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Sample records for denitrifying enrichment cultures

  1. Enrichment of denitrifying methane-oxidizing microorganisms using up-flow continuous reactors and batch cultures.

    Directory of Open Access Journals (Sweden)

    Masashi Hatamoto

    Full Text Available Denitrifying anaerobic methane oxidizing (DAMO microorganisms were enriched from paddy field soils using continuous-flow and batch cultures fed with nitrate or nitrite as a sole electron acceptor. After several months of cultivation, the continuous-flow cultures using nitrite showed remarkable simultaneous methane oxidation and nitrite reduction and DAMO bacteria belonging to phylum NC10 were enriched. A maximum volumetric nitrite consumption rate of 70.4±3.4 mg-N·L(-1·day(-1 was achieved with very short hydraulic retention time of 2.1 hour. In the culture, about 68% of total microbial cells were bacteria and no archaeal cells were detected by fluorescence in situ hybridization. In the nitrate-fed continuous-flow cultures, 58% of total microbial cells were bacteria while archaeal cells accounted for 7% of total cell numbers. Phylogenetic analysis of pmoA gene sequence showed that enriched DAMO bacteria in the continuous-flow cultivation had over 98% sequence similarity to DAMO bacteria in the inoculum. In contrast, for batch culture, the enriched pmoA gene sequences had 89-91% sequence similarity to DAMO bacteria in the inoculum. These results indicate that electron acceptor and cultivation method strongly affect the microbial community structures of DAMO consortia.

  2. Metagenomic analysis of denitrifying wastewater enrichment cultures able to transform the explosive, 3-nitro-1,2,4-triazol-5-one (NTO).

    Science.gov (United States)

    Eberly, Jed O; Indest, Karl J; Hancock, Dawn E; Jung, Carina M; Crocker, Fiona H

    2016-06-01

    Removal of 3-nitro-1,2,4-triazol-5-one (NTO) was investigated in conjunction with heterotrophic and autotrophic denitrifying growth conditions by a microbial consortium from a wastewater treatment plant. Microcosms were supplemented with molasses, methanol, or thiosulfate. Cultures were passaged twice by transferring 10 % of the culture volume to fresh media on days 11 and 21. Rates of NTO removal were 18.71 ± 0.65, 9.04 ± 2.61, and 4.34 ± 2.72 mg/L/day while rates of nitrate removal were 20.08 ± 1.13, 21.58 ± 1.20, and 24.84 ± 1.26 mg/L/day, respectively, for molasses, methanol, or thiosulfate. Metagenomic analysis showed that Proteobacteria and Firmicutes were the major phyla in the microbial communities. In molasses supplemented cultures, the community profile at the family level changed over time with Pseudomonadaceae the most abundant (67.4 %) at day 11, Clostridiaceae (65.7 %) at day 21, and Sporolactobacillaceae (35.4 %) and Clostridiaceae (41.0 %) at day 29. Pseudomonadaceae was the dominant family in methanol and thiosulfate supplemented cultures from day 21 to 29 with 76.6 and 81.6 % relative abundance, respectively. PMID:27033535

  3. Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kampman, Christel, E-mail: christel.kampman@wur.nl [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands); Hendrickx, Tim L.G. [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands); Luesken, Francisca A.; Alen, Theo A. van; Op den Camp, Huub J.M.; Jetten, Mike S.M. [Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Zeeman, Grietje; Buisman, Cees J.N.; Temmink, Hardy [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer A new concept for low-temperature anaerobic sewage treatment is proposed. Black-Right-Pointing-Pointer In this concept, denitrification and methane oxidation are performed by Methylomirabilis oxyfera. Black-Right-Pointing-Pointer The bacteria were enriched from fresh water sediment using sequencing fed-batch reactors. Black-Right-Pointing-Pointer The volumetric consumption rate has to be increased by an order of magnitude for practical application. Black-Right-Pointing-Pointer Further research should focus on systems with improved biomass retention. - Abstract: Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to 'Candidatus Methylomirabilis oxyfera' were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO{sub 2}{sup -}-N/L d (using synthetic medium) and 37.8 mg NO{sub 2}{sup -}-N/L d (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass

  4. Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

    International Nuclear Information System (INIS)

    Highlights: ► A new concept for low-temperature anaerobic sewage treatment is proposed. ► In this concept, denitrification and methane oxidation are performed by Methylomirabilis oxyfera. ► The bacteria were enriched from fresh water sediment using sequencing fed-batch reactors. ► The volumetric consumption rate has to be increased by an order of magnitude for practical application. ► Further research should focus on systems with improved biomass retention. - Abstract: Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to ‘Candidatus Methylomirabilis oxyfera’ were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO2−-N/L d (using synthetic medium) and 37.8 mg NO2−-N/L d (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass retention.

  5. Enrichment of denitrifying methanotrophic bacteria from Taihu sediments by a membrane biofilm bioreactor at ambient temperature.

    Science.gov (United States)

    Wang, Shenghui; Wu, Qing; Lei, Ting; Liang, Peng; Huang, Xia

    2016-03-01

    Denitrification coupled to anaerobic methane oxidation is a recently discovered process performed by bacteria affiliated to the NC10 phylum. These microorganisms could play important roles in the energy-efficient way of anaerobic wastewater treatment where residual dissolved methane might be removed at the expense of nitrate or nitrite. The difficulty to enrich these microorganisms due to a slow growth rate, especially at low temperatures, limited its application in engineering field. In this study, an NC10 bacteria community was enriched from Taihu sediments by a membrane biofilm bioreactor at ambient temperature of 10-25 °C. After 13 months enrichment, the maximum denitrification rate of the enriched culture reached 0.54 mM day(-1) for nitrate and 1.06 mM day(-1) for nitrite. Anaerobic methane oxidation coupled denitrification was estimated from the (13)C-labeled CO2 ((13)CO2) production during batch incubations with (13)CH4. Furthermore, analysis of 16S rRNA genes clone library confirmed the presence of NC10 phylum bacteria and fluorescence in situ hybridization showed that NC10 bacteria dominated the reactor. All of the results indicated the NC10 bacteria community was competitive in terms of treating nitrate-contaminated water or wastewater under natural conditions. PMID:26578374

  6. Evaluation of nitrate removal by continuous culturing of an aerobic denitrifying bacterium, Paracoccus pantotrophus.

    Science.gov (United States)

    Hasegawa-Kurisu, K; Otani, Y; Hanaki, K

    2006-01-01

    Nitrate removal under aerobic conditions was investigated using pure cultures of Paracoccus pantotrophus, which is a well-known aerobic-denitrifying (AD) bacterium. When a high concentration of cultures with a high carbon/nitrogen (C/N) ratio was preserved at the beginning of batch experiments, subsequently added nitrate was completely removed. When continuous culturing was perpetuated, a high nitrate removal rate (66.5%) was observed on day 4 post-culture, although gradual decreases in AD ability with time were observed. The attenuation in AD ability was probably caused by carbon limitation, because when carbon concentration of inflow water was doubled, nitrate removal efficiency improved from 18.1% to 59.6%. Bacterial community analysis using the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method showed that P. pantotrophus disappeared in the suspended medium on day 8 post-culture, whereas other bacterial communities dominated by Acidovorax sp. appeared. Interestingly, this replaced bacterial community also showed AD ability. As P. pantotrophus was detected as attached colonies around the membrane and bottom of the reactor, this bacterium can therefore be introduced in a fixed form for treatment of wastewater containing nitrate with a high C/N ratio. PMID:17163031

  7. Operation of three parallel AN/AO processes to enrich denitrifying phosphorus removing bacteria for low strength wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    XIA Si-qing; LIU Hong-bo

    2006-01-01

    Three parallel anaerobic-anoxic/anaerobic-aerobic (AN/AO) processes were developed to enrich denitrifying phosphorus removal bacteria (DPB) for low strength wastewater treatment. The main body of the parallel AN/AO process consists of an AN(anaerobic-anoxic) process and an AO (anaerobic-aerobic) process. In the AO process, the common phosphorus accumulating organisms (PAOs) was dominate, while in the AN process, DPB was dominate. The volume of anaerobic zone(Vana):anoxic zone(Vano):aerobic zone (Vaer) for the parallel AN/AO process is 1:1:1 in contrast with a Vana:Vaer and Vano,:Vaer of 1:2 and 1:4 for a traditional biological nutrient removal process (BNR). Process 3 excels in the 3 processes on the basis of COD, TN and TP removal. For 4 month operation, the effluent COD concentration of process 3 did not exceed 60 mg/L; the effluent TN concentration of process 3 was lower than 15 mg/L; and the effluent TP concentration of process 3 was lower than 1 mg/L.

  8. Isolation and denitrification characteristic of an aerobic denitrifier

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dan-dan; MA Fang; WANG Hong-yu; DONG Shuang-shi; WANG Ai-jie

    2006-01-01

    Aerobic denitrifiers were enriched by activated sludge cultivation method. By this way, 105 strains were isolated from the activated sludge and 25 strains were confirmed to be capable of obtaining energy by deoxidization of nitrate to nitrogen gas under aerobic condition. The characteristic of one denitrifier, Pseudomonas chloritidismutans strain, was particularly studied due to its higher nitrogen removal rate. It was found that Pseudomonas chloritidismutans can use nitrite, nitrate and oxygen for aerobic respiration in liquid medium, and the pH increased and ORP decreased by activated denitrifier. When they used nitrite or nitrate for respiration, nitrogen removal effect was high and nitrite could be reduced more efficiently than nitrate. Denitrification process was accomplished faster when both nitrite and nitrate existed in the medium compared to each of which existed alone. Particularly, at denitrifying activity, the nitrogen removal rate of strain was not affected by the DO concentration in the culture media.

  9. Enrichment of high ammonia tolerant methanogenic culture

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Proietti, Nicolas;

    of the current study was to isolate and identify methanogenic cultures tolerant to high ammonia concentrations. A mixed methanogenic population was stepwise exposed to ammonia concentrations (1 to 9.26 g NH4+-N L-1) during an enrichment process with successive batch cultivations. The methanogenic population...... was derived from a full scale biogas reactor (Hashøj, Denmark), fed with 75% animal manure and 25% food industries organic waste. Basal anaerobic medium was used for the enrichment along with sodium acetate (1 g HAc L-1) as a carbon source. Fluorescence insitu hybridization (FISH) was used to determine...... microbial community composition. The outcome of the enrichment process was a mesophilic aceticlastic methanogenic enriched culture able to withstand high ammonia loads and utilize acetate and form methane stoichiometrically. FISH analysis showed that the methanogens of the enriched culture belonged...

  10. Benzene and ethylbenzene removal by denitrifying culture in a horizontal fixed bed anaerobic reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gusmao, V.R.; Chinalia, F.A.; Sakamoto, I.K.; Varesche [Univ. de Sao Paulo (Brazil). Dept. de Hidraulica e Saneamento; Thiemann, O.H. [Univ. de Sao Paulo (Brazil). Inst. de Fisica de Sao Carlos

    2004-07-01

    Benzene, ethylbenzene, toluene, and xylene are toxic and are important constituents of gasoline and other petroleum fuels. These compounds are potential health hazards because of their high solubility and hence their ability to contaminate groundwater. Anaerobic immobilized biomass is a way of treating wastewater contaminated with the above compounds. The performance of a specially adapted biofilm is critical in the viability of this idea. In this investigation, an especially adapted biofilm was obtained using a denitrifying bacterial strain isolated from a slaughterhouse wastewater treatment plant. The strain was cultured in a liquid medium with added ethanol, nitrate, ethylbenzene, and benzene. To assess the viability of the strain for the purposes of degradation of ethylbenzene, and benzene two separate horizontal reactors were prepared with polyurethane foam in order to immobilize the biomass. Various concentrations of the two compounds were admitted. At high concentrations chemical oxygen demand decreased dramatically and benzene and ethylbenzene removal almost 100 per cent. DNA sequencing of the biofilm showed that Paracoccus versutus was the dominant species in the ethylbenzene reactor. 7 refs., 6 figs.

  11. Distribution of baroduric, psychrotrophic and culturable nitrifying and denitrifying bacteria in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; PradeepRam, A.S.; Nair, S.; Nath, B.N.; Chandramohan, D.

    ) dry weight sediment and formed 0.21 and 4.30% of the total counts. Unusually high number of nitrifiers comprising of 40% of the total bacterial population have been encountered in one of the cores, namely CIB 16. Denitrifying bacterial population...

  12. Distinctive denitrifying capabilities lead to differences in N2O production by denitrifying polyphosphate accumulating organisms and denitrifying glycogen accumulating organisms.

    Science.gov (United States)

    Ribera-Guardia, Anna; Marques, Ricardo; Arangio, Corrado; Carvalheira, Monica; Oehmen, Adrian; Pijuan, Maite

    2016-11-01

    This study aims at investigating the denitrification kinetics in two separate enriched cultures of denitrifying polyphosphate accumulating organisms (dPAO) and denitrifying glycogen accumulating organisms (dGAO) and compare their N2O accumulation potential under different conditions. Two sequencing batch reactors were inoculated to develop dPAO and dGAO enriched microbial communities separately. Seven batch tests with different combinations of electron acceptors (nitrate, nitrite and/or nitrous oxide) were carried out with the enriched biomass from both reactors. Results indicate that in almost all batch tests, N2O accumulated for both cultures, however dPAOs showed a higher denitrification capacity compared to dGAOs due to their higher nitrogen oxides reduction rates. Additionally, the effect of the simultaneous presence of several electron acceptors in the reduction rates of the different nitrogen oxides was also assessed in dPAOs and dGAOs. PMID:27479801

  13. Mineralization of Trichloroethylene by Heterotrophic Enrichment Cultures

    OpenAIRE

    Fliermans, C. B.; Phelps, T. J.; Ringelberg, D.; Mikell, A. T.; White, D. C.

    1988-01-01

    Microbial consortia capable of aerobically degrading more than 99% of exogenous trichloroethylene (TCE) (50 mg/liter) were collected from TCE-contaminated subsurface sediments and grown in enrichment cultures. TCE at concentrations greater than 300 mg/liter was not degraded, nor was TCE used by the consortia as a sole energy source. Energy sources which permitted growth included tryptone-yeast extract, methanol, methane, and propane. The optimum temperature range for growth and subsequent TCE...

  14. 21 CFR 866.2330 - Enriched culture medium.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Enriched culture medium. 866.2330 Section 866.2330...) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2330 Enriched culture medium. (a) Identification. An enriched culture medium is a device that consists primarily of liquid...

  15. Comparison of aerobic denitrifying activity among three cultural species with various carbon sources.

    Science.gov (United States)

    Otani, Y; Hasegawa, K; Hanaki, K

    2004-01-01

    Abilities of three aerobic denitrifiers such as Alcaligenes faecalis, Microvirgula aerodenitrificans and Paracoccus pantotrophus were compared from the viewpoints of nitrate removal efficiency and organic matter utilization. First, the effect of carbon source was investigated. Although nitrate reduction was observed in all strains under aerobic conditions, a change of carbon source considerably affected the denitrification ability. In the case of P. pantotrophus, nitrate and nitrite were completely removed in three days under sodium acetate or leucine as a carbon source. In the case of A. faecalis, sufficient nitrate removal was observed only when sodium acetate or ethanol was added. P. pantotrophus and A. faecalis showed a higher ability of nitrate removal than that of M. aerodenitrificans. Therefore, P. pantotrophus was selected in order to investigate the effects of concentration and repetitive addition of carbon. Sodium acetate was used as a sole carbon source. Nitrate was not reduced when the carbon concentration was below 500 mgC/L. However, when carbon source was added repeatedly, nitrate was reduced under 100 mgC/L after the optical density of the bacterium reached above 1.0. This result indicated that a high enough level of bacterial density was necessary to express aerobic denitrification activity. PMID:15566182

  16. Highly enriched Betaproteobacteria growing anaerobically with p-xylene and nitrate

    DEFF Research Database (Denmark)

    Rotaru, Amelia-Elena; Probian, Christina; Wilkes, Heinz;

    2010-01-01

    The identity of the microorganisms capable of anaerobic p-xylene degradation under denitrifying conditions is hitherto unknown. Here, we report highly enriched cultures of freshwater denitrifying bacteria that grow anaerobically with p-xylene as the sole organic carbon source and electron donor. ....... Long curved rods, with 95% 16S rRNA gene sequence identity to Denitratisoma oestradiolicum, dominated the enrichment cultures (>91% of all cells), as detected by phylotype-specific probes. These Rhodocyclaceae microorganisms were distantly related to other denitrifying hydrocarbon...

  17. [Reductive Dechlorination of Trichloroethylene by Benzoate-Enriched Anaerobic Cultures].

    Science.gov (United States)

    Li, Jiang-wei; Yang, Xiao-yong; Hu, An-yi; Yu, Chang-ping

    2015-10-01

    Gas chromatography was used to monitor the reductive dechlorination of trichloroethylene (TCE) by anaerobic enrichment cultures with benzoate as the sole carbon source. The 454 pyrosequencing technique was used to investigate the microbial community and the real-time quantitative PCR was used to quantify the gene copies of Dehalococcoides spp. (DHC). The results showed that TCE was dechlorinated to vinyl chloride along with the formation of methane in 94 days. The anaerobic enrichment cultures exhibited a high diversity, which were classified into 16 phyla, 33 classes, 52 orders, 88 families and 129 genera, while 51.2% of them belonged to unclassified group, which inferred that there were a large portion of bacteria with unknown functional in this system. Degradation of TCE was accomplished by reductive dechlorinating and other functional populations, and the DHC which carried tceA gene could be the dominant reductive dechlorinating populations in the system. PMID:26841609

  18. Culture enriched molecular profiling of the cystic fibrosis airway microbiome.

    Science.gov (United States)

    Sibley, Christopher D; Grinwis, Margot E; Field, Tyler R; Eshaghurshan, Christina S; Faria, Monica M; Dowd, Scot E; Parkins, Michael D; Rabin, Harvey R; Surette, Michael G

    2011-01-01

    The microbiome of the respiratory tract, including the nasopharyngeal and oropharyngeal microbiota, is a dynamic community of microorganisms that is highly diverse. The cystic fibrosis (CF) airway microbiome refers to the polymicrobial communities present in the lower airways of CF patients. It is comprised of chronic opportunistic pathogens (such as Pseudomonas aeruginosa) and a variety of organisms derived mostly from the normal microbiota of the upper respiratory tract. The complexity of these communities has been inferred primarily from culture independent molecular profiling. As with most microbial communities it is generally assumed that most of the organisms present are not readily cultured. Our culture collection generated using more extensive cultivation approaches, reveals a more complex microbial community than that obtained by conventional CF culture methods. To directly evaluate the cultivability of the airway microbiome, we examined six samples in depth using culture-enriched molecular profiling which combines culture-based methods with the molecular profiling methods of terminal restriction fragment length polymorphisms and 16S rRNA gene sequencing. We demonstrate that combining culture-dependent and culture-independent approaches enhances the sensitivity of either approach alone. Our techniques were able to cultivate 43 of the 48 families detected by deep sequencing; the five families recovered solely by culture-independent approaches were all present at very low abundance (<0.002% total reads). 46% of the molecular signatures detected by culture from the six patients were only identified in an anaerobic environment, suggesting that a large proportion of the cultured airway community is composed of obligate anaerobes. Most significantly, using 20 growth conditions per specimen, half of which included anaerobic cultivation and extended incubation times we demonstrate that the majority of bacteria present can be cultured.

  19. Culture enriched molecular profiling of the cystic fibrosis airway microbiome.

    Directory of Open Access Journals (Sweden)

    Christopher D Sibley

    Full Text Available The microbiome of the respiratory tract, including the nasopharyngeal and oropharyngeal microbiota, is a dynamic community of microorganisms that is highly diverse. The cystic fibrosis (CF airway microbiome refers to the polymicrobial communities present in the lower airways of CF patients. It is comprised of chronic opportunistic pathogens (such as Pseudomonas aeruginosa and a variety of organisms derived mostly from the normal microbiota of the upper respiratory tract. The complexity of these communities has been inferred primarily from culture independent molecular profiling. As with most microbial communities it is generally assumed that most of the organisms present are not readily cultured. Our culture collection generated using more extensive cultivation approaches, reveals a more complex microbial community than that obtained by conventional CF culture methods. To directly evaluate the cultivability of the airway microbiome, we examined six samples in depth using culture-enriched molecular profiling which combines culture-based methods with the molecular profiling methods of terminal restriction fragment length polymorphisms and 16S rRNA gene sequencing. We demonstrate that combining culture-dependent and culture-independent approaches enhances the sensitivity of either approach alone. Our techniques were able to cultivate 43 of the 48 families detected by deep sequencing; the five families recovered solely by culture-independent approaches were all present at very low abundance (<0.002% total reads. 46% of the molecular signatures detected by culture from the six patients were only identified in an anaerobic environment, suggesting that a large proportion of the cultured airway community is composed of obligate anaerobes. Most significantly, using 20 growth conditions per specimen, half of which included anaerobic cultivation and extended incubation times we demonstrate that the majority of bacteria present can be cultured.

  20. Respiration and respiratory enzyme activity in aerobic and anaerobic cultures of the marine denitrifying bacterium, Pseudomonas perfectomarinus

    Science.gov (United States)

    Packard, T. T.; Garfield, P. C.; Martinez, R.

    1983-03-01

    Oxygen consumption, nitrate reduction, respiratory electron transport activity, and nitrate reductase activity were measured in aerobic and anaerobic cultures of the marine bacterium, Pseudomonas perfectomarinus. The respiratory electron transport activity was closely correlated with oxygen consumption ( r = 0.98) in aerobic cultures and nearly as well correlated with nitrate reductase activity ( r = 0.91) and nitrate reduction ( r = 0.85) in anaerobic cultures. It was also well correlated with biomass in both aerobic ( r = 0.99) and anaerobic ( r = 0.94) cultures supporting the use of tetrazolium reduction as an index of living biomass. Time courses of nitrate and nitrate in the anaerobic cultures demonstrated that at nitrate concentrations above 1 mM, denitrification proceeds stepwise. Time courses of pH in anaerobic cultures revealed a rise from 7 to 8.5 during nitrite reduction indicating net proton utilization. This proton utilization is predicted by the stoichiometry of denitrification. Although the experiments were not under 'simulated in situ' conditions, the results are relevant to studies of denitrification, to bacterial ATP production, and to the respiratory activity of marine plankton in the ocean.

  1. Effect of various sources of organic carbon and high nitrite and nitrate concentrations on the selection of denitrifying bacteria. II. Continuous cultures in packed bed reactors.

    Science.gov (United States)

    Błaszczyk, M

    1983-01-01

    The effect of different organic compounds, nitrites and nitrates at the concentration of 1,000 mg N/l on the quantitative and strain-specific selection of denitrifying bacteria was determined in anaerobic packed bed reactors. Both the source of carbon and nitrogen form influenced strain specificity and the frequency of occurrence of denitrifying bacteria. The frequency of denitrifying bacteria within packed bed reactor ranged in different media from 11% (glucose and nitrates) to 100% (methanol and ethanol with nitrates). A single species selection was observed in the presence of nitrites within packed bed reactor: Pseudomonas aeruginosa in medium with acetate. Pseudomonas stutzeri in medium with ethanol, Pseudomonas mendocina in medium with methanol and Pseudomonas fluorescens in medium with glucose. When nitrates were present in packed bed reactor, the dominating bacteria were: P. stutzeri in medium with acetate, P. fluorescens in medium with ethanol, Paracoccus denitrificans in medium with methanol and Alcaligenes faecalis in medium with glucose. PMID:6194668

  2. Effect of temperature on denitrifying methanotrophic activity of 'Candidatus Methylomirabilis oxyfera'

    NARCIS (Netherlands)

    Kampman, C.; Piai, L.; Hendrickx, T.L.G.; Temmink, B.G.; Zeeman, G.; Buisman, C.J.N.

    2014-01-01

    The activity of denitrifying methanotrophic bacteria at 11-30 degrees C was assessed in short-term experiments. The aim was to determine the feasibility of applying denitrifying methanotrophic bacteria in low-temperature anaerobic wastewater treatment. This study showed that biomass enriched at 21 d

  3. Diel vertical variability analysis of denitrifying bacteria abundance in oxygen-enriched irrigation pond%富氧灌溉池塘中反硝化细菌丰度昼夜垂直变化特征分析

    Institute of Scientific and Technical Information of China (English)

    易能; 邸攀攀; 王岩; 张振华; 刘新红; 张力; 严少华; 高岩

    2015-01-01

    activity of microscopic algae in the pond, the concentrations of DO concentration increased during the daylight and decreased during night. Diurnal variation of pH was positively (P<0.001) correlated with DO concentration in the vertical profile of the water column in the pond, with pH in the ponds also followed the diurnal cycle of sunlight intensity. The abundances ofnirK,nirK, andnosZ genes were strongly affected by the diurnal distribution patterns of pH and DO concentrations along vertical profile of water,with significant higher abundance during the daytime while lower abundance during the night at all the different water depths. Heterogeneous distribution of denitrifying bacteria abundances along the vertical profile of sewage water column were also demonstrated, with the least abundances in the bottom water (150-170 cm) and the highest in the surface water column (10-30 cm). Although thenirK andnirS are functionally equivalent, denitrifying bacteria harboring either nitrite reductase seem to be likely not under the same community assembly rules. The abundance of nirS gene was always greater than that ofnirK gene in all water samples, suggesting that the sewage water in this study was more suitable for the growth ofnirS-type denitrifying bacteria. This speculation was consistent with previously identified habitat preferences ofnirS- andnirK-gene bearing organisms. The abundances ofnirK,nirS, andnosZ genes were significantly correlated with DO concentration and pH (P<0.01). These results demonstrated that the diel vertical variability of the water physical and chemical parameters, especially DO concentrations, in the oxygen-enriched sewage water could affect the diel vertical distribution patterns ofnirK,nirS, andnosZ genes abundances. This may suggest that a large number of aerobic denitrifying bacteria could have extensively developed in sewage water under the condition of high DO concentrations during the process of conservation in the pond. These aerobic

  4. A strict anaerobic extreme thermophilic hydrogen-producing culture enriched from digested household waste

    DEFF Research Database (Denmark)

    Karakashev, Dimitar Borisov; Kotay, Shireen Meher; Trably, Eric;

    2009-01-01

    The aim of this study was to enrich, characterize and identify strict anaerobic extreme thermophilic hydrogen (H-2) producers from digested household solid wastes. A strict anaerobic extreme thermophilic H-2 producing bacterial culture was enriched from a lab-scale digester treating household...... to the genera Bacillus and Clostridium. Relative abundance of the culture members, assessed by fluorescence in situ hybridization, were 87 +/- 5% and 13 +/- 5% for Bacillus and Clostridium, respectively. An extreme thermophilic, strict anaerobic, mixed microbial culture with H-2-producing potential was enriched...

  5. 中空纤维膜生物反应器富集反硝化厌氧甲烷氧化菌群的研究%Enrichment of denitrifying anaerobic methane oxidation microbes in a hollow fiber membrane bioreactor

    Institute of Scientific and Technical Information of China (English)

    钱祝胜; 付亮; 丁静; 丁兆威; 曾建雄

    2014-01-01

    反硝化厌氧甲烷氧化(DAMO)过程可以由一种称为Methylomirabilis oxy f era的DAMO细菌在有或者没有DAMO古菌下完成.已经报道的DAMO过程的菌群富集时间长(一般需要7~18月),且DAMO体系反硝化速率低.利用中空纤维膜生物反应器(HFMB)提高甲烷的传质来试图实现快速启动DAMO反应,结果发现HFMB在不到3个月时间内就表现出DAMO反应,其反硝化速率达到50 mg · L -1· d-1硝酸盐氮.二代测序显示,HFMB中微生物以 A naerolineaceae , A zospira ,CL500‐3占绝对优势,分别为39.08%,13.68%和11.54%,而 DAMO 细菌(Methylomirabilis)和与厌氧甲烷氧化有关的古菌 Methanosarcina分别占0.02%和0.13%,因此推测在HFMB中DAMO过程是由一群新的菌群主导完成.%The process of denitrifying anaerobic methane oxidation (DAMO) can be catalyzed by DAMO bacteria called Methylomirabilis oxyfera with or without the involvement of DAMO archaea .Enrichment of DAMO microbes often takes a long time (7 ~ 18 months) to show a faint denitrification function in reported DAMO process .This study aimed to fast enrich DAMO microbes in a hollow fiber membrane bioreactor (HFMB) as the special structure of hollow fiber can increase the mass transfer of methane .It is found that HFMB shows DAMO activity in a shorter period of time (<3 months) and the denitrification rate reaches 50 mg · L -1 · d-1 NO3 -‐N .The next‐generation DNA sequencing on the microbes in HFMB shows that Anaerolineaceae ,Azospira,CL500‐3 are dominant with 39.08% ,13.68% and 11.54% of the total microbes , respectively . Meanwhile , Methylomirabilis (DAMO bacteria ) and Methanosarcina (DAMO archaea) are only 0.02% and 0.13% ,respectively .It is speculated therefore that the DAMO process in HFMB may have been catalyzed by other microbes that are different from the known DAMO microbes .

  6. Co-enriching microflora associated with culture based methods to detect Salmonella from tomato phyllosphere.

    Science.gov (United States)

    Ottesen, Andrea R; Gonzalez, Antonio; Bell, Rebecca; Arce, Caroline; Rideout, Steven; Allard, Marc; Evans, Peter; Strain, Errol; Musser, Steven; Knight, Rob; Brown, Eric; Pettengill, James B

    2013-01-01

    The ability to detect a specific organism from a complex environment is vitally important to many fields of public health, including food safety. For example, tomatoes have been implicated numerous times as vehicles of foodborne outbreaks due to strains of Salmonella but few studies have ever recovered Salmonella from a tomato phyllosphere environment. Precision of culturing techniques that target agents associated with outbreaks depend on numerous factors. One important factor to better understand is which species co-enrich during enrichment procedures and how microbial dynamics may impede or enhance detection of target pathogens. We used a shotgun sequence approach to describe taxa associated with samples pre-enrichment and throughout the enrichment steps of the Bacteriological Analytical Manual's (BAM) protocol for detection of Salmonella from environmental tomato samples. Recent work has shown that during efforts to enrich Salmonella (Proteobacteria) from tomato field samples, Firmicute genera are also co-enriched and at least one co-enriching Firmicute genus (Paenibacillus sp.) can inhibit and even kills strains of Salmonella. Here we provide a baseline description of microflora that co-culture during detection efforts and the utility of a bioinformatic approach to detect specific taxa from metagenomic sequence data. We observed that uncultured samples clustered together with distinct taxonomic profiles relative to the three cultured treatments (Universal Pre-enrichment broth (UPB), Tetrathionate (TT), and Rappaport-Vassiliadis (RV)). There was little consistency among samples exposed to the same culturing medias, suggesting significant microbial differences in starting matrices or stochasticity associated with enrichment processes. Interestingly, Paenibacillus sp. (Salmonella inhibitor) was significantly enriched from uncultured to cultured (UPB) samples. Also of interest was the sequence based identification of a number of sequences as Salmonella despite

  7. Atrazine and its metabolites degradation in mineral salts medium and soil using an enrichment culture.

    Science.gov (United States)

    Kumar, Anup; Singh, Neera

    2016-03-01

    An atrazine-degrading enrichment culture was used to study degradation of atrazine metabolites viz. hydroxyatrazine, deethylatrazine, and deisopropylatrazine in mineral salts medium. Results suggested that the enrichment culture was able to degrade only hydroxyatrazine, and it was used as the sole source of carbon and nitrogen. Hydroxyatrazine degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as the additional sources of carbon and nitrogen, respectively. The enrichment culture could degrade high concentrations of atrazine (up to 110 μg/mL) in mineral salts medium, and neutral pH was optimum for atrazine degradation. Further, except in an acidic soil, enrichment culture was able to degrade atrazine in three soil types having different physico-chemical properties. Raising the pH of acidic soil to neutral or alkaline enabled the enrichment culture to degrade atrazine suggesting that acidic pH inhibited atrazine-degrading ability. The study suggested that the enrichment culture can be successfully utilized to achieve complete degradation of atrazine and its persistent metabolite hydroxyatrazine in the contaminated soil and water.

  8. Enrichment methodology to increase the positivity of cultures from body fluids

    Directory of Open Access Journals (Sweden)

    Alessandra Valle Daur

    2006-12-01

    Full Text Available Isolation and identification of etiological agents found in body fluids can be of critical importance for the recovery of patients suffering from potentially-severe infections, which are often followed by serious sequels. Eighty-two samples of different body fluids were analyzed using two different methods: (1 the conventional culture method (agar plating and (2 the enrichment culture technique, using the Bact/Alert® blood culture bottle. The number of positive cultures increased on average from 9.7% to 23.1% with the enrichment culture technique. Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus were the most frequently isolated bacteria. The enrichment method could provide a more accurate means the identifying etiological agents.

  9. Co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron(III-reducing enrichment culture

    Directory of Open Access Journals (Sweden)

    Shiling eZheng

    2015-09-01

    Full Text Available Methanosaeta harundinacea and Methanosarcina barkeri, known as classic acetoclastic methanogens, are capable of directly accepting electrons from Geobacter metallireducens for the reduction of carbon dioxide to methane, having been revealed as direct interspecies electron transfer (DIET in the laboratory co-cultures. However, whether their co-occurrences are ubiquitous in the iron (III-reducing environments and the other species of acetoclastic methanogens such as Methanosarcina mazei are capable of DIET are still unknown. Instead of initiating the co-cultures with pure cultures, two-step cultivation was employed to selectively enrich iron (III-reducing microorganisms in a coastal gold mining river, Jiehe River, with rich iron content in the sediments. First, iron (III reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III oxides as electron acceptor and acetate as electron donor. High-throughput Illumina sequencing, terminal restriction fragment length polymorphism (T-RFLP and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures actively contained the bacteria belong to Geobacteraceae and Bacilli, exclusively dominated by the archaea belong to Methanosarcinaceae. Second, the enrichment cultures including methanogens and Geobacteraceae were transferred with ethanol as alternative electron donor. Remarkably, aggregates were successively formed in the enrichments after three transfers. The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III-reducing enrichment culture. Furthermore, the aggregates, as close physical contact, formed in the enrichment culture, indicate that DIET could be a possible option for interspecies electron transfer in the aggregates.

  10. Enrichment culture of marine anaerobic ammonium oxidation (anammox) bacteria

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jie

    2016-01-01

    The present study investigates the enrichment of anaerobic ammonium oxidation (anammox) bacteria in the marine environment using sediment samples obtained from the East China Sea and discusses the nitrogen removal efficiency of marine anammox bioreactor. Enrichment of anammox bacteria with simultaneous removal of nitrite and ammonium ions was observed in the Anaerobic Sequencing Batch Reactor under a total nitrogen loading rate of 0.37kg-N m-3day-1. In this study, The nitrogen removal efficiency was up to 80% and the molar-reaction ratio of ammonium, nitrite and nitrate was 1.0:1.22:0.22 which was a little different from a previously reported ratio of 1.0:1.32:0.26 in a freshwater system.

  11. Use of {gamma}-hexachlorocyclohexane as a terminal electron acceptor by an anaerobic enrichment culture

    Energy Technology Data Exchange (ETDEWEB)

    Elango, Vijai, E-mail: velango@g.clemson.edu [Hazardous Substance Research Center/South and Southwest, Louisiana State University, 3221 Patrick Taylor Hall, Baton Rouge, LA 70803 (United States); Kurtz, Harry D. [Department of Genetics and Biochemistry, Clemson University, 100 Jordan Hall, Clemson, SC 29634 (United States); Anderson, Christina; Freedman, David L. [Department of Environmental Engineering and Earth Sciences, Box 340919, Clemson University, Clemson, SC 29634-0919 (United States)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Use of {gamma}-hexachlorocyclohexane as a terminal electron acceptor was demonstrated. Black-Right-Pointing-Pointer H{sub 2} served as the electron donor for an enrichment culture that dechlorinated {gamma}-HCH. Black-Right-Pointing-Pointer H{sub 2} consumption for acetogenesis and methanogenesis stopped in HEPES media. Black-Right-Pointing-Pointer Addition of vancomycin significantly slowed the rate of {gamma}-HCH dechlorination. Black-Right-Pointing-Pointer Previously identified chlororespiring microbes were not detected in the enrichment. - Abstract: The use of {gamma}-hexachlorocyclohexane (HCH) as a terminal electron acceptor via organohalide respiration was demonstrated for the first time with an enrichment culture grown in a sulfate-free HEPES-buffered anaerobic mineral salts medium. The enrichment culture was initially developed with soil and groundwater from an industrial site contaminated with HCH isomers, chlorinated benzenes, and chlorinated ethenes. When hydrogen served as the electron donor, 79-90% of the electron equivalents from hydrogen were used by the enrichment culture for reductive dechlorination of the {gamma}-HCH, which was provided at a saturation concentration of approximately 10 mg/L. Benzene and chlorobenzene were the only volatile transformation products detected, accounting for 25% and 75% of the {gamma}-HCH consumed (on a molar basis), respectively. The enrichment culture remained active with only hydrogen as the electron donor and {gamma}-HCH as the electron acceptor through several transfers to fresh mineral salts medium for more than one year. Addition of vancomycin to the culture significantly slowed the rate of {gamma}-HCH dechlorination, suggesting that a Gram-positive organism is responsible for the reduction of {gamma}-HCH. Analysis of the {gamma}-HCH dechlorinating enrichment culture did not detect any known chlororespiring genera, including Dehalobacter. In bicarbonate-buffered medium

  12. Characteristics of enriched cultures for bio-huff-`n`-puff tests at Jilin oil field

    Energy Technology Data Exchange (ETDEWEB)

    Xiu-Yuan Wang; Gang Dai; Yan-Fen Xue; Shu-Hua Xie [Institute of Microbiology, Beijing (China)] [and others

    1995-12-31

    Three enriched cultures (48, 15a, and 26a), selected from more than 80 soil and water samples, could grow anaerobically in the presence of crude oil at 30{degrees}C and could ferment molasses to gases and organic acids. Oil recovery by culture 48 in the laboratory model experiment was enhanced by 25.2% over the original reserves and by 53.7% over the residual reserves. Enriched culture 48 was composed of at least 4 species belonging to the genera Eubacterium, Fusobacterium, and Bacteroides. This enriched culture was used as inoculum for MEOR field trials at Jilin oil field with satisfactory results. The importance of the role of these isolates in EOR was confirmed by their presence and behavior in the fluids produced from the microbiologically treated reservoir.

  13. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    . The bioaugmentation was performed without pausing the continuous operation of the CSTR reactor and without excluding the ammonia-rich substrate from the feedstock. Thus, bioaugmentation with mixed methanogenic cultures could potentially support the development of an efficient and cost-effective biomethanation process...... of a pure culture, to be used as bioaugmentation inoculum, poses technical difficulties due to the required sterile conditions and the special growing media. On the contrary acclimatized enrichment methanogenic cultures have lower requirements to sterility. In the present study, we used an enriched ammonia...... tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...

  14. Ca2+ enrichment in culture medium potentiates effect of oligonucleotides.

    Science.gov (United States)

    Hori, Shin-Ichiro; Yamamoto, Tsuyoshi; Waki, Reiko; Wada, Shunsuke; Wada, Fumito; Noda, Mio; Obika, Satoshi

    2015-10-30

    Antisense and RNAi-related oligonucleotides have gained attention as laboratory tools and therapeutic agents based on their ability to manipulate biological events in vitro and in vivo. We show that Ca(2+) enrichment of medium (CEM) potentiates the in vitro activity of multiple types of oligonucleotides, independent of their net charge and modifications, in various cells. In addition, CEM reflects in vivo silencing activity more consistently than conventional transfection methods. Microscopic analysis reveals that CEM provides a subcellular localization pattern of oligonucleotides resembling that obtained by unassisted transfection, but with quantitative improvement. Highly monodispersed nanoparticles ~100 nm in size are found in Ca(2+)-enriched serum-containing medium regardless of the presence or absence of oligonucleotides. Transmission electron microscopy analysis reveals that the 100-nm particles are in fact an ensemble of much smaller nanoparticles (ϕ ∼ 15 nm). The presence of these nanoparticles is critical for the efficient uptake of various oligonucleotides. In contrast, CEM is ineffective for plasmids, which are readily transfected via the conventional calcium phosphate method. Collectively, CEM enables a more accurate prediction of the systemic activity of therapeutic oligonucleotides, while enhancing the broad usability of oligonucleotides in the laboratory. PMID:26101258

  15. Ca2+ enrichment in culture medium potentiates effect of oligonucleotides.

    Science.gov (United States)

    Hori, Shin-Ichiro; Yamamoto, Tsuyoshi; Waki, Reiko; Wada, Shunsuke; Wada, Fumito; Noda, Mio; Obika, Satoshi

    2015-10-30

    Antisense and RNAi-related oligonucleotides have gained attention as laboratory tools and therapeutic agents based on their ability to manipulate biological events in vitro and in vivo. We show that Ca(2+) enrichment of medium (CEM) potentiates the in vitro activity of multiple types of oligonucleotides, independent of their net charge and modifications, in various cells. In addition, CEM reflects in vivo silencing activity more consistently than conventional transfection methods. Microscopic analysis reveals that CEM provides a subcellular localization pattern of oligonucleotides resembling that obtained by unassisted transfection, but with quantitative improvement. Highly monodispersed nanoparticles ~100 nm in size are found in Ca(2+)-enriched serum-containing medium regardless of the presence or absence of oligonucleotides. Transmission electron microscopy analysis reveals that the 100-nm particles are in fact an ensemble of much smaller nanoparticles (ϕ ∼ 15 nm). The presence of these nanoparticles is critical for the efficient uptake of various oligonucleotides. In contrast, CEM is ineffective for plasmids, which are readily transfected via the conventional calcium phosphate method. Collectively, CEM enables a more accurate prediction of the systemic activity of therapeutic oligonucleotides, while enhancing the broad usability of oligonucleotides in the laboratory.

  16. Integrated biogas upgrading and hydrogen utilization in an anaerobic reactor containing enriched hydrogenotrophic methanogenic culture

    DEFF Research Database (Denmark)

    Luo, Gang; Angelidaki, Irini

    2012-01-01

    by PCR–DGGE. Nonetheless, they all belonged to the order Methanobacteriales, which can mediate hydrogenotrophic methanogenesis. Biogas upgrading was then tested in a thermophilic anaerobic reactor under various operation conditions. By continuous addition of hydrogen in the biogas reactor, high degree...... the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched hydrogenotrophic methanogens and fed with biogas and hydrogen. Both mesophilic- and thermophilic anaerobic cultures were enriched to convert CO2 to CH4...... by addition of H2. Enrichment at thermophilic temperature (55°C) resulted in CO2 and H2 bioconversion rate of 320 mL CH4/(gVSS h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic- and thermophilic-enriched cultures, as revealed...

  17. Enrichment Culture of Hydrogen Fermentation Microorganisms and Analysis of Microbial Communities

    Science.gov (United States)

    Huang, Xiaoyu; Matsumoto, Akiko; Ohnishi, Akihiro; Sakamoto, Masaru; Fujimoto, Naoshi; Suzuki, Masaharu

    The present study was aimed at enrichment of hydrogen fermentative microflora that can utilize garbage as fermentation substrate. It was shown that stable hydrogen fermentation was performed using enriched microbes from sewage sludge compost. During the enrichment culture, the microflora were analyzed by the FISH method and the PCR-DGGE method. As a result, predominant microbes of hydrogen production were determined to be from the genus Clostridium belonging to a Gram positive Low G+C group. Furthermore, it was supposed that genus Bacillus contributed to the stability of hydrogen productivity from garbage by genus Clostridium. In the batch culture, under pH control at 6.0, it was ascertained that enriched microflora obtained from sewage sludge compost had sufficient hydrogen productivity using garbage, and yielded 2.03mol-H2/mol-hexose. It is supposed that the microflora of sewage sludge compost is effective as inoculum of the hydrogen fermentation system when using garbage as substrate.

  18. Resource recovery from organic waste streams by microbial enrichment cultures

    OpenAIRE

    Tamis, J.

    2015-01-01

    Polyhydroxyalkanoate (PHA) is a natural product that can potentially replace a part of the chemicals and plastics derived from fossil sources. One of the main barriers for market entry of PHA is its relatively high price compared to conventional (fossil) feedstocks. This high price is related to current industrial production methods which are based on the cultivation of pure microbial cultures of a single species that a.o. has to be protected from contaminations from unwanted microorganisms t...

  19. Differential gene expression profiling of enriched human spermatogonia after short- and long-term culture.

    Science.gov (United States)

    Conrad, Sabine; Azizi, Hossein; Hatami, Maryam; Kubista, Mikael; Bonin, Michael; Hennenlotter, Jörg; Renninger, Markus; Skutella, Thomas

    2014-01-01

    This study aimed to provide a molecular signature for enriched adult human stem/progenitor spermatogonia during short-term (differentiation/spermatogenesis pathway were highly expressed in enriched short-term cultured spermatogonia. After long-term culture, a proportion of cells retained and aggravated the "spermatogonial" gene expression profile with the expression of germ and pluripotency-associated genes, while in the majority of long-term cultured cells this molecular profile, typical for the differentiation pathway, was reduced and more genes related to the extracellular matrix production and attachment were expressed. The approach we provide here to study the molecular status of in vitro cultured spermatogonia may be important to optimize the culture conditions and to evaluate the germ cell plasticity in the future.

  20. Differential Gene Expression Profiling of Enriched Human Spermatogonia after Short- and Long-Term Culture

    Directory of Open Access Journals (Sweden)

    Sabine Conrad

    2014-01-01

    Full Text Available This study aimed to provide a molecular signature for enriched adult human stem/progenitor spermatogonia during short-term (<2 weeks and long-term culture (up to more than 14 months in comparison to human testicular fibroblasts and human embryonic stem cells. Human spermatogonia were isolated by CD49f magnetic activated cell sorting and collagen−/laminin+ matrix binding from primary testis cultures obtained from ten adult men. For transcriptomic analysis, single spermatogonia-like cells were collected based on their morphology and dimensions using a micromanipulation system from the enriched germ cell cultures. Immunocytochemical, RT-PCR and microarray analyses revealed that the analyzed populations of cells were distinct at the molecular level. The germ- and pluripotency-associated genes and genes of differentiation/spermatogenesis pathway were highly expressed in enriched short-term cultured spermatogonia. After long-term culture, a proportion of cells retained and aggravated the “spermatogonial” gene expression profile with the expression of germ and pluripotency-associated genes, while in the majority of long-term cultured cells this molecular profile, typical for the differentiation pathway, was reduced and more genes related to the extracellular matrix production and attachment were expressed. The approach we provide here to study the molecular status of in vitro cultured spermatogonia may be important to optimize the culture conditions and to evaluate the germ cell plasticity in the future.

  1. Detection of Salmonella invA gene in shrimp enrichment culture by polymerase chain reaction.

    Science.gov (United States)

    Upadhyay, Bishnu Prasad; Utrarachkij, Fuangfa; Thongshoob, Jarinee; Mahakunkijcharoen, Yuvadee; Wongchinda, Niracha; Suthienkul, Orasa; Khusmith, Srisin

    2010-03-01

    Contamination of seafood with salmonellae is a major public health concern. Detection of Salmonella by standard culture methods is time consuming. In this study, an enrichment culture step prior to polymerase chain reaction (PCR) was applied to detect 284 bp fragment of Salmonella invA in comparison with the conventional culture method in 100 shrimp samples collected from four different shrimp farms and fresh food markets around Bangkok. Samples were pre-enriched in non-selective lactose broth (LB) and selective tetrathionate broth (TTB). PCR detection limit was 10 pg and 10(4) cfu/ml of viable salmonellae with 100% specificity. PCR assay detected 19 different Salmonella serovars belonging to 8 serogroups (B, C1, C2-C3, D1, E1, E4 and K) commonly found in clinical and environmental samples in Thailand. The detection rate of PCR following TTB enrichment (24%) was higher than conventional culture method (19%). PCR following TTB, but not in LB enrichment allowed salmonella detection with 84% sensitivity, 90% specificity and 89% accuracy. Shrimp samples collected from fresh food markets had higher levels of contaminated salmonellae than those from shrimp farms. The results indicated that incorporation of an enrichment step prior to PCR has the potential to be applied for detection of naturally contaminated salmonellae in food, environment and clinical samples.

  2. Preparation of Rodent Primary Cultures for Neuron–Glia, Mixed Glia, Enriched Microglia, and Reconstituted Cultures with Microglia

    OpenAIRE

    Chen, Shih-Heng; Oyarzabal, Esteban A.; Hong, Jau-Shyong

    2013-01-01

    Microglia, neurons, and macroglia (astrocytes and oligodendrocytes) are the major cell types in the central nervous system. In the past decades, primary microglia-enriched cultures have been widely used to study the biological functions of microglia in vitro. In order to study the interactions between microglia and other brain cells, neuron–glia, neuron–microglia, and mixed glia cultures were developed. The aim of this chapter is to provide basic and adaptable protocols for the preparation of...

  3. Enriching Chinese Cultural Heritage at the Queens Library

    Directory of Open Access Journals (Sweden)

    Gary E. Strong

    2001-10-01

    Full Text Available

    頁次:13-18

    The Queens Borough Public Library through its New Americans Program has been providing opportunities for the Chinese Community to experience quality library service for many years. By building collections, providing opportunities to learn English, providing job information, coping skills classes, cultural programs and electronic access to Chinese vernacular script, the Library provides a unique public library experience to its many immigrants. Through demographic analysis, the Library places its collections in the communities where immigrants live and provides programs of relevance to celebrate the cultures and traditions of the Chinese community.

  4. Breast Cancer Stem Cell Culture and Enrichment Using Poly(ε-Caprolactone) Scaffolds.

    Science.gov (United States)

    Palomeras, Sònia; Rabionet, Marc; Ferrer, Inés; Sarrats, Ariadna; Garcia-Romeu, Maria Luisa; Puig, Teresa; Ciurana, Joaquim

    2016-01-01

    The cancer stem cell (CSC) population displays self-renewal capabilities, resistance to conventional therapies, and a tendency to post-treatment recurrence. Increasing knowledge about CSCs' phenotype and functions is needed to investigate new therapeutic strategies against the CSC population. Here, poly(ε-caprolactone) (PCL), a biocompatible polymer free of toxic dye, has been used to fabricate scaffolds, solid structures suitable for 3D cancer cell culture. It has been reported that scaffold cell culture enhances the CSCs population. A RepRap BCN3D+ printer and 3 mm PCL wire were used to fabricate circular scaffolds. PCL design and fabrication parameters were first determined and then optimized considering several measurable variables of the resulting scaffolds. MCF7 breast carcinoma cell line was used to assess scaffolds adequacy for 3D cell culture. To evaluate CSC enrichment, the Mammosphere Forming Index (MFI) was performed in 2D and 3D MCF7 cultures. Results showed that the 60° scaffolds were more suitable for 3D culture than the 45° and 90° ones. Moreover, 3D culture experiments, in adherent and non-adherent conditions, showed a significant increase in MFI compared to 2D cultures (control). Thus, 3D cell culture with PCL scaffolds could be useful to improve cancer cell culture and enrich the CSCs population. PMID:27120585

  5. Breast Cancer Stem Cell Culture and Enrichment Using Poly(ε-Caprolactone Scaffolds

    Directory of Open Access Journals (Sweden)

    Sònia Palomeras

    2016-04-01

    Full Text Available The cancer stem cell (CSC population displays self-renewal capabilities, resistance to conventional therapies, and a tendency to post-treatment recurrence. Increasing knowledge about CSCs’ phenotype and functions is needed to investigate new therapeutic strategies against the CSC population. Here, poly(ε-caprolactone (PCL, a biocompatible polymer free of toxic dye, has been used to fabricate scaffolds, solid structures suitable for 3D cancer cell culture. It has been reported that scaffold cell culture enhances the CSCs population. A RepRap BCN3D+ printer and 3 mm PCL wire were used to fabricate circular scaffolds. PCL design and fabrication parameters were first determined and then optimized considering several measurable variables of the resulting scaffolds. MCF7 breast carcinoma cell line was used to assess scaffolds adequacy for 3D cell culture. To evaluate CSC enrichment, the Mammosphere Forming Index (MFI was performed in 2D and 3D MCF7 cultures. Results showed that the 60° scaffolds were more suitable for 3D culture than the 45° and 90° ones. Moreover, 3D culture experiments, in adherent and non-adherent conditions, showed a significant increase in MFI compared to 2D cultures (control. Thus, 3D cell culture with PCL scaffolds could be useful to improve cancer cell culture and enrich the CSCs population.

  6. Utilization of aminoaromatic acids by a methanogenic enrichment culture and by a novel Citrobacter freundii strain

    NARCIS (Netherlands)

    Savelieva, O.; Kotova, I.; Roelofsen, W.; Stams, A.J.M.; Netrusov, A.

    2004-01-01

    Following incubation of mesophilic methanogenic floccular sludge from a lab-scale upflow anaerobic sludge bed reactor used to treat cattle manure wastewater, a stable 5-aminosalicylate-degrading enrichment culture was obtained. Subsequently, a Citrobacter freundii strain, WA1, was isolated from the

  7. Using Enrichment Clusters to Address the Needs of Culturally and Linguistically Diverse Learners

    Science.gov (United States)

    Allen, Jennifer K.; Robbins, Margaret A.; Payne, Yolanda Denise; Brown, Katherine Backes

    2016-01-01

    Using data from teacher interviews, classroom observations, and a professional development workshop, this article explains how one component of the schoolwide enrichment model (SEM) has been implemented at a culturally diverse elementary school serving primarily Latina/o and African American students. Based on a broadened conception of giftedness,…

  8. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...... ammonia tolerant methanogen in a CSTR reactor could completely alleviate the ammonia inhibitory effect. Furthermore, it was found that bioaugmentation with the enriched culture resulted in 25% higher methane production compared to when the bioaugmentation was achieved with pure methanogenic strains....... The bioaugmentation was performed without pausing the continuous operation of the CSTR reactor and without excluding the ammonia-rich substrate from the feedstock. Thus, bioaugmentation with mixed methanogenic cultures could potentially support the development of an efficient and cost-effective biomethanation process...

  9. Newly Cultured Bacteria with Broad Diversity Isolated from Eight-Week Continuous Culture Enrichments of Cow Feces on Complex Polysaccharides

    OpenAIRE

    Ziemer, Cherie J.

    2014-01-01

    One of the functions of the mammalian large intestinal microbiota is the fermentation of plant cell wall components. In ruminant animals, the majority of their nutrients are obtained via pregastric fermentation; however, up to 20% can be recovered from microbial fermentation in the large intestine. Eight-week continuous culture enrichments of cattle feces with cellulose and xylan-pectin were used to isolate bacteria from this community. A total of 459 bacterial isolates were classified phylog...

  10. The importance of local events in enriching the cultural and tourism offer

    Directory of Open Access Journals (Sweden)

    Spasojević Bojana

    2013-01-01

    Full Text Available In the municipality of Ruma twenty five events take place per year. Most of these events have local or regional character. The event "Christmas Street" is the youngest event which is being organized in Ruma, the first time was held in late 2011. The subject of this paper is to study this event that complements the existing tourism offer of Ruma as potential tourist destination of Vojvodina. The aim of this paper is to highlight the importance of this event in the cultural enrichment of Ruma and its surroundings as well as the development of event tourism and positive presentation of the Municipality of Ruma. The significance of local events for enrichment of cultural-tourism offer will be presented as Case study of “Christmas street” in the city of Ruma. [Projekat Ministarstva nauke Republike Srbije, br. 176020

  11. Developments in techniques for the isolation, enrichment, main culture conditions and identification of spermatogonial stem cells.

    Science.gov (United States)

    He, Yanan; Chen, Xiaoli; Zhu, Huabin; Wang, Dong

    2015-12-01

    The in vitro culture system of spermatogonial stem cells (SSCs) provides a basis for studies on spermatogenesis, and also contributes to the development of new methods for the preservation of livestock and animal genetic modification. In vitro culture systems have mainly been established for mouse SSCs, but are lacking for farm animals. We reviewed and analyzed the current progress in SSC techniques such as isolation, purification, cultivation and identification. Based on the published studies, we concluded that two-step enzyme digestion and magnetic-activated cell sorting are fast becoming the main methods for isolation and enrichment of SSCs. With regard to the culture systems, serum and feeders were earlier thought to play an important role in the self-renewal and proliferation of SSCs, but serum- and feeder-free culture systems as a means of overcoming the limitations of SSC differentiation in long-term SSC culture are being explored. However, there is still a need to establish more efficient and ideal culture systems that can also be used for SSC culture in larger mammals. Although the lack of SSC-specific surface markers has seriously affected the efficiency of purification and identification, the transgenic study is helpful for our identification of SSCs. Therefore, future studies on SSC techniques should focus on improving serum- and feeder-free culture techniques, and discovering and identifying specific surface markers of SSCs, which will provide new ideas for the optimization of SSC culture systems for mice and promote related studies in farm animals. PMID:25749914

  12. nirS-Encoding denitrifier community composition, distribution, and abundance along the coastal wetlands of China.

    Science.gov (United States)

    Gao, Juan; Hou, Lijun; Zheng, Yanling; Liu, Min; Yin, Guoyu; Li, Xiaofei; Lin, Xianbiao; Yu, Chendi; Wang, Rong; Jiang, Xiaofen; Sun, Xiuru

    2016-10-01

    For the past few decades, human activities have intensively increased the reactive nitrogen enrichment in China's coastal wetlands. Although denitrification is a critical pathway of nitrogen removal, the understanding of denitrifier community dynamics driving denitrification remains limited in the coastal wetlands. In this study, the diversity, abundance, and community composition of nirS-encoding denitrifiers were analyzed to reveal their variations in China's coastal wetlands. Diverse nirS sequences were obtained and more than 98 % of them shared considerable phylogenetic similarity with sequences obtained from aquatic systems (marine/estuarine/coastal sediments and hypoxia sea water). Clone library analysis revealed that the distribution and composition of nirS-harboring denitrifiers had a significant latitudinal differentiation, but without a seasonal shift. Canonical correspondence analysis showed that the community structure of nirS-encoding denitrifiers was significantly related to temperature and ammonium concentration. The nirS gene abundance ranged from 4.3 × 10(5) to 3.7 × 10(7) copies g(-1) dry sediment, with a significant spatial heterogeneity. Among all detected environmental factors, temperature was a key factor affecting not only the nirS gene abundance but also the community structure of nirS-type denitrifiers. Overall, this study significantly enhances our understanding of the structure and dynamics of denitrifying communities in the coastal wetlands of China. PMID:27311565

  13. Enrichment of prostate cancer stem cells from primary prostate cancer cultures of biopsy samples

    OpenAIRE

    Wang, Shunqi; Huang, Shengsong; Zhao, Xin; Zhang, Qimin; Wu, Min; Sun, Feng; Han, Gang; Wu, Denglong

    2013-01-01

    This study was to enrich prostate cancer stem cells (PrCSC) from primary prostate cancer cultures (PPrCC). Primary prostate cancer cells were amplified in keratinocyte serum-free medium with epidermal growth factor (EGF) and bovine pituitary extract (BPE), supplemented with leukemia inhibitory factor (LIF), stem cell factor (SCF) and cholera toxin. After amplification, cells were transferred into ultra-low attachment dishes with serum-free DMEM/F12 medium, supplemented with EGF, basic fibrobl...

  14. Bacterial community analysis of cypermethrin enrichment cultures and bioremediation of cypermethrin contaminated soils.

    Science.gov (United States)

    Akbar, Shamsa; Sultan, Sikander; Kertesz, Michael

    2015-07-01

    Cypermethrin is widely used for insect control; however, its toxicity toward aquatic life requires its complete removal from contaminated areas where the natural degradation ability of microbes can be utilized. Agricultural soil with extensive history of CM application was used to prepare enrichment cultures using cypermethrin as sole carbon source for isolation of cypermethrin degrading bacteria and bacterial community analysis using PCR-DGGE of 16 S rRNA gene. DGGE analysis revealed that dominant members of CM enrichment culture were associated with α-proteobacteria followed by γ-proteobacteria, Firmicutes, and Actinobacteria. Three potential CM-degrading isolates identified as Ochrobactrum anthropi JCm1, Bacillus megaterium JCm2, and Rhodococcus sp. JCm5 degraded 86-100% of CM (100 mg L(-1) ) within 10 days. These isolates were also able to degrade other pyrethroids, carbofuran, and cypermethrin degradation products. Enzyme activity assays revealed that enzymes involved in CM-degradation were inducible and showed activity when strains were grown on cypermethrin. Degradation kinetics of cypermethrin (200 mg kg(-1)) in soils inoculated with isolates JCm1, JCm2, and JCm5 suggested time-dependent disappearance of cypermethrin with rate constants of 0.0516, 0.0425, and 0.0807 d(-1), respectively, following first order rate kinetics. The isolated bacterial strains were among dominant genera selected under CM enriched conditions and represent valuable candidates for in situ bioremediation of contaminated soils and waters.

  15. Metabolic characteristics of an aerobe isolated from a methylotrophic methanogenic enrichment culture

    Indian Academy of Sciences (India)

    Stephen V Rapheal; K R Swaminathan; K Lalitha

    2003-03-01

    An anaerobic methylotrophic methanogenic enrichment culture, with sustained metabolic characteristics, including that of methanation for over a decade, was the choice of the present study on interspecies interactions. Growth and methanation by the enrichment were suppressed in the presence of antibiotics, and no methanogen grown on methanol could be isolated using stringent techniques. The present study confirmed syntrophic metabolic interactions in this enrichment with the isolation of a strain of Pseudomonas sp. The organism had characteristic metabolic versatility in metabolizing a variety of substrates including alcohols, aliphatic acids, amino acids, and sugars. Anaerobic growth was favoured with nitrate in the growth medium. Cells grown anaerobically with methanol, revealed maximal nitrate reductase activity. Constitutive oxidative activity of the membrane system emerged from the high-specific oxygen uptake and nitrate reductase activities of the aerobically and anerobically grown cells respectively. Cells grown anaerobically on various alcohols effectively oxidized methanol in the presence of flavins, cofactor FAD and the methanogenic cofactor F420, suggesting a constitutive alcohol oxidizing capacity. In cells grown anaerobically on methanol, the rate of methanol oxidation with F420 was three times that of FAD. Efficient utilization of alcohols in the presence of F420 is a novel feature of the present study. The results suggest that utilization of methanol by the mixed culture would involve metabolic interactions between the Pseudomonas sp. and the methanogen(s). Methylotrophic, methanogenic partnership involving an aerobe is a novel feature hitherto unreported among anaerobic syntrophic associations and is of ecological significance.

  16. Establishment and Characterization of an Anaerobic Thermophilic (55 degrees C) Enrichment Culture Degrading Long-Chain Fatty Acids

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Ahring, Birgitte Kiær

    1995-01-01

    A thermophilic, long-chain fatty acid-oxidizing culture was enriched. Stearate was used as the substrate, and methane and carbon dioxide were the sole end products. Cultivation was possible only when a fed-batch system was used or with addition of activated carbon or bentonite. The enrichment...

  17. Proteomic characterization of golgi membranes enriched from Arabidopsis suspension cell cultures

    DEFF Research Database (Denmark)

    Hansen, Sara Fasmer; Ebert, Berit; Rautengarten, Carsten;

    2016-01-01

    from an Arabidopsis cell suspension culture that can be used to investigate the proteome of this organelle. We also provide a useful workflow for the examination of proteomic data as the result of multiple analyses. Finally, we highlight a simple technique to validate the subcellular localization......The plant Golgi apparatus has a central role in the secretory pathway and is the principal site within the cell for the assembly and processing of macromolecules. The stacked membrane structure of the Golgi apparatus along with its interactions with the cytoskeleton and endoplasmic reticulum has...... historically made the isolation and purification of this organelle difficult. Density centrifugation has typically been used to enrich Golgi membranes from plant microsomal preparations, and aside from minor adaptations, the approach is still widely employed. Here we outline the enrichment of Golgi membranes...

  18. Integrated biogas upgrading and hydrogen utilization in an anaerobic reactor containing enriched hydrogenotrophic methanogenic culture.

    Science.gov (United States)

    Luo, Gang; Angelidaki, Irini

    2012-11-01

    Biogas produced by anaerobic digestion, is mainly used in a gas motor for heat and electricity production. However, after removal of CO(2) , biogas can be upgraded to natural gas quality, giving more utilization possibilities, such as utilization as autogas, or distant utilization by using the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched hydrogenotrophic methanogens and fed with biogas and hydrogen. Both mesophilic- and thermophilic anaerobic cultures were enriched to convert CO(2) to CH(4) by addition of H(2) . Enrichment at thermophilic temperature (55°C) resulted in CO(2) and H(2) bioconversion rate of 320 mL CH(4) /(gVSS h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic- and thermophilic-enriched cultures, as revealed by PCR-DGGE. Nonetheless, they all belonged to the order Methanobacteriales, which can mediate hydrogenotrophic methanogenesis. Biogas upgrading was then tested in a thermophilic anaerobic reactor under various operation conditions. By continuous addition of hydrogen in the biogas reactor, high degree of biogas upgrading was achieved. The produced biogas had a CH(4) content, around 95% at steady-state, at gas (mixture of biogas and hydrogen) injection rate of 6 L/(L day). The increase of gas injection rate to 12 L/(L day) resulted in the decrease of CH(4) content to around 90%. Further study showed that by decreasing the gas-liquid mass transfer by increasing the stirring speed of the mixture the CH(4) content was increased to around 95%. Finally, the CH(4) content around 90% was achieved in this study with the gas injection rate as high as 24 L/(L day).

  19. Inhibition of anaerobic ammonium oxidizing (anammox) enrichment cultures by substrates, metabolites and common wastewater constituents.

    Science.gov (United States)

    Carvajal-Arroyo, José M; Sun, Wenjie; Sierra-Alvarez, Reyes; Field, Jim A

    2013-03-01

    Anaerobic ammonium oxidation (anammox) is an emerging technology for nitrogen removal that provides a more environmentally sustainable and cost effective alternative compared to conventional biological treatment methods. The objective of this study was to investigate the inhibitory impact of anammox substrates, metabolites and common wastewater constituents on the microbial activity of two different anammox enrichment cultures (suspended and granular), both dominated by bacteria from the genus Brocadia. Inhibition was evaluated in batch assays by comparing the N(2) production rates in the absence or presence of each compound supplied in a range of concentrations. The optimal pH was 7.5 and 7.3 for the suspended and granular enrichment cultures, respectively. Among the substrates or products, ammonium and nitrate caused low to moderate inhibition, whereas nitrite caused almost complete inhibition at concentrations higher than 15 mM. The intermediate, hydrazine, either stimulated or caused low inhibition of anammox activity up to 3mM. Of the common constituents in wastewater, hydrogen sulfide was the most severe inhibitor, with 50% inhibitory concentrations (IC(50)) as low as 0.03 mM undissociated H(2)S. Dissolved O(2) showed moderate inhibition (IC(50)=2.3-3.8 mg L(-1)). In contrast, phosphate and salinity (NaCl) posed very low inhibition. The suspended- and granular anammox enrichment cultures had similar patterns of response to the various inhibitory stresses with the exception of phosphate. The findings of this study provide comprehensive insights on the tolerance of the anammox process to a wide variety of potential inhibiting compounds.

  20. Large scale production of Blackleg vaccine by fermenter and enriched culture medium in Iran

    Directory of Open Access Journals (Sweden)

    Pilehchian Langroudi, R.

    2012-06-01

    Full Text Available In all biological systems growth is defined as increase of chemical compounds. Bacteria can achieve to balanced growth if they are growing in a medium, which are completely adapted to it. Clostridium chauvoei, (Clostridium feseri is an anaerobic, spore forming, motile, and polymorph bacteria, which its size varies from 0.5-1 to 3-8 micron and could be observed as individual bacterium, diplo, and rarely streptococcus. Blackleg is a fatal disease of young cattle. It produces an acute local infection, and the resulting blood poisoning leads to rapid death. Clostridium chauvoei and, less frequently, Clostridium septicum are the most commonly responsible organisms. Vaccination is the only effective means for controlling of blackleg disease. Several kinds of vaccine are available commercially. It is 4 decades that blackleg vaccine is produced in Razi institute and because of enhanced demand of country, decision was made to improve the production procedure of this vaccine using large-scale fermenter, so the aim of this study was adaptation of Clostridium chauvoei to growth and proliferation in fermenter for preparation of a potent vaccine. Accordingly attempts were made to prepare and formulate the ingredients in order to obtain high yield of Clostridium chauvoei in culture medium by fermenter. All experiments were done in two sets: A-growth in glass bottles using conventional culture medium and B-growth in fermenter using conventional culture medium similar to A and also enriched culture medium. Results showed high yield of Clostridium chauvoei suspension in fermenter after 10 hours, using enriched culture medium (more than 1,480,000,000 organisms/ml, but no significant changes was obtained in glass bottles conditions comparing to the fermenter conditions. The safety and potency of the prepared vaccine was determined in sheep and guinea pigs according to British pharmacopoeia (veterinary with satisfactory results. Since this research has been

  1. The importance of local events in enriching the cultural and tourism offer

    OpenAIRE

    Spasojević Bojana; Berić Dejan; Jovičić Ana

    2013-01-01

    In the municipality of Ruma twenty five events take place per year. Most of these events have local or regional character. The event "Christmas Street" is the youngest event which is being organized in Ruma, the first time was held in late 2011. The subject of this paper is to study this event that complements the existing tourism offer of Ruma as potential tourist destination of Vojvodina. The aim of this paper is to highlight the importance of this event in the cultural enrichment of ...

