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Sample records for anaerobiosis

  1. Anaerobiosis induced virulence of Salmonella typhi

    DEFF Research Database (Denmark)

    Kapoor, Sarika; Singh, R D; Sharma, P C;

    2002-01-01

    BACKGROUND & OBJECTIVES: Anaerobic conditions are frequently encountered by pathogens invading the gastrointestinal tract due to low/limiting oxygen conditions prevalent in the small intestine. This anaerobic stress has been suggested to enhance the virulence of gut pathogens. In the present study......, we examined the effect of anaerobiosis on the virulence of Salmonella Typhi, a Gram negative bacteria which invades through the gut mucosa and is responsible for typhoid fever. METHODS: Salmonella Typhi (ty2) was cultured in aerobic and anaerobic conditions to compare its virulence by rabbit ileal...... loop assay, hydrophobicity assay, expression of outer membrane proteins (OMPs) and antioxidant enzymes assay. RESULTS: Anaerobically grown S. Typhi showed significantly higher cell surface hydrophobicity as compared to aerobic bacteria. In vivo toxin production by rabbit ileal loop assay also showed...

  2. EFFECT OF AERO-/ANAEROBIOSIS ON DECARBOXYLASE ACTIVITY OF SELECTED LACTIC ACID BACTERIA

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    Stanislav Kráčmar

    2010-05-01

    Full Text Available Biogenic amines are undesirable compounds produced in foods mainly through bacterial decarboxylase activity. The aim of this study was to investigate some environmental conditions (particularly aero/anaerobiosis, sodium chloride concentration (0–2% w/w, and amount of lactose (0–1% w/w on the activity of tyrosine decarboxylase enzymes of selected six technological important Lactococcus lactis strains. The levels of parameters tested were chosen according to real situation in fermented dairy products technology (especially cheese-making. Tyramine was determined by the ion-exchange chromatography with post-column ninhydrine derivatization and spectrophotometric detection. Tyrosine decarboxylation occurred during the active growth phase. Under the model conditions used, oxygen availability had influence on tyramine production, anaerobiosis seemed to favour the enzyme activity because all L. lactis strains produced higher tyramine amount. doi:10.5219/43

  3. EFFECT OF AERO-/ANAEROBIOSIS ON DECARBOXYLASE ACTIVITY OF SELECTED LACTIC ACID BACTERIA

    OpenAIRE

    Stanislav Kráčmar; Vladimír Dráb; Tereza Podešvová; Eva Pollaková; Leona Buňková; František Buňka

    2010-01-01

    Biogenic amines are undesirable compounds produced in foods mainly through bacterial decarboxylase activity. The aim of this study was to investigate some environmental conditions (particularly aero/anaerobiosis, sodium chloride concentration (0–2% w/w), and amount of lactose (0–1% w/w)) on the activity of tyrosine decarboxylase enzymes of selected six technological important Lactococcus lactis strains. The levels of parameters tested were chosen according to real situation in fer...

  4. [Photochemical activity, spectral properties, and structure of chloroplasts in leaves of Pisum sativum L. under iron deficit and root anaerobiosis].

    Science.gov (United States)

    Ladygin, V G

    2005-01-01

    A combined effect of iron deficit and root anaerobiosis on the biochemical composition, functional activity, and structure of chloroplasts in pea leaves was studied. These factors are shown to affect the chlorophyll accumulation, causing leaf chlorosis. Iron deficit makes itself evident in the chlorosis of top leaves. In the case of root anaerobiosis, chlorosis damages lower plant layers. The destructive effects are summarized under the influence of both factors. The light-harvesting complexes of photosystems are reduced to a greater degree under iron deficit; under root anaerobiosis, complexes of reaction centers of photosystem I and II are reduced. Nevertheless, even under the combined effect of these factors, all pigment-protein complexes and their functional activities are preserved in yellow leaves. The ultrastructure of chloroplasts is gradually reduced in the course of developing chlorosis. In the begging, intergranal sites of thylakoids are destroyed, which is typical for iron deficit, then granal sites are broken. However, even in yellow and almost white leaves, small thylakoids capable of forming stacking and small grana of 2-3 thylakoids are preserved. The destructive effects are summarized due to different mechanisms of action of iron deficit and root anaerobiosis on the structure and function of leaves under their combined effect. PMID:15759507

  5. Changes in the activity of ascorbate peroxidase under anaerobiosis in cocoyam (Colocasia esculenta).

    Science.gov (United States)

    Chibueze, Nwose

    2014-01-01

    This study was conducted to determine the activity of ascorbate peroxidase in the cormels of cocoyam (Colocasia esculenta var. antiquorum) immediately after harvest and in storage under anaerobiosis for one and three weeks, respectively. During stress condition in plants, hydrogen peroxide is released and mechanisms to detoxify it must be maintained. The cocoyam tubers that were neither damaged nor affected by disease were harvested from a local farm in Ugbogui, Ovia North Local Government Area in Edo State, Nigeria. The selected cocoyam tubers were peeled manually, washed with ice cold water and cut into pieces. The root tissues (50 g) were homogenised with 100 mL of ice cold 0.05 M phosphate buffer. The extract obtained was clarified by centrifugation for 15 min at 8000 g at 4 degrees C. Ascorbate-peroxidising activity was assayed using the initial rate of decrease in ascorbate concentration as measured by its absorbance at 290 nm using Milton Roy Spectron 21D. Results showed the weight of the cormels decreased all through during storage. Immediately after harvest the activity of ascorbate peroxidase was 15.49 unit mL(-1) with a significant increase (p < 0.05) after one week to 73.05 U mL(-1). Thereafter there was a significant decrease in activity of the enzyme after three weeks of storage to 33.33 U mL(-1). This increase in activity of ascorbate peroxidase after three weeks of storage may be related to increase in response to various biotic stresses. Therefore, manipulation of the capacity of cocoyam to tolerate anaerobiosis is a function of its ability to modulate the antioxidant enzymes' armory in case of need.

  6. Changes in the activity of ascorbate peroxidase under anaerobiosis in cocoyam (Colocasia esculenta).

    Science.gov (United States)

    Chibueze, Nwose

    2014-01-01

    This study was conducted to determine the activity of ascorbate peroxidase in the cormels of cocoyam (Colocasia esculenta var. antiquorum) immediately after harvest and in storage under anaerobiosis for one and three weeks, respectively. During stress condition in plants, hydrogen peroxide is released and mechanisms to detoxify it must be maintained. The cocoyam tubers that were neither damaged nor affected by disease were harvested from a local farm in Ugbogui, Ovia North Local Government Area in Edo State, Nigeria. The selected cocoyam tubers were peeled manually, washed with ice cold water and cut into pieces. The root tissues (50 g) were homogenised with 100 mL of ice cold 0.05 M phosphate buffer. The extract obtained was clarified by centrifugation for 15 min at 8000 g at 4 degrees C. Ascorbate-peroxidising activity was assayed using the initial rate of decrease in ascorbate concentration as measured by its absorbance at 290 nm using Milton Roy Spectron 21D. Results showed the weight of the cormels decreased all through during storage. Immediately after harvest the activity of ascorbate peroxidase was 15.49 unit mL(-1) with a significant increase (p < 0.05) after one week to 73.05 U mL(-1). Thereafter there was a significant decrease in activity of the enzyme after three weeks of storage to 33.33 U mL(-1). This increase in activity of ascorbate peroxidase after three weeks of storage may be related to increase in response to various biotic stresses. Therefore, manipulation of the capacity of cocoyam to tolerate anaerobiosis is a function of its ability to modulate the antioxidant enzymes' armory in case of need. PMID:24783794

  7. Feasibility of installing and maintaining anaerobiosis using Escherichia coli HD701 as a facultative anaerobe for hydrogen production by Clostridium acetobutylicum ATCC 824 from various carbohydrates.

    Science.gov (United States)

    Hassan, Sedky H A; Morsy, Fatthy Mohamed

    2015-12-01

    Using Escherichia coli for installing and maintaining anaerobiosis for hydrogen production by Clostridium acetobutylicum ATCC 824 is a cost-effective approach for industrial hydrogen production, as it does not require reducing agents or sparging with inert gases. This study was devoted for investigating the feasibility for installing and maintaining anaerobiosis of hydrogen production by C. acetobutylicum ATCC 824 when using E. coli HD701 utilizable versus non utilizable sugars as a-carbon source. Using E. coli HD701 for installing anaerobiosis showed a comparable hydrogen production yield and efficiency to the use of reducing agents and nitrogen sparging in case of hydrogen production from the E. coli HD701 non utilizable sugars. In contrast, using E. coli HD701 for installing anaerobiosis showed a lower hydrogen production yield and efficiency than the use of reducing agents and nitrogen sparging in case of using glucose as a substrate. This is possibly because E. coli HD701 when using glucose compensate for the substrate, and produce hydrogen with lower efficiency than C. acetobutylicum ATCC 824. These results indicated that the use of E. coli HD701 for installing anaerobiosis would not be economically feasible when using E. coli HD701 utilizable sugars as a carbon source. In contrast, the use of this approach for installing anaerobiosis for hydrogen production from sucrose and starch would have a high potency for industrial applications.

  8. Acetate versus sulfur deprivation role in creating anaerobiosis in light for hydrogen production by Chlamydomonas reinhardtii and Spirulina platensis: two different organisms and two different mechanisms.

    Science.gov (United States)

    Morsy, Fatthy Mohamed

    2011-01-01

    This work was devoted to separate acetate role in creating anaerobiosis from that of sulfur deprivation. Chlamydomonas reinhardtii grown in TAP (Tris-acetate-phosphate) medium was resuspended in sulfur-replete or -deprived medium in sealed or nonsealed cultures. Sulfur deprivation was substantial for starch accumulation and hydrogen evolution; however, acetate induced anaerobiosis in the presence or absence of sulfur in only sealed cultures. In nonsealed cultures, Chlamydomonas did not lose its photosynthetic activity; however, it was arrested in anoxia with no photosynthetic activity as long as the culture was sealed. The sealed cultures resumed photosynthesis upon unsealing overnight unless the cells died by anoxia at late stage of the experiment. These results indicate that the enhanced oxygen consumption for the enormous acetate respiration and inhibition of the external oxygen supply in sealed cultures of Chlamydomonas are the main reasons for the steady anaerobic conditions. Although acetate was substantial for creating anaerobiosis in Chlamydomonas, sulfur deprivation alone could create anaerobiosis in Spirulina platensis grown autotrophically. Hydrogen evolution and glycogen accumulation were induced under such conditions. Severely reduced phycocyanin, chlorophyll and photosynthesis, while respiration had increased, induced anaerobiosis in Spirulina. This study reports for the first time anaerobiosis under autotrophic conditions in a cyanobacterium.

  9. Inhibition, in anaerobiosis, of the reaction of stomatal closure of Pelargonium in the presence of SO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Bonte, J.; De Cormis, L.; Louguet, P.

    1977-01-01

    The temporary stomatal closing movement of Pelargonium x hortorum induced by exposure to an atmospheric concentration of sulfur dioxide (2 x 10/sup -6/ v/v) is completely inhibited in anaerobiosis, in light as in darkness. These results suggest that SO/sub 2/ has a direct action on the stomatal cells. The significance of these experiments on the theory of the mechanism of stomatal movement is emphasized.

  10. Combined effect of anaerobiosis, low pH and cold temperatures on the growth capacities of psychrotrophic Bacillus cereus.

    Science.gov (United States)

    Guérin, Alizée; Dargaignaratz, Claire; Broussolle, Véronique; Clavel, Thierry; Nguyen-The, Christophe

    2016-10-01

    Psychrotrophic strains of the foodborne pathogen Bacillus cereus can multiply during the refrigerated storage of food products. The aim of this study was to determine the impact of anaerobiosis on the growth of two psychrotrophic B. cereus strains exposed to acidic pH at a cold temperature in a laboratory medium. At 10 °C, growth occurred at pH values equal to or higher than 5.7 during anaerobiosis, whereas aerobic growth was observed from pH 5.4. Growth rates during aerobiosis were similar at pH 5.4 and pH 7. No growth was observed for the two tested strains at 8 °C without oxygen regardless of the pH; however, both strains grew at this temperature from pH 5.4 in the presence of oxygen. These pH growth limits in aerobiosis are consistent with those reported for different strains and different foods or media, but no other studies have described anaerobic growth at acidic pH values. The maximal B. cereus concentration was approximately 6.0 log10 CFU/ml for cultures in the absence of oxygen and approximately 8.0 log10 CFU/ml for cultures in the presence of oxygen. In conclusion, we found that the combination of anaerobiosis, pH < 5.7 at 10 °C, or anaerobiosis and temperatures ≤8 °C prevent psychrotrophic B. cereus growth. PMID:27375252

  11. The HU regulon is composed of genes responding to anaerobiosis, acid stress, high osmolarity and SOS induction.

    Directory of Open Access Journals (Sweden)

    Jacques Oberto

    Full Text Available BACKGROUND: The Escherichia coli heterodimeric HU protein is a small DNA-bending protein associated with the bacterial nucleoid. It can introduce negative supercoils into closed circular DNA in the presence of topoisomerase I. Cells lacking HU grow very poorly and display many phenotypes. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the transcription profile of every Escherichia coli gene in the absence of one or both HU subunits. This genome-wide in silico transcriptomic approach, performed in parallel with in vivo genetic experimentation, defined the HU regulon. This large regulon, which comprises 8% of the genome, is composed of four biologically relevant gene classes whose regulation responds to anaerobiosis, acid stress, high osmolarity, and SOS induction. CONCLUSIONS/SIGNIFICANCE: The regulation a large number of genes encoding enzymes involved in energy metabolism and catabolism pathways by HU explains the highly pleiotropic phenotype of HU-deficient cells. The uniform chromosomal distribution of the many operons regulated by HU strongly suggests that the transcriptional and nucleoid architectural functions of HU constitute two aspects of a unique protein-DNA interaction mechanism.

  12. Anaerobiosis induced state transition: a non photochemical reduction of PQ pool mediated by NDH in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Sreedhar Nellaepalli

    Full Text Available BACKGROUND: Non photochemical reduction of PQ pool and mobilization of LHCII between PSII and PSI are found to be linked under abiotic stress conditions. The interaction of non photochemical reduction of PQ pool and state transitions associated physiological changes are critically important under anaerobic condition in higher plants. METHODOLOGY/FINDINGS: The present study focused on the effect of anaerobiosis on non-photochemical reduction of PQ pool which trigger state II transition in Arabidopsis thaliana. Upon exposure to dark-anaerobic condition the shape of the OJIP transient rise is completely altered where as in aerobic treated leaves the rise is unaltered. Rise in F(o and F(J was due to the loss of oxidized PQ pool as the PQ pool becomes more reduced. The increase in F(o' was due to the non photochemical reduction of PQ pool which activated STN7 kinase and induced LHCII phosphorylation under anaerobic condition. Further, it was observed that the phosphorylated LHCII is migrated and associated with PSI supercomplex increasing its absorption cross-section. Furthermore, evidences from crr2-2 (NDH mutant and pgr5 mutants (deficient in non NDH pathway of cyclic electron transport have indicated that NDH is responsible for non photochemical reduction of the PQ pool. We propose that dark anaerobic condition accelerates production of reducing equivalents (such as NADPH by various metabolic pathways which reduce PQ pool and is mediated by NDH leading to state II transition. CONCLUSIONS/SIGNIFICANCE: Anaerobic condition triggers non photochemical reduction of PQ pool mediated by NDH complex. The reduced PQ pool activates STN7 kinase leading to state II transition in A. thaliana.

  13. Corrosion protection by anaerobiosis.

    Science.gov (United States)

    Volkland, H P; Harms, H; Wanner; Zehnder, A J

    2001-01-01

    Biofilm-forming bacteria can protect mild (unalloyed) steel from corrosion. Mild steel coupons incubated with Rhodoccocus sp. strain C125 and Pseudomonas putida mt2 in an aerobic phosphate-buffered medium containing benzoate as carbon and energy source, underwent a surface reaction leading to the formation of a corrosion-inhibiting vivianite layer [Fe3(PO4)2]. Electrochemical potential (E) measurements allowed us to follow the buildup of the vivianite cover. The presence of sufficient metabolically active bacteria at the steel surface resulted in an E decrease to -510 mV, the potential of free iron, and a continuous release of ferrous iron. Part of the dissolved iron precipitated as vivianite in a compact layer of two to three microns in thickness. This layer prevented corrosion of mild steel for over two weeks, even in a highly corrosive medium. A concentration of 20 mM phosphate in the medium was found to be a prerequisite for the formation of the vivianite layer.

  14. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Directory of Open Access Journals (Sweden)

    Bart Ghysels

    Full Text Available Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment.

  15. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Science.gov (United States)

    Ghysels, Bart; Godaux, Damien; Matagne, René F; Cardol, Pierre; Franck, Fabrice

    2013-01-01

    Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment. PMID:23717558

  16. Microbial Ecology of Anaerobic Digesters: The Key Players of Anaerobiosis

    Directory of Open Access Journals (Sweden)

    Fayyaz Ali Shah

    2014-01-01

    Full Text Available Anaerobic digestion is the method of wastes treatment aimed at a reduction of their hazardous effects on the biosphere. The mutualistic behavior of various anaerobic microorganisms results in the decomposition of complex organic substances into simple, chemically stabilized compounds, mainly methane and CO2. The conversions of complex organic compounds to CH4 and CO2 are possible due to the cooperation of four different groups of microorganisms, that is, fermentative, syntrophic, acetogenic, and methanogenic bacteria. Microbes adopt various pathways to evade from the unfavorable conditions in the anaerobic digester like competition between sulfate reducing bacteria (SRB and methane forming bacteria for the same substrate. Methanosarcina are able to use both acetoclastic and hydrogenotrophic pathways for methane production. This review highlights the cellulosic microorganisms, structure of cellulose, inoculum to substrate ratio, and source of inoculum and its effect on methanogenesis. The molecular techniques such as DGGE (denaturing gradient gel electrophoresis utilized for dynamic changes in microbial communities and FISH (fluorescent in situ hybridization that deal with taxonomy and interaction and distribution of tropic groups used are also discussed.

  17. Modelling soil anaerobiosis from water retention characteristics and soil respiration

    NARCIS (Netherlands)

    Schurgers, G.; Dörsch, P.; Bakken, L.; Leffelaar, P.A.; Egil Haugen, L.

    2006-01-01

    Oxygen is a prerequisite for some and an inhibitor to other microbial functions in soils, hence the temporal and spatial distribution of oxygen within the soil matrix is crucial in soil biogeochemistry and soil biology. Various attempts have been made to model the anaerobic fraction of the soil volu

  18. EFFECT OF ANAEROBIOSIS ON FILTER MEDIA POLLUTANT RETENTION

    Science.gov (United States)

    This paper presents the results of experiments conducted to determine if four potential filter media (sand, activated carbon, peat moss, and compost) could retain previously-trapped pollutants even under anaerobic conditions. The results indicated that permanent retention of heav...

  19. Effect of anaerobiosis on indigenous microorganisms in blackwater with fish offal as co-substrate

    DEFF Research Database (Denmark)

    Gunnarsdottir, Ragnhildur; Heiske, Stefan; Jensen, Pernille Erland;

    2014-01-01

    . Addition of fish offal had no effect on survival of coliphages. The results of the recovery study indicated that a fraction of the E. coli in the aerobic blackwater sample and of the faecal streptococci in both the anaerobic and aerobic samples containing blackwater and Greenlandic Halibut were injured......The aim of this study was to compare the effect of mesophilic anaerobic digestion with aerobic storage on the survival of selected indigenous microorganisms and microbial groups in blackwater, including the effect of addition of Greenlandic Halibut and shrimp offal. The methane yield...... of the different substrate mixtures was determined in batch experiments to study possible correlation between methanogenic activity in the anaerobic digesters and reduction of indigenous microorganisms in the blackwater. By the end of the experiments a recovery study was conducted to determine possible injury...

  20. Alternative photosynthetic electron transport pathways during anaerobiosis in the green alga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Hemschemeier, Anja; Happe, Thomas

    2011-08-01

    Oxygenic photosynthesis uses light as energy source to generate an oxidant powerful enough to oxidize water into oxygen, electrons and protons. Upon linear electron transport, electrons extracted from water are used to reduce NADP(+) to NADPH. The oxygen molecule has been integrated into the cellular metabolism, both as the most efficient electron acceptor during respiratory electron transport and as oxidant and/or "substrate" in a number of biosynthetic pathways. Though photosynthesis of higher plants, algae and cyanobacteria produces oxygen, there are conditions under which this type of photosynthesis operates under hypoxic or anaerobic conditions. In the unicellular green alga Chlamydomonas reinhardtii, this condition is induced by sulfur deficiency, and it results in the production of molecular hydrogen. Research on this biotechnologically relevant phenomenon has contributed largely to new insights into additional pathways of photosynthetic electron transport, which extend the former concept of linear electron flow by far. This review summarizes the recent knowledge about various electron sources and sinks of oxygenic photosynthesis besides water and NADP(+) in the context of their contribution to hydrogen photoproduction by C. reinhardtii. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts. PMID:21376011

  1. The utilization of glycogen and accumulation of some intermediates during anaerobiosis in Mytilus edulis L.

    NARCIS (Netherlands)

    Zwaan, A.; Zandee, D.I.

    1972-01-01

    1. 1. Glycogen degradation in the mussel under anaerobic conditions was measured at two temperatures. Glycogen decrease at 6·6°C was about 3 mg and at 20°C about 6 mg/24 hr per mussel. A Pasteur effect was observed. 2. 2. The decrease of glycogen was almost entirely restricted to muscles, including

  2. Use of an Innovative Simple Method for Anaerobiosis in the Diagnosis and Management of Infections in Two Unusual Cases.

    Science.gov (United States)

    Haldar, J; Pal, N; Ray, R; Maiti, P K

    2016-01-01

    Technical limitations restrict routine anaerobe isolation from clinical materials in resource-limited laboratories. An innovative two steps combustion candle jar technique may be suitable for such setup. This system was tried with one case of chronic osteomyelitis developed on supracondyler compound fracture. Porphyromonas spp. was isolated and identified. Vancomycin was recommended based on in vitro sensitivity test, but the leg was amputed after receiving a resistant drug gentamycin. While in another child with hydrocephalous, V-P shunt associated infection by Peptostreptococcus anaerobius was successfully controlled by sensitive drug vancomycin. These two eye-opener cases insisted us for large scale application of the technique. PMID:27144078

  3. Genes de Vibrio cholerae involucrados en la tolerancia al cobre

    Directory of Open Access Journals (Sweden)

    Karen Marrero

    2010-01-01

    sensibilidad a cobre en aerobiosis y anaerobiosis. El principal sistema de resistencia a cobre en V. cholerae está constituido por la ATPasa transportadora de cationes CopA, codificada por VC2215, que funciona en aerobiosis y anaerobiosis. La proteína hipotética conservada codificada por VC2216 no es significativa en la resistencia a cobre en aerobiosis, pero en anaerobiosis es importante si CopA es funcional. La proteína codificada por los genes VCA0261-0260, anotados previamente como independientes, es importante en aerobiosis y a una alta concentración de cobre, pero en anaerobiosis su participación en la resistencia a cobre es solo evidente si CopA no es funcional. De esta manera, los sistemas de tolerancia a cobre en V. cholerae incluyen el producto de los genes VC2215, VC2216 y VCA0261-0260, que desempeñan diferentes funciones en diversas condiciones de cultivo.

  4. Methanogenic Food Web in Gut Contents of the Methane-Emitting Earthworm Eudrilus eugeniae from Brazil

    NARCIS (Netherlands)

    Schulz, Kristin; Hunger, S.; Brown, G.G.; Tsai, S.M.; Cerri, C.C.; Conrad, R.; Drake, H.

    2015-01-01

    The anoxic saccharide-rich conditions of the earthworm gut provide an ideal transient habitat for ingested microbes capable of anaerobiosis. It was recently discovered that the earthworm Eudrilus eugeniae from Brazil can emit methane (CH4) and that ingested methanogens might be associated with this

  5. Flooding and Plant Growth

    OpenAIRE

    Visser, E.J.W.; Voesenek, L.A.C.J.; VARTAPETIAN, B. B.; Jackson, M B

    2003-01-01

    This Special Issue is based on the 7th Conference of the International Society for Plant Anaerobiosis (ISPA), held in Nijmegen, The Netherlands, 12–16 June 2001. The papers describe and analyse many of the responses that plants display when subjected to waterlogging of the soil or deeper submergence. These responses may be injurious or adaptive, and are discussed at various levels of organizational complexity ranging from ecosystem processes, through individual plants to single cells. The res...

  6. A brief history of bacterial growth physiology

    OpenAIRE

    Schaechter, Moselio

    2015-01-01

    Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid-19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers o...

  7. Photosynthetic water splitting for hydrogen fuel synthesis

    Science.gov (United States)

    Greenbaum, E.

    Three key advances in photosynthesis research are reported. A significant advance in microalgal water splitting has been made. In the linear, low-intensity region of the light saturation curves, equivalent solar conversion efficiencies of 10% have been measured. A technological advance in the ability to genetically screen individual algal colonies has been made. Successive subcultures of anaerobiosis-stressed Chlamydomonas reinhardtii exhibited enhanced capacity for photoproduction of hydrogen and oxygen.

  8. A novel screening method for hydrogenase-deficient mutants in Chlamydomonas reinhardtii based on in vivo chlorophyll fluorescence and photosystem II quantum yield

    OpenAIRE

    Godaux, Damien; Emonds-Alt, Barbara; Berne, Nicolas; Ghysels, Bart(*); Alric, Jean; Remacle, Claire; Cardol, Pierre

    2013-01-01

    In Chlamydomonas reinhardtii, prolonged anaerobiosis leads to the expression of enzymes Received 30 August 2012 belonging to various fermentative pathways. Among them, oxygen-sensitive hydrogenases Received in revised form (HydA1/2) catalyze the synthesis of molecular hydrogen from protons and reduced ferre- 12 November 2012 doxin in the stroma. In this work, by analyzing wild type and mutants affected in H2 Accepted 16 November 2012 production, we show that maximal PSII photosynt...

  9. Analytical approaches to photobiological hydrogen production in unicellular green algae

    OpenAIRE

    Hemschemeier, Anja; Melis, Anastasios; Happe, Thomas

    2009-01-01

    Several species of unicellular green algae, such as the model green microalga Chlamydomonas reinhardtii, can operate under either aerobic photosynthesis or anaerobic metabolism conditions. A particularly interesting metabolic condition is that of “anaerobic oxygenic photosynthesis”, whereby photosynthetically generated oxygen is consumed by the cell’s own respiration, causing anaerobiosis in the culture in the light, and induction of the cellular “hydrogen metabolism” process. The latter enta...

  10. SFH2 regulates fatty acid synthase activity in the yeast Saccharomyces cerevisiae and is critical to prevent saturated fatty acid accumulation in response to haem and oleic acid depletion

    OpenAIRE

    Desfougères, Thomas; Ferreira, Thierry; Bergès, Thierry; Régnacq, Matthieu

    2007-01-01

    Abstract The yeast Saccharomyces cerevisiae is a facultative anaerobic organism. In anaerobiosis, sustained growth relies on the presence of exogenously supplied unsaturated fatty acids and ergosterol that yeast is unable to synthesize in the absence of oxygen or upon haem depletion. In the absence of exogenous supplementation with unsaturated fatty acid, a net accumulation of saturated fatty acid (SFA) is observed that induces significant modification of phospholipid profile [1]. ...

  11. Flexibility in Anaerobic Metabolism as Revealed in a Mutant of Chlamydomonas reinhardtii Lacking Hydrogenase Activity*S⃞

    OpenAIRE

    Dubini, Alexandra; Mus, Florence; Seibert, Michael; Grossman, Arthur R.; Posewitz, Matthew C.

    2009-01-01

    The green alga Chlamydomonas reinhardtii has a network of fermentation pathways that become active when cells acclimate to anoxia. Hydrogenase activity is an important component of this metabolism, and we have compared metabolic and regulatory responses that accompany anaerobiosis in wild-type C. reinhardtii cells and a null mutant strain for the HYDEF gene (hydEF-1 mutant), which encodes an [FeFe] hydrogenase maturation protein. This mutant has no hydrogenase activity...

  12. Photostimulation of H2 production in the green alga Chlamydomonas reinhardtii upon photoinhibition of its O2-evolving system

    International Nuclear Information System (INIS)

    A brief exposure (15-30 min) of green alga Chlamydomonas reinhardtii cells to high intensity light (100 W·m-2) was accompanied by rapid suppression of photosynthetic O2 evolution. The decline in the rate of O2 evolution was accompanied by stimulation of H2 production. The effect was dependent on cell suspension density, culture age, and light intensity. It appears that photoinhibition of photosynthetic O2 evolution led to anaerobiosis that is favorable for H2 production. (author)

  13. The Involvement of hybrid cluster protein 4, HCP4, in Anaerobic Metabolism in Chlamydomonas reinhardtii

    OpenAIRE

    Olson, Adam C.; Carter, Clay J

    2016-01-01

    The unicellular green algae Chlamydomonas reinhardtii has long been studied for its unique fermentation pathways and has been evaluated as a candidate organism for biofuel production. Fermentation in C. reinhardtii is facilitated by a network of three predominant pathways producing four major byproducts: formate, ethanol, acetate and hydrogen. Previous microarray studies identified many genes as being highly up-regulated during anaerobiosis. For example, hybrid cluster protein 4 (HCP4) was fo...

