WorldWideScience
1

Anaerobic ferrous oxidation by heterotrophic denitrifying enriched culture.  

Science.gov (United States)

Heterotrophic denitrifying enriched culture (DEC) from a lab-scale high-rate denitrifying reactor was discovered to perform nitrate-dependent anaerobic ferrous oxidation (NAFO). The DEC was systematically investigated to reveal their denitrification activity, their NAFO activity, and the predominant microbial population. The DEC was capable of heterotrophic denitrification with methanol as the electron donor, and autotrophic denitrification with ferrous salt as the electron donor named NAFO. The conversion ratios of ferrous-Fe and nitrate-N were 87.41 and 98.74 %, and the consumption Fe/N ratio was 2.3:1 (mol/mol). The maximum reaction velocity and half saturation constant of Fe were 412.54 mg/(l h) and 8,276.44 mg/l, and the counterparts of N were 20.87 mg/(l h) and 322.58 mg/l, respectively. The predominant bacteria were Hyphomicrobium, Thauera, and Flavobacterium, and the predominant archaea were Methanomethylovorans, Methanohalophilus, and Methanolobus. The discovery of NAFO by heterotrophic DEC is significant for the development of wastewater treatment and the biogeochemical iron cycle and nitrogen cycle. PMID:24619339

Wang, Ru; Zheng, Ping; Xing, Ya-Juan; Zhang, Meng; Ghulam, Abbas; Zhao, Zhi-Qing; Li, Wei; Wang, Lan

2014-05-01

2

Selenite Reduction by a Denitrifying Culture: Batch- and Packed-Bed- Reactor Studies  

Energy Technology Data Exchange (ETDEWEB)

Selenite reduction by a bacterial consortium enriched from an oil refinery waste sludge was studied under denitrifying conditions using acetate as the electron donor. Fed-batch studies with nitrate as the primary electron acceptor showed that accumulation of nitrite led to a decrease in the extent of selenite reduction. Also, when nitrite was added as the primary electron acceptor, rapid selenite reduction was observed only after nitrite was significantly depleted from the medium. These results indicate that selenite reduction was inhibited at high nitrite concentrations. In addition to batch experiments, continuous flow selenite reduction experiments were performed in packed-bed columns using immobilized enrichment cultures. These experiments were carried out in three phases: In phase-I, a continuous nitrate feed with different inlet selenite concentration was applied; in phase-II, nitrate was fed in a pulsed fashion; and in phase-III, nitrate was fed in a continuous mode but at much lower concentrations than the other two phases. During the phase-I experiments, little selenite was removed from the influent. However, when the column was operated in the pulse feed strategy (phase II), or in the continuous mode with low nitrate levels (phase-III), significant quantities of selenium was removed from solution and retained in the immobilization matrix in the column. Thus, immobilized denitrifying cultures can be effective in removing selenium from waste streams, but nitrate-limited operating conditions might be required.

William A. Apel; Sridhar Viamajala; Yared Bereded-Samuel; James N. Petersen

2006-08-01

3

Selenite reduction by a denitrifying culture: batch- and packed-bed reactor studies.  

Science.gov (United States)

Selenite reduction by a bacterial consortium enriched from an oil refinery waste sludge was studied under denitrifying conditions using acetate as the electron donor. Fed-batch studies with nitrate as the primary electron acceptor showed that accumulation of nitrite led to a decrease in the extent of selenite reduction. Also, when nitrite was added as the primary electron acceptor, rapid selenite reduction was observed only after nitrite was significantly depleted from the medium. These results indicate that selenite reduction was inhibited at high nitrite concentrations. In addition to batch experiments, continuous-flow selenite reduction experiments were performed in packed-bed columns using immobilized enrichment cultures. These experiments were carried out in three phases: in phase I, a continuous nitrate feed with different inlet selenite concentration was applied; in phase II, nitrate was fed in a pulsed fashion; and in phase III, nitrate was fed in a continuous mode but at much lower concentrations than the other two phases. During the phase I experiments, little selenite was removed from the influent. However, when the column was operated in the pulse feed strategy (phase II) or in the continuous mode with low nitrate levels (phase III), significant quantities of selenium were removed from solution and retained in the immobilization matrix in the column. Thus, immobilized denitrifying cultures can be effective in removing selenium from waste streams, but nitrate-limited operating conditions might be required. PMID:16432744

Viamajala, Sridhar; Bereded-Samuel, Yared; Apel, William A; Petersen, James N

2006-08-01

4

Selenite reduction by a denitrifying culture: batch- and packed-bed reactor studies  

Energy Technology Data Exchange (ETDEWEB)

Selenite reduction by a bacterial consortium enriched from an oil refinery waste sludge was studied under denitrifying conditions using acetate as the electron donor. Fed-batch studies with nitrate as the primary electron acceptor showed that accumulation of nitrite led to a decrease in the extent of selenite reduction. Also, when nitrite was added as the primary electron acceptor, rapid selenite reduction was observed only after nitrite was significantly depleted from the medium. These results indicate that selenite reduction was inhibited at high nitrite concentrations. In addition to batch experiments, continuous-flow selenite reduction experiments were performed in packed-bed columns using immobilized enrichment cultures. These experiments were carried out in three phases: in phase I, a continuous nitrate feed with different inlet selenite concentration was applied; in phase II, nitrate was fed in a pulsed fashion; and in phase III, nitrate was fed in a continuous mode but at much lower concentrations than the other two phases. During the phase I experiments, little selenite was removed from the influent. However, when the column was operated in the pulse feed strategy (phase II) or in the continuous mode with low nitrate levels (phase III), significant quantities of selenium were removed from solution and retained in the immobilization matrix in the column. Thus, immobilized denitrifying cultures can be effective in removing selenium from waste streams, but nitrate-limited operating conditions might be required. (orig.)

Viamajala, S. [National Bioenergy Center, Golden, CO (United States). National Renewable Energy Lab.; Bereded-Samuel, Y.; Petersen, J.N. [Washington State Univ., Pullman, WA (United States). Dept. of Chemical Engineering; Apel, W.A. [Idaho National Lab., Idaho Falls, ID (United States). Biological Sciences Dept.

2006-08-15

5

Degradation of Phthalic Acids by Denitrifying, Mixed Cultures of Bacteria  

OpenAIRE

Mixed cultures of bacteria, enriched from aquatic sediments, grew anaerobically on all three isomers of phthalic acid. Each culture grew anaerobically on only one isomer and also grew aerobically on the same isomer. Pure cultures were isolated from the phthalic acid (o-phthalic acid) and isophthalic acid (m-phthalic acid) enrichments that grew aerobically on phthalic and isophthalic acids. Cell suspension experiments indicated that protocatechuate is an intermediate of aerobic catabolism. Pur...

Aftring, R. Paul; Chalker, Bruce E.; Taylor, Barrie F.

1981-01-01

6

Production of NO and N2O by Pure Cultures of Nitrifying and Denitrifying Bacteria during Changes in Aeration  

OpenAIRE

Peak emissions of NO and N2O are often observed after wetting of soil. The reactions to sudden changes in the aeration of cultures of nitrifying and denitrifying bacteria with respect to NO and N2O emissions were compared to obtain more information about the microbiological aspects of peak emissions. In continuous culture, the nitrifier Nitrosomonas europaea and the denitrifiers Alcaligenes eutrophus and Pseudomonas stutzeri were cultured at different levels of aeration (80 to 0% ...

Kester, R. A.; Boer, W.; Laanbroek, H. J.

1997-01-01

7

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 sment 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.

8

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

Science.gov (United States)

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

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

2006-01-01

9

21 CFR 866.2330 - Enriched culture medium.  

Science.gov (United States)

...2010-04-01 false Enriched culture medium. 866.2330...866.2330 Enriched culture medium. (a) Identification. An enriched culture medium is a device...vitamins, and extracts of plant or animal tissues. The device is...

2010-04-01

10

Functional characterization of heterotrophic denitrifying bacteria in activated sludge  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Wastewater treatment facilities are largely accountable for the detrimental enrichment of water bodies with nitrogenous compounds, resulting in eutrophication. Denitrification is of interest as a means of removing nitrates and nitrites from water supplies because they are also hazardous to human hea [...] lth. The integration of biological nutrient removal into conventional wastewater treatment processes has, however, failed to take into sufficient consideration the role of key microorganisms present, specifically denitrifying bacteria. The purpose of the study reported here was to group such heterotrophic denitrifying bacteria using a series of biochemical and molecular analyses, to achieve an improved understanding of their functions. The role of the denitrifying bacteria in reducing nitrate and nitrite was monitored using the colorimetric nitrate reduction test. The genetic diversity of the culture collection was investigated by the use of denaturing gradient gel electrophoresis (DGGE), which enabled the creation of a microbial population profile of eight predominant isolates. Batch experiments were conducted on these isolates, the results of which ultimately confirmed their classification according to their respective functions, namely, incomplete denitrifiers, true denitrifiers, sequential denitrifiers, and exclusive nitrite reducers.

Nishani, Ramdhani; Faizal, Bux.

2007-04-01

11

Enrichment of high ammonia tolerant methanogenic culture  

DEFF Research Database (Denmark)

Ammonia is the major toxicant in full scale anaerobic digesters of animal wastes which are rich in proteins and/or urea, such as pig or poultry wastes. Ammonia inhibition decreases methane production rates, increases volatile fatty acids concentration and leads to economic losses for the biogas plants. The methods used today to counteract ammonia inhibition are slow and costexpensive. A new biological approach to avoid or counteract ammonia inhibition by using ammonia tolerant methanogens, could provide a sustainable solution for cost-effective digestion of abundant ammonia-rich wastes. The aim 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 exclusively to strict aceticlastic methanogens. Results obtained in this study, demonstrated for the first time that strictly aceticlastic methanogens, derived from an enriched culture, can efficiently produce methane under high ammonia levels.

Fotidis, Ioannis; Karakashev, Dimitar Borisov

12

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

Science.gov (United States)

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

Otani, Y; Hasegawa, K; Hanaki, K

2004-01-01

13

Metatranscriptome of an anaerobic benzene-degrading, nitrate-reducing enrichment culture reveals involvement of carboxylation in benzene ring activation.  

Science.gov (United States)

The enzymes involved in the initial steps of anaerobic benzene catabolism are not known. To try to elucidate this critical step, a metatranscriptomic analysis was conducted to compare the genes transcribed during the metabolism of benzene and benzoate by an anaerobic benzene-degrading, nitrate-reducing enrichment culture. RNA was extracted from the mixed culture and sequenced without prior mRNA enrichment, allowing simultaneous examination of the active community composition and the differential gene expression between the two treatments. Ribosomal and mRNA sequences attributed to a member of the family Peptococcaceae from the order Clostridiales were essentially only detected in the benzene-amended culture samples, implicating this group in the initial catabolism of benzene. Genes similar to each of two subunits of a proposed benzene-carboxylating enzyme were transcribed when the culture was amended with benzene. Anaerobic benzoate degradation genes from strict anaerobes were transcribed only when the culture was amended with benzene. Genes for other benzoate catabolic enzymes and for nitrate respiration were transcribed in both samples, with those attributed to an Azoarcus species being most abundant. These findings indicate that the mineralization of benzene starts with its activation by a strict anaerobe belonging to the Peptococcaceae, involving a carboxylation step to form benzoate. These data confirm the previously hypothesized syntrophic association between a benzene-degrading Peptococcaceae strain and a benzoate-degrading denitrifying Azoarcus strain for the complete catabolism of benzene with nitrate as the terminal electron acceptor. PMID:24795366

Luo, Fei; Gitiafroz, Roya; Devine, Cheryl E; Gong, Yunchen; Hug, Laura A; Raskin, Lutgarde; Edwards, Elizabeth A

2014-07-01

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Enrichment and microbial characterization of syngas converting anaerobic cultures  

OpenAIRE

Bioconversion of recalcitrant biomass/waste into bulk chemicals or biofuels is often not feasible. By gasification of these materials, syngas (mainly composed of CO2, CO and H2) is generated and can be used for the production of high value compounds by thermochemical or biotechnological processes. Here, three thermophilic cultures enriched with syngas mixtures or pure CO (T-Syn, T-Syn-CO and T-CO) were studied. Stable enriched cultures obtained by subsequent transfers for over a year, convert...

Alves, J. I.; Visser, Michael; Stams, A. J. M.; Plugge, Caroline M.; Alves, M. M.; Sousa, D. Z.

2013-01-01

15

Methanogenic degradation of acetone by an enrichment culture  

OpenAIRE

An anaerobic enrichment culture degraded 1 mol of acetone to 2 tool of methane and 1 tool of carbon dioxide. Two microorganisms were involved in this process, a filament-forming rod similar to Methanothrix sp. and an unknown rod with round to slightly pointed ends. Both organisms formed aggregates up to 300 gm in diameter. No fluorescing bacteria were observed indicating that hydrogen or formate-utilizing methanogens are not involved in this process. Acetate was utilized in this culture by th...

Platen, Harald; Schink, Bernhard

1987-01-01

16

Anaerobic Naphthalene Degradation by a Sulfate-Reducing Enrichment Culture  

OpenAIRE

Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied by substrate utilization tests and identification of metabolites by gas chromatography-mass spectrometry. In substrate utilization tests, the culture was able to oxidize naphthalene, 2-methylnaphthalene, 1- and 2-naphthoic acids, phenylacetic acid, benzoic acid, cyclohexanecarboxylic acid, and cyclohex-1-ene-carboxylic acid with sulfate as the electron acceptor. Neither hydroxylated 1- or 2-naphthoic acid d...

Meckenstock, Rainer U.; Annweiler, Eva; Michaelis, Walter; Richnow, Hans H.; Schink, Bernhard

2000-01-01

17

Anaerobic oxidation of acetylene by estuarine sediments and enrichment cultures  

International Nuclear Information System (INIS)

Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloroamphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2

18

Highly enriched Betaproteobacteria growing anaerobically with p-xylene and nitrate  

DEFF Research Database (Denmark)

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-degrading Betaproteobacteria from the Azoarcus-Thauera clade. Complete oxidation p-xylene to CO(2) coupled to denitrification was suggested by quantitative measurements of substrate consumption. Metabolite analysis identified (4-methylbenzyl)succinate and (4-methylphenyl)itaconate, suggesting addition to fumarate as an initial activation reaction.

Rotaru, Amelia-Elena; Probian, Christina

2010-01-01

19

Dimethylamine biodegradation by mixed culture enriched from drinking water biofilter.  

Science.gov (United States)

Dimethylamine (DMA) is one of the important precursors of drinking water disinfection by-product N-nitrosodimethylamine (NDMA). Reduction of DMA to minimize the formation of carcinogenic NDMA in drinking water is of practical importance. Biodegradation plays a major role in elimination of DMA pollution in the environment, yet information on DMA removal by drinking water biofilter is still lacking. In this study, microcosms with different treatments were constructed to investigate the potential of DMA removal by a mixed culture enriched from a drinking water biofilter and the effects of carbon and nitrogen sources. DMA could be quickly mineralized by the enrichment culture. Amendment of a carbon source, instead of a nitrogen source, had a profound impact on DMA removal. A shift in bacterial community structure was observed with DMA biodegradation, affected by carbon and nitrogen sources. Proteobacteria was the predominant phylum group in DMA-degrading microcosms. Microorganisms from a variety of bacterial genera might be responsible for the rapid DMA mineralization. PMID:25280176

Liao, Xiaobin; Chen, Chao; Zhang, Jingxu; Dai, Yu; Zhang, Xiaojian; Xie, Shuguang

2015-01-01

20

Characterization of a Highly Enriched Dehalococcoides-Containing Culture That Grows on Vinyl Chloride and Trichloroethene  

OpenAIRE

A highly enriched culture that reductively dechlorinates trichloroethene (TCE), cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC) to ethene without methanogenesis is described. The Dehalococcoides strain in this enrichment culture had a yield of (5.6 ± 1.4) × 108 16S rRNA gene copies/?mol of Cl? when grown on VC and hydrogen. Unlike the other VC-degrading cultures described in the literature, strains VS and BAV1, this culture maintained the ability to grow on TCE with a yield of (3....

Duhamel, Melanie; Mo, Kaiguo; Edwards, Elizabeth A.

2004-01-01

21

Enrichment methodology to increase the positivity of cultures from body fluids  

OpenAIRE

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 avera...

Alessandra Valle Daur; Francisco Klimak Jr.; Laura Lúcia Cogo; Gislene Diógenes Botão; Cristina Leise Bastos Monteiro; Libera Maria Dalla Costa

2006-01-01

22

Isolation of Methylophaga spp. from Marine Dimethylsulfide-Degrading Enrichment Cultures and Identification of Polypeptides Induced during Growth on Dimethylsulfide?  

OpenAIRE

Dimethylsulfide (DMS)-degrading enrichment cultures were established from samples of coastal seawater, nonaxenic Emiliania huxleyi cultures, and mixed marine methyl halide-degrading enrichment cultures. Bacterial populations from a broad phylogenetic range were identified in the mixed DMS-degrading enrichment cultures by denaturing gradient gel electrophoresis (DGGE). Sequences of dominant DGGE bands were similar to those of members of the genera Methylophaga and Alcanivorax. Several closely ...

Scha?fer, Hendrik

2007-01-01

23

An Effectiveness Study of a Culturally Enriched School-Based CBT Anxiety Prevention Program  

Science.gov (United States)

Anxiety disorders are prevalent in the school-aged population and are present across cultural groups. Scant research exists on culturally relevant prevention and intervention programs for mental health problems in the Aboriginal populations. An established cognitive behavioral program, FRIENDS for Life, was enriched to include content that was…

Miller, Lynn D.; Laye-Gindhu, Aviva; Bennett, Joanna L.; Liu, Yan; Gold, Stephenie; March, John S.; Olson, Brent F.; Waechtler, Vanessa E.

2011-01-01

24

Use of ?-hexachlorocyclohexane as a terminal electron acceptor by an anaerobic enrichment culture.  

Science.gov (United States)

The use of ?-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 ?-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 ?-HCH consumed (on a molar basis), respectively. The enrichment culture remained active with only hydrogen as the electron donor and ?-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 ?-HCH dechlorination, suggesting that a Gram-positive organism is responsible for the reduction of ?-HCH. Analysis of the ?-HCH dechlorinating enrichment culture did not detect any known chlororespiring genera, including Dehalobacter. In bicarbonate-buffered medium, reductive dechlorination of ?-HCH was accompanied by significant levels of acetogenesis as well as methanogenesis. PMID:21983168

Elango, Vijai; Kurtz, Harry D; Anderson, Christina; Freedman, David L

2011-12-15

25

Use of ?-hexachlorocyclohexane as a terminal electron acceptor by an anaerobic enrichment culture  

International Nuclear Information System (INIS)

Highlights: ? Use of ?-hexachlorocyclohexane as a terminal electron acceptor was demonstrated. ? H2 served as the electron donor for an enrichment culture that dechlorinated ?-HCH. ? H2 consumption for acetogenesis and methanogenesis stopped in HEPES media. ? Addition of vancomycin significantly slowed the rate of ?-HCH dechlorination. ? Previously identified chlororespiring microbes were not detected in the enrichment. - Abstract: The use of ?-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 ?-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 ?-HCH consumed (on a molar basis), respectively. The enrichment culture remained active with only hydrogen as the electron donor and ?-HCH as the electron acceptor through several transfers to fresh mineral salts medium for more than one yeum for more than one year. Addition of vancomycin to the culture significantly slowed the rate of ?-HCH dechlorination, suggesting that a Gram-positive organism is responsible for the reduction of ?-HCH. Analysis of the ?-HCH dechlorinating enrichment culture did not detect any known chlororespiring genera, including Dehalobacter. In bicarbonate-buffered medium, reductive dechlorination of ?-HCH was accompanied by significant levels of acetogenesis as well as methanogenesis.

26

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

Energy Technology Data Exchange (ETDEWEB)

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, reductive dechlorination of {gamma}-HCH was accompanied by significant levels of acetogenesis as well as methanogenesis.

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

27

Summary report on the aerobic degradation of diesel fuel and the degradation of toluene under aerobic, denitrifying and sulfate reducing conditions  

International Nuclear Information System (INIS)

This report contains a number of studies that were performed to better understand the technology of the biodegradation of petroleum hydrocarbons. Topics of investigation include the following: diesel fuel degradation by Rhodococcus erythropolis; BTEX degradation by soil isolates; aerobic degradation of diesel fuel-respirometry; aerobic degradation of diesel fuel-shake culture; aerobic toluene degradation by A3; effect of HEPES, B1, and myo-inositol addition on the growth of A3; aerobic and anaerobic toluene degradation by contaminated soils; denitrifying bacteria MPNs; sulfate-reducing bacteria MPNs; and aerobic, DNB and SRB enrichments

28

Newly cultured bacteria with broad diversity isolated from 8 week continuous culture enrichments of cow feces on complex polysaccharides  

Science.gov (United States)

One of the fascinating functions of the mammalian intestinal microbiota is the fermentation of plant cell wall components. Eight week continuous culture enrichments of cow feces with cellulose and xylan/pectin were used to isolate bacteria from this community. A total of 459 bacterial isolates were ...

29

Enrichment of nitrous oxide reducing bacteria from coastal marsh sediments  

Directory of Open Access Journals (Sweden)

Full Text Available We attempted to recover organisms capable of respiratory nitrous oxide reduction with acetate as an electron donor from a variety of coastal marine sediments from Lavaca Bay area, Texas by use of liquid enrichment cultures. Putative positive cultures were analyzed by amplifying eubacterial and archaeal 16S rRNA gene fragments and analyzing their diversity by separating them by a denaturing gradient gel electrophoresis (DGGE. No Archaea was detected in our enrichments; however, positive enrichments from coastal salt marsh indicated the presence of putative nitrous oxide reducing bacteria. DGGE patterns of the amplified DNA were similar between enrichments, with ca. 7 obvious bands. The dominant bands were tentatively identified as members of the Gammaproteobacteria class, closely related to various denitrifying pseudomonads. Our results indicate that coastal marine environments may sustain a nitrous oxide reducing community, although nitrous oxide reduction is probably an opportunistic form of metabolism in that environment.

Khuong B. T. Nguyen

2013-07-01

30

Anaerobic Degradation of Acifluorfen by Different Enrichment Cultures  

OpenAIRE

A laboratory study on the biodegradation of acifluorfen in anaerobic conditions was conducted. Mixed and pure cultures isolated from activated sludges of a waste water treatment plant and from a soil with a long history of acifluorfen applications could reduce acifluorfen to aminoacifluorfen in a medium with the herbicide as sole source of carbon. Addition of sodium acetate and sodium 2-nitrobenzoate to the medium enhanced and decreased the reduction rate, respectively. A further transformati...

Andreoni, Vincenzina; Vincenti, Marco; Negre, Michele; Ambrosoli, Roberto; Gennari, Mara Maddalena

1994-01-01

31

Characteristics of anaerobic oxalate-degrading enrichment cultures from the rumen.  

OpenAIRE

Enrichment cultures of rumen bacteria degraded oxalate within 3 to 7 days in a medium containing 10% rumen fluid and an initial level of 45 mM sodium oxalate. This capability was maintained in serially transferred cultures. One mole of methane was produced per 3.8 mol of oxalate degraded. Molecular hydrogen and formate inhibited oxalate degradation but not methanogenesis; benzyl viologen and chloroform inhibited both oxalate degradation and methanogenesis. Attempts to isolate oxalate-degradin...

Dawson, K. A.; Allison, M. J.; Hartman, P. A.

1980-01-01

32

Faculty Use of Culturally Mediated Instruction in a Community College Academic Enrichment Program  

Science.gov (United States)

The purpose of this study was to examine faculty use of Culturally Mediated Instructional (CMI) practices in a community college-based academic enrichment program. The intent of the study was two-fold: (a) to search for evidence that instructional practices were reflective of Hollins' (1996) theory of CMI, and (b) to explore faculty perceptions of…

Lacey, Charna L.

2009-01-01

33

Broad diversity and newly cultured bacterial isolates from enrichment of pig feces on complex polysaccharides  

Science.gov (United States)

One of the fascinating functions of the mammalian intestinal microbiota is the fermentation of plant cell wall components. We used 8 week continuous culture enrichments of pig feces with cellulose and xylan/pectin to isolated bacteria from this community. A total of 575 bacterial isolates were class...

34

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

Science.gov (United States)

Denitrification is essential to the removal of nitrogen from wastewater during treatment, yet an understanding of the diversity of the active denitrifying bacteria responsible in full-scale wastewater treatment plants (WWTPs) is lacking. In this study, stable-isotope probing (SIP) was applied in combination with microautoradiography (MAR)-fluorescence in situ hybridization (FISH) to identify previously unrecognized active denitrifying phylotypes in a full-scale WWTP with biological N and P removal. Acknowledging that different denitrifiers will have specific carbon source preferences, a fully (13) C-labelled complex substrate was used for SIP incubations, under nitrite-reducing conditions, in order to maximize the capture of the potentially metabolically diverse denitrifiers likely present. Members of the Rhodoferax,?Dechloromonas, Sulfuritalea,?Haliangium and Thermomonas were represented in the 16S rRNA gene clone libraries from DNA enriched in (13) C, with FISH probes optimized here for their in situ characterization. FISH and MAR confirmed that they were all active denitrifiers in the community. The combined approach of SIP and MAR-FISH represents an excellent approach for identifying and characterizing an un-described diversity of active denitrifiers in full-scale systems. PMID:25181571

McIlroy, Simon Jon; Starnawska, Anna; Starnawski, Piotr; Saunders, Aaron Marc; Nierychlo, Marta; Nielsen, Per Halkjaer; Nielsen, Jeppe Lund

2014-09-01

35

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

DEFF Research Database (Denmark)

Denitrification is essential to the removal of nitrogen from wastewater during treatment, yet an understanding of the diversity of the active denitrifying bacteria responsible in full-scale wastewater treatment plants (WWTP) is lacking. In this study stable isotope probing (SIP) was applied 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 incubations, under nitrite reducing conditions, in order to better capture the diversity of active denitrifiers present. Members of the Rhodoferax, Dechloromonas and Sulfuritalea were well represented in the 16S rRNA gene clone libraries from DNA enriched in 13 C, with FISH probes designed here for their in situ characterisation. FISH and MAR confirmed that they were core active denitrifiers in the community. The SIP clone library was additionally represented by a phylogenetically diverse group of organisms, with many previously not considered as important denitrifiers. The combined approach of SIP and MAR-FISH represents an excellent approach for identifying and characterising un-described diversity of active denitrifiers in full-scale systems.

McIlroy, Simon Jon; Szyszka, Anna

2014-01-01

36

Microbial diversity of western Canadian subsurface coal beds and methanogenic coal enrichment cultures  

Energy Technology Data Exchange (ETDEWEB)

Coalbed methane is an unconventional fuel source associated with certain coal seams. Biogenic methane can comprise a significant portion of the gas found in coal seams, yet the role of microbes in methanogenesis in situ is uncertain. The purpose of this study was to detect and identify major bacterial and archaeal species associated with coal sampled from sub-bituminous methane-producing coal beds in western Canada, and to examine the potential for methane biogenesis from coal. Enrichment cultures of coal samples were established to determine how nutrient amendment influenced the microbial community and methane production in the laboratory. 16S rRNA gene clone libraries were constructed using DNA extracted and amplified from uncultured coal samples and from methanogenic coal enrichment cultures. Libraries were screened using restriction fragment length polymorphism, and representative clones were sequenced. Most (> 50%) of the bacterial sequences amplified from uncultured coal samples were affiliated with Proteobacteria that exhibit nitrate reduction, nitrogen fixation and/or hydrogen utilization activities, including Pseudomonas, Thauera and Acidovorax spp., whereas enrichment cultures were dominated by Bacteroidetes, Clostridia and/or Lactobacillales. Archaeal 16S rRNA genes could not be amplified from uncultured coal, suggesting that methanogens are present in coal below the detection levels of our methods. However, enrichment cultures established with coal inocula produced significant volumes of methane and the archaeal clone libraries were dominated by sequences closely affiliated with Methanosarcina spp. Enrichment cultures incubated with coal plus organic nutrients produced more methane than either nutrient or coal supplements alone, implying that competent methanogenic consortia exist in coal beds but that nutrient limitations restrict their activity in situ. This report adds to the scant literature on coal bed microbiology and suggests how microbes may be involved in biogenic coal bed methane production in situ. (author)

Penner, Tara J.; Foght, Julia M. [Department of Biological Sciences, University of Alberta, Edmonton, Alberta (Canada); Budwill, Karen [Carbon and Energy Management, Alberta Innovates-Technology Futures, 250 Karl Clark Road, Edmonton, Alberta (Canada)

2010-05-01

37

Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.  

OpenAIRE

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...

Hernandez, D.; Rowe, J. J.

1987-01-01

38

High-Affinity Methane Oxidation by a Soil Enrichment Culture Containing a Type II Methanotroph  

OpenAIRE

Methanotrophic bacteria in an organic soil were enriched on gaseous mixing ratios of 1020 times the initial soil inoculum), a mixed culture was obtained which displayed an apparent half-saturation constant [Km(app)] for CH4 of 56 to 186 nM (40 to 132 ppmv). This value was the same as that measured in the soil itself and about 1 order of magnitude lower than reported values for pure cultures of methane oxidizers. However, the Km(app) increased when the culture was transferred to higher mixing ...

Dunfield, Peter F.; Liesack, Werner; Henckel, Thilo; Knowles, Roger; Conrad, Ralf

1999-01-01

39

Characteristics of anaerobic oxalate-degrading enrichment cultures from the rumen.  

Science.gov (United States)

Enrichment cultures of rumen bacteria degraded oxalate within 3 to 7 days in a medium containing 10% rumen fluid and an initial level of 45 mM sodium oxalate. This capability was maintained in serially transferred cultures. One mole of methane was produced per 3.8 mol of oxalate degraded. Molecular hydrogen and formate inhibited oxalate degradation but not methanogenesis; benzyl viologen and chloroform inhibited both oxalate degradation and methanogenesis. Attempts to isolate oxalate-degrading bacteria from these cultures were not successful. Oxalate degradation was uncoupled from methane production when enrichments were grown in continuous culture at dilution rates greater than or equal to 0.078 h-1. Growth of the uncoupled population (lacking methanogens) in batch culture was accompanied by degradation of 45 mM oxalate within 24 h and production of 0.93 mol of formate per mol of oxalate degraded. Oxalate degradation by the uncoupled population was not inhibited by molecular hydrogen or formate. Cell yields (grams [dry weight]) per mole of oxalate degraded by the primary enrichment and the uncoupled populations were 1.7 and 1.0, respectively. PMID:7425629

Dawson, K A; Allison, M J; Hartman, P A

1980-10-01

40

Erythrocyte enrichment in hematopoietic progenitor cell cultures based on magnetic susceptibility of the hemoglobin.  

