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Sample records for aerobiosis

  1. Comparative genomic analysis reveals 2-oxoacid dehydrogenase complex lipoylation correlation with aerobiosis in archaea.

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    Kirill Borziak

    Full Text Available Metagenomic analyses have advanced our understanding of ecological microbial diversity, but to what extent can metagenomic data be used to predict the metabolic capacity of difficult-to-study organisms and their abiotic environmental interactions? We tackle this question, using a comparative genomic approach, by considering the molecular basis of aerobiosis within archaea. Lipoylation, the covalent attachment of lipoic acid to 2-oxoacid dehydrogenase multienzyme complexes (OADHCs, is essential for metabolism in aerobic bacteria and eukarya. Lipoylation is catalysed either by lipoate protein ligase (LplA, which in archaea is typically encoded by two genes (LplA-N and LplA-C, or by a lipoyl(octanoyl transferase (LipB or LipM plus a lipoic acid synthetase (LipA. Does the genomic presence of lipoylation and OADHC genes across archaea from diverse habitats correlate with aerobiosis? First, analyses of 11,826 biotin protein ligase (BPL-LplA-LipB transferase family members and 147 archaeal genomes identified 85 species with lipoylation capabilities and provided support for multiple ancestral acquisitions of lipoylation pathways during archaeal evolution. Second, with the exception of the Sulfolobales order, the majority of species possessing lipoylation systems exclusively retain LplA, or either LipB or LipM, consistent with archaeal genome streamlining. Third, obligate anaerobic archaea display widespread loss of lipoylation and OADHC genes. Conversely, a high level of correspondence is observed between aerobiosis and the presence of LplA/LipB/LipM, LipA and OADHC E2, consistent with the role of lipoylation in aerobic metabolism. This correspondence between OADHC lipoylation capacity and aerobiosis indicates that genomic pathway profiling in archaea is informative and that well characterized pathways may be predictive in relation to abiotic conditions in difficult-to-study extremophiles. Given the highly variable retention of gene repertoires across

  2. Quantitative assessment of oxygen availability: perceived aerobiosis and its effect on flux distribution in the respiratory chain of Escherichia coli.

    Science.gov (United States)

    Alexeeva, Svetlana; Hellingwerf, Klaas J; Teixeira de Mattos, M Joost

    2002-03-01

    Despite a large number of studies on the role of oxygen in cellular processes, there is no consensus as to how oxygen availability to the cell should be defined, let alone how it should be quantified. Here, a quantitative definition for oxygen availability (perceived aerobiosis) is presented; the definition is based on a calibration with reference to the minimal oxygen supply rate needed for fully oxidative catabolism (i.e., complete conversion of the energy source to CO(2) and water for glucose-limited conditions). This quantitative method is used to show how steady-state electron fluxes through the alternative cytochrome oxidases of Escherichia coli are distributed as a function of the extent of aerobiosis of glucose-limited chemostat cultures. At low oxygen availability the electron flux is mainly via the high-affinity cytochrome bd oxidase, and, at higher oxygen availability, a similar phenomenon occurs but now via the low-affinity cytochrome bo oxidase. The main finding is that the catabolic activities of E. coli (and specifically its respiratory activity) are affected by the actual oxygen availability per unit of biomass rather than by the residual dissolved oxygen concentration of the culture. PMID:11844770

  3. Truce with oxygen - A naerobiosis outcompete aerobiosis in the Antarctic lacustrine bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nair, S.; DeSouza, M.J.B.D.; Chandramohan, D.

    The total number of bacteria counted directly by epifluorescent microscopy showed that they ranged from 10 sup(8)-10 sup(-1) in Antarctic lake water samples. The percentages of retrievable viable counts (RVC) of anaerobic bacteria (AnB) was greater...

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

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    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

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

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    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.

  6. The Lactococcus lactis Thioredoxin System

    DEFF Research Database (Denmark)

    Efler, Petr

    D mutant vs. wt upon exposure to sodium arsenate showed down-regulation of several ATPases (DnaK and GroEL) and GTPases (Ef-G, Ef-Ts) concomitantly with up-regulation of enzymes involved in aerobiosis and nucleotide metabolism in the ΔtrxD mutant. The ΔtrxAΔtrxD deletion mutant is viable, in agreement with...

  7. INDUCTION OF ANAEROBIC PROCESSES IN BAIKAL ENDEMICS EULIMNOGAMMARUS VITTATUS (DYB. AND E. VERRUCOSUS (DYB. (AMPHIPODA, CRUSTACEA

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    Timofeyev M.A.