  14. Cadmium removal by Euglena gracilis is enhanced under anaerobic growth conditions

    Energy Technology Data Exchange (ETDEWEB)

    Santiago-Martínez, M. Geovanni; Lira-Silva, Elizabeth; Encalada, Rusely; Pineda, Erika; Gallardo-Pérez, Juan Carlos [Departamento de Bioquímica, Instituto Nacional de Cardiología (Mexico); Zepeda-Rodriguez, Armando [Facultad de Medicina, UNAM, Mexico City (Mexico); Moreno-Sánchez, Rafael; Saavedra, Emma [Departamento de Bioquímica, Instituto Nacional de Cardiología (Mexico); Jasso-Chávez, Ricardo, E-mail: rjass_cardiol@yahoo.com.mx [Departamento de Bioquímica, Instituto Nacional de Cardiología (Mexico)

    2015-05-15

    Highlights: • The protist Euglena gracilis had the ability to grow and remove large amounts of Cd{sup 2+} under anaerobic conditions. • High biomass was attained by combination of glycolytic and mitochondrial carbon sources. • Routes of degradation of glucose, glutamate and malate under anaerobic conditions in E. gracilis are described. • Biosorption was the main mechanism of Cd{sup 2+} removal in anaerobiosis, whereas the Cd{sup 2+} intracellularly accumulated was inactivated by thiol-molecules and polyphosphate. - Abstract: The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd{sup 2+}) and biochemically characterized. High biomass (8.5 × 10{sup 6} cells mL{sup −1}) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic environment of 0.7% O{sub 2}, which was sufficient to allow mitochondrial respiratory activity: glutamate and malate were fully consumed, whereas 25–33% of the added glucose was consumed. In anaerobic cells, photosynthesis but not respiration was activated by Cd{sup 2+} which induced higher oxidative stress. Malondialdehyde (MDA) levels were 20 times lower in control cells under anaerobiosis than in aerobiosis, although Cd{sup 2+} induced a higher MDA production. Cd{sup 2+} stress induced increased contents of chelating thiols (cysteine, glutathione and phytochelatins) and polyphosphate. Biosorption (90%) and intracellular accumulation (30%) were the mechanisms by which anaerobic cells removed Cd{sup 2+} from medium, which was 36% higher versus aerobic cells. The present study indicated that E. gracilis has the ability to remove Cd{sup 2+} under anaerobic conditions, which might be advantageous for metal removal in sediments from polluted water bodies or bioreactors, where the O{sub 2} concentration is particularly low.

  15. Manganese Oxidation by Bacteria: Biogeochemical Aspects

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; LokaBharathi, P.A.

    and protection against oxidative stress in bacteria (Christianson 1997 and Spiro et al. 2010). It is important for general metabolism, carbohydrate metabolism and for both anabolic and catabolic functions in anaerobiosis and aerobiosis (Crowley et al. 2000... in biochemical processes in rivers must be great but require further investigations to know about their nutritional needs, metabolism and enzymatic systems. Knowing the importance of Mn 2+ oxidation by bacteria Johnson and Stokes (1966) readily stated...

  16. Cadmium removal by Euglena gracilis is enhanced under anaerobic growth conditions.

    Science.gov (United States)

    Santiago-Martínez, M Geovanni; Lira-Silva, Elizabeth; Encalada, Rusely; Pineda, Erika; Gallardo-Pérez, Juan Carlos; Zepeda-Rodriguez, Armando; Moreno-Sánchez, Rafael; Saavedra, Emma; Jasso-Chávez, Ricardo

    2015-05-15

    The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd(2+)) and biochemically characterized. High biomass (8.5×10(6)cellsmL(-1)) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic environment of 0.7% O₂, which was sufficient to allow mitochondrial respiratory activity: glutamate and malate were fully consumed, whereas 25-33% of the added glucose was consumed. In anaerobic cells, photosynthesis but not respiration was activated by Cd(2+) which induced higher oxidative stress. Malondialdehyde (MDA) levels were 20 times lower in control cells under anaerobiosis than in aerobiosis, although Cd(2+) induced a higher MDA production. Cd(2+) stress induced increased contents of chelating thiols (cysteine, glutathione and phytochelatins) and polyphosphate. Biosorption (90%) and intracellular accumulation (30%) were the mechanisms by which anaerobic cells removed Cd(2+) from medium, which was 36% higher versus aerobic cells. The present study indicated that E. gracilis has the ability to remove Cd(2+) under anaerobic conditions, which might be advantageous for metal removal in sediments from polluted water bodies or bioreactors, where the O₂ concentration is particularly low. PMID:25698571

  17. Time dynamics of the Bacillus cereus exoproteome are shaped by cellular oxidation.

    Science.gov (United States)

    Madeira, Jean-Paul; Alpha-Bazin, Béatrice; Armengaud, Jean; Duport, Catherine

    2015-01-01

    At low density, Bacillus cereus cells release a large variety of proteins into the extracellular medium when cultivated in pH-regulated, glucose-containing minimal medium, either in the presence or absence of oxygen. The majority of these exoproteins are putative virulence factors, including toxin-related proteins. Here, B. cereus exoproteome time courses were monitored by nanoLC-MS/MS under low-oxidoreduction potential (ORP) anaerobiosis, high-ORP anaerobiosis, and aerobiosis, with a specific focus on oxidative-induced post-translational modifications of methionine residues. Principal component analysis (PCA) of the exoproteome dynamics indicated that toxin-related proteins were the most representative of the exoproteome changes, both in terms of protein abundance and their methionine sulfoxide (Met(O)) content. PCA also revealed an interesting interconnection between toxin-, metabolism-, and oxidative stress-related proteins, suggesting that the abundance level of toxin-related proteins, and their Met(O) content in the B. cereus exoproteome, reflected the cellular oxidation under both aerobiosis and anaerobiosis.

  18. Effect of the absence of the CcpA gene on growth, metabolic production, and stress tolerance in Lactobacillus delbrueckii ssp. bulgaricus.

    Science.gov (United States)

    Li, C; Sun, J W; Zhang, G F; Liu, L B

    2016-01-01

    The catabolite control protein A (CcpA) is a kind of multi-effect regulatory protein. In the study, the effect of the inactivation of CcpA and aerobic conditions on the growth, metabolic production, and stress tolerance to heat, oxidative, and cold stresses in Lactobacillus delbrueckii ssp. bulgaricus was investigated. Results showed that inactivation of CcpA distinctly hindered growth. Total lactic acid concentration was significantly lower in aerobiosis for both strains and was lower for the mutant strain than L. bulgaricus. Acetic acid production from the mutant strain was higher than L. bulgaricus in aerobiosis compared with anaerobiosis. Enzyme activities, lactate dehydrogenase (LDH), phosphate fructose kinase (PFK), pyruvate kinase (PK), and pyruvic dehydrogenase (PDH), were significantly lower in the mutant strain than L. bulgaricus. The diameters of inhibition zone were 13.59 ± 0.02 mm and 9.76 ± 0.02 mm for L. bulgaricus in anaerobiosis and aerobiosis, respectively; and 8.12 ± 0.02 mm and 7.38 ± 0.02 mm for the mutant in anaerobiosis and aerobiosis, respectively. For both strains, cells grown under aerobic environment possess more stress tolerance. This is the first study in which the CcpA-negative mutant of L. bulgaricus is constructed and the effect of aerobic growth on stress tolerance of L. bulgaricus is evaluated. Although aerobic cultivation does not significantly improve growth, it does improve stress tolerance.

  19. Time dynamics of the Bacillus cereus exoproteome are shaped by cellular oxidation

    Directory of Open Access Journals (Sweden)

    Jean-Paul eMadeira

    2015-04-01

    Full Text Available At low density, Bacillus cereus cells release a large variety of proteins into the extracellular medium when cultivated in pH-regulated, glucose-containing minimal medium, either in the presence or absence of oxygen. The majority of these exoproteins are putative virulence factors, including toxin-related proteins. Here, B. cereus exoproteome time courses were monitored by nanoLC-MS/MS under low-oxidoreduction potential (ORP anaerobiosis, high-ORP anaerobiosis, and aerobiosis, with a specific focus on oxidative-induced post-translational modifications of methionine residues. Principal component analysis (PCA of the exoproteome dynamics indicated that toxin-related proteins were the most representative of the exoproteome changes, both in terms of protein abundance and their methionine sulfoxide (Met(O content. PCA also revealed an interesting interconnection between toxin-, metabolism-, and oxidative stress–related proteins, suggesting that the abundance level of toxin-related proteins, and their Met(O content in the B. cereus exoproteome, reflected the cellular oxidation under both aerobiosis and anaerobiosis.

  20. Mechanisms of appearance of the Pasteur effect in Saccharomyces cerevisiae: inactivation of sugar transport systems.

    Science.gov (United States)

    Lagunas, R; Dominguez, C; Busturia, A; Sáez, M J

    1982-10-01

    Saccharomyces cerevisiae does not show a noticeable Pasteur effect (activation of sugar catabolism by anaerobiosis) when growing with an excess of sugar and nitrogen source, but it does do so after exhaustion of the nitrogen source in the medium (resting state). We have found that this different behavior of growing and resting S. cerevisiae seems due to differences in the contribution of respiration to catabolism under both states. Growing S. cerevisiae respired only 3 to 20% of the catabolized sugar, depending on the sugar present; the remainder was fermented. In contrast, resting S. cerevisiae respired as much as 25 to 100% of the catabolized sugar. These results suggest that a shift to anaerobiosis would have much greater energetic consequences in resting than in growing S. cerevisiae. In resting S. cerevisiae anaerobiosis would strongly decrease the formation of ATP; as a consequence, various regulatory mechanisms would switch on, producing the observed increase of the rate of glycolysis. The greater significance that respiration reached in resting cells was not due to an increase of the respiratory capacity itself, but to a loss of fermentation which turned respiration into the main catabolic pathway. The main mechanism involved in the loss of fermentation observed during nitrogen starvation was a progressive inactivation of the sugar transport systems that reduced the rate of fermentation to less than 10% of the value observed in growing cells. Inactivation of the sugar transports seems a consequence of the turnover of the sugar carriers whose apparent half-lives were 2 to 7 h.

  1. Obtención y caracterización de mutantes fnr derivados de una cepa de Vibrio cholerae El Tor

    Directory of Open Access Journals (Sweden)

    Karen Marrero-Domínguez

    2013-01-01

    Full Text Available La bacteria anaerobia facultativa Vibrio cholerae es el agente causal del cólera. Su patogénesis comprende, entre otros procesos, la motilidad, la adherencia y la producción de la toxina del cólera y el pilus de expresión coregulada con la toxina, dos factores de virulencia esenciales. Trabajos previos invitro han mostrado que la expresión de los factores de virulencia en este microorganismo es diferencial y ocurre en respuesta a bajas tensiones de oxígeno; sin embargo, todos los reguladores que median esta respuesta no se conocen. La adaptación bacteriana al crecimiento en bajas concentraciones de oxígeno involucra a varios sistemas reguladores globales, entre los que se encuentra la proteína reguladora FNR (del inglés, Fumarate and Nitrate Reduction . El objetivo de este trabajo fue obtener mutantes en el genfnr derivados de una cepa de V. cholerae del biotipo El Tor y caracterizarlos invitro en cuanto a la producción de la toxina del cólera y el pilusco regulado con ella, así como la motilidad. Para esto, se obtuvieron dos mutantes que contenían al gen fnr parcialmente delecionado. La caracterización de estos mutantes arrojó que el regulador FNR activa específicamente la expresión de la toxina del cólera y no del pilus coregulado con la toxina en V. cholerae El Tor crecido en medio Syncase y anaerobiosis. Además, se encontró que este regulador contribuye a la motilidad de V. cholerae en anaerobiosis. Estos resultados identifican a FNR como un regulador involucrado en el control de la virulencia de V. cholerae en respuesta a la anaerobiosis, una señal fisiológicamente importante in vivo.

  2. Growth of silicone-immobilized bacteria on polycarbonate membrane filters, a technique to study microcolony formation under anaerobic conditions

    DEFF Research Database (Denmark)

    Højberg, Ole; Binnerup, S. J.; Sørensen, Jan

    1997-01-01

    A technique was developed to study microcolony formation by silicone- immobilized bacteria on polycarbonate membrane filters under anaerobic conditions. A sudden shift to anaerobiosis was obtained by submerging the filters in medium which was depleted for oxygen by a pure culture of bacteria....... The technique was used to demonstrate that preinduction of nitrate reductase under low-oxygen conditions was necessary for nonfermenting, nitrate-respiring bacteria, e.g., Pseudomonas spp., to cope with a sudden lack of oxygen. In contrast, nitrate-respiring, fermenting bacteria, e.g., Bacillus and Escherichia...

  3. Ecological study of bacteriophages of Vibrio natriegens

    Energy Technology Data Exchange (ETDEWEB)

    Zachary, A.

    1978-03-01

    Effects of temperature and anaerobic conditions on the replication of two bacteriophages, nt-1 and nt-6, of the estuarine bacterium Vibrio natriegens were studied. Reduction in temperature resulted in longer latent periods and reduced burst sizes for both phages. Replication under anaerobic conditions resulted in longer latent periods; however, phage nt-6 had a reduced burst size, whereas phage nt-1 had an increased burst size, resulting in a rate of phage production nearly equal to that observed under aerobic conditions. Therefore the distribution of the phages in marsh areas could be influenced by temperature and anaerobiosis.

  4. Metabolic-State-Dependent Remodeling of the Transcriptome in Response to Anoxia and Subsequent Reoxygenation in Saccharomyces cerevisiae†

    OpenAIRE

    Lai, Liang-Chuan; Kosorukoff, Alexander L.; Burke, Patricia V.; Kwast, Kurt E.

    2006-01-01

    We conducted a comprehensive genomic analysis of the temporal response of yeast to anaerobiosis (six generations) and subsequent aerobic recovery (≈2 generations) to reveal metabolic-state (galactose versus glucose)-dependent differences in gene network activity and function. Analysis of variance showed that far fewer genes responded (raw P value of ≤10−8) to the O2 shifts in glucose (1,603 genes) than in galactose (2,388 genes). Gene network analysis reveals that this difference is due large...

  5. Ferrous iron transport in Streptococcus mutans

    Energy Technology Data Exchange (ETDEWEB)

    Evans, S.L.; Arcenaeux, J.E.L.; Byers, B.R.; Martin, M.E.; Aranha, H.

    1986-12-01

    Radioiron uptake from /sup 59/FeCl/sub 3/ by Streptococcus mutans OMZ176 was increased by anaerobiosis, sodium ascorbate, and phenazine methosulfate (PMS), although there was a 10-min lag before PMS stimulation was evident. The reductant ascorbate may have provided ferrous iron. The PMS was reduced by the cells, and the reduced PMS then may have generated ferrous iron for transport; reduced PMS also may have depleted dissolved oxygen. It was concluded that S. mutans transports only ferrous iron, utilizing reductants furnished by glucose metabolism to reduce iron prior to its uptake.

  6. Role of phosphate in the regulation of the Pasteur effect in Saccharomyces cerevisiae.

    Science.gov (United States)

    Lagunas, R; Gancedo, C

    1983-12-15

    The occurrence of the Pasteur effect in Saccharomyces cerevisiae in several conditions has been examined. In these conditions measurements of a series of metabolites potentially involved in the regulation of the effect were performed. These included, among others, adenine nucleotides, citrate, fructose 2,6-bisphosphate and phosphate. Only phosphate changed in a consistent way, increasing in anaerobiosis when the Pasteur effect occurred. It is concluded that, with the available data, only phosphate may be considered as a regulator of the Pasteur effect in this microorganism.

  7. Alcohol dehydrogenase gene ADH3 activates glucose alcoholic fermentation in genetically engineered Dekkera bruxellensis yeast

    DEFF Research Database (Denmark)

    Schifferdecker, Anna Judith; Siurkus, Juozas; Andersen, Mikael Rørdam;

    2016-01-01

    Dekkera bruxellensis is a non-conventional Crabtree-positive yeast with a good ethanol production capability. Compared to Saccharomyces cerevisiae, its tolerance to acidic pH and its utilization of alternative carbon sources make it a promising organism for producing biofuel. In this study, we de......, respectively. The overexpression of ADH3 in D. bruxellensis also reduced the inhibition of fermentation by anaerobiosis, the "Custer effect". Thus, the fermentative capacity of D. bruxellensis could be further improved by metabolic engineering....

  8. Detection, identification, and typing of Listeria species from baled silages fed to dairy cows.

    Science.gov (United States)

    Nucera, D M; Grassi, M A; Morra, P; Piano, S; Tabacco, E; Borreani, G

    2016-08-01

    Anaerobiosis, critical for successful ensilage, constitutes a challenge in baled silages. The loss of complete anaerobiosis causes aerobic deterioration and silages undergo dry matter and nutrient losses, pathogen growth, and mycotoxin production. Silage may represent an ideal substrate for Listeria monocytogenes, a pathogen of primary concern in several cheeses. The aim of this research was to investigate the occurrence of Listeria in baled silage fed to cows producing milk for a protected designation of origin cheese, and to characterize isolates by repetitive sequence-based PCR. Listeria spp. were detected in 21 silages and L. monocytogenes in 6 out of 80 of the analyzed silages; 67% of positives were found in molded zones. Results of the PCR typing showed genotypic homogeneity: 72.9 and 78.8% similarity between strains of Listeria spp. (n=56) and L. monocytogenes (n=24), respectively. Identical profiles were recovered in molded and nonmolded areas, indicating that contamination may have occurred during production. The application of PCR allowed the unambiguous identification of Listeria isolated from baled silages, and repetitive sequence-based PCR allowed a rapid and effective typing of isolates. Results disclose the potential of the systematic typing of Listeria in primary production, which is needed for the understanding of its transmission pathways. PMID:27209131

  9. Quantitative proteome and transcriptome analysis of the archaeon Thermoplasma acidophilum cultured under aerobic and anaerobic conditions.

    Science.gov (United States)

    Sun, Na; Pan, Cuiping; Nickell, Stephan; Mann, Matthias; Baumeister, Wolfgang; Nagy, István

    2010-09-01

    A comparative proteome and transcriptome analysis of Thermoplasma acidophilum cultured under aerobic and anaerobic conditions has been performed. One-thousand twenty-five proteins were identified covering 88% of the cytosolic proteome. Using a label-free quantitation method, we found that approximately one-quarter of the identified proteome (263 proteins) were significantly induced (>2 fold) under anaerobic conditions. Thirty-nine macromolecular complexes were identified, of which 28 were quantified and 15 were regulated under anaerobiosis. In parallel, a whole genome cDNA microarray analysis was performed showing that the expression levels of 445 genes were influenced by the absence of oxygen. Interestingly, more than 40% of the membrane protein-encoding genes (145 out of 335 ORFs) were up- or down-regulated at the mRNA level. Many of these proteins are functionally associated with extracellular protein or peptide degradation or ion and amino acid transport. Comparison of the transcriptome and proteome showed only a weak positive correlation between mRNA and protein expression changes, which is indicative of extensive post-transcriptional regulatory mechanisms in T. acidophilum. Integration of transcriptomics and proteomics data generated hypotheses for physiological adaptations of the cells to anaerobiosis, and the quantitative proteomics data together with quantitative analysis of protein complexes provide a platform for correlation of MS-based proteomics studies with cryo-electron tomography-based visual proteomics approaches.

  10. Pathway of phloem unloading in tobacco sink leaves. [Nicotiana tabacum

    Energy Technology Data Exchange (ETDEWEB)

    Turgeon, R.

    1987-04-01

    Phloem unloading in transition sink leaves of tobacco (Nicotiana tabacum L.) was analyzed by quantitative autoradiography. Source leaves were labeled with /sup 14/CO/sub 2/ and experimental treatments were begun approximately 1 h later when label had entered the sink leaves. Autoradiographs were prepared from rapidly frozen, lyophilized sink tissue at the beginning and end of the treatments and the amount of label in veins and in surrounding cells was determined by microdensitometry. Photoassimilate unloaded from third order and larger, but not smaller, veins. Long-distance import and unloading did not respond the same way to all experimental treatments. Import was completely inhibited by cold, anaerobiosis or steam girdling the sink leaf petiole. Unloading was inhibited by cold but continued in an anaerobic atmosphere and after steam girdling. Uptake of exogenous (/sup 14/C)sucrose was inhibited by anaerobiosis. Since an apoplastic pathway of phloem unloading would involve solute uptake from the apoplast the results are most consistent with passive symplastic unloading of photoassimilates from phloem to surrounding cells.

  11. The Involvement of hybrid cluster protein 4, HCP4, in Anaerobic Metabolism in Chlamydomonas reinhardtii.

    Directory of Open Access Journals (Sweden)

    Adam C Olson

    Full Text Available The unicellular green algae Chlamydomonas reinhardtii has long been studied for its unique fermentation pathways and has been evaluated as a candidate organism for biofuel production. Fermentation in C. reinhardtii is facilitated by a network of three predominant pathways producing four major byproducts: formate, ethanol, acetate and hydrogen. Previous microarray studies identified many genes as being highly up-regulated during anaerobiosis. For example, hybrid cluster protein 4 (HCP4 was found to be one of the most highly up-regulated genes under anoxic conditions. Hybrid cluster proteins have long been studied for their unique spectroscopic properties, yet their biological functions remain largely unclear. To probe its role during anaerobiosis, HCP4 was silenced using artificial microRNAs (ami-hcp4 followed by extensive phenotypic analyses of cells grown under anoxic conditions. Both the expression of key fermentative enzymes and their respective metabolites were significantly altered in ami-hcp4, with nitrogen uptake from the media also being significantly different than wild-type cells. The results strongly suggest a role for HCP4 in regulating key fermentative and nitrogen utilization pathways.

  12. The Involvement of hybrid cluster protein 4, HCP4, in Anaerobic Metabolism in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Olson, Adam C; Carter, Clay J

    2016-01-01

    The unicellular green algae Chlamydomonas reinhardtii has long been studied for its unique fermentation pathways and has been evaluated as a candidate organism for biofuel production. Fermentation in C. reinhardtii is facilitated by a network of three predominant pathways producing four major byproducts: formate, ethanol, acetate and hydrogen. Previous microarray studies identified many genes as being highly up-regulated during anaerobiosis. For example, hybrid cluster protein 4 (HCP4) was found to be one of the most highly up-regulated genes under anoxic conditions. Hybrid cluster proteins have long been studied for their unique spectroscopic properties, yet their biological functions remain largely unclear. To probe its role during anaerobiosis, HCP4 was silenced using artificial microRNAs (ami-hcp4) followed by extensive phenotypic analyses of cells grown under anoxic conditions. Both the expression of key fermentative enzymes and their respective metabolites were significantly altered in ami-hcp4, with nitrogen uptake from the media also being significantly different than wild-type cells. The results strongly suggest a role for HCP4 in regulating key fermentative and nitrogen utilization pathways. PMID:26930496

  13. Ascorbate accumulation during sulphur deprivation and its effects on photosystem II activity and H2 production of the green alga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Nagy, Valéria; Vidal-Meireles, André; Tengölics, Roland; Rákhely, Gábor; Garab, Győző; Kovács, László; Tóth, Szilvia Z

    2016-07-01

    In nature, H2 production in Chlamydomonas reinhardtii serves as a safety valve during the induction of photosynthesis in anoxia, and it prevents the over-reduction of the photosynthetic electron transport chain. Sulphur deprivation of C. reinhardtii also triggers a complex metabolic response resulting in the induction of various stress-related genes, down-regulation of photosynthesis, the establishment of anaerobiosis and expression of active hydrogenase. Photosystem II (PSII) plays dual role in H2 production because it supplies electrons but the evolved O2 inhibits the hydrogenase. Here, we show that upon sulphur deprivation, the ascorbate content in C. reinhardtii increases about 50-fold, reaching the mM range; at this concentration, ascorbate inactivates the Mn-cluster of PSII, and afterwards, it can donate electrons to tyrozin Z(+) at a slow rate. This stage is followed by donor-side-induced photoinhibition, leading to the loss of charge separation activity in PSII and reaction centre degradation. The time point at which maximum ascorbate concentration is reached in the cell is critical for the establishment of anaerobiosis and initiation of H2 production. We also show that ascorbate influenced H2 evolution via altering the photosynthetic electron transport rather than hydrogenase activity and starch degradation. PMID:26714836

  14. Metabolism of D-lactate and structurally related organic acids in Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    During the initial minutes of anaerobiosis, 14C-labeled D-lactate, derived from the photosynthetic sugar phosphate pool, accumulated in the unicellular green alga, Chlamydomonas reinhardtii. The production of the D-isomer of lactate by algae is in contrast to plant and mammalian cells in which L-lactate is formed. After initial lactate formation, Chlamydomonas exhibits a mixed-acid type fermentation, thereby avoiding lactate accumulation and enabling the cells to tolerate extended periods of anaerobiosis. A pyruvate reductase which catalyzes the formation of D-lactate in Chlamydomonas was partially purified and characterized. Lactate produced anaerobically was metabolized only when Chlamydomonas cells were returned to aerobic conditions, and reoxidation of the D-lactate was apparently catalyzed by a mitochondrial membrane-bound dehydrogenase, rather than by the soluble pyruvate reductase. Mutants of Chlamydomonas, deficient in mitochondrial respiration, were used to demonstrate that lactate metabolism was linked to the mitochondrial electron transport chain. In addition, the oxidation of glycolate, a structural analog of lactate, was also linked to mitochondrial electron transport in vivo

  15. Regulation of Raoultella terrigena comb.nov. phytase expression.

    Science.gov (United States)

    Zamudio, Marcela; González, Aracely; Bastarrachea, Fernando

    2002-01-01

    Phytases catalyze the release of phosphate from phytate (myo-inositol hexakisphosphate) to inositol polyphosphates. Raoultella terrigena comb.nov. phytase activity is known to increase markedly after cells reach the stationary phase. In this study, phytase activity measurements made on single batch cultures indicated that specific enzyme activity was subject to catabolite repression. Cyclic AMP (cAMP) showed a positive effect in expression during exponential growth and a negative effect during stationary phase. RpoS exhibited the opposite effect during both growth phases; the induction to stationary phase decreased twofold in the rpoS::Tn10 mutant, but the effect of RpoS was not clearly determined. Two phy::MudI1734 mutants, MW49 and MW52, were isolated. These formed small colonies in comparison with the MW25 parent strain when plated on Luria-Bertani (LB) or LB supplemented with glucose. They did not grow in minimal media or under anaerobiosis, but did grow aerobically on LB and LB glucose at a lower rate than did MW25. The beta-galactosidase activity level in these mutants increased three to four fold during stationary growth in LB glucose and during anaerobiosis. Addition of cAMP during the exponential growth of MW52 on LB glucose provoked a decrease in beta-galactosidase activity during the stationary phase, confirming its negative effect on phytase expression during stationary growth.

  16. CELLULOSE DECOMPOSTION IN TROPICAL PEAT SWAMPS

    Institute of Scientific and Technical Information of China (English)

    Hjh Dulima Jali

    2003-01-01

    Given that organic soil is a complex substrate and there are many environmental factors which directly or indirectly control its decomposition processes, the use of standard substrate simplify the system in that the effect of substrate quality could be eliminated and influence of certain environmental conditions such as edaphic factors, acidity and moisture could be focused on. In addition to the forest floor, decomposition potential down the peat profile can also be examined. Cotton strip assay was used to estimate decomposition potentials in tropical peat swamp occupied by different Shorea Albida peat swamp forest communities, The' Alan Batu' , the ' Alan Bunga' , the' Alan Padang' and the 'mixed Alan'forest communities. Greatest decay rates on the peat surface took place during the wet period. The moist condition of the wet months appeared to favour the growth and stimulate activities of decomposer population and soil invertebrates.Generally, 50% of cotton tensile loss is achieved after four weeks of exposure. The results suggest that cellulose decomposition is influenced by the environmental variables of hydrological regime, water-table fluctuation, aeration, moisture availability,waterlogging and the resultant anaerobiosis, peat depths, and micro-sites characteristics. Decomposition of cellulose is inhibited by waterlogging and the resultant anaerobiosis in thelower segment of the cotton strip during wet periods and under dry conditions in the surface segment of the cotton strip during periods of less rain.

  17. Effects of forearm bier block with bretylium on the hemodynamic and metabolic responses to handgrip

    Science.gov (United States)

    Lee, F.; Shoemaker, J. K.; McQuillan, P. M.; Kunselman, A. R.; Smith, M. B.; Yang, Q. X.; Smith, H.; Gray, K.; Sinoway, L. I.

    2000-01-01

    We tested the hypothesis that a reduction in sympathetic tone to exercising forearm muscle would increase blood flow, reduce muscle acidosis, and attenuate reflex responses. Subjects performed a progressive, four-stage rhythmic handgrip protocol before and after forearm bier block with bretylium as forearm blood flow (Doppler) and metabolic (venous effluent metabolite concentration and (31)P-NMR indexes) and autonomic reflex responses (heart rate, blood pressure, and sympathetic nerve traffic) were measured. Bretylium inhibits the release of norepinephrine at the neurovascular junction. Bier block increased blood flow as well as oxygen consumption in the exercising forearm (P bier block (6.41 +/- 0.08 vs. 6.20 +/- 0.06; P bier block. The results support the conclusion that sympathetic stimulation to muscle during exercise not only limits muscle blood flow but also appears to limit anaerobiosis and H(+) release, presumably through a preferential recruitment of oxidative fibers.

  18. Geochemical, Genetic, and Community Controls on Mercury

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Judy D.