Science.gov (United States)

Using novel media formulations, it has been demonstrated that human placenta and umbilical cord blood-derived CD34+ cells can be expanded and differentiated into erythroid cells with high efficiency. However, obtaining mature and functional erythrocytes from the immature cell cultures with high purity and in an efficient manner remains a significant challenge. A distinguishing feature of a reticulocyte and maturing erythrocyte is the increasing concentration of hemoglobin and decreasing cell volume that results in increased cell magnetophoretic mobility (MM) when exposed to high magnetic fields and gradients, under anoxic conditions. Taking advantage of these initial observations, we studied a noninvasive (label-free) magnetic separation and analysis process to enrich and identify cultured functional erythrocytes. In addition to the magnetic cell separation and cell motion analysis in the magnetic field, the cell cultures were characterized for cell sedimentation rate, cell volume distributions using differential interference microscopy, immunophenotyping (glycophorin A), hemoglobin concentration and shear-induced deformability (elongation index, EI, by ektacytometry) to test for mature erythrocyte attributes. A commercial, packed column high-gradient magnetic separator (HGMS) was used for magnetic separation. The magnetically enriched fraction comprised 80% of the maturing cells (predominantly reticulocytes) that showed near 70% overlap of EI with the reference cord blood-derived RBC and over 50% overlap with the adult donor RBCs. The results demonstrate feasibility of label-free magnetic enrichment of erythrocyte fraction of CD34+ progenitor-derived cultures based on the presence of paramagnetic hemoglobin in the maturing erythrocytes. PMID:22952572

Jin, Xiaoxia; Abbot, Stewart; Zhang, Xiaokui; Kang, Lin; Voskinarian-Berse, Vanessa; Zhao, Rui; Kameneva, Marina V; Moore, Lee R; Chalmers, Jeffrey J; Zborowski, Maciej

2012-01-01

41

High-affinity methane oxidation by a soil enrichment culture containing a type II methanotroph  

Energy Technology Data Exchange (ETDEWEB)

Methanotrophic bacteria in an organic soil were enriched on gaseous mixing ratios of <275 parts per million of volume (ppmv) of methane (CH{sub 4}). After 4 years of growth and periodic dilution, a mixed culture was obtained which displayed an apparent half-saturation constant [K{sub m(app)}] for CH{sub 4} of 56 to 186 nM (40 to 132 ppmv). This value was the same as that measured in the soil itself and about 1 order of magnitude lower than reported values for pure cultures of methane oxidizers. However, the K{sub m(app)} increased when the culture was transferred to higher mixing ratios of CH{sub 4}. Denaturing gradient gel electrophoresis of the enrichment grown on <275 ppmv of CH{sub 4} revealed a single gene product of pmoA, which codes for a subunit of particulate methane monooxygenase. This suggested that only one methanotroph species was present. This organism was isolated from a sample of the enrichment culture grown on 1% CH{sub 4} and phylogenetically positioned based on its 16S rRNA, pmoA, and mxaF gene sequences as a type II strain of the Methlocystis/Methylosinus group. A coculture of this strain with a Variovorax sp., when grown on <275 ppmv of CH{sub 4}, had a K{sub m(app)} similar to that of the initial enrichment culture. The data suggest that the affinity of methanotrophic bacteria for CH{sub 4} varies with growth conditions and that the oxidation of atmospheric CH{sub 4} observed in this soil is carried out by type II methanotrophic bacteria which are similar to characterized species.

Dunfield, P.F. [Max-Planck-Inst. fuer Terrestrische Mikrobiologie, Marburg (Germany)]|[McGill Univ., Ste. Anne de Bellevue, Quebec (Canada). Dept. of Natural Resource Sciences; Liesack, W.; Henckel, T.; Conrad, R. [Max-Planck-Inst. fuer Terrestrische Mikrobiologie, Marburg (Germany); Knowles, R. [McGill Univ., Ste. Anne de Bellevue, Quebec (Canada). Dept. of Natural Resource Sciences

1999-03-01

42

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

Directory of Open Access Journals (Sweden)

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

Spasojevi? Bojana

2013-01-01

43

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

OpenAIRE

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...

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

2013-01-01

44

Halobacterium denitrificans sp. nov., an extremely halophilic denitrifying bacterium  

Science.gov (United States)

Halobacterium denitrificans was one of several carbohydrate-utilizing, denitrifying, extremely halophilic bacteria isolated by anaerobic enrichment in the presence of nitrate. Anaerobic growth took place only when nitrate (or nitrite) was present and was accompanied by the production of dinitrogen. In the presence of high concentrations of nitrate (i.e., 0.5 percent), nitrous oxide and nitrite were also detected. When grown aerobically in a mineral-salts medium containing 0.005 percent yeast extract, H. denitrificans utilized a variety of carbohydrates as sources of carbon and energy. In every case, carbohydrate utilization was accompanied by acid production.

Tomlinson, G. A.; Jahnke, L. L.; Hochstein, L. I.

1986-01-01

45

Halobacterium denitrificans sp. nov. - An extremely halophilic denitrifying bacterium  

Science.gov (United States)

Halobacterium denitrificans was one of several carbohydrate-utilizing, denitrifying, extremely halophilic bacteria isolated by anaerobic enrichment in the presence of nitrate. Anaerobic growth took place only when nitrate (or nitrite) was present and was accompanied by the production of dinitrogen. In the presence of high concentrations of nitrate (i.e., 0.5 percent), nitrous oxide and nitrite were also detected. When grown aerobically in a mineral-salts medium containing 0.005 percent yeast extract, H. denitrificans utilized a variety of carbohydrates as sources of carbon and energy. In every case, carbohydrate utilization was accompanied by acid production.

Tomlinson, G. A.; Jahnke, L. L.; Hochstein, L. I.

1986-01-01

46

Impact of non-storing biomass on PHA production: an enrichment culture on acetate and methanol.  

Science.gov (United States)

The use of enrichment cultures for polyhydroxyalkanoate (PHA) production from substrate mixtures such as wastewater inevitably results in the establishment of a non-PHA-storing population besides the PHA-producing bacteria. This reduces the maximum PHA content that can be established, and increases downstream-processing costs. The aim of this study was to investigate the impact of non-storing biomass on the PHA production process. A microbial culture was enriched in a sequencing batch reactor fed with acetate and methanol. Methanol served as model substrate for compounds unsuitable for PHA production. The enrichment was dominated by Plasticicumulans acidivorans, a known PHA producer, and Methylobacillus flagellatus, an obligate methylotroph that cannot store PHA. As expected, the presence of the non-storing population lowered the maximum PHA content of the culture, from more than 80 to 66wt.%. To mimic a nitrogen-rich waste stream, additional accumulation experiments were performed with continuous supply of carbon and ammonium. In these experiments P. acidivorans still accumulated large amounts of PHA, but unrestricted growth of the non-storing, methylotrophic population reduced the maximum overall PHA content to 52wt.%. Besides ammonium limitation, other strategies to restrict the fraction of non-storing biomass should be developed. The mixture of acetate and methanol is a useful model substrate for the development of such strategies. PMID:24802855

Marang, Leonie; Jiang, Yang; van Loosdrecht, Mark C M; Kleerebezem, Robbert

2014-11-01

47

Development of water purification technologies for intensive fish culture. 3. Konoritsu gyorui seisan no tame no suishitsu joka gijutsu no kaihatsu. 3. ; Dacchitsugata kara mita yuyo kaiyosei dacchitsu kinshu no senbatsu  

Energy Technology Data Exchange (ETDEWEB)

Useful strains of marine denitrifying bacteria were selected for the establishment of effective denitrification system to remove nitrate accumulating in the cultural water of seawater-recirculating aquaculture system. Enrichment culture method was adopted for the isolation of denitrifying bacteria, a higher probability in the isolation was shown by the nitrite added culture method than that by the nitrate added one. The denitrification patterns of isolated denitrifying bacteria were discriminated, and the 16 strains which were considered as useful one for the intensive fish culture system were selected. Since these strains produce only gaseous nitrogen without producing toxic nitrite in the process of denitrification, they are very suitable for the system. As for the genus of 16 strains of which their activities are not changed even in continuous culture, nine strains were genus Pseudomonas and seven strains were genus Alcaligenes. Denitrifying rates of 16 strains were measured by using the acetylene inhibition technique under anaerobic condition. Denitrifying activities ranged from 131 to 4330 n mol-N {sub 2} O/h/mg protein for the strains, the activities depended on the strains. 20 refs., 40 figs., 9 tab.

Watanabe, Y.; Kikuchi, K.; Uemoto, H.; Takeda, S.; Kiyono, M.

1989-12-01

48

Newly cultured bacteria with broad diversity isolated from eight-week continuous culture enrichments of cow feces on complex polysaccharides.  

Science.gov (United States)

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 phylogenetically using 16S rRNA gene sequencing. Six phyla were represented: Firmicutes (51.9%), Bacteroidetes (30.9%), Proteobacteria (11.1%), Actinobacteria (3.5%), Synergistetes (1.5%), and Fusobacteria (1.1%). The majority of bacterial isolates had Database Project and thus represent new species and/or genera. Within the Firmicutes isolates, most were classified in the families Lachnospiraceae, Ruminococcaceae, Erysipelotrichaceae, and Clostridiaceae I. The majority of the Bacteroidetes were most closely related to Bacteroides thetaiotaomicron, B. ovatus, and B. xylanisolvens and members of the Porphyromonadaceae family. Many of the Firmicutes and Bacteroidetes isolates were related to species demonstrated to possess enzymes which ferment plant cell wall components; the others were hypothesized to cross-feed these bacteria. The microbial communities that arose in these enrichment cultures had broad bacterial diversity. With over 98% of the isolates not represented as previously cultured, there are new opportunities to study the genomic and metabolic capacities of these members of the complex intestinal microbiota. PMID:24212576

Ziemer, Cherie J

2014-01-01

49

Enrichment and optimization of anaerobic bacterial mixed culture for conversion of syngas to ethanol.  

Science.gov (United States)

The main aim of the present study was to enrich anaerobic mixed bacterial culture capable of producing ethanol from synthesis gas fermentation. Screening of thirteen anaerobic strains together with enrichment protocol helped to develop an efficient mixed culture capable of utilizing syngas for ethanol production. Physiological and operational parameters were optimized for enhanced ethanol production. The optimized value of operational parameters i.e. initial media pH, incubation temperature, initial syngas pressure, and agitation speed were 6.0±0.1, 37°C, 2kgcm(-2) and 100rpm respectively. Under these conditions ethanol and acetic acid production by the selected mixed culture were 1.54gL(-1) and 0.8gL(-1) respectively. Furthermore, up-scaling studies in semi-continuous fermentation mode further enhanced ethanol and acetic acid production up to 2.2gL(-1) and 0.9gL(-1) respectively. Mixed culture TERI SA1 was efficient for ethanol production by syngas fermentation. PMID:25233475

Singla, Ashish; Verma, Dipti; Lal, Banwari; Sarma, Priyangshu M

2014-11-01

50

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

DEFF Research Database (Denmark)

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 culture consisted of a short rod and two bacteria antigenically related to Methanobacterium thermoautotrophicum DELTA-H and Methanosarcina thermophila TM-1.

Angelidaki, Irini; Ahring, Birgitte Kiær

1995-01-01

51

Enrichment and properties of an anaerobic mixed culture reductively dechlorinating 1,2,3-trichlorobenzene to 1,3-dichlorobenzene.  

OpenAIRE

Hexachlorobenzene (HCB), pentachlorobenzene (QCB), all three isomers of tetrachlorobenzene (TeCB), 1,2,3-trichlorobenzene (1,2,3-TCB), and 1,2,4-TCB were reductively dechlorinated by enrichment cultures in the presence of lactate, glucose, ethanol, or isopropanol as the electron donor. The enrichment cultures originated from percolation columns filled with Rhine River sediment in which dechlorination of TCBs and dichlorobenzenes (DCBs) occurred. A stable consortium obtained by transfer on lac...

Holliger, C.; Schraa, G.; Stams, A. J. M.; Zehnder, A. J. B.

1992-01-01

52

Immunochromatographic detection of the group B streptococcus antigen from enrichment cultures.  

Science.gov (United States)

Group B Streptococcus (GBS; Streptococcus agalactiae) is a leading cause of serious neonatal infections. The Centers for Disease Control and Prevention recommends GBS screening for all pregnant women during the 35th to 37th weeks of gestation. Although GBS screening has been performed mainly by the culture-based method, it takes several days to obtain a reliable result. In this study, we developed a rapid immunochromatographic test (ICT) for the detection of GBS-specific surface immunogenic protein in 15 min using an overnight enrichment culture. The ICT was prepared using two anti-Sip monoclonal antibodies. This ICT was able to detect recombinant Sip levels of 0.5 ng/ml, or about 10(6) CFU/ml of GBS cells, in tests with 9 GBS strains of different serotypes. The cross-reactivity test using 26 species of microorganism showed no detectable false-positive result. Reactivity of the ICT with 229 GBS strains showed one false-negative result that was attributable to the production of truncated Sip. Among 260 enrichment cultures of vaginal swabs, 17 produced red to orange pigments in Granada medium, and they were all GBS and Sip positive. Among 219 pigment-negative cultures, 12 were GBS positive and 10 were Sip positive. Two Sip-negative cultures contained GBS cells below the limit of detection by the ICT. Among 207 GBS-negative cultures, only one was Sip positive, which was attributable to GBS cell debris. Thus, the sensitivity and specificity of the ICT appeared to be 93.1% and 99.6%, respectively. The newly developed ICT is readily applicable to clinical use in the detection of GBS. PMID:23825191

Matsui, Hidehito; Kimura, Juri; Higashide, Masato; Takeuchi, Yoshio; Okue, Kuniyuki; Cui, Longzhu; Nakae, Taiji; Sunakawa, Keisuke; Hanaki, Hideaki

2013-09-01

53

Microbial dynamics in anaerobic enrichment cultures degrading di-n-butyl phthalic acid ester  

DEFF Research Database (Denmark)

Although anaerobic biodegradation of di-n-butyl phthalic acid ester (DBP) has been studied over the past decade, only little is known about the microorganisms involved in the biological anaerobic degradation pathways. The aim of this work is to characterize the microbial community dynamics in enrichment cultures degrading phthalic acid esters under methanogenic conditions. A selection pressure was applied by adding DBP at 10 and 200 mg L(-1) in semi-continuous anaerobic reactors. The microbial dynamics were monitored using single strand conformation polymorphism (SSCP). While only limited abiotic losses were observed in the sterile controls (20-22%), substantial DBP biodegradation was found in the enrichment cultures (90-99%). In addition, significant population changes were observed. The dominant bacterial species in the DBP-degrading cultures was affiliated to Soehngenia saccharolytica, a microorganism described previously as an anaerobic benzaldehyde degrader. Within the archaeal community, there was a shift between two different species of the genus Methanosaeta sp., indicating a highly specific impact of DBP or degradation products on archaeal species. RNA-directed probes were designed from SSCP sequences, and FISH observations confirmed the dominance of S. saccharolytica, and indicated floccular microstructures, likely providing favourable conditions for DBP degradation.

Trably, Eric; Batstone, Damien J.

2008-01-01

54

Anaerobic biotransformation of high concentrations of chloroform by an enrichment culture and two bacterial isolates.  

Science.gov (United States)

A fermentative enrichment culture (designated DHM-1) was developed that is capable of cometabolically biotransforming high concentrations of chloroform (CF) to nontoxic end products. Two Pantoea spp. were isolated from DHM-1 that also possess this dechlorination capability. Following acclimation to increasing levels of CF, corn syrup-grown DHM-1 was able to transform over 500 mg/liter CF in the presence of vitamin B(12) (approximately 3% of CF on a molar basis) at a rate as high as 22 mg/liter/day in a mineral salts medium. CO, CO(2), and organic acids were the predominant biodegradation products, suggesting that hydrolytic reactions predominate during CF transformation. DHM-1 was capable of growing on corn syrup in the presence of high concentrations of CF (as may be present near contaminant source zones in groundwater), which makes it a promising culture for bioaugmentation. Strains DHM-1B and DHM-1T transform CF at rates similar to that of the DHM-1 enrichment culture. The ability of these strains to grow in the presence of high concentrations of CF appears to be related to alteration of membrane fluidity or homeoviscous and homeophasic adaptation. PMID:20693443

Shan, Huifeng; Kurtz, Harry D; Mykytczuk, Nadia; Trevors, Jack T; Freedman, David L

2010-10-01

55

Anaerobic Biotransformation of High Concentrations of Chloroform by an Enrichment Culture and Two Bacterial Isolates ? †  

Science.gov (United States)

A fermentative enrichment culture (designated DHM-1) was developed that is capable of cometabolically biotransforming high concentrations of chloroform (CF) to nontoxic end products. Two Pantoea spp. were isolated from DHM-1 that also possess this dechlorination capability. Following acclimation to increasing levels of CF, corn syrup-grown DHM-1 was able to transform over 500 mg/liter CF in the presence of vitamin B12 (approximately 3% of CF on a molar basis) at a rate as high as 22 mg/liter/day in a mineral salts medium. CO, CO2, and organic acids were the predominant biodegradation products, suggesting that hydrolytic reactions predominate during CF transformation. DHM-1 was capable of growing on corn syrup in the presence of high concentrations of CF (as may be present near contaminant source zones in groundwater), which makes it a promising culture for bioaugmentation. Strains DHM-1B and DHM-1T transform CF at rates similar to that of the DHM-1 enrichment culture. The ability of these strains to grow in the presence of high concentrations of CF appears to be related to alteration of membrane fluidity or homeoviscous and homeophasic adaptation. PMID:20693443

Shan, Huifeng; Kurtz, Harry D.; Mykytczuk, Nadia; Trevors, Jack T.; Freedman, David L.

2010-01-01

56

Characterization of ATP release from cultures enriched in cholinergic amacrine-like neurons  

OpenAIRE

Adenosine triphosphate (ATP) has been proposed to play a role as a neurotransmitter in the retina, but not much attention has been given to the regulation of ATP release from retinal neurons. In this work, we investigated the release of ATP from cultures enriched in amacrine-like neurons. Depolarization of the cells with KCl, or activation of alpha-amino-3-hydroxy- 5-methyl-4-isoxazole-propionate (AMPA) receptors, evoked the release of ATP, as determined by the luciferin/luciferase luminescen...

Santos, Paulo F.; Caramelo, Olga L.; Carvalho, Arse?lio P.; Duarte, Carlos B.

1999-01-01

57

An efficient and economical culture approach for the enrichment of purified oligodendrocyte progenitor cells.  

Science.gov (United States)

Oligodendrocyte progenitor cell (OPC) culture has provided a powerful approach to mechanistically investigate the proliferation and differentiation of oligodendroglia. However, existing culture methods (including the traditional shake-off method) have limitations, particularly their low productivities. Therefore, we developed a simplified and highly efficient method to produce a large yield of OPCs with low expense by using specialised modified media, in which B104-conditioned medium (B104-CM) instead of growth factors was used as a mitogenic source for OPC propagation, while a modified OPC isolation-medium was applied to improve the isolation of OPCs. First, we withdrew foetal bovine serum when primary mixed glial cultures were 65-75% confluent and substituted with modified oligodendrocyte growth medium to enrich OPCs. Second, we employed a chemical-based method to isolate and purify OPCs from mixed glial cultures using a modified oligodendrocyte isolation medium. As a result, our approach produced a high yield of purified OPCs, approximately 90-fold higher than that produced via the traditional shake-off method. Importantly, the purified OPCs produced via our modified approach maintained typical capacities of proliferation and differentiation observed in oligodendrocyte lineage cells. Together, our modified method provides a highly efficient approach to OPC culture for oligodendrocyte research. PMID:22687939

Niu, Jianqin; Wang, Lingyun; Liu, Shubao; Li, Chengren; Kong, Jiming; Shen, Hai-Ying; Xiao, Lan

2012-07-30

58

The Learning Effects of an Ecology Enrichment Summer Program on Gifted Students from Mainstream and Diverse Cultural Backgrounds: A Preliminary Study  

Science.gov (United States)

Enrichment is one of the important educational models for gifted students. However, the research on gifted enrichment programs rarely leads to instructional interventions for culturally diverse students. The purposes of this study were: (a) to propose an ecology enrichment summer program for gifted students from mainstream and diverse cultural

Wang, Wen-Ling; Wu, Jiun-Wei; Lin, Yu-Chin

2006-01-01

59

Improved detection of Clostridium difficile in animals by using enrichment culture followed by LightCycler real-time PCR.  

Science.gov (United States)

The performance of our previously published TaqMan real-time PCR (TMrtPCR) for the detection of Clostridium difficile directly from animal faeces was found to be inadequate due to TMrtPCR false negative results. Therefore, we developed a new internally controlled LightCycler real-time PCR (LC rtPCR) capable of detecting variant strains in diarrhoeic and subclinical animals by using two hybridisation probes instead of one hydrolysis probe used in TMrtPCR. While LC rtPCR did not provide better results than TMrtPCR, improved detection of C. difficile in samples with low number of bacteria was introduced, using a pre-enrichment step followed by LC rtPCR. Hence, 40 (100%) rectal swabs were sampled and subjected to direct LC rtPCR, culture without enrichment and enrichment culture; after 24, 48 and 72 h, and seven days of incubation, DNA was extracted and amplified with LC rtPCR. Only one (2.5%) sample was culture positive/LC rtPCR positive without the enrichment step, while 33 (82.5%) samples were culture positive after seven days of enrichment. Only one day of enrichment evidently increases the number of culture positive (15; 37.5%) and LC rtPCR positive (28; 70%) samples. Results of this study demonstrate that one day enrichment culture for C. difficile followed by LC rtPCR assay targeting multiple genes can be applied as accurate and rapid screening test, especially in samples with low number of C. difficile, as no culture positive/LC rtPCR negative samples were observed. PMID:23419821

Avberšek, Jana; Zajc, Urška; Mi?unovi?, Jasna; Ocepek, Matjaž

2013-05-31

60

Rapid detection of Listeria monocytogenes in food using culture enrichment combined with real-time PCR.  

Science.gov (United States)

A rapid method for the detection of Listeria monocytogenes in foods combining culture enrichment and real-time PCR was compared to the ISO 11290-1 standard method. The culture enrichment component of the rapid method is based on the ISO standard and includes 24h incubation in half-Fraser broth, 4h incubation in Fraser broth followed by DNA extraction and real-time PCR detection of the ssrA gene of L. monocytogenes. An internal amplification control, which is co-amplified with the same primers as the L. monocytogenes DNA, was also included in the assay. The method has a limit of detection of 1-5CFU/25g food sample and can be performed in 2 working days compared to up to 7days for the ISO standard. A variety of food samples from retail outlets and food processing plants (n=175) and controls (n=31) were tested using rapid and conventional methods. The rapid method was 99.44% specific, 96.15% sensitive and 99.03% accurate when compared to the standard method. This method has the potential to be used as an alternative to the standard method for food quality assurance providing rapid detection of L. monocytogenes in food. PMID:19028297

O'Grady, Justin; Ruttledge, Margaret; Sedano-Balbás, Sara; Smith, Terry J; Barry, Thomas; Maher, Majella

2009-02-01

61

Properties of dissimilatory nitrate reductase purified from the denitrifier Pseudomonas aeruginosa.  

OpenAIRE

Dissimilatory nitrate reductase was purified to homogeneity from anaerobic cultures of the denitrifying bacterium Pseudomonas aeruginosa. The following procedures were used in the rapid isolation of this unstable enzyme: induction by nitrate in semianaerobic cell suspension, heat-stimulated activation and solubilization from the membrane fraction, and purification by hydrophobic interaction chromatography. The molecular weight of the purified enzyme was estimated by nondenaturing polyacrylami...

Carlson, C. A.; Ferguson, L. P.; Ingraham, J. L.

1982-01-01

62

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

OpenAIRE

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...

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

2014-01-01

63

Bacterial oxidation of dibromomethane and methyl bromide in natural waters and enrichment cultures  

Science.gov (United States)

Bacterial oxidation of 14CH2Br2 and 14CH3Br was measured in freshwater, estuarine, seawater, and hypersaline-alkaline samples. In general, bacteria from the various sites oxidized similar amounts of 14CH2Br2 and comparatively less 14CH3Br. Bacterial oxidation of 14CH3Br was rapid in freshwater samples compared to bacterial oxidation of 14CH3Br in more saline waters. Freshwater was also the only site in which methyl fluoride-sensitive bacteria (e.g., methanotrophs or nitrifiers) governed brominated methane oxidation. Half-life calculations indicated that bacterial oxidation of CH2Br2 was potentially significant in all of the waters tested. In contrast, only in freshwater was bacterial oxidation of CH3Br as fast as chemical removal. The values calculated for more saline sites suggested that bacterial oxidation of CH3Br was relatively slow compared to chemical and physical loss mechanisms. However, enrichment cultures demonstrated that bacteria in seawater can rapidly oxidize brominated methanes. Two distinct cultures of nonmethanotrophic methylotrophs were recovered; one of these cultures was able to utilize CH2Br2 as a sole carbon source, and the other was able to utilize CH3Br as a sole carbon source.

Goodwin, K.D.; Schaefer, J.K.; Oremland, R.S.

1998-01-01

64

Antibacterial Activity of Gamma-irradiated Chitosan Against Denitrifying Bacteria  

Science.gov (United States)

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.

Vilcáez, Javier; Watanabe, Tomohide

2010-11-01

65

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

Science.gov (United States)

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 ?mol 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. PMID:23892419

Cheng, Liang; Cord-Ruwisch, Ralf

2013-10-01

66

Phylogenetic analysis of anaerobic psychrophilic enrichment cultures obtained from a greenland glacier ice core  

Science.gov (United States)

The examination of microorganisms in glacial ice cores allows the phylogenetic relationships of organisms frozen for thousands of years to be compared with those of current isolates. We developed a method for aseptically sampling a sediment-containing portion of a Greenland ice core that had remained at -9 degrees C for over 100,000 years. Epifluorescence microscopy and flow cytometry results showed that the ice sample contained over 6 x 10(7) cells/ml. Anaerobic enrichment cultures inoculated with melted ice were grown and maintained at -2 degrees C. Genomic DNA extracted from these enrichments was used for the PCR amplification of 16S rRNA genes with bacterial and archaeal primers and the preparation of clone libraries. Approximately 60 bacterial inserts were screened by restriction endonuclease analysis and grouped into 27 unique restriction fragment length polymorphism types, and 24 representative sequences were compared phylogenetically. Diverse sequences representing major phylogenetic groups including alpha, beta, and gamma Proteobacteria as well as relatives of the Thermus, Bacteroides, Eubacterium, and Clostridium groups were found. Sixteen clone sequences were closely related to those from known organisms, with four possibly representing new species. Seven sequences may reflect new genera and were most closely related to sequences obtained only by PCR amplification. One sequence was over 12% distant from its closest relative and may represent a novel order or family. These results show that phylogenetically diverse microorganisms have remained viable within the Greenland ice core for at least 100,000 years.

Sheridan, Peter P.; Miteva, Vanya I.; Brenchley, Jean E.

2003-01-01

67

Cometabolic degradation of MTBE using methane-propane- and butane-utilizing enrichment cultures and rhodococcus sp. BU3  

Energy Technology Data Exchange (ETDEWEB)

The fuel oxygenated methyl tert-butyl ether (MTBE) is used worldwide to replace leaded organic compounds. Although MTBE is persistent in the environment, chiefly due to its low biodegradability, some microbial cultures are able to mineralize it. This paper reports on the cometabolic degradation of MTBE by methane-, propane- and butane-utilizing enrichment cultures and the pure Rhodococcus sp. BU3 culture isolated from natural habitats. Three methane-, three propane- and four butane-utilizing cultures, which degrade MTBE cometabolically, were enriched. In experiments with resting cells at 20 C, enrichment cultures grown on methane degraded MTBE at a maximum rate of 1.0 mg MTBE/(g biomass . h). Propane- and butane-utilizing enrichment cultures degraded MTBE and the intermediate tert-butyl alcohol (TBA) cometabolically at temperatures of 20 C at maximum rates of 7.2 mg MTBE/(g biomass . h) and 5.2 mg MTBE/(g biomass . h), respectively. Propane-utilizing cultures were also able to degrade MTBE and TBA consecutively after growth on 1-propanol. However, the MTBE degradation rate after growth on 1-propanol was lower than on propane. The isolated pure culture BU3 specified as Rhodococcus sp. degraded MTBE at maximum rates of 5.4 mg MTBE/(g biomass . h) when grown on propane and 2.3 mg MTBE/(g biomass . h) when grown on 1-propanol, respectively. In column systems with recirculation, it is shown that Rhodococcus sp. BU3 degraded 95 mg/L MTBE over a time period of 6 days. The degradation activity of the immobilized bacteria could be regenerated by the addition of growth substrates (propanol or propane). The results of these experiments provide a promising basis for their implementation in an enhanced natural attenuation approach. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Haase, K.; Wendlandt, K.D.; Graeber, A.; Stottmeister, U. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany)

2006-10-15

68

Enrichment and characterization of MTBE-degrading cultures under iron and sulfate reducing conditions  

Energy Technology Data Exchange (ETDEWEB)

Methyl tert-butyl ether (MTBE) is widely used as an additive to gasoline. It has been exposed to the environment as a result of releases from underground storage tanks and pipelines. MTBE has been banned or limited in many areas of North America because of its high aqueous solubility and slow biodegradation rate. The aim of this study was to obtain highly enriched consortia capable of the anaerobic biodegradation of MTBE. Amplified 16S rDNA restriction-digest analysis (ARDRA) was used to identify the sequencing of unique 16S rRNA genes. The study examined sulfate- and iron-reducing conditions as electron acceptors in groundwater. The aqueous cultures were inoculated in 3 different growth media to examine the effect of biodegradation. Between 5 to 8 members were identified in 3 consortia. A clone was detected in cultures containing iron. Results indicated that the buildup of intermediates and the presence of sulfides inhibited biodegradation. The results may provide biomarkers to support current anaerobic MTBE biodegradation field studies. 80 refs., 1 tab., 3 figs.

Raynal, M. [Univ. Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ingenieria; Crimi, B. [Delft Univ. of Technology (Netherlands). Dept. of Biotechnology; Pruden, A. [Virginia Tech, Blacksburg, VA (United States). Dept. of Civil and Environmental Engineering

2010-04-15

69

Cellulose hydrolysis by a methanogenic culture enriched from landfill waste in a semi-continuous reactor.  

