. Metatranscriptomes prepared from near-bottom water plankton over a 4-month time series in central Chesapeake Bay demonstrated changes consistent with terminal electron acceptor availability. The frequency of respiration-related genes in metatranscriptomes was examined by BLASTx against curated databases of genes intimately and exclusively involved in specific electron acceptor utilization pathways. The relative expression of genes involved in denitrification and dissimilatory nitrate reduction to ammonium were coincident with changes in nitrate, nitrite and ammonium concentrations. Dissimilatory iron and manganese reduction transcript ratios increase during anoxic conditions and corresponded with the highest soluble reactive phosphate and manganese concentrations. The sulfide concentration peaked in late July and early August and also matched dissimilatory sulfate reduction transcript ratios. We show that rather than abrupt transitions between terminal electron acceptors, there is substantial overlap in time and space of these various anaerobic respiratory processes in Chesapeake Bay. PMID:25470994

  18. Rapid bacterial counts in metal working fluids.

    PubMed

    Sloyer, J L; Novitsky, T J; Nugent, S

    2002-12-01

    A rapid (10 s) automated fluorescent method to estimate viable bacteria in metal working fluids (MWF) was compared with dip-slide cultures. The BactiFluor method compared favorably with 107 MWF (r=0.99) and with 30 other metal processing fluids.

  19. Molecular characterization of bacterial respiration on minerals. Final technical report, August 4, 1994--August 3, 1996

    SciTech Connect

    Blake, R. II

    1996-12-31

    The scope of work outlined in the original proposal contained two specific aims. Highlights of the results obtained and published on each specific aim during the grant period in question are summarized. The first aim continued the identification, separation, and characterization of the cellular components necessary for aerobic respiration on iron. An electrochemical apparatus for the large scale cultivation of chemolithotrophic bacteria that respire aerobically on ferrous ions was perfected. The kinetic properties of an acid-stable iron:rusticyanin oxidoreductase from T. ferrooxidans were determined. The overall tertiary structure of rusticyanin in solution was elucidated from a combination of homonuclear proton and heteronuclear {sup 15}N-edited NMR spectra. An artificial gene for rusticyanin was designed, synthesized, and successfully expressed in E. coli. The X-ray crystallographic structure of rusticyanin was solved to a resolution of 1.9 {angstrom} by multiwavelength anomalous dispersion (MAD) phasing. The second aim initiated an investigation of the molecular principles whereby these bacteria recognize and adhere to their insoluble inorganic substrates. The electrophoretic mobility of T. ferrooxidans with and without its insoluble substrates was determined by laser Doppler velocimetry under physiological conditions. The adherence of T. ferrooxidans to the surface of pyrite was observed directly in a video-enhanced light microscope.

  20. Trace metal mobilization in soil by bacterial polymers

    SciTech Connect

    Chen, Jyh-Herng; Czajka, D.R.; Lion, L.W.

    1995-02-01

    Enhanced transport of trace metal in porous media can occur in the presence of a ligand or {open_quotes}carrier{close_quotes} that has a high affinity for binding the pollutant, is dispersed and mobile in the soil environment, is recalcitrant with respect to microbial degradation, and is acceptable to the public. These aspects of the facilitated transport to trace metals are discussed with respect to a naturally occurring carrier; extracellular polymers of bacterial origin. The literature is reviewed regarding the production and composition of bacterial extracellular polymers, the processes relevant to the facilitated transport of trace metals in soil by bacterial polymers, and potential for transformation of polymers in soils by microbial degradation. Model calculations of contaminant retardation are presented for the case of polymer-mediated transport of cadmium in a sandy aquifer material. The available information suggests that extracellular polymers can bind metal ions and are mobile in the soil environment. Extracellular polymers also appear to be relatively slowly degraded by soil microorganisms. These properties and the supporting model calculations indicate that extracellular polymers of bacterial origin merit consideration as agents that may be applied to contaminated soils to enhance trace metal mobility. 58 refs., 3 figs.

  1. Costs of living in metal polluted areas: respiration rate of the ground beetle Pterostichus oblongopunctatus from two gradients of metal pollution.

    PubMed

    Bednarska, Agnieszka J; Stachowicz, Izabela

    2013-01-01

    To address the question about costs of living in polluted areas, biomarkers linked to metabolism were measured in Pterostichus oblongopunctatus (Coleoptera: Carabidae) collected along two metal-pollution gradients in the vicinity of the two largest Polish zinc smelters: 'Bolesław' and 'Miasteczko Śląskie' in southern Poland. Both gradients covered a broad range of Zn and Cd concentrations in the humus layer (109-6151 and 1.48-71.4 mg kg(-1), respectively) and body metal concentrations increased with increasing soil metal concentrations. The whole-organism respiration rate was measured as oxygen consumption with Micro-Oxymax respirometer, and cellular energy consumption-as the activity of electron transport system, which is linked to cellular respiration rate. The significant increase in the whole-organism respiration rate with the body metal concentration was found when taking into account other factors such as body mass, gradient (or year of sampling as the beetles were collected on the gradients in different years) and the interactions: body metal concentrations × collection date, body metal concentrations × body mass, and body mass × gradient/sampling year. However, no relationships between metal concentrations in soil or body metal concentrations and the whole-organism or cellular respiration rate could be detected when using mean values per site, underlining the crucial importance of incorporating individual variability in such analyses. The observed increase of the whole-organism respiration rate with increasing body contamination with metals suggests that P. oblongopunctatus incurs energetic expenditures resulting from the necessity to facilitate metal elimination or repair of toxicant-induced damage. PMID:23090483

  2. Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

    USGS Publications Warehouse

    Carlisle, D.M.; Clements, W.H.

    2005-01-01

    1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously

  3. The Study Of Metalworking Fluids Biodegradability By Indirect Measurement Of Bacterial Inoculum Respiration

    NASA Astrophysics Data System (ADS)

    Gerulová, Kristína; Tatarka, Ondrej; Štefko, Tomáš; Škulavík, Tomáš

    2015-06-01

    An apparatus for measuring biodegradability of metalworking fluids (MWFs) was constructed according to (1), based on the Zahn-Wellens test which enables a continuous determination of CO2 production by the change in conductivity of absorption solution. Results obtained from the testing of 8 different MWFs by this modified method were compared to those obtained in standardized OECD 302 B. The comparison showed better description of bacterial inoculum activity in tested solution; lag phase was easy to indicate. Tested emulsion achieved the level of primary degradability 39.7 - 40.8 %, and semi-synthetics 19.1 - 43.5%. The samples of synthetics where the degradation level reached 43.9 - 58.6 % were identified as the most degradable metalworking fluids.

  4. Beneficial role of bacterial endophytes in heavy metal phytoremediation.

    PubMed

    Ma, Ying; Rajkumar, Mani; Zhang, Chang; Freitas, Helena

    2016-06-01

    Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up pollutants from the soil, water and air. In recent years, phytoremediation assisted by bacterial endophytes has been highly recommended for cleaning up of metal polluted soils since endophytic bacteria can alleviate metal toxicity in plant through their own metal resistance system and facilitate plant growth under metal stress. Endophytic bacteria improve plant growth in metal polluted soils in two different ways: 1) directly by producing plant growth beneficial substances including solubilization/transformation of mineral nutrients (phosphate, nitrogen and potassium), production of phytohormones, siderophores and specific enzymes; and 2) indirectly through controlling plant pathogens or by inducing a systemic resistance of plants against pathogens. Besides, they also alter metal accumulation capacity in plants by excreting metal immobilizing extracellular polymeric substances, as well as metal mobilizing organic acids and biosurfactants. The present work aims to review the progress of recent research on the isolation, identification and diversity of metal resistant endophytic bacteria and illustrate various mechanisms responsible for plant growth promotion and heavy metal detoxification/phytoaccumulation/translocation in plants.

  5. A chemical equilibrium model for metal adsorption onto bacterial surfaces

    NASA Astrophysics Data System (ADS)

    Fein, Jeremy B.; Daughney, Christopher J.; Yee, Nathan; Davis, Thomas A.

    1997-08-01

    This study quantifies metal adsorption onto cell wall surfaces of Bacillus subtilis by applying equilibrium thermodynamics to the specific chemical reactions that occur at the water-bacteria interface. We use acid/base titrations to determine deprotonation constants for the important surface functional groups, and we perform metal-bacteria adsorption experiments, using Cd, Cu, Pb, and Al, to yield site-specific stability constants for the important metal-bacteria surface complexes. The acid/base properties of the cell wall of B. subtilis can best be characterized by invoking three distinct types of surface organic acid functional groups, with pK a values of 4.82 ± 0.14, 6.9 ± 0.5, and 9.4 ± 0.6. These functional groups likely correspond to carboxyl, phosphate, and hydroxyl sites, respectively, that are displayed on the cell wall surface. The results of the metal adsorption experiments indicate that both the carboxyl sites and the phosphate sites contribute to metal uptake. The values of the log stability constants for metal-carboxyl surface complexes range from 3.4 for Cd, 4.2 for Pb, 4.3 for Cu, to 5.0 for Al. These results suggest that the stabilities of the metal-surface complexes are high enough for metal-bacterial interactions to affect metal mobilities in many aqueous systems, and this approach enables quantitative assessment of the effects of bacteria on metal mobilities.

  6. Quinone-reactive proteins devoid of haem b form widespread membrane-bound electron transport modules in bacterial respiration.

    PubMed

    Simon, Jörg; Kern, Melanie

    2008-10-01

    Many quinone-reactive enzyme complexes that are part of membrane-integral eukaryotic or prokaryotic respiratory electron transport chains contain one or more haem b molecules embedded in the membrane. In recent years, various novel proteins have emerged that are devoid of haem b but are thought to fulfil a similar function in bacterial anaerobic respiratory systems. These proteins are encoded by genes organized in various genomic arrangements and are thought to form widespread membrane-bound quinone-reactive electron transport modules that exchange electrons with redox partner proteins located at the outer side of the cytoplasmic membrane. Prototypic representatives are the multihaem c-type cytochromes NapC, NrfH and TorC (NapC/NrfH family), the putative iron-sulfur protein NapH and representatives of the NrfD/PsrC family. Members of these protein families vary in the number of their predicted transmembrane segments and, consequently, diverse quinone-binding sites are expected. Only a few of these enzymes have been isolated and characterized biochemically and high-resolution structures are limited. This mini-review briefly summarizes predicted and experimentally demonstrated properties of the proteins in question and discusses their role in electron transport and bioenergetics of anaerobic respiration.

  7. Alkaline Anaerobic Respiration: Isolation and Characterization of a Novel Alkaliphilic and Metal-Reducing Bacterium

    PubMed Central

    Ye, Qi; Roh, Yul; Carroll, Susan L.; Blair, Benjamin; Zhou, Jizhong; Zhang, Chuanlun L.; Fields, Matthew W.

    2004-01-01

    Iron-reducing enrichments were obtained from leachate ponds at the U.S. Borax Company in Boron, Calif. Based on partial small-subunit (SSU) rRNA gene sequences (approximately 500 nucleotides), six isolates shared 98.9% nucleotide identity. As a representative, the isolate QYMF was selected for further analysis. QYMF could be grown with Fe(III)-citrate, Fe(III)-EDTA, Co(III)-EDTA, or Cr(VI) as electron acceptors, and yeast extract and lactate could serve as electron donors. Growth during iron reduction occurred over the pH range of 7.5 to 11.0 (optimum, pH 9.5), a sodium chloride range of 0 to 80 g/liter (optimum, 20 g/liter), and a temperature range of 4 to 45°C (optimum, approximately 35°C), and iron precipitates were formed. QYMF was a strict anaerobe that could be grown in the presence of borax, and the cells were straight rods that produced endospores. Sodium chloride and yeast extract stimulated growth. Phylogenetic analysis of the SSU rRNA gene indicated that the bacterium was a low-G+C gram-positive microorganism and had 96 and 92% nucleotide identity with Alkaliphilus transvaalensis and Alkaliphilus crotonatoxidans, respectively. The major phospholipid fatty acids were 14:1, 16:1ω7c, and 16:0, which were different from those of other alkaliphiles but similar to those of reported iron-reducing bacteria. The results demonstrated that the isolate might represent a novel metal-reducing alkaliphilic species. The name Alkaliphilus metalliredigens sp. nov. is proposed. The isolation and activity of metal-reducing bacteria from borax-contaminated leachate ponds suggest that bioremediation of metal-contaminated alkaline environments may be feasible and have implications for alkaline anaerobic respiration. PMID:15345448

  8. Seasonal Variation in Soil Microbial Biomass, Bacterial Community Composition and Extracellular Enzyme Activity in Relation to Soil Respiration in a Northern Great Plains Grassland

    NASA Astrophysics Data System (ADS)

    Wilton, E.; Flanagan, L. B.

    2014-12-01

    Soil respiration rate is affected by seasonal changes in temperature and moisture, but is this a direct effect on soil metabolism or an indirect effect caused by changes in microbial biomass, bacterial community composition and substrate availability? In order to address this question, we compared continuous measurements of soil and plant CO2 exchange made with an automatic chamber system to analyses conducted on replicate soil samples collected on four dates during June-August. Microbial biomass was estimated from substrate-induced respiration rate, bacterial community composition was determined by 16S rRNA amplicon pyrosequencing, and β-1,4-N-acetylglucosaminidase (NAGase) and phenol oxidase enzyme activities were assayed fluorometrically or by absorbance measurements, respectively. Soil microbial biomass declined from June to August in strong correlation with a progressive decline in soil moisture during this time period. Soil bacterial species richness and alpha diversity showed no significant seasonal change. However, bacterial community composition showed a progressive shift over time as measured by Bray-Curtis dissimilarity. In particular, the change in community composition was associated with increasing relative abundance in the alpha and delta classes, and declining abundance of the beta and gamma classes of the Proteobacteria phylum during June-August. NAGase showed a progressive seasonal decline in potential activity that was correlated with microbial biomass and seasonal changes in soil moisture. In contrast, phenol oxidase showed highest potential activity in mid-July near the time of peak soil respiration and ecosystem photosynthesis, which may represent a time of high input of carbon exudates into the soil from plant roots. This input of exudates may stimulate the activity of phenol oxidase, a lignolytic enzyme involved in the breakdown of soil organic matter. These analyses indicated that seasonal change in soil respiration is a complex

  9. The Role of Bacterial Spores in Metal Cycling and Their Potential Application in Metal Contaminant Bioremediation.

    PubMed

    Butterfield, Cristina N; Lee, Sung-Woo; Tebo, Bradley M

    2016-04-01

    Bacteria are one of the premier biological forces that, in combination with chemical and physical forces, drive metal availability in the environment. Bacterial spores, when found in the environment, are often considered to be dormant and metabolically inactive, in a resting state waiting for favorable conditions for them to germinate. However, this is a highly oversimplified view of spores in the environment. The surface of bacterial spores represents a potential site for chemical reactions to occur. Additionally, proteins in the outer layers (spore coats or exosporium) may also have more specific catalytic activity. As a consequence, bacterial spores can play a role in geochemical processes and may indeed find uses in various biotechnological applications. The aim of this review is to introduce the role of bacteria and bacterial spores in biogeochemical cycles and their potential use as toxic metal bioremediation agents.

  10. Improving the sensitivity of bacterial bioreporters for heavy metals.

    PubMed

    Hynninen, Anu; Tönismann, Karmen; Virta, Marko

    2010-01-01

    Whole-cell bacterial bioreporters represent a convenient testing method for quantifying the bioavailability of contaminants in environmental samples. Despite the fact that several bioreporters have been constructed for measuring heavy metals, their application to environmental samples has remained minimal. The major drawbacks of the available bioreporters include a lack of sensitivity and specificity. Here, we report an improvement in the limit of detection of bacterial bioreporters by interfering with the natural metal homeostasis system of the host bacterium. The limit of detection of a Pseudomonas putida KT2440-based Zn/Cd/Pb-biosensor was improved by a factor of up to 45 by disrupting four main efflux transporters for Zn/Cd/Pb and thereby causing the metals to accumulate in the cell. The specificity of the bioreporter could be modified by changing the sensor element. A Zn-specific bioreporter was achieved by using the promoter of the cadA1 gene from P. putida as a sensor element. The constructed transporter-deficient P. putida reporter strain detected Zn(2+) concentrations about 50 times lower than that possible with other available Zn-bioreporters. The achieved detection limits were significantly below the permitted limit values for Zn and Pb in water and in soil, allowing for reliable detection of heavy metals in the environment.

  11. Improving the sensitivity of bacterial bioreporters for heavy metals.

    PubMed

    Hynninen, Anu; Tönismann, Karmen; Virta, Marko

    2010-01-01

    Whole-cell bacterial bioreporters represent a convenient testing method for quantifying the bioavailability of contaminants in environmental samples. Despite the fact that several bioreporters have been constructed for measuring heavy metals, their application to environmental samples has remained minimal. The major drawbacks of the available bioreporters include a lack of sensitivity and specificity. Here, we report an improvement in the limit of detection of bacterial bioreporters by interfering with the natural metal homeostasis system of the host bacterium. The limit of detection of a Pseudomonas putida KT2440-based Zn/Cd/Pb-biosensor was improved by a factor of up to 45 by disrupting four main efflux transporters for Zn/Cd/Pb and thereby causing the metals to accumulate in the cell. The specificity of the bioreporter could be modified by changing the sensor element. A Zn-specific bioreporter was achieved by using the promoter of the cadA1 gene from P. putida as a sensor element. The constructed transporter-deficient P. putida reporter strain detected Zn(2+) concentrations about 50 times lower than that possible with other available Zn-bioreporters. The achieved detection limits were significantly below the permitted limit values for Zn and Pb in water and in soil, allowing for reliable detection of heavy metals in the environment. PMID:21326938

  12. Biochemical parameters and bacterial species richness in soils contaminated by sludge-borne metals and remediated with inorganic soil amendments.

    PubMed

    Mench, Michel; Renella, Giancarlo; Gelsomino, Antonio; Landi, Loretta; Nannipieri, Paolo

    2006-11-01

    The effectiveness of two amendments for the in situ remediation of a Cd- and Ni-contaminated soil in the Louis Fargue long-term field experiment was assessed. In April 1995, one replicate plot (S1) was amended with 5% w/w of beringite (B), a coal fly ash (treatment S1+B), and a second plot with 1% w/w zerovalent-Fe iron grit (SS) (treatment S1+SS), with the aim of increasing metal sorption and attenuating metal impacts. Long-term responses of daily respiration rates, microbial biomass, bacterial species richness and the activities of key soil enzymes (acid and alkaline phosphatase, arylsulfatase, beta-glucosidase, urease and protease activities) were studied in relation to soil metal extractability. Seven years after initial amendments, the labile fractions of Cd and Ni in both the S1+B and S1+SS soils were reduced to various extents depending on the metal and fractions considered. The soil microbial biomass and respiration rate were not affected by metal contamination and amendments in the S1+B and S1+SS soils, whereas the activity of different soil enzymes was restored. The SS treatment was more effective in reducing labile pools of Cd and Ni and led to a greater recovery of soil enzyme activities than the B treatment. Bacterial species richness in the S1 soil did not alter with either treatment. It was concluded that monitoring of the composition and activity of the soil microbial community is important in evaluating the effectiveness of soil remediation practices.

  13. Susceptibility of metallic magnesium implants to bacterial biofilm infections.

    PubMed

    Rahim, Muhammad Imran; Rohde, Manfred; Rais, Bushra; Seitz, Jan-Marten; Mueller, Peter P

    2016-06-01

    Magnesium alloys have promising mechanical and biological properties as biodegradable medical implant materials for temporary applications during bone healing or as vascular stents. Whereas conventional implants are prone to colonization by treatment resistant microbial biofilms in which bacteria are embedded in a protective matrix, magnesium alloys have been reported to act antibacterial in vitro. To permit a basic assessment of antibacterial properties of implant materials in vivo an economic but robust animal model was established. Subcutaneous magnesium implants were inoculated with bacteria in a mouse model. Contrary to the expectations, bacterial activity was enhanced and prolonged in the presence of magnesium implants. Systemic antibiotic treatments were remarkably ineffective, which is a typical property of bacterial biofilms. Biofilm formation was further supported by electron microscopic analyses that revealed highly dense bacterial populations and evidence for the presence of extracellular matrix material. Bacterial agglomerates could be detected not only on the implant surface but also at a limited distance in the peri-implant tissue. Therefore, precautions may be necessary to minimize risks of metallic magnesium-containing implants in prospective clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1489-1499, 2016. PMID:26860452

  14. Enhancement of bacterial iron and sulfate respiration for in situ bioremediation of acid mine drainage sites: a case study

    SciTech Connect

    Bilgin, A.A.; Harrington, J.M.; Silverstein, J.

    2007-08-15

    The prevention of acid mine drainage (AMD) in situ is more attractive than down-gradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied to an abandoned coal mine pool in Pennsylvania. The pool had a pH of 3.0 to 3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by the enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

  15. Adsorption of enterobactin to metal oxides and the role of siderophores in bacterial adhesion to metals.

    PubMed

    Upritchard, Hamish G; Yang, Jing; Bremer, Philip J; Lamont, Iain L; McQuillan, A James

    2011-09-01

    The potential contribution of chemical bonds formed between bacterial cells and metal surfaces during biofilm initiation has received little attention. Previous work has suggested that bacterial siderophores may play a role in bacterial adhesion to metals. It has now been shown using in situ ATR-IR spectroscopy that enterobactin, a catecholate siderophore secreted by Escherichia coli, forms covalent bonds with particle films of titanium dioxide, boehmite (AlOOH), and chromium oxide-hydroxide which model the surfaces of metals of significance in medical and industrial settings. Adsorption of enterobactin to the metal oxides occurred through the 2,3-dihydroxybenzoyl moieties, with the trilactone macrocycle having little involvement. Vibrational modes of the 2,3-dihydroxybenzoyl moiety of enterobactin, adsorbed to TiO(2), were assigned by comparing the observed IR spectra with those calculated by the density functional method. Comparison of the observed adsorbate IR spectrum with the calculated spectra of catecholate-type [H(2)NCOC(6)H(3)O(2)Ti(OH)(4)](2-) and salicylate-type [H(2)NCOC(6)H(3)O(2)HTi(OH)(4)](2-) surface complexes indicated that the catecholate type is dominant. Analysis of the spectra for enterobactin in solution and that adsorbed to TiO(2) revealed that the amide of the 2,3-dihydroxybenzoylserine group reorientates during coordination to surface Ti(IV) ions. Investigation into the pH dependence of enterobactin adsorption to TiO(2) surfaces showed that all 2,3-dihydroxybenzoyl groups are involved. Infrared absorption bands attributed to adsorbed enterobactin were also strongly evident for E. coli cells attached to TiO(2) particle films. These studies give evidence of enterobactin-metal bond formation and further suggest the generality of siderophore involvement in bacterial biofilm initiation on metal surfaces.

  16. High mobilization of arsenic, metals and rare earth elements in seepage waters driven by respiration of old allochthonous organic carbon.

    PubMed

    Weiske, Arndt; Schaller, Jörg; Hegewald, Tilo; Machill, Susanne; Werner, Ingo; Dudel, E Gert

    2013-12-01

    Metal and metalloid mobilization processes within seepage water are of major concern in a range of water reservoir systems. The mobilization process of arsenic and heavy metals within a dam and sediments of a drinking water reservoir was investigated. Principle component analysis (PCA) on time series data of seepage water showed a clear positive correlation of arsenic with iron and DOC (dissolved organic carbon), and a negative correlation with nitrate due to respiratory processes. A relationship of reductive metal and metalloid mobilization with respiration of old carbon was shown. The system is influenced by sediment layers as well as a recent DOC input from degraded ombrotrophic peatbogs in the catchment area. The isotopic composition ((12)C, (13)C and (14)C) of DOC is altered along the path from basin to seepage water, but no significant changes in structural parameters (LC-OCD-OND, FT-IR) could be seen. DIC (dissolved inorganic carbon) in seepage water partly originates from respiratory processes, and a higher relationship of it with sediment carbon than with the DOC inventory of infiltrating water was found. This study revealed the interaction of respiratory processes with metal and metalloid mobilization in sediment water flows. In contrast to the presumption that emerging DOC via respiratory processes mainly controls arsenic and metal mobilization it could be shown that the presence of aged carbon compounds is essential. The findings emphasize the importance of aged organic carbon for DOC, DIC, arsenic and metal turnover.

  17. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    SciTech Connect

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  18. Estimating factors to convert Chinese 'Total Dust' measurements to ACGIH respirable concentrations in metal mines and pottery industries.

    PubMed

    Gao, P; Chen, B T; Hearl, F J; McCawley, M A; Schwerha, D J; Odencrantz, J; Chen, W; Chen, J; Soderholm, S C

    2000-06-01

    Historical data on the dust exposures of Chinese workers in metal mines (iron/copper, tin, tungsten) and pottery industries are being used in an ongoing joint Chinese/United States epidemiological study to investigate the exposure-response relationship for the development of silicosis, lung cancer, and other diseases. The historical data include 'total dust' concentrations determined by a Chinese method. Information about particle size distribution and the chemical and mineralogical content of airborne particles is generally not available. In addition, the historical Chinese sampling strategy is different from a typical American eight-hour time-weighted average (TWA) sampling strategy, because the Chinese samples were collected for approximately 15 minutes during production so the sample could be compared to their maximum allowable concentration (MAC) standard. Therefore, in order to assess American respirable dust exposure standards in light of the Chinese experience, factors are needed to convert historical Chinese total dust concentrations to respirable dust concentrations. As a part of the joint study to estimate the conversion factors, airborne dust samples were collected in 20 metal mines and 9 pottery factories in China during 1988 and 1989 using three different samplers: 10mm nylon cyclones, multi-stage 'cassette' impactors, and the traditional Chinese total dust samplers. More than 100 samples were collected and analysed for each of the three samplers. The study yielded two different estimates of the conversion factor from the Chinese total dust concentrations (measured during production processes) to respirable dust concentrations. The multivariate analysis of variance (MANOVA) reveals that, with a fixed sampling/analysis method, conversion factors were not statistically different among the different job titles within each industry. It also indicates that conversion factors among the industries were not statistically different. However, the two estimates

  19. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes

    SciTech Connect

    Shi, Liang; Squier, Thomas C.; Zachara, John M.; Fredrickson, Jim K.

    2007-07-01

    Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobactersulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1-and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.

  20. A cost-effective and field-ready potentiostat that poises subsurface electrodes to monitor bacterial respiration.

    PubMed

    Friedman, Elliot S; Rosenbaum, Miriam A; Lee, Alexander W; Lipson, David A; Land, Bruce R; Angenent, Largus T

    2012-02-15

    Here, we present the proof-of-concept for a subsurface bioelectrochemical system (BES)-based biosensor capable of monitoring microbial respiration that occurs through exocellular electron transfer. This system includes our open-source design of a three-channel microcontroller-unit (MCU)-based potentiostat that is capable of chronoamperometry, which laboratory tests showed to be accurate within 0.95 ± 0.58% (95% Confidence Limit) of a commercial potentiostat. The potentiostat design is freely available online: http://angenent.bee.cornell.edu/potentiostat.html. This robust and field-ready potentiostat, which can withstand temperatures of -30°C, can be manufactured at relatively low cost ($600), thus, allowing for en-masse deployment at field sites. The MCU-based potentiostat was integrated with electrodes and a solar panel-based power system, and deployed as a biosensor to monitor microbial respiration in drained thaw lake basins outside Barrow, AK. At three different depths, the working electrode of a microbial three-electrode system (M3C) was maintained at potentials corresponding to the microbial reduction of iron(III) compounds and humic acids. Thereby, the working electrode mimics these compounds and is used by certain microbes as an electron acceptor. The sensors revealed daily cycles in microbial respiration. In the medium- and deep-depth electrodes the onset of these cycles followed a considerable increase in overall activity that corresponded to those soils reaching temperatures conducive to microbial activity as the summer thaw progressed. The BES biosensor is a valuable tool for studying microbial activity in situ in remote environments, and the cost-efficient design of the potentiostat allows for wide-scale use in remote areas. PMID:22209069

  1. A cost-effective and field-ready potentiostat that poises subsurface electrodes to monitor bacterial respiration.

    PubMed

    Friedman, Elliot S; Rosenbaum, Miriam A; Lee, Alexander W; Lipson, David A; Land, Bruce R; Angenent, Largus T

    2012-02-15

    Here, we present the proof-of-concept for a subsurface bioelectrochemical system (BES)-based biosensor capable of monitoring microbial respiration that occurs through exocellular electron transfer. This system includes our open-source design of a three-channel microcontroller-unit (MCU)-based potentiostat that is capable of chronoamperometry, which laboratory tests showed to be accurate within 0.95 ± 0.58% (95% Confidence Limit) of a commercial potentiostat. The potentiostat design is freely available online: http://angenent.bee.cornell.edu/potentiostat.html. This robust and field-ready potentiostat, which can withstand temperatures of -30°C, can be manufactured at relatively low cost ($600), thus, allowing for en-masse deployment at field sites. The MCU-based potentiostat was integrated with electrodes and a solar panel-based power system, and deployed as a biosensor to monitor microbial respiration in drained thaw lake basins outside Barrow, AK. At three different depths, the working electrode of a microbial three-electrode system (M3C) was maintained at potentials corresponding to the microbial reduction of iron(III) compounds and humic acids. Thereby, the working electrode mimics these compounds and is used by certain microbes as an electron acceptor. The sensors revealed daily cycles in microbial respiration. In the medium- and deep-depth electrodes the onset of these cycles followed a considerable increase in overall activity that corresponded to those soils reaching temperatures conducive to microbial activity as the summer thaw progressed. The BES biosensor is a valuable tool for studying microbial activity in situ in remote environments, and the cost-efficient design of the potentiostat allows for wide-scale use in remote areas.

  2. Effect of a metal alloy fuel catalyst on bacterial growth.

    PubMed

    Ghosh, Ruma; Koerting, Claudia; Suib, Steven L; Best, Michael H; Berlin, Alvin J

    2005-11-01

    Many microorganisms have been demonstrated to utilize petroleum fuel products to fulfill their nutritional requirement for carbon. As a result, the ability of these microbes to degrade fuel has both a deleterious affect as well as beneficial applications. This study focused on the undesired ability of bacteria to grow on fuel and the potential for some metal alloys to inhibit this biodegradation. The objective of this study was to review the pattern of growth of two reference strains of petroleum-degrading bacteria, Pseudomonas oleovorans and Rhodococcus rhodocrous, in a specific hydrocarbon environment in the presence of a commercially available alloy. The alloy formulated and supplied by Advanced Power Systems International Inc. (APSI) is sold for fuel reformulation and other purposes. The components of the alloy used in the study were antimony, tin, lead, and mercury formulated as pellets. Surface characterization also showed the presence of tin oxide and lead amalgam phases. Hydrocarbon used for the study was primarily 87-octane gasoline. The growth of the bacteria in the water and mineral-supplemented gasoline mixture over 6-8 weeks was monitored by the viable plate count method. While an initial increase in bacteria occurred in the first week, overall bacterial growth was found to be suppressed in the presence of the alloy. Results also indicate that the alloy surface characteristics that convey the catalytic activity may also contribute to the observed antibacterial activity. PMID:16262333

  3. Comprehensive Proteomic and Metabolomic Signatures of Nontypeable Haemophilus influenzae-Induced Acute Otitis Media Reveal Bacterial Aerobic Respiration in an Immunosuppressed Environment.

    PubMed

    Harrison, Alistair; Dubois, Laura G; St John-Williams, Lisa; Moseley, M Arthur; Hardison, Rachael L; Heimlich, Derek R; Stoddard, Alexander; Kerschner, Joseph E; Justice, Sheryl S; Thompson, J Will; Mason, Kevin M

    2016-03-01

    A thorough understanding of the molecular details of the interactions between bacteria and host are critical to ultimately prevent disease. Recent technological advances allow simultaneous analysis of host and bacterial protein and metabolic profiles from a single small tissue sample to provide insight into pathogenesis. We used the chinchilla model of human otitis media to determine, for the first time, the most expansive delineation of global changes in protein and metabolite profiles during an experimentally induced disease. After 48 h of infection with nontypeable Haemophilus influenzae, middle ear tissue lysates were analyzed by high-resolution quantitative two-dimensional liquid chromatography-tandem mass spectrometry. Dynamic changes in 105 chinchilla proteins and 66 metabolites define the early proteomic and metabolomic signature of otitis media. Our studies indicate that establishment of disease coincides with actin morphogenesis, suppression of inflammatory mediators, and bacterial aerobic respiration. We validated the observed increase in the actin-remodeling complex, Arp2/3, and experimentally showed a role for Arp2/3 in nontypeable Haemophilus influenzae invasion. Direct inhibition of actin branch morphology altered bacterial invasion into host epithelial cells, and is supportive of our efforts to use the information gathered to modify outcomes of disease. The twenty-eight nontypeable Haemophilus influenzae proteins identified participate in carbohydrate and amino acid metabolism, redox homeostasis, and include cell wall-associated metabolic proteins. Quantitative characterization of the molecular signatures of infection will redefine our understanding of host response driven developmental changes during pathogenesis. These data represent the first comprehensive study of host protein and metabolite profiles in vivo in response to infection and show the feasibility of extensive characterization of host protein profiles during disease. Identification of

  4. Comprehensive Proteomic and Metabolomic Signatures of Nontypeable Haemophilus influenzae-Induced Acute Otitis Media Reveal Bacterial Aerobic Respiration in an Immunosuppressed Environment.

    PubMed

    Harrison, Alistair; Dubois, Laura G; St John-Williams, Lisa; Moseley, M Arthur; Hardison, Rachael L; Heimlich, Derek R; Stoddard, Alexander; Kerschner, Joseph E; Justice, Sheryl S; Thompson, J Will; Mason, Kevin M

    2016-03-01

    A thorough understanding of the molecular details of the interactions between bacteria and host are critical to ultimately prevent disease. Recent technological advances allow simultaneous analysis of host and bacterial protein and metabolic profiles from a single small tissue sample to provide insight into pathogenesis. We used the chinchilla model of human otitis media to determine, for the first time, the most expansive delineation of global changes in protein and metabolite profiles during an experimentally induced disease. After 48 h of infection with nontypeable Haemophilus influenzae, middle ear tissue lysates were analyzed by high-resolution quantitative two-dimensional liquid chromatography-tandem mass spectrometry. Dynamic changes in 105 chinchilla proteins and 66 metabolites define the early proteomic and metabolomic signature of otitis media. Our studies indicate that establishment of disease coincides with actin morphogenesis, suppression of inflammatory mediators, and bacterial aerobic respiration. We validated the observed increase in the actin-remodeling complex, Arp2/3, and experimentally showed a role for Arp2/3 in nontypeable Haemophilus influenzae invasion. Direct inhibition of actin branch morphology altered bacterial invasion into host epithelial cells, and is supportive of our efforts to use the information gathered to modify outcomes of disease. The twenty-eight nontypeable Haemophilus influenzae proteins identified participate in carbohydrate and amino acid metabolism, redox homeostasis, and include cell wall-associated metabolic proteins. Quantitative characterization of the molecular signatures of infection will redefine our understanding of host response driven developmental changes during pathogenesis. These data represent the first comprehensive study of host protein and metabolite profiles in vivo in response to infection and show the feasibility of extensive characterization of host protein profiles during disease. Identification of

  5. Isolation and Genomic Characterization of 'Desulfuromonas soudanensis WTL', a Metal- and Electrode-Respiring Bacterium from Anoxic Deep Subsurface Brine.

    PubMed

    Badalamenti, Jonathan P; Summers, Zarath M; Chan, Chi Ho; Gralnick, Jeffrey A; Bond, Daniel R

    2016-01-01

    Reaching a depth of 713 m below the surface, the Soudan Underground Iron Mine (Soudan, MN, USA) transects a massive Archaean (2.7 Ga) banded iron formation, providing a remarkably accessible window into the terrestrial deep biosphere. Despite organic carbon limitation, metal-reducing microbial communities are present in potentially ancient anoxic brines continuously emanating from exploratory boreholes on Level 27. Using graphite electrodes deposited in situ as bait, we electrochemically enriched and isolated a novel halophilic iron-reducing Deltaproteobacterium, 'Desulfuromonas soudanensis' strain WTL, from an acetate-fed three-electrode bioreactor poised at +0.24 V (vs. standard hydrogen electrode). Cyclic voltammetry revealed that 'D. soudanensis' releases electrons at redox potentials approximately 100 mV more positive than the model freshwater surface isolate Geobacter sulfurreducens, suggesting that its extracellular respiration is tuned for higher potential electron acceptors. 'D. soudanensis' contains a 3,958,620-bp circular genome, assembled to completion using single-molecule real-time (SMRT) sequencing reads, which encodes a complete TCA cycle, 38 putative multiheme c-type cytochromes, one of which contains 69 heme-binding motifs, and a LuxI/LuxR quorum sensing cassette that produces an unidentified N-acyl homoserine lactone. Another cytochrome is predicted to lie within a putative prophage, suggesting that horizontal gene transfer plays a role in respiratory flexibility among metal reducers. Isolation of 'D. soudanensis' underscores the utility of electrode-based approaches for enriching rare metal reducers from a wide range of habitats. PMID:27445996

  6. Composition, Reactivity, and Regulations of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal Reducing Bacteria

    SciTech Connect

    Scholten, Johannes

    2006-06-01

    This research proposal seeks to describe the composition and function of electrically conductive appendages known as bacterial nanowires. This project targets bacterial nanowires produced by dissimilatory metal reducing bacteria Shewanella and Geobacter. Specifically, this project will investigate the role of these structures in the reductive transformation of iron oxides as solid phase electron acceptors, as well as uranium as a dissolved electron acceptor that forms nanocrystalline particles of uraninite upon reduction.

  7. Structural diversity of bacterial communities in a heavy metal mineralized granite outcrop.

    PubMed

    Gleeson, Deirdre; McDermott, Frank; Clipson, Nicholas

    2006-03-01

    This laboratory study of a variably mineralized and hydrothermally altered granite outcrop investigated the influences of rock-surface chemistry and heavy metal content on resident bacterial populations. Results indicated that elevated heavy metal concentrations had a profound impact on bacterial community structure, with strong relationships found between certain ribotypes and particular chemical/heavy metal elements. Automated ribosomal intergenic sequence analysis (ARISA) was used to assess the nature and extent of bacterial diversity, and this was combined with chemical analysis and multivariate statistics to identify the main geochemical factors influencing bacterial community structure. A randomization test revealed significant changes in bacterial structure between samples, while canonical correspondence analysis (CCA) related each individual ARISA profile to linear combinations of the chemical variables (mineralogy, major element and heavy metal concentrations) revealing the geochemical factors that correlated with changes in the ARISA data. anova was performed to further explore interactions between individual ribotypes and chemical/heavy metal composition, and revealed that a high proportion of ribotypes correlated significantly with heavy metals.

  8. Sputtered Gum metal thin films showing bacterial inactivation and biocompatibility.

    PubMed

    Achache, S; Alhussein, A; Lamri, S; François, M; Sanchette, F; Pulgarin, C; Kiwi, J; Rtimi, S

    2016-10-01

    Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) and Ti-24Nb-(N) (TN-N) (at.%) were deposited by direct current magnetron sputtering (DCMS) in different reactive atmospheres. The effects of oxygen doping (TNTZ-O) and/or nitrogen doping (TN-N) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that, in both cases, 1sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young's modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. Bacterial inactivation was concomitant with the observed pH and surface potential changes under light and in the dark. The increased cell fluidity leading to bacterial lysis was followed during the bacterial inactivation time. The increasing cell wall fluidity was attributed to the damage of the bacterial outer cell which losing its capacity to regulate the ions exchange in and out of the bacteria.

  9. Sputtered Gum metal thin films showing bacterial inactivation and biocompatibility.

    PubMed

    Achache, S; Alhussein, A; Lamri, S; François, M; Sanchette, F; Pulgarin, C; Kiwi, J; Rtimi, S

    2016-10-01

    Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) and Ti-24Nb-(N) (TN-N) (at.%) were deposited by direct current magnetron sputtering (DCMS) in different reactive atmospheres. The effects of oxygen doping (TNTZ-O) and/or nitrogen doping (TN-N) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that, in both cases, 1sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young's modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. Bacterial inactivation was concomitant with the observed pH and surface potential changes under light and in the dark. The increased cell fluidity leading to bacterial lysis was followed during the bacterial inactivation time. The increasing cell wall fluidity was attributed to the damage of the bacterial outer cell which losing its capacity to regulate the ions exchange in and out of the bacteria. PMID:27434155

  10. Effect of organic carbon and metal accumulation on the bacterial communities in sulphidogenic sediments.

    PubMed

    Bueche, Matthieu; Junier, Pilar

    2016-06-01

    A unique geochemical setting in Lake Cadagno, Switzerland, has led to the accumulation of insoluble metal sulphides in the sedimentary record as the result of past airborne pollution. This offers an exceptional opportunity to study the effect of these metals on the bacterial communities in sediments, and in particular to investigate further the link between metal contamination and an increase in the populations of endospore-forming bacteria observed previously in other metal-contaminated sediments. A decrease in organic carbon and total bacterial counts was correlated with an increase in the numbers of endospores in the oldest sediment samples, showing the first environmental evidence of a decrease in nutrient availability as a trigger of sporulation. Proteobacteria and Firmicutes were the two dominant bacterial phyla throughout the sediment, the former in an area with high sulphidogenic activity, and the latter in the oldest samples. Even though the dominant Firmicutes taxa were stable along the sediment core and did not vary with changes in metal contamination, the prevalence of some molecular species like Clostridium sp. was positively correlated with metal sulphide concentration. However, this cannot be generalized to all endospore-forming species. Overall, the community composition supports the hypothesis of sporulation as the main mechanism explaining the dominance of endospore formers in the deepest part of the sediment core, while metal contamination in the form of insoluble metal sulphide deposits appears not to be linked with sporulation as a mechanism of metal tolerance in this sulphidogenic ecosystem.

  11. Bacterial Exopolysaccharides For Corrosion Inhibition on Metal Substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofilms, composed of extra-cellular polymers secreted by bacteria, have been observed to both increase as well as decrease the rate of metal corrosion. Exopolysaccharides derived from Leuconostoc mesenteroides cultures have been shown to inhibit corrosion on corrosion-sensitive metals. The substa...

  12. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    PubMed

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  13. Engineered Bacterial Metal-binding Proteins for Nanoscale Self-assembly and heavy Metal Tolerance

    NASA Astrophysics Data System (ADS)

    Hall Sedlak, Ruth Amanda

    Implementing biological principles in material synthesis and assembly is one way to expand our abilities to efficiently assemble nanoscale materials and devices. Specifically, recent advances in identifying peptides that bind inorganic materials with high affinity and specificity has spurred investigation of protein models for nanoscale inorganic assembly. This dissertation presents the results of my studies of several E. coli proteins engineered to bind inorganic materials through simple peptide motifs. I demonstrate that these proteins modulate the self-assembly of DNA-based nanostructures and can introduce heavy metal tolerance into metal-sensitive bacteria. Chapter 2 explores use of the engineered F plasmid DNA relaxase/helicase TraI for the self-assembly of complex DNA-protein-gold nanostructures. The full-length protein is engineered with a gold binding motif at an internal permissive site (TraI369GBP1-7x), while a truncated version of TraI is engineered with the same gold binding motif at the C-terminus (TraI361GBP1-7x). Both constructs bind gold nanoparticles while maintaining their DNA binding activity, and transmission electron microscopy reveals TraI369GBP1-7x utilizes its non-specific DNA binding activity to decorate single-stranded and double-stranded DNA with gold nanoparticles. The self assembly principles demonstrated in this work will be fundamental to constructing higher ordered hybrid nanostructures through DNA-protein-nanoparticle interactions. Chapter 3 studies the effects of expressing inorganic binding peptides within cells. I identified a silver binding peptide that, when fused to the periplasmic maltose binding protein, protects E. coli from silver toxicity in batch culture and reduces silver ions to silver nanoparticles within the bacterial periplasm. Engineered metal-ion tolerant microorganisms such as this E. coli could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo

  14. Iraq Dust is Respirable, Sharp, Metal-Laden, and Induces Lung Inflammation with Fibrosis in Mice via IL-2 Upregulation and Depletion of Regulatory T Cells

    PubMed Central

    Szema, Anthony M.; Reeder, Richard J.; Harrington, Andrea D.; Schmidt, Millicent; Liu, Jingxuan; Golightly, Marc; Rueb, Todd; Hamidi, Sayyed A.

    2014-01-01

    Soldiers returning from Iraq have reported respiratory symptoms. Lung biopsies show constrictive bronchiolitis and vascular remodeling with polarizable crystals. We hypothesized that ground surface dust may be a contributing factor to Iraq Afghanistan War Lung Injury (IAW-LI) and analyzed soil grab samples from Camp Victory, Iraq to determine if particle sizes are respirable. Samples contain particles 2.5 micron in size and have sharp edges. Trace metals (including titanium), calcium and silicon are present. Mice with airway instillation of dust have polarizable crystals and septate inflammation. CD4+CD25+FOXP3+ regulatory T cells are decreased in spleen and thymus from mice exposed to dust. IL-2 is elevated from bronchoalveolar lavage taken from dust-exposed mice. Respirable Iraq dust leads to lung inflammation in mice similar to that seen in patients, particularly regarding polarizable crystals which, appear to be titanium. PMID:24603199

  15. Bacterial adhesion on amorphous and crystalline metal oxide coatings.

    PubMed

    Almaguer-Flores, Argelia; Silva-Bermudez, Phaedra; Galicia, Rey; Rodil, Sandra E

    2015-12-01

    Several studies have demonstrated the influence of surface properties (surface energy, composition and topography) of biocompatible materials on the adhesion of cells/bacteria on solid substrates; however, few have provided information about the effect of the atomic arrangement or crystallinity. Using magnetron sputtering deposition, we produced amorphous and crystalline TiO2 and ZrO2 coatings with controlled micro and nanoscale morphology. The effect of the structure on the physical-chemical surface properties was carefully analyzed. Then, we studied how these parameters affect the adhesion of Escherichia coli and Staphylococcus aureus. Our findings demonstrated that the nano-topography and the surface energy were significantly influenced by the coating structure. Bacterial adhesion at micro-rough (2.6 μm) surfaces was independent of the surface composition and structure, contrary to the observation in sub-micron (0.5 μm) rough surfaces, where the crystalline oxides (TiO2>ZrO2) surfaces exhibited higher numbers of attached bacteria. Particularly, crystalline TiO2, which presented a predominant acidic nature, was more attractive for the adhesion of the negatively charged bacteria. The information provided by this study, where surface modifications are introduced by means of the deposition of amorphous or crystalline oxide coatings, offers a route for the rational design of implant surfaces to control or inhibit bacterial adhesion.

  16. Quick discrimination of heavy metal resistant bacterial populations using infrared spectroscopy coupled with chemometrics.

    PubMed

    Gurbanov, Rafig; Simsek Ozek, Nihal; Gozen, Ayse Gul; Severcan, Feride

    2015-10-01

    Lead and cadmium are frequently encountered heavy metals in industrially polluted areas. Many heavy metal resistant bacterial strains have a high biosorption capacity and thus are good candidates for the removal of toxic metals from the environment. However, as of yet there is no accurate method for discrimination of highly adaptive bacterial strains among the populations present in a given habitat. In this study, we aimed to find distinguishing molecular features of lead and cadmium resistant bacteria using Attenuated Total Reflectance-Fourier Transformed Infrared (ATR-FT-IR) spectroscopy and chemometric approaches. Our results demonstrated that both control and metal exposed E. coli and S. aureus strains could be successfully discriminated from each other using hierarchical cluster and principal component analysis methods. Moreover, we found that lead exposed bacterial strains could be successfully discriminated from cadmium exposed ones with a high heterogeneity value. These clear discriminations can be described by the ability of a bacterium to change its metabolism in terms of the content and structure of cellular macromolecules under heavy metal stress. In our case, cadmium and lead-induced genetic response systems in bacteria caused remarkable alterations in overall cellular metabolism. Bacteria deal with a heavy metal stress by altering nucleic acid methylations and lipid and protein synthesis. Heavy metal burden led to the development of relevant metabolic changes in proteins, lipids, and nucleic acids of the resistant bacteria described in this study. Our approach showed that infrared spectra obtained via ATR-FT-IR spectroscopy coupled with chemometric analysis can be utilized for rapid, low-cost, informative, reliable, and operator-independent discrimination of resistant bacterial populations.

  17. Facilitated transport of heavy metals by bacterial colloids in sand columns

    NASA Astrophysics Data System (ADS)

    Guiné, V.; Martins, J.; Gaudet, J. P.

    2003-05-01

    The aim of this work is to evaluate the ability of biotic collois (e.g. bacterial cells) to facilitate the transport of heavy metals in soils. and to identify the main factors influencing colloid transport in order to detelmine the geo-chemical conditions where this secondary transport process may become dominant. The model colloids studied here are living cells of Escherichia coli and Ralstonia metallidurans. We studied the transport of mercury zinc, and cadmium in columns of Fontainebleau sand. The properties (i.e. optical and morphological properties, charge (zeta potential, zeta) and hydrophobia (water/hexadecane distribution parameter, K_{hw})) of the bacterial cells surface were characterised, as well as their potential for heavy metals sorption (kinetic and isotherm). Both surface charge (zeta=-54 and -14 mV) and hydrophobia (K_{hw} = 0.25 and 0.05) differ strongly for the two bacteria. Column studies were conducted with bacteria and heavy metals separately or simultaneously. The cell surface differences led to different transport behaviour of the two bacteria, although the retardation factor is close to 1 for both. We observed that colloid mobility increases when increasing bacterial cells concentration and when decreasing the ionic strength. We also observed that bacterial colloids appeared as excellent vectors for Hg, Zn and Cd. Indeed, heavy metals adsorbed on the Fontainebleau sand when injected alone in columns (retardation factors of 1.4 ; 2.9 and 3.8 for Hg, Zn and Cd, respectively); whereas no retardation (R≈1) is observed when injected in the presence of both bacteria. Moreover, transport of bio-sorbed metal appears to be 4 to 6 times higher than dissolved heavy-metal.

  18. Metal site occupancy and allosteric switching in bacterial metal sensor proteins

    PubMed Central

    Guerra, Alfredo J.; Giedroc, David P.

    2012-01-01

    All prokaryotes encode a panel of metal sensor or metalloregulatory proteins that govern the expression of genes that allows an organism to quickly adapt to toxicity or deprivation of both biologically essential transition metal ions, e.g., Zn, Cu, Fe, and heavy metal pollutants. As such, metal sensor proteins can be considered arbiters of intracellular transition metal bioavailability and thus potentially control the metallation state of the metalloproteins in the cell. Metal sensor proteins are specialized allosteric proteins that regulate transcription as a result direct binding of one or two cognate metal ions, to the exclusion of all others. In most cases, the binding of the cognate metal ion induces a structural change in a protein oligomer that either activates or inhibits operator DNA binding. A quantitative measure of the degree to which a particular metal drives metalloregulation of operator DNA-binding is the allosteric coupling free energy, ΔGc. In this review, we summarize recent work directed toward understanding metal occupancy and metal selectivity of these allosteric switches in selected families of metal sensor proteins and examine the structural origins of ΔGc in the functional context a thermodynamic “set-point” model of intracellular metal homeostasis. PMID:22178748

  19. Fluoroquinolone-metal complexes: a route to counteract bacterial resistance?

    PubMed

    Feio, Maria J; Sousa, Isabel; Ferreira, Mariana; Cunha-Silva, Luís; Saraiva, Raúl G; Queirós, Carla; Alexandre, José G; Claro, Vasco; Mendes, Adélia; Ortiz, Rosa; Lopes, Sandra; Amaral, Ana Luísa; Lino, João; Fernandes, Patrícia; Silva, Ana João; Moutinho, Lisete; de Castro, Baltazar; Pereira, Eulália; Perelló, Lourdes; Gameiro, Paula

    2014-09-01

    Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH7.4) only copper(II):FQ:phen ternary complexes are stable. Hence, these complexes were synthesised and characterised by means of UV-visible and IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. In these complexes, the FQ acts as a bidentate ligand that coordinates the metal cation through the carbonyl and carboxyl oxygen atoms and phen coordinates through two N-atoms forming the equatorial plane of a distorted square-pyramidal geometry. The fifth position of the penta-coordinated Cu(II) centre is generally occupied axially by an oxygen atom from a water molecule or from a nitrate ion. Minimum inhibitory concentration (MIC) determinations of the complexes and comparison with free FQ in various E. coli strains indicate that the Cu-complexes are as efficient antimicrobials as the free antibiotic. Moreover, results strongly suggest that the cell intake route of both species is different supporting, therefore, the complexes' suitability as candidates for further biological testing in FQ-resistant microorganisms.

  20. Progress in bioleaching: fundamentals and mechanisms of bacterial metal sulfide oxidation--part A.

    PubMed

    Vera, Mario; Schippers, Axel; Sand, Wolfgang

    2013-09-01

    Bioleaching of metal sulfides is performed by a diverse group of microorganisms. The dissolution chemistry of metal sulfides follows two pathways, which are determined by the mineralogy and the acid solubility of the metal sulfides: the thiosulfate and the polysulfide pathways. Bacterial cells can effect this metal sulfide dissolution via iron(II) ion and sulfur compound oxidation. Thereby, iron(III) ions and protons, the metal sulfide-attacking agents, are available. Cells can be active either in planktonic state or in forming biofilms on the mineral surface; however, the latter is much more efficient in terms of bioleaching kinetics. In the case of Acidithiobacillus ferrooxidans, bacterial exopolymers contain iron(III) ions, each complexed by two uronic acid residues. The resulting positive charge allows an electrostatic attachment to the negatively charged pyrite. Thus, the first function of complexed iron(III) ions is the mediation of cell attachment, while their second function is oxidative dissolution of the metal sulfide, similar to the role of free iron(III) ions in non-contact leaching. In both cases, the electrons extracted from the metal sulfide reduce molecular oxygen via a redox chain forming a supercomplex spanning the periplasmic space and connecting both outer and inner membranes. In this review, we summarize some recent discoveries relevant to leaching bacteria which contribute to a better understanding of these fascinating microorganisms. These include surface science, biochemistry of iron and sulfur metabolism, anaerobic metabolism, and biofilm formation. The study of microbial interactions among multispecies leaching consortia, including cell-to-cell communication mechanisms, must be considered in order to reveal more insights into the biology of bioleaching microorganisms and their potential biotechnological use.

  1. Effect of metals on a siderophore producing bacterial isolate and its implications on microbial assisted bioremediation of metal contaminated soils.

    PubMed

    Gaonkar, Teja; Bhosle, Saroj

    2013-11-01

    A bacterial isolate producing siderophore under iron limiting conditions, was isolated from mangroves of Goa. Based on morphological, biochemical, chemotaxonomical and 16S rDNA studies, the isolate was identified as Bacillus amyloliquefaciens NAR38.1. Preliminary characterization of the siderophore indicated it to be catecholate type with dihydroxy benzoate as the core component. Optimum siderophore production was observed at pH 7 in mineral salts medium (MSM) without any added iron with glucose as the carbon source. Addition of NaCl in the growth medium showed considerable decrease in siderophore production above 2% NaCl. Fe(+2) and Fe(+3) below 2 μM and 40 μM concentrations respectively, induced siderophore production, above which the production was repressed. Binding studies of the siderophore with Fe(+2) and Fe(+3) indicated its high affinity towards Fe(+3). The siderophore concentration in the extracellular medium was enhanced when MSM was amended with essential metals Zn, Co, Mo and Mn, however, decreased with Cu, while the concentration was reduced with abiotic metals As, Pb, Al and Cd. Significant increase in extracellular siderophore production was observed with Pb and Al at concentrations of 50 μM and above. The effect of metals on siderophore production was completely mitigated in presence of Fe. The results implicate effect of metals on the efficiency of siderophore production by bacteria for potential application in bioremediation of metal contaminated iron deficient soils especially in the microbial assisted phytoremediation processes.

  2. Adsorption to metal oxides of the Pseudomonas aeruginosa siderophore pyoverdine and implications for bacterial biofilm formation on metals.