    2014-11-10

    The sulfate-reducing bacteria (SRB) are soil bacteria that share two common characteristics, strict anaerobiosis and the ability to respire sulfate. The metabolic activities of these bacteria play significant roles in the global sulfur cycle, anaerobic degradation of biomass, biological metal corrosion in the environment and, recently, degradation of toxic compounds. The accumulation of evidence suggests these bacteria are also key to the production of the neurotoxin methylmercury in environmental settings. We propose to use our experience with the development of genetics in sulfate-reducing bacteria of the genus Desulfovibrio to create mutations that will eliminate the methylation of mercury, thereby identifying the genes essential for this process. This information may allow the environmental monitoring of the mercury methylation potential to learn the location and quantity of the production this toxin. From these data, more accurate predictive models of mercury cycling can be generated.

  19. Pyruvate decarboxylases from the petite-negative yeast Saccharomyces kluyveri

    DEFF Research Database (Denmark)

    Møller, Kasper; Langkjær, Rikke Breinhold; Nielsen, Jens;

    2004-01-01

    Saccharomyces kluyveri is a petite-negative yeast, which is less prone to form ethanol under aerobic conditions than is S. cerevisiae. The first reaction on the route from pyruvate to ethanol is catalysed by pyruvate decarboxylase, and the differences observed between S. kluyveri and S. cerevisiae...... was controlled by variations in the amount of mRNA. The mRNA level and the pyruvate decarboxylase activity responded to anaerobiosis and growth on different carbon sources in essentially the same fashion as in S. cerevisiae. This indicates that the difference in ethanol formation between these two yeasts...... is not due to differences in the regulation of pyruvate decarboxylase(s), but rather to differences in the regulation of the TCA cycle and the respiratory machinery. However, the PDC genes of Saccharomyces/Kluyveromyces yeasts differ in their genetic organization and phylogenetic origin. While S. cerevisiae...

  20. Soil 13C-CO2 profiles under a corn cultivated site: Impact of a rainfall event

    International Nuclear Information System (INIS)

    A seven months experiment (from October 2001 to May 2002) was undertaken in a bare field after corn harvesting, situated at Velleron, in the south of France (43 deg. 91' N, 5 deg. 06' E). Velleron is located in an area labelled 'zone vulnerable' with regard to major groundwater NO3- pollution due to agriculture practices (EEC 91-676 directive). The soil studied is a fluvic hypercalcaric cambisol (FAO classification) and was cultivated with corn during two years. Water table fluctuations allowed the existence of temporary anaerobiosis (reduction-oxidation stains). The objective of this experiment was to follow C and N elements behaviour in the unsaturated soil zone (2.5 m thick), thanks to corn residue decomposition and leaching in the soil profile

  1. Horizontal gene transfer promoted evolution of the ability to propagate under anaerobic conditions in yeasts

    DEFF Research Database (Denmark)

    Gojkovic, Zoran; Knecht, Wolfgang; Warneboldt, J.;

    2004-01-01

    The ability to propagate under anaerobic conditions is an essential and unique trait of brewer's or baker's yeast (Saccharomyces cervisiae). To understand the evolution of facultative anaerobiosis we studied the dependence of de novo pyrimidine biosynthesis, more precisely the fourth enzymic...... activity catalysed by dihydroorotate dehydrogenase (DHODase), on the enzymes of the respiratory chain in several yeast species. While the majority of yeasts possess a mitochondrial DHODase, Saccharomyces cerevisiae has a cytoplasmatic enzyme, whose activity is independent of the presence of oxygen. From....... We show that these two S. kluyveri enzymes, and their coding genes, differ in their dependence on the presence of oxygen. Only the cytoplasmic DHODase promotes growth in the absence of oxygen. Apparently a Saccharomyces yeast progenitor which had a eukaryotic-like mitochondrial DHODase acquired...

  2. Doxycycline induced photodamage to human neutrophils and tryptophan

    International Nuclear Information System (INIS)

    Neutrophil function were studied following irradiation (340-380 nm) of the cells in the presence of 22 μM doxycycline. At increasing light fluence the locomotion, chemiluminescence and glucose oxidation (by the hexose monophosphate shunt) of the neutrophils steadily decreased. The photodamage increased with increasing preincubation temperature and time and was enhanced in D2O, reduced in azide and abolished in anaerobiosis. Superoxide dismutase, catalase or mannitol did not influence the photodamage. Photooxidation of tryptophan in the presence of doxycycline was increased 9-10-fold in D2O and nearly abolished in the presence of 0.25 mM NaN3, indicating that singlet oxygen is the most important reactive oxygen species in the doxycycline-induced photodamage. The results may explain some of the features of tetracycline-induced photosensitivity and why other authors have obtained diverging results when studying the influence of tetracyclines on neutrophil functions. (author)

  3. Biodegradation of 14C-dicofol in wastewater aerobic treatment and sludge anaerobic biodigestion.

    Science.gov (United States)

    Oliveira, Jaime L da M; Silva, Denise P; Martins, Edir M; Langenbach, Tomaz; Dezotti, Marcia

    2012-01-01

    Organic micropollutants are often found in domestic and industrial effluents. Thus, it is important to learn their fate, the metabolites generated and their sorption during biological treatment processes. This work investigated the biodegradation of 14C-dicofol organochloride during wastewater aerobic treatment and sludge anaerobic biodigestion. The performance of these processes was evaluated by physical-chemical parameters. Radioactivity levels were monitored in both treatments, and residues of dicofol (DCF) and dichlorobenzophenone (DBP) were quantified by HPLC/UV. The efficiency of the aerobic and anaerobic processes was slightly reduced in the presence of DCF and DBP. After aerobic treatment, only 0.1% of DCF was mineralized, and 57% of radioactivity remained sorbed on biological sludge as DBP. After 18 days of anaerobiosis, only 3% of DCF and 5% of DBP were detected in the sludge. However, 70% of radioactivity remained in the sludge, probably as other metabolites. Dicofol was biodegraded in the investigated process, but not mineralized. PMID:22629645

  4. Doxycycline induced photodamage to human neutrophils and tryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Sandberg, S.; Glette, J.; Hopen, G.; Solberg, C.O. (Haukeland Sykehus, Bergen (Norway))

    1984-01-01

    Neutrophil function were studied following irradiation (340-380 nm) of the cells in the presence of 22 ..mu..M doxycycline. At increasing light fluence the locomotion, chemiluminescence and glucose oxidation (by the hexose monophosphate shunt) of the neutrophils steadily decreased. The photodamage increased with increasing preincubation temperature and time and was enhanced in D/sub 2/O, reduced in azide and abolished in anaerobiosis. Superoxide dismutase, catalase or mannitol did not influence the photodamage. Photooxidation of tryptophan in the presence of doxycycline was increased 9-10-fold in D/sub 2/O and nearly abolished in the presence of 0.25 mM NaN/sub 3/, indicating that singlet oxygen is the most important reactive oxygen species in the doxycycline-induced photodamage. The results may explain some of the features of tetracycline-induced photosensitivity and why other authors have obtained diverging results when studying the influence of tetracyclines on neutrophil functions.

  5. First data on the distribution and ecology of Vibrio spp. of the Straits of Magellan (South America).

    Science.gov (United States)

    Monticelli, L S; Crisafi, E

    1995-07-01

    During the austral summer of 1991 a study was carried out on the presence and distribution of the genus Vibrio in the Straits of Magellan. Vibrios strains were isolated using membrane filters and Marine Agar 2216 in anaerobiosis. Variations of the populations of total heterotrophic bacteria and vibrios were observed both on the surface and along the column of water. All vibrios are psychrotrophic and were grouped in 4 cluster among which cluster 1, identified as presumed V. anguillarum, seems the most important including 73% of strains. A certain habitat segregation of clusters was noted. Cluster 4 was found only in a deep and permanently colder water mass. The relations between 20 environmental parameters and the bacterial population were also studied. Significant positive correlations were observed between the vibrios population and various fractions of suspended particulate matter.

  6. Opening of the mitochondrial permeability transition pore by uncoupling or inorganic phosphate in the presence of Ca2+ is dependent on mitochondrial-generated reactive oxygen species.

    Science.gov (United States)

    Kowaltowski, A J; Castilho, R F; Vercesi, A E

    1996-01-01

    In this study, we show that mitochondrial membrane permeability transition in Ca(2+)-loaded mitochondria treated with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) or inorganic phosphate (P(i)) is preceded by enhanced production of H2O2. This production is inhibited either by ethylene glycobis(b-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA) or Mg2+, but not by cyclosporin A. Permeability transition is prevented either by EGTA, catalase or dithiothreitol, suggesting the involvement of Ca2+, H2O2 and oxidation of membrane protein thiols in this mechanism. When mitochondria are incubated under anaerobiosis, no permeabilization or H2O2 production occurs. Based on these results we conclude that mitochondrial permeability transition induced by P(i) or FCCP-uncoupling is dependent on mitochondrial-generated reactive oxygen species. PMID:8549822

  7. Study on biological phosphorus removal process by Acinetobacter lwoffi: possibility to by-pass the anaerobic phase

    Energy Technology Data Exchange (ETDEWEB)

    Ghigliazza, R.; Lodi, A.; Rovatti, M. [Institute of Chemical and Process Engineering ``G.B. Bonino``, University of Genoa (Italy)

    1998-03-01

    An Acinetobacter lwoffi culture has been submitted to anaerobic/aerobic conditions in a Sequencing Batch Reactor (SBR) in order to study the ability of this strain in biological phosphorus removal process. Even by feeding a pure sodium acetate substrate, no phosphorus release has been detected during anaerobiosis, while phosphorus uptake beyond metabolic needs has been recorded during the aerobic phase; the anaerobic phase seems to have no influence on the enhanced biological phosphorus removal mechanisms. Hence aerobic batch tests have been carried out in order to verify the ability of Acinetobacter lwoffi to remove phosphorus by ``luxury uptake`` and ``overplus accumulation`` without anaerobic stress. Obtained results revealed a phosphorus removal efficiency of 75-80%. (orig.) With 5 figs., 3 tabs., 18 refs.

  8. Process and genes for expression and overexpression of active [FeFe] hydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, Michael; King, Paul W; Ghirardi, Maria Lucia; Posewitz, Matthew C; Smolinski, Sharon L

    2014-09-16

    A process for expression of active [FeFe]-hydrogenase in a host organism that does not contain either the structural gene(s) for [FeFe]-hydrogenases and/or homologues for the maturation genes HydE, HydF and HyG, comprising: cloning the structural hydrogenase gene(s) and/or the maturation genes HydE, HydF and HydG from an organisms that contains these genes into expression plasmids; transferring the plasmids into an organism that lacks a native [FeFe]-hydrogenase or that has a disrupted [FeFe]-hydrogenase and culturing it aerobically; and inducing anaerobiosis to provide [FeFe] hydrogenase biosynthesis and H?2#191 production.

  9. Fermentation assisted byproduct recovery in the palm oil industry

    Energy Technology Data Exchange (ETDEWEB)

    Stanton, W.R.

    1983-05-01

    The production of palm oil from Elaeis guineensis is a leading natural product industry in Malaysia, giving rise to a number of residues, including a rich, fruity liquor from the pulp. The liquor, of which 7-10 million tonnes a year are currently produced, has some 6% organic solids, including 0.7-1.0% or more of oil which physical processing has failed to extract. Present anaerobic digestion processes exploit only the energy and fertiliser value. Methods are described in this paper for thermophilic, microbially assisted digestion for component separation and recovery, exploiting the widely used techniques for fruit juice extraction involving enzymic breakdown of starch, pectin and other cell components. Anaerobiosis and acidogenesis help protect and release residual oil, concomitantly preserving the solids against rancidity and spoilage by ensilage. The separated wet solids are nutritive (17% protein on dry matter), biologically safe and attractive to livestock. Downstream use of the liquor is aided by the thermophilic digestion. (Refs. 33).

  10. The role of ABC proteins Aus1p and Pdr11p in the uptake of external sterols in yeast: dehydroergosterol fluorescence study

    DEFF Research Database (Denmark)

    Kohut, Peter; Wüstner, Daniel; Hronska, L;

    2011-01-01

    Uptake of external sterols in the yeast Saccharomyces cerevisiae is a multistep process limited to anaerobiosis or heme deficiency. It includes crossing the cell wall, insertion of sterol molecules into plasma membrane and their internalization and integration into intracellular membranes. We...... applied the fluorescent ergosterol analog dehydroergosterol (DHE) to monitor the initial steps of sterol uptake by three independent approaches: fluorescence spectroscopy, fluorescence microscopy and sterol quantification by HPLC. Using specific fluorescence characteristics of DHE we showed that the entry...... of sterol molecules into plasma membrane is not spontaneous but requires assistance of two ABC (ATP-binding cassette) pumps--Aus1p or Pdr11p. DHE taken up by uptake-competent hem1ΔAUS1PDR11 cells could be directly visualized by UV-sensitive wide field fluorescence microscopy. HPLC analysis of sterols...

  11. Aerenchyma formation and methane and oxygen exchange in rice

    Energy Technology Data Exchange (ETDEWEB)

    Kludze, H.K.; DeLaune, R.D.; Patrick, W.H. Jr. (Louisiana State Univ., Baton Rouge (United States))

    Limited information exists on the direct link between the intensity of soil reduction or anaerobiosis and gas exchange in rice (Oryza sativa L.). A laboratory experiment was conducted to determine the extent to which specific levels of soil redox potential (Eh) could influence aerenchyma formation. O[sub 2] transport, and CH[sub 4] production and emission. Plants were grown in a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) under controlled Eh values of 200, -200, and [minus]300 mV. Radial O[sub 2] loss (ROL) from plant roots was estimated colorimetrically by using Ti[sup 3+]-citrate solution, a reduced compound. Methane production and its emission increased with decrease in soil Eh; CH[sub 4] production increased 10-fold while its emission was enhanced 17-fold when soil Eh dropped from [minus]200 to [minus]300 mV. A positive relationship was established between the intensity of soil anaerobiosis and both aerenchyma formation and ROL. Root and shoot dry weights and root length decreased with decrease in soil Eh. Results of this study demonstrate that soil Eh influences net CH[sub 4] flux from rice in two ways: (i) it directly determines the amount and rate of CH[sub 4] production in the soil, and (ii) it initiates morphological and physiological changes in the rice plant that affect gas exchange between the soil and the atmosphere. Although the results may not necessarily reflect actual conditions in the field, they provide a theoretical basis for understanding the influence of soil Eh on rice growth, CH[sub 4] production, and gas exchange. 36 refs., 6 figs., 2 tabs.

  12. Heat shock proteins and hypometabolism: adaptive strategy for proteome preservation

    Directory of Open Access Journals (Sweden)

    Storey KB

    2011-03-01

    Full Text Available Kenneth B Storey, Janet M StoreyDepartments of Biology and Chemistry, Carleton University, Ottawa, ON, CanadaAbstract: To survive under harsh environmental conditions many organisms retreat into hypometabolic states where metabolic rate may be reduced by 80% or more and energy use is reprioritized to emphasize key functions that sustain viability and provide cytoprotection. ATP-expensive activities, such as gene expression, protein turnover (synthesis and degradation, and the cell cycle, are largely shut down. As a consequence, mechanisms that stabilize the existing cellular proteome can become critical for long-term survival. Heat shock proteins (HSPs are well-known for their actions as chaperones that act to fold new proteins or refold proteins that are damaged. Indeed, they are part of the “minimal stress proteome” that appears to be a ubiquitous response by all cells as they attempt, successfully or unsuccessfully, to deal with stress. The present review summarizes evidence that HSPs are also a conserved feature of natural animal hypometabolism including the phenomena of estivation, hibernation, diapause, cold-hardiness, anaerobiosis, and anhydrobiosis. That is, organisms that retreat into dormant or torpid states in anticipation that environmental conditions may become too difficult for normal life also integrate the use of HSPs to protect their proteome while hypometabolic. Multiple studies show a common upregulation of expression of hsp genes and/or HSP proteins prior to or during hypometabolism in organisms as diverse as ground squirrels, turtles, land snails, insects, and brine shrimp and in situations of both preprogrammed dormancies (eg, seasonal or life stage specific and opportunistic hypometabolism (eg, triggered by desiccation or lack of oxygen. Hence, HSPs are not just a “shock” response that attempts to rescue cells from damaging stress but are a key protective strategy that is an integral component of natural states of

  13. The role of acidification in the inhibition of Neisseria gonorrhoeae by vaginal lactobacilli during anaerobic growth

    Directory of Open Access Journals (Sweden)

    Wade Jeremy J

    2011-02-01

    Full Text Available Abstract Background Vaginal lactobacilli protect the female genital tract by producing lactic acid, bacteriocins, hydrogen peroxide or a local immune response. In bacterial vaginosis, normal lactobacilli are replaced by an anaerobic flora and this may increase susceptibility to Neisseria gonorrhoeae, a facultative anaerobe. Bacterial interference between vaginal lactobacilli and N. gonorrhoeae has not been studied in liquid medium under anaerobic conditions. By co-cultivating N. gonorrhoeae in the presence of lactobacilli we sought to identify the relative contributions of acidification and hydrogen peroxide production to any growth inhibition of N. gonorrhoeae. Methods Three strains of N. gonorrhoeae distinguishable by auxotyping were grown in the presence of high concentrations (107-108 cfu/mL of three vaginal lactobacilli (L. crispatus, L. gasseri and L. jensenii in an anerobic liquid medium with and without 2-(N-morpholino-ethanesulfonic (MES buffer. Fusobacterium nucleatum was used as an indicator of anaerobiosis. Bacterial counts were performed at 15, 20 and 25 h; at 25 h pH and hydrogen peroxide concentrations were measured. Results Growth of F. nucleatum to >108 cfu/mL at 25 h confirmed anaerobiosis. All bacteria grew in the anaerobic liquid medium and the addition of MES buffer had negligible effect on growth. L. crispatus and L. gasseri produced significant acidification and a corresponding reduction in growth of N. gonorrhoeae. This inhibition was abrogated by the addition of MES. L. jensenii produced less acidification and did not inhibit N. gonorrhoeae. Hydrogen peroxide was not detected in any experiment. Conclusions During anaerobic growth, inhibition of N. gonorrhoeae by the vaginal lactobacilli tested was primarily due to acidification and abrogated by the presence of a buffer. There was no evidence of a specific mechanism of inhibition other than acid production under these conditions and, in particular, hydrogen peroxide was

  14. Rhamnolipid-dependent spreading growth of Pseudomonas aeruginosa on a high-agar medium: marked enhancement under CO2-rich anaerobic conditions.

    Science.gov (United States)

    Nozawa, Takashi; Tanikawa, Taichiro; Hasegawa, Hiroyuki; Takahashi, Chihiro; Ando, Yumi; Matsushita, Mitsugu; Nakagawa, Yoji; Matsuyama, Tohey

    2007-01-01

    Anaerobiosis of Pseudomonas aeruginosa in infected organs is now gaining attention as a unique physiological feature. After anaerobic cultivation of P. aeruginosa wild type strain PAO1 T, we noticed an unexpectedly expanding colony on a 1.5% agar medium. The basic factors involved in this spreading growth were investigated by growing the PAO1 T strain and its isogenic mutants on a Davis high-agar minimal synthetic medium under various experimental conditions. The most promotive environment for this spreading growth was an O(2)-depleted 8% CO(2) condition. From mutational analysis of this spreading growth, flagella and type IV pili were shown to be ancillary factors for this bacterial activity. On the other hand, a rhamnolipid-deficient rhlA mutant TR failed to exhibit spreading growth on a high-agar medium. Complementation of the gene defect of the mutant TR with a plasmid carrying the rhlAB operon resulted in the restoration of the spreading growth. In addition, an external supply of rhamnolipid or other surfactants (surfactin from Bacillus subtilis or artificial product Tween 80) also restored the spreading growth of the mutant TR. Such activity of surfactants on bacterial spreading on a hard-agar medium was unique to P. aeruginosa under CO(2)-rich anaerobic conditions.

  15. Metabolic characteristics of muscles in the spiny lobster, Jasus edwardsii, and responses to emersion during simulated live transport.

    Science.gov (United States)

    Speed, S R; Baldwin, J; Wong, R J; Wells, R M

    2001-03-01

    The metabolic characteristics of five muscle groups in the spiny lobster Jasus edwardsii were examined in order to compare their anaerobic and oxidative capacities. Enzyme activities of phosphorylase, phosphofructokinase, pyruvate kinase, and lactate dehydrogenase were highest in abdominal muscles supporting anaerobic burst activity. Hexokinase, citrate synthase, and HOAD activities in the leg and antennal muscles indicated higher aerobic potential. Arginine kinase activities were high in all muscle groups indicating that muscle phosphagens are an important energy reserve. Arginine phosphate concentrations in 4th periopod and abdominal flexor muscle from lobsters sampled in the field were higher than any values from captive animals, and approximately five times those for ATP. Muscle lactates were high in captive animals. Responses to emersion during simulated live transport appear to exploit the capacity for functional anaerobiosis and further differentiated the muscle groups. Abdominal muscles were especially sensitive and after 24 h showed significant increases in lactate, glucose, ADP, and AMP. ATP levels appeared to be maintained by muscle phosphagens and raised doubts about the efficacy of the adenylate energy charge in evaluating the emersion response. Haemolymph glucose, lactic acid, and ammonia peaked after 24 h emersion and were largely restored following re-immersion. We propose that arginine phosphate concentrations in the 4th periopod are an appropriate index of metabolic stress, and could lead to improved commercial handling protocols.

  16. In silico discovery of the dormancy regulons in a number of Actinobacteria genomes

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimova, Anna; Dubchak, Inna; Arkin, Adam; Gelfand, Mikhail

    2010-11-16

    Mycobacterium tuberculosis is a dangerous Actinobacteria infecting nearly one third of the human population. It becomes dormant and phenotypically drug resistant in response to stresses. An important feature of the M. tuberculosis pathogenesis is the prevalence of latent infection without disease, making understanding of the mechanisms used by the bacteria to exist in this state and to switch to metabolically active infectious form a vital problem to consider. M. tuberculosis dormancy is regulated by the three-component regulatory system of two kinases (DosT and DevS) and transcriprional regulator (DevR). DevR activates transcription of a set of genes, which allow the bacteria to survive long periods of anaerobiosis, and may be important for long-term survival within the host during latent infection. The DevR-regulon is studied experimentally in M. tuberculosis and few other phylogenetically close Mycobacteria spp. As many other two-component systems, the devRS operon is autoregulated. However, the mechanism of the dormancy is not completely clear even for these bacteria and there is no data describing the dormancy regulons in other species.

  17. Differential Susceptibility of Bacteria to Mouse Paneth Cell a-Defensins under Anaerobic Conditions

    Directory of Open Access Journals (Sweden)

    Jennifer R. Mastroianni

    2014-10-01

    Full Text Available Small intestinal Paneth cells secrete a-defensin peptides, termed cryptdins (Crps in mice, into the intestinal lumen, where they confer immunity to oral infections and define the composition of the ileal microbiota. In these studies, facultative bacteria maintained under aerobic or anaerobic conditions displayed differential sensitivities to mouse a-defensins under in vitro assay conditions. Regardless of oxygenation, Crps 2 and 3 had robust and similar bactericidal activities against S. typhimurium and S. flexneri, but Crp4 activity against S. flexneri was attenuated in the absence of oxygen. Anaerobic bacteria varied in their susceptibility to Crps 2-4, with Crp4 showing less activity than Crps 2 and 3 against Enterococcus faecalis, and Bacteroides fragilis in anaerobic assays, but Fusobacterium necrophorum was killed only by Crp4 and not by Crps 2 and 3. The influence of anaerobiosis in modulating Crp bactericidal activities in vitro suggests that a-defensin effects on the enteric microbiota may be subject to regulation by local oxygen tension.

  18. Anaerobic infections in the head and neck region.

    Science.gov (United States)

    Tabaqchali, S

    1988-01-01

    Anaerobic bacteria form the predominant flora of the oral cavity, outnumbering facultative organisms by 10-1,000: 1. The type of anaerobic bacteria and their concentration depend on the anatomical site and the degree of anaerobiosis in the different sites in the mouth. Three groups of anaerobic bacteria inhabit the oral cavity; the strict anaerobes, the moderate anaerobes, and the microaerophilic group of organisms. The majority of anaerobic bacterial infections occurring in the region of the mouth, head and neck are caused by the commensal flora. These infections include dental and periodontal disease where the predominant organisms are Bacteroides species, Veillonella, Bifidobacteria, Peptococcus, Peptostreptococcus and Propionibacterium species. More recently, Bacteroides endontalis has been isolated from a periapical abscess of endodontal origin and B. gingivalis, B. intermedius, Haemophilus actinomycetemcomitans and Wollinella species in chronic periodontal disease. Treponema species and other strict anaerobes are seen in smears of severe periodontal disease and acute necrotising gingivitis, but have not yet been isolated in pure culture. Until such time, their role in disease remains uncertain. Fusobacterium nucleatum is specially associated with severe orofacial infections which may extend into the mediastinum. Other anaerobic infections include chronic otitis media, chronic sinusitis and mastoiditis, and brain abscess. Treatment of these conditions should include the use of beta-lactamase resistant antimicrobials, such as clindamycin or one of the nitroimidazoles with penicillin.

  19. Novel Hydrogenosomes in the Microaerophilic Jakobid Stygiella incarcerata

    Science.gov (United States)

    Leger, Michelle M.; Eme, Laura; Hug, Laura A.; Roger, Andrew J.

    2016-01-01

    Mitochondrion-related organelles (MROs) have arisen independently in a wide range of anaerobic protist lineages. Only a few of these organelles and their functions have been investigated in detail, and most of what is known about MROs comes from studies of parasitic organisms such as the parabasalid Trichomonas vaginalis. Here, we describe the MRO of a free-living anaerobic jakobid excavate, Stygiella incarcerata. We report an RNAseq-based reconstruction of S. incarcerata’s MRO proteome, with an associated biochemical map of the pathways predicted to be present in this organelle. The pyruvate metabolism and oxidative stress response pathways are strikingly similar to those found in the MROs of other anaerobic protists, such as Pygsuia and Trichomonas. This elegant example of convergent evolution is suggestive of an anaerobic biochemical ‘module’ of prokaryotic origins that has been laterally transferred among eukaryotes, enabling them to adapt rapidly to anaerobiosis. We also identified genes corresponding to a variety of mitochondrial processes not found in Trichomonas, including intermembrane space components of the mitochondrial protein import apparatus, and enzymes involved in amino acid metabolism and cardiolipin biosynthesis. In this respect, the MROs of S. incarcerata more closely resemble those of the much more distantly related free-living organisms Pygsuia biforma and Cantina marsupialis, likely reflecting these organisms’ shared lifestyle as free-living anaerobes. PMID:27280585

  20. Regulation of oxidative phosphorylation: the flexible respiratory network of Paracoccus denitrificans.

    Science.gov (United States)

    Van Spanning, R J; de Boer, A P; Reijnders, W N; De Gier, J W; Delorme, C O; Stouthamer, A H; Westerhoff, H V; Harms, N; van der Oost, J

    1995-10-01

    Paracoccus denitrificans is a facultative anaerobic bacterium that has the capacity to adjust its metabolic infrastructure, quantitatively and/or qualitatively, to the prevailing growth condition. In this bacterium the relative activity of distinct catabolic pathways is subject to a hierarchical control. In the presence of oxygen the aerobic respiration, the most efficient way of electron transfer-linked phosphorylation, has priority. At high oxygen tensions P. denitrificans synthesizes an oxidase with a relatively low affinity for oxygen, whereas under oxygen limitation a high-affinity oxidase appears specifically induced. During anaerobiosis, the pathways with lower free energy-transducing efficiency are induced. In the presence of nitrate, the expression of a number of dehydrogenases ensures the continuation of oxidative phosphorylation via denitrification. After identification of the structural components that are involved in both the aerobic and the anaerobic respiratory networks of P. denitrificans, the intriguing next challenge is to get insight in its regulation. Two transcription regulators have recently been demonstrated to be involved in the expression of a number of aerobic and/or anaerobic respiratory complexes in P. denitrificans. Understanding of the regulation machinery is beginning to emerge and promises much excitement in discovery. PMID:8718455

  1. Control of periplasmic nitrate reductase gene expression (napEDABC) from Paracoccus pantotrophus in response to oxygen and carbon substrates.