Science.gov (United States)

This study investigates the hydrolysis of cellulose by a mixed culture enriched from landfill waste in a continuous reactor operated under prolonged residence times to accommodate methanogenic conditions. Chemostat studies of hydrolysis under balance methanogenic conditions are rarely reported, despite the importance of hydrolysis under these conditions in waste management and renewable energy industries. Continuous digestion was studied in a 1.25l digester, fed with a 1% (w/v) slurry of 50mum cellulose in sterilized leachate drawn from a 220l digester operated on a feedstock of mixed municipal solid waste. Unsterilized leachate was used as the inoculum. Stable and rapid hydrolytic conditions were established at residence time of 2.5, 3.5 and 5d with a 1st order hydrolysis rate 0.45+/-0.07d(-1) and high methane yields ranging from 57% to 62% of solubilised cellulose on a COD basis. Biomass yields were between 32% and 35% of solubilised cellulose on a COD basis, over three times that observed with fermentative cultures. This is attributed to the diversity of the microbial population which fully converted solubilised COD to methane, as evident by VFA yields of less than 8% on a COD basis. PMID:18929482

Song, Hyohak; Clarke, William P

2009-02-01

70

High yield derivation of enriched glutamatergic neurons from suspension-cultured mouse ESCs for neurotoxicology research  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Recently, there has been a strong emphasis on identifying an in vitro model for neurotoxicity research that combines the biological relevance of primary neurons with the scalability, reproducibility and genetic tractability of continuous cell lines. Derived neurons should be homotypic, exhibit neuron-specific gene expression and morphology, form functioning synapses and consistently respond to neurotoxins in a fashion indistinguishable from primary neurons. However, efficient methods to produce neuronal populations that are suitable alternatives to primary neurons have not been available. Methods With the objective of developing a more facile, robust and efficient method to generate enriched glutamatergic neuronal cultures, we evaluated the neurogenic capacity of three mouse embryonic stem cell (ESC lines (R1, C57BL/6 and D3 adapted to feeder-independent suspension culture. Neurogenesis and neuronal maturation were characterized as a function of time in culture using immunological, genomic, morphological and functional metrics. The functional responses of ESNs to neurotropic toxins with distinctly different targets and mechanisms of toxicity, such as glutamate, ?-latrotoxin (LTX, and botulinum neurotoxin (BoNT, were also evaluated. Results Suspension-adapted ESCs expressed markers of pluripotency through at least 30 passages, and differentiation produced 97×106 neural progenitor cells (NPCs per 10-cm dish. Greater than 99% of embryonic stem cell-derived neurons (ESNs expressed neuron-specific markers by 96 h after plating and rapidly developed complex axodendritic arbors and appropriate compartmentalization of neurotypic proteins. Expression profiling demonstrated the presence of transcripts necessary for neuronal function and confirmed that ESN populations were predominantly glutamatergic. Furthermore, ESNs were functionally receptive to all toxins with sensitivities and responses consistent with primary neurons. Conclusions These findings demonstrate a cost-effective, scalable and flexible method to produce a highly enriched glutamatergic neuron population. The functional characterization of pathophysiological responses to neurotropic toxins and the compatibility with multi-well plating formats were used to demonstrate the suitability of ESNs as a discovery platform for molecular mechanisms of action, moderate-throughput analytical approaches and diagnostic screening. Furthermore, for the first time we demonstrate a cell-based model that is sensitive to all seven BoNT serotypes with EC50 values comparable to those reported in primary neuron populations. These data providing compelling evidence that ESNs offer a neuromimetic platform suitable for the evaluation of molecular mechanisms of neurotoxicity.

Hubbard Kyle S

2012-10-01

71

Degradation of polycyclic aromatic hydrocarbons by microbial consortia enriched from three soils using two different culture media.  

Science.gov (United States)

A consortium composed of many different bacterial species is required to efficiently degrade polycyclic aromatic hydrocarbons (PAH) in oil-contaminated soil. We obtained six PAH-degrading microbial consortia from three oil-contaminated soils using two different isolation culture media. Denaturing gradient gel electrophoresis (DGGE) and sequence analyses of amplified 16s rRNA genes confirmed the bacterial community was greatly affected by both the culture medium and the soil from which the consortia were enriched. Three bacterial consortia enriched using malt yeast extract (MYE) medium showed higher degradation rates of PAHs than consortia enriched using Luria broth (LB) medium. Consortia obtained from a soil and then added back to that same soil was more effective in degrading PAHs than adding, to the same soil, consortia isolated from other, unrelated soils. This suggests that inoculum used for bioremediation should be from the same, or very similar nearby soils, as the soil that is actually being bioremediated. PMID:23570783

Wu, Manli; Chen, Liming; Tian, Yongqiang; Ding, Yi; Dick, Warren A

2013-07-01

72

Chronic impact of tetracycline on nitrification kinetics and the activity of enriched nitrifying microbial culture.  

Science.gov (United States)

This study evaluated the chronic impact of tetracycline on biomass with enriched nitrifying community sustained in a lab-scale activated sludge system. For this purpose, a fill and draw reactor fed with 100 mg COD/L of peptone mixture and 50 mg N/L of ammonia was sustained at a sludge age of 15 days. At steady-state, the reactor operation was continued with a daily tetracycline dosing of 50 mg/L for more than 40 days, with periodic monitoring of the microbial composition, the nitrifying bacteria abundance, as well as the amoA and 16S rRNA gene activity, using molecular techniques. Changes in the kinetics of nitrification were quantified by modelling concentration profiles of major nitrogen fractions and oxygen uptake rate profiles derived from parallel batch experiments. Activated sludge modeling results indicated inhibitory impact of tetracycline on the growth of nitrifiers with a significant increase of the half saturation coefficients in corresponding rate equations. Tetracycline also inactivated biomass components of the enriched culture at a gradually increasing rate with time of exposure, leading to total collapse of nitrification. Molecular analyses revealed significant changes in the composition of the microbial community throughout the observation period. They also showed that continuous exposure to tetracycline inflicted significant reduction in amoA mRNA and 16S rRNA levels directly affecting nitrification. The chronic impact was much more pronounced on the ammonia oxidizing bacteria (AOB) community. These observations explained the basis of numerical changes identified in the growth kinetics of nitrifiers under stress conditions. PMID:25616640

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

2015-04-01

73

Selective enrichment media bias the types of salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths  

Science.gov (United States)

For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the organism the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown...

74

Effects of base-pretreatment on continuous enriched culture for hydrogen production from food waste  

Energy Technology Data Exchange (ETDEWEB)

This study aimed to achieve a reliable start-up method for continuous enriched culture for hydrogen production from food waste. When ground and diluted food waste (volatile solids (VS) 4.4 {+-} 0.2% containing 27 g carbohydrate-chemical oxygen demand/L) was fed, H{sub 2} production decreased below 7.1 mL H{sub 2}/g VS (0.10 mol H{sub 2}/mol hexose{sub added}) within 20 days, because the substrate was consumed via non-H{sub 2}-producing acidogenesis. To suppress the unintended microbial reactions, three methods were examined: lowering H{sub 2} content by continuous CO{sub 2} sparging, acid-pretreatment of food waste at pH 2.0 for 1 day, and base-pretreatment of food waste at pH 12.5 for 1 day. The base-pretreatment reduced indigenous anaerobic bacteria in food waste by 4.9 log and enabled a stable long-term operation over 90 days with the H{sub 2} yields of 62.6 mL H{sub 2}/g VS (0.87 mol H{sub 2}/mol hexose{sub added}). All bacterial species were affiliated with H{sub 2}-producing Clostridium spp. at the cases. Base dosage was increased by 11% compared to the un-pretreated condition. (author)

Kim, Sang-Hyoun [Department of Civil, Construction, and Environmental Engineering, Iowa State University, 394 Town Engineering Building, Ames, IA 50011 (United States); Shin, Hang-Sik [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea)

2008-10-15

75

Isolation of Methylophaga spp. from marine dimethylsulfide-degrading enrichment cultures and identification of polypeptides induced during growth on dimethylsulfide.  

Science.gov (United States)

Dimethylsulfide (DMS)-degrading enrichment cultures were established from samples of coastal seawater, nonaxenic Emiliania huxleyi cultures, and mixed marine methyl halide-degrading enrichment cultures. Bacterial populations from a broad phylogenetic range were identified in the mixed DMS-degrading enrichment cultures by denaturing gradient gel electrophoresis (DGGE). Sequences of dominant DGGE bands were similar to those of members of the genera Methylophaga and Alcanivorax. Several closely related Methylophaga strains were obtained that were able to grow on DMS as the carbon and energy source. Roseobacter-related populations were detected in some of the enrichment cultures; however, none of the Roseobacter group isolates that were tested were able to grow on DMS. Oxidation of DMS by Methylophaga sp. strain DMS010 was not affected by addition of the inhibitor chloroform or methyl tert-butyl ether, suggesting that DMS metabolism may occur by a route different from those described for Thiobacillus species and other unidentified marine isolates. Addition of DMS and methanethiol to whole-cell suspensions of strain DMS010 induced oxygen uptake when strain DMS010 was grown on DMS but not in cells grown on methanol. The apparent K(m)s of strain DMS010 for DMS and for methanethiol were 2.1 and 4.6 microM, respectively, when grown on DMS. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the biomass of strain DMS010 and analysis of peptide bands by mass spectrometry techniques and N-terminal sequencing provided the first insight into the identity of polypeptides induced during growth on DMS. These included XoxF, a homolog of the large subunit of methanol dehydrogenase for which a biological role has not been identified previously. PMID:17322322

Schäfer, Hendrik

2007-04-01

76

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

DEFF Research Database (Denmark)

In situ detection of denitrifying bacteria by mRNA-targeted nucleic acid probes and catalyzed reporter deposition   Michael V.W. Kofoed, Peter Stief, Morten Poulsen, and Andreas Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Denmark Denitrification, the sequential reduction of nitrate to dinitrogen gas, is essential for the removal of fixed nitrogen from natural and engineered ecosystems. However, community structure and activity dynamics of denitrifying bacteria in most systems are poorly understood, partially due to difficulties in identifying and quantifying (active) denitrifiers. The goal of this study was therefore to develop a protocol for the in situ detection of denitrifying bacterial cells by targeting the mRNA of denitrification genes, hereby linking denitrification activity directly to the single-cell level. Target genes were narG (encoding nitrate 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 and catalyzed fluorescent reporter deposition (CARD-FISH). The general feasibility of the approach was first tested with pure cultures of Pseudomonas stutzeri and various denitrifying and nitrate-reducing isolates. Detailed studies of probe specificity and hybridization conditions using Clone-FISH of narG and nosZ libraries prepared from freshwater sediment revealed a sequence similarity threshold of about 80% for detectable hybridization with polynucleotide probes. Consequently, polynucleotide probes need to be designed based on habitat-specific sequence information. In contrast, oligonucleotide probes can be designed to target a broader range of denitrifying bacteria; however, they require two-pass CARD-FISH, which may result in (too) high background fluorescence. In a first application example, habitat-specific polynucleotide probes were used to quantify bacteria expressing narG and nosZ in freshwater sediments and the guts of benthic invertebrates.    

Kofoed, Michael Vedel; Stief, Peter

77

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

Directory of Open Access Journals (Sweden)

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.

Anestis Koutsoudis

2014-01-01

78

Functional consortium for denitrifying sulfide removal process  

Energy Technology Data Exchange (ETDEWEB)

Denitrifying sulfide removal (DSR) process simultaneously converts sulfide, nitrate, and chemical oxygen demand from industrial wastewaters to elemental sulfur, nitrogen gas, and carbon dioxide, respectively. This investigation utilizes a dilution-to-extinction approach at 10{sup -2} to 10{sup -6} dilutions to elucidate the correlation between the composition of the microbial community and the DSR performance. In the original suspension and in 10{sup -2} dilution, the strains Stenotrophomonas sp., Thauera sp., and Azoarcus sp. are the heterotrophic denitrifiers and the strains Paracoccus sp. and Pseudomonas sp. are the sulfide-oxidizing denitrifers. The 10{sup -4} dilution is identified as the functional consortium for the present DSR system, which comprises two functional strains, Stenotrophomonas sp. strain Paracoccus sp. At 10{sup -6} dilution, all DSR performance was lost. The functions of the constituent cells in the DSR granules were discussed based on data obtained using the dilution-to-extinction approach. (orig.)

Chen, Chuan [Harbin Inst. of Technology (CN). State Key Lab. of Water Resource and Environment (SKLWRE); Harbin Inst. of Technology (China). School of Municipal and Environmental Engineering; Ren, Nanqi; Wang, Aijie [Harbin Inst. of Technology (CN). State Key Lab. of Water Resource and Environment (SKLWRE); Liu, Lihong [Harbin Inst. of Technology (China). School of Municipal and Environmental Engineering; Lee, Duu-Jong [Harbin Inst. of Technology (CN). State Key Lab. of Water Resource and Environment (SKLWRE); National Taiwan Univ., Taipei (China). Dept. of Chemical Engineering

2010-03-15

79

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

OpenAIRE

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 microorganisms. This study provides information on the occurrence of atrazine mineralizing bacterial strains with faster metabolizing ability. The enrichment cultures were tested for the biodegradation of atrazine by high-performance liquid chromatography (HPLC) and mass spectrometry. ...

Solomon, Robinson David Jebakumar; Kumar, Amit; Satheeja Santhi, Velayudhan

2013-01-01

80

PCR amplification of Bartonella koehlerae from human blood and enrichment blood cultures  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Cats appear to be the primary reservoir host for Bartonella koehlerae, an alpha Proteobacteria that is most likely transmitted among cat populations by fleas (Ctenocephalides felis. Bartonella koehlerae has caused endocarditis in a dog and in one human patient from Israel, but other clinically relevant reports involving this bacterium are lacking. Despite publication of numerous, worldwide epidemiological studies designed to determine the prevalence of Bartonella spp. bacteremia in cats, B. koehlerae has never been isolated using conventional blood agar plates. To date, successful isolation of B. koehlerae from cats and from the one human endocarditis patient has consistently required the use of chocolate agar plates. Results In this study, Bartonella koehlerae bacteremia was documented in eight immunocompetent patients by PCR amplification and DNA sequencing, either prior to or after enrichment blood culture using Bartonella alpha Proteobacteria growth medium. Presenting symptoms most often included fatigue, insomnia, joint pain, headache, memory loss, and muscle pain. Four patients were also infected with Bartonella vinsonii subsp. berkhoffii genotype II. After molecular documentation of B. koehlerae infection in these patients, a serological test was developed and serum samples were tested retrospectively. Bartonella koehlerae antibodies were not detected (titers B. koehlerae antibody titers of 1:64 or greater. Conclusions Although biased by a study population consisting of individuals with extensive arthropod and animal exposure, the results of this study suggest that B. koehlerae bacteremia is more common in immunocompetent people than has been previously suspected. Future studies should more thoroughly define modes of transmission and risk factors for acquiring infection with B. koehlerae. In addition, studies are needed to determine if B. koehlerae is a cause or cofactor in the development of arthritis, peripheral neuropathies or tachyarrhythmias in patients.

Breitschwerdt Edward B

2010-08-01

81

Degradation of polycyclic aromatic hydrocarbons by microbial consortia enriched from three soils using two different culture media  

International Nuclear Information System (INIS)

A consortium composed of many different bacterial species is required to efficiently degrade polycyclic aromatic hydrocarbons (PAH) in oil-contaminated soil. We obtained six PAH-degrading microbial consortia from three oil-contaminated soils using two different isolation culture media. Denaturing gradient gel electrophoresis (DGGE) and sequence analyses of amplified 16s rRNA genes confirmed the bacterial community was greatly affected by both the culture medium and the soil from which the consortia were enriched. Three bacterial consortia enriched using malt yeast extract (MYE) medium showed higher degradation rates of PAHs than consortia enriched using Luria broth (LB) medium. Consortia obtained from a soil and then added back to that same soil was more effective in degrading PAHs than adding, to the same soil, consortia isolated from other, unrelated soils. This suggests that inoculum used for bioremediation should be from the same, or very similar nearby soils, as the soil that is actually being bioremediated. -- Highlights: •Six PAH-degrading microbial consortia were isolated from three oil-contaminated soils. •The bacterial community by 16s rRNA genes was affected by culture media and source soil. •Inoculum should be from the same or similar soil as the soil being bioremediated. -- Bioremediation of oil-contaminated soils was most effective when using inoculum of microbial consortia from the same or similar soil as the soil being bioremediated

82

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

DEFF Research Database (Denmark)

The aim was to investigate the effect of addition of Novobiocin to the non-selective buffered peptone water (BPW) for pre-enrichment of Salmonella in connection with plating on modified semisolid Rappaport-Vassiliadis (MSRV). In a semi-quantitative study, the level of Salmonella following pre-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-enrichment broth with BPW made semi-selective by addition of Novobiocin. The semi-quantitative assessment of the Salmonella level showed that addition of Novobiocin in the pre-enrichment step on average increased the level of Salmonella 1.2 log dilution steps. When growth was scored at five levels, 90 samples opposed to 50 yielded a strong positive reading (+++) when Novobiocin was applied. Growth was on average0.3 scores higher when pre-enriched with Novobiocin. The difference in growth score medians of the two methods was highly significant (Sign test; p <0.001). Despite the increased sensitivity, 13 culture-positive samples were missed when using the Novobiocin-containing BPW. In conclusion, a simple addition of Novobiocin in the BPW pre-enrichment step of fecal samples may facilitate reading and thereby detection of Salmonella on MSRV. The increase of Salmonella in the semi-quantitative study may be caused by a reduction in the number of competitive microorganisms.

Jensen, Annette Nygaard; SØrensen, Gitte

2003-01-01

83

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)

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)

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

84

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

OpenAIRE

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...

Bayu Agung Prahardika; Catur Retnaningdyah; Suharjono

2013-01-01

85

Triple oxygen isotope analysis of nitrate using the denitrifier method and thermal decomposition of N?O  

OpenAIRE

Interaction with ozone transfers its anomalous (non-mass-dependent) ¹?O enrichment to atmospheric nitrogen oxides and nitrate. The 17O anomaly (?17O) in nitrate can be used to identify atmospheric nitrate inputs into terrestrial and aquatic environments as well as to study the role of ozone in the atmosphere's reactive nitrogen cycle. We report here on an online method for analysis of the 17O anomaly, using a strain of denitrifiers to convert nitrate to N?O, which decomposes quantitativ...

Kaiser, J.; Hastings, M. G.; Houlton, B. Z.; Ro?ckmann, T.; Sigman, D. M.

2007-01-01

86

Site-specific variability in BTEX biodegradation under denitrifying conditions  

International Nuclear Information System (INIS)

Laboratory microcosm experiments were conducted to evaluate the feasibility of benzene, toluene, ethylbenzene, m-xylene, and o-xylene (BTEX) biodegradation under denitrifying conditions. Nine different sources of inocula, including contaminated and uncontaminated soil cores from four different sites and activated sludge, were used to establish microcosms. BTEX was not degraded under denitrifying conditions in microcosms inoculated with aquifer material from Rocky Point and Traverse City. However, rapid depletion of glucose under denitrifying conditions was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing aquifer material from Fort Bragg and Sleeping Bear Dunes and sewage sludge. Benzene was recalcitrant in all microcosms tested. The degradation of o-xylene ceased after toluene, ethylbenzene, and m-xylene were depleted in the Fort Bragg and sludge microcosms, but o-xylene continued to degrade in microcosms with contaminated Sleeping Bear Dunes soil. The most probable number (MPN) of denitrifiers in these nine different inocula were measured using a microtiter technique. There was no correlation between the MPN of denitrifiers and the TEX degradation rate under denitrifying conditions. Experimental results indicate that the degradation sequence and TEX degradation rate under denitrifying conditions may differ among siteitrifying conditions may differ among sites. Results also indicate that denitrification alone may not be a suitable bioremediation technology for gasoline-contaminated aquifers because of the inability of denitrifiers to degrade benzene

87

Microbial and metabolic characterization of a denitrifying phosphorus-uptake/side stream phosphorus removal system for treating domestic sewage.  

Science.gov (United States)

In this study, an advanced wastewater treatment process, the denitrifying phosphorus/side stream phosphorus removal system (DPR-Phostrip), was developed for the purpose of enhancing denitrifying phosphorus removal. The enrichment of denitrifying phosphorus-accumulating organisms (DPAOs) and the microbial community structure of DPR-Phostrip were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and the metabolic activity of seed sludge and activated sludge collected after 55 days of operation were evaluated by Biolog™ analysis. This experimental study of DPR-Phostrip operation showed that nutrients were removed effectively, and denitrifying phosphorus removal was observed during the pre-anoxic period. PCR-DGGE analysis indicated that DPR-Phostrip supported DPAO growth while inhibiting PAOs and GAOs. The major dominant species in DPR-Phostrip were Bacteroidetes bacterium, Saprospiraceae bacterium, and Chloroflexi bacterium. Moreover, the functional diversity indices calculated on the basis of Biolog analysis indicated that DPR-Phostrip had almost no effect on microbial community diversity but was associated with a shift in the dominant species, which confirms the results of the PCR-DGGE analysis. The results for average well color development, calculated via Biolog analysis, showed that DPR-Phostrip had a little impact on the metabolic activity of sludge. Further principal component analysis suggested that the ability to utilize low-molecular-weight organic compounds was reduced in DPR-Phostrip. PMID:25073616

Jin, Zhan; Ji, Fang-Ying; Xu, Xuan; Xu, Xiao-Yi; Chen, Qing-Kong; Li, Qi

2014-11-01

88

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)

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.

Bayu Agung Prahardika

2013-04-01

89

A New Protocol to Detect Multiple Foodborne Pathogens with PCR Dipstick DNA Chromatography after a Six-Hour Enrichment Culture in a Broad-Range Food Pathogen Enrichment Broth  

OpenAIRE

A quick foodborne pathogen screening method after six-hour enrichment culture with a broad-range food pathogen enrichment broth is described. Pathogenic factors of Salmonella enterica, Shigella spp., enteroinvasive Escherichia coli, and enterohemorrhagic E. coli are amplified with a cocktail primer and rapid polymerase chain reaction (PCR), which finishes amplification in 30?min. The PCR amplicon was differentiated with a dipstick DNA chromatography assay in 5–10?min. Starting from a fo...

Masahiro Hayashi; Tatsuya Natori; Sayoko Kubota-Hayashi; Machiko Miyata; Kiyofumi Ohkusu; Keiko Kawamoto; Hisao Kurazono; Souichi Makino; Takayuki Ezaki

2013-01-01

90

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

Science.gov (United States)

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. PMID:25108138

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

91

Fermentative degradation of acetone by an enrichment culture in membrane-separated culture devices and in cell suspensions  

OpenAIRE

A mixed culture, WoAct, growing on acetone, consisted of two dominant morphotypes: a rod-shaped acetone-fermenting bacterium producing acetate, and an acetate-utilizing Methanosaeta species. Dense cell suspensions, largely free of the aceticlastic methanogen and supplemented with bromoethanesulfonate, were able to degrade acetone and grow in small volumes in membrane-separated culture devices in which the acetate produced could diffuse into a large volume of medium. Acetone degradation and gr...

Platen, Harald; Janssen, Peter H.; Schink, Bernhard

1994-01-01

92

Bacterial and Archaeal direct counts: a faster method of enumeration, for enrichment cultures and aqueous environmental samples.  

Science.gov (United States)

A new presence/absence method has been developed to count fluorochrome-stained bacterial and archaeal cells on membrane filters using epifluorescence microscopy. This approach was derived from the random distribution of cells on membranes that allowed the use of the Poisson distribution to estimate total cell densities. Comparison with the standard Acridine Orange Direct Count (AODC) technique shows no significant difference in the estimation of total cell populations, or any reduction in the precision of these estimations. The new method offers advantages over the standard AODC in considerably faster counting, as there is no need to discriminate between every potential cell visible on a field and fluorescent detritus, it is only necessary to confirm the presence of one cell. Additionally, the new method requires less skill, so has less reliance on expert counters, and that should reduce inter-counter variability. Although this work used the fluorochrome Acridine Orange, clearly the results are applicable to any fluorochrome used to count bacterial and archaeal cells. This method was developed using enrichment cultures for use with enrichment cultures and aqueous environmental samples where interfering detrital and mineral particles are minimal e.g., freshwater/seawater, therefore, it is not suitable for estimating total cells from sediment samples. This method has the potential for use in any situation where counts of randomly distributed items are made using a grid or quadrat system. PMID:24361191

Cragg, Barry A; Parkes, R John

2014-03-01

93

Evaluation of liquid and solid culture media for the recovery and enrichment of Burkholderia cenocepacia from distilled water.  

Science.gov (United States)

Burkholderia cepacia complex (BCC) presence has been the cause of recalls of both sterile and non-sterile pharmaceutical products since these opportunistic pathogens have been implicated to cause infections to susceptible individuals. BCC are ubiquitous in nature, but in pharmaceutical settings the most common source is contaminated water systems. Some strains of BCC, previously described as Pseudomonas cepacia, were not readily detected by standard culture methods. We have explored different strategies to recover and enrich Burkholderia cenocepacia previously cultured in distilled water for 40 days. Enrichment media of varied nutrient concentrations and composition were used, including modified Tryptic Soy Agar or Broth (TSA or TSB), Reasoner's 2nd Agar or Broth (R2A or R2AB), Brain-Heart Infusion Broth (BHIB), Mueller-Hinton Broth (MHB), and Ashdown's (ASH) medium. Of the various broth media tested, cell growth was significantly greater in TSB and R2AB than in BHIB, MHB, or ASH broth. TSB and R2AB were also compared for their recovery efficiency. Generally, there was no significant difference between the numbers of B. cenocepacia grown on 15 differently modified TSA and five modified R2A solid media. Overall, however, diluted TSA and TSB media, and R2A and R2AB showed better recovery efficiency than TSA and TSB for inocula containing small numbers of cells. All strains persisted in distilled water for 40 days. Broth media were more effective than solid media for recovery of B. cenocepacia from distilled water. These results may assist in improving detection assays with recovery and enrichment strategies to maximize recovery of these fastidious organisms. PMID:24756630

Ahn, Youngbeom; Kim, Jeong Myeong; Ahn, Hyeri; Lee, Yong-Jin; LiPuma, John J; Hussong, David; Cerniglia, Carl E

2014-07-01

94

Rapid and Specific Detection of Salmonella spp. in Animal Feed Samples by PCR after Culture Enrichment  

OpenAIRE

A PCR procedure has been developed for routine analysis of viable Salmonella spp. in feed samples. The objective was to develop a simple PCR-compatible enrichment procedure to enable DNA amplification without any sample pretreatment such as DNA extraction or cell lysis. PCR inhibition by 14 different feed samples and natural background flora was circumvented by the use of the DNA polymerase Tth. This DNA polymerase was found to exhibit a high level of resistance to PCR inhibitors present in t...

Lo?fstro?m, Charlotta; Knutsson, Rickard; Axelsson, Ce; Ra?dstro?m, Peter

2004-01-01

95

A new protocol to detect multiple foodborne pathogens with PCR dipstick DNA chromatography after a six-hour enrichment culture in a broad-range food pathogen enrichment broth.  

Science.gov (United States)

A quick foodborne pathogen screening method after six-hour enrichment culture with a broad-range food pathogen enrichment broth is described. Pathogenic factors of Salmonella enterica, Shigella spp., enteroinvasive Escherichia coli, and enterohemorrhagic E. coli are amplified with a cocktail primer and rapid polymerase chain reaction (PCR), which finishes amplification in 30?min. The PCR amplicon was differentiated with a dipstick DNA chromatography assay in 5-10?min. Starting from a four- to six-hour enrichment culture, this assay was finished within 45?min. Detection sensitivity of this protocol was less than 2.5?CFU/25?g for S. enterica and 3.3?CFU/25?g for enterohemorrhagic E. coli in spiked ground meat experiments. PMID:24364031

Hayashi, Masahiro; Natori, Tatsuya; Kubota-Hayashi, Sayoko; Miyata, Machiko; Ohkusu, Kiyofumi; Kawamoto, Keiko; Kurazono, Hisao; Makino, Souichi; Ezaki, Takayuki

2013-01-01

96

eXTRA: A Culturally Enriched Malay Text to Speech System  

OpenAIRE

This paper concerns the incorporation of naturalness into Malay Text-to-Speech (TTS) systems through the addition of a culturally-localized affective component. Previous studies on emotion theories were examined to draw up assumptions about emotions. These studies also include the findings from observations by anthropologists and researchers on culturalspecific emotions, particularly, the Malay culture. These findings were used to elicit the requirements for modeling affect in the TTS that co...

Lutfi, Syaheerah L.; Montero Marti?nez, Juan Manuel; Ainon, Raja Noor; Mohd Don, Zuraidah

2008-01-01

97

DNA-based and culture-based characterization of a hydrocarbon-degrading consortium enriched from Arctic soil  

Energy Technology Data Exchange (ETDEWEB)

Oil spills are fairly common in polar tundra regions, including remote locations, and are a threat to the relatively fragile ecosystem. Remediation must be done economically and with minimum additional damage. Bioremediation is considered to be the appropriate technology, although its application in polar tundra regions is not well documented. Most studies of hydrocarbon remediation in polar regions have concerned marine oil spills, while a few studies have demonstrated on-site polar tundra soil remediation. A few of these demonstrated the presence of psychrotolerant hydrocarbon-degrading bacteria in polar tundra soils. Because fuels are complex mixtures of hydrocarbons, microbial consortia rather than pure cultures may be the most effective agents in degrading fuels. Despite their potential advantages for bioaugmentation applications, consortia are difficult to characterize and monitor. Molecular methods based on DNA analysis partially address these difficulties. One such approach is to randomly clone rRNA gene (rDNA) fragments and to sequence as a set of clones. The relative abundance of individual sequences in the clone library is related to the relative abundance of the corresponding organism in the community. In this study a psychrotolerant, fuel-degrading consortium was enriched with Arctic tundra soil. The enrichment substrate for the consortium was Jet A-1 fuel, which is very similar to Arctic diesel fuel, a common contaminant in the region. The objectives of the study were to (1) characterize thr consortium by DNA- and culture-based methods, (2) develop quantitative polymerase chain reaction assays for populations of predominant consortium members, and (3) determine the dynamics of those populations during incubation of the consortium. Result showed that is possible to quantitatively monitor members of a microbial consortium, with potential application for bioremediation of Arctic tundra soil. The relative abundance of consortium members was found to vary in laboratory culture; even greater variance may be expected in the soil environment. 37 refs., 3 tabs., 3 figs.

Thomassin-Lacroix, E. J. M.; Reimer, K. J. [Royal Military College, Dept. of Chemistry and Chemical Engineering, Kingston, On (Canada); Yu, Z.; Mohn, W. W. [British Columbia Univ., Dept. of Microbiology and Immunology, Vancouver, BC (Canada); Eriksson, M. [Royal Inst. of Technology, Dept. of Biotechnology, Stockholm (Sweden)

2001-12-01

98

Diversity of dechlorination pathways and organohalide respiring bacteria in chlorobenzene dechlorinating enrichment cultures originating from river sludge.  

Science.gov (United States)

Anaerobic reductive dechlorination of hexachlorobenzene (HCB) and three isomers of tetrachlorobenzene (TeCB) (1,2,3,4-, 1,2,3,5- and 1,2,4,5-TeCB) was investigated in microcosms containing chloroaromatic contaminated river sediment. All chlorobenzenes were dechlorinated to dichlorobenzene (DCB) or monochlorobenzene. From the sediment, a methanogenic sediment-free culture was obtained which dechlorinated HCB, pentachlorobenzene, three TeCB isomers, three trichlorobenzene (TCB) isomers (1,2,3-, 1,2,4- and 1,3,5-TCB) and 1,2-DCB. Dechlorination involved multiple pathways including the removal of doubly flanked, singly flanked and isolated chlorine substituents. 454-pyrosequencing of partial bacterial 16S rRNA genes amplified from selected chlorobenzene dechlorinating sediment-free enrichment cultures revealed the presence of a variety of bacterial species, including Dehalobacter and Dehalococcoides mccartyi, that were previously documented as organohalide respiring bacteria. A genus with apparent close relationship to Desulfitobacterium that also has been associated with organohalide respiration, composed the major fraction of the operational taxonomic units (OTUs). Another major OTU was linked with Sedimentibacter sp., a genus that was previously identified in strict co-cultures of consortia reductively dehalogenating chlorinated compounds. Our data point towards the existence of multiple interactions within highly chlorinated benzene dechlorinating communities. PMID:25037978

Vandermeeren, Pieter; Herrmann, Steffi; Cichocka, Danuta; Busschaert, Pieter; Lievens, Bart; Richnow, Hans-Hermann; Springael, Dirk

2014-09-01

99

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

Science.gov (United States)

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.