    PubMed

    Upritchard, Hamish G; Yang, Jing; Bremer, Philip J; Lamont, Iain L; McQuillan, A James

    2007-06-19

    The initiation of biofilm formation is poorly understood, and in particular, the contribution of chemical bond formation between bacterial cells and metal surfaces has received little attention. We have previously used in situ infrared spectroscopy to show, during the initial stages of Pseudomonas aeruginosa biofilm formation, the formation of coordinate covalent bonds between titanium dioxide particle films and pyoverdine, a mixed catecholate and hydroxamate siderophore. Here we show using infrared spectroscopy that pyoverdine can also form covalent bonds with particle films of Fe2O3, CrOOH, and AlOOH. Adsorption to the metal oxides through the catechol-like 2,3-diamino-6,7-dihydroxyquinoline part of pyoverdine was most evident in the infrared spectrum of the adsorbed pyoverdine molecule. Weaker infrared absorption bands that are consistent with the hydroxamic acids of pyoverdine binding covalently to TiO2, Fe2O3, and AlOOH surfaces were also observed. The adsorption of pyoverdine to TiO2 and Fe2O3 surfaces showed a pH dependence that is indicative of the dominance of the catechol-like ligand of pyoverdine. Infrared absorption bands were also evident for pyoverdine associated with the cells of P. aeruginosa on TiO2 and Fe2O3 surfaces and were notably absent for genetically modified cells unable to synthesize or bind pyoverdine at the cell surface. These studies confirm the generality of pyoverdine-metal bond formation and suggest a wider involvement of siderophores in bacterial biofilm initiation on metals.

  3. Influence of (bi)carbonate on bacterial interaction with quartz and metal oxide-coated surfaces.

    PubMed

    Park, Seong-Jik; Kim, Song-Bae

    2010-03-01

    This study investigated the influence of (bi)carbonate on the adhesion of bacteria (Bacillus subtilis ATCC 6633) to quartz, aluminum oxide-coated, and iron oxide-coated surfaces. Column experiments were conducted at various NaHCO(3) concentrations. Bacterial breakthrough curves were obtained by monitoring effluent, and mass recoveries were quantified from these curves. With NaHCO(3) concentrations varying from 0 to 200mM, the corresponding effective ionic strength varied from 0 to 149.0mM and solution pH from 6.2 to 8.7. Results show that at low and intermediate NaHCO(3) concentrations (1 and 10mM), bacterial adhesion to negatively charged quartz sand increased with increasing NaHCO(3) concentration, due to compression of the electrical double layers. At high NaHCO(3) concentrations (100 and 200mM), however, bacterial attachment to quartz sand decreased compared to the case of 10mM, possibly due to formation of short-range forces (steric repulsion/hydration force) by high ionic strength. In aluminum-coated sand, bacterial adhesion decreased gradually with increasing NaHCO(3) concentrations, due to charge modification from positive to negative by adsorbed (bi)carbonate ions. At low concentrations of 0.1 and 1mM, bacterial attachment to iron-coated sand surfaces decreased with increasing NaHCO(3) concentration, due to charge modification of coated sand surfaces from positive to negative. At intermediate concentration of 10mM, iron-coated sand surfaces were negatively charged like quartz sand, and so the presence of (bi)carbonate ions resulted in the increment of bacterial adhesion due to compression of the electrical double layers. At high concentrations of 100 and 200mM (pH 8.5-8.6), where iron-coated surfaces were negatively charged, bacterial deposition decreased compared to the case of 10mM, possibly due to the same phenomenon observed in quartz sand (short-range forces). This study demonstrates that bacterial adhesions to quartz and metal oxide-coated surfaces

  4. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance.

    PubMed

    Hölzel, Christina S; Müller, Christa; Harms, Katrin S; Mikolajewski, Sabine; Schäfer, Stefanie; Schwaiger, Karin; Bauer, Johann

    2012-02-01

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against β-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against β-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  5. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

    SciTech Connect

    Hoelzel, Christina S.; Mueller, Christa; Harms, Katrin S.; Mikolajewski, Sabine; Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann

    2012-02-15

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  6. Bacterial assisted degradation of chlorpyrifos: The key role of environmental conditions, trace metals and organic solvents.

    PubMed

    Khalid, Saira; Hashmi, Imran; Khan, Sher Jamal

    2016-03-01

    Wastewater from pesticide industries, agricultural or surface runoff containing pesticides and their residues has adverse environmental impacts. Present study demonstrates effect of petrochemicals and trace metals on chlorpyrifos (CP) biotransformation often released in wastewater of agrochemical industry. Biodegradation was investigated using bacterial strain Pseudomonas kilonensis SRK1 isolated from wastewater spiked with CP. Optimal environmental conditions for CP removal were CFU (306 × 10(6)), pH (8); initial CP concentration (150 mg/L) and glucose as additional carbon source. Among various organic solvents (petrochemicals) used in this study toluene has stimulatory effect on CP degradation process using SRK1, contrary to this benzene and phenol negatively inhibited degradation process. Application of metal ions (Cu (II), Fe (II) Zn (II) at low concentration (1 mg/L) took part in biochemical reaction and positively stimulated CP degradation process. Metal ions at high concentrations have inhibitory effect on degradation process. A first order growth model was shown to fit the data. It could be concluded that both type and concentration of metal ions and petrochemicals can affect CP degradation process.

  7. Bacterial contamination of fabric and metal-bead identity card lanyards: a cross-sectional study.

    PubMed

    Pepper, Thomas; Hicks, Georgina; Glass, Stephen; Philpott-Howard, John

    2014-01-01

    In healthcare, fabric or metal-bead lanyards are universally used for carrying identity cards. However there is little information on microbial contamination with potential pathogens that may readily re-contaminate disinfected hands. We examined 108 lanyards from hospital staff. Most grew skin flora but 7/108 (6%) had potentially pathogenic bacteria: four grew methicillin-susceptible Staphylococcus aureus, and four grew probable fecal flora: 3 Clostridium perfringens and 1 Clostridium bifermentans (one lanyard grew both S. aureus and C. bifermentans). Unused (control) lanyards had little or no such contamination. The median duration of lanyard wear was 12 months (interquartile range 3-36 months). 17/108 (16%) of the lanyards had reportedly undergone decontamination including wiping with alcohol, chlorhexidine or chlorine dioxide; and washing with soap and water or by washing machine. Metal-bead lanyards had significantly lower median bacterial counts than those from fabric lanyards (1 vs. 4 CFU/cm(2); Mann-Whitney U=300.5; P<0.001). 12/32 (38%) of the metal-bead lanyards grew no bacteria, compared with 2/76 (3%) of fabric lanyards. We recommend that an effective decontamination regimen be instituted by those who use fabric lanyards, or that fabric lanyards be discarded altogether in preference for metal-bead lanyards or clip-on identity cards. PMID:25151656

  8. A suite of recombinant luminescent bacterial strains for the quantification of bioavailable heavy metals and toxicity testing

    PubMed Central

    2009-01-01

    Background Recombinant whole-cell sensors have already proven useful in the assessment of the bioavailability of environmental pollutants like heavy metals and organic compounds. In this work 19 recombinant bacterial strains representing various Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas fluorescens) bacteria were constructed to express the luminescence encoding genes luxCDABE (from Photorhabdus luminescens) as a response to bioavailable heavy metals ("lights-on" metal sensors containing metal-response elements, 13 strains) or in a constitutive manner ("lights-off" constructs, 6 strains). Results The bioluminescence of all 13 "lights-on" metal sensor strains was expressed as a function of the sub-toxic metal concentrations enabling the quantitative determination of metals bioavailable for these strains. Five sensor strains, constructed for detecting copper and mercury, proved to be target metal specific, whereas eight other sensor strains were simultaneously induced by Cd2+, Hg2+, Zn2+and Pb2+. The lowest limits of determination of the "lights-on" sensor strains for the metals tested in this study were (μg l-1): 0.002 of CH3HgCl, 0.03 of HgCl2, 1.8 of CdCl2, 33 of Pb(NO3)2, 1626 of ZnSO4, 24 of CuSO4 and 340 of AgNO3. In general, the sensitivity of the "lights-on" sensor strains was mostly dependent on the metal-response element used while the selection of host bacterium played a relatively minor role. In contrast, toxicity of metals to the "lights-off" strains was only dependent on the bacterial host so that Gram-positive strains were remarkably more sensitive than Gram-negative ones. Conclusion The constructed battery of 19 recombinant luminescent bacterial strains exhibits several novel aspects as it contains i) metal sensor strains with similar metal-response elements in different host bacteria; ii) metal sensor strains with metal-response elements in different copies and iii) a "lights

  9. Composition, Reactivity and Regulation of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal - Reducing Bacteria.

    SciTech Connect

    Beveridge, Terrance J; Whitfield, Christopher

    2013-03-06

    This is the final technical report for the project. There were two objectives in the proposal. The first was to describe the composition and function of electrically conductive appendages, known as bacterial nanowires, which resemble pili but are longer and are electrically conductive. They were first identified on the dissimilatory metal-reducing bacteria (DMRB), Shewanella and Geobacter. Specifically, this project investigated the role of these structures in: (i) the reductive transformation of iron oxides as solid phase electron acceptors; (ii) the use of as uranium as a dissolved electron acceptor to form nanocrystalline particles of uraninite upon reduction. The Beveridge group investigated these processes using advanced cryo-transmission electron microscopy (cryoTEM) to visualize the points of connection between the distal ends of nanowires and the effect they have on solid phase Fe minerals. At the same time, immuno-electron microscopy was applied in an attempt to identify where metal reductases and cytochromes are located on the cell surface, or in the nanowires. The second objective was to define the surface physicochemistry of Shewanella spp. in an attempt to decipher how weak bonding (electrostatics and hydrophobicity) affects the adherence of the bacteria to Fe oxides. This bonding could be dictated by the chemistry of lipopolysaccharide (LPS), or the presence/absence of capsular polysaccharide.

  10. Isolation and Genomic Characterization of ‘Desulfuromonas soudanensis WTL’, a Metal- and Electrode-Respiring Bacterium from Anoxic Deep Subsurface Brine

    PubMed Central

    Badalamenti, Jonathan P.; Summers, Zarath M.; Chan, Chi Ho; Gralnick, Jeffrey A.; Bond, Daniel R.

    2016-01-01

    Reaching a depth of 713 m below the surface, the Soudan Underground Iron Mine (Soudan, MN, USA) transects a massive Archaean (2.7 Ga) banded iron formation, providing a remarkably accessible window into the terrestrial deep biosphere. Despite organic carbon limitation, metal-reducing microbial communities are present in potentially ancient anoxic brines continuously emanating from exploratory boreholes on Level 27. Using graphite electrodes deposited in situ as bait, we electrochemically enriched and isolated a novel halophilic iron-reducing Deltaproteobacterium, ‘Desulfuromonas soudanensis’ strain WTL, from an acetate-fed three-electrode bioreactor poised at +0.24 V (vs. standard hydrogen electrode). Cyclic voltammetry revealed that ‘D. soudanensis’ releases electrons at redox potentials approximately 100 mV more positive than the model freshwater surface isolate Geobacter sulfurreducens, suggesting that its extracellular respiration is tuned for higher potential electron acceptors. ‘D. soudanensis’ contains a 3,958,620-bp circular genome, assembled to completion using single-molecule real-time (SMRT) sequencing reads, which encodes a complete TCA cycle, 38 putative multiheme c-type cytochromes, one of which contains 69 heme-binding motifs, and a LuxI/LuxR quorum sensing cassette that produces an unidentified N-acyl homoserine lactone. Another cytochrome is predicted to lie within a putative prophage, suggesting that horizontal gene transfer plays a role in respiratory flexibility among metal reducers. Isolation of ‘D. soudanensis’ underscores the utility of electrode-based approaches for enriching rare metal reducers from a wide range of habitats. PMID:27445996

  11. Degradation of metal-EDTA complexes by resting cells of the bacterial strain DSM 9103

    SciTech Connect

    Satroutdinov, A.D.; Dedyukhina, E.G.; Chistyakova, T.I.; Witschel, M.; Minkevich, I.G.; Eroshin, V.K.; Egli, T.

    2000-05-01

    Ethylenediaminetetraacetate (EDTA), an industrially important chelating agent, forms very stable complexes with di- and trivalent metal ions, and in both wastewater and natural waters it is normally present in the metal-associated form. Therefore, the influence of EDTA speciation on its utilization by the EDTA-degrading bacterial strain DSM 9103 was investigated. EDTA-grown cells harvested from the exponential phase of a batch culture were incubated with 1 mM of various EDTA species and the EDTA concentration in the assay was monitored as a function of time. Uncomplexed EDTA as well as complexes with low stability constants were found to be readily degraded to completion at a constant rate. For more stable EDTA chelates (i.e., chelates of Co{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, and Pb{sup 2+}) the data suggest that these complexes were not used directly by the cells but that they had to dissociate prior to degradation. The rate of this dissociation step possibly determined the microbial degradation of these complexes. CdEDTA{sup 2{minus}} and Fe(III)EDTA{sup {minus}} were not degraded within 48 h. In case of CdEDTA{sup 2{minus}} the toxicity of freed Cd{sup 2+} ions most likely prevented a significant degradation of the complex, whereas in case of Fe(III)EDTA{sup {minus}} a combination of metal or complex toxicity and the very slow dissociation of the complex might explain the absence of degradation.

  12. Bacterial pretreatment enhances removal of heavy metals during treatment of post-methanated distillery effluent by Typha angustata L.

    PubMed

    Chandra, R; Yadav, S; Bharagava, R N; Murthy, R C

    2008-09-01

    A combination of bacterial pretreatment followed by free water surface flow through wetland plants was investigated to determine its effect on removal of heavy metals in bioremediation of post-methanated distillery effluent (PMDE). The bacterial pretreatment was intended to transform the metal complexes and organic pollutants into simpler, biologically assimilable molecules. The 10% and 30% v/v concentrations of PMDE favored luxuriant bacterial growth; the 50% concentration supported less growth, whereas the undiluted effluent (i.e., 100%) supported very little bacterial growth. The use of bacterial pretreatment combined with the constructed wetland system greatly increase the overall bioaccumulation of all heavy metals by the plants compared with the control treatment. However, the integration of bacterial pretreatment of PMDE with the Typha angustata resulted in enhanced removal of Cd (34.02-61.50% increase), Cr (35.90-57.60% increase), Cu (32.88-54.22% increase), Fe (32.50-51.26% increase), Mn (35.99-82.85% increase), Ni (35.85-59.24% increase), Pb (33.45-59.51% increase) and Zn (31.95-53.70% increase) compared with a control that lacked this pretreatment. In addition to the bioaccumulation of these heavy metals, several physico-chemical parameters also improved at the 30% effluent concentration: color, BOD, COD, phenol and total nitrogen decreased by 98.33%, 98.89%, 98.50%, 93.75% and 82.39%, respectively, after 7 days of free water surface flow treatment. The results suggest that bacterial pretreatment of PMDE, integrated with phytoremediation will improve the treatment process of PMDE and promote safer disposal of this waste.

  13. Anaerobic respiration on tellurate and other metalloids in bacteria from hydrothermal vent fields in the eastern Pacific Ocean.

    PubMed

    Csotonyi, Julius T; Stackebrandt, Erko; Yurkov, Vladimir

    2006-07-01

    This paper reports the discovery of anaerobic respiration on tellurate by bacteria isolated from deep ocean (1,543 to 1,791 m) hydrothermal vent worms. The first evidence for selenite- and vanadate-respiring bacteria from deep ocean hydrothermal vents is also presented. Enumeration of the anaerobic metal(loid)-resistant microbial community associated with hydrothermal vent animals indicates that a greater proportion of the bacterial community associated with certain vent fauna resists and reduces metal(loid)s anaerobically than aerobically, suggesting that anaerobic metal(loid) respiration might be an important process in bacteria that are symbiotic with vent fauna. Isolates from Axial Volcano and Explorer Ridge were tested for their ability to reduce tellurate, selenite, metavanadate, or orthovanadate in the absence of alternate electron acceptors. In the presence of metal(loid)s, strains showed an ability to grow and produce ATP, whereas in the absence of metal(loid)s, no growth or ATP production was observed. The protonophore carbonyl cyanide m-chlorophenylhydrazone depressed metal(loid) reduction. Anaerobic tellurate respiration will be a significant component in describing biogeochemical cycling of Te at hydrothermal vents.

  14. Biodegradation of the metallic carcinogen hexavalent chromium Cr(VI) by an indigenously isolated bacterial strain

    PubMed Central

    Mishra, Susmita

    2010-01-01

    Background: Hexavalent chromium [Cr(VI)], a potential mutagen and carcinogen, is regularly introduced into the environment through diverse anthropogenic activities, including electroplating, leather tanning, and pigment manufacturing. Human exposure to this toxic metal ion not only causes potential human health hazards but also affects other life forms. The World Health Organization, the International Agency for Research on Cancer, and the Environmental Protection Agency have determined that Cr(VI) compounds are known human carcinogens. The Sukinda valley in Jajpur District, Orissa, is known for its deposit of chromite ore, producing nearly 98% of the chromite ore in India and one of the prime open cast chromite ore mines in the world (CES, Orissa Newsletter). Materials and Methods: Our investigation involved microbial remediation of Cr(VI) without producing any byproduct. Bacterial cultures tolerating high concentrations of Cr were isolated from the soil sample collected from the chromite-contaminated sites of Sukinda, and their bioaccumulation properties were investigated. Strains capable of growing at 250 mg/L Cr(VI) were considered as Cr resistant. Results: The experimental investigation showed the maximum specific Cr uptake at pH 7 and temperature 30°C. At about 50 mg/L initial Cr(VI) concentrations, uptake of the selected potential strain exceeded 98% within 12 h of incubation. The bacterial isolate was identified by 16S rRNA sequencing as Brevebacterium casei. Conclusion: Results indicated promising approach for microbial remediation of effluents containing elevated levels of Cr(VI). PMID:20976016

  15. Bacterial degradation of cyanide and its metal complexes under alkaline conditions.

    PubMed

    Luque-Almagro, Víctor M; Huertas, María-J; Martínez-Luque, Manuel; Moreno-Vivián, Conrado; Roldán, M Dolores; García-Gil, L Jesús; Castillo, Francisco; Blasco, Rafael

    2005-02-01

    A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Coleccion Espanola de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) the bacterium stoichiometrically converted cyanide into ammonium in the presence of l-methionine-d,l-sulfoximine, a glutamine synthetase inhibitor. The bacterium was able to grow in alkaline media, up to an initial pH of 11.5, and tolerated free cyanide in concentrations of up to 30 mM, which makes it a good candidate for the biological treatment of cyanide-contaminated residues. Both acetate and d,l-malate were suitable carbon sources for cyanotrophic growth, but no growth was detected in media with cyanide as the sole carbon source. In addition to cyanide, P. pseudoalcaligenes CECT5344 used other nitrogen sources, namely ammonium, nitrate, cyanate, cyanoacetamide, nitroferricyanide (nitroprusside), and a variety of cyanide-metal complexes. Cyanide and ammonium were assimilated simultaneously, whereas cyanide strongly inhibited nitrate and nitrite assimilation. Cyanase activity was induced during growth with cyanide or cyanate, but not with ammonium or nitrate as the nitrogen source. This result suggests that cyanate could be an intermediate in the cyanide degradation pathway, but alternative routes cannot be excluded.

  16. The effect of metal loading on Cd adsorption onto Shewanella oneidensis bacterial cell envelopes: The role of sulfhydryl sites

    NASA Astrophysics Data System (ADS)

    Yu, Qiang; Fein, Jeremy B.

    2015-10-01

    The adsorption and desorption of Cd onto Shewanella oneidensis bacterial cells with and without blocking of sulfhydryl sites was measured in order to determine the effect of metal loading and to understand the role of sulfhydryl sites in the adsorption reactions. The observed adsorption/desorption behaviors display strong dependence on metal loading. Under a high loading of 40 μmol Cd/g bacterial cells, blocking the sulfhydryl sites within the cell envelope by exposure of the biomass to monobromo(trimethylammonio)bimane bromide (qBBr) does not significantly affect the extent of Cd adsorption, and we observed fully reversible adsorption under this condition. In contrast, under a low metal loading of 1.3 μmol Cd/g bacterial cells, the extent of Cd adsorption onto sulfhydryl-blocked S. oneidensis cells was significantly lower than that onto untreated cells, and only approximately 50-60% of the adsorbed Cd desorbed from the cells upon acidification. In conjunction with previous EXAFS results, our findings demonstrate that Cd adsorption onto S. oneidensis under low metal loading conditions is dominated by sulfhydryl binding, and thus is controlled by a distinct adsorption mechanism from the non-sulfhydryl site binding which controls Cd adsorption under high metal loading conditions. We use the data to develop a surface complexation model that constrains the values of the stability constants for individual Cd-sulfhydryl and Cd-non-sulfhydryl bacterial complexes, and we use this approach to account for the Cd adsorption behavior as a function of both pH and metal loading. This approach is crucial in order to predict metal adsorption onto bacteria under environmentally relevant metal loading conditions where sulfhydryl binding sites can dominate the adsorption reaction.

  17. Dynamics of the Heme-binding Bacterial Gas-sensing Dissimilative Nitrate Respiration Regulator (DNR) and Activation Barriers for Ligand Binding and Escape*

    PubMed Central

    Lobato, Laura; Bouzhir-Sima, Latifa; Yamashita, Taku; Wilson, Michael T.; Vos, Marten H.; Liebl, Ursula

    2014-01-01

    DNR (dissimilative nitrate respiration regulator) is a heme-binding transcription factor that is involved in the regulation of denitrification in Pseudomonas aeruginosa. In the ferrous deoxy state, the heme is 6-coordinate; external NO and CO can replace an internal ligand. Using fluorescence anisotropy, we show that high-affinity sequence-specific DNA binding occurs only when the heme is nitrosylated, consistent with the proposed function of DNR as NO sensor and transcriptional activator. This role is moreover supported by the NO “trapping” properties revealed by ultrafast spectroscopy that are similar to those of other heme-based NO sensor proteins. Dissociated CO-heme pairs rebind in an essentially barrierless way. This process competes with migration out of the heme pocket. The latter process is thermally activated (Ea ∼7 kJ/mol). This result is compared with other heme proteins, including the homologous CO sensor/transcription factor CooA, variants of the 5-coordinate mycobacterial sensor DosT and the electron transfer protein cytochrome c. This comparison indicates that thermal activation of ligand escape from the heme pocket is specific for systems where an external ligand replaces an internal one. The origin of this finding and possible implications are discussed. PMID:25037216

  18. Ecofriendly biosorption of dyes and metals by bacterial biomass of Aeromonas hydrophila RC1.

    PubMed

    Busi, Siddhardha; Chatterjee, Rahul; Rajkumari, Jobina; Hnamte, Sairengpuii

    2016-03-01

    The ability of dried bacterial biomass in azo dye and heavy metal removal from aqueous solution was explored. Biosorption of three textile dyes, Eriochrome black T (EBT), Acid Red 26 (AR) and Trypan blue (TB) and heavy metals (Pb and Cr) by dried biomass of Aeromonas hydrophila RC1, was investigated in a batch system under various parameters such as dye concentration, contact time, concentration of biomass, pH, and temperature. The experimental results showed that the extent of biosorption for dyes increased with increase in initial concentration of dyes, biomass concentration, contact time, temperature and decreased with increase in pH. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm equations. The Langmuir model yielded good fit to the experimental data (R² approximately 0.794, 0.844 and 0.969 for the dyes, EBT, AR and TB, respectively) with maximum monolayer adsorption capacity of 58.8 mg g⁻¹ for AR. Similarly results were obtained for heavy metals and the data fit in Langmuir model (R² value of 0.849 and 0.787) with q(m) value of 40 mg g⁻¹ for Pb. The results fit in pseudo first order kinetics with removal upto 96.67 % for Pb. Involvement of the surface characteristics of the biomass in biosorption was studied using scanning electron micrographs, FTIR, EDX and XRD analysis. Thus, use ofA. hydrophila RC1 biomass can be extensively employed in water treatment plants in order to get desired water quality in the most economical way.

  19. A copper metallochaperone for photosynthesis and respiration reveals metal-specific targets, interaction with an importer, and alternative sites for copper acquisition.

    PubMed

    Tottey, Stephen; Rondet, Sabine A M; Borrelly, Gilles P M; Robinson, Pamela J; Rich, Peter R; Robinson, Nigel J

    2002-02-15

    A bacterial two-hybrid assay revealed interaction between a protein now designated bacterial Atx1 and amino-terminal domains of copper-transporting ATPases CtaA (cellular import) and PacS (thylakoid import) but not the related zinc (ZiaA) or cobalt (CoaT) transporters from the same organism (Synechocystis PCC 6803). The specificity of metallochaperone interactions coincides with metal specificity. After reconstitution in a N(2) atmosphere, bacterial Atx1 bound 1 mol of copper mol(-1), and apoPacS(N) acquired copper from copper-Atx1. Copper was displaced from Atx1 by p-(hydroxymercuri)phenylsulfonate, indicative of thiol ligands, and two cysteine residues were obligatory for two-hybrid interaction with PacS(N). This organism contains compartments (thylakoids) where the copper proteins plastocyanin and cytochrome oxidase reside. In copper super-supplemented mutants, photooxidation of cytochrome c(6) was greater in Deltaatx1DeltactaA than in DeltactaA, showing that Atx1 contributes to efficient switching from iron in cytochrome c(6) to copper in plastocyanin for photosynthetic electron transport. Cytochrome oxidase activity was also less in membranes purified from low [copper]-grown Deltaatx1 or DeltapacS, compared with wild-type, but the double mutant Deltaatx1DeltapacS was non-additive, consistent with Atx1 acting via PacS. Conversely, activity in Deltaatx1DeltactaA was less than in either respective single mutant, revealing that Atx1 can function without the major copper importer and consistent with a role in recycling endogenous copper.

  20. A multi-level bioreactor to remove organic matter and metals, together with its associated bacterial diversity.

    PubMed

    Wu, Yonghong; Hu, Zhengyi; Kerr, Philip G; Yang, Linzhang

    2011-01-01

    The purpose of this study was to treat complex wastewater consisting of domestic wastewater, tobacco processing and building materials washings. The proposed multi-level bioreactor consists of a biopond-biofilter, anoxic/aerobic (A/O) fluidized beds and a photoautotrophic system. The results show that when the hydraulic load of the bioreactor was 200 m3/d, it successfully and simultaneously removed the organic matter and metals. When the bioreactor was in a relatively steady-state condition, the overall average organic matter and metals removal efficiencies are as follows, COD (89%), UV245 nm-matter (91%), Cu (78%), Zn (79%) and Fe (84%). The growth conditions of the native bacterial habitat were improved, which resulted from the increase of the in bacterial diversity under the rejuvenated conditions induced by the bioreactor. The results demonstrate that the multi-level bioreactor, without a sludge treatment system, can remove heterogeneous organic matter and metals from wastewater.

  1. Aqueous phase synthesis of copper nanoparticles: a link between heavy metal resistance and nanoparticle synthesis ability in bacterial systems.

    PubMed

    Ramanathan, Rajesh; Field, Matthew R; O'Mullane, Anthony P; Smooker, Peter M; Bhargava, Suresh K; Bansal, Vipul

    2013-03-21

    We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu(2+) ions provides new insights into the mechanistic aspect of Cu(2+) ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms.

  2. Aqueous phase synthesis of copper nanoparticles: a link between heavy metal resistance and nanoparticle synthesis ability in bacterial systems

    NASA Astrophysics Data System (ADS)

    Ramanathan, Rajesh; Field, Matthew R.; O'Mullane, Anthony P.; Smooker, Peter M.; Bhargava, Suresh K.; Bansal, Vipul

    2013-02-01

    We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu2+ ions provides new insights into the mechanistic aspect of Cu2+ ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms.We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu2+ ions provides new insights into the mechanistic aspect of Cu2+ ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms. Electronic supplementary information (ESI) available: Sequence similarity analysis of proteins involved in the silver and copper resistance machinery of bacteria. See DOI: 10.1039/c2nr32887a

  3. Bacterial Degradation of Cyanide and Its Metal Complexes under Alkaline Conditions

    PubMed Central

    Luque-Almagro, Víctor M.; Huertas, María-J.; Martínez-Luque, Manuel; Moreno-Vivián, Conrado; Roldán, M. Dolores; García-Gil, L. Jesús; Castillo, Francisco; Blasco, Rafael

    2005-01-01

    A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Colección Española de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) the bacterium stoichiometrically converted cyanide into ammonium in the presence of l-methionine-d,l-sulfoximine, a glutamine synthetase inhibitor. The bacterium was able to grow in alkaline media, up to an initial pH of 11.5, and tolerated free cyanide in concentrations of up to 30 mM, which makes it a good candidate for the biological treatment of cyanide-contaminated residues. Both acetate and d,l-malate were suitable carbon sources for cyanotrophic growth, but no growth was detected in media with cyanide as the sole carbon source. In addition to cyanide, P. pseudoalcaligenes CECT5344 used other nitrogen sources, namely ammonium, nitrate, cyanate, cyanoacetamide, nitroferricyanide (nitroprusside), and a variety of cyanide-metal complexes. Cyanide and ammonium were assimilated simultaneously, whereas cyanide strongly inhibited nitrate and nitrite assimilation. Cyanase activity was induced during growth with cyanide or cyanate, but not with ammonium or nitrate as the nitrogen source. This result suggests that cyanate could be an intermediate in the cyanide degradation pathway, but alternative routes cannot be excluded. PMID:15691951

  4. Examining trace metal contamination in an unanthropogenically impacted lake in Algonquin Park: implications for environmental bacterial communities and antibiotic resistance

    NASA Astrophysics Data System (ADS)

    Elliott, A. V.; Plach, J.; Droppo, I.; Warren, L. A.

    2009-05-01

    Identifying the biogeochemical processes influencing the interactions amongst trace metals, microbial communities, pathogenicity and antibiotic resistance (ABR) is key to predicting the emergence, dissemination and maintenance of ABR in the environmental arena. The co-selection of heavy metal resistance and ABR has been documented in metal-contaminated environments. However, as yet, little research has been conducted assessing the metal status of 'pristine' area lakes and associated environmental bacterial communities. As part of a larger project evaluating metal-bacterial-ABR-pathogen interactions, a field survey of 6 variably contaminated aquatic systems was conducted in the summer of 2008, including Brewer Lake -a highly organic, circumneutral, Fe stained lake in Algonquin Park. To our knowledge, this study is the first to assess metal concentrations for the suite of Ag, As, Cd, Co, Cu, Ni, Pb, Se, Zn amongst the water column, suspended floc and bed sediments for this lake. The characterization and sampling protocol included 1) in situ characterization of overlying water column physicochemical parameters and 2) collection of water samples, suspended flocs (by field flow centrifugation) and bed sediment samples (by core; surficial and at depth) for subsequent metal analysis. Floc- and sediment-associated metals were partitioned into 6 operationally defined solid matrix fractions by sequential extraction: the exchangeable (loosely bound); carbonate; reducible amorphous Fe/Mn hydrous oxides; reducible crystalline Fe/Mn oxides; and residual fractions. Results indicate that the partitioning of metals between solid (floc, sediments) and dissolved compartments is largely element- dependent. Mean total metal concentrations in the sediments ranged from nM (Ag,Se, Cd) to μM (As, Co, Cu, Ni, Pb, Zn) with only Cu and Co (nM) and Zn ( μM) being detected in the water column. However in all cases floc-associated metal concentrations were an order of magnitude greater than in

  5. Temporal dynamics and degradation activity of an bacterial inoculum for treating waste metal-working fluid.

    PubMed

    van der Gast, Christopher J; Whiteley, Andrew S; Thompson, Ian P

    2004-03-01

    In order for established bioreactors to be effective for treating chemically mixed wastes such as metal working fluids (MWF) it is essential that they harbour microbial populations that can maintain sufficient active biomass and degrade each of the chemical constituents present. In this study we investigated the effectiveness of a bacterial consortium composed of four species (Clavibacter michiganensis, Methylobacterium mesophilicum, Rhodococcus erythropolis and Pseudomonas putida), assembled on the basis of their apparent ubiquity in waste MWF, degradation ability and tolerance to fluctuating chemistry of the waste. The temporal dynamics of the inoculum and its effects on the fate of individual chemical components of the waste were studied, by regular sampling, over 400 h. Using a complementary approach of culture with chemotaxonomic (FAME) analysis and applying group specific probes (FISH), the inoculum was found to represent a significant component of the community in bioreactors with and without presence of indigenous MWF populations. In addition, the reduction in the COD by the consortium was approximately 85% of the total pollution load, and 30-40% more effectively than any other treatment (indigenous MWF community alone or activated sludge). Furthermore, all the chemical constituents, including the biocide (a formaldehyde release agent) demonstrated > 60% reduction. Many chemical components of the MWF proved to be recalcitrant in the other treatments. The results of this study confirm that assemblage of an inoculum, based on a comprehensive knowledge of the indigenous microbial community, in the target habitat, is a highly effective way of selecting microbial populations for bioaugmentation of bioreactors.

  6. Nosepiece respiration monitor

    NASA Technical Reports Server (NTRS)

    Lavery, A. L.; Long, L. E.; Rice, N. E.

    1968-01-01

    Comfortable, inexpensive nosepiece respiration monitor produces rapid response signals to most conventional high impedance medical signal conditioners. The monitor measures respiration in a manner that produces a large signal with minimum delay.

  7. Respiration in the light and bacterio-phytoplankton coupling in a coastal environment.

    PubMed

    Pringault, Olivier; Tesson, Sylvie; Rochelle-Newall, Emma

    2009-02-01

    In pelagic ecosystems, the principal source of organic matter is via autotrophic production and the primary sink is through heterotrophic respiration. One would therefore anticipate that there is some degree of linkage between these two compartments. Recent work has shown that respiration in the light is higher than dark respiration. Consequently, many of the methods used to determine respiration and production are biased as they require the assumption that light and dark respiration rates are equivalent. We show here that, in a coastal ecosystem, under visible light exposure, respiration in the light is related to gross production. More than 60% of the variation of respiration in the light, measured at 1 to 40 microg L(-1) of chlorophyll a (Chla), could be explained by the variations of gross production. Secondly, the relative contribution of bacterial respiration to community respiration in the light represented up to 79% at low Chla (1 microg L(-1)) and was negatively correlated with Chla concentration. Although bacterial production and bacterial respiration were both enhanced in the light, bacterial respiration in the light was more stimulated than bacterial production, which resulted in a decrease in bacterial growth efficiency during light exposure. These results show that the impact of light on the functioning of the microbial loop needs to be taken into account for a better understanding of the oceanic carbon cycle.

  8. Health risk assessment of heavy metals and bacterial contamination in drinking water sources: a case study of Malakand Agency, Pakistan.

    PubMed

    Nawab, Javed; Khan, Sardar; Ali, Sharafat; Sher, Hassan; Rahman, Ziaur; Khan, Kifayatullah; Tang, Jianfeng; Ahmad, Aziz

    2016-05-01

    Human beings are frequently exposed to pathogens and heavy metals through ingestion of contaminated drinking water throughout the world particularly in developing countries. The present study aimed to assess the quality of water used for drinking purposes in Malakand Agency, Pakistan. Water samples were collected from different sources (dug wells, bore wells, tube wells, springs, and hand pumps) and analyzed for different physico-chemical parameters and bacterial pathogens (fecal coliform bacteria) using standard methods, while heavy metals were analyzed using atomic absorption spectrophotometry (AAS-PEA-700). In the study area, 70 % of water sources were contaminated with F. coliform representing high bacterial contamination. The heavy metals, such as Cd (29 and 8 %), Ni (16 and 78 %), and Cr (7 %), exceeded their respective safe limits of WHO (2006) and Pak-EPA (2008), respectively, in water sources, while Pb (9 %) only exceeded from WHO safe limit. The risk assessment tools such as daily intake of metals (DIMs) and health risk indexes (HRIs) were used for health risk estimation and were observed in the order of Ni > Cr > Mn > Pb > Cd and Cd > Ni > Pb > Mn > Cr, respectively. The HRI values of heavy metals for both children and adults were <1, showing lack of potential health risk to the local inhabitants of the study area. PMID:27075311

  9. Pyrosequencing analysis of bacterial diversity in soils contaminated long-term with PAHs and heavy metals: Implications to bioremediation.

    PubMed

    Kuppusamy, Saranya; Thavamani, Palanisami; Megharaj, Mallavarapu; Venkateswarlu, Kadiyala; Lee, Yong Bok; Naidu, Ravi

    2016-11-01

    Diversity, distribution and composition of bacterial community of soils contaminated long-term with both polycyclic aromatic hydrocarbons (PAHs) and heavy metals were explored for the first time following 454 pyrosequencing. Strikingly, the complete picture of the Gram positive (+ve) and Gram negative (-ve) bacterial profile obtained in our study illustrates novel postulates that include: (1) Metal-tolerant and PAH-degrading Gram -ves belonging to the class Alphaproteobacteria persist relatively more in the real contaminated sites compared to Gram +ves, (2) Gram +ves are not always resistant to heavy metal toxicity, (3) Stenotrophomonas followed by Burkholderia and Pseudomonas are the dominant genera of PAH degraders with high metabolic activity in long-term contaminated soils, (4) Actinobacteria is the predominant group among the Gram +ves in soils contaminated with high molecular weight PAHs that co-exist with toxic heavy metals like Pb, Cu and Zn, (5) Microbial communities are nutrient-driven in natural environments and (6) Catabolically potential Gram +/-ves with diverse applicability to remediate the real contaminated sites evolve eventually in the historically-polluted soils. Thus, the most promising indigenous Gram +/-ve strains from the long-term contaminated sites with increased catabolic potential, enzymatic activity and metal tolerance need to be harnessed for mixed contaminant cleanups.

  10. Health risk assessment of heavy metals and bacterial contamination in drinking water sources: a case study of Malakand Agency, Pakistan.

    PubMed

    Nawab, Javed; Khan, Sardar; Ali, Sharafat; Sher, Hassan; Rahman, Ziaur; Khan, Kifayatullah; Tang, Jianfeng; Ahmad, Aziz

    2016-05-01

    Human beings are frequently exposed to pathogens and heavy metals through ingestion of contaminated drinking water throughout the world particularly in developing countries. The present study aimed to assess the quality of water used for drinking purposes in Malakand Agency, Pakistan. Water samples were collected from different sources (dug wells, bore wells, tube wells, springs, and hand pumps) and analyzed for different physico-chemical parameters and bacterial pathogens (fecal coliform bacteria) using standard methods, while heavy metals were analyzed using atomic absorption spectrophotometry (AAS-PEA-700). In the study area, 70 % of water sources were contaminated with F. coliform representing high bacterial contamination. The heavy metals, such as Cd (29 and 8 %), Ni (16 and 78 %), and Cr (7 %), exceeded their respective safe limits of WHO (2006) and Pak-EPA (2008), respectively, in water sources, while Pb (9 %) only exceeded from WHO safe limit. The risk assessment tools such as daily intake of metals (DIMs) and health risk indexes (HRIs) were used for health risk estimation and were observed in the order of Ni > Cr > Mn > Pb > Cd and Cd > Ni > Pb > Mn > Cr, respectively. The HRI values of heavy metals for both children and adults were <1, showing lack of potential health risk to the local inhabitants of the study area.

  11. Enhancement of Bacterial Transport in Aerobic and Anaerobic Environments: Assessing the Effect of Metal Oxide Chemical Heterogeneities

    SciTech Connect

    T.C. Onstott

    2005-09-30

    The goal of our research was to understand the fundamental processes that control microbial transport in physically and chemically heterogeneous aquifers and from this enhanced understanding determine the requirements for successful, field-scale delivery of microorganisms to metal contaminated subsurface sites. Our specific research goals were to determine; (1) the circumstances under which the preferential adsorption of bacteria to Fe, Mn, and Al oxyhydroxides influences field-scale bacterial transport, (2) the extent to which the adhesion properties of bacterial cells affect field-scale bacterial transport, (3) whether microbial Fe(III) reduction can enhance field-scale transport of Fe reducing bacteria (IRB) and other microorganisms and (4) the effect of field-scale physical and chemical heterogeneity on all three processes. Some of the spin-offs from this basic research that can improve biostimulation and bioaugmentation remediation efforts at contaminated DOE sites have included; (1) new bacterial tracking tools for viable bacteria; (2) an integrated protocol which combines subsurface characterization, laboratory-scale experimentation, and scale-up techniques to accurately predict field-scale bacterial transport; and (3) innovative and inexpensive field equipment and methods that can be employed to enhance Fe(III) reduction and microbial transport and to target microbial deposition under both aerobic and anaerobic conditions.

  12. The application of a micro-algal/bacterial biofilter for the detoxification of copper and cadmium metal wastes.

    PubMed

    Loutseti, S; Danielidis, D B; Economou-Amilli, A; Katsaros, Ch; Santas, R; Santas, Ph

    2009-04-01

    In the present study the potential of a biofilter containing a mixture of dried micro-algal/bacterial biomass for removing heavy metals (Cu(2+), Cd(2+)) from dilute electroplating waste was tested. The biomass was produced in an artificial stream using the effluent of a municipal waste water treatment plant as a nutrient source, with the additional benefit of reducing phosphorus and nitrogen loadings. Baseline batch experiments determined that optimum adsorption for both metals (80-100%) were achieved with the deionized-H(2)O conditioned biomass at initial pH 4.0. Other biosorption variables (contact time, initial metal concentration) were also tested. Biosorption data were fitted successfully by the Langmuir model and results showed a high affinity of the used biomass for both metals (q(max) 18-31 mg metal/g.d.w). Flow-through column experiments containing Ca-alginate/biomass beads showed that metal adsorption depends also on flow-rate and volume of treated waste. Desorption of both metals with weak acids was very successful (95-100%) but the regeneration of the columns was not achieved due to the destabilization of beads.

  13. Bioremediation of high molecular weight polyaromatic hydrocarbons co-contaminated with metals in liquid and soil slurries by metal tolerant PAHs degrading bacterial consortium.

    PubMed

    Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

    2012-11-01

    Bioremediation of polyaromatic hydrocarbons (PAH) contaminated soils in the presence of heavy metals have proved to be difficult and often challenging due to the ability of toxic metals to inhibit PAH degradation by bacteria. In this study, a mixed bacterial culture designated as consortium-5 was isolated from a former manufactured gas plant (MGP) site. The ability of this consortium to utilise HMW PAHs such as pyrene and BaP as a sole carbon source in the presence of toxic metal Cd was demonstrated. Furthermore, this consortium has proven to be effective in degradation of HMW PAHs even from the real long term contaminated MGP soil. Thus, the results of this study demonstrate the great potential of this consortium for field scale bioremediation of PAHs in long term mix contaminated soils such as MGP sites. To our knowledge this is the first study to isolate and characterize metal tolerant HMW PAH degrading bacterial consortium which shows great potential in bioremediation of mixed contaminated soils such as MGP.

  14. Modeling interactions of toxic metals with suspended bacterial cells, extracellular polymer and biofilms in a simulated freshwater environment

    SciTech Connect

    Nelson, Y.M.; Lo, W.; Lion, L.W.

    1995-12-01

    The transport of transition metals in aquatic environments is governed by their interactions with suspended and adherent biological materials and with colloidal and deposited metal oxides. These interactions were investigated using a laboratory biofilm reactor system containing a pure culture of a single bacterial species (Pseudomonas cepacia) to exemplify biological factors influencing trace metals. Use of controlled conditions allowed for development of mechanistic models to describe bacterial growth and attachment, extracellular polymer production, and biofilm accumulation as well as the interactions of each of these phases with trace metals (exemplified by lead). Lead binding to each component of the system was characterized by determining adsorption isotherms in separate experiments. Integration of the biological model with lead binding data and a chemical equilibrium program (MINEQL) to determine speciation provided a general mechanistic model to predict lead transport and distribution. The most significant factors influencing lead distribution in these experiments were lead binding to biofilms, which consisted of up to 80% extracellular polymer and lead binding to iron oxide deposits.

  15. Soluble metals in residual oil fly ash alter innate and adaptive pulmonary immune responses to bacterial infection in rats

    SciTech Connect

    Roberts, Jenny R. . E-mail: jur6@cdc.gov; Young, Shih-Houng; Castranova, Vincent; Antonini, James M.

    2007-06-15

    The soluble metals of the pollutant, residual oil fly ash (ROFA), have been shown to alter pulmonary bacterial clearance in rats. The goal of this study was to determine the potential effects on both the innate and adaptive lung immune responses after bacterial infection in rats pre-exposed to the soluble metals in ROFA. Sprague-Dawley rats were intratracheally dosed (i.t.) at day 0 with ROFA (R-Total) (1.0 mg/100 g body weight), the soluble fraction of ROFA (R-Soluble), the soluble sample subject to a chelator (R-Chelex), or phosphate-buffered saline (Saline). On day 3, rats were administered an i.t. dose of 5 x 10{sup 4} Listeria monocytogenes. On days 6, 8, and 10, bacterial pulmonary clearance was monitored and bronchoalveolar lavage (BAL) was performed on days 3 (pre-infection), 6, 8, and 10. A concentrated first fraction of lavage fluid was retained for analysis of lactate dehydrogenase and albumin to assess lung injury. BAL cell number, phenotype, and production of reactive oxygen (ROS) and nitrogen species (RNS) were assessed, and a variety of cytokines were measured in the BAL fluid. Rats pre-treated with R-Soluble showed elevated lung injury/cytotoxicity and increased cellular influx into the lungs. R-Soluble-treatment also altered ROS, RNS, and cytokine levels, and caused a degree of macrophage and T cell inhibition. These effects of R-Soluble result in increased pulmonary bacterial burden after infection. The results suggest that soluble metals in ROFA increase lung injury and inflammation, and alter both innate and adaptive pulmonary immune responses.

  16. Structure of a metal-independent bacterial glycosyltransferase that catalyzes the synthesis of histo-blood group A antigen

    PubMed Central

    Thiyagarajan, Nethaji; Pham, Tram T. K.; Stinson, Brittany; Sundriyal, Amit; Tumbale, Percy; Lizotte-Waniewski, Michelle; Brew, Keith; Acharya, K. Ravi

    2012-01-01

    Histo-blood group antigens (HBGAs) are a source of antigenic variation between individuals that modulates resistance and susceptibility to pathogens and is a barrier to the spread of enveloped viruses. HBGAs are also produced by a few prokaryotes where they are synthesized by glycosyltransferases (GTs) related to human HBGA synthases. Here we report the first structure of a bacterial GT of this family, from an intestinal resident, Bacteroides ovatus. Unlike its mammalian homologues and other GTs with similar folds, this protein lacks a metal-binding Asp-X-Asp motif and is fully active in the absence of divalent metal ions, yet is strikingly similar in structure and in its interactions with substrates to structurally characterized mammalian metal-dependent mammalian homologues. This shows how an apparently major divergence in catalytic properties can be accommodated by minor structural adjustments and illustrates the structural underpinnings of horizontal transfer of a functional gene from prokaryotes to vertebrates. PMID:23230506

  17. Functional diversity and dynamics of bacterial communities in a membrane bioreactor for the treatment of metal-working fluid wastewater.

    PubMed

    Grijalbo, Lucía; Garbisu, Carlos; Martín, Iker; Etxebarria, Javier; Gutierrez-Mañero, F Javier; Lucas Garcia, Jose Antonio

    2015-12-01

    An extensive microbiological study has been carried out in a membrane bioreactor fed with activated sludge and metal-working fluids. Functional diversity and dynamics of bacterial communities were studied with different approaches. Functional diversity of culturable bacterial communities was studied with different Biolog™ plates. Structure and dynamics of bacterial communities were studied in culturable and in non-culturable fractions using a 16S rRNA analysis. Among the culturable bacteria, Alphaproteobacteria and Gammaproteobacteria were the predominant classes. However, changes in microbial community structure were detected over time. Culture-independent analysis showed that Betaproteobacteria was the most frequently detected class in the membrane bioreactor (MBR) community with Zoogloea and Acidovorax as dominant genera. Also, among non-culturable bacteria, a process of succession was observed. Longitudinal structural shifts observed were more marked for non-culturable than for culturable bacteria, pointing towards an important role in the MBR performance. Microbial community metabolic abilities assessed with Biolog™ Gram negative, Gram positive and anaerobic plates also showed differences over time for Shannon's diversity index, kinetics of average well colour development, and the intensely used substrates by bacterial community in each plate.

  18. Dehalococcoides mccartyi gen. nov., sp. nov., obligately organohalide-respiring anaerobic bacteria relevant to halogen cycling and bioremediation, belong to a novel bacterial class, Dehalococcoidia classis nov., order Dehalococcoidales ord. nov. and family Dehalococcoidaceae fam. nov., within the phylum Chloroflexi.

    PubMed

    Löffler, Frank E; Yan, Jun; Ritalahti, Kirsti M; Adrian, Lorenz; Edwards, Elizabeth A; Konstantinidis, Konstantinos T; Müller, Jochen A; Fullerton, Heather; Zinder, Stephen H; Spormann, Alfred M

    2013-02-01

    Six obligately anaerobic bacterial isolates (195(T), CBDB1, BAV1, VS, FL2 and GT) with strictly organohalide-respiring metabolisms were obtained from chlorinated solvent-contaminated aquifers, contaminated and uncontaminated river sediments or anoxic digester sludge. Cells were non-motile with a disc-shaped morphology, 0.3-1 µm in diameter and 0.1-0.2 µm thick, and characteristic indentations on opposite flat sides of the cell. Growth occurred in completely synthetic, reduced medium amended with a haloorganic electron acceptor (mostly chlorinated but also some brominated compounds), hydrogen as electron donor, acetate as carbon source, and vitamins. No other growth-supporting redox couples were identified. Aqueous hydrogen consumption threshold concentrations were <1 nM. Growth ceased when vitamin B(12) was omitted from the medium. Addition of sterile cell-free supernatant of Dehalococcoides-containing enrichment cultures enhanced dechlorination and growth of strains 195 and FL2, suggesting the existence of so-far unidentified stimulants. Dechlorination occurred between pH 6.5 and 8.0 and over a temperature range of 15-35 °C, with an optimum growth temperature between 25 and 30 °C. The major phospholipid fatty acids were 14 : 0 (15.7 mol%), br15 : 0 (6.2 mol%), 16 : 0 (22.7 mol%), 10-methyl 16 : 0 (25.8 mol%) and 18 : 0 (16.6 mol%). Unusual furan fatty acids including 9-(5-pentyl-2-furyl)-nonanoate and 8-(5-hexyl-2-furyl)-octanoate were detected in strains FL2, BAV1 and GT, but not in strains 195(T) and CBDB1. The 16S rRNA gene sequences of the six isolates shared more than 98 % identity, and phylogenetic analysis revealed an affiliation with the phylum Chloroflexi and more than 10 % sequence divergence from other described isolates. The genome sizes and G+C contents ranged from 1.34 to 1.47 Mbp and 47 to 48.9 mol% G+C, respectively. Based on 16S rRNA gene sequence comparisons, genome-wide average nucleotide identity and phenotypic

  19. Impact of hydrocarbons, PCBs and heavy metals on bacterial communities in Lerma River, Salamanca, Mexico: Investigation of hydrocarbon degradation potential.

    PubMed

    Brito, Elcia M S; De la Cruz Barrón, Magali; Caretta, César A; Goñi-Urriza, Marisol; Andrade, Leandro H; Cuevas-Rodríguez, Germán; Malm, Olaf; Torres, João P M; Simon, Maryse; Guyoneaud, Remy

    2015-07-15

    Freshwater contamination usually comes from runoff water or direct wastewater discharges to the environment. This paper presents a case study which reveals the impact of these types of contamination on the sediment bacterial population. A small stretch of Lerma River Basin, heavily impacted by industrial activities and urban wastewater release, was studied. Due to industrial inputs, the sediments are characterized by strong hydrocarbon concentrations, ranging from 2 935 to 28 430μg·kg(-1) of total polyaromatic hydrocarbons (PAHs). These sediments are also impacted by heavy metals (e.g., 9.6μg·kg(-1) of Cd and 246μg·kg(-1) of Cu, about 8 times the maximum recommended values for environmental samples) and polychlorinated biphenyls (ranging from 54 to 123μg·kg(-1) of total PCBs). The bacterial diversity on 6 sediment samples, taken from upstream to downstream of the main industrial and urban contamination sources, was assessed through TRFLP. Even though the high PAH concentrations are hazardous to aquatic life, they are not the only factor driving bacterial community composition in this ecosystem. Urban discharges, leading to hypoxia and low pH, also strongly influenced bacterial community structure. The bacterial bioprospection of these samples, using PAH as unique carbon source, yielded 8 hydrocarbonoclastic strains. By sequencing the 16S rDNA gene, these were identified as similar to Mycobacterium goodii, Pseudomonas aeruginosa, Pseudomonas lundensis or Aeromonas veronii. These strains showed high capacity to degrade naphthalene (between 92 and 100% at 200mg·L(-1)), pyrene (up to 72% at 100mg·L(-1)) and/or fluoranthene (52% at 50mg·L(-1)) as their only carbon source on in vitro experiments. These hydrocarbonoclastic bacteria were detected even in the samples upstream of the city of Salamanca, suggesting chronical contamination, already in place longer before. Such microorganisms are clearly potential candidates for hydrocarbon degradation in the

  20. Metal ion effects on hydraulic conductivity of bacterial cellulose-pectin composites used as plant cell wall analogs.

    PubMed

    McKenna, Brigid A; Kopittke, Peter M; Wehr, J Bernhard; Blamey, F Pax C; Menzies, Neal W

    2010-02-01

    Low concentrations of some trace metals markedly reduce root elongation rate and cause ruptures to root rhizodermal and outer cortical cells in the elongation zone. The interactions between the trace metals and plant components responsible for these effects are not well understood but may be linked to changes in water uptake, cell turgor and cell wall extensibility. An experiment was conducted to investigate the effects of Al, La, Cu, Gd, Sc and Ru on the saturated hydraulic conductivity of bacterial cellulose (BC)-pectin composites, used as plant cell wall analogs. Hydraulic conductivity was reduced to approximately 30% of the initial flow rate by 39 microM Al and 0.6 microM Cu, approximately 40% by 4.6 microM La, 3 microM Sc and 4.4 microM Ru and approximately 55% by 3.4 microM Gd. Scanning electron microscopy (SEM) revealed changes in the ultrastructure of the composites. The results suggest that trace metal binding decreases the hydraulic conductivity through changes in pectin porosity. The experiment illustrates the importance of metal interactions with pectin, and the implications of such an interaction in plant metal toxicity and in normal cell wall processes. PMID:20053181

  1. Effect of bacterial inoculation of strains of Pseudomonas aeruginosa, Alcaligenes feacalis and Bacillus subtilis on germination, growth and heavy metal (Cd, Cr, and Ni) uptake of Brassica juncea.

    PubMed

    Ndeddy Aka, Robinson Junior; Babalola, Olubukola Oluranti

    2016-01-01

    Bacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg(-1) of NiCl2, 100 mg kg(-1) of CdCl2, and 150 mg kg(-1) of K2Cr2O7, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction. PMID:26503637

  2. Effect of bacterial inoculation of strains of Pseudomonas aeruginosa, Alcaligenes feacalis and Bacillus subtilis on germination, growth and heavy metal (Cd, Cr, and Ni) uptake of Brassica juncea.

    PubMed

    Ndeddy Aka, Robinson Junior; Babalola, Olubukola Oluranti

    2016-01-01

    Bacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg(-1) of NiCl2, 100 mg kg(-1) of CdCl2, and 150 mg kg(-1) of K2Cr2O7, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction.

  3. Uncovering the transmembrane metal binding site of the novel bacterial major facilitator superfamily-type copper importer CcoA

    DOE PAGES

    Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans -Georg; Daldal, Fevzi

    2016-01-19

    In this study, uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importermore » required for biogenesis of cbb3-type cytochromecoxidase (cbb3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive64Cu and cbb3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter.« less

  4. Uncovering the Transmembrane Metal Binding Site of the Novel Bacterial Major Facilitator Superfamily-Type Copper Importer CcoA

    PubMed Central

    Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans-Georg

    2016-01-01

    ABSTRACT Uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importer required for biogenesis of cbb3-type cytochrome c oxidase (cbb3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive 64Cu and cbb3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter. PMID:26787831

  5. Detection of bioavailable heavy metals in EILATox-Oregon samples using whole-cell luminescent bacterial sensors in suspension or immobilized onto fibre-optic tips.