    Science.gov (United States)

    Sears, H J; Sawers, G; Berks, B C; Ferguson, S J; Richardson, D J

    2000-11-01

    The napEDABC operon of Paracoccus pantotrophus encodes a periplasmic nitrate reductase (NAP), together with electron-transfer components and proteins required for the synthesis of a fully functional enzyme. Previously, it had been shown that high NAP activity was observed when P. pantotrophus was grown aerobically on highly reduced carbon sources such as butyrate or caproate, but not when cultured on more oxidized substrates such as succinate or malate. The enzyme is not present to any extent when the organism is grown anaerobically under denitrifying conditions, regardless of the carbon source. Transcriptional analyses of the nap operon have now identified two initiation sites which were differentially regulated in response to the carbon source, with expression being maximal when cells were grown aerobically with butyrate. Analysis of a P. pantotrophus mutant (M6) deregulated for NAP activity identified a single C-->A transversion in a heptameric inverted-repeat sequence that partially overlapped the proximal promoter. Transcription analysis of this mutant revealed that expression of nap was completely derepressed under all growth conditions examined. Taken together, these findings indicate that nap transcription is negatively regulated during anaerobiosis, such that expression is restricted to aerobic growth, but only when the carbon source is highly reduced. PMID:11065376

  2. [Fe]-hydrogenases in green algae: photo-fermentation and hydrogen evolution under sulfur deprivation

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, M.; Hemschemeier, A.; Happe, T. [Botanisches Institut der Universitat Bonn (Germany); Gotor, C. [CSIC y Universidad de Sevilla (Spain). Instituto de Bioquimica Vegetal y Fotosintesis; Melis, A. [University of California, Berkeley, CA (United States). Department of Plant and Microbial Biology

    2002-12-01

    Recent studies indicate that [Fe]-hydrogenases and H{sub 2} metabolism are widely distributed among green algae. The enzymes are simple structured and catalyze H{sub 2} evolution with similar rates than the more complex [Fe]-hydrogenases from bacteria. Different green algal species developed diverse strategies to survive under sulfur deprivation. Chlamydomonas reinhardtii evolves large quantities of hydrogen gas in the absence of sulfur. In a sealed culture of C. reinhardtii, the photosynthetic O{sub 2} evolution rate drops below the rate of respiratory O{sub 2} consumption due to a reversible inhibition of photosystem II, thus leading to an intracellular anaerobiosis. The algal cells survive under these anaerobic conditions by switching their metabolism to a kind of photo-fermentation. Although possessing a functional [Fe]-hydrogenase gene, the cells of Scenedesmus obliquus produce no significant amounts of H{sub 2} under S-depleted conditions. Biochemical analyses indicate that S. obliquus decreases almost the complete metabolic activities while maintaining a low level of respiratory activity. (author)

  3. Reprogramming of Yersinia from virulent to persistent mode revealed by complex in vivo RNA-seq analysis.

    Directory of Open Access Journals (Sweden)

    Kemal Avican

    2015-01-01

    Full Text Available We recently found that Yersinia pseudotuberculosis can be used as a model of persistent bacterial infections. We performed in vivo RNA-seq of bacteria in small cecal tissue biopsies at early and persistent stages of infection to determine strategies associated with persistence. Comprehensive analysis of mixed RNA populations from infected tissues revealed that Y. pseudotuberculosis undergoes transcriptional reprogramming with drastic down-regulation of T3SS virulence genes during persistence when the pathogen resides within the cecum. At the persistent stage, the expression pattern in many respects resembles the pattern seen in vitro at 26oC, with for example, up-regulation of flagellar genes and invA. These findings are expected to have impact on future rationales to identify suitable bacterial targets for new antibiotics. Other genes that are up-regulated during persistence are genes involved in anaerobiosis, chemotaxis, and protection against oxidative and acidic stress, which indicates the influence of different environmental cues. We found that the Crp/CsrA/RovA regulatory cascades influence the pattern of bacterial gene expression during persistence. Furthermore, arcA, fnr, frdA, and wrbA play critical roles in persistence. Our findings suggest a model for the life cycle of this enteropathogen with reprogramming from a virulent to an adapted phenotype capable of persisting and spreading by fecal shedding.

  4. An ATP and oxalate generating variant tricarboxylic acid cycle counters aluminum toxicity in Pseudomonas fluorescens.

    Directory of Open Access Journals (Sweden)

    Ranji Singh

    Full Text Available Although the tricarboxylic acid (TCA cycle is essential in almost all aerobic organisms, its precise modulation and integration in global cellular metabolism is not fully understood. Here, we report on an alternative TCA cycle uniquely aimed at generating ATP and oxalate, two metabolites critical for the survival of Pseudomonas fluorescens. The upregulation of isocitrate lyase (ICL and acylating glyoxylate dehydrogenase (AGODH led to the enhanced synthesis of oxalate, a dicarboxylic acid involved in the immobilization of aluminum (Al. The increased activity of succinyl-CoA synthetase (SCS and oxalate CoA-transferase (OCT in the Al-stressed cells afforded an effective route to ATP synthesis from oxalyl-CoA via substrate level phosphorylation. This modified TCA cycle with diminished efficacy in NADH production and decreased CO(2-evolving capacity, orchestrates the synthesis of oxalate, NADPH, and ATP, ingredients pivotal to the survival of P. fluorescens in an Al environment. The channeling of succinyl-CoA towards ATP formation may be an important function of the TCA cycle during anaerobiosis, Fe starvation and O(2-limited conditions.

  5. Staphylococcus epidermidis: metabolic adaptation and biofilm formation in response to different oxygen concentrations.

    Science.gov (United States)

    Uribe-Alvarez, Cristina; Chiquete-Félix, Natalia; Contreras-Zentella, Martha; Guerrero-Castillo, Sergio; Peña, Antonio; Uribe-Carvajal, Salvador

    2016-02-01

    Staphylococcus epidermidis has become a major health hazard. It is necessary to study its metabolism and hopefully uncover therapeutic targets. Cultivating S. epidermidis at increasing oxygen concentration [O2] enhanced growth, while inhibiting biofilm formation. Respiratory oxidoreductases were differentially expressed, probably to prevent reactive oxygen species formation. Under aerobiosis, S. epidermidis expressed high oxidoreductase activities, including glycerol-3-phosphate dehydrogenase, pyruvate dehydrogenase, ethanol dehydrogenase and succinate dehydrogenase, as well as cytochromes bo and aa3; while little tendency to form biofilms was observed. Under microaerobiosis, pyruvate dehydrogenase and ethanol dehydrogenase decreased while glycerol-3-phosphate dehydrogenase and succinate dehydrogenase nearly disappeared; cytochrome bo was present; anaerobic nitrate reductase activity was observed; biofilm formation increased slightly. Under anaerobiosis, biofilms grew; low ethanol dehydrogenase, pyruvate dehydrogenase and cytochrome bo were still present; nitrate dehydrogenase was the main terminal electron acceptor. KCN inhibited the aerobic respiratory chain and increased biofilm formation. In contrast, methylamine inhibited both nitrate reductase and biofilm formation. The correlation between the expression and/or activity or redox enzymes and biofilm-formation activities suggests that these are possible therapeutic targets to erradicate S. epidermidis.

  6. Salar de Surire un ecosistema altoandino en peligro, frente a escenario del cambio climático

    Directory of Open Access Journals (Sweden)

    Ingrid Garcés

    2011-12-01

    Full Text Available Este trabajo realiza un análisis al salar de Surire desde el punto de vista de la biodiversidad y sus implicancias producto del cambio climático. Como resultado se predice que los próximos años serán secos y la temperatura podría ir en aumento, lo cual afectará notablemente a la flora y fauna del altiplano. El salar de Surire es un cuerpo salino ubicado en el altiplano andino chileno, en un entorno geológico de características volcánicas. La climatología actual de aridez no permite una acumulación de agua superficial de gran extensión, y por lo tanto es posible diferenciar tres tipos principales de aguas: los aportes de drenaje, las acumulaciones de agua en la aureola pantanosa externa o “bofedales”, y las aguas del interior del cuerpo salino (surgencias termales y salmueras. Estas condiciones hidrológicas afectan factores abióticos, como anaerobiosis de suelos, disposición de nutrientes y salinidad, factores determinantes del desarrollo de la flora y fauna. Palabras claves: Salar de Surire; Biodiversidad andina; Cambio climático; Ecosistema andino

  7. Proteomic evidences for rex regulation of metabolism in toxin-producing Bacillus cereus ATCC 14579.

    Science.gov (United States)

    Laouami, Sabrina; Clair, Géremy; Armengaud, Jean; Duport, Catherine

    2014-01-01

    The facultative anaerobe, Bacillus cereus, causes diarrheal diseases in humans. Its ability to deal with oxygen availability is recognized to be critical for pathogenesis. The B. cereus genome comprises a gene encoding a protein with high similarities to the redox regulator, Rex, which is a central regulator of anaerobic metabolism in Bacillus subtilis and other Gram-positive bacteria. Here, we showed that B. cereus rex is monocistronic and down-regulated in the absence of oxygen. The protein encoded by rex is an authentic Rex transcriptional factor since its DNA binding activity depends on the NADH/NAD+ ratio. Rex deletion compromised the ability of B. cereus to cope with external oxidative stress under anaerobiosis while increasing B. cereus resistance against such stress under aerobiosis. The deletion of rex affects anaerobic fermentative and aerobic respiratory metabolism of B. cereus by decreasing and increasing, respectively, the carbon flux through the NADH-recycling lactate pathway. We compared both the cellular proteome and exoproteome of the wild-type and Δrex cells using a high throughput shotgun label-free quantitation approach and identified proteins that are under control of Rex-mediated regulation. Proteomics data have been deposited to the ProteomeXchange with identifier PXD000886. The data suggest that Rex regulates both the cross-talk between metabolic pathways that produce NADH and NADPH and toxinogenesis, especially in oxic conditions.

  8. Proteomic evidences for rex regulation of metabolism in toxin-producing Bacillus cereus ATCC 14579.

    Directory of Open Access Journals (Sweden)

    Sabrina Laouami

    Full Text Available The facultative anaerobe, Bacillus cereus, causes diarrheal diseases in humans. Its ability to deal with oxygen availability is recognized to be critical for pathogenesis. The B. cereus genome comprises a gene encoding a protein with high similarities to the redox regulator, Rex, which is a central regulator of anaerobic metabolism in Bacillus subtilis and other Gram-positive bacteria. Here, we showed that B. cereus rex is monocistronic and down-regulated in the absence of oxygen. The protein encoded by rex is an authentic Rex transcriptional factor since its DNA binding activity depends on the NADH/NAD+ ratio. Rex deletion compromised the ability of B. cereus to cope with external oxidative stress under anaerobiosis while increasing B. cereus resistance against such stress under aerobiosis. The deletion of rex affects anaerobic fermentative and aerobic respiratory metabolism of B. cereus by decreasing and increasing, respectively, the carbon flux through the NADH-recycling lactate pathway. We compared both the cellular proteome and exoproteome of the wild-type and Δrex cells using a high throughput shotgun label-free quantitation approach and identified proteins that are under control of Rex-mediated regulation. Proteomics data have been deposited to the ProteomeXchange with identifier PXD000886. The data suggest that Rex regulates both the cross-talk between metabolic pathways that produce NADH and NADPH and toxinogenesis, especially in oxic conditions.

  9. Activity of Medicinal Plant Extracts on Multiplication of Mycobacterium tuberculosis under Reduced Oxygen Conditions Using Intracellular and Axenic Assays

    Directory of Open Access Journals (Sweden)

    Purva D. Bhatter

    2016-01-01

    Full Text Available Aim. Test the activity of selected medicinal plant extracts on multiplication of Mycobacterium tuberculosis under reduced oxygen concentration which represents nonreplicating conditions. Material and Methods. Acetone, ethanol and aqueous extracts of the plants Acorus calamus L. (rhizome, Ocimum sanctum L. (leaf, Piper nigrum L. (seed, and Pueraria tuberosa DC. (tuber were tested on Mycobacterium tuberculosis H37Rv intracellularly using an epithelial cell (A549 infection model. The extracts found to be active intracellularly were further studied axenically under reducing oxygen concentrations. Results and Conclusions. Intracellular multiplication was inhibited ≥60% by five of the twelve extracts. Amongst these 5 extracts, in axenic culture, P. nigrum (acetone was active under aerobic, microaerophilic, and anaerobic conditions indicating presence of multiple components acting at different levels and P. tuberosa (aqueous showed bactericidal activity under microaerophilic and anaerobic conditions implying the influence of anaerobiosis on its efficacy. P. nigrum (aqueous and A. calamus (aqueous and ethanol extracts were not active under axenic conditions but only inhibited intracellular growth of Mycobacterium tuberculosis, suggesting activation of host defense mechanisms to mediate bacterial killing rather than direct bactericidal activity.

  10. Transcription of genes involved in sulfolipid and polyacyltrehalose biosynthesis of Mycobacterium tuberculosis in experimental latent tuberculosis infection.

    Directory of Open Access Journals (Sweden)

    Jimmy E Rodríguez

    Full Text Available The Influence of trehalose-based glycolipids in the virulence of Mycobacterium tuberculosis (Mtb is recognised; however, the actual role of these cell-wall glycolipids in latent infection is unknown. As an initial approach, we determined by two-dimensional thin-layer chromatography the sulfolipid (SL and diacyltrehalose/polyacyltrehalose (DAT/PAT profile of the cell wall of hypoxic Mtb. Then, qRT-PCR was extensively conducted to determine the transcription profile of genes involved in the biosynthesis of these glycolipids in non-replicating persistent 1 (NRP1 and anaerobiosis (NRP2 models of hypoxia (Wayne model, and murine models of chronic and progressive pulmonary tuberculosis. A diminished content of SL and increased amounts of glycolipids with chromatographic profile similar to DAT were detected in Mtb grown in the NRP2 stage. A striking decrease in the transcription of mmpL8 and mmpL10 transporter genes and increased transcription of the pks (polyketidesynthase genes involved in SL and DAT biosynthesis were detected in both the NRP2 stage and the murine model of chronic infection. All genes were found to be up-regulated in the progressive disease. These results suggest that SL production is diminished during latent infection and the DAT/PAT precursors can be accumulated inside tubercle bacilli and are possibly used in reactivation processes.

  11. Heterogeneity of dormancy in apple embryos. [Pyrus malus

    Energy Technology Data Exchange (ETDEWEB)

    Christine, B.; Camille, B.

    1986-04-01

    This study concerns the heterogeneity of embryo dormancy with the aim of investigating a possible relationship between chlorophyllogenesis and dormancy. Dormant embryos of Pyrus malus L. cv. Golden delicious were cultivated on water-agar (agar 6 g/l). They were placed flat with one cotyledon in contact with the medium. After 6 days of culture at 23/sup 0/C under fluorescent light the non-germinated embryos (99% of the total) were classified in three main categories on the basis of the state of greening of their cotyledons. By application of partial dormancy releasing treatments (chilling, anaerobiosis, GA/sub 7/), it was shown that the three categories of embryos were characterized by different depths of dormancy. Germination was most difficult for the embryos which were non pigmented after the initial culture, whereas high germination percentages were rapidly reached by embryos exhibiting high degree of greening. Evaluation of ABA by radioimmunoassay shows that the three categories of embryos also differ in their ABA and ABA-GE levels. A good correlation was thus observed between depth of dormancy and levels of ABA and ABA-GE.

  12. Deletion of Proton Gradient Regulation 5 (PGR5) and PGR5-Like 1 (PGRL1) proteins promote sustainable light-driven hydrogen production in Chlamydomonas reinhardtii due to increased PSII activity under sulfur deprivation.

    Science.gov (United States)

    Steinbeck, Janina; Nikolova, Denitsa; Weingarten, Robert; Johnson, Xenie; Richaud, Pierre; Peltier, Gilles; Hermann, Marita; Magneschi, Leonardo; Hippler, Michael

    2015-01-01

    Continuous hydrogen photo-production under sulfur deprivation was studied in the Chlamydomonas reinhardtii pgr5 pgrl1 double mutant and respective single mutants. Under medium light conditions, the pgr5 exhibited the highest performance and produced about eight times more hydrogen than the wild type, making pgr5 one of the most efficient hydrogen producer reported so far. The pgr5 pgrl1 double mutant showed an increased hydrogen burst at the beginning of sulfur deprivation under high light conditions, but in this case the overall amount of hydrogen produced by pgr5 pgrl1 as well as pgr5 was diminished due to photo-inhibition and increased degradation of PSI. In contrast, the pgrl1 was effective in hydrogen production in both high and low light. Blocking photosynthetic electron transfer by DCMU stopped hydrogen production almost completely in the mutant strains, indicating that the main pathway of electrons toward enhanced hydrogen production is via linear electron transport. Indeed, PSII remained more active and stable in the pgr mutant strains as compared to the wild type. Since transition to anaerobiosis was faster and could be maintained due to an increased oxygen consumption capacity, this likely preserves PSII from photo-oxidative damage in the pgr mutants. Hence, we conclude that increased hydrogen production under sulfur deprivation in the pgr5 and pgrl1 mutants is caused by an increased stability of PSII permitting sustainable light-driven hydrogen production in Chlamydomonas reinhardtii. PMID:26579146

  13. Deletion of Proton Gradient Regulation 5 (PGR5 and PGR5-Like 1 (PGRL1 proteins promote sustainable light-driven hydrogen production in Chlamydomonas reinhardtii due to increased PSII activity under sulfur deprivation

    Directory of Open Access Journals (Sweden)

    Janina eSteinbeck

    2015-10-01

    Full Text Available Continuous hydrogen photo-production under sulfur deprivation was studied in the Chlamydomonas reinhardtii pgr5 pgrl1 double mutant and respective single mutants. Under medium light conditions, the pgr5 exhibited the highest performance and produced about 8 times more hydrogen than the wild type, making pgr5 one of the most efficient hydrogen producer reported so far. The pgr5 pgrl1 double mutant showed an increased hydrogen burst at the beginning of sulfur deprivation under high light conditions, but in this case the overall amount of hydrogen produced by pgr5 pgrl1 as well as pgr5 was diminished due to photo-inhibition and increased degradation of PSI. In contrast, the pgrl1 was effective in hydrogen production in both high and low light. Blocking photosynthetic electron transfer by DCMU stopped hydrogen production almost completely in the mutant strains, indicating that the main pathway of electrons towards enhanced hydrogen production is via linear electron transport. Indeed, PSII remained more active and stable in the pgr mutant strains as compared to the wild type. Since transition to anaerobiosis was faster and could be maintained due to an increased oxygen consumption capacity, this likely preserves PSII from photo-oxidative damage in the pgr mutants. Hence, we conclude that increased hydrogen production under sulfur deprivation in the pgr5 and pgrl1 mutants is caused by an increased stability of PSII permitting sustainable light-driven hydrogen production in Chlamydomonas reinhardtii.

  14. Relationships between PSII-independent hydrogen bioproduction and starch metabolism as evidenced from isolation of starch catabolism mutants in the green alga Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Chochois, Vincent; Constans, Laure; Beyly, Audrey; Soliveres, Melanie; Peltier, Gilles; Cournac, Laurent [CEA, DSV, IBEB, Laboratoire de Bioenergetique et Biotechnologie des Bacteries and Microalgues, Saint Paul Lez Durance, F-13108 (France); CNRS, UMR Biologie Vegetale and Microbiologie Environnementales, Saint Paul lez Durance, F-13108 (France); Aix-Marseille Universite, Saint Paul lez Durance, F-13108 (France); Dauvillee, David; Ball, Steven [Univ Lille Nord de France, F-59000 Lille (France); USTL, UGSF, F-59650 Villeneuve d' Ascq (France); CNRS, UMR 8576, F-59650 Villeneuve d' Ascq (France)

    2010-10-15

    Sulfur deprivation, which is considered as an efficient way to trigger long-term hydrogen photoproduction in unicellular green algae has two major effects: a decrease in PSII which allows anaerobiosis to be reached and carbohydrate (starch) storage. Starch metabolism has been proposed as one of the major factors of hydrogen production, particularly during the PSII-independent (or indirect) pathway. While starch biosynthesis has been characterized in the green alga Chlamydomonas reinhardtii, little remains known concerning starch degradation. In order to gain a better understanding of starch catabolism pathways and identify those steps likely to limit the starch-dependent hydrogen production, we have designed a genetic screening procedure aimed at isolating mutants of the green alga C. reinhardtii affected in starch mobilization. Using two different screening protocols, the first one based on aerobic starch degradation in the dark and the second one on anaerobic starch degradation in the light, eighteen mutants were isolated among a library of 15,000 insertion mutants, eight (std1-8) with the first screen and ten (sda1-10) with the second. Most of the mutant strains isolated in this study showed a reduction or a delay in the PSII-independent hydrogen production. Further characterization of these mutants should allow the identification of molecular determinants of starch-dependent hydrogen production and supply targets for future biotechnological improvements. (author)

  15. Analytical approaches to photobiological hydrogen production in unicellular green algae.

    Science.gov (United States)

    Hemschemeier, Anja; Melis, Anastasios; Happe, Thomas

    2009-01-01

    Several species of unicellular green algae, such as the model green microalga Chlamydomonas reinhardtii, can operate under either aerobic photosynthesis or anaerobic metabolism conditions. A particularly interesting metabolic condition is that of "anaerobic oxygenic photosynthesis", whereby photosynthetically generated oxygen is consumed by the cell's own respiration, causing anaerobiosis in the culture in the light, and induction of the cellular "hydrogen metabolism" process. The latter entails an alternative photosynthetic electron transport pathway, through the oxygen-sensitive FeFe-hydrogenase, leading to the light-dependent generation of molecular hydrogen in the chloroplast. The FeFe-hydrogenase is coupled to the reducing site of photosystem-I via ferredoxin and is employed as an electron-pressure valve, through which electrons are dissipated, thus permitting a sustained electron transport in the thylakoid membrane of photosynthesis. This hydrogen gas generating process in the cells offers testimony to the unique photosynthetic metabolism that can be found in many species of green microalgae. Moreover, it has attracted interest by the biotechnology and bioenergy sectors, as it promises utilization of green microalgae and the process of photosynthesis in renewable energy production. This article provides an overview of the principles of photobiological hydrogen production in microalgae and addresses in detail the process of induction and analysis of the hydrogen metabolism in the cells. Furthermore, methods are discussed by which the interaction of photosynthesis, respiration, cellular metabolism, and H(2) production in Chlamydomonas can be monitored and regulated. PMID:19291418

  16. Direct inhibition by nitric oxide of the transcriptional ferric uptake regulation protein via nitrosylation of the iron

    Science.gov (United States)

    D'Autréaux, Benoît; Touati, Danièle; Bersch, Beate; Latour, Jean-Marc; Michaud-Soret, Isabelle

    2002-01-01

    Ferric uptake regulation protein (Fur) is a bacterial global regulator that uses iron as a cofactor to bind to specific DNA sequences. The function of Fur is not limited to iron homeostasis. A wide variety of genes involved in various mechanisms such as oxidative and acid stresses are under Fur control. Flavohemoglobin (Hmp) is an NO-detoxifying enzyme induced by NO and nitrosothiol compounds. Fur recently was found to regulate hmp in Salmonella typhimurium, and in Escherichia coli, the iron-chelating agent 2,2′-dipyridyl induces hmp expression. We now establish direct inhibition of E. coli Fur activity by NO. By using chromosomal Fur-regulated lacZ reporter fusion in E. coli, Fur activity is switched off by NO at micromolar concentration. In vitro Fur DNA-binding activity, as measured by protection of restriction site in aerobactin promoter, is directly sensitive to NO. NO reacts with FeII in purified FeFur protein to form a S = 1/2 low-spin FeFur–NO complex with a g = 2.03 EPR signal. Appearance of the same EPR signal in NO-treated cells links nitrosylation of the iron with Fur inhibition. The nitrosylated Fur protein is still a dimer and is stable in anaerobiosis but slowly decays in air. This inhibition probably arises from a conformational switch, leading to an inactive dimeric protein. These data establish a link between control of iron metabolism and the response to NO effects. PMID:12475930

  17. Energy-dependent intracellular translocation of proparathormone.

    Science.gov (United States)

    Chu, L L; MacGregor, R R; Cohn, D V

    1977-01-01

    We previously suggested that after synthesis, proparathormone is transferred from rough endoplasmic reticulum to the Golgi region where its conversion to parathormone occurs. We have attempted to define more closely this transfer process. In the first type of study, bovine parathyroid slices were incubated with [3H]leucine for 10 min and then radioisotope labeling was restricted by addition of a large excess of nonradioactive leucine. Under these conditions, more than 90% of the initially labeled proparathormone was converted to parathormone in 40 min. Lowered temperature in the chase period markedly inhibited the conversion. Several chemical agents were employed individually in the chase period to examine their effect on the conversion process. Antimycin A, dinitrophenol, oligomycin, and anaerobiosis (N2) inhibited the conversion, whereas sodium flouride and cycloheximide had no effect. In the second type of study, parathyroid slices were incubated with [3H]leucine for the entire incubation period. Lowered temperature and inhibitors of energy metabolism and microtubular function all lengthened the interval (lag) between the initial synthesis of [3H]parathormone. Cycloheximide, Tris, and chloroquine decreased the rates of protein synthesis and conversion, respectively, but none had any effect on the lag. We interpret the lag to represent the time of transit for proparathormone from rough endoplasmic reticulum to the Golgi region. We conclude that this transfer process is independent of the synthesis of the prohormone and its conversion to the hormone. Moreover, this translocation requires metabolic energy and appears to be mediated by microtubules.

  18. Influence of preventive dental treatment on mutans streptococci counts in patients undergoing head and neck radiotherapy

    Directory of Open Access Journals (Sweden)

    Lívia Buzati Meca

    2009-01-01

    Full Text Available The aim of this study was to evaluate the influence of chlorhexidine gluconate, sodium fluoride and sodium iodine on mutans streptococci counts in saliva of irradiated patients. MATERIAL AND METHODS: Forty-five patients were separated into three experimental groups and received chlorhexidine (0.12%, sodium fluoride (0.5% or sodium iodine (2%, which were used daily during radiotherapy and for 6 months after the conclusion of the treatment. In addition, a fourth group, composed by 15 additional oncologic patients, who did not receive the mouthwash or initial dental treatment, constituted the control group. Clinical evaluations were performed in the first visit to dental clinic, after initial dental treatment, immediately before radiotherapy, after radiotherapy and 30, 60, 90 days and 6 months after the conclusion of radiotherapy. After clinical examinations, samples of saliva were inoculated on SB20 selective agar and incubated under anaerobiosis, at 37ºC for 48 h. Total mutans streptococci counts were also evaluated by using real-time PCR, through TaqMan system, with specific primers and probes for S. mutans and S. sobrinus. RESULTS: All preventive protocols were able to reduce significantly mutans streptococci counts, but chlorhexidine gluconate was the most effective, and induced a significant amelioration of radiotherapy side effects, such as mucositis and candidosis. CONCLUSION: These results highlights the importance of the initial dental treatment for patients who will be subjected to radiotherapy for head and neck cancer treatment.

  19. Effects of anaerobic growth conditions on biomass accumulation, root morphology, and efficiencies of nutrient uptake and utilization in seedlings of some southern coastal plain

    Energy Technology Data Exchange (ETDEWEB)

    Topa, M.A.

    1984-01-01

    Seedlings of pond, and loblolly pines were grown in a non-circulating, continuously-flowing solution culture under anaerobic (0.75 mg/1 O/sub 2/) conditions to determine the effects of anaerobiosis on overall growth, root morphology and efficiencies of nutrient uptake and utilization. Although shoot growth of the 11-week old loblolly and pond was not affected by anaerobic treatment, it did significantly reduce root biomass. Sand pine suffered the largest biomass reduction. Flooding tolerance was positively correlated with morphological changes which enhanced root internal aeration. Oxygen transport from shoot to the root was demonstrated via rhizosphere oxidation experiments using indigo-carmine dye solutions and polarography. Stem and root collar lenticels were found to be the major sites of atmospheric O/sub 2/ entry for submerged roots. Longitudinal and radial pathways for gas diffusion via intercellular spaces in the pericycle and ray parenchyma, respectively, were elucidated histologically. Lenticel and aerenchyma development, and rhizosphere oxidation in roots of anaerobically-grown sand pine seedlings were minimal. Elemental analyses showed that anaerobic conditions interfered with nutrient absorption and utilization. Short-term /sup 32/P uptake experiments with intact seedlings indicated that net absorption decreased because of the reduction in root biomass. Phosphorus absorption rates were negatively correlated with internal tissue phosphorus concentrations, and root and shoot biomass. 315 refs., 25 figs., 14 tabs.

  20. SFH2 regulates fatty acid synthase activity in the yeast Saccharomyces cerevisiae and is critical to prevent saturated fatty acid accumulation in response to haem and oleic acid depletion.

    Science.gov (United States)

    Desfougères, Thomas; Ferreira, Thierry; Bergès, Thierry; Régnacq, Matthieu

    2008-01-01

    The yeast Saccharomyces cerevisiae is a facultative anaerobic organism. Under anaerobiosis, sustained growth relies on the presence of exogenously supplied unsaturated fatty acids and ergosterol that yeast is unable to synthesize in the absence of oxygen or upon haem depletion. In the absence of exogenous supplementation with unsaturated fatty acid, a net accumulation of SFA (saturated fatty acid) is observed that induces significant modification of phospholipid profile [Ferreira, Régnacq, Alimardani, Moreau-Vauzelle and Bergès (2004) Biochem. J. 378, 899-908]. In the present paper, we focus on the role of SFH2/CSR1, a hypoxic gene related to SEC14 and its involvement in lipid metabolism upon haem depletion in the absence of oleic acid supplementation. We observed that inactivation of SFH2 results in enhanced accumulation of SFA and phospholipid metabolism alterations. It results in premature growth arrest and leads to an exacerbated sensitivity to exogenous SFA. This phenotype is suppressed in the presence of exogenous oleic acid, or by a controlled expression of FAS1, one of the two genes encoding FAS. We present several lines of evidence to suggest that Sfh2p and oleic acid regulate SFA synthase in yeast at different levels: whereas oleic acid acts on FAS2 at the transcriptional level, we show that Sfh2p inhibits fatty acid synthase activity in response to haem depletion. PMID:17803462

  1. Microbiota associated with chronic osteomyelitis of the jaws

    Directory of Open Access Journals (Sweden)

    Elerson Gaetti-Jardim Júnior

    2010-12-01

    Full Text Available Chronic osteomyelitis of maxilla and mandible is rare in industrialized countries and its occurrence in developing countries is associated with trauma and surgery, and its microbial etiology has not been studied thoroughly. The aim of this investigation was to evaluate the microbiota associated with osteomyelitis of mandible or maxilla from some Brazilian patients. After clinical and radiographic evaluation, samples of bone sequestra, purulent secretion, and biopsies of granulomatous tissues from twenty-two patients with chronic osteomyelitis of mandible and maxilla were cultivated and submitted for pathogen detection by using a PCR method. Each patient harbored a single lesion. Bacterial isolation was performed on fastidious anaerobe agar supplemented with hemin, menadione and horse blood for anaerobes; and on tryptic soy agar supplemented with yeast extract and horse blood for facultative bacteria and aerobes. Plates were incubated in anaerobiosis and aerobiosis, at 37ºC for 14 and 3 days, respectively. Bacteria were cultivated from twelve patient samples; and genera Actinomyces, Fusobacterium, Parvimonas, and Staphylococcus were the most frequent. By PCR, bacterial DNA was detected from sixteen patient samples. The results suggest that cases of chronic osteomyelitis of the jaws are usually mixed anaerobic infections, reinforcing the concept that osteomyelitis of the jaws are mainly related to microorganisms from the oral environment, and periapical and periodontal infections may act as predisposing factors.