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

2014-06-01

100

Cultivation of Mesophilic Soil Crenarchaeotes in Enrichment Cultures from Plant Roots  

OpenAIRE

Because archaea are generally associated with extreme environments, detection of nonthermophilic members belonging to the archaeal division Crenarchaeota over the last decade was unexpected; they are surprisingly ubiquitous and abundant in nonextreme marine and terrestrial habitats. Metabolic characterization of these nonthermophilic crenarchaeotes has been impeded by their intractability toward isolation and growth in culture. From studies employing a combination of cultivation and molecular...

Simon, Holly M.; Jahn, Courtney E.; Bergerud, Luke T.; Sliwinski, Marek K.; Weimer, Paul J.; Willis, David K.; Goodman, Robert M.

2005-01-01

101

Culturally Diverse Literature: Enriching Variety in an Era of Common Core State Standards  

Science.gov (United States)

The authors argue for the overwhelming importance of finding and including culturally diverse literature into the curricula teachers are authorized to teach. They discuss the implications of use and offer ideas on how to identify quality literature to include in classroom and school libraries.

Boyd, Fenice B.; Causey, Lauren L.; Galda, Lee

2015-01-01

102

Growth enhancement of fowls by dietary administration of recombinant yeast cultures containing enriched growth hormone.  

Science.gov (United States)

In present study the methylotrophic yeast, Pichia pastoris, was used to express a recombinant growth hormone (rGH) gene of swine. A synthetic secretion cassette was constructed using the promoter of the alcohol oxidase1 gene (AOX1), and a alpha-factor signal peptide. After electroporatic transformation and zeocin selection, several clones exhibited high levels of rGH protein expression constituting more than 20% of total yeast protein. Over 95% of rGH was shown to be export into the culture supernatant. Yeast transformant containing the highest recombinant growth hormone level (rGH yeast) and native GS115 Pichia pastoris (non-rGH yeast, as a control) were separately cultured, harvested and adsorbed by wheat bran. Yeast cultures of four dosages (0.05, 0.1, 0.2, and 0.4%) were mixed respectively with chick basal diet and fed to simulated country chickens for 9 weeks. The results showed that, when compared to control chicks, the percentage of body weight gain was improved significantly (Pfed with diets containing 0.1 or 0.2% rGH-rich yeast culture at brooding stage, and in chicks fed with 0.4% rGH-rich yeast culture at growing stage. The average weight gain in rGH yeast treated groups for the full-term (0 to 63d) and short term (43 to 63d) of growth were 10.6 and 9.4%, respectively, better than the non-rGH yeast control group. These experimental data suggest that the use of rGH-containing yeast as a supplement in fed provided an alternative approach for growth improvement in simulated country chickens. PMID:11057760

Chen, C M; Cheng, W T; Chang, Y C; Chang, T J; Chen, H L

2000-09-15

103

Rapid, sensitive, and validated method for detection of Salmonella in food by an enrichment broth culture - nested PCR combination assay.  

Science.gov (United States)

A rapid nested PCR assay for detection of Salmonella from food was developed. The sensitivity of the assay developed was comparable to the traditional culture based methods with an advantage in reduction of assay time. The assay procedure with artificially contaminated samples was able to detect as low as 4CFU Salmonella/25g of food samples (sprout, carrot, cucumber and poultry meat). With two synthetic primers of 26 mer TS11 and 25 mer TS4, a 1.2kb fragment was amplified which served as a template for amplification of final 375bp product using TS11 and TS5 primers. No non-specific amplification from the native microbial flora of food samples was observed. The reaction generates a single band specific to Salmonella which allows the analyst to interpret data at ease and without any confusion. Enriched broth serves as template for the reaction which removes labour intensive DNA isolation procedures. In case of artificially contaminated samples, 6h enriched lactose broth can serve as template. However, for market samples where the organisms are under environmental stress, it is desirable to use template from Rappaport Vasiliadis medium. The assay also employes internal amplification control, which is amplified into a 300bp fragment and thus serves as positive control for the reaction and any possibility of false negative due to inhibitory action of food components on PCR reaction can be ruled out. PMID:18406104

Saroj, Sunil D; Shashidhar, R; Karani, Manisha; Bandekar, Jayant R

2008-06-01

104

Erythrocyte Enrichment in Hematopoietic Progenitor Cell Cultures Based on Magnetic Susceptibility of the Hemoglobin  

OpenAIRE

Using novel media formulations, it has been demonstrated that human placenta and umbilical cord blood-derived CD34+ cells can be expanded and differentiated into erythroid cells with high efficiency. However, obtaining mature and functional erythrocytes from the immature cell cultures with high purity and in an efficient manner remains a significant challenge. A distinguishing feature of a reticulocyte and maturing erythrocyte is the increasing concentration of hemoglobin and decreasing cell ...

Jin, Xiaoxia; Abbot, Stewart; Zhang, Xiaokui; Kang, Lin; Voskinarian-berse, Vanessa; Zhao, Rui; Kameneva, Marina V.; Moore, Lee R.; Chalmers, Jeffrey J.; Zborowski, Maciej

2012-01-01

105

Effects of Sulfuroxy Anions on Degradation of Pentachlorophenol by a Methanogenic Enrichment Culture  

OpenAIRE

We studied the degradation of pentachlorophenol (PCP) under methanogenic and sulfate-reducing conditions with an anaerobic mixed culture derived from sewage sludge. The consortium degraded PCP via 2,3,4,5-tetrachlorophenol, 3,4,5-trichlorophenol, and 3,5-dichlorophenol and eventually accumulated 3-chlorophenol. Dechlorination of PCP and metabolites was inhibited in the presence of sulfate, thiosulfate, and sulfite. A decrease in the rate of PCP transformation was noted when the endogenous dis...

Madsen, Torben; Aamand, Jens

1991-01-01

106

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

Directory of Open Access Journals (Sweden)

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.

Abdolmotaleb Seid-mohammadi

2013-02-01

107

Distribution of Microorganisms in Deep-Sea Hydrothermal Vent Chimneys Investigated by Whole-Cell Hybridization and Enrichment Culture of Thermophilic Subpopulations  

OpenAIRE

The microbial community structure of hydrothermal vent chimneys was evaluated by the combined use of enrichment cultures and whole-cell hybridizations with fluorescently labeled 16S rRNA-based oligonucleotide probes. Chimneys were collected during the Microsmoke cruise on the Mid-Atlantic Ridge and were subsampled on board and stored under reduced conditions or fixed. For estimation of culturable thermophiles, selective media were inoculated by dilution series of the samples and incubated at ...

Harmsen, H.; Prieur, D.; Jeanthon, C.

1997-01-01

108

Identification of enzymes involved in anaerobic benzene degradation by a strictly anaerobic iron-reducing enrichment culture.  

Science.gov (United States)

Anaerobic benzene degradation was studied with a highly enriched iron-reducing culture (BF) composed of mainly Peptococcaceae-related Gram-positive microorganisms. The proteomes of benzene-, phenol- and benzoate-grown cells of culture BF were compared by SDS-PAGE. A specific benzene-expressed protein band of 60 kDa, which could not be observed during growth on phenol or benzoate, was subjected to N-terminal sequence analysis. The first 31 amino acids revealed that the protein was encoded by ORF 138 in the shotgun sequenced metagenome of culture BF. ORF 138 showed 43% sequence identity to phenylphosphate carboxylase subunit PpcA of Aromatoleum aromaticum strain EbN1. A LC/ESI-MS/MS-based shotgun proteomic analysis revealed other specifically benzene-expressed proteins with encoding genes located adjacent to ORF 138 on the metagenome. The protein products of ORF 137, ORF 139 and ORF 140 showed sequence identities of 37% to phenylphosphate carboxylase PpcD of A. aromaticum strain EbN1, 56% to benzoate-CoA ligase (BamY) of Geobacter metallireducens and 67% to 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX) of A. aromaticum strain EbN1 respectively. These genes are proposed as constituents of a putative benzene degradation gene cluster (? 17 kb) composed of carboxylase-related genes. The identified gene sequences suggest that the initial activation reaction in anaerobic benzene degradation is probably a direct carboxylation of benzene to benzoate catalysed by putative anaerobic benzene carboxylase (Abc). The putative Abc probably consists of several subunits, two of which are encoded by ORFs 137 and 138, and belongs to a family of carboxylases including phenylphosphate carboxylase (Ppc) and 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX). PMID:20545743

Abu Laban, Nidal; Selesi, Draženka; Rattei, Thomas; Tischler, Patrick; Meckenstock, Rainer U

2010-10-01

109

The metabolism of neonicotinoid insecticide thiamethoxam by soil enrichment cultures, and the bacterial diversity and plant growth-promoting properties of the cultured isolates.  

Science.gov (United States)

A soil enrichment culture (SEC) rapidly degraded 96% of 200 mg L(-1) neonicotinoid insecticide thiamethoxam (TMX) in MSM broth within 30 d; therefore, its metabolic pathway of TMX, bacterial diversity and plant growth-promoting rhizobacteria (PGPR) activities of the cultured isolates were studied. The SEC transformed TMX via the nitro reduction pathway to form nitrso, urea metabolites and via cleavage of the oxadiazine cycle to form a new metabolite, hydroxyl CLO-tri. In addition, 16S rRNA gene-denaturing gradient gel electrophoresis analysis revealed that uncultured rhizobacteria are predominant in the SEC broth and that 77.8% of the identified bacteria belonged to uncultured bacteria. A total of 31 cultured bacterial strains including six genera (Achromobacter, Agromyces, Ensifer, Mesorhizobium, Microbacterium and Pseudoxanthomonas) were isolated from the SEC broth. The 12 strains of Ensifer adhaerens have the ability to degrade TMX. All six selected bacteria showed PGPR activities. E. adhaerens TMX-23 and Agromyces mediolanus TMX-25 produced indole-3-acetic acid, whereas E. adhaerens TMX-23 and Mesorhizobium alhagi TMX-36 are N2-fixing bacteria. The six-isolated microbes were tolerant to 200 mg L(-1) TMX, and the growth of E. adhaerens was significantly enhanced by TMX, whereas that of Achromobacter sp. TMX-5 and Microbacterium sp.TMX-6 were enhanced slightly. The present study will help to explain the fate of TMX in the environment and its microbial degradation mechanism, as well as to facilitate future investigations of the mechanism through which TMX enhances plant vigor. PMID:24762175

Zhou, Guang-Can; Wang, Ying; Ma, Yuan; Zhai, Shan; Zhou, Ling-Yan; Dai, Yi-Jun; Yuan, Sheng

2014-06-01

110

Denitrification and the denitrifier community in coastal microbial mats.  

Science.gov (United States)

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 potential rate of denitrification (7.0 ± 1.0 mmol N m(-2) d(-1)) was observed during summer at station 1 (supra-littoral). The rates of denitrification were much lower in the stations 2 (marine) and 3 (intermediate) (respectively 0.1 ± 0.05 and 0.7 ± 0.2 mmol N m(-2) d(-1)) and showed less seasonality when compared to station 1. The denitrifying community at station 1 was also more diverse than that at station 2 and 3, which were more similar to each other than either of these stations to station 1. In all three stations, the diversity of both nirS and nirK denitrifiers was higher in summer when compared to winter. The location along the tidal gradient seems to determine the composition, diversity and activity of the denitrifier community, which may be driven by salinity, nitrate/nitrite and organic carbon. Both nirS and nirK denitrifiers are equally present and therefore they are likely to play a role in the denitrification of the microbial mats studied. PMID:25764561

Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J

2015-03-01

111

Proteins differentially expressed in human beta-cells-enriched pancreatic islet cultures and human insulinomas.  

Science.gov (United States)

In view of the great demand for human beta-cells for physiological and medical studies, we generated cell lines derived from human insulinomas which secrete insulin, C-peptide and express neuroendocrine and islet markers. In this study, we set out to characterize their proteomes, comparing them to those of primary beta-cells using DIGE followed by MS. The results were validated by Western blotting. An average of 1800 spots was detected with less than 1% exhibiting differential abundance. Proteins more abundant in human islets, such as Caldesmon, are involved in the regulation of cell contractility, adhesion dependent signaling, and cytoskeletal organization. In contrast, almost all proteins more abundant in insulinoma cells, such as MAGE2, were first described here and could be related to cell survival and resistance to chemotherapy. Our proteomic data provides, for the first time, a molecular snapshot of the orchestrated changes in expression of proteins involved in key processes which could be correlated with the altered phenotype of human beta-cells. Collectively our observations prompt research towards the establishment of bioengineered human beta-cells providing a new and needed source of cultured human beta-cells for beta-cell research, along with the development of new therapeutic strategies for detection, characterization and treatment of insulinomas. PMID:23891624

Terra, Letícia F; Teixeira, Priscila C; Wailemann, Rosangela A M; Zelanis, André; Palmisano, Giuseppe; Cunha-Neto, Edecio; Kalil, Jorge; Larsen, Martin R; Labriola, Leticia; Sogayar, Mari C

2013-12-01

112

Proteins differentially expressed in human beta-cells-enriched pancreatic islet cultures and human insulinomas  

DEFF Research Database (Denmark)

In view of the great demand for human beta-cells for physiological and medical studies, we generated cell lines derived from human insulinomas which secrete insulin, C-peptide and express neuroendocrine and islet markers. In this study, we set out to characterize their proteomes, comparing them to those of primary beta-cells using DIGE followed by MS. The results were validated by Western blotting. An average of 1800 spots was detected with less than 1% exhibiting differential abundance. Proteins more abundant in human islets, such as Caldesmon, are involved in the regulation of cell contractility, adhesion dependent signaling, and cytoskeletal organization. In contrast, almost all proteins more abundant in insulinoma cells, such as MAGE2, were first described here and could be related to cell survival and resistance to chemotherapy. Our proteomic data provides, for the first time, a molecular snapshot of the orchestrated changes in expression of proteins involved in key processes which could be correlated with the altered phenotype of human beta-cells. Collectively our observations prompt research towards the establishment of bioengineered human beta-cells providing a new and needed source of cultured human beta-cells for beta-cell research, along with the development of new therapeutic strategies for detection, characterization and treatment of insulinomas.

Terra, Letícia F; Teixeira, Priscila C

2013-01-01

113

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

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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.

Javier Vilcáez

2009-01-01

114

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)

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

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

2008-05-01

115

Prostaglandin E2 increases proenkephalin mRNA level in rat astrocyte-enriched culture.  

Science.gov (United States)

The effect of prostaglandin E2 (PGE2) on proenkephalin (proENK) mRNA expression in primary cultured rat astrocytes was studied. The proENK mRNA level was significantly increased about 3.3-fold 4 h after PGE2 (10 microM) treatment and this increase was potentiated by the pre-treatment with cycloheximide (CHX; 15 microM) about 1.7-fold as much as PGE2 alone treated cells. The pretreatment with staurosporine (1 microM) completely inhibited the increase of PGE2-induced proENK mRNA level, although only a partial inhibition of PGE2-induced proENK mRNA level (approximately 1.5-fold) by H89 (10 microM) was observed. The increase of PGE2-induced proENK mRNA level was not affected by the pretreatment with PD98059 (1, 5, and 10 microM), omega-conotoxin GIVA (1 microM), nimodipine (1 microM), calmidazolium (1 microM), or KN-62 (1 microM). In addition to the proENK mRNA level, PGE2 also increased c-Fos (approximately 4.3-fold), Fra-1 ( approximately 3.8 fold), and Fra-2 (approximately 8.2-fold) protein levels at 4 h after drug treatment. However, c-Jun, JunB, and JunD protein levels were not affected by PGE2. Indeed, PGE2 failed to up-regulate c-jun mRNA expression as well as its protein product. Surprisingly, although three Jun proteins were not induced by PGE2, AP-1 and ENKCRE-2 DNA binding activities were increased by PGE2, (approximately 5 and approximately 2.8-fold, respectively) and which were effectively reduced by CHX (approximately 2.5 and 2-fold, respectively). In western blot analyses, PGE2 enhanced the phosphorylation of CREB (approximately 2.6-fold at 1 h), and CHX showed a potentiative effect on PGE2-induced CREB phosphorylation ( approximately 1.7 fold at 1 h) which is similar to the action on proENK mRNA regulation. Our results suggest that PGE2 increases proENK mRNA expression via activating serine/threonine protein kinase such as PKA, but not calcium/calmodulin dependent protein kinase and MAPK. In addition, phosphorylation of CREB rather than the increase of AP-1 may have a possible role at least early stage in PGE2-induced proENK mRNA level and CHX-evoked potentiation. PMID:9757037

Won, J S; Suh, H W; Kim, Y H; Song, D K; Huh, S O; Lee, J K; Lee, K J

1998-10-01

116

Optimizing BTEX biodegradation under denitrifying conditions  

International Nuclear Information System (INIS)

Leaking underground storage tanks are a major source of ground water contamination by petroleum hydrocarbons. Gasoline and other fuels contain benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX), which are hazardous compounds, regulated by the U.S. Environmental Protection Agency (EPA). Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Michigan, were amended with selected concentrations of nutrients and one or more hydrocarbons. Toluene, ethylbenzene, m-xylene, and p-xylene, were degraded to below 5 micrograms/L when present as sole source substrates; stoichiometric calculations indicated that nitrate removal was sufficient to account for 70 to 80% of the compounds being mineralized. o-Xylene was recalcitrant when present as a sole source substrate, but was slowly degraded in the presence of the other hydrocarbons. Benzene was not degraded within one year, regardless of whether it was available as a sole source substrate or in combination with toluene, phenol, or catechol. Pre-exposure to low levels of BTEX and nutrients had variable effects, as did the addition of different concentrations of ammonia and phosphate. Nitrate concentrations as high as 500 mg/L NO3-N were slightly inhibitory. These data indicate that nitrate-medtory. These data indicate that nitrate-mediated biodegradation of BTEX at Traverse City can occur under a variety of environmental conditions with rates relatively independent of nutrient concentrations. However, the data reaffirm that benzene is recalcitrant under strictly anaerobic conditions in these samples

117

Enhanced enrichment of prostate cancer stem-like cells with miniaturized 3D culture in liquid core-hydrogel shell microcapsules  

Science.gov (United States)

Cancer stem-like cells (CSCs) are rare subpopulations of cancer cells that are reported to be responsible for cancer resistance and metastasis associated with conventional cancer therapies. Therefore, effective enrichment/culture of CSCs is of importance to both the understanding and treatment of cancer. However, it usually takes approximately 10 days for the widely used conventional approach to enrich CSCs through the formation of CSC-containing aggregates. Here we report the time can be shortened to 2 days while obtaining prostate CSC-containing aggregates with better quality based on the expression of surface receptor markers, dye exclusion, gene and protein expression, and in vivo tumorigenicity. This is achieved by encapsulating and culturing human prostate cancer cells in the miniaturized 3D liquid core of microcapsules with an alginate hydrogel shell. The miniaturized 3D culture in core–shell microcapsules is an effective strategy for enriching/culturing CSCs in vitro to facilitate cancer research and therapy development. PMID:24952981

Yu, Jianhua; Lu, Xiongbin; Zynger, Debra L.; He, Xiaoming

2015-01-01

118

Isotope effects and O-exchange with water during N2O production by denitrifying fungi  

Science.gov (United States)

N2O from soil denitrification originates from bacteria and - to an unknown extent - also from fungi. In pure culture studies, bacterial and fungal denitrification showed differences in isotopomer ratios of N2O. Isotopomer ratios of N2O can be expressed as 15N site preference (SP), i.e. the difference between ?15N of the central and terminal N-position of the asymmetric N2O molecule and might be suitable to distinguish between bacterial and fungal N2O under denitrifying soil conditions. Oxygen exchange takes place between H2O and intermediates during the denitrification process. Several studies showed that O-exchange of bacterial denitrifiers varies, but information about fungal O-exchanges is lacking. The objectives of the study presented are i) to verify SP of fungal N2O reported for two strains from pure culture studies and ii) to analyze the oxygen exchange between intermediates and H2O during denitrification in fungal pure cultures. Six different fungal pure cultures known to be capable of denitrification were incubated under anaerobic conditions, either with nitrite or nitrate. Gas samples were analysed for concentration and isotopic signatures (SP, average ?15N, ?18O) of N2O. To investigate the oxygen exchange, both treatments were also established in a tracer experiment where 18O-labelled water was used in the medium. The fungal strains evaluated so far indicate similar SP as reported previously. Concerning the amount of N2O produced, the nitrite led to a higher yield than nitrate. O-exchange with 18O-labelled water during fungal denitrification was visible. Using nitrite, the exchange ranged amounted from 39% to full exchange while nitrate led to exchange rates between 13% and full exchange. Detailed results will be presented.

Rohe, Lena; Braker, Gesche; Well, Reinhard; Giesemann, Anette; Anderson, Traute-Heidi; Wrage-Mönnig, Nicole; Flessa, Heinz

2013-04-01

119

Establishment of microbial eukaryotic enrichment cultures from a chemically stratified antarctic lake and assessment of carbon fixation potential.  

Science.gov (United States)

Lake Bonney is one of numerous permanently ice-covered lakes located in the McMurdo Dry Valleys, Antarctica. The perennial ice cover maintains a chemically stratified water column and unlike other inland bodies of water, largely prevents external input of carbon and nutrients from streams. Biota are exposed to numerous environmental stresses, including year-round severe nutrient deficiency, low temperatures, extreme shade, hypersalinity, and 24-hour darkness during the winter (1). These extreme environmental conditions limit the biota in Lake Bonney almost exclusively to microorganisms (2). Single-celled microbial eukaryotes (called "protists") are important players in global biogeochemical cycling (3) and play important ecological roles in the cycling of carbon in the dry valley lakes, occupying both primary and tertiary roles in the aquatic food web. In the dry valley aquatic food web, protists that fix inorganic carbon (autotrophy) are the major producers of organic carbon for organotrophic organisms (4, 2). Phagotrophic or heterotrophic protists capable of ingesting bacteria and smaller protists act as the top predators in the food web (5). Last, an unknown proportion of the protist population is capable of combined mixotrophic metabolism (6, 7). Mixotrophy in protists involves the ability to combine photosynthetic capability with phagotrophic ingestion of prey microorganisms. This form of mixotrophy differs from mixotrophic metabolism in bacterial species, which generally involves uptake dissolved carbon molecules. There are currently very few protist isolates from permanently ice-capped polar lakes, and studies of protist diversity and ecology in this extreme environment have been limited (8, 4, 9, 10, 5). A better understanding of protist metabolic versatility in the simple dry valley lake food web will aid in the development of models for the role of protists in the global carbon cycle. We employed an enrichment culture approach to isolate potentially phototrophic and mixotrophic protists from Lake Bonney. Sampling depths in the water column were chosen based on the location of primary production maxima and protist phylogenetic diversity (4, 11), as well as variability in major abiotic factors affecting protist trophic modes: shallow sampling depths are limited for major nutrients, while deeper sampling depths are limited by light availability. In addition, lake water samples were supplemented with multiple types of growth media to promote the growth of a variety of phototrophic organisms. RubisCO catalyzes the rate limiting step in the Calvin Benson Bassham (CBB) cycle, the major pathway by which autotrophic organisms fix inorganic carbon and provide organic carbon for higher trophic levels in aquatic and terrestrial food webs (12). In this study, we applied a radioisotope assay modified for filtered samples (13) to monitor maximum carboxylase activity as a proxy for carbon fixation potential and metabolic versatility in the Lake Bonney enrichment cultures. PMID:22546995

Dolhi, Jenna M; Ketchum, Nicholas; Morgan-Kiss, Rachael M

2012-01-01

120

Effect of earthworm feeding guilds on ingested dissimilatory nitrate reducers and denitrifiers in the alimentary canal of the earthworm.  

Science.gov (United States)

The earthworm gut is an anoxic nitrous oxide (N(2)O)-emitting microzone in aerated soils. In situ conditions of the gut might stimulate ingested nitrate-reducing soil bacteria linked to this emission. The objective of this study was to determine if dissimilatory nitrate reducers and denitrifiers in the alimentary canal were affected by feeding guilds (epigeic [Lumbricus rubellus], anecic [Lumbricus terrestris], and endogeic [Aporrectodea caliginosa]). Genes and gene transcripts of narG (encodes a subunit of nitrate reductase and targets both dissimilatory nitrate reducers and denitrifiers) and nosZ (encodes a subunit of N(2)O reductase and targets denitrifiers) were detected in guts and soils. Gut-derived sequences were similar to those of cultured and uncultured soil bacteria and to soil-derived sequences obtained in this study. Gut-derived narG sequences and narG terminal restriction fragments (TRFs) were affiliated mainly with Gram-positive organisms (Actinobacteria). The majority of gut- and uppermost-soil-derived narG transcripts were affiliated with Mycobacterium (Actinobacteria). In contrast, narG sequences indicative of Gram-negative organisms (Proteobacteria) were dominant in mineral soil. Most nosZ sequences and nosZ TRFs were affiliated with Bradyrhizobium (Alphaproteobacteria) and uncultured soil bacteria. TRF profiles indicated that nosZ transcripts were more affected by earthworm feeding guilds than were nosZ genes, whereas narG transcripts were less affected by earthworm feeding guilds than were narG genes. narG and nosZ transcripts were different and less diverse in the earthworm gut than in mineral soil. The collective results indicate that dissimilatory nitrate reducers and denitrifiers in the earthworm gut are soil derived and that ingested narG- and nosZ-containing taxa were not uniformly stimulated in the guts of worms from different feeding guilds. PMID:20656855

Depkat-Jakob, Peter S; Hilgarth, Maik; Horn, Marcus A; Drake, Harold L

2010-09-01

121

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

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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 cultures.

Hug Laura A

2012-07-01

122

Development of PCR primer systems for amplification of nitrite reductase genes (nirK and nirS) to detect denitrifying bacteria in environmental samples  

Energy Technology Data Exchange (ETDEWEB)

A system was developed for the detection of denitrifying bacteria by the application of specific nitrite reductase gene fragments with PCR. Primer sequences were found for the amplification of fragments from both nitrite reductase genes (nirK and nirS) after comparative sequence analysis. Whenever amplification was tried with these primers, the known nir type of denitrifying laboratory cultures could be confirmed. Likewise, the method allowed a determination of the nir type of five laboratory strains. The nirK gene could be amplified from Blastobacter denitrificans, Alcaligenes xylosoxidans, and Alcaligenes sp. (DSM 30128); the nirS gene was amplified from Alcaligenes eutrophus DSM 530 and from the denitrifying isolate IFAM 3698. For each of the two genes, at least one primer combination amplified successfully for all of the test strains. Specific amplification products were not obtained wit h nondenitrifying bacteria or with strains of the other nir type. The specificity of the amplified products was confirmed by subsequent sequencing. These results suggest the suitability of the method for the qualitative detection of denitrifying bacteria in environmental samples. This was shown by applying the generally amplifying primer combination for each nir gene developed in this study to total DNA preparations from aquatic habitats.

Braker, G.; Witzel, K.P. [Max-Planck-Inst. fuer Limnologie, Ploen (Germany); Fesefeldt, A. [Univ. Kiel (Germany). Inst. fuer Allgemeine Mikrobiologie

1998-10-01

123

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

124

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

International Nuclear Information System (INIS)

Highlights: ? We started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture. ? Sulfate-reducing bacteria and anode-respiring bacteria were enriched in anodic biofilms. ? The MFC effectively remove sulfate to elementary sulfur in the presence of lactate. ? 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.

125

Denitrifying activity of activated sludge in suspension and in biofilm  

OpenAIRE

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...

Cortez, Susana; Teixeira, P.; Oliveira, Rosa?rio; Mota, M.

2008-01-01

126

Determination of alachlor and its metabolite 2,6-diethylaniline in microbial culture medium using online microdialysis enriched-sampling coupled to high-performance liquid chromatography.  

Science.gov (United States)

In this study, a simple and novel microdialysis sampling technique incorporating hollow fiber liquid phase microextraction (HF-LPME) coupled online to high-performance liquid chromatography (HPLC) for the one-step sample pretreatment and direct determination of alachlor (2-chloro-2',6'-diethyl-N -(methoxymethyl)acetanilide) and its metabolite 2,6-diethylaniline (2,6-DEA) in microbial culture medium has been developed. A reversed-phase C-18 column was utilized to separate alachlor and 2,6-DEA from other species using an acetonitrile/water mixture (1:1) containing 0.1 M phosphate buffer solution at pH 7.0 as the mobile phase. Detection was carried out with a UV detector operated at 210 nm. Parameters that influenced the enrichment efficiency of online HF-LPME sampling, including the length of the hollow fiber, the perfusion solvent and its flow rate, the pH, and the salt added in sample solution, as well as chromatographic conditions were thoroughly optimized. Under optimal conditions, excellent enrichment efficiency was achieved by the microdialysis of a sample solution (pH 7.0) using hexane as perfusate at the flow rate of 4 ?L/min. Detection limits were 72 and 14 ng/mL for alachlor and 2,6-DEA, respectively. The enrichment factors were 403 and 386 (RSD < 5%) for alachlor and 2,6-DEA, respectively, when extraction was performed by using a 40 cm regenerated cellulose hollow fiber and hexane as perfusion solvent at the flow rate of 0.1 ?L/min. The proposed method provides a sensitive, flexible, fast, and eco-friendly procedure to enrich and determine alachlor and its metabolite (2,6-DEA) in microbial culture medium. PMID:21707080

Chen, Chi-Zen; Yan, Cheing-Tong; Kumar, Ponnusamy Vinoth; Huang, Jenn-Wen; Jen, Jen-Fon

2011-08-10

127

Diversity of Denitrifying Bacteria in the San Francisco Bay  

Science.gov (United States)

We compared the diversity of communities of denitrifying bacteria from the San Francisco Bay to investigate whether environmental factors affect diversity. To do this, we studied the sequence diversity of the marker gene nirK. nirK codes for the enzyme nitrite reductase which helps reduce nitrite to nitric oxide, an important step in denitrification. Sediment samples were collected spatially from five different locations and temporally during the four different seasons along a salinity gradient in the bay. After collecting samples and extracting DNA from them, we used PCR to amplify our gene of interest, created clone libraries for sequencing, and compared phylogenetic trees from the different communities. Based on several phylogenetic analyses on our tree and environments, we saw that denitrifying bacteria from the North and Central Bay form distinct spatial clusters; Central Bay communities are very similar to each other, while communities from the North Bay are more distinct from each other and from communities in the Central Bay. Bacteria from site 8.1M (Carquinez Strait) showed the most cm-scale spatial diversity, and there was the most species richness during the winter. All this suggests that diversity of communities of denitrifying bacteria may be affected by spatial and temporal environmental factors.

Atluri, A.; Lee, J.; Francis, C. A.

2012-12-01

128

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

Energy Technology Data Exchange (ETDEWEB)

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. •Warming impact strongly depends on the bacterial successional trajectory.