    PubMed

    Hakkila, Kaisa; Green, Tal; Leskinen, Piia; Ivask, Angela; Marks, Robert; Virta, Marko

    2004-01-01

    At the EILATox-Oregon Workshop, nine luminescent whole-cell bacterial sensors were used for the determination of bioavailable metals in blind samples (17 synthetic and 3 environmental). A non-inducible luminescent control strain was used to determine sample matrix effects and bacterial toxicity. Whole-cell bacterial sensors capable of determining arsenic, inorganic mercury and its organic derivatives, cadmium, lead or copper were used in suspensions and a bacterial sensor for the detection of inorganic mercury was immobilized onto fibre-optic tips using calcium alginate. Bioavailable amounts of metals were estimated using calibration plots, that were constructed to determine the range of metals giving rise to a linear relationship between luminescence and the amount of metals present in the standard solutions. EILATox-Oregon sample 5, which contained 74 mg l(-1) of Hg, gave a significant response with both formats of the mercury sensor. The bioavailable amounts of mercury according to the measurement of bacterial sensor in suspension and immobilized onto a fibre-optic tip were 76 and 93 mg l(-1), respectively. The bacterial sensor for arsenic and copper showed a response with sample 6 (58 mg l(-1) of As) and sample 8 (400 mg l(-1) of metham sodium), respectively. This study showed that the bacterial sensors in suspension or immobilized onto optical fibres are capable of quantifying bioavailable metals from unknown samples. The measurement protocol of bacterial sensors is simple and possible to perform in the field. Moreover, the samples do not need any pretreatment before analysis. Construction and characterization of the strain for the detection of bioavailable copper are described.

  6. Enhanced Bioaccumulation of Heavy Metal Ions by Bacterial Cells Due to Surface Display of Short Metal Binding Peptides

    PubMed Central

    Kotrba, Pavel; Dolečková, Lucie; de Lorenzo, Víctor; Ruml, Tomas

    1999-01-01

    Metal binding peptides of sequences Gly-His-His-Pro-His-Gly (named HP) and Gly-Cys-Gly-Cys-Pro-Cys-Gly-Cys-Gly (named CP) were genetically engineered into LamB protein and expressed in Escherichia coli. The Cd2+-to-HP and Cd2+-to-CP stoichiometries of peptides were 1:1 and 3:1, respectively. Hybrid LamB proteins were found to be properly folded in the outer membrane of E. coli. Isolated cell envelopes of E. coli bearing newly added metal binding peptides showed an up to 1.8-fold increase in Cd2+ binding capacity. The bioaccumulation of Cd2+, Cu2+, and Zn2+ by E. coli was evaluated. Surface display of CP multiplied the ability of E. coli to bind Cd2+ from growth medium fourfold. Display of HP peptide did not contribute to an increase in the accumulation of Cu2+ and Zn2+. However, Cu2+ ceased contribution of HP for Cd2+ accumulation, probably due to the strong binding of Cu2+ to HP. Thus, considering the cooperation of cell structures with inserted peptides, the relative affinities of metal binding peptide and, for example, the cell wall to metal ion should be taken into account in the rational design of peptide sequences possessing specificity for a particular metal. PMID:10049868

  7. Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone

    SciTech Connect

    Bagai, I.; Rensing, C.; Blackburn, N.; McEvoy, M.M.

    2009-05-11

    Transition metals require exquisite handling within cells to ensure that cells are not harmed by an excess of free metal species. In Gram-negative bacteria, copper is required in only small amounts in the periplasm, not in the cytoplasm, so a key aspect of protection under excess metal conditions is to export copper from the periplasm. Additional protection could be conferred by a periplasmic chaperone to limit the free metal species prior to export. Using isothermal titration calorimetry, we have demonstrated that two periplasmic proteins, CusF and CusB, of the Escherichia coli Cu(I)/Ag(I) efflux system undergo a metal-dependent interaction. Through the development of a novel X-ray absorption spectroscopy approach using selenomethionine labeling to distinguish the metal sites of the two proteins, we have demonstrated transfer of Cu(I) occurs between CusF and CusB. The interaction between these proteins is highly specific, as a homologue of CusF with a 51% identical sequence and a similar affinity for metal, did not function in metal transfer. These experiments establish a metallochaperone activity for CusF in the periplasm of Gram-negative bacteria, serving to protect the periplasm from metal-mediated damage.

  8. Effects of properties of metal-contaminated soils on bacterial bioluminescence activity, seed germination, and root and shoot growth.

    PubMed

    Kang, Il-Mo; Kong, In Chul

    2016-01-01

    This study examined the effects of several factors (metal contents and soil properties) on bacterial bioluminescence activity, seed germination and root/shoot growth of Lactuca in metal-contaminated soils. Each bioassay showed different sensitivities to extractants of soil samples. Average sensitivities of the bioassay were in the following order: root growth > bioluminescence ≥ shoot growth ≥ seed germination. Both total and weak acid-extracted metal contents showed no observable correlations with the activity of any bioassays (r(2) < 0.279). However, reasonable correlations were observed between the bioluminescence activity and organics (r(2) = 0.7198) as well as between root growth and CEC (r(2) = 0.6676). Effects of soils were difficult to generalize since they were dependent on many factors, such as soil properties, metal contents, and the organism used in each test. Nonetheless, these results indicated that a battery of bioassays is an effective strategy for assessment of contaminated soils. Furthermore, specific soil factors were shown to more influence on soil toxicity, depending on the type of bioassay.

  9. Molecular and functional assessment of bacterial community convergence in metal-amended soils.

    PubMed

    Anderson, J A H; Hooper, M J; Zak, J C; Cox, S B

    2009-07-01

    Species diversity and the structure of microbial communities in soils are thought to be a function of the cumulative selective pressures within the local environment. Shifts in microbial community structure, as a result of metal stress, may have lasting negative effects on soil ecosystem dynamics if critical microbial community functions are compromised. Three soils in the vicinity of a copper smelter, previously contaminated with background, low and high levels of aerially deposited metals, were amended with metal-salts to determine the potential for metal contamination to shape the structural and functional diversity of microbial communities in soils. We hypothesized that the microbial communities native to the three soils would initially be unique to each site, but would converge on a microbial community with similar structure and function, as a result of metal stress. Initially, the three different sites supported microbial communities with unique structural and functional diversity, and the nonimpacted site supported inherently higher levels of microbial activity and biomass, relative to the metal-contaminated sites. Amendment of the soils with metal-salts resulted in a decrease in microbial activity and biomass, as well as shifts in microbial community structure and function at each site. Soil microbial communities from each site were also observed to be sensitive to changes in soil pH as a result of metal-salt amendment; however, the magnitude of these pH-associated effects varied between soils. Microbial communities from each site did not converge on a structurally or functionally similar community following metal-salt amendment, indicating that other factors may be equally important in shaping microbial communities in soils. Among these factors, soil physiochemical parameters like organic matter and soil pH, which can both influence the bioavailability and toxicity of metals in soils, may be critical. PMID:19030917

  10. Mercury and Other Heavy Metals Influence Bacterial Community Structure in Contaminated Tennessee Streams▿ †

    PubMed Central

    Vishnivetskaya, Tatiana A.; Mosher, Jennifer J.; Palumbo, Anthony V.; Yang, Zamin K.; Podar, Mircea; Brown, Steven D.; Brooks, Scott C.; Gu, Baohua; Southworth, George R.; Drake, Meghan M.; Brandt, Craig C.; Elias, Dwayne A.

    2011-01-01

    High concentrations of uranium, inorganic mercury [Hg(II)], and methylmercury (MeHg) have been detected in streams located in the Department of Energy reservation in Oak Ridge, TN. To determine the potential effects of the surface water contamination on the microbial community composition, surface stream sediments were collected 7 times during the year, from 5 contaminated locations and 1 control stream. Fifty-nine samples were analyzed for bacterial community composition and geochemistry. Community characterization was based on GS 454 FLX pyrosequencing with 235 Mb of 16S rRNA gene sequence targeting the V4 region. Sorting and filtering of the raw reads resulted in 588,699 high-quality sequences with lengths of >200 bp. The bacterial community consisted of 23 phyla, including Proteobacteria (ranging from 22.9 to 58.5% per sample), Cyanobacteria (0.2 to 32.0%), Acidobacteria (1.6 to 30.6%), Verrucomicrobia (3.4 to 31.0%), and unclassified bacteria. Redundancy analysis indicated no significant differences in the bacterial community structure between midchannel and near-bank samples. Significant correlations were found between the bacterial community and seasonal as well as geochemical factors. Furthermore, several community members within the Proteobacteria group that includes sulfate-reducing bacteria and within the Verrucomicrobia group appeared to be associated positively with Hg and MeHg. This study is the first to indicate an influence of MeHg on the in situ microbial community and suggests possible roles of these bacteria in the Hg/MeHg cycle. PMID:21057024

  11. Mercury and other heavy metals influence bacterial community structure in contaminated Tennessee streams

    SciTech Connect

    Vishnivetskaya, Tatiana A; Mosher, Jennifer J; Palumbo, Anthony Vito; Yang, Zamin; Podar, Mircea; Brown, Steven D; Brooks, Scott C; Gu, Baohua; Southworth, George R; Drake, Meghan M; Brandt, Craig C; Elias, Dwayne A

    2011-01-01

    High concentrations of uranium, inorganic mercury [Hg(II)], and methylmercury (MeHg) have been detected in streams located in the Department of Energy reservation in Oak Ridge, TN. To determine the potential effects of the surface water contamination on the microbial community composition, surface stream sediments were collected 7 times during the year, from 5 contaminated locations and 1 control stream. Fifty-nine samples were analyzed for bacterial community composition and geochemistry. Community characterization was based on GS 454 FLX pyrosequencing with 235 Mb of 16S rRNA gene sequence targeting the V4 region. Sorting and filtering of the raw reads resulted in 588,699 high-quality sequences with lengths of >200 bp. The bacterial community consisted of 23 phyla, including Proteobacteria (ranging from 22.9 to 58.5% per sample), Cyanobacteria (0.2 to 32.0%), Acidobacteria (1.6 to 30.6%), Verrucomicrobia (3.4 to 31.0%), and unclassified bacteria. Redundancy analysis indicated no significant differences in the bacterial community structure between midchannel and near-bank samples. Significant correlations were found between the bacterial community and seasonal as well as geochemical factors. Furthermore, several community members within the Proteobacteria group that includes sulfate-reducing bacteria and within the Verrucomicrobia group appeared to be associated positively with Hg and MeHg. This study is the first to indicate an influence of MeHg on the in situ microbial community and suggests possible roles of these bacteria in the Hg/MeHg cycle.

  12. Expressing a bacterial mercuric ion binding protein in plant for phytoremediation of heavy metals.

    PubMed

    Hsieh, Ju-Liang; Chen, Ching-Yi; Chiu, Meng-Hsuen; Chein, Mei-Fang; Chang, Jo-Shu; Endo, Ginro; Huang, Chieh-Chen

    2009-01-30

    A specific mercuric ion binding protein (MerP) originating from transposon TnMERI1 of Bacillus megaterium strain MB1 isolated from Minamata Bay displayed good adsorption capability for a variety of heavy metals. In this study, the Gram-positive MerP protein was expressed in transgenic Arabidopsis to create a model system for phytoremediation of heavy metals. Under control of an actin promoter, the transgenic Arabidpsis showed higher tolerance and accumulation capacity for mercury, cadium and lead when compared with the control plant. Results from confocal microscopy analysis also indicate that MerP was localized at the cell membrane and vesicles of plant cells. The developed transgenic plants possessing excellent metal-accumulative ability could have potential applications in decontamination of heavy metals.

  13. Gut bacterial community structure (Porcellio scaber, Isopoda, Crustacea) as a measure of community level response to long-term and short-term metal pollution.

    PubMed

    Lapanje, Ales; Rupnik, Maja; Drobne, Damjana

    2007-04-01

    Prokaryotes are of high importance in the assessment of environmental pollution effects. Due to fast responsiveness of bacterial communities to environmental physicochemical factors, it is difficult to compare results of bacterial community investigations on the temporal and spatial scale. To reduce the effects of variable physicochemical environmental conditions on bacterial microbiota when investigating the specific impact of contaminants on bacterial communities, we investigated the bacterial community in the gut of terrestrial isopods (Porcellio scaber, Isopoda, Crustacea) from clean and metal-polluted environments. Animals were collected from a chronically mercury-polluted site, a chronically multiple metal-(Cd, Pb, Zn) polluted site, and two reference sites. In addition, animals from an unpolluted site were laboratory exposed to 5 microg Hg/g food in order to compare the effect of acute and chronic Hg exposure. The bacterial gut microbiota was investigated by temporal temperature gradient gel electrophoresis (TTGE) and clone library construction based on polymerase chain reaction amplified 16S rRNA genes. The major bacterial representatives of the emptied gut microbiota in the animals from the chronically polluted environments seemed not affected when analyzed by TTGE. The detailed bacterial community structure investigated by 16S rRNA clone library construction, however, showed that the community from the Hg-polluted site also was affected severely (242.4 operational taxonomic units [OTU] in the polluted and 650.6 OTU in the unpolluted environment). When animals were acutely exposed to mercury, changes of bacterial community structures already were seen on TTGE profiles and no additional analysis was needed. We suggest the use of P. scaber gut bacterial community structure as a measure of effects caused by both long- and short-term exposure to pollution.

  14. Variability In Marine Plankton Community Respiration and The Effects On Carbon Fluxes

    NASA Astrophysics Data System (ADS)

    Robinson, Carol

    In order to divide the amount of photosynthetically fixed carbon between that which is simply recycled back to carbon dioxide and that which is exported to the oceanSs interior, it is important to understand the spatial and temporal variability of plankton respiration and how this relates to community structure and substrate supply. While measurements of community respiration constrain the maximum respiration rate and minimum growth efficiency of each microbial group within the plankton, an improved understanding of the transfer of carbon through the complex planktonic food web would be achieved if the respiration of each of the microbial groups within the plankton was known. Unfortunately, there are few studies directly apportioning community respiration to trophic group, and such accounting exercises are highly de- pendent upon the substrate utilisation efficiencies used. Whereas some studies advo- cate bacterial respiration to be the major component of community respiration, algal respiration is thought to account for the majority of community respiration in some eutrophic ecosystems. The present study analyses measurements of community respiration made in inter- disciplinary research programs in shelf seas, coastal upwelling regions and the open ocean. The specific objectives were to relate the magnitude and variability of commu- nity respiration to bacterial, algal and microzooplankton biomass and activity and to investigate the use of indicator measurements to predict community respiration.

  15. Respiration in Aquatic Insects.

    ERIC Educational Resources Information Center

    MacFarland, John

    1985-01-01

    This article: (1) explains the respiratory patterns of several freshwater insects; (2) describes the differences and mechanisms of spiracular cutaneous, and gill respiration; and (3) discusses behavioral aspects of selected aquatic insects. (ML)

  16. 76 FR 28811 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Respirator...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-18

    ...; Respirator Program Records ACTION: Notice. SUMMARY: The Department of Labor (DOL) is submitting the Mine..., ``Respirator Program Records,'' to the Office of Management and Budget (OMB) for review and approval for... equipment is used, metal and nonmetal mine operators institute a respirator program governing...

  17. A simple synthesis method to produce metal oxide loaded carbon paper using bacterial cellulose gel and characterization of its electrochemical behavior in an aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Miyajima, Naoya; Jinguji, Ken; Matsumura, Taiyu; Matsubara, Toshihiro; Sakane, Hideto; Akatsu, Takashi; Tanaike, Osamu

    2016-04-01

    A simple synthetic chemical process to produce metal oxide loaded carbon papers was developed using bacterial cellulose gel, which consisted of nanometer-sized fibrous cellulose and water. Metal ions were successfully impregnated into the gel via aqueous solution media before drying and carbonization methods resulting in metal oxide contents that were easy to control through variations in the concentration of aqueous solutions. The papers loaded by molybdenum oxides were characterized as pseudocapacitor electrodes preliminary, and the large redox capacitance of the oxides was followed by a conductive fibrous carbon substrate, suggesting that a binder and carbon black additive-free electrode consisting of metal oxides and carbon paper was formed.

  18. Application of a bacterial extracellular polymeric substance in heavy metal adsorption in a co-contaminated aqueous system

    PubMed Central

    de Oliveira Martins, Paula Salles; de Almeida, Narcisa Furtado; Leite, Selma Gomes Ferreira

    2008-01-01

    The application of a bacterial extracellular polymeric substance (EPS) in the bioremediation of heavy metals (Cd, Zn and Cu) by a microbial consortium in a hydrocarbon co-contaminated aqueous system was studied. At the low concentrations used in this work (1.00 ppm of each metal), it was not observed an inhibitory effect on the cellular growing. In the other hand, the application of the EPS lead to a lower concentration of the free heavy metals in solution, once a great part of them is adsorbed in the polymeric matrix (87.12% of Cd; 19.82% of Zn; and 37.64% of Cu), when compared to what is adsorbed or internalized by biomass (5.35% of Cd; 47.35% of Zn; and 24.93% of Cu). It was noted an increase of 24% in the consumption of ethylbenzene, among the gasoline components that were quantified, in the small interval of time evaluated (30 hours). Our results suggest that, if the experiments were conducted in a larger interval of time, it would possibly be noted a higher effect in the degradation of gasoline compounds. Still, considering the low concentrations that were evaluated, it is possible that a real system could be bioremediated by natural attenuation process, demonstrated by the low effect of those levels of contaminants and co-contaminants over the naturally present microbial consortium. PMID:24031307

  19. Impact of hydrocarbons, PCBs and heavy metals on bacterial communities in Lerma River, Salamanca, Mexico: Investigation of hydrocarbon degradation potential.

    PubMed

    Brito, Elcia M S; De la Cruz Barrón, Magali; Caretta, César A; Goñi-Urriza, Marisol; Andrade, Leandro H; Cuevas-Rodríguez, Germán; Malm, Olaf; Torres, João P M; Simon, Maryse; Guyoneaud, Remy

    2015-07-15

    Freshwater contamination usually comes from runoff water or direct wastewater discharges to the environment. This paper presents a case study which reveals the impact of these types of contamination on the sediment bacterial population. A small stretch of Lerma River Basin, heavily impacted by industrial activities and urban wastewater release, was studied. Due to industrial inputs, the sediments are characterized by strong hydrocarbon concentrations, ranging from 2 935 to 28 430μg·kg(-1) of total polyaromatic hydrocarbons (PAHs). These sediments are also impacted by heavy metals (e.g., 9.6μg·kg(-1) of Cd and 246μg·kg(-1) of Cu, about 8 times the maximum recommended values for environmental samples) and polychlorinated biphenyls (ranging from 54 to 123μg·kg(-1) of total PCBs). The bacterial diversity on 6 sediment samples, taken from upstream to downstream of the main industrial and urban contamination sources, was assessed through TRFLP. Even though the high PAH concentrations are hazardous to aquatic life, they are not the only factor driving bacterial community composition in this ecosystem. Urban discharges, leading to hypoxia and low pH, also strongly influenced bacterial community structure. The bacterial bioprospection of these samples, using PAH as unique carbon source, yielded 8 hydrocarbonoclastic strains. By sequencing the 16S rDNA gene, these were identified as similar to Mycobacterium goodii, Pseudomonas aeruginosa, Pseudomonas lundensis or Aeromonas veronii. These strains showed high capacity to degrade naphthalene (between 92 and 100% at 200mg·L(-1)), pyrene (up to 72% at 100mg·L(-1)) and/or fluoranthene (52% at 50mg·L(-1)) as their only carbon source on in vitro experiments. These hydrocarbonoclastic bacteria were detected even in the samples upstream of the city of Salamanca, suggesting chronical contamination, already in place longer before. Such microorganisms are clearly potential candidates for hydrocarbon degradation in the

  20. Bacterial inoculants for enhanced seed germination of Spartina densiflora: Implications for restoration of metal polluted areas.

    PubMed

    Paredes-Páliz, Karina I; Pajuelo, Eloísa; Doukkali, Bouchra; Caviedes, Miguel Ángel; Rodríguez-Llorente, Ignacio D; Mateos-Naranjo, Enrique

    2016-09-15

    The design of effective phytoremediation programs is severely hindered by poor seed germination on metal polluted soils. The possibility that inoculation with plant growth promoting rhizobacteria (PGPR) could help overcoming this problem is hypothesized. Our aim was investigating the role of PGPR in Spartina densiflora seed germination on sediments with different physicochemical characteristics and metal pollution degrees. Gram negative Pantoea agglomerans RSO6 and RSO7, and gram positive Bacillus aryabhattai RSO25, together with the consortium of the three strains, were used for independent inoculation experiments. The presence of metals (As, Cu, Pb and Zn) in sediments reduced seed germination by 80%. Inoculation with Bacillus aryabhattai RSO25 or Pantoea agglomerans RSO6 and RSO7 enhanced up to 2.5 fold the germination rate of S. densiflora in polluted sediments regarding non-inoculated controls. Moreover, the germination process was accelerated and the germination period was extended. The consortium did not achieve further improvements in seed germination.

  1. Detection of γ-radiation and heavy metals using electrochemical bacterial-based sensor

    NASA Astrophysics Data System (ADS)

    Al-Shanawa, M.; Nabok, A.; Hashim, A.; Smith, T.; Forder, S.

    2013-06-01

    The main aim of this work is to develop a simple electrochemical sensor for detection of γ-radiation and heavy metals using bacteria. A series of DC and AC electrical measurements were carried out on samples of two types of bacteria, namely Escherichia coli and Deinococcus radiodurans. As a first step, a correlation between DC and AC electrical conductivity and bacteria concentration in solution was established. The study of the effect of γ-radiation and heavy metal ions (Cd2+) on DC and AC electrical characteristics of bacteria revealed a possibility of pattern recognition of the above inhibition factors.

  2. Accumulation of clinically relevant antibiotic-resistance genes, bacterial load, and metals in freshwater lake sediments in Central Europe.

    PubMed

    Devarajan, Naresh; Laffite, Amandine; Graham, Neil D; Meijer, Maria; Prabakar, Kandasamy; Mubedi, Josué I; Elongo, Vicky; Mpiana, Pius T; Ibelings, Bastiaan Willem; Wildi, Walter; Poté, John

    2015-06-01

    Wastewater treatment plants (WWTP) receive the effluents from various sources (communities, industrial, and hospital effluents) and are recognized as reservoir for antibiotic-resistance genes (ARGs) that are associated with clinical pathogens. The aquatic environment is considered a hot-spot for horizontal gene transfer, and lake sediments offer the opportunity for reconstructing the pollution history and evaluating the impacts. In this context, variation with depth and time of the total bacterial load, the abundance of faecal indicator bacteria (FIB; E. coli and Enterococcus spp. (ENT)), Pseudomonas spp., and ARGs (blaTEM, blaSHV, blaCTX-M, blaNDM, and aadA) were quantified in sediment profiles of different parts of Lake Geneva using quantitative PCR. The abundance of bacterial marker genes was identified in sediments contaminated by WWTP following eutrophication of the lake. Additionally, ARGs, including the extended-spectrum ß-lactam- and aminoglycoside-resistance genes, were identified in the surface sediments. The ARG and FIB abundance strongly correlated (r ≥ 0.403, p < 0.05, n = 34) with organic matter and metal concentrations in the sediments, indicating a common and contemporary source of contamination. The contamination of sediments by untreated or partially treated effluent water can affect the quality of ecosystem. Therefore, the reduction of contaminants from the source is recommended for further improvement of water quality. PMID:25933054

  3. Ex Situ Formation of Metal Selenide Quantum Dots Using Bacterially Derived Selenide Precursors

    SciTech Connect

    Fellowes, Jonathan W.; Pattrick, Richard; Lloyd, Jon; Charnock, John M.; Coker, Victoria S.; Mosselmans, JFW; Weng, Tsu-Chien; Pearce, Carolyn I.

    2013-04-12

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII-) as the precursor. Biogenic SeII- was produced by the reduction of Se-IV by Veillonella atypica and compared directly against borohydride-reduced Se-IV for the production of glutathione-stabilized CdSe and beta-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII- formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII- included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII- is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.

  4. Orthopaedic metal devices coated with a novel antiseptic dye for the prevention of bacterial infections.

    PubMed

    Bahna, Paul; Dvorak, Tanya; Hanna, Hend; Yasko, Alan W; Hachem, Ray; Raad, Issam

    2007-05-01

    Gendine is a novel antiseptic dye with broad-spectrum antimicrobial activity that may be used to coat plastics and metal devices. Our objective was to determine the efficacy of gendine-coated orthopaedic metal devices in preventing methicillin-resistant Staphylococcus aureus (MRSA) colonisation. Stainless steel and titanium Schanz rods were coated with gendine. The zone of inhibition (ZoI) around the rods with and without gamma-irradiation was determined by a modified Kirby-Bauer method. A previously published bioprosthetic biofilm colonisation model, modified Kuhn's method, was used to determine the adherence of MRSA to coated and uncoated rods, with and without irradiation, after insertion into bovine bone and after 3 months shelf life followed by 2 weeks of immersion in serum. The gendine-coated Schanz metal rods showed a net ZoI of 16 mm against MRSA before and after irradiation. Gendine-coated rods showed no biofilm formation (0 colony-forming units (CFU)), which was a significant reduction (P<0.001) compared with uncoated controls (>5000 CFU). Coated rods exposed to high-dose gamma-irradiation and coated rods drilled into bone also showed significant efficacy (P<0.001) in preventing biofilm adherence. After 2 weeks, gendine-coated rods maintained significant durability (P<0.01), resulting in 90% reduction in MRSA biofilm adherence compared with uncoated control rods. Results indicate that gendine-coated metal rods are highly efficacious in the prevention of MRSA biofilm.

  5. RESPIROMETRY AS A TOOL TO DETERMINE METAL TOXICITY IN A SULFATE REDUCING BACTERIAL CULTURE

    EPA Science Inventory

    A novel method under development for treatment of acid mine drainage waste uses biologically- generated hydrogen sulfide (H2S) to precipitate the metals in acid mine drainage (principally zinc, copper, aluminum, nickel, cadmium, arsenic, manganese, iron, and cobalt). The insolub...

  6. 42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... mist respirators designed for respiratory protection against fumes of various metals having an air... HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist....1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for...

  7. 42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... mist respirators designed for respiratory protection against fumes of various metals having an air... HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist....1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for...

  8. The effect of surface properties of polycrystalline, single phase metal coatings on bacterial retention.

    PubMed

    Whitehead, Kathryn A; Olivier, Sebastien; Benson, Paul S; Arneborg, Nils; Verran, Joanna; Kelly, Peter

    2015-03-16

    In the food industry microbial contamination of surfaces can result in product spoilage which may lead to potential health problems of the consumer. Surface properties can have a substantial effect on microbial retention. The surface characteristics of chemically different coatings (Cu, Ti, Mo, Ag, Fe) were defined using white light profilometry (micro-topography and surface features), atomic force microscopy (nano-topography) and physicochemical measurements. The Ag coating had the greatest topography measurements and Fe and Mo the least. Mo was the most hydrophobic coating (lowest γAB,γ(+), γ(-)) whilst Ag was the most hydrophilic (greatest γAB,γ(+), γ(-)). The physicochemical results for the Fe, Ti and Cu coatings were found to lie between those of the Ag and Mo coatings. Microbiological retention assays were carried out using Listeria monocytogenes, Escherichia coli and Staphylococcus aureus in order to determine how surface properties influenced microbial retention. It was found that surface chemistry had an effect on microbial retention, whereas the shape of the surface features and nano-topography did not. L. monocytogenes and S. aureus retention to the surfaces were mostly affected by surface micro-topography, whereas retention of E. coli to the coatings was mostly affected by the coating physicochemistry. There was no trend observed between the bacterial cell surface physicochemistry and the coating physicochemistry. This work highlights that different surface properties may be linked to factors affecting microbial retention hence, the use of surface chemistry, topography or physicochemical factors alone to describe microbial retention to a surface is no longer adequate. Moreover, the effects of surface parameters on microbial retention should be considered individually for each bacterial genus.

  9. Bacterial exposure to metal-oxide nanoparticles: Methods, physical interactions, and biological effects

    NASA Astrophysics Data System (ADS)

    Horst, Allison Marie

    Nanotechnology is a major endeavor of this century, with proposed applications in fields ranging from agriculture to energy to medicine. Nanoscale titanium dioxide (nano-TiO2) is among the most widely produced nanoparticles worldwide, and already exists in consumer products including impermanent personal care products and surface coatings. Inevitably, nano-TiO2 will be transported into the environment via consumer or industrial waste, where its effects on organisms are largely unknown. Out of concern for the possible ill-effects of nanoparticles in the environment, there is now a field of study in nanotoxicology. Bacteria are ideal organisms for nanotoxicology research because they are environmentally important, respond rapidly to intoxication, and provide evidence for effects in higher organisms. My doctoral research focuses on the effects and interactions of nano-TiO2 in aqueous systems with planktonic bacteria. This dissertation describes four projects and the outcomes of the research: (1) A discovery, using a combination of environmental- and cryogenic-scanning electron microscopy and dynamic light scattering (DLS), that initially agglomerated nano-TiO2 is dispersed upon bacterial contact, as nanoparticles preferentially sorbed to cell surfaces. (2) Establishment of a method to disperse nanoparticles in an aqueous culture medium for nanotoxicology studies. A combination of electrostatic repulsion, steric hindrance and sonication yielded a high initial level of nano-TiO2 dispersion (i.e. < 300 nm average agglomerate size) and reduced nanoparticle sedimentation. The approach is described in the context of general considerations for dispersion that are transferable to other nanoparticle and media chemistries. (3) Assessment and optimization of optically-based assays to simultaneously study effects of nanoparticles on bacterial membranes (membrane potential, membrane permeability, and electron transport chain function) and generation of reactive oxygen species. A

  10. Trace metals and their relation to bacterial infections studied by X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Maser, J.; Wagner, D.; Lai, B.; Cai, Z.; Legnini, D.; Moric, I.; Bermudez, L.

    2003-03-01

    Bacterial pathogens survive in different environments in the human host by responding with expression of virulence factors that enable them to adapt to changing conditions. Trace elements regulate the expression of many virulence genes in bacteria and are thus important for their survival in the host. Mycobacteria are intracellular pathogens that can cause diseases such as tuberculosis or secondary infections in immunocompromised patients. We have used a hard x-ray microprobe to study the trace element distribution in the mycobacterial phagosome after infection of macrophages. We have studied phagosomes with virulent (M. avium) and nonvirulent (M. smegmatis) mycobacteria. In this article, we will show that the iron concentration in phagosomes with macrophages infected with nonvirulent M. smegmatis is reduced 24 hours after infection but increased in phagosomes in cells infected with virulent M. avium. In addition, we will show the effect activation of macrophages with tumor necrosis factor (TNF-α) or interferon (IFN-γ) has on the iron concentration in M. avium.

  11. A Multinuclear Metal Complex Based DNase-Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms.

    PubMed

    Chen, Zhaowei; Ji, Haiwei; Liu, Chaoqun; Bing, Wei; Wang, Zhenzhen; Qu, Xiaogang

    2016-08-26

    Extracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase-mimetic artificial enzyme (DMAE) for anti-biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3 O4  /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase-like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti-biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm-encased bacteria and eradiate biofilms. PMID:27484616

  12. Influence of charge and metal coordination of meso-substituted porphyrins on bacterial photoinactivation.

    PubMed

    Zoltan, Tamara; Vargas, Franklin; López, Verónica; Chávez, Valery; Rivas, Carlos; Ramírez, Álvaro H

    2015-01-25

    The photodynamic effect of meso-substituted porphyrins with different charges and metal ions: meso-tetraphenylporphyrin tetrasulfonate 1, its nickel 2 and zinc complexes 3; meso-tetranaphthylporphyrin tetrasulfonate 4, and its zinc complex Zn 5; and tetra piridyl ethylacetate porphirins 6 and their nickel 7 and zinc 8 complexes, were synthesized and studied their antimicrobial activity against Escherichia coli. Fluorescence quantum yields (ΦF) were measured in water using reference TPPS4, obtaining higher values for complexes 3 and 4. The singlet oxygen ΦΔ were measured using histidine as trapping singlet oxygen and Rose Bengal as a reference standard. Complexes 1, 2 and 6 have the highest quantum yields of singlet oxygen formation, showing no relation with the peripheral charges and efficiency as Type II photosensitizers. Meanwhile complexes 3, 8 and 4 were the most efficient in producing radical species, determined with their reaction with NADH. The photoinduced antibacterial activity of complex was investigated at different concentrations of the photosensitizers with an irradiation time of 30 min. The higher antibacterial activities were obtained for the complexes 1-3 that are those with greater production of ROS and minor structural deformations. Complexes 7 and 8 had moderate activity, while 4-6 a low activity. Thus, in this work demonstrates that the production of ROS and structural deformations due to peripheral substituents and metal coordination, influence the activity of the complexes studied. Therefore, is important to perform comprehensive study physics and structurally when predicting or explain such activity.

  13. Assessment of bacterial communities and characterization of lead-resistant bacteria in the rhizosphere soils of metal-tolerant Chenopodium ambrosioides grown on lead-zinc mine tailings.

    PubMed

    Zhang, Wen-hui; Huang, Zhi; He, Lin-yan; Sheng, Xia-fang

    2012-06-01

    Bacterial communities in the rhizosphere soils of metal tolerant and accumulating Chenopodium ambrosioides grown in highly and moderately lead-zinc mine tailings contaminated-soils as well as the adjacent soils with low metal contamination were characterized by using cultivation-independent and cultivation techniques. A total of 69, 73, and 83 bacterial operational taxonomic units (OTUs) having 84.8-100% similarity with the closest match in the database were detected among high, moderate, and low-contamination soil clone libraries, respectively. These OTUs had a Shannon diversity index value in the range of 4.06-4.30. There were 9, 10, and 14 bacterial genera specific to high, moderate, and low metal-contaminated soil clone libraries, respectively. Phylogenetic analysis showed that the Pb-resistant isolates belonged to 8 genera. Pseudomonas and Arthrobacter were predominant among the isolates. Most of the isolates (82-86%) produced indole acetic acid and siderophores. More strains from the highly metal-contaminated soil produced 1-aminocyclopropane-1-carboxylate deaminase than the strains from the moderately and lowly metal-contaminated soils. In experiments involving canola grown in quartz sand containing 200 mg kg(-1) of Pb, inoculation with the isolated Paenibacillus jamilae HTb8 and Pseudomonas sp. GTa5 was found to significantly increase the above-ground tissues dry weight (ranging from 19% to 36%) and Pb uptake (ranging from 30% to 40%) compared to the uninoculated control. These results show that C. ambrosioides harbor different metal-resistant bacterial communities in their rhizosphere soils and the isolates expressing plant growth promoting traits may be exploited for improving the phytoextraction efficiency of Pb-polluted environment.

  14. Assessment of bacterial communities and characterization of lead-resistant bacteria in the rhizosphere soils of metal-tolerant Chenopodium ambrosioides grown on lead-zinc mine tailings.

    PubMed

    Zhang, Wen-hui; Huang, Zhi; He, Lin-yan; Sheng, Xia-fang

    2012-06-01

    Bacterial communities in the rhizosphere soils of metal tolerant and accumulating Chenopodium ambrosioides grown in highly and moderately lead-zinc mine tailings contaminated-soils as well as the adjacent soils with low metal contamination were characterized by using cultivation-independent and cultivation techniques. A total of 69, 73, and 83 bacterial operational taxonomic units (OTUs) having 84.8-100% similarity with the closest match in the database were detected among high, moderate, and low-contamination soil clone libraries, respectively. These OTUs had a Shannon diversity index value in the range of 4.06-4.30. There were 9, 10, and 14 bacterial genera specific to high, moderate, and low metal-contaminated soil clone libraries, respectively. Phylogenetic analysis showed that the Pb-resistant isolates belonged to 8 genera. Pseudomonas and Arthrobacter were predominant among the isolates. Most of the isolates (82-86%) produced indole acetic acid and siderophores. More strains from the highly metal-contaminated soil produced 1-aminocyclopropane-1-carboxylate deaminase than the strains from the moderately and lowly metal-contaminated soils. In experiments involving canola grown in quartz sand containing 200 mg kg(-1) of Pb, inoculation with the isolated Paenibacillus jamilae HTb8 and Pseudomonas sp. GTa5 was found to significantly increase the above-ground tissues dry weight (ranging from 19% to 36%) and Pb uptake (ranging from 30% to 40%) compared to the uninoculated control. These results show that C. ambrosioides harbor different metal-resistant bacterial communities in their rhizosphere soils and the isolates expressing plant growth promoting traits may be exploited for improving the phytoextraction efficiency of Pb-polluted environment. PMID:22397839

  15. Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration.

    PubMed

    Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

    2016-01-01

    Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment. PMID:27256514

  16. Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration

    PubMed Central

    Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

    2016-01-01

    Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment. PMID:27256514

  17. Genes for all metals--a bacterial view of the periodic table. The 1996 Thom Award Lecture.

    PubMed

    Silver, S

    1998-01-01

    Bacterial chromosomes have genes for transport proteins for inorganic nutrient cations and oxyanions, such as NH4+, K+, Mg2+, Co2+, Fe3+, Mn2+, Zn2+ and other trace cations, and PO4(3-), SO4(2-) and less abundant oxyanions. Together these account for perhaps a few hundred genes in many bacteria. Bacterial plasmids encode resistance systems for toxic metal and metalloid ions including Ag+, AsO2-, AsO4(3-), Cd2+, Co2+, CrO4(2-), Cu2+, Hg2+, Ni2+, Pb2+, TeO3(2-), Tl+ and Zn2+. Most resistance systems function by energy-dependent efflux of toxic ions. A few involve enzymatic (mostly redox) transformations. Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. The Cd(2+)-resistance cation pump of Gram-positive bacteria is membrane P-type ATPase, which has been labeled with 32P from [gamma-32P]ATP and drives ATP-dependent Cd2+ (and Zn2+) transport by membrane vesicles. The genes defective in the human hereditary diseases of copper metabolism, Menkes syndrome and Wilson's disease, encode P-type ATPases that are similar to bacterial cadmium ATPases. The arsenic resistance system transports arsenite [As(III)], alternatively with the ArsB polypeptide functioning as a chemiosmotic efflux transporter or with two polypeptides, ArsB and ArsA, functioning as an ATPase. The third protein of the arsenic resistance system is an enzyme that reduces intracellular arsenate [As(V)] to arsenite [As(III)], the substrate of the efflux system. In Gram-negative cells, a three polypeptide complex functions as a chemiosmotic cation/protein exchanger to efflux Cd2+, Zn2+ and Co2+. This pump consists of an inner membrane (CzcA), an outer membrane (CzcC) and a membrane-spanning (CzcB) protein that function together.

  18. Small ecosystem engineers as important regulators of lake's sediment respiration.

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Lewandowski, Joerg; Krause, Stefan; Romeijn, Paul

    2016-04-01

    Although shallow lakes are covering only about 1.5% of the land surface of the Earth, they are responsible for sequestration of carbon amounts similar or even larger than those sequestered in all marine sediments. One of the most important drivers of the carbon sequestration in lakes is sediment respiration. Especially in shallow lakes, bioturbation, i.e. the biogenic reworking of the sediment matrix and the transport of fluids within the sediment, severely impacts on sediment respiration. Widespread freshwater bioturbators such as chironomid larvae (Diptera, Chironomidae) are building tubes in the sediment and actively pump water through their burrows (ventilation). In the present work we study how different organism densities and temperatures (5-30°C) impact on respiration rates. In a microcosm experiment the bioreactive resazurin/resorufin smart tracer system was applied for quantifying the impacts of different densities of Chironomidae (Diptera) larvae (0, 1000, 2000 larvae/m2) on sediment respiration. Tracer transformation rates (and sediment respiration) were correlated with larval densities with highest transformation rates occurring in microcosms with highest larval densities. Respiration differences between defaunated sediment and sediment with 1000 and 2000 larvae per m2 was insignificant at 5 °C, and was progressively increasing with rising temperatures. At 30 °C respiration rates of sediment with 2000 larvae per m2 was 4.8 times higher than those of defaunated sediment. We interpret this as an effect of temperature on larval metabolic and locomotory activity. Furthermore, bacterial communities are benefiting from the combination of the high water temperatures and bioirrigation as bacterial community are able to maintain high metabolic rates due to oxygen supplied by bioirrigation. In the context of global climate change that means that chironomid ecosystem engineering activity will have a profound and increasing impact on lake sediment respiration

  19. Outward- and inward-facing structures of a putative bacterial transition-metal transporter with homology to ferroportin

    PubMed Central

    Taniguchi, Reiya; Kato, Hideaki E.; Font, Josep; Deshpande, Chandrika N.; Wada, Miki; Ito, Koichi; Ishitani, Ryuichiro; Jormakka, Mika; Nureki, Osamu

    2015-01-01

    In vertebrates, the iron exporter ferroportin releases Fe2+ from cells into plasma, thereby maintaining iron homeostasis. The transport activity of ferroportin is suppressed by the peptide hormone hepcidin, which exhibits upregulated expression in chronic inflammation, causing iron-restrictive anaemia. However, due to the lack of structural information about ferroportin, the mechanisms of its iron transport and hepcidin-mediated regulation remain largely elusive. Here we report the crystal structures of a putative bacterial homologue of ferroportin, BbFPN, in both the outward- and inward-facing states. Despite undetectable sequence similarity, BbFPN adopts the major facilitator superfamily fold. A comparison of the two structures reveals that BbFPN undergoes an intra-domain conformational rearrangement during the transport cycle. We identify a substrate metal-binding site, based on structural and mutational analyses. Furthermore, the BbFPN structures suggest that a predicted hepcidin-binding site of ferroportin is located within its central cavity. Thus, BbFPN may be a valuable structural model for iron homeostasis regulation by ferroportin. PMID:26461048

  20. Plankton community respiration during a coccolithophore bloom

    NASA Astrophysics Data System (ADS)

    Robinson, Carol; Widdicombe, Claire E.; Zubkov, Mikhail V.; Tarran, Glen A.; Miller, Axel E. J.; Rees, Andrew P.

    Plankton dark community respiration (DCR), gross production (GP), bacterial production, protozoan herbivory, and phytoplankton, microzooplankton and heterotrophic bacterial abundance were measured during a bloom of the coccolithophore Emiliania huxleyi. The study, which was conducted in the northern North Sea during June 1999, included a spatial survey and a 6-day Lagrangian time series informed by a sulphur hexafluoride (SF 6) tracer-release experiment. E. huxleyi abundance in surface waters ranged from 380 to 3000 cells ml -1, while DCR varied between 2 and 4 mmol O 2 m -3 d -1 and GP between 2 and 5 mmol O 2 m -3 d -1. Euphotic zone integrated DCR and GP were in approximate balance, with a mean (±SD) P:R ratio of 0.9±0.4 ( n=9). However, highest GP occurred at the surface alongside maxima of E. huxleyi, whereas highest rates of DCR occurred at depths of 25-30 m associated with maxima in chlorophyll a and bacterial biomass. DCR was positively correlated with bacterial biomass, microzooplankton biomass, attenuance, particulate organic carbon, and chlorophyll a concentration; and negatively correlated with apparent oxygen utilisation. DCR was not correlated with in situ temperature, dissolved organic carbon concentration or E. huxleyi abundance. A˜100 h incubation of 0.8 μm filtered seawater enabled the estimation of a bacterial respiratory quotient (RQ) and growth efficiency (BGE) from the slopes of the linear regressions of the decrease in dissolved oxygen and increase in dissolved inorganic carbon (DIC) and bacterial carbon with time. During this experiment the bacterial RQ was 0.69 and the growth efficiency was 18%. This measured BGE was used in comparison with literature values to apportion DCR to that associated with bacterial (13-71%), microzooplankton (10-50%), and algal (11-28%) activity. This accounting exercise compared well with measured DCR (to within ±50%), the exact calculation being highly dependent on the BGE used.

  1. Synergy of fresh and accumulated organic matter to bacterial growth.

    PubMed

    Farjalla, Vinicius F; Marinho, Claudio C; Faria, Bias M; Amado, André M; Esteves, Francisco de A; Bozelli, Reinaldo L; Giroldo, Danilo

    2009-05-01

    The main goal of this research was to evaluate whether the mixture of fresh labile dissolved organic matter (DOM) and accumulated refractory DOM influences bacterial production, respiration, and growth efficiency (BGE) in aquatic ecosystems. Bacterial batch cultures were set up using DOM leached from aquatic macrophytes as the fresh DOM pool and DOM accumulated from a tropical humic lagoon. Two sets of experiments were performed and bacterial growth was followed in cultures composed of each carbon substrate (first experiment) and by carbon substrates combined (second experiment), with and without the addition of nitrogen and phosphorus. In both experiments, bacterial production, respiration, and BGE were always higher in cultures with N and P additions, indicating a consistent inorganic nutrient limitation. Bacterial production, respiration, and BGE were higher in cultures set up with leachate DOM than in cultures set up with humic DOM, indicating that the quality of the organic matter pool influenced the bacterial growth. Bacterial production and respiration were higher in the mixture of substrates (second experiment) than expected by bacterial production and respiration in single substrate cultures (first experiment). We suggest that the differences in the concentration of some compounds between DOM sources, the co-metabolism on carbon compound decomposition, and the higher diversity of molecules possibly support a greater bacterial diversity which might explain the higher bacterial growth observed. Finally, our results indicate that the mixture of fresh labile and accumulated refractory DOM that naturally occurs in aquatic ecosystems could accelerate the bacterial growth and bacterial DOM removal. PMID:18985269

  2. The Diesel Exhaust in Miners Study: III. Interrelations between Respirable Elemental Carbon and Gaseous and Particulate Components of Diesel Exhaust derived from Area Sampling in Underground Non-metal Mining Facilities

    PubMed Central

    Vermeulen, Roel; Coble, Joseph B.; Yereb, Daniel; Lubin, Jay H.; Blair, Aaron; Portengen, Lützen; Stewart, Patricia A.; Attfield, Michael; Silverman, Debra T.

    2010-01-01

    Diesel exhaust (DE) has been implicated as a potential lung carcinogen. However, the exact components of DE that might be involved have not been clearly identified. In the past, nitrogen oxides (NOx) and carbon oxides (COx) were measured most frequently to estimate DE, but since the 1990s, the most commonly accepted surrogate for DE has been elemental carbon (EC). We developed quantitative estimates of historical exposure levels of respirable elemental carbon (REC) for an epidemiologic study of mortality, particularly lung cancer, among diesel-exposed miners by back-extrapolating 1998–2001 REC exposure levels using historical measurements of carbon monoxide (CO). The choice of CO was based on the availability of historical measurement data. Here, we evaluated the relationship of REC with CO and other current and historical components of DE from side-by-side area measurements taken in underground operations of seven non-metal mining facilities. The Pearson correlation coefficient of the natural log-transformed (Ln)REC measurements with the Ln(CO) measurements was 0.4. The correlation of REC with the other gaseous, organic carbon (OC), and particulate measurements ranged from 0.3 to 0.8. Factor analyses indicated that the gaseous components, including CO, together with REC, loaded most strongly on a presumed ‘Diesel exhaust’ factor, while the OC and particulate agents loaded predominantly on other factors. In addition, the relationship between Ln(REC) and Ln(CO) was approximately linear over a wide range of REC concentrations. The fact that CO correlated with REC, loaded on the same factor, and increased linearly in log–log space supported the use of CO in estimating historical exposure levels to DE. PMID:20876234

  3. Bacterial ecologies in limonite.

    PubMed

    Vishniac, W

    1965-01-01

    Limonite (Fe2O3 . nH2O) may be a constituent of the Martian surface. We have prepared culture media with ferric hydroxide as an electron acceptor. One medium contained ethanol, another gaseous hydrogen and carbon dioxide. Bacterial growth without light and oxygen suggests that ferric iron serves as a terminal respiratory electron acceptor. The oxidation of ferrous hydroxide may be carried out by photosynthetic bacteria. A ferrous-ferric couple may thus support bacterial respiration and photosynthesis in the absence of oxygen. This cycle may account for the dark markings of Mars.

  4. Analysis and characterization of cultivable heavy metal-resistant bacterial endophytes isolated from Cd-hyperaccumulator Solanum nigrum L. and their potential use for phytoremediation.

    PubMed

    Luo, Sheng-lian; Chen, Liang; Chen, Jue-liang; Xiao, Xiao; Xu, Tao-ying; Wan, Yong; Rao, Chan; Liu, Cheng-bin; Liu, Yu-tang; Lai, Cui; Zeng, Guang-ming

    2011-11-01

    This study investigates the heavy metal-resistant bacterial endophytes of Cd-hyperaccumulator Solanum nigrum L. grown on a mine tailing by using cultivation-dependent technique. Thirty Cd-tolerant bacterial endophytes were isolated from roots, stems, and leaves of S. nigrum L. and classified by amplified ribosomal DNA-restriction analysis into 18 different types. Phylogenetic analysis based on 16S rDNA sequences showed that these isolates belonged to four groups: Actinobacteria (43%), Proteobacteria (23%), Bacteroidetes (27%) and Firmicutes (7%). All the isolates were then characterized for their plant growth promoting traits as well as their resistances to different heavy metals; and the actual plant growth promotion and colonization ability were also assessed. Four isolates were re-introduced into S. nigrum L. under Cd stress and resulted in Cd phytotoxicity decrease, as dry weights of roots increased from 55% to 143% and dry weights of above-ground from 64% to 100% compared to the uninoculated ones. The total Cd accumulation of inoculated plants increased from 66% to 135% (roots) and from 22% to 64% (above-ground) compared to the uninoculated ones. Our research suggests that bacterial endophytes are a most promising resource and may be the excellent candidates of bio-inoculants for enhancing the phytoremediation efficiency. PMID:21868057

  5. Hybrid respiration-signal conditioner

    NASA Technical Reports Server (NTRS)

    Rinard, G. A.; Steffen, D. A.; Sturm, R. E.

    1979-01-01

    Hybrid impedance-pneumograph and respiration-rate signal conditioner element of hand-held vital signs monitor measures changes in impedance of chest during breathing cycle and generates analog respiration signal as output along with synchronous square wave that can be monitored by breath-rate processor.

  6. Bacterial riboswitches cooperatively bind Ni2+ or Co2+ ions and control expression of heavy metal transporters

    PubMed Central

    Furukawa, Kazuhiro; Ramesh, Arati; Zhou, Zhiyuan; Weinberg, Zasha; Vallery, Tenaya; Winkler, Wade C.; Breaker, Ronald R.

    2015-01-01

    SUMMARY Bacteria regularly encounter widely varying metal concentrations in their surrounding environment. As metals become depleted, or, conversely, accrue to toxicity, microbes will activate cellular responses that act to maintain metal homeostasis. A suite of metal-sensing regulatory (‘metalloregulatory’) proteins orchestrate these responses by allosterically coupling the selective binding of target metals to the activity of DNA-binding domains. However, we report here the discovery, validation and structural details of a widespread class of riboswitch RNAs, whose members selectively and tightly bind the low abundance transition metals, Ni2+ and Co2+. These riboswitches bind metal cooperatively, and with affinities in the low micromolar range. The structure of a Co2+-bound RNA reveals a network of molecular contacts that explain how it achieves cooperative binding between adjacent sites. These findings reveal that bacteria have evolved to utilize highly selective metalloregulatory riboswitches, in addition to metalloregulatory proteins, for detecting and responding to toxic levels of heavy metals. PMID:25794617

  7. Biodecolorization of Reactive Black-5 by a metal and salt tolerant bacterial strain Pseudomonas sp. RA20 isolated from Paharang drain effluents in Pakistan.

    PubMed

    Hussain, Sabir; Maqbool, Zahid; Ali, Shafaqat; Yasmeen, Tahira; Imran, Muhammad; Mahmood, Faisal; Abbas, Farhat

    2013-12-01

    Discharge of untreated azo dyes contaminated textile wastewater into soil and water bodies causes severe contamination. The present study was conducted to isolate dye degrading bacterial strains from a textile industry wastewater carrying drain in the neighborhood of Faisalabad, Pakistan. Seventy six bacterial strains were initially isolated and was screened using liquid mineral salts medium spiked with Reactive Black-5 azo dye. The strain RA20 was found to be the most efficient azo dye degrading bacterial isolate and was identified by amplifying and sequencing its 16S rRNA. Analysis indicated that this strain belonged to genus Pseudomonas and was designated as Pseudomonas sp. RA20. It had the highest decolorization activity at pH 8 and 25 °C incubation temperature under static conditions using yeast extract as an additional C source. This strain was also effective in decolorizing structurally related other reactive dyes including Reactive Orange 16, Reactive Yellow 2 and Reactive Red 120 but with varying efficacy. RA20 decolorized Reactive Black-5 significantly in the presence of up to 30 g L⁻¹ NaCl; however, the decolorization rate was significantly (p≤0.05) reduced beyond this salt concentration. Moreover, this bacterial strain also exhibited moderate tolerance to different heavy metals including zinc (Zn), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu). RA20 also decolorized Reactive Black-5 in the presence of a mixture of the selected heavy metals depending upon their concentrations. This study highlights the importance of Pseudomonas sp. RA20 as a prospective biological resource for bioremediation of water and soils contaminated with azo dyes.

  8. A comparison of conventional methods for the quantification of bacterial cells after exposure to metal oxide nanoparticles

    PubMed Central

    2014-01-01

    Background Due to potential interference of nanoparticles on bacterial quantification, there is a challenge to develop a fast, accurate and reproducible method for bacterial quantification. Currently various bacterial quantification methods are used by researchers performing nanoparticles study, but there has been no efficacy evaluation of these methods. Here we study interference of nanoparticles on three most commonly used conventional bacterial quantification methods, including colony counting to determine the colony-forming units (CFU), spectrophotometer method of optical density (OD) measurement, and flow cytometry (FCM). Results Three oxide nanoparticles including ZnO, TiO2, and SiO2 and four bacterial species including Salmonella enterica serovar Newport, Staphylococcus epidermidis, Enterococcus faecalis, and Escherichia coli were included in the test. Results showed that there is no apparent interference of the oxide nanoparticles on quantifications of all four bacterial species by FCM measurement; CFU counting is time consuming, less accurate and not suitable for automation; and the spectrophotometer method using OD measurement was the most unreliable method to quantify and detect the bacteria in the presence of the nanoparticles. Conclusion In summary, FCM measurement proved to be the best method, which is suitable for rapid, accurate and automatic detection of bacteria in the presence of the nanoparticles. PMID:25138641

  9. Respiration signals from photoplethysmography.

    PubMed

    Nilsson, Lena M

    2013-10-01

    respiratory modulation of the pulse oximeter waveform and has been shown to predict fluid responsiveness in mechanically ventilated patients including infants. The pleth variability index value depends on the size of the tidal volume and on positive end-expiratory pressure. In conclusion, the respiration modulation of the PPG signal can be used to monitor respiratory rate. It is probable that improvements in neural network technology will increase sensitivity and specificity for detecting both central and obstructive apnea. The size of the PPG respiration variation can predict fluid responsiveness in mechanically ventilated patients. PMID:23449854

  10. Overview of organohalide-respiring bacteria and a proposal for a classification system for reductive dehalogenases

    PubMed Central

    Hug, Laura A.; Maphosa, Farai; Leys, David; Löffler, Frank E.; Smidt, Hauke; Edwards, Elizabeth A.; Adrian, Lorenz

    2013-01-01

    Organohalide respiration is an anaerobic bacterial respiratory process that uses halogenated hydrocarbons as terminal electron acceptors during electron transport-based energy conservation. This dechlorination process has triggered considerable interest for detoxification of anthropogenic groundwater contaminants. Organohalide-respiring bacteria have been identified from multiple bacterial phyla, and can be categorized as obligate and non-obligate organohalide respirers. The majority of the currently known organohalide-respiring bacteria carry multiple reductive dehalogenase genes. Analysis of a curated set of reductive dehalogenases reveals that sequence similarity and substrate specificity are generally not correlated, making functional prediction from sequence information difficult. In this article, an orthologue-based classification system for the reductive dehalogenases is proposed to aid integration of new sequencing data and to unify terminology. PMID:23479752

  11. Anxiety during respirator use: comparison of two respirator types.

    PubMed

    Wu, Samantha; Harber, Philip; Yun, David; Bansal, Siddharth; Li, Yuan; Santiago, Silverio

    2011-03-01

    Anxiety may interfere with proper respirator use. This study directly compares the effect of two types of respirators--elastomeric half-face mask with dual-cartridges (HFM) and N95 filtering facepiece--on anxiety levels. Twelve volunteers with normal or mildly impaired respiratory conditions performed a series of simulated work tasks using the HFM and N95 on different days. The State-Trait Anxiety Inventory (STAI) measured state anxiety (SA) before and during respirator use. STAI also measured trait anxiety (TA), a stable personal characteristic. The effect of the respirator was measured as the difference between SA pre-use and during use. Work with HFM was associated with an increase in SA (2.92 units, p < .01), whereas work with the N95 had no observed effect. Anxiety should be considered in the selection of the best respirator for a user. Impact on anxiety should be considered for respirator design and certification purposes, particularly if the device is to be widely used in workplace and community settings. PMID:21318920

  12. From breathing to respiration.

    PubMed

    Fitting, Jean-William

    2015-01-01

    The purpose of breathing remained an enigma for a long time. The Hippocratic school described breathing patterns but did not associate breathing with the lungs. Empedocles and Plato postulated that breathing was linked to the passage of air through pores of the skin. This was refuted by Aristotle who believed that the role of breathing was to cool the heart. In Alexandria, breakthroughs were accomplished in the anatomy and physiology of the respiratory system. Later, Galen proposed an accurate description of the respiratory muscles and the mechanics of breathing. However, his heart-lung model was hampered by the traditional view of two non-communicating vascular systems - veins and arteries. After a period of stagnation in the Middle Ages, knowledge progressed with the discovery of pulmonary circulation. The comprehension of the purpose of breathing progressed by steps thanks to Boyle and Mayow among others, and culminated with the contribution of Priestley and the discovery of oxygen by Lavoisier. Only then was breathing recognized as fulfilling the purpose of respiration, or gas exchange. A century later, a controversy emerged concerning the active or passive transfer of oxygen from alveoli to the blood. August and Marie Krogh settled the dispute, showing that passive diffusion was sufficient to meet the oxygen needs.

