WorldWideScience

Sample records for anaerobiosis

  1. A new chemically defined medium for the growth and sporulation of Bacillus cereus strains in anaerobiosis

    OpenAIRE

    Abbas, Amina aïcha; Tichit-Planchon, Stella; Jobin, Michel

    2014-01-01

    A new chemically defined liquid medium, MODS, was developed for the aerobic growth and anaerobic growth and sporulation of Bacillus cereus strains. The comparison of sporulation capacity of 18 strains of B. cereus has shown effective growth and spore production in anaerobiosis.

  2. Anaerobiosis, type 1 fimbriae, and growth phase are factors that affect invasion of HEp-2 cells by Salmonella typhimurium.

    OpenAIRE

    Ernst, R K; Dombroski, D M; Merrick, J. M.

    1990-01-01

    The invasion of HEp-2 cells by Salmonella typhimurium was studied under various conditions. Anaerobiosis was shown to markedly affect the internalization of bacterial cells by HEp-2 cells. Anaerobically grown bacteria incubated with HEp-2 cells under anaerobic conditions markedly stimulated the rate of invasion. Anaerobiosis may therefore be a controlling factor in the invasion process. Cells obtained during the logarithmic phase of growth invaded at much higher rates than cells obtained duri...

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

    Directory of Open Access Journals (Sweden)

    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

  4. 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...

  5. [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

  6. Phospholipid fatty acids in mitochondria and microsomes of wheat and rice seedling roots during aeration and anaerobiosis

    International Nuclear Information System (INIS)

    Mitochondrial and microsomal fractions were isolated from the roots after residence of wheat and rice seedlings under conditions of aeration or anaerobiosis and used to determine the percentage ratio of phospholipid fatty acids (PFA), their content, and the rate of incorporation of [2-14C]-acetate into them. In rice mitochondria under anaerobic influence, the ratio of unsaturated to saturated PFA was higher than the level that occurred in the control plants and PFA content remained close to the control level throughout the entire course of exposure. On the other hand, these indices declined in wheat mitochondria and microsomes of both plants. Anoxia also powerfully inhibited incorporation of labelled acetate into PFA of both membrane fractions in wheat and rice seedlings alike. Probably indicating adaptive reorganizations in composition of the main groups of PFA and inhibition of their decomposition in rice mitochondria, the obtained data are discussed in relation to greater resistance to temporary anaerobiosis in rice as compared with wheat

  7. 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

  8. Anaerobiosis and ethanol effects on germination, growth, and protein synthesis of five Echinochloa species

    International Nuclear Information System (INIS)

    Five Echinochloa species, encompassing a spectrum from flood tolerant to flood intolerant, were studied to determine the mechanisms of anaerobic germination and growth. Seeds were germinated in air or N2, plus 0, 1 or 3% ethanol, and germination rates and growth measurements recorded for 7 days. In air or N2 increasing ethanol levels did not affect total germination per se, although the rate of germination was delayed in N2. Shoot/root lengths in air were highest for tolerant species and increased with increasing ethanol, whereas, in intolerant species, shoot/root lengths decreased with increasing ethanol. Aerobic vs. anaerobic polypeptide profiles of each of the species were compared by SDS/PAGE. For all species, the number of polypeptides decreased under anaerobiosis and several quantitative differences were apparent relative to the aerobic profile. In addition, amino acid incorporation into protein was analyzed by [35S]-Met labeling of 3 day old seedlings grown in air or N2. Significant protein synthesis was measured in tolerant seedlings under N2 and several polypeptides were specifically induced. These results are being compared with labeling patterns of the other semi-tolerant and intolerant Echinochloa species to determine their importance in flooding tolerance

  9. Dynamic Aspects of Alcoholic Fermentation of Rice Seedlings in Response to Anaerobiosis and to Complete Submergence: Relationship to Submergence Tolerance

    OpenAIRE

    BOAMFA, E. I.; RAM, P. C.; Jackson, M B; Reuss, J.; Harren, F.J.M.

    2003-01-01

    Rice plants are severely damaged by complete submergence. This is a problem in rice farming and could be the result, in part, of tissue anoxia imposed by a reduced availability of oxygen. To investigate this possibility we monitored alcoholic fermentation products as markers for tissue anaerobiosis using sensitive laser‐based spectroscopy able to sense ethanol and acetaldehyde down to 3 nl l–1 and 0·1 nl l–1, respectively. Acetaldehyde emission began within 0·5 h of imposing an oxygen‐free ga...

  10. 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.

  11. 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.

  12. 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

  13. 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...

  14. 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; Schmidt, Jens Ejbye; Villumsen, Arne; Jenssen, Petter Deinboll

    2014-01-01

    . Amoxicillin resistant bacteria were reduced in the anaerobic samples in the beginning of the study but increased towards the end of it. The opposite pattern was observed in the aerobic samples, with a growth in the beginning followed by a reduction. During the anaerobic digestion tetracycline resistant...

  15. 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

  16. Impact of Anaerobiosis on Expression of the Iron-Responsive Fur and RyhB Regulons

    OpenAIRE

    Beauchene, Nicole A.; Kevin S Myers; Chung, Dongjun; Park, Dan M.; Weisnicht, Allison M.; Keleş, Sündüz; Kiley, Patricia J.

    2015-01-01

    ABSTRACT Iron, a major protein cofactor, is essential for most organisms. Despite the well-known effects of O2 on the oxidation state and solubility of iron, the impact of O2 on cellular iron homeostasis is not well understood. Here we report that in Escherichia coli K-12, the lack of O2 dramatically changes expression of genes controlled by the global regulators of iron homeostasis, the transcription factor Fur and the small RNA RyhB. Using chromatin immunoprecipitation sequencing (ChIP-seq)...

  17. Effect of anaerobiosis on the geochemical cycling of plutonium in PAR Pond

    International Nuclear Information System (INIS)

    Most of the fallout plutonium in Lake Michigan sediments is found associated with hydrous oxides which are significantly solubilized only under reducing conditions. As most of the sediments of Lake Michigan remain aerobic all year long, the possibility of resolubilization of these oxides and reintroduction of the associated plutonium into the overlying water through this mechanism is small. However, in some water bodies, such as PAR Pond, South Carolina, anaerobic sedimentary conditions do prevail for a portion of the year. PAR Pond was studied to determine if the seasonal anaerobic conditions in the sediments lead to a measurable increase in the plutonium concentration of the overlying water. The data indicated that there was a slight increase in the 239240Pu concentration near the bottom as compared to the rest of the water column in the July 1975 and August 1976 samples. However, no significant increase in 239240Pu concentration was observed in the hypolimnetic waters of the pond which could be related to the anaerobic conditions of the sediment and deep waters during the summer months

  18. 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

  19. ATP Production by Respiration and Fermentation, and Energy Charge during Aerobiosis and Anaerobiosis in Twelve Fatty and Starchy Germinating Seeds.