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

129

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

International Nuclear Information System (INIS)

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. •Warming impact strongly depends on the bacterial successional trajectory

130

Cr(VI) reduction under aerobic and denitrifying conditions by an aquifer-derived Pseudomonad  

Science.gov (United States)

Chromium contamination of groundwater is widespread within the Department of Energy (DOE) complex. For example, at DOE’s Hanford 100 Area in Washington state, the volume of Cr-contaminated groundwater is estimated to be 1.5 billion gallons. Bioremediation (in situ reductive immobilization) studies involving injection of a lactate-containing polymer have been conducted in the Hanford 100H area, where we have observed sequential use of the dissolved electron acceptors present in groundwater, namely, oxygen, nitrate, and sulfate. As part of an effort to explore Cr(VI) reduction under relevant electron-accepting conditions and with relevant bacteria, we have conducted studies with strain RCH2, a denitrifying bacterium similar to Pseudomonas stutzeri that was isolated from the Hanford 100H aquifer. Cell suspension studies with lactate demonstrated that Cr(VI) reduction could occur under either denitrifying or aerobic conditions (at comparable rates), and that reduction was much more rapid when the terminal electron acceptor (i.e., nitrate or O2) was present. It appears that, under both aerobic and denitrifying conditions, the chromate reductase gene(s) are not inducible by Cr; this conclusion is based on the fact that these cell suspension studies were conducted with cells grown in the absence of Cr and resuspended in a buffer that included chloramphenicol, which inhibits protein synthesis. As our studies indicate that anaerobic Cr(VI) reduction by strain RCH2 is much more rapid in the presence of nitrate (i.e., during denitrification) than in its absence, we explored molecular methods that could readily assess in situ denitrification. Specifically, we investigated whether the gene and transcript copy number of diagnostic denitrification genes (nirS and narG) in groundwater could be used to estimate in situ denitrification rates. Continuous culture (chemostat) studies showed strong correlations (r2 values > 0.93) between denitrification rate and either nirS or narG transcript copy number, suggesting that monitoring expression of such genes (and relevant chromate reductase genes, when characterized) in groundwater could provide valuable information for understanding the biogeochemical dynamics of in situ chromate reduction.

Beller, H. R.; Han, R.; Geller, J. T.

2009-12-01

131

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

Science.gov (United States)

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 ?D values has been observed during aerobic metabolism, denitrifying cultures produce a more limited range in ?D 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 ?D 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 ?D and metabolism previously understood from aerobic bacteria is not universally applicable.

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

2012-12-01

132

Cultivo del nematodo Panagrellus redivivus (Goodey, 1945) en un medio de avena enriquecida con Spirulina sp. / Nematode culture of Panagrellus redivivus (Goodey, 1945) with Spirulina sp. - enriched oatmeal  

Scientific Electronic Library Online (English)

Full Text Available El nematodo Panagrellus redivivus se cultivó en dos medios: uno con hojuelas de avena y otro con hojuelas de avena enriquecido con Spirulina sp., en recipientes de plástico de 15x15x5 cm de altura con 200 g de hojuela de avena y 300 mL de agua purificada. Se utilizaron 5 g de Spirulina en el medio. [...] Se utilizó el programa SYSTAT versión 10.2 para el análisis estadístico; para determinar las diferencias significativas entre los tratamientos, se usó un análisis de varianza unidireccional (ANDEVA) con una confiabilidad ?= 0,05. Los resultados obtenidos muestran que el crecimiento de las poblaciones de nematodos en el medio enriquecido con Spirulina presentó la mayor abundancia de individuos a la segunda semana del cultivo, mientras que la población que creció en el medio de avena, presentó su mayor registro a la quinta semana del cultivo y no alcanzó el número de organismos que tuvo la población cultivada en el medio con Spirulina. El contenido de aminoácidos de las poblaciones de ambos medios se comparó y se cotejaron con los reportados para Artemia alimentada con Spirulina, observándose que en la mayoría de los aminoácidos las cantidades fueron mayores en P. redivivus cultivado en el medio con Spirulina. La composición de ácidos grasos en los nematodos cultivados en ambos medios presentó diferencias significativas entre los ácidos grasos linoleico, araquidónico y eicosapentenoico los cuales fueron en mayor porcentaje que los reportados en P. redivivus cultivado en avena con aceite de girasol. Estos datos demuestran que la cianobacteria Spirulina sp. acelera el crecimiento de la población del nematodo y permite la presencia de aminoácidos y ácidos grasos, y hace que estos nematodos puedan cubrir los requerimientos nutritivos de larvas de peces dulceacuícolas, sin embargo, se requieren estudios que lo demuestren Abstract in english The nematode Pangrellus redivivus was cultured in two media: one with oat flakes and the other with Spirulina sp.-enriched oat flakes, in 15x15x5 cm plastic containers with 200 g oat flakes and 300 mL purified water. Five grams of Spirulina was used in the medium. SYSTAT version 10.2 was used for st [...] atistical analysis; to determine the significant differences between treatment a unidirectional analysis of variance (ANOVA) was used with a confidence level of ?= 0.05. The results show that growth of the nematode population in the Spirulina-enriched medium presented the highest abundance of individuals on the second week of culture, whereas the population grown in the oat flakes medium showed the highest abundance on the fifth week of culture and did not reach the number of organisms attained by the population cultured in the Spirulina-enriched medium. The amino acids content of the populations from both media were compared to those reported for Artemia fed with Spirulina, observing that the amounts were higher for most amino acids in P. redivivus cultured in the Spirulina-enriched medium. The composition of fatty acids in the nematode cultures in both media depicted significant differences for the linoleic, arachidonic, and eicosapentaenoic fatty acids, which were found in a higher percentage than reported for P. redivivus cultures in oat flakes supplemented with sunflower oil. These data reveal that the cyanobacterium Spirulina sp. accelerates growth of the nematode populations and allows the presence of amino and fatty acids, making these nematodes suitable to cover the nutritional requirements of freshwater fish larvae, but further studies are needed to demonstrate it

Ramón, de Lara; Thalía, Castro; Jorge, Castro; Germán, Castro.

2007-04-01

133

Growth and enrichment of pentachlorophenol-degrading microorganisms in the nutristat, a substrate concentration-controlled continuous culture.  

OpenAIRE

The nutristat, a substrate concentration-controlled continuous culture, was used to grow pentachlorophenol (PCP)-degrading microorganisms. The PCP concentration control system consisted of on-line measurement of the PCP concentration in the culture vessel with a tangential filter and a flowthrough spectrophotometer. With PCP concentrations between 45 and 77 microM, a stable situation was established in the nutristat, with an average dilution rate of 0.035 +/- 0.003 h-1. Compared with those of...

Rutgers, M.; Bogte, J. J.; Breure, A. M.; Andel, J. G.

1993-01-01

134

Adaptation of Denitrifying Populations to Low Soil pH †  

OpenAIRE

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 den...

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

1985-01-01

135

Survival of Denitrifiers in Nitrate-Free, Anaerobic Environments  

OpenAIRE

Experiments were undertaken to explain the occurrence of a high denitrification capacity in anaerobic, NO3--free habitats. Deep layers of freshwater sediments that were buried more than 40 years ago and digested sludge were the habitats studied. The denitrifier populations were 3.1 × 103 and 3.1 × 105 cells cm-3 in deep sediments from a river and lake, respectively, and 5.3 × 106 cells cm-3 in digested sludge. The denitrification capacities of the samples reflected the population densities...

Jørgensen, Kirsten S.; Tiedje, James M.

1993-01-01

136

Modeling denitrifying sulfide removal process using artificial neural networks  

International Nuclear Information System (INIS)

The denitrifying sulfide removal (DSR) process has complex interactions between autotrophic and heterotrophic denitrifers; thus, constructing a detailed mechanistic model and proper control architecture is difficult. Artificial neural networks (ANNs) are capable of inferring the complex relationships between input and output process variables without a detailed characterization of the mechanisms governing the process. This work presents a novel ANN that accurately predicts the steady-state performance of an expended granular sludge bed (EGSB)-DSR bioreactor for nitrite denitrification and the complete DSR process. The proposed ANN shows that at a threshold hydraulic retention time (HRT) < 7 h, influent sulfide concentration markedly affects reactor performance.

137

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

OpenAIRE

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 o...

Napaporn Sae-Lee; Orapin Kerdchoechuen; Natta Laohakunjit

2014-01-01

138

Characterization of denitrifying activity by the alphaproteobacterium, Sphingomonas wittichii RW1.  

Science.gov (United States)

Sphingomonas wittichii RW1 has no reported denitrifying activity yet encodes nitrite and nitric oxide reductases. The aims of this study were to determine conditions under which S. wittichii RW1 consumes nitrite (NO(-) 2) and produces nitrous oxide (N2O), examine expression of putative genes for N-oxide metabolism, and determine the functionality of chromosomal (ch) and plasmid (p) encoded quinol-dependent nitric oxide reductases (NorZ). Batch cultures of wildtype (WT) and a norZ ch mutant of S. wittichii RW1 consumed NO(-) 2 and produced N2O during stationary phase. The norZ ch mutant produced N2O, although at significantly lower levels (c.a. 66-87%) relative to the WT. Rates of N2O production were 2-3 times higher in cultures initiated at low relative to atmospheric O2 per unit biomass, although rates of NO(-) 2 consumption were elevated in cultures initiated with atmospheric O2 and 1 mM NaNO2. Levels of mRNA encoding nitrite reductase (nirK), plasmid-encoded nitric oxide dioxygenase (hmp p) and plasmid-encoded nitric oxide reductase (norZ p) were significantly higher in the norZ ch mutant over a growth curve relative to WT. The presence of NO(-) 2 further increased levels of nirK and hmp p mRNA in both the WT and norZ ch mutant; levels of norZ p mRNA compensated for the loss of norZ ch expression in the norZ ch mutant. Together, the results suggest that S. wittichii RW1 denitrifies NO(-) 2 to N2O and expresses gene products predicted to detoxify N-oxides. So far, only S. wittichii strains within four closely related taxa have been observed to encode both nirK and norZ genes, indicating a species-specific lateral gene transfer that may be relevant to the niche preference of S. wittichii. PMID:25147547

Cua, Lynnie S; Stein, Lisa Y

2014-01-01

139

Characterization of denitrifying activity by the alphaproteobacterium, Sphingomonas wittichii RW1  

Directory of Open Access Journals (Sweden)

Full Text Available Sphingomonas wittichii RW1 has no reported denitrifying activity yet encodes nitrite and nitric oxide reductases. The aims of this study were to determine conditions under which S. wittichii RW1 consumes nitrite (NO2- and produces nitrous oxide (N2O, examine expression of putative genes for N-oxide metabolism, and determine the functionality of chromosomal (ch and plasmid (p encoded quinol-dependent nitric oxide reductases (NorZ. Batch cultures of wildtype (WT and a norZch mutant of S. wittichii RW1 consumed NO2- and produced N2O during stationary phase. The norZch mutant produced N2O, although at significantly lower levels (c.a. 66-87% relative to the WT. Rates of N2O production were 2-3 times higher in cultures initiated at low relative to atmospheric O2 per unit biomass, although rates of NO2- consumption were elevated in cultures initiated with atmospheric O2 and 1 mM NaNO2. Levels of mRNA encoding nitrite reductase (nirK, plasmid-encoded nitric oxide dioxygenase (hmpp and plasmid-encoded nitric oxide reductase (norZp were significantly higher in the norZch mutant over a growth curve relative to WT. The presence of NO2- further increased levels of nirK and hmpp mRNA in both the WT and norZch mutant; levels of norZp mRNA compensated for the loss of norZch expression in the norZch mutant. Together, the results suggest that S. wittichii RW1 denitrifies NO2- to N2O and expresses gene products predicted to detoxify N-oxides. So far, only S. wittichii strains within four closely related taxa have been observed to encode both nirK and norZ genes, indicating a species-specific lateral gene transfer that may be relevant to the niche preference of S. wittichii.

LisaYStein

2014-08-01

140

Effects of Temperature on Denitrifying Growth and Nitrate Reduction End Products of Comamonas testosteroni Isolated from Estuarine Sediment  

Directory of Open Access Journals (Sweden)

Full Text Available Predictions of seasonal changes in N2O emission that occur in natural estuaries are important to anticipate the future implications of global warming. This study showed the effect of temperature on denitrifying growth and nitrate reduction end product of Comamonas testoteroni isolated from estuarine sediment using both batch and continuous cultures. The ?max values of Comamonas testosteroni grown in anaerobic batch culture were increased with increasing temperature, and the highest ?max was found at 26 °C. Concentrations of nitrate reduced (mg-1 dried weight cells were higher at low temperature. Concentrations of N2 produced were higher at low temperature and the production of N2 was higher than both NO2- and N2O productions

IMAN RUSMANA

2007-01-01

141

TANK CULTURE OF SUNSHINE BASS MORONE CHRYSOPS X M. SAXATILIS FINGERLINGS WITH THREE CONCENTRATIONS OF ENRICHED ROTIFERS AND ARTEMIA NAUPLII  

Science.gov (United States)

Sunshine bass Morone chrysops X M. saxatilis fry are obligate zooplankton consumers. They begin to eat rotifers at 4 days post hatch but soon switch to larger zooplankton. For tank culture, the rotifer Brachionus plicatus appears to be a suitable first food. Within a few days the fry may be switche...

142

An enrichment and acclimation procedure to obtain photo heterotrophic cultures for H2 production from organic effluents  

International Nuclear Information System (INIS)

Production of H2 via photo heterotrophic is an attractive alternative, due to the capacity of photo heterotrophic organisms to convert the organic matter of effluents into H2. 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 H2. (Author)

143

A Fungal Cytochrome P-450nor Confers Denitrifying Ability to Tobacco By-2 Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Reactive nitrogen gases progressively contribute to the global warming. Development of gas-gas denitrifying plants that can efficiently reduce reactive nitrogen gases to dinitrogen (N2 could help to mitigate the effect of these gases. Taking the advances in gene manipulation technology, tobacco BY-2 cells were transformed with the fungus Cylindrocarpon tonkinense cytochrome P-450nor2 (Cnor2 gene. The product of this gene acts as nitric oxide reductase (nor. Transgenic BY-2 cell clones cultured in 15N-labelled nitrate (15NO3- actively evolved 15N2O gas up to 35-folds compared to the wild-type cells. In 15N-labelled ammonium (15NH4+, the transgenic and wild-type cells produced comparable amounts of 15N2O. This indicates that ammonium is not a direct substrate for nor and the small amount of N2O observed may be due to the nitrification of ammonium to nitrite. Addition of tungstate (a nitrate reductase inhibitor and cyanide to the transgenic cell cultures strongly inhibited 15N2O production. Activity of nor enzyme was also confirmed by in vitro activity assay. These observations together suggest that Cnor2 is actively expressed and enhanced the reduction of nitrate to N2O in plant cells. This finding indicates that plant cells are capable to tackle the denitrification pathway.

Babiker M.A. Abdel-Banat

2008-01-01

144

Effects of resveratrol on enrichment of adipose-derived stem cells and their differentiation to osteoblasts in two-and three-dimensional cultures.  

Science.gov (United States)

The goal of this study was to develop a method for increasing the yield of multipotent adipose-derived mesenchymal stem cells (ASCs) and osteoprogenitor cells (OPCs) from subcutaneous fat. After removing mature adipocytes and haematopoietic cells from rat inguinal fat, ASCs in the remaining cell population were verified by their attachment to plastic, surface marker profile (CD271(+), CD73(+) and CD45(-)) and ability to differentiate into adipocytes, chondrocytes and osteoblasts. OPCs were defined as E11(+) and OCN(+). Adherent cells were cultured in growth medium (GM) or osteogenic medium (OM) and treated with resveratrol (0, 12.5, and 25 µM) for 7 days; ASCs and OPCs were assessed by flow cytometry. Osteogenic potential was determined in two-dimensional (2D) cultures as a function of alkaline phosphatase-specific activity and osteocalcin production. In addition, cells were seeded onto three-dimensional (3D) poly-?-caprolactone scaffolds and cultured under dynamic conditions; mineralization was quantified by micro-CT at 4, 8 and 12 weeks. Resveratrol increased the percentage of ASCs in the population (population%) and number of ASCs in both GM and OM, but increased only the number of OPCs in GM. In both media types resveratrol increased alkaline phosphatase activity and osteocalcin levels. In 3D cultures, resveratrol-treated cells significantly increased mineralized matrix volume at early time points. Resveratrol exerted a biphasic effect on adherent cells by enriching the ASC and OPC populations and enhancing osteogenic differentiation. Resveratrol pretreatment induced more mineralization at earlier time points and represents a clinically viable technique for orthopaedic and dental applications for autologous stem cell therapy. PMID:22467433

Erdman, Christopher P; Dosier, Christopher R; Olivares-Navarrete, Rene; Baile, Clifton; Guldberg, Robert E; Schwartz, Zvi; Boyan, Barbara D

2012-12-01

145

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

Science.gov (United States)

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.

González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

2009-01-01

146

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 o 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)

147

Greenhouse Gas Emission from In-situ Denitrifying Bioreactors  

Science.gov (United States)

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 studies have focused on the reactions and products of DNBRs and instead note NO3- reductions in outflows as evidence that this should be used to treat agricultural discharges. It is, however, critical to understand all of the potential impacts that this treatment solution may have, which means identifying processes and design specifications that may affect them. This study addresses this lack of mechanistic understanding of DNBRs by means of sampling for incomplete products. Results will quantify gaseous products and internal processes and present a more complete picture of the potential for widespread use of DNBRs.

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

2013-12-01

148

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

Directory of Open Access Journals (Sweden)

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.

E. González-Toril

2009-01-01

149

Short communication: Viability of culture organisms in honey-enriched acidophilus-bifidus-thermophilus (ABT)-type fermented camel milk.  

Science.gov (United States)

The aim of this research was to monitor the survival during refrigerated storage of Lactobacillus acidophilus LA-5 (A), Bifidobacterium animalis ssp. lactis BB-12 (B), and Streptococcus thermophilus CHCC 742/2130 (T) in cultured dairy foods made from camel and, for comparison, cow milks supplemented with black locust (Robinia pseudoacacia L.) honey and fermented by an acidophilus-bifidus-thermophilus (ABT)-type culture. Two liters of dromedary camel milk and 2 L of cow milk were heated to 90 °C and held for 10 min, then cooled to 40 °C. One half of both types of milk was fortified with black locust honey at the rate of 5.0% (wt/vol), whereas the other half was devoid of honey and served as a control. The camel and cow milks with and without honey were subsequently inoculated with ABT-5 culture and were fermented at 37 °C until a pH value of 4.6 was reached. Thereafter, the probiotic fermented milks were cooled to 15 °C in ice water and were each separated into 18 fractions that were transferred in sterile, tightly capped centrifuge tubes. After 24 h of cooling at 8 °C (d 0), the samples were stored at refrigeration temperature (4 °C). Three tubes of all 4 products (i.e., fermented camel and cow milks with and without honey) were taken at each sampling time (i.e., following 0, 7, 14, 21, 28, and 35 d of storage), and the counts of characteristic microorganisms and those of certain spoilage microbes (yeasts, molds, coliforms, Escherichia coli) were enumerated. The entire experimental program was repeated twice. The results showed that addition of black locust honey at 5% to heat-treated camel and cow milks did not influence the growth and survival of starter streptococci during production and subsequent refrigerated storage of fermented ABT milks. In contrast, honey improved retention of viability of B. animalis ssp. lactis BB-12 in the camel milk-based product during storage at 4 °C up to 5 wk. No spoilage organisms were detected in any of the samples tested in this study. In conclusion, supplementation of cultured dairy foods, especially those made from camel milk, with honey is recommended because honey is a healthy natural sweetener with a variety of beneficial microbiological, nutritional, and sensory properties. PMID:25151879

Varga, L; Süle, J; Nagy, P

2014-11-01

150

INHIBITION OF ALKYLBENZENE BIODEGRADATION UNDER DENITRIFYING CONDITIONS BY USING THE ACETYLENE BLOCK TECHNIQUE  

Science.gov (United States)

Addition of acetylene to microcosms simultaneously amended with nitrate and alkylbenzenes resulted in inhibition of the rate of alkylbenzene biodegradation under denitrifying conditions. oluene, xylenes, and 1,2,4-trimethylbenzene were recalcitrant, whereas ethylbenzene was degra...

151

BIODEGRADATION OF AROMATIC COMPOUNDS UNDER MIXED OXYGEN/DENITRIFYING CONDITIONS: A REVIEW  

Science.gov (United States)

Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Many aromatic hydrocarbons degrade very slowly or not at all under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen, and denitrifying bacteria...

152

Non-cultured adipose-derived CD45- side population cells are enriched for progenitors that give rise to myofibres in vivo.  

Science.gov (United States)

Side population (SP) cells are highly able to exclude the Hoechst 33342 dye through membrane transporters, a feature associated with cell immaturity and therefore proposed as a marker of stem cells. Herein we demonstrate that the adipose tissue derived stromal vascular fraction (SVF) contains a novel population of non-haematopoietic "side population" (SPCD45(-)) cells. Simultaneous qRT-PCR of 64 genes revealed that the freshly isolated SPCD45(-) was highly enriched for cells expressing genes related to stem cells, the Notch pathway, and early vascular precursors. Notably, the expression of smooth muscle actin, C-met and Cd34 together with Angpt2, Flk1, VE-cadherin, and Cd31 suggested a phenotypic resemblance to pericytes and aorta-derived mesoangioblasts. Recent evidence suggests that cells residing within the vascular niche may participate in regeneration of skeletal muscle and although skeletal muscle repair mainly relies on the satellite cell, several reports have shown that vessel-associated cells may adopt a myogenic phenotype when exposed to a muscle environment. In accordance with these findings, we also observed in vitro myogenic specification of SPCD45(-) cells when cocultured with myoblasts. Furthermore, immediate intramuscular engraftment of non-cultured SPCD45(-) cells gave rise to myofibres and cells lining blood vessels, whereas the SVF only provided donor derived mononuclear cells. We therefore conclude that the SPCD45(-) fraction of adipose-derived SVF is enriched for cells expressing vascular associated markers and that the myogenic differentiation potential of these cells does not depend on prior in vitro expansion. PMID:18647602

Andersen, Ditte C; Schrøder, Henrik D; Jensen, Charlotte H

2008-10-01

153

Nitrogen removal from micro-polluted reservoir water by indigenous aerobic denitrifiers.  

Science.gov (United States)

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 3.01%, with no nitrite accumulation in either system. Our results show that aerobic denitrifying bacteria remain highly active after domestication and demonstrate the applicability of such organisms in the bioremediation of oligotrophic ecosystems. PMID:25867475

Huang, Ting-Lin; Zhou, Shi-Lei; Zhang, Hai-Han; Zhou, Na; Guo, Lin; Di, Shi-Yu; Zhou, Zi-Zhen

2015-01-01

154

Methyl t-Butyl Ether Mineralization in Surface-Water Sediment Microcosms under Denitrifying Conditions  

OpenAIRE

Mineralization of [U-14C]methyl t-butyl ether (MTBE) to 14CO2 without accumulation of t-butyl alcohol (TBA) was observed in surface-water sediment microcosms under denitrifying conditions. Methanogenic activity and limited transformation of MTBE to TBA were observed in the absence of denitrification. Results indicate that bed sediment microorganisms can effectively degrade MTBE to nontoxic products under denitrifying conditions.

Bradley, Paul M.; Chapelle, Francis H.; Landmeyer, James E.

2001-01-01

155

Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water. I. Water hyacinth, water lettuce, and pennywort  

Energy Technology Data Exchange (ETDEWEB)

Seasonal growth characteristics and biomass yield potential of 3 floating aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated in central Florida's climatic conditions. Growth cycle (growth curve) of the plants was found to be complete when maximum plant density was reached and no additional increase in growth was recorded. Biomass yield per unit area and time was found to be maximum in the linear phase of the growth curve; plant density in this phase was defined as operational plant density, a density range in which a biomass production system is operated to obtain the highest possible yields. Biomass yields were found to be 106, 72, and 41 t (dry wt) ha/sup -1/ yr/sup -1/, respectively, for water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), and pennywort (Hydrocotyle umbellata). Operational plant density was found to be in the range of 500-2,000 g dry wt m/sup -2/ for water hyacinth, 200-700 g dry wt m/sup -2/ for water lettuce, and 250-650 g dry wt m/sup -2/ for pennywort. Seasonality was observed in growth rates but not in operational plant density. Specific growth rate (% increase per day) was found to maximum at low plant densities and decreased as the plant density increased. Results show that water hyacinth and water lettuce can be successfully grown for a period of about 10 mo, while pennywort, a cool season plant, can be integrated into water hyacinth/water lettuce biomass production system to obtain high yields in the winter.

Reddy, K.R.; DeBusk, W.F.

156

Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water. I. Water hyacinth, water lettuce, and pennywort  

Energy Technology Data Exchange (ETDEWEB)

Seasonal growth characteristics and biomass yield potential of 3 floating aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated in central Florida's climatic conditions. Growth cycle (growth curve) of the plants was found to be complete when maximum plant density was reached and no additional increase in growth was recorded. Biomass yield per unit area and time was found to be maximum in the linear phase of the growth curve; plant density in this phase was defined as ''operational plant density,'' a density range in which a biomass production system is operated to obtain the highest possible yields. Biomass yields were found to be 106, 72, and 41 t(dry wt) ha/sup -1/yr/sup -1/, respectively, for water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), and pennywort (Hydrocotyle umbellata). Operational plant density was found to be in the range of 500-2000 g dry wt m/sup -2/ for water hyacinth, 200-700 g dry wt m/sup -2/ for water lettuce, and 250-650 g dry wt/sup -2/ for pennywort. Seasonality was observed in growth rates but not in operational plant density. Specific growth rate (% increase per day) was found to maximum at low plant densities and decreased as the plant density increased. Results show that water hyacinth and water lettuce can be successfully grown for a period of about 10 mo, while pennywort, a cool season plant, can be integrated into water hyacinth/water lettuce biomass production system to obtain high yields in the winter.

Reddy, K.R.; DeBusk, W.F.

157

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

Science.gov (United States)

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 zone, to get an insight for insurance values.

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

2012-04-01

158

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)

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.)

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

159

Comparing spatial and temporal dynamics of anammox and denitrifying communities at Cape Fear River Estuary and New River Estuary, North Carolina  

Science.gov (United States)

Anaerobic ammonium oxidation (anammox) and denitrification are two main microbial processes capable of removing fixed nitrogen by conversion into a gaseous species. Both microbial processes are known to occur in anoxic estuarine sediments and are capable of remediating excess nitrogen loadings from anthropogenic activities. In order to understand the importance of anammox and denitrification in estuarine ecosystems, we investigated both processes in two different estuaries of North Carolina to compare sedimentary nitrogen removal capacity and to identify key players of N2 production pathways. Both Cape Fear River Estuary (CFRE) and New River Estuary (NRE) are highly enriched with nitrogen from anthropogenic sources in spite of distinct geomorphological and geochemical characteristics. We conducted seasonal samplings to collect sediments across transects at fifteen stations along each estuary. 15N tracer techniques were used to measure spatial and temporal variations of N2 production by denitrification and anammox in estuarine sediments. Molecular analysis of nitrous oxide reductase (nosZ) and hydrazine oxidase (hzo) genes was conducted to examine community structures of denitrifying and anammox bacteria, respectively. Denitrification was found to be the dominant N2 production processes in both estuaries. Anammox contributed up to 19% and 15 % of total N2 productions in the CFEE and the NRE, respectively. Phylogenetic analysis of hzo genes identified that the anammox bacteria at both estuaries are closely associated with five known genera in the order Brocadiales. Anammox communities at the CFRE showed biogeographical distribution along the estuarine gradients while high seasonal variations were observed in the NRE communities. Spatial and temporal variations of denitrifying communities at both estuaries were also found based on nosZ gene analysis. Multivariate analysis was conducted to define key biogeochemical parameters influencing the community dynamics and activities of anammox and denitrifying bacteria in these ecosystems. Thus, this study reveals the importance of community structure to its function, as well as estimates and compares potential N removal capacity in two geologically distinct estuarine ecosystems.

Lisa, J. A.; Hirsch, M. D.; Duernberger, K. A.; Tobias, C. R.; Song, B.

2010-12-01

160

Isolation and characterization of a mesophilic heavy-metals-tolerant sulfate-reducing bacterium Desulfomicrobium sp. from an enrichment culture using phosphogypsum as a sulfate source  

International Nuclear Information System (INIS)

A sulfate-reducing bacterium, was isolated from a 6 month trained enrichment culture in an anaerobic media containing phosphogypsum as a sulfate source, and, designated strain SA2. Cells of strain SA2 were rod-shaped, did not form spores and stained Gram-negative. Phylogenetic analysis of the 16S rRNA gene sequence of the isolate revealed that it was related to members of the genus Desulfomicrobium (average sequence similarity of 98%) with Desulfomicrobium baculatum being the most closely related (sequence similarity of 99%). Strain SA2 used thiosulfate, sulfate, sulfite and elemental sulfur as electron acceptors and produced sulfide. Strain SA2 reduced sulfate contained in 1-20 g/L phosphogypsum to sulfide with reduction of sulfate contained in 2 g/L phosphogypsum being the optimum concentration. Strain SA2 grew with metalloid, halogenated and non-metal ions present in phosphogypsum and with added high concentrations of heavy metals (125 ppm Zn and 100 ppm Ni, W, Li and Al). The relative order for the inhibitory metal concentrations, based on the IC50 values, was Cu, Te > Cd > Fe, Co, Mn > F, Se > Ni, Al, Li > Zn

161

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

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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.

Daniel L. Haus

2014-09-01

162

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

Science.gov (United States)

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. PMID:25082219

Haus, Daniel L; Nguyen, Hal X; Gold, Eric M; Kamei, Noriko; Perez, Harvey; Moore, Harry D; Anderson, Aileen J; Cummings, Brian J

2014-09-01

163

Feeding glycerol-enriched yeast culture improves performance, energy status, and heat shock protein gene expression of lactating Holstein cows under heat stress.  

Science.gov (United States)

This study was conducted to evaluate the effects of supplemental common yeast culture (CY) and glycerol-enriched yeast culture (GY) on performance, plasma metabolites, antioxidant status, and heat shock protein 70 (HSP70) mRNA expression in lactating Holstein cows under heat stress. During summer months, 30 healthy multiparous lactating cows (parity 3.25 ± 0.48; 60 ± 13 d in milk [DIM]; 648 ± 57 kg BW; an average milk yield of 33.8 ± 1.6 kg/d) were blocked by parity, previous milk yield, and DIM and randomly allocated to 3 dietary treatments: no supplemental yeast culture (Control), 1 L/d of CY (33.1 g yeast) per cow, and 2 L/d of GY (153.2 g glycerol and 31.6 g yeast) per cow. During the 60-d experiment, values of air temperature and relative humidity inside the barn were recorded hourly every 3 d to calculate temperature-humidity index (THI). Weekly rectal temperatures (RT) and respiration rates and daily DMI and milk yield were recorded for all cows. Milk and blood samples were taken twice monthly, and BW and BCS were obtained on d 0 and 60. In this experiment, THI values indicated cows experienced a moderate heat stress. Cows supplemented with CY and GY had greater yields of milk, energy-corrected milk and milk fat, and milk fat percent but lower HSP70 mRNA expression in peripheral blood lymphocytes than Control cows (P yield and erythrocyte glutathione, and reduce plasma urea nitrogen compared with Control. Lower plasma NEFA concentration and HSP70 mRNA expression in peripheral blood lymphocytes (P < 0.05) and tendencies towards greater plasma glucose concentration (P = 0.11) but less BW loss (P = 0.14) were observed in GY relative to CY cows. In conclusion, either CY or GY supplementation partially mitigated the negative effects of heat stress on performance and HSP70 mRNA expression of lactating cows, and GY supplementation provided additional improvements in energy status and HSP70 gene expression of lactating cows. PMID:24668959

Liu, J; Ye, G; Zhou, Y; Liu, Y; Zhao, L; Liu, Y; Chen, X; Huang, D; Liao, S F; Huang, K

2014-06-01

164

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 demonstratemes 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.