    2006-03-01

    Full Text Available The data confirming the ability of Baikalian endemic species Eulimnogammarus vittatus (Dyb. and E. verrucosus (Dyb. to activate anaerobic glycolysis under hypoxia are presented. The differences in the degree and the rate of lactic acid accumulation and remetabolisation in returning to aerobiosis are noted in the species concerned. On the example of E. vittatus the ability of Baikalian endemics to activate anaerobic lipolysis and process of anaerobic formation of succinate is shown

  8. INDUCTION OF ANAEROBIC PROCESSES IN BAIKAL ENDEMICS EULIMNOGAMMARUS VITTATUS (DYB.) AND E. VERRUCOSUS (DYB.) (AMPHIPODA, CRUSTACEA)

    OpenAIRE

    Timofeyev M.A; Kirichenko K.A.; Rokhin A.V.; Bedulina D.S.; Chernyshova K.P.; Pobezhimova T.P.

    2006-01-01

    The data confirming the ability of Baikalian endemic species Eulimnogammarus vittatus (Dyb.) and E. verrucosus (Dyb.) to activate anaerobic glycolysis under hypoxia are presented. The differences in the degree and the rate of lactic acid accumulation and remetabolisation in returning to aerobiosis are noted in the species concerned. On the example of E. vittatus the ability of Baikalian endemics to activate anaerobic lipolysis and process of anaerobic formation of succinate is shown

  9. Iron is required to relieve inhibitory effects on NifL on transcriptional activation by NifA in Klebsiella pneumoniae.

    OpenAIRE

    Schmitz, R. A.; He, L.; Kustu, S

    1996-01-01

    In Klebsiella pneumoniae, products of the nitrogen fixation nifLA operon regulate transcription of the other nif operons. NifA activates transcription by sigma54-holoenzyme. In vivo, NifL antagonizes the action of NifA under aerobic conditions or in the presence of combined nitrogen. In contrast to a previous report, we show that depletion of iron (Fe) from the growth medium with the chelating agent o-phenanthroline (20 microM) mimics aerobiosis or combined nitrogen in giving rise to inhibiti...

  10. SUT1 suppresses sec14-1 through upregulation of CSR1 in Saccharomyces cerevisiae.

    Science.gov (United States)

    Régnacq, Matthieu; Ferreira, Thierry; Puard, Julien; Bergès, Thierry

    2002-11-01

    SUT1 constitutive expression in aerobiosis suppressed the ts phenotype of the sec14-1 mutation, restored growth of the sec14-null mutant and corrected the translocation defect of the vacuolar carboxypeptidase Y. Therefore SUT1 was shown to be a novel potent sec14-1 suppressor. Further, the hypoxic gene CSR1 (YLR380W), a Sec14 homolog, was upregulated upon SUT1 constitutive expression. In addition, SUT1 effects on both sec14-1 suppression and on free sterol composition were abolished in a csr1-null background, showing that this gene acts downstream of SUT1. PMID:12435498

  11. Survival rate of campylobacter coli strains in sterile buffalo and bovine milk Tasas de sobrevida de Campylobacter coli en leche de búfalo y de bovino

    OpenAIRE

    A. TRESIERRA-AYALA; Guzmán, A.; H Fernández

    2001-01-01

    The survival rate of five Campylobacter coli strains, isolated from bovine faeces (3) and from buffalo faeces (2), was studied in sterile buffalo and bovine milk kept at 4°C under aerobic conditions. All strains lost their viability substantially more rapidly in buffalo milk than in bovine milkSe determinó, en leche de bovino y de búfalo autoclavadas y mantenidas a 4ºC bajo condiciones de aerobiosis, la sobrevida de cinco cepas de Campylobacter coli aisladas de fecas de bovino (3) y ...

  12. 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)

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

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    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.

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

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    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

  15. Biodegradación de compuestos fenólicos del alpechín con Aspergillus terreus

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    García Paeja, María P.

    1992-04-01

    Full Text Available Olive mill wastewater degradation by Aspergillus terreus and under aerobic conditions at 28°C, was measured by the parameter of phenol content. We have explored the effect of different concentrations of olive mill wastewater upon the activity of Aspergillus terreus. Through HPLC, 10 phenol compounds (90% of the total phenolic content of the olive mill wastewater were identified.Se estudia la degradación de alpechines con Aspergillus terreus en condiciones de aerobiosis y temperatura de 28°C, utilizando como parámetro el contenido fenólico. Se analiza el efecto de la concentración de alpechín con Aspergillus terreus utilizando el mismo parámetro. Se han identificado por cromatografía líquida de alta eficacia (CLAE 10 compuestos fenólicos que suponen el 90% del total del alpechín.