  13. From breathing to respiration.

    PubMed

    Fitting, Jean-William

    2015-01-01

    The purpose of breathing remained an enigma for a long time. The Hippocratic school described breathing patterns but did not associate breathing with the lungs. Empedocles and Plato postulated that breathing was linked to the passage of air through pores of the skin. This was refuted by Aristotle who believed that the role of breathing was to cool the heart. In Alexandria, breakthroughs were accomplished in the anatomy and physiology of the respiratory system. Later, Galen proposed an accurate description of the respiratory muscles and the mechanics of breathing. However, his heart-lung model was hampered by the traditional view of two non-communicating vascular systems - veins and arteries. After a period of stagnation in the Middle Ages, knowledge progressed with the discovery of pulmonary circulation. The comprehension of the purpose of breathing progressed by steps thanks to Boyle and Mayow among others, and culminated with the contribution of Priestley and the discovery of oxygen by Lavoisier. Only then was breathing recognized as fulfilling the purpose of respiration, or gas exchange. A century later, a controversy emerged concerning the active or passive transfer of oxygen from alveoli to the blood. August and Marie Krogh settled the dispute, showing that passive diffusion was sufficient to meet the oxygen needs. PMID:25532022

  14. Respiration in spiders (Araneae).

    PubMed

    Schmitz, Anke

    2016-05-01

    Spiders (Araneae) are unique regarding their respiratory system: they are the only animal group that breathe simultaneously with lungs and tracheae. Looking at the physiology of respiration the existence of tracheae plays an important role in spiders with a well-developed tracheal system. Other factors as sex, life time, type of prey capture and the high ability to gain energy anaerobically influence the resting and the active metabolic rate intensely. Most spiders have metabolic rates that are much lower than expected from body mass; but especially those with two pairs of lungs. Males normally have higher resting rates than females; spiders that are less evolved and possess a cribellum have lower metabolic rates than higher evolved species. Freely hunting spiders show a higher energy turnover than spiders hunting with a web. Spiders that live longer than 1 year will have lower metabolic rates than those species that die after 1 year in which development and reproduction must be completed. Lower temperatures and starvation, which most spiders can cope with, will decrease the metabolic rate as well. PMID:26820263

  15. Hospital Effluents Are One of Several Sources of Metal, Antibiotic Resistance Genes, and Bacterial Markers Disseminated in Sub-Saharan Urban Rivers.

    PubMed

    Laffite, Amandine; Kilunga, Pitchouna I; Kayembe, John M; Devarajan, Naresh; Mulaji, Crispin K; Giuliani, Gregory; Slaveykova, Vera I; Poté, John

    2016-01-01

    Data concerning the occurrence of emerging biological contaminants such as antibiotic resistance genes (ARGs) and fecal indicator bacteria (FIB) in aquatic environments in Sub-Saharan African countries is limited. On the other hand, antibiotic resistance remains a worldwide problem which may pose serious potential risks to human and animal health. Consequently, there is a growing number of reports concerning the prevalence and dissemination of these contaminants into various environmental compartments. Sediments provide the opportunity to reconstruct the pollution history and evaluate impacts so this study investigates the abundance and distribution of toxic metals, FIB, and ARGs released from hospital effluent wastewaters and their presence in river sediments receiving systems. ARGs (bla TEM, bla CTX-M, bla SHV, and aadA), total bacterial load, and selected bacterial species FIB [Escherichia coli, Enterococcus (ENT)] and species (Psd) were quantified by targeting species specific genes using quantitative PCR (qPCR) in total DNA extracted from the sediments recovered from 4 hospital outlet pipes (HOP) and their river receiving systems in the City of Kinshasa in the Democratic Republic of the Congo. The results highlight the great concentration of toxic metals in HOP, reaching the values (in mg kg(-1)) of 47.9 (Cr), 213.6 (Cu), 1434.4 (Zn), 2.6 (Cd), 281.5 (Pb), and 13.6 (Hg). The results also highlight the highest (P < 0.05) values of 16S rRNA, FIB, and ARGs copy numbers in all sampling sites including upstream (control site), discharge point, and downstream of receiving rivers, indicating that the hospital effluent water is not an exclusive source of the biological contaminants entering the urban rivers. Significant correlation were observed between (i) all analyzed ARGs and total bacterial load (16S rRNA) 0.51 to 0.72 (p < 0.001, n = 65); (ii) ARGs (except bla TEM) and FIB and Psd 0.57 < r < 0.82 (p < 0.001, n = 65); and (iii) ARGs (except bla TEM) and toxic

  16. Hospital Effluents Are One of Several Sources of Metal, Antibiotic Resistance Genes, and Bacterial Markers Disseminated in Sub-Saharan Urban Rivers

    PubMed Central

    Laffite, Amandine; Kilunga, Pitchouna I.; Kayembe, John M.; Devarajan, Naresh; Mulaji, Crispin K.; Giuliani, Gregory; Slaveykova, Vera I.; Poté, John

    2016-01-01

    Data concerning the occurrence of emerging biological contaminants such as antibiotic resistance genes (ARGs) and fecal indicator bacteria (FIB) in aquatic environments in Sub-Saharan African countries is limited. On the other hand, antibiotic resistance remains a worldwide problem which may pose serious potential risks to human and animal health. Consequently, there is a growing number of reports concerning the prevalence and dissemination of these contaminants into various environmental compartments. Sediments provide the opportunity to reconstruct the pollution history and evaluate impacts so this study investigates the abundance and distribution of toxic metals, FIB, and ARGs released from hospital effluent wastewaters and their presence in river sediments receiving systems. ARGs (blaTEM, blaCTX-M, blaSHV, and aadA), total bacterial load, and selected bacterial species FIB [Escherichia coli, Enterococcus (ENT)] and species (Psd) were quantified by targeting species specific genes using quantitative PCR (qPCR) in total DNA extracted from the sediments recovered from 4 hospital outlet pipes (HOP) and their river receiving systems in the City of Kinshasa in the Democratic Republic of the Congo. The results highlight the great concentration of toxic metals in HOP, reaching the values (in mg kg−1) of 47.9 (Cr), 213.6 (Cu), 1434.4 (Zn), 2.6 (Cd), 281.5 (Pb), and 13.6 (Hg). The results also highlight the highest (P < 0.05) values of 16S rRNA, FIB, and ARGs copy numbers in all sampling sites including upstream (control site), discharge point, and downstream of receiving rivers, indicating that the hospital effluent water is not an exclusive source of the biological contaminants entering the urban rivers. Significant correlation were observed between (i) all analyzed ARGs and total bacterial load (16S rRNA) 0.51 to 0.72 (p < 0.001, n = 65); (ii) ARGs (except blaTEM) and FIB and Psd 0.57 < r < 0.82 (p < 0.001, n = 65); and (iii) ARGs (except blaTEM) and toxic metals

  17. Presence of the siderophores pyoverdine and pyochelin in the extracellular medium reduces toxic metal accumulation in Pseudomonas aeruginosa and increases bacterial metal tolerance.

    PubMed

    Braud, Armelle; Geoffroy, Valérie; Hoegy, Françoise; Mislin, Gaëtan L A; Schalk, Isabelle J

    2010-06-01

    In order to get access to iron, Pseudomonas aeruginosa strain PAO1 produces two major siderophores pyoverdine (PVD) and pyochelin (PCH). Both siderophores are able to chelate many other metals in addition to iron. However, despite this property, only iron is transported efficiently into the bacteria by the PVD and PCH uptake pathways. Growth studies with P. aeruginosa strains showed a lower sensitivity to toxic metals for the siderophore-producing strain than for the mutants unable to produce siderophores. Moreover, addition of PVD or PCH to the growth medium of a siderophore-deficient strain considerably reduced the toxicity of toxic metals present at concentrations of 100 µM in iron-limited and iron-supplemented growth conditions. Measurement by Inductively Coupled Plasma-Atomic Emission Spectrometry of the concentration of metals present in bacteria incubated with metals in the presence or absence of PVD or PCH indicated that both siderophores were able to sequester metals from the extracellular medium of the bacteria, decreasing metal diffusion into the bacteria. Pyoverdine was able to sequester Al(3+) , Co(2+) , Cu(2+) , Eu(3+) , Ni(2+) , Pb(2+) , Tb(3+) and Zn(2+) from the extracellular medium, and PCH, Al(3+) , Co(2+) , Cu(2+) , Ni(2+) , Pb(2+) and Zn(2+) . Moreover, the presence of 100 µM Cu(2+) and Ni(2+) increased PVD production by 290% and 380%, respectively, in a medium supplemented with iron. All these data suggest that PVD and PCH may contribute to P. aeruginosa resistance to heavy metals. PMID:23766115

  18. Use of poly(lactic acid) amendments to promote the bacterial fixation of metals in zinc smelter tailings.

    PubMed

    Edenborn, H M

    2004-04-01

    The ability of poly(lactic acid) (PLA) to serve as a long-term source of lactic acid for bacterial sulfate reduction activity in zinc smelter tailings was investigated. Solid PLA polymers mixed in water hydrolyzed abiotically to release lactic acid into solution over an extended period of time. The addition of both PLA and gypsum was required for indigenous bacteria to lower redox potential, raise pH, and stimulate sulfate reduction activity in highly oxidized smelter tailings after one year of treatment. Bioavailable cadmium, copper, lead and zinc were all lowered significantly in PLA/gypsum treated soil, but PLA amendments alone increased the bioavailability of lead, nickel and zinc. Similar PLA amendments may be useful in constructed wetlands and reactive barrier walls for the passive treatment of mine drainage, where enhanced rates of bacterial sulfate reduction are desirable.

  19. The influence of bacterial-humus preparations on the biological activity of soils polluted with oil products and heavy metals

    NASA Astrophysics Data System (ADS)

    Kozlova, E. N.; Stepanov, A. L.; Lysak, L. V.

    2015-04-01

    The influence of bacterial-humus preparations based on Gumigel ( Agrosintez Company) on the biological activity of soddy-podzolic soil polluted with Pb(CH3COO)2 and gasoline was studied in a model experiment. Some indicators of biological activity are shown to depend on soil pollution to different extents. The process of nitrogen fixation and the activity of dehydrogenase and phosphatase were mostly inhibited by Pb(CH3COO)2 and gasoline. Gasoline compared to Pb(CH3COO)2 inhibited the soil biological activity to a greater extent. The bacterial-humus preparations exerted a significant positive effect on the biological activity of the polluted soils manifested in the increase of the total number of bacteria and of the enzyme activity (1.5-5.0 times), in the intensification of nitrogen fixation and denitrification (3-8 times), as well as in the increase in the biomass of the plants grown (1.5-2.0 times). The application of bacterial suspensions of pure cultures or the microbial complex without the preparations of humic acids did not always give a positive effect.

  20. Characterization of a salt resistant bacterial strain Proteus sp. NA6 capable of decolorizing reactive dyes in presence of multi-metal stress.

    PubMed

    Abbas, Naila; Hussain, Sabir; Azeem, Farrukh; Shahzad, Tanvir; Bhatti, Sajjad Haider; Imran, Muhammad; Ahmad, Zulfiqar; Maqbool, Zahid; Abid, Muhammad

    2016-11-01

    Microbial biotechnologies for the decolorization of textile wastewaters have attracted worldwide attention because of their economic suitability and easiness in handling. However, the presence of high amounts of salts and metal ions in textile wastewaters adversely affects the decolorization efficiency of the microbial bioresources. In this regard, the present study was conducted to isolate salt tolerant bacterial strains which might have the potential to decolorize azo dyes even in the presence of multi-metal ion mixtures. Out of the tested 48 bacteria that were isolated from an effluent drain, the strain NA6 was found relatively more efficient in decolorizing the reactive yellow-2 (RY2) dye in the presence of 50 g L(-1) NaCl. Based on the similarity of its 16S rRNA gene sequence and its position in a phylogenetic tree, this strain was designated as Proteus sp. NA6. The strain NA6 showed efficient decolorization (>90 %) of RY2 at pH 7.5 in the presence of 50 g L(-1) NaCl under static incubation at 30 °C. This strain also had the potential to efficiently decolorize other structurally related azo dyes in the presence of 50 g L(-1) NaCl. Moreover, Proteus sp. NA6 was found to resist the presence of different metal ions (Co(+2), Cr(+6), Zn(+2), Pb(+2), Cu(+2), Cd(+2)) and was capable of decolorizing reactive dyes in the presence of different levels of the mixtures of these metal ions along with 50 g L(-1) NaCl. Based on the findings of this study, it can be suggested that Proteus sp. NA6 might serve as a potential bioresource for the biotechnologies involving bioremediation of textile wastewaters containing the metal ions and salts.

  1. Effects of Metal Compounds With Distinct Physicochemical Properties on Iron Homeostasis and Anti-Bacterial Activity in the Lungs: Cr and V

    PubMed Central

    Cohen, Mitchell D.; Sisco, Maureen; Prophete, Colette; Yoshida, Kotaro; Chen, Lung-chi; Zelikoff, Judith T.; Smee, Jason; Holder, Alvin A.; Stonehuerner, Jacqueline; Crans, Debbie C.; Ghio, Andrew J.

    2014-01-01

    In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. We hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both penta-valent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5 hr/d for 5 d) of each at 100 μg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in there were significant increases in production of select cytokines/chemokines). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly-encountered ambient metal pollutants. PMID:19757987

  2. Characterization of a salt resistant bacterial strain Proteus sp. NA6 capable of decolorizing reactive dyes in presence of multi-metal stress.

    PubMed

    Abbas, Naila; Hussain, Sabir; Azeem, Farrukh; Shahzad, Tanvir; Bhatti, Sajjad Haider; Imran, Muhammad; Ahmad, Zulfiqar; Maqbool, Zahid; Abid, Muhammad

    2016-11-01

    Microbial biotechnologies for the decolorization of textile wastewaters have attracted worldwide attention because of their economic suitability and easiness in handling. However, the presence of high amounts of salts and metal ions in textile wastewaters adversely affects the decolorization efficiency of the microbial bioresources. In this regard, the present study was conducted to isolate salt tolerant bacterial strains which might have the potential to decolorize azo dyes even in the presence of multi-metal ion mixtures. Out of the tested 48 bacteria that were isolated from an effluent drain, the strain NA6 was found relatively more efficient in decolorizing the reactive yellow-2 (RY2) dye in the presence of 50 g L(-1) NaCl. Based on the similarity of its 16S rRNA gene sequence and its position in a phylogenetic tree, this strain was designated as Proteus sp. NA6. The strain NA6 showed efficient decolorization (>90 %) of RY2 at pH 7.5 in the presence of 50 g L(-1) NaCl under static incubation at 30 °C. This strain also had the potential to efficiently decolorize other structurally related azo dyes in the presence of 50 g L(-1) NaCl. Moreover, Proteus sp. NA6 was found to resist the presence of different metal ions (Co(+2), Cr(+6), Zn(+2), Pb(+2), Cu(+2), Cd(+2)) and was capable of decolorizing reactive dyes in the presence of different levels of the mixtures of these metal ions along with 50 g L(-1) NaCl. Based on the findings of this study, it can be suggested that Proteus sp. NA6 might serve as a potential bioresource for the biotechnologies involving bioremediation of textile wastewaters containing the metal ions and salts. PMID:27646208

  3. Characterization of antibacterial polyethersulfone membranes using the Respiration Activity Monitoring System (RAMOS).

    PubMed

    Kochan, Jozef; Scheidle, Marco; van Erkel, Joost; Bikel, Matías; Büchs, Jochen; Wong, John Erik; Melin, Thomas; Wessling, Matthias

    2012-10-15

    Membranes with antibacterial properties were developed using surface modification of polyethersulfone ultrafiltration membranes. Three different modification strategies using polyelectrolyte layer-by-layer (LbL) technique are described. The first strategy relying on the intrinsic antibacterial properties of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(ethylenimine) (PEI) exhibits only little antibacterial effects. The other two strategies contain silver in both ionic (Ag(+)) and metallic (Ag(0)) form. Ag(+) embedded into negatively charged poly(sodium 4-styrene sulfonate) (PSS) layers totally inhibits bacterial growth. Ag(0) nanoparticles were introduced to the membrane surface by LbL deposition of chitosan- and poly(methacrylic acid) - sodium salt (PMA)-capped silver nanoparticles and subsequent UV or heat treatment. Antibacterial properties of the modified membranes were quantified by a new method based on the Respiration Activity Monitoring System (RAMOS), whereby the oxygen transfer rates (OTR) of E. coli K12 cultures on the membranes were monitored online. As opposed to colony forming counting method RAMOS yields more quantitative and reliable data on the antibacterial effect of membrane modification. Ag-imprinted polyelectrolyte film composed of chitosan (Ag(0))/PMA(Ag(0))/chitosan(Ag(0)) was found to be the most promising among the tested membranes. Further investigation revealed that the concentration and equal distribution of silver in the membrane surface plays an important role in bacterial growth inhibition. PMID:22884245

  4. Heavy metal impact on bacterial biomass based on DNA analyses and uptake by wild plants in the abandoned copper mine soils.

    PubMed

    Guo, Zhaohui; Megharaj, Mallavarapu; Beer, Michael; Ming, Hui; Mahmudur Rahman, Mohammad; Wu, Weihong; Naidu, Ravi

    2009-09-01

    The metals contamination in surface soils and their accumulation in wild plants from the abandoned Burra and Kapunda copper mines located in South Australia were assessed, and the predominant bacterial diversity in the contaminated surface soils from these two abandoned copper mine sites were evaluated through polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results showed the average concentration of Cu in soils was 3821.59 mg/kg while wild plants accumulated up to 173.44 mg/kg. The concentration of Cu in shoots of spear grass (Stipa uitida) and berry saltbush (Afriplex semibaccata) was higher than that of roots. The concentration of total and extractable As, Cd, Cu and Pb in soils slightly correlated with of these elements in the corresponding wild plants. The toxicity of Cu in heavily contaminated soils impacted on the quantities of specific microbial populations and no significant change in the microbial diversity of highly contaminated soils.

  5. Predicting soil respiration from peatlands.

    PubMed

    Rowson, J G; Worrall, F; Evans, M G; Dixon, S D

    2013-01-01

    This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO(2) productivity related to increased soil microbial CO(2) production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO(2) production is lower with less labile carbon. A final model allows the zone of high CO(2) production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle.

  6. ENDOGENOUS RESPIRATION OF STAPHYLOCOCCUS AUREUS

    PubMed Central

    Ramsey, H. H.

    1962-01-01

    Ramsey, H. H. (Stanford University, Palo Alto, Calif.). Endogenous respiration of Staphylococcus aureus. J. Bacteriol. 83:507–514. 1962.—The endogenous respiration of Staphylococcus aureus is dependent upon the medium used to grow the cell suspension. Within wide ranges, the concentration of glucose in the medium has no effect upon subsequent endogenous respiration of the cells, but the concentration of amino acids in the medium, within certain limits, has a very marked effect. The total carbohydrate content of the cells does not decrease during endogenous respiration. As endogenous respiration proceeds, ammonia appears in the supernatant, and the concentration of glutamic acid in the free amino acid pool decreases. Organisms grown in the presence of labeled glutamic acid liberate labeled CO2 when allowed to respire without added substrate. The principal source of this CO2 is the free glutamate in the metabolic pool; its liberation is not suppressed by exogenous glucose or glutamate. With totally labeled cells, the free pool undergoes a rapid, but not total, depletion and remains at a low level for a long time. Activity of the protein fraction declines with time and shows the largest net decrease of all fractions. Exogenous glucose does not inhibit the release of labeled CO2 by totally labeled cells. Other amino acids in the free pool which can serve as endogenous substrates are aspartic acid and, to much lesser extents, glycine and alanine. The results indicate that both free amino acids and cellular protein may serve as endogenous substrates of S. aureus. PMID:14490204

  7. Predicting soil respiration from peatlands.

    PubMed

    Rowson, J G; Worrall, F; Evans, M G; Dixon, S D

    2013-01-01

    This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO(2) productivity related to increased soil microbial CO(2) production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO(2) production is lower with less labile carbon. A final model allows the zone of high CO(2) production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle. PMID:23178842

  8. Assessment of metal and bacterial contamination in cultivated fish and impact on human health for residents living in the Mekong Delta.

    PubMed

    Chanpiwat, Penradee; Sthiannopkao, Suthipong; Widmer, Kenneth; Himeno, Seiichiro; Miyataka, Hideki; Vu, Ngoc-Ut; Tran, Van-Viet; Pham, Thi-Tuyet-Ngan

    2016-11-01

    Fish is the main source of animal protein and micronutrients for inhabitants in the lower Mekong River basin. Consumption of fish in the basin ranges from 41 to 51 kg capita(-1) year(-1). Thus, concerns of human health impacts caused by daily intake of metals contained in fish, and the incidence of bacterial contamination from Listeria and Escherichia coli have been raised. This study was conducted to 1) determine concentrations of metals, fecal indicator organisms, and Listeria spp. in cultivated common diet fish, and 2) assess human health risks as results of fish consumption on a daily basis. The results showed significant impacts of metal accumulation in fish especially from the intensive aquaculture. Chemical use to promote the rapid allometric growth of fish was expected to be the explanation for this finding. Concentrations of metals contained in different fish species were not statistically different with the exceptions of Na, Mn, and Zn. This might be due to the mobility of elements in aquaculture farms. Listeria and E. coli log CFU/g were 1.36 ± 0.11 (standard error) and 1.57 ± 0.1 s.e., respectively with higher counts observed in samples collected in market sites. Lastly, for human health risk assessment via fish consumption, it was found that hazard quotients of consuming As, Cu, and Zn contained in all fish species could contribute adverse health effects to the local residents (hazard quotients higher than 1). Therefore, risk management measures must be promoted and implemented in all study areas to reduce potential risks to local Vietnamese residents.

  9. Assessment of metal and bacterial contamination in cultivated fish and impact on human health for residents living in the Mekong Delta.

    PubMed

    Chanpiwat, Penradee; Sthiannopkao, Suthipong; Widmer, Kenneth; Himeno, Seiichiro; Miyataka, Hideki; Vu, Ngoc-Ut; Tran, Van-Viet; Pham, Thi-Tuyet-Ngan

    2016-11-01

    Fish is the main source of animal protein and micronutrients for inhabitants in the lower Mekong River basin. Consumption of fish in the basin ranges from 41 to 51 kg capita(-1) year(-1). Thus, concerns of human health impacts caused by daily intake of metals contained in fish, and the incidence of bacterial contamination from Listeria and Escherichia coli have been raised. This study was conducted to 1) determine concentrations of metals, fecal indicator organisms, and Listeria spp. in cultivated common diet fish, and 2) assess human health risks as results of fish consumption on a daily basis. The results showed significant impacts of metal accumulation in fish especially from the intensive aquaculture. Chemical use to promote the rapid allometric growth of fish was expected to be the explanation for this finding. Concentrations of metals contained in different fish species were not statistically different with the exceptions of Na, Mn, and Zn. This might be due to the mobility of elements in aquaculture farms. Listeria and E. coli log CFU/g were 1.36 ± 0.11 (standard error) and 1.57 ± 0.1 s.e., respectively with higher counts observed in samples collected in market sites. Lastly, for human health risk assessment via fish consumption, it was found that hazard quotients of consuming As, Cu, and Zn contained in all fish species could contribute adverse health effects to the local residents (hazard quotients higher than 1). Therefore, risk management measures must be promoted and implemented in all study areas to reduce potential risks to local Vietnamese residents. PMID:27552694

  10. [Dark respiration of terrestrial vegetations: a review].

    PubMed

    Sun, Jin-Wei; Yuan, Feng-Hui; Guan, De-Xin; Wu, Jia-Bing

    2013-06-01

    The source and sink effect of terrestrial plants is one of the hotspots in terrestrial ecosystem research under the background of global change. Dark respiration of terrestrial plants accounts for a large fraction of total net carbon balance, playing an important role in the research of carbon cycle under global climate change. However, there is little study on plant dark respiration. This paper summarized the physiological processes of plant dark respiration, measurement methods of the dark respiration, and the effects of plant biology and environmental factors on the dark respiration. The uncertainty of the dark respiration estimation was analyzed, and the future hotspots of related researches were pointed out.

  11. The Effect of Graphene Oxide/Reduced Graphene Oxide Functionalized with Metal Nanoparticles on Dermal, Bacterial, and Cancerous/Non-Cancerous Epithelial Cells

    NASA Astrophysics Data System (ADS)

    Chen, Arthur; Rafailovich, Miriam; Simon, Marcia; Isseroff, Rebecca; Walker, Stephen; Cho, Jae Hee; Jerome, John

    Graphene and metal nanoparticles are permeating health products but their effects individually and combined on human skin are uncertain. This project studied the effect of graphene oxide (GO) and reduced graphene oxide (rGO) functionalized with Ag or Pt nanoparticles (Ag/PtNPs) on bacterial, dermal (DFBC's), and cancerous (SCC13's) and non-cancerous (DO33's) epidermal cells. GO was functionalized with AgNPs or PtNPs, forming metallized-GO; then reduced with NaBH4. FTIR and SEM confirmed the synthesis and composition. Confocal and SEM showed that Ag-rGO, depending on nanoparticle size, killed either S. Aureus or K. Pneumoniae, while Pt-rGO and rGO had no effect. Rhodamine staining revealed that Ag-rGO was very toxic to SCC13's, but only slightly toxic to DO33's. Pt-rGO and rGO had little effect on SCC13's and DO33's. At high concentrations all GO solutions inhibited cell growth but were not cytotoxic. Optical microscopy displayed that every GO/rGO solution adhered to DFBC's and influenced their direction of growth, making GO/rGO potentially applicable for wound healing. Garcia MRSEC Polymers at Engineered Interfaces.

  12. Soil Respiration - A Geochemist's Perspective

    NASA Astrophysics Data System (ADS)

    Van Cappellen, P.

    2015-12-01

    Soil biogeochemistry is largely driven by the decomposition of plant-derived organic matter by soil microorganisms. In addition to its effects on water quality and soil fertility, the decomposition of organic matter couples soil processes to climate, via the production and emission of greenhouse gases. In this presentation, I will review a number of key factors controlling the rate of decomposition of soil organic matter. In particular, I will discuss the importance of the spatial and temporal variations in redox conditions as drivers of soil respiration. The discussion will highlight the limitations of current soil respiration models based on partitioning soil organic matter in a finite number of pools of different degradability. In order to predict the sensitivity of soil respiration to anthropogenic pressures - including climate warming - it is crucial to relate the apparent degradability of soil organic matter to the geochemical and hydrological dynamics of the soil environment. Overall, there remains much scope for geochemists to help develop more robust, process-based, representations of soil respiration in global carbon models and climate predictions.

  13. Persistence of respirator use learning.

    PubMed

    Harber, Philip; Su, Jing; Hu, Cheng Cheng

    2014-01-01

    Although retraining and repeat fit-testing are needed for respirator users, the optimal frequency is uncertain. The persistence of proper respirator donning/doffing techniques and changes in quantitative fit factor over 6 months after initial training were measured in this study. Initial training was designed for rapid rollout situations in which direct contact with well-trained occupational health professionals may be infeasible. Subjects (n = 175) were assigned randomly to use either a filtering facepiece N95 (FFR) or dual cartridge half facemask (HFM) respirator. Each was assigned randomly to one of three training methods-printed brochure, video, or computer-based training. Soon after initial training, quantitative fit and measures of proper technique were determined. These measurements were repeated 6 months later. In the six-month followup, subjects were randomized to receive either a brief reminder card or a placebo card. Total performance score, major errors, and quantitative fit all became significantly worse at 6 months. An individual's result soon after training was the most important predictor of performance 6 months later. There was a marginal not statistically significant tendency for those initially trained by video to have better protection 6 months later. The study suggests that persons who use respirators intermittently should be thoroughly retrained and reevaluated periodically. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: Additional statistical analyses. PMID:24847912

  14. Ecology and Biotechnology of Selenium-Respiring Bacteria

    PubMed Central

    2015-01-01

    SUMMARY In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications. PMID:25631289

  15. Ecology and biotechnology of selenium-respiring bacteria.

    PubMed

    Nancharaiah, Y V; Lens, P N L

    2015-03-01

    In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications. PMID:25631289

  16. 30 CFR 57.5044 - Respirators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10, 1995 or under the equivalent section of 42 CFR part 84 and such respirator use shall be in compliance...

  17. 30 CFR 57.5044 - Respirators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10, 1995 or under the equivalent section of 42 CFR part 84 and such respirator use shall be in compliance...

  18. 30 CFR 57.5044 - Respirators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10, 1995 or under the equivalent section of 42 CFR part 84 and such respirator use shall be in compliance...

  19. 30 CFR 57.5044 - Respirators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10, 1995 or under the equivalent section of 42 CFR part 84 and such respirator use shall be in compliance...

  20. 30 CFR 57.5044 - Respirators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10, 1995 or under the equivalent section of 42 CFR part 84 and such respirator use shall be in compliance...

  1. The Source of Carbon for Root Respiration

    NASA Astrophysics Data System (ADS)

    Cisneros-Dozal, L.; Trumbore, S.; Zheng, S.

    2004-12-01

    In the Enriched Background Isotope Study (EBIS) that took advantage of a whole-ecosystem radiocarbon label that occurred in the temperate forest near Oak Ridge, Tennessee, we measured the radiocarbon signature of total soil respiration, heterotrophic respiration and root respiration, at different times during the last 3 growing seasons (2002-2004). By applying a mass balance approach, the relative and absolute contributions of heterotrophic and root respiration to total soil respiration were estimated. In contrast to heterotrophic respiration, root respiration seemed to be less affected by changes in soil moisture and temperature but rather showed a link to photosynthetic activity with a very similar pattern during the growing season as that of leaf area index. The radiocarbon signature of root respiration was very dynamic with low values in spring compared to the summer. The sources of variation can include changes in the local atmospheric signature and/or changes in the source of C being respired. Two different sites with different values and patterns of local atmospheric radiocarbon signature showed the same pattern in radiocarbon signatures of root respiration indicating that the source of variation was phenological. Low values during the spring could indicate the use of stored carbohydrates switching to more recent photosynthetic products as the summer progresses. As a first attempt to elucidate the source of C respired by roots, we will compare the radiocarbon content of starch, cellulose and soluble sugars in roots to that of bulk root material and root respired CO2. These radiocarbon signatures can help us identify the pool of C that is most likely being respired by roots during the growing season. A better understanding of the source of C for root respiration has implications for understanding the role of root respiration in C cycling in temperate forests, specifically the timescale over which carbon is fixed through photosynthesis and returned to the

  2. Surface coagulation, microbial respiration and primary production in the Sargasso Sea

    NASA Astrophysics Data System (ADS)

    Kepkay, P. E.; Harrison, W. G.; Irwin, B.

    1990-01-01

    Coagulation of colloidal organic material onto bubble surfaces caused a rapid and short-lived increase of microbial respiration in Sargasso surface water. This process of surface coagulation in a nutrient-poor, stratified water column enhanced respiration in the mixed layer by a factor of 8.6-11.2. Net bacterial biomass also was increased by a factor of 2.0-6.7. This was in contrast to results from previous work in coastal waters where, in response to bubbling, the net increase of bacterial biomass was minimal. Enhancement of respiration was correlated positively with primary production, negatively with chlorophyll and decreased rapidly towards the base of the mixed layer. This suggests that surface coagulation had little impact on "older" DOC in deeper water. Instead, bubbling appeared to be confined in its biological effect to "newer" colloids associated with higher productivity near the ocean surface.

  3. Degradation of the metal-cyano complex tetracyanonickelate(II) by cyanide-utilizing bacterial isolates. [Klebsiella; Pseudomonas putida

    SciTech Connect

    Silva-Avalos, J.; Richmond, M.G.; Nagappan, O.; Kunz, D.A. )

    1990-12-01

    Ten bacterial isolates capable of growth on tetracyanonickelate(II) {l brace}K{sub 2}(Ni(CN){sub 4}){r brace} (TCN) as the sole nitrogen source were isolated from soil, freshwater, and sewage sludge enrichments. Seven of the 10 were identified as pseudomonads, while the remaining 3 were classified as Klebsiella species. A detailed investigation of one isolate, Pseudomonas putide BCN3, revealed a rapid growth rate on TCN (generation time, 2 h), with substrate removal and growth occurring in parallel. In addition to TCN, all isolates were able to utilize KCN, although the latter was significantly more toxic; MICs ranged from 0.2 to 0.8 mM for KCN and {ge}50 mM for TCN. While growth occurred over a wide range of TCN concentrations (0.25 to 16 mM), degradation was most substantial under growth-limiting conditions and did not occur when ammonia was present. In addition, cells grown on TCN were found to accumulate nickel cyanide (Ni(CN){sub 2}) as a major biodegradation product. The results show that bacteria capable of growth on TCN can readily be isolated and that degradation (i) appears to parallel the capacity for growth on KCN, (ii) does not occur in the presence of ammonia, and (iii) proceeds via the formation of Ni(CN){sub 2} as a biological metabolite.

  4. MICROBIAL COLONIZATION, RESPIRATION, AND BREAKDOWN OF MAPLE LEAVES ALONG A STREAM-MARSH CONTINUUM

    EPA Science Inventory

    Breakdown rates, macroinvertebrate and bacterial colonization, and microbial respiration were measured on decaying maple (Acer saccharum) leaves at three sites along a stream-marsh continuum. Breakdown rates (-k+-SE) were 0.0284+-0.0045 d-1 for leaves in a high-gradient, non-tida...

  5. MICROBIAL COLONIZATION, RESPIRATION AND BREAKDOWN OF MAPLE LEAVES ALONG A STREAM-MARSH CONTINUUM

    EPA Science Inventory

    Breakdown rates, macroinvertebrate and bacterial colonization, and microbial respiration were measured on decaying maple leaves at three sites along a stream-marsh continuum. Breakdown rates were 0.0284+/-0.0045 d-1 for leaves in a high-gradient, non-tidal stream; 0.0112 +/- 0.0...

  6. Simulated workplace performance of N95 respirators.

    PubMed

    Coffey, C C; Campbell, D L; Zhuang, Z

    1999-01-01

    During July 1995 the National Institute for Occupational Safety and Health (NIOSH) began to certify nine new classes of particulate respirators. To determine the level of performance of these respirators, NIOSH researchers conducted a study to (1) measure the simulated workplace performance of 21 N95 respirator models, (2) determine whether fit-testing affected the performance, and (3) investigate the effect of varying fit-test pass/fail criteria on respirator performance. The performance of each respirator model was measured by conducting 100 total penetration tests. The performance of each respirator model was then estimated by determining the 95th percentile of the total penetration through the respirator (i.e., 95% of wearers of that respirator can expect to have a total penetration value below the 95th percentile penetration value). The 95th percentile of total penetrations for each respirator without fit-testing ranged from 6 to 88%. The 95th percentile of total penetrations for all the respirators combined was 33%, which exceeds the amount of total penetration (10%) normally expected of a half-mask respirator. When a surrogate fit test (1% criterion) was applied to the data, the 95th percentile of total penetrations for each respirator decreased to 1 to 16%. The 95th percentile of total penetrations for all the respirators combined was only 4%. Therefore, fit-testing of N95 respirators is necessary to ensure that the user receives the expected level of protection. The study also found that respirator performance was dependent on the value of the pass/fail criterion used in the surrogate fit-test. PMID:10529991

  7. A Versatile Strategy for Production of Membrane Proteins with Diverse Topologies: Application to Investigation of Bacterial Homologues of Human Divalent Metal Ion and Nucleoside Transporters.

    PubMed

    Ma, Cheng; Hao, Zhenyu; Huysmans, Gerard; Lesiuk, Amelia; Bullough, Per; Wang, Yingying; Bartlam, Mark; Phillips, Simon E; Young, James D; Goldman, Adrian; Baldwin, Stephen A; Postis, Vincent L G

    2015-01-01

    Membrane proteins play key roles in many biological processes, from acquisition of nutrients to neurotransmission, and are targets for more than 50% of current therapeutic drugs. However, their investigation is hampered by difficulties in their production and purification on a scale suitable for structural studies. In particular, the nature and location of affinity tags introduced for the purification of recombinant membrane proteins can greatly influence their expression levels by affecting their membrane insertion. The extent of such effects typically depends on the transmembrane topologies of the proteins, which for proteins of unknown structure are usually uncertain. For example, attachment of oligohistidine tags to the periplasmic termini of membrane proteins often interferes with folding and drastically impairs expression in Escherichia coli. To circumvent this problem we have employed a novel strategy to enable the rapid production of constructs bearing a range of different affinity tags compatible with either cytoplasmic or periplasmic attachment. Tags include conventional oligohistidine tags compatible with cytoplasmic attachment and, for attachment to proteins with a periplasmic terminus, either tandem Strep-tag II sequences or oligohistidine tags fused to maltose binding protein and a signal sequence. Inclusion of cleavage sites for TEV or HRV-3C protease enables tag removal prior to crystallisation trials or a second step of purification. Together with the use of bioinformatic approaches to identify members of membrane protein families with topologies favourable to cytoplasmic tagging, this has enabled us to express and purify multiple bacterial membrane transporters. To illustrate this strategy, we describe here its use to purify bacterial homologues of human membrane proteins from the Nramp and ZIP families of divalent metal cation transporters and from the concentrative nucleoside transporter family. The proteins are expressed in E. coli in a

  8. A Versatile Strategy for Production of Membrane Proteins with Diverse Topologies: Application to Investigation of Bacterial Homologues of Human Divalent Metal Ion and Nucleoside Transporters

    PubMed Central

    Huysmans, Gerard; Lesiuk, Amelia; Bullough, Per; Wang, Yingying; Bartlam, Mark; Phillips, Simon E.; Young, James D.; Goldman, Adrian; Postis, Vincent L. G.

    2015-01-01

    Membrane proteins play key roles in many biological processes, from acquisition of nutrients to neurotransmission, and are targets for more than 50% of current therapeutic drugs. However, their investigation is hampered by difficulties in their production and purification on a scale suitable for structural studies. In particular, the nature and location of affinity tags introduced for the purification of recombinant membrane proteins can greatly influence their expression levels by affecting their membrane insertion. The extent of such effects typically depends on the transmembrane topologies of the proteins, which for proteins of unknown structure are usually uncertain. For example, attachment of oligohistidine tags to the periplasmic termini of membrane proteins often interferes with folding and drastically impairs expression in Escherichia coli. To circumvent this problem we have employed a novel strategy to enable the rapid production of constructs bearing a range of different affinity tags compatible with either cytoplasmic or periplasmic attachment. Tags include conventional oligohistidine tags compatible with cytoplasmic attachment and, for attachment to proteins with a periplasmic terminus, either tandem Strep-tag II sequences or oligohistidine tags fused to maltose binding protein and a signal sequence. Inclusion of cleavage sites for TEV or HRV-3C protease enables tag removal prior to crystallisation trials or a second step of purification. Together with the use of bioinformatic approaches to identify members of membrane protein families with topologies favourable to cytoplasmic tagging, this has enabled us to express and purify multiple bacterial membrane transporters. To illustrate this strategy, we describe here its use to purify bacterial homologues of human membrane proteins from the Nramp and ZIP families of divalent metal cation transporters and from the concentrative nucleoside transporter family. The proteins are expressed in E. coli in a

  9. Impact of Mining Waste on Airborne Respirable Particulates in Northeastern Oklahoma, United States

    EPA Science Inventory

    Atmospheric dispersion of particles from mine waste is potentially an important route of human exposure to metals in communities close to active and abandoned mining areas. In this study, we assessed sources of mass and metal concentrations in two size fractions of respirable pa...

  10. Mesoporous silica nanoparticles inhibit cellular respiration.

    PubMed

    Tao, Zhimin; Morrow, Matthew P; Asefa, Tewodros; Sharma, Krishna K; Duncan, Cole; Anan, Abhishek; Penefsky, Harvey S; Goodisman, Jerry; Souid, Abdul-Kader

    2008-05-01

    We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O 2 consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500 microg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 microg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 microg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both nanoparticles inhibited respiration of isolated mitochondria and submitochondrial particles.

  11. Purification, substrate range, and metal center of AtzC: the N-isopropylammelide aminohydrolase involved in bacterial atrazine metabolism.

    PubMed

    Shapir, Nir; Osborne, Jeffrey P; Johnson, Gilbert; Sadowsky, Michael J; Wackett, Lawrence P

    2002-10-01

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The K(m) and k(cat) values for AtzC with N-isopropylammelide were 406 micro M and 13.3 s(-1), respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher k(cat) values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Delta epsilon = 84 M(-1) cm(-1)) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g((x)) = 5.18, g((y)) = 3.93, and g((z)) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g((x)) = 5.11, g((y)) = 4.02, and g((z)) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides. PMID:12218024

  12. Purification, Substrate Range, and Metal Center of AtzC: the N-Isopropylammelide Aminohydrolase Involved in Bacterial Atrazine Metabolism

    PubMed Central

    Shapir, Nir; Osborne, Jeffrey P.; Johnson, Gilbert; Sadowsky, Michael J.; Wackett, Lawrence P.

    2002-01-01

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 μM and 13.3 s−1, respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Δɛ = 84 M−1 cm−1) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) = 5.18, g(y) = 3.93, and g(z) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) = 5.11, g(y) = 4.02, and g(z) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides. PMID:12218024

  13. With respect to coefficient of linear thermal expansion, bacterial vegetative cells and spores resemble plastics and metals, respectively

    PubMed Central

    2013-01-01

    Background If a fixed stress is applied to the three-dimensional z-axis of a solid material, followed by heating, the amount of thermal expansion increases according to a fixed coefficient of thermal expansion. When expansion is plotted against temperature, the transition temperature at which the physical properties of the material change is at the apex of the curve. The composition of a microbial cell depends on the species and condition of the cell; consequently, the rate of thermal expansion and the transition temperature also depend on the species and condition of the cell. We have developed a method for measuring the coefficient of thermal expansion and the transition temperature of cells using a nano thermal analysis system in order to study the physical nature of the cells. Results The tendency was seen that among vegetative cells, the Gram-negative Escherichia coli and Pseudomonas aeruginosa have higher coefficients of linear expansion and lower transition temperatures than the Gram-positive Staphylococcus aureus and Bacillus subtilis. On the other hand, spores, which have low water content, overall showed lower coefficients of linear expansion and higher transition temperatures than vegetative cells. Comparing these trends to non-microbial materials, vegetative cells showed phenomenon similar to plastics and spores showed behaviour similar to metals with regards to the coefficient of liner thermal expansion. Conclusions We show that vegetative cells occur phenomenon of similar to plastics and spores to metals with regard to the coefficient of liner thermal expansion. Cells may be characterized by the coefficient of linear expansion as a physical index; the coefficient of linear expansion may also characterize cells structurally since it relates to volumetric changes, surface area changes, the degree of expansion of water contained within the cell, and the intensity of the internal stress on the cellular membrane. The coefficient of linear expansion holds

  14. Adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II), and As(V) on bacterially produced metal sulfides.

    PubMed

    Jong, Tony; Parry, David L

    2004-07-01

    The adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II) and As(V) onto bacterially produced metal sulfide (BPMS) material was investigated using a batch equilibrium method. It was found that the sulfide material had adsorptive properties comparable with those of other adsorbents with respect to the specific uptake of a range of metals and, the levels to which dissolved metal concentrations in solution can be reduced. The percentage of adsorption increased with increasing pH and adsorbent dose, but decreased with increasing initial dissolved metal concentration. The pH of the solution was the most important parameter controlling adsorption of Cd(II), Cu(II), Fe(II), Ni(II), Pb(II), Zn(II), and As(V) by BPMS. The adsorption data were successfully modeled using the Langmuir adsorption isotherm. Desorption experiments showed that the reversibility of adsorption was low, suggesting high-affinity adsorption governed by chemisorption. The mechanism of adsorption for the divalent metals was thought to be the formation of strong, inner-sphere complexes involving surface hydroxyl groups. However, the mechanism for the adsorption of As(V) by BPMS appears to be distinct from that of surface hydroxyl exchange. These results have important implications to the management of metal sulfide sludge produced by bacterial sulfate reduction.

  15. Synthesis, aggregation and spectroscopic studies of novel water soluble metal free, zinc, copper and magnesium phthalocyanines and investigation of their anti-bacterial properties.

    PubMed

    Bayrak, Rıza; Akçay, Hakkı Türker; Beriş, Fatih Şaban; Sahin, Ertan; Bayrak, Hacer; Demirbaş, Ümit

    2014-12-10

    In this study, novel phthalonitrile derivative (3) was synthesized by the reaction between 4-nitrophthalonitrile (2) and a triazole derivative (1) containing pyridine moiety. Crystal structure of compound (3) was characterized by X-ray diffraction. New metal free and metallo-phthalocyanine complexes (Zn, Cu, and Mg) were synthesized using the phthalonitrile derivative (3). Cationic derivatives of these phthalocyanines (5, 7, 9, and 11) were prepared from the non-ionic phthalocyanines (4, 6, 8, and 10). All proposed structures were supported by instrumental methods. The aggregation behaviors of the phthalocyanines (4-11) were investigated in different solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform and water. Water soluble cationic Pcs (5, 7, 9, and 11) aggregated in water and sodium dodecyl sulfate was used to prevent the aggregation. The second derivatives of the UV-Vis spectra of aggregated Pcs were used for analyzing the Q and B bands of aggregated species. Thermal behaviors of the phthalocyanines were also studied. In addition, anti-bacterial properties of the phthalocyanines were investigated. We used four gram negative and two gram positive bacteria to determine antibacterial activity of these compounds. Compound 7 has the best activity against the all bacteria with 125μg/mL of MIC value. Compounds 4, 6, and 10 have the similar effect on the bacteria with 250μg/mL of MIC value.

  16. Synthesis, aggregation and spectroscopic studies of novel water soluble metal free, zinc, copper and magnesium phthalocyanines and investigation of their anti-bacterial properties.

    PubMed

    Bayrak, Rıza; Akçay, Hakkı Türker; Beriş, Fatih Şaban; Sahin, Ertan; Bayrak, Hacer; Demirbaş, Ümit

    2014-12-10

    In this study, novel phthalonitrile derivative (3) was synthesized by the reaction between 4-nitrophthalonitrile (2) and a triazole derivative (1) containing pyridine moiety. Crystal structure of compound (3) was characterized by X-ray diffraction. New metal free and metallo-phthalocyanine complexes (Zn, Cu, and Mg) were synthesized using the phthalonitrile derivative (3). Cationic derivatives of these phthalocyanines (5, 7, 9, and 11) were prepared from the non-ionic phthalocyanines (4, 6, 8, and 10). All proposed structures were supported by instrumental methods. The aggregation behaviors of the phthalocyanines (4-11) were investigated in different solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform and water. Water soluble cationic Pcs (5, 7, 9, and 11) aggregated in water and sodium dodecyl sulfate was used to prevent the aggregation. The second derivatives of the UV-Vis spectra of aggregated Pcs were used for analyzing the Q and B bands of aggregated species. Thermal behaviors of the phthalocyanines were also studied. In addition, anti-bacterial properties of the phthalocyanines were investigated. We used four gram negative and two gram positive bacteria to determine antibacterial activity of these compounds. Compound 7 has the best activity against the all bacteria with 125μg/mL of MIC value. Compounds 4, 6, and 10 have the similar effect on the bacteria with 250μg/mL of MIC value. PMID:24952089

  17. Qualitative Alterations of Bacterial Metabolome after Exposure to Metal Nanoparticles with Bactericidal Properties: A Comprehensive Workflow Based on (1)H NMR, UHPLC-HRMS, and Metabolic Databases.

    PubMed

    Chatzimitakos, Theodoros G; Stalikas, Constantine D

    2016-09-01

    Metal nanoparticles (NPs) have proven to be more toxic than bulk analogues of the same chemical composition due to their unique physical properties. The NPs, lately, have drawn the attention of researchers because of their antibacterial and biocidal properties. In an effort to shed light on the mechanism through which the bacteria elimination is achieved and the metabolic changes they undergo, an untargeted metabolomic fingerprint study was carried out on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria species. The (1)H NMR spectroscopy, in conjunction with high resolution mass-spectrometry (HRMS) and an unsophisticated data processing workflow were implemented. The combined NMR/HRMS data, supported by an open-access metabolomic database, proved to be efficacious in the process of assigning a putative annotation to a wide range of metabolite signals and is a useful tool to appraise the metabolome alterations, as a consequence of bacterial response to NPs. Interestingly, not all the NPs diminished the intracellular metabolites; bacteria treated with iron NPs produced metabolites not present in the nonexposed bacteria sample, implying the activation of previously inactive metabolic pathways. In contrast, copper and iron-copper NPs reduced the annotated metabolites, alluding to the conclusion that the metabolic pathways (mainly alanine, aspartate, and glutamate metabolism, beta-alanine metabolism, glutathione metabolism, and arginine and proline metabolism) were hindered by the interactions of NPs with the intracellular metabolites. PMID:27432757

  18. A comparison of carbon/energy and complex nitrogen sources for bacterial sulphate-reduction: potential applications to bioprecipitation of toxic metals as sulphides.

    PubMed

    White, C; Gadd, G M

    1996-08-01

    Detailed nutrient requirements were determined to maximise efficacy of a sulphate-reducing bacterial mixed culture for biotechnological removal of sulphate, acidity and toxic metals from waste waters. In batch culture, lactate produced the greatest biomass, while ethanol was more effective in stimulating sulphide production and acetate was less effective. The presence of additional bicarbonate and H2 only marginally stimulated sulphide production. The sulphide output per unit of biomass was greatest using ethanol as substrate. In continuous culture, ethanol and lactate were used directly as efficient substrates for sulphate reduction while acetate yielded only slow growth. Glucose was utilised following fermentation to organic acids and therefore had a deleterious effect on pH. Ethanol was selected as the most efficient substrate due to cost and efficient yield of sulphide. On ethanol, the presence of additional carbon sources had no effect on growth or sulphate reduction in batch culture but the presence of complex nitrogen sources (yeast extract or cornsteep) stimulated both. Cornsteep showed the strongest effect and was also preferred on cost grounds. In continuous culture, cornsteep significantly improved the yield of sulphate reduced per unit of ethanol consumed. These results suggest that the most efficient nutrient regime for bioremediation using sulphate-reducing bacteria required both ethanol as carbon source and cornsteep as a complex nitrogen source.

  19. Contact Killing of Bacteria on Copper Is Suppressed if Bacterial-Metal Contact Is Prevented and Is Induced on Iron by Copper Ions

    PubMed Central

    Mathews, Salima; Hans, Michael

    2013-01-01

    Bacteria are rapidly killed on copper surfaces, and copper ions released from the surface have been proposed to play a major role in the killing process. However, it has remained unclear whether contact of the bacteria with the copper surface is also an important factor. Using laser interference lithography, we engineered copper surfaces which were covered with a grid of an inert polymer which prevented contact of the bacteria with the surface. Using Enterococcus hirae as a model organism, we showed that the release of ionic copper from these modified surfaces was not significantly reduced. In contrast, killing of bacteria was strongly attenuated. When E. hirae cells were exposed to a solid iron surface, the loss of cell viability was the same as on glass. However, exposing cells to iron in the presence of 4 mM CuSO4 led to complete killing in 100 min. These experiments suggest that contact killing proceeds by a mechanism whereby the metal-bacterial contact damages the cell envelope, which, in turn, makes the cells susceptible to further damage by copper ions. PMID:23396344

  20. Patterns of benthic bacterial diversity in coastal areas contaminated by heavy metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)

    PubMed Central

    Quero, Grazia Marina; Cassin, Daniele; Botter, Margherita; Perini, Laura; Luna, Gian Marco

    2015-01-01

    Prokaryotes in coastal sediments are fundamental players in the ecosystem functioning and regulate processes relevant in the global biogeochemical cycles. Nevertheless, knowledge on benthic microbial diversity patterns across spatial scales, or as function to anthropogenic influence, is still limited. We investigated the microbial diversity in two of the most chemically polluted sites along the coast of Italy. One site is the Po River Prodelta (Northern Adriatic Sea), which receives contaminant discharge from one of the largest rivers in Europe. The other site, the Mar Piccolo of Taranto (Ionian Sea), is a chronically polluted area due to steel production plants, oil refineries, and intense maritime traffic. We collected sediments from 30 stations along gradients of contamination, and studied prokaryotic diversity using Illumina sequencing of amplicons of a 16S rDNA gene fragment. The main sediment variables and the concentration of eleven metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured. Chemical analyses confirmed the high contamination in both sites, with concentrations of PCBs particularly high and often exceeding the sediment guidelines. The analysis of more than 3 millions 16S rDNA sequences showed that richness decreased with higher contamination levels. Multivariate analyses showed that contaminants significantly shaped community composition. Assemblages differed significantly between the two sites, but showed wide within-site variations related with spatial gradients in the chemical contamination, and the presence of a core set of OTUs shared by the two geographically distant sites. A larger importance of PCB-degrading taxa was observed in the Mar Piccolo, suggesting their potential selection in this historically polluted site. Our results indicate that sediment contamination by multiple contaminants significantly alter benthic prokaryotic diversity in coastal areas, and suggests considering the potential

  1. Patterns of benthic bacterial diversity in coastal areas contaminated by heavy metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs).