  2. D-lactate metabolism in the alga, Chlamydomonas Reinhardtii

    International Nuclear Information System (INIS)

    [14C]D-lactate rapidly accumulates in Chlamydomonas cells under anaerobic conditions from the sugar-phosphate pools which are labeled during photosynthesis with 14CO2. A soluble D-lactate dehydrogenase (30 μmol NADH oxidized/h/mg Chl), which functions only in the direction of pyruvate reduction, has been partially purified and characterized. The D-lactate is reoxidized in Chlamydomonas by a mitochondrial membrane-bound dehydrogenase. This enzyme is known in the plant literature as glycolate dehydrogenase, an enzyme of the oxidative photosynthetic carbon (C2) cycle. This dehydrogenase may be linked to the mitochondrial electron transport chain, although the direct electron acceptor is unknown. Therefore, D-lactate accumulation may be, in part, due to the shut down of electron transport during anaerobiosis. In vivo chase experiments have shown that the D-lactate turns over rapidly when algal cells, which have been grown with air levels of CO2 (0.04%), are returned to aerobic conditions in the light. Such turnover is not observed in cells which had been grown with 1 to 5% CO2. Cells grown with high CO2 have lower levels of glycolate dehydrogenase activity. They are currently using mutants of Chlamydomonas deficient in mitochondrial respiration to study the role of D-lactate oxidation in these algae

  3. Isolation of a rice gene homologous to the human putative tumor suppressor gene QM

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    QM gene was originally isolated from human by Dowdy et al during a search for a wilms′ tumor suppressor gene. Researches of QM gene focused mainly on animals and yeasts, little was known about plant QM gene. For better understanding of QM gene in rice, a QM homologous fragment was used as a probe to screen rice (Oryza sativa subsp. indica c.v. Guanglu′ ai 4) genomic DNA library,and two clones were obtained. One of them, OSQM2, encoded a highly basic protein of 184 amino acids, the sequence was about 3.1 kb long with a very special promoter region compared with other known QM genes. Seven potential G boxes could be found between -690 and -230. G box, which contains a ACGT core motif, had been reported in many plants to act as a cis acting DNA element in the regulation of genes in a variety of environmental conditions, such as ABA regulated gene expression, red light, UV light, anaerobiosis, and wounding etc. Two closely linked DRE related motifs (dehydration responsive element) could also be found between -182 and 173, which had a CCGAC conserved sequence and had been identified in many cold and drought responsive genes in Arabidopsis. Six MYC recognition sequences with the conserved motif NCANNTGN were also presented, which might be essential for ABA and drought responsive expression of the plant genes.

  4. Anaerobic side-stream reactor for excess sludge reduction: 5-year management of a full-scale plant.

    Science.gov (United States)

    Velho, V F; Foladori, P; Andreottola, G; Costa, R H R

    2016-07-15

    The long-term performances of a full-scale anaerobic side-stream reactor (ASSR) aimed at sludge reduction have been monitored for the first time, in comparison with a conventional activated sludge process (CAS). The plant was integrated with an ASSR treatment of 2293-3293 m(3). Operational parameters in the ASSR were: ORP -250 mV, interchange ratio of 7-10%, hydraulic retention time of 7 d. No worsening of effluent quality was observed in the ASSR configuration and removal efficiency of COD and NH4 was above 95%. A slight increase in the Sludge Volume Index did not cause worsening in effluent solids concentration. The observed sludge yield (Yobs) passed from 0.44 kgTSS/kgCOD in the CAS to 0.35 in the ASSR configuration. The reduction of Yobs by 20% is lower than expected from the literature where sythetic wastewater is used, indicating that sludge reduction efficiency is largely affected by inert mass fed with influent real wastewater. An increase by 45% of the ASSR volume did not promote a further reduction of Yobs, because sludge reduction is affected not solely by endogenous decay but also by other factors such as interchange ratio and aerobiosis/anaerobiosis alternation. PMID:27107390

  5. Processes of malate catabolism during the anaerobic metabolism of grape berries

    International Nuclear Information System (INIS)

    In order to precise malate fate during the anaerobic metabolism of grape, malate-3-14C was injected into Carignan berries kept in darkness at 350C under carbon dioxide atmosphere. The injection of labelled malate was effected in presence or not of non-labelled oxalate which inhibits malic enzyme (EC I.I.I.40). The analyses of the samples fixed after 3 and 7 days anaerobiosis concerned the titration of various substrates, organic acids, amino-acids and glycolysis products, and the measuring of the NADP+-malic enzyme (EC I.I.I.40) and malate dehydrogenase (EC I.I.I.40). Radioactivity is mainly observed in ethanol, amino-butyrate the non-separated group glycerate-shikimate and succinate. Malic enzyme acts in the first sequence of a process leading from malate to ethanol. Alanin synthesis seems to be stimulated in presence of oxalate. The results obtained and some hypotheses presented in the literature induce to suggest a utilization scheme for malate in the anaerobic metabolism of grape

  6. Some physical properties of wetland soils with reference to the tropics

    International Nuclear Information System (INIS)

    Some physical properties of wetland soils are reviewed with reference to the tropical regions. The soils have a common feature periodic flooding during the year. They exhibit wide variability in mechanical composition in accordance with their genesis and location. Bulk densities range from 1.0 to 1.9 Mg m-3 for mineral soils with moderate organic matter content and from about 0.02 to 0.2 Mg m-3 for organic soils. Total porosities are generally high with dominance of micropores in organic and clayey wetland soils. Shrink-swell potential is also generally high in many of these wetland types with consequent problems of crack formation. Anaerobiosis condition is a common feature in wetland soils. Also carbon dioxide levels may be excessive for normal crop development. Water-retentivity has been found to be high to very high to in a number of tropical wetland soils of medium to fine texture. In some organic soils values of over 100% (mass basis) are not uncommon. In particular, a value of up to 3000% has been reported. Water infiltration and percolation are highly variable. The heat capacities are generally high with resultant reduced temperatures. Land use and management strategies are proferred in the light of the properties. (author). 44 refs, 9 tabs

  7. Anaerobic digestion challenge of raw olive mill wastewater.

    Science.gov (United States)

    Sampaio, M A; Gonçalves, M R; Marques, I P

    2011-12-01

    Olive mill wastewater (OMW) was digested in its original composition (100% v/v) in an anaerobic hybrid. High concentrations (54-55 kg COD m(-3)), acid pH (5.0) and lack of alkalinity and nitrogen are some OMW adverse characteristics. Loads of 8 kg COD m(-3) d(-1) provided 3.7-3.8 m3 biogas m(-3) d(-1) (63-64% CH4) and 81-82% COD removal. An effluent with basic pH (8.1) and high alkalinity was obtained. A good performance was also observed with weekly load shocks (2.7-4.1, 8.4-10.4 kg COD m(-3) d(-1)) by introducing piggery effluent and OMW alternately. Biogas of 3.0-3.4 m3 m(-3) d(-1) (63-69% CH4) was reached. Developed biomass (350 days) was neither affected by raw OMW nor by organic shocks. Through the effluents complementarity concept, a stable process able of degrading the original OMW alone was obtained. Unlike what is referred, OMW is an energy resource through anaerobiosis without additional expenses to correct it or decrease its concentration/toxicity. PMID:21983408

  8. Activity of Medicinal Plant Extracts on Multiplication of Mycobacterium tuberculosis under Reduced Oxygen Conditions Using Intracellular and Axenic Assays.

    Science.gov (United States)

    Bhatter, Purva D; Gupta, Pooja D; Birdi, Tannaz J

    2016-01-01

    Aim. Test the activity of selected medicinal plant extracts on multiplication of Mycobacterium tuberculosis under reduced oxygen concentration which represents nonreplicating conditions. Material and Methods. Acetone, ethanol and aqueous extracts of the plants Acorus calamus L. (rhizome), Ocimum sanctum L. (leaf), Piper nigrum L. (seed), and Pueraria tuberosa DC. (tuber) were tested on Mycobacterium tuberculosis H37Rv intracellularly using an epithelial cell (A549) infection model. The extracts found to be active intracellularly were further studied axenically under reducing oxygen concentrations. Results and Conclusions. Intracellular multiplication was inhibited ≥60% by five of the twelve extracts. Amongst these 5 extracts, in axenic culture, P. nigrum (acetone) was active under aerobic, microaerophilic, and anaerobic conditions indicating presence of multiple components acting at different levels and P. tuberosa (aqueous) showed bactericidal activity under microaerophilic and anaerobic conditions implying the influence of anaerobiosis on its efficacy. P. nigrum (aqueous) and A. calamus (aqueous and ethanol) extracts were not active under axenic conditions but only inhibited intracellular growth of Mycobacterium tuberculosis, suggesting activation of host defense mechanisms to mediate bacterial killing rather than direct bactericidal activity. PMID:26941797

  9. Adaptation to anaerobic metabolism in two mussel species, Mytilus edulis and Mytilus galloprovincialis, from the tidal zone at Arcachon Bay, France

    Science.gov (United States)

    de Vooys, C. G. N.

    Aspects of anaerobic metabolism were investigated in two sympatric mussel species, viz. Mytilus edulis and Mytilus galloprovincialis, living in the tidal zone in Arcachon Bay, France. Specific activities of pyruvate kinase (PK) and phosphoenolpyruvate kinase (PEP-CK) were remarkably similar in the two sympatric species and generally corresponded more closely to those observed in M. galloprovincialis in the Mediterranean than with M. edulis in the Dutch Wadden Sea. However, the values for the radio PK: PEP-CK for the two species in Arcachon Bay agreed with those of intertidal M. edulis from the Dutch Wadden Sea. Succinate accumulation during the first 24 h of anaerobicsis was about the same as in M. galloprovincialis in the Mediterranean, but decreased during the second 24 h, particularly in M. edulis, obviously due to propionate formation. Decrease in ATP concentrations in the tissues during anaerobiosis corresponded to that of intertidal M. edulis from the Dutch Wadden Sea. With the exception of specific activities of PK and PEP-CK, all properties investigated in both species were as expected in intertidal mussels.

  10. Endo- and exoglucanase activities in bacteria from mangrove sediment.

    Science.gov (United States)

    Soares Júnior, Fábio Lino; Dias, Armando Cavalcante Franco; Fasanella, Cristiane Cipola; Taketani, Rodrigo Gouvêa; de Souza Lima, André Oliveira; Melo, Itamar Soares; Andreote, Fernando Dini

    2013-01-01

    The mangrove ecosystem is an unexplored source for biotechnological applications. In this unique environment, endemic bacteria have the ability to thrive in the harsh environmental conditions (salinity and anaerobiosis), and act in the degradation of organic matter, promoting nutrient cycles. Thus, this study aimed to assess the cellulolytic activities of bacterial groups present in the sediment from a mangrove located in Ilha do Cardoso (SP, Brazil). To optimize the isolation of cellulolytic bacteria, enrichments in two types of culture media (tryptone broth and minimum salt medium), both supplemented with 5% NaCl and 1% of cellulose, were performed. Tests conducted with the obtained colonies showed a higher occurrence of endoglycolytic activity (33 isolates) than exoglycolytic (19 isolates), and the degradation activity was shown to be modulated by the presence of NaCl. The isolated bacteria were clustered by BOX-PCR and further classified on the basis of partial 16S rRNA sequences as Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmicutes or Bacteroidetes. Therefore, this study highlights the importance of studies focusing on the endemic species found in mangroves to exploit them as novel biotechnological tools for the degradation of cellulose. PMID:24516466

  11. Endo-and exoglucanase activities in bacteria from mangrove sediment

    Directory of Open Access Journals (Sweden)

    Fábio Lino Soares Júnior

    2013-09-01

    Full Text Available The mangrove ecosystem is an unexplored source for biotechnological applications. In this unique environment, endemic bacteria have the ability to thrive in the harsh environmental conditions (salinity and anaerobiosis, and act in the degradation of organic matter, promoting nutrient cycles. Thus, this study aimed to assess the cellulolytic activities of bacterial groups present in the sediment from a mangrove located in Ilha do Cardoso (SP, Brazil. To optimize the isolation of cellulolytic bacteria, enrichments in two types of culture media (tryptone broth and minimum salt medium, both supplemented with 5% NaCl and 1% of cellulose, were performed. Tests conducted with the obtained colonies showed a higher occurrence of endoglycolytic activity (33 isolates than exoglycolytic (19 isolates, and the degradation activity was shown to be modulated by the presence of NaCl. The isolated bacteria were clustered by BOX-PCR and further classified on the basis of partial 16S rRNA sequences as Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmicutes or Bacteroidetes. Therefore, this study highlights the importance of studies focusing on the endemic species found in mangroves to exploit them as novel biotechnological tools for the degradation of cellulose.

  12. Gel-Entrapped Staphylococcus aureus Bacteria as Models of Biofilm Infection Exhibit Growth in Dense Aggregates, Oxygen Limitation, Antibiotic Tolerance, and Heterogeneous Gene Expression.

    Science.gov (United States)

    Pabst, Breana; Pitts, Betsey; Lauchnor, Ellen; Stewart, Philip S

    2016-10-01

    An experimental model that mimicked the structure and characteristics of in vivo biofilm infections, such as those occurring in the lung or in dermal wounds where no biomaterial surface is present, was developed. In these infections, microbial biofilm forms as cell aggregates interspersed in a layer of mucus or host matrix material. This structure was modeled by filling glass capillary tubes with an agarose gel that had been seeded with Staphylococcus aureus bacteria and then incubating the gel biofilm in medium for up to 30 h. Confocal microscopy showed that the bacteria formed in discrete pockets distributed throughout the gel matrix. These aggregates enlarged over time and also developed a size gradient, with the clusters being larger near the nutrient- and oxygen-supplied interface and smaller at greater depths. Bacteria entrapped in gels for 24 h grew slowly (specific growth rate, 0.06 h(-1)) and were much less susceptible to oxacillin, minocycline, or ciprofloxacin than planktonic cells. Microelectrode measurements showed that the oxygen concentration decreased with depth into the gel biofilm, falling to values less than 3% of air saturation at depths of 500 μm. An anaerobiosis-responsive green fluorescent protein reporter gene for lactate dehydrogenase was induced in the region of the gel where the measured oxygen concentrations were low, confirming biologically relevant hypoxia. These results show that the gel biofilm model captures key features of biofilm infection in mucus or compromised tissue: formation of dense, distinct aggregates, reduced specific growth rates, local hypoxia, and antibiotic tolerance. PMID:27503656

  13. Characterization of Monoclonal Antibodies Specific for Erwinia carotovora subsp. atroseptica and Comparison of Serological Methods for Its Sensitive Detection on Potato Tubers.

    Science.gov (United States)

    Gorris, M T; Alarcon, B; Lopez, M M; Cambra, M

    1994-06-01

    Seven monoclonal antibodies (MAbs) to Erwinia carotovora subsp. atroseptica have been produced. One, called 4G4, reacted with high specificity for serogroup I of E. carotovora subsp. atroseptica, the most common serogroup on potato tubers in different serological assays. Eighty-six strains belonging to different E. carotovora subsp. atroseptica serogroups were assayed. Some strains of serogroup XXII also reacted positively. No cross-reactions were observed against other species of plant pathogenic bacteria or 162 saprophytic bacteria from potato tubers. Only one strain of E. chrysanthemi from potato cross-reacted. A comparison of several serological techniques to detect E. carotovora subsp. atroseptica on potato tubers was performed with MAb 4G4 or polyclonal antibodies. The organism was extracted directly from potato peels of artificially inoculated tubers by soaking or selective enrichment under anaerobiosis in a medium with polypectate. MAb 4G4 was able to detect specifically 240 E. carotovora subsp. atroseptica cells per ml by indirect immunofluorescence and immunofluorescence colony staining and after soaking by ELISA-DAS (double-antibody sandwich enzyme-linked immunosorbent assay) after enrichment. The same amount of cells was detected by using immunolectrotransfer with polyclonal antibodies, and E. carotovora subsp. atroseptica and subsp. carotovora were distinguished by the latter technique. ELISA-DAS using MAb 4G4 with an enrichment step also efficiently detected E. carotovora subsp. atroseptica in naturally infected tubers and plants. PMID:16349293

  14. Risk analysis of tyramine concentration in food production

    Science.gov (United States)

    Doudová, L.; Buňka, F.; Michálek, J.; Sedlačík, M.; Buňková, L.

    2013-10-01

    The contribution is focused on risk analysis in food microbiology. This paper evaluates the effect of selected factors on tyramine production in bacterial strains of Lactococcus genus which were assigned as tyramine producers. Tyramine is a biogenic amine sythesized from an amino acid called tyrosine. It can be found in certain foodstuffs (often in cheese), and can cause a pseudo-response in sensitive individuals. The above-mentioned bacteria are commonly used in the biotechnological process of cheese production as starter cultures. The levels of factors were chosen with respect to the conditions which can occur in this technological process. To describe and compare tyramine production in chosen microorganisms, generalized regression models were applied. Tyramine production was modelled by Gompertz curves according to the selected factors (the lactose concentration of 0-1% w/v, NaCl 0-2% w/v and aero/anaerobiosis) for 3 different types of bacterial cultivation. Moreover, estimates of model parameters were calculated and tested; multiple comparisons were discussed as well. The aim of this paper is to find a combination of factors leading to a similar tyramine production level.

  15. Forever Young: Mechanisms of Natural Anoxia Tolerance and Potential Links to Longevity

    Directory of Open Access Journals (Sweden)

    Anastasia Krivoruchko

    2010-01-01

    Full Text Available While mammals cannot survive oxygen deprivation for more than a few minutes without sustaining severe organ damage, some animals have mastered anaerobic life. Freshwater turtles belonging to the Trachemys and Chrysemys genera are the champion facultative anaerobes of the vertebrate world, often surviving without oxygen for many weeks at a time. The physiological and biochemical mechanisms that underlie anoxia tolerance in turtles include profound metabolic rate depression, post-translational modification of proteins, strong antioxidant defenses, activation of specific stress-responsive transcription factors, and enhanced expression of cyto-protective proteins. Turtles are also known for their incredible longevity and display characteristics of “negligible senescence.” We propose that the robust stress-tolerance mechanisms that permit long term anaerobiosis by turtles may also support the longevity of these animals. Many of the mechanisms involved in natural anoxia tolerance, such as hypometabolism or the induction of various protective proteins/pathways, have been shown to play important roles in mammalian oxygen-related diseases and improved understanding of how cells survive without oxygen could aid in the understanding and treatment of various pathological conditions that involve hypoxia or oxidative stress. In the present review we discuss the recent advances made in understanding the molecular nature of anoxia tolerance in turtles and the potential links between this tolerance and longevity.

  16. Role of Boreal Vegetation in Controlling Ecosystem Processes and Feedbacks to Climate

    Science.gov (United States)

    Chapin, F. S., III; Hooper, D. U.; Hobbie, S. E.; Verville, J. H.

    1997-01-01

    In the field, dark respiration rates are greatest in cores from more northerly locations. This is due in part to greater amounts of dwarf shrub biomass in the more northerly cores, but also to differences in soil organic matter quality. Laboratory incubations of these soils under common conditions show some evidence for greater pools of available carbon in soils from more northerly tundra sites, although the most northerly site does not fit this pattern for reasons which are unclear at this time. While field measurements of cores transplanted among different vegetation types at the same location (Toolik Lake) show relatively small differences in whole ecosystem carbon flux, laboratory incubation of these same soils shows that there are large differences in soil respiration rates under common conditions. This is presumably due to differences in organic matter quality. Microenvironmental site factors (temperature, soil moisture, degree of anaerobiosis, etc.) may be responsible for evening out these differences in the field. These site factors, which differ with slope, aspect, and drainage within a given location along the latitudinal gradient, appear to exert at least as strong a control over carbon fluxes as do macroclimatic factors among sites across the latitudinal gradient. While our field measurements indicate that, in the short term, warming will tend to increase ecosystem losses Of CO2 via respiration more than they will increase plant gross assimilation, the degree to which different topographically-defined plant communities will respond is likely to vary.

  17. The Candida albicans Pho4 Transcription Factor Mediates Susceptibility to Stress and Influences Fitness in a Mouse Commensalism Model

    Science.gov (United States)

    Urrialde, Verónica; Prieto, Daniel; Pla, Jesús; Alonso-Monge, Rebeca

    2016-01-01

    The Pho4 transcription factor is required for growth under low environmental phosphate concentrations in Saccharomyces cerevisiae. A characterization of Candida albicans pho4 mutants revealed that these cells are more susceptible to both osmotic and oxidative stress and that this effect is diminished in the presence of 5% CO2 or anaerobiosis, reflecting the relevance of oxygen metabolism in the Pho4-mediated response. A pho4 mutant was as virulent as wild type strain when assayed in the Galleria mellonella infection model and was even more resistant to murine macrophages in ex vivo killing assays. The lack of Pho4 neither impairs the ability to colonize the murine gut nor alters the localization in the gastrointestinal tract. However, we found that Pho4 influenced the colonization of C. albicans in the mouse gut in competition assays; pho4 mutants were unable to attain high colonization levels when inoculated simultaneously with an isogenic wild type strain. Moreover, pho4 mutants displayed a reduced adherence to the intestinal mucosa in a competitive ex vivo assays with wild type cells. In vitro competitive assays also revealed defects in fitness for this mutant compared to the wild type strain. Thus, Pho4, a transcription factor involved in phosphate metabolism, is required for adaptation to stress and fitness in C. albicans.

  18. Control of Hydrogen Photoproduction by the Proton Gradient Generated by Cyclic Electron Flow in Chlamydomonas reinhardtii[W

    Science.gov (United States)

    Tolleter, Dimitri; Ghysels, Bart; Alric, Jean; Petroutsos, Dimitris; Tolstygina, Irina; Krawietz, Danuta; Happe, Thomas; Auroy, Pascaline; Adriano, Jean-Marc; Beyly, Audrey; Cuiné, Stéphan; Plet, Julie; Reiter, Ilja M.; Genty, Bernard; Cournac, Laurent; Hippler, Michael; Peltier, Gilles

    2011-01-01

    Hydrogen photoproduction by eukaryotic microalgae results from a connection between the photosynthetic electron transport chain and a plastidial hydrogenase. Algal H2 production is a transitory phenomenon under most natural conditions, often viewed as a safety valve protecting the photosynthetic electron transport chain from overreduction. From the colony screening of an insertion mutant library of the unicellular green alga Chlamydomonas reinhardtii based on the analysis of dark-light chlorophyll fluorescence transients, we isolated a mutant impaired in cyclic electron flow around photosystem I (CEF) due to a defect in the Proton Gradient Regulation Like1 (PGRL1) protein. Under aerobiosis, nonphotochemical quenching of fluorescence (NPQ) is strongly decreased in pgrl1. Under anaerobiosis, H2 photoproduction is strongly enhanced in the pgrl1 mutant, both during short-term and long-term measurements (in conditions of sulfur deprivation). Based on the light dependence of NPQ and hydrogen production, as well as on the enhanced hydrogen production observed in the wild-type strain in the presence of the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, we conclude that the proton gradient generated by CEF provokes a strong inhibition of electron supply to the hydrogenase in the wild-type strain, which is released in the pgrl1 mutant. Regulation of the trans-thylakoidal proton gradient by monitoring pgrl1 expression opens new perspectives toward reprogramming the cellular metabolism of microalgae for enhanced H2 production. PMID:21764992

  19. Factors required for the high CO2 specificity of the anaerobically induced maize GapC4 promoter in transgenic tobacco.

    Science.gov (United States)

    Niemeyer, Julia; Machens, Fabian; Fornefeld, Eva; Keller-Hüschemenger, Jens; Hehl, Reinhard

    2011-02-01

    Flooding, a natural cause of anaerobiosis, is often accompanied by high CO(2) concentrations in the flood water. Plants need to respond to these environmental conditions. Strong anaerobic reporter gene activity in tobacco (Nicotiana tabacum) controlled by the glycolytic glyceraldehyde-3-phosphate dehydrogenase (GapC4) promoter from maize (Zea mays) depends on the presence of CO(2) and light. To identify factors required for CO(2) regulated gene expression, promoter deletions fused to the β-glucuronidase reporter gene were studied in transgenic tobacco. Deletion of a 40 bp fragment directly upstream of the TATA box leads to increased anaerobic reporter gene activity both, in the presence and absence of CO(2). This deletion does not affect light specific anaerobic expression. A positive correlation between increasing CO(2) concentrations and gene activity is observed. Electrophoretic mobility shift experiments indicate that tobacco nuclear extracts harbour proteins that bind to part of the 40 bp fragment. Database assisted as well as experimental analysis reveal a role for AP2/EREBP transcription factors for conferring the high CO(2) specificity to the GapC4 promoter in tobacco leaves. This work highlights the importance for plants to respond to high environmental CO(2) concentrations under anaerobic conditions. PMID:20880205

  20. Regulation of carotenoid and bacteriochlorophyll biosynthesis genes and identification of an evolutionarily conserved gene required for bacteriochlorophyll accumulation.

    Science.gov (United States)

    Armstrong, G A; Cook, D N; Ma, D; Alberti, M; Burke, D H; Hearst, J E

    1993-05-01

    The temporal expression of ten clustered genes required for carotenoid (crt) and bacteriochlorophyll (bch) biosynthesis was examined during the transition from aerobic respiration to anaerobiosis requisite for the development of the photosynthetic membrane in the bacterium Rhodobacter capsulatus. Accumulation of crtA, crtC, crtD, crtE, crtF, crtK, bchC and bchD mRNAs increased transiently and coordinately, up to 12-fold following removal of oxygen from the growth medium, paralleling increases in mRNAs encoding pigment-binding polypeptides of the photosynthetic apparatus. The crtB and crtI genes, in contrast, were expressed similarly in the presence or absence of oxygen. The regulation patterns of promoters for the crtA and crtI genes and the bchCXYZ operon were characterized using lacZ transcriptional fusion and qualitatively reflected the corresponding mRNA accumulation patterns. We also report that the bchI gene product, encoded by a DNA sequence previously considered to be a portion of crtA, shares 49% sequence identity with the nuclear-encoded Arabidopsis thaliana Cs chloroplast protein required for normal pigmentation in plants.

  1. Plasmodesmal-mediated cell-to-cell transport in wheat roots is modulated by anaerobic stress

    Science.gov (United States)

    Cleland, R. E.; Fujiwara, T.; Lucas, W. J.

    1994-01-01

    Cell-to-cell transport of small molecules and ions occurs in plants through plasmodesmata. Plant roots are frequently subjected to localized anaerobic stress, with a resultant decrease in ATP. In order to determine the effect of this stress on plasmodesmal transport, fluorescent dyes of increasing molecular weight (0.46 to 1OkDa) were injected into epidermal and cortical cells of 3-day-old wheat roots, and their movement into neighboring cells was determined by fluorescence microscopy. Anaerobiosis was generated by N2 gas or simulated by the presence of sodium azide, both of which reduced the ATP levels in the tissue by over 80%. In the absence of such stress, the upper limit for movement, or size exclusion limit (SEL), of cortical plasmodesmata was roots, indicating that plasmodesmata may be conduits for nucleotide (ATP and ADP) exchange between cells. Upon imposition of stress, the SEL rose to between 5 and 10 kDa. This response of plasmodesmata to a decrease in the level of ATP suggests that they are constricted by an ATP-dependent process so as to maintain a restricted SEL. When roots are subjected to anaerobic stress, an increase in SEL may permit enhanced delivery of sugars to the affected cells of the root where anaerobic respiration could regenerate the needed ATP.