    Science.gov (United States)

    Raymond, P; Al-Ani, A; Pradet, A

    1985-11-01

    The respiration and fermentation rates were compared in germinating seeds of 12 different cultivated species from five families. In air, fermentation contributes significantly to the energy metabolism only in some species (pea, maize), but is generally negligible when compared to respiration. The fermentation rate under anoxia was related either to the metabolic activity under air or to the adenine nucleotide content of the seeds: it was generally higher in seeds which contain starchy reserves (rice, maize, sorghum, pea), than in seeds which do not contain starch (lettuce, sunflower, radish, turnip, cabbage, flax); however, it was similar in wheat, sorghum (starchy seeds), and soya (nonstarchy seeds). The value of the energy charge of all the seeds was lower under anoxia than in air: after 24 hours under anoxia, it was higher than 0.5 in the starchy seeds and in soya and it was around 0.25 in the other fatty seeds. PMID:16664509

  20. Plant anaerobic stress II. Strategy of avoidance of anaerobiosis and other aspects of plant life under hypoxia and anoxia

    Science.gov (United States)

    This article is a logical follow-up of previous publications (Vartapetian and Crawford 2007; Sachs and Vartapetian 2007) where an attempt was made to summarize the results of earlier periods of investigations of plant anaerobic stress and the activity of members of the International Society for Plan...

  1. Synergy between 13C-metabolic flux analysis and flux balance analysis for understanding metabolic adaption to anaerobiosis in e. coli

    Science.gov (United States)

    Genome-based Flux Balance Analysis (FBA, constraints based flux analysis) and steady state isotopic-labeling-based Metabolic Flux Analysis (MFA) are complimentary approaches to predicting and measuring the operation and regulation of metabolic networks. Here a genome-derived model of E. coli metabol...

  2. 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

  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. 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...

  5. 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...

  6. Differences in cold adaptation of .i.Bacillus subtilis./i. under anaerobic and aerobic conditions

    Czech Academy of Sciences Publication Activity Database

    Beranová, J.; Mansilla, M.C.; de Mendoza, D.; Elhottová, Dana; Konopásek, I.

    2010-01-01

    Roč. 192, č. 16 (2010), s. 4164-4171. ISSN 0021-9193 R&D Projects: GA MŠk LC06066 Institutional research plan: CEZ:AV0Z60660521 Keywords : cold adaptation * Bacillus subtilis * anaerobiosis Subject RIV: EE - Microbiology, Virology Impact factor: 3.726, year: 2010

  7. Reference: ANAEROBICCISZMGAPC4 [PLACE

    Lifescience Database Archive (English)

    Full Text Available rs with cis-regulatory sequences in the maize GapC4 promoter Plant Mol Biol 43: 11-21 (2000) PubMed: 10949370; ... ...ANAEROBICCISZMGAPC4 Geffers R, Cerff R, Hehl R Anaerobiosis-specific interaction of tobacco nuclear facto

  8. Reference: GCBP2ZMGAPC4 [PLACE

    Lifescience Database Archive (English)

    Full Text Available rs with cis-regulatory sequences in the maize GapC4 promoter Plant Mol Biol 43: 11-21 (2000) PubMed: 10949370; ... ...GCBP2ZMGAPC4 Geffers R, Cerff R, Hehl R Anaerobiosis-specific interaction of tobacco nuclear facto

  9. 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

    OpenAIRE

    Elerson Gaetti Jardim Júnior; Joseane Maria Dias Bosco; Angélica Marquezim Lopes; Luís Fernando Landucci; Ellen Cristina Gaetti Jardim; Sílvia Rosana Soares Carneiro

    2006-01-01

    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, ...

  10. 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...

  11. Multiple controls exerted on in vivo expression of the pepN gene in Escherichia coli: studies with pepN-lacZ operon and protein fusion strains.

    OpenAIRE

    Gharbi, S.; Belaich, A; Murgier, M; Lazdunski, A

    1985-01-01

    Three physiological conditions were shown to promote transcriptional regulation of pepN expression: phosphate limitation, the nature of the source of carbon and energy, and anaerobiosis. The transcriptional level of regulation can be deduced from the observation of these effects in strains carrying operon fusion pepN-lacZ. Mutations in the various genes phoB, phoM, phoR, crp, and fnr (oxrA) did not affect pepN expression.

  12. 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.

  13. 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)

  14. 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...

  15. Nitrate reductase regulation in tomato roots by exogenous nitrate: a possible role in tolerance to long-term root anoxia

    OpenAIRE

    Allègre, Adeline; Silvestre, Jérôme; Morard, Philippe; Kallerhoff, Jean; Pinelli, Eric

    2004-01-01

    The mechanism of nitrate reductase (NR) regulation under long-term anoxia in roots of whole plants and the putative role of nitrate in anoxia tolerance have been addressed. NR activity in tomato roots increased significantly after 24 h of anaerobiosis and increased further by 48 h, with a concomitant release of nitrite into the culture medium. Anoxia promoted NR activation through dissociation of the 14-3-3 protein inhibitor and NR dephosphorylation. After 24 h of anoxia, the total amount of ...

  16. 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...

  17. 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.

  18. 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...

  19. 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...

  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

    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]. ...

  1. 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...

  2. 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

  3. 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.

  4. Synthetic lac Operator Substitutions for Studying the Nitrate- and Nitrite-Responsive NarX-NarL and NarQ-NarP Two-Component Regulatory Systems of Escherichia coli K-12

    OpenAIRE

    Stewart, Valley; Bledsoe, Peggy J.

    2003-01-01

    The NarX and NarQ sensor-histidine kinases control phosphorylation of the NarL and NarP response regulators in response to the respiratory oxidants nitrate and nitrite. Target operon transcription is activated by the Fnr protein in response to anaerobiosis, and it is further activated and/or repressed by the phospho-NarL and phospho-NarP proteins, which bind to heptamer DNA sequences. The location and arrangement of heptamers vary widely among different target operon control regions. We have ...

  5. 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...

  6. 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.; Coutelis, J.B.; Pynyaha, J.; Neuveglise, C.; Møller, Kasper; Loffler, M.; Piskur, Jure

    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...... the phylogenetic point of view, this enzyme is closely related to a bacterial DHODase from Lactococcus lactis. Here we show that S. kluyveri, which separated from the S. cerevisiae lineage more than 100 million years ago, represents an evolutionary intermediate, having both cytoplasmic and...... acquired a bacterial gene for DHODase, which subsequently allowed cell growth gradually to become independent of oxygen....

  7. Dimorphic transition in Yarrowia lipolytica isolated from oil-polluted sea water

    International Nuclear Information System (INIS)

    Fungal cultures from oil-polluted sea water near Mumbai, India have been studies for their capability to degrade crude oil. A yeast isolate identified as Yarrowia lipolytica was further investigated with respect to its dimorphic behaviour and alkane degradation. Y. lipolytica NCIM 3589 in the yeast form degraded the aliphatic fraction of crude oil and also pure alkanes (20-60% within 48h) under aerobic conditions. Unlike most Y. lipolytica strains, our isolate required partial anaerobiosis for mycelium formation. Studies with two isolates suggested that mycelium to yeast transition may be the prerequisite for effective alkane degradation. (author)

  8. Dimorphic transition in Yarrowia lipolytica isolated from oil-polluted sea water

    Energy Technology Data Exchange (ETDEWEB)

    Zinjarde, Smita S.; Pant, Aditi; Deshpande, Mukund V. [National Chemical Lab., Biochemical Sciences Div., Pune (India)

    1998-09-01

    Fungal cultures from oil-polluted sea water near Mumbai, India have been studies for their capability to degrade crude oil. A yeast isolate identified as Yarrowia lipolytica was further investigated with respect to its dimorphic behaviour and alkane degradation. Y. lipolytica NCIM 3589 in the yeast form degraded the aliphatic fraction of crude oil and also pure alkanes (20-60% within 48h) under aerobic conditions. Unlike most Y. lipolytica strains, our isolate required partial anaerobiosis for mycelium formation. Studies with two isolates suggested that mycelium to yeast transition may be the prerequisite for effective alkane degradation. (author)

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli

    International Nuclear Information System (INIS)

    Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 J/m2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O2-radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn2+ and Fe2+, inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N2 for 90 min, the respiration, growth, and viability time-course responses were the same as for cells not exposed to anaerobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation of respiration and cell death and that inadequate aeration or anaerobiosis delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration

  15. 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.