165

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

Czech Academy of Sciences Publication Activity Database

Ro?. 56, ?. 3 (2011), s. 230-235. ISSN 0015-5632 R&D Projects: GA MŠk LC06066; GA AV ?R IAA600660605 Institutional research plan: CEZ:AV0Z60660521 Keywords : pH * denitrifying enzyme activity * pasture soil s Subject RIV: EH - Ecology, Behaviour Impact factor: 0.677, year: 2011

?uhel, Ji?í; Šimek, Miloslav

2011-01-01

166

[NO3-/NO2- inhibits sulfate-reducing activity of the enrichment culture of sulfate-reducing prokaryotes from an off-shore oil reservoir at Bohai Bay, China].  

Science.gov (United States)

Long-term injection of sulfate-rich water into oil reservoirs stimulates the proliferation of sulfate-reducing prokaryotes (SRP) therein and results in production of a great amount of H2S, leading to souring in oil reservoirs and related environmental problems. In this study, we first, using modified API RP 38 medium, enriched SRP present in production water from a producing well at Bohai Bay, China, and then examined the inhibitory effects of nitrate or nitrite on sulfate reduction activity of the SRP. Results showed that the enriched SRP culture exhibited a high sulfate reduction activity as indicated by a sulfate-reducing rate of 10.4 mmol SO4(2-) x d(-1) x g(-1) dry cell. In presence of 0.4, 0.8, 1.8, and 4.2 mmol x L(-1) nitrate, sulfate reduction was inhibited for 5, 9, 20, and over 35 days, respectively. With the addition of 0.6, 0.9, 1.4, 2.6 and 4.6 mmol x L(-1) of nitrite, the inhibitory period lasted 3, 12, 22, and over 39 days, respectively. The SRP enrichment culture could dissimilatorily reduce nitrate to ammonium. When sulfate, nitrate and nitrite coexisted, nitrate or nitrite was preferentially used over sulfate as electron acceptor by the enriched SRP. This competitive use of electron acceptor and the strong inhibitory effect of nitrite possibly accounted for the suppression of nitrate and nitrite on the sulfate-reducing activity of the enriched SRP cultures from offshore oil reservoir at Bohai Bay. PMID:25509091

Liu, Hong-Yu; Shi, Rong-Jiu; Zhang, Ying; Shi, Zhen-Guo; Zhang, Ying-Yue; Yu, Liang; Zhang, Xiao-Bo; Tan, Tao

2014-08-01

167

Improvement of sensitivity for Mycobacterium avium subsp. paratuberculosis (MAP) detection in bovine fecal samples by specific duplex F57/IC real-time and conventional IS900 PCRs after solid culture enrichment.  

Science.gov (United States)

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Johne's disease in ruminants and a probable pathogen of Crohn's disease in humans. Accurate, cost-effective, and time-relevant diagnostics are the basis for efficient control programs. This study was conducted as an attempt to re-evaluate MAP detection improvement by coupling solid media enrichment to a more specific IS900 conventional PCR and a very specific F57/IC real-time PCR. In a spiking experiment, we investigated the improvement of molecular-based MAP detection in feces after a culture-based enrichment step into Herrold's egg yolk media with mycobactin J (HEYM-MJ) for different time intervals, when compared to traditional culture. Detection limit of culture was 0.33?×?10(4) bacteria?×?g(-1) (33 CFU g(-1)), while that of IS900 PCR when coupled with an enrichment step for 2, 4, and 6 weeks was 0.33?×?10(5) (0.33?×?10(3) CFU g(-1)), 0.33?×?10(4) (33 CFU g(-1)), and 33 (>3.3 CFU g(-1)) bacteria?×?g(-1), respectively. Whereas the detection limits of F57/IC real-time PCR after the enrichment step for the same time intervals were 0.33?×?10(5) (0.33?×?10(3) CFU g(-1)), 0.33?×?10(3) (3.3 CFU g(-1)), and 33 (>3.3 CFU g(-1)) bacteria?×?g(-1), respectively. Altogether, enrichment of bovine fecal samples into solid media increased the sensitivity of specific molecular detection of MAP using IS900 conventional PCR and duplex F57/IC real-time PCR and offers an expedited and accurate alternative for MAP detection in bovine feces. Validation of these results is further recommended using field bovine fecal samples. PMID:25716216

Fawzy, Ahmad; Eisenberg, Tobias; El-Sayed, Amr; Zschöck, Michael

2015-04-01

168

Phosphorus removal and N?O production in anaerobic/anoxic denitrifying phosphorus removal process: long-term impact of influent phosphorus concentration.  

Science.gov (United States)

This study was conducted to investigate the long-term impact of influent phosphorus concentration on denitrifying phosphorus removal and N2O production during denitrifying phosphorous removal process. The results showed that, denitrifying phosphate accumulating organisms (DPAOs) could become dominant populations quickly in anaerobic/anoxic SBR by providing optimum cultivating conditions, and the reactor performed well for denitrifying phosphorus removal. The influent phosphorus concentration significantly affected anaerobic poly-?-hydroxyalkanoates (PHA) synthesis, denitrifying phosphorus removal, and N2O production during the denitrifying phosphorus removal process. As the influent phosphorus concentration was more than 20 mg L(-1), the activity of DPAOs began to be inhibited due to the transformation of the available carbon source type. Meanwhile, N2O production was inhibited with the mitigation of anoxic NO2(-)-N accumulation. Adoption of a modified feeding could enhance denitrifying phosphorus removal and inhibit N2O production during denitrifying phosphorous removal processes. PMID:25541320

Wang, Zhen; Meng, Yuan; Fan, Ting; Du, Yuneng; Tang, Jie; Fan, Shisuo

2015-03-01

169

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

170

Metaproteogenomic analysis of a sulfate-reducing enrichment culture reveals genomic organization of key enzymes in the m-xylene degradation pathway and metabolic activity of proteobacteria.  

Science.gov (United States)

This study aimed to ascertain the functional and phylogenetic relationships within an m-xylene degrading sulfate-reducing enrichment culture, which had been maintained for several years in the laboratory with m-xylene as the sole source of carbon and energy. Previous studies indicated that a phylotype affiliated to the Desulfobacteraceae was the main m-xylene assimilating organism. In the present study, genes and gene products were identified by a metaproteogenomic approach using LC-MS/MS analysis of the microbial community, and 2426 peptides were identified from 576 proteins. In the metagenome of the community, gene clusters encoding enzymes involved in fumarate addition to a methyl moiety of m-xylene (nms, bss), as well as gene clusters coding for enzymes involved in modified beta-oxidation to (3-methyl)benzoyl-CoA (bns), were identified in two separate contigs. Additionally, gene clusters containing homologues to bam genes encoding benzoyl-CoA reductase (Bcr) class II, catalyzing the dearomatization of (3-methyl)benzoyl-CoA, were identified. Time-resolved protein stable isotope probing (protein-SIP) experiments using (13)C-labeled m-xylene showed that the respective gene products were highly (13)C-labeled. The present data suggested the identification of gene products that were similar to those involved in methylnaphthalene degradation even though the consortium was not capable of growing in the presence of naphthalene, methylnaphthalene or toluene as substrates. Thus, a novel branch of enzymes was found that was probably specific for anaerobic m-xylene degradation. PMID:25156802

Bozinovski, Dragana; Taubert, Martin; Kleinsteuber, Sabine; Richnow, Hans-Hermann; von Bergen, Martin; Vogt, Carsten; Seifert, Jana

2014-10-01

171

Differential isotopic fractionation during Cr(VI) reduction by an aquifer-derived bacterium under arobic versus denitrifying conditions  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-02-01

172

[Identification and denitrification characteristics of a psychrotolerant facultative basophilic aerobic denitrifier].  

Science.gov (United States)

An aerobic denitrifier was isolated from the activated sludge of landfill leachate through traditional microbiological methods. Based on its morphological feature, physiological and biochemical properties, and 16S rDNA sequence analysis, this strain was identified as Pseudomonas sp., named as GL19 with an accession number of KC710974 in GenBank. Its aerobic denitrification characteristics and nitrification function were studied to show that the factors including carbon source, C/N, pH and cultivation temperature were important for denitrification. The optimized condition for aerobic denitrification was as follows: sodium citrate as the carbon resource, C/N no less than 15, pH of 6-10, DO of 4.8-7.7 mg x L(-1), culture temperature of 15-34 degrees C and the initial nitrate nitrogen of 140 mg x L(-1). Combining these conditions, the removal rate of nitrate nitrogen and average removal rate of TN reached 100% and 96.5%, respectively, without the accumulation of nitrite nitrogen. The strain had the capability to utilize nitrite nitrogen or ammonia nitrogen to achieve high nitrogen removal efficiency: the nitrite nitrogen removal rate reached 100% in 20 hours with an initial nitrite nitrogen of 140 mg x L(-1); the ammonia nitrogen was efficiently removed from 280 mg x L(-1) to 3.11 mg x L(-1) in 28 hours with the removal rate of up to 98.9%. These results suggested that strain GL19 with the function of cold resistance and highly effective aerobic denitrification could achieve simultaneous nitrification and denitrification. Hence, GL19 could have high potential in practical wastewater treatment in winter of south area. PMID:25158516

Wang, Zhao-Yang; Chen, Guo-Yao; Jiang, Ke; Xu, Pei-Ya

2014-06-01

173

Effects of plant biomass on denitrifying genes in subsurface-flow constructed wetlands.  

Science.gov (United States)

The effect of Typha latifolia and its litter on density and abundance of three denitrifying genes (nirS, nirK and nosZ) were investigated in six laboratory-scale SSF CW microcosms. Results showed that the copy numbers of nirS, nirK and nosZ in wetland microcosms were ranged between 10(8)-10(9), 10(6)-10(7) and 10(7)-10(8) copies g(-1), respectively. The presence of T. latifolia encouraged the growth of nirK containing bacteria. Addition of cattail litter could greatly stimulate the growth of bacteria containing nirS and nosZ gene. Path analysis illustrated that the presence of plants and litters had no significant direct impact on denitrifying genes, while it affected the denitrifying genes via alteration of dissolved oxygen and carbon sources. PMID:24565872

Chen, Yi; Wen, Yue; Zhou, Qi; Vymazal, Jan

2014-04-01

174

Concurrent Activity of Anammox and Denitrifying Bacteria in the Black Sea  

Directory of Open Access Journals (Sweden)

Full Text Available After the discovery of ANaerobic AMMonium OXidation (anammox in the Black Sea in 2003, the role of heterotrophic denitrification as the main marine pathway for fixed N loss was questioned. A 3 part, 15 month time series investigating Black Sea nitrite reductase (nirS mRNA transcripts at a single location was conducted in order to better understand the activity of anammox and denitrifying bacteria. Here we show that both of these groups were active, as well as being concurrent in the lower suboxic zone over this time span. Their distributions, however, were fundamentally different; denitrification expression was much more variable. Depth profiles covering the suboxic zone showed that the four groups of anammox-type sequences were expressed consistently in the lower suboxic zone, and were consistent with anammox 16S rDNA gene profiles. By contrast, denitrifier-type nirS sequence groups were mixed; half of the groups exhibited consistent expression in the lower suboxic zone, while others varied between season and depth. Co-occurrence of both anammox and denitrifier expression was common and ongoing. Both types of transcripts were also found in samples with low concentrations of sulfide ( >2 ?M. 6 major groups of denitrifier-type nirS transcripts were identified, making these transcripts more diverse than previous DNA clone libraries. Several groups of denitrifier-type nirS transcripts were closely related to sequences from the Baltic Sea. An increase in denitrifier-type nirS transcript diversity and depth range in October 2007 corresponded to an increase in mixed layer net community productivity as measured by O2/Ar gas ratios, as well as to an increase in N2 concentrations in the upper suboxic zone. Taken together, the variations in expression patterns between anammox and denitrification provide one explanation as to how near instantaneous rate measurements, such as isotope spike experiments, may regularly detect anammox activity but underreport denitrification.

JohnB.Kirkpatrick

2012-07-01

175

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 sensitiverS 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.

176

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

Science.gov (United States)

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. PMID:25580463

Linchangco, Richard

2014-01-01

177

Post cold-storage conditioning time affects soil denitrifying enzyme activity  

DEFF Research Database (Denmark)

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 in DEA following cold storage, suggesting a need to consider conditioning time when planning and interpreting results.

Chirinda, Ngoni; Olesen, JØrgen E

2011-01-01

178

Assessing the impact of denitrifier-produced nitric oxide on other bacteria.  

Science.gov (United States)

A series of experiments was undertaken to learn more about the impact on other bacteria of nitric oxide (NO) produced during denitrification. The denitrifier Rhodobacter sphaeroides 2.4.3 was chosen as a denitrifier for these experiments. To learn more about NO production by this bacterium, NO levels during denitrification were measured by using differential mass spectrometry. This revealed that NO levels produced during nitrate respiration by this bacterium were in the low muM range. This concentration of NO is higher than that previously measured in denitrifiers, including Achromobacter cycloclastes and Paracoccus denitrificans. Therefore, both 2.4.3 and A. cycloclastes were used in this work to compare the effects of various NO levels on nondenitrifying bacteria. By use of bacterial overlays, it was found that the NO generated by A. cycloclastes and 2.4.3 cells during denitrification inhibited the growth of both Bacillus subtilis and R. sphaeroides 2.4.1 but that R. sphaeroides 2.4.3 caused larger zones of inhibition in the overlays than A. cycloclastes. Both R. sphaeroides 2.4.3 and A. cycloclastes induced the expression of the NO stress response gene hmp in B. subtilis. Taken together, these results indicate that there is variability in the NO concentrations produced by denitrifiers, but, irrespective of the NO levels produced, microbes in the surrounding environment were responsive to the NO produced during denitrification. PMID:16517672

Choi, Peter S; Naal, Zeki; Moore, Charles; Casado-Rivera, Emerilis; Abruña, Hector D; Helmann, John D; Shapleigh, James P

2006-03-01

179

Enriched Uranium  

Science.gov (United States)

This Wikipedia website provides information about the various concentrations of uranium used for different applications. Topics include a brief description of the grades of uranium and methods of isotope separation. There are also links to other aspects of uranium enrichment and related information. This information lays the foundation for informed discussion about the potential of nuclear energy and the risks of nuclear proliferation.

Wikipedia

180

Uranium enrichment  

International Nuclear Information System (INIS)

In view of greatly reduced increase forecasts for the nuclear industry there is a worldwide over-capacity on the enrichment market and until the 1990's this market will therefore to an increasing extent become a buyer's market. In order to meet this challenge the US DOE, after a brief but intensive study and assessment of the enrichment techniques at present being developed, reached the decision at the beginning of June 1985 that the laser isotope separation technique was at once to be promoted exclusively and to be developed to industrial perfection. According to present plans the first large industrial plant is to reach full production by 1995. Above all, the advantages to be gained when using this laser technique in the reprocessing of spent fuel rods and in armament production no doubt played a part in influencing the American decision. Officially, the reasons given for this decision are advantages as regards costs both for research and development and also for subsequent operation of the plant in question. The paper discusses the possible effects of the new laser techniques. These are, in particular: a higher degree of depletion as a result of the higher separation factor and thus better utilisation, i.e. by about one-third, of the natural uranium used and further depletion of the quantities of UF6 which have already been moderately depleted, although this further depletion is limited because the laser enrichment capacity is only built up slowly; impront capacity is only built up slowly; improvement in the reprocessing of spent fuel elements. The first reactions from overseas show that considerable interest is evinced there. France also intends to establish a laser enrichment capacity, and Japan has already sent a team of engineers to the USA as a fact finding mission. (orig./HP)

181

Uranium enrichment  

International Nuclear Information System (INIS)

This chapter discusses the development of uranium enrichment processes. In the introduction there is a brief history of uranium enrichment, followed by a summary of the criteria used for the assessment of an isotope separation process, e.g. the separation factor, separative power, and the power consumption of a separating element. This is followed by a discussion of the two main processes used, i.e. gaseous diffusion and centrifugation. The reason for the change from diffusion to centrifugation in the UK, mainly on power costs, is discussed. The development potential of centrifuges is also assessed. Other processes which have been developed up to pilot stage are described, e.g. the Becker jet nozzle and the South African process. This is followed by a description of some plasma-based methods. The next topic is concerned with chemical exchange methods and an attempt is made to assess their potential in the enrichment scene from published information. This chapter concludes with a discussion of the advanced laser isotope-separation methods. The two approaches, i.e. the atomic and the molecular routes are discussed again using published information. This information is insufficient to give a complete assessment of the methods, especially the molecular route, but is enough to give indications of their potential

182

ANAEROBIC BIODEGRADATION OF O-, M- AND P-CRESOL BY SULFATE-REDUCING BACTERIAL ENRICHMENT CULTURES OBTAINED FROM A SHALLOW ANOXIC AQUIFER  

Science.gov (United States)

Sulfate-reducing bacterial enrichments were obtained from a shallow anoxic aquifer for their ability to metabolize either o-, or p-cresol. C/MS and simultaneous adaptation experiments suggested that the anaerobic decomposition of p-cresol proceeds by the initial oxidation of the ...

183

RELATIONSHIP BETWEEN THE CONCENTRATION OF DENITRIFIERS AND PSEUDOMONAS SPP. IN SOILS: IMPLICATIONS FOR BTX BIOREMEDIATION (R823420)  

Science.gov (United States)

Aquifer microcosms were used to investigate the effect of stimulating denitrification on microbial population shifts and BTX degradation potential. Selective pressure for facultative denitrifiers was applied to a treatment set by feeding acetate and nitrate, and cycling electr...

184

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

Energy Technology Data Exchange (ETDEWEB)

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 hydraulic retention time is an efficient way to make the reactor tolerating high S{sup 2?} loadings. The proposed model properly described the kinetic behaviors of DSR processes over wide parametric ranges and which can offer engineers with basis to optimize bioreactor operation to improve the treatment capacity.

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

185

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

International Nuclear Information System (INIS)

Graphical abstract: Model evaluation applied to case study 1: (A-G) S2?, NO3?-N, NO2?-N, and Ac?-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?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 (S2?), nitrate (NO3?) and acetate (Ac?) 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 S2? concentration, S2?/NO3?-N ratio and Ac?-C/NO3?-N ratio. Simulation supported that the heterotrophic denitratation step (NO3? reduction to NO2?) was inhibited by S2? compared with the denitritation step (NO2? reduction to N2). Also, the S2? oxidation by autotrophic denitrifiers was shown two times lower in rate with NO2? as electron acceptor than that with NO3? as electron acceptor. NO3? reduction by autotrophic denitrifiers occurs 3–10 times slower when S0 participates as final electron donor compared to the S2?-driven pathway. Model simulation on continuous-flow DSR reactor suggested that the adjustment of hydraulic retention time is an efficient way to make the reactor tolerating high S2? loadings. The proposed model properly described the kinetic behaviors of DSR processes over wide parametric ranges and which can offer engineers with basis to optimize bioreactor operation to improve the treatment capacity

186

Diversity and Distribution of nirK-Harboring Denitrifying Bacteria in the Water Column in the Yellow River Estuary  

OpenAIRE

We investigated the diversity and community composition of denitrifying bacteria in surface water from the Yellow River estuary. Our results indicated that the diversity of the denitrifying community in freshwater based on the nirK gene was higher than that in seawater. Furthermore, phylogenetic analysis suggested that the bacteria community could be distributed into eight clusters (Clusters I to VIII). Redundancy analysis (RDA) revealed that community compositions were related to multiple en...

Li, Jing; Wei, Guangshan; Wang, Ningxin; Gao, Zheng

2014-01-01

187

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

OpenAIRE

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...

Barak, Yoram; Rijn, Jaap

2000-01-01

188

Inhibition of alkylbenzene biodegradation under denitrifying conditions by using the acetylene block technique.  

OpenAIRE

Addition of acetylene to microcosms simultaneously amended with nitrate and alkylbenzenes resulted in inhibition of the rate of alkylbenzene biodegradation under denitrifying conditions. Toluene, xylenes, and 1,2,4-trimethylbenzene were recalcitrant, whereas ethylbenzene was degraded at a slower rate than usual. Benzene was not degraded in either case. Addition of acetylene to microcosms preexposed to nitrate and alkylbenzenes produced similar inhibition. These data indicate that the activiti...

Hutchins, S. R.

1992-01-01

189

Genetic Diversity of Benzoyl Coenzyme A Reductase Genes Detected in Denitrifying Isolates and Estuarine Sediment Communities  

OpenAIRE

Benzoyl coenzyme A (benzoyl-CoA) reductase is a central enzyme in the anaerobic degradation of organic carbon, which utilizes a common intermediate (benzoyl-CoA) in the metabolism of many aromatic compounds. The diversity of benzoyl-CoA reductase genes in denitrifying bacterial isolates capable of degrading aromatic compounds and in river and estuarine sediment samples from the Arthur Kill in New Jersey and the Chesapeake Bay in Maryland was investigated. Degenerate primers were developed fro...

Song, Bongkeun; Ward, Bess B.

2005-01-01

190

Direct enrichment of perchlorate-reducing microbial community for efficient electroactive perchlorate reduction in biocathodes.  

Science.gov (United States)

Biological reduction of perchlorate (ClO??) has emerged as a promising solution for the removal of perchlorate in contaminated water and soils. In this work, we demonstrate a simple process to enrich perchlorate-reducing microbial communities separately using acetate as electron donor and the municipal aerobic membrane bioreactor sludge as inoculum. Inoculation of cathodes in microbial fuel cells (MFCs) with these enrichments, and further electrochemical enrichment at constant resistance operation of the MFCs, led to perchlorate-reducing biocathodes with peak reduction rates of 0.095 mM/day (2 mg/m²/day). Analysis of the microbial diversity of perchlorate-reducing biocathodes using PCR-DGGE revealed unique community profiles when compared to the denitrifying biocathode communities. More importantly, the total time taken for enrichment of the electroactive communities was reduced from several months reported previously in literature to less than a month in this work. PMID:23925794

Mieseler, Maren; Atiyeh, Mays N; Hernandez, Hector H; Ahmad, Farrukh

2013-11-01

191

Start-up of granule-based denitrifying reactors with multiple magnesium supplementation strategies.  

Science.gov (United States)

In the present work, the effect of Mg(2+) supplementation on the start-up of a denitrification process and the granulation of denitrifying sludge was investigated in three upflow anaerobic sludge blanket (UASB) reactors. The reactors R1 and R2 were continuously and intermittently, respectively, supplied with 50 mg L(-1) Mg(2+), whereas R0 was used as the control. The nitrogen loading rate (NLR) and organic loading rate (OLR) gradually increased, and extremely high values were obtained (36.0 kgN m(-3) d(-1) and 216.0 kgCOD m(-3) d(-1), respectively). Granulation occurred in R1 first, but the reactor capacities were comparable. Suffering from starvation, the R0-R2 performances were comparable. At the end of the experiment, the average diameter of the granules in R0, R1, and R2 were 1.67, 1.72 and 1.68 mm, respectively, and the settling velocities of the granules in R1 and R2 were 1.14-fold the speed of R0. The specific denitrifying activity (SDA) of the sludge from the reactors supplied with Mg(2+) was greater than the reactor without Mg(2+). Intermittent Mg(2+) supplementation was identified as the best choice to be utilized to cultivate denitrifying granules, which was consistent with kinetic analysis. PMID:25837295

Chen, Hui; He, Li-Ling; Liu, An-Na; Guo, Qiong; Zhang, Zheng-Zhe; Jin, Ren-Cun

2015-05-15

192

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

Science.gov (United States)

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 ?-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

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

2014-01-01

193

Below-ground responses of loblolly pine and sweetgum in pure and mixed culture to CO[sub 2] enrichment, water and nutrient status  

Energy Technology Data Exchange (ETDEWEB)

To determine how below-ground processes are affected by CO[sub 2] under varied water and nutrient (nitrogen, N) regimes, loblolly pine and sweetgum seedlings were exposed to 350 ppm CO[sub 2] or 700 ppm CO[sub 2] in continuously-stirred tank reactors. Miniature stands (2.5 x 2.5 cm spacing) were raised in forest soil in 22-L pots for two accelerted growth cycles (42 wks. total). Three stand-types were raised: pine in monoculture, sweetgum in monoculture, and 50:50 mixtures of pine-sweetgum. Root growth responses (determined for 87 cm[sup 3] soil cores), differed according to stand type; sweetgum stands were more responsive to treatments than pine stands, and mixed stands of sweetgum were even more responsive than monocultures. At the end of the second growth cycle, root growth was generally increased by CO[sub 2]-enrichment (1.2 to 1.7-fold increase). Water and nitrogen effects were strong but varied in direction (increased or decreased root growth) according to stand type. Interactions of particular interest were those involving the influence of water and/or N on CO[sub 2] responses. The positive effect of CO[sub 2]-enrichment on root growth were consistently greater under water- or N-limited conditions for all stand types, and this pattern was most evident for sweetgum in mixture. For example, under water stress, CO[sub 2]-enrichment increased root length density (cm root/cm[sup 3] soil) of sweetgum by 74% and that of pine by 34%, whereas under high water, the increase was 32% for sweetgum and 10% for pine. This suggests an increased capacity of sweetgum to exploit a given soil volume, under elevated atmospheric CO[sub 2], as compared with pine.

Jifon, J.L.; Friend, A.L. (Mississippi State Univ. (United States)); Berrang, P. (USFS, Dry Branch, GA (United States)); Seiler, J.R.; Zedaker, S.M. (Forestry Dept, Blacksburg, VA (United States))

1993-06-01

194

Use of starter cultures of lactic acid bacteria and yeasts as inoculum enrichment for the production of gowé, a sour beverage from Benin  

DEFF Research Database (Denmark)

Lactobacillus fermentum, Weissella confusa, Kluyveromyces marxianus and Pichia anomala, previously isolated during natural fermentation of traditional gowé, were tested as inoculum enrichment for controlled fermentation of gowé. The final product was subjected to chemical analysis and sensory evaluation. Growth of the lactic acid bacteria (LAB) and yeasts were verified by determination of colony forming units (CFU) and molecular biology techniques. A significant decrease in pH from 6.1 to 3.3, with a concomitant increase in titratable acidity (11 to 60 g/kg as lactic acid, dry weight), was observed after 24 h of fermentation when LAB was used either alone or in combination with yeasts. The LAB count increased significantly from 6.1 to 9.4 log CFU/ml, while the yeast count remained constant throughout fermentation. Repetitive-polymerase chain reaction (rep-PCR) assays performed on isolates during the fermentation confirmed the dominance of the added LAB strains. Sensory evaluation revealed that the product fermented for 7 h with L. fermentum alone or in combination with K. marxianus was as acceptable as the traditional product normally obtained after a minimum of 24 h of fermentation. Consequently, gowé can be obtained by controlled fermentation, using L. fermentum as inoculum enrichment, in a small scale industry.  

Vieira-Dalodé, G.; Madodé, Y.E.

2008-01-01

195

Nutrient Cycles and Marine Microbes in a CO2-Enriched Ocean  

Directory of Open Access Journals (Sweden)

Full Text Available The ocean carbon cycle is tightly linked with the cycles of the major nutrient elements nitrogen, phosphorus, and silicon. It is therefore likely that enrichment of the ocean with anthropogenic CO2 and attendant acidification will have large consequences for marine nutrient biogeochemistry, and for the microbes that mediate many key nutrient transformations. The best available evidence suggests that the nitrogen cycle may respond strongly to higher CO2 through increases in global N2 fixation and possibly denitrification, as well as potential decreases in nitrification. These trends could cause nitrification to become a nitrogen cycle “bottleneck,” by increasing the flux of N2 fixed into ammonium while decreasing the fraction being oxidized to nitrite and nitrate. The consequences could include reduced supplies of oxidized nitrogen substrates to denitrifiers, lower levels of nitrate-supported new primary production, and expansion of the regenerated production system accompanied by shifts in current phytoplankton communities. The phosphorus and silicon cycles seem less likely to be directly affected by enhanced CO2 conditions, but will undoubtedly respond indirectly to changing carbon and nitrogen biogeochemistry. A review of culture experiments that examined the effects of increased CO2 on elemental ratios of phytoplankton suggests that for most cyanobacteria and eukaryotes, C:N and N:P ratios will either remain at Redfield values or increase substantially. Natural plankton community CO2 manipulation experiments show much more mixed outcomes, with both increases and decreases in C:N and N:P ratios reported at future CO2 levels. We conclude our review with projections of overall trends in the cycles of nitrogen, phosphorus, and silicon over the next century as they respond to the steady accumulation of fossil-fuel-derived CO2 in a rapidly changing ocean.

David A. Hutchins

2009-12-01

196

Effects of elevated CO2 on communities of denitrifying bacteria and methanogens in a temperate marsh microcosm.  

Science.gov (United States)

The effects of elevated CO(2) on soil bacterial community with upland vegetation have been widely studied, but limited information is available regarding responses of denitrifier and methanogen communities to elevated CO(2) in wetland ecosystems. Using restriction fragment length polymorphism (RFLP), terminal RFLP analysis, and real-time quantitative PCR, we compared communities of denitrifiers and methanogens in a laboratory-scale wetland system planted with one of three macrophytes, Typha latifolia, Scirpus lacustris, or Juncus effusus, after 110 days of incubation. Our study showed that elevated CO(2) could affect community structures of both denitrifiers and methanogens, each of which had a unique response pattern. In particular, elevated CO(2) shifted nirS-containing community with a unique structure irrespective of vegetation type. mcrA-containing community appeared to shift to community with unique types of hydrogenotrophs under elevated CO(2) conditions. The change of dissolved organic carbon driven by elevated CO(2) appeared to be related with the shift of both denitrifiers and methanogens. Overall, this study indicates that elevated CO(2) could change the community structure of denitrifiers and methanogens temporarily. These results also suggest a presence of stable dominant populations that were not substantially affected by changes in CO(2) concentration. PMID:22441572

Lee, Seung-Hoon; Kim, Seon-Young; Kang, Hojeong

2012-08-01

197

Primers for overlooked nirK, qnorB, and nosZ genes of thermophilic Gram-positive denitrifiers.  

Science.gov (United States)

Although efforts have been made the past few years, knowledge on genomic and phenotypic diversity and occurrence of the denitrification ability in Gram-positive bacteria are still fragmentary. Many environmental monitoring approaches have used nir, nor, and nos genes as marker genes for detection of denitrification or denitrifying bacteria. However, primers used in these methods often fail to detect the genes in specific bacterial taxa, such as Gram-positive denitrifiers. In this study, novel primer sets specifically targeting nirK, qnorB, and nosZ genes of the Firmicute genus Geobacillus were developed by genomic mining and tested in parallel with commonly used primers on a set of phylogenetically closely related denitrifying geobacilli. Novel nirK and qnorB sequences were recovered from all strains tested, whereas nosZ was detected in part of the strain set, which was in agreement with observed phenotypes. Interspecies and modest intraspecies variations in amplified fragment length polymorphism (AFLP) patterns were observed, verifying presence of genomic variation within the strain set. Our study shows that closely related Gram-positive denitrifiers may differ in denitrification phenotype and genotype. But foremost, novel primers targeting very divergent nirK, qnorB, and nosZ gene sequences of Gram-positive denitrifiers, are now available for cultivation-independent environmental surveys. PMID:24784780

Verbaendert, Ines; Hoefman, Sven; Boeckx, Pascal; Boon, Nico; De Vos, Paul

2014-07-01

198

Development of a Cell Culture Method To Isolate and Enrich Salmonella enterica Serotype Enteritidis from Shell Eggs for Subsequent Detection by Real-Time PCR?  