  2. High potential for iron reduction in upland soils.

    Science.gov (United States)

    Yang, Wendy H; Liptzin, Daniel

    2015-07-01

    Changes in the redox state of iron (Fe) can be coupled to the biogeochemical cycling of carbon (C), nitrogen, and phosphorus, and thus regulate soil C, ecosystem nutrient availability, and greenhouse gas production. However, its importance broadly in non-flooded upland terrestrial ecosystems is unknown. We measured Fe reduction in soil samples from an annual grassland, a drained peatland, and a humid tropical forest We incubated soil slurries in an anoxic glovebox for 5.5 days and added sodium acetate daily at rates up to 0.4 mg C x (g soil)(-1) x d(-1). Soil moisture, poorly crystalline Fe oxide concentrations, and Fe(II) concentrations differed among study sites in the following order: annual grassland < drained peatland < tropical forest (P < 0.001 for all characteristics). All of the soil samples demonstrated high Fe reduction potential with maximum rates over the course of the incubation averaging 1706 ± 66, 2016 ± 12, and 2973 ± 115 μg Fe x (g soil)(-1) x d(-1) (mean ± SE) for the tropical forest, annual grassland, and drained peatland, respectively. Our results suggest that upland soils from diverse ecosystems have the potential to exhibit high short-term rates of Fe reduction that may play an important role in driving soil biogeochemical processes during periods of anaerobiosis. PMID:26378323

  3. How does oxygen inhibit central metabolism in the obligate anaerobe Bacteroides thetaiotaomicron.

    Science.gov (United States)

    Pan, N; Imlay, J A

    2001-03-01

    The molecular basis of obligate anaerobiosis is not well established. Bacteroides thetaiotaomicron is an opportunistic pathogen that cannot grow in fully aerobic habitats. Because microbial niches reflect features of energy-producing strategies, we suspected that aeration would interfere with its central metabolism. In anaerobic medium, this bacterium fermented carbohydrates to a mixture of succinate, propionate and acetate. When cultures were exposed to air, the formation of succinate and propionate ceased abruptly. In vitro analysis demonstrated that the fumarase of the succinate-propionate pathway contains an iron-sulphur cluster that is sensitive to superoxide. In vivo, fumarase activity fell to PFOR), the first enzyme in the acetate fermentation branch, to 3% of its anaerobic activity. This cluster-containing enzyme was damaged in vitro by molecular oxygen but not by superoxide. Thus, aerobic growth is precluded by the vulnerability of these iron-sulphur cluster enzymes to oxidation. Importantly, both enzymes were maintained in a stable, inactive form for long periods in aerobic cells; they were then rapidly repaired when the bacterium was returned to anaerobic medium. This result explains how this pathogen can easily recover from occasional exposure to oxygen. PMID:11260473

  4. Metabolism of 5-methylthioribose to methionine

    International Nuclear Information System (INIS)

    During ethylene biosynthesis, the H3CS-group of S-adenosylmethionine is released as 5'-methylthioadenosine, which is recycled to methionine via 5-methylthioribose (MTR). In mungbean hypocotyls and cell-free extracts of avocado, [14C]MTR was converted into labeled methionine via 2-keto-4-methylthiobutyric acid (KMB) and 2-hydroxy-4-methylthiobutyric acid (HMB), as intermediates. Incubation of [ribose-U-14C]MTR with avocado extract resulted in the production of [14C]formate, indicating the conversion of MTR to KMB involves a loss of formate, presumably from C-1 of MTR. Tracer studies showed that KMB was converted readily in vivo and in vitro to methionine, while HMB was converted much more slowly. The conversion of KMB to methionine by dialyzed avocado extract requires an amino donor. Among several potential donors examined, L-glutamine was the most efficient. Anaerobiosis inhibited only partially the oxidation of MTR to formate, KMB/HMB, and methionine by avocado extract. The role of O2 in the conversion of MTR to methionine is discussed

  5. Porphyromonas gingivalis LIBRE DE POLISACÁRIDOS UTILIZANDO CROMATOGRAFÍA DE ALTA RESOLUCIÓN SEPHACRYL S-200 Purification of Porphyromonas gingivalis polysaccharide free lipopolysaccharide using Sephacryl S-200 high resolution chromatography

    Directory of Open Access Journals (Sweden)

    DIEGO GUALTERO

    Full Text Available El objetivo de este trabajo fue mejorar un método estándar para la purificación de lipopolisacárido (LPS de Porphyromonas gingivalis libre de polisacáridos usando una estrategia de extracción, digestión enzimática y cromatografía de alta resolución. La bacteria P. gingivalis se cultivó en condiciones de anaerobiosis y se hizo extracción de las membranas con el método de fenol-agua. Luego de una digestión enzimática (DNAsa, RNAsa y proteasa se separó el extracto por filtración por gel con Sephacryl S-200. La muestra purificada se caracterizó por electroforesis en gel de acrilamida con tinción de plata y por el método Purpald se detecto el ácido 2-ceto-3-desoxioctu-losónico (KDO. Se obtuvo una preparación libre de ácidos nucleicos, proteínas y polisacáridos. La separación por cromatografía fue de alta resolución al permitir la obtención de dos picos con diferentes componentes. El protocolo de purificación nos permitió obtener LPS de P. gingivalis con alto grado de pureza, el cual podría ser usado en próximos ensayos para evaluar su función en ensayos in vitro e in vivo; así como iniciar la obtención de LPS de otras bacterias periodontopáticas, con el fin de investigar la asociación de enfermedad periodontal con enfermedades cardiovasculares.The aim of this work was to improve a standard methodology to purify Porphyromonas gingivalis lipopolysaccharide (LPS using a protocol of extraction, enzymatic digestion and high resolution chromatography. P. gingivalis bacteria was cultured in anaerobiosis, their membranes were extracted using the phenol-water method, then subjected to DNAse, RNAse and protease digestion and finally, the extract was separated by chromatography using Sephacryl S-200. The purified extract was characterized by silver staining after polyacrylamide gel electrophoresis and 2-keto-3-deoxioctanoic acid (KDO was detected using the Purpald’s method. A preparation free of nucleic acid-, protein

  6. Characterization of the temporal dynamics of soil CO2 and N gas production (NO, N2O, N2) under varying environmental conditions

    Science.gov (United States)

    Wang, Rui; Butterbach-Bahl, Klaus; Brüggemann, Nicolas; Zheng, Xunhua

    2010-05-01

    - depending on the nitrate availability at the start of the experiments - for another 5-10 days, before finally no N2 production stopped. Typical rates of N2 production following establishment of anaerobiosis were up to 1500-2000 µg N kg-1 SDW h-1, whereas peak emissions of N2O or NO were approx. a factor of 2-3 lower. Our experiments clearly show that ratios of N and C gas production change very dynamically following the initialization of anaerobiosis. The obtained results are allowing to test our current understanding of denitrification in soils and to develop an improved parameterization for the denitrification process as needed for biogeochemical models. Butterbach-Bahl K., Willibald G., Papen H., 2002, Soil core method for direct simultaneous determination of N2 and N2O emissions from forest soils. Plant and Soil, 240, 105-116 Dannenmann M., Butterbach-Bahl K., Gasche R., Willibald G., Papen H., 2008, Dinitrogen emissions and the N2:N2O emission ratio of a Rendzic Leptosol as influenced by pH and forest thinning. Soil Biol. Biochem. 40, 2317-2323

  7. Eficacia de la solución de hidróxido de calcio a 20% en la reducción de microorganismos asociados a la cárie de dentina Efficacy of 20% calcium hydroxide solution for reduction of microorganisms in carious dentin

    Directory of Open Access Journals (Sweden)

    IVA Pinheiro

    2005-06-01

    Full Text Available Objetivo: Evaluar la eficácia da solución de hidróxido de calcio a 20% en la reducción de microorganismos asociados a la carie de dentina. Metodología:Treinta preparos cavitários fueron realizados en molares permanentes de 30 indivíduos entre las edades de 9 a 18 años. Solución salina reductora fue utilizada como líquido de colecta para la recuperación de microorganismos, antes y después del lavado cavitário. Las muestras fueron colocadas en placas de agar sangre de carnero e incubadas en anaerobiosis por 48 horas a 37ºC. Después Del crecimiento bacteriano, se realizo un análisis semi cuantitativo y cualitativo de las bacterias, a través de hibridización DNA-DNA para 23 tipos de bacterias. Resultados: Una reducción significativa de la cantidad de microorganismos en las muestras colectadas después del lavado de la cavidad con solución de hidróxido de calcio fue observada cuando comparado con el momento anterior al lavado. Del total de muestras que presentaron microorganismos en la cavidad recién preparada, 46,15% presentaron eliminación de éstos microorganismos después del lavado con agua de cal y 53,84% presentaron reducción significativa del número de microorganismos. El teste t pareado de Student mostró una diferencia extremamente significativa (p=0,0007 entre el momento anterior y posterior al lavado. Con relación al tipo de bacterias encontradas después Del lavado de la cavidad con solución de hidróxido de calcio, se observó reducción considerable de S. anginosus, S. mitis y S. sobrinus, así como de S. aureus y S. epidermidis, a pesar de no ser significativa (p>0,05. Conclusión: La solución de hidróxido de calcio parece ser un método de limpieza cavitária eficaz en la reducción de la microbiota asociada a la carie de dentina.Objective: This study aimed to test the effectiveness of the cavity cleansing solution (calcium hydroxide 20% in the elimination or reduction of microorganisms associated to

  8. Use of photocatalytic reduction to hasten preparation of culture media for saccharolytic Clostridium species Uso de redução fotocatalítica para acelerar preparo de meio de cultura para espécies sacarolíticas de Clostridium

    Directory of Open Access Journals (Sweden)

    Romualdo S. Fukushima

    2003-04-01

    Full Text Available Cysteine is the preferred reducing agent used in the preparation of culture media for the growth of many strictly anaerobic microorganisms; however, redox potential reduction of cysteine is very slow, making it inconvenient if the medium is needed immediately or in large quantity. The time required to reduce culture medium containing resazurin (an indicator of reducing conditions was dramatically shortened when the medium, after being injected with the reducing agent cysteine, was irradiated with incandescent light from a halogen lamp. Light intensity had an effect upon reduction time: tubes kept in the dark took more than 12 h to achieve the desired degree of anaerobiosis (measured spectrophotometrically by the bleaching of the indicator, resazurin while tubes subjected to ordinary laboratory illumination were reduced in about 2 h. When exposed to maximum light intensity (equivalent to a regular 100 watt bulb lamp tubes could be made anaerobic in less than 20 min. Cysteine was essential for the bleaching of resazurin. Evidence that adequate anaerobiosis was achieved by light irradiation was provided by the fact that four Clostridium strains and one Thermoanaerobacter strain displayed similar growth (measured by lag time, growth rate, and extent of growth in media reduced under high intensity light or under normal laboratory illumination.A cisteína é o agente redutor preferido para o preparo de meios de cultura para muitos microrganismos estritamente anaeróbicos; no entanto, a ação redutora do potencial redox da cisteína é muito lenta, tornando-a inconveniente, para o uso imediato do meio ou em grande quantidade. O tempo requerido para reduzir o meio de cultura contendo resazurina (um indicador redox foi bastante encurtado quando o meio, após ter sido injetado com o agente redutor cisteína, foi irradiado com luz incandescente proveniente de duas lâmpadas de halogênio. A intensidade da iluminação afetou o tempo gasto na redu

  9. PURIFICACIÓN DE LIPOPOLISACÁRIDO DE Porphyromonas gingivalis LIBRE DE POLISACÁRIDOS UTILIZANDO CROMATOGRAFÍA DE ALTA RESOLUCIÓN SEPHACRYL S-200

    Directory of Open Access Journals (Sweden)

    Lafaurie Gloria

    2008-12-01

    Full Text Available El objetivo de este trabajo fue mejorar un método estándar para la purificación de lipopolisacárido (LPS de Porphyromonas gingivalis libre de polisacáridos usando una estrategia de extracción, digestión enzimática y cromatografía de alta resolución. La bacteria P. gingivalis se cultivó en condiciones de anaerobiosis y se hizo extracción de las membranas con el método de fenol-agua. Luego de una digestión enzimática (DNAsa, RNAsa y proteasa se separó el extracto por filtración por gel con Sephacryl S-200. La muestra purificada se caracterizó por electroforesis en gel de acrilamida con tinción de plata y por el método Purpald se detecto el ácido 2-ceto-3-desoxioctulosónico (KDO. Se obtuvo una preparación libre de ácidos nucleicos, proteínas y polisacáridos. La separación por cromatografía fue de alta resolución al permitir la obtención de dos picos con diferentes componentes. El protocolo de purificación nos permitió obtener LPS de P. gingivalis con alto grado de pureza, el cual podría ser usado en próximos ensayos para evaluar su función en ensayos in vitro e in vivo; así como iniciar la obtención de LPS de otras bacterias períodontopáticas, con el fin de investigar la asociación de enfermedad períodontal con enfermedades cardiovasculares.

  10. Dinámica microbial del suelo asociada a diferentes estrategias de manejo de Phytophthora cinnamomi Rands en aguacate

    Directory of Open Access Journals (Sweden)

    Joaquín Guillermo Ramírez Gil

    2013-12-01

    Full Text Available La marchitez del aguacate es la enfermedad más limitante de este cultivo, cuyo agente causal más relevante es el oomycete Phytophthora cinnamomi Rands. Es por esto que se han desarrollado diferentes estrategias para su manejo integrado, pero aún prevalece el uso de productos químicos, como única medida de manejo, generando impactos negativos en el ambiente y la salud. Uno de los efectos perjudiciales que se ocasiona es la alteración de las poblaciones microbianas en el suelo. Este trabajo estuvo encaminado a conocer la dinámica microbiana del suelo, bajo diferentes estrategias de manejo de esta enfermedad, para lo cual se midió su dinamismo mediante unidades formadoras de colonias (UFC, para hongos, bacterias y actinomicetos, a partir de muestras de suelo y rizósfera de la raíz, bajo incubación en condiciones de anaerobiosis y aerobiosis, además se midió la actividad microbiana total, en condiciones de laboratorio, como complemento se cuantificaron microorganismos como: Trichiderma spp, bacterias formadoras de endosporas (BAFE, celulolíticos, proteolíticos, amilolíticos, solubilizadores de fosfato, fijadores asimbióticos de nitrógeno y promotores del crecimiento, como Pseudomonas spp., fluorescentes. Los resultados encontrados en esta investigación, sugieren que el uso individual y combinado de mantillo orgánico, material compostado de estiércol bovino, enmienda mineral y cascarilla de arroz y la propuesta de integración; incrementan significativamente la población y actividad microbiana aerobia, en la cual se identificaron microorganismos antagonistas como, Trichiderma spp., celulolíticos, Pseudomonas spp. fluorescentes y BAFE.

  11. Survival of bacteria from human dental plaque under various transport conditions.

    Science.gov (United States)

    Hoover, C I; Newbrun, E

    1977-09-01

    The effects of transport media, temperature, and anaerobiosis on the survival of bacteria from human supragingival dental plaque were studied. Individual samples were obtained by passing sterile, unwaxed dental floss through the interproximal spaces. The plaque-bearing portion of floss was immediately placed in vials containing reduced transport fluid, viability-preserving microbistatic medium, or reduced salt solution transport fluid. Plaque samples were dispersed by ultrasonic oscillation, serially diluted, and plated in duplicate on MM10-sucrose-blood agar, mitis salivarius bacitracin agar, and Rogosa tomato juice agar. Initial viable counts (time 0) were compared with viable count determinations after 48- and 72-h storage. Quantitative recovery (>30%) of various groups of oral bacteria was accomplished from both reduced transport fluid and viability-preserving microbistatic medium after 48- and 72-h storage. Storage of dental plaque in reduced salt solution proved unsatisfactory for most bacteria (less than 10% survival). Since growth of some bacteria may occur in viability-preserving microbistatic medium and the charcoal present interferes with colonly enumeration on low-dilution plates, we found reduced transport fluid to be the most suitable medium for transport and recovery of bacteria from supragingival dental plaque. Subzero storage (-196 and -40 degrees C) did not enhance the survival of bacteria from dental plaque; storage at moderate (5 and 20 degrees C) temperatures gave better recovery of viable bacteria. Survival after anaerobic or aerobic storage was comparable for total colony-forming units; however, anaerobic storage enhanced survival of Streptococcus mutans and Lactobacillus. Since these organisms are specifically associated with dental caries, anaerobic techniques are preferred for caries activity testing of plaque.

  12. Respiratory, acid-base, and metabolic responses of the Christmas Island blue crab, Cardisoma hirtipes (Dana), during simulated environmental conditions.

    Science.gov (United States)

    Dela-Cruz, J; Morris, S

    1997-01-01

    The dependency of the Christmas Island blue crab, Cardisoma hirtipes, on fresh water for respiratory gas exchange and transport was investigated in laboratory simulations. The gas exchange rates of air-breathing C. hirtipes were similar to those of other land crabs but decreased to 20% in submerged crabs. Crabs with access to air maintained arterial and pulmonary O2 content (CO2) and partial pressure (PO2), while in submerged crabs the PO2 and CO2 rapidly decreased (by 50%). There was no anaerobiosis, but haemolymph glucose concentration and cardiac output decreased when crabs were submersed, which suggests a hypometabolic state. Submersion induced a metabolic rather than a respiratory alkalosis, and since respiratory gas exchange was low, CO2 excretion to water was unimportant. Cardisoma hirtipes haemocyanin (Hc) has high O2 affinity but low pH sensitivity, which facilitates O2 uptake from hypoxic environments. The high Hc-O2 affinity supports O2 loading but may prevent access to a venous O2 reserve. Calcium, magnesium, and urate, but not L-lactate, were effectors of Hc-O2 affinity. In submerged crabs increased circulating urate maintained haemolymph O2 content. The CO2 capacitance and nonbicarbonate buffering of the haemolymph were relatively low. A significant Haldane effect seemed important for CO2 excretion but would require CO2 and O2 exchange to occur at the same organ (gills or lungs). Submersion interferes with respiration and is not needed for haemolymph acid-base balance; thus; C. hirtipes is an air-breathing crab.

  13. What It Takes to Be a Pseudomonas aeruginosa? The Core Genome of the Opportunistic Pathogen Updated.

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    Benoît Valot

    Full Text Available Pseudomonas aeruginosa is an opportunistic bacterial pathogen able to thrive in highly diverse ecological niches and to infect compromised patients. Its genome exhibits a mosaic structure composed of a core genome into which accessory genes are inserted en bloc at specific sites. The size and the content of the core genome are open for debate as their estimation depends on the set of genomes considered and the pipeline of gene detection and clustering. Here, we redefined the size and the content of the core genome of P. aeruginosa from fully re-analyzed genomes of 17 reference strains. After the optimization of gene detection and clustering parameters, the core genome was defined at 5,233 orthologs, which represented ~ 88% of the average genome. Extrapolation indicated that our panel was suitable to estimate the core genome that will remain constant even if new genomes are added. The core genome contained resistance determinants to the major antibiotic families as well as most metabolic, respiratory, and virulence genes. Although some virulence genes were accessory, they often related to conserved biological functions. Long-standing prophage elements were subjected to a genetic drift to eventually display a G+C content as higher as that of the core genome. This contrasts with the low G+C content of highly conserved ribosomal genes. The conservation of metabolic and respiratory genes could guarantee the ability of the species to thrive on a variety of carbon sources for energy in aerobiosis and anaerobiosis. Virtually all the strains, of environmental or clinical origin, have the complete toolkit to become resistant to the major antipseudomonal compounds and possess basic pathogenic mechanisms to infect humans. The knowledge of the genes shared by the majority of the P. aeruginosa isolates is a prerequisite for designing effective therapeutics to combat the wide variety of human infections.

  14. Apn1 AP-endonuclease is essential for the repair of oxidatively damaged DNA bases in yeast frataxin-deficient cells.

    Science.gov (United States)

    Lefevre, Sophie; Brossas, Caroline; Auchère, Françoise; Boggetto, Nicole; Camadro, Jean-Michel; Santos, Renata

    2012-09-15

    Frataxin deficiency results in mitochondrial dysfunction and oxidative stress and it is the cause of the hereditary neurodegenerative disease Friedreich ataxia (FA). Here, we present evidence that one of the pleiotropic effects of oxidative stress in frataxin-deficient yeast cells (Δyfh1 mutant) is damage to nuclear DNA and that repair requires the Apn1 AP-endonuclease of the base excision repair pathway. Major phenotypes of Δyfh1 cells are respiratory deficit, disturbed iron homeostasis and sensitivity to oxidants. These phenotypes are weak or absent under anaerobiosis. We show here that exposure of anaerobically grown Δyfh1 cells to oxygen leads to down-regulation of antioxidant defenses, increase in reactive oxygen species, delay in G1- and S-phases of the cell cycle and damage to mitochondrial and nuclear DNA. Nuclear DNA lesions in Δyfh1 cells are primarily caused by oxidized bases and single-strand breaks that can be detected 15-30 min after oxygen exposition. The Apn1 enzyme is essential for the repair of the DNA lesions in Δyfh1 cells. Compared with Δyfh1, the double Δyfh1Δapn1 mutant shows growth impairment, increased mutagenesis and extreme sensitivity to H(2)O(2). On the contrary, overexpression of the APN1 gene in Δyfh1 cells decreases spontaneous and induced mutagenesis. Our results show that frataxin deficiency in yeast cells leads to increased DNA base oxidation and requirement of Apn1 for repair, suggesting that DNA damage and repair could be important features in FA disease progression.

  15. Sustainable hydrogen photoproduction by phosphorus-deprived marine green microalgae Chlorella sp.

    Science.gov (United States)

    Batyrova, Khorcheska; Gavrisheva, Anastasia; Ivanova, Elena; Liu, Jianguo; Tsygankov, Anatoly

    2015-01-01

    Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S), sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P) conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5-1.8 mg Chl·L-1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture. PMID:25629229

  16. Mechanistic modeling of sulfur-deprived photosynthesis and hydrogen production in suspensions of Chlamydomonas reinhardtii.

    Science.gov (United States)

    Williams, C R; Bees, M A

    2014-02-01

    The ability of unicellular green algal species such as Chlamydomonas reinhardtii to produce hydrogen gas via iron-hydrogenase is well known. However, the oxygen-sensitive hydrogenase is closely linked to the photosynthetic chain in such a way that hydrogen and oxygen production need to be separated temporally for sustained photo-production. Under illumination, sulfur-deprivation has been shown to accommodate the production of hydrogen gas by partially-deactivating O2 evolution activity, leading to anaerobiosis in a sealed culture. As these facets are coupled, and the system complex, mathematical approaches potentially are of significant value since they may reveal improved or even optimal schemes for maximizing hydrogen production. Here, a mechanistic model of the system is constructed from consideration of the essential pathways and processes. The role of sulfur in photosynthesis (via PSII) and the storage and catabolism of endogenous substrate, and thus growth and decay of culture density, are explicitly modeled in order to describe and explore the complex interactions that lead to H2 production during sulfur-deprivation. As far as possible, functional forms and parameter values are determined or estimated from experimental data. The model is compared with published experimental studies and, encouragingly, qualitative agreement for trends in hydrogen yield and initiation time are found. It is then employed to probe optimal external sulfur and illumination conditions for hydrogen production, which are found to differ depending on whether a maximum yield of gas or initial production rate is required. The model constitutes a powerful theoretical tool for investigating novel sulfur cycling regimes that may ultimately be used to improve the commercial viability of hydrogen gas production from microorganisms. PMID:24026984

  17. Reductive dechlorination of tetrachloroethene in marine sediments: Biodiversity and dehalorespiring capabilities of the indigenous microbes.

    Science.gov (United States)

    Matturro, B; Presta, E; Rossetti, S

    2016-03-01

    Chlorinated compounds pose environmental concerns due to their toxicity and wide distribution in several matrices. Microorganisms specialized in leading anaerobic reductive dechlorination (RD) processes, including Dehalococcoides mccartyi (Dhc), are able to reduce chlorinated compounds to harmless products or to less toxic forms. Here we report the first detailed study dealing with the RD potential of heavy polluted marine sediment by evaluating the biodegradation kinetics together with the composition, dynamics and activity of indigenous microbial population. A microcosm study was conducted under strictly anaerobic conditions on marine sediment collected near the marine coast of Sarno river mouth, one of the most polluted river in Europe. Tetrachloroethene (PCE), used as model pollutant, was completely converted to ethene within 150 days at reductive dechlorination rate equal to 0.016 meq L(-1) d(-1). Consecutive spikes of PCE allowed increasing the degradation kinetics up to 0.1 meq L(-1)d(-1) within 20 days. Strictly anaerobiosis and repeated spikes of PCE stimulated the growth of indigenous Dhc cells (growth yield of ~7.0 E + 07 Dhc cells per μM Cl(-1) released). Dhc strains carrying the reductive dehalogenase genes tceA and vcrA were detected in the original marine sediment and their number increased during the treatment as demonstrated by the high level of tceA expression at the end of the microcosm study (2.41 E + 05 tceA gene transcripts g(-1)). Notably, the structure of the microbial communities was fully described by Catalysed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) as wells as the dynamics of the dechlorinating bacteria during the microcosms operation. Interestingly, a direct role of Dhc cells was ascertained suggesting the existence of strains adapted at salinity conditions. Additionally, non-Dhc Chloroflexi were retrieved in the original sediment and were kept stable over time suggesting their likely flanking role of the RD

  18. Role of oxygen in enhancement in repair of radiation injuries in Tribolium

    International Nuclear Information System (INIS)

    The oxygen enhancement ratio (OER) was determined for various biological responses in Tribolium confusum McGill Black. The biological responses included acute lethality of the adults and larvae; sexual sterilization of the male and female adults; fecundity of the females and hatchability of their eggs as well as the competitiveness of the males. The OER for acute lethality for the male and female adults was found to be 2.25-2.38, regardless of the type of inert gas used to achieve anaerobiosis. Acute lethality for the larvae showed an OER of 2.79. The OER for male and female sexual sterilization was 2.35 and 3.37 respectively. With irradiation carried out in oxygen, the results suggested that at the tissue level of the adults and the male reproductive organ, there is a certain degree of hypoxia. Sexual sterilization of the males by radiation is attributed to the induction of dominant lethal mutation in the sperms, and that of the females involves a combination of dominant lethals and decreased egg production. The OER for egg hatchability at a hatchability level of 50% of the control for irradiated females was 4.0, a surprisingly higher value than that of any other biological responses studied. The OER for fecundity of irradiated females and for male competitiveness were roughly estimated to be 2.8 and 2.3-2.7 respectively. Since the OER for male sexual sterilization is basically the same as that for acute lethality for adults, it is expected that the competitiveness, which depends on the amount of somatic damage by radiation, will not be protected to a much greater extent by anaerobic irradiation than sterilization. It is clearly demonstrated that OER values are specific for the particular end point scored. Even within the same organism, different OER can be obtained with different biological responses

  19. Sustainable Hydrogen Photoproduction by Phosphorus-Deprived Marine Green Microalgae Chlorella sp.

    Directory of Open Access Journals (Sweden)

    Khorcheska Batyrova

    2015-01-01

    Full Text Available Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S, sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5–1.8 mg Chl·L−1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture.

  20. Hypoxia and anoxia effects on alcohol dehydrogenase activity and hemoglobin content in Chironomus riparius Meigen, 1804

    Directory of Open Access Journals (Sweden)

    Valentina Grazioli

    2016-02-01

    Full Text Available The metabolic effects of low oxygen content on alcohol-dehydrogenase (ADH activity and hemoglobin (Hb concentration were investigated in IV-instar larvae of Chironomus riparius (Diptera: Chironomidae from an Italian stream. Two series of short-term (48 h experiments were carried out: exposure to (1 progressive hypoxia (95 to 5% of oxygen saturation and (2 anoxia (at <5% of oxygen saturation. In (1, Hb amount increased with increasing oxygen depletion up to a critical value of oxygenation (about 70% of oxygen saturation. Below this percentage, the Hb amount declined to values comparable with those present in the control. The respiration rate (R remained almost constant at oxygen saturation >50% and decreased significantly only after 48 h of treatment (= <5% of oxygen saturation reaching values <100 mmolO2 gAFDW-1 h-1. ADH activity showed two phases of growth, within the first 14 h and over 18 h of exposure. Overall, we inferred that i Hb might function as short-term oxygen storage, enabling animals to delay the on-set of anaerobiosis; and ii alcoholic fermentation co-occurs for a short time with aerobic respiration, becoming the prevalent metabolic pathway below 5% of oxygen saturation (<1 mg L-1. These considerations were supported also by results from anoxia exposure (2. In such condition, larvae were visibly stressed, becoming immobile after few minutes of incubation, and ADH reached higher values than in the hypoxia treatment (2.03±0.15 UADH mg prot-1. Overall, this study showed a shift from aerobic to anaerobic activity in C. riparius larvae exposed to poorly oxygenated water with an associated alteration of ADH activity and the Hb amount. Such metabolites might be valid candidate biomarkers for the environmental monitoring of running waters.