  16. Antimicrobial capacity of Aloe vera and propolis dentifrice against Streptococcus mutans strains in toothbrushes: an in vitro study

    Directory of Open Access Journals (Sweden)

    Patrícia Fernanda Roesler Bertolini

    2012-02-01

    Full Text Available OBJECTIVES: This study evaluated in vitro the efficiency of Aloe vera and propolis dentifrice on reducing the contamination of toothbrush bristles by a standard strain of Streptococcus mutans (ATCC 25175; SM, after toothbrushing. MATERIAL AND METHODS: Fifteen sterile toothbrushes were randomly divided into 5 toothbrushing groups: I (negative control: without dentifrice; II: with fluoridated dentifrice; III: with triclosan and gantrez dentifrice; IV (positive control: without dentifrice and irrigation with 10 mL of 0.12% chlorhexidine gluconate; V: with Aloe vera and propolis dentifrice. In each group, 1 sterile bovine tooth was brushed for 1 min, where the toothbrush bristles were contaminated with 25 µL of SM. After toothbrushing, the bristles were stored in individual test tubes with 3 mL of BHI under anaerobiosis of 37°C for 48 h. Then, they were seeded with sterile swab in triplicate in the Mitis salivarius - Bacitracin culture medium. The samples were kept under anaerobiosis of 37°C for 48 h. Scores were used to count the number of colony forming units (cfu. The results were submitted to the Mann-Whitney statistical test at 5% significance level. RESULTS: There was statistically significant difference (p<0.05 for the reduction of bristle contamination comparing groups II, III, IV and V to group I. CONCLUSIONS: It may be stated that after toothbrushing, the Aloe vera and propolis dentifrice reduced the contamination of toothbrush bristles by SM, without differentiation from the other chemical agents used.

  17. 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.

  18. 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.

  19. 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

  20. Adequacy of Petrifilm™ Aerobic Count plates supplemented with de Man, Rogosa & Sharpe broth and chlorophenol red for enumeration of lactic acid bacteria in salami.

    Science.gov (United States)

    de Castilho, Natália Parma Augusto; Okamura, Vivian Tiemi; Camargo, Anderson Carlos; Pieri, Fábio Alessandro; Nero, Luís Augusto

    2015-12-01

    The present study aimed to assess the performance of alternative protocols to enumerate lactic acid bacteria (LAB) in salami. Fourteen cultures and two mixed starter cultures were plated using six protocols: 1) Petrifilm™ Aerobic Count (AC) with MRS broth and chlorophenol red (CR), incubated under aerobiosis or 2) under anaerobiosis, 3) MRS agar with CR, 4) MRS agar with bromocresol purple, 5) MRS agar at pH5.7, and 6) All Purpose Tween agar. Samples of salami were obtained and the LAB microbiota was enumerated by plating according protocols 1, 2, 3 and 5. Regression analysis showed a significant correlation between the tested protocols, based on culture counts (p0.05). Colonies were confirmed as LAB, indicating proper selectivity of the protocols. The results showed the adequacy of Petrifilm™ AC supplemented with CR for the enumeration of LAB in salami. PMID:26291606

  1. 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

  2. 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.

  3. 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

    developed an auxotrophic transformation system and an expression vector, which enabled the manipulation of D. bruxellensis, thereby improving its fermentative performance. Its gene ADH3, coding for alcohol dehydrogenase, was cloned and overexpressed under the control of the strong and constitutive promoter...... TEF1. Our recombinant D. bruxellensis strain displayed 1.4 and 1.7 times faster specific glucose consumption rate during aerobic and anaerobic glucose fermentations, respectively; it yielded 1.2 times and 1.5 times more ethanol than did the parental strain under aerobic and anaerobic conditions......, 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....

  4. 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).

  5. 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 blood flow but also appears to limit anaerobiosis and H(+) release, presumably through a preferential recruitment of oxidative fibers.

  6. 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)

  7. Long-term anoxia and release of ancient, labile carbon upon thaw of Pleistocene permafrost

    Science.gov (United States)

    Ewing, Stephanie A.; O'Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna; Butman, David; Windham-Myers, Lisamarie; Kanevskiy, Mikhail Z.

    2015-12-01

    The fate of permafrost carbon upon thaw will drive feedbacks to climate warming. Here we consider the character and context of dissolved organic carbon (DOC) in yedoma permafrost cores from up to 20 m depth in central Alaska. We observed high DOC concentrations (4 to 129 mM) and consistent low molecular weight organic acid concentrations in three cores. We estimate a DOC production rate of 12 µmol DOC m-2 yr-1 based on model ages of up to ~200 kyr derived from uranium isotopes. Acetate C accounted for 24 ± 1% of DOC in all samples. This proportion suggests long-term anaerobiosis and is likely to influence thaw outcomes due to biolability of acetate upon release in many environments. The combination of uranium isotopes, ammonium concentrations, and calcium concentrations explained 86% of the variation in thaw water DOC concentrations, suggesting that DOC production may be related to both reducing conditions and mineral dissolution over time.

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

    DEFF Research Database (Denmark)

    Møller, Kasper; Langkjær, Rikke Breinhold; Nielsen, Jens; Piskur, Jure; Olsson, Lisbeth

    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...... with respect to ethanol formation under aerobic conditions could be caused by differences in the regulation of this enzyme activity. We have identified and cloned three genes encoding functional pyruvate decarboxylase enzymes ( PDC genes) from the type strain of S. kluyveri (Sk-PDC11, Sk-PDC12 and Sk...... activity 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...

  9. 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

  10. 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.

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

    Science.gov (United States)

    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.

  12. 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

  13. 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.

  14. 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

  15. Changes in growth, rRNA content, and cell morphology of Listeria monocytogenes induced by CO2 up- and downshift

    DEFF Research Database (Denmark)

    Jydegaard-Axelsen, A.M.; Aaes-Jorgensen, A.; Koch, A.G.; Stoumann Jensen, J.; Knochel, S.

    2005-01-01

    Cell morphology, rRNA content, and growth were examined for Listeria monocytogenes LO28 and EGD, respectively, grown in brain-heart infusion (BHI) and on slices of sausage at 10degreesC in 100% CO2, 100% N-2, and air. In CO2, filamentous cells were formed by both strains on sausage slices and by L....... monocytogenes EGD in BHI. Filamentation was not induced by anaerobiosis only. Fluorescent in situ rRNA hybridization (FISH) of cells grown in BHI showed that the L. monocytogenes EGD filaments consisted of chains of individual slightly elongated cells. The rods formed by L. monocytogenes LO28 had the same size...... in air and CO2.. Septation and cell division were induced in the filaments after a CO2 downshift (i.e., exposure to air). In BHI, the number of colony forming units increased rapidly when L. monocytogenes EGD grown in CO2 was exposed to air whereas the number of L. monocytogenes LO28 remained almost...

  16. 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

  17. Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile.

    Science.gov (United States)

    Lara, José; Escudero González, Lorena; Ferrero, Marcela; Chong Díaz, Guillermo; Pedrós-Alió, Carlos; Demergasso, Cecilia

    2012-05-01

    Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H(2), H(2)S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels. PMID:22555750

  18. 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.

  19. 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.