  2. Batch fermentative hydrogen production by enriched mixed culture: Combination strategy and their microbial composition.

    Science.gov (United States)

    Sivagurunathan, Periyasamy; Sen, Biswarup; Lin, Chiu-Yue

    2014-02-01

    The effect of individual and combined mixed culture on dark fermentative hydrogen production performance was investigated. Mixed cultures from cow dung (C1), sewage sludge (C2), and pig slurry (C3) were enriched under strict anaerobic conditions at 37°C with glucose as the sole carbon source. Biochemical hydrogen production test in peptone-yeast-glucose (PYG) and basal medium was performed for individual mixed cultures (C1, C2 and C3) and their combinations (C1-C2, C2-C3, C1-C3 and C1-C2-C3) at a glucose concentration of 10 g/L, 37°C and initial pH 7. Maximum hydrogen yields (HY) of 2.0 and 1.86 [Formula: see text] by C2, and 1.98 and 1.95 mol(H2)/mol(glucose) by C2-C3 were obtained in PYG and basal medium, respectively. Butyrate and acetate were the major soluble metabolites produced by all the cultures, and the ratio of butyrate to acetate was ∼2 fold higher in basal medium than PYG medium, indicating strong influence of media formulation on glucose catabolism. The major hydrogen-producing bacterial strains, observed in all mixed cultures, belonged to Clostridium butyricum, C. saccharobutylicum, C. tertium and C. perfringens. The hydrogen production performance of the combined mixed culture (C2-C3) was further evaluated on beverage wastewater (10 g/L) at pH 7 and 37°C. The results showed an HY of 1.92 mol(H2)/mol(glucose-equivalent). Experimental evidence suggests that hydrogen fermentation by mixed culture combination could be a novel strategy to improve the HY from industrial wastewater. PMID:24095211

  3. Batch fermentative hydrogen production by enriched mixed culture: Combination strategy and their microbial composition.

    Science.gov (United States)

    Sivagurunathan, Periyasamy; Sen, Biswarup; Lin, Chiu-Yue

    2014-02-01

    The effect of individual and combined mixed culture on dark fermentative hydrogen production performance was investigated. Mixed cultures from cow dung (C1), sewage sludge (C2), and pig slurry (C3) were enriched under strict anaerobic conditions at 37°C with glucose as the sole carbon source. Biochemical hydrogen production test in peptone-yeast-glucose (PYG) and basal medium was performed for individual mixed cultures (C1, C2 and C3) and their combinations (C1-C2, C2-C3, C1-C3 and C1-C2-C3) at a glucose concentration of 10 g/L, 37°C and initial pH 7. Maximum hydrogen yields (HY) of 2.0 and 1.86 [Formula: see text] by C2, and 1.98 and 1.95 mol(H2)/mol(glucose) by C2-C3 were obtained in PYG and basal medium, respectively. Butyrate and acetate were the major soluble metabolites produced by all the cultures, and the ratio of butyrate to acetate was ∼2 fold higher in basal medium than PYG medium, indicating strong influence of media formulation on glucose catabolism. The major hydrogen-producing bacterial strains, observed in all mixed cultures, belonged to Clostridium butyricum, C. saccharobutylicum, C. tertium and C. perfringens. The hydrogen production performance of the combined mixed culture (C2-C3) was further evaluated on beverage wastewater (10 g/L) at pH 7 and 37°C. The results showed an HY of 1.92 mol(H2)/mol(glucose-equivalent). Experimental evidence suggests that hydrogen fermentation by mixed culture combination could be a novel strategy to improve the HY from industrial wastewater.

  4. Molecular phylogeny of heterotrophic nitrifiers and aerobic denitrifiers and their potential role in ammonium removal.

    Science.gov (United States)

    Srivastava, Meenakshi; Kaushik, Manish Singh; Singh, Anumeha; Singh, Deepti; Mishra, Arun Kumar

    2016-08-01

    To investigate the physiology and taxonomic composition of the key players of nitrification and denitrification processes in paddy fields, culture dependent and independent studies have been carried out. A total of 28 bacterial strains have been screened in which six were capable of reducing nitrate and nitrite as well as having significant ammonium removal potential. 16S rRNA-PCR-DGGE-based molecular typing of enriched batch culture was done with time duration to explore and identify dominant and stable soil denitrifiers. Notably, three isolates namely PDN3, PDN19, PDN14 were found to be efficiently involved in the removal of 70.32, 71.46, and 81.50% of NH4 (+) and showed closest similarity (>98%) with Bacillus cereus, Bacillus subtilis, and Pseudomonas aeruginosa strains, respectively. The bacterial strain PDN14 showed maximum growth with highest ammonium removal rate (2.78 gN/(m(3) ·h) has also been characterized based on nosZ gene which showed similarity to uncultured γ- Proteobacteria, P. aeruginosa sp. B3. Median joining (MJ) network and rRNA secondary structure have been analyzed for their detailed taxonomic diversity and derived haplotype-based co-occurrence. Results demonstrated that such strains can serve as good candidate for in situ nitrogen transformation in paddy soils and improvingly characterized by physiological and detailed phylogenetic approaches. PMID:27037833

  5. Identification of novel glycosyl hydrolases with cellulolytic activity against crystalline cellulose from metagenomic libraries constructed from bacterial enrichment cultures

    OpenAIRE

    Mori, Toshio; Kamei, Ichiro; Hirai, Hirofumi; Kondo, Ryuichiro

    2014-01-01

    To obtain cellulases that are capable of degrading crystalline cellulose and cedar wood, metagenomic libraries were constructed from raw soil sample which was covered to pile of cedar wood sawdust or from its enrichment cultures. The efficiency of screening of metagenomic library was improved more than 3 times by repeating enrichment cultivation using crystalline cellulose as a carbon source, compared with the library constructed from raw soil. Four cellulase genes were obtained from the meta...

  6. Biogeochemical insights into microbe-mineral-fluid interactions in hydrothermal chimneys using enrichment culture.

    Science.gov (United States)

    Callac, Nolwenn; Rouxel, Olivier; Lesongeur, Françoise; Liorzou, Céline; Bollinger, Claire; Pignet, Patricia; Chéron, Sandrine; Fouquet, Yves; Rommevaux-Jestin, Céline; Godfroy, Anne

    2015-05-01

    Active hydrothermal chimneys host diverse microbial communities exhibiting various metabolisms including those involved in various biogeochemical cycles. To investigate microbe-mineral-fluid interactions in hydrothermal chimney and the driver of microbial diversity, a cultural approach using a gas-lift bioreactor was chosen. An enrichment culture was performed using crushed active chimney sample as inoculum and diluted hydrothermal fluid from the same vent as culture medium. Daily sampling provided time-series access to active microbial diversity and medium composition. Active archaeal and bacterial communities consisted mainly of sulfur, sulfate and iron reducers and hydrogen oxidizers with the detection of Thermococcus, Archaeoglobus, Geoglobus, Sulfurimonas and Thermotoga sequences. The simultaneous presence of active Geoglobus sp. and Archaeoglobus sp. argues against competition for available carbon sources and electron donors between sulfate and iron reducers at high temperature. This approach allowed the cultivation of microbial populations that were under-represented in the initial environmental sample. The microbial communities are heterogeneously distributed within the gas-lift bioreactor; it is unlikely that bulk mineralogy or fluid chemistry is the drivers of microbial community structure. Instead, we propose that micro-environmental niche characteristics, created by the interaction between the mineral grains and the fluid chemistry, are the main drivers of microbial diversity in natural systems.

  7. Selective enrichment and production of highly urease active bacteria by non-sterile (open) chemostat culture.

    Science.gov (United States)

    Cheng, Liang; Cord-Ruwisch, Ralf

    2013-10-01

    In general, bioprocesses can be subdivided into naturally occurring processes, not requiring sterility (e.g., beer brewing, wine making, lactic acid fermentation, or biogas digestion) and other processes (e.g., the production of enzymes and antibiotics) that typically require a high level of sterility to avoid contaminant microbes overgrowing the production strain. The current paper describes the sustainable, non-sterile production of an industrial enzyme using activated sludge as inoculum. By using selective conditions (high pH, high ammonia concentration, and presence of urea) for the target bacterium, highly active ureolytic bacteria, physiologically resembling Sporosarcina pasteurii were reproducibly enriched and then continuously produced via chemostat operation of the bioreactor. When using a pH of 10 and about 0.2 M urea in a yeast extract-based medium, ureolytic bacteria developed under aerobic chemostat operation at hydraulic retention times of about 10 h with urease levels of about 60 μmol min⁻¹ ml⁻¹ culture. For cost minimization at an industrial scale the costly protein-rich yeast extract medium could be replaced by commercial milk powder or by lysed activated sludge. Glutamate, molasses, or glucose-based media did not result in the enrichment of ureolytic bacteria by the chemostat. The concentration of intracellular urease was sufficiently high such that the produced raw effluent from the reactor could be used directly for biocementation in the field.

  8. Fermentative bio-hydrogen production from cellulose by cow dung compost enriched cultures

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Nan-Qi; Xu, Ji-Fei; Gao, Ling-Fang; Xin, Liang; Qiu, Jie; Su, Dong-Xia [State Key Laboratory of Urban Water Resources and Environment, Harbin Institute of Technology, Harbin 150090 (China)

    2010-04-15

    The performance of hydrogen production from cellulose by the cow dung compost enriched continuously in defined medium containing cellulose was investigated. In the initial experiments, batch-fermentation was carried out to observe the effects of different substrate concentration conditions on the rate of cellulose-degrading, growth of bacteria and the capability of hydrogen-producing from cellulose. The result showed that the cellulose degradation decreased from 55% at 5 g/l to 22% at 30 g/l. The maximum cumulative hydrogen production and the rate of hydrogen production first increased from 828 ml/l at 5 g/l to 1251 ml/l at 10 g/l then remained constant beyond 10 g/l. The maximum hydrogen production potential, the rate of hydrogen production and the yield of hydrogen was 1525 ml/l, 33 ml/l.h, and 272 ml/g-cellulose (2.09 mol/mol-hexose) was obtained at substrate concentration 10 g/l, the hydrogen concentration in biogas was 47-50%(v/v) and there was no methane observed. During the conversion of cellulose into hydrogen, acetate and butyrate were main liquid end-products in the metabolism of hydrogen fermentation. These results proposed that cow dung compost enriched cultures were ideal microflora for hydrogen production from cellulose. (author)

  9. Diversity of benzyl- and alkylsuccinate synthase genes in hydrocarbon-impacted environments and enrichment cultures.

    Science.gov (United States)

    Callaghan, Amy V; Davidova, Irene A; Savage-Ashlock, Kristen; Parisi, Victoria A; Gieg, Lisa M; Suflita, Joseph M; Kukor, Jerome J; Wawrik, Boris

    2010-10-01

    Hydrocarbon-degrading microorganisms play an important role in the natural attenuation of spilled petroleum in a variety of anoxic environments. The role of benzylsuccinate synthase (BSS) in aromatic hydrocarbon degradation and its use as a biomarker for field investigations are well documented. The recent discovery of alkylsuccinate synthase (ASS) allows the opportunity to test whether its encoding gene, assA, can serve as a comparable biomarker of anaerobic alkane degradation. Degenerate assA- and bssA-targeted PCR primers were designed in order to survey the diversity of genes associated with aromatic and aliphatic hydrocarbon biodegradation in petroleum-impacted environments and enrichment cultures. DNA was extracted from an anaerobic alkane-degrading isolate (Desulfoglaeba alkenexedens ALDC), hydrocarbon-contaminated river and aquifer sediments, a paraffin-degrading enrichment, and a propane-utilizing mixed culture. Partial assA and bssA genes were PCR amplified, cloned, and sequenced, yielding several novel clades of assA genes. These data expand the range of alkane-degrading conditions for which relevant gene sequences are available and indicate that considerable diversity of assA genes can be found in hydrocarbon-impacted environments. The detection of genes associated with anaerobic alkane degradation in conjunction with the in situ detection of alkylsuccinate metabolites was also demonstrated. Comparable molecular signals of assA/bssA were not found when environmental metagenome databases of uncontaminated sites were searched. These data confirm that the assA gene is a useful biomarker for anaerobic alkane metabolism. PMID:20504044

  10. Selective enrichment of hepatoeytes from mouse embryonic stem cells with a culture system containing cholestatic serum

    Institute of Scientific and Technical Information of China (English)

    Jun MIN; Er-wei SONG; Ji-sheng CHEN; Chang-zhen SHANG; Ya-jin CHEN; Lei ZHANG; Lu LIU; Xiao-geng DENG; Mei YANG; Dong-ping CHEN; Jun CAO

    2007-01-01

    Aim: There is increasing evidence indicating that embryonic stem (ES) cells are capable of differentiating into hepatocyte-like cells in vitro. However, it is neces- sary to improve the differentiation efficiency so as to promote the clinical application. Here, we report an efficient culture system to support hepatocyte differentiation from ES cells by utilizing cholestatic serum. Methods: One week after the induction of El4 mouse ES cells into hepatocytes with sodium butyrate, cholestatic serum was added into the culture system at various concentrations and hepatocyte-like cells were induced to proliferate. The morphological and phenotypic markers of hepatocytes were characterized using light microscopy, immunocytochemistry, and RT-PCR, respectively. The function of glycogen stor- age of the differentiated cells was detected by Periodic acid-Schiff (PAS) reaction, and the ratio of hepatic differentiation was determined by counting the albumin and PAS-positive cells. Results: In the presence of conditional selective medium containing cholestatic serum, numerous epithelial cells resembling hepatocytes were observed. The RT-PCR analysis showed that undifferentiated ES cells did not express any hepatic-specific markers; however, in the presence of sodium butyrate and conditional selective medium containing cholestatic serum, hepatic differentiation markers were detected. Immunofluorescence staining showed that those ES-derived hepatocytes were α-fetoprotein, albumin, and cytokeratin 18 positive, with the ability of storing glycogen. Further determination of the hepatic differentiation ratio showed that the application of cholestatic serum efficiently enriched ES-derived hepatocyte-like cells by inducing lineage differentiation and enhancing lineage proliferation. Conclusion: The conditional selective medium containing cholestatic serum is optimal to selectively enrich hepatocyte-like cells from mixed differentiated ES cells, which may provide a novel method to

  11. Hydrogenotrophic culture enrichment reveals rumen Lachnospiraceae and Ruminococcaceae acetogens and hydrogen-responsive Bacteroidetes from pasture-fed cattle.

    Science.gov (United States)

    Gagen, Emma J; Padmanabha, Jagadish; Denman, Stuart E; McSweeney, Christopher S

    2015-07-01

    Molecular information suggests that there is a broad diversity of acetogens in the rumen, distinct from any currently isolated acetogens. We combined molecular analysis with enrichment culture techniques to investigate this diversity further. Methane-inhibited, hydrogenotrophic enrichment cultures produced acetate as the dominant end product. Acetyl-CoA synthase gene analysis revealed putative acetogens in the cultures affiliated with the Lachnospiraceae and Ruminococcaceae as has been found in other rumen studies. No formyltetrahydrofolate synthetase genes affiliating with acetogens or with 'homoacetogen similarity' scores >90% were identified. To further investigate the hydrogenotrophic populations in these cultures and link functional gene information with 16S rRNA gene identity, cultures were subcultured quickly, twice, through medium without exogenous hydrogen, followed by incubation without exogenous hydrogen. Comparison of cultures lacking hydrogen and their parent cultures revealed novel Lachnospiraceae and Ruminococcaceae that diminished in the absence of hydrogen, supporting the hypothesis that they were likely the predominant acetogens in the enrichments. Interestingly, a range of Bacteroidetes rrs sequences that demonstrated <86% identity to any named isolate also diminished in cultures lacking hydrogen. Acetogens or sulphate reducers from the Bacteroidetes have not been reported previously; therefore this observation requires further investigation.

  12. Hydrogenotrophic culture enrichment reveals rumen Lachnospiraceae and Ruminococcaceae acetogens and hydrogen-responsive Bacteroidetes from pasture-fed cattle.

    Science.gov (United States)

    Gagen, Emma J; Padmanabha, Jagadish; Denman, Stuart E; McSweeney, Christopher S

    2015-07-01

    Molecular information suggests that there is a broad diversity of acetogens in the rumen, distinct from any currently isolated acetogens. We combined molecular analysis with enrichment culture techniques to investigate this diversity further. Methane-inhibited, hydrogenotrophic enrichment cultures produced acetate as the dominant end product. Acetyl-CoA synthase gene analysis revealed putative acetogens in the cultures affiliated with the Lachnospiraceae and Ruminococcaceae as has been found in other rumen studies. No formyltetrahydrofolate synthetase genes affiliating with acetogens or with 'homoacetogen similarity' scores >90% were identified. To further investigate the hydrogenotrophic populations in these cultures and link functional gene information with 16S rRNA gene identity, cultures were subcultured quickly, twice, through medium without exogenous hydrogen, followed by incubation without exogenous hydrogen. Comparison of cultures lacking hydrogen and their parent cultures revealed novel Lachnospiraceae and Ruminococcaceae that diminished in the absence of hydrogen, supporting the hypothesis that they were likely the predominant acetogens in the enrichments. Interestingly, a range of Bacteroidetes rrs sequences that demonstrated <86% identity to any named isolate also diminished in cultures lacking hydrogen. Acetogens or sulphate reducers from the Bacteroidetes have not been reported previously; therefore this observation requires further investigation. PMID:26109360

  13. Denitrifying Bacteria in Paddy Soils of Taihu Lake Basin,China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua-Yong; LI Zhen-Gao; PAN Ying-Hua; LI Liang-Mo

    2004-01-01

    This study attempted to determine the characteristics of the communities, the ecological factors, and the denitrifying enzyme activity for denitrifying bacteria found in the paddy soils of the Taihu Lake Basin, China. Samples of the six main soil types of the basin were taken from paddy fields with different fertilities. The total numbers of bacteria and denitrifying bacteria in the high fertility soils were much more than those in low fertility soils, and the number of denitrifying bacteria accounted for 49% to 80% of the total number of bacteria. The O2 content was an important ecological factor that affected denitrification. Of test the strains isolated from the paddy soils in the Taihu Lake Basin, some (e.g., Pseudomonas spp.)grew well under low oxygen partial pressure, while others (e.g., Bacillus spp.) had no strict predilection with O2 content.Another critical ecological factor was the nitrogen concentration. Three selected denitrifying bacteria grew better in a culture medium with 135 instead of 276 mg L-1 nitrogen. At the same time 67% of the test strains were able to reduce NO-3 to NO-2 and 56% had N2O reductase.

  14. Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

    Science.gov (United States)

    Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

    1997-01-01

    We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

  15. Numerically dominant denitrifying bacteria from world soils.

    Science.gov (United States)

    Gamble, T N; Betlach, M R; Tiedje, J M

    1977-04-01

    Nineteen soils, three freshwater lake sediments, and oxidized poultry manure were examined to determine the dominant denitrifier populations. The samples, most shown or expected to support active denitrification, were from eight countries and included rice paddy, temperate agricultural, rain forest, organic, and waste-treated soils. Over 1,500 organisms that could grow anaerobically on nitrate agar were isolated. After purification, 146 denitrifiers were obtained, as verified by production of N(2) from NO(3) (-). These isolates were characterized by 52 properties appropriate for the Pseudomonas-Alcaligenes group. Numerical taxonomic procedures were used to group the isolates and compare them with nine known denitrifier species. The major group isolated was representative of Pseudonomas fluorescens biotype II. The second most prevalent group was representative of Alcaligenes. Other Pseudomonas species as well as members of the genus Flavobacterium, the latter previously not known to denitrify, also were identified. One-third of the isolates could not utilize glucose or other carbohydrates as sole carbon sources. Significantly, none of the numerically dominant denitrifiers we isolated resembled the most studied species: Pseudomonas denitrificans, Pseudomonas perfectomarinus, and Paracoccus denitrificans. Denitrification appears to be a property of a very diverse group of gram-negative, motile bacteria, as shown by the large number (22.6%) of ungrouped organisms. The diversity of denitrifiers from a given sample was usually high, with at least two groups present. Denitrifiers, nitrite accumulators, and organisms capable of anaerobic growth were present in the ratio of 0.20+/-0.23:0.81+/-0.23:1. There were few correlations between their numbers and the sample characteristics measured. However, the temperatures at which isolates could grow were significantly related to the temperatures of the environments from which they were isolated. Regression analysis revealed few

  16. Therapy of Chronic Cardiosclerosis in WAG Rats Using Cultures of Cardiovascular Cells Enriched with Cardiac Stem Cell.

    Science.gov (United States)

    Chepeleva, E V; Pavlova, S V; Malakhova, A A; Milevskaya, E A; Rusakova, Ya L; Podkhvatilina, N A; Sergeevichev, D S; Pokushalov, E A; Karaskov, A M; Sukhikh, G T; Zakiyan, S M

    2015-11-01

    We developed a protocol for preparing cardiac cell culture from rat heart enriched with regional stem cells based on clonogenic properties and proliferation in culture in a medium with low serum content. Experiments on WAG rats with experimental ischemic myocardial damage showed that implantation of autologous regional stem cells into the left ventricle reduced the volume of cicatricial tissue, promoted angiogenesis in the damaged zone, and prevented the risk of heart failure development.

  17. Continuous enrichment culture and molecular monitoring to investigate the microbial diversity of thermophiles inhabiting deep-sea hydrothermal ecosystems

    OpenAIRE

    POSTEC, Anne; Urios, Laurent; Lesongeur, Francoise; Ollivier, Bernard; Querellou, Joel; Godfroy, Anne

    2005-01-01

    The microflora developing during a continuous enrichment culture from a hydrothermal chimney sample was investigated by molecular methods. The culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90 degrees C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus, Marinitoga, and Bacillus were detected through DGGE analysis of 16S rDNA. Addi...

  18. High molecular weight dissolved organic matter enrichment selects for methylotrophs in dilution to extinction cultures.

    Science.gov (United States)

    Sosa, Oscar A; Gifford, Scott M; Repeta, Daniel J; DeLong, Edward F

    2015-12-01

    The role of bacterioplankton in the cycling of marine dissolved organic matter (DOM) is central to the carbon and energy balance in the ocean, yet there are few model organisms available to investigate the genes, metabolic pathways, and biochemical mechanisms involved in the degradation of this globally important carbon pool. To obtain microbial isolates capable of degrading semi-labile DOM for growth, we conducted dilution to extinction cultivation experiments using seawater enriched with high molecular weight (HMW) DOM. In total, 93 isolates were obtained. Amendments using HMW DOM to increase the dissolved organic carbon concentration 4x (280 μM) or 10x (700 μM) the ocean surface water concentrations yielded positive growth in 4-6% of replicate dilutions, whereas <1% scored positive for growth in non-DOM-amended controls. The majority (71%) of isolates displayed a distinct increase in cell yields when grown in increasing concentrations of HMW DOM. Whole-genome sequencing was used to screen the culture collection for purity and to determine the phylogenetic identity of the isolates. Eleven percent of the isolates belonged to the gammaproteobacteria including Alteromonadales (the SAR92 clade) and Vibrio. Surprisingly, 85% of isolates belonged to the methylotrophic OM43 clade of betaproteobacteria, bacteria thought to metabolically specialize in degrading C1 compounds. Growth of these isolates on methanol confirmed their methylotrophic phenotype. Our results indicate that dilution to extinction cultivation enriched with natural sources of organic substrates has a potential to reveal the previously unsuspected relationships between naturally occurring organic nutrients and the microorganisms that consume them.

  19. Stable acetate production in extreme-thermophilic (70ºC) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

    NARCIS (Netherlands)

    Zhang, F.; Zhang, Y.; Ding, J.; Dai, K.; Van Loosdrecht, M.C.M.; Zeng, R.J.

    2014-01-01

    The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-th

  20. Persistence of Denitrifying Enzyme Activity in Dried Soils †

    OpenAIRE

    Smith, M. Scott; Parsons, Laura L.

    1985-01-01

    The effects of air drying soil on denitrifying enzyme activity, denitrifier numbers, and rates of N gas loss from soil cores were measured. Only 29 and 16% of the initial denitrifying enzyme activity in fresh, near field capacity samples of Maury and Donerail soils, respectively, were lost after 7 days of air drying. The denitrifying activity of bacteria added to soil and activity recently formed in situ were not stable during drying. When dried and moist soil cores were irrigated, evolution ...

  1. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part A-Monocyclic and Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-08-01

    Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene.

  2. Survey of Naegleria from Taiwan recreational waters using culture enrichment combined with PCR.

    Science.gov (United States)

    Huang, Shih-Wei; Hsu, Bing-Mu

    2011-08-01

    Naegleria is a free-living amoeba. Pathogenic Naegleria may pose a health risk to people who come in contact with recreational waters. Here, we used Naegleria culture enrichment with PCR to identify the Naegleria species and investigated the distribution of Naegleria spp. in recreational waters including spring water, stream water and raw domestic water in central and southern Taiwan. In this study, Naegleria spp. were detected in 19 (17.8%) of the water samples. The occurrence of Naegleria in raw domestic water was 28.6%, higher than in stream water (14.7%) and in spring water (6.5%). The most frequently identified species exhibiting the closest phylogenetic relationships to the isolates were N. australiensis (n=4) and N. canariensis (n=4), followed by N. clarki (n=3) and N. philippinensis (n=3); N. americana (n=2). N. lovaniensis, N. dobsoni, and N. gruberi were each detected once. The pathogenic species N. fowleri was not detected, probably due to the low incubation temperature; however, the isolates exhibiting the closest phylogenetic relationships to the pathogenic species in mice of PAM, N. australiensis and N. philippinensis, were found. Results of this survey suggest the distribution of Naegleria spp. excluding N. fowleri in recreational waters. It should be considered a potential threat for health associated with human activities in recreational waters.

  3. Diversity of reductive dehalogenase genes from environmental samples and enrichment cultures identified with degenerate primer PCR screens.

    Directory of Open Access Journals (Sweden)

    Laura Audrey Hug

    2013-11-01

    Full Text Available Reductive dehalogenases are the critical enzymes for anaerobic organohalide respiration, a microbial metabolic process that has been harnessed for bioremediation efforts to resolve chlorinated solvent contamination in groundwater and is implicated in the global halogen cycle. Reductive dehalogenase sequence diversity is informative for the dechlorination potential of the site or enrichment culture. A suite of degenerate PCR primers targeting a comprehensive curated set of reductive dehalogenase genes was designed and applied to twelve DNA samples extracted from contaminated and pristine sites, as well as six enrichment cultures capable of reducing chlorinated compounds to non-toxic end-products. The amplified gene products from four environmental sites and two enrichment cultures were sequenced using Illumina HiSeq, and the reductive dehalogenase complement of each sample determined. The results indicate that the diversity of the reductive dehalogenase gene family is much deeper than is currently accounted for: one-third of the translated proteins have less than 70% pairwise amino acid identity to database sequences. Approximately 60% of the sequenced reductive dehalogenase genes were broadly distributed, being identified in four or more samples, and often in previously sequenced genomes as well. In contrast, 17% of the sequenced reductive dehalogenases were unique, present in only a single sample and bearing less than 90% pairwise amino acid identity to any previously identified proteins. Many of the broadly distributed reductive dehalogenases are uncharacterized in terms of their substrate specificity, making these intriguing targets for further biochemical experimentation. Finally, comparison of samples from a contaminated site and an enrichment culture derived from the same site eight years prior allowed examination of the effect of the enrichment process.

  4. Passive markers as a low-cost method of enriching cultural visits on user’s demand

    Directory of Open Access Journals (Sweden)

    Anestis Koutsoudis

    2014-01-01

    Full Text Available The idea of enriching a cultural heritage visitor’s experience by employing mobile devices such as smartphones and tablets is an active research domain. This is mainly due to the worldwide user penetration of such devices along with their continuous hardware performance enhancement. This work presents the experience and feedback gained by one year of operation of an experimental information system that aims in enhancing the experience of a visitor on his/her demand. The evaluated system is based on the use case-scenario where the a mobile device is used to capture and decode passive markers (such as QR-codes that are located on facades of selected important buildings in the old town of Xanthi, Greece, in order to enrich the visitor’s experience through a broad context of historical and architectural information delivered over the Web.   Keywords: On-demand information, Passive marker, QR-code, Smartphone, Visit enrichment.

  5. Bacterial community analysis in chlorpyrifos enrichment cultures via DGGE and use of bacterial consortium for CP biodegradation.

    Science.gov (United States)

    Akbar, Shamsa; Sultan, Sikander; Kertesz, Michael

    2014-10-01

    The organophosphate pesticide chlorpyrifos (CP) has been used extensively since the 1960s for insect control. However, its toxic effects on mammals and persistence in environment necessitate its removal from contaminated sites, biodegradation studies of CP-degrading microbes are therefore of immense importance. Samples from a Pakistani agricultural soil with an extensive history of CP application were used to prepare enrichment cultures using CP as sole carbon source for bacterial community analysis and isolation of CP metabolizing bacteria. Bacterial community analysis (denaturing gradient gel electrophoresis) revealed that the dominant genera enriched under these conditions were Pseudomonas, Acinetobacter and Stenotrophomonas, along with lower numbers of Sphingomonas, Agrobacterium and Burkholderia. Furthermore, it revealed that members of Bacteroidetes, Firmicutes, α- and γ-Proteobacteria and Actinobacteria were present at initial steps of enrichment whereas β-Proteobacteria appeared in later steps and only Proteobacteria were selected by enrichment culturing. However, when CP-degrading strains were isolated from this enrichment culture, the most active organisms were strains of Acinetobacter calcoaceticus, Pseudomonas mendocina and Pseudomonas aeruginosa. These strains degraded 6-7.4 mg L(-1) day(-1) of CP when cultivated in mineral medium, while the consortium of all four strains degraded 9.2 mg L(-1) day(-1) of CP (100 mg L(-1)). Addition of glucose as an additional C source increased the degradation capacity by 8-14 %. After inoculation of contaminated soil with CP (200 mg kg(-1)) disappearance rates were 3.83-4.30 mg kg(-1) day(-1) for individual strains and 4.76 mg kg(-1) day(-1) for the consortium. These results indicate that these organisms are involved in the degradation of CP in soil and represent valuable candidates for in situ bioremediation of contaminated soils and waters.

  6. Vertical Distribution of Soil Denitrifying Communities in a Wet Sclerophyll Forest under Long-Term Repeated Burning.

    Science.gov (United States)

    Liu, Xian; Chen, Chengrong; Wang, Weijin; Hughes, Jane M; Lewis, Tom; Hou, Enqing; Shen, Jupei

    2015-11-01

    Soil biogeochemical cycles are largely mediated by microorganisms, while fire significantly modifies biogeochemical cycles mainly via altering microbial community and substrate availability. Majority of studies on fire effects have focused on the surface soil; therefore, our understanding of the vertical distribution of microbial communities and the impacts of fire on nitrogen (N) dynamics in the soil profile is limited. Here, we examined the changes of soil denitrification capacity (DNC) and denitrifying communities with depth under different burning regimes, and their interaction with environmental gradients along the soil profile. Results showed that soil depth had a more pronounced impact than the burning treatment on the bacterial community size. The abundance of 16S rRNA and denitrification genes (narG, nirK, and nirS) declined exponentially with soil depth. Surprisingly, the nosZ-harboring denitrifiers were enriched in the deeper soil layers, which was likely to indicate that the nosZ-harboring denitrifiers could better adapt to the stress conditions (i.e., oxygen deficiency, nutrient limitation, etc.) than other denitrifiers. Soil nutrients, including dissolved organic carbon (DOC), total soluble N (TSN), ammonium (NH(4)(+)), and nitrate (NO(3)(-)), declined significantly with soil depth, which probably contributed to the vertical distribution of denitrifying communities. Soil DNC decreased significantly with soil depth, which was negligible in the depths below 20 cm. These findings have provided new insights into niche separation of the N-cycling functional guilds along the soil profile, under a varied fire disturbance regime.

  7. Vertical Distribution of Soil Denitrifying Communities in a Wet Sclerophyll Forest under Long-Term Repeated Burning.

    Science.gov (United States)

    Liu, Xian; Chen, Chengrong; Wang, Weijin; Hughes, Jane M; Lewis, Tom; Hou, Enqing; Shen, Jupei

    2015-11-01

    Soil biogeochemical cycles are largely mediated by microorganisms, while fire significantly modifies biogeochemical cycles mainly via altering microbial community and substrate availability. Majority of studies on fire effects have focused on the surface soil; therefore, our understanding of the vertical distribution of microbial communities and the impacts of fire on nitrogen (N) dynamics in the soil profile is limited. Here, we examined the changes of soil denitrification capacity (DNC) and denitrifying communities with depth under different burning regimes, and their interaction with environmental gradients along the soil profile. Results showed that soil depth had a more pronounced impact than the burning treatment on the bacterial community size. The abundance of 16S rRNA and denitrification genes (narG, nirK, and nirS) declined exponentially with soil depth. Surprisingly, the nosZ-harboring denitrifiers were enriched in the deeper soil layers, which was likely to indicate that the nosZ-harboring denitrifiers could better adapt to the stress conditions (i.e., oxygen deficiency, nutrient limitation, etc.) than other denitrifiers. Soil nutrients, including dissolved organic carbon (DOC), total soluble N (TSN), ammonium (NH(4)(+)), and nitrate (NO(3)(-)), declined significantly with soil depth, which probably contributed to the vertical distribution of denitrifying communities. Soil DNC decreased significantly with soil depth, which was negligible in the depths below 20 cm. These findings have provided new insights into niche separation of the N-cycling functional guilds along the soil profile, under a varied fire disturbance regime. PMID:26066514

  8. Assessing the influence of CH4 concentration during culture enrichment on the biodegradation kinetics and population structure.

    Science.gov (United States)

    López, Juan C; Quijano, Guillermo; Pérez, Rebeca; Muñoz, Raúl

    2014-12-15

    Methanotrophic communities were enriched in three stirred tank reactors continuously supplied with CH4-laden air at 20, 2 and 0.2 gCH4 m(-3) in order to evaluate the influence of CH4 concentration on the biodegradation kinetics, population structure and potential polyhydroxyalkanoate production under sequential nitrogen limitations. The population structure of the enriched cultures, dominated by type I methanotrophs, was influenced by CH4 concentration. No significant correlation between CH4 concentration and the maximum specific degradation rate (qmax) or the half-saturation constant (KS) was recorded, microorganisms enriched at 2 gCH4 m(-3) presenting the highest qmax and those enriched at 20 and 0.2 gCH4 m(-3) exhibiting the lowest KS. Maximum polyhydroxybutyrate (PHB) contents of 1.0% and 12.6% (w/w) were achieved at 20 and 2 g CH4 m(-3), respectively. Polyhydroxyvalerate (PHV) was also detected at PHV:PHB ratios of up to 12:1 and 4:1 in the communities enriched at 20 and 0.2 gCH4 m(-3), respectively.

  9. Diversity of reductive dehalogenase genes from environmental samples and enrichment cultures identified with degenerate primer PCR screens

    OpenAIRE

    LauraAudreyHug; ElizabethAnneEdwards

    2013-01-01

    Reductive dehalogenases are the critical enzymes for anaerobic organohalide respiration, a microbial metabolic process that has been harnessed for bioremediation efforts to resolve chlorinated solvent contamination in groundwater and is implicated in the global halogen cycle. Reductive dehalogenase sequence diversity is informative for the dechlorination potential of the site or enrichment culture. A suite of degenerate PCR primers targeting a comprehensive curated set of reductive dehaloge...

  10. Potential effect of matrix stiffness on the enrichment of tumor initiating cells under three-dimensional culture conditions.

    Science.gov (United States)

    Liu, Chang; Liu, Yang; Xu, Xiao-xi; Wu, Hao; Xie, Hong-guo; Chen, Li; Lu, Ting; Yang, Li; Guo, Xin; Sun, Guang-wei; Wang, Wei; Ma, Xiao-jun; He, Xin

    2015-01-01

    Cancer stem cell (CSC) or tumor initiating cell (TIC) plays an important role in tumor progression and metastasis. Biophysical forces in tumor microenvironment have an important effect on tumor formation and development. In this study, the potential effect of matrix stiffness on the biological characteristics of human head and neck squamous cell carcinoma (HNSCC) TICs, especially the enrichment of HNSCC TICs, was investigated under three-dimensional (3D) culture conditions by means of alginate gel (ALG) beads with different matrix stiffnesses. ALG beads with soft (21 kPa), moderate (70 kPa) and hard (105 kPa) stiffness were generated by changing alginate concentration. It was found that significant HNSCC TIC enrichment was achieved in the ALG beads with moderate matrix stiffness (70 kPa). The gene expression of stemness markers Oct3/4 and Nanog, TIC markers CD44 and ABCG2 was enhanced in cells under this moderate (70 kPa) stiffness. HNSCC TIC proportion was also highly enriched under moderate matrix stiffness, accompanying with higher tumorigenicity, metastatic ability and drug resistance. And it was also found that the possible molecular mechanism underlying the regulated TIC properties by matrix stiffness under 3D culture conditions was significantly different from 2D culture condition. Therefore, the results achieved in this study indicated that 3D biophysical microenvironment had an important effect on TIC characteristics and alginate-based biomimetic scaffolds could be utilized as a proper platform to investigate the interaction between tumor cells and 3D microenvironment.

  11. Culture and Phosphorus Removal Property of Granular Sludge for Denitrifying Phosphorus Removal%反硝化除磷颗粒污泥的培养与除磷性能

    Institute of Scientific and Technical Information of China (English)

    李军; 张宇坤; 韦甦; 王亚宜; 马骁; 彭永臻

    2012-01-01

    The granular sludge for denitrifying phosphorus removal is successfully formed in a sequencing batch reactor (SBR) fed with synthetic wastewater, by controlling the operational modes of anaerobic/ anoxic/aerobic, anoxie addition of the nitrate, and selection pressure. The granular sludge turns into ashape with a diameter of 0.3 to 0.5 mm, and sludge volume index (SVI) and mixed solid (MLSS) are maintained at 45 mL/g and 4 000 rag/L, respectively, during the The granular sludge for the denitrifying phosphorus removal also shows a good nutrient re steady moval suspended operation. capability,with the COD, ammonia nitrogen and phosphorus removal effieiencies of 88%, 96% and 90%, respectively. The fate of phosphorus and the X-ray diffraction test results suggest the existence of granular sludge phosphate precipitation phosphorus removal phenomena. Granular sludge for the denitrifyingphosphorus removal in the experiment uses biological phosphorus removal, and it also has phosphorus removal through phosphate precipitation in granular sludge.%摘要:以普通絮状污泥为接种污泥,人工配制生活污水,采用厌氧/缺氧/好氧的运行方式,通过在缺氧段投加硝酸盐氮和控制选择压,经98d的培养与调整在SBR中获得具有反硝化除磷功能的颗粒污泥.稳定运行的颗粒污泥粒径主要在0.3-0.5mm,SVI约为45mL/g,p(MLSS)约为4000mg/L.具有反硝化除磷功能的颗粒污泥对COD、氨氮和磷酸盐的去除率分别可达88%、96%和90%.通过分析磷的去向及X射线衍射检测结果可知存在颗粒污泥的磷酸盐沉淀除磷现象.培养的反硝化除磷颗粒污泥除生物除磷外,还具有磷酸盐固化于污泥颗粒方式除磷。

  12. Enrichment strategy to select functional consortium from mixed cultures: Consortium from rumen liquor for simultaneous cellulose degradation and hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Aijie; Ren, Nanqi [State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); School of Environmental and Municipal Engineering, Harbin Institute of Technology, Harbin 150090 (China); Gao, Lingfang; Xu, Jifei; Liu, Chong; Lee, Duu-Jong [School of Environmental and Municipal Engineering, Harbin Institute of Technology, Harbin 150090 (China)

    2010-12-15

    Strain isolation using conventional roll tube/plating technique is time consuming and is able to culture in vitro only a small fraction of existing microbes in a natural microflora. This paper proposed a simple and rapid method to select the as-simple-as-possible biological consortium by serially diluting the original mixed culture. The diluted which remains, while the one diluted in serial loses the target function, is defined as the functional consortium of the original mixed culture. Since the microbial structure and the reaction pathway incorporated with the functional consortium is much simpler than its original mother liquor, detailed analysis on the strain interaction is possible without the risk of losing key functional strains as often caused from conventional isolation method. The rumen liquor that can degrade cellulose and produce hydrogen is used as a demonstration example. A ''rumen cellulose-degrading bacterial consortium'' (RCBC) was identified using the proposed enrichment strategy. (author)

  13. Biodiversity within hot spring microbial mat communities: molecular monitoring of enrichment cultures

    Science.gov (United States)

    Ward, D. M.; Santegoeds, C. M.; Nold, S. C.; Ramsing, N. B.; Ferris, M. J.; Bateson, M. M.

    1997-01-01

    We have begun to examine the basis for incongruence between hot spring microbial mat populations detected by cultivation or by 16S rRNA methods. We used denaturing gradient gel electrophoresis (DGGE) to monitor enrichments and isolates plated therefrom. At near extincting inoculum dilutions we observed Chloroflexus-like and cyanobacterial populations whose 16S rRNA sequences have been detected in the 'New Pit' Spring Chloroflexus mat and the Octopus Spring cyanobacterial mat. Cyanobacterial populations enriched from 44 to 54 degrees C and 56 to 63 degrees C samples at near habitat temperatures were similar to those previously detected in mat samples of comparable temperatures. However, a lower temperature enrichment from the higher temperature sample selected for the populations found in the lower temperature sample. Three Thermus populations detected by both DGGE and isolation exemplify even more how enrichment may bias our view of community structure. The most abundant population was adapted to the habitat temperature (50 degrees C), while populations adapted to 65 degrees C and 70 degrees C were 10(2)- and 10(4)-fold less abundant, respectively. However, enrichment at 70 degrees C favored the least abundant strain. Inoculum dilution and incubation at the habitat temperature favored the more numerically relevant populations. We enriched many other aerobic chemoorganotrophic populations at various inoculum dilutions and substrate concentrations, most of whose 16S rRNA sequences have not been detected in mats. A common feature of numerically relevant cyanobacterial, Chloroflexus-like and aerobic chemorganotrophic populations, is that they grow poorly and resist cultivation on solidified medium, suggesting plating bias, and that the medium composition and incubation conditions may not reflect the natural microenvironments these populations inhabit.

  14. Conversion of methane-derived carbon and microbial community in enrichment cultures in response to O2 availability.

    Science.gov (United States)

    Wei, Xiao-Meng; He, Ruo; Chen, Min; Su, Yao; Ma, Ruo-Chan

    2016-04-01

    Methanotrophs not only play an important role in mitigating CH4 emissions from the environment, but also provide a large quantity of CH4-derived carbon to their habitats. In this study, the distribution of CH4-derived carbon and microbial community was investigated in a consortium enriched at three O2 tensions, i.e., the initial O2 concentrations of 2.5 % (LO-2), 5 % (LO-1), and 21 % (v/v) (HO). The results showed that compared with the O2-limiting environments (2.5 and 5 %), more CH4-derived carbon was converted into CO2 and biomass under the O2 sufficient condition (21 %). Besides biomass and CO2, a high conversion efficiency of CH4-derived carbon to dissolved organic carbon was detected in the cultures, especially in LO-2. Quantitative PCR and Miseq sequencing both showed that the abundance of methanotroph increased with the increasing O2 concentrations. Type II methanotroph Methylocystis dominated in the enrichment cultures, accounting for 54.8, 48.1, and 36.9 % of the total bacterial 16S rRNA gene sequencing reads in HO, LO-1, and LO-2, respectively. Methylotrophs, mainly including Methylophilus, Methylovorus, Hyphomicrobium, and Methylobacillus, were also abundant in the cultures. Compared with the O2 sufficient condition (21 %), higher microbial biodiversity (i.e., higher Simpson and lower Shannon indexes) was detected in LO-2 enriched at the initial O2 concentration of 2.5 %. These findings indicated that compared with the O2 sufficient condition, more CH4-derived carbon was exuded into the environments and promoted the growth of non-methanotrophic microbes in O2-limiting environments. PMID:26728286

  15. Effects of carbon sources on the enrichment of halophilic polyhydroxyalkanoate-storing mixed microbial culture in an aerobic dynamic feeding process

    Science.gov (United States)

    Cui, You-Wei; Zhang, Hong-Yu; Lu, Peng-Fei; Peng, Yong-Zhen

    2016-08-01

    Microbial polyhydroxyalkanoate (PHA) production serves as a substitute for petroleum-based plastics. Enriching mixed microbial cultures (MMCs) with the capacity to store PHA is a key precursor for low-cost PHA production. This study investigated the impact of carbon types on enrichment outcomes. Three MMCs were separately fed by acetate sodium, glucose, and starch as an enriching carbon source, and were exposed to long-term aerobic dynamic feeding (ADF) periods. The PHA production capacity, kinetics and stoichiometry of the enrichments, the PHA composition, and the microbial diversity and community composition were explored to determine carbon and enrichment correlations. After 350-cycle enriching periods under feast-famine (F-F) regimes, the MMCs enriched by acetate sodium and glucose contained a maximum PHA content of 64.7% and 60.5% cell dry weight (CDW). The starch-enriched MMC only had 27.3% CDW of PHA. High-throughput sequencing revealed that non-PHA bacteria survived alongside PHA storing bacteria, even under severe F-F selective pressure. Genus of Pseudomonas and Stappia were the possible PHA accumulating bacteria in acetate-enriched MMC. Genus of Oceanicella, Piscicoccus and Vibrio were found as PHA accumulating bacteria in glucose-enriched MMC. Vibrio genus was the only PHA accumulating bacteria in starch-enriched MMC. The community diversity and composition were regulated by the substrate types.

  16. Effects of CO2 enrichment and nutrients supply intermittency on batch cultures of Isochrysis galbana.

    Science.gov (United States)

    Picardo, Marta C; de Medeiros, José Luiz; Araújo, Ofélia de Queiroz F; Chaloub, Ricardo Moreira

    2013-09-01

    Aiming at enhanced performance to increase economic feasibility of microalgae based processes, Isochrysis galbana was grown in three modes of cultivation: batch, intermittent fed batch and semi-continuous. The batch mode was conducted under two regimes of aeration: conventional aeration and CO2 enriched aeration (5% v/v in air). Increased biomass productivity without significant impact on lipid accumulation was observed for CO2 enriched aeration relatively to cultivation aerated with air only. The intermittent fed batch cultivation policy was proven to be useful for lipid accumulation, increasing the lipid content by 19.8%. However, the semi-continuous mode resulted in higher productivity due to increased biomass concentration; the biomass productivity reached 0.51 g/(Ld). Fluorescence measurements were performed; the calculated low electron transport rate showed the need to increase the irradiance. The results showed that I. galbana can be grown in semi-continuous condition at high levels of biomass productivity.

  17. Passport to Cultural Enrichment: The Peace Corps World Wise Schools Experience

    Science.gov (United States)

    Carano, Kenneth T.

    2009-01-01

    In recent studies, youths in the United States have demonstrated a remarkable lack of cultural literacy. As the world is becoming increasingly interconnected, it is imperative that students enhance their understanding of other cultures. A classroom correspondence match with a Peace Corps volunteer through the Coverdell Peace Corps World Wise…

  18. Signatures of Autotrophic and Heterotrophic Metabolic Activity in Enrichment Cultures from a Sulphur Oxidizing Acid Mine Site

    Science.gov (United States)

    Slater, G. F.; Bernier, L.; Cowie, B. R.; Warren, L. A.

    2006-12-01

    Delineating the role of microorganisms in geochemical processes of interest in natural environments requires the development of tools that provide the ability to distinguish amongst microbial activity associated with different metabolic guilds. The gap between phylogenetic characterization and phenotypic understanding remains, underscoring the need to consider alternative methods. Compound specific analysis of cellular components has the potential to differentiate between active metabolic processes supporting microbial communities and may be especially useful in extreme environments. The goal of this study was to determine whether the phospholipids fatty acid (PLFA) distribution and isotopic signatures associated with autotrophs and heterotrophs enriched from an acid mine drainage (AMD) system differed, and further whether natural consortial autotrophic isolates showed similar signatures to autotrophic pure strains of Acidithiobacillus ferrooxidans and A. thiooxidans. Two distinct initial enrichments with tetrathionate and CO2 yielded primarily autotrophic (95%) Acidithiobaccillus spp. sulphur oxidizing communities. The remaining microbial members of theses enrichments (subculture of the consortial isolates in a medium amended with glucose but without tetrathionate selectively resulted in their visible growth. PLFA profiles and δ13C signatures from autotrophic (1) natural enrichments, pure cultures of (2) A. ferrooxidans and (3) A. thiooxidans were similar, but collectively differed from those of the natural heterotrophic enrichment cultures. The PLFA profiles for the heterotrophic communities were made up of primarily (88-99%) C16:0 and two isomers of C18:1. In contrast, the autotrophic communities had high proportions of C16:1 (up to 18%) as well as cyclo C17 and cyclo C19 PLFA that combined comprised 18 to 58% of the observed PLFA. The δ13C signatures of the PLFA also differed strongly between the two trophic levels. The δ13C of the autotrophic PLFA, - 24 to

  19. The Control of Microcystis spp. Bloom by Combining Indigenous Denitrifying Bacteria From Sutami Reservoir with Fimbristylis globulosa and Vetiveria zizanoides

    OpenAIRE

    Bayu Agung Prahardika; Catur Retnaningdyah; Suharjono

    2013-01-01

    The purpose of this research is to know the ability of polyculture macrophyte (Fimbristylis globulosa and Vetiveria zizanoides) and the combination of both with consortium of indigenous denitrifying bacteria from Sutami reservoir that was added by Microcystis spp. or not to reduce the concentration of nitrate, dissolved phosphate and the carrying capacity of Microcystis spp. The experiment was done in a medium filled up with Sutami reservoir water enriched with 16 ppm of nitrate and 0.4 ppm o...

  20. Applicability of a Lactobacillus amylovorus strain as co-culture for natural folate bio-enrichment of fermented milk.

    Science.gov (United States)

    Laiño, Jonathan Emiliano; Juarez del Valle, Marianela; Savoy de Giori, Graciela; LeBlanc, Jean Guy Joseph

    2014-11-17

    The ability of 55 strains from different Lactobacillus species to produce folate was investigated. In order to evaluate folic acid productivity, lactobacilli were cultivated in the folate-free culture medium (FACM). Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were distinctive features of individual strains. Lactobacillus amylovorus CRL887 was selected for further studies because of its ability to produce significantly higher concentrations of vitamin (81.2 ± 5.4 μg/L). The safety of this newly identified folate producing strain was evaluated through healthy experimental mice. No bacterial translocation was detected in liver and spleen after consumption of CRL887 during 7 days and no undesirable side effects were observed in the animals that received this strain. This strain in co-culture with previously selected folate producing starter cultures (Lactobacillus bulgaricus CRL871, and Streptococcus thermophilus CRL803 and CRL415) yielded a yogurt containing high folate concentrations (263.1 ± 2.4 μg/L); a single portion of which would provide 15% of the recommended dietary allowance. This is the first report where a Lactobacillus amylovorus strain was successfully used as co-culture for natural folate bio-enrichment of fermented milk.

  1. The Control of Microcystis spp. Bloom by Combining Indigenous Denitrifying Bacteria From Sutami Reservoir with Fimbristylis globulosa and Vetiveria zizanoides

    Directory of Open Access Journals (Sweden)

    Bayu Agung Prahardika

    2013-04-01

    Full Text Available The purpose of this research is to know the ability of polyculture macrophyte (Fimbristylis globulosa and Vetiveria zizanoides and the combination of both with consortium of indigenous denitrifying bacteria from Sutami reservoir that was added by Microcystis spp. or not to reduce the concentration of nitrate, dissolved phosphate and the carrying capacity of Microcystis spp. The experiment was done in a medium filled up with Sutami reservoir water enriched with 16 ppm of nitrate and 0.4 ppm of phosphate. The denitrifying bacteria used in this research were DR-14, DU-27-1, DU-30-1, DU-30-2, TA-8 and DU-27-4 isolated from Sutami reservoir. The treatments were incubated within 15 days. Microcystis spp. abundance was calculated every day, but the measurement of the concentration of nitrate and dissolved phosphate was done every six days. The results showed that both treatment and the combination of both macrophytes with a consortium of denitrifying indigenous bacteria were added or not either Microcystis able to reduce nitrate at 99% and 93-99% orthophosphoric. The combination of macrophytes with denitrifying indigenous bacterial consortium from Sutami reservoir was able to inhibit the carrying capacity of Microcystis spp. highest up to 47.87%. They could also significantly reduce the abundance of Microcystis from 107 cells/mL in earlier days of the treatment into 0.35x104 cells/mL after fifteen days of incubation.

  2. IDENTIFICATION AND ECOPHYSIOLOGY OF ACTIVE DENITRIFIERS IN ACTIVATED SLUDGE

    DEFF Research Database (Denmark)

    Hansen, Aviaja Anna; Le-Quy, Vang; Nielsen, Kåre Lehmann;

    and when external carbon sources were supplemented to the activated sludge the composition of the denitrifying communities was significantly affected. Transcriptome profiling provided detailed insight in the metabolic pathways in several of the active denitrifiers in activated sludge. In conclusion...... reactor studies. To obtain better identification of active denitrifying communities in full-scale wastewater treatment plants (WWTPs) we applied DNA-SIP with 13C-labelled substrates, and RT-PCR of expressed denitrification genes (nirS, nirK and nosZ) upon various substrate-inductions. To come around...... were determined with quantitative FISH, while their active metabolic pathways were investigated directly in activated sludge with a tag-based metatranscriptomic approach under acetate-utilizing and denitrifying conditions. The different methods revealed a majority of denitrifiers in all WWTPs belonging...

  3. Comparative genomics of "Dehalococcoides ethenogenes" 195 and an enrichment culture containing unsequenced "Dehalococcoides" strains.

    Science.gov (United States)

    West, Kimberlee A; Johnson, David R; Hu, Ping; DeSantis, Todd Z; Brodie, Eoin L; Lee, Patrick K H; Feil, Helene; Andersen, Gary L; Zinder, Stephen H; Alvarez-Cohen, Lisa

    2008-06-01

    Tetrachloroethene (PCE) and trichloroethene (TCE) are prevalent groundwater contaminants that can be completely reductively dehalogenated by some "Dehalococcoides" organisms. A Dehalococcoides-organism-containing microbial consortium (referred to as ANAS) with the ability to degrade TCE to ethene, an innocuous end product, was previously enriched from contaminated soil. A whole-genome photolithographic microarray was developed based on the genome of "Dehalococcoides ethenogenes" 195. This microarray contains probes designed to hybridize to >99% of the predicted protein-coding sequences in the strain 195 genome. DNA from ANAS was hybridized to the microarray to characterize the genomic content of the ANAS enrichment. The microarray results revealed that the genes associated with central metabolism, including an apparently incomplete carbon fixation pathway, cobalamin-salvaging system, nitrogen fixation pathway, and five hydrogenase complexes, are present in both strain 195 and ANAS. Although the gene encoding the TCE reductase, tceA, was detected, 13 of the 19 reductive dehalogenase genes present in strain 195 were not detected in ANAS. Additionally, 88% of the genes in predicted integrated genetic elements in strain 195 were not detected in ANAS, consistent with these elements being genetically mobile. Sections of the tryptophan operon and an operon encoding an ABC transporter in strain 195 were also not detected in ANAS. These insights into the diversity of Dehalococcoides genomes will improve our understanding of the physiology and evolution of these bacteria, which is essential in developing effective strategies for the bioremediation of PCE and TCE in the environment. PMID:18359838

  4. Atrazine biodegradation efficiency, metabolite detection, and trzD gene expression by enrichment bacterial cultures from agricultural soil

    Institute of Scientific and Technical Information of China (English)

    Robinson David Jebakumar SOLOMON; Amit KUMAR; Velayudhan SATHEEJA SANTHI

    2013-01-01

    Atrazine is a selective herbicide used in agricultural fields to control the emergence of broadleaf and grassy weeds. The persistence of this herbicide is influenced by the metabolic action of habituated native microor-ganisms. This study provides information on the occurrence of atrazine mineralizing bacterial strains with faster me-tabolizing ability. The enrichment cultures were tested for the biodegradation of atrazine by high-performance liquid chromatography (HPLC) and mass spectrometry. Nine cultures JS01.Deg01 to JS09.Deg01 were identified as the degrader of atrazine in the enrichment culture. The three isolates JS04.Deg01, JS07.Deg01, and JS08.Deg01 were identified as efficient atrazine metabolizers. Isolates JS04.Deg01 and JS07.Deg01 produced hydroxyatrazine (HA) N-isopropylammelide and cyanuric acid by dealkylation reaction. The isolate JS08.Deg01 generated deethylatrazine (DEA), deisopropylatrazine (DIA), and cyanuric acid by N-dealkylation in the upper degradation pathway and later it incorporated cyanuric acid in their biomass by the lower degradation pathway. The optimum pH for degrading atrazine by JS08.Deg01 was 7.0 and 16S rDNA phylogenetic typing identified it as Enterobacter cloacae strain JS08.Deg01. The highest atrazine mineralization was observed in case of isolate JS08.Deg01, where an ample amount of trzD mRNA was quantified at 72 h of incubation with atrazine. Atrazine bioremediating isolate E. cloacae strain JS08.Deg01 could be the better environmental remediator of agricultural soils and the crop fields contaminated with atrazine could be the source of the efficient biodegrading microbial strains for the environmental cleanup process.

  5. Biodegradation of Chlorpyrifos by Pseudomonas Resinovarans Strain AST2.2 Isolated from Enriched Cultures.

    Directory of Open Access Journals (Sweden)

    Anish Sharma*,

    2016-04-01

    Full Text Available A bacterial strain AST2.2 with chlorpyrifos degrading ability was isolated by enrichment technique from apple orchard soil with previous history of chlorpyrifos use. Based on the morphological, biochemical tests and 16S rRNA sequence analysis, AST2.2 strain was identified as Pseudomonas resinovarans. The strain AST2.2 utilized chlorpyrifos as the sole source of carbon and energy. This strain exhibited growth upto 400mg/l concentration of chlorpyrifos and exhibited high extracellular organophosphorus hydrolase (OPH activity. Gas chromatography-flame ionization detector (GC-FID studies revealed that Pseudomonas resinovarans AST2.2 degraded 43.90 % of chlorpyrifos (400 mg/l within 96 hrs. Intermediates of chlorpyrifos degradation were identified using GC-MS. This strain have potential to degrade chlorpyrifos and thus can be used for bioremediation and ecological restoration of sites contaminated with chlorpyrifos.

  6. Growth and nitrate reduction of Beggiatoa filaments studied in enrichment cultures

    DEFF Research Database (Denmark)

    Kamp, Anja

    in oxygen-sulphide gradient tubes, and observed with a camera system. Growth mode, breakage, and movement directions of Beggiatoa filaments were documented via time-lapse video recording. The initial doubling time of cells was 15.7 ±1.3 h (mean ±SD; room temperature). Filaments grew up to an average length......In this thesis, several aspects of the gliding, filamentous, colourless sulphur bacteria Beggiatoa were investigated. The first part of this thesis addressed the growth mode, breakage of filaments for multiplication, and movement directions of filaments of Beggiatoa. Marine Beggiatoa were enriched...... sediments, and affect the benthic sulphur cycle. In addition, Beggiatoa may influence the nitrogen cycle when they use nitrate anaerobically as an alternative electron acceptor in place of oxygen. The ability of freshwater and marine Beggiatoa to oxidise sulphide anaerobically with nitrate has been studied...

  7. Real-time PCR detection of Campylobacter spp.: A comparison toclassic culturing and enrichment

    NARCIS (Netherlands)

    Boer, P. de; Rahaoui, H.; Leer, R.J.; Montijn, R.C.; Vossen, J.M.B.M. van der

    2015-01-01

    The major disadvantage of the current gold standard for detection of the food pathogen Campylobacter, i.e. culturing, is the lengthy procedure. In this study we assessed the use of real-time PCR for detection of Campylobacter. To this end, 926 poultry samples, taken from transport containers and bro

  8. Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

    Science.gov (United States)

    Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

    2014-06-01

    The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 +/- 0.06, 1.0 +/- 0.13 and 0.4 +/- 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.

  9. Effects of Culture Media and Light Intensity on in vitro Growth of Oncidium under CO2 Enrichment Condition

    Institute of Scientific and Technical Information of China (English)

    He Songlin; Pan Huitang; Yang Qiusheng; Kong Dezheng; Zhang Qixiang; Michio Tanaka

    2003-01-01

    The effects of culture media and light intensity on in vitro growth of Oncidium 'Aloha Iwanga' were investigated under CO2 enrichment condition. Height, fresh and dry weight of the Oncidium seedlings were measured, and the leaf number per plant, shoot number per plant, leaf width and leaf chlorophyll content were also investigated. The results were as follows: 1) The seedling height, fresh and dry weight, leaf number per plant, leaf width and leaf chlorophyll content of the shoots growing on MS complete culture medium were higher than those on 1/2MS, VW and 1/2VW media. The root number per plant and ratio of dry matter of the seedlings cultured on 1/2MS and 1/2VW media were higher than those on MS and VW; 2) The seedling height, fresh weight, dry weight, dry matter ratio and leaf chlorophyll content, leaf length, leaf width, root length, leaf number per plant, root number per plant of seedlings of Oncidium growing under 4 500 lx and 1 700 lx were higher than those under 750 lx. However, there was no significant difference in those growth parameters mentioned above while dealing with 4 500 lx and 1 700 lx except for the seedling height. Nevertheless, the leaf color of plants under 4 500 lx was lighter and the leaves of the lower parts became yellowish in comparison with those growing under 1 700 lx.

  10. Nicotine suppresses lipopolysaccharide-induced release of interleukin-6 in mixed glia and microglia-enriched cultures

    Institute of Scientific and Technical Information of China (English)

    Zhihua Li; Qingzan Zhao; Hua Zhang; Xiuhua Ren; Mingfu Zhou; Weidong Zang

    2011-01-01

    Inflammation plays an important role in the pathogenesis of Parkinson's disease (PD) through the over-activation of microglia.Epidemiological studies show that smoking is associated with a lower incidence of PD.This study hypothesized that the neuroprotective effect of nicotine is mediated by modulating the activation of microglia via cytokine release.This study found that nicotine pretreatment suppressed the lipopolysaccharide-induced inflammatory reaction in the nervous system, especially microglia activation and interleukin-6 production.The inhibitory effects of 100 pmol/L nicotine were stronger compared with 1 and 10 pmol/L nicotine.These findings indicate that nicotine significantly decreases the production of proinflammatory interleukin-6 in mixed glia or microglia-enriched cultures, and plays an inhibitory effect on the lipopolysaccharide-induced inflammatory reaction.

  11. Biopolymer Production by Bacterial Enrichment Cultures Using Non-Fermented Substrates

    OpenAIRE

    Moralejo Gárate, H.

    2014-01-01

    Polyhydroxyalkanotes (PHAs) are naturally occurring polymers synthesized by a wide range of microorganisms. Their physiological role is to act as carbon and energy reserves, and their mechanical and physical properties are similar to those of petrochemical plastics. PHAs can be synthesized from renewable materials and they are biodegradable. Considering these properties, PHAs are commonly known as bioplastics. Commercial processes for the production of PHA are based on the use of pure culture...

  12. Production of polyhydroxyalkanoates from fermented sugar cane molasses by a mixed culture enriched in glycogen accumulating organisms.

    Science.gov (United States)

    Bengtsson, Simon; Pisco, Ana R; Reis, Maria A M; Lemos, Paulo C

    2010-02-01

    Batch production of polyhydroxyalkanoates (PHAs) under aerobic conditions by an open mixed culture enriched in glycogen accumulating organisms (GAOs) with fermented sugar cane molasses as substrate was studied. The produced polymers contained five types of monomers, namely 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylbutyrate (3H2MB), 3-hydroxy-2-methylvalerate (3H2MV) and the medium chain length monomer 3-hydroxyhexanoate (3HHx). With fermented molasses as substrate, PHA was produced under concurrent consumption of stored glycogen with yields of 0.47-0.66 C-mol PHA per C-mol of total carbon substrate and with rates up to 0.65 C-mol/C-molX h. In order to investigate the role of glycogen during aerobic PHA accumulation in GAOs, synthetic single volatile fatty acids (VFAs) were used as substrates and it was found that the fate of glycogen was dependent on the type of VFA being consumed. Aerobic PHA accumulation occurred under concurrent glycogen consumption with acetate as substrate and under minor concurrent glycogen production with propionate as substrate. With butyrate and valerate as substrates, PHA accumulation occurred with the glycogen pool unaffected. The composition of the PHA was dependent on the VFA composition of the fermented molasses and was 56-70 mol-% 3HB, 13-43 mol-% 3HV, 1-23 mol-% 3HHx and 0-2 mol-% 3H2MB and 3H2MV. The high polymer yields and production rates suggest that enrichment of GAOs can be a fruitful strategy for mixed culture production of PHA from waste substrates. PMID:19958801

  13. Chronic impact of sulfamethoxazole on the metabolic activity and composition of enriched nitrifying microbial culture.

    Science.gov (United States)

    Katipoglu-Yazan, Tugce; Merlin, Christophe; Pons, Marie-Noëlle; Ubay-Cokgor, Emine; Orhon, Derin

    2016-09-01

    This study investigated the chronic impact of sulfamethoxazole (SMX) on activated sludge sustaining an enriched nitrifying biomass. For this purpose, a laboratory scale fill and draw reactor was operated with 100 mg COD/L of peptone mixture and 50 mg N/L of ammonia at a sludge age of 15 days. Additionally, the biomass was exposed to a daily SMX dose of 50 mg/L once the reactor reached steady-state conditions. The reactor performance and microbial composition were monitored for 37 days with conventional parameters and molecular techniques based on the gene for ammonia monooxygenase subunit A (amoA) and the prokaryotic 16S rRNA gene. Denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene cloning analyses suggested a microbial community change concurrent with the addition of SMX. Specifically, quantitative polymerase chain reaction analyses (qPCR/RT-qPCR) revealed a significant reduction in the levels and activity of ammonia oxidizing bacteria (AOB). However, the acclimation period ended with high amoA mRNA levels and improved nitrification efficiency. Partial degradation of SMX by heterotrophic bacteria was also observed. PMID:27235775

  14. Isolation and identification of histone H3 protein enriched in microvesicles secreted from cultured sebocytes.

    Science.gov (United States)

    Nagai, Ayako; Sato, Takashi; Akimoto, Noriko; Ito, Akira; Sumida, Michihiro

    2005-06-01

    Secretion of microvesicles, defined as sebosomes, containing lipid particles were discovered for the first time in cultured sebocytes. After reaching confluency, hamster-cloned sebocytes released bubble-like microvesicles with a diameter range of 0.5-5.0 microm. They had a complex structure containing multiple Oil Red O-stainable particles. The lipid components of the microvesicles were large amounts of squalene both of hamster-cloned and rat primary cultured sebocytes. The microvesicles contained a concentrated 17-kDa cationic protein, which was soluble in sulfate buffer including Nonidet P-40 at pH 1.5. As the protein bound tightly to heparin-Sepharose and eluted with 1.5 M NaCl, it was further purified from a SDS-PAGE gel. Peptide sequencing identified the protein to be histone H3. Polyclonal antibodies against the purified protein detected the antigen in the microvesicles both in the hamster-cloned and rat primary cultured sebocytes. The antibodies demonstrated a distribution of the protein within the nucleus, cytoplasm, and precursor microvesicles. When a gene construct encoding histone H3-enhanced green fluorescent protein was transfected to the sebocytes, fluorescence of the fusion proteins was detected within both the nucleus and the precursor microvesicles of the cytoplasm. The distribution of heparan sulfate was evident in the microvesicles, and it suggested the possibility that the histone H3 protein was recruited and then condensed to the secreted microvesicles by the molecules. In addition, the 14-3-3 protein, which was detected in the microvesicles, also may help incorporate the histone H3 protein in the microvesicles because it can bind to both histone and lipid particles. PMID:15746254

  15. A discourse on creating and rendering educational and cultural enrichment services to rural migrant workers by public libraries

    Institute of Scientific and Technical Information of China (English)

    WANG; Zizhou; Charles; C.Yan

    2009-01-01

    As far as China’s enormous success in her economic reforms and development is concerned,Chinese rural migrant workers indeed have had their biggest share of contributions.Yet ironically in return,they have only received a disproportionate meager share of benefit rewards.These people represent a huge economically deprived group at the bottom of the social totem pole in China’s metropolises.On the whole as a social group,their educational attainment is relatively low as compared to their average urban coworkers.As such being the case,their rights to access some of the cost-free cultural and educational enrichment programs in the society are limited and not always assured.Nevertheless and in general speaking,they manifest a strong and consistent desire to acquire all sorts of new and practical knowledge by means of accessing the resources and facilities of their local public libraries.It is suggested in this paper that public libraries are in a good position to give strong support to the central government’s strategic planning for the development of a public culture service systema).In implementing such a government initiative with an unswerving purpose of advancing social justice and equality,public libraries should strife to provide as many as possible their library services at no cost to the public,especially to those socially deprived rural migrant workers.