  1. Impairment of Pseudomonas aeruginosa Biofilm Resistance to Antibiotics by Combining the Drugs with a New Quorum-Sensing Inhibitor

    Science.gov (United States)

    Lajoie, Barbora; El Hage, Salome; Baziard, Genevieve; Roques, Christine

    2015-01-01

    Pseudomonas aeruginosa plays an important role in chronic lung infections among patients with cystic fibrosis (CF) through its ability to form antibiotic-resistant biofilms. In P. aeruginosa, biofilm development and the production of several virulence factors are mainly regulated by the rhl and las quorum-sensing (QS) systems, which are controlled by two N-acyl-homoserine lactone signal molecules. In a previous study, we discovered an original QS inhibitor, N-(2-pyrimidyl)butanamide, called C11, based on the structure of C4-homoserine lactone, and found that it is able to significantly inhibit P. aeruginosa biofilm formation. However, recent data indicate that P. aeruginosa grows under anaerobic conditions and forms biofilms in the lungs of CF patients that are denser and more robust than those formed under aerobic conditions. Our confocal microscopy observations of P. aeruginosa biofilms developed under aerobic and anaerobic conditions confirmed that the biofilms formed under these two conditions have radically different architectures. C11 showed significant dose-dependent antibiofilm activity on biofilms grown under both aerobic and anaerobic conditions, with a greater inhibitory effect being seen under conditions of anaerobiosis. Gene expression analyses performed by quantitative reverse transcriptase PCR showed that C11 led to the significant downregulation of rhl QS regulatory genes but also to the downregulation of both las QS regulatory genes and QS system-regulated virulence genes, rhlA and lasB. Furthermore, the activity of C11 in combination with antibiotics against P. aeruginosa biofilms was tested, and synergistic antibiofilm activity between C11 and ciprofloxacin, tobramycin, and colistin was obtained under both aerobic and anaerobic conditions. This study demonstrates that C11 may increase the efficacy of treatments for P. aeruginosa infections by increasing the susceptibility of biofilms to antibiotics and by attenuating the pathogenicity of the

  2. Profiles of nuclear and mitochondrial encoded mRNAs in developing and quiescent embryos of Artemia franciscana.

    Science.gov (United States)

    Hardewig, I; Anchordoguy, T J; Crawford, D L; Hand, S C

    1996-05-24

    Embryos of the brine shrimp Artemia franciscana are able to withstand long bouts of environmental anoxia by entering a quiescent state during which metabolism is greatly depressed. Recent evidence supports a global arrest of protein synthesis during quiescence. In this study we measured the amounts of mRNA for a mitochondrial-encoded subunit of cytochrome c oxidase (COX I) and for nuclear-encoded actin during aerobic development, anaerobiosis, and aerobic acidosis (artificial quiescence imposed by intracellular acidification under aerobic conditions). The levels of both COX I and actin transcripts increased significantly during aerobic development. COX I mRNA levels were tightly correlated with previous measures of COX catalytic activity, which suggests that COX synthesis could be regulated by message concentration during aerobic development. The ontogenetic increase for these mRNAs was blocked by anoxia and aerobic acidosis. Importantly, the levels of COX I and actin mRNA did not decline appreciably during the 6 h bouts of quiescence, even though protein synthesis is acutely arrested by these same treatments. Thus, the constancy of mRNA levels during quiescence indicate that reduced protein synthesis is not caused by message limitation, but rather, is likely controlled at the translational level. One advantage of this regulatory mechanism is the conservation of mRNA molecules during quiescence, which would potentially favor a quick resumption of translation as soon as oxygen is returned to the embryos. Finally, because anoxia and aerobic acidosis are both characterized by acidic intracellular pH, the reduction in pH may serve, directly or indirectly, as one signal regulating levels of mRNA in this embryo during quiescence. PMID:8817476

  3. Methanogenic food web in the gut contents of methane-emitting earthworm Eudrilus eugeniae from Brazil.

    Science.gov (United States)

    Schulz, Kristin; Hunger, Sindy; Brown, George G; Tsai, Siu M; Cerri, Carlos C; Conrad, Ralf; Drake, Harold L

    2015-08-01

    The anoxic saccharide-rich conditions of the earthworm gut provide an ideal transient habitat for ingested microbes capable of anaerobiosis. It was recently discovered that the earthworm Eudrilus eugeniae from Brazil can emit methane (CH4) and that ingested methanogens might be associated with this emission. The objective of this study was to resolve trophic interactions of bacteria and methanogens in the methanogenic food web in the gut contents of E. eugeniae. RNA-based stable isotope probing of bacterial 16S rRNA as well as mcrA and mrtA (the alpha subunit of methyl-CoM reductase and its isoenzyme, respectively) of methanogens was performed with [(13)C]-glucose as a model saccharide in the gut contents. Concomitant fermentations were augmented by the rapid consumption of glucose, yielding numerous products, including molecular hydrogen (H2), carbon dioxide (CO2), formate, acetate, ethanol, lactate, succinate and propionate. Aeromonadaceae-affiliated facultative aerobes, and obligate anaerobes affiliated to Lachnospiraceae, Veillonellaceae and Ruminococcaceae were associated with the diverse fermentations. Methanogenesis was ongoing during incubations, and (13)C-labeling of CH4 verified that supplemental [(13)C]-glucose derived carbon was dissimilated to CH4. Hydrogenotrophic methanogens affiliated with Methanobacteriaceae and Methanoregulaceae were linked to methanogenesis, and acetogens related to Peptostreptoccocaceae were likewise found to be participants in the methanogenic food web. H2 rather than acetate stimulated methanogenesis in the methanogenic gut content enrichments, and acetogens appeared to dissimilate supplemental H2 to acetate in methanogenic enrichments. These findings provide insight on the processes and associated taxa potentially linked to methanogenesis and the turnover of organic carbon in the alimentary canal of methane-emitting E. eugeniae. PMID:25615437

  4. Meeting reproductive demands in a dynamic upwelling system: Foraging strategies of a pursuit-diving seabird, the marbled murrelet

    Science.gov (United States)

    Peery, M.Z.; Newman, S.H.; Storlazzi, C.D.; Beissinger, S.R.

    2009-01-01

    Seabirds maintain plasticity in their foraging behavior to cope with energy demands and foraging constraints that vary over the reproductive cycle, but behavioral studies comparing breeding and nonbreeding individuals are rare. Here we characterize how Marbled Murrelets (Brachyramphus marmoratus) adjust their foraging effort in response to changes in reproductive demands in an upwelling system in central California. We radio-marked 32 murrelets of known reproductive status (9 breeders, 12 potential breeders, and 11 nonbreeders) and estimated both foraging ranges and diving rates during the breeding season. Murrelets spent more time diving during upwelling than oceanographic relaxation, increased their foraging ranges as the duration of relaxation grew longer, and reduced their foraging ranges after transitions to upwelling. When not incubating, murrelets moved in a circadian pattern, spending nighttime hours resting near flyways used to reach nesting habitat and foraging during the daytime an average of 5.7 km (SD 6.7 km) from nighttime locations. Breeders foraged close to nesting habitat once they initiated nesting and nest attendance was at a maximum, and then resumed traveling longer distances following the completion of nesting. Nonbreeders had similar nighttime and daytime distributions and tended to be located farther from inland flyways. Breeders increased the amount of time they spent diving by 71-73% when they had an active nest by increasing the number of dives rather than by increasing the frequency of anaerobiosis. Thus, to meet reproductive demands during nesting, murrelets adopted a combined strategy of reducing energy expended commuting to foraging sites and increasing aerobic dive rates. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

  5. Regulatory mechanisms controlling expression of the DAN/TIR mannoprotein genes during anaerobic remodeling of the cell wall in Saccharomyces cerevisiae.

    Science.gov (United States)

    Abramova, N E; Cohen, B D; Sertil, O; Kapoor, R; Davies, K J; Lowry, C V

    2001-03-01

    The DAN/TIR genes of Saccharomyces cerevisiae encode homologous mannoproteins, some of which are essential for anaerobic growth. Expression of these genes is induced during anaerobiosis and in some cases during cold shock. We show that several heme-responsive mechanisms combine to regulate DAN/TIR gene expression. The first mechanism employs two repression factors, Mox1 and Mox2, and an activation factor, Mox4 (for mannoprotein regulation by oxygen). The genes encoding these proteins were identified by selecting for recessive mutants with altered regulation of a dan1::ura3 fusion. MOX4 is identical to UPC2, encoding a binucleate zinc cluster protein controlling expression of an anaerobic sterol transport system. Mox4/Upc2 is required for expression of all the DAN/TIR genes. It appears to act through a consensus sequence termed the AR1 site, as does Mox2. The noninducible mox4Delta allele was epistatic to the constitutive mox1 and mox2 mutations, suggesting that Mox1 and Mox2 modulate activation by Mox4 in a heme-dependent fashion. Mutations in a putative repression domain in Mox4 caused constitutive expression of the DAN/TIR genes, indicating a role for this domain in heme repression. MOX4 expression is induced both in anaerobic and cold-shocked cells, so heme may also regulate DAN/TIR expression through inhibition of expression of MOX4. Indeed, ectopic expression of MOX4 in aerobic cells resulted in partially constitutive expression of DAN1. Heme also regulates expression of some of the DAN/TIR genes through the Rox7 repressor, which also controls expression of the hypoxic gene ANB1. In addition Rox1, another heme-responsive repressor, and the global repressors Tup1 and Ssn6 are also required for full aerobic repression of these genes.

  6. Impairment of Pseudomonas aeruginosa Biofilm Resistance to Antibiotics by Combining the Drugs with a New Quorum-Sensing Inhibitor.

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    Furiga, Aurelie; Lajoie, Barbora; El Hage, Salome; Baziard, Genevieve; Roques, Christine

    2016-03-01

    Pseudomonas aeruginosa plays an important role in chronic lung infections among patients with cystic fibrosis (CF) through its ability to form antibiotic-resistant biofilms. In P. aeruginosa, biofilm development and the production of several virulence factors are mainly regulated by the rhl and las quorum-sensing (QS) systems, which are controlled by two N-acyl-homoserine lactone signal molecules. In a previous study, we discovered an original QS inhibitor, N-(2-pyrimidyl)butanamide, called C11, based on the structure of C4-homoserine lactone, and found that it is able to significantly inhibit P. aeruginosa biofilm formation. However, recent data indicate that P. aeruginosa grows under anaerobic conditions and forms biofilms in the lungs of CF patients that are denser and more robust than those formed under aerobic conditions. Our confocal microscopy observations of P. aeruginosa biofilms developed under aerobic and anaerobic conditions confirmed that the biofilms formed under these two conditions have radically different architectures. C11 showed significant dose-dependent antibiofilm activity on biofilms grown under both aerobic and anaerobic conditions, with a greater inhibitory effect being seen under conditions of anaerobiosis. Gene expression analyses performed by quantitative reverse transcriptase PCR showed that C11 led to the significant downregulation of rhl QS regulatory genes but also to the downregulation of both las QS regulatory genes and QS system-regulated virulence genes, rhlA and lasB. Furthermore, the activity of C11 in combination with antibiotics against P. aeruginosa biofilms was tested, and synergistic antibiofilm activity between C11 and ciprofloxacin, tobramycin, and colistin was obtained under both aerobic and anaerobic conditions. This study demonstrates that C11 may increase the efficacy of treatments for P. aeruginosa infections by increasing the susceptibility of biofilms to antibiotics and by attenuating the pathogenicity of the

  7. Temperature Affects the Use of Storage Fatty Acids as Energy Source in a Benthic Copepod (Platychelipus littoralis, Harpacticoida).

    Science.gov (United States)

    Werbrouck, Eva; Van Gansbeke, Dirk; Vanreusel, Ann; De Troch, Marleen

    2016-01-01

    The utilization of storage lipids and their associated fatty acids (FA) is an important means for organisms to cope with periods of food shortage, however, little is known about the dynamics and FA mobilization in benthic copepods (order Harpacticoida). Furthermore, lipid depletion and FA mobilization may depend on the ambient temperature. Therefore, we subjected the temperate copepod Platychelipus littoralis to several intervals (3, 6 and 14 days) of food deprivation, under two temperatures in the range of the normal habitat temperature (4, 15 °C) and under an elevated temperature (24 °C), and studied the changes in FA composition of storage and membrane lipids. Although bulk depletion of storage FA occurred after a few days of food deprivation under 4 °C and 15 °C, copepod survival remained high during the experiment, suggesting the catabolization of other energy sources. Ambient temperature affected both the degree of FA depletion and the FA mobilization. In particular, storage FA were more exhausted and FA mobilization was more selective under 15 °C compared with 4 °C. In contrast, depletion of storage FA was limited under an elevated temperature, potentially due to a switch to partial anaerobiosis. Food deprivation induced selective DHA retention in the copepod's membrane, under all temperatures. However, prolonged exposure to heat and nutritional stress eventually depleted DHA in the membranes, and potentially induced high copepod mortality. Storage lipids clearly played an important role in the short-term response of the copepod P. littoralis to food deprivation. However, under elevated temperature, the use of storage FA as an energy source is compromised.

  8. Influence of hydrological fluxes on bio-geochemical processes in a peatland

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    N. Bougon

    2009-05-01

    Full Text Available Factors influencing the dynamics of nitrate and sulphate concentration observed in a south Normandy peatland were determined experimentally. The effects of high or low nitrate input, and oxic or anoxic conditions on microbial activity were investigated in bioreactors, using peat samples from field sites influenced by different hydrologic regimes. Site S, unlike site G, was characterized by the presence of hydrogeological gradients inducing water fluxes from river to peat during most of the hydrological cycle. Peat samples from both sites were subjected to similar experimental conditions to distinguish between the chemical effects (NO3-, O2 and the physical effects (hydrologic regimes.

    [Cl-], [SO42-] and [NO3-] were monitored for 240 h. Nitrate was significantly reduced in most experiments: (1 Removal of 70% of the initial nitrate content after 51 h under anoxic conditions; (2 Complete nitrate reduction after 240 h in soil from the S site. This reduction was interpreted as heterotrophic denitrification. Sulphate monitoring revealed that 400 mg/L were produced in peat from site S under aerobic conditions. Sulphate changes under anaerobiosis were not significant or, for samples from G, under any conditions. Clear differences in chloride content (deviance analysis, P<0.05, sulphate concentration and nitrate consumption dynamics (deviance analysis, P<0.0001 were observed between the G and S sites. Our results demonstrate that the rates of nitrate removal and sulphate production differ between peat samples from sites subjected to different hydrological regimes, even under similar redox and nitrate conditions. This experimental approach highlights the effect of hydrological fluxes leading to modifications of microbial activity which are likely related to changes in microbial diversity.

  9. Carbohydrate metabolism in germinating caryopses of Oryza sativa L. exposed to prolonged anoxia.

    Science.gov (United States)

    Pompeiano, Antonio; Guglielminetti, Lorenzo

    2016-09-01

    Anoxia tolerance can be evaluated not only in terms of growth or survival of plant organs during oxygen deprivation, but also in relation to carbohydrate utilization in the context of a well-modulated fermentative metabolism. Rice (Oryza spp.) is unique among cereals, in that it has the distinctive ability to germinate under complete anaerobiosis by using the starchy reserves in its seeds to fuel the anaerobic metabolism. The aim of the present study was to evaluate the ability of germinating rice seedlings to survive a long-term oxygen deficiency [40 days after sowing (DAS)] and the effects on sugar metabolism, focusing on starch degradation as well as soluble sugars transport and storage under anoxia. No significant decline in vitality occurred until 30 DAS though no recovery was detected following longer anoxic treatments. Growth arrest was observed following anoxic treatments longer that 20 DAS, in concomitance with considerably lower ethanol production. Amylolytic activity in embryos and endosperms had similar responses to anoxia, reaching maximum content 30 days after the onset of stress, following which the levels declined for the remainder of the experiment. Under anoxia, average amylolytic activity was twofold higher in embryos than endosperms. Efficient starch degradation was observed in rice under anoxia at the onset of the treatment but it decreased over time and did not lead to a complete depletion. Our analysis of α-amylase activity did not support the hypothesis that starch degradation plays a critical role in explaining differences in vitality and coleoptile growth under prolonged oxygen deprivation. PMID:27289587

  10. Transcriptional regulation of the outer membrane porin gene ompW reveals its physiological role during the transition from the aerobic to the anaerobic lifestyle of Escherichia coli

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    Minfeng eXiao

    2016-05-01

    Full Text Available Understanding bacterial physiology relies on elucidating the regulatory mechanisms and cellular functions of those differentially expressed genes in response to environmental changes. A widespread Gram-negative bacterial outer membrane protein OmpW has been implicated in the adaptation to stresses in various species. It is recently found to be present in the regulon of the global anaerobic transcription factor FNR and ArcA in E. coli. However, little is known about the physiological implications of this regulatory disposition. In this study, we demonstrate that transcription of ompW is indeed mediated by a series of global regulators involved in the anaerobiosis of E. coli. We show that FNR can both activate and repress the expression of ompW through its direct binding to two distinctive sites, -81.5 and -126.5 bp respectively, on ompW promoter. ArcA also participates in repression of ompW under anaerobic condition, but in an FNR dependent manner. Additionally, ompW is also subject to the regulation by CRP and NarL which senses the availability and types of carbon sources and respiration electron acceptors in the environment respectively, implying a role of OmpW in the carbon and energy metabolism of E. coli during its anaerobic adaptation. Molecular docking reveals that OmpW can bind fumarate, an alternative electron acceptor in anaerobic respiration, with sufficient affinity. Moreover, supplement of fumarate or succinate which belongs to the C4-dicarboxylates family of metabolite, to E. coli culture rescues OmpW-mediated colicin S4 killing. Taken together, we propose that OmpW is involved in anaerobic carbon and energy metabolism to mediate the transition from aerobic to anaerobic lifestyle in E. coli.

  11. Identification and Characterization of msf, a Novel Virulence Factor in Haemophilus influenzae.

    Science.gov (United States)

    Kress-Bennett, Jennifer M; Hiller, N Luisa; Eutsey, Rory A; Powell, Evan; Longwell, Mark J; Hillman, Todd; Blackwell, Tenisha; Byers, Barbara; Mell, Joshua C; Post, J Christopher; Hu, Fen Z; Ehrlich, Garth D; Janto, Benjamin A

    2016-01-01

    Haemophilus influenzae is an opportunistic pathogen. The emergence of virulent, non-typeable strains (NTHi) emphasizes the importance of developing new interventional targets. We screened the NTHi supragenome for genes encoding surface-exposed proteins suggestive of immune evasion, identifying a large family containing Sel1-like repeats (SLRs). Clustering identified ten SLR-containing gene subfamilies, each with various numbers of SLRs per gene. Individual strains also had varying numbers of SLR-containing genes from one or more of the subfamilies. Statistical genetic analyses of gene possession among 210 NTHi strains typed as either disease or carriage found a significant association between possession of the SlrVA subfamily (which we have termed, macrophage survival factor, msf) and the disease isolates. The PittII strain contains four chromosomally contiguous msf genes. Deleting all four of these genes (msfA1-4) (KO) resulted in a highly significant decrease in phagocytosis and survival in macrophages; which was fully complemented by a single copy of the msfA1 gene. Using the chinchilla model of otitis media and invasive disease, the KO strain displayed a significant decrease in fitness compared to the WT in co-infections; and in single infections, the KO lost its ability to invade the brain. The singly complemented strain showed only a partial ability to compete with the WT suggesting gene dosage is important in vivo. The transcriptional profiles of the KO and WT in planktonic growth were compared using the NTHi supragenome array, which revealed highly significant changes in the expression of operons involved in virulence and anaerobiosis. These findings demonstrate that the msfA1-4 genes are virulence factors for phagocytosis, persistence, and trafficking to non-mucosal sites.

  12. A Brief History of Bacterial Growth Physiology

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    Moselio eSchaechter

    2015-04-01

    Full Text Available Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid 19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism.Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the Copenhagen School. During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell.Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs.

  13. Reductive dechlorination of tetrachloroethene in marine sediments: Biodiversity and dehalorespiring capabilities of the indigenous microbes.

    Science.gov (United States)

    Matturro, B; Presta, E; Rossetti, S

    2016-03-01

    Chlorinated compounds pose environmental concerns due to their toxicity and wide distribution in several matrices. Microorganisms specialized in leading anaerobic reductive dechlorination (RD) processes, including Dehalococcoides mccartyi (Dhc), are able to reduce chlorinated compounds to harmless products or to less toxic forms. Here we report the first detailed study dealing with the RD potential of heavy polluted marine sediment by evaluating the biodegradation kinetics together with the composition, dynamics and activity of indigenous microbial population. A microcosm study was conducted under strictly anaerobic conditions on marine sediment collected near the marine coast of Sarno river mouth, one of the most polluted river in Europe. Tetrachloroethene (PCE), used as model pollutant, was completely converted to ethene within 150 days at reductive dechlorination rate equal to 0.016 meq L(-1) d(-1). Consecutive spikes of PCE allowed increasing the degradation kinetics up to 0.1 meq L(-1)d(-1) within 20 days. Strictly anaerobiosis and repeated spikes of PCE stimulated the growth of indigenous Dhc cells (growth yield of ~7.0 E + 07 Dhc cells per μM Cl(-1) released). Dhc strains carrying the reductive dehalogenase genes tceA and vcrA were detected in the original marine sediment and their number increased during the treatment as demonstrated by the high level of tceA expression at the end of the microcosm study (2.41 E + 05 tceA gene transcripts g(-1)). Notably, the structure of the microbial communities was fully described by Catalysed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) as wells as the dynamics of the dechlorinating bacteria during the microcosms operation. Interestingly, a direct role of Dhc cells was ascertained suggesting the existence of strains adapted at salinity conditions. Additionally, non-Dhc Chloroflexi were retrieved in the original sediment and were kept stable over time suggesting their likely flanking role of the RD

  14. Locomotion, respiratory physiology, and energetics of amphibious and terrestrial crabs.

    Science.gov (United States)

    Adamczewska, A M; Morris, S

    2000-01-01

    The transition from breathing air to breathing water requires physiological and morphological adaptations. The study of crustaceans in transitional habitats provides important information as to the nature of these adaptations. This article addresses the physiology of air breathing in amphibious and terrestrial crabs and their relative locomotor abilities. Potamonautes warreni is an apparently amphibious freshwater crab from southern Africa, Cardisoma hirtipes is an air-breathing gecarcinid crab with some dependency on freshwater, and Gecarcoidea natalis is an obligate air-breathing gecarcinid endemic to Christmas Island in the Indian Ocean. All three species have well-developed lungs but retain gills and show seasonally different activity patterns that, in the gercarcinids, especially G. natalis, include long-distance breeding migrations. The three species were better at breathing air than water, but P. warreni was the best at breathing water. Cardisoma hirtipes is essentially an obligate air breather and appears to experience facultative hypometabolism during immersion. Cardisoma hirtipes has a haemocyanin with a high affinity for O(2) that facilitates loading from air but makes 30% of the Hc bound O(2) inaccessible. The gecarcinids but not P. warreni show increased diffusion limitation for O(2) over the lung during exercise. Gecarcoidea natalis outperforms C. hirtipes by virtue of a unique haemolymph shunt from the lung into the gills. Paradoxically, it is modifications of the gills for aerial O(2) uptake in G. natalis that allow for relatively greater haemolymph oxygenation. Despite showing decreased arterial-venous DeltaPo(2), P. warreni increased the arterial-venous Delta[O(2)] with no recourse to anaerobiosis during 5 min exercise. In the short term, P. warreni is more adept at walking than C. hirtipes. The breeding migrations of C. hirtipes and G. natalis were completely aerobic, but G. natalis walk farther and probably faster. Seasonal changes in underlying

  15. Catalase (KatA plays a role in protection against anaerobic nitric oxide in Pseudomonas aeruginosa.

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    Shengchang Su

    Full Text Available Pseudomonas aeruginosa (PA is a common bacterial pathogen, responsible for a high incidence of nosocomial and respiratory infections. KatA is the major catalase of PA that detoxifies hydrogen peroxide (H2O2, a reactive oxygen intermediate generated during aerobic respiration. Paradoxically, PA displays elevated KatA activity under anaerobic growth conditions where the substrate of KatA, H2O2, is not produced. The aim of the present study is to elucidate the mechanism underlying this phenomenon and define the role of KatA in PA during anaerobiosis using genetic, biochemical and biophysical approaches. We demonstrated that anaerobic wild-type PAO1 cells yielded higher levels of katA transcription and expression than aerobic cells, whereas a nitrite reductase mutant ΔnirS produced ∼50% the KatA activity of PAO1, suggesting that a basal NO level was required for the increased KatA activity. We also found that transcription of the katA gene was controlled, in part, by the master anaerobic regulator, ANR. A ΔkatA mutant and a mucoid mucA22 ΔkatA bacteria demonstrated increased sensitivity to acidified nitrite (an NO generator in anaerobic planktonic and biofilm cultures. EPR spectra of anaerobic bacteria showed that levels of dinitrosyl iron complexes (DNIC, indicators of NO stress, were increased significantly in the ΔkatA mutant, and dramatically in a ΔnorCB mutant compared to basal levels of DNIC in PAO1 and ΔnirS mutant. Expression of KatA dramatically reduced the DNIC levels in ΔnorCB mutant. We further revealed direct NO-KatA interactions in vitro using EPR, optical spectroscopy and X-ray crystallography. KatA has a 5-coordinate high spin ferric heme that binds NO without prior reduction of the heme iron (Kd ∼6 μM. Collectively, we conclude that KatA is expressed to protect PA against NO generated during anaerobic respiration. We proposed that such protective effects of KatA may involve buffering of free NO when potentially toxic

  16. Energy-limited tolerance to stress as a conceptual framework to integrate the effects of multiple stressors.

    Science.gov (United States)

    Sokolova, Inna M

    2013-10-01

    Integrating the effects of multiple stressors and predicting their consequences for the species' survival and distribution is an important problem in ecological physiology. This review applies the concept of energy-limited tolerance to stress to develop bioenergetic markers that can assist in integrating the effects of multiple stressors and distinguishing between the moderate stress compatible with long-term survival of populations and bioenergetically unsustainable extreme stress. These markers reflect the progressive decline of the aerobic scope of an organism (defined as the fraction of the energy flux and metabolic power supporting this flux available after the basal maintenance costs of an organism are met) with increasing levels of the environmental stress. During the exposure to moderate stress (i.e., in the pejus range of the environmental conditions), the aerobic scope is positive but reduced compared with the optimum conditions. The reduction of the metabolic scope can be due to the (1) elevated costs of basal metabolism, (2) activation of the mechanisms for protection and damage repair, (3) reduced assimilation of food, and/or (4) stress-induced impacts on the aerobic pathways producing ATP. This leads to suboptimal growth and reproductive rates in the pejus range of environmental conditions and is commonly observed in food-limited and energy-limited wild populations. The tolerance windows of the organisms are delimited by the pessimum range(s) of environmental conditions in which the aerobic scope of the organism disappears (so that all available energy and metabolic capacity are used in support of basal metabolism), energy resources are depleted, and partial anaerobiosis and/or metabolic rate depression set in. The habitats where environmental conditions remain in the pessimum zone long enough to prevent consistent growth and reproduction often coincide with the species' distributional limits. Thus, focus on the bioenergetic effects of environmental

  17. Cuantificación, aislamiento e identificaciónde comunidades anaerobias amilolíticas de un manantial termomineral de Paipa, Boyacá

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    Posada Yully

    2004-12-01

    Full Text Available Se cuantif icaron microorganismos anaerobios termofílicos amilolíticos de un manantial termomineral en la región andina (5° 45' 69’’ N, 73° 6' 61’’ W, 2500 msnm a través del Número Más Probable (NMP. Los recuentos microbianos de las poblaciones presentaron valores entre 1,9*102 células/100 mL y 5.8*102 células/100 mL en presencia de almidón y tiosulfato como aceptor de electrones y 1,4*102células/100 mL y 3,4*102 células/100 mL en presencia solamente de almidón. Se realizaron aislamientos microbianos a partir de las últimas diluciones positivas del NMP y se aislaron 8 cepas bacterianas denominadas P4-6, P4-7, P4-8, P4-9, P4-10, P4-11, P4-12 y P4-13. Estas cepas crecieron a temperaturas óptimas entre 60 y 65 °C, y exhibieron un metabolismo fermentativo. El principal producto de fermentación fue etanol seguido de acetato, CO2 e hidrógeno. El tiosulfato fue utilizado como aceptor externo de electrones, pero el sulfato o el hierro férrico no fue reducido. La diversidad filogenética de estas 8 cepas fue evaluada por medio de geles de electroforesis de gradiente denaturalizante (DGGE. Se analizó la secuencia del gen 16S rRNA de dos de las cepas aisladas (P4-6 y P4-9 y el análisis indicó que éstas pertenecen a la familia Thermoanaerobiaceae del dominio Bacteria. Del análisis fenotípico y genotípico se deduce que estos organismos pertenecen al género Thermoanaerobacter, y con base en el análisis de las secuencias del 16S rDNA se observa una similitud del 98% con Thermoanaerobacter italicus y Thermoanaerobacter mathranii. Palabras clave: termofilia, manantiales termominerales, anaerobiosis, Thermoanaerobacter, DGGE.

  18. ISOLATION OF ANAEROBES IN DEEP SEATED PRESSURE ULCERS USING A NOVEL INNOVATIVE TECHNIQUE OF ANAEROBE ISOLATION

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    Lalbiaktluangi

    2015-12-01

    recommended E-test technique. In 50% cases of Bacteroides fragilis, resistance to Metronidazole was seen. CONCLUSION The advantage of this innovative technique of anaerobe isolation is, it is cost-effective and can be used in resource constrained settings and anaerobiosis is achieved at the bedside of the patient.

  19. Occurrence of Actinobacillus actinomycetemcomitans in patients with chronic periodontitis, aggressive periodontitis, healthy subjects and children with gingivitis in two cities of the state of São Paulo, Brazil Ocorrência de Actinobacillus actinomycetemcomitans em pacientes com periodontite crônica, periodontite agressiva, pessoas saudáveis e crianças com gengivite em duas cidades do Estado de São Paulo, Brasil

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    Elerson Gaetti Jardim Júnior

    2006-06-01

    Full Text Available The aim of this study was to determine the frequency of isolation of Actinobacillus actinomycetemcomitans (Aa in 100 patients with chronic periodontitis, 14 patients with aggressive periodontitis, 142 pre-school children with gingivitis and 134 periodontally healthy subjects. Samples of subgingival plaque were taken using sterilized paper points introduced into periodontal pockets or gingival crevice for 60 seconds and inoculated on TSBV agar, which was incubated under anaerobiosis at 37ºC, for 4 days. Microbial identification was performed through biochemical methods and morphocellular and morphocolonial analysis. Aa was detected in 40.3% of healthy subjects, 68% of patients with chronic periodontitis, 92.86% of patients with aggressive periodontitis and 40.14% of children with gingivitis. The rate of recovery of Aa in the tested human groups proved to be higher than previously reported and in agreement with participation of this facultative anaerobe as a member of native microbiota of the periodontium and its relation with aggressive and chronic periodontitis in Brazil.Avaliou-se a ocorrência de Actinobacillus actinmycetemcomitans (Aa em pacientes 100 pacientes com periodontite crônica, 14 com doença periodontal agressiva, 142 crianças com gengivite em idade pré-escolar e 134 indivíduos adultos saudáveis. Amostras de placa subgengival foram coletadas usando cones de papel estéreis introduzidos nas bolsas periodontais ou no sulco gengival por 60 segundos e inoculadas em ágar TSBV, que foram incubadas em anaerobiose a 37ºC, por 4 dias. A identificação microbiana foi realizada através de análises bioquímicas, morfocelulares e morfocoloniais. Aa foi detectado em 40,3% de indivíduos saudáveis, 68% de pacientes com periodontite crônica, 92,86% de pacientes com periodontite agressiva e 40,14% das crianças com gengivite. A taxa de ocorrência de Aa nos grupos testados provou ser mais alta do que a previamente descrita na literatura

  20. Clonado de cepas de Tritrichomonas foetus obtenidas de infecciones naturales en bovinos Cloned strains of Tritrichomonas foetus obtained from natural infections in cattle

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    M.L. Doumecq

    2011-12-01

    Full Text Available El objetivo del presente trabajo es describir una técnica sencilla para clonar cepas de Tritrichomonas foetus en un medio sólido. A partir de diferentes cepas obtenidas de infecciones naturales de bovinos se ensayaron dos técnicas: Homogeneizado en tubo y Homogeneizado en placa. Para cada una de ellas se evaluaron diferentes concentraciones de agar en el medio de cultivo y el tiempo de incubación más apropiado. Los resultados obtenidos demostraron que la técnica más adecuada fue la técnica de Homogeneizado en placa, con una concentración de agar 0,45 g % p/v y un tiempo de incubación de 5 días en anaerobiosis. Esta técnica resulta un procedimiento útil y sencillo para la obtención de clones de T. foetus ya que permite el crecimiento de protozoarios en colonias aisladas sobre un medio sólido. Además la técnica puede ser utilizada para evaluar la producción de colonias hemolíticas por la presencia de glóbulos rojos en el medio de cultivo.The aim of this work is to describe a simple technique to cloned strain of Tritrichomonas foetus in a solid medium. From different strains from natural infections in cattle two techniques: Homogenized in tube and Homogenized in plate were tested. The must appropriate agar concentrations in the culture medium and incubation time were evaluated for each techniques. The results showed that the most appropriate technique was Homogenized in plate with an agar concentration of 0.45 g% w /v and an incubation time of 5 days. This technique is a useful and easy to obtain clones of T. foetus, allows the growth of protozoa in isolated colonies on solid media. Furthermore the technique can be used to evaluate the production of hemolytic colonies for the presence of bovine red blood cells in the culture medium.