  16. Survival rate of campylobacter coli strains in sterile buffalo and bovine milk Tasas de sobrevida de Campylobacter coli en leche de búfalo y de bovino

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    A. TRESIERRA-AYALA

    2001-01-01

    Full Text Available The survival rate of five Campylobacter coli strains, isolated from bovine faeces (3 and from buffalo faeces (2, was studied in sterile buffalo and bovine milk kept at 4°C under aerobic conditions. All strains lost their viability substantially more rapidly in buffalo milk than in bovine milkSe determinó, en leche de bovino y de búfalo autoclavadas y mantenidas a 4ºC bajo condiciones de aerobiosis, la sobrevida de cinco cepas de Campylobacter coli aisladas de fecas de bovino (3 y de búfalo (2. Todas las cepas perdieron su viabilidad más rápidamente en leche de búfalo que en leche bovina

  17. Growth kinetic study of Tetratrichomonas didelphidis isolated from opossum Lutreolina crassicaudata and interaction with a prokaryotic cell.

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    Tasca, T; DeCarli, G A

    2001-08-01

    Tetratrichomonas didelphidis is a flagellate protozoan found in the intestine, cecum and colon of opossums, Didelphis marsupialis. This work reports the occurrence of T. didelphidis in another opossum species, Lutreolina crassicaudata. The strain was cultivated in monoxenic culture with Escherichia coli in Diamond (TYM) medium without maltose and with starch solution (trypticase-yeast extract-starch), pH 7.5 at 28 degrees C. The growth kinetic study of T. didelphidis showed a longer time of growth and a higher number of trophozoites when inoculated with E. coli than in axenic cultures, in aerobiosis as well as under anaerobic conditions. Scanning electron microscopy showed that the bacteria adhered throughout the protozoan body and probably evoked endocytic channels, strongly suggesting the existence of endocytosis of rods by T. didelphidis. Our preliminary results suggest that the in vitro culture of T. didelphidis depends on E. coli as a growth-promoting partner, and requires monoxenic cultivation. PMID:11510998

  18. Earth's earliest biosphere: Its origin and evolution

    International Nuclear Information System (INIS)

    Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

  19. MÉTODO EFECTIVO PARA LA DESINFECCIÓN TOTAL DE ESPORAS DE HONGOS MICORRIZÓGENOS ARBUSCULARES (HMA: AISLAMIENTO Y CARACTERIZACIÓN DE BACTERIAS ENDOSPÓRICAS EN Glomus clarum

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    Lorelí Mirabal

    2002-01-01

    Full Text Available Los hongos micorrizógenos arbusculares (HMA son endosimbiontes obligados, presentes en muchos ecosistemas naturales y agrícolas, con gran responsabilidad en la integridad fisiológica de la planta. Esta investigación se basa en la realización de diferentes aislamientos de Glomus clarum, proveniente de cultivos puros del cepario del INCA. Se aislaron y purificaron 25 cepas bacterianas endospóricas, a las cuales se les realizaron varias pruebas morfológicas y bioquímicas, siendo muy interesantes la aerobiosis y la capacidad nitrofijadora. Tres cepas bacterianas aisladas tienen características coincidentes con el endófito diazótrofo Gluconoacetobacter diazotrophicus. Además, se estableció un método efectivo para la desinfección total de la pared externa de las esporas de HMA.

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

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    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

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

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    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

  2. 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

  3. Microbiota associated with chronic osteomyelitis of the jaws

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    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

  4. Microbiota associated with chronic osteomyelitis of the jaws

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    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.

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

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    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.

  6. 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

  7. An evaluation and partial characterization of a bacteriocin produced by Lactococcus lactis subsp lactis ST1 isolated from goat milk.

    Science.gov (United States)

    Taheri, Parinaz; Samadi, Nasrin; Ehsani, Mohammad Reza; Khoshayand, Mohammad Reza; Jamalifar, Hossein

    2012-10-01

    A bacteriocin-like inhibitory substance producing Lactococcus lactis subsp lactis strain, ST1, isolated from goat milk of Iranian origin and with broad spectrum of activity and desirable technical properties was used for evaluating some futures of bacteriocin inhibitory activity. Cell growth and bacteriocin production studies were carried out in MRS medium incubated statically under uncontrolled pH condition. The antibacterial activity presented a primary metabolite pattern and showed a rapid decrease at the stationary phase. Microaerobiosis and capnophily growth conditions resulted in higher bacteriocin production while aerobiosis showed negative effect on both cell growth and bacteriocin production. Bacteriocin production, on the other hand, was favored in MRS broth (pH; 6.5) inoculated with 0.1 ml l(-1) fresh culture when incubation was carried out at 30 °C. This indicated that the conditions resulted in higher levels of growth were frequently favoring bacteriocin production by ST1 as well. Decrease in activity, at the stationary growth phase, was much pronounced in favored growth condition. Nutrient depletion, deferent effect of low pH on bacteriocin production and/or protein degradation seemed more responsible for this phenomenon. The study also provided further data on new method for bacteriocin release from the cell wall of producer. It was clearly shown that both heating and ultrasound shock for 5 min at pH 2 could increase bacteriocin activity significantly. The release was more pronounced in the presence of 0.5% Tween80. PMID:24031976