  16. Enhancement of phenolics, resveratrol and antioxidant activity by nitrogen enrichment in cell suspension culture of Vitis vinifera.

    Science.gov (United States)

    Sae-Lee, Napaporn; Kerdchoechuen, Orapin; Laohakunjit, Natta

    2014-01-01

    Ammonium nitrate (NH4NO3), an important nitrogen source (34% N), has been used as an elicitor to stimulate plant growth and development as well as induce secondary metabolites under controlled conditions. In the present paper, we investigated the enhancement of cell biomass, total phenolics, resveratrol levels, and antioxidant activity of Vitis vinifera cv. Pok Dum by nitrogen enrichment (MS medium supplemented with NH4NO3 at 0, 500, 1,000, 5,000 and 10,000 mg/L). The highest accumulations of biomass, phenolics and resveratrol contents were observed at 8.8-fold (86.6 g DW/L), 15.9-fold (71.91 mg GAE/g DW) and 5.6-fold (277.89 µg/g DW) by the 14th day, in the medium supplemented with 500 mg/L NH4NO3. Moreover, the antioxidant activities of cultured grape cells estimated by the DPPH· and ABTS·+ assay were positively correlated with phenolics and resveratrol, and the maximum activity was also observed in cultured cells with 500 mg/L NH4NO3 at 176.11 and 267.79 mmol TE/100 g DW, respectively. PMID:24962393

  17. Enhancement of Phenolics, Resveratrol and Antioxidant Activity by Nitrogen Enrichment in Cell Suspension Culture of Vitis vinifera

    Directory of Open Access Journals (Sweden)

    Napaporn Sae-Lee

    2014-06-01

    Full Text Available Ammonium nitrate (NH4NO3, an important nitrogen source (34% N, has been used as an elicitor to stimulate plant growth and development as well as induce secondary metabolites under controlled conditions. In the present paper, we investigated the enhancement of cell biomass, total phenolics, resveratrol levels, and antioxidant activity of Vitis vinifera cv. Pok Dum by nitrogen enrichment (MS medium supplemented with NH4NO3 at 0, 500, 1,000, 5,000 and 10,000 mg/L. The highest accumulations of biomass, phenolics and resveratrol contents were observed at 8.8-fold (86.6 g DW/L, 15.9-fold (71.91 mg GAE/g DW and 5.6-fold (277.89 µg/g DW by the 14th day, in the medium supplemented with 500 mg/L NH4NO3. Moreover, the antioxidant activities of cultured grape cells estimated by the DPPH· and ABTS·+ assay were positively correlated with phenolics and resveratrol, and the maximum activity was also observed in cultured cells with 500 mg/L NH4NO3 at 176.11 and 267.79 mmol TE/100 g DW, respectively.

  18. More Than "Getting Us Through:" A Case Study in Cultural Capital Enrichment of Underrepresented Minority Undergraduates.

    Science.gov (United States)

    Ovink, Sarah M; Veazey, Brian D

    2011-01-01

    Minority students continue to be underrepresented among those who seek graduate and professional degrees in the sciences. Much previous research has focused on academic preparation. Equally important, however, are the psychological-social barriers and lack of institutional support encountered by many minority students. We present a case study of a university-sponsored intervention program for minority science majors that addresses not only academics, but also socialization into the academic community, networking, and the ability to practice newfound skills and dispositions through undergraduate research. In examining this case, we suggest that concerted, formal efforts toward expanding habitus and thereby augmenting cultural and social capital may have positive effects for underrepresented minority (URM) college students' academic and career prospects. Moreover, we argue that these differences complement the gains program participants make in academic preparedness, showing that attention to academics alone may be insufficient for addressing longstanding inequities in science career attainment among URM students. PMID:24954971

  19. Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine, cyanuric acid and biuret in industrial wastewater.

    Science.gov (United States)

    Dutta, Anirban; Vasudevan, Venugopal; Nain, Lata; Singh, Neera

    2016-01-01

    An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL(-1), 265.6 and 1805.2 µg mL(-1) and 1.85 and 16.12 µg mL(-1), respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples

  20. Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine, cyanuric acid and biuret in industrial wastewater.

    Science.gov (United States)

    Dutta, Anirban; Vasudevan, Venugopal; Nain, Lata; Singh, Neera

    2016-01-01

    An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL(-1), 265.6 and 1805.2 µg mL(-1) and 1.85 and 16.12 µg mL(-1), respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples

  1. Geochemical diversity in S processes mediated by culture-adapted and environmental-enrichments of Acidithiobacillus spp.

    Science.gov (United States)

    Bernier, Luc; Warren, Lesley A.

    2007-12-01

    Coupled S speciation and acid generation resulting from S processing associated with five different microbial treatments, all primarily Acidithiobacillus spp. (i.e. autotrophic S-oxidizers) were evaluated in batch laboratory experiments. Microbial treatments included two culture-adapted strains, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, their consortia and two environmental enrichments from a mine tailings lake that were determined to be >95% Acidithiobacillus spp., by whole-cell fluorescent hybridization. Using batch experiments simulating acidic mine waters with no carbon amendments, acid generation, and S speciation associated with the oxidation of three S substrates (thiosulfate, tetrathionate, and elemental S) were evaluated. Aseptic controls showed no observable pH decrease over the experimental time course (1 month) for all three S compounds examined. In contrast, pH decreased in all microbial treatments from starting pH values of 4 to 2 or less for all three S substrates. Results show a non-linear relationship between the pH dynamics of the batch cultures and their corresponding sulfate concentrations, and indicate how known microbial S processing pathways have opposite impacts, ultimately on pH dynamics. Associated geochemical modeling indicated negligible abiogenic processes contributing to the observed results, indicating strong microbial control of acid generation extending over pH ranges from 4 to less than 2. However, the observed acid generation rates and associated S speciation were both microbial treatment and substrate-specific. Results reveal a number of novel insights regarding microbial catalysis of S oxidation: (1) metabolic diversity in S processing, as evidenced by the observed geochemical signatures in S chemical speciation and rates of acid generation amongst phylogenetically similar organisms (to the genus level); (2) consortial impacts differ from those of individual strain members; (3) environmental enrichments

  2. Nitrifying and denitrifying bacteria in aerobic granules formed in sequencing batch airlift reactors

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; YANG Fenglin; QI Aijiu

    2007-01-01

    The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH3 -N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.

  3. Selective pressure of temperature on competition and cross-feeding within denitrifying and fermentative microbial communities

    Directory of Open Access Journals (Sweden)

    Anna eHanke

    2016-01-01

    Full Text Available In coastal marine sediments, denitrification and fermentation are important processes in the anaerobic decomposition of organic matter. Microbial communities performing these two processes were enriched from tidal marine sediments in replicated, long term chemostat incubations at 10ºC and 25ºC. Whereas denitrification rates at 25ºC were more or less stable over time, at 10ºC denitrification activity was unstable and could only be sustained either by repeatedly increasing the amount of carbon substrates provided or by repeatedly decreasing the dilution rate. Metagenomic and transcriptomic sequencing was performed at different time points and provisional whole genome sequences and gene activities of abundant populations were compared across incubations. These analyses suggested that a temperature of 10ºC selected for populations related to Vibrionales/Photobacterium that contributed to both fermentation (via pyruvate/formate lyase and nitrous oxide reduction. At 25ºC, denitrifying populations affiliated with Rhodobacteracaea were more abundant. The latter performed complete denitrification, and may have used carbon substrates produced by fermentative populations (cross-feeding. Overall, our results suggest that a mixture of competition – for substrates between fermentative and denitrifying populations, and for electrons between both pathways active within a single population –, and cross feeding – between fermentative and denitrifying populations – controlled the overall rate of denitrification. Temperature was shown to have a strong selective effect, not only on the populations performing either process, but also on the nature of their ecological interactions. Future research will show whether these results can be extrapolated to the natural environment.

  4. Drinking Water Denitrification using Autotrophic Denitrifying Bacteria in a Fluidized Bed Bioreactor 

    Directory of Open Access Journals (Sweden)

    Abdolmotaleb Seid-mohammadi

    2013-02-01

    Full Text Available Background and Objectives: Contamination of drinking water sources with nitrate may cause adverse effects on human health. Due to operational and maintenance problems of physicochemical nitrate removal processes, using biological denitrification processes have been performed. The aim of this study is to evaluate nitrate removal efficiency from drinking water using autotrophic denitrifying bacteria immobilized on sulfur impregnated activated carbon in a fluidized bed bioreactor. Materials and Methods: After impregnating activated carbon by sulfur as a microorganism carriers and enrichment and inoculation of denitrifying bacteria, a laboratory-scale fluidized bed bioreactor was operated. Nitrate removal efficiency, nitrite, turbidity, hardness and TOC in the effluent were examined during the whole experiment under various conditions including constant influent nitrate concentration as 90 mg NO3--N/l corresponding to different HRT ranging from 5.53 to 1.5 hr. Results: We found that  the denitrification rates was depended on the hydraulic retention time and the nitrate removal efficiency was up to 98%  and nitrite concentration was lower than 1mg/l at optimum HRT=2.4 hr respectively. Moreover, there was no difference in hardness between influent and effluent due to supplying sodium bicarbonate as carbon source for denitrifying bacteria.  However pH, TOC, hardness, and turbidity of the effluent met the W.H.O guidelines for drinking water.  Conclusion: This study demonstrated that an innovative carrier as sulfur impregnated activated carbon could be used as both the biofilm carrier and energy source for treating nitrate contaminated drinking water in the lab-scale fluidized bed bioreactor.

  5. Identification and Metabolic Mechanism of Non-fermentative Short-cut Denitrifying Phosphorus-removing Bacteria

    Institute of Scientific and Technical Information of China (English)

    LIU Hui; SUN Yanfu; JIA Xiaoshan; LI Jun; ZHOU Kangqun; QU Xiangdong; TAO Xueqin

    2013-01-01

    To investigate the characteristics and metabolic mechanism of short-cut denitrifying phosphorus-removing bacteria (SDPB) that are capable of enhanced biological phosphorus removal (EBPR) using nitrite as an electron acceptor,an aerobic/anoxic sequencing batch reactor was operated under three phases.An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological,physiological,biochemical properties and 16S rDNA gene sequence analysis.Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand (COD),phosphate,nitrite,poly-fβ-hydroxybutyrate (PHB),and glycogen.The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans.As a kind of non-fermentative bacteria,the energy of strain YC was mainly generated from phosphorus release (96.2%) under anaerobic conditions with 0.32 mg P per mg synthesized PHB.Under anoxic conditions,strain YC accumulated 0.45 mg P per mg degraded PHB,which produced most of energy for phosphate accumulation (91.3%) and a little for glycogen synthesis (8.7%).This metabolic mechanism of strain YC is different from that of traditional phosphorus-accumulating organisms (PAOs).It is also found that PHB,a kind of intracellular polymer,plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification.Therefore,monitoring △P/△PHB and △NO2--N/△PHB is more necessary than monitoring △P/△COD,△NO2--N/△COD,or △P/△NO2--N.

  6. Cultivation and irradiation of human fibroblasts in a medium enriched with platelet lysate for obtaining feeder layer in epidermal cell culture

    International Nuclear Information System (INIS)

    For over 30 years, the use of culture medium, enriched with bovine serum, and murines fibroblasts, with the rate of proliferation controlled by irradiation or by share anticarcinogenic drugs, has been playing successfully its role in assisting in the development of keratinocytes in culture, for clinical purposes. However, currently there is a growing concern about the possibility of transmitting prions and animals viruses to transplanted patients. Taking into account this concern, the present work aims to cultivate human fibroblasts in a medium enriched with human platelets lysate and determine the irradiation dose of these cells, for obtaining feeder layer in epidermal cell culture. For carrying out the proposed objective, platelets lysis has standardized, this lysate was used for human fibroblasts cultivation and the irradiation dose enough to inhibit its duplication was evaluated. Human keratinocytes were cultivated in these feeder layers, in culture medium enriched with the lysate. With these results we conclude that the 10% platelets lysate promoted a better adhesion and proliferation of human fibroblasts and in all dose levels tested (60 to 300 Gy), these had their mitotic activity inactivated by ionizing irradiation, being that the feeder layers obtained with doses from 70 to 150 Gy were those that provided the best development of keratinocytes in medium containing 2.5% of human platelet lysate. Therefore, it was possible to standardize both the cultivation of human fibroblasts as its inactivation for use as feeder layer in culture of keratinocytes, so as to eliminate xenobiotics components. (author)

  7. Rapid and Specific Enrichment of Culturable Gram Negative Bacteria Using Non-Lethal Copper-Free Click Chemistry Coupled with Magnetic Beads Separation.

    Science.gov (United States)

    Fugier, Emilie; Dumont, Audrey; Malleron, Annie; Poquet, Enora; Mas Pons, Jordi; Baron, Aurélie; Vauzeilles, Boris; Dukan, Sam

    2015-01-01

    Currently, identification of pathogenic bacteria present at very low concentration requires a preliminary culture-based enrichment step. Many research efforts focus on the possibility to shorten this pre-enrichment step which is needed to reach the minimal number of cells that allows efficient identification. Rapid microbiological controls are a real public health issue and are required in food processing, water quality assessment or clinical pathology. Thus, the development of new methods for faster detection and isolation of pathogenic culturable bacteria is necessary. Here we describe a specific enrichment technique for culturable Gram negative bacteria, based on non-lethal click chemistry and the use of magnetic beads that allows fast detection and isolation. The assimilation and incorporation of an analog of Kdo, an essential component of lipopolysaccharides, possessing a bio-orthogonal azido function (Kdo-N3), allow functionalization of almost all Gram negative bacteria at the membrane level. Detection can be realized through strain-promoted azide-cyclooctyne cycloaddition, an example of click chemistry, which interestingly does not affect bacterial growth. Using E. coli as an example of Gram negative bacterium, we demonstrate the excellent specificity of the technique to detect culturable E. coli among bacterial mixtures also containing either dead E. coli, or live B. subtilis (as a model of microorganism not containing Kdo). Finally, in order to specifically isolate and concentrate culturable E. coli cells, we performed separation using magnetic beads in combination with click chemistry. This work highlights the efficiency of our technique to rapidly enrich and concentrate culturable Gram negative bacteria among other microorganisms that do not possess Kdo within their cell envelope.

  8. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part B--Nitrogen-, Sulfur-, and Oxygen-Containing Heterocyclic Aromatic Compounds.

    Science.gov (United States)

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-07-01

    Present study focused on the biodegradation of various heterocyclic nitrogen, sulfur, and oxygen (NSO) compounds using naphthalene-enriched culture. Target compounds in the study were pyridine, quinoline, benzothiophene, and benzofuran. Screening studies were carried out using different microbial consortia enriched with specific polycyclic aromatic hydrocarbon (PAH) and NSO compounds. Among different microbial consortia, naphthalene-enriched culture was the most efficient consortium based on high substrate degradation rate. Substrate degradation rate with naphthalene-enriched culture followed the order pyridine > quinoline > benzofuran > benzothiophene. Benzothiophene and benzofuran were found to be highly recalcitrant pollutants. Benzothiophene could not be biodegraded when concentration was above 50 mg/l. It was observed that 2-(1H)-quinolinone, benzothiophene-2-one, and benzofuran-2,3-dione were formed as metabolic intermediates during biodegradation of quinoline, benzothiophene, and benzofuran, respectively. Quinoline-N and pyridine-N were transformed into free ammonium ions during the biodegradation process. Biodegradation pathways for various NSO compounds are proposed. Monod inhibition model was able to simulate single substrate biodegradation kinetics satisfactorily. Benzothiophene and benzofuran biodegradation kinetics, in presence of acetone, was simulated using a generalized multi-substrate model.

  9. Molecular analysis of enrichment cultures of ammonia oxidizers from the Salar de Huasco, a high altitude saline wetland in northern Chile.

    Science.gov (United States)

    Dorador, Cristina; Busekow, Annika; Vila, Irma; Imhoff, Johannes F; Witzel, Karl-Paul

    2008-05-01

    We analyzed enrichment cultures of ammonia-oxidizing bacteria (AOB) collected from different areas of Salar de Huasco, a high altitude, saline, pH-neutral water body in the Chilean Altiplano. Samples were inoculated into mineral media with 10 mM NH4+ at five different salt concentrations (10, 200, 400, 800 and 1,400 mM NaCl). Low diversity (up to three phylotypes per enrichment) of beta-AOB was detected using 16S rDNA and amoA clone libraries. Growth of beta-AOB was only recorded in a few enrichment cultures and varied according to site or media salinity. In total, five 16S rDNA and amoA phylotypes were found which were related to Nitrosomonas europaea/Nitrosococcus mobilis, N. marina and N. communis clusters. Phylotype 1-16S was 97% similar with N. halophila, previously isolated from Mongolian soda lakes, and phylotypes from amoA sequences were similar with yet uncultured beta-AOB from different biofilms. Sequences related to N. halophila were frequently found at all salinities. Neither gamma-AOB nor ammonia-oxidizing Archaea were recorded in these enrichment cultures. PMID:18305895

  10. INDISIM-Paracoccus, an individual-based and thermodynamic model for a denitrifying bacterium.

    Science.gov (United States)

    Araujo Granda, Pablo; Gras, Anna; Ginovart, Marta; Moulton, Vincent

    2016-08-21

    We have developed an individual-based model for denitrifying bacteria. The model, called INDISIM-Paracoccus, embeds a thermodynamic model for bacterial yield prediction inside the individual-based model INDISIM, and is designed to simulate the bacterial cell population behavior and the product dynamics within the culture. The INDISIM-Paracoccus model assumes a culture medium containing succinate as a carbon source, ammonium as a nitrogen source and various electron acceptors such as oxygen, nitrate, nitrite, nitric oxide and nitrous oxide to simulate in continuous or batch culture the different nutrient-dependent cell growth kinetics of the bacterium Paracoccus denitrificans. The individuals in the model represent microbes and the individual-based model INDISIM gives the behavior-rules that they use for their nutrient uptake and reproduction cycle. Three previously described metabolic pathways for P. denitrificans were selected and translated into balanced chemical equations using a thermodynamic model. These stoichiometric reactions are an intracellular model for the individual behavior-rules for metabolic maintenance and biomass synthesis and result in the release of different nitrogen oxides to the medium. The model was implemented using the NetLogo platform and it provides an interactive tool to investigate the different steps of denitrification carried out by a denitrifying bacterium. The simulator can be obtained from the authors on request. PMID:27179457

  11. Detection of Mycoplasma ovipneumoniae and M. arginini in bighorn sheep using enrichment culture coupled with genus- and species-specific polymerase chain reaction.

    Science.gov (United States)

    Weiser, Glen C; Drew, Mark L; Cassirer, E Frances; Ward, Alton C S

    2012-04-01

    Mycoplasma species are of interest as possible primary pathogens in the pneumonia complex of bighorn sheep (Ovis canadensis). Previous investigations have not commonly detected low frequencies of Mycoplasma spp. from free-ranging bighorn sheep, possibly due to the fastidious and slow growth of these organisms. We developed a culture protocol that employed an average initial 3-day enrichment culture in liquid Hayflick broth in a CO(2)-enhanced atmosphere. The broth was plated to solid Hayflick medium and the cultures observed for growth for up to 30 days. Polymerase chain reaction (PCR) was performed on DNA isolated from the enrichment broth and on isolates obtained from culture using Mycoplasma genus-specific PCR assays and species-specific PCR assays for M. arginini and M. ovipneumoniae. Some cultures that grew on Hayflick plates were picked as single colonies but were mixed because two organisms may grow together and appear as a single colony. Culture and PCR tests produced similar results for M. arginini, but for M. ovipneumoniae, culture alone was less accurate than PCR. Use of genus-specific primers also may allow detection of other species in samples negative for M. arginini and M. ovipneumoniae. Two methods of transport from field to laboratory (Port-a-Cul™ tubes, cryoprotectant in liquid N(2) and Fisher Transport System) gave similar results under our study conditions.

  12. Characterization of Denitrifying Phosphorus Removal Microorganisms in a Novel Two-Sludge Process by Combining Chemical with Microbial Analysis

    Directory of Open Access Journals (Sweden)

    Haiming Zou

    2014-01-01

    Full Text Available The present work focuses on the investigation of denitrifying phosphorus removal organisms (DPB in a novel two-sludge denitrifying phosphorus removal process by combining chemical with microbial analysis. When the two-sludge process operated stably over one year, good phosphorus (P release and P uptake performance of activated sludge samples collected from this process were present in anaerobic and anoxic conditions, respectively, via batch test, showing that the ratio of P release specific rate to P uptake specific rate was 1.31. The analysis of energy dispersive spectrometry (EDS showed that P content of activated sludge samples collected at the end of anoxic phase was 12.3% of dry weight, further demonstrating the existence of microorganisms responsible for phosphorus removal in this two-sludge process. From polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE analysis, the presence of microorganisms mostly belonging to the phyla Firmicutes and Proteobacteria was observed, previously evidenced in the phosphorus removal wastewater treatment process. Fluorescence in situ hybridization (FISH quantitative analysis showed that Accumulibacter responsible for phosphorus removal was dominant in this two-sludge process, accounting for 69.7% of all bacteria in activated sludge. These results obtained from chemical and microbial analysis in this study suggested that denitrifying phosphorus removal microorganisms were completely enriched in the two-sludge process proposed here.

  13. Denitrifying capability and community dynamics of glycogen accumulating organisms during sludge granulation in an anaerobic-aerobic sequencing batch reactor

    Science.gov (United States)

    Bin, Zhang; Bin, Xue; Zhigang, Qiu; Zhiqiang, Chen; Junwen, Li; Taishi, Gong; Wenci, Zou; Jingfeng, Wang

    2015-08-01

    Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3--N could be removed or reduced, some amount of NO2--N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy.

  14. Legal Thinking on the Construction of Culture -Enriched Beijing%"人文北京"建设的法制思考

    Institute of Scientific and Technical Information of China (English)

    杨积堂

    2012-01-01

    The core of Culture - enriched Beijing construction lies in humanity and culture. From the perspec- tive of humanity, Culture - enriched Beijing construction aims to build up a more prosperous, civilized, harmoni- ous, livable and healthy socialist society. From the perspective of culture, Culture -enriched Beijing construction aims to build up the socialism with Chinese characteristics with the most humanistic concern, civilized and cultural charm capital. Legal construction is the significant aim and content requirement. For one thing, rule of law is one of content requirements to realize the real Culture - enriched Beijing. For another, perfecting the legal system is the fundamental guarantee in Culture -enriched Beijing construction. The perfect culture legal system, harmonious and efficient enforcement of cultural mechanism, uncorrupted judicial operation mechanism as well as convenient law intermediary service mechanism are the requirements of cultural legal construction. As for the legal system construc- tion, laying down the legal construction strategy, perfecting the local cultural code system and creating good legal atmosphere for Culture -enriched Beijing construction are proposed.%“人文北京”建设的核心是“人”和“文”,以人为本,以文化人,从“人”的角度,“人文北京”就是要建设更加繁荣、文明、和谐、宜居、健康的社会主义和谐社会“首善之区”。从“文”的角度.“人文北京”就是要建成最具人文关怀、最显文明风采、最有文化魅力的中国特色社会主义先进文化之都。“法治”建设,是人文北京建设的重要目标和内涵要求。一方面,法治是实现真正的“人文北京”的内涵之一;另一方面,健全法制又是“人文北京”建设的根本保障。完善的文化法律法规体系、协调高效的文化执法机制、廉洁公正的司法运行机制、便捷的法律中介服务机制是文化法制

  15. Comparative metagenomics of three Dehalococcoides-containing enrichment cultures: the role of the non-dechlorinating community

    Directory of Open Access Journals (Sweden)

    Hug Laura A

    2012-07-01

    Full Text Available Abstract Background The Dehalococcoides are strictly anaerobic bacteria that gain metabolic energy via the oxidation of H2 coupled to the reduction of halogenated organic compounds. Dehalococcoides spp. grow best in mixed microbial consortia, relying on non-dechlorinating members to provide essential nutrients and maintain anaerobic conditions. A metagenome sequence was generated for the dechlorinating mixed microbial consortium KB-1. A comparative metagenomic study utilizing two additional metagenome sequences for Dehalococcoides-containing dechlorinating microbial consortia was undertaken to identify common features that are provided by the non-dechlorinating community and are potentially essential to Dehalococcoides growth. Results The KB-1 metagenome contained eighteen novel homologs to reductive dehalogenase genes. The metagenomes obtained from the three consortia were automatically annotated using the MG-RAST server, from which statistically significant differences in community composition and metabolic profiles were determined. Examination of specific metabolic pathways, including corrinoid synthesis, methionine synthesis, oxygen scavenging, and electron-donor metabolism identified the Firmicutes, methanogenic Archaea, and the ∂-Proteobacteria as key organisms encoding these pathways, and thus potentially producing metabolites required for Dehalococcoides growth. Conclusions Comparative metagenomics of the three Dehalococcoides-containing consortia identified that similarities across the three consortia are more apparent at the functional level than at the taxonomic level, indicating the non-dechlorinating organisms’ identities can vary provided they fill the same niche within a consortium. Functional redundancy was identified in each metabolic pathway of interest, with key processes encoded by multiple taxonomic groups. This redundancy likely contributes to the robust growth and dechlorination rates in dechlorinating enrichment

  16. Inhibitory Effect of Gamma-Irradiated Chitosan on the Growth of Denitrifiers

    Directory of Open Access Journals (Sweden)

    Javier Vilcáez

    2009-01-01

    Full Text Available In order to find an environmentally benign substitute to hazardous inhibitory agents, the inhibitory effect of -irradiated chitosans against a mixed culture of denitrifying bacteria was experimentally evaluated. Unlike other studies using pure aerobic cultures, the observed effect was not a complete inhibition but a transient inhibition reflected by prolonged lag phases and reduced growth rates. Raw chitosan under acid conditions (pH 6.3 exerted the strongest inhibition followed by the 100 kGy and 500 kGy irradiated chitosans, respectively. Therefore, because the molecular weight of chitosan decreases with the degree of -irradiation, the inhibitory properties of chitosan due to its high molecular weight were more relevant than the inhibitory properties gained due to the modification of the surface charge and/or chemical structure by -irradiation. High dosage of -irradiated appeared to increase the growth of mixed denitrifying bacteria in acid pH media. However, in neutral pH media, high dosage of -irradiation appeared to enhance the inhibitory effect of chitosan.

  17. Role of the denitrifying Haloarchaea in the treatment of nitrite-brines.

    Science.gov (United States)

    Nájera-Fernández, Cindy; Zafrilla, Basilio; Bonete, María José; Martínez-Espinosa, Rosa María

    2012-09-01

    Haloferax mediterranei is a denitrifying halophilic archaeon able to reduce nitrate and nitrite under oxic and anoxic conditions. In the presence of oxygen, nitrate and nitrite are used as nitrogen sources for growth. Under oxygen scarcity, this haloarchaeon uses both ions as electron acceptors via a denitrification pathway. In the present work, the maximal nitrite concentration tolerated by this organism was determined by studying the growth of H. mediterranei in minimal medium containing 30, 40 and 50 mM nitrite as sole nitrogen source and under initial oxic conditions at 42 degrees C. The results showed the ability of H. mediterranei to withstand nitrite concentrations up to 50 mM. At the beginning of the incubation, nitrate was detected in the medium, probably due to the spontaneous oxidation of nitrite under the initial oxic conditions. The complete removal of nitrite and nitrate was accomplished in most of the tested conditions, except in culture medium containing 50 mM nitrite, suggesting that this concentration compromised the denitrification capacity of the cells. Nitrite and nitrate reductases activities were analyzed at different growth stages of H. mediterranei. In all cases, the activities of the respiratory enzymes were higher than their assimilative counterparts; this was especially the case for NirK. The denitrifying and possibly detoxifying role of this enzyme might explain the high nitrite tolerance of H. mediterranei. This archaeon was also able to remove 60% of the nitrate and 75% of the nitrite initially present in brine samples collected from a wastewater treatment facility. These results suggest that H. mediterranei, and probably other halophilic denitrifying Archaea, are suitable candidates for the bioremediation of brines with high nitrite and nitrate concentrations. PMID:23847815

  18. Landfill Leachate as Enrichment Culture for Ammonia-Oxidizing Bacteria%利用垃圾渗滤液富集培养氨氧化菌

    Institute of Scientific and Technical Information of China (English)

    崔荣; 李金玲; 李凤德; 韩京龙

    2011-01-01

    Maintaining a certain amount of active ammonia-oxidizing bacteria (AOB) in activated sludge is essential for the biological nitrogen removal process. The addition of enriched AOB into activated sludge is an effective option to increase AOB population. To economically get enriched AOB and effectively treat landfill leachate, the feasibility of using landfill leachate as a culture for enriching AOB was examined. Leachate from the Yantai municipal landfill site was used as the culture, and returned sludge from the Xin' an River municipal sewage treatment plant A2/O process was used as seed sludge. The AOB were enriched by fed batch cultivation. The results showed that after four cultivation cycles, the population of cells in the enriched AOB was 5. 6 times higher than the original activated sludge. By adding 14.5% of enriched AOB after four cultivation cycles into the activated sludge, the ammonia oxidation rate increased by 65.4%, which confirmed that landfill leachate could be used as a culture for enriching AOB.%确保活性污泥中适当的氨氧化菌(AOB)的数量及活性对污水生物除氮过程至关重要,投加富集AOB是增加活性污泥中AOB浓度的方法之一.为了经济有效地获取富集的AOB并有效处理难降解的垃圾渗滤液,对利用垃圾渗滤液富集培养AOB的可行性进行了研究.采用烟台市生活垃圾填埋场的垃圾渗滤液作为培养基,利用辛安河污水处理厂A2/O工艺二沉池的回流污泥进行接种,通过更代方式富集培养AOB.结果显示:更代4次后,菌液中AOB的浓度增至原来的5.6倍;向活性污泥中投加14.5%的经过4次更代富集培养的AOB,氨氧化速率提高了65.4%,从而验证了利用垃圾渗滤液富集AOB是可行的.

  19. Effect on the Growth of Denitrifying Bacteria from Different Carbon Sources%不同碳源对反硝化细菌生长的影响

    Institute of Scientific and Technical Information of China (English)

    李建; 潘康成

    2012-01-01

    The growth of bacteria was relative to carbon sources intimately. The experiment was designed to find the best carbon source in enlarging denitrifying bacteria by research into effect on the growth of denitrifying bacteria from different carbon sources. The 5 carbon sources including glucose, potassium sodium tartrate, cane sugar, acetic acid and ethanol were used as the only carbon source respectively taking denitrifying bacteria into liquid culture media in the contrast test. Live bacteria number was used to denitrifying bacteria from different carbon sources. The results made it clear that of denitrifying bacteria more remarkably than the others. The results indicated others in enlarging denitrifying bacteria. estimate effect on the growth of glucose could promote the growth that glucose was better than the%细菌的生长速度和碳源有非常密切的关系,研究不同碳源对反硝化细菌生长的影响,以找到适合用于扩大培养菌种的最佳碳源。分别采用葡萄糖、酒石酸钾钠、蔗糖、乙酸和乙醇5种碳源作为唯一碳源,接种反硝化细菌进行对比实验,采用活菌数来反映不同碳源对反硝化细菌生长的影响。结果显示,葡萄糖促进反硝化细菌生长的作用明显优于其余4种碳源。对反硝化细菌进行扩大培养,葡萄糖的效果是比较好的。

  20. Are Isotopologue Signatures of N2O from Bacterial Denitrifiers Indicative of NOR Type?

    Science.gov (United States)

    Well, R.; Braker, G.; Giesemann, A.; Flessa, H.

    2010-12-01

    NOR and qCuANOR. Pure cultures where incubated at 25°C under denitrifying conditions (anaerobic in the presence of 5 mM NO3-) in their preferred media for 2 weeks. Acetylene (10%) was added to the headspace to inhibit reduction of N2O. Gas samples where collected from incubation vessels and analysed for δ18O, δ15Nbulk and SP using isotope ratio mass spectrometry. ɛSP of the qNOR-type ranged between -9.7 and -18 ‰ and of the cNOR-type between -1.7 to -10.8 ‰. Our results suggest that SP of N2O produced by soil bacteria may be more negative than previously estimated since the ɛSP range of the tested cNOR-type was larger compared to earlier studies and the qNOR type tended to be even more negative. This needs to be taken into account when using isotopologue signatures of N2O to estimate other processes such as fungal denitrification, nitrification and N2O reduction by denitrifiers. References Schmidt, H.-L. et al. 2004, Rapid Comm. Mass Spectrom. 18, 2036-2040. Sutka, R.L et al. 2006, Appl. Environ. Microbiol. 72, 638-644. Sutka, R. L et al. 2008, Rapid Commun. Mass Spectrom. 22, 3989-3996. Toyoda, S. et al. 2005, Soil Biol. Biochem. 37, 1535-1545.

  1. Identification and Characteristics Analysis of Simultaneous Nitrifying-Denitrifying Bacteria and Nitrogen Removing%同步硝化反硝化细菌的鉴定与脱氮特性研究

    Institute of Scientific and Technical Information of China (English)

    张巍

    2012-01-01

    依据同步硝化反硝化脱氮原理,以生活污水处理厂污泥为种泥,利用15℃低温摇床富集并分离出同步硝化反硝化细菌(SNDB-5),采用传统与现代分子生物学相结合的手段对其鉴定,以确定其分类地位;利用水浴摇床研究SNDB-5对硝化细菌液体培养基NO2-N的去除效果.结果表明:SNDB-5与Pseudomonas mendocina同源性达99.0%,形态特征、革兰氏染色及生理生化与Pseudomonas mendocina最相似,属假单胞菌属;摇床培养反应条件显示,当NO2-N浓度加大到150 mg/L时,菌株SNDB-5的活性受到了抑制.%Based on the principle of simultaneously nitrifying-denitrifying nitrogen removing, sewage treatment plant wastewater sludge was used as inoculum, and the continuous low temperature shaker was used to enrich the simultaneously nitrifying-denitrifying nitrogen removing bacteria (SNDB-5) at 15℃. Traditional and modern molecular biology methods were adopted to determine the taxonomic status of the isolated bacteria which was named SNDB-5. Water bath shaker was used to analyze the NO2- -N removal in the nitrifying bacteria culture medium. The results show that SNDB-5 has 99. 0 % homology with Pseudomonas mendocina. Morphological, gram staining and biochemical characteristics are also similar to Pseudomonas mendocina. Incubating reaction conditions in shaker shows that SNDB-5 activity is inhibited when the concentration of NO2- - N increases to 150 mg/L.

  2. Hydraulic flow characteristics of agricultural residues for denitrifying bioreactor media

    Science.gov (United States)

    Denitrifying bioreactors are a promising technology to mitigate agricultural subsurface drainage nitrate-nitrogen losses, a critical water quality goal for the Upper Mississippi River Basin. This study was conducted to evaluate the hydraulic properties of agricultural residues that are potential bio...

  3. Denitrifying bioreactors for nitrate removal from tile drained cropland

    Science.gov (United States)

    Denitrification bioreactors are a promising technology for mitigation of nitrate-nitrogen (NO3-N) losses in subsurface drainage water. Bioreactors are constructed with carbon substrates, typically wood chips, to provide a substrate for denitrifying microorganisms. Researchers in Iowa found that for ...

  4. Denitrification and the denitrifier community in coastal microbial mats

    NARCIS (Netherlands)

    Fan, H.; Bolhuis, H.; Stal, L.J.

    2015-01-01

    Denitrification was measured in three structurally different coastal microbial mats by using the stable isotope technique. The composition of the denitrifying community was determined by analyzing the nitrite reductase (nirS and nirK) genes using clone libraries and the GeoChip. The highest potentia

  5. Treatment and electricity harvesting from sulfate/sulfide-containing wastewaters using microbial fuel cell with enriched sulfate-reducing mixed culture

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Duu-Jong, E-mail: cedean@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan (China); Lee, Chin-Yu [Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan (China); Chang, Jo-Shu [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan (China); Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer We started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture. Black-Right-Pointing-Pointer Sulfate-reducing bacteria and anode-respiring bacteria were enriched in anodic biofilms. Black-Right-Pointing-Pointer The MFC effectively remove sulfate to elementary sulfur in the presence of lactate. Black-Right-Pointing-Pointer The present device can treat sulfate laden wastewaters with electricity harvesting. - Abstract: Anaerobic treatment of sulfate-laden wastewaters can produce excess sulfide, which is corrosive to pipelines and is toxic to incorporated microorganisms. This work started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture as anodic biofilms and applied the so yielded MFC for treating sulfate or sulfide-laden wastewaters. The sulfate-reducing bacteria in anodic biofilm effectively reduced sulfate to sulfide, which was then used by neighboring anode respiring bacteria (ARB) as electron donor for electricity production. The presence of organic carbons enhanced MFC performance since the biofilm ARB were mixotrophs that need organic carbon to grow. The present device introduces a route for treating sulfate laden wastewaters with electricity harvesting.

  6. Analysis and Outlook of Denitrifying Phosphorus Removal Technology%反硝化除磷技术分析及展望

    Institute of Scientific and Technical Information of China (English)

    邴帅; 赵萌

    2011-01-01

    目前水体富营养化情况相当严重,其主要原因是磷含量的增加,因此废水的除磷技术十分重要.反硝化除磷技术利用厌氧、缺氧交替的环境,通过反硝化聚磷菌的作用,同时完成过量吸磷和反硝化过程,应用前景广阔.简述了反硝化除磷技术的机理,介绍了单污泥系统反硝化除磷工艺(BCFS工艺)及双污泥系统反硝化除磷工艺(A2N工艺、DEPHANOX工艺),探讨了反硝化除磷工艺的影响因素,将其与传统除磷技术进行了比较,并对其发展进行了展望.%The current eutrophication situation is quite serious?mainly due to the increase in phosphorus content, so phosphorus removal technology in wastewater is very important. Using the anaerobic and aerobic alternate environment, denitrifying phosphorus removal technology can finish at the same time excessive phosphorus uptake and denitrification process with the role of the denitrification phosphorus enrichment bacteria. Because of these characteristics,the application of denitrifying phosphorus removal technology becomes increasingly widespread. The denitrification and phospohous removal mechanism was stated in brief. The single sludge system denitrifying phosphorus removal technology such as BCFS technology*and the double sludge system denitrifying phosphorus removal technology such as A2N technology and DEPHANOX technology were introduced. And the influential factors to the removal technology were discussed. The denitrifying phosphorus removal technology was compared with traditional phosphopous removal technology and its development was prospected.

  7. Trace Gas Emission from in-Situ Denitrifying Bioreactors

    Science.gov (United States)

    Pluer, W.; Walter, M. T.; Geohring, L.

    2014-12-01

    Despite decades of concerted effort to mitigate nonpoint source nitrate (NO3-) pollution from agricultural lands, these efforts have not been sufficient to arrest eutrophication. A primary process for removing excess NO3- from water is denitrification, where denitrifying bacteria use NO3- for respiration in the absence of oxygen. Denitrification results in reduced forms of nitrogen, often dinitrogen gas (N2) but also nitrous oxide (N2O), an aggressive greenhouse gas. A promising solution to NO3- pollution is to intercept agricultural discharges with denitrifying bioreactors (DNBRs). DNBRs provide conditions ideal for denitrifiers: an anaerobic environment, sufficient organic matter, and excess NO3-. These conditions are also ideal for methanogens, which produce methane (CH4), another harmful trace gas. While initial results from bioreactor studies show that they can cost-effectively remove NO3-, trace gas emissions are an unintended consequence. This study's goal was to determine how bioreactor design promotes denitrification while limiting trace gas production. Reactor inflow and outflow water samples were tested for nutrients, including NO3-, and dissolved inflow and outflow gas samples were tested for N2O and CH4. NO3- reduction and trace gas production were evaluated at various residence times, pHs, and inflow NO3- concentrations in field and lab-scale reactors. Low NO3- reduction indicated conditions that stressed denitrifying bacteria while high reductions indicated designs that optimized pollutant treatment for water quality. Several factors influenced high N2O, suggesting non-ideal conditions for the final step of complete denitrification. High CH4 emissions pointed to reactor media choice for discouraging methanogens, which may remove competition with denitrifiers. It is critical to understand all of potential impacts that DNBRs may have, which means identifying processes and design specifications that may affect them.

  8. Addition of novobiocin in pre-enrichment step can improve Salmonella culture protocol of modified semisolid Rappaport-Vassiliadis

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Sørensen, Gitte; Baggesen, Dorte Lau;

    2003-01-01

    -enrichment of 32 presumably naturally contaminated swine fecal samples were assessed for BPW with and without addition of Novobiocin (22 mug/ml). In another experiment, a total of 400 swine fecal samples were screened for the presence of Salmonella spp., in order to compare the performance of the nonselective pre...... be caused by a reduction in the number of competitive microorganisms....

  9. INTERMITTENT OPPORTUNITIES, SOME OBSERVATIONS AND HYPOTHESES RELATING TO AN EDUCATIONAL ENRICHMENT SUMMER PROGRAM FOR SOME CULTURALLY DEPRIVED CHILDREN OF BOSTON.

    Science.gov (United States)

    HOZID, JOSEPH L.

    THIS RESEARCH INVESTIGATED WHY DISADVANTAGED STUDENTS CHOSE TO ATTEND OR NOT TO ATTEND A SUMMER ENRICHMENT PROGRAM. INTERVIEWS WERE CONDUCTED WITH A SAMPLE OF GIRLS AND THEIR MOTHERS TO DETERMINE THE INFLUENCE OF SCHOOL AND FAMILY ON THEIR CHOICE. SOME OF THE SPECIFIC FACTORS AFFECTING THEIR ATTENDING WERE CONSIDERED IN PLANNING THE PROGRAM FOR…

  10. Comparative Analysis of 16S rRNA and amoA Genes from Archaea Selected with Organic and Inorganic Amendments in Enrichment Culture

    OpenAIRE

    Xu, Mouzhong; Schnorr, Jon; Keibler, Brandon; Holly M Simon

    2012-01-01

    We took advantage of a plant-root enrichment culture system to characterize mesophilic soil archaea selected through the use of organic and inorganic amendments. Comparative analysis of 16S rRNA and amoA genes indicated that specific archaeal clades were selected under different conditions. Three amoA sequence clades were identified, while for a fourth group, identified by 16S rRNA gene analysis alone and referred to as the “root” clade, we detected no corresponding amoA gene. The amoA-contai...

  11. Enhanced nitrate and phosphate removal in a denitrifying bioreactor with biochar.

    Science.gov (United States)

    Bock, Emily; Smith, Nick; Rogers, Mark; Coleman, Brady; Reiter, Mark; Benham, Brian; Easton, Zachary M

    2015-03-01

    Denitrifying bioreactors (DNBRs) are an emerging technology used to remove nitrate-nitrogen (NO) from enriched waters by supporting denitrifying microorganisms with organic carbon in an anaerobic environment. Field-scale investigations have established successful removal of NO from agricultural drainage, but the potential for DNBRs to remediate excess phosphorus (P) exported from agricultural systems has not been addressed. We hypothesized that biochar addition to traditional woodchip DNBRs would enhance NO and P removal and reduce nitrous oxide (NO) emissions based on previous research demonstrating reduced leaching of NO and P and lower greenhouse gas production associated with biochar amendment of agricultural soils. Nine laboratory-scale DNBRs, a woodchip control, and eight different woodchip-biochar treatments were used to test the effect of biochar on nutrient removal. The biochar treatments constituted a full factorial design of three factors (biochar source material [feedstock], particle size, and application rate), each with two levels. Statistical analysis by repeated measures ANOVA showed a significant effect of biochar, time, and their interaction on NO and dissolved P removal. Average P removal of 65% was observed in the biochar treatments by 18 h, after which the concentrations remained stable, compared with an 8% increase in the control after 72 h. Biochar addition resulted in average NO removal of 86% after 18 h and 97% after 72 h, compared with only 13% at 18 h and 75% at 72 h in the control. Biochar addition also resulted in significantly lower NO production. These results suggest that biochar can reduce the design residence time by enhancing nutrient removal rates. PMID:26023979

  12. Denitrifying activity of activated sludge in suspension and in biofilm

    OpenAIRE

    Cortez, Susana; Teixeira, P.; Oliveira, Rosário; Mota, M.

    2008-01-01

    A method based on measuring substrate depletion rate was developed to evaluate the denitrifying activity of activated sludge in suspension and in biofilm form in anoxic serum flasks. The adapted activated sludge inoculum was grown as biofilm in an anoxic rotating biological contactor (RBC). Acetate was used as external carbon source to obtain a carbon to nitrogen ratio (C/N) of 2. The results showed that the specific activity of cells in biofilm form was higher than in planktonic for...

  13. Denitrifying bacterial community composition changes associated with stages of denitrification in oxygen minimum zones

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; O'Mullan, G.D.; Naqvi, S.W.A.; Ward, B.B.

    the absolute and relative abundance of denitrifying cells increase. Competition for carbon substrates, and perhaps NO 3 − , among denitrifiers becomes important, and selection starts to play a role in determining the growth success of any particular denitrify... approaching equilibrium. The niche differentiation model [49] predicts that multiple species will be maintained as long as each has a competitive advantage due to a resource, combination of resources, or environmental conditions creating a niche where each...

  14. Denitrification characteristics of a marine origin psychrophilic aerobic denitrifying bacterium.

    Science.gov (United States)

    Zheng, Haiyan; Liu, Ying; Sun, Guangdong; Gao, Xiyan; Zhang, Qingling; Liu, Zhipei

    2011-01-01

    A psychrophilic aerobic denitrifying bacterium, strain S1-1, was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system. Strain S1-1 was preliminarily identified as Psychrobacter sp. based on the analysis of its 16S rRNA gene sequence, which showed 100% sequence similarity to that of Psychrobacter sp. TSBY-70. Strain S1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite, and the total nitrogen removal rates could reach to 46.48% and 31.89%, respectively. The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low level accumulation of nitrite, suggesting that the aerobic denitrification process of strain S1-1 occurred mainly in this phase. The GC-MS results showed that N2O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1. Finally, factors affecting the growth of strain S1-1 and its aerobic denitrifying ability were also investigated. Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source, C/N ratio15, salinity 10 g/L NaCl, incubation temperature 20 degrees C and initial pH 6.5. PMID:22432315

  15. Denitrification characteristics of a marine origin psychrophilic aerobic denitrifying bacterium

    Institute of Scientific and Technical Information of China (English)

    Haiyan Zheng; Ying Liu; Guangdong Sun; Xiyan Gao; Qingling Zhang; Zhipei Liu

    2011-01-01

    A psychrophilic aerobic denitrifying bacterium,strain S1-1,was isolated from a biological aerated filter conducted for treatment of recirculating water in a marine aquaculture system.Strain S1-1 was preliminarily identified as Psychrobacter sp.based on the analysis of its 16S rRNA gene sequence,which showed 100% sequence similarity to that of Psychrobacter sp.TSBY-70.Strain S 1-1 grew well either in high nitrate or high nitrite conditions with a removal of 100% nitrate or 63.50% nitrite,and the total nitrogen removal rates could reach to 46.48% and 31.89%,respectively.The results indicated that nitrate was mainly reduced in its logarithmic growth phase with a very low leve 1 accumulation of nitrite,suggesting that the aerobic denitrification process of strain S l-1 occurred mainly in this phase.The GC-MS results showed that N2O was formed as the major intermediate during the aerobic denitrifying process of strain S1-1.Finally,factors affecting the growth of strain Sl-1 and its aerobic denitrifying ability were also investigated.Results showed that the optimum aerobic denitrification conditions for strain S1-1 were sodium succinate as carbon source,C/N ratio15,salinity 10 g/L NaCl,incubation temperature 20℃ and initial pH 6.5.

  16. Complete genome sequence of Methylophilus sp. TWE2 isolated from methane oxidation enrichment culture of tap-water.

    Science.gov (United States)

    Xia, Fei; Zou, Bin; Shen, Cong; Zhu, Ting; Gao, Xin-Hua; Quan, Zhe-Xue

    2015-10-10

    The non-methane-utilizing methylotroph, Methylophilus sp. TWE2, was isolated from tap-water during the enrichment of methanotrophs with methane. The complete genome sequence of strain TWE2 showed that this bacterium may convert methanol to formaldehyde via catalysis of methanol dehydrogenase (MDH), after which formaldehyde would be assimilated to biomass through the ribulose monophosphate (RuMP) pathway or dissimilated via the tetrahydromethanopterin (H4MPT) pathway. The deficiency of glycolysis and the TCA cycle indicate that strain TWE2 may be an obligate methylotroph. This is the first complete genome sequence of the genus Methylophilus. PMID:26253961

  17. D/H fractionation in lipids of facultative and obligate denitrifying and sulfate reducing bacteria

    Science.gov (United States)

    Osburn, M. R.; Sessions, A. L.

    2012-12-01

    The hydrogen isotopic composition of lipids has been shown to vary broadly in both cultured bacteria and in environmental samples. Culturing studies have indicated that this variability may primarily reflect metabolism; however, the limited number of organisms studied thus far prevents application of these trends to interpretation of environmental samples. Here we report D/H fractionations in anaerobic bacteria, including both facultative and obligate anaerobic organisms with a range of electron donors, acceptors, and metabolic pathways. Experiments using the metabolically flexible alphaproteobacterium Paracoccus denitrificans probe particular central metabolic pathways using a range of terminal electron acceptors. While a large range of δD values has been observed during aerobic metabolism, denitrifying cultures produce a more limited range in δD values that are more similar to each other than the corresponding aerobic culture. Data from the sulfate reducing bacteria Desulfobacterium autotrophicum and Desulfobacter hydrogenophilus indicate that chemolithoautotrophy and anaerobic heterotrophy can produce similar δD values, and are similar between bacteria despite differing metabolic pathways. These results suggest that the fractionation of D/H depends both on the specific metabolic pathway and the electron acceptor. While this is not inconsistent with previous studies, it suggests the simple correspondence between δD and metabolism previously understood from aerobic bacteria is not universally applicable.

  18. Bringing the Past to the Present. : The use of tagging and storytelling for the enrichment of cultural heritage.

    NARCIS (Netherlands)

    Vliet, H.M.M. (Harry) van; Hekman, Erik

    2011-01-01

    The Internet’s dominant role in recent years has caused a change in the relationship between media producers, suppliers and consumers in the traditional media landscape. The cultural sector must therefore decide what to do with today’s digital media in response to the general public’s changing role,

  19. An enrichment and acclimation procedure to obtain photo heterotrophic cultures for H{sub 2} production from organic effluents

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo-Benitez, J. A.; Ponce-Noyola, M. T.; Poggi-Varaldo, H. M.

    2009-07-01

    Production of H{sub 2} via photo heterotrophic is an attractive alternative, due to the capacity of photo heterotrophic organisms to convert the organic matter of effluents into H{sub 2}. The objective of our work was to develop a protocol for selecting undefined mixed cultures of photo heterotrophic microorganism with the capability of producing of H{sub 2}. (Author)

  20. ENRICHMENT AND CHARACTERIZATION OF THYMUS-REPOPULATING CELLS IN STROMA-DEPENDENT CULTURES OF RAT BONE-MARROW

    NARCIS (Netherlands)

    PRAKAPAS, Z; DENOYELLE, M; DARGEMONT, C; KROESE, FGM; THIERY, JP; DEUGNIER, MA

    1993-01-01

    The bone marrow precursor cells seeding the thymus have been difficult to investigate using fresh bone marrow and in vivo thymus reconstitution assays. We have therefore designed a short-term bone marrow culture system allowing the study of thymus-repopulating cells in the marrow microenvironment. L

  1. Elimination of pharmaceuticals in single- and three-stage pre-denitrifying MBBR

    OpenAIRE

    Polesel, Fabio; Torresi, Elena; Loreggian, L.; Escola Casas, Monica; Bester, Kai; Plósz, Benedek G.

    2015-01-01

    This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs) in single- and three-stage configurations. Under batch conditions, biotransformation and retransformation of two pharmaceuticals (trimethoprim, sulfamethoxazole) occurred at comparable or higher rates than in denitrifying activated sludge. Based on estimated rate coefficients, concentrations in continuously operated MBBRs were predicted.

  2. Thermo-acidophillic biohydrogen production from rice bran de-oiled wastewater by Selectively enriched mixed culture

    Directory of Open Access Journals (Sweden)

    D.Sivaramakrishna, D.Sreekanth, V.Himabindu, M.Lakshmi Narasu

    2010-07-01

    Full Text Available The present study focuses on the biohydrogen production in an anaerobic batch reactor operated at thermophillic (570C and acidophilic conditions (pH 6 with rice bran de-oiled wastewater (RBOW as substrate. The hydrogen generating mixed microflora was enriched from slaughter house sludge (SHS through acid treatment (pH 3-4, for 24h coupled with heat treatment (1h at 1000C to eliminate non-spore forming bacteria and to inhibit the growth of methanogenic bacteria (MB prior to inoculation in the reactor. The hydrogen production rate was maximum at 570C (1861±14ml/L-WW/d compared to 370C (651±30ml/L-ww/d. The Hydrogen yield increased with temperature from 1.1 to 2.2 molH2/mol of substrate respectively. The optimum pH range for hydrogen production in this system was observed in between 5.5 to 6. Acid-forming pathway with butyric acid as a major metabolite dominated the metabolic flow during the hydrogen production.

  3. Thermo-acidophillic biohydrogen production from rice bran de-oiled wastewater by Selectively enriched mixed culture

    Energy Technology Data Exchange (ETDEWEB)

    Sivaramakrishna, D.; Sreekanth, D.; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally Hyderabad-500 085 (India); Narasu, M. Lakshmi [Centre for Biotechnology, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally Hyderabad-500 085 (India)

    2010-07-01

    The present study focuses on the biohydrogen production in an anaerobic batch reactor operated at thermophillic (570C) and acidophilic conditions (pH 6) with rice bran de-oiled wastewater (RBOW) as substrate. The hydrogen generating mixed microflora was enriched from slaughter house sludge (SHS) through acid treatment (pH 3-4, for 24h) coupled with heat treatment (1h at 1000C) to eliminate non-spore forming bacteria and to inhibit the growth of methanogenic bacteria (MB) prior to inoculation in the reactor. The hydrogen production rate was maximum at 570C (1861 +- 14ml/L-WW/d) compared to 370C (651 +- 30ml/L-ww/d). The Hydrogen yield increased with temperature from 1.1 to 2.2 molH2/mol of substrate respectively. The optimum pH range for hydrogen production in this system was observed in between 5.5 to 6. Acid-forming pathway with butyric acid as a major metabolite dominated the metabolic flow during the hydrogen production.

  4. Characterization of a marine origin aerobic nitrifying-denitrifying bacterium.

    Science.gov (United States)

    Zheng, Hai-Yan; Liu, Ying; Gao, Xi-Yan; Ai, Guo-Min; Miao, Li-Li; Liu, Zhi-Pei

    2012-07-01

    The bacterial strain F6 was isolated from a biological aerated filter that is used for purifying recirculating water in a marine aquaculture system and was identified as Marinobacter sp. based on the analysis of its 16S rRNA gene sequence. Strain F6 showed efficient aerobic denitrifying ability. One hundred percent of nitrates and 73.10% of nitrites were removed, and the total nitrogen (TN) removal rates reached 50.08% and 33.03% under a high nitrate and nitrite concentration in the medium, respectively. N(2)O and (15)N(2), as revealed by GC-MS and GC-IRMS, were the products of aerobic denitrification. Factors affecting the growth and aerobic denitrifying performance of strain F6 were investigated. The results showed that the optimum aerobic denitrification conditions for strain F6 were the presence of sodium succinate as a carbon source, a C/N ratio of 15, salinity ranging from 32-35 g/L of NaCl, incubation temperature of 30°C, an initial pH of 7.5, and rotation speed of 150 rpm [dissolved oxygen (DO) 6.75 mg/L]. In addition, strain F6 was confirmed to be a heterotrophic nitrifier through its NO(2)(-) generation and 25.96% TN removal when NH(4)(+) was used as the sole N source. Therefore, strain F6, the first reported member of genus Marinobacter with aerobic heterotrophic nitrifying-denitrifying ability, is an excellent candidate for facilitating simultaneous nitrification and denitrification (SND) in industry and aquaculture wastewater. PMID:22578593

  5. Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

    Directory of Open Access Journals (Sweden)

    E. González-Toril

    2009-01-01

    Full Text Available Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area and the Andes (Nevado Illimani summit, Bolivia, from Antarctic aerosol (French station Dumont d'Urville and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas, in a minimal mineral (oligotrophic media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified and the marine Antarctic soil the poorest (only one. Snow samples from Col du Midi (Alps and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones. These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone. The only microorganism identified in the Antarctica soil (Brevundimonas sp. was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

  6. Chloramphenicol Inhibition of Denitrifying Enzyme Activity in Two Agricultural Soils

    OpenAIRE

    Murray, Robert E.; Knowles, Roger

    1999-01-01

    Chloramphenicol, at concentrations greater than 0.1 g/liter (0.3 mM), inhibited the denitrifying enzyme activity (DEA) of slurries of humisol and sandy loam soils by disrupting the activity of existing nitrate reductase enzymes. When the concentration of chloramphenicol was increased from 0.1 to 2.0 g/liter (6.0 mM), the rate of nitrite production from nitrate decreased by 25 to 46%. The rate of NO production from nitrate decreased by 20 to 39%, and the rate of N2O production from nitrate, in...

  7. Determination of the cause of the symptoms on yellow yam (Dioscorea cayenensis Lam.) leaf tissue and their eradication, enriching the culture medium and using techniques of meristem culture, thermo and chemotherapy on in vitro conditions

    International Nuclear Information System (INIS)

    Yams (Dioscorea spp) has been cultivated for exportation in Costa Rica, in North Huetar region. In vitro culture technique has been used for multiplying planting material for many advantages. However, cleaning of viruses that affect has been ineffective. Viruses such as: the potyvirus, potexvirus, cucumovirus . Methods like meristem culture, chemotherapy, thermotherapy and combinations of these have been used for the elimination of virus in plant species. The plants were evaluated in indexing assays, observing symptoms, serological methods and electron microscopy, among others. Other problems that have been affecting in vitro plant are deficient culture media in some nutrient. The presence of some abnormal characteristics in leaf tissue was determined whether have been caused by a virus or a nutritional deficiency in the culture medium. The presence of the virus has tried to find using ELISA and electron microscopy. Tests meristem culture, thermotherapy and chemotherapy have been made for the eradication of a possible virus; which have been assessed by observation of symptomatology and ELISA. The efficiency of the culture medium was evaluated to enrich it with nitrogen or excess iron. None of the suspected virus found in ELISA tests. Filaments are presumably viral particles were found through analysis of ultrastructure, as well as alterations in chloroplasts which indicated the presence of a pathogen or toxicity. Thermotherapy and chemotherapy with the concentration of 40 mg/L of ribavirin have been the most effective for the elimination of symptoms in virus eradication treatments. Assessments nutrient concentrations have shown that the differences between the various treatments used were undetectable. The symptoms presented were caused, according to the conclusions, by a virus which should preferably deal with thermotherapy. (author)

  8. Heavy metal incorporation in foraminiferal calcite: results from multi-element enrichment culture experiments with Ammonia tepida

    Directory of Open Access Journals (Sweden)

    G.-J. Reichart

    2010-08-01

    Full Text Available The incorporation of heavy metals into carbonate tests of the shallow water benthic foraminifer Ammonia tepida was investigated under controlled laboratory conditions. Temperature, salinity, and pH of the culture solutions were kept constant throughout the duration of this experiment, while trace metal concentrations were varied. Concentrations of Ni, Cu, and Mn were set 5-, 10-, and 20 times higher than levels found in natural North Sea water; for reference, a control experiment with pure filtered natural North Sea water was also analysed. The concentrations of Cu and Ni from newly grown chambers were determined by means of both μ-synchrotron XRF and Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS. The results of both independent analytical techniques agreed within the analytical uncertainty. In general, the concentration of the analysed elements in the tests increased in line with their concentration in the culture solutions. Potential toxic and/or chemical competition effects might have resulted in the decreased incorporation of Ni and Cu into the calcite of the specimens exposed to the highest elemental concentrations. Mn incorporation exhibited large variability in the experiment with the 20-fold increased element concentrations, potentially due to antagonistic effects with Cu. The partition coefficients of Cu and Ni were calculated to be 0.14 ± 0.02 and 1.0 ± 0.5, respectively, whereas the partition coefficient of Mn was estimated to be least 2.4. These partition coefficients now open the way for reconstructing past concentrations for these elements in sea water.

  9. Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

    Energy Technology Data Exchange (ETDEWEB)

    Boulêtreau, Stéphanie, E-mail: stephanie.bouletreau@univ-tlse3.fr [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Lyautey, Emilie [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Dubois, Sophie [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France); Compin, Arthur [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Delattre, Cécile; Touron-Bodilis, Aurélie [EDF Recherche et Développement, LNHE (Laboratoire National d' Hydraulique et Environnement), 6 quai Watier, F-78401 Chatou (France); Mastrorillo, Sylvain [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Garabetian, Frédéric [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France)

    2014-01-01

    Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age.

  10. 异养硝化/好氧反硝化菌的分离鉴定及其在不同培养条件下产N_2O研究%Isolation of Heterotrophic Nitrifiers/Aerobic Denitrifiers and Their Roles in N_2O Production for Different Incubations

    Institute of Scientific and Technical Information of China (English)

    蒋静艳; 胡正华; 黄耀

    2009-01-01

    Soil microorganisms are important sources of N_2O for the atmosphere. Peak emissions of N_2O are often observed after wetting of soil. The simultaneous heterotrophic: nitrifying and aerobic denitrifying hacteria with respect to N_2O emission were studied to obtain more information about the microbiological aspects of peak emissions. Using acelamide as the C and N source, two strains of nitrifying and denitrifying bacteria were isolated,coded as XM1 and HX2,respectively. XMlstrain was Gram-negative chain-like bacilli,and the HX2 was Gram-negative cocci. In enrichment culture,N_2O production of HX2 was 76 times more than XM1 . Two strains could grow with glucose,mannitol or sodium tartrate as sole carbon source,respectively. They could nitrify with sodium nitrate or denitrify with ammonium sulfate as unique nitrogen source, and produce intermediate product nitrite. XMlstrain growth velocity and nitrite formation were obviously higher than HX2. The phylogentic analysis based on partial 16S rDNA showed that two isolated strains were the closest relative of Pseudomonas sp.99% sequence similarity. Under different WFPS (water-filled-pore-space) conditions, the aerobic autoclaved soil incubation trial showed that, HX2 strain was suitable for growing in 30% WFPS,and N_2O production was (36.01 ± 2.48) ng/g which was 1.9 times than that in 60% WFPS. But XM1 was suitable for growing in 60% WFPS and almost had no N_2O production. To investigate the nitrifying and denitrifying mechanisms of heterotrophic nitrifiers/aerobic denitrifiers should be useful for mastering the mitigation way of soil N_2O emission in future.%以乙酰胺为唯一碳氮源分离纯化出2株既能异养硝化又能好氧反硝化的菌株XM1和HX2,革兰氏阴性,分别为链状杆菌和球状菌.在富集培养基中,菌株HX2产N_2O量为XM1的76倍;两菌株均能分别以葡萄糖、甘露醇、酒石酸钠为唯一碳源进行生长;也可分别以硝酸钠和硫酸铵为唯一氮源进行硝化

  11. Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

    NARCIS (Netherlands)

    Kampman, C.; Hendrickx, T.L.G.; Luesken, F.; Alen, T.A.; Jetten, M.S.M.; Camp, op den H.J.M.; Zeeman, G.; Buisman, C.J.N.; Temmink, B.G.

    2012-01-01

    Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and metha

  12. Dynamic Metabolic Modeling of Denitrifying Bacterial Growth: The Cybernetic Approach

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hyun-Seob; Liu, Chongxuan

    2015-06-29

    Denitrification is a multistage reduction process converting nitrate ultimately to nitrogen gas, carried out mostly by facultative bacteria. Modeling of the denitrification process is challenging due to the complex metabolic regulation that modulates sequential formation and consumption of a series of nitrogen oxide intermediates, which serve as the final electron acceptors for denitrifying bacteria. In this work, we examined the effectiveness and accuracy of the cybernetic modeling framework in simulating the growth dynamics of denitrifying bacteria in comparison with kinetic models. In four different case studies using the literature data, we successfully simulated diauxic and triauxic growth patterns observed in anoxic and aerobic conditions, only by tuning two or three parameters. In order to understand the regulatory structure of the cybernetic model, we systematically analyzed the effect of cybernetic control variables on simulation accuracy. The results showed that the consideration of both enzyme synthesis and activity control through u- and v-variables is necessary and relevant and that uvariables are of greater importance in comparison to v-variables. In contrast, simple kinetic models were unable to accurately capture dynamic metabolic shifts across alternative electron acceptors, unless an inhibition term was additionally incorporated. Therefore, the denitrification process represents a reasonable example highlighting the criticality of considering dynamic regulation for successful metabolic modeling.

  13. Simultaneous denitrifying phosphorus accumulation in a sequencing batch reactor

    Institute of Scientific and Technical Information of China (English)

    YUAN Linjiang; HAN Wei; WANG Lei; YANG Yongzhe; WANG Zhiying

    2007-01-01

    In order to achieve simultaneous nitrogen and phosphorus removal in the biological treatment process,denitrifying phosphorus accumulation(DNPA)and its affecting factors were studied in a sequencing batch reactor(SBR)with synthetic wastewater.The results showed that when acetate was used as the sole carbon resource in the influent.the sludge acclimatized under anaerobic/aerobic operation had good phosphorus removal ability.Denitrifying phosphorus accumulation was observed soon when fed with nitrate instead of aeration following the anaerobic stage,which is a vital premise to DNPA.If DNPA sludge is fed with nitrate prior to the anaerobic stage,the DNPA would weaken or even disappear.At the high concen tration of nitrate fed in the anoxic stage,the longer anoxic time needed,the better the DNPA was.Induced DNPA did not disappear even though an aerobic stage followed the anoxic stage,but the shorter the aerobic stage lasted,the higher the proportions of phosphorus removal via DNPA to total removal.

  14. Denitrifying Bioreactors for Nitrate Removal: A Meta-Analysis.

    Science.gov (United States)

    Addy, Kelly; Gold, Arthur J; Christianson, Laura E; David, Mark B; Schipper, Louis A; Ratigan, Nicole A

    2016-05-01

    Meta-analysis approaches were used in this first quantitative synthesis of denitrifying woodchip bioreactors. Nitrate removal across environmental and design conditions was assessed from 26 published studies, representing 57 separate bioreactor units (i.e., walls, beds, and laboratory columns). Effect size calculations weighted the data based on variance and number of measurements for each bioreactor unit. Nitrate removal rates in bed and column studies were not significantly different, but both were significantly higher than wall studies. In denitrifying beds, wood source did not significantly affect nitrate removal rates. Nitrate removal (mass per volume) was significantly lower in beds with effects with bed temperature; a of 2.15 was quite similar to other studies. Lessons from this meta-analysis can be incorporated into bed designs, especially extending hydraulic retention times to increase nitrate removal under low temperature and high flow conditions. Additional column studies are warranted for comparative assessments, as are field-based studies for assessing in situ conditions, especially in aging beds, with careful collection and reporting of design and environmental data. Future assessment of these systems might take a holistic view, reviewing nitrate removal in conjunction with other processes, including greenhouse gas and other unfavorable by-product production. PMID:27136153

  15. Is Job Enrichment Really Enriching?

    OpenAIRE

    Robert D. Mohr; Cindy Zoghi

    2006-01-01

    This study uses a survey of Canadian workers with rich, matched data on job characteristics to examine whether “enriched” job design, with features like quality circles, feedback, suggestion programs, and task teams, affects job satisfaction. We identify two competing hypotheses on the relationship between enriched jobs and job satisfaction. The “motivation hypothesis,” implies that enrichment will generally increase satisfaction and the “intensification hypothesis,” implies that enrichment m...

  16. The social cost of coastal erosion. Using cultural theory to enrich the interpretation of stated preference data.

    Science.gov (United States)

    Kontogianni, A.; Tourkolias, C.; Vousdoukas, M.; Skourtos, M.