  1. Regulation of glutamine synthetase, aspartokinase, and total protein turnover in Klebsiella aerogenes.

    Science.gov (United States)

    Fulks, R M; Stadtman, E R

    1985-12-13

    When suspensions of Klebsiella aerogenes are incubated in a nitrogen-free medium there is a gradual decrease in the levels of acid-precipitable protein and of aspartokinase III (lysine-sensitive) and aspartokinase I (threonine-sensitive) activities. In contrast, the level of glutamine synthetase increases slightly and then remains constant. Under these conditions, the glutamine synthetase and other proteins continue to be synthesized as judged by the incorporation of [14C]leucine into the acid-precipitable protein fraction and into protein precipitated by anti-glutamine synthetase antibodies, by the fact that growth-inhibiting concentrations of chloramphenicol also inhibit the incorporation of [14C]leucine into protein and into protein precipitated by anti-glutamine synthetase antibody, and by the fact that chloramphenicol leads to acceleration in the loss of aspartokinases I and III and promotes a net decrease in the level of glutamine synthetase and its cross-reactive protein. The loss of aspartokinases I and III in cell suspensions is stimulated by glucose and is inhibited by 2,4-dinitrophenol. Glucose also stimulates the loss of aspartokinases and glutamine synthetase in the presence of chloramphenicol. Cell-free extracts of K. aerogenes catalyze rapid inactivation of endogenous glutamine synthetase as well as exogenously added pure glutamine synthetase. This loss of glutamine synthetase is not associated with a loss of protein that cross-reacts with anti-glutamine synthetase antibodies. The inactivation of glutamine synthetase in extracts is not due to adenylylation. It is partially prevented by sulfhydryl reagents, Mn2+, antimycin A, 2,4-dinitrophenol, EDTA, anaerobiosis and by dialysis. Following 18 h dialysis, the capacity of extracts to catalyze inactivation of glutamine synthetase is lost but can be restored by the addition of Fe2+ (or Ni2+) together with ATP (or other nucleoside di- and triphosphates. After 40-60 h dialysis Fe3+ together with NADH (but

  2. Autodepuração de cursos d´água: um programa de modelagem Streeter Phelps com calibração automática e correção de anaerobiose Self-depuration in watercourses: a program for Streeter Phelps modeling with automatic calibration and correction for anaerobic conditions

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    Iury Steiner de Oliveira Bezerra

    2008-06-01

    Full Text Available Foi desenvolvido um programa usando Object Pascal e Matlab, para o modelo de Streeter Phelps de autodepuração. Foram incorporadas condições de contorno, sugeridas por Chapra, que propiciam: a simulação do perfil de OD e DBO5 considerando várias entradas de efluentes ao longo do curso d'água e a correção para condições de anaerobiose, condições estas que contribuem com o surgimento de concentrações negativas de OD e conduzem a previsões errôneas. Foi, também, incorporada uma metodologia de calibração automática, baseada na minimização dos erros quadráticos entre as concentrações calculadas e observadas, para obtenção e escolha dos valores dos coeficientes de desoxigenação e reaeração. Para o teste do programa, foram feitas várias simulações: uma para testar o método de calibração automática e outras duas para testar as condições de contorno. Em todos os casos, os resultados obtidos produziram bons desempenhos. O aplicativo executável servirá como ferramenta auxiliar no meio acadêmico, como recurso didático, em aulas de saneamento ambiental, e como ferramenta de gestão da qualidade das águas.Using Object Pascal and Matlab, a program was developed for Streeter Phelps modeling of self-purification. Boundary conditions suggested by Chapra were incorporated that permit the simulation of DO and BOD5 profiles considering multiple point sources along the flow path and a correction for conditions of anaerobiosis, which lead to negative DO and erroneous previsions in Streeter Phelps modeling. A method of automatic calibration, based on minimizing square deviations between simulated and observed concentrations, for obtaining the coefficients of deoxygenation and reaeration, was incorporated also. Various simulations for testing the program were performed: one for automatic calibration and two for boundary conditions. In all cases a good performance was obtained. The program may serve equally as a teaching

  3. Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

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    Julie P M Viala

    Full Text Available During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i to survive an extreme acid shock, (ii to grow at mild acidic pH and (iii to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

  4. Characterization of the pelL gene encoding a novel pectate lyase of Erwinia chrysanthemi 3937.

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    Lojkowska, E; Masclaux, C; Boccara, M; Robert-Baudouy, J; Hugouvieux-Cotte-Pattat, N

    1995-06-01

    Erwinia chrysanthemi 3937 secretes five major isoenzymes of pectate lyases encoded by the pelA, pelB, pelC, pelD and pelE genes. Recently, a new set of pectate lyases was identified in E. chrysanthemi mutants deleted of those pel genes. We cloned the pelL gene, encoding one of these secondary pectate lyases of E. chrysanthemi 3937, from a genomic bank of a strain deleted of the five major pel genes. The nucleotide sequence of the region containing the pelL gene was determined. The pelL reading frame is 1275 bases long, corresponding to a protein of 425 amino acids including a typical amino-terminal signal sequence of 25 amino acids. Comparison of the amino acid sequences of PelL and the exo-pectate lyase PelX of E. chrysanthemi EC16 revealed a low homology, limited to 220 residues of the central part of the proteins. No homology was detected with other bacterial pectinolytic enzymes. Regulation of pelL transcription was analysed using gene fusion. As shown for the other pel genes, the transcription of pelL is dependent on various environmental conditions. It is induced by pectic catabolic products and affected by growth phase, temperature, iron starvation, osmolarity, anaerobiosis, nitrogen starvation and catabolite repression. Regulation of pelL expression appeared to be independent of the KdgR repressor, which controls all the steps of pectin catabolism. In contrast, the pecS gene, which is involved in regulation of the synthesis of the major pectate lyases and of cellulase, also appeared to be involved in pelL expression. The PelL protein is able to macerate plant tissue. This enzyme has a basic isoelectric point, presents an endo-cleaving activity on polygalacturonate or partially methylated pectin, with a basic pH optimum and an absolute requirement for Ca2+. The pelL mutant displayed a reduced virulence on potato tubers and Saintpaulia ionantha plants, demonstrating the important role of this enzyme in soft-rot disease. PMID:8577252

  5. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., organism and high (>90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions, equilibrium carbon isotope

  6. Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements Retenção de microrganismos bucais em cimentos de ionômero de vidro convencionais e modificados por resina

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    Denise PEDRINI

    2001-09-01

    Full Text Available Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R and resin-modified (Vitremer and Fuji II LC glass-ionomer cements, in situ, using a hybrid composite resin (Z100 as a control. Twelve volunteers wore Hawley appliances with specimens made of all tested filling materials for 7 days. The specimens were then removed from the appliances and transferred to tubes containing 2.0 ml of Ringer-PRAS. Microorganisms from the samples were inoculated onto blood agar and Mitis Salivarius Bacitracin agar and incubated under anaerobiosis (90% N2, 10% CO2, at 37°C, for 10 and 2 days, respectively. The resin-modified glass-ionomer cements and the composite resin retained the same levels of microorganisms on their surfaces. The resin-modified glass-ionomers retained less mutans streptococci than the composite resin and conventional glass-ionomer cements. The conventional glass-ionomer cements retained less mutans streptococci than the composite resin, but that difference was not statistically significant.A cárie secundária representa problema de saúde pública e socioeconômico no mundo. A restauração de dentes acometidos por cárie pode criar condições favoráveis à proliferação microbiana na superfície do material restaurador ou na interface dente/restauração, criando ambiente propício para o estabelecimento de cárie secundária. O objetivo deste estudo foi avaliar a capacidade de retenção de placa bacteriana em cimentos de ionômero de vidro convencionais (Chelon-Fil e Vidrion R e modificados por resina (Vitremer e Fuji II LC e de resina composta híbrida (Z100, utilizada como controle. Nos testes de reten

  7. Swine manure post-treatment technologies for pathogenic organism inactivation Tecnologias de pós-tratamento de dejetos suínos para inativar organismos patogênicos

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    Patrícia Bilotta

    2013-04-01

    Full Text Available Swine manure agricultural use is a common practice in Brazil. Their physic-chemical characteristics favor its use as biofertilizer, but the presence of pathogens may become a risk to human health. This research presents a qualitative study of the main alternatives of pig manure disinfection, analyzing efficiency, advantages and limitations of each procedure. The disinfection studies reported in literature are based on the following treatments: alkaline, thermal, biological, chemical, and physical. The greater efficiencies are in thermal treatment (> 4 log: 60 °C, chemical treatment (3 to 4 log: 30mg Cl- L-1; 3 to 4 log: 40 mg O3 L-1 and physical treatment (3 a 4 log: 220 mJ UV radiation cm-2. The biological treatment (anaerobiosis also promotes the pathogen reduction of swine manure, however with lower efficiency (1 to 2 log. The selection of the treatment should consider: implementation and operation cost, necessity of preliminary treatment, efficiency obtained and destination of the treated manure (agricultural use, water reuse. Brazilian regulation does not have specific guidelines for the microbiological quality of animal production effluents that is very important to be considered due to confined animal feeding operation transformation in the last years in the country.O uso agrícola de dejetos suínos é uma prática comum no Brasil. Suas características físico-químicas favorecem seu aproveitamento como biofertilizante, porém a presença de patógenos pode representar um risco à saúde humana. Este trabalho apresenta um estudo qualitativo das principais alternativas de desinfecção de dejetos suínos, analisando eficiência, vantagens e limitações de cada procedimento. Os estudos de desinfecção reportados na literatura são baseados nos seguintes tratamentos: alcalino, térmico, biológico, químico e físico. As maiores eficiências de redução de patógenos estão no tratamento térmico (>4 log: 60 °C, tratamento químico (3

  8. Aggregatibacter actinomycetemcomitansarcB influences hydrophobic properties, biofilm formation and adhesion to hydroxyapatite ArcB em Aggregatibacter actinomycetmcomitans influencia propriedades hidrofóbicas, formação de biofilme e aderência a hidroxiapatita

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    PL Longo

    2009-09-01

    Full Text Available The regulation of gene expression in the oral pathogen Aggregatibacter actinomycetemcomitans is still not fully elucidated. ArcAB is a two-component system which allows facultative anaerobic bacteria to sense various respiratory growth conditions and adapt their gene expression accordingly. This study investigated in A. actinomycetemcomitans the role of arcB on the regulation of biofilm formation, adhesion to saliva coated hydroxyapatite (SHA and the hydrophobic properties of the cell. These phenotypic traits were determined for an A. actinomycetemcomitansarcB deficient type and a wild type strain. Differences in hydrophobic properties were shown at early and late exponential growth phases under microaerobic incubation and at late exponential phase under anaerobiosis. The arcB mutant formed less biofilm than the wild type strain when grown under anaerobic incubation, but displayed higher biofilm formation activity under microaerobic conditions. The adherence to SHA was significantly lower in the mutant when compared with the wild type strain. These results suggest that the transmembrane sensor kinase arcB, in A. actinomycetemcomitans, senses redox growth conditions and regulates the expression of surface components of the bacterial cell related to biofilm formation and adhesion to saliva coated surfaces.A regulação da expressão gênica do patógeno oral Aggregatibacter actinomycetemcomitans não está completamente descrita. O sistema de dois componentes ArcAB permite que bactérias anaeróbias facultativas percebam diferenças nas condições respiratórias durante sua multiplicação e adaptem a expressão de genes à estas condições. Este estudo investigou em A. actinomycetemcomitans o papel de arcB na regulação da formação de biofilme, aderência à hidroxiapatita recoberta por saliva (SHA e nas propriedades hidrofóbicas celulares. Estas características fenotípicas foram determinadas para uma linhagem de A. actinomycetemcomitans

  9. Antimicrobial activity of Lactobacillus and Bifidobacterium strains against pathogenic microorganisms “in vitro”Atividade antimicrobiana de Lactobacillus e Bifodobacterium frente a microrganismos patogênicos “in vitro”

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    Giselle Nobre Costa

    2012-10-01

    Full Text Available Lactobacilli and bifidobacteria have a long history of safe use in foods. These bacteria have biotechnological characteristics of interest such as the inhibition of pathogens. In this work, two lactobacilli strain and a bifidobacterium strain isolated from human gut were evaluated concerning to their ability to inhibit pathogenic microorganisms in foods by diffusion agar tests. Moreover, we assessed the metabolites produced in culture broth under static and shaking growth to simulate anaerobiosis and aerobiosis conditions, respectively. L. acidophilus LA5, L. plantarum DCTA 8420 and B. lactis DCTA 8724 showed ability to inhibit S. aureus FRI 196, strains producer toxins A and D, as well as B. cereus ATCC 25923, E. coli ATCC 25922 and S. Enteritidis, whose inhibition halos reached, on average, 24 mm in diameter. In the agar diffusion method with concentrated culture medium, it was possible to observe the effect of oxygen on the production of toxic substances. This result showed that cultivation of Lactobacillus under aerobic conditions seems to exert greater inhibitory effect, whereas for Bifidobacterium strain the effect was the opposite.Lactobacilos e bifidobactérias apresentam um longo histórico de uso seguro em alimentos, além de apresentarem características de interesse biotecnológico como a inibição de patógenos. Neste trabalho duas linhagens de lactobacilos e uma de bifidobactéria, isoladas do intestino humano, foram avaliadas em testes de difusão em ágar, quanto à capacidade de inibição de microrganismos patogênicos de ocorrência comuns em toxinfecções alimentares. Adicionalmente, foram avaliados os metabólitos produzidos em caldo de cultivo estático e em agitação para simular condições de anaerobiose a aerobiose, respectivamente. As três bactérias, L. acidophilus LA5, L. plantarum DCTA 8420 e B. lactis DCTA 8724 apresentaram capacidade de inibição para S. aureus FRI 196 linhagem produtora de toxinas A e D

  10. Regulation of nitrogen fixation in Klebsiella pneumoniae and Azotobacter vinelandii: NifL, transducing two environmental signals to the nif transcriptional activator NifA.

    Science.gov (United States)

    Schmitz, Ruth A; Klopprogge, Kai; Grabbe, Roman

    2002-05-01

    The enzymatic reduction of molecular nitrogen to ammonia requires high amounts of energy, and the presence of oxygen causes the catalyzing nitrogenase complex to be irreversible inactivated. Thus nitrogen-fixing microorganisms tightly control both the synthesis and activity of nitrogenase to avoid the unnecessary consumption of energy. In the free-living diazotrophs Klebsiella pneumoniae and Azotobacter vinelandii, products of the nitrogen fixation nifLA operon regulate transcription of the other nifoperons. NifA activates transcription of nif genes by the alternative form of RNA-polymerase, sigma54-holoenzyme; NifL modulates the activity of the transcriptional activator NifA in response to the presence of combined nitrogen and molecular oxygen. The translationally-coupled synthesis of the two regulatory proteins, in addition to evidence from studies of NifL/NifA complex formation, imply that the inhibition of NifA activity by NifL occurs via direct protein-protein interaction in vivo. The inhibitory function of the negative regulator NifL appears to lie in the C-terminal domain, whereas the N-terminal domain binds FAD as a redox-sensitive cofactor, which is required for signal transduction of the internal oxygen status. Recently it was shown, that NifL acts as a redox-sensitive regulatory protein, which modulates NifA activity in response to the redox-state of its FAD cofactor, and allows NifA activity only in the absence of oxygen. In K. pneumoniae, the primary oxygen sensor appears to be Fnr (fumarate nitrate reduction regulator), which is presumed to transduce the signal of anaerobiosis towards NifL by activating the transcription of gene(s) whose product(s) function to relieve NifL inhibition through reduction of the FAD cofactor. In contrast, the reduction of A. vinelandii-NifL appears to occur unspecifically in response to the availability of reducing equivalents in the cell. Nitrogen status of the cells is transduced towards the NifL/NifA regulatory system

  11. Azospirillum, a free-living nitrogen-fixing bacterium closely associated with grasses: genetic, biochemical and ecological aspects.

    Science.gov (United States)

    Steenhoudt, O; Vanderleyden, J

    2000-10-01

    nitrogen-status. NifL was found to be a redox-sensitive flavoprotein. The relief of NifL inhibition on NifA activity, in response to N-limitation, is suggested to involve a P(II)-like protein. Moreover, nitrogenase activity is regulated according to the intracellular nitrogen and O(2) level. In A. brasilense and Azospirillum lipoferum posttranslational control of nitrogenase, in response to ammonium and anaerobiosis, involves ADP-ribosylation of the nitrogenase iron protein, mediated by the enzymes DraT and DraG. At least three pathways for indole-3-acetic acid (IAA) biosynthesis in A. brasilense exist: two Trp-dependent (the indole-3-pyruvic acid and presumably the indole-3-acetamide pathway) and one Trp-independent pathway. The occurrence of an IAA biosynthetic pathway not using Trp (tryptophan) as precursor is highly unusual in bacteria. Nevertheless, the indole-3-pyruvate decarboxylase encoding ipdC gene is crucial in the overall IAA biosynthesis in Azospirillum. A number of genes essential for Trp production have been isolated in A. brasilense, including trpE(G) which codes for anthranilate synthase, the key enzyme in Trp biosynthesis. The relevance of each of these four aspects for plant growth promotion by Azospirillum is discussed. PMID:10978548

  12. In vitro effect of intracanal medicaments on strict anaerobes by means of the broth dilution method Efeito in vitro de medicações intracanal sobre anaeróbios estritos pelo método de diluição em caldo

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    Odila Pereira da Silva ROSA

    2002-03-01

    Full Text Available The determination of bacterial susceptibility to intracanal medicaments is a necessity. Nevertheless, few studies utilize the proper methodology to carry out that evaluation with anaerobes. In this study, the steps of a broth dilution method, carried out in microplates (microdilution and tubes (macrodilution, to test the effect of traditional intracanal medicaments on anaerobic bacteria are described. The results are presented as values of minimal inhibitory and bactericidal concentrations (MIC and MBC. Standardized inocula of the anaerobic bacteria Prevotella nigrescens (ATCC 33563, Fusobacterium nucleatum (ATCC 25586 and Clostridium perfringens (ATCC 13124, in reinforced Clostridium medium (RCM and supplemented Brucella broth, were submitted to different concentrations of calcium hydroxide, chlorhexidine digluconate, camphorated paramonochlorophenol and formocresol solutions. The drugs were diluted in the same culture broths, in microplates and tubes, and were then incubated in anaerobiosis jars at 37ºC for 48 or 96 hours. The determination of MICs was carried out through visual and spectrophotometric readings, and the determination of MBCs, through the plating of aliquots on RCM-blood agar. For that kind of study, the macromethod with spectrophotometric reading should be the natural choice. MICs and MBCs obtained with the macromethod were compatible with the known clinical performance of the studied medications, and the values varied according to the bacteria and culture media employed. RCM was the most effective medium and C. perfringens, the most resistant microorganism.A determinação da suscetibilidade bacteriana aos medicamentos intracanal é uma necessidade, mas são poucos os estudos que utilizam metodologia própria para anaeróbios estritos nessa avaliação. Neste estudo, são descritos os passos de um método de diluição em caldo, feito em microplacas (microdiluição e em tubo (macrodiluição, para testar a ação de

  13. Azospirillum, a free-living nitrogen-fixing bacterium closely associated with grasses: genetic, biochemical and ecological aspects.

    Science.gov (United States)

    Steenhoudt, O; Vanderleyden, J

    2000-10-01

    nitrogen-status. NifL was found to be a redox-sensitive flavoprotein. The relief of NifL inhibition on NifA activity, in response to N-limitation, is suggested to involve a P(II)-like protein. Moreover, nitrogenase activity is regulated according to the intracellular nitrogen and O(2) level. In A. brasilense and Azospirillum lipoferum posttranslational control of nitrogenase, in response to ammonium and anaerobiosis, involves ADP-ribosylation of the nitrogenase iron protein, mediated by the enzymes DraT and DraG. At least three pathways for indole-3-acetic acid (IAA) biosynthesis in A. brasilense exist: two Trp-dependent (the indole-3-pyruvic acid and presumably the indole-3-acetamide pathway) and one Trp-independent pathway. The occurrence of an IAA biosynthetic pathway not using Trp (tryptophan) as precursor is highly unusual in bacteria. Nevertheless, the indole-3-pyruvate decarboxylase encoding ipdC gene is crucial in the overall IAA biosynthesis in Azospirillum. A number of genes essential for Trp production have been isolated in A. brasilense, including trpE(G) which codes for anthranilate synthase, the key enzyme in Trp biosynthesis. The relevance of each of these four aspects for plant growth promotion by Azospirillum is discussed.

  14. Efectividad del té verde en el tratamiento de periodontitis crónica Greentea effectiveness in chronic periodontitis treatment

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    ER Funosas

    2005-06-01

    pharmacological effects. In recent years, systematic studies performed mainly by Japanese researchers have evidenced the wide range of very useful antimicrobial properties of tea extracts. The aim of the present study was to quantitatively evaluate the clinical and microbiological efficacy of green tea in the treatment of chronic periodontitis. Fifty male and female patients who attended the Department of Periodontics, Faculty of Dentistry, National University of Rosario, Argentina, and had been diagnosed with chronic periodontitis were included in the study. The selected patients had at least 3 periodontal pockets per quadrant, depth on probing ≥ 5 mm and proximal attachment loss ≥ 2 mm. The clinical endpoints assessed were Gingival Index (Loe y Silness, 1963, Bleeding on Probing (Val del Verden, 1979, Depth on Probing with a Marquis type probe and Level of Vertical Epithelial Attachment. Samples of subgingival plaque were obtained with sterile paper cones from the bottom of the periodontal pockets to evaluate microbiological efficacy. The samples were seeded in Agar Schlaeder medium - blood enriched with 1% hemine and vitamin K in anaerobiosis at 37°C for 5 days. Typification was performed employing the commercial semi-automatic method Api 20 A Biomerieux - France. The use of green tea extract coupled to mechanical periodontal therapy for chronic periodontitis was efficient in controlling these variables. However, when it was used coupled to root scaling and planing it did not significantly improve the control of anaerobic flora as compared to scaling and planing used alone.

  15. Application of fluorescent microscopy and cascade filtration methods for analysis of soil microbial community

    Science.gov (United States)

    Ivanov, Konstantin; Pinchuk, Irina; Gorodnichev, Roman; Polyanskaya, Lubov

    2016-04-01

    by the availability of nutrients (glucose) and the degree of agricultural anthropogenic stress. Various combinations of factors such as stressful conditions (anaerobiosis, acidity and temperature) influenced on bacterial size. The decrease of these stress factors resulted in return to the original bacterial cell size in soil. Furthermore the modification of gram-negative bacteria quantification was performed and combined with FISH method and DNA extraction. We established the methodological comparison of gram-negative bacteria groups in aerobic and anaerobic conditions. Due to absence of significant difference between the most frequent soil gram-negative bacteria groups we concluded the important ecological role of gram-negative bacteria as common group of microorganisms in natural polymer degradation. Depending on nutrient (glucose, cellulose, chitin) gram-negative bacteria competed with actinomyces for available nutrients at the different time, what explained by the ecological flexibility of this soil bacteria group. The experiments showed expressed faster chitinolytic activity of soil gram-negative bacteria compare to actinomyces. Thus our approaches to use the combination both traditional and cutting-edge methods, forms the unique basement for various research and mostly open the wide doors to design new scientific experiments in ecology of terrestrial ecosystems and especially in soil microbial ecology.

  16. Viability of autogenous bone grafts obtained by using bone collectors: histological and microbiological study Viabilidade dos enxertos autógenos obtidos com a utilização de coletores para osso: estudo histológico e microbiológico

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    Alberto Blay

    2003-09-01

    Full Text Available The use of autogenous bone grafts is considered to be the best choice for reconstructive surgery. In the periodontal literature, the utilization of osseous coagulum was suggested by the end of the sixties. The purpose of this study is to consider the use of bone collectors (bone traps as an alternative method for obtaining material to fill small bone imperfections, such as fenestrations and dehiscences. Thirty samples were obtained from bone drilling during fixture installation in patients (13 men and 17 women, with an average age of 54 years requiring treatment at the Department of Periodontology and Implant Dentistry, University of Santo Amaro. These samples were fixed in 10% neutral formaldehyde for 24 hours and subjected to histological preparation, in order to evaluate the presence of viable osteoblasts. In addition, the material was placed in a fluid thioglycolate medium and incubated for 24 hours at 36 ± 1°C in aerobiosis and anaerobiosis. Bacterial growth evaluation was made by using six different culture media (MacConkey agar, blood agar base, mannitol salt agar, Anaerokit LTD medium, Anaerokit LTD - bile medium, Anaerinsol. The results show that, if proper care is taken to prevent saliva contamination during the surgical procedure, this method of collecting autogenous bone may be useful in situations where small amounts of bone are required.A utilização de enxertos autógenos é considerada a melhor opção nos tratamentos cirúrgicos de reconstrução óssea. Na literatura periodontal, a utilização de coágulo ósseo foi sugerida no final da década de 60. O objetivo deste estudo é considerar a utilização de coletores para osso como um método alternativo de se obter osso autógeno para preenchimento de defeitos ósseos como fenestrações e deiscências. Trinta amostras foram obtidas no processo de perfuração do tecido ósseo, durante a instalação de implantes em pacientes (13 homens e 17 mulheres, com média etária de

  17. ESQUEMA SIMPLIFICADO PARA IDENTIFICAÇÃO DE ESTAFILOCOCOS COAGULASE-POSITIVOS ISOLADOS DE MASTITE BOVINA SIMPLIFIED SCHEME FOR IDENTIFICATION OF COAGULASE-POSITIVE STAPHYLOCOCCI ISOLATED FROM BOVINE MASTITIS

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    Maria Aparecida Vasconcelos Paiva Brito

    2002-02-01

    Full Text Available Os testes de produção de acetoína, determinação da atividade da enzima beta-galactosidase e utilização anaeróbica do manitol em conjunto com a susceptibilidade à acriflavina foram avaliados para diferenciação de amostras de Staphylococcus coagulase-positivas (SCP isoladas de mastite bovina. As amostras foram classificadas no gênero Staphylococcus por meio da sensibilidade a furazolidona, resistência à bacitracina, produção de ácido em aerobiose a partir de glicerol na presença de 0,4mig m-1 de eritromicina e catalase, e foram positivas no teste de coagulase do plasma de coelho em tubos. A susceptibilidade à acriflavina foi testada em placas de ágar Baird Parker e ágar P com 7,0mig m-1 de acriflavina. Como controle dos testes, foram incluídas cinco amostras coagulase-negativas de S. hyicus isoladas de leite bovino e identificadas pelo sistema API Staph e a amostra de S. aureus ATCC 29213. Trinta e oito das 49 amostras de SCP foram identificadas como S. aureus e 11 como S. hyicus, não sendo identificada nenhuma como S. intermedius. O sistema API Staph foi empregado para confirmar a identificação das amostras coagulase-positivas de S. hyicus, sete amostras de S. aureus negativas no teste de produção de acetoína e quatro negativas na fermentação anaeróbica do manitol. Todas as amostras de S. aureus foram resistentes a acriflavina, enquanto as de S. hyicus foram sensíveis. Concluiu-se que a sensibilidade a acriflavina pode ser empregada juntamente com os testes de coagulase e produção de acetoína na diferenciação de SCP isolados de mastite bovina.Production of acetoin, acid production from mannitol under anaerobiosis and beta-galactosidase activity in addition to acriflavin susceptibility were evaluated to differentiate between coagulase-positive strains of Staphylococcus (CPS isolated from bovine mastitis. The strains were classified in the genus Staphylococcus by means of sensitivity to furazolidone, resistance