  8. An evaluation and partial characterization of a bacteriocin produced by Lactococcus lactis subsp lactis ST1 isolated from goat milk

    Directory of Open Access Journals (Sweden)

    Parinaz Taheri

    2012-12-01

    Full Text Available A bacteriocin-like inhibitory substance producing Lactococcus lactis subsp lactis strain, ST1, isolated from goat milk of Iranian origin and with broad spectrum of activity and desirable technical properties was used for evaluating some futures of bacteriocin inhibitory activity. Cell growth and bacteriocin production studies were carried out in MRS medium incubated statically under uncontrolled pH condition. The antibacterial activity presented a primary metabolite pattern and showed a rapid decrease at the stationary phase. Microaerobiosis and capnophily growth conditions resulted in higher bacteriocin production while aerobiosis showed negative effect on both cell growth and bacteriocin production. Bacteriocin production, on the other hand, was favored in MRS broth (pH; 6.5 inoculated with 0.1 ml l-1 fresh culture when incubation was carried out at 30 °C. This indicated that the conditions resulted in higher levels of growth were frequently favoring bacteriocin production by ST1 as well. Decrease in activity, at the stationary growth phase, was much pronounced in favored growth condition. Nutrient depletion, deferent effect of low pH on bacteriocin production and/or protein degradation seemed more responsible for this phenomenon. The study also provided further data on new method for bacteriocin release from the cell wall of producer. It was clearly shown that both heating and ultrasound shock for 5 min at pH 2 could increase bacteriocin activity significantly. The release was more pronounced in the presence of 0.5% Tween80.

  9. 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

  10. 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

  11. Effects of hypoxia and ethanol on xanthine oxidase of isolated rat hepatocytes: conversion from D to O form and leakage from cells.

    Science.gov (United States)

    Battelli, M G; Abbondanza, A; Stirpe, F

    1992-06-15

    The combined effects of ethanol and hypoxia on the conversion of xanthine dehydrogenase (D form) to xanthine oxidase (O form) and on the leakage of the enzyme from isolated rat hepatocytes was studied. Time-dependent death of cells occurred during incubation in hypoxic conditions. Ethanol (40 mM) had only a moderate effect on viability in aerobiosis, but accelerated the loss of hypoxic cells, which was 96% after 3 h of incubation. In hypoxic conditions, the xanthine oxidase was gradually converted from D into O form. The conversion was complete in 3 h, and was accelerated by 1 mM xanthine or by ethanol, in a concentration-related manner. Hypoxia brought about a progressive leakage of xanthine oxidase from hepatocytes, which was accelerated by ethanol in a concentration-dependent manner. The enzyme found outside hepatocytes was mostly in its O form. The xanthine oxidase of hepatocytes cytosol was converted from D into O form by human plasma or serum. In all cases the conversion could be completely reverted by treatment of the extract with dithiothreitol. PMID:1643670

  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. Two-Dimensional Stable Isotope Fractionation During Aerobic and Anaerobic Alkane Biodegradation and Implications for the Field

    Science.gov (United States)

    El Morris, Brandon; Suflita, Joseph M.; Richnow, Hans-Hermann

    2010-05-01

    Quantitatively, n-alkanes comprise a major portion of most crude oils. In petroliferous formations, it may be possible to relate the loss of these compounds to the levels of biodegradation occurring in situ [1]. Moreover, it is important to develop indicators of alkane degradation that may be used to monitor bioremediation of hydrocarbon-impacted environments. Desulfoglaeba alkanexedens and Pseudomonas putida GPo1 were used to determine if carbon and hydrogen stable isotope fractionation could differentiate between n-alkane degradation under anaerobic and aerobic conditions, respectively in the context of the Rayleigh equation model [2]. Bacterial cultures were sacrificed by acidification and headspace samples were analyzed for stable isotope composition using gas chromatography-isotope ratio mass spectrometry. Carbon enrichment factors (bulk) for anaerobic and aerobic biodegradation of hexane were -5.52 ± 0.2‰ and -4.34 ± 0.3‰, respectively. Hydrogen enrichment during hexane degradation was -43.14 ± 6.32‰ under sulfate-reducing conditions, and was too low for quantification during aerobiosis. Collectively, this indicates that the correlation between carbon and hydrogen stable isotope fractionation (may be used to help elucidate in situ microbial processes in oil reservoirs, and during intrinsic as well as engineered remediation efforts. References 1. Asif, M.; Grice, K.; Fazeelat, T., Assessment of petroleum biodegradation using stable hydrogen isotopes of individual saturated hydrocarbon and polycyclic aromatic hydrocarbon distributions in oils from the Upper Indus Basin, Pakistan. Organic Geochemistry 2009, 40, (3), 301-311. 2. Fischer, A.; Herklotz, I.; Herrmann, S.; Thullner, M.; Weelink, S. A. B.; Stams, A., J. M.; Schloemann, M.; Richnow, H.-H.; Vogt, C., Combined carbon and hydrogen isotope fractionation investigations for elucidating benzene biodegradation pathways. Environ. Sci. Technol. 2008, 42, 4356-4363.