    2012-04-01

    Natural coastal processes are to a great extent modified by proximity to man-made structures. Engineered interventions, port facilities, housing and industrial infrastructure, all can increase the coastline fluctuations significantly relative to those along a long unobstructed coastline. As a consequence, coastlines are increasingly exposed to coastal erosion, a phenomenon defined as the encroachment of land by the sea after averaging over a period, which is sufficiently long to eliminate the impacts of weather, storm events and local sediment dynamics. In order to provide cost effective management of coastal erosion it is crucial to estimate both the benefits and costs associated with various management alternatives. The initiatives on Integrated Coastal Zone Manegment in Europe, but also the upcoming Marine Strategy Framwork Directive would benefit greatly from a proliferation of socioeconomic information to assist decision makers who must weigh the impacts of various types of coastal improvement and the cost of beach protection/restoration. In that spirit, the objective of the present research is to report the results of a survey undertaken in two resort beaches on the island of Lesvos (Greece), designed to estimate public preferences for avoiding coastal erosion. A mixed methodological approach is employed by combining an open-ended contingent valuation survey with cultural theory of risk perception. The empirical models to analyze individual choices of erosion control programs and the associated welfare measures are presented, followed by the discussion of model specification and estimation issues, and the results of the data analysis. Some concluding remarks are then presented. By choosing this approach we aim at improving our understanding of preference structure for avoiding public risk, accepted level of risk and perceptions thereof. The framework can also be used for assessing the social cost of extreme weather events such as storm surges in the coastal

  17. Uranium enrichment

    International Nuclear Information System (INIS)

    GAO was asked to address several questions concerning a number of proposed uranium enrichment bills introduced during the 100th Congress. The bill would have restructured the Department of Energy's uranium enrichment program as a government corporation to allow it to compete more effectively in the domestic and international markets. Some of GAO's findings discussed are: uranium market experts believe and existing market models show that the proposed DOE purchase of a $750 million of uranium from domestic producers may not significantly increase production because of large producer-held inventories; excess uranium enrichment production capacity exists throughout the world; therefore, foreign producers are expected to compete heavily in the United States throughout the 1990s as utilities' contracts with DOE expire; and according to a 1988 agreement between DOE's Offices of Nuclear Energy and Defense Programs, enrichment decommissioning costs, estimated to total $3.6 billion for planning purposes, will be shared by the commercial enrichment program and the government

  18. Enriching Number Knowledge

    Science.gov (United States)

    Mack, Nancy K.

    2011-01-01

    Exploring number systems of other cultures can be an enjoyable learning experience that enriches students' knowledge of numbers and number systems in important ways. It helps students deepen mental computation fluency, knowledge of place value, and equivalent representations for numbers. This article describes how the author designed her…

  19. Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition

    International Nuclear Information System (INIS)

    The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed.

  20. Greenhouse Gas Emission from In-situ Denitrifying Bioreactors

    Science.gov (United States)

    Pluer, W.; Walter, M. T.; Geohring, L.

    2013-12-01

    Despite decades of concerted effort to mitigate nonpoint source nitrate (NO3-) pollution from agricultural lands, these efforts have not been sufficient to arrest eutrophication, which continues to be a serious and chronic problem. Two primary processes for removing excess NO3- from water are biological assimilation and denitrification. Denitrifying bacteria use NO3- as the electron acceptor for respiration in the absence of oxygen. Denitrification results in reduced forms of nitrogen, often dinitrogen gas (N2) but also nitrous oxide (N2O), an aggressive greenhouse gas (GHG). A promising solution to NO3- pollution is to intercept agricultural discharges with denitrifying bioreactors (DNBRs), though research has been limited to NO3- level reduction and omitted process mechanisms. DNBRs work by providing an anaerobic environment with plenty of organic matter (commonly woodchips) for denitrifying bacteria to flourish. While, initial results from bioreactor studies show that they can cost-effectively remove NO3-, GHG emission could be an unintended consequence. The study's goal is to determine how bioreactor design promotes microbial denitrification while limiting N2O production. It specifically focuses on expanding the body of knowledge concerning DNBRs in the areas of design implications and internal processes by measuring intermediate compounds and not solely NO3-. Nutrient samples are collected at inflow and outflow structures and tested for NO3- and nitrite (NO2-). Dissolved and headspace gas samples are collected and tested for N2O. Additional gas samples will be analyzed for naturally-occurring isotopic N2 to support proposed pathways. Designs will be analyzed both through the N2O/N2 production ratio and NO2- production caused by various residence times and inflow NO3- concentrations. High GHG ratios and NO2- production suggest non-ideal conditions or flow patterns for complete denitrification. NO3- reduction is used for comparison with previous studies. Few

  1. Uranium enrichment

    International Nuclear Information System (INIS)

    Canada is the world's largest producer and exporter of uranium, most of which is enriched elsewhere for use as fuel in LWRs. The feasibility of a Canadian uranium-enrichment enterprise is therefore a perennial question. Recent developments in uranium-enrichment technology, and their likely impacts on separative work supply and demand, suggest an opportunity window for Canadian entry into this international market. The Canadian opportunity results from three particular impacts of the new technologies: 1) the bulk of the world's uranium-enrichment capacity is in gaseous diffusion plants which, because of their large requirements for electricity (more than 2000 kW·h per SWU), are vulnerable to competition from the new processes; 2) the decline in enrichment costs increases the economic incentive for the use of slightly-enriched uranium (SEU) fuel in CANDU reactors, thus creating a potential Canadian market; and 3) the new processes allow economic operation on a much smaller scale, which drastically reduces the investment required for market entry and is comparable with the potential Canadian SEU requirement. The opportunity is not open-ended. By the end of the century the enrichment supply industry will have adapted to the new processes and long-term customer/supplier relationships will have been established. In order to seize the opportunity, Canada must become a credible supplier during this century

  2. 短程反硝化除磷系统的驯化及除磷特性研究%Domestication of Denitrifying Phosphorus Removal System and Characteristics of Phosphorus Removal

    Institute of Scientific and Technical Information of China (English)

    唐旭光; 王淑莹; 张婧倩

    2009-01-01

    依据反硝化除磷(DBP)原理,采用批式试验,以城市污水为处理对象,研究了以NO_2~-为电子受体的反硝化除磷菌的筛选与富集,并对其反硝化除磷性能进行了考察.结果表明:NO_2~-对传统EBPR系统的抑制作用明显高于以NO_3~-为电子受体的反硝化除磷系统;对以NO_3~-为电子受体的反硝化除磷污泥用NO_2~-进行驯化,经过52个周期,缺氧吸磷量由0.3 mg/L升高到9.1mg/L,短程反硝化除磷系统驯化成熟;驯化成熟的短程反硝化除磷系统仍能以氧和NO_3~-作为电子受体进行吸磷并维持较高的吸磷速率,以亚硝酸盐为电子受体的除磷菌占总除磷菌的58.82%,说明短程反硝化除磷菌存在于传统除磷系统中,且能够很好地利用氧和硝酸盐为电子受体进行反硝化除磷.%Based on the denitrifying phosphorus removal principle, batch experiments were used to treat municipal wastewater. The screening and enrichment of denitrifying phosphorus removing bacteria using nitrite as electron acceptor and their characteristics were studied. The results show that the nitrite is more inhibitory to the EBPR system than denitrifying phosphorus removal system using nitrate as electron aeeeptor. The denitrifying phosphorus removal sludge using nitrate as electron acceptor is domesticated by nitrite. After 52 cycles, anoxie phosphorus uptake is increased from 0.3 mg/L to 9.1 mg/L. The short-cut denitrifying phosphorus removal system is domesticated maturely, and it can also use oxygen and nitrate as the electrun acceptors to take up phosphorus and keep a high phosphorus uptake rate. The phosphorus removing bacteria using nitrite as electron aeeeptor account for 58.82%, showing that the shortcut denitrifying phosphorus removing bacteria exist in the conventional phosphorus removal system and can well use oxygen and nitrate as the electron acceptors for denitrifying phosphorus removal.

  3. CD133-enriched Xeno-Free human embryonic-derived neural stem cells expand rapidly in culture and do not form teratomas in immunodeficient mice

    Directory of Open Access Journals (Sweden)

    Daniel L. Haus

    2014-09-01

    Full Text Available Common methods for the generation of human embryonic-derived neural stem cells (hNSCs result in cells with potentially compromised safety profiles due to maintenance of cells in conditions containing non-human proteins (e.g. in bovine serum or on mouse fibroblast feeders. Additionally, sufficient expansion of resulting hNSCs for scaling out or up in a clinically relevant time frame has proven to be difficult. Here, we report a strategy that produces hNSCs in completely “Xeno-Free” culture conditions. Furthermore, we have enriched the hNSCs for the cell surface marker CD133 via magnetic sorting, which has led to an increase in the expansion rate and neuronal fate specification of the hNSCs in vitro. Critically, we have also confirmed neural lineage specificity upon sorted hNSC transplantation into the immunodeficient NOD-scid mouse brain. The future use or adaptation of these protocols has the potential to better facilitate the advancement of pre-clinical strategies from the bench to the bedside.

  4. Development and evaluation of a loop-mediated isothermal amplification assay combined with enrichment culture for rapid detection of very low numbers of Vibrio parahaemolyticus in seafood samples.

    Science.gov (United States)

    Di, Huiling; Ye, Lei; Neogi, Sucharit Basu; Meng, Hecheng; Yan, He; Yamasaki, Shinji; Shi, Lei

    2015-01-01

    The aim of this study was to develop and evaluate a rapid and effective method to detect Vibrio parahaemolyticus, a leading pathogen causing seafood-borne gastroenteritis. A newly designed loop-mediated isothermal amplification (LAMP) assay including a short enrichment period was optimized. This assay correctly detected all the target strains (n=61) but none of the non-target strains (n=34). Very low numbers of V. parahaemolyticus (2 colony forming unit (CFU) per gram of seafood) could be detected within 3 h and the minimum time of the whole assay was only 5 h. Comparative screening of various seafood samples (n=70) indicated that the LAMP assay is superior to polymerase chain reaction (PCR) and conventional culture methods because it is more rapid and less complex. This highly sensitive LAMP assay can be applicable as the method of choice in large-scale and rapid screening of seafood and environmental samples to detect V. parahaemolyticus strains. PMID:25744462

  5. Nitrogen removal from wastewater by anaerobic methane-driven denitrification in a lab-scale reactor: heterotrophic denitrifiers associated with denitrifying methanotrophs.

    Science.gov (United States)

    He, Zhanfei; Wang, Jiaqi; Zhang, Xu; Cai, Chaoyang; Geng, Sha; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-12-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is a newly discovered bioprocess that reduces nitrite to dinitrogen with methane as electron donor, which has promising potential to remove nitrogen from wastewater. In this work, a lab-scale sequencing batch reactor (SBR) was operated for 609 days with methane as the sole external electron donor. In the SBR, nitrite in synthetic wastewater was removed continuously; the final volumetric nitrogen removal rate was 12.22±0.02 mg N L(-1) day(-1) and the percentage of nitrogen removal was 98.5 ± 0.2 %. Microbial community analysis indicated that denitrifying methanotrophs dominated (60-70 %) the population of the final sludge. Notably, activity testing and microbial analysis both suggested that heterotrophic denitrifiers existed in the reactor throughout the operation period. After 609 days, the activity testing indicated the nitrogen removal percentage of heterotrophic denitrification was 17 ± 2 % and that of n-damo was 83 ± 2 %. A possible mutualism may be developed between the dominated denitrifying methanotrophs and the associated heterotrophs through cross-feed. Heterotrophs may live on the microbial products excreted by denitrifying methanotrophs and provide growth factors that are required by denitrifying methanotrophs. PMID:26342737

  6. Enrichment of the Cancer Stem Phenotype in Sphere Cultures of Prostate Cancer Cell Lines Occurs through Activation of Developmental Pathways Mediated by the Transcriptional Regulator ΔNp63α.

    Directory of Open Access Journals (Sweden)

    Roberto Portillo-Lara

    Full Text Available Cancer stem cells (CSC drive prostate cancer tumor survival and metastasis. Nevertheless, the development of specific therapies against CSCs is hindered by the scarcity of these cells in prostate tissues. Suspension culture systems have been reported to enrich CSCs in primary cultures and cell lines. However, the molecular mechanisms underlying this phenomenon have not been fully explored.We describe a prostasphere assay for the enrichment of CD133+ CSCs in four commercial PCa cell lines: 22Rv1, DU145, LNCaP, and PC3. Overexpression of CD133, as determined by flow cytometric analysis, correlated with an increased clonogenic, chemoresistant, and invasive potential in vitro. This phenotype is concordant to that of CSCs in vivo. Gene expression profiling was then carried out using the Cancer Reference panel and the nCounter system from NanoString Technologies. This analysis revealed several upregulated transcripts that can be further explored as potential diagnostic markers or therapeutic targets. Furthermore, functional annotation analysis suggests that ΔNp63α modulates the activation of developmental pathways responsible for the increased stem identity of cells growing in suspension cultures.We conclude that profiling the genetic mechanisms involved in CSC enrichment will help us to better understand the molecular pathways that underlie CSC pathophysiology. This platform can be readily adapted to enrich and assay actual patient samples, in order to design patient-specific therapies that are aimed particularly against CSCs.

  7. Microbial diversity in methanogenic hydrocarbon-degrading enrichment cultures isolated from a water-flooded oil reservoir (Dagang oil field, China)

    Science.gov (United States)

    Jiménez, Núria; Cai, Minmin; Straaten, Nontje; Yao, Jun; Richnow, Hans H.; Krüger, Martin

    2015-04-01

    Microbial transformation of oil to methane is one of the main degradation processes taking place in oil reservoirs, and it has important consequences as it negatively affects the quality and economic value of the oil. Nevertheless, methane could constitute a recovery method of carbon from exhausted reservoirs. Previous studies combining geochemical and isotopic analysis with molecular methods showed evidence for in situ methanogenic oil degradation in the Dagang oil field, China (Jiménez et al., 2012). However, the main key microbial players and the underlying mechanisms are still relatively unknown. In order to better characterize these processes and identify the main microorganisms involved, laboratory biodegradation experiments under methanogenic conditions were performed. Microcosms were inoculated with production and injection waters from the reservoir, and oil or 13C-labelled single hydrocarbons (e.g. n-hexadecane or 2-methylnaphthalene) were added as sole substrates. Indigenous microbiota were able to extensively degrade oil within months, depleting most of the n-alkanes in 200 days, and producing methane at a rate of 76 ± 6 µmol day-1 g-1 oil added. They could also produce heavy methane from 13C-labeled 2-methylnaphthalene, suggesting that further methanogenesis may occur from the aromatic and polyaromatic fractions of Dagang reservoir fluids. Microbial communities from oil and 2-methyl-naphthalene enrichment cultures were slightly different. Although, in both cases Deltaproteobacteria, mainly belonging to Syntrophobacterales (e.g. Syntrophobacter, Smithella or Syntrophus) and Clostridia, mostly Clostridiales, were among the most represented taxa, Gammaproteobacteria could be only identified in oil-degrading cultures. The proportion of Chloroflexi, exclusively belonging to Anaerolineales (e.g. Leptolinea, Bellilinea) was considerably higher in 2-methyl-naphthalene degrading cultures. Archaeal communities consisted almost exclusively of representatives of

  8. Elimination of pharmaceuticals in single- and three-stage pre-denitrifying MBBR

    DEFF Research Database (Denmark)

    Polesel, Fabio; Torresi, Elena; Loreggian, L.;

    This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs) in single- and three-stage configurations. Under batch conditions, biotransformation and retransformation of two pharmaceuticals (trimethoprim, sulfamethoxazole) occurred at comparable...

  9. A Comparative Study of the Bacterial Community in Denitrifying and Traditional Enhanced Biological Phosphorus Removal Processes

    OpenAIRE

    Lv, Xiao-Mei; Shao, Ming-Fei; Li, Chao-Lin; Li, Ji; Gao, Xin-lei; Sun, Fei-Yun

    2014-01-01

    Denitrifying phosphorus removal is an attractive wastewater treatment process due to its reduced carbon source demand and sludge minimization potential. Two lab-scale sequencing batch reactors (SBRs) were operated in alternating anaerobic-anoxic (A-A) or anaerobic-oxic (A-O) conditions to achieve denitrifying enhanced biological phosphate removal (EBPR) and traditional EBPR. No significant differences were observed in phosphorus removal efficiencies between A-A SBR and A-O SBR, with phosphoru...

  10. Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support

    Science.gov (United States)

    Sakano, Yuko; Pickering, Karen D.; Strom, Peter F.; Kerkhof, Lee J.; Janes, H. W. (Principal Investigator)

    2002-01-01

    Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.

  11. Effect of pH on the denitrifying enzyme activity in pasture soils in relation to the intrinsic differences in denitrifier communities

    OpenAIRE

    Čuhel, Jiří

    2011-01-01

    The effects of pH on denitrifying enzyme activity (DEA) and on the ratio of the denitrification products, N2O and N2, were determined in three pasture soils differing in cattle impact. The linkage between intrinsic differences in the denitrifying communities and pH effects on relative N2O production was also assessed. The soils were therefore analyzed for DEA and N2O production over a range of pH values and for the kinetic constants of NO3- and N2O reductions.

  12. Analysis of denitrifier community in a bioaugmented sequencing batch reactor for the treatment of coking wastewater containing pyridine and quinoline

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yaohui; Xing, Rui; Wen, Donghui; Tang, Xiaoyan [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Sun, Qinghua [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Chinese Center for Disease Control and Prevention, Beijing (China). Inst. of Environmental Health and Related Product Safety

    2011-05-15

    The denitrifier community and associated nitrate and nitrite reduction in the bioaugmented and general sequencing batch reactors (SBRs) during the treatment of coking wastewater containing pyridine and quinoline were investigated. The efficiency and stability of nitrate and nitrite reduction in SBR was considerably improved after inoculation with four pyridine- or quinoline-degrading bacterial strains (including three denitrifying strains). Terminal restriction fragment length polymorphism (T-RFLP) based on the nosZ gene revealed that the structures of the denitrifier communities in bioaugmented and non-bioaugmented reactors were distinct and varied during the course of the experiment. Bioaugmentation protected indigenous denitrifiers from disruptions caused by pyridine and quinoline. Clone library analysis showed that one of the added denitrifiers comprised approximately 6% of the denitrifier population in the bioaugmented sludge. (orig.)

  13. 一个硫酸盐还原细菌富集物对丁草胺的厌氧降解%Anaerobic degradation of butachlor by sulfate-reducing bacteria enrichment culture

    Institute of Scientific and Technical Information of China (English)

    叶央芳; 杜宇峰

    2000-01-01

    An enrichment culture of sulfate-reducing bacteria,capable of anaerabic degrading butachlor,was obtained.The degradation kinetics of butachlor by the enrichment culture was determined and the optimum concentration of butachlor,the optimum pH and temperature for degradation of butachlor were observed..%通过多次富集培养,得到一个能有效厌氧降解丁草胺的硫酸盐还原细菌(SRB)富集物,并对该富集物的生长动力学以及生长的最适丁草胺浓度、最适pH和最适温度作了探讨.

  14. Job Enrichment

    Science.gov (United States)

    Sanders, Rick

    1970-01-01

    Job enrichment means giving people more decision-making power, more responsibility, more grasp of the totality of the job, and a sense of their own importance in the company. This article presents evidence of the successful working of this approach (Donnelly Mirrors), and the lack of success with an opposing approach (General Motors). (NL)

  15. A combined approach for the enhanced detection and isolation of Bartonella species in dog blood samples: pre-enrichment liquid culture followed by PCR and subculture onto agar plates.

    Science.gov (United States)

    Duncan, Ashlee W; Maggi, Ricardo G; Breitschwerdt, Edward B

    2007-05-01

    Historically, direct plating, lysis centrifugation, or freeze-thaw approaches have proven to be highly insensitive methods for confirming Bartonella species infection in dogs. A prospective study was designed to compare diagnostic methods for the detection of Bartonella using samples submitted to the Vector-Borne Disease Diagnostic Laboratory at North Carolina State University. Methods included indirect immunofluorescence assay, PCR, direct inoculation of a blood agar plate (trypticase soy agar with 5% rabbit blood), and inoculation into a novel pre-enrichment liquid medium, Bartonella/alpha-Proteobacteria growth medium (BAPGM). Sequential research efforts resulted in the development of a combinational approach consisting of pre-enrichment culture of Bartonella species in BAPGM, sub-inoculation of the liquid culture onto agar plates, followed by DNA amplification using PCR. The multi-faceted approach resulted in substantial improvement in the microbiological detection and isolation of Bartonella when compared to direct inoculation of a blood agar plate. Importantly, this approach facilitated the detection and subsequent isolation of both single and co-infections with two Bartonella species in the blood of naturally infected dogs. The use of a combinational approach of pre-enrichment culture and PCR may assist in the diagnostic confirmation of bartonellosis in dogs and other animals.

  16. The effects of co-contaminants and native wetland sediments on the activity and dominant transformation mechanisms of a 1,1,2,2-tetrachloroethane (TeCA)-degrading enrichment culture

    Science.gov (United States)

    Lorah, Michelle M.; Schiffmacher, Emily N.; Becker, Jennifer G.; Voytek, Mary A.

    2016-01-01

    Bioremediation strategies, including bioaugmentation with chlorinated ethene-degrading enrichment cultures, have been successfully applied in the cleanup of subsurface environments contaminated with tetrachloroethene (PCE) and/or trichloroethene (TCE). However, these compounds are frequently found in the environment as components of mixtures that may also contain chlorinated ethanes and methanes. Under these conditions, the implementation of bioremediation may be complicated by inhibition effects, particularly when multiple dehalorespirers are present. We investigated the ability of the 1,1,2,2-tetrachloroethane (TeCA)-dechlorinating culture WBC-2 to biotransform TeCA alone, or a mixture of TeCA plus PCE and carbon tetrachloride (CT), in microcosms. The microcosms contained electron donors provided to biostimulate the added culture and sediment collected from a wetland where numerous “hotspots” of contamination with chlorinated solvent mixtures exist. The dominant TeCA biodegradation mechanism mediated by the WBC-2 culture in the microcosms was different in the presence of these wetland sediments than in the sediment-free enrichment culture or in previous WBC-2 bioaugmented microcosms and column tests conducted with wetland sediment collected at nearby sites. The co-contaminants and their daughter products also inhibited TeCA biodegradation by WBC-2. These results highlight the need to conduct biodegradability assays at new sites, particularly when multiple contaminants and dehalorespiring populations are present.

  17. The effects of co-contaminants and native wetland sediments on the activity and dominant transformation mechanisms of a 1,1,2,2-tetrachloroethane (TeCA)-degrading enrichment culture.

    Science.gov (United States)

    Schiffmacher, Emily N; Becker, Jennifer G; Lorah, Michelle M; Voytek, Mary A

    2016-03-01

    Bioremediation strategies, including bioaugmentation with chlorinated ethene-degrading enrichment cultures, have been successfully applied in the cleanup of subsurface environments contaminated with tetrachloroethene (PCE) and/or trichloroethene (TCE). However, these compounds are frequently found in the environment as components of mixtures that may also contain chlorinated ethanes and methanes. Under these conditions, the implementation of bioremediation may be complicated by inhibition effects, particularly when multiple dehalorespirers are present. We investigated the ability of the 1,1,2,2-tetrachloroethane (TeCA)-dechlorinating culture WBC-2 to biotransform TeCA alone, or a mixture of TeCA plus PCE and carbon tetrachloride (CT), in microcosms. The microcosms contained electron donors provided to biostimulate the added culture and sediment collected from a wetland where numerous "hotspots" of contamination with chlorinated solvent mixtures exist. The dominant TeCA biodegradation mechanism mediated by the WBC-2 culture in the microcosms was different in the presence of these wetland sediments than in the sediment-free enrichment culture or in previous WBC-2 bioaugmented microcosms and column tests conducted with wetland sediment collected at nearby sites. The co-contaminants and their daughter products also inhibited TeCA biodegradation by WBC-2. These results highlight the need to conduct biodegradability assays at new sites, particularly when multiple contaminants and dehalorespiring populations are present. PMID:26766361

  18. Denitrifying bacteria from the terrestrial subsurface exposed to mixed waste contamination

    International Nuclear Information System (INIS)

    In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available with which to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria) and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were confirmed as complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. Ribosomal RNA gene analyses reveal that bacteria from the genus Rhodanobacter comprise a diverse population of circumneutral to moderately acidophilic denitrifiers at the ORIFRC site, with a high relative abundance in areas of the acidic source zone. Rhodanobacter species do not contain a periplasmic nitrite reductase and have not been previously detected in functional gene surveys of denitrifying bacteria at the OR-IFRC site. Sequences of nitrite and nitrous oxide reductase genes were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation, genomic and metagenomic data are essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifying microorganisms. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface.

  19. Microbiological Denitrification and Denitrifying Activity of Paracoccus Denitrificans

    Institute of Scientific and Technical Information of China (English)

    万曦; 万国江; 等

    2000-01-01

    With rapidly industrial and agricultural development,more and more fertilizers,chemicals and heavy ions will be discharged into lakes and rivers,which would cause lake eutrophication and quality deterioration in drinking water sources.Therefore,denitrification is essential for controlling the amounts of nitrogen,During the transformation process from nitrate to the end products-nitrogen and several intermediated[e.g.nitrite(NO2-),nitrous oxide(N2O) and nitric oxide(NO)]may be accumulated,which have more toxic influences on the environment.in This study,the denitrification effect of Paracoccus Denitrificans was examined on the changes between oxic and anoxic conditions at varying pH.At pH=7.5,denitrification proceeded well after 3 switches from oxic to anoxic conditions and vice versa,Production of N2 was constant and the amounts of NO2-,N2O and NO were extremely low.How ever,at pH=6.8,denitrification activity was inhitied and there large amounts of the intermaediates.The denitrifying bacteria decreased violently in dry weight and were washed out.

  20. Uranium enrichment

    International Nuclear Information System (INIS)

    This paper reports that in 1990 the Department of Energy began a two-year project to illustrate the technical and economic feasibility of a new uranium enrichment technology-the atomic vapor laser isotope separation (AVLIS) process. GAO believes that completing the AVLIS demonstration project will provide valuable information about the technical viability and cost of building an AVLIS plant and will keep future plant construction options open. However, Congress should be aware that DOE still needs to adequately demonstrate AVLIS with full-scale equipment and develop convincing cost projects. Program activities, such as the plant-licensing process, that must be completed before a plant is built, could take many years. Further, an updated and expanded uranium enrichment analysis will be needed before any decision is made about building an AVLIS plant. GAO, which has long supported legislation that would restructure DOE's uranium enrichment program as a government corporation, encourages DOE's goal of transferring AVLIS to the corporation. This could reduce the government's financial risk and help ensure that the decision to build an AVLIS plant is based on commercial concerns. DOE, however, has no alternative plans should the government corporation not be formed. Further, by curtailing a planned public access program, which would have given private firms an opportunity to learn about the technology during the demonstration project, DOE may limit its ability to transfer AVLIS to the private sector

  1. Positive role of nitrite as electron acceptor on anoxic denitrifying phosphorus removal process

    Institute of Scientific and Technical Information of China (English)

    HUANG RongXin; LI Dong; LI XiangKun; BAO LinLin; JIANG AnXi; ZHANG Jie

    2007-01-01

    Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process.Batch test experiments were used to investigate the inhibitory effect during the anoxic condition.The inoculated activated sludge was taken from a continuous double- sludge denitrifying phosphorus and nitrogen removal system.Nitrite was added at the anoxic stage.One time injection and sequencing batch injection were carried on in the denitrifying dephosphorus procedure.The results indicated that the nitrite concentration higher than 30 mg/L would inhibit the anoxic phosphate uptake severely, and the threshold inhibitory concentration was dependent on the characteristics of the activated sludge and the operating conditions; instead, lower than the inhibitory concentration would not be detrimental to anoxic phosphorus uptake, and it could act as good electron acceptor for the anoxic phosphate accumulated.Positive effects performed during the denitrifying biological dephosphorus all the time.The utility of nitrite as good electron acceptor would provide a new feasible way in the denitrifying phosphorus process.

  2. Effect of denitrifying bacteria on the electrochemical reaction of activated carbon fiber in electrochemical biofilm system

    Institute of Scientific and Technical Information of China (English)

    YING Diwen; JIA Jinping; ZHANG Lehua

    2007-01-01

    An electrochemical-activated denitrifying biofilm system consisting of activated carbon fiber electrodes immobilized with denitrifying bacteria film as cathode was studied.A revised model for an electrochemical-activated denitrifying biofilm was developed and validated by electrochemical analysis of cathodal polarization curves and nitrate consumption rate.The cathodal polarization curve and nitrate consumption rate were introduced to verify the rate of electrochemical reaction and the activity of denitrifying bacteria,respectively.It was shown that the denitrification process effectively strengthened the electrochemical reaction while the electron also intensified denitrification activity.Electron was transferred between electrochemical process and biological process not only by hydrogen molecule but also by new produced active hydrogen atom.Additionally,a parameter of apparent exchange current density was deprived from the cathodal polarization curve with high overpotential,and a new bio-effect current density was defined through statistical analysis,which was linearly dependent to the activity of denitrification bacteria.Activated carbon fiber (ACF) electrode was also found to be more suitable to the electrochemical denitrifying system compared with graphite and platinum.

  3. Rapid identification of Salmonella serovars in feces by specific detection of virulence genes, invA and spvC, by an enrichment broth culture-multiplex PCR combination assay.

    Science.gov (United States)

    Chiu, C H; Ou, J T

    1996-10-01

    In order to make a rapid and definite diagnosis of Salmonella enteritis in children, an enrichment broth culture-multiplex PCR combination assay was devised to identify Salmonella serovars directly from fecal samples. Two pairs of oligonucleotide primers were prepared according to the sequences of the chromosomal invA and plasmid spvC genes. PCR with these two primers would produce either one amplicon (from the invA gene) or two amplicons (from the invA and spvC genes), depending on whether or not the Salmonella bacteria contained a virulence plasmid. The fecal sample was diluted 10- to 20-fold into gram-negative enrichment broth and incubated to eliminate inhibitory compounds and also to allow selective enrichment of the bacteria. One or two amplicons were obtained, the expected result if Salmonella bacteria were present. The detection limit of this PCR was about 200 bacteria per reaction mixture. The primers were specific, as no amplification products were obtained with 18 species and 22 isolates of non-Salmonella bacteria tested which could be present in the feces or cause contamination. In contrast, when 23 commonly seen Salmonella serovars (38 isolates) were tested, all were shown to carry the invA gene and seven concomitantly harbored the spvC gene of the virulence plasmid. This assay was applied to the diagnosis of Salmonella enteritis in 57 children who were suffering from mucoid and/or bloody diarrhea. Of the 57 children, 38 were PCR positive and 22 were culture positive. There were two culture-positive samples that were not detected by PCR. Thus, this PCR assay showed an efficiency of 95% (38 of 40), which is much higher than the 60% (24 of 40) by culture alone. Not only is this method more sensitive, rapid, and efficient but it will cause only an incremental increase in the cost of stool processing, since enrichment cultivation of fecal samples from diarrheal patients using gram-negative enrichment broth is a routine practice for identification in many

  4. Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen

    NARCIS (Netherlands)

    Lipsewers, Y.A.; Hopmans, E.C.; Meysman, F.J.R.; Sinninghe Damsté, J.S.; Villanueva, L.

    2016-01-01

    Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, an

  5. Differential Isotopic Fractionation during Cr(VI) Reduction by an Aquifer-Derived Bacterium under Aerobic versus Denitrifying Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Han, R.; Qin, L.; Brown, S. T.; Christensen, J. N.; Beller, H. R.

    2012-01-27

    We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Finally, despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (ε was ~2‰ aerobically and ~0.4‰ under denitrifying conditions).

  6. Identification of a denitrifying bacterium and verification of its anaerobic ammonium oxidation ability

    Institute of Scientific and Technical Information of China (English)

    HU; Baolan; ZHENG; Ping; LI; Jinye; XU; Xiangyang; JIN; Rencun

    2006-01-01

    A strain D3 of denitrifying bacterium was isolated from an anammox reactor, and identified as Pseudomonas mendocina based on the morphological and physiological assay, Vitek test,Biolog test, (G+C) mol% content, and 16S rDNA phylogenetic analysis. As a typical denitrifying bactration of 88.5 mg N/L. The optimal pH and growth temperature were 7.84 and 34.9℃, respectively.Strain D3 was able to oxidize ammonia under anaerobic condition. The maximum nitrate and ammoof ammonia to nitrate was 1:1.91. Electron microscopic observation revealed peculiar cell inclusions in strain D3. Because of its relation to anammox activity, strain D3 was presumed to be anammoxosome.The present investigation proved that denitrifying bacteria have the anammox ability, and the results have engorged the range of anammox populations.

  7. Factors affecting biological denitrifying dephosphatation in anaerobic/anoxic/aerobic sequencing batch reactor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study was conducted to verify and discuss the denitrifying dephosphatation under different levels of nitrate concentration and retention time of anoxic/aerobic process in a Sequencing Batch Reactor ( SBR ).The results of tests demonstrated that there were two kinds of phosphorus-accumulating organisms (PAOs) in the biological excess phosphorus removal (BEPR) system. One was non-DNPAOs that could only use oxygen as terminal electron acceptors, the other was denitrifying PAOs (DNPAOs) that could use both nitrate and oxygen as terminal electron acceptors. Phosphorus uptake efficiency could be attained under anoxic period ranging from 28.7%-96.7% in an anacrobic/anoxic/aerobic system. Experimental results showed that nitrate concentration and retention time of anoxic/aerobic process were the key factors affecting the course of denitrifying dephosphatation.

  8. Nitrification and denitrifying phosphorus removal in an upright continuous flow reactor.

    Science.gov (United States)

    Reza, Maryam; Alvarez Cuenca, Manuel

    2016-01-01

    Simultaneous nitrification and denitrifying phosphorus removal was achieved in a single-sludge continuous flow bioreactor. The upright bioreactor was aligned with a biomass fermenter (BF) and operated continuously for over 350 days. This study revealed that unknown bacteria of the Saprospiraceae class may have been responsible for the successful nutrient removal in this bioreactor. The successive anoxic-aerobic stages of the bioreactor with upright alignment along with a 60 L BF created a unique ecosystem for the growth of nitrifier, denitrifiers, phosphorus accumulating organisms and denitrifying phosphorus accumulating organisms. Furthermore, total nitrogen to chemical oxygen demand (COD) ratio and total phosphorus to COD ratio of 0.6 and 0.034, respectively, confirmed the comparative advantages of this advanced nutrient removal process relative to both sequencing batch reactors and activated sludge processes. The process yielded 95% nitrogen removal and over 90% phosphorus removal efficiencies. PMID:27148710

  9. Accelerated methanogenesis from effluents of hydrogen-producing stage in anaerobic digestion by mixed cultures enriched with acetate and nano-sized magnetite particles.

    Science.gov (United States)

    Yang, Zhiman; Xu, Xiaohui; Guo, Rongbo; Fan, Xiaolei; Zhao, Xiaoxian

    2015-08-01

    Potential for paddy soil enrichments obtained in the presence of nano-sized magnetite particles (named as PSEM) to promote methane production from effluents of hydrogen-producing stage in two-stage anaerobic digestion was investigated. The results showed that the addition of magnetite significantly accelerated methane production from acetate in a dose-independent manner. The results from high-throughput sequencing analysis revealed that Rhodocyclaceae-related species were selectively enriched, which were likely the key players for conversion of acetate to methane in PSEM. Compared to the paddy soil enrichments obtained in the absence of magnetite (named as PSEC), the maximum methane production rate in PSEM was significantly higher (1.5-5.5times higher for the artificial medium and 0.2-1.7times higher for the effluents). The accelerated methane production from the effluents indicated remarkably application potential of PSEM for improving performance of anaerobic digestion. PMID:25935393

  10. Porównawcze badania nad występowaniem bakterii w hydroponicznych uprawach sałaty (Lactuca sativa L. z azotanowaą i amonową formą azotu w pożywce [Comparative studies on the occurrence of bacteria in hydroponic cultures of lettuce (Lactuca sativa L. enriched with nitrate or ammonia forms of nitrogen in the nutrient medium

    Directory of Open Access Journals (Sweden)

    Z. Kobierzyńska-Gołąb

    2015-06-01

    Full Text Available The experiment demonstrated the greatest number of bacteria on the surface of roots immersed in nutrient solution, next on the epidermis of the parts of roots remaining in the air space above the nutrient solution and on the roots growing in the seed-bed; a smaller number in the seed-bed itself and the smallest number in the nutrient solution. The population of bacteria consisted of up to 90% short rod of bacilli. The total number of bacteria in hydroponic culture with ammonium was higher than in that with nitrate. As a rule the bacteria belonging to the separate physiological groups, participating in nitrogen metabolism (ammonifying, proteolytic, proteinizing, denitrifying and oligonitrophilic bacteria appeared to be more numerus in the culture with ammonium than in that with nitrate. The growth of plants in hydroponic culture with ammonium was weaker than in that with nitrate.

  11. Effect of pyrene on denitrification activity and abundance and composition of denitrifying community in an agricultural soil

    International Nuclear Information System (INIS)

    Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene to a series of concentrations (0-500 mg kg-1) followed by dose-response and dynamic incubation experiments. Results showed a positive correlation between potential denitrification activity and copy numbers of denitrifying functional genes (nirK, nirS and nosZ), and were both negatively correlated with pyrene concentrations. Based on the comparison of EC50 values, denitrifiers harboring nirK, nirS or nosZ gene were more sensitive than denitrification activity, and denitrifiers harboring nirS gene were more sensitive than that harboring nirK or nosZ genes. Seven days after spiking with EC50 concentration of pyrene, denitrifiers diversity decreased and community composition changed in comparison with the control. Phylogenetic analyses of three genes showed that the addition of pyrene increased the proportion of Bradyrhizobiaceae, Rhodospirillales, Burkholderiales and Pseudomonadales. Some species belonging to these groups were reported to be able to degrade PAHs. - Highlights: → Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene. → PDA was positively correlated with the abundance of denitrifiers harboring nirK, nirS or nosZ gene. → Both PDA and the abundance of denitrifiers were negatively correlated with pyrene concentrations. → Denitrifiers harboring nirk, nirS or nosZ gene are more sensitive to pyrene than PDA in soils. - Denitrifiers harboring nirK, nirS or nosZ gene are more sensitive to pyrene contamination than potential denitrification activity in soils.

  12. Pyruvic Oxime Nitrification and Copper and Nickel Resistance by a Cupriavidus pauculus, an Active Heterotrophic Nitrifier-Denitrifier

    Directory of Open Access Journals (Sweden)

    Miguel Ramirez

    2014-01-01

    Full Text Available Heterotrophic nitrifiers synthesize nitrogenous gasses when nitrifying ammonium ion. A Cupriavidus pauculus, previously thought an Alcaligenes sp. and noted as an active heterotrophic nitrifier-denitrifier, was examined for its ability to produce nitrogen gas (N2 and nitrous oxide (N2O while heterotrophically nitrifying the organic substrate pyruvic oxime [CH3–C(NOH–COOH]. Neither N2 nor N2O were produced. Nucleotide and phylogenetic analyses indicated that the organism is a member of a genus (Cupriavidus known for its resistance to metals and its metabolism of xenobiotics. The microbe (a Cupriavidus pauculus designated as C. pauculus strain UM1 was examined for its ability to perform heterotrophic nitrification in the presence of Cu2+ and Ni2+ and to metabolize the xenobiotic phenol. The bacterium heterotrophically nitrified well when either 1 mM Cu2+ or 0.5 mM Ni2+ was present in either enriched or minimal medium. The organism also used phenol as a sole carbon source in either the presence or absence of 1 mM Cu2+ or 0.5 mM Ni2+. The ability of this isolate to perform a number of different metabolisms, its noteworthy resistance to copper and nickel, and its potential use as a bioremediation agent are discussed.

  13. Environmental evaluation of coexistence of denitrifying anaerobic methane-oxidizing archaea and bacteria in a paddy field.

    Science.gov (United States)

    Ding, Jing; Fu, Liang; Ding, Zhao-Wei; Lu, Yong-Ze; Cheng, Shuk H; Zeng, Raymond J

    2016-01-01

    The nitrate-dependent denitrifying anaerobic methane oxidation (DAMO) process, which is metabolized together by anaerobic methanotrophic archaea and NC10 phylum bacteria, is expected to be important for the global carbon and nitrogen cycles. However, there are little studies about the existence of this process and the functional microbes in environments. Therefore, the coexistence of DAMO archaea and bacteria in a paddy field was evaluated in this study. Next-generation sequencing showed that the two orders, Methanosarcinales and Nitrospirales, to which DAMO archaea and DAMO bacteria belong, were detected in the four soil samples. Then the in vitro experiments demonstrated both of nitrite- and nitrate-dependent DAMO activities, which confirmed the coexistence of DAMO archaea and DAMO bacteria. It was the first report about the coexistence of DAMO archaea and bacteria in a paddy field. Furthermore, anammox bacteria were detected in two of the four samples. The in vitro experiments did not show anammox activity in the initial period but showed low anammox activity after 20 days' enrichment. These results implicated that anammox bacteria may coexist with DAMO microorganisms in this field, but at a very low percentage. PMID:26394860

  14. Multiplex Real-Time PCR Assays for Screening of Shiga Toxin 1 and 2 Genes, Including All Known Subtypes, and Escherichia coli O26-, O111-, and O157-Specific Genes in Beef and Sprout Enrichment Cultures.

    Science.gov (United States)

    Harada, Tetsuya; Iguchi, Atsushi; Iyoda, Sunao; Seto, Kazuko; Taguchi, Masumi; Kumeda, Yuko

    2015-10-01

    Shiga toxin family members have recently been classified using a new nomenclature into three Stx1 subtypes (Stx1a, Stx1c, and Stx1d) and seven Stx2 subtypes (Stx2a, Stx2b, Stx2c, Stx2d, Stx2e, Stx2f, and Stx2g). To develop screening methods for Stx genes, including all of these subtype genes, and Escherichia coli O26-, O111-, and O157-specific genes in laboratory investigations of Shiga toxin-producing E. coli (STEC) foodborne cases, we developed multiplex real-time PCR assays and evaluated their specificity and quantitative accuracy using STEC and non-STEC isolates, recombinant plasmids, and food enrichment cultures and by performing STEC spiking experiments with beef and sprout enrichment cultures. In addition, we evaluated the relationship between the recovery rates of the target strains by direct plating and immunomagnetic separation and the cycle threshold (CT) values of the real-time PCR assays for the Stx subtypes and STEC O26, O111, and O157 serogroups. All three stx1- and seven stx2-subtype genes were detected by real-time PCR with high sensitivity and specificity, and the quantitative accuracy of this assay was confirmed using control plasmids and STEC spiking experiments. The results of the STEC spiking experiments suggest that it is not routinely possible to isolate STEC from enrichment cultures with real-time PCR CT values greater than 30 by direct plating on MacConkey agar, although highly selective media and immunomagnetic beads were able to isolate the inoculated strains from the enrichment cultures. These data suggest that CT values obtained from the highly quantitative real-time PCR assays developed in this study provide useful information to develop effective isolation strategies for STEC from food samples. The real-time PCR assays developed here are expected to aid in investigations of infections or outbreaks caused by STEC harboring any of the stx-subtype genes in the new Stx nomenclature, as well as STEC O26, O111, and O157.

  15. Nitrogen Removal from Micro-Polluted Reservoir Water by Indigenous Aerobic Denitrifiers

    Directory of Open Access Journals (Sweden)

    Ting-Lin Huang

    2015-04-01

    Full Text Available Treatment of micro-polluted source water is receiving increasing attention because of environmental awareness on a global level. We isolated and identified aerobic denitrifying bacteria Zoogloea sp. N299, Acinetobacter sp. G107, and Acinetobacter sp. 81Y and used these to remediate samples of their native source water. We first domesticated the isolated strains in the source water, and the 48-h nitrate removal rates of strains N299, G107, and 81Y reached 33.69%, 28.28%, and 22.86%, respectively, with no nitrite accumulation. We then conducted a source-water remediation experiment and cultured the domesticated strains (each at a dry cell weight concentration of 0.4 ppm together in a sample of source water at 20–26 °C and a dissolved oxygen concentration of 3–7 mg/L for 60 days. The nitrate concentration of the system decreased from 1.57 ± 0.02 to 0.42 ± 0.01 mg/L and that of a control system decreased from 1.63 ± 0.02 to 1.30 ± 0.01 mg/L, each with no nitrite accumulation. Total nitrogen of the bacterial system changed from 2.31 ± 0.12 to 1.09 ± 0.01 mg/L, while that of the control system changed from 2.51 ± 0.13 to 1.72 ± 0.06 mg/L. The densities of aerobic denitrification bacteria in the experimental and control systems ranged from 2.8 × 104 to 2 × 107 cfu/mL and from 7.75 × 103 to 5.5 × 105 cfu/mL, respectively. The permanganate index in the experimental and control systems decreased from 5.94 ± 0.12 to 3.10 ± 0.08 mg/L and from 6.02 ± 0.13 to 3.61 ± 0.11 mg/L, respectively, over the course of the experiment. Next, we supplemented samples of the experimental and control systems with additional bacteria or additional source water and cultivated the systems for another 35 days. The additional bacteria did little to improve the water quality. The additional source water provided supplemental carbon and brought the nitrate removal rate in the experimental system to 16.97%, while that in the control system reached only 3

  16. Effects of earthworms and substrate on diversity and abundance of denitrifying genes (nirS and nirK) and denitrifying rate during rural domestic wastewater treatment.

    Science.gov (United States)

    Wang, Longmian; Zhang, Yimin; Luo, Xingzhang; Zhang, Jibiao; Zheng, Zheng

    2016-07-01

    This study investigated the performance of an ecological filter (EF) and vermifiltration (VF) system, the effects of substrate and earthworms on the diversity and abundance of denitrifying genes coding for nitrite (nirS and nirK) reductases and on denitrifying rate, and the factors influencing denitrification. The majority of organic matter, ammonia nitrogen and total nitrogen from sewage was removed by the soil layer in both reactors, and their total removal efficiencies increased in VF compared with those in EF. Additionally, substrate in the reactors significantly influenced the Shannon diversity index and abundance of nirS and nirK, as well as the denitrifying rate. However, the earthworms only significantly influenced nirS diversity. Furthermore, evaluation of the factors controlling denitrification implied that increasing NH3-N availability, diversity and abundance of nirS and nirK or decreasing available NO3-N might be responsible for the enhanced denitrification activity obtained using VF for rural domestic wastewater treatment. PMID:27099942

  17. Post cold-storage conditioning time affects soil denitrifying enzyme activity

    OpenAIRE

    Chirinda, Ngonidzashe; J. E. Olesen; Porter, J R

    2011-01-01

    Soil denitrifying enzyme activity (DEA) is often assessed after cold storage.Previous studies using the short-term acetylene inhibition method have not considered conditioning time (post-cold storage warming-up time prior to soil analysis) as a factor influencing results. We observed fluctuations in DEA following cold storage, suggesting a need to consider conditioning time when planning and interpreting results.

  18. [Performance Recoverability of Denitrifying Granular Sludge Under the Stressing Effect of Nanoscale Zero-valent Iron].

    Science.gov (United States)

    Wang, Fan-fan; Qian, Fei-yue; Shen, Yao-liang; Wang, Jian-fang; Zhang, Yue-ru; Liu, Guo-xun

    2016-04-15

    To explore the potential stressing effect of nanoscale zero-valent iron (nZVI) on denitrifying granular sludge (DGS), the evolution of DGS denitrifying performance under different C/N ratios was investigated in this study, by carrying out batch tests of eight successive periods with the nZVI shock-loading. The results showed that the specific denitrification rate of µ value decreased when the nZVI dosage was higher than 5 mg · L⁻¹. Meanwhile, a positive correlation between the inhibition ratio (IR) of µ value and substrate C/N ratios or nZVI dosage was observed. When the nZVI dosage reached 100 mg · L⁻¹, both extracellular protein and polysaccharides concentrations decreased obviously. It would be beneficial to promote the recovery of DGS denitrifying activity and reduce the COD demanding to remove unit mass of nitrate, by increasing external carbon source with C/N ratios of higher than 4. On the basis of Freundlich and Langmuir adsorption isotherms, when higher C/N ratio was provided, stronger bioadsorption of nZVI would be achieved. During the recovery period, a significant improvement of DCS denitrifying performance under the high C/N ratio was expected, due to the continuous washout of total iron in sludge phase (Qe), while the µ value would reach or approach the one of the control group when Qe was lower than 0.4 mg · g⁻¹. PMID:27548972

  19. Optimization of denitrifying bioreactor performance with agricultural residue-based filter media

    Science.gov (United States)

    Denitrification bioreactors are a promising technology for mitigation of nitrate-nitrogen (NO3-N) losses in subsurface drainage water. Bioreactors are constructed with carbon substrates, typically wood chips, to provide a substrate for denitrifying microorganisms. Columns were packed with wood chips...

  20. Influence of carbon source and temperature on the denitrifying phosphorus removal process

    Institute of Scientific and Technical Information of China (English)

    WANG Yayi; WANG Shuying; PENG Yongzhen; Zhu Guibing; LING Yunfang

    2007-01-01

    To supply the valuable operating parameters for the popular usage of the new denitrifying phosphors removal process,it is essential to study the dominant biochemical reactions and the characteristics of denitriflying phosphorus removing bacteria(DPB).Thus,parallel batch experiments using DPB sludge were carried out to assess the effect of substrates(sewage,HAc,and endogenous carbon source)on denitriflying dephosphorus removal efficiency in this study.The results showed that the initial specific phosphorus release rate increased with the high concentration of the short-chain volatile fatty acids ratio in the influent,and sufficient phosphorus was released by DPB.This improved the subsequent denitrification and phosphorus uptake efficiency.The specific endogenous denitrification mainly relies on the internal carbon source(PHB)stored by poly-P bacteria.Denitrifying phosphorus removing bacteria were very hungry when the internal PHB was consumed.Consequently,the specific endogenous denitrification rate was low and the phosphorus uptake did not happen.On the other hand,in the experiment,the denitrifying phosphorus removal performance under two temperature conditions(8-10℃ and 25-26℃)was also investigated and analyzed.It was found that the lower temperature decreased the specific phosphorus release and uptake rate,but did not inhibit the denitrifying phosphorus removal completely.Therefore,the negative influence of the low temperature on the overall phosphorus removal was not significant.

  1. Effect of carbon source and nitrate concentration on denitrifying phosphorus removal by DPB sludge

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-yi; PENG Yong-zhen; Wang Shu-ying; PAN Mian-li

    2004-01-01

    Effect of added carbon source and nitrate concentration on the denitrifying phosphorus removal by DPB sludge was systematically studied using batch experiments, at the same time the variation of ORP was investigated.Results showed that the denitrifying and phosphorus uptake rate in anoxic phase increased with the high initial anaerobic carbon source addition. However once the initial COD concentration reached a certain level, which was in excess to the PHB saturation of poly-P bacteria, residual COD carried over to anoxic phase inhibited the subsequent denitrifying phosphorus uptake. Simultaneously, phosphate uptake continued until all nitrate was removed, following a slow endogenous release of phosphate. High nitrate concentration in anoxic phase increased the initial denitrifying phosphorus rate. Once the nitrate was exhausted, phosphate uptake changed to release. Moreover, the time of this turning point occurred later with the higher nitrate addition. On the other hand, through on-line monitoring the variation of the ORP with different initial COD concentration , it was found ORP could be used as a control parameter for phosphorus release, but it is impossible to utilize ORP for controlling the denitrificaion and anoxic phosphorus uptake operations.

  2. Optimizing hydraulic retention times in denitrifying woodchip bioreactors treating recirculating aquaculture system wastewater

    Science.gov (United States)

    The performance of wood-based denitrifying bioreactors to treat high-nitrate wastewaters from aquaculture systems has not previously been demonstrated. Four pilot-scale woodchip bioreactors (approximately 1:10 scale) were constructed and operated for 268 d to determine the optimal range of design hy...

  3. Identification of active denitrifiers in full-scale nutrient removal wastewater treatment systems

    DEFF Research Database (Denmark)

    McIlroy, Simon Jon; Szyszka, Anna; Starnawski, Piotr Marian;

    2016-01-01

    in combination with microautoradiography (MAR)-fluorescence in situ hybridisation (FISH) to identify the active denitrifiers in a full-scale WWTP with biological N and P removal. Recognising that a range of carbon sources likely drive denitrification, a fully 13 C-labelled complex substrate was used for SIP...

  4. Post-cold-storage conditioning time affects soil denitrifying enzyme activity

    DEFF Research Database (Denmark)

    Chirinda, Ngonidzashe; Olesen, Jørgen Eivind; Porter, John Roy

    2011-01-01

    Soil denitrifying enzyme activity (DEA) is often assessed after cold storage. Previous studies using the short-term acetylene inhibition method have not considered conditioning time (post-cold-storage warm-up time prior to soil analysis) as a factor influencing results. We observed fluctuations...

  5. Nitrous oxide reductase genes (nosZ) of denitrifying populations in soil and the earthworm gut are phylogenetically similar

    DEFF Research Database (Denmark)

    Horn, Marcus A.; Drake, Harold L.; Schramm, Andreas

    2006-01-01

    analysis of nosZ, the gene for the terminal enzyme in denitrification, N2O reductase. A total of 182 and 180 nosZ sequences were retrieved from gut and soil, respectively; coverage of gene libraries was 79 to 100%. Many of the nosZ sequences were heretofore unknown, clustered with known soil......Earthworms emit nitrous oxide (N2O) and dinitrogen (N2). It has been hypothesized that the in situ conditions of the earthworm gut activates ingested soil denitrifiers during gut passage and leads to these in vivo emissions (M. A. Horn, A. Schramm, and H. L. Drake, Appl. Environ. Microbiol. 69......:1662-1669, 2003). This hypothesis implies that the denitrifiers in the earthworm gut are not endemic to the gut but rather are regular members of the soil denitrifier population. To test this hypothesis, the denitrifier populations of gut and soil from three different sites were comparatively assessed by sequence...

  6. Simultaneous removal of sulfide, nitrate and acetate under denitrifying sulfide removal condition: Modeling and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xijun; Chen, Chuan; Wang, Aijie; Guo, Wanqian; Zhou, Xu [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Lee, Duu-Jong, E-mail: djlee@ntu.edu.tw [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Ren, Nanqi, E-mail: rnq@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Chang, Jo-Shu [Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan (China)

    2014-01-15

    Graphical abstract: Model evaluation applied to case study 1: (A-G) S{sup 2−}, NO{sub 3}{sup −}-N, NO{sub 2}{sup −}-N, and Ac{sup −}-C profiles under initial sulfide concentrations of 156.2 (A), 539 (B), 964 (C), 1490 (D), 342.7 (E), 718 (F), and 1140.7 (G) mg L{sup −1}. The solid line represents simulated result and scatter represents experimental result. -- Highlights: • This work developed a mathematical model for DSR process. • Kinetics of sulfur–nitrogen–carbon and interactions between denitrifiers were studied. • Kinetic parameters of the model were estimated via data fitting. • The model described kinetic behaviors of DSR processes over wide parametric range. -- Abstract: Simultaneous removal of sulfide (S{sup 2−}), nitrate (NO{sub 3}{sup −}) and acetate (Ac{sup −}) under denitrifying sulfide removal process (DSR) is a novel biological wastewater treatment process. This work developed a mathematical model to describe the kinetic behavior of sulfur–nitrogen–carbon and interactions between autotrophic denitrifiers and heterotrophic denitrifiers. The kinetic parameters of the model were estimated via data fitting considering the effects of initial S{sup 2−} concentration, S{sup 2−}/NO{sub 3}{sup −}-N ratio and Ac{sup −}-C/NO{sub 3}{sup −}-N ratio. Simulation supported that the heterotrophic denitratation step (NO{sub 3}{sup −} reduction to NO{sub 2}{sup −}) was inhibited by S{sup 2−} compared with the denitritation step (NO{sub 2}{sup −} reduction to N{sub 2}). Also, the S{sup 2−} oxidation by autotrophic denitrifiers was shown two times lower in rate with NO{sub 2}{sup −} as electron acceptor than that with NO{sub 3}{sup −} as electron acceptor. NO{sub 3}{sup −} reduction by autotrophic denitrifiers occurs 3–10 times slower when S{sup 0} participates as final electron donor compared to the S{sup 2−}-driven pathway. Model simulation on continuous-flow DSR reactor suggested that the adjustment of

  7. Relationship between Nitrite Reduction and Active Phosphate Uptake in the Phosphate-Accumulating Denitrifier Pseudomonas sp. Strain JR 12

    OpenAIRE

    Barak, Yoram; van Rijn, Jaap

    2000-01-01

    Phosphate uptake by the phosphate-accumulating denitrifier Pseudomonas sp. JR12 was examined with different combinations of electron and carbon donors and electron acceptors. Phosphate uptake in acetate-supplemented cells took place with either oxygen or nitrate but did not take place when nitrite served as the final electron acceptor. Furthermore, nitrite reduction rates by this denitrifier were shown to be significantly reduced in the presence of phosphate. Phosphate uptake assays in the pr...

  8. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds

    OpenAIRE

    Warneke, Sören; Schipper, Louis A.; Matiasek, Michael G.; Scow, Kate M.; Cameron, Stewart; Bruesewitz, Denise A.; McDonald, Ian R.

    2011-01-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate ( NO3−) from point source discharges into non-reactive dinitrogen (N2) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO3− removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m3) filled with either maize cobs, w...

  9. Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems

    Directory of Open Access Journals (Sweden)

    Vinayak Laxman Pachapur

    2016-01-01

    Full Text Available Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H2 production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG as substrate. Results for heat treatment (100 °C for 15 min showed the highest H2 production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H2 consuming bacteria and produced twice as much as H2 as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L, percentage of inoculum size (InS (1.23% to 24% v/v along with initial pH (2.98 to 8.02 was tested using central composite design (CCD with H2 production as response parameter. The maximum H2 production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011 contribution to H2 production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H2 production.

  10. Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems.

    Science.gov (United States)

    Pachapur, Vinayak Laxman; Kutty, Prianka; Brar, Satinder Kaur; Ramirez, Antonio Avalos

    2016-01-13

    Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H₂) production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG) as substrate. Results for heat treatment (100 °C for 15 min) showed the highest H₂ production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H₂ consuming bacteria and produced twice as much as H₂ as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L), percentage of inoculum size (InS) (1.23% to 24% v/v) along with initial pH (2.98 to 8.02) was tested using central composite design (CCD) with H₂ production as response parameter. The maximum H₂ production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011) contribution to H₂ production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H₂ production.

  11. Effect of a Semi-Purified Oligosaccharide-Enriched Fraction from Caprine Milk on Barrier Integrity and Mucin Production of Co-Culture Models of the Small and Large Intestinal Epithelium

    Directory of Open Access Journals (Sweden)

    Alicia M. Barnett

    2016-05-01

    Full Text Available Caprine milk contains the highest amount of oligosaccharides among domestic animals, which are structurally similar to human milk oligosaccharides (HMOs. This suggests caprine milk oligosaccharides may offer similar protective and developmental effects to that of HMOs. However, to date, studies using oligosaccharides from caprine milk have been limited. Thus, this study aimed to examine the impact of a caprine milk oligosaccharide-enriched fraction (CMOF on barrier function of epithelial cell co-cultures of absorptive enterocytes (Caco-2 cells and mucus-secreting goblet cells (HT29-MTX cells, that more closely simulate the cell proportions found in the small (90:10 and large intestine (75:25. Treatment of epithelial co-cultures with 0.4, 1.0, 2.0 and 4.0 mg/mL of CMOF was shown to have no effect on metabolic activity but did enhance cell epithelial barrier integrity as measured by trans-epithelial electrical resistance (TEER, in a dose-dependent manner. The CMOF at the maximum concentration tested (4.0 mg/mL enhanced TEER, mucin gene expression and mucin protein abundance of epithelial co-cultures, all of which are essential components of intestinal barrier function.

  12. cultural

    Directory of Open Access Journals (Sweden)

    Irene Kreutz

    2006-01-01

    Full Text Available Es un estudio cualitativo que adoptó como referencial teorico-motodológico la antropología y la etnografía. Presenta las experiencias vivenciadas por mujeres de una comunidad en el proceso salud-enfermedad, con el objetivo de comprender los determinantes sócio-culturales e históricos de las prácticas de prevención y tratamiento adoptados por el grupo cultural por medio de la entrevista semi-estructurada. Los temas que emergieron fueron: la relación entre la alimentación y lo proceso salud-enfermedad, las relaciones con el sistema de salud oficial y el proceso salud-enfermedad y lo sobrenatural. Los dados revelaron que los moradores de la comunidad investigada tienen un modo particular de explicar sus procedimientos terapéuticos. Consideramos que es papel de los profesionales de la salud en sus prácticas, la adopción de abordajes o enfoques que consideren al individuo en su dimensión sócio-cultural e histórica, considerando la enorme diversidad cultural en nuestro país.

  13. Anaerobic oxidation of p-cresol mediated by a partially purified methylhydroxylase from a denitrifying bacterium.

    OpenAIRE

    Bossert, I D; Whited, G; Gibson, D T; Young, L. Y.

    1989-01-01

    Anoxic cell extracts of a denitrifying bacterial isolate (PC-07) were shown to oxidize p-cresol to p-hydroxybenzoate. Oxidation of the substrate was independent of molecular oxygen and required nitrate as the natural terminal electron acceptor. Two enzyme activities were implicated in the pathway utilized by PC-07. A p-cresol methylhydroxylase mediated the oxidation of p-cresol to p-hydroxybenzaldehyde, which was further oxidized to p-hydroxybenzoate by an NAD+-dependent dehydrogenase. The PC...

  14. Granulation of susceptible sludge under carbon deficient conditions: A case of denitrifying sulfur conversion-associated EBPR process.

    Science.gov (United States)

    Guo, Gang; Wu, Di; Hao, Tianwei; Mackey, Hamish Robert; Wei, Li; Lu, Hui; Chen, Guanghao

    2016-10-15

    Sludge granulation has been recognized as a promising biotechnology in wastewater treatment. Whereas the granulation of susceptible sludge in particular with a very low organic loading rate (OLR) (≤0.6 kg COD/m(3)/day or ≤ 120 mg COD/g VSS/day) is a difficult task that has not been achieved in activated sludge systems yet. This study was aimed at exploring an effective strategy for sludge granulation in the recently developed Denitrifying Sulfur conversion-associated Enhanced Biological Phosphorus Removal (DS-EBPR) process using a sequencing batch pump-lift reactor. Four strategies were studied by manipulating the factors of organic loading rate (OLR), superficial upflow velocity and sludge settling time individually or collectively. Increasing both the OLR and the superficial upflow velocity effectively promoted granule formation but at the same time led to unstable and even deteriorated reactor performance. The development of granules proceeded via several stages: formation, dispersion, reformation and stabilization. Gradually increasing the superficial upflow velocity from 5.1 to 6.8 m/h and keeping the OLR at 112.4 mg COD/g VSS/day proved to be most effective strategy for accelerating granulation while simultaneously achieving stable reactor performance. Under these conditions, the granules became stable with a diameter of 375-400 μm and displayed excellent settleability. The two major microbial groups, sulfate-reducing bacteria and sulfide-oxidizing bacteria, in the microbial community of the DS-EBPR granular sludge were enriched to 17.7% and 15.8% respectively. The newly developed DS-EBPR granular system was able to achieve an almost threefold improvement in phosphorus removal efficiency and 25% reduction in the operating cycle time compared with a flocculent DS-EBPR system. PMID:27498252

  15. A comparative study of the bacterial community in denitrifying and traditional enhanced biological phosphorus removal processes.

    Science.gov (United States)

    Lv, Xiao-Mei; Shao, Ming-Fei; Li, Chao-Lin; Li, Ji; Gao, Xin-Lei; Sun, Fei-Yun

    2014-09-17

    Denitrifying phosphorus removal is an attractive wastewater treatment process due to its reduced carbon source demand and sludge minimization potential. Two lab-scale sequencing batch reactors (SBRs) were operated in alternating anaerobic-anoxic (A-A) or anaerobic-oxic (A-O) conditions to achieve denitrifying enhanced biological phosphate removal (EBPR) and traditional EBPR. No significant differences were observed in phosphorus removal efficiencies between A-A SBR and A-O SBR, with phosphorus removal rates being 87.9% and 89.0% respectively. The community structures in denitrifying and traditional EBPR processes were evaluated by high-throughput sequencing of the PCR-amplified partial 16S rRNA genes from each sludge. The results obtained showed that the bacterial community was more diverse in A-O sludge than in A-A sludge. Taxonomy and β-diversity analyses indicated that a significant shift occurred in the dominant microbial community in A-A sludge compared with the seed sludge during the whole acclimation phase, while a slight fluctuation was observed in the abundance of the major taxonomies in A-O sludge. One Dechloromonas-related OTU outside the 4 known Candidatus "Accumulibacter" clades was detected as the main OTU in A-A sludge at the stationary operation, while Candidatus "Accumulibacter" dominated in A-O sludge. PMID:24964811

  16. Disentangling the rhizosphere effect on nitrate reducers and denitrifiers: insight into the role of root exudates.

    Science.gov (United States)

    Henry, S; Texier, S; Hallet, S; Bru, D; Dambreville, C; Chèneby, D; Bizouard, F; Germon, J C; Philippot, L

    2008-11-01

    To determine to which extent root-derived carbon contributes to the effects of plants on nitrate reducers and denitrifiers, four solutions containing different proportions of sugar, organic acids and amino acids mimicking maize root exudates were added daily to soil microcosms at a concentration of 150 microg C g(-1) of soil. Water-amended soils were used as controls. After 1 month, the size and structure of the nitrate reducer and denitrifier communities were analysed using the narG and napA, and the nirK, nirS and nosZ genes as molecular markers respectively. Addition of artificial root exudates (ARE) did not strongly affect the structure or the density of nitrate reducer and denitrifier communities whereas potential nitrate reductase and denitrification activities were stimulated by the addition of root exudates. An effect of ARE composition was also observed on N(2)O production with an N(2)O:(N(2)O + N(2)) ratio of 0.3 in microcosms amended with ARE containing 80% of sugar and of 1 in microcosms amended with ARE containing 40% of sugar. Our study indicated that ARE stimulated nitrate reduction or denitrification activity with increases in the range of those observed with the whole plant. Furthermore, we demonstrated that the composition of the ARE affected the nature of the end-product of denitrification and could thus have a putative impact on greenhouse gas emissions.

  17. Formation of diclofenac and sulfamethoxazole reversible transformation products in aquifer material under denitrifying conditions: batch experiments.

    Science.gov (United States)

    Barbieri, Manuela; Carrera, Jesús; Ayora, Carlos; Sanchez-Vila, Xavier; Licha, Tobias; Nödler, Karsten; Osorio, Victoria; Pérez, Sandra; Köck-Schulmeyer, Marianne; López de Alda, Miren; Barceló, Damià

    2012-06-01

    Soil-aquifer processes have proven to work as a natural treatment for the attenuation of numerous contaminants during artificial recharge of groundwater. Nowadays, significant scientific effort is being devoted to understanding the fate of pharmaceuticals in subsurface environments, and to verify if such semipersistent organic micropollutants could also be efficiently removed from water. In this context we carried out a series of batch experiments involving aquifer material, selected drugs (initial concentration of 1 μg/L and 1 mg/L), and denitrifying conditions. Diclofenac and sulfamethoxazole exhibited an unreported and peculiar behavior. Their concentrations consistently dropped in the middle of the tests but recovered toward the end, which suggest a complex effect of denitrifying conditions on aromatic amines. The transformation products Nitro-Diclofenac and 4-Nitro-Sulfamethoxazole were detected in the biotic experiments, while nitrite was present in the water. Their concentrations developed almost opposite to those of their respective parent compounds. We conjecture that this temporal and reversible effect of denitrifying conditions on the studied aromatic amines could have significant environmental implications, and could explain at least partially the wide range of removals in subsurface environments reported in literature for DCF and SMX, as well as some apparent discrepancies on SMX behavior. PMID:22534360

  18. [Analysis on Diversity of Denitrifying Microorganisms in Sequential Batch Bioreactor Landfill].

    Science.gov (United States)

    Li, Wei-Hua; Sun, Ying-Jie; Liu, Zi-Liang; Ma, Qiang; Yang, Qiang

    2016-01-15

    A denitrification functional microorganism gene clone library (amoA, nosZ) and the PCR-RFLP technology was constructed to investigate the microbial diversity of denitrifying microorganisms in the late period of stabilization of sequential batch bioreactor landfill. The results indicated that: the bacterial diversity of ammonia oxidizing bacteria in the aged refuse reactor was very high, and most of them were unknown groups, also, all bacteria were unculturable or had not been isolated. The phylogenetic analysis suggested that the dominant ammonia oxidizing bacteria were presumably Nitrosomonas of 6-Proteobacteria. The diversity of denitrifying bacteria in fresh refuse reactor was abundant, which mainly included Thauera and Thiobacillus of 6-Proteobacteria. As Thauera sp. has the denitrification characteristics under the condition of aerobic while Thiobacillus denitrificans has the autotrophic denitrification characteristics, it was speculated that aerobic denitrification and autotrophic denitrification might be the main pathways for nitrogen removal in the fresh refuse reactor at the late period of stabilization. Additionally, another group in the gene clone library of denitrifying bacteria may be classified as Bradyrhizobiaceae of alpha-Proteobacteria. PMID:27078976

  19. [Analysis on Diversity of Denitrifying Microorganisms in Sequential Batch Bioreactor Landfill].