    PubMed

    Quero, Grazia Marina; Cassin, Daniele; Botter, Margherita; Perini, Laura; Luna, Gian Marco

    2015-01-01

    Prokaryotes in coastal sediments are fundamental players in the ecosystem functioning and regulate processes relevant in the global biogeochemical cycles. Nevertheless, knowledge on benthic microbial diversity patterns across spatial scales, or as function to anthropogenic influence, is still limited. We investigated the microbial diversity in two of the most chemically polluted sites along the coast of Italy. One site is the Po River Prodelta (Northern Adriatic Sea), which receives contaminant discharge from one of the largest rivers in Europe. The other site, the Mar Piccolo of Taranto (Ionian Sea), is a chronically polluted area due to steel production plants, oil refineries, and intense maritime traffic. We collected sediments from 30 stations along gradients of contamination, and studied prokaryotic diversity using Illumina sequencing of amplicons of a 16S rDNA gene fragment. The main sediment variables and the concentration of eleven metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured. Chemical analyses confirmed the high contamination in both sites, with concentrations of PCBs particularly high and often exceeding the sediment guidelines. The analysis of more than 3 millions 16S rDNA sequences showed that richness decreased with higher contamination levels. Multivariate analyses showed that contaminants significantly shaped community composition. Assemblages differed significantly between the two sites, but showed wide within-site variations related with spatial gradients in the chemical contamination, and the presence of a core set of OTUs shared by the two geographically distant sites. A larger importance of PCB-degrading taxa was observed in the Mar Piccolo, suggesting their potential selection in this historically polluted site. Our results indicate that sediment contamination by multiple contaminants significantly alter benthic prokaryotic diversity in coastal areas, and suggests considering the potential

  2. Effect of Rocking Movements on Respiration

    PubMed Central

    Omlin, Ximena; Crivelli, Francesco; Heinicke, Lorenz; Zaunseder, Sebastian; Achermann, Peter; Riener, Robert

    2016-01-01

    For centuries, rocking has been used to promote sleep in babies or toddlers. Recent research suggested that relaxation could play a role in facilitating the transition from waking to sleep during rocking. Breathing techniques are often used to promote relaxation. However, studies investigating head motions and body rotations showed that vestibular stimulation might elicit a vestibulo-respiratory response, leading to an increase in respiration frequency. An increase in respiration frequency would not be considered to promote relaxation in the first place. On the other hand, a coordination of respiration to rhythmic vestibular stimulation has been observed. Therefore, this study aimed to investigate the effect of different movement frequencies and amplitudes on respiration frequency. Furthermore, we tested whether subjects adapt their respiration to movement frequencies below their spontaneous respiration frequency at rest, which could be beneficial for relaxation. Twenty-one healthy subjects (24–42 years, 12 males) were investigated using an actuated bed, moving along a lateral translation. Following movement frequencies were applied: +30%, +15%, -15%, and -30% of subjects’ rest respiration frequency during baseline (no movement). Furthermore, two different movement amplitudes were tested (Amplitudes: 15 cm, 7.5 cm; movement frequency: 0.3 Hz). In addition, five subjects (25–28 years, 2 males) were stimulated with their individual rest respiration frequency. Rocking movements along a lateral translation caused a vestibulo-respiratory adaptation leading to an increase in respiration frequency. The increase was independent of the applied movement frequencies or amplitudes but did not occur when stimulating with subjects’ rest respiration frequency. Furthermore, no synchronization of the respiration frequency to the movement frequency was observed. In particular, subjects did not lower their respiration frequency below their resting frequency. Hence, it was not

  3. Soil respiration under climate warming: differential response of heterotrophic and autotrophic respiration.

    PubMed

    Wang, Xin; Liu, Lingli; Piao, Shilong; Janssens, Ivan A; Tang, Jianwu; Liu, Weixing; Chi, Yonggang; Wang, Jing; Xu, Shan

    2014-10-01

    Despite decades of research, how climate warming alters the global flux of soil respiration is still poorly characterized. Here, we use meta-analysis to synthesize 202 soil respiration datasets from 50 ecosystem warming experiments across multiple terrestrial ecosystems. We found that, on average, warming by 2 °C increased soil respiration by 12% during the early warming years, but warming-induced drought partially offset this effect. More significantly, the two components of soil respiration, heterotrophic respiration and autotrophic respiration showed distinct responses. The warming effect on autotrophic respiration was not statistically detectable during the early warming years, but nonetheless decreased with treatment duration. In contrast, warming by 2 °C increased heterotrophic respiration by an average of 21%, and this stimulation remained stable over the warming duration. This result challenged the assumption that microbial activity would acclimate to the rising temperature. Together, our findings demonstrate that distinguishing heterotrophic respiration and autotrophic respiration would allow us better understand and predict the long-term response of soil respiration to warming. The dependence of soil respiration on soil moisture condition also underscores the importance of incorporating warming-induced soil hydrological changes when modeling soil respiration under climate change.

  4. Measuring aerobic respiration in stream ecosystems using the resazurin-resorufin system

    NASA Astrophysics Data System (ADS)

    GonzáLez-Pinzón, Ricardo; Haggerty, Roy; Myrold, David D.

    2012-09-01

    The use of smart tracers to study hydrologic systems is becoming more widespread. Smart tracers are compounds that irreversibly react in the presence of a process or condition under investigation. Resazurin (Raz) is a smart tracer that undergoes an irreversible reduction to resorufin (Rru) in the presence of cellular metabolic activity. We quantified the relationship between the transformation of Raz and aerobic bacterial respiration in pure culture experiments using two obligate aerobes and two facultative anaerobes, and in colonized surface and shallow (<10 cm) hyporheic sediments using reach-scale experiments. We found that the transformation of Raz to Rru was nearly perfectly (minr2 = 0.986), positively correlated with aerobic microbial respiration in all experiments. These results suggest that Raz can be used as a surrogate to measure respiration in situ and in vivoat different spatial scales, thus providing an alternative to investigate mechanistic controls of solute transport and stream metabolism on nutrient processing. Lastly, a comparison of respiration and mass-transfer rates in streams suggests that field-scale respiration is controlled by the slower of respiration and mass transfer, highlighting the need to understand both biogeochemistry and physics in stream ecosystems.

  5. Cyanide-insensitive Respiration in Pea Cotyledons.

    PubMed

    James, T W; Spencer, M S

    1979-09-01

    Mitochondria isolated by a zonal procedure from the cotyledons of germinating peas possessed a cyanide-resistant respiration. This respiration was virtually absent in mitochondria isolated during the first 24 hours of germination but thereafter increased gradually until the 6th or 7th day of seedling development. At this time between 15 and 20% of the succinate oxidation was not inhibited by cyanide. The activity of the cyanide-resistant respiration was also determined in the absence of cyanide. Relationships among mitochondrial structure, cyanide-resistant respiration, and seedling development are discussed.

  6. Respirator selection for clandestine methamphetamine laboratory investigation.

    PubMed

    Nelson, Gary O; Bronder, Gregory D; Larson, Scott A; Parker, Jay A; Metzler, Richard W

    2012-01-01

    First responders to illicit drug labs may not always have SCBA protection available. Air-purifying respirators using organic vapor cartridges with P-100 filters may not be sufficient. It would be better to use a NIOSH-approved CBRN respirator with its required multi-purpose cartridge system, which includes a P-100 filter. This would remove all the primary drug lab contaminants—organic vapors, acid gases, ammonia, phosphine, iodine, and airborne meth particulates. To assure the proper selection and use of a respirator, it is recommended that the contaminants present be identified and quantified and the OSHA 29 CFR 1910.134 respirator protection program requirements followed. PMID:22571884

  7. Respirator protection factors: Part II-protection factors of supplied-air respirators.

    PubMed

    Hack, A L; Bradley, O D; Trujillo, A

    1980-05-01

    Protection Factors provided by 25 NIOSH approved supplied-air respirators were determined while the devices were worn by a panel of test subjects anthropometrically selected to represent adult facial sizes. Polydispersed DOP aerosol was used for respirator fit tests on continuous flow, demand, and pressure-demand respirators. Based on facepiece leakage measurements it appears that demand-type respirators should neither be used nor approved. The highest level of protection was provided by pressure-demand devices.

  8. Bacterial Sialidase

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

  9. Comparative study of heavy metal and pathogenic bacterial contamination in sludge and manure in biogas and non-biogas swine farms.

    PubMed

    Tulayakul, Phitsanu; Boonsoongnern, Alongkot; Kasemsuwan, Suwicha; Wiriyarampa, Srisamai; Pankumnoed, Juree; Tippayaluck, Suwanna; Hananantachai, Hathairad; Mingkhwan, Ratchaneekorn; Netvichian, Ramnaree; Khaodhiar, Sutha

    2011-01-01

    The objective of this study is to determine and compare the heavy metal (Zn, Cu, Cd, Pb) and bacterial (E. coli, coliform and Salmonella spp.) contamination between swine farms utilizing biogas and non-biogas systems in the central part of Thailand. Results showed that average levels of E. coli, coliform, BOD, COD, Zn, Cu and Pb in sludge from the post-biogas pond were higher than the standard limits. Moreover, the levels of E. coli, coliform, Cd and Pb were also higher than the standard limits for dry manure. The levels of E. coli, coliform and BOD on biogas farms were lower than on non-biogas farms. Following isolation of Salmonella spp., it was found that Salmonella serovars Rissen was the most abundant at 18.46% (12/65), followed by Anatum 12.31% (8/65), and Kedougou 9.23% (6/65). The pathogenic strains of Salmonella serovars Paratyphi B var. java and Typhimurium were present in equal amounts at 4.62% (3/65) in samples from all swine farms. This study revealed that significant reduction in E. coli and coliform levels in sludge from covered lagoon biogas systems on swine farms. The presence of Salmonella as well as Cd and Pb, in significant amount in dry manure, suggests that there is a high probability of environmental contamination if it is used for agricultural purposes. Thus, careful waste and manure disposal from swine farms and the regular monitoring of wastewater is strongly recommended to ensure the safety of humans, other animals and the environment. PMID:22066222

  10. 42 CFR 84.197 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Respirator containers; minimum requirements. 84.197... Cartridge Respirators § 84.197 Respirator containers; minimum requirements. Respirators shall be equipped... commercial designation of the respirator it contains and all appropriate approval labels....

  11. 42 CFR 84.250 - Vinyl chloride respirators; description.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Vinyl chloride respirators; description. 84.250... Respirators § 84.250 Vinyl chloride respirators; description. Vinyl chloride respirators, including all completely assembled respirators which are designed for use as respiratory protection during entry into...

  12. 42 CFR 84.134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Respirator containers; minimum requirements. 84.134... Respirators § 84.134 Respirator containers; minimum requirements. Supplied-air respirators shall be equipped... commercial designation of the respirator it contains, and all appropriate approval labels....

  13. 42 CFR 84.250 - Vinyl chloride respirators; description.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Vinyl chloride respirators; description. 84.250... Respirators § 84.250 Vinyl chloride respirators; description. Vinyl chloride respirators, including all completely assembled respirators which are designed for use as respiratory protection during entry into...

  14. Direct reading of electrocardiograms and respiration rates

    NASA Technical Reports Server (NTRS)

    Wise, J. P.

    1969-01-01

    Technique for reading heart and respiration rates is more accurate and direct than the previous method. Index of a plastic calibrated card is aligned with a point on the electrocardiogram. Complexes are counted as indicated on the card and heart or respiration rate is read directly from the appropriate scale.

  15. Photosynthesis and Respiration in a Jar.

    ERIC Educational Resources Information Center

    Buttner, Joseph K.

    2000-01-01

    Describes an activity that reduces the biosphere to a water-filled jar to simulate the relationship between cellular respiration, photosynthesis, and energy. Allows students in high school biology and related courses to explore quantitatively cellular respiration and photosynthesis in almost any laboratory setting. (ASK)

  16. Modelling Soil respiration in agro-ecosystems

    NASA Astrophysics Data System (ADS)

    Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth

    2013-04-01

    A soil respiration model was developed to simulate soil respiration in crops on a daily time step. The soil heterotrophic respiration component was derived from Century (Parton et al., 1987). Soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition rate coefficient. Carbon flows between these pools are controlled by carbon inputs (crop residues), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To model the soil autotrophic respiration component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence (Ryan et al., 1991). Growth respiration is calculated assuming a dependence on both growth rate and construction cost of the considered organ (MacCree et al., 1982) A database, made of four different soil and climate conditions in mid-latitude was used to study the two components of the soil respiration model in wheat fields. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to

  17. Physicochemical properties of respirable-size lunar dust

    NASA Astrophysics Data System (ADS)

    McKay, D. S.; Cooper, B. L.; Taylor, L. A.; James, J. T.; Thomas-Keprta, K.; Pieters, C. M.; Wentworth, S. J.; Wallace, W. T.; Lee, T. S.

    2015-02-01

    We separated the respirable dust and other size fractions from Apollo 14 bulk sample 14003,96 in a dry nitrogen environment. While our toxicology team performed in vivo and in vitro experiments with the respirable fraction, we studied the size distribution and shape, chemistry, mineralogy, spectroscopy, iron content and magnetic resonance of various size fractions. These represent the finest-grained lunar samples ever measured for either FMR np-Fe0 index or precise bulk chemistry, and are the first instance we know of in which SEM/TEM samples have been obtained without using liquids. The concentration of single-domain, nanophase metallic iron (np-Fe0) increases as particle size diminishes to 2 μm, confirming previous extrapolations. Size-distribution studies disclosed that the most frequent particle size was in the 0.1-0.2 μm range suggesting a relatively high surface area and therefore higher potential toxicity. Lunar dust particles are insoluble in isopropanol but slightly soluble in distilled water (~0.2 wt%/3 days). The interaction between water and lunar fines, which results in both agglomeration and partial dissolution, is observable on a macro scale over time periods of less than an hour. Most of the respirable grains were smooth amorphous glass. This suggests less toxicity than if the grains were irregular, porous, or jagged, and may account for the fact that lunar dust is less toxic than ground quartz.

  18. Sleep and Respiration in Microgravity

    NASA Technical Reports Server (NTRS)

    West, John B.; Elliott, Ann R.; Prisk, G. Kim; Paiva, Manuel

    2003-01-01

    Sleep is often reported to be of poor quality in microgravity, and studies on the ground have shown a strong relationship between sleep-disordered breathing and sleep disruption. During the 16-day Neurolab mission, we studied the influence of possible changes in respiratory function on sleep by performing comprehensive sleep recordings on the payload crew on four nights during the mission. In addition, we measured the changes in the ventilatory response to low oxygen and high carbon dioxide in the same subjects during the day, hypothesizing that changes in ventilatory control might affect respiration during sleep. Microgravity caused a large reduction in the ventilatory response to reduced oxygen. This is likely the result of an increase in blood pressure at the peripheral chemoreceptors in the neck that occurs when the normally present hydrostatic pressure gradient between the heart and upper body is abolished. This reduction was similar to that seen when the subjects were placed acutely in the supine position in one-G. In sharp contrast to low oxygen, the ventilatory response to elevated carbon dioxide was unaltered by microgravity or the supine position. Because of the similarities of the findings in microgravity and the supine position, it is unlikely that changes in ventilatory control alter respiration during sleep in microgravity. During sleep on the ground, there were a small number of apneas (cessation of breathing) and hypopneas (reduced breathing) in these normal subjects. During sleep in microgravity, there was a reduction in the number of apneas and hypopneas per hour compared to preflight. Obstructive apneas virtually disappeared in microgravity, suggesting that the removal of gravity prevents the collapse of upper airways during sleep. Arousals from sleep were reduced in microgravity compared to preflight, and virtually all of this reduction was as a result of a reduction in the number of arousals from apneas and hypopneas. We conclude that any sleep

  19. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and... contamination of respirators which are not removed, and to prevent damage to respirators during transit....

  20. Apparatus and method for the characterization of respirable aerosols

    DOEpatents

    Clark, Douglas K.; Hodges, Bradley W.; Bush, Jesse D.; Mishima, Jofu

    2016-05-31

    An apparatus for the characterization of respirable aerosols, including: a burn chamber configured to selectively contain a sample that is selectively heated to generate an aerosol; a heating assembly disposed within the burn chamber adjacent to the sample; and a sampling segment coupled to the burn chamber and configured to collect the aerosol such that it may be analyzed. The apparatus also includes an optional sight window disposed in a wall of the burn chamber such that the sample may be viewed during heating. Optionally, the sample includes one of a Lanthanide, an Actinide, and a Transition metal.

  1. Performance of the piezoelectric microbalance respirable aerosol sensor.

    PubMed

    Sem, G J; Tsurubayashi, K; Homma, K

    1977-11-01

    A battery-portable respirable aerosol sensor has been experimentally evaluated. Calibration procedures are described. For instruments calibrated with welding smoke, test results show agreement within +/- 15% of parallel filter samples for 10 laboratory and industrial aerosols including welding and tobacco smoke, oil mist, cotton and asbestos mill dusts, powdered metal and walnut shell dusts, and atmospheric urban aerosol in the 0.05-5.5 mg/m3 range. Results show that an average of several piezobalance measurements can accurately simulate a time-integrated filter sample in many industrial environments.

  2. Effect of long-term industrial waste effluent pollution on soil enzyme activities and bacterial community composition.

    PubMed

    Subrahmanyam, Gangavarapu; Shen, Ju-Pei; Liu, Yu-Rong; Archana, Gattupalli; Zhang, Li-Mei

    2016-02-01

    Although numerous studies have addressed the influence of exogenous pollutants on microorganisms, the effect of long-term industrial waste effluent (IWE) pollution on the activity and diversity of soil bacteria was still unclear. Three soil samples characterized as uncontaminated (R1), moderately contaminated (R2), and highly contaminated (R3) receiving mixed organic and heavy metal pollutants for more than 20 years through IWE were collected along the Mahi River basin, Gujarat, western India. Basal soil respiration and in situ enzyme activities indicated an apparent deleterious effect of IWE on microbial activity and soil function. Community composition profiling of soil bacteria using 16S rRNA gene amplification and denaturing gradient gel electrophoresis (DGGE) method indicated an apparent bacterial community shift in the IWE-affected soils. Cloning and sequencing of DGGE bands revealed that the dominated bacterial phyla in polluted soil were affiliated with Firmicutes, Acidobacteria, and Actinobacteria, indicating that these bacterial phyla may have a high tolerance to pollutants. We suggested that specific bacterial phyla along with soil enzyme activities could be used as relevant biological indicators for long-term pollution assessment on soil quality. Graphical Abstract Bacterial community profiling and soil enzyme activities in long-term industrial waste effluent polluted soils.

  3. Effect of long-term industrial waste effluent pollution on soil enzyme activities and bacterial community composition.

    PubMed

    Subrahmanyam, Gangavarapu; Shen, Ju-Pei; Liu, Yu-Rong; Archana, Gattupalli; Zhang, Li-Mei

    2016-02-01

    Although numerous studies have addressed the influence of exogenous pollutants on microorganisms, the effect of long-term industrial waste effluent (IWE) pollution on the activity and diversity of soil bacteria was still unclear. Three soil samples characterized as uncontaminated (R1), moderately contaminated (R2), and highly contaminated (R3) receiving mixed organic and heavy metal pollutants for more than 20 years through IWE were collected along the Mahi River basin, Gujarat, western India. Basal soil respiration and in situ enzyme activities indicated an apparent deleterious effect of IWE on microbial activity and soil function. Community composition profiling of soil bacteria using 16S rRNA gene amplification and denaturing gradient gel electrophoresis (DGGE) method indicated an apparent bacterial community shift in the IWE-affected soils. Cloning and sequencing of DGGE bands revealed that the dominated bacterial phyla in polluted soil were affiliated with Firmicutes, Acidobacteria, and Actinobacteria, indicating that these bacterial phyla may have a high tolerance to pollutants. We suggested that specific bacterial phyla along with soil enzyme activities could be used as relevant biological indicators for long-term pollution assessment on soil quality. Graphical Abstract Bacterial community profiling and soil enzyme activities in long-term industrial waste effluent polluted soils. PMID:26803661

  4. Bacterial Proteasomes

    PubMed Central

    Jastrab, Jordan B.; Darwin, K. Heran

    2015-01-01

    Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology. PMID:26488274

  5. Bacterial concrete

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Venkataswamy; Ramesh, K. P.; Bang, S. S.

    2001-04-01

    Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self-repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii and Sporosarcina bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and CaCl2 medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places. Energy- dispersive X-ray (EDX) spectra of the microbial precipitation on the surface of the crack indicated the abundance of calcium and the precipitation was inferred to be calcite (CaCO3).

  6. Inhalation exposure of lead in brass foundry workers: the evaluation of the effectiveness of a powered air-purifying respirator and engineering controls.

    PubMed

    Que Hee, S S; Lawrence, P

    1983-10-01

    The protection that a powered air-purifying respirator afforded to ladle and furnace attendants who were exposed to lead, copper and zinc fumes in a brass foundry was found by measuring metal levels at the lapel and at nose level inside the respirator. Respirator fit was evaluated by use of a hot-wire anemometer at the face/Tyvek seal interfaces, and at the exit of the respirator. Effective protection factors for lead ranged from 1.05 to 67. Ergonomic factors and engineering controls are also discussed. PMID:6650396

  7. The world-class Howard's Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

    NASA Astrophysics Data System (ADS)

    Gadd, Michael G.; Layton-Matthews, Daniel; Peter, Jan M.; Paradis, Suzanne; Jonasson, Ian R.

    2016-07-01

    The Howard's Pass district of sedimentary exhalative (SEDEX) Zn-Pb deposits is located in Yukon Territory and comprises 14 Zn-Pb deposits that contain an estimated 400.7 Mt of sulfide mineralization grading 4.5 % Zn and 1.5 % Pb. Mineralization is hosted in carbonaceous and calcareous and, to a lesser extent, siliceous mudstones. Pyrite is a minor but ubiquitous mineral in the host rocks stratigraphically above, within, and below mineralization. Petrographic analyses reveal that pyrite has a complex and protracted growth history, preserving multiple generations of pyrite within single grains. Sulfur isotope analysis of paragenetically complex pyrite by secondary ion mass spectrometry (SIMS) reveals that sulfur isotope compositions vary with textural zonation. Within the Zn-Pb deposits, framboidal pyrite is the earliest pyrite generation recognized, and this exclusively has negative δ34S values (mean = -16.6 ± 4.1 ‰; n = 55), whereas paragenetically later pyrite and galena possess positive δ34S values (mean = 29.1 ± 7.5 and 22.4 ± 3.0 ‰, n = 13 and 13, respectively). Previous studies found that sphalerite and galena mineral separates have exclusively positive δ34S values (mean = 16.8 ± 3.3 and 12.7 ± 2.8 ‰, respectively; Goodfellow and Jonasson 1986). These distinct sulfur isotope values are interpreted to reflect varying contributions of bacterially reduced seawater sulfate (negative; framboidal pyrite) and thermochemically reduced seawater sulfate and/or hydrothermal sulfate (positive; galena, sphalerite, later forms of pyrite). Textural evidence indicates that framboidal pyrite predates galena and sphalerite deposition. Collectively, the in situ and bulk sulfur isotope data are much more complex than δ34S values permitted by prevailing genetic models that invoke only biogenically reduced sulfur and coeval deposition of galena, sphalerite, and framboidal pyrite within a euxinic water column, and we present several lines of evidence that argue

  8. I. Development of Metal-Mediated SPOT-Synthesis Methods for the Efficient Construction of Small-Molecule Macroarrays. II. Design and Synthesis of Novel Bacterial Biofilm Inhibitors

    NASA Astrophysics Data System (ADS)

    Frei, Reto

    I. The use of small molecule probes to explore biological phenomena has become a valuable tool in chemical biology. As a result, methods that permit the rapid synthesis and biological evaluation of such compounds are highly sought-after. The small molecule macroarray represents one such approach for the synthesis and identification of novel bioactive agents. Macroarrays are readily constructed via the SPOT-synthesis technique on planar cellulose membranes, yielding spatially addressed libraries of ˜10-1000 unique compounds. We sought to expand the arsenal of chemical reactions compatible with this solid-phase platform, and developed highly efficient SPOT-synthesis protocols for the Mizoroki-Heck, Suzuki-Miyaura, and copper-catalyzed azide-alkyne cycloaddition reaction. We demonstrated that these metal-mediated reactions can be implemented, either individually or sequentially, for the efficient construction of small molecules in high purity on rapid time scales. Utilizing these powerful C-C and C-N bond forming coupling reactions, we constructed a series of macroarrays based on novel stilbene, phenyl-naphthalene, and triazole scaliblds. Subsequent biological testing of the stilbene and phenyl-naphthalene libraries revealed several potent antagonists and agonists, respectively, of the quorum sensing (QS) receptor LuxR in Vibrio fischeri. II. Bacteria living within biofilms are notorious for their resistance to known antibiotic agents, and constitute a major human health threat. Methods to attenuate biofilm growth would have a significant impact on the management of bacterial infections. Despite intense research efforts, small molecules capable of either inhibiting or dispersing biolilms remain scarce. We utilized natural products with purported anti-biofilm or QS inhibitory activity as sources of structural insight to guide the synthesis of novel biofilm modulators with improved activities. These studies revealed 2-aminobenzimidazole derivatives as highly potent

  9. Respirator physiological effects under simulated work conditions.

    PubMed

    Bansal, Siddharth; Harber, Philip; Yun, David; Liu, David; Liu, Yihang; Wu, Samantha; Ng, David; Santiago, Silverio

    2009-04-01

    This study compared the physiological impacts of two respirator types in simulated work conditions. Fifty-six subjects included normal volunteers and persons with mild respiratory impairments (chronic rhinitis, mild COPD, and mild asthma). Respiratory parameters and electrocardiogram were measured using respiratory inductive plethysmography while performing eight work tasks involving low to moderate exertion using two respirators: (1) a dual cartridge half face mask (HFM) respirator, and (2) the N95. Mixed model regression analyses evaluating the effect of task and respirator type showed that task affected tidal volume, minute ventilation, breathing frequency and heart rate; all were greater in heavier tasks. Although respirator type did not affect respiratory volume parameters and flow rates, the HFM led to increase in the inspiratory time, reduction of the expiratory time, and increase in the duty cycle in comparison with the N95. The magnitude of differences was relatively small. The results suggest that most individuals, including persons with mild respiratory impairments, will physiologically tolerate either type of respirator at low to moderate exertion tasks. However, because effective protection depends on proper use, differences in subjective effect may have greater impact than physiological differences. Using respirators may be feasible on a widespread basis if necessary for maintaining essential services in the face of widespread concern about an infectious or terrorist threat. PMID:19180375

  10. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

    PubMed Central

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-01-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community. PMID:27241173

  11. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China.

    PubMed

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-01-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community. PMID:27241173

  12. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

    NASA Astrophysics Data System (ADS)

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-05-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community.

  13. Environmental and genotypic effects on the respiration associated with symbiotic nitrogen fixation in peas.

    PubMed

    Mahon, J D

    1979-05-01

    Estimated values for the respiration associated with symbiotic nitrogen fixation in Pisum sativum L. were independent of irradiance, temperature, plant age, and CO(2) concentration, despite large variation in the total rates of C(2)H(2) reduction and root + nodule respiration. Similar values were also found in Phaseolus vulgaris L., Vicia faba L. and Glycine max (L.) Merr. Among all combinations of four Pisum cultivars with four Rhizobium leguminosarum inoculants only the plant genotype significantly affected the fixation-linked respiration, although both plant and bacterial types significantly influenced the total rate of C(2)H(2) reduction. On the basis of measured rates of H(2) evolution and C(2)H(2) reduction, or total nitrogen gain in the same system, the least respiration per unit of ammonia produced symbiotically was estimated as 4.8 to 6.9 moles CO(2) (mole NH(3))(-1) in Laxton's Progress and the greatest as 9.3 to 13.3 moles CO(2) (mole NH(3))(-1) in an Indian cultivar, as compared to a theoretical minimum respiration requirement of 4.7 moles CO(2) (mole NH(3))(-1) in peas.

  14. Environmental and Genotypic Effects on the Respiration Associated with Symbiotic Nitrogen Fixation in Peas 1

    PubMed Central

    Mahon, John D.

    1979-01-01

    Estimated values for the respiration associated with symbiotic nitrogen fixation in Pisum sativum L. were independent of irradiance, temperature, plant age, and CO2 concentration, despite large variation in the total rates of C2H2 reduction and root + nodule respiration. Similar values were also found in Phaseolus vulgaris L., Vicia faba L. and Glycine max (L.) Merr. Among all combinations of four Pisum cultivars with four Rhizobium leguminosarum inoculants only the plant genotype significantly affected the fixation-linked respiration, although both plant and bacterial types significantly influenced the total rate of C2H2 reduction. On the basis of measured rates of H2 evolution and C2H2 reduction, or total nitrogen gain in the same system, the least respiration per unit of ammonia produced symbiotically was estimated as 4.8 to 6.9 moles CO2 (mole NH3)−1 in Laxton's Progress and the greatest as 9.3 to 13.3 moles CO2 (mole NH3)−1 in an Indian cultivar, as compared to a theoretical minimum respiration requirement of 4.7 moles CO2 (mole NH3)−1 in peas. PMID:16660833

  15. Soil microbial community composition and respiration along an experimental precipitation gradient in a semiarid steppe

    PubMed Central

    Zhao, Cancan; Miao, Yuan; Yu, Chengde; Zhu, Lili; Wang, Feng; Jiang, Lin; Hui, Dafeng; Wan, Shiqiang

    2016-01-01

    As a primary limiting factor in arid and semiarid regions, precipitation strongly influences soil microbial properties. However, the patterns and mechanisms of soil microbial responses to precipitation have not been well documented. In this study, changes in soil microorganisms along an experimental precipitation gradient with seven levels of precipitation manipulation (i.e., ambient precipitation as a control, and ±20%, ±40%, and ±60% of ambient precipitation) were explored in a semiarid temperate steppe in northern China. Soil microbial biomass carbon and respiration as well as the ratio of fungal to bacterial biomass varied along the experimental precipitation gradient and peaked under the +40% precipitation treatment. The shifts in microbial community composition could be largely attributable to the changes in soil water and nutrient availability. The metabolic quotient increased (indicating reduced carbon use efficiency) with increasing precipitation due to the leaching of dissolved organic carbon. The relative contributions of microbial respiration to soil and ecosystem respiration increased with increasing precipitation, suggesting that heterotrophic respiration will be more sensitive than autotrophic respiration if precipitation increases in the temperate steppe as predicted under future climate-change scenarios. PMID:27074973

  16. Particulate Respirators Functionalized with Silver Nanoparticles Showed Excellent Real-Time Antimicrobial Effects against Pathogens.

    PubMed

    Zheng, Clark Renjun; Li, Shuai; Ye, Chengsong; Li, Xinyang; Zhang, Chiqian; Yu, Xin

    2016-07-01

    Particulate respirators designed to filtrate fine particulate matters usually do not possess antimicrobial functions. The current study aimed to functionalize particulate respirators with silver nanoparticles (nanosilver or AgNPs), which have excellent antimicrobial activities, utilizing a straightforward and effective method. We first enhanced the nanosilver-coating ability of nonwoven fabrics from a particulate respirator through surface modification by sodium oleate. The surfactant treatment significantly improved the fabrics' water wet preference where the static water contact angles reduced from 122° to 56°. Both macroscopic agar-plate tests and microscopic scanning electron microscope (SEM) characterization revealed that nanosilver functionalized fabrics could effectively inhibit the growth of two model bacterial strains (i.e., Staphylococcus aureus and Pseudomonas aeruginosa). The coating of silver nanoparticles would not affect the main function of particulate respirators (i.e., filtration of fine air-borne particles). Nanosilver coated particulate respirators with excellent antimicrobial activities can provide real-time protection to people in regions with severe air pollution against air-borne pathogens. PMID:27327938

  17. Soil microbial community composition and respiration along an experimental precipitation gradient in a semiarid steppe.

    PubMed

    Zhao, Cancan; Miao, Yuan; Yu, Chengde; Zhu, Lili; Wang, Feng; Jiang, Lin; Hui, Dafeng; Wan, Shiqiang

    2016-04-14

    As a primary limiting factor in arid and semiarid regions, precipitation strongly influences soil microbial properties. However, the patterns and mechanisms of soil microbial responses to precipitation have not been well documented. In this study, changes in soil microorganisms along an experimental precipitation gradient with seven levels of precipitation manipulation (i.e., ambient precipitation as a control, and ±20%, ±40%, and ±60% of ambient precipitation) were explored in a semiarid temperate steppe in northern China. Soil microbial biomass carbon and respiration as well as the ratio of fungal to bacterial biomass varied along the experimental precipitation gradient and peaked under the +40% precipitation treatment. The shifts in microbial community composition could be largely attributable to the changes in soil water and nutrient availability. The metabolic quotient increased (indicating reduced carbon use efficiency) with increasing precipitation due to the leaching of dissolved organic carbon. The relative contributions of microbial respiration to soil and ecosystem respiration increased with increasing precipitation, suggesting that heterotrophic respiration will be more sensitive than autotrophic respiration if precipitation increases in the temperate steppe as predicted under future climate-change scenarios.

  18. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    NASA Astrophysics Data System (ADS)

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  19. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    SciTech Connect

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-06-15

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  20. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces.

    PubMed

    Gross, Benjamin J; El-Naggar, Mohamed Y

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  1. BOREAS TE-5 Soil Respiration Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. Soil respiration data were collected from 26-May-94 to 07-Sep-94 in the BOREAS NSA and SSA to compare the soil respiration rates in different forest sites using a LI-COR 6200 soil respiration chamber (model 6299). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  2. The effect of subject characteristics and respirator features on respirator fit.

    PubMed

    Zhuang, Ziqing; Coffey, Christopher C; Ann, Roland Berry

    2005-12-01

    A recent study was conducted to compare five fit test methods for screening out poor-fitting N95 filtering-facepiece respirators. Eighteen models of NIOSH-certified, N95 filtering-facepiece respirators were used to assess the fit test methods by using a simulated workplace protection factor (SWPF) test. The purpose of this companion study was to investigate the effect of subject characteristics (gender and face dimensions) and respirator features on respirator fit. The respirator features studied were design style (folding and cup style) and number of sizes available (one size fits all, two sizes, and three sizes). Thirty-three subjects participated in this study. Each was measured for 12 face dimensions using traditional calipers and tape. From this group, 25 subjects with face size categories 1 to 10 tested each respirator. The SWPF test protocol entailed using the PortaCount Plus to determine a SWPF based on total penetration (face-seal leakage plus filter penetration) while the subject performed six simulated workplace movements. Six tests were conducted for each subject/respirator model combination with redonning between tests. The respirator design style (folding style and cup style) did not have a significant effect on respirator fit in this study. The number of respirator sizes available for a model had significant impact on respirator fit on the panel for cup-style respirators with one and two sizes available. There was no significant difference in the geometric mean fit factor between male and female subjects for 16 of the 18 respirator models. Subsets of one to six face dimensions were found to be significantly correlated with SWPFs (p < 0.05) in 16 of the 33 respirator model/respirator size combinations. Bigonial breadth, face width, face length, and nose protrusion appeared the most in subsets (five or six) of face dimensions and their multiple linear regression coefficients were significantly different from zero (p < 0.05). Lip length was found in

  3. Respiration in Neonate Sea Turtles

    PubMed Central

    Paladino, Frank V.; Strohl, Kingman P.; Pilar Santidrián, T.; Klann, Kenneth; Spotila, James R.

    2007-01-01

    The pattern and control of respiration is virtually unknown in hatchling sea turtles. Using incubator-raised turtles, we measured oxygen consumption, frequency, tidal volume, and minute volume for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) turtle hatchlings for the first six days after pipping. In addition, we tested the hatchlings’ response to hypercapnic, hyperoxic, and hypoxic challenges over this time period. Hatchling sea turtles generally showed resting ventilation characteristics that are similar to those of adults: a single breath followed by a long respiratory pause, slow frequency, and high metabolic rate. With hypercapnic challenge, both species responded primarily by elevating respiratory frequency via a decrease in the non-ventilatory period. Leatherback resting tidal volume increased with age but otherwise, neither species’ resting respiratory pattern nor response to gas challenge changed significantly over the first few days after hatching. At the time of nest emergence, sea turtles have achieved a respiratory pattern that is similar to that of actively diving adults. PMID:17258487

  4. [Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

    PubMed

    Lu, Xing-li; Liao, Yun-cheng

    2015-06-01

    To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P < 0.05), which could explain 35%-75% variability of soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

  5. Photosynthesis and Respiration in Leaf Slices.

    ERIC Educational Resources Information Center

    Brown, Simon

    1998-01-01

    Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)

  6. Snorkel tracheotomy tube for respirator use.

    PubMed

    LEBO, C P

    1954-07-01

    The Snorkel tracheotomy tube, a simple modification of the standard tube, overcomes many of the mechanical inconveniences usually encountered in the care of patients with tracheotomy who have to be kept in respirators. With it in place, it is not necessary to use special devices to hold the collar of the respirator away from the site of the tracheal incision. Nursing care of the patient is made easier.

  7. THE TEMPERATURE CHARACTERISTIC OF RESPIRATION OF AZOTOBACTER.

    PubMed

    Lineweaver, H; Burk, D; Horner, C K

    1932-05-20

    The temperature characteristic of respiration of Azotobacter vinelandii possesses a constant value of 19,330 +/- 165 over the temperature range 20-30 degrees C. This value is independent of pH, oxygen tension, age of culture, and other factors within the limits studied. The optimum temperature of respiration is 34-35 degrees C., with limits at about 10 degrees and 50 degrees C.

  8. Ultrafine and respirable particle exposure during vehicle fire suppression.

    PubMed

    Evans, Douglas E; Fent, Kenneth W

    2015-10-01

    Vehicle fires are a common occurrence, yet few studies have reported exposures associated with burning vehicles. This article presents an assessment of firefighters' potential for ultrafine and respirable particle exposure during vehicle fire suppression training. Fires were initiated within the engine compartment and passenger cabins of three salvaged vehicles, with subsequent water suppression by fire crews. Firefighter exposures were monitored with an array of direct reading particle and air quality instruments. A flexible metallic duct and blower drew contaminants to the instrument array, positioned at a safe distance from the burning vehicles, with the duct inlet positioned at the nozzle operator's shoulder. The instruments measured the particle number, active surface area, respirable particle mass, photoelectric response, aerodynamic particle size distributions, and air quality parameters. Although vehicle fires were suppressed quickly (<10 minutes), firefighters may be exposed to short duration, high particle concentration episodes during fire suppression, which are orders of magnitude greater than the ambient background concentration. A maximum transient particle concentration of 1.21 × 10(7) particles per cm(3), 170 mg m(-3) respirable particle mass, 4700 μm(2) cm(-3) active surface area and 1400 (arbitrary units) in photoelectric response were attained throughout the series of six fires. Expressed as fifteen minute time-weighted averages, engine compartment fires averaged 5.4 × 10(4) particles per cm(3), 0.36 mg m(-3) respirable particle mass, 92 μm(2) cm(-3) active particle surface area and 29 (arbitrary units) in photoelectric response. Similarly, passenger cabin fires averaged 2.04 × 10(5) particles per cm(3), 2.7 mg m(-3) respirable particle mass, 320 μm(2) cm(-3) active particle surface area, and 34 (arbitrary units) in photoelectric response. Passenger cabin fires were a greater potential source of exposure than engine compartment fires. The

  9. Ultrafine and respirable particle exposure during vehicle fire suppression.

    PubMed

    Evans, Douglas E; Fent, Kenneth W

    2015-10-01

    Vehicle fires are a common occurrence, yet few studies have reported exposures associated with burning vehicles. This article presents an assessment of firefighters' potential for ultrafine and respirable particle exposure during vehicle fire suppression training. Fires were initiated within the engine compartment and passenger cabins of three salvaged vehicles, with subsequent water suppression by fire crews. Firefighter exposures were monitored with an array of direct reading particle and air quality instruments. A flexible metallic duct and blower drew contaminants to the instrument array, positioned at a safe distance from the burning vehicles, with the duct inlet positioned at the nozzle operator's shoulder. The instruments measured the particle number, active surface area, respirable particle mass, photoelectric response, aerodynamic particle size distributions, and air quality parameters. Although vehicle fires were suppressed quickly (<10 minutes), firefighters may be exposed to short duration, high particle concentration episodes during fire suppression, which are orders of magnitude greater than the ambient background concentration. A maximum transient particle concentration of 1.21 × 10(7) particles per cm(3), 170 mg m(-3) respirable particle mass, 4700 μm(2) cm(-3) active surface area and 1400 (arbitrary units) in photoelectric response were attained throughout the series of six fires. Expressed as fifteen minute time-weighted averages, engine compartment fires averaged 5.4 × 10(4) particles per cm(3), 0.36 mg m(-3) respirable particle mass, 92 μm(2) cm(-3) active particle surface area and 29 (arbitrary units) in photoelectric response. Similarly, passenger cabin fires averaged 2.04 × 10(5) particles per cm(3), 2.7 mg m(-3) respirable particle mass, 320 μm(2) cm(-3) active particle surface area, and 34 (arbitrary units) in photoelectric response. Passenger cabin fires were a greater potential source of exposure than engine compartment fires. The

  10. Ultrafine and respirable particle exposure during vehicle fire suppression

    PubMed Central

    Fent, Kenneth W.

    2015-01-01

    Vehicle fires are a common occurrence, yet few studies have reported exposures associated with burning vehicles. This article presents an assessment of firefighters’ potential for ultrafine and respirable particle exposure during vehicle fire suppression training. Fires were initiated within the engine compartment and passenger cabins of three salvaged vehicles, with subsequent water suppression by fire crews. Firefighter exposures were monitored with an array of direct reading particle and air quality instruments. A flexible metallic duct and blower drew contaminants to the instrument array, positioned at a safe distance from the burning vehicles, with the duct inlet positioned at the nozzle operator’s shoulder. The instruments measured the particle number, active surface area, respirable particle mass, photoelectric response, aerodynamic particle size distributions, and air quality parameters. Although vehicle fires were suppressed quickly (<10 minutes), firefighters may be exposed to short duration, high particle concentration episodes during fire suppression, which are orders of magnitude greater than the ambient background concentration. A maximum transient particle concentration of 1.21 × 107 particles per cm3, 170 mg m−3 respirable particle mass, 4700 μm2 cm−3 active surface area and 1400 (arbitrary units) in photoelectric response were attained throughout the series of six fires. Expressed as fifteen minute time-weighted averages, engine compartment fires averaged 5.4 × 104 particles per cm3, 0.36 mg m−3 respirable particle mass, 92 μm2 cm−3 active particle surface area and 29 (arbitrary units) in photoelectric response. Similarly, passenger cabin fires averaged 2.04 × 105 particles per cm3, 2.7 mg m−3 respirable particle mass, 320 μm2 cm−3 active particle surface area, and 34 (arbitrary units) in photoelectric response. Passenger cabin fires were a greater potential source of exposure than engine compartment fires. The wind direction

  11. 42 CFR 84.130 - Supplied-air respirators; description.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Supplied-air respirators; description. 84.130... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.130 Supplied-air respirators; description. Supplied-air respirators, including all...

  12. 42 CFR 84.130 - Supplied-air respirators; description.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Supplied-air respirators; description. 84.130... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.130 Supplied-air respirators; description. Supplied-air respirators, including all...

  13. 42 CFR 84.130 - Supplied-air respirators; description.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Supplied-air respirators; description. 84.130... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.130 Supplied-air respirators; description. Supplied-air respirators, including all...

  14. 42 CFR 84.134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.134... Respirators § 84.134 Respirator containers; minimum requirements. Supplied-air respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type...

  15. 42 CFR 84.174 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.174... Air-Purifying Particulate Respirators § 84.174 Respirator containers; minimum requirements. (a) Except..., durable container bearing markings which show the applicant's name, the type of respirator it...

  16. 42 CFR 84.197 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.197... Cartridge Respirators § 84.197 Respirator containers; minimum requirements. Respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type...

  17. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  18. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  19. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  20. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  1. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  2. 42 CFR 84.130 - Supplied-air respirators; description.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Supplied-air respirators; description. 84.130... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.130 Supplied-air respirators; description. Supplied-air respirators, including all...

  3. 42 CFR 84.174 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Respirator containers; minimum requirements. 84.174... Air-Purifying Particulate Respirators § 84.174 Respirator containers; minimum requirements. (a) Except as provided in paragraph (b) of this section each respirator shall be equipped with a...

  4. 42 CFR 84.1131 - Respirators; required components.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Respirators; required components. 84.1131 Section..., and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1131 Respirators; required components. (a) Each respirator described in § 84.1130...

  5. 42 CFR 84.1131 - Respirators; required components.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirators; required components. 84.1131 Section..., and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1131 Respirators; required components. (a) Each respirator described in § 84.1130...

  6. Bacterial Keratitis

    MedlinePlus

    ... very quickly, and if left untreated, can cause blindness. The bacteria usually responsible for this type of ... to intense ultraviolet radiation exposure, e.g. snow blindness or welder's arc eye). Next Bacterial Keratitis Symptoms ...

  7. Shared and distinct mechanisms of iron acquisition by bacterial and fungal pathogens of humans

    PubMed Central

    Caza, Mélissa; Kronstad, James W.

    2013-01-01

    Iron is the most abundant transition metal in the human body and its bioavailability is stringently controlled. In particular, iron is tightly bound to host proteins such as transferrin to maintain homeostasis, to limit potential damage caused by iron toxicity under physiological conditions and to restrict access by pathogens. Therefore, iron acquisition during infection of a human host is a challenge that must be surmounted by every successful pathogenic microorganism. Iron is essential for bacterial and fungal physiological processes such as DNA replication, transcription, metabolism, and energy generation via respiration. Hence, pathogenic bacteria and fungi have developed sophisticated strategies to gain access to iron from host sources. Indeed, siderophore production and transport, iron acquisition from heme and host iron-containing proteins such as hemoglobin and transferrin, and reduction of ferric to ferrous iron with subsequent transport are all strategies found in bacterial and fungal pathogens of humans. This review focuses on a comparison of these strategies between bacterial and fungal pathogens in the context of virulence and the iron limitation that occurs in the human body as a mechanism of innate nutritional defense. PMID:24312900

  8. Genotoxicity of air pollution in a non-ferrous metal foundry in three bacterial tests and a micronucleus test--a comparative study.

    PubMed

    Gasiorowski, K; Szyba, K; Sawicka, J; Osada, A; Gonera, B; Gulanowski, B

    1989-01-01

    Acetone extracts of dusts and fumes collected at workplaces in a non-ferrous metal foundry exhibited genotoxic activity in all of the tests used. Of the compared tests, the Ames method is the most useful for preliminary screening detection of the genotoxic agents that are present in acetone extracts of dusts and fumes emitted at workplaces in a non-ferrous metal foundry.

  9. Effects of Picoxystrobin and 4-n-Nonylphenol on Soil Microbial Community Structure and Respiration Activity

    PubMed Central

    Stenrød, Marianne; Klemsdal, Sonja S.; Norli, Hans Ragnar; Eklo, Ole Martin

    2013-01-01

    There is widespread use of chemical amendments to meet the demands for increased productivity in agriculture. Potentially toxic compounds, single or in mixtures, are added to the soil medium on a regular basis, while the ecotoxicological risk assessment procedures mainly follow a chemical by chemical approach. Picoxystrobin is a fungicide that has caused concern due to studies showing potentially detrimental effects to soil fauna (earthworms), while negative effects on soil microbial activities (nitrification, respiration) are shown to be transient. Potential mixture situations with nonylphenol, a chemical frequently occurring as a contaminant in sewage sludge used for land application, infer a need to explore whether these chemicals in mixture could alter the potential effects of picoxystrobin on the soil microflora. The main objective of this study was to assess the effects of picoxystrobin and nonylphenol, as single chemicals and mixtures, on soil microbial community structure and respiration activity in an agricultural sandy loam. Effects of the chemicals were assessed through measurements of soil microbial respiration activity and soil bacterial and fungal community structure fingerprints, together with a degradation study of the chemicals, through a 70 d incubation period. Picoxystrobin caused a decrease in the respiration activity, while 4-n-nonylphenol caused an increase in respiration activity concurring with a rapid degradation of the substance. Community structure fingerprints were also affected, but these results could not be directly interpreted in terms of positive or negative effects, and were indicated to be transient. Treatment with the chemicals in mixture caused less evident changes and indicated antagonistic effects between the chemicals in soil. In conclusion, the results imply that the application of the fungicide picoxystrobin and nonylphenol from sewage sludge application to agricultural soil in environmentally relevant concentrations, as

  10. Bacterial rheotaxis

    PubMed Central

    Marcos; Fu, Henry C.; Powers, Thomas R.; Stocker, Roman

    2012-01-01

    The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. Using carefully controlled microfluidic flows, we show that rheotaxis also occurs in bacteria. Excellent quantitative agreement between experiments with Bacillus subtilis and a mathematical model reveals that bacterial rheotaxis is a purely physical phenomenon, in contrast to fish rheotaxis but in the same way as sperm rheotaxis. This previously unrecognized bacterial taxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that alters a bacterium's swimming direction. Because this torque is independent of the presence of a nearby surface, bacterial rheotaxis is not limited to the immediate neighborhood of liquid–solid interfaces, but also takes place in the bulk fluid. We predict that rheotaxis occurs in a wide range of bacterial habitats, from the natural environment to the human body, and can interfere with chemotaxis, suggesting that the fitness benefit conferred by bacterial motility may be sharply reduced in some hydrodynamic conditions. PMID:22411815

  11. Modeling vertical carbon flux from zooplankton respiration

    NASA Astrophysics Data System (ADS)

    Packard, Theodore T.; Gómez, May

    2013-03-01

    The transport of carbon from ocean surface waters to the deep sea is a critical factor in calculations of planetary carbon cycling and climate change. This vertical carbon flux is currently thought to support the respiration of all the organisms in the water column below the surface, the respiration of the organisms in the benthos, as well as the carbon lost to deep burial. Accordingly, for conditions where the benthic respiration and the carbon burial are small relative to the respiration in the water column, and where horizontal fluxes are known or negligible, the carbon flux can be calculated by integrating the vertical profile of the water-column plankton respiration rate. Here, this has been done for the zooplankton component of the vertical carbon flux from measurements of zooplankton ETS activity south of the Canary Island Archipelago. From zooplankton ETS activity depth profiles, zooplankton respiration depth profiles were calculated and using the equations for the profiles as models, the epipelagic (3.05 μmol CO2 m-3 h-1), mesopelagic (112.82 nmol CO2 m-3 h-1), and bathypelagic (27.89 nmol CO2 m-3 h-1) zooplankton respiration for these waters were calculated. Then, by integration of the depth-normalized respiration profiles, zooplankton-associated carbon flux profiles below 150 m were calculated. These had an uncertainty of ±40%. At the station level (local regional variation) the variability was ±114% (n = 16). At 150 m and 500 m the average passive carbon flux associated with the zooplankton was 36 (±114%) and 20 (±113%) μmol C m-2 h-1. The carbon transfer efficiency (Teff) from the 150 to the 500 m levels averaged 51 ± 21% and a new metric, the nutrient retention efficiency (NRE), averaged 49 ± 21%. This metric is an index of the efficiency with which nutrients are maintained in the epipelagic zone and is directly related to the respiration in the water column. The carbon flux equation describing the pooled data (n = 16) was 131.14Z-0.292. Using

  12. Extracellular respiration of dimethyl sulfoxide by Shewanella oneidensis strain MR-1.

    PubMed

    Gralnick, Jeffrey A; Vali, Hojatollah; Lies, Douglas P; Newman, Dianne K

    2006-03-21

    Shewanella species are renowned for their respiratory versatility, including their ability to respire poorly soluble substrates by using enzymatic machinery that is localized to the outside of the cell. The ability to engage in "extracellular respiration" to date has focused primarily on respiration of minerals. Here, we identify two gene clusters in Shewanella oneidensis strain MR-1 that each contain homologs of genes required for metal reduction and genes that are predicted to encode dimethyl sulfoxide (DMSO) reductase subunits. Molecular and genetic analyses of these clusters indicate that one (SO1427-SO1432) is required for anaerobic respiration of DMSO. We show that DMSO respiration is an extracellular respiratory process through the analysis of mutants defective in type II secretion, which is required for transporting proteins to the outer membrane in Shewanella. Moreover, immunogold labeling of DMSO reductase subunits reveals that they reside on the outer leaflet of the outer membrane under anaerobic conditions. The extracellular localization of the DMSO reductase in S. oneidensis suggests these organisms may perceive DMSO in the environment as an insoluble compound.

  13. Heavy metal speciation in solid-phase materials from a bacterial sulfate reducing bioreactor using sequential extraction procedure combined with acid volatile sulfide analysis.

    PubMed

    Jong, Tony; Parry, David L

    2004-04-01

    Heavy metal mobility, bioavailability and toxicity depends largely on the chemical form of metals and ultimately determines potential for environmental pollution. For this reason, determining the chemical form of heavy metals and metalloids, immobilized in sludges by biological mediated sulfate reduction, is important to evaluate their mobility and bioavailability. A modified Tessier sequential extraction procedure (SEP), complemented with acid volatile sulfide (AVS) and simultaneous extracted metals (SEM) measurements, were applied to determine the partitioning of five heavy metals (defined as Fe, Ni, Zn and Cu, and the metalloid As) in anoxic solid-phase material (ASM) from an anaerobic, sulfate reducing bioreactor into six operationally defined fractions. These fractions were water soluble, exchangeable, bound to carbonates (acid soluble), bound to Fe-Mn oxides (reducible), bound to organic matter and sulfides (oxidizable) and residual. It was found that the distribution of Fe, Ni, Zn, Cu and As in ASM was strongly influenced by its association with the above solid fractions. The fraction corresponding to organic matter and sulfides appeared to be the most important scavenging phases of As, Fe, Ni, Zn and Cu in ASM (59.8-86.7%). This result was supported by AVS and SEM (Sigma Zn, Ni and Cu) measurements, which indicated that the heavy metals existed overwhelmingly as sulfides in the organic matter and sulfide fraction. A substantial amount of Fe and Ni at 16.4 and 20.1%, respectively, were also present in the carbonate fraction, while an appreciable portion of As (18.3%) and Zn (19.4%) was bound to Fe-Mn oxides. A significant amount of heavy metals was also associated with the residual fraction, ranging from 2.1% for Zn to 18.8% for As. Based on the average total extractable heavy metal (TEHM) values, the concentration of heavy metals in the ASM was in the order of Cu > Ni > Zn > Fe > As. If the mobility and bioavailability of heavy metals are assumed to be

  14. Soil respiration partition and its components in the total agro-ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth; Mary, Bruno

    2013-04-01

    Close to 15% of the Earth's terrestrial surface is used for cropland. In the context of global warming, and acknowledged by the Kyoto Protocol, agricultural soils could be a significant sink for atmospheric CO2. Understanding the factors influencing carbon fluxes of agricultural soils is essential for implementing efficient mitigation practices. Most of the soil respiration modeling studies was carried out in forest ecosystems, but only a few was carried out in agricultural ecosystems. In the study, we evaluated simple formalisms to model soil respiration using wheat data from four contrasting geographical mi-latitude regions. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to soil respiration exchange. These NEE data were used to validate the model. Different biotic and abiotic descriptors were used to model daily soil respiration and its heterotrophic and autotrophic components: soil temperature, soil relative humidity, Gross Primary Productivity (GPP), shoot biomass, crop height, with different formalisms. It was interesting to conclude that using biotic descriptors did not improve the performances of the model. In fact, a combination of abiotic descriptors (soil humidity and soil temperature) allowed significant model formalism to model soil respiration. The simple soil respiration model was used to calculate the heterotrophic and autotrophic source contributions to

  15. Component analysis of respirator user training.

    PubMed

    Harber, Philip; Boumis, Robert J; Su, Jing; Barrett, Sarah; Alongi, Gabriela

    2013-01-01

    Respirators must be properly used to be effective. In an experimental protocol, 145 subjects were trained and then observed donning and doffing respirators. Filtering facepiece and dual cartridge half face mask types were studied. Subjects were then tested for knowledge and for proper performance using video recording analysis. Knowledge tests showed adequate learning, but performance was often poor. Inspection, strap tension (half mask), seal checking, and avoiding mask contact during doffing were particularly problematic. Mask positioning was generally well done. Correlation between knowledge and performance for specific items was generally poor, although there was a weak correlation between overall knowledge and overall performance (rho = 0.32) for the half mask users. Actual unprompted performance as well as knowledge and fit-testing should be assessed for user certification. Respirator design approval should consider users' ability to learn proper technique. PMID:24011265

  16. Influence of the molybdenum cofactor biosynthesis on anaerobic respiration, biofilm formation and motility in Burkholderia thailandensis.

    PubMed

    Andreae, Clio A; Titball, Richard W; Butler, Clive S

    2014-01-01

    Burkholderia thailandensis is closely related to Burkholderia pseudomallei, a bacterial pathogen and the causative agent of melioidosis. B. pseudomallei can survive and persist within a hypoxic environment for up to one year and has been shown to grow anaerobically in the presence of nitrate. Currently, little is known about the role of anaerobic respiration in pathogenesis of melioidosis. Using B. thailandensis as a model, a library of 1344 transposon mutants was created to identify genes required for anaerobic nitrate respiration. One transposon mutant (CA01) was identified with an insertion in BTH_I1704 (moeA), a gene required for the molybdopterin biosynthetic pathway. This pathway is involved in the synthesis of a molybdopterin cofactor required for a variety of molybdoenzymes, including nitrate reductase. Disruption of molybdopterin biosynthesis prevented growth under anaerobic conditions, when using nitrate as the sole terminal electron acceptor. Defects in anaerobic respiration, nitrate reduction, motility and biofilm formation were observed for CA01. Mutant complementation with pDA-17:BTH_I1704 was able to restore anaerobic growth on nitrate, nitrate reductase activity and biofilm formation, but did not restore motility. This study highlights the potential importance of molybdoenzyme-dependent anaerobic respiration in the survival and virulence of B. thailandensis.

  17. Cholera Toxin Production Induced upon Anaerobic Respiration is Suppressed by Glucose Fermentation in Vibrio cholerae.