  20. 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

  1. 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.

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

    Science.gov (United States)

    Júnior, Fábio Lino Soares; 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

  3. 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

  4. 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

  5. Microbiota associated with chronic osteomyelitis of the jaws

    Science.gov (United States)

    Gaetti-Jardim Júnior, Elerson; Fardin, Angélica Cristiane; Gaetti-Jardim, Ellen Cristina; de Castro, Alvimar Lima; Schweitzer, Christiane Marie; Avila-Campos, Mario Julio

    2010-01-01

    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. PMID:24031586

  6. 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 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Ecology and ecophysiology of tree stems: corticular and wood photosynthesis

    Science.gov (United States)

    Pfanz, H.; Aschan, G.; Langenfeld-Heyser, R.; Wittmann, C.; Loose, M.

    2002-03-01

    Below the outer peridermal or rhytidomal layers, most stems of woody plants possess greenish tissues. These chlorophyll-containing tissues (the chlorenchymes) within the stems are able to use the stem internal CO2 and the light penetrating the rhytidome to photoassimilate and produce sugars and starch. Although net photosynthetic uptake of CO2 is rarely found, stem internal re-fixation of CO2 in young twigs and branches may compensate for 60-90% of the potential respiratory carbon loss. Isolated chlorenchymal tissues reveal rather high rates of net photosynthesis (being up to 75% of the respective rates for leaf photosynthesis). Corticular photosynthesis is thus thought to be an effective mechanism for recapturing respiratory carbon dioxide before it diffuses out of the stem. Furthermore, chloroplasts of the proper wood or pith fraction also take part in stem internal photosynthesis. Although there has been no strong experimental evidence until now, we suggest that the oxygen evolved during wood or pith photosynthesis may play a decisive role in avoiding/reducing stem internal anaerobiosis.

  13. 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

  14. 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

  15. 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 forest (P 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

  16. 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

  17. 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.

  18. 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)

  19. 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

  20. 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

  1. 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.

  2. Physiological effects of the form of nitrogen on corn root tips: a 31P nuclear magnetic resonance study

    International Nuclear Information System (INIS)

    Physiological effects of different N forms (NO−3, NH+4, or a combination of both) on corn (Zea mays L.) root tips and leaves were studied by following 31P signals with a nuclear magnetic resonance spectrometer. With root tips, both cytoplasmic and vacuolar pH could be measured, whereas with leaves, only vacuolar pH could be determined. The N treatments did not affect the cytoplasmic pH of corn root tips in contrast to proposals of previous workers. Leaf vacuolar pH was higher and root tip vacuolar pH lower with NO−3 than with NH+4. Under anaerobic conditions, cytoplasmic pH was reduced because of lactic acid fermentation. Nitrate, an electron acceptor, delayed the acidification of the cytoplasm compartment because it represents an alternative way to reoxidize NADH. In conclusion, for the conditions of these experiments, the pH of the cytoplasm of corn root tips was not modified by the form of N absorbed; however, the pH of this compartment was affected by the form of N presented during development anaerobiosi. (author)

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

    Science.gov (United States)

    Schifferdecker, Anna Judith; Siurkus, Juozas; Andersen, Mikael Rørdam; Joerck-Ramberg, Dorte; Ling, Zhihao; Zhou, Nerve; Blevins, James E; Sibirny, Andriy A; Piškur, Jure; Ishchuk, Olena P

    2016-04-01

    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 developed an auxotrophic transformation system and an expression vector, which enabled the manipulation of D. bruxellensis, thereby improving its fermentative performance. Its gene ADH3, coding for alcohol dehydrogenase, was cloned and overexpressed under the control of the strong and constitutive promoter TEF1. Our recombinant D. bruxellensis strain displayed 1.4 and 1.7 times faster specific glucose consumption rate during aerobic and anaerobic glucose fermentations, respectively; it yielded 1.2 times and 1.5 times more ethanol than did the parental strain under aerobic and anaerobic conditions, 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. PMID:26743658

  4. Development of microorganisms in the chernozem under aerobic and anaerobic conditions

    Science.gov (United States)

    Polyanskaya, L. M.; Gorbacheva, M. A.; Milanovskii, E. Yu.; Zvyagintsev, D. G.

    2010-03-01

    A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in different horizons of a chernozem. It was revealed that, under aerobic conditions, all the microorganisms grow irrespective of the soil horizon; fungi and bacteria grow at the first succession stages, and actinomycetes grow at the last stages. It was shown that, in the case of a simulated anaerobiosis commonly used to study anaerobic populations of bacteria, the mycelium of micromycetes grows in the upper part of the chernozem’s A horizon. Under anaerobic conditions, the peak of the mycelium development is shifted from the 3rd to 7th days (typical for aerobic conditions) to the 7th to 15th days of incubation. The level of mycelium length’s stabilization under aerobic and anaerobic conditions also differs: it is higher or lower than the initial one, respectively. Under anaerobic conditions, the growth of fungal mycelium, bacteria, and actinomycetes in the lower part of the A horizon and in the B horizon is extremely weak. There was not any observed growth of actinomycetes in all the chernozem’s horizons under anaerobic conditions.

  5. Evaluation of americium-241 toxicity influence on the microbial growth of organic wastes

    International Nuclear Information System (INIS)

    Available in abstract form only. Full text of publication follows: Since the licenses for using radioactive sources in radioactive lightning rods were lifted by the Brazilian national nuclear authority, in 1989, the radioactive devices have been replaced by Franklin type and collected as radioactive waste. However, only 20 percent of the estimated total number of installed rods was delivered to Brazilian Nuclear Commission. This situation causes concern, due to, first, the possibility of the rods being disposed as domestic waste, and second, the americium, the most commonly employed radionuclide, is classified as a high-toxicity element. In the present study, Am-241 migration experiments were performed by a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as a common solid waste. Besides the risk evaluation, it is important to know the mechanism of the Am-241 release or retention in waste as well as its influence in the waste decomposition processes. Many factors are involved, but microorganisms present in the waste play an important role in its degradation, which control the physical and chemical processes. The objective of this work was to evaluate the Am-241 influence on the microbial population by counting number of cells in lysimeters leachate. Preliminary results suggest that americium may influence significantly the bacteria growth in organic waste, evidenced by culture under aerobiosis and an-aerobiosis and the antimicrobial resistance test. (authors)

  6. Distinct physiological roles for the two L-asparaginase isozymes of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Srikhanta, Yogitha N. [Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010 (Australia); Atack, John M.; Beacham, Ifor R. [Institute for Glycomics, Griffith University, Gold Coast, QLD 4222 (Australia); Jennings, Michael P., E-mail: m.jennings@griffith.edu.au [Institute for Glycomics, Griffith University, Gold Coast, QLD 4222 (Australia)

    2013-07-05

    Highlights: •Escherichia coli contains two L-asparaginase isozymes with distinct localization, kinetics and regulation. •Mutant strains were used to examine the roles of these enzymes in L-asparagine utilization. •We report that L-asparaginase II permits growth on asparagine and glycerol under anaerobic conditions. •We propose that this enzyme is the first step in a co-regulated pathway leading to fumarate. •The pathway is regulated by anaerobiosis and cAMP and provides a terminal elector acceptor. -- Abstract: Escherichia coli expresses two L-asparaginase (EC 3.5.1.1) isozymes: L-asparaginse I, which is a low affinity, cytoplasmic enzyme that is expressed constitutively, and L-asparaginase II, a high affinity periplasmic enzyme that is under complex co-transcriptional regulation by both Fnr and Crp. The distinct localisation and regulation of these enzymes suggest different roles. To define these roles, a set of isogenic mutants was constructed that lacked either or both enzymes. Evidence is provided that L-asparaginase II, in contrast to L-asparaginase I, can be used in the provision of an anaerobic electron acceptor when using a non-fermentable carbon source in the presence of excess nitrogen.