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

    Directory of Open Access Journals (Sweden)

    Joaquín Guillermo Ramírez Gil

    2013-12-01

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

  15. Screening of bacterial strains capable of converting biodiesel-derived raw glycerol into 1,3-propanediol, 2,3-butanediol and ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Metsoviti, Maria; Paramithiotis, Spiros; Drosinos, Eleftherios H.; Galiotou-Panayotou, Maria; Nychas, George-John E.; Papanikolaou, Seraphim [Department of Food Science and Technology, Agricultural University of Athens, Athens (Greece); Zeng, An-Ping [Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology (TUHH), Hamburg (Germany)

    2012-02-15

    The ability of bacterial strains to assimilate glycerol derived from biodiesel facilities to produce metabolic compounds of importance for the food, textile and chemical industry, such as 1,3-propanediol (PD), 2,3-butanediol (BD) and ethanol (EtOH), was assessed. The screening of 84 bacterial strains was performed using glycerol as carbon source. After initial trials, 12 strains were identified capable of consuming raw glycerol under anaerobic conditions, whereas 5 strains consumed glycerol under aerobiosis. A plethora of metabolic compounds was synthesized; in anaerobic batch-bioreactor cultures PD in quantities up to 11.3 g/L was produced by Clostridium butyricum NRRL B-23495, while the respective value was 10.1 g/L for a newly isolated Citrobacter freundii. Adaptation of Cl. butyricum at higher initial glycerol concentration resulted in a PD{sub max} concentration of {proportional_to}32 g/L. BD was produced by a new Enterobacter aerogenes isolate in shake-flask experiments, under fully aerobic conditions, with a maximum concentration of {proportional_to}22 g/L which was achieved at an initial glycerol quantity of 55 g/L. A new Klebsiella oxytoca isolate converted waste glycerol into mixtures of PD, BD and EtOH at various ratios. Finally, another new C. freundii isolate converted waste glycerol into EtOH in anaerobic batch-bioreactor cultures with constant pH, achieving a final EtOH concentration of 14.5 g/L, a conversion yield of 0.45 g/g and a volumetric productivity of {proportional_to}0.7 g/L/h. As a conclusion, the current study confirmed the utilization of biodiesel-derived raw glycerol as an appropriate substrate for the production of PD, BD and EtOH by several newly isolated bacterial strains under different experimental conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. The Sinorhizobium meliloti RNA chaperone Hfq influences central carbon metabolism and the symbiotic interaction with alfalfa

    Directory of Open Access Journals (Sweden)

    Jiménez-Zurdo José I

    2010-03-01

    Full Text Available Abstract Background The bacterial Hfq protein is able to interact with diverse RNA molecules, including regulatory small non-coding RNAs (sRNAs, and thus it is recognized as a global post-transcriptional regulator of gene expression. Loss of Hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. Sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. Despite the predicted general involvement of Hfq in the establishment of successful bacteria-eukaryote interactions, its function in S. meliloti has remained unexplored. Results Two independent S. meliloti mutants, 2011-3.4 and 1021Δhfq, were obtained by disruption and deletion of the hfq gene in the wild-type strains 2011 and 1021, respectively, both exhibiting similar growth defects as free-living bacteria. Transcriptomic profiling of 1021Δhfq revealed a general down-regulation of genes of sugar transporters and some enzymes of the central carbon metabolism, whereas transcripts specifying the uptake and metabolism of nitrogen sources (mainly amino acids were more abundant than in the wild-type strain. Proteomic analysis of the 2011-3.4 mutant independently confirmed these observations. Symbiotic tests showed that lack of Hfq led to a delayed nodulation, severely compromised bacterial competitiveness on alfalfa roots and impaired normal plant growth. Furthermore, a large proportion of nodules (55%-64% elicited by the 1021Δhfq mutant were non-fixing, with scarce content in bacteroids and signs of premature senescence of endosymbiotic bacteria. RT-PCR experiments on RNA from bacteria grown under aerobic and microoxic conditions revealed that Hfq contributes to regulation of nifA and fixK1/K2, the genes controlling nitrogen fixation, although the Hfq-mediated regulation of fixK is only aerobiosis dependent. Finally, we found that some of the recently

  17. Adhesion, Biofilm Formation, and Genomic Features of Campylobacter jejuni Bf, an Atypical Strain Able to Grow under Aerobic Conditions.