OpenAIRE

Salmonella enterica serotype Enteritidis is a major cause of nontyphoidal salmonellosis from ingestion of contaminated raw or undercooked shell eggs. Current techniques used to identify Salmonella serotype Enteritidis in eggs are extremely laborious and time-consuming. In this study, a novel eukaryotic cell culture system was combined with real-time PCR analysis to rapidly identify Salmonella serotype Enteritidis in raw shell eggs. The system was compared to the standard microbiological metho...

Day, J. B.; Basavanna, U.; Sharma, S. K.

2009-01-01

199

Regeneration of Ginger Plant from Callus Culture Through Organogenesis and Effect of CO2 Enrichment on the Differentiation of Regenerated Plant  

OpenAIRE

A efficient and systematic protocol for complete plant regeneration via shoot apical meristem culture has been developed for Zingiber officinale L. Callus was initiated from shoot-tip of young plant on MS-media supplemented with a combination of Naphthalene acetic acid (0.1 mg L-1) and Kinetin (1.0-2.0 mg L-1) and Indole-3-acetic acid (0.1 mg L-1) and 6-Benzylaminopurine (1.0-2.0 mg L-1). Maximum shoot differentiation from callus occurred on MS medium supplemented with Indole-3-acetic acid (0...

Muhammad Jamil; Jin Key Kim; Zahid Akram; Saif Ullah Ajmal; Eui Shik Rha

2007-01-01

200

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

Science.gov (United States)

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 ?. 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. PMID:25768227

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

2015-03-01

201

Genetic diversity of benzoyl coenzyme A reductase genes detected in denitrifying isolates and estuarine sediment communities.  

Science.gov (United States)

Benzoyl coenzyme A (benzoyl-CoA) reductase is a central enzyme in the anaerobic degradation of organic carbon, which utilizes a common intermediate (benzoyl-CoA) in the metabolism of many aromatic compounds. The diversity of benzoyl-CoA reductase genes in denitrifying bacterial isolates capable of degrading aromatic compounds and in river and estuarine sediment samples from the Arthur Kill in New Jersey and the Chesapeake Bay in Maryland was investigated. Degenerate primers were developed from the known benzoyl-CoA reductase genes from Thauera aromatica, Rhodopseudomonas palustris, and Azoarcus evansii. PCR amplification detected benzoyl-CoA reductase genes in the denitrifying isolates belonging to alpha-, beta-, or gamma-Proteobacteria as well as in the sediment samples. Phylogenetic analysis, sequence similarity comparison, and conserved indel determination grouped the new sequences into either the bcr type (found in T. aromatica and R. palustris) or the bzd type (found in A. evansii). All the Thauera strains and the isolates from the genera Acidovorax, Bradyrhizobium, Paracoccus, Ensifer, and Pseudomonas had bcr-type benzoyl-CoA reductases with amino acid sequence similarities of more than 97%. The genes detected from Azarocus strains were assigned to the bzd type. A total of 50 environmental clones were detected from denitrifying consortium and sediment samples, and 28 clones were assigned to either the bcr or the bzd type of benzoyl-CoA reductase genes. Thus, we could determine the genetic capabilities for anaerobic degradation of aromatic compounds in sediment communities of the Chesapeake Bay and the Arthur Kill on the basis of the detection of two types of benzoyl-CoA reductase genes. The detected genes have future applications as genetic markers to monitor aromatic compound degradation in natural and engineered ecosystems. PMID:15812036

Song, Bongkeun; Ward, Bess B

2005-04-01

202

Survival of the North American strain of viral hemorrhagic septicemia virus (VHSV) in filtered seawater and seawater containing ovarian fluid, crude oil and serum-enriched culture medium.  

Science.gov (United States)

The North American strain of viral hemorrhagic septicemia virus (NA-VHSV) could be recovered for up to 40 h in natural filtered seawater (27 ppt) with a 50% loss of infectivity after approximately 10 h at 15 degrees C. Addition of 10 ppb North Slope crude oil to the seawater had no effect on virus survival. However, when various concentrations of teleost ovarian fluid were added to seawater, virus could be recovered after 72 h at 0.01% ovarian fluid and after 96 h at 1.0%. When cell culture medium supplemented with 10% fetal bovine serum was added to the seawater, 100% of the virus could be recovered for the first 15 d and 60% of the virus remained after 36 d. These findings quantify NA-VHSV infectivity in natural seawater and demonstrate that ovarian fluid, which occurs naturally during spawning events, significantly prolongs the survival and infectivity of the virus. The extended stabilization of virus in culture medium supplemented with serum allows for low titer field samples to be collected and transported in an unfrozen state without significant loss of virus titer. PMID:11253879

Kocan, R M; Hershberger, P K; Elder, N E

2001-01-26

203

Molecular Characterization of Diazotrophic and Denitrifying Bacteria Associated with Mangrove Roots?  

OpenAIRE

An analysis of the molecular diversity of N2 fixers and denitrifiers associated with mangrove roots was performed using terminal restriction length polymorphism (T-RFLP) of nifH (N2 fixation) and nirS and nirK (denitrification), and the compositions and structures of these communities among three sites were compared. The number of operational taxonomic units (OTU) for nifH was higher than that for nirK or nirS at all three sites. Site 3, which had the highest organic matter and sand content i...

Flores-mireles, Ana L.; Winans, Stephen C.; Holguin, Gina

2007-01-01

204

Autotrophic, Hydrogen-Oxidizing, Denitrifying Bacteria in Groundwater, Potential Agents for Bioremediation of Nitrate Contamination  

OpenAIRE

Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent Km of 0.45 to 0.60 ?M and a Vmax of 18.7 nmol cm-3 h-1 at 30°C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strai...

Smith, Richard L.; Ceazan, Marnie L.; Brooks, Myron H.

1994-01-01

205

In Vivo Emission of Dinitrogen by Earthworms via Denitrifying Bacteria in the Gut  

OpenAIRE

Earthworms emit the greenhouse gas nitrous oxide (N2O), and ingested denitrifiers in the gut appear to be the main source of this N2O. The primary goal of this study was to determine if earthworms also emit dinitrogen (N2), the end product of complete denitrification. When [15N]nitrate was injected into the gut, the earthworms Aporrectodea caliginosa and Lumbricus terrestris emitted labeled N2 (and also labeled N2O) under in vivo conditions; emission of N2 by these two earthworms was relative...

Horn, Marcus A.; Mertel, Ralph; Gehre, Matthias; Ka?stner, Matthias; Drake, Harold L.

2006-01-01

206

Taxis response of various denitrifying bacteria to nitrate and nitrite.  

Science.gov (United States)

The taxis response of Rhodobacter sphaeroides 2.4.1 and 2.4.3, Rhodopseudomonas palustris, and Agrobacterium tumefaciens to nitrate and nitrite was evaluated by observing the macroscopic behavior of cells suspended in soft agar and incubated under various conditions. R. sphaeroides 2.4.3, which is capable of both nitrate and nitrite reduction, showed a taxis response to both nitrate and nitrite. R. sphaeroides 2.4.1, which contains nitrate reductase but not nitrite reductase, did not show a taxis response towards either nitrogen oxide. Insertional inactivation of the nitrite reductase structural gene or its transcriptional regulator, NnrR, in strain 2.4.3 caused a loss of a taxis response towards both nitrate and nitrite. An isolate of 2.4.1 carrying a copy of the nitrite reductase gene from 2.4.3 showed a taxis response to both nitrogen oxides. The taxis response of 2.4.3 was observed under anaerobic conditions, suggesting that the taxis response was due to nitrate and nitrite respiration, not to inhibition of oxygen respiration by respiration of nitrogen oxides. Strain 2.4.3 showed a taxis response to nitrate and nitrite under photosynthetic and aerobic conditions. Changing the carbon source in the culture medium caused an unexpected subtle shift in the taxis response of 2.4.3 to nitrite. A taxis response to nitrogen oxides was also observed in R. palustris and A. tumefaciens. R. palustris exhibited a taxis response to nitrite but not to nitrate, while A. tumefaciens exhibited a response to both compounds. PMID:11976082

Lee, Dong Yun; Ramos, Adela; Macomber, Lee; Shapleigh, James P

2002-05-01

207

Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae was identified as dominant benzene degrader by Stable Isotope Probing (SIP)  

OpenAIRE

An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a syntrophic interaction, and that benzene can be degraded in syntrophy by consortia with various electron acceptors in the same culture. The benzene-degrading microorganisms were identified by DNA-sta...

Zaan, B. M.; Talarico Saia, F.; Plugge, C. M.; Vos, W. M.; Smidt, H.; Stams, A. J. M.; Langenhoff, A. A. M.; Gerritse, J.

2012-01-01

208

Effect of CO2 enrichment and high photosynthetic photon flux densities (PPFD) on rubisco and PEP-case activities of in vitro cultured strawberry plants  

International Nuclear Information System (INIS)

Standard growing conditions in vitro (low light and CO2) are not conducive to autotrophy. An experiment was conducted to improve photosynthesis in vitro in the hope of increasing survival in acclimatization. A factorial experiment was elaborated where CO2 and PPFD were supplied to in vitro cultured strawberry plants in the rooting stage. Activities of carboxylating enzymes were determined after 4 weeks of culture. The activities of non-activated and activated rubisco and PEP-Case were measured after extraction of the enzymes and a reaction with NaH14CO3 followed by scintillation counting spectroscopy. High CO2 concentration significantly increased net assimilation rates (NAR) by 165% over the control for both 1650 and 3000 ppm CO2. High PPFD only increased NAR by 12 and 35% for 150 and 250 ?mol·m-2·s-1 respectively over the control. Plants grown at 3000 ppm CO2 had the highest level of chlorophyll/g FW with 97% more than the control. The activity of PEP-Case was the highest at high light levels and high CO2 with rates of 1.65 for 1650 ppm versus 1.22 mmol CO2 mg-1 chl. h-1 at 250 ?mol·m-2·s-1. There was no difference in PEP activity at low light levels. The rubisco activity was lower at 1650 and 3000 ppm CO2. Increases in NAR correlate more closely to the PEP-Case than to Rubisco activity.e PEP-Case than to Rubisco activity. Physiological significance of high activity of PEP-Case over rubisco will be discussed

209

Characterization of the denitrifying fraction of phosphate accumulating organisms in biological phosphate removal  

DEFF Research Database (Denmark)

Results of experimental investigations are presented that strongly support the hypothesis that PAO from activated sludge systems consist of two groups: a) denitrifying PAO (DNPAO) capable of using oxygen and nitrate and b) non-denitrifying PAO (non-DNPAO) only able to use oxygen. Batch experiments were performed in which activated sludge obtained from a pilot scale BIODENIPHO(TM) was submitted to a sequence of anaerobic/anoxic/aerobic, anaerobic/aerobic or anaerobic/anoxic conditions while monitoring the course of NOX-N, NH4-N, PO4-P, PHB and PHV. Several methods for the determination of the two fractions of PAO are performed and compared. This study extends on previously reported results (Kerrn-Jespersen and Henze, 1993) in that the pH was controlled to around pH 7 to assure that phosphate precipitation was minimal, and in the measurement of PHB and PHV. With regards to the latter, the paper also examines the influence of the size of the internal PHA pool on the anoxic phosphorus uptake rate. Simulations implementing existing models for the growth of non-DNPAO and DNPAO are used to confirm the experimental results and to gain a better understanding of some of the observations. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.

Meinhold, Jens; Filipe, Carlos D.M.

1999-01-01

210

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

Science.gov (United States)

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 efficient denitrifying ability (94.2% of nitrate removal and 80.9% of total nitrogen removal in 48 h). During denitrification by NY-4, no NO2 (-)-N was accumulated, N2 was the only gaseous product and no harmful N2O was produced. Because of its rapid denitrification ability, broad carbon use range and ability to grow under high salinity and pH conditions, NY-4 holds promise for the treatment of saline waste waters. PMID:25538872

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

2013-01-01

211

Evaluation of the microbial diversity of denitrifying bacteria in batch reactor  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Microbial communities in an industrial activated sludge plant may contribute to the denitrification process, but the information on the microorganisms present in denitrifying reactors is still scarce. Removal of inorganic nitrogen compounds can be accomplished by the addition of carbon sources to th [...] e biological process of denitrification. Ethanol is an economically viable alternative as a carbon source in tropical countries like Brazil, with large-scale production from sugarcane. This paper reports the successful aplication of activated sludge with nitrate and ethanol in a batch anaerobic reactor. The operation lasted 61.5 h with total consumption of nitrate in 42.5 h, nitrite generation (2.0 mg/L) and ethanol consumption (830.0 mg/L) in 23.5 h. Denitrifying cell counts by the most probable number at the start of the operation were lower than at the end, confirming the ability of the inoculum from activated sludge for the denitrification process. The samples from cell counts were identified as Acidovorax sp., Acinetobacter sp., Comamonas sp. and uncultured bacteria. Therefore, these species may be involved in nitrate reduction and ethanol consumption in the batch reactor.

S. I., Maintinguer; I. K., Sakamoto; M. A. T., Adorno; M. B. A., Varesche.

2013-09-01

212

Development of a macrophage cell culture method to isolate and enrich Francisella tularensis from food matrices for subsequent detection by real-time PCR.  

Science.gov (United States)

Francisella tularensis is a gram-negative bacterium that can cause gastrointestinal or oropharyngeal tularemia in humans from ingestion of contaminated food or water. Despite the potential for accidental or intentional contamination of foods with F. tularensis, there are no techniques currently available to detect this organism in specific food matrices. In this study, a macrophage cell culture system is combined with real-time PCR to identify F. tularensis in food matrices. The method utilizes a mouse macrophage cell line (RAW 264.7) as host for the isolation and intracellular replication of F. tularensis. Exposure of macrophages to F. tularensis-contaminated food matrices results in uptake and intracellular replication of the bacteria, which can be subsequently detected by real-time PCR analysis of the DNA released from infected macrophage cell lysates. Macrophage monolayers were exposed to infant formula, liquid egg whites, and lettuce contaminated with varying quantities of F. tularensis. As few as 10 CFU/ml (or CFU per gram) F. tularensis was detected in infant formula and lettuce after 5 h postinfection. As few as 10 CFU/ml F. tularensis was detected in liquid egg whites after 18 h postinfection. Intracellular F. tularensis could also be isolated on Mueller-Hinton medium from lysates of macrophages infected with the bacteria in infant formula, liquid egg whites, and lettuce for subsequent confirmatory identification. This method is the first to successfully identify F. tularensis from select food matrices. PMID:19610325

Day, J B; Whiting, R C

2009-06-01

213

Regeneration of Ginger Plant from Callus Culture Through Organogenesis and Effect of CO2 Enrichment on the Differentiation of Regenerated Plant  

Directory of Open Access Journals (Sweden)

Full Text Available A efficient and systematic protocol for complete plant regeneration via shoot apical meristem culture has been developed for Zingiber officinale L. Callus was initiated from shoot-tip of young plant on MS-media supplemented with a combination of Naphthalene acetic acid (0.1 mg L-1 and Kinetin (1.0-2.0 mg L-1 and Indole-3-acetic acid (0.1 mg L-1 and 6-Benzylaminopurine (1.0-2.0 mg L-1. Maximum shoot differentiation from callus occurred on MS medium supplemented with Indole-3-acetic acid (0.1 mg L-1 and 6-Benzylaminopurine (1.0 mg L-1. Complete plantlets were transferred into specially made plastic pot containing soilrite followed by their transfer to the field soil. Survival rate of the plantlets under ex vitro condition was 90%. Regenerated plants on MS medium supplemented with Naphthalene acetic acid (0.1 mg L-1 and 6-Benzylaminopurine (0.1 mg L-1 was exposed to elevated CO2 concentration. A 400-4000 ppm increase in atmospheric CO2 concentration led to an increase in adventitious bud and shoot primodium while the growth of adventitious bud and shoot primodium were reduced at 8000 ppm.

Muhammad Jamil

2007-01-01

214

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

Science.gov (United States)

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.

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

2010-12-01

215

Effects of mechanical disintegration of activated sludge on the activity of nitrifying and denitrifying bacteria and phosphorus accumulating organisms.  

Science.gov (United States)

The purpose of the study was to analyse the impact of hydrodynamic disintegration of thickened excess activated sludge, performed at different levels of energy density (70, 140 and 210 kJ/L), on the activity of microorganisms involved in nutrient removal from wastewater, i.e. nitrifiers, denitrifiers and phosphorus accumulating organisms (PAOs). Ammonium and nitrogen utilisation rates and phosphorus release rates for raw and disintegrated sludge were determined using batch tests. The experiment also included: 1) analysis of organic and nutrient compound release from activated sludge flocs, 2) determination of the sludge disintegration degree (DD), and 3) evaluation of respiratory activity of the biomass by using the oxygen uptake rate (OUR) batch test. It was shown that the activity degree of the examined groups of microorganisms depended on energy density and related sludge disintegration degree, and that inactivation of individual groups of microorganisms occurred at different values of DD. Least resistant to the destruction of activated sludge flocs turned out to be phosphorus accumulating organisms, while the most resistant were denitrifiers. A decrease of 20-40% in PAO activity was noted already at DD equal to 3-5%. The threshold values of DD, after crossing which the inactivation of nitrifiers and denitrifiers occurred, were equal to 8% and 10%, respectively. At lesser DD values an increase in the activity of these groups of microorganisms was observed, averaging 20.2-41.7% for nitrifiers and 9.98-36.3% for denitrifiers. PMID:24922354

Zubrowska-Sudol, Monika; Walczak, Justyna

2014-09-15

216

Actinobacterial nitrate reducers and proteobacterial denitrifiers are abundant in N2O-metabolizing palsa peat.  

Science.gov (United States)

Palsa peats are characterized by elevated, circular frost heaves (peat soil on top of a permanently frozen ice lens) and are strong to moderate sources or even temporary sinks for the greenhouse gas nitrous oxide (N(2)O). Palsa peats are predicted to react sensitively to global warming. The acidic palsa peat Skalluvaara (approximate pH 4.4) is located in the discontinuous permafrost zone in northwestern Finnish Lapland. In situ N(2)O fluxes were spatially variable, ranging from 0.01 to -0.02 ?mol of N(2)O m(-2) h(-1). Fertilization with nitrate stimulated in situ N(2)O emissions and N(2)O production in anoxic microcosms without apparent delay. N(2)O was subsequently consumed in microcosms. Maximal reaction velocities (v(max)) of nitrate-dependent denitrification approximated 3 and 1 nmol of N(2)O per h per gram (dry weight [g(DW)]) in soil from 0 to 20 cm and below 20 cm of depth, respectively. v(max) values of nitrite-dependent denitrification were 2- to 5-fold higher than the v(max) nitrate-dependent denitrification, and v(max) of N(2)O consumption was 1- to 6-fold higher than that of nitrite-dependent denitrification, highlighting a high N(2)O consumption potential. Up to 12 species-level operational taxonomic units (OTUs) of narG, nirK and nirS, and nosZ were retrieved. Detected OTUs suggested the presence of diverse uncultured soil denitrifiers and dissimilatory nitrate reducers, hitherto undetected species, as well as Actino-, Alpha-, and Betaproteobacteria. Copy numbers of nirS always outnumbered those of nirK by 2 orders of magnitude. Copy numbers of nirS tended to be higher, while copy numbers of narG and nosZ tended to be lower in 0- to 20-cm soil than in soil below 20 cm. The collective data suggest that (i) the source and sink functions of palsa peat soils for N(2)O are associated with denitrification, (ii) actinobacterial nitrate reducers and nirS-type and nosZ-harboring proteobacterial denitrifiers are important players, and (iii) acidic soils like palsa peats represent reservoirs of diverse acid-tolerant denitrifiers associated with N(2)O fluxes. PMID:22660709

Palmer, Katharina; Horn, Marcus A

2012-08-01

217

Kinetics of nitrate inhibition of carbon tetrachloride transformation by a denitrifying consortia  

International Nuclear Information System (INIS)

Past operations of the US Department of Energy's Hanford Site resulted in carbon tetrachloride (CT) contamination in both the aquifer and vadose zones. Bioremediation is one technology currently being developed by the US Department of Energy to meet the need for cost-effective technologies to remove this contaminant. The kinetics of nitrate inhibition of carbon tetrachloride (CT) transformation were examined using a denitrifying consortium. Comparison of data from fed-batch experiments to the model reported by Hooker et al. indicate that the inhibition constant ranges between 3.2 and 21 mg/L, with an average of 8.8 mg/L. This range is much lower than the previously reported value of 169 mg/L. Simulations using the corrected parameter accurately reflect this new data and the data reported by Hooker et al. In contrast, the earlier reported coefficient value does not reflect the data reported in this work

218

Characterization of the dihemic cytochrome c549 from the marine denitrifying bacterium Pseudomonas nautica 617.  

Science.gov (United States)

A dihemic ferricytochrome c549 (21 kDa) was purified and characterized from cells of the marine denitrifier Pseudomonas nautica strain 617. Several spectroscopic techniques, including UV-visible, NMR and EPR spectroscopies were applied to the characterization of this cytochrome. The visible and the 1H-NMR spectra show that both hemes have histidine-methionine as axial ligands. The dihemic cytochrome c549 has mid-point redox potentials of +230 mV and +250 mV, at pH 7.6 and its NH2-terminal sequence presents a high degree of similarity with those of cytochromes c4. The EPR studies allowed the determination of the orientation between the two axial ligands, indicating an axial ligand field for one of the hemes of cytochrome c549 and a rhombic symmetry for the other heme. PMID:8147872

Saraiva, L M; Besson, S; Fauque, G; Moura, I

1994-03-30

219

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

Science.gov (United States)

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

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

2015-04-01

220

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

Directory of Open Access Journals (Sweden)

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 ? –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 was detected.

MichelaLangone

2014-02-01

221

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

Science.gov (United States)

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 ?M 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 constrained.

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

2011-12-01

222

Advantages of functional single-cell isolation method over standard agar plate dilution method as a tool for studying denitrifying bacteria in rice paddy soil  

OpenAIRE

We recently established a method for isolating functional single cells from environmental samples using a micromanipulator (Functional single-cell (FSC) isolation), and applied it to the study of denitrifying bacteria in rice paddy soil (Ashida et al. 2010. Appl Microbiol Biotechnol 85:1211–1217). To further examine the advantages and possible disadvantages of the FSC method, we isolated denitrifying bacteria from the same rice paddy soil sample using both FSC and standard agar plate diluti...

Nishizawa, Tomoyasu; Tago, Kanako; Uei, Yusuke; Ishii, Satoshi; Isobe, Kazuo; Otsuka, Shigeto; Senoo, Keishi

2012-01-01

223

Uranium Enrichment, an overview  

International Nuclear Information System (INIS)

This general presentation on uranium enrichment will be followed by lectures on more specific topics including descriptions of enrichment processes and assessments of the prevailing commercial and industrial situations. I shall therefore avoid as much as possible duplications with these other lectures, and rather dwell on: some theoretical aspects of enrichment in general, underlying the differences between statistical and selective processes, a review and comparison between enrichment processes, remarks of general order regarding applications, the proliferation potential of enrichment. It is noteworthy that enrichment: may occur twice in the LWR fuel cycle: first by enriching natural uranium, second by reenriching uranium recovered from reprocessing, must meet LWR requirements, and in particular higher assays required by high burn up fuel elements, bears on the structure of the entire front part of the fuel cycle, namely in the conversion/reconversion steps only involving UF6 for the moment. (author). tabs., figs., 4 refs

224

Isolation of the ?-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin  

International Nuclear Information System (INIS)

?-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 ?-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 ?-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 ?-caprolactam to denitrify from synthetic wastewater. Complete ?-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

225

Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples  

OpenAIRE

The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of nitrous oxide production at oxic conditions, but strongly enhanced the nitrous oxide production at oxygen-poor and anoxic conditions. Inhibition of nitrification by short exposure (1 to 24 h) to h...

Kester, R. A.; Boer, W.; Laanbroek, H. J.

1996-01-01

226

Impacts of different N management regimes on nitrifier and denitrifier communities and N cycling in soil microenvironments  

OpenAIRE

Real-time quantitative PCR assays, targeting part of the ammonia-monooxygenase (amoA), nitrous oxide reductase (nosZ), and 16S rRNA genes were coupled with 15N pool dilution techniques to investigate the effects of long-term agricultural management practices on potential gross N mineralization and nitrification rates, as well as ammonia-oxidizing bacteria (AOB), denitrifier, and total bacterial community sizes within different soil microenvironments. Three soil microenvironments [coarse parti...

Kong, Angela Y. Y.; Hristova, Krassimira; Scow, Kate M.; Six, Johan

2010-01-01

227

Anaerobic Mineralization of Quaternary Carbon Atoms: Isolation of Denitrifying Bacteria on Pivalic Acid (2,2-Dimethylpropionic Acid)  

OpenAIRE

The degradability of pivalic acid was established by the isolation of several facultative denitrifying strains belonging to Zoogloea resiniphila, to Thauera and Herbaspirillum, and to Comamonadaceae, related to [Aquaspirillum] and Acidovorax, and of a nitrate-reducing bacterium affiliated with Moraxella osloensis. Pivalic acid was completely mineralized to carbon dioxide. The catabolic pathways may involve an oxidation to dimethylmalonate or a carbon skeleton rearrangement, a putative 2,2-dim...

Probian, Christina; Wu?lfing, Annika; Harder, Jens

2003-01-01

228

Influence of Freeze-Thaw Stress on the Structure and Function of Microbial Communities and Denitrifying Populations in Soil†  

OpenAIRE

Microbial N2O release during the course of thawing of soil was investigated in model experiment focusing on denitrification, since freeze-thaw has been shown to cause significant physical and biological changes in soil, including a surge of N2O and CO2. The origin of these is still controversially discussed. The increase in denitrification after thawing may be attributed to the diffusion of organic substrates newly available to denitrifiers from disrupted soil aggregates, leading to an increa...

Sharma, Shilpi; Szele, Zsofia; Schilling, Rolf; Munch, Jean Charles; Schloter, Michael

2006-01-01

229

Population analysis in a denitrifying sand filter: conventional and in situ identification of Paracoccus spp. in methanol-fed biofilms.  

OpenAIRE

The microbial community of a denitrifying sand filter in a municipal wastewater treatment plant was examined by conventional and molecular techniques to identify the bacteria actively involved in the removal of nitrate. In this system, denitrification is carried out as the last step of water treatment by biofilms growing on quartz grains with methanol as a supplemented carbon source. The biofilms are quite irregular, having a median thickness of 13 to 20 microns. Fatty acid analysis of 56 den...

Neef, A.; Zaglauer, A.; Meier, H.; Amann, R.; Lemmer, H.; Schleifer, K. H.

1996-01-01

230

Effect of Earthworm Feeding Guilds on Ingested Dissimilatory Nitrate Reducers and Denitrifiers in the Alimentary Canal of the Earthworm ? †  

OpenAIRE

The earthworm gut is an anoxic nitrous oxide (N2O)-emitting microzone in aerated soils. In situ conditions of the gut might stimulate ingested nitrate-reducing soil bacteria linked to this emission. The objective of this study was to determine if dissimilatory nitrate reducers and denitrifiers in the alimentary canal were affected by feeding guilds (epigeic [Lumbricus rubellus], anecic [Lumbricus terrestris], and endogeic [Aporrectodea caliginosa]). Genes and gene transcripts of narG (encodes...

Depkat-jakob, Peter S.; Hilgarth, Maik; Horn, Marcus A.; Drake, Harold L.

2010-01-01

231

Advanced enrichment techniques  

International Nuclear Information System (INIS)

BNFL is in a unique position in that it has commercial experience of diffusion enrichment, and of centrifuge enrichment through its associate company Urenco. In addition BNFL is developing laser enrichment techniques as part of a UK development programme in this area. The paper describes the development programme which led to the introduction of competitive centrifuge enrichment technology by Urenco and discusses the areas where improvements have and will continue to be made in the centrifuge process. It also describes the laser development programme currently being undertaken in the UK. The paper concludes by discussing the relative merits of the various methods of uranium enrichment, with particular reference to the enrichment market likely to obtain over the rest of the century. (author)

232

Uranium enrichment: an overview  

International Nuclear Information System (INIS)

This paper is a general presentation of uranium enrichment processes and assessments of the prevailing commercial and industrial situations. It gives first some theoretical aspects of enrichment in general and explains the differences between statistical and selective processes in particular. Then a review of the different processes is made with a comparison between them. Finally, some general remarks concerning applications are given and the risks of proliferation related to enrichment are mentioned. (J.S.). 4 refs., 5 figs., 8 tabs

233

Uranium enrichment: an overview  

Energy Technology Data Exchange (ETDEWEB)

This paper is a general presentation of uranium enrichment processes and assessments of the prevailing commercial and industrial situations. It gives first some theoretical aspects of enrichment in general and explains the differences between statistical and selective processes in particular. Then a review of the different processes is made with a comparison between them. Finally, some general remarks concerning applications are given and the risks of proliferation related to enrichment are mentioned. (J.S.). 4 refs., 5 figs., 8 tabs.

Cazalet, J.

1995-12-31

234

Uranium enrichment and conversion  

International Nuclear Information System (INIS)

This report mainly refers to uranium enrichment. Following points are dealt with: The present situation on the world market for separation activities; Decision of DOE regarding the future enrichment techniques in the USA; Start-up of the new enrichment plant of URENCO DEUTSCHLAND in Gronau; Successes of the Urenco-centrifuge techniques; Present level of laser enrichment from the standpoint of Uranit. This is followed by a brief survey of the market for conversion. The conversion of uranium recovered from the reprocessing of LWR-fuel is dealt with more closely. (orig./UA)

235

Thermal characterization during dehydration of nitrifying and denitrifying microbiological mud encapsulated in silica gel  

International Nuclear Information System (INIS)

An alternative method to diminish the nitrogen pollutant levels in waste waters is to encapsulate microorganisms whitin ceramic materials. The sol-gel method has been extensively used for the preparation of such kind of materials permitting a higher stability and viability of useful organisms. In this work, the thermal characterization during dehydration of nitrifying and denitrifying aqueous emulsions of mud encapsulated in sol-gel silica is presented during the process of dehydration in ambient conditions and as a function of temperature. The characterization was performed by a photopyroelectric (PPE) technique, whose detector was made with a 110 mm polyvinyldifluoride (PVDF). The cell was constructed in such a way that the sample was inside the cell, and the bottom of the cell was closed by the PVDF foil. Thermal effusivity as a function of temperature was obtained illuminating the PVDF directly by a modulated 1W tungsten lamp. The sample is enclosed inside a chamber, using a Peltier cell that controls temperature in a range from 40 to 27 deg. C. The sample is on top of the PVDF, which is illuminated by the modulated tungsten lamp

236

A biofilm model to understand the onset of sulfate reduction in denitrifying membrane biofilm reactors.  

Science.gov (United States)

This work presents a multispecies biofilm model that describes the co-existence of nitrate- and sulfate-reducing bacteria in the H(2)-based membrane biofilm reactor (MBfR). The new model adapts the framework of a biofilm model for simultaneous nitrate and perchlorate removal by considering the unique metabolic and physiological characteristics of autotrophic sulfate-reducing bacteria that use H(2) as their electron donor. To evaluate the model, the simulated effluent H(2), UAP (substrate-utilization-associated products), and BAP (biomass-associated products) concentrations are compared to experimental results, and the simulated biomass distributions are compared to real-time quantitative polymerase chain reaction (qPCR) data in the experiments for parameter optimization. Model outputs and experimental results match for all major trends and explain when sulfate reduction does or does not occur in parallel with denitrification. The onset of sulfate reduction occurs only when the nitrate concentration at the fiber's outer surface is low enough so that the growth rate of the denitrifying bacteria is equal to that of the sulfate-reducing bacteria. An example shows how to use the model to design an MBfR that achieves satisfactory nitrate reduction, but suppresses sulfate reduction. PMID:23055395

Tang, Youneng; Ontiveros-Valencia, Aura; Feng, Liang; Zhou, Chen; Krajmalnik-Brown, Rosa; Rittmann, Bruce E

2013-03-01

237

Spatial variations in denitrification activity in wetland sediments explained by hydrology and denitrifying community structure.  