  7. Distinct physiological roles for the two L-asparaginase isozymes of Escherichia coli

    International Nuclear Information System (INIS)

    Highlights: •Escherichia coli contains two L-asparaginase isozymes with distinct localization, kinetics and regulation. •Mutant strains were used to examine the roles of these enzymes in L-asparagine utilization. •We report that L-asparaginase II permits growth on asparagine and glycerol under anaerobic conditions. •We propose that this enzyme is the first step in a co-regulated pathway leading to fumarate. •The pathway is regulated by anaerobiosis and cAMP and provides a terminal elector acceptor. -- Abstract: Escherichia coli expresses two L-asparaginase (EC 3.5.1.1) isozymes: L-asparaginse I, which is a low affinity, cytoplasmic enzyme that is expressed constitutively, and L-asparaginase II, a high affinity periplasmic enzyme that is under complex co-transcriptional regulation by both Fnr and Crp. The distinct localisation and regulation of these enzymes suggest different roles. To define these roles, a set of isogenic mutants was constructed that lacked either or both enzymes. Evidence is provided that L-asparaginase II, in contrast to L-asparaginase I, can be used in the provision of an anaerobic electron acceptor when using a non-fermentable carbon source in the presence of excess nitrogen

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. The induction of proteinases in corn and soybean by anoxia

    International Nuclear Information System (INIS)

    This study characterized the anaerobic changes in proteinase activities in corn and soybean roots and to investigate the possibility that these changes might contribute to the differential anaerobiosis tolerance of the two species. After 24 h of anoxia, crude protein extracts from H60 corn and Keller soybean root tips (10cm) were assayed for proteinase activities at pH range from 4.5 to 9.5. Turnover of aberrant proteins was studied in seedlings labelled with 3H-leucine for 12 h under: (a) puromycin (0.64 mM) in air, (b) ethanol (1%) in air, (c) nitrogen and (d) air. After the treatment, the labelled proteins remaining in roots were determined every 2 h for 6 h. In both corn and soybean, activities of alkali proteinases increased, and activities of acid proteinases declined under anoxia. Neutral proteinases increase in anoxic corn roots, but decline in anoxic soybean roots. The protein turnover rate in corn treated with puromycin, ethanol and nitrogen was much higher than in control roots. The protein turnover rate in soybean roots treated with puromycin, ethanol was similar to the rate of the control. The results indicated that: (a) anoxic corn can degrade aberrant proteins, but anoxic soybean cannot, (b) the degradation of aberrant proteins in anoxic corn is accomplished by neutral proteinases, and (c) the accumulation of aberrant proteins in soybean might contribute to the susceptibility of this species to anoxia

  15. Spontaneous mutability and light-induced mutagenesis in Salmonella typhimurium: effects of an R-plasmid

    International Nuclear Information System (INIS)

    The UV-protecting plasmid R46 was transferred by conjugation to a genetically marked mouse-virulent Salmonella typhimurium strain, not derived from LT2; in this host the plasmid conferred UV protection and enhanced UV mutagenesis just as it does in LT2 lines. Tra-derivatives of R46 encountered during transduction retained UV-protecting and mutagenesis-enhancing ability. Stored strains carrying the R46-derived plasmids with strong mutator effect but not UV-protecting had lost most of their original streptomycin resistance but were slightly resistant to spectinomycin; attempts to transfer such plasmids failed. R46 enhanced the weak mutagenic effect of visible light on several his and trp mutants of strain LT2, including some whose frequency of spontaneous reversion was not increased by the plasmid. A mutagenic effect was produced by visible-light irradiation of hisG46(R46), either growing cells or nonmultiplying (histidine-deprived cells at 100C). Presence of catalase or cyanide during irradiation did not prevent mutagenesis, which excludes some hypothetical mechanisms. Visible-light irradiation of hisG46 or hisG46(R46) under strict anaerobiosis had little or no mutagenic effect (controls showed that revertants if produced would have been detected). This is as expected if visible-light irradiation in air causes photodynamic damage to DNA and mutations are produced during error-prone, plasmid-enhanced repair

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

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    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.

  17. Enrichment of anammox from activated sludge and its application in the CANON process.

    Science.gov (United States)

    Third, K A; Paxman, J; Schmid, M; Strous, M; Jetten, M S M; Cord-Ruwisch, R

    2005-02-01

    A microbial culture capable of actively oxidizing ammonium to dinitrogen gas in the absence of oxygen, using nitrite as the electron acceptor, was enriched from local activated sludge (Western Australia) in activity achieved by the anaerobic culture was 0.26 mmol NH (4) (+) (g biomass)(-1) h(-1) (0.58 kg total-N m(-3) day(-1)). Qualitative FISH analysis (fluorescence in situ hybridization) confirmed the phylogenetic position of the enriched microorganism as belonging to the order Planctomycetales, in which all currently identified anammox strains fall. Preliminary FISH analysis suggests the anammox strain belongs to the same phylogenetic group as the Candidatus 'Brocadia anammoxidans' strain discovered in the Netherlands. However, there are quite a few differences in the target sites for the more specific probes of these organisms and it is therefore likely to represent a new species of anammox bacteria. A small amount of aerobic ammonium-oxidizing biomass was inoculated into the anammox reactor (10% v/v) to initiate completely autotrophic nitrogen removal over nitrite (the CANON process) in chemostat culture. The culture was always under oxygen limitation and no organic carbon was added. The CANON reactor was operated as an intermittently aerated system with 20 min aerobiosis and 30 min anaerobiosis, during which aerobic and anaerobic ammonium oxidation were performed in sequential fashion, respectively. Anammox was not inhibited by repeated intermittent exposure to oxygen, allowing sustained, completely autotrophic ammonium removal (0.08 kg N m(-3) day(-1)) for an extended period of time. PMID:15735941

  18. Treatment of nitrogen-rich wastewater using partial nitrification and anammox in the CANON process.

    Science.gov (United States)

    Third, K A; Paxman, J; Schmid, M; Strous, M; Jetten, M S M; Cord-Ruwisch, R

    2005-01-01

    Partial nitrification combined with Anammox in a single reactor (the CANON process) is an energy-efficient N-removal technology that could substantially lower the N-load of a WWTP by separate treatment of nitrogen-rich side streams, preventing the need for extensive expansion and reducing the total energy requirement. This study looks at the enrichment of Anammox from activated sludge and its application in the CANON process on lab-scale. The aim was to identify the critical process control parameters necessary for successful operation of CANON. An Anammox culture capable of removing 0.6 kg N/m3/d was enriched in 14 weeks in a sequencing batch reactor. Nitrifying biomass was inoculated into the Anammox reactor (10% v/v) together with limited oxygen supply (culture. The small flocs formed by the biomass (< 1000 microm) were sensitive to low O2 concentrations (< 0.1 mg/L) which prevented simultaneous nitrification and Anammox. Operation with 20 min aerobiosis and 30 min anaerobiosis was necessary to achieve sustained, completely autotrophic N-removal for an extended period at a rate of 0.08 kg N/m3/d. Essential process control parameters for stable CANON operation were the nitrite concentration, oxygen concentration, pH and the temperature. PMID:16235745

  19. 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.