    PubMed

    Oh, Young Taek; Lee, Kang-Mu; Bari, Wasimul; Kim, Hwa Young; Kim, Hye Jin; Yoon, Sang Sun

    2016-03-01

    The causative agent of pandemic cholera, Vibrio cholerae, infects the anaerobic environment of the human intestine. Production of cholera toxin (CT), a major virulence factor of V. cholerae, is highly induced during anaerobic respiration with trimethylamine N-oxide (TMAO) as an alternative electron acceptor. However, the molecular mechanism of TMAO-stimulated CT production is not fully understood. Herein, we reveal that CT production during anaerobic TMAO respiration is affected by glucose fermentation. When the seventh pandemic V. cholerae O1 strain N16961 was grown with TMAO and additional glucose, CT production was markedly reduced. Furthermore, an N16961 Δcrp mutant, devoid of cyclic AMP receptor protein (CRP), was defective in CT production during growth by anaerobic TMAO respiration, further suggesting a role of glucose metabolism in regulating TMAO-mediated CT production. TMAO reductase activity was noticeably decreased when grown together with glucose or by mutation of the crp gene. A CRP binding region was identified in the promoter region of the torD gene, which encodes a structural subunit of the TMAO reductase. Gel shift assays further confirmed the binding of purified CRP to the torD promoter sequence. Together, our results suggest that the bacterial ability to respire using TMAO is controlled by CRP, whose activity is dependent on glucose availability. Our results reveal a novel mechanism for the regulation of major virulence factor production by V. cholerae under anaerobic growth conditions.

  18. Cholera Toxin Production Induced upon Anaerobic Respiration is Suppressed by Glucose Fermentation in Vibrio cholerae.

    PubMed

    Oh, Young Taek; Lee, Kang-Mu; Bari, Wasimul; Kim, Hwa Young; Kim, Hye Jin; Yoon, Sang Sun

    2016-03-01

    The causative agent of pandemic cholera, Vibrio cholerae, infects the anaerobic environment of the human intestine. Production of cholera toxin (CT), a major virulence factor of V. cholerae, is highly induced during anaerobic respiration with trimethylamine N-oxide (TMAO) as an alternative electron acceptor. However, the molecular mechanism of TMAO-stimulated CT production is not fully understood. Herein, we reveal that CT production during anaerobic TMAO respiration is affected by glucose fermentation. When the seventh pandemic V. cholerae O1 strain N16961 was grown with TMAO and additional glucose, CT production was markedly reduced. Furthermore, an N16961 Δcrp mutant, devoid of cyclic AMP receptor protein (CRP), was defective in CT production during growth by anaerobic TMAO respiration, further suggesting a role of glucose metabolism in regulating TMAO-mediated CT production. TMAO reductase activity was noticeably decreased when grown together with glucose or by mutation of the crp gene. A CRP binding region was identified in the promoter region of the torD gene, which encodes a structural subunit of the TMAO reductase. Gel shift assays further confirmed the binding of purified CRP to the torD promoter sequence. Together, our results suggest that the bacterial ability to respire using TMAO is controlled by CRP, whose activity is dependent on glucose availability. Our results reveal a novel mechanism for the regulation of major virulence factor production by V. cholerae under anaerobic growth conditions. PMID:26718467

  19. Microbial respiration and trophic regimes in the Northern Adriatic Sea (Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    La Ferla, Rosabruna; Azzaro, Maurizio; Maimone, Giovanna

    2006-08-01

    Remineralization in the Northern Adriatic Sea has been examined by studying the respiratory rates, through electron transport system activity, in four systems identified on the basis of different salinities, caused by riverine outflows, and different productivity regimes measured by apparent oxygen utilization. The sea waters influenced by river discharges were characterized by high respiratory activity while in fully marine waters respiration fell close to the typical value for the surface pelagic Mediterranean waters. A speculative approach to quantify the trophic balance in the examined sub-systems was adopted and the following ratios were computed: Primary Production/Respiration (PP/R); Primary Production/(Bacterial Production + Respiration) [PP/(BP + R)]; (Dissolved Organic Carbon + Particulate Organic Carbon)/Respiration [(DOC + POC)/R], using the data generated at the same time from the same multidisciplinary cruises. High variability of these metabolic ratios in the described subsystems occurred, so that shifting autotrophy and heterotrophy patterns through summer-winter and cross-productivity front trends occurred. Episodic heterotrophy has been found to happen in the North Adriatic Sea, although this is normally considered a productive ecosystem.

  20. Impacts of Shewanella oneidensis c-type cytochromes on aerobic and anaerobic respiration.

    PubMed

    Gao, Haichun; Barua, Soumitra; Liang, Yili; Wu, Lin; Dong, Yangyang; Reed, Samantha; Chen, Jingrong; Culley, Dave; Kennedy, David; Yang, Yunfeng; He, Zhili; Nealson, Kenneth H; Fredrickson, James K; Tiedje, James M; Romine, Margaret; Zhou, Jizhong

    2010-07-01

    Shewanella are renowned for their ability to utilize a wide range of electron acceptors (EA) for respiration, which has been partially accredited to the presence of a large number of the c-type cytochromes. To investigate the involvement of c-type cytochrome proteins in aerobic and anaerobic respiration of Shewanella oneidensis Mr -1, 36 in-frame deletion mutants, among possible 41 predicted, c-type cytochrome genes were obtained. The potential involvement of each individual c-type cytochrome in the reduction of a variety of EAs was assessed individually as well as in competition experiments. While results on the well-studied c-type cytochromes CymA(SO4591) and MtrC(SO1778) were consistent with previous findings, collective observations were very interesting: the responses of S. oneidensis Mr -1 to low and highly toxic metals appeared to be significantly different; CcoO, CcoP and PetC, proteins involved in aerobic respiration in various organisms, played critical roles in both aerobic and anaerobic respiration with highly toxic metals as EA. In addition, these studies also suggested that an uncharacterized c-type cytochrome (SO4047) may be important to both aerobiosis and anaerobiosis.

  1. Impacts of Shewanella oneidensis c-type cytochromes on aerobic and anaerobic respiration

    SciTech Connect

    Gao, Haichun; Barua, Soumitra; Liang, Yili; Wu, Lianming; Dong, Yangyang; Reed, Samantha B.; Chen, Jingrong; Culley, David E.; Kennedy, David W.; Yang, Yunfeng; He, Zhili; Nealson, Kenneth H.; Fredrickson, Jim K.; Tiedje, James M.; Romine, Margaret F.; Zhou, Jizhong

    2010-06-24

    Shewanella are renowned for their ability to utilize a wide range of electron acceptors (EA) for respiration, which has been partially accredited to the presence of a large number of the c-type cytochromes. To investigate the involvement of c-type cytochrome proteins in aerobic and anaerobic respiration of Shewanella oneidensis Mr -1, 36 in-frame deletion mutants, among possible 41 predicted, c-type cytochrome genes were obtained. The potential involvement of each individual c-type cytochrome in the reduction of a variety of EAs was assessed individually as well as in competition experiments. While results on the wellstudied c-type cytochromes CymA(SO4591) and MtrC(SO1778) were consistent with previous findings, collective observations were very interesting: the responses of S. oneidensis Mr -1 to low and highly toxic metals appeared to be significantly different; CcoO, CcoP and PetC, proteins involved in aerobic respiration in various organisms, played critical roles in both aerobic and anaerobic respiration with highly toxic metals as EA. In addition, these studies also suggested that an uncharacterized c-type cytochrome (SO4047) may be important to both aerobiosis and anaerobiosis.

  2. Impacts of Shewanella oneidensis c‐type cytochromes on aerobic and anaerobic respiration

    PubMed Central

    Gao, Haichun; Barua, Soumitra; Liang, Yili; Wu, Lin; Dong, Yangyang; Reed, Samantha; Chen, Jingrong; Culley, Dave; Kennedy, David; Yang, Yunfeng; He, Zhili; Nealson, Kenneth H.; Fredrickson, James K.; Tiedje, James M.; Romine, Margaret; Zhou, Jizhong

    2010-01-01

    Summary Shewanella are renowned for their ability to utilize a wide range of electron acceptors (EA) for respiration, which has been partially accredited to the presence of a large number of the c‐type cytochromes. To investigate the involvement of c‐type cytochrome proteins in aerobic and anaerobic respiration of Shewanella oneidensis Mr ‐1, 36 in‐frame deletion mutants, among possible 41 predicted, c‐type cytochrome genes were obtained. The potential involvement of each individual c‐type cytochrome in the reduction of a variety of EAs was assessed individually as well as in competition experiments. While results on the well‐studied c‐type cytochromes CymA(SO4591) and MtrC(SO1778) were consistent with previous findings, collective observations were very interesting: the responses of S. oneidensis Mr ‐1 to low and highly toxic metals appeared to be significantly different; CcoO, CcoP and PetC, proteins involved in aerobic respiration in various organisms, played critical roles in both aerobic and anaerobic respiration with highly toxic metals as EA. In addition, these studies also suggested that an uncharacterized c‐type cytochrome (SO4047) may be important to both aerobiosis and anaerobiosis. PMID:21255343

  3. Using half-facepiece respirators for H1N1.

    PubMed

    Larson, Scott

    2009-11-01

    A respirator is a device designed to help provide the wearer with respiratory protection against inhalation of airborne contaminants. Increasing the filtration level of a particle respirator does not increase the respirator's ability to reduce a user's exposure to contaminants. The APF of a respirator, which is affected by the respirator style, determines the potential for exposure reduction. Surgical masks that are not approved as filtering facepiece half-mask respirators do not have an APF and should not be used for reducing workers' exposures to particles in the air. PMID:19927872

  4. Complementarity among plant growth promoting traits in rhizospheric bacterial communities promotes plant growth.

    PubMed

    Singh, Mangal; Awasthi, Ashutosh; Soni, Sumit K; Singh, Rakshapal; Verma, Rajesh K; Kalra, Alok

    2015-10-27

    An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants.

  5. Complementarity among plant growth promoting traits in rhizospheric bacterial communities promotes plant growth

    PubMed Central

    Singh, Mangal; Awasthi, Ashutosh; Soni, Sumit K.; Singh, Rakshapal; Verma, Rajesh K.; Kalra, Alok

    2015-01-01

    An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants. PMID:26503744

  6. BOREAS TE-2 Root Respiration Data

    NASA Technical Reports Server (NTRS)

    Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set includes means of tree root respiration measurements on roots having diameters ranging from 0 to 2 mm conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  7. BOREAS TE-2 Continuous Wood Respiration Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Ryan, Michael G.; Lavigne, Michael

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of wood respiration measured continuously (about once per hour) in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  8. BOREAS TE-2 Wood Respiration Data

    NASA Technical Reports Server (NTRS)

    Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of wood respiration conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  9. BOREAS TE-2 Foliage Respiration Data

    NASA Technical Reports Server (NTRS)

    Ryan, Michael G.; Hall, Forrest G. (Editor); Lavigne, Michael; Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of foliar respiration conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  10. Changes in soil respiration components and their specific respiration along three successional forests in the subtropics

    DOE PAGES

    Han, Tianfeng; Liu, Juxiu; Wang, Gangsheng; Huang, Wenjuan; Zhou, Guoyi

    2016-01-16

    1.Understanding how soil respiration components change with forest succession is critical for modelling and predicting soil carbon (C) processes and its sequestration below-ground. The specific respiration (a ratio of respiration to biomass) is increasingly being used as an indicator of forest succession conceptually based on Odum's theory of ecosystem development. However, the hypothesis that specific soil respiration declines with forest succession remains largely untested. 2.We used a trenching method to partition soil respiration into heterotrophic respiration and autotrophic respiration (RH and RA) and then evaluated the specific RH and specific RA in three successional forests in subtropical China. 3.Our resultsmore » showed a clear seasonality in the influence of forest succession on RH, with no significant differences among the three forests in the dry season but a higher value in the old-growth forest than the other two forests in the wet season. RA in the old-growth forest tended to be the highest among the three forests. Both the specific RH and specific RA decreased with the progressive maturity of three forests. 4.Lastly, our results highlight the importance of forest succession in determining the variation of RH in different seasons. With forest succession, soil microbes and plant roots become more efficient to conserve C resources, which would result in a greater proportion of C retained in soils.« less

  11. Effective capture of respirable sized particulates using electrostatic precipitator technology

    SciTech Connect

    Parker, K.R.; Sanyal, A.

    1999-11-01

    The electrostatic precipitator widely used for the prevention of particulate pollution from industrial sources, can also be effective, when correctly sized and operated, for the collection of respirable fine particulates. That is, those below some 2 micron diameter, particularly of heavy metals which tend to be cumulative and hence injurious to health. Following a review of the basic principles of operation of electrostatic precipitators, specifically addressed to the capture of fine particulates, an outline of the various types of equipment used for collecting solid and liquid (mist) particulates will be discussed. Finally some typical precipitator applications will be illustrated, together with suggestions as to how efficiencies can be further increased to meet compliance with any potential future changes in legislation.

  12. Facial hair policy in a respirator program

    SciTech Connect

    Steinmeyer, P.R. )

    1989-10-01

    In this paper the prohibition against facial hair for respirator users is explored. Reasons for the prohibition are given, along with suggestions for establishing or reviewing a policy. Recommendations are given for properly wording a facial hair policy, and the issue of facial hair on female workers is also addressed.

  13. Temperature, Pulse, and Respiration. Learning Activity Package.

    ERIC Educational Resources Information Center

    Runge, Lillian

    This learning activity package on temperature, pulse, and respiration is one of a series of 12 titles developed for use in health occupations education programs. Materials in the package include objectives, a list of materials needed, information sheets, reviews (self evaluations) of portions of the content, and answers to reviews. These topics…

  14. Estimating Canopy Dark Respiration for Crop Models

    NASA Technical Reports Server (NTRS)

    Monje Mejia, Oscar Alberto

    2014-01-01

    Crop production is obtained from accurate estimates of daily carbon gain.Canopy gross photosynthesis (Pgross) can be estimated from biochemical models of photosynthesis using sun and shaded leaf portions and the amount of intercepted photosyntheticallyactive radiation (PAR).In turn, canopy daily net carbon gain can be estimated from canopy daily gross photosynthesis when canopy dark respiration (Rd) is known.

  15. Respiration patterns of resting wasps (Vespula sp.)

    PubMed Central

    Käfer, Helmut; Kovac, Helmut; Stabentheiner, Anton

    2013-01-01

    We investigated the respiration patterns of wasps (Vespula sp.) in their viable temperature range (2.9–42.4 °C) by measuring CO2 production and locomotor and endothermic activity. Wasps showed cycles of an interburst–burst type at low ambient temperatures (Ta < 5 °C) or typical discontinuous gas exchange patterns with closed, flutter and open phases. At high Ta of >31 °C, CO2 emission became cyclic. With rising Ta they enhanced CO2-emission primarily by an exponential increase in respiration frequency, from 2.6 mHz at 4.7 °C to 74 mHz at 39.7 °C. In the same range of Ta CO2 release per cycle decreased from 38.9 to 26.4 μl g−1 cycle−1. A comparison of wasps with other insects showed that they are among the insects with a low respiratory frequency at a given resting metabolic rate (RMR), and a relatively flat increase of respiratory frequency with RMR. CO2 emission was always accompanied by abdominal respiration movements in all open phases and in 71.4% of the flutter phases, often accompanied by body movements. Results suggest that resting wasps gain their highly efficient gas exchange to a considerable extent via the length and type of respiration movements. PMID:23399474

  16. Development of conformal respirator monitoring technology

    SciTech Connect

    Shonka, J.J.; Weismann, J.J.; Logan, R.J.

    1997-04-01

    This report summarizes the results of a Small Business Innovative Research Phase II project to develop a modular, surface conforming respirator monitor to improve upon the manual survey techniques presently used by the nuclear industry. Research was performed with plastic scintillator and gas proportional modules in an effort to find the most conducive geometry for a surface conformal, position sensitive monitor. The respirator monitor prototype developed is a computer controlled, position-sensitive detection system employing 56 modular proportional counters mounted in molds conforming to the inner and outer surfaces of a commonly used respirator (Scott Model 801450-40). The molds are housed in separate enclosures and hinged to create a {open_quotes}waffle-iron{close_quotes} effect so that the closed monitor will simultaneously survey both surfaces of the respirator. The proportional counter prototype was also designed to incorporate Shonka Research Associates previously developed charge-division electronics. This research provided valuable experience into pixellated position sensitive detection systems. The technology developed can be adapted to other monitoring applications where there is a need for deployment of many traditional radiation detectors.

  17. 42 CFR 84.1130 - Respirators; description.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying... reaction with sorbent material in the canister. (c) Pesticide respirators, including all completely...) Front-mounted or back-mounted gas masks; (2) Chin-style gas mask; (3) Chemical cartridge; (4)...

  18. 42 CFR 84.1130 - Respirators; description.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying... reaction with sorbent material in the canister. (c) Pesticide respirators, including all completely...) Front-mounted or back-mounted gas masks; (2) Chin-style gas mask; (3) Chemical cartridge; (4)...

  19. 42 CFR 84.1130 - Respirators; description.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying... reaction with sorbent material in the canister. (c) Pesticide respirators, including all completely...) Front-mounted or back-mounted gas masks; (2) Chin-style gas mask; (3) Chemical cartridge; (4)...

  20. 42 CFR 84.1130 - Respirators; description.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying... reaction with sorbent material in the canister. (c) Pesticide respirators, including all completely...) Front-mounted or back-mounted gas masks; (2) Chin-style gas mask; (3) Chemical cartridge; (4)...

  1. 42 CFR 84.1130 - Respirators; description.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying... reaction with sorbent material in the canister. (c) Pesticide respirators, including all completely...) Front-mounted or back-mounted gas masks; (2) Chin-style gas mask; (3) Chemical cartridge; (4)...

  2. Microbial iron respiration: impacts on corrosion processes.

    PubMed

    Lee, A K; Newman, D K

    2003-08-01

    In this review, we focus on how biofilms comprising iron-respiring bacteria influence steel corrosion. Specifically, we discuss how biofilm growth can affect the chemistry of the environment around the steel at different stages of biofilm development, under static or dynamic fluid regimes. We suggest that a mechanistic understanding of the role of biofilm metabolic activity may facilitate corrosion control.

  3. Respiration patterns of resting wasps (Vespula sp.).

    PubMed

    Käfer, Helmut; Kovac, Helmut; Stabentheiner, Anton

    2013-04-01

    We investigated the respiration patterns of wasps (Vespula sp.) in their viable temperature range (2.9-42.4°C) by measuring CO2 production and locomotor and endothermic activity. Wasps showed cycles of an interburst-burst type at low ambient temperatures (Ta<5°C) or typical discontinuous gas exchange patterns with closed, flutter and open phases. At high Ta of >31°C, CO2 emission became cyclic. With rising Ta they enhanced CO2-emission primarily by an exponential increase in respiration frequency, from 2.6 mHz at 4.7°C to 74 mHz at 39.7°C. In the same range of Ta CO2 release per cycle decreased from 38.9 to 26.4 μl g(-1)cycle(-1). A comparison of wasps with other insects showed that they are among the insects with a low respiratory frequency at a given resting metabolic rate (RMR), and a relatively flat increase of respiratory frequency with RMR. CO2 emission was always accompanied by abdominal respiration movements in all open phases and in 71.4% of the flutter phases, often accompanied by body movements. Results suggest that resting wasps gain their highly efficient gas exchange to a considerable extent via the length and type of respiration movements.

  4. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    NASA Astrophysics Data System (ADS)

    Wing, Boswell A.; Halevy, Itay

    2014-12-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2Sṡcell-1ṡd-1).

  5. Effects of an oil spill on benthic community production and respiration on subtropical intertidal sandflats.

    PubMed

    Lee, Li-Hua; Lin, Hsing-Juh

    2013-08-15

    This study determined effects of an oil spill on subtropical benthic community production and respiration by monitoring CO2 fluxes in benthic chambers on intertidal sandflats during emersion before and after an accidental spill. The oil spill decreased sediment chlorophyll a concentrations, altered benthic macrofaunal community, and affected ecological functioning by suppressing or even stopping microalgal production, increasing bacterial respiration, and causing a shift from an autotrophic system to a heterotrophic system. Effects of the oil spill on the macrofauna were more severe than on benthic microalgae, and affected sedentary infauna more than motile epifauna. Despite the oil spill's impact on the benthic community and carbon metabolism, the affected area appeared to return to normal in about 23 days. Our results suggest that the prompt response of benthic metabolism to exposure to petroleum hydrocarbons can serve as a useful indicator of the impact of an oil spill.

  6. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    PubMed Central

    Wing, Boswell A.; Halevy, Itay

    2014-01-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2S⋅cell−1⋅d−1). PMID:25362045

  7. How to Properly Put On, Take Off a Disposable Respirator

    MedlinePlus

    ... the nose piece at your fingertips. Checking Your Seal 2 Cup the respirator in your hand allowing ... quick breath in to check whether the respirator seals tightly to the face. Place both hands completely ...

  8. Factors Controlling Respiration Rates and Respired Carbon Dioxide Signatures in Riverine Ecosystems of the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Ellis, E. E.; Richey, J. E.; Aufdenkampe, A. K.; Quay, P. D.; Krusche, A. V.; Alin, S. R.

    2006-12-01

    This study examined the processes controlling respiration rates observed in streams and rivers throughout the Amazon basin during the dry season by substituting spatial coverage for experimental manipulation. Throughout the Brazilian states of Amazonas and Acre, respiration rates ranged from 0.066 to 1.45 μM/hr of O2 consumed. In situ respiration was positively correlated with pH (r2=0.60), with pH values ranging from 3.95 to 8.57. Although the concentration of bulk size fractions of organic matter(dissolved organic carbon (DOC), fine particulate organic carbon, and coarse particulate organic carbon) were uncorrelated with both pH and respiration, respiration was positively correlated with the percentage of DOC that was less than 5 kDa as determined by centrifuge ultrafiltration (r2=0.52). No correlation was observed for the less than 100 kDa fraction. Further, pH was also correlated with the percentage of DOC in the <5 kDa fraction (r2=0.86), as the <5 kDa fraction increased from 34% in acidic blackwater streams to 91% in more basic whitewater rivers. These results suggest that low molecular weight organic matter (LMWOM, <5 kDa) is labile and supports higher respiration rates as compared to high molecular weight organic matter, and that pH may control the size distribution of dissolved organic matter. Further, at high pH sites with high respiration rates, net primary production ranged from 3.54 to 13.5 μM/hr of O2 produced. These rates suggest that higher pH sites are dominated by in situ production, resulting in high yields of LMWOM, which is rapidly consumed during the dry season. The 13C of respired CO2 was monitored during bottle incubations to characterize the source of organic matter being respired. Values ranged from -15.2 to -27.0‰, similar to the 13C of DIC at each site, indicating that respiration is a key process controlling the δ13C of the DIC. Furthermore, there is a positive correlation between the δ13C of respired CO2 and respiration rate (r2

  9. [Regulation of respiration in assisted ventilation].

    PubMed

    Waurick, S; König, F

    1984-02-01

    Based on knowledge of the control of external respiration, the physiological reactions are discussed which should be evoked proprioceptively and chemoreceptively by an assisting respirator's disturbances of spontaneous breathing movements. The following possible states are discriminated: 1. "no adaption": the respiratory motor system does not remain passive during the machine's stroke; 2. "passive adaption": the respiratory motor system remains passive during the respirator's stroke; to changes of the blood gas-status, only the breathing frequency responds, but in just the same manner as during spontaneous ventilation; 3. "active adaption": the ventilatory motor apparatus remains passive during the respirator's operation; changes of the blood gases are responded to by the breathing frequency only, but in a manner different to spontaneous breathing and which compensates for the invariability of the fixed stroke-volume. - Related to these 3 states, consequences concerning the efficiency of chemical respiratory control can be derived which should reveal themselves during experimental manipulation of the blood gas partial pressures. Accordingly, the CO2-response curves of minute ventilation, breathing frequency and tidal-volume generated in 9 healthy, awake and cooperative subjects during spontaneous breathing and assisted (stroke-volume controlled) respiration with gas mixtures of 0, 3 and 6% CO2 were investigated and compared. (In each subject assisted ventilation with 2 or 3 different stroke-volumes was performed. The smallest stroke-volume equalled the medium tidal-volume of spontaneous ventilation. Every stroke-volume produced its particular CO2-response curve). Hence it follows that with assisted ventilation, using a stroke-volume larger than the spontaneous tidal-volume, the subjects maintain a state between "passive" and "active adaption".(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Evaluation of the efficacy of a bacterial consortium for the removal of color, reduction of heavy metals, and toxicity from textile dye effluent.

    PubMed

    Jadhav, J P; Kalyani, D C; Telke, A A; Phugare, S S; Govindwar, S P

    2010-01-01

    A microbial consortium DAS consisting three bacterial sp. originally obtained from dye contaminated sites of Solapur, India was selected because it was capable of decolorizing textile effluent and dye faster than the individual bacteria under static conditions. Identification of the isolates by 16S rRNA techniques revealed the isolates to be Pseudomonas species. The concerted metabolic activity of these isolates led to complete decolorization of textile effluent as well as Reactive Orange 16 (100 mg l(-1)) within 48-h at pH 7 and 30 degrees C. Studies involving Reactive Orange 16 (RO16) dye were carried with the bacterial consortium DAS to elucidate the mechanism of biodegradation. Induction of the laccase and reductase enzyme during RO16 decolorization indicated their role in biodegradation. The biodegradation of RO16 was monitored by using IR spectroscopy, HPLC and GC-MS analysis. Cytotoxicity, genotoxicity and phytotoxicity studies carried out before and after decolorization of the textile effluent revealed the nontoxic nature of the biotreated sample.

  11. [Stem respiration of Pinus koraiensis in Changbai Mountains].

    PubMed

    Wang, Miao; Ji, Lanzhu; Li, Qiurong; Xiao, Dongmei; Liu, Hailiang

    2005-01-01

    In this paper, soil respiration chamber, a simple and precise method, was used to measure the stem respiration of trees. LI-6400-09 respiration chamber serving as a system is usually used in soil respiration, but we made polyvinyl chloride (PVC) collar and fixed it on the stem surface to measure the stem respiration. From May to October 2003, the stem respiration of Pinus koraiensis, the dominant tree species in Changbai Mountain, was measured in different time and different places using this technique. Meanwhile, the temperatures in the stems and in the forests were measured. The results showed that the stem respiration rate had a remarkably seasonal tendency with a single peak, the maximum was in August and the minimum was in February. The stem respiration rate had an exponential relationship with stem temperature, and the curve exponential regressions for stem respiration rate and temperature factor of trees with big DBH were better than those with small DBH. The stem respiration in different DBH trees was higher in the south stem face than that in the north stem face, and the variance of respiration rate between south and north decreased with a decrease of DBH trees. During the growing season from May to October, the average maintenance respiration accounted for 63.63% in different DBH trees, and the maintenance respiration contribution to total respiratory consumption increased with increasing DBH, which was 66.76, 73.29% and 50.84%, respectively. The stem respiration Q10 values ranged from 2.56-3.32 in different DBH of trees, and the seasonal tendency for stem R, and Rm in different DBH of trees was obtained by using respiration Q10. Therefore, the differences between different parts of stem and different DBH of trees should be considered in estimating the respiration model in ecosystem. PMID:15852948

  12. A glacier respires: Quantifying the distribution and respiration CO2 flux of cryoconite across an entire Arctic supraglacial ecosystem

    NASA Astrophysics Data System (ADS)

    Hodson, Andy; Anesio, Alexandre M.; Ng, Felix; Watson, Rory; Quirk, Joe; Irvine-Fynn, Tristram; Dye, Adrian; Clark, Chris; McCloy, Patrick; Kohler, Jack; Sattler, Birgit

    2007-12-01

    This paper quantifies the mass distribution of cryoconite at the glacier scale using photographic surveys conducted either at ground level, or at 20 m elevation using a novel uninhabited aerial vehicle (UAV). Image acquisition allowed three key deposits to be quantified: cryoconite holes, cryoconite in streams ("stream cryoconite"), and dispersed cryoconite granules (detectable only in the ground-based images). Cryoconite was found all over the snow-free parts of the glacier in one or more of these forms, covering about 0.42% (4600 kg km-2 dry weight) as holes and stream cryoconite deposits (>0.25 cm2 and thus visible in the UAV images), or 1% (10600 kg km-2) when smaller dispersed granules were included (using the ground images). No spatial patterns in the distribution of cryoconite cover were apparent, although cryoconite holes were far more common than stream cryoconite at high altitude due to lower melt rates. Measurements of respiration and bacterial carbon production estimated from in situ incubations of cryoconite-water mixtures indicated rates of 1.174 ± 0.182 (1 standard deviation) and 0.040 ± 0.019 μg C g-1 h-1, respectively. The respiration measurements then yielded glacier-wide CO2 fluxes for 1998 and 2000 of 6.3 and 5.1 kg C km-2 a-1 when the loci and duration of activity were defined using the UAV images and a degree day model, respectively. These fluxes increased to 14 and 12 kg C km-2 a-1 when the dispersed cryoconite detected in the ground-based images were also considered. The measurements therefore show that cryoconite ecosystems clearly have the capacity to impact upon carbon cycling in glacial environments.

  13. [Bacterial vaginosis].

    PubMed

    Romero Herrero, Daniel; Andreu Domingo, Antonia

    2016-07-01

    Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. PMID:27474242

  14. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Pesticide respirators; performance requirements... DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1156 Pesticide respirators; performance requirements;...

  15. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Pesticide respirators; performance requirements... DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1156 Pesticide respirators; performance requirements;...

  16. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic ECG/respirator synchronizer. 892.1970... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic ECG/respirator synchronizer. (a) Identification. A radiographic ECG/respirator synchronizer is a device intended to be used...

  17. 20 CFR 718.303 - Death from a respirable disease.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Death from a respirable disease. 718.303... Death from a respirable disease. (a)(1) If a deceased miner was employed for ten or more years in one or more coal mines and died from a respirable disease, there shall be a rebuttable presumption that his...

  18. 20 CFR 718.303 - Death from a respirable disease.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false Death from a respirable disease. 718.303... Death from a respirable disease. (a)(1) If a deceased miner was employed for ten or more years in one or more coal mines and died from a respirable disease, there shall be a rebuttable presumption that his...

  19. 20 CFR 718.303 - Death from a respirable disease.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false Death from a respirable disease. 718.303... Death from a respirable disease. (a)(1) If a deceased miner was employed for ten or more years in one or more coal mines and died from a respirable disease, there shall be a rebuttable presumption that his...

  20. 20 CFR 410.462 - Presumption relating to respirable disease.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Presumption relating to respirable disease... Pneumoconiosis § 410.462 Presumption relating to respirable disease. (a) Even though the existence of... was employed for 10 years or more in the Nation's coal mines and died from a respirable disease,...

  1. 20 CFR 718.303 - Death from a respirable disease.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Death from a respirable disease. 718.303... from a respirable disease. (a)(1) If a deceased miner was employed for ten or more years in one or more coal mines and died from a respirable disease, there shall be a rebuttable presumption that his or...

  2. 20 CFR 410.462 - Presumption relating to respirable disease.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Presumption relating to respirable disease... Pneumoconiosis § 410.462 Presumption relating to respirable disease. (a) Even though the existence of... was employed for 10 years or more in the Nation's coal mines and died from a respirable disease,...

  3. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Pesticide respirators; performance requirements... DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1156 Pesticide respirators; performance requirements;...

  4. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Pesticide respirators; performance requirements... DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1156 Pesticide respirators; performance requirements;...

  5. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Pesticide respirators; performance requirements... DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1156 Pesticide respirators; performance requirements;...

  6. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Respirator containers; minimum requirements. 84..., Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided...

  7. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic ECG/respirator synchronizer. 892.1970... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic ECG/respirator synchronizer. (a) Identification. A radiographic ECG/respirator synchronizer is a device intended to be used...

  8. Contribution of silver nanoparticles to extend Salmonella typhimurium growth under various respiration regimes.

    PubMed

    Hidouri, Slah; Yohmes, Mannoubia Ben; Landoulsi, Ahmed

    2016-10-01

    Living cells interact with different forms of metal; the resulted biochemical alteration depends on the dose. Over an average dose in ionic form, metals interact with respiration processes at various levels, and it induces oxidative stress by shifting the whole oxydoreduction equilibrium. To correct the toxicity, cell develops different ways to cancel the effect of the exceeded charges, and it reduces the ion to get a more stable form. In the case of nanoparticles, the reactivity of surface has been enhanced that can alter the biological mechanisms; the cell may develop different strategies to minimize this reactivity. The current study is focused on the pursuing of cell behavior regarding the presence of nanoparticles and their associated metals. Nanoparticles have been synthesized using bio-reducing agents and then were structurally characterized using X-ray diffraction, UV-Vis, and infra-red spectroscopy. The oxydoreduction flexibility of the post-synthesis modified nanoparticles was tested in vitro. Interactions with cells were done using Salmonella under various respiration conditions. The final results show the possible correction of oxidative stress effects and the recuperation of respiration.

  9. Contribution of silver nanoparticles to extend Salmonella typhimurium growth under various respiration regimes.

    PubMed

    Hidouri, Slah; Yohmes, Mannoubia Ben; Landoulsi, Ahmed

    2016-10-01

    Living cells interact with different forms of metal; the resulted biochemical alteration depends on the dose. Over an average dose in ionic form, metals interact with respiration processes at various levels, and it induces oxidative stress by shifting the whole oxydoreduction equilibrium. To correct the toxicity, cell develops different ways to cancel the effect of the exceeded charges, and it reduces the ion to get a more stable form. In the case of nanoparticles, the reactivity of surface has been enhanced that can alter the biological mechanisms; the cell may develop different strategies to minimize this reactivity. The current study is focused on the pursuing of cell behavior regarding the presence of nanoparticles and their associated metals. Nanoparticles have been synthesized using bio-reducing agents and then were structurally characterized using X-ray diffraction, UV-Vis, and infra-red spectroscopy. The oxydoreduction flexibility of the post-synthesis modified nanoparticles was tested in vitro. Interactions with cells were done using Salmonella under various respiration conditions. The final results show the possible correction of oxidative stress effects and the recuperation of respiration. PMID:27287758

  10. Assessment of heavy metal and bacterial pollution in coastal aquifers from SIPCOT industrial zones, Gulf of Mannar, South Coast of Tamil Nadu, India

    NASA Astrophysics Data System (ADS)

    Selvam, S.; Antony Ravindran, A.; Venkatramanan, S.; Singaraja, C.

    2015-06-01

    Heavy metals and microbiological contamination were investigated in groundwater in the industrial and coastal city of Thoothukudi. The main sources of drinking water in this area are water bores which are dug up to the depth of 10-50 m in almost every house. A number of chemical and pharmaceutical industries have been established since past three decades. Effluents from these industries are reportedly being directly discharged onto surrounding land, irrigation fields and surface water bodies forming point and non-point sources of contamination for groundwater in the study area. The study consists of the determination of physico-chemical properties, trace metals, heavy metals and microbiological quality of drinking water. Heavy metals were analysed using Inductively Coupled Plasma Mass Spectrometry and compared with the (WHO in Guidelines for drinking water quality, 2004) standards. The organic contamination was detected in terms of most probable number (MPN) test in order to find out faecal coliforms that were identified through biochemical tests. A comparison of the results of groundwater samples with WHO guidelines reveals that most of the groundwater samples are heavily contaminated with heavy metals like arsenic, selenium, lead, boron, aluminium, iron and vanadium. The selenium level was higher than 0.01 mg/l in 82 % of the study area and the arsenic concentration exceeded 0.01 mg/l in 42 % of the area. The results reveal that heavy metal contamination in the area is mainly due to the discharge of effluents from copper industries, alkali chemical industry, fertiliser industry, thermal power plant and sea food industries. The results showed that there are pollutions for the groundwater, and the total Coliform means values ranged from 0.6-145 MPN ml-1, faecal Coliform ranged from 2.2-143 MPN ml-1, Escherichia coli ranged from 0.9 to 40 MPN ml-1 and faecal streptococci ranged from 10-9.20 × 102 CFU ml-1. The coastal regions are highly contaminated with total

  11. Tryptophan Cu(I)–π interaction fine-tunes the metal binding properties of the bacterial metallochaperone CusF

    PubMed Central

    Loftin, Isabell R.; McEvoy, Megan M.; Blackburn, Ninian J.

    2009-01-01

    The periplasmic metallochaperone CusF coordinates Cu(I) and Ag(I) through a unique site consisting of a Met2His motif as well as a Cu(I)–π interaction between a nearby tryptophan, W44, and the metal ion. Through mutational analyses we investigate here the role that W44 in CusF plays in metal coordination. Nuclear magnetic resonance spectra show that the specificity of CusF for Cu(I) and Ag(I) is not altered by mutation of W44. X-ray absorption studies reveal that W44 protects the bound Cu(I) from oxidation as well as from adventitious ligands. Competition assays demonstrate that W44 does not significantly contribute to the affinity of CusF for metal, but that substitution of W44 by methionine, which forms a fourth Cu(I) ligand, substantially increases the affinity. These studies indicate that W44 is important in maintaining a moderate-affinity and solvent-shielded three-coordinate environment for Cu(I), which has implications for the function of CusF as a metallochaperone. PMID:19381697

  12. Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

    NASA Astrophysics Data System (ADS)

    Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

    2016-04-01

    Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and

  13. Standing stocks, production, and respiration of phytoplankton and heterotrophic bacteria in the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.; Hill, Victoria; Cottrell, Matthew T.; Gradinger, Rolf; Malmstrom, Rex R.; Parker, Alexander

    2009-08-01

    Standing stocks and production rates for phytoplankton and heterotrophic bacteria were examined during four expeditions in the western Arctic Ocean (Chukchi Sea and Canada Basin) in the spring and summer of 2002 and 2004. Rates of primary production (PP) and bacterial production (BP) were higher in the summer than in spring and in shelf waters than in the basin. Most surprisingly, PP was 3-fold higher in 2004 than in 2002; ice-corrected rates were 1581 and 458 mg C m -2 d -1, respectively, for the entire region. The difference between years was mainly due to low ice coverage in the summer of 2004. The spatial and temporal variation in PP led to comparable variation in BP. Although temperature explained as much variability in BP as did PP or phytoplankton biomass, there was no relationship between temperature and bacterial growth rates above about 0 °C. The average ratio of BP to PP was 0.06 and 0.79 when ice-corrected PP rates were greater than and less than 100 mg C m -2 d -1, respectively; the overall average was 0.34. Bacteria accounted for a highly variable fraction of total respiration, from 3% to over 60% with a mean of 25%. Likewise, the fraction of PP consumed by bacterial respiration, when calculated from growth efficiency (average of 6.9%) and BP estimates, varied greatly over time and space (7% to >500%). The apparent uncoupling between respiration and PP has several implications for carbon export and storage in the western Arctic Ocean.

  14. Differences in the Effect of Coal Pile Runoff (Low pH, High Metal Concentrations) Versus Natural Carolina Bay Water (Low pH, Low Metal Concentrations) on Plant Condition and Associated Bacterial Epiphytes of Salvinia minima.

    PubMed

    Lindell, A H; Tuckfield, R C; McArthur, J V

    2016-05-01

    Numerous wetlands and streams have been impacted by acid mine drainage (AMD) resulting in lowered pH and increased levels of toxic heavy metals. Remediation of these contaminated sites requires knowledge on the response of microbial communities (especially epiphytic) and aquatic plants to these altered environmental conditions. We examined the effect of coal pile runoff waters as an example of AMD in contrast to natural water from Carolina Bays with low pH and levels of metals on Salvinia minima, a non-native, metal accumulating plant and associated epiphytic bacteria. Treatments included water from two Carolina Bays, one AMD basin and Hoagland's Solution at two pH levels (natural and adjusted to 5.0-5.5). Using controlled replicated microcosms (N = 64) we determined that the combination of low pH and high metal concentrations has a significant negative impact (p < 0.05) on plant condition and epiphytes. Solution metal concentrations dropped indicating removal from solution by S. minima in all microcosms. PMID:26908369

  15. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    PubMed

    Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics. PMID:26629819

  16. Frost Induces Respiration and Accelerates Carbon Depletion in Trees

    PubMed Central

    Sperling, Or; Earles, J. Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A.

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0°C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm-3 yr-1 on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics. PMID:26629819

  17. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    PubMed

    Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  18. A MEMS turbine prototype for respiration harvesting

    NASA Astrophysics Data System (ADS)

    Goreke, U.; Habibiabad, S.; Azgin, K.; Beyaz, M. I.

    2015-12-01

    The design, manufacturing, and performance characterization of a MEMS-scale turbine prototype is reported. The turbine is designed for integration into a respiration harvester that can convert normal human breathing into electrical power through electromagnetic induction. The device measures 10 mm in radius, and employs 12 blades located around the turbine periphery along with ball bearings around the center. Finite element simulations showed that an average torque of 3.07 μNm is induced at 12 lpm airflow rate, which lies in normal breathing levels. The turbine and a test package were manufactured using CNC milling on PMMA. Tests were performed at respiration flow rates between 5-25 lpm. The highest rotational speed was measured to be 9.84 krpm at 25 lpm, resulting in 8.96 mbar pressure drop across the device and 370 mW actuation power.

  19. Paper-Based Electrical Respiration Sensor.

    PubMed

    Güder, Firat; Ainla, Alar; Redston, Julia; Mosadegh, Bobak; Glavan, Ana; Martin, T J; Whitesides, George M

    2016-05-01

    Current methods of monitoring breathing require cumbersome, inconvenient, and often expensive devices; this requirement sets practical limitations on the frequency and duration of measurements. This article describes a paper-based moisture sensor that uses the hygroscopic character of paper (i.e. the ability of paper to adsorb water reversibly from the surrounding environment) to measure patterns and rate of respiration by converting the changes in humidity caused by cycles of inhalation and exhalation to electrical signals. The changing level of humidity that occurs in a cycle causes a corresponding change in the ionic conductivity of the sensor, which can be measured electrically. By combining the paper sensor with conventional electronics, data concerning respiration can be transmitted to a nearby smartphone or tablet computer for post-processing, and subsequently to a cloud server. This means of sensing provides a new, practical method of recording and analyzing patterns of breathing. PMID:27059088

  20. Tumors and mitochondrial respiration: a neglected connection.

    PubMed

    Viale, Andrea; Corti, Denise; Draetta, Giulio F

    2015-09-15

    For decades, tumor cells have been considered defective in mitochondrial respiration due to their dominant glycolytic metabolism. However, a growing body of evidence is now challenging this assumption, and also implying that tumors are metabolically less homogeneous than previously supposed. A small subpopulation of slow-cycling cells endowed with tumorigenic potential and multidrug resistance has been isolated from different tumors. Deep metabolic characterization of these tumorigenic cells revealed their dependency on mitochondrial respiration versus glycolysis, suggesting the existence of a common metabolic program active in slow-cycling cells across different tumors. These findings change our understanding of tumor metabolism and also highlight new vulnerabilities that can be exploited to eradicate cancer cells responsible for tumor relapse.

  1. Transducer for monitoring respiration during imaging procedures.

    PubMed

    Jones, K R

    1988-07-01

    A transducer system for monitoring respiration is described; it uses a 'liquid column' sensor with a remote integrated circuit pressure module. It was designed primarily for non-invasive monitoring and control of respiration during diagnostic imaging procedures, but has also found applications in other areas, e.g. physiotherapy and pulse monitoring. The device is a new version of a system developed several years ago and takes advantage of relatively low cost commercial 'building blocks'. The output is an analogue voltage (from a low impedance source) capable of driving a wide range of recorders, amplifiers and computer interfaces. Reference is also made in the text to a bio-feedback signal processing and display unit (described elsewhere) which, when used with this transducer, provides a versatile respiratory control system.

  2. Hydrological pulse regulating the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes

    PubMed Central

    Vidal, Luciana O.; Abril, Gwenäel; Artigas, Luiz F.; Melo, Michaela L.; Bernardes, Marcelo C.; Lobão, Lúcia M.; Reis, Mariana C.; Moreira-Turcq, Patrícia; Benedetti, Marc; Tornisielo, Valdemar L.; Roland, Fabio

    2015-01-01

    We evaluated in situ rates of bacterial carbon processing in Amazonian floodplain lakes and mainstems, during both high water (HW) and low water (LW) phases (p < 0.05). Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration. Bacterial carbon demand was mostly accounted by BR and presented the same pattern that BR in both water phases. Bacterial growth efficiency (BGE) showed a wide range (0.2–23%) and low mean value of 3 and 6%, (in HW and LW, respectively) suggesting that dissolved organic carbon was mostly allocated to catabolic metabolism. However, BGE was regulated by BP in LW phase. Consequently, changes in BGE showed the same pattern that BP. In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW. Multiple correlation analyses revealed that indexes of organic matter (OM) quality (chlorophyll-a, N stable isotopes and C/N ratios) were the strongest seasonal drivers of bacterial carbon metabolism. Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality. PMID:26483776

  3. Hydrological pulse regulating the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes.

    PubMed

    Vidal, Luciana O; Abril, Gwenäel; Artigas, Luiz F; Melo, Michaela L; Bernardes, Marcelo C; Lobão, Lúcia M; Reis, Mariana C; Moreira-Turcq, Patrícia; Benedetti, Marc; Tornisielo, Valdemar L; Roland, Fabio

    2015-01-01

    We evaluated in situ rates of bacterial carbon processing in Amazonian floodplain lakes and mainstems, during both high water (HW) and low water (LW) phases (p < 0.05). Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration. Bacterial carbon demand was mostly accounted by BR and presented the same pattern that BR in both water phases. Bacterial growth efficiency (BGE) showed a wide range (0.2-23%) and low mean value of 3 and 6%, (in HW and LW, respectively) suggesting that dissolved organic carbon was mostly allocated to catabolic metabolism. However, BGE was regulated by BP in LW phase. Consequently, changes in BGE showed the same pattern that BP. In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW. Multiple correlation analyses revealed that indexes of organic matter (OM) quality (chlorophyll-a, N stable isotopes and C/N ratios) were the strongest seasonal drivers of bacterial carbon metabolism. Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality. PMID:26483776

  4. Physiologic and subjective effects of respirator mask type.

    PubMed

    Harber, P; Beck, J; Brown, C; Luo, J

    1991-09-01

    The effect of alternate airflow path designs on full-face mask air-purifying respirators was assessed in 14 healthy volunteers during submaximal exercise. Respirator designs included no respirator (N), full-face mask, dual-cartridge with no nasal deflector (FN), full-face mask respirator with nasal deflector (FD), and a powered air-purifying respirator (PA). Physiologic effects were measured by using respiratory inductive plethysmography and subjective responses by two visual analog scales. There were significant effects of airflow path design upon the physiologic parameters of ventilation, tidal volume, and mean flow rate. There were no significant physiologic or subjective differences between the full-face mask respirators with and without the nasal deflector in place. The PA had less physiologic impact than the nonpowered models but did not show significant subjective benefit. The study suggests that both subjective and objective physiologic responses must be utilized in assessing respirator design. PMID:1781441

  5. Respirators, internal dose, and Oyster Creek

    SciTech Connect

    Michal, R.

    1996-06-01

    This article looks at the experience of Oyster Creek in relaxing the requirements for the use of respirators in all facets of plant maintenance, on the overall dose received by plant maintenance personnel. For Roger Shaw, director of radiological controls for three years at GPU Nuclear Corporation`s Oyster Creek nuclear plant the correct dose balance is determined on a job-by-job basis: Does the job require a respirator, which is an effective means of decreasing worker inhalation of airborne radioactive particles? Will wearing a respirator slow down a worker, consequently increasing whole body radiation exposure by prolonging the time spent in fields of high external radiation? How does respiratory protection affect worker safety and to what degree? While changes to the Nuclear Regulatory Commission`s 10CFR20 have updated the radiation protection requirements for the nuclear industry, certain of the revisions have been directed specifically at reducing worker dose, Shaw said. {open_quotes}It basically delineates that dose is dose,{close_quotes} Shaw said, {open_quotes}regardless of whether it is acquired externally or internally.{close_quotes} The revision of Part 20 changed the industry`s attitude toward internal dose, which had always been viewed negatively. {open_quotes}Internal dose was always seen as preventable by wearing respirators and by using engineering techniques such as ventilation control and decontamination,{close_quotes} Shaw said, {open_quotes}whereas external dose, although reduced where practical, was seen as a fact of the job.{close_quotes}

  6. Aerosol penetration through respirator exhalation valves.

    PubMed

    Bellin, P; Hinds, W C

    1990-10-01

    Exhalation valves are a critical component of industrial respirators. They are designed to permit minimal inward leakage of air contaminants during inhalation and provide low resistance during exhalation. Under normal conditions, penetration of aerosol through exhalation valves is minimal. The exhalation valve is, however, a vulnerable component of a respirator and under actual working conditions may become dirty or damaged to the point of causing significant leakage. Aerosol penetration was measured for normal exhalation valves and valves compromised by paint or fine copper wires on the valve seat. Penetration increased with increasing wire diameter. A wire 250 microns in diameter allowed greater than 1% penetration into the mask cavity. Dirt or paint accumulated on the exhalation valve allowed a similar level of penetration. Work rate had little effect on observed penetration. Penetration decreased significantly with increasing aerosol particle size. The amount of material on the valve or valve seat necessary for significant (greater than 0.5%) inward leakage in a half-mask respirator could be readily observed by careful inspection of the exhalation valve and its seat in good lighting conditions.

  7. How Ecosystems Breathe: Measuring Respiration of Soil

    NASA Astrophysics Data System (ADS)

    McTammany, M. E.

    2005-05-01

    Curriculum for general ecology labs often uses in-lab exercises and computer simulations to demonstrate ecological principles rather than experimental field projects. In addition, ecosystem processes can be difficult to incorporate into general ecology labs because the techniques require sophisticated equipment or complex field designs. As an alternative to in-lab projects, I have integrated field measurement of soil respiration into my general ecology lab to teach students aspects of experimental design (sampling, replication, error, etc.) and to demonstrate how organism-level processes operate beyond single organisms in nature and are influenced by environmental conditions. In a program laden with biomedical interests, analogies between organisms and ecosystems are quite appealing to students. Students in my general ecology course complete a 2-week field project in which they measure soil respiration inside a dark microcosm chamber. We use 10% KOH to trap evolved CO2 and titrate unreacted KOH in lab using 1N HCl. The protocol is simple, only requires some chemicals, and can be used in many different habitats (including flower beds on campus) quite easily. Potential experiments could involve varying environmental conditions, such as soil moisture, nutrient availability, gaseous environment, carbon supply, or temperature, to affect soil respiration rate.

  8. Diffusion in biofilms respiring on electrodes

    SciTech Connect

    Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Beyenal, Haluk

    2012-11-15

    The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed for noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that (1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; (2) Drs at a given location decreases with G. sulfurreducens biofilm age; (3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and (4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.

  9. DIFFUSION IN BIOFILMS RESPIRING ON ELECTRODES

    PubMed Central

    Renslow, RS; Babauta, JT; Majors, PD; Beyenal, H

    2013-01-01

    The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that 1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; 2) Drs at a given location decreases with G. sulfurreducens biofilm age; 3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and 4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms. PMID:23420623

  10. Continuous respirable mine dust monitor development

    SciTech Connect

    Cantrell, B.K.; Williams, K.L.; Stein, S.W.

    1996-12-31

    In June 1992, the Mine Safety and Health Administration (MSHA) published the Report of the Coal Mine Respirable Dust Task Group, Review of the Program to Control Respirable Coal Mine Dust in the United States. As one of its recommendations, the report called for the accelerated development of two mine dust monitors: (1) a fixed-site monitor capable of providing continuous information on dust levels to the miner, mine operator, and to MSHA, if necessary, and (2) a personal sampling device capable of providing both a short-term personal exposure measurement as well as a full-shift measurement. In response to this recommendation, the U.S. Bureau of Mines initiated the development of a fixed-site machine-mounted continuous respirable dust monitor. The technology chosen for monitor development is the Rupprecht and Patashnick Co., Inc. tapered element oscillating microbalance. Laboratory and in-mine tests have indicated that, with modification, this sensor can meet the humidity and vibration requirements for underground coal mine use. The U.S. Department of Energy Pittsburgh Research Center (DOE-PRC) is continuing that effort by developing prototypes of a continuous dust monitor based on this technology. These prototypes are being evaluated in underground coal mines as they become available. This effort, conducted as a joint venture with MSHA, is nearing completion with every promise of success.

  11. Natural Niche for Organohalide-Respiring Chloroflexi

    PubMed Central

    Krzmarzick, Mark J.; Crary, Benjamin B.; Harding, Jevon J.; Oyerinde, Oyenike O.; Leri, Alessandra C.; Myneni, Satish C. B.

    2012-01-01

    The phylum Chloroflexi contains several isolated bacteria that have been found to respire a diverse array of halogenated anthropogenic chemicals. The distribution and role of these Chloroflexi in uncontaminated terrestrial environments, where abundant natural organohalogens could function as potential electron acceptors, have not been studied. Soil samples (116 total, including 6 sectioned cores) from a range of uncontaminated sites were analyzed for the number of Dehalococcoides-like Chloroflexi 16S rRNA genes present. Dehalococcoides-like Chloroflexi populations were detected in all but 13 samples. The concentrations of organochlorine ([organochlorine]), inorganic chloride, and total organic carbon (TOC) were obtained for 67 soil core sections. The number of Dehalococcoides-like Chloroflexi 16S rRNA genes positively correlated with [organochlorine]/TOC while the number of Bacteria 16S rRNA genes did not. Dehalococcoides-like Chloroflexi were also observed to increase in number with a concomitant accumulation of chloride when cultured with an enzymatically produced mixture of organochlorines. This research provides evidence that organohalide-respiring Chloroflexi are widely distributed as part of uncontaminated terrestrial ecosystems, they are correlated with the fraction of TOC present as organochlorines, and they increase in abundance while dechlorinating organochlorines. These findings suggest that organohalide-respiring Chloroflexi may play an integral role in the biogeochemical chlorine cycle. PMID:22101035

  12. A comparative analysis of green synthesis approach starch capped metal oxides (ZnO & CdO) nanoparticles and its bacterial activity

    NASA Astrophysics Data System (ADS)

    Vidhya, K.; Devarajan, V. P.; Viswanathan, C.; Nataraj, D.; Bhoopathi, G.

    2013-06-01

    In this study, we have investigated the bacterial activity of starch capped ZnO & CdO NPs. The NPs were prepared through green technique under room temperature and then obtained samples were characterized by using XRD and PL techniques. XRD pattern confirms the crystal nature it shows hexagonal structure for ZnO NPs and monoclinic structure for CdO NPs and their average particle size is ±20 nm. Further, the optical properties of NPs were investigated using PL technique in which the starch capped ZnO NPs shows maximum emission at 440 nm whereas starch capped CdO NPs shows maximum emission at 545 nm. Finally, toxic test was performed with E.coli bacteria and their results were investigated. Hence, starch capped ZnO NPs induced less killing effect when compared with starch capped CdO NPs. Therefore, we conclude that the starch capped ZnO NPs may be less toxic to microorganisms when compared with starch capped CdO NPs. In addition, starch capped ZnO NPs is also suitable for anti-microbial activity.

  13. Bacterial Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  14. Bacterial arthritis.

    PubMed

    Ho, G

    2001-07-01

    The septic arthritis literature of 2000 revisited several topics previously examined in some detail. These include septic arthritis in rheumatoid arthritis, rheumatic manifestations of bacterial endocarditis, and infectious complications of prosthetic joints. The trend in antibiotic prophylaxis to prevent late infections in total joint replacement is to narrow the targeted hosts to those most at risk, to define the procedures associated with the greatest risk of bacteremia, and to simplify the antibiotic regimen. The diagnoses of septic arthritis of the lumbar facet joint and septic arthritis caused by direct inoculation of bacteria by a foreign object penetrating the joint are facilitated by noninvasive imaging technologies. Septic arthritis caused by uncommon microorganisms and septic arthritis in immunocompromised hosts are other noteworthy topics in this year's literature. PMID:11555734

  15. Use of a fluorescent redox probe for direct visualization of actively respiring bacteria.

    PubMed

    Rodriguez, G G; Phipps, D; Ishiguro, K; Ridgway, H F

    1992-06-01

    The redox dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was employed for direct epifluorescent microscopic enumeration of respiring bacteria in environmental samples. Oxidized CTC is nearly colorless and is nonfluorescent; however, the compound is readily reduced via electron transport activity to fluorescent, insoluble CTC-formazan, which accumulates intracellularly. Bacteria containing CTC-formazan were visualized by epifluorescence microscopy in wet-mount preparations, on polycarbonate membrane filter surfaces, or in biofilms associated with optically opaque surfaces. Counterstaining of CTC-treated samples with the DNA-specific fluorochrome 4',6-diamidino-2-phenylindole allowed enumeration of active and total bacterial subpopulations within the same preparation. Municipal wastewater, groundwater, and seawater samples supplied with exogenous nutrients yielded CTC counts that were generally lower than total 4',6-diamidino-2-phenylindole counts but typically equal to or greater than standard heterotrophic (aerobic) plate counts. In unsupplemented water samples, CTC counts were typically lower than those obtained with the heterotrophic plate count method. Reduction of CTC by planktonic or biofilm-associated bacteria was suppressed by formaldehyde, presumably because of inhibition of electron transport activity and other metabolic processes. Because of their bright red fluorescence (emission maximum, 602 nm), actively respiring bacteria were readily distinguishable from abiotic particles and other background substances, which typically fluoresced at shorter wavelengths. The use of CTC greatly facilitated microscopic detection and enumeration of metabolically active (i.e., respiring) bacteria in environmental samples.