    Science.gov (United States)

    Li, Wei-Hua; Sun, Ying-Jie; Liu, Zi-Liang; Ma, Qiang; Yang, Qiang

    2016-01-15

    A denitrification functional microorganism gene clone library (amoA, nosZ) and the PCR-RFLP technology was constructed to investigate the microbial diversity of denitrifying microorganisms in the late period of stabilization of sequential batch bioreactor landfill. The results indicated that: the bacterial diversity of ammonia oxidizing bacteria in the aged refuse reactor was very high, and most of them were unknown groups, also, all bacteria were unculturable or had not been isolated. The phylogenetic analysis suggested that the dominant ammonia oxidizing bacteria were presumably Nitrosomonas of 6-Proteobacteria. The diversity of denitrifying bacteria in fresh refuse reactor was abundant, which mainly included Thauera and Thiobacillus of 6-Proteobacteria. As Thauera sp. has the denitrification characteristics under the condition of aerobic while Thiobacillus denitrificans has the autotrophic denitrification characteristics, it was speculated that aerobic denitrification and autotrophic denitrification might be the main pathways for nitrogen removal in the fresh refuse reactor at the late period of stabilization. Additionally, another group in the gene clone library of denitrifying bacteria may be classified as Bradyrhizobiaceae of alpha-Proteobacteria.

  20. Denitrifying phosphorus removal from municipal wastewater and dynamics of "Candidatus Accumulibacter" and denitrifying bacteria based on genes of ppk1, narG, nirS and nirK.

    Science.gov (United States)

    Zeng, Wei; Zhang, Jie; Wang, Anqi; Peng, Yongzhen

    2016-05-01

    Relevance of clade-level population dynamics of "Candidatus Accumulibacter" to performance of denitrifying phosphorus (P) removal from municipal wastewater was investigated. Stable denitrifying P removal in anoxic zone of continuous-flow reactor was achieved, accounting for 90% of total P removal. Clades IIC and IIF affiliated with Accumulibacter lineage were the dominant clades during denitrifying P removal, reaching 90% of ppk1 clone library. NarG gene library indicated Gamma and Beta-proteobacteria played an important role in nitrate reduction. Diversity and abundance of nirS library was much more than nirK, and thus became the main functional gene to execute nitrite reduction. Based on abundance of nirS, nirK and ppk1, the ratio of Accumulibacter capable of denitrifying P removal to total Accumulibacter was 22%. No matter whether Accumulibacter had narG gene or not, high abundance of narG at a level of 10(9)cells/(g dried-sludge) promoted nitrate reduced to nitrite, ensuring performance of denitrifying P removal. PMID:26896717

  1. Beyond Job Enrichment to Employment Enrichment

    Science.gov (United States)

    Werther, William B., Jr.

    1975-01-01

    Employment enrichment views the total work environment confronting employees as a system consisting of two overlapping areas: worker-job and worker-organization subsystems. Job enrichment has improved the worker-job subsystem. The focus of this article is on methods of improving the worker-organization relationship. (Author/JB)

  2. Development of a rapid lateral flow immunoassay test for detection of exosomes previously enriched from cell culture medium and body fluids.

    Science.gov (United States)

    Oliveira-Rodríguez, Myriam; López-Cobo, Sheila; Reyburn, Hugh T; Costa-García, Agustín; López-Martín, Soraya; Yáñez-Mó, María; Cernuda-Morollón, Eva; Paschen, Annette; Valés-Gómez, Mar; Blanco-López, Maria Carmen

    2016-01-01

    Exosomes are cell-secreted nanovesicles (40-200 nm) that represent a rich source of novel biomarkers in the diagnosis and prognosis of certain diseases. Despite the increasingly recognized relevance of these vesicles as biomarkers, their detection has been limited due in part to current technical challenges in the rapid isolation and analysis of exosomes. The complexity of the development of analytical platforms relies on the heterogeneous composition of the exosome membrane. One of the most attractive tests is the inmunochromatographic strips, which allow rapid detection by unskilled operators. We have successfully developed a novel lateral flow immunoassay (LFIA) for the detection of exosomes based on the use of tetraspanins as targets. We have applied this platform for the detection of exosomes purified from different sources: cell culture supernatants, human plasma and urine. As proof of concept, we explored the analytical potential of this LFIA platform to accurately quantify exosomes purified from a human metastatic melanoma cell line. The one-step assay can be completed in 15 min, with a limit of detection of 8.54×10(5) exosomes/µL when a blend of anti-CD9 and anti-CD81 were selected as capture antibodies and anti-CD63 labelled with gold nanoparticles as detection antibody. Based on our results, this platform could be well suited to be used as a rapid exosome quantification tool, with promising diagnostic applications, bearing in mind that the detection of exosomes from different sources may require adaptation of the analytical settings to their specific composition. PMID:27527605

  3. Development of a rapid lateral flow immunoassay test for detection of exosomes previously enriched from cell culture medium and body fluids

    Directory of Open Access Journals (Sweden)

    Myriam Oliveira-Rodríguez

    2016-08-01

    Full Text Available Exosomes are cell-secreted nanovesicles (40–200 nm that represent a rich source of novel biomarkers in the diagnosis and prognosis of certain diseases. Despite the increasingly recognized relevance of these vesicles as biomarkers, their detection has been limited due in part to current technical challenges in the rapid isolation and analysis of exosomes. The complexity of the development of analytical platforms relies on the heterogeneous composition of the exosome membrane. One of the most attractive tests is the inmunochromatographic strips, which allow rapid detection by unskilled operators. We have successfully developed a novel lateral flow immunoassay (LFIA for the detection of exosomes based on the use of tetraspanins as targets. We have applied this platform for the detection of exosomes purified from different sources: cell culture supernatants, human plasma and urine. As proof of concept, we explored the analytical potential of this LFIA platform to accurately quantify exosomes purified from a human metastatic melanoma cell line. The one-step assay can be completed in 15 min, with a limit of detection of 8.54×105 exosomes/µL when a blend of anti-CD9 and anti-CD81 were selected as capture antibodies and anti-CD63 labelled with gold nanoparticles as detection antibody. Based on our results, this platform could be well suited to be used as a rapid exosome quantification tool, with promising diagnostic applications, bearing in mind that the detection of exosomes from different sources may require adaptation of the analytical settings to their specific composition.

  4. Enrichment of Breast Cancer Stem Cells by Serum-free Shaking Suspension Culture%无血清摇动悬浮培养富集乳腺癌干细胞

    Institute of Scientific and Technical Information of China (English)

    闫文星; 陈玉丙; 张红梅; 国春龙; 王铁君

    2011-01-01

    Objective To investigate the characteristics of division of breast cancer MCF-7 cells under various conditions so as to develop a rapid and effective method for enrichment of breast cancer stem cells. Methods MCF-7 cells were subjected to static culture in complete medium (group A), shaking culture in complete medium (group B), static culture with cytokine (group C) and shaking culture with cytokine (group D) respectively, for 12, 24 and 36 h, then observed for division under inverted phase contrast microscope, based on which clone formation rate was calculated, and determined for the percentage of CD44+/CD24"/low lymphocyte subsets. Results In groups B and C, rod-like divisions were observed in both about 30% of cells 12 h, and in about 50% and about 60% of cells respectively 24 h, while large cell clones were formed 36 h after culture. However, in group D, rod-like division was observed in about 50% of cells 12 h, and in about 80% of cells 24 h when several cell clones appeared, while the number of cell clones decreased 36 h after culture. The percentage of CD44+/CD24"/km lymphocyte subsets 12 h after culture in group D (8. 05%) was 8 times of those in group B (0. 99%) and 2. 1 times of those in group C (3. 80%). However, the percentage 24 h after culture in group D (15. 24%) was 3 times of those in group B (4. 83%) and 6 times of those in group C (2. 30%). The percentage in group D decreased to 9. 68% 36 h after culture, which was about 9 times of those in groups B (0. 95%) and C (1. 03%). Conclusion The mitotic division of MCF-7 cells was accelerated in shaking culture with cytokine, while the percentage of CD44+/CD24'/low lymphocyte subsets increased rapidly, and stem cell pool increased significantly, indicating serum-free shaking suspension culture a rapid and effective method for enrichment of breast cancer stem cells.%目的 探讨不同培养条件下乳腺癌MCF-7细胞的分裂特点,建立快速、有效的乳腺癌干细胞富集方法.方法 将MCF-7

  5. Diversity and distribution of amoA-type nitrifying and nirS-type denitrifying microbial communities in the Yangtze River estuary

    OpenAIRE

    Y. Zhang; Xie, X.; Jiao, N.; Hsiao, S. S.-Y.; Kao, S.-J.

    2014-01-01

    Coupled nitrification–denitrification plays a critical role in the removal of excess nitrogen, which is chiefly caused by humans, to mitigate estuary and coastal eutrophication. Despite its obvious importance, limited information about the relationships between nitrifying and denitrifying microbial communities in estuaries, and their controlling factors have been documented. We investigated the nitrifying and denitrifying microbial communities in the estuary of turbid subtro...

  6. Moving Denitrifying Bioreactors beyond Proof of Concept: Introduction to the Special Section.

    Science.gov (United States)

    Christianson, Laura E; Schipper, Louis A

    2016-05-01

    Denitrifying bioreactors are organic carbon-filled excavations designed to enhance the natural process of denitrification for the simple, passive treatment of nitrate-nitrogen. Research on and installation of these bioreactors has accelerated within the past 10 years, particularly in watersheds concerned about high nonpoint-source nitrate loads and also for tertiary wastewater treatment. This special section, inspired by the meeting of the Managing Denitrification in Agronomic Systems Community at the 2014 Annual Meeting of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, aims to firmly establish that denitrifying bioreactors for treatment of nitrate in drainage waters, groundwater, and some wastewaters have moved beyond the proof of concept. This collection of 14 papers expands the peer-reviewed literature of denitrifying bioreactors into new locations, applications, and environmental conditions. There is momentum behind the pairing of wood-based bioreactors with other media (biochar, corn cobs) and in novel designs (e.g., use within treatment trains or use of baffles) to broaden applicability into new kinds of waters and pollutants and to improve performance under challenging field conditions such as cool early season agricultural drainage. Concerns about negative bioreactor by-products (nitrous oxide and hydrogen sulfide emissions, start-up nutrient flushing) are ongoing, but this translates into a significant research opportunity to develop more advanced designs and to fine tune management strategies. Future research must think more broadly to address bioreactor impacts on holistic watershed health and greenhouse gas balances and to facilitate collaborations that allow investigation of mechanisms within the bioreactor "black box." PMID:27136139

  7. Moving Denitrifying Bioreactors beyond Proof of Concept: Introduction to the Special Section.

    Science.gov (United States)

    Christianson, Laura E; Schipper, Louis A

    2016-05-01

    Denitrifying bioreactors are organic carbon-filled excavations designed to enhance the natural process of denitrification for the simple, passive treatment of nitrate-nitrogen. Research on and installation of these bioreactors has accelerated within the past 10 years, particularly in watersheds concerned about high nonpoint-source nitrate loads and also for tertiary wastewater treatment. This special section, inspired by the meeting of the Managing Denitrification in Agronomic Systems Community at the 2014 Annual Meeting of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, aims to firmly establish that denitrifying bioreactors for treatment of nitrate in drainage waters, groundwater, and some wastewaters have moved beyond the proof of concept. This collection of 14 papers expands the peer-reviewed literature of denitrifying bioreactors into new locations, applications, and environmental conditions. There is momentum behind the pairing of wood-based bioreactors with other media (biochar, corn cobs) and in novel designs (e.g., use within treatment trains or use of baffles) to broaden applicability into new kinds of waters and pollutants and to improve performance under challenging field conditions such as cool early season agricultural drainage. Concerns about negative bioreactor by-products (nitrous oxide and hydrogen sulfide emissions, start-up nutrient flushing) are ongoing, but this translates into a significant research opportunity to develop more advanced designs and to fine tune management strategies. Future research must think more broadly to address bioreactor impacts on holistic watershed health and greenhouse gas balances and to facilitate collaborations that allow investigation of mechanisms within the bioreactor "black box."

  8. Marine Oxygen-Deficient Zones Harbor Depauperate Denitrifying Communities Compared to Novel Genetic Diversity in Coastal Sediments.

    Science.gov (United States)

    Bowen, Jennifer L; Weisman, David; Yasuda, Michie; Jayakumar, Amal; Morrison, Hilary G; Ward, Bess B

    2015-08-01

    Denitrification is a critically important biogeochemical pathway that removes fixed nitrogen from ecosystems and thus ultimately controls the rate of primary production in nitrogen-limited systems. We examined the community structure of bacteria containing the nirS gene, a signature gene in the denitrification pathway, from estuarine and salt marsh sediments and from the water column of two of the world's largest marine oxygen-deficient zones (ODZs). We generated over 125,000 nirS gene sequences, revealing a large degree of genetic diversity including 1,815 unique taxa, the vast majority of which formed clades that contain no cultured representatives. These results underscore how little we know about the genetic diversity of metabolisms underlying this critical biogeochemical pathway. Marine sediments yielded 1,776 unique taxa when clustered at 95 % sequence identity, and there was no single nirS denitrifier that was a competitive dominant; different samples had different highly abundant taxa. By contrast, there were only 39 unique taxa identified in samples from the two ODZs, and 99 % of the sequences belonged to 5 or fewer taxa. The ODZ samples were often dominated by nirS sequences that shared a 92 % sequence identity to a nirS found in the anaerobic ammonium-oxidizing (anammox) genus Scalindua. This sequence was abundant in both ODZs, accounting for 38 and 59 % of all sequences, but it was virtually absent in marine sediments. Our data indicate that ODZs are remarkably depauperate in nirS genes compared to the remarkable genetic richness found in coastal sediments.

  9. POTENTIAL APPLICATION OF AN AEROBIC DENITRIFYING BACTERIUM AS BIOAGENTS FOR WASTEWATER TREATMENT

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Denitrificationis the ability of bacteria to use nitro-gen oxides(NO3-and NO2-)as electron acceptorsto pro-duce gaseous nitrogen,mainly N2.The oxidation of or-ganic material coupled to reduction of oxygen leads to ahigher energy yield than reduction of nitrate.Oxygen iscommonly accepted to be the first choice as electron ac-ceptor[1].Therefore,denitrifying is generally thought toonly occur under almost anaerobic conditions.Anefficientwastewater treatment toremove nitrogen components relieson successively ex...

  10. Marinobacter hydrocarbonoclasticus NY-4, a novel denitrifying, moderately halophilic marine bacterium

    OpenAIRE

    Li, Rongpeng; Zi, Xiaoli; Wang, Xinfeng; Zhang, Xia; Gao, Haofeng; Hu, Nan

    2013-01-01

    The isolation and characterization of a novel halophilic denitrifying marine bacterium is described. The halophilic bacterium, designated as NY-4, was isolated from soil in Yancheng City, China, and identified as Marinobacter hydrocarbonoclasticus by 16S rRNA gene sequence phylogenetic analysis. This organism can grow in NaCl concentrations ranging from 20 to 120 g/L. Optimum growth occurs at 80 g/L NaCl and pH 8.0. The organism can grow on a broad range of carbon sources and demonstrated eff...

  11. Adaptation of Denitrifying Populations to Low Soil pH †

    OpenAIRE

    Parkin, Timothy B.; Sexstone, Alan J.; Tiedje, James M.

    1985-01-01

    Natural denitrification rates and activities of denitrifying enzymes were measured in an agricultural soil which had a 20-year past history of low pH (pH ca. 4) due to fertilization with acid-generating ammonium salts. The soil adjacent to this site had been limed and had a pH of ca. 6.0. Natural denitrification rates of these areas were of similar magnitude: 158 ng of N g−1 of soil day−1 for the acid soil and 390 ng of N g−1 of soil day−1 at the neutral site. Estimates of in situ denitrifyin...

  12. Development of Denitrifying and Nitrifying Bacteria and Their Co-occurrence in Newly Created Biofilms in Urban Streams

    Science.gov (United States)

    Vaessen, T. N.; Martí Roca, E.; Pinay, G.; Merbt, S. N.

    2015-12-01

    Biofilms play a pivotal role on nutrient cycling in streams, which ultimately dictates the export of nutrients to downstream ecosystems. The extent to which biofilms influence the concentration of dissolved nutrients, oxygen and pH in the water column may be determined by the composition of the microbial assemblages and their activity. Evidence of biological interactions among bacteria and algae are well documented. However, the development, succession and co-occurence of nitrifying and denitrifying bacteria remain poorly understood. These bacteria play a relevant role on the biogeochemical process associated to N cycling, and their relative abundance can dictate the fate of dissolved inorganic nitrogen in streams. In particular, previous studies indicated that nitrifiers are enhanced in streams receiving inputs from wastewater treatment plant (WWTP) effluents due to both increases in ammonium concentration and inputs of nitrifiers. However, less is known about the development of denitrifiers in receiving streams, although environmental conditions seem to favor it. We conducted an in situ colonization experiment in a stream receiving effluent from a WWTP to examine how this input influences the development and co-occurrence of nitrifying and denitrifying bacteria. We placed artificial substrata at different locations relative to the effluent and sampled them over time to characterize the developed biofilm in terms of bulk measurements (organic matter content and algae) as well as in terms of abundance of nitrifiers and denitrifiers (using qPCR). The results of this study contribute to a better understanding of the temporal dynamics of denitrifiers and nitrifiers in relation to the developed organic matter, dissolved oxygen and pH and the biomass accrual in stream biofilms under the influence of nutrients inputs from WWTP effluent. Ultimately, the results provide insights on the potential role of nitrifiers and denitrifiers on N cycling in WWTP effluent receiving

  13. Association of Novel and Highly Diverse Acid-Tolerant Denitrifiers with N2O Fluxes of an Acidic Fen▿ †

    OpenAIRE

    Palmer, Katharina; Drake, Harold L; Horn, Marcus A.

    2009-01-01

    Wetlands are sources of denitrification-derived nitrous oxide (N2O). Thus, the denitrifier community of an N2O-emitting fen (pH 4.7 to 5.2) was investigated. N2O was produced and consumed to subatmospheric concentrations in unsupplemented anoxic soil microcosms. Total cell counts and most probable numbers of denitrifiers approximated 1011 cells·gDW−1 (where DW is dry weight) and 108 cells·gDW−1, respectively, in both 0- to 10-cm and 30- to 40-cm depths. Despite this uniformity, depth-related ...

  14. Cultivation and irradiation of human fibroblasts in a medium enriched with platelet lysate for obtaining feeder layer in epidermal cell culture; Cultivo e irradiacao de fibroblastos humanos em meio enriquecido com lisado de plaquetas para obtencao de camada de sustentacao em culturas de celulas da epiderme

    Energy Technology Data Exchange (ETDEWEB)

    Yoshito, Daniele

    2011-07-01

    For over 30 years, the use of culture medium, enriched with bovine serum, and murines fibroblasts, with the rate of proliferation controlled by irradiation or by share anticarcinogenic drugs, has been playing successfully its role in assisting in the development of keratinocytes in culture, for clinical purposes. However, currently there is a growing concern about the possibility of transmitting prions and animals viruses to transplanted patients. Taking into account this concern, the present work aims to cultivate human fibroblasts in a medium enriched with human platelets lysate and determine the irradiation dose of these cells, for obtaining feeder layer in epidermal cell culture. For carrying out the proposed objective, platelets lysis has standardized, this lysate was used for human fibroblasts cultivation and the irradiation dose enough to inhibit its duplication was evaluated. Human keratinocytes were cultivated in these feeder layers, in culture medium enriched with the lysate. With these results we conclude that the 10% platelets lysate promoted a better adhesion and proliferation of human fibroblasts and in all dose levels tested (60 to 300 Gy), these had their mitotic activity inactivated by ionizing irradiation, being that the feeder layers obtained with doses from 70 to 150 Gy were those that provided the best development of keratinocytes in medium containing 2.5% of human platelet lysate. Therefore, it was possible to standardize both the cultivation of human fibroblasts as its inactivation for use as feeder layer in culture of keratinocytes, so as to eliminate xenobiotics components. (author)

  15. Fate of aniline and sulfanilic acid in UASB bioreactors under denitrifying conditions.

    Science.gov (United States)

    Pereira, Raquel; Pereira, Luciana; van der Zee, Frank P; Madalena Alves, M

    2011-01-01

    Two upflow anaerobic sludge blanket (UASB) reactors were operated to investigate the fate of aromatic amines under denitrifying conditions. The feed consisted of synthetic wastewater containing aniline and/or sulfanilic acid and a mixture of volatile fatty acids (VFA) as the primary electron donors. Reactor 1 (R1) contained a stoichiometric concentration of nitrate and Reactor 2 (R2) a stoichiometric nitrate and nitrite mixture as terminal electron acceptors. The R1 results demonstrated that aniline could be degraded under denitrifying conditions while sulfanilic acid remains. The presence of nitrite in the influent of R2, caused a chemical reaction that led to immediate disappearance of both aromatic amines and the formation of an intense yellow coloured solution. HPLC analysis of the influent solution, revealed the emergence of three product peaks: the major one at retention time (R(t)) 14.3 min and two minor at R(t) 17.2 and 21.5 min. In the effluent, the intensity of the peaks at R(t) 14.3 and 17.2 min was very low and of that at R(t) 21.5 min increased (∼3-fold). Based on the mass spectrometry analysis, we propose the structures of some possible products, mainly azo compounds. Denitrification activity tests suggest that biomass needed to adapt to the new coloured compounds, but after a 3 days lag phase, activity is recovered and the final (N(2) + N(2)O) is even higher than that of the control.

  16. Full-scale post denitrifying biofilters: sinks of dissolved N2O?

    Science.gov (United States)

    Bollon, Julien; Filali, Ahlem; Fayolle, Yannick; Guerin, Sabrina; Rocher, Vincent; Gillot, Sylvie

    2016-09-01

    In this study, nitrous oxide (N2O) emissions from a full-scale denitrifying biofilter plant were continuously monitored over two periods (summer campaign in September 2014 and winter campaign in February 2015). Results of the summer campaign showed that the major part (>99%) of N2O flux was found in the liquid phase and was discharged with the effluent. N2O emissions were highly variable and represented in average 1.28±1.99% and 0.22±0.31% of the nitrate uptake rate during summer and winter campaigns, respectively. Denitrification was able to consume a large amount of dissolved N2O coming from the upstream nitrification stage. In the absence of methanol injection failure and with an influent BOD/NO3-N ratio higher than 3, average reduction of N2O was estimated to be of 93%. The control of exogenous carbon dosage is essential to minimize N2O production from denitrifying biofilters, in correlation to NO2-N concentrations in the filter.

  17. Experimental Study on Denitrification Using Coated Electrode of Immobilized Denitrifying Bacteria

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To develop a coated electrode of immobilized denitrificants and to evaluate the performance of a bioelectrochemical reactor to enhance and control denitrification. Methods Denitrifying bacteria were developed by batch incubation and immobilized with polyvinyl alcohol (PVA) on the surface of activated carbon fiber (ACF) to make a coated electrode. Then the coated electrode (cathode) and graphite electrode (anode) were transferred to the reactor to reduce nitrate. Results After acclimated to the mixtrophic and autotrophic denitrification stages, the denitrifying bacteria could use hydrogen as an electron donor to reduce nitrate. When the initial nitrate concentration was 30.2 mg NO3--N/L, the denitrification efficiency was 57.3% at an applied electric current of 15 mA and a hydraulic retention time (HRT) of 12 hours.Correspondingly, the current density was 0.083 mA / cm2. The nitrate removal rate of the reactor was 34.4 g NO3--N / m3·d, and the surface area loading was 1.34 g NO3--N / m2·d. Conclusion The coated electrode may keep high quantity of biomass, thus achieving a high denitrification rate. Denitrification efficiencies are related to HRT, current density, oxidation reduction potential (ORP), dissolved oxygen (DO), pH value, and temperature.

  18. Full-scale post denitrifying biofilters: sinks of dissolved N2O?

    Science.gov (United States)

    Bollon, Julien; Filali, Ahlem; Fayolle, Yannick; Guerin, Sabrina; Rocher, Vincent; Gillot, Sylvie

    2016-09-01

    In this study, nitrous oxide (N2O) emissions from a full-scale denitrifying biofilter plant were continuously monitored over two periods (summer campaign in September 2014 and winter campaign in February 2015). Results of the summer campaign showed that the major part (>99%) of N2O flux was found in the liquid phase and was discharged with the effluent. N2O emissions were highly variable and represented in average 1.28±1.99% and 0.22±0.31% of the nitrate uptake rate during summer and winter campaigns, respectively. Denitrification was able to consume a large amount of dissolved N2O coming from the upstream nitrification stage. In the absence of methanol injection failure and with an influent BOD/NO3-N ratio higher than 3, average reduction of N2O was estimated to be of 93%. The control of exogenous carbon dosage is essential to minimize N2O production from denitrifying biofilters, in correlation to NO2-N concentrations in the filter. PMID:27139304

  19. Efficiency and detrimental side effects of denitrifying bioreactors for nitrate reduction in drainage water.

    Science.gov (United States)

    Weigelhofer, Gabriele; Hein, Thomas

    2015-09-01

    A laboratory column experiment was conducted to test the efficiency of denitrifying bioreactors for the nitrate (NO3-N) removal in drainage waters at different flow rates and after desiccation. In addition, we investigated detrimental side effects in terms of the release of nitrite (NO2-N), ammonium (NH4-N), phosphate (PO4-P), dissolved organic carbon (DOC), methane (CH4), and dinitrogen oxide (N2O). The NO3-N removal efficiency decreased with increasing NO3-N concentrations, increasing flow rates, and after desiccation. Bioreactors with purely organic fillings showed higher NO3-N removal rates (42.6-55.7 g NO3-N m(-3) day(-1)) than those with organic and inorganic fillings (6.5-21.4 g NO3-N m(-3) day(-1)). The release of NO2-N and DOC was considerable and resulted in concentrations of up to 800 μg NO2-N L(-1)and 25 mg DOC L(-1) in the effluent water. N2O concentrations increased by 4.0 to 15.3 μg N2O-N L(-1) between the influent and the effluent, while CH4 production rates were low. Our study confirms the high potential of denitrifying bioreactors to mitigate NO3-N pollution in drainage waters, but highlights also the potential risks for the environment. PMID:25943519

  20. High-efficient nitrogen removal by coupling enriched autotrophic-nitrification and aerobic-denitrification consortiums at cold temperature.

    Science.gov (United States)

    Zou, Shiqiang; Yao, Shuo; Ni, Jinren

    2014-06-01

    This study paid particular attention to total nitrogen removal at low temperature (10°C) by excellent coupling of enriched autotrophic nitrifying and heterotrophic denitrifying consortiums at sole aerobic condition. The maximum specific nitrifying rate of the nitrifying consortium reached 8.85mgN/(gSSh). Further test in four identical lab-scale sequencing batch reactors demonstrated its excellent performance for bioaugmentation in potential applications. On the other hand, the aerobic denitrifying consortium could achieve a specific denitrifying rate of 32.93mgN/(gSSh) under dissolved oxygen of 1.0-1.5mg/L at 10°C. Coupling both kinds of consortiums was proved very successful for a perfect total nitrogen (TN) removal at COD/N of 4 and dissolved oxygen of 1.5-4.5mg/L, which was hardly reached by any single consortium reported previously. The encouraging results from coupling aerobic consortiums implied a huge potential in practical treatment of low-strength domestic wastewater (200-300mg/L COD) during wintertime.

  1. 反硝化除磷菌筛选及其特性研究%Studies on the screening of denitrifying and phosphorus removal bacteria and its characteristics

    Institute of Scientific and Technical Information of China (English)

    安健; 伏光辉; 阮记明; 陈百尧; 龚琪本; 唐兴本; 杨先乐

    2012-01-01

    [Objective] In order to study on the characteristics of denitrifying and phosphorus removal bacteria. [Methods] Many strains with denitrification and phosphorus removal characteristics under aerobic condition were isolated by screening of microorganism and methods of biological characteristics from the water and sediment samples of shrimp culture ponds. [Results] Among them strain LY-1 could remove nitrite nitrogen from 10 mg/L to 0.04 mg/L, and the PO43- -P from 10 mg/L to 0.05 mg/L in 18 h, respectively; and approximately to 100% of denitrifying and phosphorus removal rate were reached at the DO concentration of 5.0-5.9 mg/L. Furthermore, in comparison with a denitrifying and phosphorus removal bacterium, Bacillus subtilis selected as the positive control and Escherichia coli as the negative control, strain LY-1 was tested under different pH, temperature, salty, PO43--P and nitrite concentration, its denitrifying removal rate was reached approximately 99%, and phosphorus removal rate reached 86% at the pH of 5-9; the denitrifying and phosphorus removal rate of strain YX-6 reached proximately 100% at 30 °C; The rate almost reached 99% when salty ranged between 5 and 15, phosphorus concentration was 10 mg/L and nitrite nitrogen concentration was 20 mg/L. [Conclusion] The results showed that the denitrifying and phosphorus removal of LY-1 was significantly higher than that of the two controls (P<0.05). According to the morphological, physiological and biochemical properties, and the analysis of its 16S rRNA gene sequence, strain LY-1 was identified as Bacillus cereus primarily.%[目的]研究反硝化除磷菌特性.[方法]通过微生物筛选和生物学特性研究方法,从对虾养殖池塘中筛选出多株可在有氧条件下同时具有反硝化除磷功能的菌种.[结果]菌株LY-1可在18h内将初始量为10 mg/L的亚硝酸盐氮降低至0.04 mg/L,PO43--P降低至0.05 mg/L.在DO浓度为5.0-5.9 mg/L时,该菌反硝化除磷率近100%.试验选取

  2. In situ detection of denitrifying bacteria by mRNA-targeted nucleic acid probes and catalyzed reporter deposition

    DEFF Research Database (Denmark)

    Kofoed, Michael Vedel; Stief, Peter; Poulsen, Morten;

    reductase) and nosZ (encoding nitrous oxide reductase), to detect nitrate-reducing and completely denitrifying bacteria, respectively. Enzyme-labelled oligonucleotide probes and digoxygenin-labelled polynucleotide probes were evaluated for in situ hybridization in combination with immunochemical detection......Z in freshwater sediments and the guts of benthic invertebrates.    ...

  3. Using T-RFLP data on denitrifier community composition to inform understanding of denitrification in stream sediments (Invited)

    Science.gov (United States)

    Wang, S.; Somers, K.; Sudduth, E.; Hassett, B.; Bernhardt, E. S.; Urban, D. L.

    2010-12-01

    We used terminal restriction fragment length polymorphism (T-RFLP), a molecular fingerprinting method, to characterize denitrifier communities in sediments taken from 48 study streams in North Carolina, USA. In addition to characterizing denitrifier communities, we also used denitrification enzyme activity (DEA) assays to measure potential denitrification rates. Due to differences in watershed land-use, study streams covered a gradient of nitrogen and carbon concentrations, as well as a gradient of contaminant loading from stormwater and sanitary sewers. Nitrogen and carbon (i.e., substrate) concentrations are commonly used to make predictions about denitrification rates in streams. Such models do not take into account denitrifier community composition, which may be an important, independent control of denitrification rates, particularly under stressful conditions (e.g., high contaminant loading) that prevent communities from capitalizing on high substrate availability. Our results indicate that substrate availability by itself was a weak predictor of denitrification rates; the same was also true for denitrifier community composition. However, when both factors were incorporated in a multiple regression model, the percent variation explained increased substantially. These findings suggest that T-RFLP, a relatively cost-effective method, can be used to improve our understanding of controls on denitrification rates in streams with varying watershed land-uses.

  4. Toxic effects exerted on methanogenic, nitrifying and denitrifying bacteria by chemicals used in a milk analysis laboratory

    NARCIS (Netherlands)

    Lopez-Fiuza, J.; Buys, B.; Mosquera-Corral, A.; Omil, F.; Mendez, R.

    2002-01-01

    The toxic effects caused by the chemicals contained in wastewaters generated by laboratories involved in raw milk analyses were assessed using batch assays. These assays were carried out separately with methanogenic, ammonium-oxidizing, nitrite-oxidizing and denitrifying bacteria. Since sodium azide

  5. POTENTIAL APPLICATION OF AN AEROBIC DENITRIFYING BACTERIUM AS BIOAGENTS FOR WASTEWATER TREATMENT%利用需氧反硝化细菌处理废水的潜在应用价值

    Institute of Scientific and Technical Information of China (English)

    LI Ping; LIU De-Li; ZHENG Yong-Liang; JIANG Yue; ZHANG Shan; CHEN Shu-Li

    2006-01-01

    A bacterium strain HS-03 was isolated from the activated sludge plant in a suburb of Wuhan city, China which has been found to be capable of aerobic denitrification. The effect of different inoculated amounts of pre-cultured media was analyzed. The denitrifying rates of this strain under aerobic and micro-anaerobic conditions were compared. The result indicated that the rate was almost not affected by the presence of oxygen. 10m M nitrate was removed more than 90% in 36 hours by this bacterium in the specific medium. During the denitrifying process, nitrite was always kept at very low level. The denitrification potential of this bacterium was evaluated to treat artificial wastewater under fully aerobic conditions. Main biochemical and physiological features of this strain were characterized. The 16S rDNA sequence was compared with the published data in GenBank by using BLAST. The BLAST level of similarity to Pseudomonas stutzeri was 99.1%. These results of phenotype and genotype proved that the strain HS03 was a new strain belonging to the species of P. stutzeri.

  6. Acidophilic denitrifiers dominate the N2O production in a 100-year-old tea orchard soil.

    Science.gov (United States)

    Huang, Ying; Long, Xi-En; Chapman, Stephen J; Yao, Huaiying

    2015-03-01

    Aerobic denitrification is the main process for high N2O production in acid tea field soil. However, the biological mechanisms for the high emission are not fully understood. In this study, we examined N2O emission and denitrifier communities in 100-year-old tea soils with four pH levels (3.71, 5.11, 6.19, and 7.41) and four nitrate concentration (0, 50, 200, and 1000 mg kg(-1) of NO3 (-)-N) addition. Results showed the highest N2O emission (10.1 mg kg(-1) over 21 days) from the soil at pH 3.71 with 1000 mg kg(-1) NO3 (-) addition. The N2O reduction and denitrification enzyme activity in the acid soils (pH pH 7.41. Moreover, TRF 78 of nirS and TRF 187 of nosZ dominated in soils of pH 3.71, suggesting an important role of acidophilic denitrifiers in N2O production and reduction. CCA analysis also showed a negative correlation between the dominant denitrifier ecotypes (nirS TRF 78, nosZ TRF 187) and soil pH. The representative sequences were identical to those of cultivated denitrifiers from acidic soils via phylogenetic tree analysis. Our results showed that the acidophilic denitrifier adaptation to the acid environment results in high N2O emission in this highly acidic tea soil. PMID:25273518

  7. Uranium enrichment. Principles

    International Nuclear Information System (INIS)

    Uranium enrichment industry is a more than 60 years old history and has developed without practically no cost, efficiency or profit constraints. However, remarkable improvements have been accomplished since the Second World War and have led to the development of various competing processes which reflect the diversity of uranium compositions and of uranium needs. Content: 1 - general considerations: uranium isotopes, problem of uranium enrichment, first realizations (USA, Russia, Europe, Asia, other countries), present day situation, future needs and market evolution; 2 - principles of isotopic separation: processes classification (high or low enrichment), low elementary enrichment processes, equilibrium time, cascade star-up and monitoring, multi-isotopes case, uranium reprocessing; 3 - enrichment and proliferation. (J.S.)

  8. Heterotrophic ammonium removal characteristics of an aerobic heterotrophic nitrifying-denitrifying bacterium, Providencia rettgeri YL

    Institute of Scientific and Technical Information of China (English)

    TAYLOR Shauna M; HE Yiliang; ZHAO Bin; HUANG Jue

    2009-01-01

    Bacterium Providencia rettgeri YL was found to exhibit an unusual ability to heterotrophically nitrify and aerobically denitrify various concentrations of ammonium (NH4+-N). In order to further analyze its removal ability, several experiments were conducted to identify the growth and ammonium removal response in different carbon to nitrogen (C/N) mass ratios, shaking speeds, temperatures, ammonium concentrations and to qualitatively verify the production of nitrogen gas using gas chromatography techniques. Results showed that under optimum conditions (C/N 10, 30℃, 120 r/min), YL can significantly remove low and high concentrations of ammonium within 12 to 48 h of growth. The nitrification products hydroxylamine (NH2OH), nitrite (NO2-) and nitrate (NO3-) as well as the denitrification product, nitrogen gas (N2), were detected under completely aerobic conditions.

  9. Enhanced Performance of Denitrifying Sulifde Removal Process by 1,2-Naphthoquinone-4-Sulphonate

    Institute of Scientific and Technical Information of China (English)

    Liu Chunshuang; Han Kang; Zhao Dongfeng; Guo Yadonag; Liu Lihong; Liu Fang; Zhao Chaocheng

    2016-01-01

    The denitrifying sulifde removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitriifers can simultaneously convert nitrate, sulifde and acetate species into di-nitrogen gas, elemental sulfur and carbon dioxide, respectively, at high loading rates. This study has determined that the reaction rate of sulifde oxidized into sulfur could be enhanced in the presence of 1,2-naphthoquinone-4-sulphonate (NQS). The presence of NQS mitigated the inhibi-tion effects of sulifde species on denitriifcation. Furthermore, the reaction rates of nitrate and acetate to nitrogen gas and CO2, respectively, were also promoted in the presence of NQS, thereby enhancing the performance of DSR granules. The advantages and disadvantages of applying the NQS-DSR process are discussed.

  10. Maintaining granulation in a denitrifying upflow sludge-blanket reactor treating groundwater with low hardness.

    Science.gov (United States)

    Rouse, Joseph D; Nakashima, Takahiro; Furukawa, Kenji

    2003-01-01

    Maintenance of denitrifying granular sludge for treating soft groundwater (total hardness = 75 mg calcium carbonate/L) in an upflow sludge-blanket reactor was demonstrated with complete removal of applied nitrate (20 mg N/L) over extended operation and a hydraulic residence time of 34 minutes. A high pH of approximately 9.0 was shown to be important for generation of mineral precipitation needed for production of heavy granular sludge with good retention characteristics. As a method of increasing precipitation potential, pH adjustment was determined to be more economically favorable than calcium or alkalinity supplementation. In addition, temporary increases in substrate loading were shown to be effective for enhancing biomass levels in a manageable granular sludge. The significance of biomass in promoting mineral precipitation was discussed.

  11. Denitrifying sulfide removal process on high-salinity wastewaters in the presence of Halomonas sp.

    Science.gov (United States)

    Liu, Chunshuang; Zhao, Dongfeng; Ma, Wenjuan; Guo, Yadong; Wang, Aijie; Wang, Qilin; Lee, Duu-Jong

    2016-02-01

    Biological conversion of sulfide, acetate, and nitrate to, respectively, elemental sulfur (S(0)), carbon dioxide, and nitrogen-containing gas (such as N2) at NaCl concentration of 35-70 g/L was achieved in an expanded granular sludge bed (EGSB) reactor. A C/N ratio of 1:1 was noted to achieve high sulfide removal and S(0) conversion rate at high salinity. The extracellular polymeric substance (EPS) quantities were increased with NaCl concentration, being 11.4-mg/g volatile-suspended solids at 70 mg/L NaCl. The denitrifying sulfide removal (DSR) consortium incorporated Thauera sp. and Halomonas sp. as the heterotrophs and Azoarcus sp. being the autotrophs at high salinity condition. Halomonas sp. correlates with the enhanced DSR performance at high salinity. PMID:26454867

  12. Soil functional operating range linked to microbial biodiversity and community composition using denitrifiers as model guild.

    Directory of Open Access Journals (Sweden)

    Sara Hallin

    Full Text Available Soil microorganisms are key players in biogeochemical cycles. Yet, there is no consistent view on the significance of microbial biodiversity for soil ecosystem functioning. According to the insurance hypothesis, declines in ecosystem functioning due to reduced biodiversity are more likely to occur under fluctuating, extreme or rapidly changing environmental conditions. Here, we compare the functional operating range, a new concept defined as the complete range of environmental conditions under which soil microbial communities are able to maintain their functions, between four naturally assembled soil communities from a long-term fertilization experiment. A functional trait approach was adopted with denitrifiers involved in nitrogen cycling as our model soil community. Using short-term temperature and salt gradients, we show that the functional operating range was broader and process rates were higher when the soil community was phylogenetically more diverse. However, key bacterial genotypes played an important role for maintaining denitrification as an ecosystem functioning under certain conditions.

  13. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    Science.gov (United States)

    Shen, Hui; Thrush, Simon F; Wan, Xihe; Li, Hui; Qiao, Yi; Jiang, Ge; Sun, Ruijian; Wang, LiBao; He, Peimin

    2016-09-15

    Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm(-2), physical disturbance depth of 16.4cm, bacterial density of 0.18Lm(-2), and polychaetes biomass of 0.16kgm(-2), respectively. These results emphasize the value of combining different species in field-based bioremediation. PMID:27371956

  14. DRIVERS OF THE DYNAMICS OF DIAZOTROPHS AND DENITRIFIERS IN NORTH SEA BOTTOM WATERS AND SEDIMENTS

    Directory of Open Access Journals (Sweden)

    Lucas eStal

    2015-07-01

    Full Text Available The fixation of dinitrogen (N2 and denitrification are two opposite processes in the nitrogen cycle. The former transfers atmospheric dinitrogen gas into bound nitrogen in the biosphere, while the latter returns this bound nitrogen back to atmospheric dinitrogen. It is unclear whether or not these processes are intimately connected in any microbial ecosystem or that they are spatially and/or temporally separated. Here, we measured seafloor nitrogen fixation and denitrification as well as pelagic nitrogen fixation by using the stable isotope technique. Alongside, we measured the diversity, abundance, and activity of nitrogen-fixing and denitrifying microorganisms at three stations in the southern North Sea. Nitrogen fixation ranged from undetectable to 2.4 nmol N L-1 d-1 and from undetectable to 8.2 nmol N g-1 d-1 in the water column and seafloor, respectively. The highest rates were measured in August at Doggersbank, both for the water column and for the seafloor. Denitrification ranged from 1.7 to 208.8 µmol m-2 d-1 and the highest rates were measured in May at the Oyster Grounds. DNA sequence analysis showed sequences of nifH, a structural gene for nitrogenase, related to sequences from anaerobic sulfur/iron reducers and sulfate reducers. Sequences of the structural gene for nitrite reductase, nirS, were related to environmental clones from marine sediments. Quantitative polymerase chain reaction (qPCR data revealed the highest abundance of nifH and nirS genes at the Oyster Grounds. Quantitative reverse transcription polymerase chain reaction (qRT-PCR data revealed the highest nifH expression at Doggersbank and the highest nirS expression at the Oyster Grounds. The distribution of the diazotrophic and denitrifying communities seems to be subject to different selecting factors, leading to spatial and temporal separation of nitrogen fixation and denitrification. These selecting factors include temperature, organic matter availability, and

  15. Continuous nitrous oxide abatement in a novel denitrifying off-gas bioscrubber.

    Science.gov (United States)

    Frutos, Osvaldo D; Arvelo, Ilan A; Pérez, Rebeca; Quijano, Guillermo; Muñoz, Raúl

    2015-04-01

    The potential of a bioscrubber composed of a packed bed absorption column coupled to a stirred tank denitrification bioreactor (STR) was assessed for 95 days for the continuous abatement of a diluted air emission of N2O at different liquid recycling velocities. N2O removal efficiencies of up to 40 ± 1 % were achieved at the highest recirculation velocity (8 m h(-1)) at an empty bed residence time of 3 min using a synthetic air emission containing N2O at 104 ± 12 ppmv. N2O was absorbed in the packed bed column and further reduced in the STR at efficiencies >80 % using methanol as electron donor. The long-term operation of the bioscrubber suggested that the specialized N2O degrading community established was not able to use N2O as nitrogen source. Additional nitrification assays showed that the activated sludge used as inoculum was not capable of aerobically oxidizing N2O to nitrate or nitrite, regardless of the inorganic carbon concentration tested. Denitrification assays confirmed the ability of non-acclimated activated sludge to readily denitrify N2O at a specific rate of 3.9 mg N2O g VSS h(-1) using methanol as electron donor. This study constitutes, to the best of our knowledge, the first systematic assessment of the continuous abatement of N2O in air emission. A characterization of the structure of the microbial population in the absorption column by DGGE-sequencing revealed a high microbial diversity and the presence of heterotrophic denitrifying methylotrophs. PMID:25547842

  16. Modeling of Cr(VI) Bioreduction Under Fermentative and Denitrifying Conditions

    Science.gov (United States)

    Molins, S.; Steefel, C.; Yang, L.; Beller, H. R.

    2011-12-01

    The mechanisms of bioreductive immobilization of Cr(VI) were investigated by reactive transport modeling of a set of flow-through column experiments performed using natural Hanford 100H aquifer sediment. The columns were continuously eluted with 5 μM Cr(VI), 5 mM lactate as the electron donor, and selected electron acceptors (tested individually). Here we focus on the two separate experimental conditions that showed the most removal of Cr(VI) from solution: fermentation and denitrification. In each case, a network of enzymatic and abiotic reaction pathways was considered to interpret the rate of chromate reduction. The model included biomass growth and decay, and thermodynamic limitations on reaction rates, and was constrained by effluent concentrations measured by IC and ICP-MS and additional information from bacterial isolates from column effluent. Under denitrifying conditions, Cr(VI) reduction was modeled as co-metabolic with nitrate reduction based on experimental observations and previous studies on a denitrifying bacterium derived from the Hanford 100H aquifer. The reactive transport model results supported this interpretation of the reaction mechanism and were used to quantify the efficiency of the process. The models results also suggest that biomass growth likely relied on a nitrogen source other than ammonium (e.g. nitrate). Under fermentative conditions and based on cell suspension studies performed on a bacterial isolate from the columns, the model assumes that Cr(VI) reduction is carried out directly by fermentative bacteria that convert lactate into acetate and propionate. The evolution to complete lactate fermentation and Cr(VI) reduction took place over a week's time and simulations were used to determine an estimate for a lower limit of the rate of chromate reduction by calibration with the flow-through column experimental results. In spite of sulfate being added to these columns, sulfate reduction proceeded at a slow rate and was not well

  17. Responses of activities, abundances and community structures of soil denitrifiers to short-term mercury stress

    Institute of Scientific and Technical Information of China (English)

    Zhifeng Zhou; Yuanming Zheng; Jupei Shen; Limei Zhang; Yurong Liu; Jizheng He

    2012-01-01

    The responses of activities,abundances and community structures of soil denitrifiers to mercury(Hg)stress were investigated through a short-term incubation experiment.Four soil treatments with different concentrations of Hg(CK,Hg25,Hg50,and Hgl00,denoted as 0,25,50,and 100 mg Hg/kg dry soil,respectively)were incubated for 28 days.Soil denitrification enzyme activity(DEA)was measured at day 3,7 and 28.The abundances and community structures of two denitrification concerning genes,nirS(Cd1-nitrite reductase gene)and nosZ(nitrous oxide reductase gene),were analyzed using real-time PCR and denaturing gradient gel electrophoresis(DGGE).Results showed that soil DEA was significantly stimulated in the treatments of Hg25 and Hg50 compared with others at day 7.Meanwhile,no difference in the abundances of soil nirS and nosZ was found between Hg spiked treatments and CK,except the lower abundance of nirS(P < 0.05)in the Hg added treatments compared with that in the CK at day 28.The community structures of denitrifiers based on nirS gene presented obvious change at day 7 along with the Hg additions,however,no variation was found in all treatments based on the nosZ gene.The results indicated that Hg(Hg25 and Hg50)had a strongly short-term stimulation on soil DEA,and nirS gene is more sensitive than nosZ gene to Hg stress.

  18. TRIGA low enrichment fuel

    International Nuclear Information System (INIS)

    Sixty TRIGA reactors have been sold and the earliest of these are now passing twenty years of operation. All of these reactors use the uranium-zirconium hydride fuel (UZrH) which provides certain unique advantages arising out of its large prompt negative temperature coefficient, very low fission product release, and high temperature capability. Eleven of these Sixty reactors are conversions from plate fuel to TRIGA fuel which were made as a result of these advantages. With only a few exceptions, TRIGA reactors have always used low-enriched-uranium (LEU) fuel with an enrichment of 19.9%. The exceptions have either been converted from the standard low-enriched fuel to the 70% enriched FLIP fuel in order to achieve extended lifetime, or are higher powered reactors which were designed for long life using 93%-enriched uranium during the time when the use and export of highly enriched uranium (HEU) was not restricted. The advent of international policies focusing attention on nonproliferation and safeguards made the HEU fuels obsolete. General Atomic immediately undertook a development effort (nearly two years ago) in order to be in a position to comply with these policies for all future export sales and also to provide a low-enriched alternative to fully enriched plate-type fuels. This important work was subsequently partially supported by the U.S. Department of Energy. The laboratory and production tests have shown that higher uranium densities can be achieved to compensate for reducing the enrichment to 20%, and that the fuels maintain the characteristics of the very thoroughly proven standard TRIGA fuels. In May of 1978, General Atomic announced that these fuels were available for TRIGA reactors and for plate-type reactors with power levels up to 15 MW with GA's standard commercial warranty

  19. TRIGA low enrichment fuel

    International Nuclear Information System (INIS)

    Sixty TRIGA reactors have been sold and the earliest of these are now passing twenty years of operation. All of these reactors use the uranium zirconium hydride fuel (UZrH) which provides certain unique advantages arising out of its large prompt negative temperature coefficient, very low fission product release, and high temperature capability. Eleven of these Sixty reactors are conversions from plate fuel to TRIGA fuel which were made as a result of these advantages. With only a few exceptions, TRIGA reactors have always used low-enriched uranium (LEU) fuel with an enrichment of 19.9%. The exceptions have either been converted from the standard low-enriched fuel to the 70% enriched FLIP fuel in order to achieve extended lifetime, or are higher powered reactors which were designed for long life using 93%-enriched uranium during the time when the use and export of highly enriched uranium (HEU) was not restricted. The advent of international policies focusing attention on nonproliferation and safeguards made the HEU fuels obsolete. General Atomic immediately undertook a development effort (nearly two years ago) in order to be in a position to comply with these policies for all future export sales and also to provide a low-enriched alternative to fully enriched plate-type fuels. This important work was subsequently partially supported by the U.S. Department of Energy. The laboratory and production tests have shown that higher uranium densities can be achieved to compensate for reducing the enrichment to 20%, and that the fuels maintain the characteristics of the very thoroughly proven standard TRIGA fuels. In May of 1978, General Atomic announced that these fuels were available for TRIGA reactors and for plate-type reactors with power levels up to 15 MW with General Atomic's standard commercial warranty

  20. Drying-Rewetting and Flooding Impact Denitrifier Activity Rather than Community Structure in a Moderately Acidic Fen

    Science.gov (United States)

    Palmer, Katharina; Köpp, Julia; Gebauer, Gerhard; Horn, Marcus A.

    2016-01-01

    Wetlands represent sources or sinks of the greenhouse gas nitrous oxide (N2O). The acidic fen Schlöppnerbrunnen emits denitrification derived N2O and is also capable of N2O consumption. Global warming is predicted to cause more extreme weather events in future years, including prolonged drought periods as well as heavy rainfall events, which may result in flooding. Thus, the effects of prolonged drought and flooding events on the abundance, community composition, and activity of fen denitrifiers were investigated in manipulation experiments. The water table in the fen was experimentally lowered for 8 weeks in 2008 and raised for 5.5 months in 2009 on three treatment plots, while three plots were left untreated and served as controls. In situ N2O fluxes were rather unaffected by the drought treatment and were marginally increased by the flooding treatment. Samples were taken before and after treatment in both years. The structural gene markers narG and nosZ were used to assess possible changes in the nitrate reducer and denitrifier community in response to water table manipulations. Detected copy numbers of narG and nosZ were essentially unaffected by the experimental drought and flooding. Terminal restriction fragment length polymorphism (TRFLP) patterns of narG and nosZ were similar before and after experimental drought or experimental flooding, indicating a stable nitrate reducer and denitrifier community in the fen. However, certain TRFs of narG and nosZ transcripts responded to experimental drought or flooding. Nitrate-dependent Michaelis-Menten kinetics were assessed in anoxic microcosms with peat samples taken before and 6 months after the onset of experimental flooding. Maximal reaction velocities vmax were higher after than before flooding in samples from treament but not in those from control plots taken at the same time. The ratio of N2O to N2O + N2 was lower in soil from treatment plots after flooding than in soil from control plots, suggesting

  1. Nitrite Reductase Genes (nirK and nirS) as Functional Markers To Investigate Diversity of Denitrifying Bacteria in Pacific Northwest Marine Sediment Communities

    OpenAIRE

    Braker, Gesche; Zhou, Jizhong; Wu, Liyou; Devol, Allan H.; Tiedje, James M.

    2000-01-01

    Genetic heterogeneity of denitrifying bacteria in sediment samples from Puget Sound and two sites on the Washington continental margin was studied by PCR approaches amplifying nirK and nirS genes. These structurally different but functionally equivalent single-copy genes coding for nitrite reductases, a key enzyme of the denitrification process, were used as a molecular marker for denitrifying bacteria. nirS sequences could be amplified from samples of both sampling sites, whereas nirK sequen...

  2. 水培条件下几种观赏植物对铅的富集特征%Enrichment Characteristics of Pb by Several Kinds of Ornamental Plants Under Hydroponic Culture

    Institute of Scientific and Technical Information of China (English)

    李翠兰; 邵泽强; 王玉军; 张晋京

    2011-01-01

    通过水培试验,研究了铅处理质量浓度为0~200 mg·L-1条件下,7种观赏植物(包括四季海棠、百日草、茶花凤仙、金鱼草、金盏菊、天竺葵和雁来红)的生长反应和富集特征.结果表明:供试观赏植物在试验的铅胁迫水平下都具有较强的耐性;四季海棠和百日草的地上部最大铅质量分数分别达到了1 229.2、1 209.7 mg·kg-1,满足超富集植物的临界质量分数标准,同时它们在试验铅处理质量浓度下的地上部铅质量分数和富集系数均显著高于其他观赏植物;四季海棠和百日草的铅转移系数最高值可达到0.9以上,并且百日草铅质量浓度在200 mg·L-1时的转移系数仍高于100 mg·L-1时的转移系数.%The growth response and enrichment characteristics of seven ornamental plants, Begonia semperflorens, Zinnia elegan, Impatiens balsamina, Antirrhinum majus, Calendula officinalis, Pelargonium hortorum and Amaranthus tricolo, were studied under hydroponic culture with 0-200 mg · L-1 of Pb. Results showed that all the tested ornamental plants had higher tolerance to Pb in the range of experimental Pb stress levels. The highest Pb mass fractions in the above-ground parts of B. semperflorens and Z. elegan were 1 229.2 and 1 209.7 mg · kg-1, respectively, which reached the critical standard of Pb hyperaccumulating plants. And the Pb mass fraction and bioaccumulation coefficient in the above-ground parts of B. semperflorens and Z. elegan was significantly higher than those of the other five ornamental plants. The highest Pb translocation factors for B. semperflorens and Z. elegan were over 0.9, and the Pb translocation factor for Z. elegan was still higher under 200 mg · L-1 than under 100 mg · L-1 of Pb.

  3. Diversity of Nitrate-Reducing and Denitrifying Bacteria in a Marine Aquaculture Biofilter and their Response to Sulfide

    DEFF Research Database (Denmark)

    Krieger, Bärbel; Schwermer, Carsten U.; Rezakhani, Nastaran;

    2006-01-01

    DIVERSITY OF NITRATE-REDUCING AND DENITRIFYING BACTERIA IN A MARINE AQUACULTURE BIOFILTER AND THEIR RESPONSE TO SULFIDE B.U. Krieger 1,5, C. Schwermer 2, N. Rezakhani 5, M.A. Horn 1, A. Gieseke 2, E. Cytryn 3, D. Minz 3, J. van Rijn 4, H.L. Drake 1, A. Schramm 5 1 Dept. of Ecological Microbiology...... was developed containing a 3-stage biofilter for nitrification, denitrification/anaerobic sludge digestion, and sulfide oxidation. Sulfate reduction in the anaerobic part of the system leads to sulfide concentrations exceeding 5 mM, which may affect nitrate reduction and denitrification. Sulfide can inhibit...... nitrous oxide reductase, trigger a shift from denitrification to dissimilatory nitrate reduction to ammonium (DNRA), or be used as electron donor for nitrate reduction. The goal of this study was to identify and isolate nitrate-reducing and denitrifying bacteria from the biofilter and to investigate...

  4. Study on Short-cut Denitrifying Phosphorus Removal%短程反硝化除磷技术研究

    Institute of Scientific and Technical Information of China (English)

    张少辉; 姜应和

    2011-01-01

    短程反硝化除磷技术适合于对低有机碳高氮磷废水的同步脱氮除磷,其主要影响因素有NO2-、COD及pH等.笔者论述了短程反硝化除磷的理论基础、影响因素及主要工艺,并提出应加强研究的方向.%Short-cut denitrifying phosphorus removal is suitable for simultaneous nitrogen and phosphorus removal from wastewater lacking of organic carbon and rich in nitrogen and phosphorus. The main influencing factors were nitrite, COD, pH and so on. The theory base, effect factors and main process of short-cut denitrifying phosphorus removal were reviewed. Direction for further study was proposed.

  5. Effect of land use on the density of nitrifying and denitrifying bacteria in the colombian coffee region

    OpenAIRE

    Vallejo Quintero, Victoria Eugenia; Gómez, María M.; Cubillos, Ana M.; Roldán, Fabio

    2012-01-01

    Soil microbial communities involved in the cycling of nitrogen (N) are essential to maintaining and improving soil fertility, productivity and functionality of natural and agricultural ecosystems. However, some compounds generated during the metabolic processes performed by nitrifying (NB) and denitrifying (DB) bacteria are associated with the production of greenhouse gases, groundwater pollution and acidification. Therefore, the study of these bacteria is essential for economic and environme...

  6. The Denitrifying Biological Phosphorus Removal Performance in Anaerobic/Anoxic Sequencing Batch Reactor: The Effect of Carbon Source

    OpenAIRE

    Gürtekin, Engin; Nusret ŞEKERDAĞ

    2015-01-01

    In this study, the effect of carbon source on denitrifying biological phosphorus removal performance in acetate and glucose fed two anaerobic/anoxic sequencinq batch reactor (SBR) was investigated. Glucose and acetate were used as the substrates. In acetate and glucose fed reactors, the COD (Chemical Oxygen Demand) removal efficiencies were 91,90% and PO4-P removal efficiencies were 87,51% respectively. These results shows that the phosphorus removal efficiency is lower in glucose fed reactor.

  7. Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

    Science.gov (United States)

    Chen, Gang; Zhang, Shaohui; Li, Meng; Wei, Yan

    2015-01-01

    A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

  8. The incidence of nirS and nirK and their genetic heterogeneity in cultivated denitrifiers.

    Science.gov (United States)

    Heylen, Kim; Gevers, Dirk; Vanparys, Bram; Wittebolle, Lieven; Geets, Joke; Boon, Nico; De Vos, Paul

    2006-11-01

    Gene sequence analysis of nirS and nirK, both encoding nitrite reductases, was performed on cultivated denitrifiers to assess their incidence in different bacterial taxa and their taxonomical value. Almost half of the 227 investigated denitrifying strains did not render an nir amplicon with any of five previously described primers. NirK and nirS were found to be prevalent in Alphaproteobacteria and Betaproteobacteria, respectively, nirK was detected in the Firmicutes and Bacteroidetes and nirS and nirK with equal frequency in the Gammaproteobacteria. These observations deviated from the hitherto reported incidence of nir genes in bacterial taxa. NirS gene phylogeny was congruent with the 16S rRNA gene phylogeny on family or genus level, although some strains did group within clusters of other bacterial classes. Phylogenetic nirK gene sequence analysis was incongruent with the 16S rRNA gene phylogeny. NirK sequences were also found to be significantly more similar to nirK sequences from the same habitat than to nirK sequences retrieved from highly related taxa. This study supports the hypothesis that horizontal gene transfer events of denitrification genes have occurred and underlines that denitrification genes should not be linked with organism diversity of denitrifiers in cultivation-independent studies.

  9. Enrichment: Dealing with overcapacity

    International Nuclear Information System (INIS)

    Today's surplus of enrichment capacity will continue until at least the end of this century. This will challenge the ingenuity of the separative work unit (SWU) suppliers as they attempt to keep market share and remain profitable in a very competitive marketplace. The utilities will be faced with attractive choices, but making the best choice will require careful analysis and increased attention to market factors. Current demand projections will probably prove too high to the extent that more reactors are canceled or delayed. The DOE has the vast majority of the unused capacity, so it will feel the most immediate impact of this large surplus in productive capacity. The DOE has responded to these market challenges by planning another reorganization of its enriching operations. Without a major agreement among the governments affected by the current surplus in enrichment capacity, the future will see lower prices, more competitive terms, and the gradual substitution of centrifuge or laser enrichment for the gaseous diffusion plants. The competition that is forcing the gaseous diffusion prices down to marginal cost will provide the long-term price basis for the enrichment industry

  10. Coexistence of nitrifying, anammox and denitrifying bacteria in a sequencing batch reactor

    Directory of Open Access Journals (Sweden)

    Michela eLangone

    2014-02-01

    Full Text Available Elevated nitrogen removal efficiencies from ammonium-rich wastewaters have been demonstrated by several applications, that combine nitritation and anammox processes. Denitrification will occur simultaneously when organic carbon is also present. In this study, the activity of aerobic ammonia oxidizing, anammox and denitrifying bacteria in a full scale Sequencing Batch Reactor, treating digester supernatants, was studied by means of batch-assays. AOB and anammox activities were maximum at pH of 8.0 and 7.8-8.0, rispectively. Short term effect of nitrite on anammox activity was studied, showing nitrite up to 42 mg/L did not result in inhibition. Both denitrification via nitrate and nitrite were measured. To reduce nitrite-oxidizing activity, high of NH3 – N (1.9-10 mg N-NH3/L and low nitrite (3-8 mg TNN/L are required conditions during the whole SBR cycle.Molecular analysis showed the nitritation-anammox sludge harbored a high microbial diversity, where each microorganism has a specific role. Using ammonia monooxygenase α –subunit (amoA gene as a marker, our analyses suggested different macro- and micro-environments in the reactor strongly affect the AOB community, allowing the development of different AOB species, such as N. europaea/eutropha and N. oligotropha groups, which improve the stability of nitritation process. A specific PCR primer set, used to target the 16S rRNA gene of anammox bacteria, confirmed the presence of the Ca. Brocadia fulgida type, able to grow in precence of organic matter and to tolerate high nitrite concentrations. The diversity of denitrifiers was assessed by using dissimilatory nitrite reductase (nirS gene-based analyses, who showed denitifiers were related to different betaproteobacterial genera, such as Thauera, Pseudomonas, Dechloromonas and Aromatoleum, able to assist in forming microbial aggregates. Concerning possible secondary processes, no n-damo bacteria were found while NOB from the genus of Nitrobacter

  11. Oxygen enrichment incineration

    International Nuclear Information System (INIS)

    Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested

  12. Oxygen enrichment incineration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung

    2000-10-01

    Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested.

  13. Laser and gas centrifuge enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Heinonen, Olli [Senior Fellow, Belfer Center for Science and International Affairs, Harvard Kennedy School, Cambridge, Massachusetts (United States)

    2014-05-09

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  14. Laser and gas centrifuge enrichment

    Science.gov (United States)

    Heinonen, Olli

    2014-05-01

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  15. Segal Enriched Categories I

    CERN Document Server

    Bacard, Hugo V

    2010-01-01

    We develop a theory of enriched categories over a (higher) category M equipped with a class W of morphisms called homotopy equivalences. We call them Segal M_W -categories. Our motivation was to generalize the notion of "up-to-homotopy monoids" in a monoidal category M, introduced by Leinster. The formalism adopted generalizes the classical Segal categories and extends the theory of enriched category over a bicategory. In particular we have a linear version of Segal categories which did not exist so far. Our goal in this paper is to present the theory and provide some examples. Applications are reserved for the future.

  16. Advanced uranium enrichment processes

    International Nuclear Information System (INIS)

    Three advanced Uranium enrichment processes are dealt with in the report: AVLIS (Atomic Vapour LASER Isotope Separation), MLIS (Molecular LASER Isotope Separation) and PSP (Plasma Separation Process). The description of the physical and technical features of the processes constitutes a major part of the report. If further presents comparisons with existing industrially used enrichment technologies, gives information on actual development programmes and budgets and ends with a chapter on perspectives and conclusions. An extensive bibliography of the relevant open literature is added to the different subjects discussed. The report was drawn up by the nuclear research Centre (CEA) Saclay on behalf of the Commission of the European Communities

  17. Bacterial community succession during the enrichment of chemolithoautotrophic arsenite oxidizing bacteria at high arsenic concentrations

    Institute of Scientific and Technical Information of China (English)

    Nguyen Ai Le; Akiko Sato; Daisuke Inoue; Kazunari Sei; Satoshi Soda; Michihiko Ike

    2012-01-01

    To generate cost-effective technologies for the removal of arsenic from water,we developed an enrichment culture of chemolithoautotrophic arsenite oxidizing bacteria (CAOs) that could effectively oxidize widely ranging concentrations of As(Ⅲ) to As(Ⅴ).In addition,we attempted to elucidate the enrichment process and characterize the microbial composition of the enrichment culture.A CAOs enrichment culture capable of stably oxidizing As(Ⅲ) to As(Ⅴ) was successfully constructed through repeated batch cultivation for more than 700 days,during which time the initial As(Ⅲ) concentrations were increased in a stepwise manner from l to 10-12 mmol/L.As(Ⅲ) oxidation activity of the enrichment culture gradually improved,and 10-12 mmol/L As(Ⅲ) was almost completely oxidized within four days.Terminal restriction fragment length polymorphism analysis showed that the dominant bacteria in the enrichment culture varied drastically during the enrichment process depending on the As(Ⅲ) concentration.Isolation and characterization of bacteria in the enrichment culture revealed that the presence of multiple CAOs with various As(Ⅲ) oxidation abilities enabled the culture to adapt to a wide range of As(Ⅲ) concentrations.The CAOs enrichment culture constructed here may he useful for pretreatment of water from which arsenic is being removed.

  18. Denitrification activity of a remarkably diverse fen denitrifier community in finnish lapland is N-oxide limited.

    Science.gov (United States)

    Palmer, Katharina; Horn, Marcus A

    2015-01-01

    Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anoxic microcosms, fen soil produced N2O only when acetylene was added to block nitrous oxide reductase, suggesting complete denitrification. Nitrate and nitrite stimulated denitrification in fen soil, and maximal reaction velocities (vmax) of nitrate or nitrite dependent denitrification where 18 and 52 nmol N2O h-1 gDW-1, respectively. N2O was below 30% of total produced N gases in fen soil when concentrations of nitrate and nitrite were N2O consumption was up to 36 nmol N2O h-1 gDW-1. Denitrifier diversity was assessed by analyses of narG, nirK/nirS, and nosZ (encoding nitrate-, nitrite-, and nitrous oxide reductases, respectively) by barcoded amplicon pyrosequencing. Analyses of ~14,000 quality filtered sequences indicated up to 25 species-level operational taxonomic units (OTUs), and up to 359 OTUs at 97% sequence similarity, suggesting diverse denitrifiers. Phylogenetic analyses revealed clusters distantly related to publicly available sequences, suggesting hitherto unknown denitrifiers. Representatives of species-level OTUs were affiliated with sequences of unknown soil bacteria and Actinobacterial, Alpha-, Beta-, Gamma-, and Delta-Proteobacterial sequences. Comparison of the 4 gene markers at 97% similarity indicated a higher diversity of narG than for the other gene markers based on Shannon indices and observed number of OTUs. The collective data indicate (i) a high denitrification and N2O consumption potential, and (ii) a highly diverse, nitrate limited denitrifier

  19. Denitrification activity of a remarkably diverse fen denitrifier community in finnish lapland is N-oxide limited.

    Directory of Open Access Journals (Sweden)

    Katharina Palmer

    Full Text Available Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anoxic microcosms, fen soil produced N2O only when acetylene was added to block nitrous oxide reductase, suggesting complete denitrification. Nitrate and nitrite stimulated denitrification in fen soil, and maximal reaction velocities (vmax of nitrate or nitrite dependent denitrification where 18 and 52 nmol N2O h-1 gDW-1, respectively. N2O was below 30% of total produced N gases in fen soil when concentrations of nitrate and nitrite were <500 μM. vmax for N2O consumption was up to 36 nmol N2O h-1 gDW-1. Denitrifier diversity was assessed by analyses of narG, nirK/nirS, and nosZ (encoding nitrate-, nitrite-, and nitrous oxide reductases, respectively by barcoded amplicon pyrosequencing. Analyses of ~14,000 quality filtered sequences indicated up to 25 species-level operational taxonomic units (OTUs, and up to 359 OTUs at 97% sequence similarity, suggesting diverse denitrifiers. Phylogenetic analyses revealed clusters distantly related to publicly available sequences, suggesting hitherto unknown denitrifiers. Representatives of species-level OTUs were affiliated with sequences of unknown soil bacteria and Actinobacterial, Alpha-, Beta-, Gamma-, and Delta-Proteobacterial sequences. Comparison of the 4 gene markers at 97% similarity indicated a higher diversity of narG than for the other gene markers based on Shannon indices and observed number of OTUs. The collective data indicate (i a high denitrification and N2O consumption potential, and (ii a highly diverse

  20. Proton translocation during denitrification by a nitrifying--denitrifying Alcaligenes sp.

    Science.gov (United States)

    Castignetti, D; Hollocher, T C

    1983-04-01

    A heterotrophic nitrifying Alcaligenes sp. from soil was grown as a denitrifier on nitrate and subjected to oxidant pulse experiments to ascertain the apparent efficiencies of proton translocations during O2 and nitrogen-oxide respirations. With endogenous substrate as the reducing agent the leads to H+/2e- ratios, extrapolated to zero amount of oxidant per pulse, were 9.4, 3.7, 4.3 and 3.5 for O2, nitrate, nitrite and N2O, respectively. The value for O2 and those for the N-oxides are, respectively, somewhat larger and smaller than corresponding values for Paracoccus denitrificans. None of the three permeant ions employed with the Alcaligenes sp. (valinomycin-K+, thiocyanate and triphenylmethylphosphonium) was ideal for all purposes. Thiocyanate provided highest ratios for O2 but abolished the oxidant pulse response for nitrate and N2O. Valinomycin was slow to penetrate to the cytoplasmic membrane and relatively high concentrations were required for optimal performance. Triphenylmethylphosphonium enhanced passive proton permeability and diminished proton translocation at concentrations required to realize the maximal oxidant pulse response. PMID:6311094

  1. Correlating denitrifying catabolic genes with N2O and N2 emissions from swine slurry composting.

    Science.gov (United States)

    Angnes, G; Nicoloso, R S; da Silva, M L B; de Oliveira, P A V; Higarashi, M M; Mezzari, M P; Miller, P R M

    2013-07-01

    This work evaluated N dynamics that occurs over time within swine slurry composting piles. Real-time quantitative PCR (qPCR) analyzes were conducted to estimate concentrations of bacteria community harboring specific catabolic nitrifying-ammonium monooxygenase (amoA), and denitrifying nitrate- (narG), nitrite- (nirS and nirG), nitric oxide- (norB) and nitrous oxide reductases (nosZ) genes. NH3-N, N2O-N, N2-N emissions represented 15.4 ± 1.9%, 5.4 ± 0.9%, and 79.1 ± 2.0% of the total nitrogen losses, respectively. Among the genes tested, temporal distribution of narG, nirS, and nosZ concentration correlated significantly (pcompost pile. Considering our current empirical limitations to accurately measure N2 emissions from swine slurry composting at field scale the use of these catabolic genes could represent a promising monitoring tool to aid minimize our uncertainties on biological N mass balances in these systems.