  20. In vitro effect of intracanal medicaments on strict anaerobes by means of the broth dilution method

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    ROSA Odila Pereira da Silva

    2002-01-01

    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.

  1. 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

  2. Gingival Condition in Children Aged From 6 to 12 Years Old: Clinical and Microbiological Aspects

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    Ane Stella Salgado XAVIER

    2007-03-01

    Full Text Available Objective: The aim of this study was to evaluate the gingival condition and the occurrence of periodontopathogens in 93 children aged from 6 to 12 years old in Araçatuba, Brazil. Method: Clinical examination was performed in accordance to Schour and Massler (1947 while the subgingival plaque samples were obtained though sterilized paper point that were placed into health and inflamed gingival crevice of tooth 54 or 14, 61 or 11, 26, 75 or 35, 82 or 42 and 46, where they were kept for 60 seconds and tranferred to tubes containing 5 ml of thioglicolate broth. Microorganisms were isolated on blood agar and CVE an agar after incubation under anaerobiosis, at 37ºC, for 10 days. The identification of the isolates was based on their morphological, cellular and biochemical features. Results: 91.40% shows gingivitis while 70.97% presented mild gingivitis. Only 8.6% didn’t presented gingivitis. It was verified that the most of children presented mild gengivitis and was had some periodontopathogens. Conclusion: The gingivitis deteriored with age and only F. nucleatum was related with the deterioration of gengival status.

  3. 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

  4. 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.

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

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    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.

  6. [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)

  7. 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

  8. 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

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    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

  9. 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

  10. 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

  11. 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

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    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

  12. 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. PMID:26986852

  13. 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.

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

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    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.

  15. 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. PMID:11238402

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

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    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.

  17. 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

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

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    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.

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

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    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. 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

  1. 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

  2. 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

  3. Regulation of the ansB gene of Salmonella enterica.

    Science.gov (United States)

    Jennings, M P; Scott, S P; Beacham, I R

    1993-07-01

    The expression of L-asparaginase II (encoded by ansB) in Salmonella enterica was found to be positively regulated by the cAMP receptor protein (CRP) and anaerobiosis. The anaerobic regulation of the S. enterica ansB gene is not mediated by the anaerobic transcriptional activator FNR. This is unlike the situation of the ansB gene of Escherichia coli, which is dependent on both CRP and FNR. To investigate this fundamental difference in the regulation of L-asparaginase II expression in S. enterica, the ansB gene was cloned and the nucleotide sequence of the promoter region determined. Sequence analysis and transcript mapping of the 5' promoter region revealed a single transcriptional start point (tsp) and two regulatory sites with substantial homology with those found in E. coli. One site, centred -90.5 bp from the tsp, is homologous to a hybrid CRP/FNR ('CF') site which is the site of CRP regulation in the E. coli promoter. The other site, centred 40.5 bp upstream of the tsp, is homologous to the FNR binding site of the E. coli promoter. Significantly, however, a single base-pair difference exists in this site, at a position of the related CRP and FNR DNA-binding site consensus sequences known to be involved in CRP versus FNR specificity. Site-directed mutagenesis indicates that this single difference, relative to the homologous E. coli site, results in a CRP binding site and the observed FNR-independent ansB expression in S. enterica.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8412661

  4. 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.

  5. The Influence of Organic Material and Temperature on the Burial Tolerance of the Blue Mussel, Mytilus edulis: Considerations for the Management of Marine Aggregate Dredging

    Science.gov (United States)

    Cottrell, Richard S.; Black, Kenny D.; Hutchison, Zoë L.; Last, Kim S.

    2016-01-01

    Rationale and Experimental Approach Aggregate dredging is a growing source of anthropogenic disturbance in coastal UK waters and has the potential to impact marine systems through the smothering of benthic fauna with organically loaded screening discards. This study investigates the tolerance of the blue mussel, Mytilus edulis to such episodic smothering events using a multi-factorial design, including organic matter concentration, temperature, sediment fraction size and duration of burial as important predictor variables. Results and Discussion Mussel mortality was significantly higher in organically loaded burials when compared to control sediments after just 2 days. Particularly, M. edulis specimens under burial in fine sediment with high (1%) concentrations of organic matter experienced a significantly higher mortality rate (ptreatment (20°C) exhibited significantly increased mortality (ptreatment group (15°C). Total Oxygen Uptake rates of experimental aggregates were greatest (112.7 mmol m-2 day-1) with 1% organic loadings in coarse sediment at 20°C. Elevated oxygen flux rates in porous coarse sediments are likely to be a function of increased vertical migration of anaerobically liberated sulphides to the sediment-water interface. However, survival of M. edulis under bacterial mats of Beggiatoa spp. indicates the species’ resilience to sulphides and so we propose that the presence of reactive organic matter within the burial medium may facilitate bacterial growth and increase mortality through pathogenic infection. This may be exacerbated under the stable interstitial conditions in fine sediment and increased bacterial metabolism under high temperatures. Furthermore, increased temperature may impose metabolic demands upon the mussel that cannot be met during burial-induced anaerobiosis. Summary Lack of consideration for the role of organic matter and temperature during sedimentation events may lead to an overestimation of the tolerance of benthic species

  6. 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

  7. Luminal lactate in acute pancreatitis - validation and relation to disease severity

    Directory of Open Access Journals (Sweden)

    Pynnönen Lauri

    2012-04-01

    Full Text Available Abstract Background Increased rectal luminal lactate concentration may be associated with the severity of the septic shock and high dose of vasopressors. It suggests hypoperfusion of the gut mucosa. This is potentially associated with bacterial translocation from the gut leading to local and systemic inflammation. In acute pancreatitis (AP bacterial translocation is considered as the key event leading to infection of necrotic pancreatic tissue and high severity of illness. Methods We used rectal luminal equilibration dialysis for the measurement of gut luminal lactate in 30 consecutive patients admitted to hospital due to acute pancreatitis to test the hypothesis that a single measurement of rectal luminal lactate predicts the severity of acute pancreatitis, the length of hospital stay, the need of intensive care and ultimately, mortality. We also tested the physiological validity of luminal lactate concentration by comparing it to luminal partial tension of oxygen. Additionally, a comparison between two different L-lactate analyzers was performed. Results High rectal luminal lactate was associated with low mucosal partial tension of oxygen (R = 0.57, p = 0.005 thereby indicating the physiological validity of the method. Rectal luminal lactate at the hospital admission was not associated with the first day or the highest SOFA score, CRP level, hospital length of stay, length of stay in intensive care or mortality. In this cohort of unselected consecutive patients with acute pancreatitis we observed a tendency of increased rectal lactate in the severe cases. Low precision and high bias was observed between two lactate analyzers. Conclusions The association between rectal luminal lactate and oxygen tension indicates that luminal lactate is a marker mucosal anaerobiosis. Comparison between two different analyzers showed poor, non-constant precision over the range of lactate concentrations. Rectal luminal lactate concentration at the time of

  8. 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

  9. Oxygen consumption rate v. rate of energy utilization of fishes: a comparison and brief history of the two measurements.