    Science.gov (United States)

    Bronnec, Vicky; Turoňová, Hana; Bouju, Agnès; Cruveiller, Stéphane; Rodrigues, Ramila; Demnerova, Katerina; Tresse, Odile; Haddad, Nabila; Zagorec, Monique

    2016-01-01

    Campylobacter jejuni is the leading cause of bacterial enteritis in Europe. Human campylobacteriosis cases are frequently associated to the consumption of contaminated poultry meat. To survive under environmental conditions encountered along the food chain, i.e., from poultry digestive tract its natural reservoir to the consumer's plate, this pathogen has developed adaptation mechanisms. Among those, biofilm lifestyle has been suggested as a strategy to survive in the food environment and under atmospheric conditions. Recently, the clinical isolate C. jejuni Bf has been shown to survive and grow under aerobic conditions, a property that may help this strain to better survive along the food chain. The aim of this study was to evaluate the adhesion capacity of C. jejuni Bf and its ability to develop a biofilm. C. jejuni Bf can adhere to abiotic surfaces and to human epithelial cells, and can develop biofilm under both microaerobiosis and aerobiosis. These two conditions have no influence on this strain, unlike results obtained with the reference strain C. jejuni 81-176, which harbors only planktonic cells under aerobic conditions. Compared to 81-176, the biofilm of C. jejuni Bf is more homogenous and cell motility at the bottom of biofilm was not modified whatever the atmosphere used. C. jejuni Bf whole genome sequence did not reveal any gene unique to this strain, suggesting that its unusual property does not result from acquisition of new genetic material. Nevertheless some genetic particularities seem to be shared only between Bf and few others strains. Among the main features of C. jejuni Bf genome we noticed (i) a complete type VI secretion system important in pathogenicity and environmental adaptation; (ii) a mutation in the oorD gene involved in oxygen metabolism; and (iii) the presence of an uncommon insertion of a 72 amino acid coding sequence upstream from dnaK, which is involved in stress resistance. Therefore, the atypical behavior of this strain under

  18. Adhesion, Biofilm Formation, and Genomic Features of Campylobacter jejuni Bf, an Atypical Strain Able to Grow under Aerobic Conditions

    Science.gov (United States)

    Bronnec, Vicky; Turoňová, Hana; Bouju, Agnès; Cruveiller, Stéphane; Rodrigues, Ramila; Demnerova, Katerina; Tresse, Odile; Haddad, Nabila; Zagorec, Monique

    2016-01-01

    Campylobacter jejuni is the leading cause of bacterial enteritis in Europe. Human campylobacteriosis cases are frequently associated to the consumption of contaminated poultry meat. To survive under environmental conditions encountered along the food chain, i.e., from poultry digestive tract its natural reservoir to the consumer’s plate, this pathogen has developed adaptation mechanisms. Among those, biofilm lifestyle has been suggested as a strategy to survive in the food environment and under atmospheric conditions. Recently, the clinical isolate C. jejuni Bf has been shown to survive and grow under aerobic conditions, a property that may help this strain to better survive along the food chain. The aim of this study was to evaluate the adhesion capacity of C. jejuni Bf and its ability to develop a biofilm. C. jejuni Bf can adhere to abiotic surfaces and to human epithelial cells, and can develop biofilm under both microaerobiosis and aerobiosis. These two conditions have no influence on this strain, unlike results obtained with the reference strain C. jejuni 81-176, which harbors only planktonic cells under aerobic conditions. Compared to 81-176, the biofilm of C. jejuni Bf is more homogenous and cell motility at the bottom of biofilm was not modified whatever the atmosphere used. C. jejuni Bf whole genome sequence did not reveal any gene unique to this strain, suggesting that its unusual property does not result from acquisition of new genetic material. Nevertheless some genetic particularities seem to be shared only between Bf and few others strains. Among the main features of C. jejuni Bf genome we noticed (i) a complete type VI secretion system important in pathogenicity and environmental adaptation; (ii) a mutation in the oorD gene involved in oxygen metabolism; and (iii) the presence of an uncommon insertion of a 72 amino acid coding sequence upstream from dnaK, which is involved in stress resistance. Therefore, the atypical behavior of this strain under

  19. Iron is required to relieve inhibitory effects on NifL on transcriptional activation by NifA in Klebsiella pneumoniae.