  2. Simultaneous Nitrogen and Phosphorus Removal by Denitrifying Dephosphatation in a (AO)2 Sequencing Batch Reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan-ping; PENG Yong-zhen; WANG Shu-ying; WANG Shao-po

    2005-01-01

    A 24 L working volume reactor was used for the research on simultaneous phosphorus (P) and nitrogen (N) removal by denitrifying dephosphatation in an anaerobic-oxid-anoxic-oxid sequencing batch reactor ((AO)2SBR) system. The durations of each phase are: anaerobic 1.5 h, aerobic 2.5 h, anoxic 1.5 h, post-aerobic 0.5 h, settling 1.0 h, fill 0.5 h. The successful removal of nitrogen and phosphorus is achieved in a stable (AO)2SBR. The effluent P concentrations is below 1 mg/L, and the COD,TN and P average removal efficiency is 88.9%, 77.5% and 88.7%, respectively. The batch experiment results show that the durations of aerobic and anoxic phase influence the P removal efficiency. Some feature points are found on the DO, ORP and pH curves to demonstrate the complete of phosphate release and phosphate uptake. These feature points can be used for the control of (AO)2 SBR.

  3. Characteristics of a Novel Aerobic Denitrifying Bacterium, Enterobacter cloacae Strain HNR.

    Science.gov (United States)

    Guo, Long-Jie; Zhao, Bin; An, Qiang; Tian, Meng

    2016-03-01

    A novel aerobic denitrifier strain HNR, isolated from activated sludge, was identified as Enterobacter cloacae by16S rRNA sequencing analysis. Glucose was considered as the most favorable C-source for strain HNR. The logistic equation well described the bacterial growth, yielding a maximum growth rate (μmax) of 0.283 h(-1) with an initial NO3 (-)-N concentration of 110 mg/L. Almost all NO3 (-)-N was removed aerobically within 30 h with an average removal rate of 4.58 mg N L(-1) h(-1). Nitrogen balance analysis revealed that proximately 70.8 % of NO3 (-)-N was removed as gas products and only 20.7 % was transformed into biomass. GC-MS result indicates that N2 was the end product of aerobic denitrification. The enzyme activities of nitrate reductase and nitrite reductase, which are related to the process of aerobic denitrification, were 0.0688 and 0.0054 U/mg protein, respectively. Thus, the aerobic denitrification of reducing NO3 (-) to N2 by strain HNR was demonstrated. The optimal conditions for nitrate removal were C/N ratio 13, pH value 8, shaking speed 127 rpm and temperature 30 °C. These findings show that E. cloacae strain HNR has a potential application on wastewater treatment to achieve nitrate removal under aerobic conditions.

  4. Designing job enrichment projects.

    Science.gov (United States)

    Clakeley, G L

    1988-01-01

    This paper describes a management strategy for a job satisfaction program utilized in a large occupational therapy department. The goal of the program is to retain satisfied, productive employees and reduce attrition of therapists and assistants. The use of job enrichment projects for occupational therapy assistants will be presented with brief descriptions of two projects. PMID:23944880

  5. Job Enrichment in Extension.

    Science.gov (United States)

    Fourman, Louis S.; Jones, Jo

    1997-01-01

    Interviews with 10 participants in Ohio State University's job enrichment program for midcareer extension agents found that 5 returned to their same jobs after the experience but only 2 felt challenged/renewed. Part-time participation while working made it difficult to balance responsibilities. More information and a structured orientation were…

  6. Enriching the Catalog

    Science.gov (United States)

    Tennant, Roy

    2004-01-01

    After decades of costly and time-consuming effort, nearly all libraries have completed the retrospective conversion of their card catalogs to electronic form. However, bibliographic systems still are really not much more than card catalogs on wheels. Enriched content that Amazon.com takes for granted--such as digitized tables of contents, cover…

  7. Methodology for content enrichment

    NARCIS (Netherlands)

    Nederbragt, H.; Heerlien, M.

    2010-01-01

    The STERNA project mainly focuses on enrichment of existing content of content holding organisations in the natural history domain. Therefore, developing a methodology on how to best integrate one’s content into the STERNA information space is an essential part of the project. This document is the o

  8. Enrichment of Methane-Utilizing Mixed Culture with a High Polyβ-Hydroxybutyrat Content in an Open System%开放条件下高聚3-羟基丁酸酯含量的甲烷氧化混合茵群的富集

    Institute of Scientific and Technical Information of China (English)

    姜丹; 董静; 辛嘉英; 张莹莹; 张颖鑫; 夏春谷

    2011-01-01

    Objective: To enrich a methane-utilizing mixed culture with a high poly-p-hydroxybutyrate (PHB) content using methane as substrate in an open system, then obtain microbial species of high PHB content at low carbon cost. Methods: The method of feast-famine aerobic dynamic feeding was used to cultivate methane-utilizing mixed culture using methane as substrate in an open system, and the effect of feast-famine ratio on enriching mixed culture with a high PHB content was studied based on sudan black staining. Results: The PHB content in biomass increased from 17.7% to 35.5% when the feast-famine ratio was 1:3, and the structure of mixed culture was stable in an open system. Conclusion: Methane-Utilizing mixed culture enriched by the method of feast-famine aerobic dynamic feeding has the application value for commercial PHB production.%目的:在开放条件下以甲烷为底物富集高聚β-羟基丁酸酯(PHB)含量的甲烷氧化菌群,获得能够利用低成本碳源高产PHB的菌种.方法:采用丰盛-饥饿模式间歇供料,以甲烷为底物,好氧开放式培养甲烷氧化混合菌群,利用苏丹黑染色法动态检测丰盛和饥饿阶段胞内PHB含量的变化,以此为基础考察丰盛-饥饿期比例对富集高PHB含量的甲烷氧化菌群的影响.结果:丰盛-饥饿期比例为1:3时,微生物PHB含量从17.7%增加到35.5%,且开放培养过程中菌群结构稳定.结论:通过丰盛-饥饿模式间歇供料开放式培养所得的高PHB含量的稳定的甲烷氧化菌群,具有工业生产PHB的应用价值.

  9. Enrichment marketplace - today (and tomorrow)

    International Nuclear Information System (INIS)

    The technologies and capacities of the four primary sources of enrichment services, the United States Department of Energy, Eurodif, Techsnabexport of the Soviet Union, and Urenco, were given. Forecasts of future capacities and prices of enriched uranium were also included

  10. The role of paraffin oil on the interaction between denitrifying anaerobic methane oxidation and Anammox processes.

    Science.gov (United States)

    Fu, Liang; Ding, Zhao-Wei; Ding, Jing; Zhang, Fang; Zeng, Raymond J

    2015-10-01

    Methane is sparingly soluble in water, resulting in a slow reaction rate in the denitrifying anaerobic methane oxidation (DAMO) process. The slow rate limits the feasibility of research to examine the interaction between the DAMO and the anaerobic ammonium oxidation (Anammox) process. In this study, optimized 5 % (v/v) paraffin oil was added as a second liquid phase to improve methane solubility in a reactor containing DAMO and Anammox microbes. After just addition, methane solubility was found to increase by 25 % and DAMO activity was enhanced. After a 100-day cultivation, the paraffin reactor showed almost two times higher consumption rates of NO3 (-) (0.2268 mmol/day) and NH4 (+) (0.1403 mmol/day), compared to the control reactor without paraffin oil. The microbes tended to distribute in the oil-water interface. The quantitative (q) PCR result showed the abundance of gene copies of DAMO archaea, DAMO bacteria, and Anammox bacteria in the paraffin reactor were higher than those in the control reactor after 1 month. Fluorescence in situ hybridization revealed that the percentages of the three microbes were 55.5 and 77.6 % in the control and paraffin reactors after 100 days, respectively. A simple model of mass balance was developed to describe the interactions between DAMO and Anammox microbes and validate the activity results. A mechanism was proposed to describe the possible way that paraffin oil enhanced DAMO activity. It is quite clear that paraffin oil enhances not only DAMO activity but also Anammox activity via the interaction between them; both NO3 (-) and NH4 (+) consumption rates were about two times those of the control.

  11. Characterization of Two Efficient Aerobic Denitrifying Strains Isolated from Shallow Aquifers in Suzhou City, China

    Science.gov (United States)

    Ruan, X.; Zhu, X.; Sun, H.; Li, M.

    2010-12-01

    Sixty two stains that can utilize nitrate as source of nitrogen under aerobic conditions were isolated from shallow aquifer samples in Suzhou city, China. Two of the strains, XK42 and PJ21, can convert nitrate into nitrogen gas efficiently without obvious accumulation of nitite. According to morphological, biochemical/biophysical and 16S rDNA gene sequence analysis, XK42 and PJ21 were identified as Pseudomonas Stutzeri and Pseudomonas Mendocica, respectively. The generation time, optimum pH value range and optimum growth temperature range were 4.64h, 6.5˜8.0, 25˜35°C for XK42 and 8.39h, 6.5˜8.5, 25˜35°C for PJ21. Under aerobic conditions (DO=6.9˜7.8 mg/L), the nitrate concentrations in the medium inoculated with XK42 and PJ21 decreased to 42.35 mg/L and 35.69 mg/L with initial nitrate concentration of 276.25 mg/L within 12 hours, respectively. The nitrite concentrations reached to 3.06 mg/L and 3.70 mg/L, and their nitrate removal rates reached 18.24 mg/L●h and 17.51 mg/L●h. The total nitrogen loss through denitrification of XK42 and PJ21 were 70.9% and 66.3%, respectively. The nitrate reduction efficiencies within 60 hours was up to 95.13% (strain XK42) and 95.55% (strain PJ21). The results indicate that the isolated strians XK42 and PJ21 are aerobic denitrifiers with high nitrogen removal efficiency, and can be used for in-situ bioremediation of nitrogen-contaminated shallow groundwater and biotreatment of wasterwater.

  12. Tertiary Denitrification of the Secondary Effluent by Denitrifying Biofilters Packed with Different Sizes of Quartz Sand

    Directory of Open Access Journals (Sweden)

    Nan Wei

    2014-05-01

    Full Text Available Tertiary denitrification of the secondary effluent in wastewater treatment plants is necessary to control the eutrophication of receiving water bodies. Two denitrifying biofilters (DNBF, one packed with quart sand with sizes of 2–4 mm (DNBFS and the other of 4–6 mm (DNBFL, were operated for tertiary denitrification under empty bed retention times (EBRTs of 30 min, 15 min and 7.5 min, respectively. Under EBRTs of 30 min, 15 min and 7.5 min, the NO3−-N removal percentages were 93%, 82% and 83% in DNBFS, and were 92%, 68% and 36% in DNBFL, respectively. The nitrogen removal loading rates increased with decreasing EBRTs, and at the EBRT of 7.5 min, the rate was 2.15 kg/(m3·d in DNBFS and 1.08 kg/(m3·d in DNBFL. The half-order denitrification coefficient of DNBFS increased from 0.42 (mg/L1/2/min at the EBRT of 30 min to 0.70 (mg/L1/2/min at the EBRT of 7.5 min, while did not vary much in DNBFL with values from 0.22 to 0.25 (mg/L1/2/min. The performance of both DNBFs was stable within each backwashing cycle, with the NO3−-N removal percentage variation within 5%. Better denitrification was achieved in DNBFS but with a slightly high decreased flow rate during the operation.

  13. Denitrifying and diazotrophic community responses to artificial warming in permafrost and tallgrass prairie soils

    Directory of Open Access Journals (Sweden)

    Christopher Ryan Penton

    2015-07-01

    Full Text Available Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH, and denitrifying (nirS, nirK, nosZ soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass prairie in Oklahoma (OK and the active layer above permafrost in Alaska (AK. Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH to 862 (NirK. The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only one year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations

  14. Optimizing Hydraulic Retention Times in Denitrifying Woodchip Bioreactors Treating Recirculating Aquaculture System Wastewater.

    Science.gov (United States)

    Lepine, Christine; Christianson, Laura; Sharrer, Kata; Summerfelt, Steven

    2016-05-01

    The performance of wood-based denitrifying bioreactors to treat high-nitrate wastewaters from aquaculture systems has not previously been demonstrated. Four pilot-scale woodchip bioreactors (approximately 1:10 scale) were constructed and operated for 268 d to determine the optimal range of design hydraulic retention times (HRTs) for nitrate removal. The bioreactors were operated under HRTs ranging from 6.6 to 55 h with influent nitrate concentrations generally between 20 and 80 mg NO-N L. These combinations resulted in N removal rates >39 g N m d, which is greater than previously reported. These high removal rates were due in large part to the relatively high chemical oxygen demand and warm temperature (∼19°C) of the wastewater. An optimized design HRT may not be the same based on metrics of N removal rate versus N removal efficiency; longer HRTs demonstrated higher removal efficiencies, and shorter HRTs had higher removal rates. When nitrate influent concentrations were approximately 75 mg NO-N L ( = 6 sample events), the shortest HRT (12 h) had the lowest removal efficiency (45%) but a significantly greater removal rate than the two longest HRTs (42 and 55 h), which were N limited. Sulfate reduction was also observed under highly reduced conditions and was exacerbated under prolonged N-limited environments. Balancing the removal rate and removal efficiency for this water chemistry with a design HRT of approximately 24 h would result in a 65% removal efficiency and removal rates of at least 18 g N m d. PMID:27136146

  15. Effect of Biochar on Nitrate Removal in a Pilot-Scale Denitrifying Bioreactor.

    Science.gov (United States)

    Bock, Emily M; Coleman, Brady; Easton, Zachary M

    2016-05-01

    Denitrifying bioreactors (DNBRs) harness the natural capacity of microorganisms to convert bioavailable nitrogen (N) into inert nitrogen gas (N) by providing a suitable anaerobic habitat and an organic carbon energy source. Woodchip systems are reported to remove 2 to 22 g N m d, but the potential to enhance denitrification with alternative substrates holds promise. The objective of this study was to determine the effect of adding biochar, an organic carbon pyrolysis product, to an in-field, pilot-scale woodchip DNBR. Two 25-m DNBRs, one with woodchips and the other with woodchips and a 10% by volume addition of biochar, were installed on the Delmarva Peninsula, Virginia. Performance was assessed using flood-and-drain batch experiments. An initial release of N was observed during the establishment of both DNBRs, reflecting a start-up phenomenon observed in previous studies. Nitrate (NO-N) removal rates observed during nine batch experiments 4 to 22 mo after installation were 0.25 to 6.06 g N m d. The presence of biochar, temperature, and influent NO-N concentration were found to have significant effects on NO-N removal rates using a linear mixed effects model. The model predicts that biochar increases the rate of N removal when influent concentrations are above approximately 5 to 10 mg L NO-N but that woodchip DNBRs outperform biochar-amended DNBRs when influent concentrations are lower, possibly reflecting the release of N temporarily stored in the biochar matrix. These results indicate that in high N-yielding systems the addition of biochar to standard woodchip DNBRs has the potential to significantly increase N removal. PMID:27136140

  16. Structure of a new azurin from the denitrifying bacterium Alcaligenes xylosoxidans at high resolution.

    Science.gov (United States)

    Dodd, F E; Hasnain, S S; Abraham, Z H; Eady, R R; Smith, B E

    1995-11-01

    It has been reported previously that Alcaligenes xylosoxidans (NC1MB 11015) grown under denitrifying conditions produces two azurins instead of the single previously identified azurin [Dodd, Hasnain, Hunter, Abraham, Debenham, Kanzler, Eldridge, Eady, Ambler & Smith (1995). Biochemistry. In the press]. The new azurin, called azurin II, has been crystallized as blue elongated rectangular prisms with the tetragonal space group P4(1)22 and unit-cell parameters a = b = 52.65, c = 100.63 A. X-ray crystallographic data extending to 1.9 A resolution were collected by the Weissenberg method using 200 x 400 mm image plates and synchrotron X-rays of wavelength 0.97 A. The three-dimensional structure of azurin II has been solved by the molecular-replacement method using the structure of azurin from Alcaligenes denitrificans NCTC 8582 with which this new azurin shows a close homology. The quality of the initial map was sufficient to predict a number of sequence differences. The model is currently refined to an R-factor of 18.8% with X-ray data between 8.5 and 1.9 A. The final model of 961 protein atoms, one Cu atom and 50 water molecules has r.m.s. deviations from ideality of 0.009 A for bond lengths and 1.7 degrees for bond angles. The overall structure is similar to that of the azurin from A. denitrificans NCTC 8582. It has a beta-barrel structure with the Cu atom located near the top end of the molecule. The Cu atom is coordinated to Ndelta of His46 and His117 at 2.02 A and to Sgamma of Cys112 at 2.12 A, while the carbonyl O atom of Gly45 and Sdelta atom of Met121 provide the additional interactions at 2.75 and 3.26 A, respectively.

  17. [Distribution Characteristics of Nitrifiers and Denitrifiers in the River Sediments of Tongling City].

    Science.gov (United States)

    Cheng, Jian-hua; Dou, Zhi-yong; Sun, Qing-ye

    2016-04-15

    Rivers in mining areas were influenced by contaminants such as nitrogen, phosphorus and organic matter due to domestic and agricultural wastewater discharge in addition to pollutants caused by mining activities. In this study, surface sediment samples of rivers in Tongling city were collected to address the effect of season and pollution type on the abundance of nitrifiers and denitrifiers using quantitative polymerase chain reaction (QPCR) technique targeting at the ammonia monooxygenase (amoA) and nitrite reductase (nir) genes. The results showed that the average ahundance of ammonia oxidizing archaea (AGA) (ranging from 1.74 x 10⁵ to 1.45 x 10⁸ copies · g⁻¹) was 4.39 times that of ammonia oxidizing hacteria (AGH) (ranging from 1.39 x 10⁵ to 3.39 x 10⁷ copies · g⁻¹); and the average abundance of nirK gene (ranging from 4.45 x 10⁶ to 1.51 x 10⁸ copies · g) was almost a thirtieth part of nirS gene (ranging from 1.69 x 10⁷ to 8.55 x 10⁹ copies · g⁻¹). The abundance of AOA was higher in spring and autumn, and lower in summer and winter. And sediment AOB abundance was higher in spring and winter than in summer and autumn. Meanwhile, the abundance of nir genes was in the order of spring (nirS )/autumn (nirK) > summer > winter > autumn (nirS )/spring (nirK). Moreover, the abundance of bacterial and archaeal arnoA and nirS genes in sediments influenced by mine pollution was generally higher than that in sediments influenced by agricultural non-point pollution, whereas the abundance of nirK gene showed an opposite trend. PMID:27548957

  18. Biodegradation of p-cresol and sulfide removal by a marine-denitrifying consortium.

    Science.gov (United States)

    Meza-Escalante, Edna R; Alvarez, Luis H; Serrano, Denisse; Mendoza, Erika; Bonola, Ramsés

    2015-02-01

    The simultaneous removal of sulfide and p-cresol was carried out by using a marine-denitrifying consortium collected in the coastal zone of Sonora, Mexico. Different experimental conditions were used to evaluate the capacity of the consortium to simultaneously eliminate nitrate, sulfide, and p-cresol. For instance, the first set of assays was conducted at different sulfide concentrations (20, 50, and 100 mg S(2À) L(À1) ), with a fixed concentration of p-cresol (45 mg C L(À1) ). The second set of assays was developed at different concentrations of p-cresol (45, 75, and 100 mg C L(-1) ), in the presence of 20 mg S(2À) L(À1) . In all cases, the concentration of nitrate was stoichiometrically added for the complete oxidization of the substrates. The results showed removal efficiencies up to 92% for p-cresol and nitrate at 20 and 50 mg S(2À) L(À1) ; whereas at 100 mg S(2À) L(À1) removal efficiencies were 77% and 59% for p-cresol and nitrate, respectively. On the other hand, sulfide (20 mg L(À1) ) was completely removed under different concentrations of p-cresol tested, with a partial accumulation of nitrite according to the increment of p-cresol concentration. The results obtained indicate that the marine consortium was able to simultaneously remove the pollutants studied. PMID:25418931

  19. Decaying cyanobacteria decrease N2O emissions related to diversity of intestinal denitrifiers of Chironomus plumosus

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2014-10-01

    Full Text Available Nitrous oxide (N2O emission of fresh invertebrates has too long been neglected in eutrophic lakes, although the sediments these animals inhabit are presumably hot spots of N2O emission. Thus, the experiment in this research was designed to gain insight into the influence of cyanobacterial degradation on the N2O emission by fresh water invertebrates (Chironomus plumosus. The presence of decaying cyanobacteria in Lake Taihu decreased the N2O emission rate of Chironomus plumosus larvae from the larvae body by almost 400% for the larvae as a whole. The N2O emission rate decreased by 350% based on readings from studies of their gut, which was mostly due to stimulation of intestinal complete denitrification. The quantitative PCR results showed that intestinal gene abundance of nirK, nosZ (encoding the copper nitrite reductase and N2O reductase, respectively were significantly increased with the presence of decaying cyanobacteria. In contrast nirS (encoding the cytochrome cd1 heme nitrite reductase and the total bacteria decreased. In the gut of Chironomus plumosus, the diversity and richness of nosZ and nirK were lower with the cyanobacteria. Phylogenetic analysis of the intestinal function genes (nosZ and nirK showed that the nosZ- and nirK-type denitrifying bacterial sequences were related to different phylotypes. Hence, additional cyanobacteria increased the abundance, but decreased the richness and diversity of intestinal nitrate-reducing bacteria, probably by providing more carbon source in the gut. The data obtained in this study elucidates that the decaying cyanobacteria decreased the emissions of N2O by the aquatic invertebrates in freshwater sediment and could serve as a valuable resource for nitrogen removal affecting greenhouse gas emissions.

  20. Ecology of Nitrogen Fixing, Nitrifying, and Denitrifying Microorganisms in Tropical Forest Soils.

    Science.gov (United States)

    Pajares, Silvia; Bohannan, Brendan J M

    2016-01-01

    Soil microorganisms play important roles in nitrogen cycling within forest ecosystems. Current research has revealed that a wider variety of microorganisms, with unexpected diversity in their functions and phylogenies, are involved in the nitrogen cycle than previously thought, including nitrogen-fixing bacteria, ammonia-oxidizing bacteria and archaea, heterotrophic nitrifying microorganisms, and anammox bacteria, as well as denitrifying bacteria, archaea, and fungi. However, the vast majority of this research has been focused in temperate regions, and relatively little is known regarding the ecology of nitrogen-cycling microorganisms within tropical and subtropical ecosystems. Tropical forests are characterized by relatively high precipitation, low annual temperature fluctuation, high heterogeneity in plant diversity, large amounts of plant litter, and unique soil chemistry. For these reasons, regulation of the nitrogen cycle in tropical forests may be very different from that of temperate ecosystems. This is of great importance because of growing concerns regarding the effect of land use change and chronic-elevated nitrogen deposition on nitrogen-cycling processes in tropical forests. In the context of global change, it is crucial to understand how environmental factors and land use changes in tropical ecosystems influence the composition, abundance and activity of key players in the nitrogen cycle. In this review, we synthesize the limited currently available information regarding the microbial communities involved in nitrogen fixation, nitrification and denitrification, to provide deeper insight into the mechanisms regulating nitrogen cycling in tropical forest ecosystems. We also highlight the large gaps in our understanding of microbially mediated nitrogen processes in tropical forest soils and identify important areas for future research. PMID:27468277

  1. Ecology of Nitrogen Fixing, Nitrifying, and Denitrifying Microorganisms in Tropical Forest Soils

    Science.gov (United States)

    Pajares, Silvia; Bohannan, Brendan J. M.

    2016-01-01

    Soil microorganisms play important roles in nitrogen cycling within forest ecosystems. Current research has revealed that a wider variety of microorganisms, with unexpected diversity in their functions and phylogenies, are involved in the nitrogen cycle than previously thought, including nitrogen-fixing bacteria, ammonia-oxidizing bacteria and archaea, heterotrophic nitrifying microorganisms, and anammox bacteria, as well as denitrifying bacteria, archaea, and fungi. However, the vast majority of this research has been focused in temperate regions, and relatively little is known regarding the ecology of nitrogen-cycling microorganisms within tropical and subtropical ecosystems. Tropical forests are characterized by relatively high precipitation, low annual temperature fluctuation, high heterogeneity in plant diversity, large amounts of plant litter, and unique soil chemistry. For these reasons, regulation of the nitrogen cycle in tropical forests may be very different from that of temperate ecosystems. This is of great importance because of growing concerns regarding the effect of land use change and chronic-elevated nitrogen deposition on nitrogen-cycling processes in tropical forests. In the context of global change, it is crucial to understand how environmental factors and land use changes in tropical ecosystems influence the composition, abundance and activity of key players in the nitrogen cycle. In this review, we synthesize the limited currently available information regarding the microbial communities involved in nitrogen fixation, nitrification and denitrification, to provide deeper insight into the mechanisms regulating nitrogen cycling in tropical forest ecosystems. We also highlight the large gaps in our understanding of microbially mediated nitrogen processes in tropical forest soils and identify important areas for future research. PMID:27468277

  2. Simultaneous electricity generation and pollutant removal in microbial fuel cell with denitrifying biocathode over nitrite

    International Nuclear Information System (INIS)

    Highlights: • An MFC was successfully started up using nitrite as cathodic electron acceptor. • The optimal HRT was deemed to be 8 h in this study. • The suitable temperature for power generation was found to be 20 °C. • The suitable temperature for pollutant removal was found to be 25 °C. • Free buffer led to 50% decrease of TN removal rate and power generation. - Abstract: The influences of hydraulic retention time, temperature and free buffer on the performance of short-cut denitrifying microbial fuel cell were investigated after it was successfully started up using nitrite as the cathodic electron acceptor. The results revealed that a power density of 8.3 ± 0.5 W m−3 NC was obtained after 15 days operation. The desirable hydraulic retention time was found in this study to be 8 h, with a COD removal rate of 2.117 ± 0.006 kg m−3 NC d−1 and a total nitrogen removal rate of 0.041 ± 0.002 kg m−3 NC d−1, respectively. It demonstrated that temperature had different effects on the electricity generation and pollutant removal performance of microbial fuel cell. The suitable temperature for power generation and pollutant removal was found to be 20 °C and 25 °C, respectively. Free buffer led to 50% decrease of both total nitrogen removal rate and power density of microbial fuel cell compared to that with phosphate buffer solution addition. The optimal total nitrogen removal rate obtained in the case with sodium azide addition (0.075 ± 0.008 kg m−3 NC d−1) increased by 50% as compared to that without sodium azide addition. It suggested that abolishing oxygen or inhibiting nitrite oxidizing bacteria would favor nitrogen removal

  3. Discussion on the Affecting Factors in the Process of Denitrifying Phosphorus Removal%反硝化除磷过程中影响因素的探讨

    Institute of Scientific and Technical Information of China (English)

    张硕峰; 侯毛宇; 陈文松

    2012-01-01

    介绍了反硝化除磷的机理和影响因素;讨论和分析了污泥龄、NO3、NO2、溶解氧和氧化还原电位、碳源、温度、MUSS、pH等对反硝化除磷效果的影响,指出反硝化除磷工艺是适合可持续发展的绿色工艺。%The mechanism and influence factors of denitrifying phosphorus removal were introduced in this paper. The influencing factors for the effect of denitrifying phosphorus removal such as sludge age, NO3- and NO2-concentration, dissolved oxygen, redox potential, carbon source, temperature, MISS and pH etc. were discussed and analyzed and that denitrifying phosphorus removal technology is the green technology fitting for sustainable development was pointed out.

  4. Abundance, composition and activity of ammonia oxidizer and denitrifier communities in metal polluted rice paddies from South China.

    Directory of Open Access Journals (Sweden)

    Yuan Liu

    Full Text Available While microbial nitrogen transformations in soils had been known to be affected by heavy metal pollution, changes in abundance and community structure of the mediating microbial populations had been not yet well characterized in polluted rice soils. Here, by using the prevailing molecular fingerprinting and enzyme activity assays and comparisons to adjacent non-polluted soils, we examined changes in the abundance and activity of ammonia oxidizing and denitrifying communities of rice paddies in two sites with different metal accumulation situation under long-term pollution from metal mining and smelter activities. Potential nitrifying activity was significantly reduced in polluted paddies in both sites while potential denitrifying activity reduced only in the soils with high Cu accumulation up to 1300 mg kg-1. Copy numbers of amoA (AOA and AOB genes were lower in both polluted paddies, following the trend with the enzyme assays, whereas that of nirK was not significantly affected. Analysis of the DGGE profiles revealed a shift in the community structure of AOA, and to a lesser extent, differences in the community structure of AOB and denitrifier between soils from the two sites with different pollution intensity and metal composition. All of the retrieved AOB sequences belonged to the genus Nitrosospira, among which species Cluster 4 appeared more sensitive to metal pollution. In contrast, nirK genes were widely distributed among different bacterial genera that were represented differentially between the polluted and unpolluted paddies. This could suggest either a possible non-specific target of the primers conventionally used in soil study or complex interactions between soil properties and metal contents on the observed community and activity changes, and thus on the N transformation in the polluted rice soils.

  5. [Shortcut Nitrosation-Denitrifying Phosphorus Removal Based on High-quality Carbon Source in Combined Process of CAMBR].

    Science.gov (United States)

    Cheng, Ji-hui; Wu, Peng; Cheng, Chao-yang; Shen, Yao-liang

    2015-12-01

    The volatile fatty acids (VFAs) are high-quality carbon source which can be utilized in the process of denitrifying phosphorus removal. Therefore, a combined process of anaerobic baffled reactor (ABR) with microbial phase separation and membrane bioreactor (MBR), i. e. CAMBR, with high-quality effluent was investigated in this experiment for highly efficient denitrifying phosphorus removal through providing high-quality carbon source by optimizing operational conditions such as hydraulic retention time (HRT) in the ABR. The results indicated that sufficient high-quality carbon source VFA could be acquired when the HRT of ABR was 4.8 h. The consumption of VFA was 56. 1 mg · L⁻¹ while the release of phosphorus was 10.43 mg · L⁻¹ showing that 5.38 mg of VFA was required to release 1 mg PO₄³⁻-P. Meanwhile, the uptake of phosphorus was 12. 35 mg · L⁻¹, while the uptake of phosphorus of MBR tank was 1.33 mg · L⁻¹. In the process of shortcut nitrification, 0.62 mg NOx⁻-N was needed when 1 mg PO₄³⁻-P was taken up, and 1.67 to 2.04 mg NO₂⁻-N was required when 1 mg PO₄³⁻-P was taken up, and the combined system achieved stable effluent quality. The average removal rates of COD, TN and soluble PO₄³⁻-P were 91%, 84% and 93%, respectively, correspondingly the average effluent concentrations were 30, 7.15 and 0.55 mg · L⁻¹, respectively. The results stated that the CAMBR achieved stable and highly efficient denitrifying phosphorus removal in domestic sewage treatment. PMID:27011991

  6. Different response of nitrifiers and denitrifiers to re-wetting shape the NO release from soils in laboratory incubation experiments

    Science.gov (United States)

    Behrendt, Thomas; Wu, Dianming; Song, Guozheng; Pommerenke, Bianca; Braker, Gesche

    2014-05-01

    Laboratory incubation studies incubating soils at a wide range of soil moistures, soil temperatures and mixing ratios of NO in the headspace and inorganic nutrient contents (NH4+,NO3-, NO2-) showed that release rates of NO follow an exponential function with increasing soil temperature and an optimum function for soil moisture. This approach assumes that environmental factors play the dominant role in shaping an ecosystem and thereby microbial communities and control the NO release from soil. We determined the NO release rate for a dryland farming soil under flooding irrigation in Xinjiang, China, a mid-latitude agricultural soil (Mainz, Germany), and a rice paddy (Ambai, India) upon wetting and subsequent drying out of soils. Only the release rate for the mid-latitude agricultural soil followed an optimum function for soil moisture. Release rates for the dryland farming soil and rice paddy, however, followed a two maxima function with distinct maxima at higher and lower soil moisture. Acknowledgement of two distinct maxima is critical for more accurately assessing regional biogenic NO emissions of soils under field conditions. To analyse the response of nitrifiers and denitrifiers involved in NO turnover in more detail we linked molecular analysis of functional gene expression (nirK and nirS, bacterial and archaeal amoA) and microbial community composition to NO release rates. We could show that the maximal transcriptional activity of denitrifiers and ammonia oxidizers differs with soil moisture and that higher transcriptional activity of nirS-type denitrifiers at higher soil moisture and of archaeal ammonia oxidizers at lower soil moisture may explain the two maxima for NO release.

  7. Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

    the perennial oxygen minimum zone (OMZ) in © Inter-Research 2004 · www.int-res.com*Corresponding author. Email: bbw@princeton.edu Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea D. Amal Jayakumar 1 , Chris..., excess water was removed from the Sterivex using a syringe, and the capsule was capped using sealing clay and a luer lock cap, packed in polypropylene bags, and immediately frozen in liquid nitrogen. The samples were stored in liquid nitrogen, on dry ice...

  8. Denitrification Activity of a Remarkably Diverse Fen Denitrifier Community in Finnish Lapland Is N-Oxide Limited

    OpenAIRE

    Palmer, Katharina; Horn, Marcus A.

    2015-01-01

    Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anox...

  9. [Effects of different fertilization regimes on abundance and community structure of the nirK-type denitrifying bacteria in greenhouse vegetable soils].

    Science.gov (United States)

    Zeng, Xi-Bai; Wang, Ya-Nan; Wang, Yu-Zhong; Bai, Ling-Yu; Li, Lian-Fang; Duan, Ran; Su, Shi-Ming; Wu, Cui-Xia

    2014-02-01

    The community structure and abundance of nirK-type denitrifying bacteria in different soil layers (0-20 cm and 20-40 cm) under various fertilization regimes in Wuwei, Gansu Province were investigated by the combination of terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR. Results showed that the nirK-type denitrifying bacteria community structure was significantly affected by fertilization regimes, especially for 70, 156 and 190 bp T-RFs that represented the dominant populations in greenhouse soil. Fertilization regimes significantly influenced the abundance of nirK gene in the 0-20 cm soil layer with the highest abundance of nirK gene copy number (2.16 x 10(7) copies x g(-1) soil) detected in the manure treatment (M), which was 2.04 and 2.02 times of that in the control (CK) and chemical fertilizer (NPK) treatments, respectively. Both the dominant population and abundance of nirK-type denitrifying bacteria in the greenhouse soil were significantly different between the 0-20 cm and 20-40 cm soil layers, and the nirK-type denitrifying bacteria community structure and abundance in the greenhouse soil were obviously different from that in the field. Soil pH, soil organic matter content and nitrate-N content had the greatest influence on the bacterial community composition. Phylogenetic analysis indicated that there were not only anaerobic nirK-type denitrifying bacteria in greenhouse soil, but also aerobic denitrifying bacteria, such as Rhizobium, Ochrobactrum, Agrobacterium. PMID:24830252

  10. pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil

    Directory of Open Access Journals (Sweden)

    Kristof eBrenzinger

    2015-09-01

    Full Text Available Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production. Little is known about how complex soil denitrifier communities respond to pH change and whether their ability to maintain denitrification over a wider pH range relies on phenotypic redundancy. In the present study, we followed the abundance and composition of an overall and transcriptionally active denitrifier community extracted from a farmed organic soil in Sweden (pHH2O = 7.1 when exposed to pH 5.4 and drifting back to pH 6.6. The soil was previously shown to retain much of its functioning (low N2O/N2 ratios over a wide pH range, suggesting a high functional versatility of the underlying community. We found that denitrifier community composition, abundance and transcription changed throughout incubation concomitant with pH change in the medium, allowing for complete reduction of nitrate to N2 with little accumulation of intermediates. When exposed to pH 5.4, the denitrifier community was able to grow but reduced N2O to N2 only when near-neutral pH was reestablished by the alkalizing metabolic activity of an acid-tolerant part of the community. The genotypes proliferating under these conditions differed from those dominant in the control experiment run at neutral pH. Denitrifiers of the nirS-type appeared to be severely suppressed by low pH and nirK-type and nosZ-containing denitrifiers showed strongly reduced transcriptional activity and growth, even after restoration of neutral pH. Our study suggests that low pH episodes alter transcriptionally active populations which shape denitrifier communities and determine their gas kinetics.

  11. pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil.

    Science.gov (United States)

    Brenzinger, Kristof; Dörsch, Peter; Braker, Gesche

    2015-01-01

    Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production. Little is known about how complex soil denitrifier communities respond to pH change and whether their ability to maintain denitrification over a wider pH range relies on phenotypic redundancy. In the present study, we followed the abundance and composition of an overall and transcriptionally active denitrifier community extracted from a farmed organic soil in Sweden (pH H2O = 7.1) when exposed to pH 5.4 and drifting back to pH 6.6. The soil was previously shown to retain much of its functioning (low N2O/N2 ratios) over a wide pH range, suggesting a high functional versatility of the underlying community. We found that denitrifier community composition, abundance and transcription changed throughout incubation concomitant with pH change in the medium, allowing for complete reduction of nitrate to N2 with little accumulation of intermediates. When exposed to pH 5.4, the denitrifier community was able to grow but reduced N2O to N2 only when near-neutral pH was reestablished by the alkalizing metabolic activity of an acid-tolerant part of the community. The genotypes proliferating under these conditions differed from those dominant in the control experiment run at neutral pH. Denitrifiers of the nirS-type appeared to be severely suppressed by low pH and nirK-type and nosZ-containing denitrifiers showed strongly reduced transcriptional activity and growth, even after restoration of neutral pH. Our study suggests that low pH episodes alter transcriptionally active populations which shape denitrifier communities and determine their gas kinetics. PMID:26441895

  12. pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil

    OpenAIRE

    Brenzinger, Kristof; Dörsch, Peter; Braker, Gesche

    2015-01-01

    Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production. Little is known about how complex soil denitrifier communities respond to pH change and whether their ability ...

  13. Uranium enrichment by gas centrifuge

    International Nuclear Information System (INIS)

    After recalling the physical principles and the techniques of centrifuge enrichment the report describes the centrifuge enrichment programmes of the various countries concerned and compares this technology with other enrichment technologies like gaseous diffusion, laser, aerodynamic devices and chemical processes. The centrifuge enrichment process is said to be able to replace with advantage the existing enrichment facilities in the short and medium term. Future prospects of the process are also described, like recycled uranium enrichment and economic improvements; research and development needs to achieve the economic prospects are also indicated. Finally the report takes note of the positive aspect of centrifuge enrichment as far as safeguards and nuclear safety are concerned. 27 figs, 113 refs

  14. Isolation of the {epsilon}-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.-C. [Department of Environmental Engineering, Hungkuang University, Shalu, Taichung 433, Taiwan (China)]. E-mail: chunchin@sunrise.hk.edu.tw; Lee, C.-M. [Department of Environmental Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

    2007-06-25

    {epsilon}-Caprolactam has high COD and toxicity, so its discharge to natural water and soil systems may lead to an adverse environmental effect on water quality, endangering public health and welfare. This investigation attempts to isolate {epsilon}-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene (ABS) resin. The goal is to elucidate the effectiveness of isolated pure strain and ABS mixed strains in treating {epsilon}-caprolactam from synthetic wastewater. The results reveal that Paracoccus versutus MDC-3 was isolated from the wastewater treatment system manufactured with ABS resin. The ABS mixed strains and P. versutus MDC-3 can consume up to 1539 mg/l {epsilon}-caprolactam to denitrify from synthetic wastewater. Complete {epsilon}-caprolactam removal depended on the supply of sufficient electron acceptors (nitrate). Strain P. versutus MDC-3, Hyphomicrobium sp. HM, Methylosinus pucelana and Magnetospirillum sp. CC-26 are related closely, according to the phylogenetic analyses of 16S rDNA sequences.

  15. Isolation of the epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin.

    Science.gov (United States)

    Wang, Chun-Chin; Lee, Chi-Mei

    2007-06-25

    epsilon-Caprolactam has high COD and toxicity, so its discharge to natural water and soil systems may lead to an adverse environmental effect on water quality, endangering public health and welfare. This investigation attempts to isolate epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene (ABS) resin. The goal is to elucidate the effectiveness of isolated pure strain and ABS mixed strains in treating epsilon-caprolactam from synthetic wastewater. The results reveal that Paracoccus versutus MDC-3 was isolated from the wastewater treatment system manufactured with ABS resin. The ABS mixed strains and P. versutus MDC-3 can consume up to 1539mg/l epsilon-caprolactam to denitrify from synthetic wastewater. Complete epsilon-caprolactam removal depended on the supply of sufficient electron acceptors (nitrate). Strain P. versutus MDC-3, Hyphomicrobium sp. HM, Methylosinus pucelana and Magnetospirillum sp. CC-26 are related closely, according to the phylogenetic analyses of 16S rDNA sequences. PMID:17161908

  16. Shifts in the microbial community, nitrifiers and denitrifiers in the biofilm in a full-scale rotating biological contactor.

    Science.gov (United States)

    Peng, Xingxing; Guo, Feng; Ju, Feng; Zhang, Tong

    2014-07-15

    The objective of this study was to investigate the microbial community shifts, especially nitrifiers and denitrifiers, in the biofilm of two rotating biological contactor (RBC) trains with different running times along the plug flowpath. The microbial consortia were profiled using multiple approaches, including 454 high-throughput sequencing of the V3-V4 region of 16S rRNA gene, clone libraries, and quantitative polymerase chain reaction (qPCR). The results demonstrated that (1) the overall microbial community at different locations had distinct patterns, that is, there were similar microbial communities at the beginnings of the two RBC trains and completely different populations at the ends of the two RBC trains; (2) nitrifiers, including ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB, Nitrosomonas) and nitrite-oxidizing bacteria (NOB, Nitrospira), increased in relative abundance in the biofilm along the flowpath, whereas denitrifiers (Rhodanobacter, Paracoccus, Thauera, and Azoarcus) markedly decreased; (3) the AOA were subdominant to the AOB in all sampled sections; and (4) strong ecological associations were shown among different bacteria. Overall, the results of this study provided more comprehensive information regarding the biofilm community composition and assemblies in full-scale RBCs.

  17. Removal of nitrogen and phosphorus from the secondary effluent in tertiary denitrifying biofilters combined with micro-coagulation.

    Science.gov (United States)

    Wei, Nan; Shi, Yunhong; Wu, Guangxue; Hu, Hongying; Guo, Yumei; Wu, Yihui; Wen, Hui

    2016-01-01

    Effective control of nitrogen and phosphorus in secondary effluent can reduce or avoid the eutrophication of receiving water bodies. Two denitrifying biofilters (DNBFs) packed with different sizes of quartz sands combined with micro-coagulation were operated for simultaneous removal of nitrogen and phosphorus from the secondary effluent. The quartz sand size in one DNBF was 2-4 mm (DNBFS), and in the other was 4-6 mm (DNBFL). In both DNBFs, methanol was used as the electron donor and different organic carbon to nitrogen (C/N) ratios were applied. Under C/N ratios of 1.5, 1.25, and 0.75 g/g, the nitrate nitrogen (NO3(-)-N) removal percentages were 73%, 77%, and 50% in DNBFS, and 43%, 25%, and 21% in DNBFL; the effluent total phosphorus concentrations were 0.15, 0.14, and 0.18 mg/L in DNBFS, and 0.29, 0.35, and 0.24 mg/L in DNBFL. The performance of both biofilters was quite stable within a backwashing cycle. The NO3(-)-N reduction rates were 1.31, 1.10, and 0.48 mg/(L·min) in DNBFS, and 0.97, 0.27, and 0.10 mg/(L·min) in DNBFL. For biomass detached from both biofilters, their denitrifying activities were similar. Biofilm biomass in DNBFS was higher than that in DNBFL, inducing a high denitrification efficiency in DNBFS.

  18. Isolation of aerobic denitrifier and characteristics of enhanced nitrogen removal in concentric-circles reactor with diversion wall

    Institute of Scientific and Technical Information of China (English)

    许晓毅; 汤丽娟; 罗固源; 蒋真玉

    2009-01-01

    Three strains of aerobic denitrifiers,named as AT3,AT6 and AT7,were isolated from concentric-circles reactor with diversion wall possessing simultaneous nitrification and denitrification (SND) effect of 69%. The three strains are all gram-positive and rod-shaped,and their colonial colors are pale yellow,milk white and pink,respectively. Combined with 16SrDNA sequence homology comparison and biochemical tests,AT3 and AT7 were identified to belong to Rhodococcus,and AT6 to Gordonia. These bacterial strains could grow well in the medium with potassium nitrate as nitrogen source and sodium citrate as carbon source. Based on the enhanced nitrogen removal experiments of selected bacteria mixture for activated sludge,the inoculum amount of 5% was supposed to be proper. The mixed biomass suspension of selected strains with PVA immobilization was put into the concentric-circles reactor in order to study the characteristics of enhanced nitrogen removal after amplifying cultivation with inoculated amount of 5%. The experimental results show that the average removal efficiencies of ammonia nitrogen (NH3-N) and total nitrogen (TN) in the reactor enhanced with aerobic denitrifying bacteria using PVA are 92.18% and 79.14% respectively,increasing by 5.29% and 7.83% respectively compared with removal effects of control group without strains enhancement.

  19. Estimate of denitrifying microbiota in tertiary sewage treatment and kinetics of the denitrification process using different sources of carbon

    Directory of Open Access Journals (Sweden)

    Marchetto Margarida

    2003-01-01

    Full Text Available A study of the kinetics of denitrification was carried out in the laboratory based on the quantification of N2O, the final product of the activity of denitrifying microorganisms, when the enzymatic reduction of N2O to N2 was blocked by acetylene. Concentrated mixed liquor (sludge from a reactor with intermittent aeration used for sewage treatment was used as the inoculum, while methanol, acetic acid, glucose, effluent sewage from an anaerobic fluidized bed reactor and synthetic substrate simulating domestic sewage were used as carbon sources. The mean concentration of nitrate was 20 mg/L. Maxima of N2O production and NO3- consumption occurred between 0.5h and 2.0h of incubation using all the carbon sources, which characterized the denitrification process. Acetic acid and methanol were responsible for the highest rates of N2O production. The estimated number of denitrifying microorganisms in the reactor with intermittent aeration, using the MPN technique, varied from 10(9 to 10(10 MPN/g VSS, indicating a high potential for the occurrence of denitrification.

  20. 好氧反硝化菌的筛选鉴定及其脱氮特性研究%SCREENING, IDENTIFICATION AND DENITRIFICATION CHARACTERISTICS OF AEROBIC DENITRIFIERS

    Institute of Scientific and Technical Information of China (English)

    张宇燕; 贺根和; 陆丽君; 刘佳; 黄翔峰; 梁亮亮

    2014-01-01

    通过分离筛选获得3株好氧反硝化菌S1、S2和S3,初步鉴定S1为土生拉乌尔菌属(Raoultella terrigena), S2和S3均为解鸟氨酸拉乌尔菌属(Raoultella ornithinolytica)。这3株菌为好氧反硝化菌属首次报道,对其好氧反硝化脱氮特性的研究结果表明,培养液中氮含量的大幅变化均发生于菌株的对数生长期;在以硝酸盐或亚硝酸盐为唯一氮源的研究中,NO3--N和NO2--N的24 h去除率分别约为26%和67%,说明这3株菌更容易利用亚硝酸盐进行好氧反硝化;而且研究结果还表明,S3为脱氮效率最优的菌株,对低氮浓度的富营养化水质有较好的反硝化效果,4 h时S3的反硝化速率最大,达0.62 mg·L-1·h-1,对TN的反硝化脱氮贡献率可达52.5%。%Three aerobic denitrifiers(S1, S2 and S3)were abtained by isolating and screening. Strain S1 was identified as Raoultella terrigena, while strains S2 and S3 were identified as Raoultella ornithinolytica. It is first reported that the three bacteria are aerobic denitrifiers. Studies on their aerobic denitrification characteristics showed that significant changes of nitrogen level in culture media occurred in the logarithmic growth phase of strains; in the studies on using nitrate or nitrite as sole nitrogen source, respectively, the removal rates of NO3--N and NO2--N were 26%and 67%at 24 h, respectively, which proved that nitrite was used more easily for aerobic denitrification of three strains;Results also showed that S3 was optimal strain with the highest removal efficiency of nitrogen, which had better denitrification effects on eutrophic water with low concentration nitrogen, and S3 had the highest denitrification rate of 0.62 mg·L-1·h-1 and denitrification contribution rate of TN up to 52.5%at 4 h.

  1. Submerged macrophytes shape the abundance and diversity of bacterial denitrifiers in bacterioplankton and epiphyton in the Shallow Fresh Lake Taihu, China.

    Science.gov (United States)

    Fan, Zhou; Han, Rui-Ming; Ma, Jie; Wang, Guo-Xiang

    2016-07-01

    nirK and nirS genes are important functional genes involved in the denitrification pathway. Recent studies about these two denitrifying genes are focusing on sediment and wastewater microbe. In this study, we conducted a comparative analysis of the abundance and diversity of denitrifiers in the epiphyton of submerged macrophytes Potamogeton malaianus and Ceratophyllum demersum as well as in bacterioplankton in the shallow fresh lake Taihu, China. Results showed that nirK and nirS genes had significant different niches in epiphyton and bacterioplankton. Bacterioplankton showed greater abundance of nirK gene in terms of copy numbers and lower abundance of nirS gene. Significant difference in the abundance of nirK and nirS genes also existed between the epiphyton from different submerged macrophytes. Similar community diversity yet different community abundance was observed between epiphytic bacteria and bacterioplankton. No apparent seasonal variation was found either in epiphytic bacteria or bacterioplankton; however, environmental parameters seemed to have direct relevancy with nirK and nirS genes. Our study suggested that submerged macrophytes have greater influence than seasonal parameters in shaping the presence and abundance of bacterial denitrifiers. Further investigation needs to focus on the potential contact and relative contribution between denitrifiers and environmental factors. PMID:27048324

  2. A Contrastive Research on American-Chinese Cultural Identity from Perspective of Mass Culture

    Institute of Scientific and Technical Information of China (English)

    赵欣

    2012-01-01

    The appearance and development of "Super Girl" accompanies with the rise of mass culture and it reflects the main features of mass culture.Meanwhile western mass cultural product especially the American mass cultural product "American Idol" influenced Chinese mass culture and it has produced massive impact on the identity of national cultural and cultural independence in China.The thesis can help to deepen and make up for the deficiency of mass culture theories,to enrich the applicational experience and the...

  3. Evidence for the biogenic origin of manganese-enriched layers in Lake Superior sediments.

    Science.gov (United States)

    Palermo, Christine; Dittrich, Maria

    2016-04-01

    Manganese (Mn) and iron (Fe)-enriched sediment layers were discovered in Lake Superior within, above and below the oxic-anoxic interface. While the role of bacteria in redox reactions with Mn is known to be significant, little information exists about indigenous microbial communities in many freshwater environments. This study examined the bacterial communities of Mn-enriched layers in Lake Superior to identify the potential Mn(II) oxidizers responsible for the formation of Mn oxides. Anaerobic Mn(II) oxidation occurring in the Mn-enriched layers at the oxic-anoxic interface was investigated using Mn(II)-enriched cultures. High-resolution microscopic and spectroscopic investigations provided evidence of the biogenic formation of Mn oxides on cell surfaces. Spectroscopic mapping confirmed high levels of Mn in structures resembling biogenic Mn oxides. These structures were observed in enrichment cultures and in Mn-enriched layer sediment samples, indicating the significance of biogenic Mn oxidation occurring in situ. 16S ribosomal DNA pyrosequencing was used to identify the bacteria potentially responsible for Mnoxide formation in the enrichment cultures and Mn-enriched layers, revealing that the Mn-enriched layer contains classes with known Mn(II)-oxidizing members. Pyrosequencing of bacterial cultures suggested that these bacteria may be Bacillus strains, and that anaerobic microbial-mediated Mn(II) oxidation contributes to the formation of the layers.

  4. Evidence for the biogenic origin of manganese-enriched layers in Lake Superior sediments.

    Science.gov (United States)

    Palermo, Christine; Dittrich, Maria

    2016-04-01

    Manganese (Mn) and iron (Fe)-enriched sediment layers were discovered in Lake Superior within, above and below the oxic-anoxic interface. While the role of bacteria in redox reactions with Mn is known to be significant, little information exists about indigenous microbial communities in many freshwater environments. This study examined the bacterial communities of Mn-enriched layers in Lake Superior to identify the potential Mn(II) oxidizers responsible for the formation of Mn oxides. Anaerobic Mn(II) oxidation occurring in the Mn-enriched layers at the oxic-anoxic interface was investigated using Mn(II)-enriched cultures. High-resolution microscopic and spectroscopic investigations provided evidence of the biogenic formation of Mn oxides on cell surfaces. Spectroscopic mapping confirmed high levels of Mn in structures resembling biogenic Mn oxides. These structures were observed in enrichment cultures and in Mn-enriched layer sediment samples, indicating the significance of biogenic Mn oxidation occurring in situ. 16S ribosomal DNA pyrosequencing was used to identify the bacteria potentially responsible for Mnoxide formation in the enrichment cultures and Mn-enriched layers, revealing that the Mn-enriched layer contains classes with known Mn(II)-oxidizing members. Pyrosequencing of bacterial cultures suggested that these bacteria may be Bacillus strains, and that anaerobic microbial-mediated Mn(II) oxidation contributes to the formation of the layers. PMID:26636960

  5. Survival of indicator organisms during enrichment on tetrachloroethene.

    Science.gov (United States)

    Skramstad, J D; Hurst, C J; Novak, P J

    2003-01-01

    A laboratory study was performed as the basis for a full-scale bioaugmentation project at a site contaminated with chlorinated ethenes. The objectives of this study were to 1) develop a protocol to enrich for a tetrachloroethene (PCE)-dechlorinating culture from waste activated sludge and anaerobic digester biosolids and 2) monitor the survival of fecal coliform bacteria and bacteriophage, which model enteric viruses, during the enrichment process. A culture was enriched in 8 days with the ability to degrade 6-microM PCE to cis-dichloroethene. Using the enrichment protocol in two identical experiments, significant inactivation of fecal coliform bacteria (2 log) and somatic coliphage (0.33 log) was observed in one of the experiments; no inactivation occurred in the second experiment. The number of F-specific coliphage decreased in both experiments (0.87 and 1.26 log inactivation). Despite the decrease in some of the coliform and bacteriophage numbers, the quantity of organisms and phage particles present after enrichment was still high (approximately 7.5 x 10(5) most probable number/L, 6.9 x 10(6) plaque-forming units (PFU)/L, and 3.3 x 10(5) PFU/L, for fecal coliform bacteria, somatic coliphage, and F-specific coliphage, respectively). This may be cause for concern, depending on the current and future groundwater use at or near a site undergoing bioaugmentation with cultures derived from waste activated sludge and anaerobic digester biosolids.

  6. Denitrifying Phosphorus Removal in MUCT-MBR%MUCT-MBR工艺反硝化除磷脱氮研究

    Institute of Scientific and Technical Information of China (English)

    刘鹏霄; 张捍民; 王晓琳; 肖景霓; 杨凤林

    2009-01-01

    自行设计的双反应器MUCT-MBR简化了MUCT工艺,将反应池由5个简化到2个,减小了工艺占地面积,并且采用膜过滤取代二沉池出水,操作简单,出水安全可靠.针对MUCT-MBR工艺脱氮除磷性能,尤其是反硝化除磷功能进行研究.结果表明,当进水C/N/P比在33.3/5/1~25/5.5/1范围内,整个实验过程中COD、TN和TP平均去除率分别达到89.3%、75.4%、79.2%;且膜出水不受污泥沉降性的影响.缺氧段的反硝化吸磷是MUCT-MBR工艺除磷的关键,系统运行至第58 d,系统中反硝化除磷菌(DPAOs)所占比例达84.2%,反硝化除磷占系统总磷去除的67.07%.%The self-designed MUCT-MBR simplifies the MUCT process with reducing reactors from 5 to 2, which greatly reduces land occupied by equipment. Instead of secondary sedimentation tank, the. membrane effluent quality is quite safe, and the operation is simple. In the investigation about simultaneous phosphorus and nitrogen removal of MUCT-MBR, the results showed that: when the proportions of C, N and P in the influent were 33.3/5/1-25/5.5/1, the average removal rate of COD, TN and TP in the whole experimental process were 89.3%,75.4% and 79.2 % , respectively. And the sludge settling capacity had no influence on the membrane effluent quality. The key factor of N and P removal rates is denitrifying phosphorus removal in anoxic condition. The proportion of denitrifying phosphate accumulating organisms (DPAOs) and the rate of denitrifying phosphorous removal were 84.2% and 67.07% on the 58th day, respectively.

  7. Earthquake forecast enrichment scores

    Directory of Open Access Journals (Sweden)

    Christine Smyth

    2012-03-01

    Full Text Available The Collaboratory for the Study of Earthquake Predictability (CSEP is a global project aimed at testing earthquake forecast models in a fair environment. Various metrics are currently used to evaluate the submitted forecasts. However, the CSEP still lacks easily understandable metrics with which to rank the universal performance of the forecast models. In this research, we modify a well-known and respected metric from another statistical field, bioinformatics, to make it suitable for evaluating earthquake forecasts, such as those submitted to the CSEP initiative. The metric, originally called a gene-set enrichment score, is based on a Kolmogorov-Smirnov statistic. Our modified metric assesses if, over a certain time period, the forecast values at locations where earthquakes have occurred are significantly increased compared to the values for all locations where earthquakes did not occur. Permutation testing allows for a significance value to be placed upon the score. Unlike the metrics currently employed by the CSEP, the score places no assumption on the distribution of earthquake occurrence nor requires an arbitrary reference forecast. In this research, we apply the modified metric to simulated data and real forecast data to show it is a powerful and robust technique, capable of ranking competing earthquake forecasts.

  8. The Cultural Heritage of Interculturalism

    Directory of Open Access Journals (Sweden)

    Martin Peterson

    2015-03-01

    Full Text Available The article traces the cultural heritage of inter-cultural contexts, which have had profound impact over long time. It takes its departure in antique and culturally complex environments in the eastern Mediterranean. One millennium later corresponding inter-cultural conditions are explored in the western part of the Mediterranean. Both cases demonstrated their wide and long lasting influences on posterity. The cultural heritage implied the deep effects of cross-fertilization and ensuing cultural enrichment as the conflation of several well-endowed cultures took place. A similar, more powerful outcome followed the Radical Enlightenment in Leiden around 1650s and in Vienna some centuries later.

  9. Enrichment and activity of methanotrophic microorganisms from municipal wastewater sludge.

    Science.gov (United States)

    Siniscalchi, Luciene Alves Batista; Vale, Isabel Campante; Dell'Isola, Jéssica; Chernicharo, Carlos Augusto; Calabria Araujo, Juliana

    2015-01-01

    In this study, methanotrophic microorganisms were enriched from a municipal wastewater sludge taken from an Upflow Anaerobic Sludge Blanket reactor. The enrichment was performed in a sequencing batch reactor (SBR) with an autotrophic medium containing nitrite and nitrate. The microbial community composition of the inoculum and of the enrichment culture after 100 days of SBR operation was investigated and compared with the help of data obtained from 454 pyrosequencing analyses. The nitrite and nitrate removal efficiencies were 68% and 53%, respectively, probably due to heterotrophic denitrification. Archaeal cells of the anaerobic methanotrophic Archaic (ANME)-I and ANME-II groups were detected by polymerase chain reaction throughout the whole cultivation period. Pyrosequencing analysis showed that community composition was different among the two samples analysed. The dominant phyla found in the inoculum were Synergistestes, Firmicutes and Euryarchaeota, while Planctomycetes, Verrucomicrobia, Chloroflexi and Proteobacteria prevailed in the enriched biomass. The cultivation conditions decreased Methanobacterium abundance from 8% to 1%, and enriched for methanotrophic bacteria such as Methylocaldum, Methylocistis and Methylosinus. Sequences of Methylocaldum sp. accounted for 2.5% of the total reads. The presence and high predominance of Verrucomicrobia in the enriched biomass suggested that other unknown methanotrophic species related to that phylum might also have occurred in the reactor. Anaerobic methane oxidation activity was measured for both samples, and showed that the activity of the enrichment culture was nearly three times higher than the activity of the inoculum. Taken together, these results showed that the inoculum type and cultivation conditions were properly suited for methanotrophic enrichment. PMID:25495866

  10. Enrichment of anaerobic syngas converting bacteria from bioreactor sludges

    NARCIS (Netherlands)

    Alves, J.I.; Stams, A.J.M.; Plugge, C.M.; Alves, M.M.; Sousa, D.Z.

    2013-01-01

    Thermophilic (55°C) anaerobic microbial communities were enriched with a synthetic syngas mixture (composed of CO, H2 and CO2 ) or with CO alone. Cultures T-Syn and T-CO were incubated and successively transferred with syngas (16 transfers) or CO (9 transfers), respectively, with increasing CO parti

  11. Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation by Thiobacillus denitrificans Under Aerobic vs. Denitrifying Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Beller, H R; Letain, T E; Chakicherla, A; Kane, S R; Legler, T C; Coleman, M A

    2006-04-22

    Thiobacillus denitrificans is one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with ke chemolithoautotrophic functions (such as sulfur-compound oxidation and CO2 fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately ten percent of the genome) as differentially expressed using Robust Multi-array Average statistical analysis and a 2-fold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochrome cbb3 oxidase genes, cbbL and cbbS (encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions included nar, nir, and nor genes (associated respectively with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification), cbbM (encoding form II RubisCO), and genes involved with sulfur-compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and of dsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the order nar > nir > nor > nos. Reverse transcription, quantitative PCR analysis was used to validate these trends.

  12. The diversity of denitrifying bacteria in the alpine meadow soil of Sanjiangyuan natural reserve in Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    XU Haiping; ZHANG Yuguang; SUN Yanping; LI Diqiang; CHEN Xinmou; WANG Huimin; XIAO Qiming; LIU Xueduan

    2006-01-01

    This is the first time to describe the diversity of denitrifying bacteria in Sanjiangyuan natural reserve in Tibet Plateau by investigating the molecular diversity and phylogenetic analysis of nirK and nosZ genes using PCR-RFLP and sequencing. Four soil samples were collected from alpine meadow communities from over an altitude of 4600 m which had different physicochemical properties by principal component analysis (PCA). For the genes fragment of nirKand nosZ, the diverse PCR products were characterized by cloning, restriction fragment length polymorphism (RFLP) analysis and sequenced. A total of 253 nirK clones and 283 nosZ clones were received in four samples, and 78 operational taxonomic units (OTUs) of nirK and 120 OTUs of nosZ by the restriction enzymes Mspl and Rsal digested. The analysis of environmental factors showed that altitude and C/N ratio in soil may be the key factors to the denitrifying bacteria community. 36 nirK clones and 17 nosZ clones were sequenced, and their levels of nucleotide identity were from 69% to 98% and 57% to 97%, respectively. The phylogenetic tree was constructed using the Clustal W and Mega softwares, and all the sequenced clones could be subdivided into 4 groups. Some of clone sequences were related to the nirK and nosZ genes belonging to three phylogenetic subdivisions (α-, β- and Y subclasses of the Proteobacteria), while most of the clones were closely related to the genes of the uncultured bacteria. The sequence distributions were not clear relating to the sample sites in the tree.

  13. Hydrogen-enriched fuels

    Energy Technology Data Exchange (ETDEWEB)

    Roser, R. [NRG Technologies, Inc., Reno, NV (United States)

    1998-08-01

    NRG Technologies, Inc. is attempting to develop hardware and infrastructure that will allow mixtures of hydrogen and conventional fuels to become viable alternatives to conventional fuels alone. This commercialization can be successful if the authors are able to achieve exhaust emission levels of less than 0.03 g/kw-hr NOx and CO; and 0.15 g/kw-hr NMHC at full engine power without the use of exhaust catalysts. The major barriers to achieving these goals are that the lean burn regimes required to meet exhaust emissions goals reduce engine output substantially and tend to exhibit higher-than-normal total hydrocarbon emissions. Also, hydrogen addition to conventional fuels increases fuel cost, and reduces both vehicle range and engine output power. Maintaining low emissions during transient driving cycles has not been demonstrated. A three year test plan has been developed to perform the investigations into the issues described above. During this initial year of funding research has progressed in the following areas: (a) a cost effective single-cylinder research platform was constructed; (b) exhaust gas speciation was performed to characterize the nature of hydrocarbon emissions from hydrogen-enriched natural gas fuels; (c) three H{sub 2}/CH{sub 4} fuel compositions were analyzed using spark timing and equivalence ratio sweeping procedures and finally; (d) a full size pick-up truck platform was converted to run on HCNG fuels. The testing performed in year one of the three year plan represents a baseline from which to assess options for overcoming the stated barriers to success.

  14. Importance of pre-enrichment media for isolation of Salmonella spp. from swine and poultry

    DEFF Research Database (Denmark)

    Hoorfar, Jeffrey; Baggesen, Dorte Lau

    1998-01-01

    of the BPW method with parallel pre-enrichment of the same sample in UB resulted in high sensitivity for swine (0.92) and poultry (0.95) samples. A 2-h pre-enrichment in the non-selective Revive, followed by overnight enrichment in selective broth, resulted in a low sensitivity, particularly for the neck......, it may be advantageous to use SEE rather than standard culturing. (C) 1998 Federation of European Microbiological Societies....

  15. Comparison between traditional biological phosphorus removal by anaerobic/aerobic and denitrifying phosphorus removal by anaerobic/aerobic%传统厌氧/好氧生物除磷与厌氧/缺氧反硝化除磷效能的比较

    Institute of Scientific and Technical Information of China (English)

    苏婉琳; 韩萍芳

    2011-01-01

    采用序批式反应器(SBR),对比厌氧/好氧(A/O)和厌氧/缺氧(A/A)2种运行模式对模拟生活和工业混合污水同时脱氮除磷的效能.结果表明:反硝化聚磷菌完全可以在厌氧/缺氧交替运行条件下得到富集,稳定运行的2种模式对有机物和P的去除率分别保持在90%和85%以上,且A/A SBR具有更强的释磷能力,其释磷量比A/O SBR高出1.2倍.进一步试验表明:磷的释放在有无硝酸盐的情况下效果是不同的.2个系统内污泥均有反硝化除磷能力,A/A SBR中所含反硝化聚磷菌(DPAO)的比例是A/O SBR的4.56倍.2种模式出水水质都能取得较好的效果,且能实现同步除磷脱氮,而反硝化除磷在生物除磷方面更具优势.%Two sequence batch reactors(SBRs) in A/O and A/A run modes were operated in parallel to compare their ability of simultaneous phosphorus and nitrogen removal. The results showed that the ability of the anaerobic/anoxic strategy enriched the growth of denitrifying phosphorus bacteria capable of taking up phosphate under anoxic condition, and the removal of COD and phosphorus were averaged over 90% and 85% in the steady-state, respectively. A/A SBR had the stronger anaerobic phosphorus release ability; its amount of anaerobic released phosphorus is higher than 1. 2 times compared with A/O SBR. It is shown that interpretation of phosphorus release tests with or without nitrate present was different. The proportion of denitrifying phosphate accumulating organism ( DPAO) was 4. 56 times compared with the one of A/O SBR. The qualities of effluent were met the criteria, and DPAO systems could obtaia get simultaneous denitrifying and phosphorus removal. Thus, DPAO had more advantages than PAO for biological phosphorus removal.