    Science.gov (United States)

    Nelson, J A

    2016-01-01

    Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2 ] in water is more challenging than measuring [O2 ], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption (M˙O2 ) has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included. PMID:26768970

  10. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  12. 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

  13. Origin and evolution of the mitochondrial proteome.

    Science.gov (United States)

    Kurland, C G; Andersson, S G

    2000-12-01

    The endosymbiotic theory for the origin of mitochondria requires substantial modification. The three identifiable ancestral sources to the proteome of mitochondria are proteins descended from the ancestral alpha-proteobacteria symbiont, proteins with no homology to bacterial orthologs, and diverse proteins with bacterial affinities not derived from alpha-proteobacteria. Random mutations in the form of deletions large and small seem to have eliminated nonessential genes from the endosymbiont-mitochondrial genome lineages. This process, together with the transfer of genes from the endosymbiont-mitochondrial genome to nuclei, has led to a marked reduction in the size of mitochondrial genomes. All proteins of bacterial descent that are encoded by nuclear genes were probably transferred by the same mechanism, involving the disintegration of mitochondria or bacteria by the intracellular membranous vacuoles of cells to release nucleic acid fragments that transform the nuclear genome. This ongoing process has intermittently introduced bacterial genes to nuclear genomes. The genomes of the last common ancestor of all organisms, in particular of mitochondria, encoded cytochrome oxidase homologues. There are no phylogenetic indications either in the mitochondrial proteome or in the nuclear genomes that the initial or subsequent function of the ancestor to the mitochondria was anaerobic. In contrast, there are indications that relatively advanced eukaryotes adapted to anaerobiosis by dismantling their mitochondria and refitting them as hydrogenosomes. Accordingly, a continuous history of aerobic respiration seems to have been the fate of most mitochondrial lineages. The initial phases of this history may have involved aerobic respiration by the symbiont functioning as a scavenger of toxic oxygen. The transition to mitochondria capable of active ATP export to the host cell seems to have required recruitment of eukaryotic ATP transport proteins from the nucleus. The identity of

  14. The activity and community structure of total bacteria and denitrifying bacteria across soil depths and biological gradients in estuary ecosystem.

    Science.gov (United States)

    Lee, Seung-Hoon; Kang, Hojeong

    2016-02-01

    The distribution of soil microorganisms often shows variations along soil depth, and even in the same soil layer, each microbial group has a specific niche. In particular, the estuary soil is intermittently flooded, and the characteristics of the surface soil layer are different from those of other terrestrial soils. We investigated the microbial community structure and activity across soil depths and biological gradients composed of invasive and native plants in the shallow surface layer of an estuary ecosystem by using molecular approaches. Our results showed that the total and denitrifying bacterial community structures of the estuarine wetland soil differed according to the short depth gradient. In growing season, gene copy number of 16S rRNA were 1.52(±0.23) × 10(11), 1.10(±0.06) × 10(11), and 4.33(±0.16) × 10(10) g(-1) soil; nirS were 5.41(±1.25) × 10(8), 4.93(±0.94) × 10(8), and 2.61(±0.28) × 10(8) g(-1) soil; and nirK were 9.67(±2.37) × 10(6), 3.42(±0.55) × 10(6), and 2.12(±0.19) × 10(6) g(-1) soil in 0 cm, 5 cm, and 10 cm depth layer, respectively. The depth-based difference was distinct in the vegetated sample and in the growing season, evidencing the important role of plants in structuring the microbial community. In comparison with other studies, we observed differences in the microbial community and functions even across very short depth gradients. In conclusion, our results suggested that (i) in the estuary ecosystem, the denitrifying bacterial community could maintain its abundance and function within shallow surface soil layers through facultative anaerobiosis, while the total bacterial community would be both quantitatively and qualitatively affected by the soil depth, (ii) the nirS gene community, rather than the nirK one, should be the first candidate used as an indicator of the microbial denitrification process in the estuary system, and (iii) as the microbial community is distributed and plays a certain

  15. 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.

  16. 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., 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 fractionation

  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. 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

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

    Science.gov (United States)

    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

  20. Acción antimicrobiana in vitro de dentífricos conteniendo fitoterápicos Antimicrobial action in vitro of dentifricies with phytoterapeutics agents

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    Liza Barreto V

    2005-08-01

    Full Text Available Este estudio analizó el potencial antimicrobiano in vitro de 7 dentífricos conteniendo fitoterápicos sobre bacterias orales recuperadas de la saliva y cepas patrón de S. mutans ATCC25175, S. sanguis ATCC 10556 y L. casei ATCC 4646. Fueron obtenidas soluciones concentradas de los dentífricos evaluados y de controles mezclándose 3 gramos de cada uno con 10 mL de agua deionozada estéril, seguido de centrifugación; los sobrenadantes resultantes fueron diluidos en proporciones de 1:2 hasta 1:32. Fue realizado un test de difusión en ágar, colocando cepas patrón y la saliva total estimulada de 10 pacientes saludables. Discos empapados con las suspensiones de los dentífricos fueron dispuestos en las placas, las cuales fueron incubadas en anaerobiosis por 48 horas, siendo los aros de inhibición medidos en milímetros. Los resultados obtenidos fueron analizados mediante ANOVA y llevando en consideración el control positivo se constató que, solamente las soluciones puras de los dentífricos presentaron capacidad antimicrobiana contra cepas patrón, equivalente a la del dentífrico con triclosan, excepto el Gessy Cristal®. Además, los dentífricos diluidos a 1:2 presentaron acción antimicrobiana contra las bacterias orales recuperadas de la saliva, excepto el Parodontax®.The aim of this study was to evaluate and compare in vitro antimicrobial potential of 7 dentifrices containing phytotherapics agents oral bacteria obtained from saliva and standard strains of S. mutans ATCC 25175, S. sanguis ATCC 10556, and L. casei ATCC 4646. For this purpose, concentrated test and control solutions were obtained by mixing 3 grams of each in 10 ml of sterile deionized water which was submitted to centrifugation, the sublimate obtained was further dissolved in a ratio of 1:2 to 1:32. A diffusion test in agar was carried out by sowing the standard strain and stimulated total saliva. Disks soaked in a dentifrices solution and then placed on culture disks

  1. Aislamiento y caracterización de cepas nativas de Lactobacillus spp. para su uso como probióticos en la industria láctea

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    Sylvia Vázquez

    2011-05-01

    Full Text Available La utilización de fermentos en la elaboración de productos lácteos es una práctica diaria a nivel industrial. En nuestro país los mismos son comprados a multinacionales extranjeras que se dedican a producir y comercializar fermentos; muchos de los cuales incorporan bacterias probióticas. Los probióticos pueden definirse como microorganismos que luego de ser consumidos en cantidades adecuadas, confieren algún efecto benéfico en el huésped. En el presente trabajo se realizó el aislamiento de una cepa de Lactobacillus de origen humano. Se identificó por tinción gram, prueba catalasa, crecimiento en anaerobiosis y aerobiosis y un test API 50 CH. Con el objetivo de probar propiedades probióticas de la cepa se llevaron a cabo estudios de resistencia al pH, tolerancia a sales biliares y se realizó un Modelo Gástrico in vitro. Los resultados permiten afirmar que estamos en presencia de una cepa nativa de Lactobacillus acidophilus caracterizada fenotípicamente con un 97% de confianza. Presentaría la habilidad de sobrevivir al pasaje a través del tubo digestivo ya que resistió la exposición a un pH similar al estomacal, pudo crecer en un medio con sales biliares y sobrevivió a la acción conjunta de la pepsina y una simulación de jugo gástrico; características que permiten clasificarla como posible cepa probiótica.Abstract  The use of starters to elaborate dairy products is a current practice in the industry. In our Country we import these starters from foreign companies dedicated to make and sale it, and most of them include probiotic bacterias. Probiotics can be defined as microorganisms that after be consumed in adequate amount, can give some advantageous effect to the host. In this study a strain of Lactobacillus was isolated from a human. The identification was done through gram stain, catalase test, aerobic and anaerobic growth, and an API 50 CH test. In order to prove the probiotic properties of the strain, studies of p