    Science.gov (United States)

    Schmitz, R A; He, L; Kustu, S

    1996-08-01

    In Klebsiella pneumoniae, products of the nitrogen fixation nifLA operon regulate transcription of the other nif operons. NifA activates transcription by sigma54-holoenzyme. In vivo, NifL antagonizes the action of NifA under aerobic conditions or in the presence of combined nitrogen. In contrast to a previous report, we show that depletion of iron (Fe) from the growth medium with the chelating agent o-phenanthroline (20 microM) mimics aerobiosis or combined nitrogen in giving rise to inhibition of NifA activity even under anaerobic, nitrogen-limiting conditions. Adding back Fe in only twofold molar excess over phenanthroline restores NifA activity, whereas adding other metals fails to do so. By using strains that lack NifL, we showed that NifA activity itself does not require Fe and is not directly affected by phenanthroline. Hence, Fe is required to relieve the inhibition of NifA activity by NifL in vivo. Despite the Fe requirement in vivo, we have found no evidence that NifL contains Fe or an iron-sulfur (Fe-S) cluster. Determination of the molecular mass of an inhibitory form of NifL overproduced under aerobic conditions indicated that it was not posttranslationally modified. When NifL was synthesized in vitro, it inhibited transcriptional activation by NifA even when it was synthesized under anaerobic conditions in the presence of a high Fe concentration or of superoxide dismutase, which is known to protect some Fe-S clusters. Moreover, overproduction of superoxide dismutase in vivo did not relieve NifL, inhibition under aerobic conditions, and attempts to relieve NifL inhibition in vitro by reconstituting Fe-S clusters with the NifS enzyme (Azotobacter vinelandii) were unsuccessful. Since we obtained no evidence that Fe acts directly on NifL or NifA, we postulate that an additional Fe-containing protein, not yet identified, may be required to relieve NifL inhibition under anaerobic, nitrogen-limiting conditions. PMID:8755900

  20. The Cloud Paradigm: Geostable molecules as proxies for surface oxygenation

    Science.gov (United States)

    Summons, R. E.; Hallmann, C.

    2011-12-01

    before the great oxidation event. Science 317, 1903-1906. (2007). Bosak T. et al., Morphological record of oxygenic photosynthesis in conical stromatolites. Proc. Natl. Acad. Sci. USA 106:10939-10943 (2009). Kopp, R.E. et al.,The Paleoproterozoic snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis. Proc. Natl. Acad. Sci. USA 102: 11131-11136 (2005). Waldbauer J.R. et al. Late Archean molecular fossils from the Transvaal Supergroup record the antiquity of microbial diversity and aerobiosis. Precambrian Research 169, 28-47 (2008).

  1. Aluminium effects on calcium uptake in chicken isolated duodenal cells

    International Nuclear Information System (INIS)

    Full text: The objective of this work was to study in vitro actions of aluminium (Al) on kinetics of radio calcium uptake (45CaUPT) in chicken isolated duodenal cells. Epithelial cells, obtained according to method described by Liang et al., were incubated in aero-biosis, during 30 min. with 0 and 100 μM Al lactate, at [Ca2+] varying from 0.01 to 5 μM (pH 7.4). Apparent constants Vmax and Km were calculated from 45CaUPT vs. [Ca2+] plots by a non-linear fitting method using the Marquardt-Levenburg algorithm. Curves were compared by analysis of covariance. In other series of experiments, enterocytes were treated with Al in presence of: 1) diltiazem (D) or nifedipine (N) (blockers of L-type voltage-dependent Ca channels, VOCC): 1, 10 and 100 μM; 2) A23187 (Ca ionophore): 1 μM; 3) Bay K8644 (Ca channel activator, acting on dihydroxypyridine site): 1 μM; 4) capsaicin (activator of Epithelial Calcium Channel, ECaC): 2 and 20 μM; 5) U73122 (activator of store-operated Ca channels): 1 nM. Controls were incubated with respective vehicles (C). Results were expressed as % of respective Al-free control. Al significantly reduced both Vmax (15.3 ± 1.9 vs. 22.1 ± 3.4 nmol Ca/mg prot.) and Km (1.4 ± 0.2 vs. 2.1 ± 0.4 mM) as compared to Al-free control (P< 0.05). D from 1 μM (101 ± 2 %) and N from 10 μM (100 ± 3%), completely annulled Al inhibition as compared to C (56 ± 3%). Bay K8644 (82 ± 4%), U73122 (84 ± 3%) and capsaicin (2 μM= 97 ± 2%, 20 μM= 89 ± 3%) reduced Al inhibition. A23187 increased Al inhibition (45 ± 3%, n = 4, P< 0.05, ANOVA). In summary, Al could reduce Ca entry in chicken enterocytes acting directly on VOCC, preferably in the open state of channels. (author)

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

    Directory of Open Access Journals (Sweden)

    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

  3. In situ carbon isotope analysis of Archean organic matter with SIMS

    Science.gov (United States)

    Williford, K. H.; Ushikubo, T.; Lepot, K.; Hallmann, C.; Spicuzza, M. J.; Eigenbrode, J. L.; Summons, R. E.; Valley, J. W.