  16. High enrichment to low enrichment core's conversion. Technical securities

    International Nuclear Information System (INIS)

    This work presents the fulfillment of the technical securities subscribed by INVAP S.E. for the conversion of a high enriched uranium core. The reactor (of 5 thermal Mw), built in the 50's and 60's, is of the 'swimming pool' type, with light water and fuel elements of the curve plates MTR type, enriched at 93.15 %. These are neutronic and thermohydraulic securities. (Author)

  17. A novel denitrifying methanotroph of the NC10 phylum and its microcolony

    Science.gov (United States)

    He, Zhanfei; Cai, Chaoyang; Wang, Jiaqi; Xu, Xinhua; Zheng, Ping; Jetten, Mike S. M.; Hu, Baolan

    2016-09-01

    The NC10 phylum is a candidate phylum of prokaryotes and is considered important in biogeochemical cycles and evolutionary history. NC10 members are as-yet-uncultured and are difficult to enrich, and our knowledge regarding this phylum is largely limited to the first species ‘Candidatus Methylomirabilis oxyfera’ (M. oxyfera). Here, we enriched NC10 members from paddy soil and obtained a novel species of the NC10 phylum that mediates the anaerobic oxidation of methane (AOM) coupled to nitrite reduction. By comparing the new 16S rRNA gene sequences with those already in the database, this new species was found to be widely distributed in various habitats in China. Therefore, we tentatively named it ‘Candidatus Methylomirabilis sinica’ (M. sinica). Cells of M. sinica are roughly coccus-shaped (0.7–1.2 μm), distinct from M. oxyfera (rod-shaped; 0.25–0.5 × 0.8–1.1 μm). Notably, microscopic inspections revealed that M. sinica grew in honeycomb-shaped microcolonies, which was the first discovery of microcolony of the NC10 phylum. This finding opens the possibility to isolate NC10 members using microcolony-dependent isolation strategies.

  18. A novel denitrifying methanotroph of the NC10 phylum and its microcolony.

    Science.gov (United States)

    He, Zhanfei; Cai, Chaoyang; Wang, Jiaqi; Xu, Xinhua; Zheng, Ping; Jetten, Mike S M; Hu, Baolan

    2016-01-01

    The NC10 phylum is a candidate phylum of prokaryotes and is considered important in biogeochemical cycles and evolutionary history. NC10 members are as-yet-uncultured and are difficult to enrich, and our knowledge regarding this phylum is largely limited to the first species 'Candidatus Methylomirabilis oxyfera' (M. oxyfera). Here, we enriched NC10 members from paddy soil and obtained a novel species of the NC10 phylum that mediates the anaerobic oxidation of methane (AOM) coupled to nitrite reduction. By comparing the new 16S rRNA gene sequences with those already in the database, this new species was found to be widely distributed in various habitats in China. Therefore, we tentatively named it 'Candidatus Methylomirabilis sinica' (M. sinica). Cells of M. sinica are roughly coccus-shaped (0.7-1.2 μm), distinct from M. oxyfera (rod-shaped; 0.25-0.5 × 0.8-1.1 μm). Notably, microscopic inspections revealed that M. sinica grew in honeycomb-shaped microcolonies, which was the first discovery of microcolony of the NC10 phylum. This finding opens the possibility to isolate NC10 members using microcolony-dependent isolation strategies. PMID:27582299

  19. Use of an Interculturally Enriched Collaboration Script in Computer-Supported Collaborative Learning in Higher Education

    NARCIS (Netherlands)

    Popov, V.; Biemans, H.J.A.; Kuznetsov, A.N.; Mulder, M.

    2014-01-01

    In this exploratory study, the authors introduced an interculturally enriched collaboration script (IECS) for working in culturally diverse groups within a computer-supported collaborative learning (CSCL) environment and then assessed student online collaborative behaviour, learning performance and

  20. Screening identification and optimal biodegradation conditions of new aerobic denitrifying bacteria%一株好氧反硝化菌的筛选鉴定及其条件优化

    Institute of Scientific and Technical Information of China (English)

    魏俊虎; 赵晓祥; 王苑

    2011-01-01

    This paper is aimed to introduce the screening process and optimization of the biodegradation conditions of a new efficient aerobic denitrifying bacterium. The aerobic denitrifying bacteria N- 4 was extracted from the water samples of Wuning section and Zhejiang section of Suzhou River in Shanghai. The results of biornass and denitrification test indicated that the optimum degradation conditions of the strain N - 4 can be stated as follows: the best temperature was 30 degrees Celsius, the denitrificafion efficiency decreased rapidly when the temperature exceeded 30 degrees Celsius; the best pH value was 7.5 with a high biomass between 7 and 7.5. The best inoculums' size was 20 % and there was no change when it was more than 20 %.Nevertheless, in practice, large amoumt of 20% vaccination can be reduced to 5% and it brings no significant impact to the degradation processing provided the denitrification extends to five hours. The best carbon source was glucose; it was consistent with the characteristics of Klebsiella. Under the conditions motioned above, the degradation rate could reach 87.6% within 16 hours. Through the analysis, the bacteria N -4 was identified as Klebsiella ornithinolytica where under an electron microscope, it was observed as short stubby bacilli with a separate arrangement, no spores, no flagellum, about 0.8 - 1.5 microns in length and about 0.3 - 0.6 microns in diameter. The colonies were off-white round and it was a Gram-negative bacterium.The strain was found in other domestic waters as glycogen accumulating organisms. The Klebsiella strains with denitrifying function was rarely reported in the literature. It can survive in the culture medium from weeks to several months and it can be killed in 30 minutes at 55 degrees, to ensure the application prospect with ecological safety. In this study, the direct sampling from heavily polluted Suzhou creek is equivalent to the natural domestication process. Hence, the screening process is far

  1. Meadow enriched ACP process algebras

    OpenAIRE

    J.A. Bergstra; Middelburg, C.A.

    2009-01-01

    We introduce the notion of an ACP process algebra. The models of the axiom system ACP are the origin of this notion. ACP process algebras have to do with processes in which no data are involved. We also introduce the notion of a meadow enriched ACP process algebra, which is a simple generalization of the notion of an ACP process algebra to processes in which data are involved. In meadow enriched ACP process algebras, the mathematical structure for data is a meadow.

  2. 东南太平洋热液区硫化物样品富集培养物中Fe3+还原细菌的多样性分析%Diversity analysis of Fe3+ -reducing bacteria in enriched cultures from hydrothermal sulfide sample of southeast Pacific Ocean

    Institute of Scientific and Technical Information of China (English)

    秦丹; 张晓波; 姜丽晶; 盖英宝; 曾湘

    2011-01-01

    采集了东南太平洋热液区DY115-20V-S35-TVG17站位的沉积物硫化物样品,其含有76.717% (m/m)强还原性的磁性良好的黄铁矿.以乳酸钠为电子供体,不溶性的氢氧化铁为电子受体,对该样品进行Fe3+还原细菌的定向富集培养.通过构建该菌群的16S rDNA基因文库,随机挑选82个阳性克隆子进行群落结构多样性分析.研究结果表明:82个克隆代表的6种基因型分别属于4个主要类群,其中ε-变形杆菌占有绝对优势,达到55.2%.此外其还包括厚壁菌门、β-变形杆菌和α-变形杆菌,克隆子比例依次为27.6%、10.3%、6.9%.在富集产物中还原氢氧化铁的功能菌群主要是具有硫还原作用的ε-变形菌中的硫还原菌.%The ocean contains rich resources and in deep sea sediments there exists iron compounds at different stages of oxidation and reduction. Iron is one of the most widely distributed elements on the earth and its cycle chiefly includes two processes of oxidation and reduction. As a primitive form of respiration, Fe3 + -reduction and Fe3 + -reducing bacteria play an important role in the iron cycle where in sediments with an anaerobic environment, where iron chiefly exists in a reduced form. In the current study, a hydrothermal sulfide sample was obtained from the southeast Pacific Ocean, site DY115-20V-S35-TVG17 (50.648 l°N,37.780 2°W, depth 2 783 m) using a television grasp sampler in December, 2008, and was found to be mainly composed of iron pyrite with good magnetism, chiefly Fe1-XS and FeS2, 76.717% (m/m) through X-ray detection. To investigate the diversity of Fe3 +-reducing bacteria in the sample, we designed a medium with sodium lactate as the electron donor and insoluble ferric hydroxide as electron acceptor and cultivated the enriched culture of Fe3 +-reducing bacteria from this sample. The 16S Rdna gene library showed that the 29 selected clones in enriched cultures were clustered into two groups. Pro

  3. Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.

    Directory of Open Access Journals (Sweden)

    Xavier Le Roux

    Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification

  4. Building a Culture of Achievement

    Science.gov (United States)

    Major, Marc R.

    2009-01-01

    Culture is the social and intergenerational glue that defines, connects, sustains, and enriches the members of successful communities--including schools and classrooms. A classroom culture is a psychological atmosphere that nurtures and shapes students' attitudes about their own identity, classes, school, and learning in general. Classroom culture…

  5. Linking N2O emission from biochar-amended composting process to the abundance of denitrify (nirK and nosZ) bacteria community.

    Science.gov (United States)

    Li, Shuqing; Song, Lina; Jin, Yaguo; Liu, Shuwei; Shen, Qirong; Zou, Jianwen

    2016-12-01

    Manure composting has been recognized as an important anthropogenic source of nitrous oxide (N2O) contributing to global warming. However, biochar effect on N2O emissions from manure composting is rarely evaluated, especially by linking it to abundance of denitrifying bacteria community. Results of this study indicated that biochar amendment significantly reduced N2O emissions from manure composting, primarily due to suppression of the nirK gene abundance of denitrifying bacteria. Pearson's correlation analysis showed a significant positive correlation between nirK abundance and N2O fluxes, while a negative correlation between nosZ density and N2O fluxes. Simultaneously, a linear correlation between nirK gene abundance minus nosZ gene abundance with N2O fluxes was also observed. In addition, a statistical model for estimating N2O emissions based on the bacterial denitrifying functional genes was developed and verified to adequately fit the observed emissions. Our results highlighted that biochar amendment would be an alternative strategy for mitigating N2O emissions during manure composting, and the information of related functional bacterial communities could be helpful for understanding the mechanism of N2O emissions. PMID:27207069

  6. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

    Science.gov (United States)

    Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

    2016-03-01

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10–50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera.

  7. A doubling of microphytobenthos biomass coincides with a tenfold increase in denitrifier and total bacterial abundances in intertidal sediments of a temperate estuary.

    Directory of Open Access Journals (Sweden)

    Helen Decleyre

    Full Text Available Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS and competition for nutrients (including nitrogen. Pyrosequencing and qPCR was performed on two intertidal surface sediments of the Westerschelde estuary characterized by a two-fold difference in MPB biomass but no difference in MPB composition. Doubling of MPB biomass was accompanied by a disproportionately (ten-fold increase in total bacterial abundances while, unexpectedly, no difference in general community structure was observed, despite significantly lower bacterial richness and distinct community membership, mostly for non-abundant taxa. Denitrifier abundances corresponded likewise while community structure, both for nirS and nirK denitrifiers, remained unchanged, suggesting that competition with diatoms for nitrate is negligible at concentrations in the investigated sediments (appr. 1 mg/l NO3-. This study indicates that MPB biomass increase has a general, significantly positive effect on total bacterial and denitrifier abundances, with stimulation or inhibition of specific bacterial groups that however do not result in a re-structured community.

  8. MALDI-TOF MS Imaging evidences spatial differences in the degradation of solid polycaprolactone diol in water under aerobic and denitrifying conditions.

    Science.gov (United States)

    Rivas, Daniel; Ginebreda, Antoni; Pérez, Sandra; Quero, Carmen; Barceló, Damià

    2016-10-01

    Degradation of solid polymers in the aquatic environment encompasses a variety of biotic and abiotic processes giving rise to heterogeneous patterns across the surface of the material, which cannot be investigated using conventional Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that only renders an "average" picture of the sample. In that context, MALDI-TOF MS Imaging (MALDI MSI) provides a rapid and efficient tool to study 2D spatial changes occurred in the chemical composition of the polymer surface. Commercial polycaprolactone diol (average molecular weight of 1250Da) was selected as test material because it had been previously known to be amenable to biological degradation. The test oligomer probe was incubated under aerobic and denitrifying conditions using synthetic water and denitrifying mixed liquor obtained from a wastewater treatment plant respectively. After ca. seven days of exposure the mass spectra obtained by MALDI MSI showed the occurrence of chemical modifications in the sample surface. Observed heterogeneity across the probe's surface indicated significant degradation and suggested the contribution of biotic processes. The results were investigated using different image processing tools. Major changes on the oligomer surface were observed when exposed to denitrifying conditions. PMID:27213667

  9. Abundance and diversity of bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants revealed by high-throughput sequencing.

    Directory of Open Access Journals (Sweden)

    Zhu Wang

    Full Text Available Biological nitrification/denitrification is frequently used to remove nitrogen from tannery wastewater containing high concentrations of ammonia. However, information is limited about the bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants (WWTPs due to the low-throughput of the previously used methods. In this study, 454 pyrosequencing and Illumina high-throughput sequencing, combined with molecular methods, were used to comprehensively characterize structures and functions of nitrification and denitrification bacterial communities in aerobic and anaerobic sludge of two full-scale tannery WWTPs. Pyrosequencing of 16S rRNA genes showed that Proteobacteria and Synergistetes dominated in the aerobic and anaerobic sludge, respectively. Ammonia-oxidizing bacteria (AOB amoA gene cloning revealed that Nitrosomonas europaea dominated the ammonia-oxidizing community in the WWTPs. Metagenomic analysis showed that the denitrifiers mainly included the genera of Thauera, Paracoccus, Hyphomicrobium, Comamonas and Azoarcus, which may greatly contribute to the nitrogen removal in the two WWTPs. It is interesting that AOB and ammonia-oxidizing archaea had low abundance although both WWTPs demonstrated high ammonium removal efficiency. Good correlation between the qPCR and metagenomic analysis is observed for the quantification of functional genes amoA, nirK, nirS and nosZ, indicating that the metagenomic approach may be a promising method used to comprehensively investigate the abundance of functional genes of nitrifiers and denitrifiers in the environment.

  10. Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land-use.

    Science.gov (United States)

    Keil, Daniel; Niklaus, Pascal A; von Riedmatten, Lars R; Boeddinghaus, Runa S; Dormann, Carsten F; Scherer-Lorenzen, Michael; Kandeler, Ellen; Marhan, Sven

    2015-07-01

    Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity. PMID:26092950

  11. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR).

    Science.gov (United States)

    Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

    2016-01-01

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10-50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera. PMID:26983801

  12. Kinetics of p-aminoazobenzene degradation by Bacillus subtilis under denitrifying conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zissi, U.S.; Kornaros, M.E.; Lyberatos, G.C.

    1999-05-01

    Bacillus subtilis is an organism capable of degrading an azo dye, such as p-aminoazobenzene (pAAB), under both aerobic and anoxic conditions. In both cases, pAAB is co-metabolized with a main carbon source and under anoxic conditions denitrification is observed. Kinetic experiments were carried out with a pure culture of B. subtilis and a mathematical model that accurately describes both biodegradation of pAAB under anoxic conditions and the denitrification process under both carbon- and nitrate- or nitrite-limited conditions is developed. Presence of pAAB in culture medium causes an inhibition of bacterial growth and of nitrite accumulation. Bacterial growth and pAAB degradation rates are found to be slower under anoxic conditions compared to the corresponding rates under aerobic conditions.

  13. Uranium enrichment: technology, economics, capacity

    International Nuclear Information System (INIS)

    Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R and D efforts on various processes

  14. Study on Tolerance and Enrichment Characteristics of Sedum alfredii Hance to Cd in Soil Culture%土培条件下东南景天对镉的耐性和富集特性的研究

    Institute of Scientific and Technical Information of China (English)

    熊愈辉

    2011-01-01

    [Objective] To reveal the differences of tolerance and uptake characteristics of cadmium in soil between mined ecotype and nonmined plants of 5. Alfredii. [ Method ] Using pot culture, different amount of Cd were put into soil as treatment, to study the growth responses of two ecotypes plants of S. Alfredii in soil with different Cd content and the change of Cd content and accumulation. [ Result] The growth responses were different obviously between the two plants. The tolerance threshold of mined ecotype S. Alfredii to Cd was 300 rag/kg, and the non-mined ecotype was SO mg/kg. Maximum Cd concentrations reached 893 rag/kg in shoots and 344 mg/kg in roots of the mined ecotype plant respectively; while the maximum Cd concentration in shoots was 124 mg/kg, the root was 212 mg/kg for the non-mined ecotype plant. Cd concentration in shoots was higher than roots for the mined ecotype, whereas Cd concentration was always lower in shoots than in roots for the non-mined ecotype. The Cd accumulation in shoots of the mined ecotype reached the maximum of 151.67 μ/plant, while the non-mined ecotype reached 11.99 μg/plant. Compare the two ecotypes of 5. Alfredii, concentration and accumulation of Cd in shoots of the mined ecotype was obviously higher than the non-mined ecotype in same content treatment of Cd in soil. [Conclusion] Cd tolerance and accumulation of the mined ecotype of S. Alfredii is remarkably more than the non-mining ecotype. The mined ecotype of S. Alfredii is a Cd hyperaccumulator.%[目的] 探讨土培条件下东南景天矿山与非矿山生态型植物对Cd耐性和富集能力的差异.[方法] 采用土培盆栽的方法,以向水稻土中加入不同量的镉作为处理,研究东南景天两种生态型植物在不同镉含量土壤中的生长反应以及体内镉含量与积累量变化.[结果] 两种生态型植物对土壤中不同含量Cd的生长反应不同,矿山生态型对土壤Cd的耐受阈值为300 mg/kg,非矿山生态型为50mg/kg.矿

  15. 污水处理厂反硝化除磷研究及实践%Study and application of denitrifying phosphorus removal in wastewater treatment plant

    Institute of Scientific and Technical Information of China (English)

    吴魏刚

    2011-01-01

    结合苏州娄江污水处理厂生产运行实践,研究了改良型一体化交替反应池在实现良好反硝化除磷条件下的运行工况.实践表明,提高反硝化除磷的关键是要有充足的硝酸盐氮为反硝化聚磷菌(DPB)提供电子受体,当NO-2N浓度在5 mg/L以上时,可以实现较好的反硝化除磷;当SRT为12~14 d时,反硝化除磷和系统脱氮除磷效果最好,生物除磷运行成本较低.此外,进水COD/TP、好氧池DO、厌氧池MLSS以及SRT也是影响一体化反应池生物除磷的主要因素.针对雨季低负荷运行除磷效果不理想的现象,提出了相应的工况运行措施.%Based on the practical operation of the Suzhou Loujiang Wastewater Treatment Plant, the operating condition of improved all-in-one alternate reaction tank in well denitrifying phosphorus removing condition was studied. The practice results showed: the key points to improve denitrifying phosphorus removal lied in offering enough chlorate as electron acceptor for denitrifying phosphorus bacteria (DPB); when the NO3--N concentration was above 5 mg/L, relatively good denitrifying phosphorus removal could be achieved. The best denitrifying phosphorus removal and system nitrogen and phosphorus removal could be achieved when SRT was 12~ 14 days, and the bio-phosphorus removal operation cost was low. The results also showed that influent COD/TP ratio,aerobic reaction tank DO, anaerobic tank MLSS and SRT were also main factors on all-in-one reaction tank bio-phosphorus removal effects. According to the unsatisfying low-loading phosphorus removal effects in rainy season, relating operation measures were also brought forward.

  16. Enrichment of light hydrocarbon mixture

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dali (Los Alamos, NM); Devlin, David (Santa Fe, NM); Barbero, Robert S. (Santa Cruz, NM); Carrera, Martin E. (Naperville, IL); Colling, Craig W. (Warrenville, IL)

    2011-11-29

    Light hydrocarbon enrichment is accomplished using a vertically oriented distillation column having a plurality of vertically oriented, nonselective micro/mesoporous hollow fibers. Vapor having, for example, both propylene and propane is sent upward through the distillation column in between the hollow fibers. Vapor exits neat the top of the column and is condensed to form a liquid phase that is directed back downward through the lumen of the hollow fibers. As vapor continues to ascend and liquid continues to countercurrently descend, the liquid at the bottom of the column becomes enriched in a higher boiling point, light hydrocarbon (propane, for example) and the vapor at the top becomes enriched in a lower boiling point light hydrocarbon (propylene, for example). The hollow fiber becomes wetted with liquid during the process.

  17. A Systematic Approach to Marital Enrichment.

    Science.gov (United States)

    Dinkmeyer, Don; Carlson, Jon

    1986-01-01

    Presents a systematic approach to enriching marital relationships. The history and current status of marital enrichment is reviewed. An Adlerian approach to marital enrichment is described. Applications of the program in enrichment groups, marriage therapy and couple groups are included. (Author)

  18. Advances in uranium enrichment processes

    International Nuclear Information System (INIS)

    Advances in gas centrifuges and development of the atomic vapour laser isotope separation process promise substantial reductions in the cost of enriched uranium. The resulting reduction in LWR fuel costs could seriously erode the economic advantage of CANDU, and in combination with LWR design improvements, shortened construction times and increased operational reliability could allow the LWR to overtake CANDU. CANDU's traditional advantages of neutron economy and high reliability may no longer be sufficient - this is the challenge. The responses include: combining neutron economy and dollar economy by optimizing CANDU for slightly enriched uranium fuel; developing cost-reducing improvements in design, manufacture and construction; and reducing the cost of heavy water. Technology is a renewable resource which must be continually applied to a product for it to remain competitive in the decades to come. Such innovation is a prerequisite to Canada increasing her share of the international market for nuclear power stations. The higher burn-up achievable with enriched fuel in CANDU can reduce the fuel cycle costs by 20 to 40 percent for a likely range of costs for yellowcake and separative work. Alternatively, some of the benefits of a higher fissile content can take the form of a cheaper reactor core containing fewer fuel channels and less heavy water, and needing only a single fuelling machine. An opportunity that is linked to this need to introduce an enriched uranium fuel cycle into CANDU is to build an enrichment business in Canada. This could offer greater value added to our uranium exports, security of supply for enriched CANDUs, technological growth in Canada and new employment opportunities. AECL has a study in progress to define this opportunity

  19. Biomedical advances from tissue culture

    OpenAIRE

    Okamoto, Tetsuji; Sato, J. Denry; Barnes, David W.; Sato, Gordon H.

    2013-01-01

    The demonstration that the “dedifferentiation” of cells commonly observed in the early days of tissue culture was due to selective overgrowth of fibroblasts led to enrichment culture techniques (alternate animal and culture passage) designed to give a selective advantage to functionally differentiated tumor cells. These experiments resulted in the derivation of a large number of functionally differentiated clonal strains of a range of cell types. These results gave rise to the hypothesis that...

  20. Tissue culture: the unrealized potential

    OpenAIRE

    Sato, Gordon

    2007-01-01

    Lack of differentiated functions of the tissue of origin in tissue culture thought to be due to dedifferentiation was shown to be due to selective overgrowth of fibroblasts. Enrichment culture techniques, (alternate animal and culture passage), designed to give the functionally differentiated cells selective advantage over the fibroblasts resulted in a large number of functionally differentiated clonal strains. Thus the dogma of dedifferentiation was destroyed. It is proposed to substitute th...

  1. Uranium enrichment. 1980 annual report

    International Nuclear Information System (INIS)

    This report contains data and related information on the production of enriched uranium at the gaseous diffusion plants and an update on the construction and project control center for the gas centrifuge plant. Power usage at the gaseous diffusion plants is illustrated. The report contains several glossy color pictures of the plants and processes described. In addition to gaseous diffusion and the centrifuge process, three advanced isotope separation process are now being developed. The business operation of the enrichment plants is described; charts on revenue, balance sheets, and income statements are included

  2. Marinobacter strain NNA5, a newly isolated and highly efficient aerobic denitrifier with zero N2O emission.

    Science.gov (United States)

    Liu, Ying; Ai, Guo-Min; Miao, Li-Li; Liu, Zhi-Pei

    2016-04-01

    An efficient aerobic denitrification bacterium, strain NNA5, was isolated and identified as Marinobacter sp. NNA5. NNA5 did not perform heterotrophic nitrification. GC/IRMS analysis revealed that (15)N2 was produced from Na(15)NO2 and K(15)NO3. GC/MS and quantitative analyses showed that no N2O emission occurred when nitrite or nitrate was used as substrate. Single factor experiments indicated that optimal conditions for aerobic denitrification were: sodium succinate or sodium pyruvate as carbon source, temperature 35 °C, NaCl concentration 2-4%, C/N ratio 6-8, pH 7.5, rotation speed 150 rpm (giving dissolved oxygen concentration 6.08 mg/L), NO3(-)-N concentration ranging from 140 to 700 mg/L. NNA5 displayed highly efficient aerobic denitrifying ability, with maximal NO3(-)-N removal rate 112.8 mg/L/d. In view of its ability to perform aerobic denitrification with zero N2O emission, NNA5 has great potential for future application in aerobic denitrification processes in industrial and aquaculture wastewater treatment systems. PMID:26836845

  3. Functional bacteria and process metabolism of the Denitrifying Sulfur conversion-associated Enhanced Biological Phosphorus Removal (DS-EBPR) system: An investigation by operating the system from deterioration to restoration.

    Science.gov (United States)

    Guo, Gang; Wu, Di; Hao, Tianwei; Mackey, Hamish Robert; Wei, Li; Wang, Haiguang; Chen, Guanghao

    2016-05-15

    A sulfur conversion-associated Enhanced Biological Phosphorus (P) Removal (EBPR) system is being developed to cater for the increasing needs to treat saline/brackish wastewater resulting from seawater intrusion into groundwater and sewers and frequent use of sulfate coagulants during drinking water treatment, as well as to meet the demand for eutrophication control in warm climate regions. However, the major functional bacteria and metabolism in this emerging biological nutrient removal system are still poorly understood. This study was thus designed to explore the functional microbes and metabolism in this new EBPR system by manipulating the deterioration, failure and restoration of a lab-scale system. This was achieved by changing the mixed liquor suspended solids (MLSS) concentration to monitor and evaluate the relationships among sulfur conversion (including sulfate reduction and sulfate production), P removal, variation in microbial community structures, and stoichiometric parameters. The results show that the stable Denitrifying Sulfur conversion-associated EBPR (DS-EBPR) system was enriched by sulfate-reducing bacteria (SRB) and sulfide-oxidizing bacteria (SOB). These bacteria synergistically participated in this new EBPR process, thereby inducing an appropriate level of sulfur conversion crucial for achieving a stable DS-EBPR performance, i.e. maintaining sulfur conversion intensity at 15-40 mg S/L, corresponding to an optimal sludge concentration of 6.5 g/L. This range of sulfur conversion favors microbial community competition and various energy flows from internal polymers (i.e. polysulfide or elemental sulfur (poly-S(2-)/S(0)) and poly-β-hydroxyalkanoates (PHA)) for P removal. If this range was exceeded, the system might deteriorate or even fail due to enrichment of glycogen-accumulating organisms (GAOs). Four methods of restoring the failed system were investigated: increasing the sludge concentration, lowering the salinity or doubling the COD

  4. New primers for detecting and quantifying denitrifying anaerobic methane oxidation archaea in different ecological niches.

    Science.gov (United States)

    Ding, Jing; Ding, Zhao-Wei; Fu, Liang; Lu, Yong-Ze; Cheng, Shuk H; Zeng, Raymond J

    2015-11-01

    The significance of ANME-2d in methane sink in the environment has been overlooked, and there was no any study evaluating the distribution of ANME-2d in the environment. New primers were thus needed to be designed for following research. In this paper, a pair of primers (DP397F and DP569R) was designed to quantify ANME-2d. The specificity and amplification efficiency of this primer pair were acceptable. PCR amplification of another pair of primers (DP142F and DP779R) generated a single, bright targeted band from the enrichment sample, but yielded faint, multiple bands from the environmental samples. Nested PCR was conducted using the primers DP142F/DP779R in the first round and DP142F/DP569R in the second round, which generated a bright targeted band. Further phylogenetic analysis showed that these targeted bands were ANME-2d-related sequences. Real-time PCR showed that the copies of the 16s ribosomal RNA gene of ANME-2d in these samples ranged from 3.72 × 10(4) to 2.30 × 10(5) copies μg(-1) DNA, indicating that the percentage of ANME-2d was greatest in a polluted river sample and least in a rice paddy sample. These results demonstrate that the newly developed real-time PCR primers could sufficiently quantify ANME-2d and that nested PCR with an appropriate combination of the new primers could successfully detect ANME-2d in environmental samples; the latter finding suggests that ANME-2d may spread in environments. PMID:26300291

  5. Meadow enriched ACP process algebras

    NARCIS (Netherlands)

    J.A. Bergstra; C.A. Middelburg

    2009-01-01

    We introduce the notion of an ACP process algebra. The models of the axiom system ACP are the origin of this notion. ACP process algebras have to do with processes in which no data are involved. We also introduce the notion of a meadow enriched ACP process algebra, which is a simple generalization o

  6. Environmental Development Plan: uranium enrichment

    International Nuclear Information System (INIS)

    This Environmental Development Plan identifies and examines the environmental, health, safety, and socioeconomic concerns and corresponding requirements associated with the DOE research, development, demonstration, and operation of the Uranium Enrichment program, including the gaseous diffusion process, the centrifuge process, centrifuge rotor fabrication, and related research and development activities

  7. On enrichment way and characteristic features of typical DPB strains in a new species of A/O/A/O-SBR%新型A/O/A/O-SBR中DPB的富集及其典型菌株特性研究

    Institute of Scientific and Technical Information of China (English)

    胡筱敏; 杨辉

    2012-01-01

    为能更好地达到同步除磷脱氮的目的,对反硝化聚磷菌( Denitrifying Phosphorus Removal Bacteria,DPB)进行了富集培养,并对其中的典型菌株进行了特性研究.以校园生活区污水为研究对象,在温度为25℃,pH值为7.5,乙酸钠为碳源,进水COD为316.5 mg/L的条件下,采用三阶段的污泥驯化,对反硝化聚磷菌种进行了分离纯化,并对富集的典型菌株进行了生理生化试验、吸磷试验、硝酸盐还原产气试验.结果表明,富集培养后的DPB在A/O/A/O-SBR系统(厌氧2h,好氧1.5h,缺氧1.5 h,后置曝气0.5h)中成为优势菌群,系统中COD、NH4+-N、TN、TP的出水质量浓度分别为28.35 mg/L、0.87 mg/L、4.05mg/L和0.37 mg/L.分离鉴定出具有反硝化除磷能力的Z7、Z9两株典型菌株,其吸磷率均在50%左右.经细菌形态观察、生理特性分析及16S rDNA序列测定,鉴定Z7、Z9为缺氧反硝化聚磷菌,与假单胞菌(Pseudomonas)最相似,其同源性均达99.9%.%The present paper pursues a study of the enrichment way and characteristic features of typical DPB strains in a new species of A/O/A/O - SBR. The research urgency has come down to us is that in recent years, the land freshwater quality has been worsening than before due to the serious water eutrophication and greater nitrogen and phosphorus content in the sewage, which makes it an essential problem for water quality control. To achieve the synchronous phosphorus removal and dcnitrification, the present paper is dedicated to the study of the accumulation culture of the denitrifying phosphorus removal bacteria (DPB) and the characteristic features of the typical strains in a new species of anaerobic/aerobic/anoxic/aerobic SBR. In our study, we have done purifying treatment of the sewage of campus living area and conducted experiment with the carbon source of sodium acetate with the mass density of the water inlet of COD of 316.5 mg/L in an Sequencing Batch Reactor at the temperature of 25

  8. Phylogenetic and functional diversity within toluene-degrading, sulphate-reducing consortia enriched from a contaminated aquifer.

    Science.gov (United States)

    Kuppardt, Anke; Kleinsteuber, Sabine; Vogt, Carsten; Lüders, Tillmann; Harms, Hauke; Chatzinotas, Antonis

    2014-08-01

    Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers.

  9. Succession of Denitrifying Community Composition in Coastal Wetland Soils Along a Salinity Gradient

    Institute of Scientific and Technical Information of China (English)

    PIAO Zhe; ZHANG Wen-Wen; MA Shuai; LI Yu-Min; YIN Shi-Xue

    2012-01-01

    To better understand the effect of salinity on denitrification communities,soils along a salinity gradient (ranging from 7.32 to 1.70 mS cm-1) in a wetland along the Yellow Sea coastline in Jiangsu Province,China,were studied using both culture-dependent and -independent methods.Culture efforts yielded 82 isolates in total,81.7% of which were close relatives of Bacillus sp.based on partial sequences of their 16S rRNA genes.Denaturing gradient gel electrophoresis (DGGE) analysis based on 16S rRNA sequences suggested possible existence of bacterial community succession along the salinity gradient.Clone library analysis based on nosZ gene sequences (coding nitrous oxide reductase) showed that operational taxonomic units (OTUs) associated with α-proteobacteria dominated in all three soils,whereas those associated with β-and γ-subdivisions showed a clear succession.In the high salinity soil,only the OTUs associated with α-subdivision were found.In the medium salinity soil,small proportions ofβ- (6.5%) and γ-associated (19.6%) OTUs were found.In the low salinity soil,the proportions were further increased to 33% and 25% for β- and γ-Proteobacteria,respectively.Statistic analysis using Unifrac P test showed that nosZ-communities in different saline soils were significantly different from each other.It could be concluded that α-subdivision of nosZ-community tended to be sustained in high salinity environments whereas β- and γ-subdivisions,especially the former,tended to be sustained in low salinity environments.Salinity was the key determinant of nosZ-community composition in the environment.

  10. Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria

    Directory of Open Access Journals (Sweden)

    T. Yamazaki

    2013-10-01

    Full Text Available Nitrous oxide (N2O is a potent greenhouse gas and produced in denitrification and nitrification in environmental nitrogen cycle by various microorganism. Site preference (SP of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathway. To determine representative SP value for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO purified from two species of ammonia oxidizing bacteria (AOB, Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR from Paracoccus denitrificans, respectively. The SP value for NOR reaction (−5.9 ± 2.1‰ showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰ was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2– reduction (which is followed by NO reduction to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for NH2OH oxidation pathway possibly due to a small contribution of NO2– reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

  11. Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria

    Science.gov (United States)

    Yamazaki, T.; Hozuki, T.; Arai, K.; Toyoda, S.; Koba, K.; Fujiwara, T.; Yoshida, N.

    2014-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification by various microorganisms. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathways. To determine representative SP values for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans. The SP value for NOR reaction (-5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2-) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for the NH2OH oxidation pathway possibly due to a small contribution of NO2- reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

  12. Cultural Enrichment: Connecting African American Elementary Children to Academic Achievement

    Science.gov (United States)

    Winston, Deborah L.

    2011-01-01

    A large, growing number of mis-educated American citizens are being produced by America's public schools. Many of these students are being funneled into the penal system shortly after dropping out of high school. This phenomenon is especially prevalent among African American male students, many of whom have withdrawn academically years prior…

  13. Resource recovery from organic waste streams by microbial enrichment cultures

    NARCIS (Netherlands)

    Tamis, J.

    2015-01-01

    Polyhydroxyalkanoate (PHA) is a natural product that can potentially replace a part of the chemicals and plastics derived from fossil sources. One of the main barriers for market entry of PHA is its relatively high price compared to conventional (fossil) feedstocks. This high price is related to cur

  14. Mixing Intensity Effects of Attached Growth on Enriched Anammox Cultures

    Directory of Open Access Journals (Sweden)

    Pongsak Noophan

    2015-01-01

    Full Text Available Anaerobic ammonium oxidation (anammox is a promising new technology for the treatment of wastewater with high ammonium and low carbon concentrations. Earlier work suggests that optimal processing would be realized within a sequencing batch reactor (SBR. However, the relatively slow growth of anammox bacteria inhibits the rates of nitrogen removal and biomass yielding. Improved anammox performance has been demonstrated when the bacteria are in granular form or attached to a growth medium. Little has been reported concerning the effect of mixing rate on nitrogen (N removal with attached anammox bacteria. This work subjected anammox bacteria attached to polystyrene sponge in SBR to various intensities of impeller mixing and studied the effect on NH4+ and NO2- removal. Nitrogen processing was virtually the same with velocity gradient values between 13.5 and 222 s-1. More vigorous mixing at 407 and 666 s-1 values significantly inhibited N removal, likely due to detachment of bacteria from the growth medium. Following the poor N removal at the two higher mixing intensities, agitation was reduced to 24.8 s-1 velocity gradient value. Recovery of N removal rates required 2-3 weeks, the slow time attributed to slow reattachment to the growth medium. Denaturing gradient gel electrophoresis (DGGE analysis identified the prominent anammox species in the experimental study as Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis.

  15. Influences of Quinclorac on Culturable Microorganisms and Soil Respiration in Flooded Paddy Soil

    Institute of Scientific and Technical Information of China (English)

    ZHEN-MEI LU; HANG MIN; YANG-FANG YE

    2003-01-01

    Objective To investigate the potential effects of herbicide quinclorac (3,7-dichloro-8-quinoline-carboxylic) on the culturable microorganisms in flooded paddy soil. Methods Total soil aerobic bacteria, actinomycetes and fungi were counted by a 10-fold serial dilution plate technique. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN)methods with anaerobic liquid enrichment media. The number of methanogenic bacteria (MB) and nitrogen-fixing bacteria (NFB) was determined by the rolling tube method in triplicate. Soil respiration was monitored by a 102G-type gas chromatography with a stainless steel column filled with GDX-104 and a thermal conductivity detector. Results Quinclorac concentration was an important factor affecting the populations of various culturable microorganisms. There were some significant differences in the aerobic heterotrophic bacteria. AFB and DNB between soils were supplemented with quinclorac and non-quinclorac at the early stage of incubation, but none of them was persistent. The number of fungi and DNB was increased in soil samples treated by lower than1.33 μg·g-1 dried soil, while the CFU of fungi and HPAB was inhibited in soil samples treated by higher than 1.33 μg·g-1 dried soil. The population of actinomycete declined in negative proportion to the concentrations of quinclorac applied after 4 days. However, application of quinclorac greatly stimulated the growth of AFB and NFB. MB was more sensitive to quinclorac than the others, and the three soil samples with concentrations higher than 1 μg·g-1 dried soil declined significantly to less than 40% of that in the control, but the number of samples with lower concentrations of quinclorac was nearly equal to that in the control at the end of experiments. Conclusion Quinclorac is safe to the soil microorganisms when applied at normal

  16. Selective Enrichment of a Methanol-Utilizing Consortium Using Pulp and Paper Mill Waste Streams

    Science.gov (United States)

    Mockos, Gregory R.; Smith, William A.; Loge, Frank J.; Thompson, David N.

    Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater. Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Wasteactivated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensate system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25°C with a hydraulic residence time and a solids retention time of 4 days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24-h feed/ decant cycles ranged from 79 to 89%, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste-activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen-limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen-limited conditions. This indicates that selectively enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.

  17. Job enrichment in job design.

    Science.gov (United States)

    Bobeng, B J

    1977-03-01

    For optimal operation in labor-intensive industries, such as foodservice, not only scientific management principles but also behavioral aspects (the people) must be considered in designing job content. Three psychologic states--work that is meaningful, responsibility for outcomes, and knowledge of outcomes--are critical in motivating people. These, in turn encompass the core dimensions of skill variety, task identity, task significance, autonomy, and feedback. Job enrichment and job enlargement--related but not identical means of expanding job content--when combined, offer the likelihood of redesigned jobs in the core dimensions. Effective implementation of a job enrichment program hinges on diagnosing problems in the work system, actual changes in the work, and systematic evaluation of the changes. The importance of the contribution of the behavioral sciences to management cannot be neglected.

  18. Real-time PCR assay for the simultaneous quantification of nitrifying and denitrifying bacteria in activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Geets, J.; Cooman, M. de; Wittebolle, L.; Verstraete, W.; Boon, N. [Ghent Univ. (BE). Lab. of Microbial Ecology and Technology (LabMET); Heylen, K.; Vanparys, B.; Vos, P. de [Ghent Univ. (Belgium). Dept. of Biochemistry, Physiology and Microbiology

    2007-05-15

    In order to improve wastewater treatment processes, a need exists for tools that rapidly give detailed insight into the community structure of activated sludge, supplementary to chemical and physical data. In this study, the advantages of microarrays and quantitative polymerase chin reaction (PCR) methods were combined into a real-time PCR assay that allows the simultaneous quantification of phylogenetic and functional genes involved in nitrification and denitrification processes. Simultaneous quantification was possible along a 5-log dynamic range and with high linear correlation (R{sup 2}>0.98). The specificity of the assay was confirmed by cloning and sequencing analyses of PCR amplicons obtained from activated sludge. The real-time assay was validated on mixed liquid samples of different treatment plants, which varied in nitrogen removal rate. The abundance of ammonia oxidizers was in the order of magnitude of 10{sup 6} down to 10{sup 4} ml{sup -1}, whereas nitrite oxidizers were less abundant (10{sup 3}-10{sup 1} order of magnitude). The results were in correspondence with the nitrite oxidation rate in the sludge types. As for the nirS, nirK, and nosZ gene copy numbers, their abundance was generally in the order of magnitude of 10{sup 8}-10{sup 5}. When sludge samples were subjected to lab-scale perturbations, a decrease in nitrification rate was reflected within 18 h in the copy numbers of nitrifier genes (decrease with 1 to 5 log units), whereas denitrification genes remained rather unaffected. These results demonstrate that the method is a fast and accurate tool for the analysis of the (de)nitrifying community structure and size in both natural and engineered environmental samples. (orig.)

  19. Degradation pathway of quinolines in a biofilm system under denitrifying conditions

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, S.S.; Arvin, E.; Mosbaek, H. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Environmental Science and Engineering; Hansen, A.B. [National Environmental Research Inst., Roskilde (Denmark). Dept. of Environmental Chemistry

    1997-09-01

    This article reports for the first time the degradation pathways of quinoline, isoquinoline, and methylquinolines by a mixed culture in a biofilm under nitrate-reducing conditions. A simple reverse-phase high-performance liquid chromatography method using ultraviolet detection at 223 nm for determination of seven quinoline analogues and 15 metabolites was developed, and gas chromatography--mass spectrometry and thin-layer chromatography analyses were used for identification. The inhibition of nitrification by the parent compounds and their degradation products was assessed by a nitrification toxicity test called MINNTOX. Quinoline and 3-, 4-, 6-, and 8-methylquinoline were all transformed by hydroxylation into their 2-hydroxyquinoline analogues (2-quinolinones), and isoquinoline was transformed into 1-hydroxyisoquinoline. 2-Methylquinoline was not transformed by this microcosm, likely due to the blockage at position 2 by the methyl group. The hydroxylated metabolites of isoquinoline and quinolines methylated at the heterocyclic ring were not transformed further, whereas metabolites of quinoline and quinolines methylated at the homocyclic ring were hydrogenated at position 3 and 4, and the resulting 3,4-dihydro-2-quinolinone analogues accumulated. Of these metabolites, only 3,4-dihydro-2-quinolinone from the degradation of quinoline was further transformed into unidentified products. All quinolines and their metabolites had inhibiting effects on the nitrifying bacteria at the same level (ppm) in the applied bioassay, indicating that the inhibition of the compounds was not influenced by the initial transformation reactions.

  20. Effect of dissolved oxygen on nitrate removal using polycaprolactone as an organic carbon source and biofilm carrier in fixed-film denitrifying reactors.

    Science.gov (United States)

    Luo, Guozhi; Xu, Guimei; Gao, Jinfang; Tan, Hongxin

    2016-05-01

    Nitrate-nitrogen (NO3(-)-N) always accumulates in commercial recirculating aquaculture systems (RASs) with aerobic nitrification units. The ability to reduce NO3(-)-N consistently and confidently could help RASs to become more sustainable. The rich dissolved oxygen (DO) content and sensitive organisms stocked in RASs increase the difficulty of denitrifying technology. A denitrifying process using biologically degradable polymers as an organic carbon source and biofilm carrier was proposed because of its space-efficient nature and strong ability to remove NO3(-)-N from RASs. The effect of dissolved oxygen (DO) levels on heterotrophic denitrification in fixed-film reactors filled with polycaprolactone (PCL) was explored in the current experiment. DO conditions in the influent of the denitrifying reactors were set up as follows: the anoxic treatment group (Group A, average DO concentration of 0.28±0.05mg/L), the low-oxygen treatment DO group (Group B, average DO concentration of 2.50±0.24mg/L) and the aerated treatment group (Group C, average DO concentration of 5.63±0.57mg/L). Feeding with 200mg/L of NO3(-)-N, the NO3(-)-N removal rates were 1.53, 1.60 and 1.42kg/m(3) PCL/day in Groups A, B and C, respectively. No significant difference in NO3(-)-N removal rates was observed among the three treatments. It was concluded that the inhibitory effects of DO concentrations lower than 6mg/L on heterotrophic denitrification in the fixed-film reactors filled with PCL can be mitigated. PMID:27155419

  1. Boron Enrichment in Martian Clay

    OpenAIRE

    James D Stephenson; Lydia J Hallis; Kazuhide Nagashima; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest minera...

  2. Enrichment of lanthanides in aragonite

    Institute of Scientific and Technical Information of China (English)

    瞿成利; 路波; 刘刚

    2009-01-01

    Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were determined by inductive coupled plasma mass spectrometer.All these lanthanides were strongly enriched in aragonite overgrowths.The amount of lanthanum,gadolinium,and lutetium incorporated into aragonite accounted for 57%-99%,50%-89%,and 40%-91% of their initial total amount,respectively.With the in...

  3. Environmental signatures of enrichment facilities

    International Nuclear Information System (INIS)

    Environmental sampling is a potentially useful tool that could be used for the detection of undeclared enrichment facilities. However, this would be likely to require the use of sophisticated and expensive analytical techniques to evaluate 235U/238U ratios. It would be, therefore, unlikely to be an inexpensive approach to detect proliferation. The probability of detecting an enrichment operation will depend on the type of facility. A gaseous diffusion operation will be relatively difficult to detect in relation to an EMIS facility and a gaseous centrifuge plant will be more difficult still. Releases from an enrichment operation are likely to be restricted to atmospheric discharges. Aquatic discharges would be relatively easy to contain and it would be unwise to devise a sampling strategy based on the measurement of these. The detection of atmospheric discharges is likely to be dependent on meteorological conditions, in particular stability. Stable atmospheric conditions are the most favourable for detecting releases at significant distances from the plant. Given stable conditions, detection of an EMIS facility might be possible at a distance of several 10s of km

  4. Enrichment and aggression in primates.

    Science.gov (United States)

    Honess, P E; Marin, C M

    2006-01-01

    There is considerable evidence that primates housed under impoverished conditions develop behavioural abnormalities, including, in the most extreme example, self-harming behaviour. This has implications for all contexts in which primates are maintained in captivity from laboratories to zoos since by compromising the animals' psychological well-being and allowing them to develop behavioural abnormalities their value as appropriate educational and research models is diminished. This review examines the extensive body of literature documenting attempts to improve living conditions with a view to correcting behavioural abnormalities and housing primates in such a way that they are encouraged to exhibit a more natural range and proportion of behaviours, including less self-directed and social aggression. The results of housing, feeding, physical, sensory and social enrichment efforts are examined with specific focus on their effect on aggressive behaviour and variation in their use and efficacy. It is concluded that while inappropriate or poorly distributed enrichment may encourage aggressive competition, enrichment that is species, sex, age and background appropriate can dramatically reduce aggression, can eliminate abnormal behaviour and substantially improve the welfare of primates maintained in captivity.

  5. Community Structure Evolution and Enrichment of Glycogen-Accumulating Organisms Producing Polyhydroxyalkanoates from Fermented Molasses▿

    OpenAIRE

    Pisco, Ana R.; Bengtsson, Simon; Werker, Alan; Reis, Maria A. M.; Lemos, Paulo C.

    2009-01-01

    An open mixed culture was enriched with glycogen-accumulating organisms (GAOs) by using a sequencing batch reactor and treating an agroindustrial waste (sugar cane molasses) under cyclic anaerobic-aerobic conditions. Over a 1-year operating period, the culture exhibited a very stable GAO phenotype with an average polyhydroxyalkanoate (PHA) content of 17% total suspended solids. However, the GAO microbial community evolved over the course of operation to a culture exhibiting unusual characteri...

  6. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

    OpenAIRE

    Mei Yu; Hui Lu; Di Wu; Qing Zhao; Fangang Meng; Yudan Wang; Xiaodi Hao; Guang-Hao Chen

    2016-01-01

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were ...

  7. Insights into the Effect of Soil pH on N2O and N2 Emissions and Denitrifier Community Size and Activity ▿

    OpenAIRE

    Čuhel, Jiří; Šimek, Miloslav; Laughlin, Ronnie J.; Bru, David; Chèneby, Dominique; Watson, Catherine J.; Philippot, Laurent

    2010-01-01

    The objective of this study was to investigate how changes in soil pH affect the N2O and N2 emissions, denitrification activity, and size of a denitrifier community. We established a field experiment, situated in a grassland area, which consisted of three treatments which were repeatedly amended with a KOH solution (alkaline soil), an H2SO4 solution (acidic soil), or water (natural pH soil) over 10 months. At the site, we determined field N2O and N2 emissions using the 15N gas flux method and...

  8. Job Enrichment and the Mentally Retarded Worker.

    Science.gov (United States)

    Morris, Jerry L.; And Others

    1981-01-01

    The effect of job enrichment on the production rate of 14 mentally retarded adult workers was evaluated. Job enrichment led to increases in standard rates of production for high IQ Ss and lower rates for low IQ Ss. (Author)

  9. Uranium enrichment (a strategy analysis overview)

    International Nuclear Information System (INIS)

    An analysis of available information on enrichment technology, separative work supply and demand, and SWU cost is presented. Estimates of present and future enrichment costs are provided for use in strategy analyses of alternate nuclear fuel cycles and systems. (auth)

  10. Enriched uranium sales: effect on supply industry

    International Nuclear Information System (INIS)

    The subject is covered in sections: introduction (combined effect of low-enriched uranium (LEU) inventory sales and utility services enrichment contract terms); enrichment market overview; enrichment market dynamics; the reaction of the US Department of Energy; elimination of artificial demand; draw down of inventories; purchase and sale of LEU inventories; tails assay option; unfulfilled requirements for U3O8; conclusions. (U.K.)

  11. NEAT: an efficient network enrichment analysis test

    OpenAIRE

    Signorelli, Mirko; Vinciotti, Veronica; Wit, Ernst C

    2016-01-01

    Background Network enrichment analysis is a powerful method, which allows to integrate gene enrichment analysis with the information on relationships between genes that is provided by gene networks. Existing tests for network enrichment analysis deal only with undirected networks, they can be computationally slow and are based on normality assumptions. Results We propose NEAT, a test for network enrichment analysis. The test is based on the hypergeometric distribution, which naturally arises ...

  12. Enriching Music and Language Arts Experiences

    Science.gov (United States)

    Flohr, John W.

    2006-01-01

    The article focuses on enriching music and language arts experiences of students. Music can enrich literature and language arts, poetry, theater arts, transitions, science, and math, as well as help meet special learner needs. A well-understood example of enrichment is the alphabet song. A music or classroom teacher using the alphabet song helps…

  13. How Did the IGM Become Enriched?

    CERN Document Server

    Aguirre, A; Aguirre, Anthony; Schaye, Joop

    2006-01-01

    The enrichment of the intergalactic medium with heavy elements is a process that lies at the nexus of poorly-understood aspects of physical cosmology. We review current understanding of the processes that may remove metals from galaxies, the basic predictions of these models, the key observational constraints on enrichment, and how intergalactic enrichment may be used to test cosmological simulations.

  14. Perspectives on Job Enrichment and Productivity.

    Science.gov (United States)

    Suojanen, Waino W., Ed.; And Others

    The book of reading focuses on the state of job enrichment in the United States today, as well as some of its international implications. Featured in the book are 20 selected working papers analyzing the development and use of job enrichment in various types of organizations, union response to job enrichment, and its outlook for the future. The…

  15. 污泥反硝化除磷-诱导磷结晶工艺中硝化池内的微生物特性%Characteristics of nitrifier in sludge denitrifying phosphorus removal and recovery process

    Institute of Scientific and Technical Information of China (English)

    邹海明; 吕锡武; 史静; 顾倩

    2013-01-01

    electron micrograph (SEM) and the software of Image-Pro Plus (IPP). In this process, the abundance of ammonia-oxidizing bacteria (AOB) responsible for the transformation of ammonia nitrogen to nitrite was significantly higher than that of nitrite-oxidizing bacteria (NOB) capable of the conversion of nitrite to nitrate. According to the FISH analysis, the proportion of AOB to total bacteria was 46.2%, while NOB was 28.5%. Generally, the AOB was close to the external layer of sludge granule while the NOB was in the internal layer. From SEM, the nitrifiers in the nitrification pond were typically coccus or short rods and preferably grown the dense clusters. The aggregates formed by the AOB were bigger than those of NOB tending to combine with several cells. Based on the three dimensional graphs of microstructures of nitrification sludge analyzed by using IPP software, it was found that the structure was density in the external layer, while that was loose in the internal layer and much void or hollows were found as well, which might be due to the difference of the abundance of microorganisms and the concentrations of nutrients and oxygen between the external and the internal. In conclusion, compared with the conventional single-sludge wastewater treatment processes, two-sludge denitrifying phosphorus removal processes have a great advantage to enrich the nitrifiers. Therefore, these results obtained here could be effective for optimization of process parameters or construction of pilot plant and design of wastewater treatment process responsible for nitrogen and phosphorus removal as well.

  16. Characteristics of nitrifier in sludge denitrifying phosphorus removal and recovery process%污泥反硝化除磷-诱导磷结晶工艺中硝化池内的微生物特性

    Institute of Scientific and Technical Information of China (English)

    邹海明; 吕锡武; 史静; 顾倩

    2013-01-01

    between the external and the internal. In conclusion, compared with the conventional single-sludge wastewater treatment processes, two-sludge denitrifying phosphorus removal processes have a great advantage to enrich the nitrifiers. Therefore, these results obtained here could be effective for optimization of process parameters or construction of pilot plant and design of wastewater treatment process responsible for nitrogen and phosphorus removal as well.%  为了探究双污泥系统下反硝化除磷-诱导磷结晶工艺中硝化池内微生物特性,该文利用原位荧光杂交(fluorescence in situ hybridization,FISH)技术、电子显微镜扫描(scanning electron micrograph,SEM)方法和Image-Pro Plus(IPP)软件考察了该工艺中硝化细菌的种群结构、形态和硝化污泥微观三维结构图.结果表明:该工艺中硝化池内氨氧化细菌(ammonia-oxidizing bacteria,AOB)数量要多于亚硝酸盐氧化细菌(nitrite-oxidizing bacteria,NOB),占总细菌的比例分别为46.2%,28.5%,且AOB处于污泥颗粒外层而NOB处于污泥颗粒内层,可能由于NOB利用AOB的代谢产物所致;工艺中硝化细菌多以球形或短杆菌为主,NOB生长时多以几个细胞形成小团聚体,而 AOB 生长时则形成大的团聚体;通过硝化污泥微观三维结构发现,污泥外层呈密实状而内层较疏松且有空洞存在,可能由于污泥外层和内层微生物的丰度差异、营养物质和溶解氧的浓度差异所致.此外,与传统的单污泥污水处理工艺相比,双污泥工艺明显地增强了硝化细菌的生长和富集能力.

  17. Ecophysiological and anatomical responses of Vallisneria natans to nitrogen and phosphorus enrichment

    OpenAIRE

    Wang Y; Gao G.; Qin B; Wang X

    2012-01-01

    Here, we describe an experiment using four nitrogen (N) and phosphorus (P) concentrations to investigate the effects of nutrient enrichment on the submersed macrophyte Vallisneria natans (tape grass) grown in a sand culture medium. The objective of this study was to examine the influence of nutrient enrichment in the water column on V. natans, especially with regard to anatomical structures. The results showed both the absolute growth rate (AGR) and intrinsic efficiency of light energy conver...

  18. Taking a systems-oriented view of phosphorous enrichment in fresh waters

    OpenAIRE

    Everard, Mark

    2001-01-01

    Eutrophication of fresh waters through anthropogenic enrichment by phosphorus is a global problem. The role of phosphorus enrichment in the formation of blooms of toxic blue-green algae (Cyanobacteria) in fresh waters is well established and of considerable concern in terms of human and animal health, loss of water resources and amenities, threats to fish stocks, and aesthetic considerations. Cultural eutrophication also poses threats to the ecosystem balance in fresh waters, with implication...

  19. Early stationary phase culture supernatant accelerates growth of sputum cultures collected after initiation of anti-tuberculosis treatment.

    Science.gov (United States)

    Kolwijck, E; Friedrich, S O; Karinja, M N; van Ingen, J; Warren, R M; Diacon, A H

    2014-07-01

    We investigated the effect of Mycobacterium tuberculosis culture supernatant added to sputum cultures collected during the first 8 weeks of anti-tuberculosis treatment. With ongoing treatment duration, time to culture positivity decreased significantly in supernatant-enriched cultures, possibly due to stimulation of dormant or slowly metabolizing M. tuberculosis cells.

  20. Enriching Orphans’ Potentials through Interpersonal and Intrapersonal Intelligence Enrichment Activities

    Directory of Open Access Journals (Sweden)

    Nurulwahida Hj Azid

    2016-01-01

    Full Text Available Orphans are considered a minority and they should be given a greater emphasis so that they do not feel left out and can build their own lives without a sense of humility. This does not mean that the orphans should be pampered instead they should be given the confidence and motivation to strive for success in later life. Humility among orphans can be associated with interpersonal and intrapersonal intelligences. This study aims to evaluate the impact of problem-solving activity treatment based on the interpersonal and intrapersonal intelligences. 46 students from two orphanages were involved as the treatment group. The research design used was a one-group pretest-posttest design applied through a combination of quantitative and qualitative approaches. Enrichment activities that provided interpersonal and intrapersonal skills as evidenced in this study should be carried out regularly at orphanages. Our study has proven that orphans‟ rights to learn cannot be neglected and „no child left behind „policy needs to be carried through by everybody involved with orphans‟ well-being. Teachers and carers need to be trained to use these enrichment activities at their orphanages to help maximize the orphans‟ potentials.

  1. EMIS: Enrichment Management Information System

    International Nuclear Information System (INIS)

    The objective of the effort was the development of a calculational tool which would permit DOE to make realistic projections of the separative work demands of its customers as an aid in planning for the future operation of the enrichment facilities. The calculational methods were to recognize the flexibility in scheduling, etc., available to DOE customers under their enrichment contreacts as well as the ability to pool separative work withdrawn under two or more contracts. It was also to be designed to permit the user to add new customers or delete existing contracts as well as to allow variation of the estimated start-up dates for those reactors currently under construction. The output of the model was to display projections of separative work demand as SWU and in triplet form for several categories of reactors. These included, in addition to the total demand on the enrichment complex, separate totals for domestic and foreign customers, for reactors with Requirements and Adjustable Fixed Commitment contracts and for reactors in operation, under construction and projected new reactors designated by the user. The foundations upon which the system is based are described in this report. This includes a discussion of the available alternatives for customer management of separative work and the assumptions and guidelines established for development of the model. The report also contains a description of the computational procedures used in the model, and a description of the EMIS system itself, which also serves as a users' manual for the code. Finally, samples demonstrating the use of the system and indicating the form of the input and output are included

  2. Enrichment planting without soil treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hagner, Mats

    1998-12-31

    Where enrichment planting had been carried out with either of the two species Picea abies and Pinus contorta, the survival of the planted seedlings was at least as good as after planting in a normal clear cut area treated with soil scarification. This was in spite of the fact that the seedlings were placed shallow in the humus layer without any soil treatment. However, they were sheltered from insects by treatment before planting. Where enrichment planting was carried out with Pinus sylvestris the survival in dense forest was poor, but in open forest the survival was good. The growth of planted seedlings was enhanced by traditional clearing and soil treatment. However, this was for Pinus sylvestris not enough to compensate for the loss of time, 1-2 years, caused by arrangement of soil scarification. The growth of seedlings planted under crown cover was directly related to basal area of retained trees. However, the variation in height growth among individual seedlings was very big, which meant that some seedlings grow well also under a fairly dense forest cover. The pioneer species Pinus sylvestris reacted more strongly to basal area of retained trees than did the shade tolerant species Picea abies. Enrichment planting seems to be a necessary tool for preserving volume productivity, at places where fairly intensive harvest of mature trees has been carried out in stands of ordinary forest type in central Sweden. If double seedlings, with one Picea abies and one Pinus sylvestris, are used, the probability for long term establishment is enhanced 13 refs, 20 figs, 4 tabs

  3. Boron enrichment in martian clay.

    Science.gov (United States)

    Stephenson, James D; Hallis, Lydia J; Nagashima, Kazuhide; Freeland, Stephen J

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  4. DOE enrichment plant hums ahead

    International Nuclear Information System (INIS)

    The Department of Energy's $10-billion gas centrifuge uranium enrichment plant, after three years of construction, is rising on schedule near Piketon, Ohio. A detailed conceptual design, smart management, liberal design fees, hungry contractors and cooperative unions are combining to get the job done. One reason for completing the task is that this will be a far more efficient process - 135 MW will be required to operate the centrifuge plant vs more than 2100 MW to produce the same amount of fuel at the mile-square diffusion plant near Portsmouth, Ohio

  5. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  6. Uranium enrichment plant risk analysis

    International Nuclear Information System (INIS)

    A method for risk analysis of enrichment facilities is presented and applied to a small scale ultracentrifuge plant. Internal events are identified and the consequences of accidental releases of U F6 are quantified in terms of its toxicological and radiological impact. It is shown that releases in the feed and the cascade areas offers no hazards to the public . Releases of liquefied U F6 in the withdrawal areas, associated with failures in the building isolation systems, may cause undesirable consequences. (author). 11 refs, 4 figs, 3 tabs

  7. Two-step nitrification in a pure moving bed biofilm reactor-membrane bioreactor for wastewater treatment: nitrifying and denitrifying microbial populations and kinetic modeling.

    Science.gov (United States)

    Leyva-Díaz, J C; González-Martínez, A; Muñío, M M; Poyatos, J M

    2015-12-01

    The moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) is a novel solution to conventional activated sludge processes and membrane bioreactors. In this study, a pure MBBR-MBR was studied. The pure MBBR-MBR mainly had attached biomass. The bioreactor operated with a hydraulic retention time (HRT) of 9.5 h. The kinetic parameters for heterotrophic and autotrophic biomasses, mainly nitrite-oxidizing bacteria (NOB), were evaluated. The analysis of the bacterial community structure of the ammonium-oxidizing bacteria (AOB), NOB, and denitrifying bacteria (DeNB) from the pure MBBR-MBR was carried out by means of pyrosequencing to detect and quantify the contribution of the nitrifying and denitrifying bacteria in the total bacterial community. The relative abundance of AOB, NOB, and DeNB were 5, 1, and 3%, respectively, in the mixed liquor suspended solids (MLSS), and these percentages were 18, 5, and 2%, respectively, in the biofilm density (BD) attached to carriers. The pure MBBR-MBR had a high efficiency of total nitrogen (TN) removal of 71.81±16.04%, which could reside in the different bacterial assemblages in the fixed biofilm on the carriers. In this regard, the kinetic parameters for autotrophic biomass had values of YA=2.3465 mg O2 mg N(-1), μm, A=0.7169 h(-1), and KNH=2.0748 mg NL(-1).

  8. Experimental and model-based evaluation of the role of denitrifying polyphosphate accumulating organisms at two large scale WWTPs in northern Poland.

    Science.gov (United States)

    Makinia, J; Rosenwinkel, K H; Swinarski, M; Dobiegala, E

    2006-01-01

    The capabilities of denitrifying Polyphosphate Accumulating Organisms (DPAOs) in two large-scale plants in northern Poland performing enhanced biological phosphorus removal (EBPR) were evaluated in this study. A series of batch tests with the process biomass aimed at the measurements of phosphate release (with artificial substrate and real wastewater) and subsequent phosphate uptake under anoxic/aerobic conditions. The process kinetics were predicted using ASM2d implemented in the GPS-X ver. 4.0.2 simulation package. The results from one experimental series (summer) were used for the model calibration, whereas the results from another series (spring) were used for the model validation. The model parameters were also accurately confirmed by predictions of the accompanying field measurements in the full-scale bioreactors. The experimental and simulation results revealed that a relatively small fraction of PAO could denitrify (eta(NO3,PAO) = 0.32). The denitrification rates associated with the anoxic storage of PP and the anoxic growth of PAO only constituted 16.0-21.0% of the denitrification rates associated with the anoxic activity of "ordinary" heterotrophs. PMID:17163015

  9. Advance of Research on the Technology of Nitrite-denitrifying Phosphorus Removal%亚硝化-反硝化除磷技术研究进展

    Institute of Scientific and Technical Information of China (English)

    叶丽红; 李冬; 张杰; 张金库; 曾辉平

    2016-01-01

    With nitrogen and phosphorus in water body caused the environmental problem, removal of the nitrogen and phosphorus in water body with low cost has become a challenge to the biological wastewater treatment worldwide. The technology of nitrite-denitrifying phosphorus removal has advantages of reducing carbon source consumption, saving occupied area, improving water treatment equipment utilization, and decreasing sludge production. But it remains unclear about the cognition of phosphorus accumulating organisms( PAOs) , and the stable operation of the whole technology that ammonia is reduced to nitrite and denitrifying phosphorus removal is not reported at present. Simultaneously, according to different researchers, PAOs has different classification, while the main results of the mechanism with short-cut denitrifying phosphorus removal are phosphate release and storage energy in anaerobic, then the energy supply for denitrifying phosphorus uptake with nitrite as the electron acceptor in anoxic. The effect of nitrogen and phosphorus removal is influenced by temperature, pH, the kind of carbon source, the value of ρ(C)/ρ(P) and other factors, so, in order to achieve the stable and efficient treatment of sewage wastewater, the reaction conditions of short-cut denitrifying phosphorus removal is necessarily reasonable. It is necessary to summerize the relevant research reported on the nitrite-denitrification and phosphorus removal to guide and overcome the disadvantages of the biological nitrogen and phosphorus removal.%氮磷引起的环境问题已引起世界关注,低成本减少水体氮磷污染是生物处理工艺面临的挑战。亚硝化-反硝化除磷工艺具有节约碳源和能源、节省空间及占地、提高水处理设备利用率、减少污泥产量等优势,但关于聚磷菌( PAOs)的认知缺乏深入了解,且目前尚未见氨氮亚硝化-反亚硝酸除磷整体工艺的稳定运行报道。关于PAOs的分类,不同研究者有不

  10. 亚硝化-反硝化除磷技术研究进展%Advance of Research on the Technology of Nitrite-denitrifying Phosphorus Removal

    Institute of Scientific and Technical Information of China (English)

    叶丽红; 李冬; 张杰; 张金库; 曾辉平

    2016-01-01

    With nitrogen and phosphorus in water body caused the environmental problem, removal of the nitrogen and phosphorus in water body with low cost has become a challenge to the biological wastewater treatment worldwide. The technology of nitrite-denitrifying phosphorus removal has advantages of reducing carbon source consumption, saving occupied area, improving water treatment equipment utilization, and decreasing sludge production. But it remains unclear about the cognition of phosphorus accumulating organisms( PAOs) , and the stable operation of the whole technology that ammonia is reduced to nitrite and denitrifying phosphorus removal is not reported at present. Simultaneously, according to different researchers, PAOs has different classification, while the main results of the mechanism with short-cut denitrifying phosphorus removal are phosphate release and storage energy in anaerobic, then the energy supply for denitrifying phosphorus uptake with nitrite as the electron acceptor in anoxic. The effect of nitrogen and phosphorus removal is influenced by temperature, pH, the kind of carbon source, the value of ρ(C)/ρ(P) and other factors, so, in order to achieve the stable and efficient treatment of sewage wastewater, the reaction conditions of short-cut denitrifying phosphorus removal is necessarily reasonable. It is necessary to summerize the relevant research reported on the nitrite-denitrification and phosphorus removal to guide and overcome the disadvantages of the biological nitrogen and phosphorus removal.%氮磷引起的环境问题已引起世界关注,低成本减少水体氮磷污染是生物处理工艺面临的挑战。亚硝化-反硝化除磷工艺具有节约碳源和能源、节省空间及占地、提高水处理设备利用率、减少污泥产量等优势,但关于聚磷菌( PAOs)的认知缺乏深入了解,且目前尚未见氨氮亚硝化-反亚硝酸除磷整体工艺的稳定运行报道。关于PAOs的分类,不同研究者有不

  11. Nitrogen removal and spatial distribution of denitrifier and anammox communities in a bioreactor for mine drainage treatment.