  2. Effect of a multiple mixture of herbaceous leguminous and Leucaena leucocephala in the population protozoa and other ecological groups of rumen in yearling cattle crossbreeds Holstein x Cebu

    International Nuclear Information System (INIS)

    Twenty four yearling cattle crossbreeds Holstein x Zebu of 134 kg of PV, were managed with the objective of comparing the effect of a multiple mixture of herbaceous leguminous or Leucaena leucocephala in the population protozoa and their relationship with other ecological groups and their fermentative products. The treatments were: (To) Leucaena leucocephala (T1) mixes of herbaceous legumes (Neonotonia wightii, Pueraria phaseoloides, Macroptilium atropurpurem and Centrocema pubensis). The stocking rate was 2 animals per ha and the duration of the experiment was 150 d between May to October. L. leucocephala was associated in 100% of area with nature pasture with a population density and and botanic composition of 6,000 plants per has and Sporolobius indicus, Dechantisum anmorlatum and Paspalum notatum, respectively. Chemistry and phytochemical screening were carried out. The total area was 12 ha; 6 ha per treatments. The animals also had free access to water and mixed minerals composed of (g/kg) (PO4)2 Ca3, 500; NaCl, 400; ZnCO3, 20; CuSO4, 10; FeSO4, 27; MgSO4, 23; CoSO4, 0.1; Sodium Selenite, 0.02 and 19.86 mixed maize. Dry matter digestibility, expressed as stocking grass, was of 12.9 kg DM.100 kg de PV -1 with legumes mixes and 9.9 kg de DM. 100 kg de PV-1 with Leucaena. Rumen liquor samples were taken at 10:00 a.m. with oesophageal tube every month to determine ruminal bacteria, protozoa and fungi populations, pH, ammonia, VFA, and methane production. The technique of culture in roll tubes was used under conditions of strict anaerobiosis. There were not significant differences in the ruminal protozoa population when L. leucocephala or legumes mixtures were used in the diet. In both treatments the protozoa populations were lower in respect to diets without legumes. This result suggests that multiple mixtures or Leucaena produce defaunant effect in the rumen. With the use of multiple mixtures of herbaceous legumes, the ruminal cellulolytic bacteria population was

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  5. 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

  6. 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

  7. ``What comes up … must come down'': Peat carbon and mineral-interactions in Arctic Coastal tundra

    Science.gov (United States)

    Raab, T. K.; Lipson, D.; Crook, N. P.; Miller, K.; Bozzolo, F.

    2010-12-01

    Coastal arctic tundra is a significant landscape unit above 65o N, and in the absence of significant nitrate, sulfate or manganese, these wet, permafrost-influenced soils have few electron acceptors readily available to support microbial anaerobiosis. Based on morphological criteria and satellite photos, we selected 4 drained, thaw-lake basins (DTLBs) of vastly differing ages - 50 to 5500 years, based on 14C-dating efforts near Barrow AK. Replicate 100m transects for each thawed-lake basin were collected using a towable 500 MHz ground-penetrating radar system. Inspection of the raw profiles in the field further suggested points along which 20m-length common-midpoint gathers were also obtained to discriminate contrasting propagation speeds within the top 0.5 m of the surface. At later visits, several SIPRE cores were taken to 0.5 m-depth, and the cores stored frozen until analysis. The cores were measured, and physical/color and mineral data collected to correlate with the CMP velocity-profiles. The point of these measurements was to ascertain the minimum-depth to mineral material below the surficial peats, and to build-up a profile of basin age versus mineral-depth. Availability of inorganic reducing agents may provide a significant constraint on soil microbial C-processing. Minimum-tension microlysimeters (PTFE and iron-free) were deployed along replicate transects in each of 5 basins, and filtered soil-pore water was collected from 0-10 cm, as was filtered, acidified standing water from early June-Sept of both 2009 and 2010. Results of inorganic analyses are presented in a separate poster. Fluorescence spectroscopy was used to monitor seasonal patterns in DOC composition, and fluorescence emission intensity of soil pore-water was inversely proportional to basin age - humic signature emission spectra peaked sharply at 445 nm, and a broader secondary maximum occurred at 500 nm. Fluorescence emission varied 5-fold among basins, and decreased at all sites as soil

  8. Effect of mineral fertilizers on microbiological and biochemical characteristics of agrochernozem.

    Science.gov (United States)

    Tkhakakhova, Azida; Vasilenko, Elena; Kutovaya, Olga

    2013-04-01

    The problem of reproduction of soil fertility of chernozems are solved with integrated action, the ecological condition of the soil can be assessed by the activity of physiological groups of microorganisms. Microorganisms are the most important in the transformation of compounds of biogenic elements and therefore it is very interesting to study the nature of the relationship of some biochemical parameters with the development of microflora and micromycetes eco-trophic groups. Agrochemical researches have been conducted at agroecological station "Stone Steppe" in central Russia. Experiment variants: 1 - Control (without fertilizer); 2 - N10,5 P10,5 K10,5; 3 - N56,5 P56,5 K56,5; 4 - deposit soil. Mobile forms of humic substances (mobile carbon and carbon water extract) have changed during the cultivation of the chernozem soil. Amount of mobile humus has doubled in the variants with the use of mineral fertilizers. It's just mobile humus which determines the soil response to any impact, especially ecological. Water extract carbon - organic matter contained in the soil solution and the subject of assimilation of plants and microorganisms. It increased in agricultural soils. The total nitrogen and nitrate nitrogen amount in the variants of agricultural use is higher than in the deposit soil. This is probably because of the soil aeration, the release of nitrogen from the labile humus due to biological activity and nitrification. Amount of ammonia nitrogen has increased in the variant with the use of high doses of fertilizers. Deposit soil (40 years without agricultural use) has a lower, but more stable microbial activity. Process of anoxic decomposition of plant remains develops more active than others, due to the natural structure of the soil anaerobiosis in the spring time. Processes of nitrogen cycle (nitrogen accumulation - fixation of atmospheric nitrogen, nitrogen losses - denitrification) are progressing very intensively in agricultural soil with fertilizer

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

    International Nuclear Information System (INIS)

    A 7 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. We put several apparatus in the soil profile to follow soil water content, gas and temperature. These probes were: Temperature sensors, installed at 5, 20, 60, 100 and 170 cm depth; Tensiometers, installed each 20 cm from 20 to 220 cm depth; Capacitive probes, installed each 20 cm from 20 to 160 cm depth; Gas probes, installed each 20 cm from 20 to 200 cm depth; A piezometer reaching 300 cm depth; A pluviograph Temperature sensors, tensiometers and capacitive probes are electronic probes connected to a data collecting apparatus. With gas probes, we followed CO2, O2, N2 and N2O concentrations. One of the objectives was to determine the 13C gas profile and also to evaluate rainfall effect on soil CO2 production and 13CO2 isotope. Then, two soil 13CO2 profiles (figure) were established before and after a rainfall event (55 mm), at the beginning of May 2002, and discussed relative to CO2 gas diffusion, soil texture and composition (organic carbon content), soil water content and microbial respiration measurements. The last has been carried out by O2 consumption measurements on soil samples re-wetted and equilibrated at a 0,001Mpa water suction for 48h at 20 deg. C. As expected for a soil cultivated with C4 plant, isotopic 13C

  10. 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

  11. 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

  12. 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

  13. 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