    2011-12-01

    rates as low as 10% relative to anthracite. Samples from the ABDP-9 (n=3; Mount McRae Shale, ~2.5 Ga), RHDH2a (n=2; Carrawine Dolomite and Jeerinah Fm, ~2.6 Ga), WRL1 (n=3; Wittenoom Fm, Marra Mamba Iron Formation, and Jeerinah Fm, ~2.6 Ga), and SV1 (n=1; Tumbiana Fm, ~2.7 Ga) drill cores, each previously analyzed for bulk organic carbon isotope composition, yielded 100 new, in situ data from Neoarchean sedimentary OM. In these samples, δ13C varies between -53.1 and -28.3% and offsets between in situ and bulk compositions range from -8.3 to 18.8%. In some cases, isotopic composition and mode of occurrence (e.g. morphology and mineral associations) are statistically correlated, enabling the identification of distinct reservoirs of OM. Our results support previous evidence for aerobiosis and depth gradients of oxidation in Neoarchean environments driven by photosynthesis and methane metabolism. The relevance of these findings to questions of bio- and syngenicity as well as the alteration history of this OM and similar, previously reported Archean OM will be discussed.

  4. Geostable molecules and the Late Archean 'Whiff of Oxygen'

    Science.gov (United States)

    Summons, R. E.; Illing, C. J.; Oduro, H. D.; French, K. L.; Ono, S.; Hallmann, C.; Strauss, H.

    2012-12-01

    exhibits a 'MIF' signal that is significantly amplified compared to co-occurring pyrite sulfur. Limited isotopic exchange between the organic and inorganic sulfur pools suggests Archean origin of these organic sulfur compounds. We also report new results from the 2012 Agouron Pilbara drilling project. Anbar A.D. et al. A whiff of oxygen before the great oxidation event. Science 317, 1903-1906. (2007). Bosak T. et al., Morphological record of oxygenic photosynthesis in conical stromatolites. Proc. Natl. Acad. Sci. USA 106:10939-10943 (2009). Kopp, R.E. et al.,The Paleoproterozoic snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis. Proc. Natl. Acad. Sci. USA 102: 11131-11136 (2005). Waldbauer J.R. et al., Late Archean molecular fossils from the Transvaal Supergroup record the antiquity of microbial diversity and aerobiosis. Precambrian Research 169, 28-47 (2008). Waldbauer J.R. et al., 2011. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life. Proceedings of the National Academy of Sciences (USA) 108, 13409-13414

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

    Directory of Open Access Journals (Sweden)

    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

  6. Aerobic stability of triticale silage in single culture or in mixtures with oat and/or legumes Estabilidade aeróbia de silagens de triticale em cultivo exclusivo ou em misturas com aveia e/ou leguminosas

    Directory of Open Access Journals (Sweden)

    Valter Harry Bumbieris Junior

    2010-11-01

    Full Text Available The objective of the present study was to evaluate the aerobic stability and losses during the fermentation process of triticale silages in single crop or in mixtures with oats and/or legumes. The following crops were used for silage production: triticale (X. Triticosecale Wittimack, triticale intercropped with forage pea (Pisum arvense and triticale intercropped with oats (Avena strigosa Schreb, forage pea and vetch (Vicia sativa. The dry matter content and its recovery did not differ among the silages. Buffer capacity was higher for tricale silage intercropped with oats, forage pea and vetch(88.67 m eq. NaOH/100 g DM followed by triticale intercropped with forage pea (80.80 m eq. NaOH/100 g DM. Electric conductivity values were higher in the intercropped triticale silages. Triticale silage presented the lowest temperatures observed in the silos, and the silages of intercropped triticale silages presented higher heat retention and higher pH values. Silage of triticale intercropped with oats and legumes presented lower aerobic stability but it did not reduce the aerobic stability of the total feed. Dry matter recovery during storage and in stability evaluations in aerobiosis is similar among the silages.O objetivo neste trabalho foi avaliar a estabilidade aeróbia e as perdas durante o processo de fermentação de silagens de triticale em cultivo exclusivo ou em misturas com aveia e/ou leguminosas. As culturas utilizadas para produção das silagens foram: triticale (X. Triticosecale Wittimack; triticale em consórcio com ervilha-forrageira (Pisum arvense; e triticale em consórcio com aveia (Avena strigosa Schreb, ervilha-forrageira e ervilhaca (Vicia sativa. O teor de matéria seca e a recuperação de matéria seca não diferiram entre as silagens. A capacidade tampão foi maior para a silagem de triticale cultivado em consórcio com aveia, ervilha-forrageira e ervilhaca (88,67 m eq. NaOH/100 g de MS, seguida da silagem de triticale cultivado