  16. Large particle penetration through N95 respirator filters and facepiece leaks with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Reponen, Tiina; McKay, Roy; Shukla, Rakesh; Haruta, Hiroki; Sekar, Padmini; Grinshpun, Sergey A

    2010-01-01

    The aim of this study was to investigate respirator filter and faceseal penetration of particles representing bacterial and fungal spore size ranges (0.7-4 mum). First, field experiments were conducted to determine workplace protection factors (WPFs) for a typical N95 filtering facepiece respirator (FFR). These data (average WPF = 515) were then used to position the FFR on a manikin to simulate realistic donning conditions for laboratory experiments. Filter penetration was also measured after the FFR was fully sealed on the manikin face. This value was deducted from the total penetration (obtained from tests with the partially sealed FFR) to determine the faceseal penetration. All manikin experiments were repeated using three sinusoidal breathing flow patterns corresponding to mean inspiratory flow rates of 15, 30, and 85 l min(-1). The faceseal penetration varied from 0.1 to 1.1% and decreased with increasing particle size (P < 0.001) and breathing rate (P < 0.001). The fractions of aerosols penetrating through the faceseal leakage varied from 0.66 to 0.94. In conclusion, even for a well-fitting FFR respirator, most particle penetration occurs through faceseal leakage, which varies with breathing flow rate and particle size.

  17. Large particle penetration through N95 respirator filters and facepiece leaks with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Reponen, Tiina; McKay, Roy; Shukla, Rakesh; Haruta, Hiroki; Sekar, Padmini; Grinshpun, Sergey A

    2010-01-01

    The aim of this study was to investigate respirator filter and faceseal penetration of particles representing bacterial and fungal spore size ranges (0.7-4 mum). First, field experiments were conducted to determine workplace protection factors (WPFs) for a typical N95 filtering facepiece respirator (FFR). These data (average WPF = 515) were then used to position the FFR on a manikin to simulate realistic donning conditions for laboratory experiments. Filter penetration was also measured after the FFR was fully sealed on the manikin face. This value was deducted from the total penetration (obtained from tests with the partially sealed FFR) to determine the faceseal penetration. All manikin experiments were repeated using three sinusoidal breathing flow patterns corresponding to mean inspiratory flow rates of 15, 30, and 85 l min(-1). The faceseal penetration varied from 0.1 to 1.1% and decreased with increasing particle size (P < 0.001) and breathing rate (P < 0.001). The fractions of aerosols penetrating through the faceseal leakage varied from 0.66 to 0.94. In conclusion, even for a well-fitting FFR respirator, most particle penetration occurs through faceseal leakage, which varies with breathing flow rate and particle size. PMID:19700488

  18. Respiration and intensity dependence of photosynthesis in Chlorella.

    PubMed

    BRACKETT, F S; OLSON, R A; CRICKARD, R G

    1953-03-01

    1. Respiration changes as a result of illumination. 2. In the absence of glucose or other supply of substrate, respiration decays in the dark showing at least two types-a fast decay in a few minutes and a slow decay lasting hours. 3. Respiratory response to illumination is delayed. 4. Intermittent illumination (in the absence of glucose, etc.) produces a periodic variation in respiration with a delay or phase lag. 5. Periodic variation of respiration may produce a higher average value in the dark than in the light due to the lag and depending upon the period of intermittent illumination. 6. Based upon average respiration values our data confirm the Kok effect. 7. Interpolated values of respiration, however, result in photosynthetic rates which are linearly dependent upon intensity of illumination. 8. Thus the quantum efficiency is found to be independent of intensity, over the wide range of intensities investigated.

  19. RESPIRATION AND INTENSITY DEPENDENCE OF PHOTOSYNTHESIS IN CHLORELLA

    PubMed Central

    Brackett, Frederick S.; Olson, Rodney A.; Crickard, Robert G.

    1953-01-01

    1. Respiration changes as a result of illumination. 2. In the absence of glucose or other supply of substrate, respiration decays in the dark showing at least two types—a fast decay in a few minutes and a slow decay lasting hours. 3. Respiratory response to illumination is delayed. 4. Intermittent illumination (in the absence of glucose, etc.) produces a periodic variation in respiration with a delay or phase lag. 5. Periodic variation of respiration may produce a higher average value in the dark than in the light due to the lag and depending upon the period of intermittent illumination. 6. Based upon average respiration values our data confirm the Kok effect. 7. Interpolated values of respiration, however, result in photosynthetic rates which are linearly dependent upon intensity of illumination. 8. Thus the quantum efficiency is found to be independent of intensity, over the wide range of intensities investigated. PMID:13035068

  20. The effect of the new Massachusetts Bay sewage outfall on the concentrations of metals and bacterial spores in nearby bottom and suspended sediments

    USGS Publications Warehouse

    Bothner, Michael H.; Casso, M.A.; Rendigs, R. R.; Lamothe, P.J.

    2002-01-01

    Since the new outfall for Boston's treated sewage effluent began operation on September 6, 2000, no change has been observed in concentrations of silver or Clostridium perfringens spores (an ecologically benign tracer of sewage), in bottom sediments at a site 2.5 km west of the outfall. In suspended sediment samples collected with a time-series sediment trap located 1.3 km south of the outfall, silver and C. perfringens spores increased by 38% and 103%, respectively, in post-outfall samples while chromium, copper, and zinc showed no change. All metal concentrations in sediments are <50% of warning levels established by the Massachusetts Water Resources Authority. An 11-year data set of bottom sediment characteristics collected three times per year prior to outfall startup provides perspective for the interpretation of post-outfall data. A greater than twofold increase in concentrations of sewage tracers (silver and C. perfringens) was observed in muddy sediments following the exceptional storm of December 11-16, 1992 that presumably moved contaminated inshore sediment offshore. ?? 2002 Elsevier Science Ltd. All rights reserved.

  1. Tillage Effects on Soil Properties & Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Bogdan, Ileana; Moraru, Paula; Pop, Adrian; Duda, Bogdan; Cacovean, Horea; Coste, Camelia

    2015-04-01

    Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and soil structural condition. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1) to assess the effects of tillage systems (Conventional System-CS, Minimum Tillage-MT, No-Tillage-NT) on soil compaction, soil temperature, soil moisture and soil respiration and 2) to establish the relationship that exists in changing soil properties. Three treatments were installed: CS-plough + disc; MT-paraplow + rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15 cm of soil depth and increased the soil temperature by 0.5-2.20C. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the two conservation tillage measures decreased soil respiration, with the best effects of no-tillage. An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of

  2. Soil respiration under different land uses in Eastern China.

    PubMed

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84-98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86-1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  3. Performance evaluation of filtering facepiece respirators using virus aerosols.

    PubMed

    Zuo, Zhili; Kuehn, Thomas H; Pui, David Y H

    2013-01-01

    Physical penetration and infectivity penetration of adenovirus and influenza virus aerosols through respirators were measured to better characterize the effectiveness of filtering facepiece respirators against airborne virus. A physical penetration of 2%-5% was found. However, large sample-to-sample variation made it difficult to quantify the difference in physical penetration caused by the different virus aerosols. Infectivity penetration of adenovirus was much lower than physical penetration, indicating that the latter provides a conservative estimate for respirator performance. PMID:22483237

  4. Soil Respiration under Different Land Uses in Eastern China

    PubMed Central

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  5. Bacterial vaginosis.

    PubMed Central

    Spiegel, C A

    1991-01-01

    Bacterial vaginosis (BV) is the most common of the vaginitides affecting women of reproductive age. It appears to be due to an alteration in the vaginal ecology by which Lactobacillus spp., the predominant organisms in the healthy vagina, are replaced by a mixed flora including Prevotella bivia, Prevotella disiens, Porphyromonas spp., Mobiluncus spp., and Peptostreptococcus spp. All of these organisms except Mobiluncus spp. are also members of the endogenous vaginal flora. While evidence from treatment trials does not support the notion that BV is sexually transmitted, recent studies have shown an increased risk associated with multiple sexual partners. It has also been suggested that the pathogenesis of BV may be similar to that of urinary tract infections, with the rectum serving as a reservoir for some BV-associated flora. The organisms associated with BV have also been recognized as agents of female upper genital tract infection, including pelvic inflammatory disease, and the syndrome BV has been associated with adverse outcome of pregnancy, including premature rupture of membranes, chorioamnionitis, and fetal loss; postpartum endometritis; cuff cellulitis; and urinary tract infections. The mechanisms by which the BV-associated flora causes the signs of BV are not well understood, but a role for H2O2-producing Lactobacillus spp. in protecting against colonization by catalase-negative anaerobic bacteria has been recognized. These and other aspects of BV are reviewed. PMID:1747864

  6. ESTIMATING ROOT RESPIRATION IN SPRUCE AND BEECH: DECREASES IN SOIL RESPIRATION FOLLOWING GIRDLING

    EPA Science Inventory

    A study was undertaken to follow seasonal fluxes of CO2 from soil and to estimate the contribution of autotrophic (root + mycorrhizal) to total soil respiration (SR) in a mixed stand of European beech (Fagus sylvatica) and Norway spruce (Picea abies) near Freising, Germany. Matu...

  7. Remediation of grey forest soils heavily polluted with heavy metals by means of their leaching at acidic pH followed by the soil reclamation by means of neutralization and bacterial manure addition

    NASA Astrophysics Data System (ADS)

    Georgiev, Plamen; Groudev, Stoyan; Spasova, Irena; Nicolova, Marina

    2014-05-01

    Some grey forest soils in Western Bulgaria are heavily polluted with heavy metals (copper, lead, and zinc), arsenic, and uranium due to the infiltration of acid mine drainage generated at the abandoned uranium mine Curilo. This paper presents some results from a study about soil remediation based on the contaminants leaching from the topsoil by means of irrigation with solutions containing sulphuric acid or its in situ generation by means of sulphur-oxidizing chemolithotrophic bacteria in or without the presence of finely cut straw. These methods were tested in large scale zero suction lysimeters. The approaches based on S° and finely cut straw addition was the most efficient amongst the tested methods and for seven months of soil remediation the concentration of all soil contaminants were decreased below the relevant Maximum Admissible Concentration (MAC). Neutralization of the soil acidity was applied as a next stage of soil reclamation by adding CaCO3 and cow manure. As a result, soil pH increased from strongly acidic (2.36) to slightly acidic (6.15) which allowed subsequent addition of humic acids and bacterial manure to the topsoil. The soil habitat changed in this way facilitated the growth of microorganisms which restored the biogeochemical cycles of nitrogen and carbon to the levels typical for non-polluted grey forest soil.

  8. Metal Binding Specificity of the MntABC Permease of Neisseria gonorrhoeae and Its Influence on Bacterial Growth and Interaction with Cervical Epithelial Cells▿ †

    PubMed Central

    Lim, Karen H. L.; Jones, Christopher E.; vanden Hoven, Rachel N.; Edwards, Jennifer L.; Falsetta, Megan L.; Apicella, Michael A.; Jennings, Michael P.; McEwan, Alastair G.

    2008-01-01

    mntABC from Neisseria gonorrhoeae encodes an ABC permease which includes a periplasmic divalent cation binding receptor protein of the cluster IX family, encoded by mntC. Analysis of an mntC mutant showed that growth of N. gonorrhoeae could be stimulated by addition of either manganese(II) or zinc(II) ions, suggesting that the MntABC system could transport both ions. In contrast, growth of the mntAB mutant in liquid culture was possible only when the medium was supplemented with an antioxidant such as mannitol, consistent with the view that ion transport via MntABC is essential for protection of N. gonorrhoeae against oxidative stress. Using recombinant MntC, we determined that MntC binds Zn2+ and Mn2+ with almost equal affinity (dissociation constant of ∼0.1 μM). Competition assays with the metallochromic zinc indicator 4-(2-pyridylazo)resorcinol showed that MntC binds Mn2+ and Zn2+ at the same binding site. Analysis of the N. gonorrhoeae genome showed that MntC is the only Mn/Zn metal binding receptor protein cluster IX in this bacterium, in contrast to the situation in many other bacteria which have systems with dedicated Mn and Zn binding proteins as part of distinctive ABC cassette permeases. Both the mntC and mntAB mutants had reduced intracellular survival in a human cervical epithelial cell model and showed reduced ability to form a biofilm. These data suggest that the MntABC transporter is of importance for survival of Neisseria gonorrhoeae in the human host. PMID:18426887

  9. Cyanide-insensitive Respiration in Pea Cotyledons 1

    PubMed Central

    James, Terrance W.; Spencer, Mary S.

    1979-01-01

    Mitochondria isolated by a zonal procedure from the cotyledons of germinating peas possessed a cyanide-resistant respiration. This respiration was virtually absent in mitochondria isolated during the first 24 hours of germination but thereafter increased gradually until the 6th or 7th day of seedling development. At this time between 15 and 20% of the succinate oxidation was not inhibited by cyanide. The activity of the cyanide-resistant respiration was also determined in the absence of cyanide. Relationships among mitochondrial structure, cyanide-resistant respiration, and seedling development are discussed. PMID:16660982

  10. Ecosystem-level controls on root-rhizosphere respiration.

    PubMed

    Hopkins, Francesca; Gonzalez-Meler, Miquel A; Flower, Charles E; Lynch, Douglas J; Czimczik, Claudia; Tang, Jianwu; Subke, Jens-Arne

    2013-07-01

    Recent advances in the partitioning of autotrophic from heterotrophic respiration processes in soils in conjunction with new high temporal resolution soil respiration data sets offer insights into biotic and environmental controls of respiration. Besides temperature, many emerging controlling factors have not yet been incorporated into ecosystem-scale models. We synthesize recent research that has partitioned soil respiration into its process components to evaluate effects of nitrogen, temperature and photosynthesis on autotrophic flux from soils at the ecosystem level. Despite the widely used temperature dependence of root respiration, gross primary productivity (GPP) can explain most patterns of ecosystem root respiration (and to some extent heterotrophic respiration) at within-season time-scales. Specifically, heterotrophi crespiration is influenced by a seasonally variable supply of recent photosynthetic products in the rhizosphere. The contribution of stored root carbon (C) to root respiratory fluxes also varied seasonally, partially decoupling the proportion of photosynthetic C driving root respiration. In order to reflect recent insights, new hierarchical models, which incorporate root respiration as a primary function of GPP and which respond to environmental variables by modifying Callocation belowground, are needed for better prediction of future ecosystem C sequestration. PMID:23943914

  11. LINKAGE BETWEEN PRODUCTION AND RESPIRATION ON THE LOUISIANA CONTINENTAL SHELF.

    EPA Science Inventory

    Abstract for presentation. Original title, "PRIMARY PRODUCTION, BACTERIOPLANKTON PRODUCTION, AND COMMUNITY RESPIRATION IN STRATIFIED WATERS OF THE NORTHERN GULF OF MEXICO CONTINENTAL SHELF: LINKAGE TO HYPOXIA."

  12. Autotrophic and heterotrophic components of soil respiration in permafrost zone.

    NASA Astrophysics Data System (ADS)

    Udovenko, Maria; Goncharova, Olga

    2016-04-01

    Soil carbon dioxide emissions production is an important integral indicator of soil biological activity and it includes several components: the root respiration and microbial decomposition of organic matter. Separate determination of the components of soil respiration is necessary for studying the balance of carbon in the soil and to assessment its potential as a sink or source of carbon dioxide. The aim of this study was testing field methods of separate determination of root and microbial respiration in soils of north of West Siberia. The research took place near the town Nadym, Yamalo-Nenets Autonomous District (north of West Siberia).The study area was located in the northern taiga with sporadic permafrost. Investigations were carried out at two sites: in forest and in frozen peatland. 3 methods were tested for the separation of microbial and root respiration. 1) "Shading"; 2) "Clipping"(removing the above-ground green plant parts); 3)a modified method of roots exclusion (It is to compare the emission of soils of "peat spots", devoid of vegetation and roots, and soils located in close proximity to the spots on which there is herbaceous vegetation and moss). For the experiments on methods of "Shading" and "Clipping" in the forest and on the frozen peatland ware established 12 plots, 1 x 1 m (3 plots in the forest and at 9 plots on frozen peatland; 4 of them - control).The criterions for choosing location sites were the similarity of meso- and microrelief, the same depth of permafrost, the same vegetation. Measurement of carbon dioxide emissions (chamber method) was carried out once a day, in the evening, for a week. Separation the root and microbial respiration by "Shading" showed that in the forest the root respiration contribution is 5%, and microbial - 95%. On peatlands root respiration is 41%, 59% of the microbial. In the experiment "Clipping" in peatlands root respiration is 56%, the microbial respiration - 44%, in forest- root respiration is 17%, and

  13. A survey of respirators usage for airborne chemicals in Korea.

    PubMed

    Han, Don-Hee; Kang, Min-Sun

    2009-10-01

    A questionnaire survey was undertaken to identify the current status of respirator usage in manufacturing work environments subject to gas/vapor chemicals exposure in Korea and to suggest improvements to enhance the effectiveness of respirator usage. The number of target companies included 17 big companies, 110 small & mid-size companies, and 5 foreign companies, and the number of respondents included 601 workers and 69 persons in charge of respirators (PCR). The results explained clearly that respirator programs in practice were extremely poor in small & mid-sized companies. The findings indicated that the selection of respirators was not appropriate. Quarter mask including filtering facepiece was the most common facepiece form for respirator and was worn by sixty-four percent. Not a little proportion of respondents (33%) complained about the fit: faceseal leakage between the face and facepiece. A filtering facepiece with carbon fiber filter was used as a substitution for a gas/vapor respirator. Another result was that the PCR respondents' perception of the administration of respirators was very low. The results of this survey suggest that regal enforcement of respiratory protection programs should be established in Korea. On the basis of these findings, respiratory protection programs should include respirator selection, maintenance, training, and fit testing. PMID:19834267

  14. A survey of respirators usage for airborne chemicals in Korea.

    PubMed

    Han, Don-Hee; Kang, Min-Sun

    2009-10-01

    A questionnaire survey was undertaken to identify the current status of respirator usage in manufacturing work environments subject to gas/vapor chemicals exposure in Korea and to suggest improvements to enhance the effectiveness of respirator usage. The number of target companies included 17 big companies, 110 small & mid-size companies, and 5 foreign companies, and the number of respondents included 601 workers and 69 persons in charge of respirators (PCR). The results explained clearly that respirator programs in practice were extremely poor in small & mid-sized companies. The findings indicated that the selection of respirators was not appropriate. Quarter mask including filtering facepiece was the most common facepiece form for respirator and was worn by sixty-four percent. Not a little proportion of respondents (33%) complained about the fit: faceseal leakage between the face and facepiece. A filtering facepiece with carbon fiber filter was used as a substitution for a gas/vapor respirator. Another result was that the PCR respondents' perception of the administration of respirators was very low. The results of this survey suggest that regal enforcement of respiratory protection programs should be established in Korea. On the basis of these findings, respiratory protection programs should include respirator selection, maintenance, training, and fit testing.

  15. Ecosystem-level controls on root-rhizosphere respiration.

    PubMed

    Hopkins, Francesca; Gonzalez-Meler, Miquel A; Flower, Charles E; Lynch, Douglas J; Czimczik, Claudia; Tang, Jianwu; Subke, Jens-Arne

    2013-07-01

    Recent advances in the partitioning of autotrophic from heterotrophic respiration processes in soils in conjunction with new high temporal resolution soil respiration data sets offer insights into biotic and environmental controls of respiration. Besides temperature, many emerging controlling factors have not yet been incorporated into ecosystem-scale models. We synthesize recent research that has partitioned soil respiration into its process components to evaluate effects of nitrogen, temperature and photosynthesis on autotrophic flux from soils at the ecosystem level. Despite the widely used temperature dependence of root respiration, gross primary productivity (GPP) can explain most patterns of ecosystem root respiration (and to some extent heterotrophic respiration) at within-season time-scales. Specifically, heterotrophi crespiration is influenced by a seasonally variable supply of recent photosynthetic products in the rhizosphere. The contribution of stored root carbon (C) to root respiratory fluxes also varied seasonally, partially decoupling the proportion of photosynthetic C driving root respiration. In order to reflect recent insights, new hierarchical models, which incorporate root respiration as a primary function of GPP and which respond to environmental variables by modifying Callocation belowground, are needed for better prediction of future ecosystem C sequestration.

  16. Bioremediation of soils co-contaminated with heavy metals and 2,4,5-trichlorophenol by fruiting body of Clitocybe maxima.

    PubMed

    Liu, Hongying; Guo, Shanshan; Jiao, Kai; Hou, Junjun; Xie, Han; Xu, Heng

    2015-08-30

    Pot experiments were performed to investigate the single effect of 2,4,5-trichlorophenol (TCP) or heavy metals (Cu, Cd, Cu+Cd) and the combined effects of metals-TCP on the growth of Clitocybe maxima together with the accumulation of heavy metals as well as dissipation of TCP. Results showed a negative effect of contaminations on fruiting time and biomass of the mushroom. TCP decreased significantly in soils accounting for 70.66-96.24% of the initial extractable concentration in planted soil and 66.47-91.42% in unplanted soil, which showed that the dissipation of TCP was enhanced with mushroom planting. Higher biological activities (bacterial counts, soil respiration and laccase activity) were detected in planted soils relative to unplanted controls, and the enhanced dissipation of TCP in planted soils might be derived from the increased biological activities. The metals accumulation in mushroom increased with the augment of metal load, and the proportion of acetic acid (HOAc) extractable metal in soils with C. maxima was larger than that in unplanted soils, which may be an explanation of metal uptake by C. maxima. These results suggested that the presence of C. maxima was effective in promoting the bioremediation of soil contaminated with heavy metals and TCP.

  17. Pichia pastoris "just in time" alternative respiration.

    PubMed

    Kern, Alexander; Hartner, Franz S; Freigassner, Maria; Spielhofer, Julia; Rumpf, Cornelia; Leitner, Laura; Fröhlich, Kai-Uwe; Glieder, Anton

    2007-04-01

    Alternative oxidases (Aox or Aod) are present in the mitochondria of plants, fungi and many types of yeast. These enzymes transfer electrons from the ubiquinol pool directly to oxygen without contributing to the proton transfer across the mitochondrial membrane. Alternative oxidases are involved in stress responses, programmed cell death and maintenance of the cellular redox balance. The alternative oxidase gene of the methylotrophic yeast Pichia pastoris was isolated and cloned to study its regulation and the effects of deregulation of the alternative respiration by overexpression or disruption of the gene. Both disruption and overexpression had negative effects on the biomass yield; however, the growth rate and substrate uptake rate of the strain overexpressing the alternative oxidase were slightly increased. These effects were even more pronounced when higher glucose concentrations were used. The occurrence of free intracellular radicals and cell death phenomena was investigated using dihydrorhodamine 123 and the TUNEL test. The results suggest a major contribution of the alternative oxidase to P. pastoris cell viability. The negative effects of deregulated alternative respiration clearly indicated the importance of precise regulation of the alternative oxidase in this yeast.

  18. Filtration of respired gases: theoretical aspects.

    PubMed

    Thiessen, Ron J

    2006-06-01

    The filtration of aerosols and the behavior of aerosolized particles are less intuitive and more complex than commonly indicated in the medical literature, but once the basic principles are presented, they are not difficult to understand or apply. Particles with diameters close to the most penetrating particle size are clearly the particles of greatest concern, interest, and value in considering the performance of different filtration devices, and this size has been identified as the standard particle size for testing respirators and breathing system filters. Although almost every level of health care now mandates the N95 (NIOSH rating) as the minimum rating for medical respirators, there is no such mandate regarding minimum efficiencies of breathing system filters. At least in North America, it still falls to each individual purchaser to ensure that these standardized tests are performed, because manufacturers adhere to these standards only on a voluntary basis. Government regulations similar to NIOSH 42 CFR 84 are needed for breathing system filters and should include a rating system such as N95, N99, or N100. For breathing system filters, the BFE and VFE tests are misleading and should be abandoned (or even better, banned) in favor of internationally recognized sodium chloride tests. Until then, manufacturers will be hesitant to abandon their BFE and VFE data, which give the appearance of vastly better performance than does the sodium chloride test. PMID:16828690

  19. Underwater breathing: the mechanics of plastron respiration

    NASA Astrophysics Data System (ADS)

    Flynn, M. R.; Bush, John W. M.

    The rough, hairy surfaces of many insects and spiders serve to render them water-repellent; consequently, when submerged, many are able to survive by virtue of a thin air layer trapped along their exteriors. The diffusion of dissolved oxygen from the ambient water may allow this layer to function as a respiratory bubble or , and so enable certain species to remain underwater indefinitely. Maintenance of the plastron requires that the curvature pressure balance the pressure difference between the plastron and ambient. Moreover, viable plastrons must be of sufficient area to accommodate the interfacial exchange of O2 and CO2 necessary to meet metabolic demands. By coupling the bubble mechanics, surface and gas-phase chemistry, we enumerate criteria for plastron viability and thereby deduce the range of environmental conditions and dive depths over which plastron breathers can survive. The influence of an external flow on plastron breathing is also examined. Dynamic pressure may become significant for respiration in fast-flowing, shallow and well-aerated streams. Moreover, flow effects are generally significant because they sharpen chemical gradients and so enhance mass transfer across the plastron interface. Modelling this process provides a rationale for the ventilation movements documented in the biology literature, whereby arthropods enhance plastron respiration by flapping their limbs or antennae. Biomimetic implications of our results are discussed.

  20. Penetration of asbestos fibers in respirator filters

    SciTech Connect

    Cheng, Yung-Sung; Pearson, S.D.; Rohrbacher, K.D.; Yeh, Hsu-Chi

    1994-11-01

    Currently, the health risks associated with asbestos have restricted its use and created a growing asbestos abatement industry with a need for respirator filters that are effective for worker protection. The main purpose of this project is to determine the influence of fiber size, electrostatic charge, and flow rate on the penetration of asbestos fibers in respirator filter cartridges. The study includes four types of filters each tested at two flow rates: the AO-R57A, a dual cartridge HEPA filter tested at 16 and 42.5 L/min; the MSA-S, a dust and mist filter tested at 16 and 42.5 L/min; the MSA-A power filter tested at 32 and 85 L/min; and the 3M-8710, a low-efficiency disposable face mask filter tested at 32 and 85 L/min. The three types of asbestos fibers used (amosite, crocidolite, and chrysotile) ranged in length from 0.04-0.5 {mu}m and in aspect ratio (ratio of length to diameter) from 3 to 60. The fibers were used in both charged and neutralized forms. The results from amosite fibers are reported here.

  1. Angiotensin stimulates respiration in spontaneously hypertensive rats.

    PubMed

    Jennings, D B; Lockett, H J

    2000-05-01

    Spontaneously hypertensive rats (SHR) have an activated brain angiotensin system. We hypothesized 1) that ventilation (V) would be greater in conscious SHR than in control Wistar-Kyoto (WKY) rats and 2) that intravenous infusion of the ANG II-receptor blocker saralasin would depress respiration in SHR, but not in WKY. Respiration and oxygen consumption (VO(2)) were measured in conscious aged-matched groups (n = 16) of adult female SHR and WKY. For protocol 1, rats were habituated to a plethysmograph and measurements obtained over 60-75 min. After installation of chronic intravenous catheters, protocol 2 consisted of 30 min of saline infusion ( approximately 14 microliter. kg(-1). min(-1)) followed by 40 min of saralasin (1.3 microgram. kg(-1). min(-1)). V, tidal volume (VT), inspiratory flow [VT/inspiratory time (TI)], breath expiratory time, and VO(2) were higher, and breath TI was lower in "continuously quiet" SHR. In SHR, but not in WKY rats, ANG II-receptor block decreased V, VT, and VT/TI and increased breath TI. During ANG II-receptor block, an average decrease in VO(2) in SHR was not significant. About one-half of the higher V in SHR appears to be accounted for by an ANG II mechanism acting either via peripheral arterial receptors or circumventricular organs.

  2. Can we distinguish autotrophic respiration from heterotrophic respiration in a field site using high temporal resolution CO2 flux measurements?

    NASA Astrophysics Data System (ADS)

    Biro, Beatrice; Berger, Sina; Praetzel, Leandra; Blodau, Christian

    2016-04-01

    The processes behind C-cycling in peatlands are important to understand for assessing the vulnerability of peatlands as carbon sinks under changing climate conditions. Especially boreal peatlands are likely to underlie strong alterations in the future. It is expected that C-pools that are directly influenced by vegetation and water table fluctuations can be easily destabilized. The CO2 efflux through respiration underlies autotrophic and heterotrophic processes that show different feedbacks on changing environmental conditions. In order to understand the respiration fluxes better for more accurate modelling and prognoses, the determination of the relative importance of different respiration sources is necessary. Earlier studies used e.g. exfoliation experiments, incubation experiments or modelling approaches to estimate the different respiration sources for the total ecosystem respiration (Reco). To further the understanding in this topic, I want to distinguish autotrophic and heterotrophic respiration using high temporal resolution measurements. The study site was selected along a hydrological gradient in a peatland in southern Ontario (Canada) and measurements were conducted from May to September 2015 once per month. Environmental controls (water table, soil temperature and soil moisture) that effect the respiration sources were recorded. In my study I used a Li-COR 6400XT and a Los Gatos greenhouse gas analyzer (GGA). Reco was determined by chamber flux measurements with the GGA, while simultaneously CO2 respiration measurements on different vegetation compartments like roots, leaves and mosses were conducted using the Li-COR 6400XT. The difference between Reco and autotrophic respiration equals heterotrophic respiration. After the measurements, the vegetation plots were harvested and separated for all compartments (leaves, roots, mosses, soil organic matter), dried and weighed. The weighted respiration rates from all vegetation compartments sum up to

  3. Endotoxin-induced basal respiration alterations of renal HK-2 cells: A sign of pathologic metabolism down-regulation

    SciTech Connect

    Quoilin, C.; Mouithys-Mickalad, A.; Duranteau, J.; Gallez, B.; Hoebeke, M.

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer A HK-2 cells model of inflammation-induced acute kidney injury. Black-Right-Pointing-Pointer Two oximetry methods: high resolution respirometry and ESR spectroscopy. Black-Right-Pointing-Pointer Oxygen consumption rates of renal cells decrease when treated with LPS. Black-Right-Pointing-Pointer Cells do not recover normal respiration when the LPS treatment is removed. Black-Right-Pointing-Pointer This basal respiration alteration is a sign of pathologic metabolism down-regulation. -- Abstract: To study the mechanism of oxygen regulation in inflammation-induced acute kidney injury, we investigate the effects of a bacterial endotoxin (lipopolysaccharide, LPS) on the basal respiration of proximal tubular epithelial cells (HK-2) both by high-resolution respirometry and electron spin resonance spectroscopy. These two complementary methods have shown that HK-2 cells exhibit a decreased oxygen consumption rate when treated with LPS. Surprisingly, this cellular respiration alteration persists even after the stress factor was removed. We suggested that this irreversible decrease in renal oxygen consumption after LPS challenge is related to a pathologic metabolic down-regulation such as a lack of oxygen utilization by cells.

  4. Respirator Performance against Nanoparticles under Simulated Workplace Activities.

    PubMed

    Vo, Evanly; Zhuang, Ziqing; Horvatin, Matthew; Liu, Yuewei; He, Xinjian; Rengasamy, Samy

    2015-10-01

    Filtering facepiece respirators (FFRs) and elastomeric half-mask respirators (EHRs) are commonly used by workers for protection against potentially hazardous particles, including engineered nanoparticles. The purpose of this study was to evaluate the performance of these types of respirators against 10-400 nm particles using human subjects exposed to NaCl aerosols under simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured for eight combinations of respirator models (2 N95 FFRs, 2 P100 FFRs, 2 N95 EHRs, and 2 P100 EHRs) worn by 25 healthy test subjects (13 females and 12 males) with varying face sizes. Before beginning a SWPF test for a given respirator model, each subject had to pass a quantitative fit test. Each SWPF test was performed using a protocol of six exercises for 3 min each: (i) normal breathing, (ii) deep breathing, (iii) moving head side to side, (iv) moving head up and down, (v) bending at the waist, and (vi) a simulated laboratory-vessel cleaning motion. Two scanning mobility particle sizers were used simultaneously to measure the upstream (outside the respirator) and downstream (inside the respirator) test aerosol; SWPF was then calculated as a ratio of the upstream and downstream particle concentrations. In general, geometric mean SWPF (GM-SWPF) was highest for the P100 EHRs, followed by P100 FFRs, N95 EHRs, and N95 FFRs. This trend holds true for nanoparticles (10-100 nm), larger size particles (100-400 nm), and the 'all size' range (10-400 nm). All respirators provided better or similar performance levels for 10-100 nm particles as compared to larger 100-400 nm particles. This study found that class P100 respirators provided higher SWPFs compared to class N95 respirators (P < 0.05) for both FFR and EHR types. All respirators provided expected performance (i.e. fifth percentile SWPF > 10) against all particle size ranges tested.

  5. Respirator Performance against Nanoparticles under Simulated Workplace Activities.

    PubMed

    Vo, Evanly; Zhuang, Ziqing; Horvatin, Matthew; Liu, Yuewei; He, Xinjian; Rengasamy, Samy

    2015-10-01

    Filtering facepiece respirators (FFRs) and elastomeric half-mask respirators (EHRs) are commonly used by workers for protection against potentially hazardous particles, including engineered nanoparticles. The purpose of this study was to evaluate the performance of these types of respirators against 10-400 nm particles using human subjects exposed to NaCl aerosols under simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured for eight combinations of respirator models (2 N95 FFRs, 2 P100 FFRs, 2 N95 EHRs, and 2 P100 EHRs) worn by 25 healthy test subjects (13 females and 12 males) with varying face sizes. Before beginning a SWPF test for a given respirator model, each subject had to pass a quantitative fit test. Each SWPF test was performed using a protocol of six exercises for 3 min each: (i) normal breathing, (ii) deep breathing, (iii) moving head side to side, (iv) moving head up and down, (v) bending at the waist, and (vi) a simulated laboratory-vessel cleaning motion. Two scanning mobility particle sizers were used simultaneously to measure the upstream (outside the respirator) and downstream (inside the respirator) test aerosol; SWPF was then calculated as a ratio of the upstream and downstream particle concentrations. In general, geometric mean SWPF (GM-SWPF) was highest for the P100 EHRs, followed by P100 FFRs, N95 EHRs, and N95 FFRs. This trend holds true for nanoparticles (10-100 nm), larger size particles (100-400 nm), and the 'all size' range (10-400 nm). All respirators provided better or similar performance levels for 10-100 nm particles as compared to larger 100-400 nm particles. This study found that class P100 respirators provided higher SWPFs compared to class N95 respirators (P < 0.05) for both FFR and EHR types. All respirators provided expected performance (i.e. fifth percentile SWPF > 10) against all particle size ranges tested. PMID:26180261

  6. Cholera toxin production during anaerobic trimethylamine N-oxide respiration is mediated by stringent response in Vibrio cholerae.

    PubMed

    Oh, Young Taek; Park, Yongjin; Yoon, Mi Young; Bari, Wasimul; Go, Junhyeok; Min, Kyung Bae; Raskin, David M; Lee, Kang-Mu; Yoon, Sang Sun

    2014-05-01

    As a facultative anaerobe, Vibrio cholerae can grow by anaerobic respiration. Production of cholera toxin (CT), a major virulence factor of V. cholerae, is highly promoted during anaerobic growth using trimethylamine N-oxide (TMAO) as an alternative electron acceptor. Here, we investigated the molecular mechanisms of TMAO-stimulated CT production and uncovered the crucial involvement of stringent response in this process. V. cholerae 7th pandemic strain N16961 produced a significantly elevated level of ppGpp, the bacterial stringent response alarmone, during anaerobic TMAO respiration. Bacterial viability was impaired, and DNA replication was also affected under the same growth condition, further suggesting that stringent response is induced. A ΔrelA ΔspoT ppGpp overproducer strain produced an enhanced level of CT, whereas anaerobic growth via TMAO respiration was severely inhibited. In contrast, a ppGpp-null strain (ΔrelA ΔspoT ΔrelV) grew substantially better, but produced no CT, suggesting that CT production and bacterial growth are inversely regulated in response to ppGpp accumulation. Bacterial capability to produce CT was completely lost when the dksA gene, which encodes a protein that works cooperatively with ppGpp, was deleted. In the ΔdksA mutant, stringent response growth inhibition was alleviated, further supporting the inverse regulation of CT production and anaerobic growth. In vivo virulence of ΔrelA ΔspoT ΔrelV or ΔdksA mutants was significantly attenuated. The ΔrelA ΔspoT mutant maintained virulence when infected with exogenous TMAO despite its defective growth. Together, our results reveal that stringent response is activated under TMAO-stimulated anaerobic growth, and it regulates CT production in a growth-dependent manner in V. cholerae.

  7. Carbon Monoxide Gas Is Not Inert, but Global, in Its Consequences for Bacterial Gene Expression, Iron Acquisition, and Antibiotic Resistance

    PubMed Central

    Wareham, Lauren K.; Begg, Ronald; Jesse, Helen E.; van Beilen, Johan W.A.; Ali, Salar; Svistunenko, Dimitri; McLean, Samantha; Hellingwerf, Klaas J.; Sanguinetti, Guido

    2016-01-01

    Abstract Aims: Carbon monoxide is a respiratory poison and gaseous signaling molecule. Although CO-releasing molecules (CORMs) deliver CO with temporal and spatial specificity in mammals, and are proven antimicrobial agents, we do not understand the modes of CO toxicity. Our aim was to explore the impact of CO gas per se, without intervention of CORMs, on bacterial physiology and gene expression. Results: We used tightly controlled chemostat conditions and integrated transcriptomic datasets with statistical modeling to reveal the global effects of CO. CO is known to inhibit bacterial respiration, and we found expression of genes encoding energy-transducing pathways to be significantly affected via the global regulators, Fnr, Arc, and PdhR. Aerobically, ArcA—the response regulator—is transiently phosphorylated and pyruvate accumulates, mimicking anaerobiosis. Genes implicated in iron acquisition, and the metabolism of sulfur amino acids and arginine, are all perturbed. The global iron-related changes, confirmed by modulation of activity of the transcription factor Fur, may underlie enhanced siderophore excretion, diminished intracellular iron pools, and the sensitivity of CO-challenged bacteria to metal chelators. Although CO gas (unlike H2S and NO) offers little protection from antibiotics, a ruthenium CORM is a potent adjuvant of antibiotic activity. Innovation: This is the first detailed exploration of global bacterial responses to CO, revealing unexpected targets with implications for employing CORMs therapeutically. Conclusion: This work reveals the complexity of bacterial responses to CO and provides a basis for understanding the impacts of CO from CORMs, heme oxygenase activity, or environmental sources. Antioxid. Redox Signal. 24, 1013–1028. PMID:26907100

  8. Observing Mean Annual Mediterranean Maquis Ecosystem Respiration

    NASA Astrophysics Data System (ADS)

    Marras, S.; Bellucco, V.; Mereu, S.; Sirca, C.; Spano, D.

    2014-12-01

    In semi arid ecosystems, extremely low Soil Water Content (SWC) values may limit ecosystem respiration (Reco) to the point of hiding the typical exponential response of respiration to temperature. This work is aimed to understand and model the Reco of an evergreen Mediterranean maquis ecosystem and to estimate the contribution of soil CO2 efflux to Reco. The selected site is located in the center of the Mediterranean sea in Sardinia (Italy). Mean annual precipitation is 588 mm and mean annual temperature is 15.9 °C. Vegetation cover is heterogeneous: 70% covered by shrubs and 30% of bare soil. Net Ecosystem Exchange (NEE) is monitored with an Eddy Covariance (EC) tower since April 2004. Soil collars were placed underneath the dominant species (Juniperus phoenicea and Pistacia lentiscus) and over the bare soil. Soil CO2 efflux was measured once a month since April 2012. Soil temperature and SWC were monitored continuously at 5 cm depth in 4 different positions close to the soil collars. Six years of EC measurements (2005-2010) and two years of soil CO2 efflux (2012-2013) measurements were analysed. Reco was estimated from the measured EC fluxes at night after filtering for adequate turbulence (u* > 1.5). Reco measurements were then binned into 1°C intervals and median values were first fitted using the Locally Estimated Scatterplot Smoothing (LOESS) method (to determine the dominant trend of the experimental curve) Reco shows an exponential increase with air and soil temperature, until SWC measured at 0.2 m depth remains above 19% vol. Secondly, the coefficients of the selected Lloyd and Taylor (1994) were estimated through the nonlinear least square (nls) method: Rref (ecosystem respiration rate at a reference temperature of 10 °C was equal to 1.65 μmol m-2 s-1 and E0 (activation energy parameter that determines the temperature sensitivity) was equal to 322.46. In addition, bare and drier soils show a reduced response of measured CO2 efflux to increasing

  9. Respiration detection chip with integrated temperature-insensitive MEMS sensors and CMOS signal processing circuits.

    PubMed

    Wei, Chia-Ling; Lin, Yu-Chen; Chen, Tse-An; Lin, Ren-Yi; Liu, Tin-Hao

    2015-02-01

    An airflow sensing chip, which integrates MEMS sensors with their CMOS signal processing circuits into a single chip, is proposed for respiration detection. Three micro-cantilever-based airflow sensors were designed and fabricated using a 0.35 μm CMOS/MEMS 2P4M mixed-signal polycide process. Two main differences were present among these three designs: they were either metal-covered or metal-free structures, and had either bridge-type or fixed-type reference resistors. The performances of these sensors were measured and compared, including temperature sensitivity and airflow sensitivity. Based on the measured results, the metal-free structure with fixed-type reference resistors is recommended for use, because it has the highest airflow sensitivity and also can effectively reduce the output voltage drift caused by temperature change.

  10. 30 CFR 70.300 - Respiratory equipment; respirable dust.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SAFETY AND HEALTH MANDATORY HEALTH STANDARDS-UNDERGROUND COAL MINES Respiratory Equipment § 70.300 Respiratory equipment; respirable dust. Respiratory equipment approved by NIOSH under 42 CFR part 84 shall be... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Respiratory equipment; respirable dust....

  11. 30 CFR 70.300 - Respiratory equipment; respirable dust.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SAFETY AND HEALTH MANDATORY HEALTH STANDARDS-UNDERGROUND COAL MINES Respiratory Equipment § 70.300 Respiratory equipment; respirable dust. Respiratory equipment approved by NIOSH under 42 CFR part 84 shall be... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Respiratory equipment; respirable dust....

  12. Waiting to inhale: HIF-1 modulates aerobic respiration.

    PubMed

    Boutin, Adam T; Johnson, Randall S

    2007-04-01

    The hypoxia-inducible factor HIF-1 is known to promote anaerobic respiration during low oxygen conditions (hypoxia). In this issue, Fukuda et al. (2007) expand the range of HIF-1's functions by showing that it modulates aerobic respiration as well.

  13. Soil Respiration and Student Inquiry: A Perfect Match

    ERIC Educational Resources Information Center

    Hoyt, Catherine Marie; Wallenstein, Matthew David

    2011-01-01

    This activity explores the cycling of carbon between the atmosphere (primarily as CO[subscript 2]) and biomass in plants, animals, and microscopic organisms. Students design soil respiration experiments using a protocol that resembles current practice in soil ecology. Three methods for measuring soil respiration are presented. Student-derived…

  14. 42 CFR 84.1131 - Respirators; required components.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... noseclip, hood, or helmet; (2) Filter unit, canister with filter, or cartridge with filter; (3) Harness; (4... 42 Public Health 1 2012-10-01 2012-10-01 false Respirators; required components. 84.1131 Section..., and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and...

  15. 42 CFR 84.1131 - Respirators; required components.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... noseclip, hood, or helmet; (2) Filter unit, canister with filter, or cartridge with filter; (3) Harness; (4... 42 Public Health 1 2013-10-01 2013-10-01 false Respirators; required components. 84.1131 Section..., and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and...

  16. 42 CFR 84.1131 - Respirators; required components.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... noseclip, hood, or helmet; (2) Filter unit, canister with filter, or cartridge with filter; (3) Harness; (4... 42 Public Health 1 2014-10-01 2014-10-01 false Respirators; required components. 84.1131 Section..., and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and...

  17. Respiration hastens maturation and lowers yield in rice.

    PubMed

    Sitaramam, V; Bhate, R; Kamalraj, P; Pachapurkar, S

    2008-07-01

    Role of respiration in plant growth remains an enigma. Growth of meristematic cells, which are not photosynthetic, is entirely driven by endogenous respiration. Does respiration determine growth and size or does it merely burn off the carbon depleting the biomass? We show here that respiration of the germinating rice seed, which is contributed largely by the meristematic cells of the embryo, quantitatively correlates with the dynamics of much of plant growth, starting with the time for germination to the time for flowering and yield. Seed respiration appears to define the quantitative phenotype that contributes to yield via growth dynamics that could be discerned even in commercial varieties, which are biased towards higher yield, despite considerable susceptibility of the dynamics to environmental perturbations. Intrinsic variation, irreducible despite stringent growth conditions, required independent validation of relevant physiological variables both by critical sampling design and by constructing dendrograms for the interrelationships between variables that yield high consensus. More importantly, seed respiration, by mediating the generation clock time via variable time for maturation as seen in rice, directly offers the plausible basis for the phenotypic variation, a major ecological stratagem in a variable environment with uncertain water availability. Faster respiring rice plants appear to complete growth dynamics sooner, mature faster, resulting in a smaller plant with lower yield. Counter to the common allometric views, respiration appears to determine size in the rice plant, and offers a valid physiological means, within the limits of intrinsic variation, to help parental selection in breeding. PMID:23572892

  18. Study of contact characteristics between a respirator and a headform.

    PubMed

    Cai, Mang; Shen, Shengnan; Li, Hui; Zhang, Xiaotie; Ma, Yanzhao

    2016-01-01

    This article presents a computational study on contact characteristics of contact pressure and resultant deformation between an N95 filtering facepiece respirator and a newly developed digital headform. The geometry of the headform model is obtained based on computed tomography scanning of a volunteer. The segmentation and reconstruction of the headform model is performed by Mimics v16.0 (Materialise, Leuven, Belgium), which is a medical image processing software. The respirator model is obtained by scanning the surface of a 3M 8210 N95 respirator using a 3D digitizer and then the model is transformed by Geomagic Studio v12.0 (3D system, Rock Hill, SC), a reverse engineering software. The headform model contains a soft tissue layer, a skull layer, and a separate nose. The respirator model contains two layers (an inner face sealing layer and an outer layer) and a nose clip. Both the headform and respirator are modeled as solid elements and are deformable. The commercial software, LS-DYNA (LSTC, Livermore, CA), is used to simulate the contact between the respirator and headform. Contact pressures and resultant deformation of the headform are investigated. Effects of respirator stiffness on contact characteristics are also studied. A Matlab (MathWorks, Natick, MA) program is developed to calculate local gaps between the headform and respirator in the stable wearing state. PMID:26558322

  19. Automatic patient respiration failure detection system with wireless transmission

    NASA Technical Reports Server (NTRS)

    Dimeff, J.; Pope, J. M.

    1968-01-01

    Automatic respiration failure detection system detects respiration failure in patients with a surgically implanted tracheostomy tube, and actuates an audible and/or visual alarm. The system incorporates a miniature radio transmitter so that the patient is unencumbered by wires yet can be monitored from a remote location.

  20. Theoretical description of RESPIRATION-CP

    NASA Astrophysics Data System (ADS)

    Nielsen, Anders B.; Tan, Kong Ooi; Shankar, Ravi; Penzel, Susanne; Cadalbert, Riccardo; Samoson, Ago; Meier, Beat H.; Ernst, Matthias

    2016-02-01

    We present a quintuple-mode operator-based Floquet approach to describe arbitrary amplitude modulated cross polarization experiments under magic-angle spinning (MAS). The description is used to analyze variants of the RESPIRATION approach (RESPIRATIONCP) where recoupling conditions and the corresponding first-order effective Hamiltonians are calculated, validated numerically and compared to experimental results for 15N-13C coherence transfer in uniformly 13C,15N-labeled alanine and in uniformly 2H,13C,15N-labeled (deuterated and 100% back-exchanged) ubiquitin at spinning frequencies of 16.7 and 90.9 kHz. Similarities and differences between different implementations of the RESPIRATIONCP sequence using either CW irradiation or small flip-angle pulses are discussed.

  1. N95 respirator use during advanced pregnancy

    PubMed Central

    Roberge, Raymond J.; Kim, Jung-Hyun; Powell, Jeffrey B.

    2015-01-01

    Background To determine the physiological and subjective effects of wearing an N95 filtering facepiece respirator (N95 FFR) in advanced stages of pregnancy. Methods Healthy pregnant women (n = 22) and nonpregnant women (n = 22) had physiological and subjective measurements taken with and without wearing an N95 FFR during exercise and postural sedentary activities over a 1-hour period. Results There were no differences between the pregnant and nonpregnant women with respect to heart rate, respiratory rate, oxygen saturation, transcutaneous carbon dioxide level, chest wall temperature, aural temperature, and subjective perceptions of exertion and thermal comfort. No significant effect on fetal heart rate was noted. Conclusions Healthy pregnant women wearing an N95 FFR for 1 hour during exercise and sedentary activities did not exhibit any significant differences in measured physiological and subjective responses compared with nonpregnant women. PMID:25278401

  2. Paint spray tests for respirators: aerosol characteristics.

    PubMed

    Ackley, M W

    1980-05-01

    Liquid paint is sprayed from an atomizing nozzle to form an aerosol for testing paint spray respirators. The generated aerosol conditions are dependent upon liguid properties, spray-nozzle flow conditions and droplet evaporation. A technique was developed for controlling the aerosol concentrations reliably. Particle-size distributions of lacquer and enamel have been measured. The lacquer distribution was found to be multi-modal. Aerosol concentration dradients arise when the nozzle is not properly positioned. Filter loading resistance is significantly affected by these concentration variations. With regard to selection of standard aerosol test be improved by modifying the current NIOSH criteria to include a description of the particle-size distribution, a more precise definition of the paint and paint thinner chemical compositions, and a narrower concentration range. PMID:6932174

  3. Hereditary respiration deficiency in Saccharomycodes ludwigii.

    PubMed

    Nagai, S; Kané, N; Ochi, S; Kawai, K; Yamazaki, T

    1976-01-01

    Saccharomycodes ludwigii, supposed to be "petite-negative," gave rise to respiration-deficient mutants when acriflavine and ultraviolet irradiation, respectively, were applied to this yeast, strain IFO 1194. The frequency of such mutants was very low as compared with that in Saccharomyces cervisiae and other "petite-positive" yeasts. Cytochrome composition was characterized by spectrophotometry at the temperature of liquid nitrogen. The respiratory mutants examined contained cytochrome c unaltered in quality and quantity. Cytochrome b was often present only in small amounts though never absent, while cytochrome a + a3 was either present or absent. The respiratory mutants could form zygotes after conjugation with a wild-type culture of opposite mating type (alpha vs. a). The hybridization and segregation analysis of spore tetrads showed the inheritance of respiratory mutant character to be either Mendelian or non-Mendelian and similar to that of pet (nuclear) and rho- (cytoplasmic) mutants, respectively, in Saccharomyces cerevisiae. PMID:1087863

  4. Bacterial differentiation.

    PubMed

    Shapiro, L; Agabian-Keshishian, N; Bendis, I

    1971-09-01

    technique can be used to select for mutants blocked in the various stages of morphogenesis. 3) Temperature-sensitive mutants of Caulobacter that are restricted in macromolecular synthesis and development at elevated temperatures have been isolated. 4) Genetic exchange in the Calflobacter genus has been demonstrated and is now being defined. Two questions related to control processes can now readily be approached experimentally. (i) Is the temporal progression of events occurring during bacterial differentiation controlled by regulator gene products? (ii) Is the differentiation cycle like a biosynthetic pathway where one event must follow another? The availability of temperature-sensitive mutants blocked at various stages of development permits access to both questions. An interesting feature of the differentiation cycle is that the polar organelle may represent a special segregated unit which is operative in the control of the differentiation process. Perhaps the sequential morphogenic changes exhibited by Caulobacter are dependent on the initial synthesis of this organelle. Because the ultimate expression of cell changes are dependent on selective protein synthesis, specific messenger RNA production-either from DNA present in an organelle or from the chromosome-may prove to be a controlling factor in cell differentiation. We have begun studies with RNA polymerase purified from Caulobacter crescentus to determine whether cell factors or alterations in the enzyme structure serve to change the specificity of transcription during the cell cycle. Control of sequential cell changes at the level of transcription has long been postulated and has recently been substantiated in the case of Bacillus sporulation (6). The Caulobacter bacteria now present another system in which direct analysis of these control mechanisms is feasible. PMID:5572165

  5. Direct Quantification of Microbial Community Respiration along a Contamination Gradient using a novel Hydrologic Smart Tracer

    NASA Astrophysics Data System (ADS)

    Stanaway, D. J.; Haggerty, R.; Feris, K. P.

    2010-12-01

    Heavy metal contamination in lotic ecosystems is a major health and environmental concern worldwide. The Resazurin Resorufin (Raz Rru) Smart Tracer system (Haggerty et al., 2008) provides a novel approach to test current models of microbial ecosystem response to chronic stressors such as heavy metals. These models predict that functional redundancy of metabolic capabilities of community members (e.g. respiration rate and enzyme activity) will compensate for decreases in species diversity until a stress threshold is reached. At this point, species diversity and function are expected to decline rapidly. Contrary to this model, microbial communities of the Clark Fork River (CF), Montana, demonstrate high levels of species diversity along the contamination gradient, whereas community function is inversely proportional to the level of contamination. The Raz Rru tool, a metabolically reactive hydrologic tracer, allows for direct quantification of in-situ microbial respiration rates. Therefore, this tool provides an opportunity to build upon studies of ecosystem response to contamination previously limited to extrapolation of point scale measurements to reach scale processes. The Raz Rru tool is used here to quantify the magnitude of metal induced limits on heterotrophic microbial respiration in communities that have evolved to different levels of chronic metal exposure. In this way we propose to be able to test a novel hypothesis concerning the nature of evolution of community processes to chronic stress and persistent environmental pollutants. Specifically, we hypothesize that metal contamination produces a measureable metabolic cost to both tolerant and intolerant communities. To test this hypothesis, rates of respiration associated with hyporheic sediments, supporting intact microbial communities, were quantified in the presence and absence of an acute Cd exposure in column experiments. Hyporheic sediment was collected from differently contaminated locations within

  6. Identification and characterization of a bacterial hydrosulphide ion channel

    SciTech Connect

    Czyzewski, Bryan K.; Wang, Da-Neng

    2012-10-26

    The hydrosulphide ion (HS{sup -}) and its undissociated form, hydrogen sulphide (H{sub 2}S), which are believed to have been critical to the origin of life on Earth, remain important in physiology and cellular signalling. As a major metabolite in anaerobic bacterial growth, hydrogen sulphide is a product of both assimilatory and dissimilatory sulphate reduction. These pathways can reduce various oxidized sulphur compounds including sulphate, sulphite and thiosulphate. The dissimilatory sulphate reduction pathway uses this molecule as the terminal electron acceptor for anaerobic respiration, in which process it produces excess amounts of H{sub 2}S. The reduction of sulphite is a key intermediate step in all sulphate reduction pathways. In Clostridium and Salmonella, an inducible sulphite reductase is directly linked to the regeneration of NAD{sup +}, which has been suggested to have a role in energy production and growth, as well as in the detoxification of sulphite. Above a certain concentration threshold, both H{sub 2}S and HS{sup -} inhibit cell growth by binding the metal centres of enzymes and cytochrome oxidase, necessitating a release mechanism for the export of this toxic metabolite from the cell. Here we report the identification of a hydrosulphide ion channel in the pathogen Clostridium difficile through a combination of genetic, biochemical and functional approaches. The HS{sup -} channel is a member of the formate/nitrite transport family, in which about 50 hydrosulphide ion channels form a third subfamily alongside those for formate (FocA) and for nitrite (NirC). The hydrosulphide ion channel is permeable to formate and nitrite as well as to HS{sup -} ions. Such polyspecificity can be explained by the conserved ion selectivity filter observed in the channel's crystal structure. The channel has a low open probability and is tightly regulated, to avoid decoupling of the membrane proton gradient.