    Science.gov (United States)

    Herbert, Roger B; Winbjörk, Harry; Hellman, Maria; Hallin, Sara

    2014-12-01

    Mine drainage water may contain high levels of nitrate (NO3(-)) due to undetonated nitrogen-based explosives. The removal of NO3(-) and nitrite (NO2(-)) in cold climates through the microbial process of denitrification was evaluated using a pilot-scale fixed-bed bioreactor (27 m(3)). Surface water was diverted into the above-ground bioreactor filled with sawdust, crushed rock, and sewage sludge. At hydraulic residence times of ca.15 h and with the addition of acetate, NO3(-) and NO2(-) were removed to below detection levels at a NO3(-) removal rate of 5-10 g N m(-3) (bioreactor material) d(-1). The functional groups contributing to nitrogen removal in the bioreactor were studied by quantifying nirS and nirK present in denitrifying bacteria, nosZI and nosZII genes from the nitrous oxide - reducing community, and a taxa-specific part of the16S rRNA gene for the anammox community. The abundances of nirS and nirK were almost 2 orders of magnitude greater than the anammox specific 16S rRNA gene, indicating that denitrification was the main process involved in nitrogen removal. The spatial distribution of the quantified genes was heterogeneous in the bioreactor, with trends observed in gene abundance as a function of depth, distance from the bioreactor inlet, and along specific flowpaths. There was a significant relationship between the abundance of nirS, nirK, and nosZI genes and depth in the bioreactor, such that the abundance of organisms containing these genes may be controlled by oxygen diffusion and substrate supply in the partially or completely water-saturated material. Among the investigated microbial functional groups, nirS and anammox bacterial 16S rRNA genes exhibited a systematic trend of decreasing and increasing abundance, respectively, with distance from the inlet, which suggested that the functional groups respond differently to changing environmental conditions. The greater abundance of nirK along central flowpaths may indicate that the bioreactor

  12. Using metagenomic analyses to estimate the consequences of enrichment bias for pathogen detection

    Directory of Open Access Journals (Sweden)

    Pettengill James B

    2012-07-01

    Full Text Available Abstract Background Enriching environmental samples to increase the probability of detection has been standard practice throughout the history of microbiology. However, by its very nature, the process of enrichment creates a biased sample that may have unintended consequences for surveillance or resolving a pathogenic outbreak. With the advent of next-generation sequencing and metagenomic approaches, the possibility now exists to quantify enrichment bias at an unprecedented taxonomic breadth. Findings We investigated differences in taxonomic profiles of three enriched and unenriched tomato phyllosphere samples taken from three different tomato fields (n = 18. 16S rRNA gene meteganomes were created for each of the 18 samples using 454/Roche’s pyrosequencing platform, resulting in a total of 165,259 sequences. Significantly different taxonomic profiles and abundances at a number of taxonomic levels were observed between the two treatments. Although as many as 28 putative Salmonella sequences were detected in enriched samples, there was no significant difference in the abundance of Salmonella between enriched and unenriched treatments. Conclusions Our results illustrate that the process of enriching greatly alters the taxonomic profile of an environmental sample beyond that of the target organism. We also found evidence suggesting that enrichment may not increase the probability of detecting a target. In conclusion, our results further emphasize the need to develop metagenomics as a validated culture independent method for pathogen detection.

  13. Uranium enrichment and the environment

    International Nuclear Information System (INIS)

    The three gaseous diffusion plants comprise one of the largest industrial complexes in the free world. Since all of the enrichment is done inside a very large plumbing maze, the control of radioactivity does not present a serious problem. Conventional, nonexotic engineering and administrative measures adequately control the minor levels of radioactivity associated with support activities such as equipment decontamination and maintenance. The treatment and control of chemical waste streams to comply with Federal and state regulations has required the commitment of 47 million dollars since 1974. Through 1982, an additional 84 million dollars may be required. The high cost is not a reflection of initially poor conditions but is rather the result of providing large treatment systems to meet very low discharge limits. Examples that will be discussed include airborne particulate removal, recirculating cooling water treatment, and hazardous waste disposal concepts

  14. Tibet Policies Enrich Region's Development

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    During an interview with the German magazine Der Spiegel published on March 26,the 14th Dalai Lama attacked the Chinese government as"dividing Tibet by letting other provinces govern parts of Tibet".He also claimed that Tibet was"suffering cultural homicide".

  15. Anaerobic Oxidation of Methane Coupled to Nitrite Reduction by Halophilic Marine NC10 Bacteria.

    Science.gov (United States)

    He, Zhanfei; Geng, Sha; Cai, Chaoyang; Liu, Shuai; Liu, Yan; Pan, Yawei; Lou, Liping; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-08-15

    Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite. PMID:26048927

  16. Genetic Diversity through the Looking Glass: Effect of Enrichment Bias

    OpenAIRE

    Dunbar, J.; White, S.; Forney, L

    1997-01-01

    The effect of enrichment bias on the diversity of 2,4-dichlorophenoxyacetate (2,4-D)-degrading (2,4-D(sup+)) bacteria recovered from soil was evaluated by comparing the diversity of isolates obtained by direct plating to the diversity of isolates obtained from 85 liquid batch cultures. By the two methods, a total of 159 isolates were purified from 1 g of soil and divided into populations based on repeated extragenic palindromic sequence PCR (rep-PCR) genomic fingerprints. Approximately 42% of...

  17. Enrichment of carbon monoxide utilising microorganisms from methanogenic bioreactor sludge

    OpenAIRE

    Pereira, Ana Luísa; Stams, A.J.M.; Alves, M. M.; Sousa, D.Z.

    2015-01-01

    Conversion of CO is the rate limiting step during anaerobic conversion of syngas (a gaseous mixture mainly composed of CO, CO2 and H2). In this work we study the microbial diversity in anaerobic sludge submitted to extended contact to syngas in a multi-orifice baffled bioreactor (MOBB). Methane was the main product resulting from syngas conversion in the MOBB. Enrichment cultures started with this sludge produced methane as final product, but also acetate. 16S rRNA gene analysis revealed a pr...

  18. Cultivation of Denitrifying Polyphosphate-accumulating Organisms in Sequencing Batch Reactor%SBR反应器中反硝化除磷菌的快速富集

    Institute of Scientific and Technical Information of China (English)

    夏灵敏; 王弘宇; 田俊; 杨开; 张静

    2013-01-01

    Denitrifying polyphosphate-accumulating organisms (DPAOs),a principal part in the denitrifying phosphorus removal process,can remove nitrogen and phosphorus simultaneously under anoxic condition.The cultivation of DPAOs was achieved in a two-stage sequencing batch reactor (SBR) system,using the returned sludge from a secondary settling tank of Wuhan Shahu WWTP.The first-stage SBR operated in anaerobic/aerobic (A/O) mode to achieve the cultivation of PAOs.After 13 d,the removal rates of nitrogen and phosphorus were all above 85%.The second-stage SBR operated in anaerobic/aerobic/anoxic (A/O/A) mode to achieve the cultivation of DPAOs.After 26 d,the removal rates of ammonia nitrogen and phosphate were 92.2% and 91.2%,respectively.There was a linear relationship between phosphorus uptake and nitrate consumption,which suggested that the denitrifying phosphorus removal ability of the system was enhanced significantly.%反硝化除磷菌(DPAOs)能够在缺氧条件下同步完成脱氮除磷,是反硝化除磷工艺的主体.以武汉沙湖污水处理厂二沉池的回流污泥为种泥,采用二段式SBR工艺实现了反硝化除磷菌的快速富集.在第一阶段反应器采用厌氧/好氧(A/O)模式运行,可以实现对除磷菌(PAOs)的快速诱导和富集,运行13d后,SBR反应器对氮、磷的去除率均达到85%以上.而后进入第二阶段,采用厌氧/好氧/缺氧(A/O/A)模式运行,以快速富集培养反硝化除磷菌,经过26 d的运行,反应器对氨氮和磷酸盐的去除率分别达到92.2%和91.2%左右,且典型周期内硝酸盐的消耗量与磷的吸收量基本呈线性关系,表明系统的反硝化除磷能力得到显著增强.

  19. Environmental enrichment in farm, zoo, companion and experimental animals

    Directory of Open Access Journals (Sweden)

    Vučinić Marijana

    2009-01-01

    Full Text Available The paper deals with environmental enrichment for domestic animals at farms, animals in zoos, experimental animals and pet animals. Also, the paper defines and describes different strategies of environmental enrichment. Environmental enrichment is a simple and effective mean of prevention of boredom, behavioral disorders as well as an effective mean of improving animal welfare in farm, zoo, companion and experimental animals. Different items and materials may be used for environmental enrichment. They need to be evaluated for use by taking into account the following: the species of an animal, its needs, habits and capabilities, the type of an enrichment device, the device's ability to stimulate the animal's interest and the safety of the device. Enrichment programmes should always include two forms of enrichment: behavioral enrichment and environmental enrichment. Enrichment comes in many forms such as structural or physical enrichment, sensory enrichment (auditory and olfactory stimulation, dietary enrichment, manipulatable enrichment and social enrichment.

  20. Enriching Ontologies with Multilingual Information

    OpenAIRE

    Aguado de Cea, G.; A. GÓMEZ-PÉREZ; Montiel-Ponsoda, Elena

    2009-01-01

    Organizations working in a multilingual environment demand multilingual ontologies. To solve this problem we propose LabelTranslator, a system that automatically localizes ontologies. Ontology localization consists of adapting an ontology to a concrete language and cultural community. LabelTranslator takes as input an ontology whose labels are described in a source natural language and obtains the most probable translation into a target natural language of each ontology label. Our main con...

  1. Basic uranium-235 enrichment by the Asahi Chemical Enrichment Process (ACEP)

    International Nuclear Information System (INIS)

    The development of Asahi Chemical Enrichment Process (ACEP) led to the establishment of basic process technology permitting attainment of 3% enrichment within several months of operation by the mid-1980s, through advances which brought increased electron-exchange and adsorption-desorption reaction rates, effective uranium adsorption band formation and maintenance, and equilibrium plate height reductions based on the elucidation of mobile-phase dispersion. The theoretical and experimental development of redox agent self-regeneration led to a new 'Super Process' characterized by greater simplicity and efficiency than previously thought possible. A semi-commercial plant with enrichment columns of 1 m in diameter and 3 m in height, constructed at Hyuga City in Miyazaki Prefecture, demonstrated 3% uranium enrichment in April 1988. Through the improvement of enrichment efficiency, overall enrichment costs have been greatly lowered. The advantage of the chemical enrichment process, and its low cost of enrichment, have now been clearly demonstrated. (author)

  2. Enrichment-ELISA for Detection of Salmonella typhi From Food and Water Samples

    Institute of Scientific and Technical Information of China (English)

    S.KUMAR; K.BALAKRISHNA; HV.BATRA

    2008-01-01

    Objective Development of monoclonal antibody based sandwich enzyme linked immunosorbant assay(sELISA)for rapid detection of Salmonella enterica serovar typhi(S.typhi) from food and water samples and optimization of enrichment procedures for use with the developed sELISA to increase the detection Sensitivity of the assay. Methods Spleen cells from BALB/c mice immunized with flagellin(H=d)antigen of S.typhi were fused with Sp2/0 myeloma cells.The hybridoma cell line specific to H=d antigen was established.characterized and ascites raised against one of these clones.The hypefimmune serum to flagellin antigen was raised in New Zealand White rabbits.An sELISA was developed using polyclonalantibody as capture and monoelonal antibody as detection antibody.To design the efficient culture sUrategies for use with the sELISA.different pre-enrichment and enrichment brothswere evaluated.The mediaincluded buffered peptonewater(BPW)and brain heart infusion broth for pre-enrichment and selenite F broth and Rappaport-Vassiliadis broth as enrichment broths.The developed sELISA with preceding enrichment step in BPW(Enrichment-ELISA)was evaluated in various food samples artificially inoculated with S. typhi bacteria.Various food(30)and water(35)samples collected from field were also tested by Enrichment-ELISA and culture method. Results Out of four specific clones to H=d antigen,one clone(#2/56.IgG2a isotype)was usedin sELISA.The sELISA had the detectionlimit of 104-105 cfu of S.typhi.Of the various broths used with sELISA,BPW was found to yield maximum ELISA values.Enrichment-ELISA,when tested in artificially inoculated food samples,generally,could detect 102S.typhi cfu/mL within 10 h from variousfood rinses(meat,vegetable)and milk samples.After overnight enrichment in BPW,as less as 2 bacteria per 10 mL of milk,meat rinse.and chicken rinse could be detected.Only one of the field samples(water)gave false positive result by Enrichment-ELISA.Conclusion In comparison to culture

  3. Enriching the hot circumgalactic medium

    CERN Document Server

    Crain, Robert A; Schaye, Joop; Frenk, Carlos S; Theuns, Tom

    2013-01-01

    Models of galaxy formation in a CDM universe predict that massive galaxies are surrounded by a hot, quasi-hydrostatic circumgalactic corona of slowly cooling gas, predominantly accreted from the IGM. This prediction is borne out by the cosmological hydrodynamical simulations of Crain et al., which reproduce scaling relations between the X-ray and optical properties of nearby disc galaxies. Such coronae are metal poor, but observations of the X-ray emitting circumgalactic medium (CGM) of local galaxies typically indicate enrichment to near-solar iron abundance, potentially signalling a shortcoming in galaxy formation models. We show here that, while the hot CGM of galaxies formed in the simulations is metal poor in a mass-weighted sense, its X-ray luminosity-weighted metallicity is often close to solar. This bias arises because the soft X-ray emissivity of a typical 0.1 keV corona is dominated by collisionally-excited metal ions that are synthesised in stars and recycled into the hot CGM. We find that these me...

  4. Student science enrichment training program

    Energy Technology Data Exchange (ETDEWEB)

    Sandhu, S.S.

    1994-08-01

    This is a report on the Student Science Enrichment Training Program, with special emphasis on chemical and computer science fields. The residential summer session was held at the campus of Claflin College, Orangeburg, SC, for six weeks during 1993 summer, to run concomitantly with the college`s summer school. Fifty participants selected for this program, included high school sophomores, juniors and seniors. The students came from rural South Carolina and adjoining states which, presently, have limited science and computer science facilities. The program focused on high ability minority students, with high potential for science engineering and mathematical careers. The major objective was to increase the pool of well qualified college entering minority students who would elect to go into science, engineering and mathematical careers. The Division of Natural Sciences and Mathematics and engineering at Claflin College received major benefits from this program as it helped them to expand the Departments of Chemistry, Engineering, Mathematics and Computer Science as a result of additional enrollment. It also established an expanded pool of well qualified minority science and mathematics graduates, which were recruited by the federal agencies and private corporations, visiting Claflin College Campus. Department of Energy`s relationship with Claflin College increased the public awareness of energy related job opportunities in the public and private sectors.

  5. Vegetation, soil and hydrology management influence denitrification activity and the composition of nirK-type denitrifier communities in a newly afforested riparian buffer.

    Science.gov (United States)

    Boz, Bruno; Mizanur Rahman, Md; Bottegal, Mariangela; Basaglia, Marina; Squartini, Andrea; Gumiero, Bruna; Casella, Sergio

    2013-09-25

    Soil microbial community composition and activity could be affected by suitable manipulation of the environment they live in. If correctly applied such an approach could become a very effective way to remediate excess of chemicals. The concentration of nitrogen, especially nitrate deriving from agricultural managements, is generally found to increase in water flow. Therefore, by forcing the water flow through a buffer strip specifically designed and possibly afforested with suitable plant species, may result effective in reducing high nitrogen contents. The management of a riparian buffer may definitely affect the soil microbial activities, including denitrification, as well as the composition of the community. The present study reports on the changes occurred in terms of denitrifying microbial community composition, as compared to that of a neighbouring agricultural area, as a consequence of hydraulic management coupled to the suspension of farming practices and to the development of the woody and herbaceous vegetation. With this aim, denitrification was repeatedly measured and the data obtained were related to those deriving from a specific analysis of bacterial groups involved in denitrification. nirK, encoding for nitrite reductase, an enzyme essential for the conversion of nitrite to nitric oxide and considered the key step in the denitrification process, was chosen as the target gene. The main results obtained indicated that denitrification activity changes in riparian buffer as compared to agricultural soil and it is strongly influenced by carbon availability and soil depth. Although no significant differences on the community composition between superficial (0-15 cm) and medium (40-55 cm) layers were observed, the nirK-type denitrifier community was shown to significantly differ between riparian and agricultural soils in both surface and medium layers.

  6. Diversity and distribution of amoA-type nitrifying and nirS-type denitrifying microbial communities in the Yangtze River estuary

    Science.gov (United States)

    Zhang, Y.; Xie, X.; Jiao, N.; Hsiao, S. S.-Y.; Kao, S.-J.

    2014-04-01

    Coupled nitrification-denitrification plays a critical role in the removal of excess nitrogen, which is chiefly caused by humans, to mitigate estuary and coastal eutrophication. Despite its obvious importance, limited information about the relationships between nitrifying and denitrifying microbial communities in estuaries, and their controlling factors have been documented. We investigated the nitrifying and denitrifying microbial communities in the estuary of turbid subtropical Yangtze River (YRE), the largest river in Asia, by analyzing the ammonia monooxygenase gene amoA, including archaeal and bacterial amoA, and the dissimilatory nitrite reductase gene nirS using clone libraries and quantitative PCR (qPCR). The diversity indices and rarefaction analysis revealed a quite low diversity for both β-proteobacterial and archaeal amoA genes, but qPCR data showed significantly higher amoA gene copy numbers for archaea than β-proteobacteria. Compared with the amoA gene, a significantly higher level of diversity but lower gene copy numbers were found for the nirS gene. Nitrification and denitrification rates based on 15N incubation experiments supported gene abundance data as denitrification rates were below detection limit, suggesting lower denitrification than nitrification potential. In general, the abundances of the amoA and nirS genes were significantly higher in the bottom samples than the surface ones, and in the high-turbidity river mouth, were significantly higher in the particle-associated (> 3 μm) than the free-living (0.2 ~ 3 μm) communities. Notably, positive correlations between the amoA and nirS gene abundances suggested potential gene-based coupling between nitrification and denitrification, especially for the particle-associated assemblages. Statistical analysis of correlations between the community structure, gene abundances and environmental variables further revealed that dissolved oxygen and total suspended material might be the key factors

  7. Enrichment technology. Dependable vendor of gas centrifuges

    International Nuclear Information System (INIS)

    Enrichment Technology is an innovative, high-tech company that develops, manufactures and installs gas centrifuges for enriching uranium. In addition, Enrichment Technology designs enrichment plants that use gas centrifuge technology. This technology offers the most efficient and cost-effective method for enriching uranium yet: high-performance, safe technology that dominates the market with a global share of 45 percent. A determining factor in Enrichment Technology's success is its mission: supplying its customers with safe, reliable technology. Production of the centrifuges requires versatile know-how and collaboration between different departments as well as interdisciplinary teams at the various sites. More than 2000 operators at 8 sites in 5 countries contribute their individual knowledge and personal skills in order to produce this exceptional technology. The head office is in Beaconsfield near London and the operational headquarters are in Almelo in the Netherlands. There are other sites in Germany (Juelich und Gronau), Great Britain (Capenhurst) as well as project sites in the USA and France. Capenhurst is where experienced engineers design new enrichment plants and organise their construction. Centrifuge components are manufactured in Almelo and Juelich, while the pipework needed to connect up the centrifuges is produced at the site in Gronau. In Juelich, highly qualified scientists in interdisciplinary teams are continuously researching ways of improving the current centrifuges. Communication between specialists in the fields of chemistry, physics and engineering forms the basis for the company's success and the key to extending this leading position in the global enrichment market. (orig.)

  8. 21 CFR 137.350 - Enriched rice.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Enriched rice. 137.350 Section 137.350 Food and... Related Products § 137.350 Enriched rice. (a) The foods for which definitions and standards of identity are prescribed by this section are forms of milled rice (except rice coated with talc and glucose...

  9. Perspectives for the uranium enrichment in Brazil

    International Nuclear Information System (INIS)

    Through an analysis of the electrical energy future in Brazil, the needs for enriched uranium are discussed, and therefore the importance of developing local capability for self-production. A description of the production processes that are well established is given first, then the analysis itself is performed and finally a visualization of the International Market for enriched uranium is shown. (author)

  10. A Component Analysis of Marriage Enrichment.

    Science.gov (United States)

    Buston, Beverley G.; And Others

    Although marriage enrichment programs have been shown to be effective for many couples, a multidimensional approach to assessment is needed in investigating these groups. The components of information and social support in successful marriage enrichment programs were compared in a completely crossed 2 x 2 factorial design with repeated measures.…

  11. 北运河沉积物中主要脱氮功能微生物的群落特征%Diversity, abundance and distribution ofnirS-type denitrifiers and Anammox bacteria in sediments of Beiyun River

    Institute of Scientific and Technical Information of China (English)

    鲍林林; 王晓燕; 陈永娟; 张苓荣

    2016-01-01

    Denitrification and anaerobic ammonia oxidation are two main processes for nitrogen removal in nitrogen cycle. The seasonal variation of community diversity and abundance, phylogenetic composition ofnirS-type denitrifiers and Anammox (anaerobic ammonia oxidation) bacteria of sediments in Beiyun River were compared based on PCR (polymerase chain reaction), T-RFLP (terminal restriction fragment length polymorphism), clone and sequencing. The abundance of nirS-type denitrifiers increased from summer to winter while the abundance of Anammox bacteria decreased significantly. What's more, the abundance ofnirS-type denitrifiers was significantly higher than Anammox in fall and winter. Community composition of the two microbial groups varied seasonally and the community diversity ofnirS-type denitrifiers was much higher than Anammox bacteria. Concentrations of nitrogens and organic carbon in the sediments increased significantly from summer to winter. Environmental temperature was significantly correlated with the seasonal changes of abundance and community distribution of the two microbial groups in sediments. Correlation analysis revealed that total nitrogen had a great effect on the abundance ofnirS-type denitrifiers, while C/N was significantly correlated with abundance of Anammox bacteria. NOx? and pH were also the main environmental factors determining the community distribution ofnirS-type denitrifiers and Anammox bacteria in sediments. Phylogenetic analysis revealed that most of the denitrifying microbes belonged to species with relatively high pollution-resistance and efficiency of nitrogen removal. Phylogenetic diversity of nirS-type denitrifiers was much higher than that of Anammox bacteria.nirS-type denitrifiers were grouped into genera Pseudomonas andHalomonas, while Anammox was mainly bacteria belonged toCandidatus Brocadia.%应用分子生物学技术研究北运河沉积物中主要脱氮功能微生物,反硝化细菌和厌氧氨氧化细菌(Anammox)的

  12. The Cognitive Enrichment Network Program: Goodness of Fit with At-Risk Gifted Students.

    Science.gov (United States)

    Greenberg, Katherine H.; And Others

    1993-01-01

    The Cognitive Enrichment Network Educational Model (COGNET) is a comprehensive elementary school approach to assist children in becoming effective, independent, life-long learners, by using mediated learning to address each child's personal and cultural characteristics and social milieu. This paper describes the COGNET approach for nurturing…

  13. Selective enrichment of Geobacter sulfurreducens from anaerobic granular sludge with quinones as terminal electron acceptors

    NARCIS (Netherlands)

    Cervantes-Carillo, F.J.; Duong Dac, T.; Ivanova, A.E.; Roest, de K.; Akkermans, A.D.L.; Lettinga, G.; Field, J.A.

    2003-01-01

    A quinone-respiring, enrichment culture derived from methanogenic granular sludge was phylogenetically characterized by using a combined cloning-denaturing gradient gel electrophoresis (DGGE) method, which revealed that the consortium developed was dominated by a single microorganism: 97% related, i

  14. The low-enrichment fuel development program

    International Nuclear Information System (INIS)

    In the 1950s and 1960s, low-power research reactors were built around the world utilized MTR-type fuel elements containing 20% enriched uranium. However, the demand for higher specific power created a need for greater uranium-235 concentrations. Early difficulties in increasing uranium content led to the substitution of highly enriched uranium in place of the 20% enriched fuel previously utilized. The highly enriched material also yielded other benefits including longer core residence time, higher specific reactivity, and somewhat lower cost. Highly enriched material then became readily available and was used for high-power reactors as well as in low-power reactors where 20% enriched material would have sufficed. The trend toward higher and higher specific power also led to the development of the dispersion-type fuels which utilized highly enriched uranium at a concentration of about 40 wt%. In the 1970's, however, concerns were raised about the proliferation resistance of fuels and fuel cycles. As a consequence, the U.S. Department of State has recently prohibited the foreign shipment of highly enriched material, except where prior contractual obligation or special merit exists. This will impact on the availability and utilization of highly enriched uranium for research and test reactor fuel. It has also stimulated development programs on fuels with higher uranium content which would allow the use of uranium of lower enrichment. The purpose of this report is to briefly describe the overall fuel development program which is coordinated by Argonne National Laboratory for the Department of Energy, and to indicate the current and potential uranium loadings. Other reports will address the individual fuel-development activities in greater detail

  15. The low-enrichment fuel development program

    International Nuclear Information System (INIS)

    In the 1950s and 1960s, low-power research reactors were built around the world utilized MTR-type fuel elements containing 20% enriched uranium. However, the demand for higher specific power created a need for greater uranium-235 concentrations. Early difficulties in increasing uranium content led to the substitution of highly enriched uranium in place of the 20% enriched fuel previously utilized. The highly enriched material also yielded other benefits including longer core residence time, higher specific reactivity, and somewhat lower cost. Highly enriched material then became readily available and was used for high-power reactors as well as in low-power reactors where 20% enriched material would have sufficed. The trend toward higher and higher specific power also led to the development of the dispersion-type fuels which utilized highly enriched uranium at a concentration of about 40 wt%. In the 1970's, however, concerns were raised about the proliferation resistance of fuels and fuel cycles. As a consequence, the U.S. Department of State has recently prohibited the foreign shipment of highly enriched material, except where prior contractual obligation or special merit exists. This will impact on the availability and utilization of highly enriched uranium for research and test reactor fuel. It has also stimulated development programs on fuels with higher uranium content which would allow the use of uranium of lower enrichment. The purpose of this report is to briefly describe the overall fuel-development program which is coordinated by Argonne National Laboratory for the Department of Energy, and to indicate the current and potential uranium loadings. Other reports will address the individual fuel-development activities in greater detail

  16. Fecal culture

    Science.gov (United States)

    Stool culture; Culture - stool ... stool tests are done in addition to the culture, such as: Gram stain of stool Fecal smear ... Giannella RA. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Feldman M, Friedman LS, Brandt LJ, ...

  17. Urine culture

    Science.gov (United States)

    Culture and sensitivity - urine ... when urinating. You also may have a urine culture after you have been treated for an infection. ... when bacteria or yeast are found in the culture. This likely means that you have a urinary ...

  18. Dialogismo, lenguas extranjeras e identidad cultural (Dialogism, Foreign Languages, and Cultural Identity).

    Science.gov (United States)

    Zoreda, Margaret Lee

    Foreign Language education will play an important role in the broadening and globalization of higher education for the 21st century. Where else will educators find the tools to "dialog" with--to engage--the "other" as part of the enriching process that accompanies cultural exchange, cultural broadening? This paper sheds light on these issues, and…

  19. Safeguards Culture

    Energy Technology Data Exchange (ETDEWEB)

    Frazar, Sarah L.; Mladineo, Stephen V.

    2012-07-01

    The concepts of nuclear safety and security culture are well established; however, a common understanding of safeguards culture is not internationally recognized. Supported by the National Nuclear Security Administration, the authors prepared this report, an analysis of the concept of safeguards culture, and gauged its value to the safeguards community. The authors explored distinctions between safeguards culture, safeguards compliance, and safeguards performance, and evaluated synergies and differences between safeguards culture and safety/security culture. The report concludes with suggested next steps.

  20. Deuterium enrichment of interstellar dusts

    Science.gov (United States)

    Das, Ankan; Chakrabarti, Sandip Kumar; Majumdar, Liton; Sahu, Dipen

    2016-07-01

    High abundance of some abundant and simple interstellar species could be explained by considering the chemistry that occurs on interstellar dusts. Because of its simplicity, the rate equation method is widely used to study the surface chemistry. However, because the recombination efficiency for the formation of any surface species is highly dependent on various physical and chemical parameters, the Monte Carlo method is best suited for addressing the randomness of the processes. We carry out Monte-Carlo simulation to study deuterium enrichment of interstellar grain mantle under various physical conditions. Based on the physical properties, various types of clouds are considered. We find that in diffuse cloud regions, very strong radiation fields persists and hardly a few layers of surface species are formed. In translucent cloud regions with a moderate radiation field, significant number of layers would be produced and surface coverage is mainly dominated by photo-dissociation products such as, C, CH_3, CH_2D, OH and OD. In the intermediate dense cloud regions (having number density of total hydrogen nuclei in all forms ˜2 × 10^4 cm^{-3}), water and methanol along with their deuterated derivatives are efficiently formed. For much higher density regions (˜10^6 cm^{-3}), water and methanol productions are suppressed but surface coverage of CO, CO_2, O_2, O_3 are dramatically increased. We find a very high degree of fractionation of water and methanol. Observational results support a high fractionation of methanol but surprisingly water fractionation is found to be low. This is in contradiction with our model results indicating alternative routes for de-fractionation of water.

  1. Italian activities in uranium enrichment

    International Nuclear Information System (INIS)

    The paper describes Italian activities in uranium enrichment, which have mainly developed along the lines of the two classical processes: gaseous diffusion and centrifuges. Research, development and industrial activities play different roles in the two methods, and a special working group, GIAU, was established by CNEN to help co-ordinate this activity. In the field of gaseous diffusion, R and D effort was, from the start of the programme in 1968, mainly devoted to barriers and compressors, with the object of fully understanding the process and of demonstrating that it was capable of overcoming the main problems in this technology. Isotope separation of UF6 was demonstrated in 1974 at experimental plant level. Cost-sharing contracts were signed between CNEN and industries to build prototypes and ''first-of-a-kind'' components; small production lines have been set up to evaluate economics and assess production quality. Eurodif is partially associated with the development of this activity. On the industrial level, AGIP Nucleare and CNEN were among the promoters of the Eurodif venture from the beginning in 1973 and now own 25% of the shares. In the field of ultracentrifugation, work is still devoted mainly to R and D on the machines. The separation process was demonstrated in 1973 at laboratory level with a Zippe type centrifuge. Later activities aimed at developing high-capacity machines; different solutions are under close scrutiny. Carbon fibres and multiplerotor machines have been mechanically tested, and the first reference design of a small cascade plant has been completed. In the field of laser separation, after a complete and critical survey of different processes under development in other countries, experimental research work is now being undertaken, and experiments on basic aspects of the process are in progress. (author)

  2. Denitrifier Community of Leachate Treated by Semi-Aerobic Aged-Refuse Bioreactor%准好氧矿化垃圾床处理渗滤液的脱氮菌群研究

    Institute of Scientific and Technical Information of China (English)

    张爱平; 刘丹; 韩智勇; 刘咏

    2011-01-01

    A biological mechanism for nitrogen removal from leachate was investigated using a semi-aerobic aged-refuse bioreactor.The quantity and microbial community structure of denitrifier at various heights of the bioreactor were studied using the most probable number method, a series of biochemical tests and microscopic photos. The results showed that the average quantity of nitrosobacteria,nitrobacteria,anaerobic and aerobic denitrifying bacteria were 5.3×106 ,7.5×106 ,6.9×103 and 2. 5×l05 per gram, respectively. Nitrosobacteria, nitrobacteria and aerobic denitrifying bacteria were mostly found at the surface and bottom of the bioreactor,while anaerobic denitrifying bacteria were mostly at the middle. Finally, three strains of nitrosobacteria, six strains of nitrobacteria, five strains of anaerobic denitrifying bacteria and six strains of aerobic denitrifying bacteria were isolated from the bioreactor. Thus, the biological mechanism could be explained by simultaneous nitrification and denitrification, and its action zones were mainly presented at the surface and bottom of the bioreactor.%为探明准好氧矿化垃圾床处理渗滤液的生物脱氮机理,采用最大或然数计数法以及一系列的生化试验和镜检照片,研究了床层不同高度脱氮菌的数量和菌群结构.结果表明:床内亚硝化菌、硝化菌、厌氧反硝化菌和好氧反硝化菌的平均数量分别为5.3×106,7.5×106,6.9×103和2.5×105 g-1,亚硝化菌、硝化菌和好氧反硝化菌主要富集于反应床的表层和底部,厌氧反硝化菌主要富集于反应床的中部;从床内共分离出3株亚硝化菌,6株硝化菌,5株厌氧反硝化菌和6株好氧反硝化菌.准好氧矿化垃圾床处理渗滤液的生物脱氮机理为同步硝化反硝化,主要发生在反应床的表层和底部.

  3. Organizational Culture

    Directory of Open Access Journals (Sweden)

    Adrian HUDREA

    2006-02-01

    Full Text Available Cultural orientations of an organization can be its greatest strength, providing the basis for problem solving, cooperation, and communication. Culture, however, can also inhibit needed changes. Cultural changes typically happen slowly – but without cultural change, many other organizational changes are doomed to fail. The dominant culture of an organization is a major contributor to its success. But, of course, no organizational culture is purely one type or another. And the existence of secondary cultures can provide the basis for change. Therefore, organizations need to understand the cultural environments and values.

  4. World enrichment services market 1990-2005

    International Nuclear Information System (INIS)

    Growth in world enrichment capacity, already in oversupply, will lead to a very competitive enrichment services market by the second half of the 1990s. Three of the four primary enrichment suppliers (USDOE, Eurodif, and Urenco) already have the capacity to produce 33 million SWU per year. Explorts from the Soviet Union and the People's Republic of China (PRC) currently make available an additional six million SWU per year, and that figure could rise substantially. With additional supply capability expected from China, the Soviet Union, Louisiana Energy Services (LES) and Isotope Technologies (ITI), and the increased capacity of Urenco, and possibly even AVLIS from DOE, enrichment supply capability could exceed 46 million SWU per year by the year 2000. Yet annual enrichment requirements are only estimated to grow from 23.5 million SWU in 1990, to 28.9 million SWU by 2000. Total unfilled enrichment requirements will rise significantly in the second half of the 1990s, particularly from US utilities, creating sales opportunities for which suppliers will compete aggressively. These factors foretell a very competitive market in which sellers will offer low prices and flexible contracts. The anticipation of such strong competition also raises the question of which enrichment technology will succeed, and puts tremendous pressure on all suppliers to find cost-effective means of production as quickly as possible

  5. The US Enrichment Corp.. Looking towards privatisation

    International Nuclear Information System (INIS)

    The United States Enrichment Corporation (USEC) was launched in 1993 with the intention of bringing private sector disciplines into the US enrichment industry. It is charged with operating as a business enterprise on a profitable and efficient basis, with maximizing the long term value of the Corporation to the Treasury and taxpayer, and with maintaining a reliable and economic source of enriched uranium. Though acting like a commercial business, it remains for the moment in US government ownership. The directors have an obligation, however, to recommend to the government in 1995 if, how and when the Corporation should be privatized. (UK)

  6. Metal enrichment of the CGM through outflows

    Science.gov (United States)

    Christensen, Charlotte

    2016-01-01

    Galactic outflows enrich the circumgalactic medium through the redistribution of metals from the disks of galaxies. We examine the history of this enrichment by analyzing the outflows of twenty high-resolution simulated galaxies spanning two and a half orders of magnitude in halo mass. These simulations match many observed trends, including the mass-metallicity relation. By tracking particles in the simulations, we follow the removal and reaccretion of metals between redshift 3.5 and 0. We also determine the enrichment of the outflowing gas compared to the local interstellar media. Finally we compare the redshift zero metal census to observed values.

  7. Profile of World Uranium Enrichment Programs - 2007

    Energy Technology Data Exchange (ETDEWEB)

    Laughter, Mark D [ORNL

    2007-11-01

    It is generally agreed that the most difficult step in building a nuclear weapon is acquiring weapons grade fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, while HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium (LEU) for use in fuel for nuclear reactors. However, the same equipment used to produce LEU for nuclear fuel can also be used to produce HEU for weapons. Safeguards at an enrichment plant are the array of assurances and verification techniques that ensure uranium is only enriched to LEU, no undeclared LEU is produced, and no uranium is enriched to HEU or secretly diverted. There are several techniques for enriching uranium. The two most prevalent are gaseous diffusion, which uses older technology and requires a lot of energy, and gas centrifuge separation, which uses more advanced technology and is more energy efficient. Gaseous diffusion plants (GDPs) provide about 40% of current world enrichment capacity, but are being phased out as newer gas centrifuge enrichment plants (GCEPs) are constructed. Estimates of current and future enrichment capacity are always approximate, due to the constant upgrades, expansions, and shutdowns occurring at enrichment plants, largely determined by economic interests. Currently, the world enrichment capacity is approximately 53 million kg-separative work units (SWU) per year, with 22 million in gaseous diffusion and 31 million in gas centrifuge plants. Another 23 million SWU/year of capacity are under construction or planned for the near future, almost entirely using gas centrifuge separation. Other less-efficient techniques have also been used in the past, including electromagnetic and aerodynamic separations, but these are considered obsolete, at least from a commercial perspective. Laser isotope separation shows promise as a possible enrichment technique

  8. Industrial cultures

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    1996-01-01

    The chapter deals with different paradigms andtheories of cultural development. The problem toexplain change and methods to analyse developmentin different cultures are presented and discussed.......The chapter deals with different paradigms andtheories of cultural development. The problem toexplain change and methods to analyse developmentin different cultures are presented and discussed....

  9. Cultural Heritage Content Re-Use: An Aggregators's Point of View

    Science.gov (United States)

    Gavrilis, D.; Ioannides, M.; Theofanous, E.

    2015-08-01

    This paper introduces a use case of re-using aggregated and enriched metadata for the tourism creative industry. The MORe aggregation and enrichment framework is presented along with an example for enriching cultural heritage objects harvested from a number of Omeka repositories. The enriched content is then published both to the EU Digital Library Europeana (http://www.europeana.eu) and to an Elastic Search component that feeds a portal aimed at providing tourists with interesting information.

  10. A Guide to Job Enrichment and Redesign.

    Science.gov (United States)

    Cunningham, J. Barton; Eberle, Ted

    1990-01-01

    Describes job design alternatives--job enrichment, the job characteristics model, Japanese style management, and quality-of-worklife approaches. Focuses on the problems that human resources professionals may encounter when attempting to implement these approaches. (Author/JOW)

  11. Management's Ecstasy and Disparity Over Job Enrichment

    Science.gov (United States)

    King, Albert S.

    1976-01-01

    A case study analyzing job enrichment schemes and manager expectations of increased productivity is presented. It was found that it was the managers' expectations of increased productivity, not the reorganization of work, that led to higher productivity. (EC)

  12. Job Enrichment: How to Avoid the Pitfalls

    Science.gov (United States)

    Tregoe, Benjamin B., Jr.

    1974-01-01

    While many job enrichment programs fail, a program called Analytical Trouble Shooting has been successful in training people to increase their problem-solving capabilities and to communicate readily with persons in other areas and on different levels. (AG)

  13. Status of laser enrichment technology updated

    Science.gov (United States)

    Sakabe, Y.

    1986-08-01

    The principles of uranium enrichment by a laser method, the technology's current status and future prospects, centered on research and development activity at the Japan Atomic Energy Research Institute and the Institute of Physical and Chemical Research are described.

  14. Community Structure of Denitrifiers, Bacteria, and Archaea along Redox Gradients in Pacific Northwest Marine Sediments by Terminal Restriction Fragment Length Polymorphism Analysis of Amplified Nitrite Reductase (nirS) and 16S rRNA Genes

    OpenAIRE

    Braker, Gesche; Ayala-del-Río, Héctor L.; Devol, Allan H.; Fesefeldt, Andreas; Tiedje, James M.

    2001-01-01

    Steep vertical gradients of oxidants (O2 and NO3−) in Puget Sound and Washington continental margin sediments indicate that aerobic respiration and denitrification occur within the top few millimeters to centimeters. To systematically explore the underlying communities of denitrifiers, Bacteria, and Archaea along redox gradients at distant geographic locations, nitrite reductase (nirS) genes and bacterial and archaeal 16S rRNA genes (rDNAs) were PCR amplified and analyzed by terminal restrict...

  15. Challenges when developing omega-3 enriched foods

    OpenAIRE

    Jacobsen, Charlotte

    2010-01-01

    Due to the polyunsaturated nature of omega-3 fatty acids, lipid oxidation is a major challenge when developing omega-3 enriched foods. In multiphase food systems, several factors can affect lipid oxidation and efficacy of antioxidants, added to prevent lipid oxidation. This review discusses the influence of important factors such as oil quality, delivery systems for omega-3 fatty acids, processing conditions, composition of the food matrix on lipid oxidation in different omega-3 enriched food...

  16. NRC licensing of uranium enrichment plants

    International Nuclear Information System (INIS)

    The US Nuclear Regulatory Commission (NRC) is preparing a rule making that establishes the licensing requirements for low-enriched uranium enrichment plants. Although implementation of this rule making is timed to correspond with receipt of a license application for the Louisiana Energy Services centrifuge enrichment plant, the rule making is applicable to all uranium enrichment technologies. If ownership of the US gaseous diffusion plants and/or atomic vapor laser isotope separation is transferred to a private or government corporation, these plants also would be licensable under the new rule making. The Safeguards Studies Department was tasked by the NRC to provide technical assistance in support of the rule making and guidance preparation process. The initial and primary effort of this task involved the characterization of the potential safeguards concerns associated with a commercial enrichment plant, and the licensing issues associated with these concerns. The primary safeguards considerations were identified as detection of the loss of special nuclear material, detection of unauthorized production of material of low strategic significance, and detection of production of uranium enriched to >10% 235U. The primary safeguards concerns identified were (1) large absolute limit of error associated with the material balance closing, (2) the inability to shutdown some technologies to perform a cleanout inventory of the process system, and (3) the flexibility of some technologies to produce higher enrichments. Unauthorized production scenarios were identified for some technologies that could prevent conventional material control and accounting programs from detecting the production and removal of 5 kg 235U as highly enriched uranium. Safeguards techniques were identified to mitigate these concerns

  17. Modeling of Transients in an Enrichment Circuit

    International Nuclear Information System (INIS)

    In the present work a mathematical model is presented in order to describe the dynamic behavior inside a closed enrichment loop, the latter representing a single stage of an uranium gaseous diffusion enrichment cascade.The analytical model is turned into a numerical model, and implemented through a computational code.Transients of two species separation were numerically analyzed, including setting times of each magnitude, behavior of each one of them during different transients, and redistribution of concentrations along the closed loop

  18. U.S. forms uranium enrichment corporation

    International Nuclear Information System (INIS)

    After almost 40 years of operation, the federal government is withdrawing from the uranium enrichment business. On July 1, the Department of Energy turned over to a new government-owned entity--the US Enrichment Corp. (USEC)--both the DOE enrichment plants at Paducah, Ky., and Portsmouth, Ohio, and domestic and international marketing of enriched uranium from them. Pushed by the inability of DOE's enrichment operations to meet foreign competition, Congress established USEC under the National Energy Policy Act of 1992, envisioning the new corporation as the first step to full privatization. With gross revenues of $1.5 billion in fiscal 1992, USEC would rank 275th on the Fortune 500 list of top US companies. USEC will lease from DOE the Paducah and Portsmouth facilities, built in the early 1950s, which use the gaseous diffusion process for uranium enrichment. USEC's stock is held by the US Treasury, to which it will pay annual dividends. Martin Marietta Energy Systems, which has operated Paducah since 1984 and Portsmouth since 1986 for DOE, will continue to operate both plants for USEC. Closing one of the two facilities will be studied, especially in light of a 40% world surplus of capacity over demand. USEC also will consider other nuclear-fuel-related ventures. USEC will produce only low-enriched uranium, not weapons-grade material. Indeed, USEC will implement a contract now being completed under which the US will purchase weapons-grade uranium from dismantled Russian nuclear weapons and convert it into low-enriched uranium for power reactor fuel

  19. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

    2011-11-15

    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  20. Enrichment of Mouse Spermatogonial Stem Cells by the Stem Cell Dye CDy1.

    Science.gov (United States)

    Kanatsu-Shinohara, Mito; Morimoto, Hiroko; Shinohara, Takashi

    2016-01-01

    Spermatogonial stem cells (SSCs) comprise a small population of germ cells with self-renewal potential. Previous studies have shown that SSCs share several common features with stem cells in other self-renewing tissues, including surface markers and proliferative machinery. However, studies of SSCs are severely handicapped by the small number of SSCs and the lack of SSC-specific markers. In the present study, we examined the utility of CDy1 and Rh123, both of which are used for the collection of stem cells in several self-renewing tissues. CDy1 stained germline stem (GS) cells, cultured spermatogonia enriched for SSC activity, after in vitro incubation without exerting toxic effects. Unlike previously reported stem cell-specific dyes, CDy1 was also useful for enrichment of SSCs in both GS cell culture and mature adult testes. Spermatogonial transplantation showed that ∼1 in 66.7 cells exhibited SSC activity after CDH1-based magnetic cell selection and CDy1 staining. In contrast, although Rh123 was previously used successfully to collect SSCs from cryptorchid testes, it was not possible to recover SSCs from both GS cell cultures and wild-type testes. Thus, CDy1 staining will provide a useful strategy for the enrichment of SSCs and may be used in conjunction with other reagents for the enrichment of SSCs.

  1. Enrichment and isolation of Flavobacterium strains with tolerance to high concentrations of cesium ion.

    Science.gov (United States)

    Kato, Souichiro; Goya, Eri; Tanaka, Michiko; Kitagawa, Wataru; Kikuchi, Yoshitomo; Asano, Kozo; Kamagata, Yoichi

    2016-01-01

    Interest in the interaction of microorganisms with cesium ions (Cs(+)) has arisen, especially in terms of their potent ability for radiocesium bioaccumulation and their important roles in biogeochemical cycling. Although high concentrations of Cs(+) display toxic effects on microorganisms, there have been only limited reports for Cs(+)-tolerant microorganisms. Here we report enrichment and isolation of Cs(+)-tolerant microorganisms from soil microbiota. Microbial community analysis revealed that bacteria within the phylum Bacteroidetes, especially Flavobacterium spp., dominated in enrichment cultures in the medium supplemented with 50 or 200 mM Cs(+), while Gammaproteobacteria was dominant in the control enrichment cultures (in the presence of 50 and 200 mM K(+) instead of Cs(+)). The dominant Flavobacterium sp. was successfully isolated from the enrichment culture and was closely related to Flavobacterium chungbukense with 99.5% identity. Growth experiments clearly demonstrated that the isolate has significantly higher tolerance to Cs(+) compared to its close relatives, suggesting the Cs(+)-tolerance is a specific trait of this strain, but not a universal trait in the genus Flavobacterium. Measurement of intracellular K(+) and Cs(+) concentrations of the Cs(+)-tolerant isolate and its close relatives suggested that the ability to maintain low intracellular Cs(+) concentration confers the tolerance against high concentrations of external Cs(+). PMID:26883718

  2. Oak Ridge National Laboratory's isotope enrichment program

    International Nuclear Information System (INIS)

    The Isotope Enrichment Program (IEP) at Oak Ridge National Laboratory (ORNL) is responsible for the production and distribution of ∼225 enriched stable isotopes from 50 multi-isotopic elements. In addition, ORNL distributes enriched actinide isotopes and provides extensive physical- and chemical-form processing of enriched isotopes to meet customer requirements. For more than 50 yr, ORNL has been a major provider of enriched isotopes and isotope-related services to research, medical, and industrial institutions throughout the world. Consolidation of the Isotope Distribution Office (IDO), the Isotope Research Materials Laboratory (IRML), and the stable isotope inventories in the Isotope Enrichment Facility (IEF) have improved operational efficiencies and customer services. Recent changes in the IEP have included adopting policies for long-term contracts, which offer program stability and pricing advantages for the customer, and prorated service charges, which greatly improve pricing to the small research users. The former U.S. Department of Energy (DOE) Loan Program has been converted to a lease program, which makes large-quantity or very expensive isotopes available for nondestructive research at a nominal cost. Current efforts are being pursued to improve and expand the isotope separation capabilities as well as the extensive chemical- and physical-form processing that now exists. The IEF's quality management system is ISO 9002 registered and accredited in the United States, Canada, and Europe

  3. Carbon dioxide enrichment of greenhouse crops

    Energy Technology Data Exchange (ETDEWEB)

    Enoch, H.Z.; Kimball, B.A.

    1986-01-01

    This volume contains the following on these major topics of physiology, yield and economics: Fixation of Inorganic Carbon in Plant Cells. Effects of CO/sub 2/ Enrichment on Photosynthesis of C/sub 3/ Plants. Effects of CO/sub 2/ Concentration on Photosynthesis and Respiration of C/sub 4/ and CAM Plants. Effects of CO/sub 2/ Concentration on Composition, Anatomy, and Morphology of Plants. Stimulation of Growth and Yield Under Environmental Restraints. Woody Plant Reactions to CO/sub 2/ Enrichment. Influence of the CO/sub 2/ Content of the Ambient Air on Stomatal Conductance and CO/sub 2/ Concentration in Leaves. Influence of Elevated CO/sub 2/ on Crop Yield. Fertilization of Carnations and Some Other Flower Crops. CO/sub 2/ Enrichment for Greenhouse Rose Production. CO/sub 2/ Enrichment of Tomato Crops. CO/sub 2/ Enrichment Duration and Heating Credit as Determined by Climate. Economics of CO/sub 2/ Enrichment in Greenhouses. Units Conversion. Currency Exchange Rates.

  4. Development of a multi-pathogen enrichment broth for simultaneous growth of five common foodborne pathogens.

    Science.gov (United States)

    Chen, Juan; Tang, Junni; Bhunia, Arun K; Tang, Cheng; Wang, Changting; Shi, Hui

    2015-01-01

    The objective of the present study was to formulate a multi-pathogen enrichment broth which could support the simultaneous growth of five common foodborne pathogens (Salmonella enterica, Staphylococcus aureus, Shigella flexneri, Listeria monocytogenes and Escherichia coli O157:H7). The formulated broth SSSLE was composed of potassium tellurite, bile salt, lithium chloride, and sodium chloride as growth-inhibitors; glucose, esculin, mannitol and sodium pyruvate as growth-promoters. Compared with the respective specific selective enrichment broths, the individual growth pattern of each target pathogen in SSSLE was equal, or even better, except in the case of S. flexneri. In mixed-culture experiments, the gram-negative bacteria showed higher growth capabilities than the gram-positive bacteria after 8-h enrichment; however, the cell numbers after 24-h enrichment indicated that SSSLE could support the concurrent growth of five target pathogens irrespective of whether pathogens were inoculated initially at equal or unequal levels. For natural food samples under the high background flora, the final cell numbers enriched in SSSLE for five targets were enough to be detected by multiplex PCR. In conclusion, SSSLE was capable of supporting the growth of five target pathogens concurrently. The new broth formulated in this study has the potential of saving time, efforts and costs in multi-pathogen enrichment procedures. PMID:26782652

  5. Contribution of enrichments and resampling for sulfate reducing bacteria diversity assessment by high-throughput cultivation.

    Science.gov (United States)

    Colin, Yannick; Goñi-Urriza, Marisol; Caumette, Pierre; Guyoneaud, Rémy

    2015-03-01

    The development of new high-throughput cultivation methods aims to increase the isolation efficiency as compared to standard techniques that often require enrichment procedures to compensate the low microbial recovery. In the current study, estuarine sulfate-reducing bacteria were isolated using an anaerobic isolation procedure in 384-well microplates. Ninety-nine strains were recovered from initial sediments. Isolates were identified according to their partial 16S rRNA sequences and clustered into 13 phylotypes. Besides, the increase in species richness obtained through enrichments or resampling was investigated. Forty-four enrichment procedures were conducted and shifts in sulfate-reducing bacterial communities were investigated through dsrAB gene fingerprinting. Despite efforts in conducting numerous enrichment conditions only few of them were statistically different from initial sample. The cultural diversity obtained from 3 of the most divergent enrichments, as well as from resampled sediments equally contributed to raise the sulfate-reducing diversity up to 22 phylotypes. Enrichments (selection of metabolism) or resampling (transient populations and micro-heterogeneity) may still be helpful to assess new microbial phylotypes. Nevertheless, all the newly cultivated strains were all representatives of minor Operational Taxonomic Units and could eventually be recovered by maintaining high-throughput isolation effort from the initial sediments.

  6. ORGANIZATIONAL CULTURE AND MANAGEMENT CULTURE

    OpenAIRE

    Tudor Hobeanu; Loredana Vacarescu Hobeanu

    2010-01-01

    Communication reveals the importance of organizational culture and management culture supported by the remarkable results in economic and social level of organization. Their functions are presented and specific ways of expression levels of organizational culture and ways of adapting to the requirements of the organization's management culture.

  7. Nitrogen removal characteristics of indigenous aerobic denitrifiers and changes in the microbial community of a reservoir enclosure system via in situ oxygen enhancement using water lifting and aeration technology.

    Science.gov (United States)

    Zhou, Shilei; Huang, Tinglin; Ngo, Huu Hao; Zhang, Haihan; Liu, Fei; Zeng, Mingzheng; Shi, Jianchao; Qiu, Xiaopeng

    2016-08-01

    Indigenous aerobic denitrifiers of a reservoir system were enhanced in situ by water lifting and aeration technology. Nitrogen removal characteristics and changes in the bacterial community were investigated. Results from a 30-day experiment showed that the TN in the enhanced water system decreased from 1.08-2.02 to 0.75-0.91mg/L and that TN removal rates varied between 21.74% and 52.54% without nitrite accumulation, and TN removal rate of surface sediments reached 41.37±1.55%. The densities of aerobic denitrifiers in the enhanced system increased. Furthermore, the enhanced system showed a clear inhibition of Fe, Mn, and P performances. Community analysis using Miseq showed that diversity was higher in the in situ oxygen enhanced system than in the control system. In addition, the microbial composition was significantly different between systems. It can be concluded that in situ enhancement of indigenous aerobic denitrifiers is very effective in removing nitrogen from water reservoir systems. PMID:27128190

  8. Enhancing effect of induced crystallization process on denitrifying phosphorus removal%诱导结晶对反硝化除磷的强化作用

    Institute of Scientific and Technical Information of China (English)

    顾倩; 吕锡武; 史静; 李洁

    2013-01-01

    To investigate the enhancing effect of induced crystallization on the denitrifying phosphorus removal,experiments were carried out by combining the two-sludge system and the induced crystallization process.The results show that the phosphorus recovery rate of induced crystallizer is not greatly improved when the mole ratio of n(Ca2+)/n(PO43--P) reaches 5∶1.The optimum value of n (Ca2 +)/n (PO43--P) is 3∶1 which achieves a phosphorus recovery rate of 62.05 %.Appropriately increasing the amount of phosphorus recovery does not have a significant effect on the amount of anaerobic phosphorus release.When the amount of phosphorus release maintains at (13.44 ± 0.55)mg/L,the amount of phosphorus uptake decreases from 21.11 to 16.42 mg/L.The ratio of phosphorus uptake amount to release amount falls from 1.51 to 1.24 along with a high recovery rate,which means that the burden of bio-P removal is lightened.During the prior period of denitrifying phosphorus removal,the rate of phosphorus uptake goes down while the amount of phosphorus recovery increases,but the reaction of denitrifying phosphorus removal all ends after 30 min.Chemical phosphorus recovery do not cause negative effect on biological phosphorus removal.Moreover,the process which combines biological phosphorus removal with chemical phosphorus recovery can ensure that the effluent quality meets the related requirements under the condition of low influent CODto-phosphorus mass ratio.%以双污泥-诱导结晶工艺为研究对象,考察诱导结晶工艺回收磷对反硝化除磷的强化作用.结果表明,当摩尔比n(Ca2+)/n(PO43--P)提高到5∶1时,反应器内回收率没有明显的提高,最佳n(Ca2+)/n(PO43--P)为3∶1,回收率可达62.05%;提高磷回收量对厌氧释磷影响并不大,当释磷量保持在(13.44±0.55) mg/L时,聚磷量由21.11 mg/L降至16.42 mg/L,聚磷量与释磷量之比从1.51降至1.24,化学回收磷减轻了生物除磷负担;提高结晶磷回收量会降低聚磷

  9. Nitrous Oxide Emission and Denitrifier Abundance in Two Agricultural Soils Amended with Crop Residues and Urea in the North China Plain

    Science.gov (United States)

    Jin, Haiyang; Liu, Yuan; Bai, Xueying; Ma, Dongyun; Zhu, Yunji; Wang, Chenyang; Guo, Tiancai

    2016-01-01

    The application of crop residues combined with Nitrogen (N) fertilizer has been broadly adopted in China. Crop residue amendments can provide readily available C and N, as well as other nutrients to agricultural soils, but also intensify the N fixation, further affecting N2O emissions. N2O pulses are obviously driven by rainfall, irrigation and fertilization. Fertilization before rainfall or followed by flooding irrigation is a general management practice for a wheat-maize rotation in the North China Plain. Yet, little is known on the impacts of crop residues combined with N fertilizer application on N2O emission under high soil moisture content. A laboratory incubation experiment was conducted to investigate the effects of two crop residue amendments (maize and wheat), individually or in combination with N fertilizer, on N2O emissions and denitrifier abundance in two main agricultural soils (one is an alluvial soil, pH 8.55, belongs to Ochri-Aquic Cambosols, OAC, the other is a lime concretion black soil, pH 6.61, belongs to Hapli-Aquic Vertosols, HAV) under 80% WFPS (the water filled pore space) in the North China Plain. Each type soil contains seven treatments: a control with no N fertilizer application (CK, N0), 200 kg N ha-1 (N200), 250 kg N ha-1 (N250), maize residue plus N200 (MN200), maize residue plus N250 (MN250), wheat residue plus N200 (WN200) and wheat residue plus N250 (WN250). Results showed that, in the HAV soil, MN250 and WN250 increased the cumulative N2O emissions by 60% and 30% compared with N250 treatment, respectively, but MN200 and WN200 decreased the cumulative N2O emissions by 20% and 50% compared with N200. In the OAC soil, compared with N200 or N250, WN200 and WN250 increased the cumulative N2O emission by 40%-50%, but MN200 and MN250 decreased the cumulative N2O emission by 10%-20%. Compared with CK, addition of crop residue or N fertilizer resulted in significant increases in N2O emissions in both soils. The cumulative N2O emissions

  10. Nitrous Oxide Emission and Denitrifier Abundance in Two Agricultural Soils Amended with Crop Residues and Urea in the North China Plain.

    Directory of Open Access Journals (Sweden)

    Jianmin Gao

    Full Text Available The application of crop residues combined with Nitrogen (N fertilizer has been broadly adopted in China. Crop residue amendments can provide readily available C and N, as well as other nutrients to agricultural soils, but also intensify the N fixation, further affecting N2O emissions. N2O pulses are obviously driven by rainfall, irrigation and fertilization. Fertilization before rainfall or followed by flooding irrigation is a general management practice for a wheat-maize rotation in the North China Plain. Yet, little is known on the impacts of crop residues combined with N fertilizer application on N2O emission under high soil moisture content. A laboratory incubation experiment was conducted to investigate the effects of two crop residue amendments (maize and wheat, individually or in combination with N fertilizer, on N2O emissions and denitrifier abundance in two main agricultural soils (one is an alluvial soil, pH 8.55, belongs to Ochri-Aquic Cambosols, OAC, the other is a lime concretion black soil, pH 6.61, belongs to Hapli-Aquic Vertosols, HAV under 80% WFPS (the water filled pore space in the North China Plain. Each type soil contains seven treatments: a control with no N fertilizer application (CK, N0, 200 kg N ha-1 (N200, 250 kg N ha-1 (N250, maize residue plus N200 (MN200, maize residue plus N250 (MN250, wheat residue plus N200 (WN200 and wheat residue plus N250 (WN250. Results showed that, in the HAV soil, MN250 and WN250 increased the cumulative N2O emissions by 60% and 30% compared with N250 treatment, respectively, but MN200 and WN200 decreased the cumulative N2O emissions by 20% and 50% compared with N200. In the OAC soil, compared with N200 or N250, WN200 and WN250 increased the cumulative N2O emission by 40%-50%, but MN200 and MN250 decreased the cumulative N2O emission by 10%-20%. Compared with CK, addition of crop residue or N fertilizer resulted in significant increases in N2O emissions in both soils. The cumulative N2O

  11. Conversion of Crude Oil to Methane by a Microbial Consortium Enriched From Oil Reservoir Production Waters

    Directory of Open Access Journals (Sweden)

    Carolina eBerdugo-Clavijo

    2014-05-01

    Full Text Available The methanogenic biodegradation of crude oil is an important process occurring in petroleum reservoirs and other oil-containing environments such as contaminated aquifers. In this process, syntrophic bacteria degrade hydrocarbon substrates to products such as acetate, and/or H2 and CO2 that are then used by methanogens to produce methane in a thermodynamically dependent manner. We enriched a methanogenic crude oil-degrading consortium from production waters sampled from a low temperature heavy oil reservoir. Alkylsuccinates indicative of fumarate addition to C5 and C6 n-alkanes were identified in the culture (above levels found in controls, corresponding to the detection of an alkyl succinate synthase gene (assA in the culture. In addition, the enrichment culture was tested for its ability to produce methane from residual oil in a sandstone-packed column system simulating a mature field. Methane production rates of up 5.8 μmol CH4/g of oil/day were measured in the column system. Amounts of produced methane were in relatively good agreement with hydrocarbon loss showing depletion of more than 50% of saturate and aromatic hydrocarbons. Microbial community analysis revealed that the enrichment culture was dominated by members of the genus Smithella, Methanosaeta, and Methanoculleus. However, a shift in microbial community occurred following incubation of the enrichment in the sandstone columns. Here, Methanobacterium sp. were most abundant, as were bacterial members of the genus Pseudomonas and other known biofilm forming organisms. Our findings show that microorganisms enriched from petroleum reservoir waters can bioconvert crude oil components to methane both planktonically and in sandstone-packed columns as test systems. Further, the results suggest that different organisms may contribute to oil biodegradation within different phases (e.g., planktonic versus sessile within a subsurface crude oil reservoir.

  12. 反硝化菌株GW1的筛选及特性研究%Isolation and characteristics of denitrifying bacterium strain GW1

    Institute of Scientific and Technical Information of China (English)

    李海波; 廉静; 李敏; 陈建荣; 赵丽君; 姜宗姗; 许志芳; 王晓磊; 郭建博

    2012-01-01

    A highly active denitrifier named GW1 was isolated from the denitrification granule sludge,and 16S rDNA identification of the strain was performed. Influencing factors such as temperature,pH,carbon source and C/N ratio were optimized through batch experiments,and the effect of nitrate concentration on the denitrification was also studied. The phylogenetic analysis based on 16S rDNA suggests that strain GW1 is the closest relative of Paracoccus versutus with 99. 9 % sequence similarity and high homology. Genbank sequence number is GU111570. Strain GW1 is Gram-positive. The optimal conditions for the denitrification by strain GW1 are sodium succinate as carbon source,temperature 35 ~ 40℃,pH(7.0 ~ 8.0)and proposed project use of C/N ratio 3,respectively. Strain GW1 can remove nitrate effectively. The study may help solve the problem of slow denitrifying rate.%研究利用反硝化培养基,从实验室厌氧反硝化颗粒污泥中分离、筛选出1株反硝化优势菌株GW1,通过16S rDNA序列分析对其初步鉴定,并研究了温度、pH值、碳源、碳氮比和硝酸盐氮质量浓度对菌株GW1反硝化特性的影响.研究结果表明,菌株GW1的16S rDNA基因序列与Paracoccus versutus有最大相似性,达到99.9%,Genebank登录序列号为GU111570;分离菌株呈革兰氏阳性;最佳反硝化条件:丁二酸钠为碳源,温度为35~40℃,pH值为7.0~8.0,建议工程应用碳氮比为3∶1(质量比).该菌株特性的研究为解决反硝化速率过慢问题提供了技术支持.

  13. Global Nomads and the Search for Cultural Identity: Tips from the Classroom

    Science.gov (United States)

    Al-Issa, Ahmad

    2004-01-01

    Understanding one's cultural system leads to greater skills in appreciating other cultures. When students and teachers from diverse cultural backgrounds come together, they bring diversity that can either improve or break down the process of learning and teaching. If handled properly, cultural diversity can enrich the classroom; if ignored,…

  14. Throat Culture

    Science.gov (United States)

    ... limited. Home Visit Global Sites Search Help? Throat Culture Share this page: Was this page helpful? Collecting | ... treatment | Getting results | see BLOOD SAMPLE Collecting A culture is a test that is often used to ...

  15. Repellent Culture.

    Science.gov (United States)

    Carroll, Jeffrey

    2001-01-01

    Considers defining "culture," noting how it is difficult to define because those individuals defining it cannot separate themselves from it. Relates these issues to student writing and their writing improvement. Addresses violence in relation to culture. (SG)

  16. Culturing Protozoa.

    Science.gov (United States)

    Stevenson, Paul

    1980-01-01

    Compares various nutrient media, growth conditions, and stock solutions used in culturing protozoa. A hay infusion in Chalkey's solution maintained at a stable temperature is recommended for producing the most dense and diverse cultures. (WB)

  17. Corporate culture

    OpenAIRE

    Stoklasa, Pavel

    2010-01-01

    The theme of the bachelor's thesis is corporate culture, that is currently becoming a very important part of every company. In the theoretical part provides views of the individual authors on this issue. Here are also explained important concepts related to this topic. In particular, the elements of corporate culture, corporate culture change and determinants, that affect it. Furthermore, the theoretical part describes the most famous typology of corporate cultures international authors. The ...

  18. Safety culture

    Energy Technology Data Exchange (ETDEWEB)

    Keen, L.J. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)

    2003-07-01

    Safety culture has become a topic of increasing interest for industry and regulators as issues are raised on safety problems around the world. The keys to safety culture are organizational effectiveness, effective communications, organizational learning, and a culture that encourages the identification and resolution of safety issues. The necessity of a strong safety culture places an onus on all of us to continually question whether the safety measures already in place are sufficient, and are being applied. (author)

  19. Profile of World Uranium Enrichment Programs-2009

    Energy Technology Data Exchange (ETDEWEB)

    Laughter, Mark D [ORNL

    2009-04-01

    It is generally agreed that the most difficult step in building a nuclear weapon is acquiring fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, whereas HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium (LEU) for use as fuel for nuclear reactors to generate electricity. However, the same equipment used to produce LEU for nuclear reactor fuel can also be used to produce HEU for weapons. Safeguards at an enrichment plant are the array of assurances and verification techniques that ensure uranium is not diverted or enriched to HEU. There are several techniques for enriching uranium. The two most prevalent are gaseous diffusion, which uses older technology and requires a lot of energy, and gas centrifuge separation, which uses more advanced technology and is more energy efficient. Gaseous diffusion plants (GDPs) provide about 40% of current world enrichment capacity but are being phased out as newer gas centrifuge enrichment plants (GCEPs) are constructed. Estimates of current and future enrichment capacity are always approximate, due to the constant upgrades, expansions, and shutdowns occurring at enrichment plants, largely determined by economic interests. Currently, the world enrichment capacity is approximately 56 million kilogram separative work units (SWU) per year, with 22.5 million in gaseous diffusion and more than 33 million in gas centrifuge plants. Another 34 million SWU/year of capacity is under construction or planned for the near future, almost entirely using gas centrifuge separation. Other less-efficient techniques have also been used in the past, including electromagnetic and aerodynamic separations, but these are considered obsolete, at least from a commercial perspective. Laser isotope separation shows promise as a possible enrichment technique of the future but has yet to be

  20. How is uranium supply affecting enrichment?

    International Nuclear Information System (INIS)

    As a result of the enlivened uranium market, momentum has in turn picked up in the enrichment sector. What are the consequences of higher uranium prices? There is, of course, a link between uranium and enrichment supply to the extent that they are at least partial substitutes. On the enrichment supply side, the most obvious feature is the gradual replacement of the old gas diffusion facilities of Usec in the USA and EURODIF in France with more modern and economical centrifuge plants. Assuming Usec can overcome the financing and technical issues surrounding its plans, the last gas diffusion capacity should disappear around 2015 and the entire enrichment market should then be using centrifuges. On the commercial side, the key anticipated developments are mostly in Russia. Although there should still continue to be substantial quantities of surplus Russian HEU available for down blending in the period beyond 2013, it is now reasonable to expect that it will be mostly consumed by internal needs, to fuel Russian-origin reactors both at home and in export markets such as China and India. Finally, as a key sensitive area for the non-proliferation of nuclear weapons, the enrichment sector is likely to be a central point of the new international arrangements which must be developed to support a buoyant nuclear sector throughout this century.