  7. Bacterial Landlines: Contact-dependent Signaling in Bacterial Populations

    PubMed Central

    Blango, Matthew G.; Mulvey, Matthew A.

    2009-01-01

    Summary Bacterial populations utilize a variety of signaling strategies to exchange information, including the secretion of quorum-sensing molecules and contact-dependent signaling cascades. Although quorum sensing has received the bulk of attention for many years, contact-dependent signaling is forging a niche in the research world with the identification of novel systems and the emergence of more mechanistic data. Contact-dependent signaling is likely a common strategy by which bacteria in close contact, such as within biofilms, can modulate the growth and behavior of both siblings and competitors. Ongoing work with diverse bacterial systems, including Myxococcus xanthus, pathogenic Escherichia coli strains, Bacillus subtilis, and dissimilatory metal-reducing soil bacteria, is providing increasingly detailed insight into the dynamic mechanisms and potential of contact-dependent signaling processes. PMID:19246237

  8. Does metal pollution matter with C retention by rice soil?

    NASA Astrophysics Data System (ADS)

    Bian, Rongjun; Cheng, Kun; Zheng, Jufeng; Liu, Xiaoyu; Liu, Yongzhuo; Li, Zhipeng; Li, Lianqing; Smith, Pete; Pan, Genxing; Crowley, David; Zheng, Jinwei; Zhang, Xuhui; Zhang, Liangyun; Hussain, Qaiser

    2015-08-01

    Soil respiration, resulting in decomposition of soil organic carbon (SOC), emits CO2 to the atmosphere and increases under climate warming. However, the impact of heavy metal pollution on soil respiration in croplands is not well understood. Here we show significantly increased soil respiration and efflux of both CO2 and CH4 with a concomitant reduction in SOC storage from a metal polluted rice soil in China. This change is linked to a decline in soil aggregation, in microbial abundance and in fungal dominance. The carbon release is presumably driven by changes in carbon cycling occurring in the stressed soil microbial community with heavy metal pollution in the soil. The pollution-induced increase in soil respiration and loss of SOC storage will likely counteract efforts to increase SOC sequestration in rice paddies for climate change mitigation.

  9. Does metal pollution matter with C retention by rice soil?

    PubMed

    Bian, Rongjun; Cheng, Kun; Zheng, Jufeng; Liu, Xiaoyu; Liu, Yongzhuo; Li, Zhipeng; Li, Lianqing; Smith, Pete; Pan, Genxing; Crowley, David; Zheng, Jinwei; Zhang, Xuhui; Zhang, Liangyun; Hussain, Qaiser

    2015-08-14

    Soil respiration, resulting in decomposition of soil organic carbon (SOC), emits CO2 to the atmosphere and increases under climate warming. However, the impact of heavy metal pollution on soil respiration in croplands is not well understood. Here we show significantly increased soil respiration and efflux of both CO2 and CH4 with a concomitant reduction in SOC storage from a metal polluted rice soil in China. This change is linked to a decline in soil aggregation, in microbial abundance and in fungal dominance. The carbon release is presumably driven by changes in carbon cycling occurring in the stressed soil microbial community with heavy metal pollution in the soil. The pollution-induced increase in soil respiration and loss of SOC storage will likely counteract efforts to increase SOC sequestration in rice paddies for climate change mitigation.

  10. Y-12 Respirator Flow Cycle Time Reduction Project

    SciTech Connect

    Hawk, C.T.; Rogers, P.E.

    2000-12-01

    In mid-July 2000, a Cycle Time Reduction (CTR) project was initiated by senior management to improve the flow and overall efficiency of the respirator distribution process at Y-12. A cross-functional team was formed to evaluate the current process and to propose necessary changes for improvement. Specifically, the team was challenged to make improvements that would eliminate production work stoppages due to the unavailability of respirators in Y-12 Stores. Prior to the team initiation, plant back orders for a specific model respirator were averaging above 600 and have been as high as 750+. The Cycle Time Reduction team segmented the respirator flow into detailed steps, with the focus and emphasis primarily being on the movement of dirty respirators out of work areas, transportation to Oak Ridge National Laboratory (ORNL) Laundry, and return back to Y-12 Stores inventory. The team selected a popular model respirator, size large, to track improvements. Despite a 30 percent increase in respirator usage for the same period of time in the previous year, the team has reduced the back orders by 89% with a steady trend downward. Summary of accomplishments: A 47 percent reduction in the average cycle time for dirty respirators to be laundered and stocked for reuse at the Y-12 Complex; A 73 percent reduction in the average cycle time for dirty respirators to be laundered and stocked for reuse specifically for major users: Enriched Uranium Operations (EUO) and Facilities Maintenance Organization (FMO); Development of a performance measure for tracking back orders; An 89 percent reduction in the number of laundered respirators on back order; Implementation of a tracking method to account for respirator loss; Achievement of an annual cost savings/avoidance of $800K with a one-time cost of $20K; Implementation of a routine pick-up schedule for EUO (major user of respirators); Elimination of activities no longer determined to be needed; Elimination of routine complaint calls to

  11. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    PubMed

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China. PMID:26808376

  12. Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

    NASA Technical Reports Server (NTRS)

    Soler-Crespo, R. A.; Monje, O. A.

    2010-01-01

    Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

  13. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    PubMed

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  14. Respiration from the organ level to the stand

    SciTech Connect

    Sprugel, D.G.; Ryan, M.G.; Brooks, J.R.; Vogt, K.A.; Martin, T.A.

    1995-07-01

    The status of efforts to estimate respiration of conifers varies sharply from one tissue to another. There have been numerous measurements of foliage respiration in conifers, but relatively few measurements of within-stand variation in reference to parameters that might be used for scaling. However, a number of logical models for scaling have been proposed (e.g., light, age, or N) and general directions for future research seem well established. There are far fewer measurements of woody-tissue respiration that might be useful for scaling, but some consensus seems to have developed that the use of sapwood biomass and growth rates as indices may provide the key to scaling woody-tissue respiration up to the stand level. Root respiration is still bogged down by a plurality of methods, each of which seems to have some serious disadvantages, so that even the nature of within-stand variation is poorly known. Successful and believable scaling of root respiration from tissue-specific measurements to the stand level seems to be far in the future. Finally, proxy measurements such as litterfall and N concentration can and have been used to estimate respiration for whole stands without measuring tissue-specific rates at all, but all of these techniques require assumptions that need further testing before they will be generally accepted.

  15. Respiration and sodium transport in rabbit urinary bladder.

    PubMed

    Silverthorn, S U; Eaton, D C

    1982-07-28

    Respiration of rabbit urinary bladder was measured in free-floating pieces and in short-circuited pieces mounted in an Ussing chamber. Ouabain, amiloride, and potassium-free saline inhibited respiration approx. 20%; sodium-free saline depressed respiration approx. 40-50%. The coupling ratio between respiration and transport in short-circuited tissues was about two sodium ions per molecule O2. Chloride-free saline depressed mean oxygen consumption 21% in free-floating tissue pieces; 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and furosemide had no effect. The effect of chloride-free saline in short-circuited tissues was variable; in tissues with low transport rates, respiration was stimulated about 21% while in tissue with high transport rates respiration was reduced about 24%. Nystatin and monensin, both of which markedly increase the conductance of cell membranes with a concomitant increase in sodium entry, stimulated respiration. These data indicate that 50-60% of the total oxygen consumption is not influenced by sodium, 20-25% is linked to (Na+ +K+)-ATPase transport, while the remaining 25-30% is sodium-dependent but not ouabain-inhibitable.

  16. Workplace protection factors for an N95 filtering facepiece respirator.

    PubMed

    Janssen, Larry L; Nelson, Thomas J; Cuta, Karen T

    2007-09-01

    This study evaluated the workplace performance of an N95 filtering facepiece, air-purifying respirator in a steel foundry. Air samples were collected inside and outside respirators worn by workers who were properly trained and qualitatively fit tested. For most workers, three or four pairs of air samples were collected on each of 2 days. The 49 valid sample sets were analyzed for iron, silicon, and zirconium. Only iron was present in sufficient concentrations to perform workplace protection factor (WPF) calculations. Individual WPF measurements ranged from 5 to 753. The geometric mean of the distribution was 119 with a lower 5th percentile value of 19. Time-weighted average WPFs (WPF(TWA)) were also calculated for each day for each worker as an estimate of the protection an individual might receive with daily respirator use. The WPF(TWA) values ranged from 15 for the worker with the single WPF value of 5, to a high of 684. The distribution of WPF(TWA) had a geometric mean of 120 and a lower 5th percentile of 22. Both data treatments indicate this respirator's performance was consistent with the assigned protection factor of 10 typically used for half facepiece respirators. The respirator provided adequate protection as used in this study. All contaminant concentrations inside the respirator were well below the relevant occupational exposure limits. Data collected also illustrate the dynamic nature of faceseal leakage in the workplace.

  17. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management

    PubMed Central

    Hou, Xiangyang; Schellenberg, Michael P.

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17μmol.m−2.s−1) and clipping (2.06μmol.m−2.s−1) than under grazing (1.65μmol.m−2.s−1) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China. PMID:26808376

  18. Soil Respiration Hotspots in Temperate Tidal Restored and Natural Wetlands

    NASA Astrophysics Data System (ADS)

    Scott, M.; Schafer, K. V.

    2015-12-01

    Whether a wetland is a carbon dioxide sink or source is dependent on the balance of photosynthesis and ecosystem respiration. As temperature is increasing, respiration may accelerate over photosynthesis, yet the dynamics in tidal temperate wetlands are not clear as the tidal influence impact respiration egress of the soil. Here, we investigated soil respiration of two different microsites in each a natural and a restored wetland over a range of temperature and water level conditions over the growing season. Soil respiration increased with incoming tide and was lowest under water-inundated conditions. Mudflat microsites tended to have higher soil respiration than vegetated areas, indicating sufficiently high carbon input into non-vegetated areas for high respiratory fluxes. Whereby Spartina alterniflora microsites exhibited on average lower soil respiration fluxes of about 13 micromol m-2 s-1, Spartina patens exhibited higher fluxes at about 38 micromol m2 s-1 with Phragmites australis intermediate soil respiratory fluxes. Largest spatial variation was observed for mudflat microsites.

  19. Workplace protection factors for an N95 filtering facepiece respirator.

    PubMed

    Janssen, Larry L; Nelson, Thomas J; Cuta, Karen T

    2007-09-01

    This study evaluated the workplace performance of an N95 filtering facepiece, air-purifying respirator in a steel foundry. Air samples were collected inside and outside respirators worn by workers who were properly trained and qualitatively fit tested. For most workers, three or four pairs of air samples were collected on each of 2 days. The 49 valid sample sets were analyzed for iron, silicon, and zirconium. Only iron was present in sufficient concentrations to perform workplace protection factor (WPF) calculations. Individual WPF measurements ranged from 5 to 753. The geometric mean of the distribution was 119 with a lower 5th percentile value of 19. Time-weighted average WPFs (WPF(TWA)) were also calculated for each day for each worker as an estimate of the protection an individual might receive with daily respirator use. The WPF(TWA) values ranged from 15 for the worker with the single WPF value of 5, to a high of 684. The distribution of WPF(TWA) had a geometric mean of 120 and a lower 5th percentile of 22. Both data treatments indicate this respirator's performance was consistent with the assigned protection factor of 10 typically used for half facepiece respirators. The respirator provided adequate protection as used in this study. All contaminant concentrations inside the respirator were well below the relevant occupational exposure limits. Data collected also illustrate the dynamic nature of faceseal leakage in the workplace. PMID:17654225

  20. Respirator donning in post-hurricane New Orleans.

    PubMed

    Cummings, Kristin J; Cox-Ganser, Jean; Riggs, Margaret A; Edwards, Nicole; Kreiss, Kathleen

    2007-05-01

    We evaluated correctness of N95 filtering facepiece respirator donning by the public in post-hurricane New Orleans, where respirators were recommended for mold remediation. We randomly selected, interviewed, and observed 538 participants, using multiple logistic regression for analysis. Only 129 (24%) participants demonstrated proper donning. Errors included nose clip not tightened (71%) and straps incorrectly placed (52%); 22% put on the respirator upside down. Factors independently associated with proper donning were as follows: ever having used a mask or respirator (odds ratio [OR] 5.28; 95% confidence interval [CI], 1.79-22.64); ever having had a respirator fit test (OR 4.40; 95% CI, 2.52-7.81); being male (OR 2.44; 95% CI, 1.50-4.03); Caucasian race (OR 2.09; 95% CI, 1.32-3.33); having a certified respirator (OR 1.99, 95% CI, 1.20-3.28); and having participated in mold clean-up (OR 1.82; 95% CI,1.00-3.41). Interventions to improve respirator donning should be considered in planning for influenza epidemics and disasters. PMID:17553247

  1. Noninvasive, quantitative respirator fit testing through dynamic pressure measurement.

    PubMed

    Carpenter, D R; Willeke, K

    1988-10-01

    A new method has been invented for the noninvasive and quantitative determination of fit for a respirator. The test takes a few seconds and requires less expensive instrumentation than presently used for invasive testing. In this test, the breath is held at a negative pressure for a few seconds, and the leak-induced pressure decay inside the respirator cavity is monitored. A dynamic pressure sensor is attached to a modified cartridge of an air-purifying respirator or built into the respirator body or into the air supply line of an air-supplied respirator. The method is noninvasive in that the modified cartridge can be mounted onto any air-purifying respirator. The pressure decay during testing quantifies the airflow entered through the leak site. An equation has been determined which gives the air leakage as a function of pressure decay slope, respirator volume and the pressure differential during actual wear--all of which are determined by the dynamic pressure sensor. Thus, the ratio of air inhaled through the filters or via the air supply line to the leak rate is a measure of respirator fit, independent of aerosol deposition in the lung and aerosol distribution in the respirator cavity as found for quantitative fit testing with aerosols. The new method is shown to be independent of leak and sensor locations. The concentration and distribution of aerosols entered through the leak site is dependent only on the physical dimensions of the leak site and the air velocity in it, which can be determined independently.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3189157

  2. Respirator Use in a Hospital Setting: Establishing Surveillance Metrics

    PubMed Central

    Yarbrough, Mary I.; Ficken, Meredith E.; Lehmann, Christoph U.; Talbot, Thomas R.; Swift, Melanie D.; McGown, Paula W.; Wheaton, Robert F.; Bruer, Michele; Little, Steven W.; Oke, Charles A.

    2016-01-01

    Information that details use and supply of respirators in acute care hospitals is vital to prevent disease transmission, assure the safety of health care personnel, and inform national guidelines and regulations. Objective To develop measures of respirator use and supply in the acute care hospital setting to aid evaluation of respirator programs, allow benchmarking among hospitals, and serve as a foundation for national surveillance to enhance effective Personal Protective Equipment (PPE) use and management. Methods We identified existing regulations and guidelines that govern respirator use and supply at Vanderbilt University Medical Center (VUMC). Related routine and emergency hospital practices were documented through an investigation of hospital administrative policies, protocols, and programs. Respirator dependent practices were categorized based on hospital workflow: Prevention (preparation), patient care (response), and infection surveillance (outcomes). Associated data in information systems were extracted and their quality evaluated. Finally, measures representing major factors and components of respirator use and supply were developed. Results Various directives affecting multiple stakeholders govern respirator use and supply in hospitals. Forty-seven primary and secondary measures representing factors of respirator use and supply in the acute care hospital setting were derived from existing information systems associated with the implementation of these directives. Conclusion Adequate PPE supply and effective use that limit disease transmission and protect health care personnel are dependent on multiple factors associated with routine and emergency hospital practices. We developed forty-seven measures that may serve as the basis for a national PPE surveillance system, beginning with standardized measures of respirator use and supply for collection across different hospital types, sizes, and locations to inform hospitals, government agencies

  3. Influence of soil moisture on soil respiration

    NASA Astrophysics Data System (ADS)

    Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

    2015-04-01

    The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes

  4. Controls on Ecosystem and Root Respiration in an Alaskan Peatland

    NASA Astrophysics Data System (ADS)

    McConnell, N. A.; McGuire, A. D.; Harden, J. W.; Kane, E. S.; Turetsky, M. R.

    2010-12-01

    Boreal ecosystems cover 14% of the vegetated surface on earth and account for 25-30% of the world’s soil carbon (C), mainly due to large carbon stocks in deep peat and frozen soil layers. While peatlands have served as historical sinks of carbon, global climate change may trigger re-release of C to the atmosphere and may turn these ecosystems into net C sources. Rates of C release from a peatland are determined by regional climate and local biotic and abiotic factors such as vegetation cover, thaw depth, and peat thickness. Soil CO2 fluxes are driven by both autotrophic (plant) respiration and heterotrophic (microbial) respiration. Thus, changes in plant and microbial activity in the soil will impact CO2 emissions from peatlands. In this study, we explored environmental and vegetation controls on ecosystem respiration and root respiration in a variety of wetland sites. The study was conducted at the Alaskan Peatland Experiment (APEX; www.uoguelph.ca/APEX) sites in the Bonanza Creek Experimental Forest located 35 km southwest of Fairbanks Alaska. We measured ecosystem respiration, root respiration, and monitored a suite of environmental variables along a vegetation and soil moisture gradient including a black spruce stand with permafrost, a shrubby site with permafrost, a tussock grass site, and a herbaceous open rich fen. Within the rich fen, we have been conducting water table manipulations including a control, lowered, and raised water table treatment. In each of our sites, we measured total ecosystem respiration using static chambers and root respiration by harvesting roots from the uppermost 20 cm and placing them in a root cuvette to obtain a root flux. Ecosystem respiration (ER) on a μmol/m2/sec basis varied across sites. Water table was a significant predictor of ER at the lowered manipulation site and temperature was a strong predictor at the control site in the rich fen. Water table and temperature were both significant predictors of ER at the raised

  5. Oxygen and carbon isotopic compositions of gases respired by humans

    SciTech Connect

    Epstein, S.; Zeiri, L. )

    1988-03-01

    Oxygen-isotope fractionation associated with respiration in human individuals at rest is linearly related to the fraction of the O{sub 2} utilized in the respiration process. The slope of this relationship is affected by a history of smoking, by vigorous exercise, and by the N{sub 2}/O{sub 2} ratio of the inhaled gas. For patients who suffer anemia-related diseases, the slope of this relationship is directly proportional to their level of hemoglobin. These results introduce a new approach for studying the mechanisms of O{sub 2} consumption in human respiration and how they are affected by related diseases.

  6. Soil respiration flux in northern coastal temperate rainforest ecosystems

    NASA Astrophysics Data System (ADS)

    D'Amore, D. V.; Nay, S. M.; Edwards, R.; Valentine, D. W.; Hood, E. W.

    2009-12-01

    Forest carbon budgets are of increasing concern because of their linkages with changing climate. The potential source strength of northern forested ecosystems is of great interest due to the large carbon stock of these systems, especially the extensive peatlands. Where very few long-term measurements of soil carbon cycles have been made, such as the North Pacific coastal temperate margin, peatlands have potentially large but largely unknown source strengths, particularly through soil respiration. The easily and widely measured factors that influence the metabolism of plants and microorganisms in soils, such as temperature, moisture and substrate quality, must be coupled with a network of plot-scale measurements of soil respiration fluxes in this region in order to produce reasonable models of soil respiration flux across gradients of climate, vegetation and soil types. We designed a study to address this issue and measured soil respiration across a hydrologic gradient to quantify the influence of soil temperature and moisture on the magnitude and seasonality of carbon fluxes in the coastal temperate rainforest biome. Replicated study sites were established in three common ecosystem types (peatlands, forested wetlands, and upland forest) within three coastal watersheds. In total, nine sites of the three ecosystem types were measured at monthly intervals during the snow-free period between May and November for two years. Soil respiration fluxes during the six-month measurement period were used to construct a respiration flux model for each landscape type. Soil respiration fluxes followed the seasonal temperature pattern in all ecosystem types and also varied with soil saturation as well in uplands. Temperature dependent models of soil respiration flux were best fit to intermediate drainage conditions in forested wetlands and explained up to 85% of the variation in this ecosystem type. Modeled soil respiration estimates were better at low temperatures with high water

  7. Soil respiration flux in northern coastal temperate rainforest ecosystems

    NASA Astrophysics Data System (ADS)

    D'Amore, David; Nay, S. Mark; Edwards, Richard; Valentine, David; Hood, Eran

    2010-05-01

    Forest carbon budgets are of increasing concern because of their linkages with changing climate. The potential source strength of northern forested ecosystems is of great interest due to the large carbon stock of these systems, especially the extensive peatlands. Where very few long-term measurements of soil carbon cycles have been made, such as the North Pacific coastal temperate margin, peatlands have potentially large but largely unknown source strengths, particularly through soil respiration. The easily and widely measured factors that influence the metabolism of plants and microorganisms in soils, such as temperature, moisture and substrate quality, must be coupled with a network of plot-scale measurements of soil respiration fluxes in this region in order to produce reasonable models of soil respiration flux across gradients of climate, vegetation and soil types. We designed a study to address this issue and measured soil respiration across a hydrologic gradient to quantify the influence of soil temperature and moisture on the magnitude and seasonality of carbon fluxes in the coastal temperate rainforest biome. Replicated study sites were established in three common ecosystem types (peatlands, forested wetlands, and upland forest) within three coastal watersheds. In total, nine sites of the three ecosystem types were measured at monthly intervals during the snow-free period between May and November for two years. Soil respiration fluxes during the six-month measurement period were used to construct a respiration flux model for each landscape type. Soil respiration fluxes followed the seasonal temperature pattern in all ecosystem types and also varied with soil saturation as well in uplands. Temperature dependent models of soil respiration flux were best fit to intermediate drainage conditions in forested wetlands and explained up to 85% of the variation in this ecosystem type. Modeled soil respiration estimates were better at low temperatures with high water

  8. Wood and foliar respiration of tropical wet forest environment

    NASA Astrophysics Data System (ADS)

    Asao, S.; Bedoya Arrieta, R.; Ryan, M. G.

    2011-12-01

    Wood and foliar respiration from tropical forests constitute major components of ecosystem respiration that may control their productivity and carbon storage. However, few estimates on tropical forests vary greatly. Furthermore, the trees in these forests respire great amounts of carbon, but impacts of individual tree species on respiration is not well known. We examined wood and foliar respiration in this environment in relation to individual tree species. The objectives of this study were to: 1) identify how respiration rates relate to scaling variables for wood and foliage, 2) examine the effects of individual tree species on these relationships, 3) extrapolate the rates to the annual fluxes of the whole stands, and 4) determine if tree species differed in these fluxes. Established on an abandoned pasture in 1988 at La Selva Biological Station in Costa Rica, the monodominant stands contained four native species in a complete randomized block design. Respiration rates based on tissue surface area ranged among dominant tree species from 0.6 to 1.0 μg C m^-2 s^-1 for small diameter wood (<10cm), 1.0 to 1.8 μg C m^-2 s^-1 for large diameter wood, and 0.7 to 0.8 μg C m^-2 s^-1 for foliage. Understory species had similar wood respiration rates, but foliage respiration rates were about half of those for canopy leaves. Among surface area, volume, or biomass, respiration rates scaled best with surface area for wood with small diameter, volume or biomass for large diameter wood, and leaf area for foliage. These relationships differed slightly among tree species and between canopy trees and understory species. Foliar respiration rate was generally related to leaf nitrogen content, and this relationship differed among dominant tree species. Temperature response of foliar respiration also differed among tree species and canopy class. However, daily and annual temperature fluctuations had less than 3% effect on annual flux. Annual respiratory fluxes from wood and foliage

  9. Metal Inhibition of Growth and Manganese Oxidation in Pseudomonas putida GB-1

    NASA Astrophysics Data System (ADS)

    Pena, J.; Sposito, G.

    2009-12-01

    Biogenic manganese oxides (MnO2) are ubiquitous nanoparticulate minerals that contribute to the adsorption of nutrient and toxicant metals, the oxidative degradation of various organic compounds, and the respiration of metal-reducing bacteria in aquatic and terrestrial environments. The formation of these minerals is catalyzed by a diverse and widely-distributed group of bacteria and fungi, often through the enzymatic oxidation of aqueous Mn(II) to Mn(IV). In metal-impacted ecosystems, toxicant metals may alter the viability and metabolic activity of Mn-oxidizing organisms, thereby limiting the conditions under which biogenic MnO2 can form and diminishing their potential as adsorbent materials. Pseudomonas putida GB-1 (P. putida GB-1) is a model Mn-oxidizing laboratory culture representative of freshwater and soil biofilm-forming bacteria. Manganese oxidation in P. putida GB-1 occurs via two single-electron-transfer reactions, involving a multicopper oxidase enzyme found on the bacterial outer membrane surface. Near the onset of the stationary phase of growth, dark brown MnO2 particles are deposited in a matrix of bacterial cells and extracellular polymeric substances, thus forming heterogeneous biomineral assemblages. In this study, we assessed the influence of various transition metals on microbial growth and manganese oxidation capacity in a P. putida GB-1 culture propagated in a nutrient-rich growth medium. The concentration-response behavior of actively growing P. putida GB-1 cells was investigated for Fe, Co, Ni, Cu and Zn at pH ≈ 6 in the presence and absence of 1 mM Mn. Toxicity parameters such as EC0, EC50 and Hillslope, and EC100 were obtained from the sigmoidal concentration-response curves. The extent of MnO2 formation in the presence of the various metal cations was documented 24, 50, 74 and 104 h after the metal-amended medium was inoculated. Toxicity values were compared to twelve physicochemical properties of the metals tested. Significant

  10. Effects of viruses on bacterial functions under contrasting nutritional conditions for four species of bacteria isolated from Hong Kong waters.

    PubMed

    Liu, Hao; Yuan, Xiangcheng; Xu, Jie; Harrison, Paul J; He, Lei; Yin, Kedong

    2015-01-01

    Free living viruses are ubiquitous in marine waters and concentrations are usually several times higher than the bacterial abundance. These viruses are capable of lysing host bacteria and therefore, play an important role in the microbial loop in oligotrophic waters. However, few studies have been conducted to compare the role of viruses in regulating bacterial abundance and heterotrophic activities between natural oligotrophic waters and anthropogenic influenced eutrophic waters. In this study, we examined viral effects on bacterial functions of four single bacterial species incubated with natural viral assemblages in seawater samples from eutrophic and oligotrophic waters. The viral-lysis of bacteria was significantly higher in eutrophic than oligotrophic waters. This suggests that viruses were capable of controlling bacterial abundance, respiration and production in the eutrophic waters. Cellular bacterial respiration and production was higher with viruses than without viruses, which was more evident in the oligotrophic waters. These results indicate that viruses can slow down bacterial consumption of oxygen and reduce bacteria-induced eutrophication effects in anthropogenic eutrophic waters, but switch to the role of sustaining the bacterial population when nutrients are limiting. There were bacterial species differences in resisting viral attack, which can influence the dominance and biodiversity of bacterial species in coastal waters. PMID:26404394

  11. Effects of viruses on bacterial functions under contrasting nutritional conditions for four species of bacteria isolated from Hong Kong waters

    PubMed Central

    Liu, Hao; Yuan, Xiangcheng; Xu, Jie; Harrison, Paul J.; He, Lei; Yin, Kedong

    2015-01-01

    Free living viruses are ubiquitous in marine waters and concentrations are usually several times higher than the bacterial abundance. These viruses are capable of lysing host bacteria and therefore, play an important role in the microbial loop in oligotrophic waters. However, few studies have been conducted to compare the role of viruses in regulating bacterial abundance and heterotrophic activities between natural oligotrophic waters and anthropogenic influenced eutrophic waters. In this study, we examined viral effects on bacterial functions of four single bacterial species incubated with natural viral assemblages in seawater samples from eutrophic and oligotrophic waters. The viral-lysis of bacteria was significantly higher in eutrophic than oligotrophic waters. This suggests that viruses were capable of controlling bacterial abundance, respiration and production in the eutrophic waters. Cellular bacterial respiration and production was higher with viruses than without viruses, which was more evident in the oligotrophic waters. These results indicate that viruses can slow down bacterial consumption of oxygen and reduce bacteria-induced eutrophication effects in anthropogenic eutrophic waters, but switch to the role of sustaining the bacterial population when nutrients are limiting. There were bacterial species differences in resisting viral attack, which can influence the dominance and biodiversity of bacterial species in coastal waters. PMID:26404394

  12. Effects of viruses on bacterial functions under contrasting nutritional conditions for four species of bacteria isolated from Hong Kong waters

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Yuan, Xiangcheng; Xu, Jie; Harrison, Paul J.; He, Lei; Yin, Kedong

    2015-09-01

    Free living viruses are ubiquitous in marine waters and concentrations are usually several times higher than the bacterial abundance. These viruses are capable of lysing host bacteria and therefore, play an important role in the microbial loop in oligotrophic waters. However, few studies have been conducted to compare the role of viruses in regulating bacterial abundance and heterotrophic activities between natural oligotrophic waters and anthropogenic influenced eutrophic waters. In this study, we examined viral effects on bacterial functions of four single bacterial species incubated with natural viral assemblages in seawater samples from eutrophic and oligotrophic waters. The viral-lysis of bacteria was significantly higher in eutrophic than oligotrophic waters. This suggests that viruses were capable of controlling bacterial abundance, respiration and production in the eutrophic waters. Cellular bacterial respiration and production was higher with viruses than without viruses, which was more evident in the oligotrophic waters. These results indicate that viruses can slow down bacterial consumption of oxygen and reduce bacteria-induced eutrophication effects in anthropogenic eutrophic waters, but switch to the role of sustaining the bacterial population when nutrients are limiting. There were bacterial species differences in resisting viral attack, which can influence the dominance and biodiversity of bacterial species in coastal waters.

  13. Effects of viruses on bacterial functions under contrasting nutritional conditions for four species of bacteria isolated from Hong Kong waters.

    PubMed

    Liu, Hao; Yuan, Xiangcheng; Xu, Jie; Harrison, Paul J; He, Lei; Yin, Kedong

    2015-01-01

    Free living viruses are ubiquitous in marine waters and concentrations are usually several times higher than the bacterial abundance. These viruses are capable of lysing host bacteria and therefore, play an important role in the microbial loop in oligotrophic waters. However, few studies have been conducted to compare the role of viruses in regulating bacterial abundance and heterotrophic activities between natural oligotrophic waters and anthropogenic influenced eutrophic waters. In this study, we examined viral effects on bacterial functions of four single bacterial species incubated with natural viral assemblages in seawater samples from eutrophic and oligotrophic waters. The viral-lysis of bacteria was significantly higher in eutrophic than oligotrophic waters. This suggests that viruses were capable of controlling bacterial abundance, respiration and production in the eutrophic waters. Cellular bacterial respiration and production was higher with viruses than without viruses, which was more evident in the oligotrophic waters. These results indicate that viruses can slow down bacterial consumption of oxygen and reduce bacteria-induced eutrophication effects in anthropogenic eutrophic waters, but switch to the role of sustaining the bacterial population when nutrients are limiting. There were bacterial species differences in resisting viral attack, which can influence the dominance and biodiversity of bacterial species in coastal waters.

  14. Small bowel bacterial overgrowth

    MedlinePlus

    Overgrowth - intestinal bacteria; Bacterial overgrowth - intestine; Small intestinal bacterial overgrowth; SIBO ... Most of the time, the small intestine does not have a high number ... in the small intestine may use up the nutrients needed by the ...

  15. Two decades of warming increases diversity of a potentially lignolytic bacterial community

    PubMed Central

    Pold, Grace; Melillo, Jerry M.; DeAngelis, Kristen M.

    2015-01-01

    As Earth's climate warms, the massive stores of carbon found in soil are predicted to become depleted, and leave behind a smaller carbon pool that is less accessible to microbes. At a long-term forest soil-warming experiment in central Massachusetts, soil respiration and bacterial diversity have increased, while fungal biomass and microbially-accessible soil carbon have decreased. Here, we evaluate how warming has affected the microbial community's capability to degrade chemically-complex soil carbon using lignin-amended BioSep beads. We profiled the bacterial and fungal communities using PCR-based methods and completed extracellular enzyme assays as a proxy for potential community function. We found that lignin-amended beads selected for a distinct community containing bacterial taxa closely related to known lignin degraders, as well as members of many genera not previously noted as capable of degrading lignin. Warming tended to drive bacterial community structure more strongly in the lignin beads, while the effect on the fungal community was limited to unamended beads. Of those bacterial operational taxonomic units (OTUs) enriched by the warming treatment, many were enriched uniquely on lignin-amended beads. These taxa may be contributing to enhanced soil respiration under warming despite reduced readily available C availability. In aggregate, these results suggest that there is genetic potential for chemically complex soil carbon degradation that may lead to extended elevated soil respiration with long-term warming. PMID:26042112

  16. Two decades of warming increases diversity of a potentially lignolytic bacterial community.

    PubMed

    Pold, Grace; Melillo, Jerry M; DeAngelis, Kristen M

    2015-01-01

    As Earth's climate warms, the massive stores of carbon found in soil are predicted to become depleted, and leave behind a smaller carbon pool that is less accessible to microbes. At a long-term forest soil-warming experiment in central Massachusetts, soil respiration and bacterial diversity have increased, while fungal biomass and microbially-accessible soil carbon have decreased. Here, we evaluate how warming has affected the microbial community's capability to degrade chemically-complex soil carbon using lignin-amended BioSep beads. We profiled the bacterial and fungal communities using PCR-based methods and completed extracellular enzyme assays as a proxy for potential community function. We found that lignin-amended beads selected for a distinct community containing bacterial taxa closely related to known lignin degraders, as well as members of many genera not previously noted as capable of degrading lignin. Warming tended to drive bacterial community structure more strongly in the lignin beads, while the effect on the fungal community was limited to unamended beads. Of those bacterial operational taxonomic units (OTUs) enriched by the warming treatment, many were enriched uniquely on lignin-amended beads. These taxa may be contributing to enhanced soil respiration under warming despite reduced readily available C availability. In aggregate, these results suggest that there is genetic potential for chemically complex soil carbon degradation that may lead to extended elevated soil respiration with long-term warming. PMID:26042112

  17. Occupational Exposure to Respirable Dust, Respirable Crystalline Silica and Diesel Engine Exhaust Emissions in the London Tunnelling Environment.

    PubMed

    Galea, Karen S; Mair, Craig; Alexander, Carla; de Vocht, Frank; van Tongeren, Martie

    2016-03-01

    Personal 8-h shift exposure to respirable dust, diesel engine exhaust emissions (DEEE) (as respirable elemental carbon), and respirable crystalline silica of workers involved in constructing an underground metro railway tunnel was assessed. Black carbon (BC) concentrations were also assessed using a MicroAeth AE51. During sprayed concrete lining (SCL) activities in the tunnel, the geometric mean (GM) respirable dust exposure level was 0.91mg m(-3), with the highest exposure measured on a back-up sprayer (3.20mg m(-3)). The GM respirable crystalline silica concentration for SCL workers was 0.03mg m(-3), with the highest measurement also for the back-up sprayer (0.24mg m(-3)). During tunnel boring machine (TBM) activities, the GM respirable dust concentration was 0.54mg m(-3). The GM respirable elemental carbon concentration for all the TBM operators was 18 µg m(-3); with the highest concentration measured on a segment lifter. The BC concentrations were higher in the SCL environment in comparison to the TBM environment (daily GM 18-54 µg m(-3) versus 3-6 µg m(-3)). This small-scale monitoring campaign provides additional personal data on exposures experienced by underground tunnel construction workers.

  18. Occupational Exposure to Respirable Dust, Respirable Crystalline Silica and Diesel Engine Exhaust Emissions in the London Tunnelling Environment.

    PubMed

    Galea, Karen S; Mair, Craig; Alexander, Carla; de Vocht, Frank; van Tongeren, Martie

    2016-03-01

    Personal 8-h shift exposure to respirable dust, diesel engine exhaust emissions (DEEE) (as respirable elemental carbon), and respirable crystalline silica of workers involved in constructing an underground metro railway tunnel was assessed. Black carbon (BC) concentrations were also assessed using a MicroAeth AE51. During sprayed concrete lining (SCL) activities in the tunnel, the geometric mean (GM) respirable dust exposure level was 0.91mg m(-3), with the highest exposure measured on a back-up sprayer (3.20mg m(-3)). The GM respirable crystalline silica concentration for SCL workers was 0.03mg m(-3), with the highest measurement also for the back-up sprayer (0.24mg m(-3)). During tunnel boring machine (TBM) activities, the GM respirable dust concentration was 0.54mg m(-3). The GM respirable elemental carbon concentration for all the TBM operators was 18 µg m(-3); with the highest concentration measured on a segment lifter. The BC concentrations were higher in the SCL environment in comparison to the TBM environment (daily GM 18-54 µg m(-3) versus 3-6 µg m(-3)). This small-scale monitoring campaign provides additional personal data on exposures experienced by underground tunnel construction workers. PMID:26403363

  19. A bacterial bioreporter panel to assay the cytotoxicity of atmospheric particulate matter

    NASA Astrophysics Data System (ADS)

    Kessler, Nivi; Schauer, James J.; Yagur-Kroll, Sharon; Melamed, Sahar; Tirosh, Ofir; Belkin, Shimshon; Erel, Yigal

    2012-12-01

    Numerous studies have demonstrated that elevated concentrations of suspended atmospheric particulate matter (PM) are associated with adverse health effects. In order to minimize the adverse public health effects of atmospheric PM by exposure management, there is a need for a greater understanding of the toxic mechanisms and the components that are responsible for the toxic effects. The aim of this study was to utilize bioassay techniques to investigate these aspects. For this purpose a reporter panel of 9 genetically engineered bacterial (Escherichia coli) strains was composed. Each panel member was designed to report on a different stress condition with a measurable light signal produced by the luciferase enzyme. Toxic mechanisms and components were studied using six anthropogenic PM source samples, including two vehicle combustion particles, three coal fly ash (CFA) samples and an urban dust sample. The most prominent outcome of the panel exposure results were broad panel responses observed for two of the CFA samples, indicating oxidative stress, respiration inhibition and iron deficiency. These responses were relieved when the samples were treated with EDTA, a non-specific metal chelator, suggesting the involvement of metals in the observed effects. Bioavailability analysis of the samples suggests that chromium was related to the toxic responses induced by two of the CFA samples. Oxidative stress was also observed in several samples of ambient atmospheric aerosols and excess metal toxicity in an urban dust sample collected in a parking lot. The reporter panel approach, as demonstrated in this study, has the potential of providing novel insights as to the mechanisms of atmospheric PM toxicity. Furthermore, combining the panel's results with bioavailability data can enlighten about the role of different PM components in the observed toxicity.

  20. A bacterial view of the periodic table: genes and proteins for toxic inorganic ions.

    PubMed

    Silver, Simon; Phung, Le T

    2005-12-01

    Essentially all bacteria have genes for toxic metal ion resistances and these include those for Ag+, AsO2-, AsO4(3-), Cd2+ Co2+, CrO4(2-), Cu2+, Hg2+, Ni2+, Pb2+, TeO3(2-), Tl+ and Zn2+. The largest group of resistance systems functions by energy-dependent efflux of toxic ions. Fewer involve enzymatic transformations (oxidation, reduction, methylation, and demethylation) or metal-binding proteins (for example, metallothionein SmtA, chaperone CopZ and periplasmic silver binding protein SilE). Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. For example, Cd2+-efflux pumps of bacteria are either inner membrane P-type ATPases or three polypeptide RND chemiosmotic complexes consisting of an inner membrane pump, a periplasmic-bridging protein and an outer membrane channel. In addition to the best studied three-polypeptide chemiosmotic system, Czc (Cd2+, Zn2+, and Co2), others are known that efflux Ag+, Cu+, Ni2+, and Zn2+. Resistance to inorganic mercury, Hg2+ (and to organomercurials, such as CH3Hg+ and phenylmercury) involve a series of metal-binding and membrane transport proteins as well as the enzymes mercuric reductase and organomercurial lyase, which overall convert more toxic to less toxic forms. Arsenic resistance and metabolizing systems occur in three patterns, the widely-found ars operon that is present in most bacterial genomes and many plasmids, the more recently recognized arr genes for the periplasmic arsenate reductase that functions in anaerobic respiration as a terminal electron acceptor, and the aso genes for the periplasmic arsenite oxidase that functions as an initial electron donor in aerobic resistance to arsenite.

  1. [Effects of soil temperature and humidity on soil respiration rate under Pinus sylvestriformis forest].

    PubMed

    Liu, Ying; Han, Shijie; Hu, Yanling; Dai, Guanhua

    2005-09-01

    Employing root-wrenching method and LI-6400-09 soil respiration chamber, this paper measured the diurnal changes of soil respiration rate with and without roots in situ on June 17, August 5, and October 10, 2003. The seasonal changes of soil respiration were also measured from May to September, 2004. The results showed that both the total and the root-wrenched soil respiration appeared single diurnal pattern, with the peaks presented during 12:00-14:00. The diurnal fluctuation of soil respiration on August 5 was smaller than that on June 17 and October 10. There were also obvious seasonal changes in total and root-wrenched soil respiration, as well as in root respiration, which were higher from June to August but lower in May and September. The average total soil respiration, root-wrenched soil respiration, and root respiration were 3.12, 1.94 and 1.18 micromol CO2 x m(-2) s(-1), respectively, and the contribution of roots to total soil respiration ranged from 26.5% to 52.6% from May to September, 2004. There were exponential correlations between respiration rate and soil temperature, and linear correlations between respiration rate and soil humidity. The Q10 values were 2.44, 2.55 and 2.27 for total soil respiration, root-wrenched soil respiration, and root respiration, respectively. The effect of soil temperature on root-wrenched soil respiration was lager than that on total soil respiration and root respiration. Soil humidity had a larger effect on total soil respiration than on root respiration and root-wrenched soil respiration. PMID:16355765

  2. Aerosol penetration behavior of respirator valves.

    PubMed

    Brosseau, L M

    1998-03-01

    Exhalation and inhalation valves from half-facepiece negative pressure respirators were evaluated for leakage during an 8-hour cyclic breathing test period using two work rates (415 and 622 kg-m/min) and two particle sizes (0.3 and 0.8 micron). Three different models (manufacturers) of exhalation valves were tested, with two lots for each model. Exhalation valve leakage ranged from 0.0 to 0.03%; no failure of exhalation valves occurred. No differences in lot or manufacturer were found. Differences in particle size did not lead to differences in penetration at the lower work rate; at the higher work rate 0.3-micron particles were less penetrating than 0.8-micron particles (0.03 versus 0.06%). When tested for air leakage at a pressure of 2.54 cm H2O, following the National Institute for Occupational Safety and Health certification method, exhalation valves exhibited no leakage either before or after the experiments. Inhalation valves averaged 20% leakage for all experiments; 0.3-micron particles were again less penetrating (13%) than 0.8-micron particles (27%). No inhalation valve failure occurred. No differences in lot (within manufacturer) were found; there were, however, significant differences in particle penetration among the three manufacturers' inhalation valves. Airflow leakage through the inhalation valves did not change during the experimental period, but differed among the three manufacturers. Measurements using airflow leakage and particle penetration produced the same ranking for the three manufacturers' inhalation valves.

  3. Service life of respirator cartridges for formaldehyde

    SciTech Connect

    Nelson, G.O.; Carlson, G.J.; Johnson, J.S.

    1981-11-20

    To date there is no NIOSH-approved air-purifying respirator which will effectively remove formaldehyde gas. Because of formaldehyde's high vapor pressure, service life values calculated using the adsorption isotherm and Wheeler equations indicate that organic vapor cartridges containing activated carbon will last less than 10 minutes at concentrations greater than 10 ppM. Studies were initiated to identify a suitable sorbent for this potentially dangerous material. The project involves the following steps: develop a method for producing relatively high concentrations (20 ppM) of a formaldehyde test mixture; verify this test concentration using the NIOSH-approved chromotropic acid wet chemical technique; and survey a wide variety of sorbents, both plain and impregnated, in hopes of identifying a suitable air-purifying cartridge for formaldehyde. A dynamic formaldehyde generation system was fabricated in which formaldehyde was produced by continuously injecting formalin using a syringe pump. The concentration was monitored using an infrared analyzer and checked using the chromotropic acid technique. Twenty-five cartridges were tested for service life at concentrations of formaldehyde gas from 7.1 to 14.8 ppM. Acid gas cartridges and those containing Pittsburgh FCA or ASC showed superior service life.

  4. Respiration in heterotrophic unicellular eukaryotic organisms.

    PubMed

    Fenchel, Tom

    2014-08-01

    Surface:volume quotient, mitochondrial volume fraction, and their distribution within cells were investigated and oxygen gradients within and outside cells were modelled. Cell surface increases allometrically with cell size. Mitochondrial volume fraction is invariant with cell size and constitutes about 10% and mitochondria are predominantly found close to the outer membrane. The results predict that for small and medium sized protozoa maximum respiration rates should be proportional to cell volume (scaling exponent ≈1) and access to intracellular O2 is not limiting except at very low ambient O2-tensions. Available data do not contradict this and some evidence supports this interpretation. Cell size is ultimately limited because an increasing fraction of the mitochondria becomes exposed to near anoxic conditions with increasing cell size. The fact that mitochondria cluster close to the cell surface and the allometric change in cell shape with increasing cell size alleviates the limitation of aerobic life at low ambient O2-tension and for large cell size.

  5. The regulatory role of ferric uptake regulator (Fur) during anaerobic respiration of Shewanella piezotolerans WP3.

    PubMed

    Yang, Xin-Wei; He, Ying; Xu, Jun; Xiao, Xiang; Wang, Feng-Ping

    2013-01-01

    Ferric uptake regulator (Fur) is a global regulator that controls bacterial iron homeostasis. In this study, a fur deletion mutant of the deep-sea bacterium Shewanella piezotolerans WP3 was constructed. Physiological studies revealed that the growth rate of this mutant under aerobic conditions was only slightly lower than that of wild type (WT), but severe growth defects were observed under anaerobic conditions when different electron acceptors (EAs) were provided. Comparative transcriptomic analysis demonstrated that Fur is involved not only in classical iron homeostasis but also in anaerobic respiration. Fur exerted pleiotropic effects on the regulation of anaerobic respiration by controlling anaerobic electron transport, the heme biosynthesis system, and the cytochrome c maturation system. Biochemical assays demonstrated that levels of c-type cytochromes were lower in the fur mutant, consistent with the transcriptional profiling. Transcriptomic analysis and electrophoretic mobility shift assays revealed a primary regulation network for Fur in WP3. These results suggest that Fur may act as a sensor for anoxic conditions to trigger and influence the anaerobic respiratory system.

  6. Effects of the Changjiang (Yangtze) River discharge on planktonic community respiration in the East China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Chung-Chi; Shiah, Fuh-Kwo; Chiang, Kuo-Ping; Gong, Gwo-Ching; Kemp, W. Michael

    2009-03-01

    Planktonic communities tend to flourish on the western margins of the East China Sea (ECS) fueled by substrates delivered largely from the Changjiang River, the fifth largest river in the world. To study the effects of the Changjiang River discharge on planktonic community respiration (CR), physical-chemical variables and key processes were measured in three consecutive summers in the ECS. Results showed that concentrations of nitrate and Chl a, protozoan biomass, bacterial production, as well as CR in the surface water were all negatively correlated with sea surface salinity, reflecting the strong influence of river discharge on the ECS shelf ecosystem. Moreover, mean values of nitrate, Chl a concentrations, and CR rates were proportionally related to the area of Changjiang diluted water (CDW; salinity ≤31.0 practical salinity units (psu)), an index of river discharge rate. Presumably, higher river flow delivers higher nutrient concentrations which stimulate phytoplankton growth, which in turn fuels CR. CR exhibited significant monthly and interannual variability, and rates appear to be dominated by bacteria and phytoplankton. Although the plankton community was relatively productive (mean = 0.8 mg C m-2 d-1) in the CDW, the mean ratio of production to respiration was low (0.42). This suggests that the heterotrophic processes regulating CR were supported by riverine organic carbon input in addition to in situ autotrophic production.

  7. Structural and Spectral Features of Selenium Nanospheres Produced by Se-Respiring Bacteria

    USGS Publications Warehouse

    Oremland, R.S.; Herbel, M.J.; Blum, J.S.; Langley, S.; Beveridge, T.J.; Ajayan, P.M.; Sutto, T.; Ellis, A.V.; Curran, S.

    2004-01-01

    Certain anaerobic bacteria respire toxic selenium oxyanions and in doing so produce extracellular accumulations of elemental selenium [Se(0)]. We examined three physiologically and phylogenetically diverse species of selenate- and selenite-respiring bacteria, Sulfurospirillum barnesii, Bacillus selenitireducens, and Selenihalanaerobacter shriftii, for the occurrence of this phenomenon. When grown with selenium oxyanions as the electron acceptor, all of these organisms formed extracellular granules consisting of stable, uniform nanospheres (diameter, ???300 nm) of Se(0) having monoclinic crystalline structures. Intracellular packets of Se(0) were also noted. The number of intracellular Se(0) packets could be reduced by first growing cells with nitrate as the electron acceptor and then adding selenite ions to washed suspensions of the nitrate-grown cells. This resulted in the formation of primarily extracellular Se nanospheres. After harvesting and cleansing of cellular debris, we observed large differences in the optical properties (UV-visible absorption and Raman spectra) of purified extracellular nanospheres produced in this manner by the three different bacterial species. The spectral properties in turn differed substantially from those of amorphous Se(0) formed by chemical oxidation of H2Se and of black, vitreous Se(0) formed chemically by reduction of selenite with ascorbate. The microbial synthesis of Se(0) nanospheres results in unique, complex, compacted nanostructural arrangements of Se atoms. These arrangements probably reflect a diversity of enzymes involved in the dissimilatory reduction that are subtly different in different microbes. Remarkably, these conditions cannot be achieved by current methods of chemical synthesis.

  8. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, Arokiasamy J.; Dodge, Cleveland J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in wastestreams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled.

  9. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, A.J.; Dodge, C.J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in waste streams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled. 4 figs.

  10. Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

    PubMed

    Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

    2016-03-01

    We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities.

  11. Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

    PubMed

    Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

    2016-03-01

    We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities. PMID:26233741

  12. Molecular characterization of bacterial respiration on minerals. Progress report, June 1992--November, 1993

    SciTech Connect

    Blake, R. II.

    1993-12-31

    Progress is reported towards elucidating electron transport components of Thiobacillus ferrooxidans involved in the metabolic oxidation of iron. Also included are results of an investigation into the molecular principles whereby the bacteria recognize and adhere to their insoluble substrates

  13. Bacterial Electron Transfer Chains Primed by Proteomics.

    PubMed

    Wessels, H J C T; de Almeida, N M; Kartal, B; Keltjens, J T

    2016-01-01

    Electron transport phosphorylation is the central mechanism for most prokaryotic species to harvest energy released in the respiration of their substrates as ATP. Microorganisms have evolved incredible variations on this principle, most of these we perhaps do not know, considering that only a fraction of the microbial richness is known. Besides these variations, microbial species may show substantial versatility in using respiratory systems. In connection herewith, regulatory mechanisms control the expression of these respiratory enzyme systems and their assembly at the translational and posttranslational levels, to optimally accommodate changes in the supply of their energy substrates. Here, we present an overview of methods and techniques from the field of proteomics to explore bacterial electron transfer chains and their regulation at levels ranging from the whole organism down to the Ångstrom scales of protein structures. From the survey of the literature on this subject, it is concluded that proteomics, indeed, has substantially contributed to our comprehending of bacterial respiratory mechanisms, often in elegant combinations with genetic and biochemical approaches. However, we also note that advanced proteomics offers a wealth of opportunities, which have not been exploited at all, or at best underexploited in hypothesis-driving and hypothesis-driven research on bacterial bioenergetics. Examples obtained from the related area of mitochondrial oxidative phosphorylation research, where the application of advanced proteomics is more common, may illustrate these opportunities. PMID:27134025

  14. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Containers for gas masks combinations shall be designed and constructed to permit easy removal of the mask. ... Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided...

  15. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Containers for gas masks combinations shall be designed and constructed to permit easy removal of the mask. ... Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided...

  16. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Containers for gas masks combinations shall be designed and constructed to permit easy removal of the mask. ... Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided...

  17. Effect of exercise level on ventilatory adaptation to respirator use.

    PubMed

    Harber, P; Shimozaki, S; Barrett, T; Fine, G

    1990-10-01

    The effect of exercise on the adaptation to an air-purifying respirator type load (dead space + inspiratory resistance) was studied in a group of 13 volunteers with a rapidly incremental exercise protocol. The difference between loaded and unloaded breathing at each exercise level was determined for each subject for a series of parameters describing the ventilatory work to overcome the respirator load pattern of breathing and metabolic work. Linear regression and t tests determined the average effect of the respirator load and the extent to which this effect was affected by the level of exercise. The inspiratory time and duty cycle were increased by the load, and exercise did not significantly affect the magnitude of this adaptation. High exercise did, however, increase the magnitude of the effect of the respiratory load on ventilatory work. These findings suggest that constraints to respiratory pattern adjustment, which may decrease respirator tolerance, occur at high exercise levels. PMID:2262825

  18. Enumeration of Organohalide Respirers in Municipal Wastewater Anaerobic Digesters

    PubMed Central

    Smith, Bryan JK; Boothe, Melissa A; Fiddler, Brice A; Lozano, Tania M; Rahi, Russel K; Krzmarzick, Mark J

    2015-01-01

    Organohalide contaminants such as triclosan and triclocarban have been well documented in municipal wastewater treatment plants (WWTPs), but the degradation of these contaminants is not well understood. One possible removal mechanism is organohalide respiration by which bacteria reduce the halogenated compound. The purpose of this study was to determine the abundance of organohalide-respiring bacteria in eight WWTP anaerobic digesters. The obligate organohalide respiring Dehalococcoides mccartyi was the most abundant and averaged 3.3 × 107 copies of 16S rRNA genes per gram, while the Dehalobacter was much lower at 2.6 × 104 copies of 16S rRNA genes per gram. The genus Sulfurospirillum spp. was also detected at 1.0 × 107 copies of 16S rRNA genes per gram. No other known or putatively organohalide-respiring strains in the Dehalococcoidaceae family were found to be present nor were the genera Desulfitobacterium or Desulfomonile. PMID:26508873

  19. EFFECT OF PREGNANCY UPON FACIAL ANTHROPOMETRICS AND RESPIRATOR FIT TESTING

    PubMed Central

    Roberge, Raymond J.; Kim, Jung-Hyun; Palmiero, Andrew; Powell, Jeffrey B.

    2016-01-01

    Workers required to wear respirators must undergo additional respirator fit testing if a significant change in body weight occurs. Approximately 10% of working women of reproductive age will be pregnant and experience a significant change in weight, yet the effect of pregnancy-associated weight gain on respirator fit is unknown. Cephalo-facial anthropometric measurements and quantitative fit testing of N95 filtering facepiece respirators (N95 FFR) of 15 pregnant women and 15 matched, non-pregnant women were undertaken for comparisons between the groups.There were no significant differences between pregnant and non-pregnant women with respect to cephalo-facial anthropometric measurements or N95 FFR quantitative fit tests. Healthy pregnant workers, who adhere to the recommended weight gain limits of pregnancy, are unlikely to experience an increase in cephalo-facial dimensions that would mandate additional N95 FFR fit testing above that which is normally required on an annual basis. PMID:26011754

  20. Effect of Pregnancy Upon Facial Anthropometrics and Respirator Fit Testing.

    PubMed

    Roberge, Raymond J; Kim, Jung-Hyun; Palmiero, Andrew; Powell, Jeffrey B

    2015-01-01

    Workers required to wear respirators must undergo additional respirator fit testing if a significant change in body weight occurs. Approximately 10% of working women of reproductive age will be pregnant and experience a significant change in weight, yet the effect of pregnancy-associated weight gain on respirator fit is unknown. Cephalo-facial anthropometric measurements and quantitative fit testing of N95 filtering facepiece respirators (N95 FFR) of 15 pregnant women and 15 matched, non-pregnant women were undertaken for comparisons between the groups. There were no significant differences between pregnant and non-pregnant women with respect to cephalo-facial anthropometric measurements or N95 FFR quantitative fit tests. Healthy pregnant workers, who adhere to the recommended weight gain limits of pregnancy, are unlikely to experience an increase in cephalo-facial dimensions that would mandate additional N95 FFR fit testing above that which is normally required on an annual basis. PMID:26011754