Science.gov (United States)

We determined spatial variations in potential denitrification activity and the controlling hydrological as well as biochemical processes in the sediments of a Swedish treatment wetland. Hydrological processes, including water residence times, were analyzed using a 2D depth-averaged flow model and the denitrifier community structure was analyzed using denaturing gradient gel electrophoreses (DGGE) of nosZ genes, encoding nitrous oxide reductase. In addition, we provide a theoretical basis for evaluation of denitrification rates useful in nitrate-limited conditions. The results demonstrate that potential denitrification rates differed significantly between the sampling locations (CV=0.34). The variations were best described by concentration of nitrogen in sediments and water residence time. DGGE analyses indicated that a few key populations dominated and that the community diversity increased with decreasing nutrient levels and increasing water residence times. Moreover, we found that denitrification rates in terms of Menten and first-order kinetics can be evaluated by fitting a mathematical expression, comparing denitrification and other nitrogen-transforming processes to measured product formation in nitrate-limited experiments. PMID:17643466

Kjellin, Johan; Hallin, Sara; Wörman, Anders

2007-12-01

238

Biogeographical distribution of denitrifying anaerobic methane oxidizing bacteria in Chinese wetland ecosystems.  

Science.gov (United States)

The discovery of denitrifying anaerobic methane oxidation with nitrite as electron acceptor mediated by 'Candidatus?Methylomirabilis oxyfera' connected the biogeochemical carbon and nitrogen cycle in a new way. However, it is important to have a comprehensive understanding about the distribution of M.?oxyfera-like bacteria in the terrestrial realm, especially the wetland ecosystems that are known as the largest natural source of atmospheric methane. Here, our molecular evidence demonstrated that a wide geographical distribution of M.?oxyfera-like bacteria at oxic/anoxic interfaces of various wetlands (n?=?91) over the Chinese territory. Intriguingly, the M.?oxyfera-like bacteria were detected in some extreme environments, indicating that M.?oxyfera-like bacteria occupied a wide range of habitats. Quantitative polymerase chain reaction estimated that the abundance of M.?oxyfera-like bacteria ranged from 2.2?×?10(3) to 2.3?×?10(7) copies?g(-1) dry soil, and up to around 0.62% of the total number of bacteria. Moreover, the M.?oxyfera-like bacteria showed high biodiversity in wetland ecosystems based on the analysis of 462 pmoA and 287 16S rRNA gene sequences. The current study revealed the widespread distribution and biogeography of M.?oxyfera-like bacteria in the terrestrial system. PMID:25223900

Zhu, Guibing; Zhou, Leiliu; Wang, Yu; Wang, Shanyun; Guo, Jianhua; Long, Xi-En; Sun, Xingbin; Jiang, Bo; Hou, Qiaoyun; Jetten, Mike S M; Yin, Chengqing

2015-02-01

239

Sustainable nitrogen removal by denitrifying anammox applied for anaerobic pre-treated potato wastewater.  

Science.gov (United States)

The feasibility of sustainable nitrogen removal was investigated in a two stage biofilm configuration consisting of a MBBR (Moving Bed Biofilm Reactor) and a Deamox reactor (Biobed-EGSB). The MBBR is used for nitrification and the denitrifying ammonium oxidation (Deamox) is aimed at a nitrogen removal process in which part of the required nitrite for the typical anammox reaction originated from nitrate. Anaerobic pre-treated potato wastewater was supplied to a MBBR and Deamox reactor operated in series with a bypass flow of 30%. The MBBR showed stable nitrite production at ammonium-loading rates of 0.9-1.0 kg NH?-N/m³ d with ammonium conversion rates of 0.80-0.85 kg NH?-N/m³ d. The nitrogen-loading rate and conversion rate of the Deamox reactor were 1.6-1.8 and 1.6 kg N/m³ d. The maximum ammonium removal capacity in the Deamox reactor was 0.6 kg NH?-N/m³ d. The removal efficiency of soluble total nitrogen reached 90%. The Deamox process performance was found to be negatively affected during decline of the operating temperature from 33 to 22 °C and by organic loading rates with a chemical oxygen demand (COD)/NO?-N ratio >1. PMID:23109579

Mulder, A; Versprille, A I; van Braak, D

2012-01-01

240

Developments in uranium enrichment  

International Nuclear Information System (INIS)

The enrichment services market is still characterized by overcapacities. While consumption worldwide will rise by some 15% to 39,000 t SWU/a over the next ten years, capacities amount to nearly 50,000 t SWU/a. The price for enrichment services probably has reached its all time low. Prices below U.S. $ 100/kg SWU are not likely to cover costs even of the economically most advanced enrichment processes. Urenco has prepared for the difficult enrichment business in the years to come by streamlining and cost cutting measures. The company intends to hold and increase its share of more than 10% in the world market. The uranium enrichment plant of Gronau will be expanded further. Expansion beyond 1000 t is subject to another permit being granted under the Atomic Energy Act, an application for which was filed in December 1994. Centrifuge technology is the superior enrichment technology, i.e., there is still considerable potential for further development. Construction of enrichment plants employing the centrifuge technology in the United States and in France is being pursued in various phases, from feasibility studies to licensing procedures. Before these plants could be implemented, however, considerable problems of organization would have to be solved, and the market would have to change greatly, respectively. The laser process, at the present time, does not seem to be able to develop into a major industrial competitor. (orig.)

241

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

242

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

243

Enrichment go-ahead  

International Nuclear Information System (INIS)

The Atomic Energy Corporation of South Africa's uranium enrichment plant at Valindaba is expected to come into commercial production by the end of 1987, thus ending Escom's dependence on foreign enrichment facilities. Because there is a world surplus of enrichment capacity, it is unlikely that South Africa will find export markets for production surplus. The prices quoted oversees for enriched uranium are below cost. The market for natural uranium is also over-supplied. Uranium prices are thus likely to remain low until the end of the century. The nuclear development programme around the world has been adversely affected by increased concern over safety as well as a slow growth of demand for energy in the West

244

Uranium isotopic enrichment  

International Nuclear Information System (INIS)

After having recalled, with the help of tables the offer and demand for enrichment services in the world, the various techniques, namely: gas diffusion, ultracentrifugation, aerodynamic processes, chemical exchange and laser separation are compared from the technical, economic and proliferation angles. The producers of enriched uranium are: DOE (USA), Technabexport (USSR), Eurodif, Urenco and PNC (Japan). The article concludes with the techniques under development or projected

245

Urenco's enrichment experience  

International Nuclear Information System (INIS)

Although enrichment capacity will exceed the demand from nuclear power plants until the nineties, new enrichment capacity is being constructed in the USA and Europe. In both cases centrifuge technology is being employed. In the USA industrial-scale plants are replacing diffusion capacity on a step-wise basis. Urenco began construction of the first industrial centrifuge plants some 10 years ago and today possesses a capacity of about 1 200 t separative work per year

246

Decaying Cyanobacteria decrease N2O emissions related to diversity of intestinal denitrifiers of Chironomus plumosus  

Directory of Open Access Journals (Sweden)

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.

Xu Sun

2014-02-01

247

Molecular characterization of diazotrophic and denitrifying bacteria associated with mangrove roots.  

Science.gov (United States)

An analysis of the molecular diversity of N(2) fixers and denitrifiers associated with mangrove roots was performed using terminal restriction length polymorphism (T-RFLP) of nifH (N(2) fixation) and nirS and nirK (denitrification), and the compositions and structures of these communities among three sites were compared. The number of operational taxonomic units (OTU) for nifH was higher than that for nirK or nirS at all three sites. Site 3, which had the highest organic matter and sand content in the rhizosphere sediment, as well as the lowest pore water oxygen concentration, had the highest nifH diversity. Principal component analysis of biogeochemical parameters identified soil texture, organic matter content, pore water oxygen concentration, and salinity as the main variables that differentiated the sites. Nonmetric multidimensional scaling (MDS) analyses of the T-RFLP data using the Bray-Curtis coefficient, group analyses, and pairwise comparisons between the sites clearly separated the OTU of site 3 from those of sites 1 and 2. For nirS, there were statistically significant differences in the composition of OTU among the sites, but the variability was less than for nifH. OTU defined on the basis of nirK were highly similar, and the three sites were not clearly separated on the basis of these sequences. The phylogenetic trees of nifH, nirK, and nirS showed that most of the cloned sequences were more similar to sequences from the rhizosphere isolates than to those from known strains or from other environments. PMID:17827324

Flores-Mireles, Ana L; Winans, Stephen C; Holguin, Gina

2007-11-01

248

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

Science.gov (United States)

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. PMID:15299774

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

1995-11-01

249

Anaerobic activation of p-cymene in denitrifying betaproteobacteria: methyl group hydroxylation versus addition to fumarate.  

Science.gov (United States)

The betaproteobacteria "Aromatoleum aromaticum" pCyN1 and "Thauera" sp. strain pCyN2 anaerobically degrade the plant-derived aromatic hydrocarbon p-cymene (4-isopropyltoluene) under nitrate-reducing conditions. Metabolite analysis of p-cymene-adapted "A. aromaticum" pCyN1 cells demonstrated the specific formation of 4-isopropylbenzyl alcohol and 4-isopropylbenzaldehyde, whereas with "Thauera" sp. pCyN2, exclusively 4-isopropylbenzylsuccinate and tentatively identified (4-isopropylphenyl)itaconate were observed. 4-Isopropylbenzoate in contrast was detected with both strains. Proteogenomic investigation of p-cymene- versus succinate-adapted cells of the two strains revealed distinct protein profiles agreeing with the different metabolites formed from p-cymene. "A. aromaticum" pCyN1 specifically produced (i) a putative p-cymene dehydrogenase (CmdABC) expected to hydroxylate the benzylic methyl group of p-cymene, (ii) two dehydrogenases putatively oxidizing 4-isopropylbenzyl alcohol (Iod) and 4-isopropylbenzaldehyde (Iad), and (iii) the putative 4-isopropylbenzoate-coenzyme A (CoA) ligase (Ibl). The p-cymene-specific protein profile of "Thauera" sp. pCyN2, on the other hand, encompassed proteins homologous to subunits of toluene-activating benzylsuccinate synthase (termed [4-isopropylbenzyl]succinate synthase IbsABCDEF; identified subunits, IbsAE) and protein homologs of the benzylsuccinate ?-oxidation (Bbs) pathway (termed BisABCDEFGH; all identified except for BisEF). This study reveals that two related denitrifying bacteria employ fundamentally different peripheral degradation routes for one and the same substrate, p-cymene, with the two pathways apparently converging at the level of 4-isopropylbenzoyl-CoA. PMID:25261521

Strijkstra, Annemieke; Trautwein, Kathleen; Jarling, René; Wöhlbrand, Lars; Dörries, Marvin; Reinhardt, Richard; Drozdowska, Marta; Golding, Bernard T; Wilkes, Heinz; Rabus, Ralf

2014-12-01

250

Denitrifiers in the surface zone are primarily responsible for the nitrous oxide emission of dairy manure compost  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? Nitrous oxide (N{sub 2}O) productions of each compost zones were compared. ? The pile surface emitted significant fluxes of N{sub 2}O. ? The isotopic signature of N{sub 2}O from surface and NO{sub 2}{sup ?} amended core were different. ? The denitrifying gene abundance was significantly higher in pile surface than the pile core. -- Abstract: During the dairy manure composting process, significant nitrous oxide (N{sub 2}O) emissions occur just after the pile turnings. To understand the characteristics of this N{sub 2}O emission, samples were taken from the compost surface and core independently, and the N{sub 2}O production was monitored in laboratory incubation experiments. Equal amounts of surface and core samples were mixed to simulate the turning, and the {sup 15}N isotope ratios within the molecules of produced N{sub 2}O were analyzed by isotopomer analysis. The results showed that the surface samples emitted significant levels of N{sub 2}O, and these emissions were correlated with NO{sub x}{sup ?}-N accumulation. Moreover, the surface samples and surface-core mixed samples incubated at 30 °C produced N{sub 2}O with a low site preference (SP) value (?0.9 to 7.0‰) that was close to bacteria denitrification (0‰), indicating that denitrifiers in the surface samples are responsible for this N{sub 2}O production. On the other hand, N{sub 2}O produced by NO{sub 2}{sup ?}-amended core samples and surface samples incubated at 60 °C showed unrecognized isotopic signatures (SP = 11.4–20.3‰). From these results, it was revealed that the N{sub 2}O production occurring just after the turnings was mainly derived from bacterial denitrification (including nitrifier denitrification) of NO{sub x}{sup ?}-N under mesophilic conditions, and surface denitrifying bacteria appeared to be the main contributor to this process.

Maeda, Koki, E-mail: k_maeda@affrc.go.jp [Dairy Research Division, National Agricultural Research Center for Hokkaido Region, National Agricultural and Food Research Organization, 1 Hitsujigaoka, Sapporo 062-8555 (Japan); Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Toyoda, Sakae [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Hanajima, Dai [Dairy Research Division, National Agricultural Research Center for Hokkaido Region, National Agricultural and Food Research Organization, 1 Hitsujigaoka, Sapporo 062-8555 (Japan); Yoshida, Naohiro [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2013-03-15

251

Influence of freeze-thaw stress on the structure and function of microbial communities and denitrifying populations in soil.  

Science.gov (United States)

Microbial N2O release during the course of thawing of soil was investigated in model experiment focusing on denitrification, since freeze-thaw has been shown to cause significant physical and biological changes in soil, including a surge of N2O and CO2. The origin of these is still controversially discussed. The increase in denitrification after thawing may be attributed to the diffusion of organic substrates newly available to denitrifiers from disrupted soil aggregates, leading to an increase in microbial activity. Laboratory experiments with upper soil layer of a grassland were conducted in microcosms for real-time gas measurements during the entire phase of freeze and thaw. Shifts in microbial communities were evident on resolution of 16S and 18S rRNA genes and transcripts by denaturing gradient gel electrophoresis (DGGE). Microbial expression profiles were compared by RNA-arbitrarily primed PCR technique and subsequent resolution of amplified products on acrylamide gels. Differences in expression levels of periplasmic nitrate reductase gene (napA) and cytochrome cd1 nitrite reductase (nirS) were observed by most-probable-number-reverse transcription-PCR, with higher levels of expression occurring just after thawing began, followed by a decrease. napA and nirS DGGE profiles showed no change in banding patterns with fingerprints derived from DNA, whereas those derived from cDNA showed a clear succession of denitrifying bacteria, with the most complex pattern being observed at the end of the N2O surge. This study provides insight into the structural community changes and expression dynamics of denitrifiers as a result of freeze-thaw stress. Also, the results presented here support the belief that the gas fluxes observed during thawing is a result of freezing initiated high microbial activity. PMID:16517665

Sharma, Shilpi; Szele, Zsofia; Schilling, Rolf; Munch, Jean Charles; Schloter, Michael

2006-03-01

252

Denitrifiers in the surface zone are primarily responsible for the nitrous oxide emission of dairy manure compost  

International Nuclear Information System (INIS)

Highlights: ? Nitrous oxide (N2O) productions of each compost zones were compared. ? The pile surface emitted significant fluxes of N2O. ? The isotopic signature of N2O from surface and NO2? amended core were different. ? The denitrifying gene abundance was significantly higher in pile surface than the pile core. -- Abstract: During the dairy manure composting process, significant nitrous oxide (N2O) emissions occur just after the pile turnings. To understand the characteristics of this N2O emission, samples were taken from the compost surface and core independently, and the N2O production was monitored in laboratory incubation experiments. Equal amounts of surface and core samples were mixed to simulate the turning, and the 15N isotope ratios within the molecules of produced N2O were analyzed by isotopomer analysis. The results showed that the surface samples emitted significant levels of N2O, and these emissions were correlated with NOx?-N accumulation. Moreover, the surface samples and surface-core mixed samples incubated at 30 °C produced N2O with a low site preference (SP) value (?0.9 to 7.0‰) that was close to bacteria denitrification (0‰), indicating that denitrifiers in the surface samples are responsible for this N2O production. On the other hand, N2O produced by NO2?-amended core samples and surface samples incubated at 60 °C showed unrecognized isotopic signatures (SP = 11.4–20.3‰). From these results, it was revealed that the N2O production occurring just after the turnings was mainly derived from bacterial denitrification (including nitrifier denitrification) of NOx?-N under mesophilic conditions, and surface denitrifying bacteria appeared to be the main contributor to this process

253

Evaluation of different culture media and enrichment in orange juice upon the growth of Alicyclobacillus spp. / Avaliação de diferentes meios de cultura e enriquecimento em suco de laranja sobre o crescimento de Alicyclobacillus spp.  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese As bactérias do gênero Alicyiclobacillus spp. formam esporos e se desenvolvem em meios ácidos, podendo causar deterioração em sucos cítricos. O Brasil é o maior exportador de suco de laranja concentrado do mundo e, assim, este gênero vem sendo estudado por causar alterações de odor e sabor. Vários e [...] studos relatam diferentes meios de culturas empregados para a detecção e enumeração de Alicyclobacillus spp. Este estudo teve como objetivo avaliar a recuperação de esporos de Alicyclobacillus spp. nos meios ALI, BAT, K ágar e YSG, utilizando a metodologia indicada pela ABECitrus. Cinco inóculos diferentes foram utilizados, sendo dois de linhagens-referência e os outros três isolados de suco concentrado de laranja pasteurizado. Também foi verificada a recuperação das células após o enriquecimento em suco de laranja reconstituído. Foi inoculada uma população inicial de 6 log UFC/mL. Os meios ALI, BAT e YSG conseguiram recuperar esta população nos diferentes inóculos, não existindo diferenças significativas entre os resultados. Contudo, devido à facilidade do preparo, os meios ALI e YSG mostraram-se mais vantajosos quando comparados ao meio BAT. O meio K ágar apresentou recuperação inferior aos outros meios para todos os inóculos, porém, houve diferença significativa apenas para Alicyclobacillus acidocaldarius 0298 T (3,66 log UFC/mL) e Alicyclobacillus pomorum-like CBMAI 0278 (4,11 log UFC/mL). Abstract in english Bacteria of the genus Alicyiclobacillus spp. form spores and develop in acid media, leading to the spoilage of citrus juices. Brazil is the largest exporter of orange juice concentrate, and yet, it has been extensively studied due to changes in taste and smell. Several investigations have reported d [...] ifferent culture media used to detect and enumerate Alicyiclobacillus spp. The objective of the present study was to evaluate the recovery of Alicyiclobacillus spp. spores grown in ALI, BAT, K agar and YSG media using the methodology suggested by ABECitrus. Five inocula were used, two from reference strains and three from pasteurized concentrated orange juice. Cell recovery after the enrichment in reconstituted orange juice was also analyzed. An initial population of 6 log CFU/mL was inoculated. ALI, BAT and YSG media were able to recover the initial population of all different inocula, with no significant differences between the results. When compared to BAT, however, the preparation of ALI and YSG media was simpler and had more advantages. The recovery with K agar medium was lower than the other media for all the tested inocula, with significant differences found for Alicyclobacillus acidocaldarius 0298T (3.66 log CFU/mL) and Alicyclobacillus pomorum-like CBMAI 0278 (4.11 log CFU/mL).

Márcia Maria, Anjos; Suelen Pereira, Ruiz; Benício Alves, Abreu Filho.

2014-04-01

254

Evaluation of droplet digital PCR for characterizing plasmid reference material used for quantifying ammonia oxidizers and denitrifiers  

OpenAIRE

DNA reference materials of certified value have a critical function in many analytical processes of DNA measurement. Quantification of amoA genes in ammonia oxidizing bacteria (AOB) and archaea (AOA), and of nirS and nosZ genes in the denitrifiers is very important for determining their distribution and abundance in the natural environment. A plasmid reference material containing nirS, nosZ, amoA-AOB, and amoA-AOA is developed to provide a DNA standard with copy number concentration for ensur...

Dong, Lianhua; Meng, Ying; Wang, Jing; Liu, Yingying

2014-01-01

255

Functional diversity in the denitrifying biofilm of the methanol-fed marine denitrification system at the Montreal Biodome.  

Science.gov (United States)

Nitrate is a serious problem in closed-circuit public aquariums because its accumulation rapidly becomes toxic to many lifeforms. A moving bed biofilm denitrification reactor was installed at the Montreal Biodome to treat its 3,250-m(3) seawater system. Naturally occurring microorganisms from the seawater affluent colonized the reactor carriers to form a denitrifying biofilm. Here, we investigated the functional diversity of this biofilm by retrieving gene sequences related to narG, napA, nirK, nirS, cnorB, and nosZ. A total of 25 sequences related to these genes were retrieved from the biofilm. Among them, the corresponding napA1, nirK1, cnorB9, and nosZ3 sequences were identical to the corresponding genes found in Hyphomicrobium sp. NL23 while the narG1 and narG2 sequences were identical to the two corresponding narG genes found in Methylophaga sp. JAM1. These two bacterial strains were previously isolated from the denitrifying biofilm. To assess the abundance of denitrifiers and nitrate respirers in the biofilm, the gene copy number of all the narG, napA, nirS, and nirK sequences found in biofilm was determined by quantitative PCR. napA1, nirK1, narG1, and narG2, which were all associated with either Methylophaga sp. JAM1 or Hyphomicrobium sp. NL23, were the most abundant genes. The other genes were 10 to 10,000 times less abundant. nirK, cnorB, and nosZ but not napA transcripts from Hyphomicrobium sp. NL23 were detected in the biofilm, and only the narG1 transcripts from Methylophaga sp. JAM1 were detected in the biofilm. Among the 19 other genes, the transcripts of only two genes were detected in the biofilm. Our results show the predominance of Methylophaga sp. JAM1 and Hyphomicrobium sp. NL23 among the denitrifiers detected in the biofilm. The results suggest that Hyphomicrobium sp. NL23 could use the nitrite present in the biofilm generated by nitrate respirers such as Methylophaga sp. JAM1. PMID:22006549

Auclair, Julie; Parent, Serge; Villemur, Richard

2012-05-01

256

Denitrifier communities in tank bromeliads and prospected N2O emissions from tank substrate upon increasing N-deposition  

Science.gov (United States)

It is well known that tropical rainforest soils with total emissions of 1.34 Tg N/yr from the tropics, play a significant role in the global N2O emissions scenarios. Significant contributions were reported particularly for tropical rainforest soils in South and Central America due to the large areas covered by rainforest in this region. In tropical rainforests of the Americas tank bromeliads constitute a prominent group of plants and were shown to significantly contribute to the production of the greenhouse gas methane from tropical forests. It is, however, essentially unknown whether and how bromeliads may contribute to the production of N2O, another important greenhouse gas. It is also unknown whether N2O emissions relate to atmospheric N-deposition and whether an increase in emissions is to be expected upon the prospected increase in N-deposition. We studied the propensity of tank substrate of the bromeliad Werauhia gladioliflora to emit N2O and how this potential is related to the underlying denitrifier communities. In tropical forests of Costa Rica Werauhia gladioliflora is very abundant with 9.85 specimen m-2. Incubation of the tank substrate with increasing amounts of fertilizer to reflect predicted N-deposition scenarios resulted in proportionally increasing net N2O production. Based on the abundance of Werauhia gladioliflora we estimated annual emissions of 395 µg N2O-N m-2 day-1 for N-deposition levels to date which is in the range of tropical soils. At a surplus of N 70% of N2O produced were not reduced leading to accumulation of N2O which agreed well with the finding that 95% of the denitrifiers detected lacked a gene encoding a N2O-reductase and are therefore unable to reduce N2O to dinitrogen. Generally, denitrifiers were highly abundant and ready to denitrify immediately after provision of a nitrogen source because carbon is non-limiting in tank substrate. Our results suggest that tank bromeliad substrate may be a significant source of N2O in neotropical forests and that with prospected increasing future N-depositions annual N2O emissions might increase.

Suleiman, Marcel; Brandt, Franziska; Brenzinger, Kristof; Martinson, Guntars; Braker, Gesche

2014-05-01

257

Application of a modified denitrifying bacteria method foranalyzing groundwater and vadose zone pore water nitrate at the HanfordSite, WA, USA.  

Energy Technology Data Exchange (ETDEWEB)

The Hanford Site in southern Washington contains a largeproportion of the 250,000 metric tons of nitrate estimated to reside atDOE sites across the USA. Nitrate concentrations>600 mg/L have beenreported for Hanford groundwaters, where nitrate commonly accompanieselevated levels of radionuclide contamination. Much of the Hanfordnitrate is stored in the vadose zone, where complicated hydrology andpoorly understood chemical and biochemical processes lead to uncertainfate and transport. Analysis of the nitrogen and oxygen isotopiccomposition of nitrate provides a promising method to identify sourcesand investigate biochemical degradation of nitrate in the subsurface atHanford. A preliminary investigation of NO3- fate and transport at theHanford Site focuses on pore water nitrate, extracted by 1:1 sediment toDI water rinses of vadose zone sediments, in a vertical profile through aradionuclide plume at the TX-TY tank farm, and compares these resultswith transects across major nitrate plumes in the Hanford unconfinedaquifer.Until recently, methods for analyzing d15N and d18O of NO3- inwaters were unwieldy for routine analyses of dilute groundwaters and porewater extracts from vadose zone sediments; however, Sigman, et al., 2001(Anal. Chem) and Casciotti, et al., 2002 (Anal. Chem), developed a methodusing denitrifying bacteria with a truncated enzymatic pathway togenerate N2O for analyzing both isotopes simultaneously from NO3- indilute samples. Our modifications to this method decrease both culturepreparation and sample processing times. Culturing time has been reducedto 2-3 days by increasing the initial inoculation volume to 2mL in 100mL.We grow cultures on a bench top and mix by inversion twice daily, insteadof growing on a constant shaking unit. These changes have not been shownto affect the cell yield nor the N2O levels in blanks. Secondly, cellpreparation for NO3- reduction has been modified to decrease sampleprocessing time. Intense centrifugation was found to be unnecessary andloose pellet formation at a lower g is more than adequate. We found nodetectable background level of N2O in the cultures, and have reduced thesample venting time. Lastly, we have found that samples can be injected,cells lysed, and N2O run in the same day with negligible affects to N2Oyield and d15N/d18O values.

Woods, KatharineN.; Singleton, Michael J.; Conrad, Mark

2003-11-18

258

Laser and gas centrifuge enrichment  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2014-05-09

259

Laser and gas centrifuge enrichment  

Science.gov (United States)

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.

Heinonen, Olli

2014-05-01

260

Uranium enrichment in Europe  

International Nuclear Information System (INIS)

Until the mid 1970's, the USA had a monopoly of separation work. There is now sufficient capacity at the Eurodif and Urenco plants for fully servicing Europe, but the Americans still have a large proportion of the European market. In 1984/85, the international market was determined by a series of basic decisions by the American market leader, which in turn were determined by the world-wide marketing activities of the European concerns Eurodif and Urenco. The author deals with the present situation in the world market for separation work, the recent decisions by the US Department of Energy (DOE) in enrichment technology, the setting to work of the enrichment plant at Urenco Germany at Gronau, the successes of the Urenco centrifuge technique and the state of laser enrichment. (orig.)

261

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

262

Nitrate-dependent anaerobic ferrous oxidation (NAFO) by denitrifying bacteria: a perspective autotrophic nitrogen pollution control technology.  

Science.gov (United States)

The nitrate-dependent anaerobic ferrous oxidation (NAFO) is an important discovery in the fields of microbiology and geology, which is a valuable biological reaction since it can convert nitrate into nitrogen gas, removing nitrogen from wastewater. The research on NAFO can promote the development of novel autotrophic biotechnologies for nitrogen pollution control and get a deep insight into the biogeochemical cycles. In this work, batch experiments were conducted with denitrifying bacteria as biocatalyst to investigate the performance of nitrogen removal by NAFO. The results showed that the denitrifying bacteria were capable of chemolithotrophic denitrification with ferrous salt as electron donor, namely NAFO. And the maximum nitrate conversion rates (qmax) reached 57.89 mg (g VSS d)?1, which was the rate-limiting step in NAFO. Fe/N ratio, temperature and initial pH had significant influences on nitrogen removal by NAFO process, and their optimal values were 2.0 °C, 30.15 °C and 8.0 °C, respectively. PMID:25461924

Zhang, Meng; Zheng, Ping; Wang, Ru; Li, Wei; Lu, Huifeng; Zhang, Jiqiang

2014-12-01

263

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)

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.

Marchetto Margarida

2003-01-01

264

Isolation of the {epsilon}-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin  

Energy Technology Data Exchange (ETDEWEB)

{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.

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

265

Influence of biofilm thickness on nitrous oxide (N2O) emissions from denitrifying fluidized bed bioreactors (DFBBRs).  

Science.gov (United States)

Nitrous oxide (N2O) is a significant anthropogenic greenhouse gas emitted from biological nutrient removal (BNR) processes. This study tries to get a deeper insight into N2O emissions from denitrifying fluidized bed bioreactors (DFBBRs) and its relationship to the biofilm thickness, diffusivity, and reaction rates. The DFBBR was operated at two different organic and nitrogen loading rates of 5.9–7 kg COD/(m3 d) and 1.2–2 kg N/(m3 d), respectively. Results showed that the N2O conversion rate from the DFBBR at a biofilm thickness of 680 ?m was 0.53% of the total influent nitrogen loading while at the limited COD and a biofilm thickness of 230 ?m, the N2O conversion rate increased by 196–1.57% of the influent nitrogen loading concomitant with a sevenfold increase in liquid nitrite concentration. Comparing the N2O emissions at different biofilm thickness showed that the N2O emission decreased exponentially with biofilm thickness due to the retention of slow growth denitrifiers and the limited diffusivity of N2O. PMID:25450644

Eldyasti, Ahmed; Nakhla, George; Zhu, Jesse

2014-12-20

266

Structure and function of denitrifying and nitrifying bacterial communities in relation to the plant species in a constructed wetland.  

Science.gov (United States)

The community structure and potential activities of nitrifying and denitrifying bacteria were studied in the rhizosphere of Typha latifolia and Phragmites australis present in a free water system constructed wetland (CW). Potential nitrate reduction and nitrification activities were shown to be significantly higher in the rhizosphere when compared with the nonvegetated sediment. Higher rates were generally obtained for P. australis. The community structure of denitrifying bacteria in the rhizosphere differed from that found at the bulk sediment, as revealed by PCR-denaturing gradient gel electrophoresis (DGGE) of the nitrous oxide reductase encoding gene nosZ. Results also show a greater nosZ genotype diversification and suggest a plant species effect in rhizosphere samples obtained during events of low hydraulic retention times. Ammonia-oxidizing communities were less complex on the basis of PCR-DGGE analysis of the 16S rRNA gene. Retrieved sequences were all related to Nitrosomonas marina and Nitrosomonas ureae, being both present in rhizosphere and bulk sediment regardless of environmental changes. The results demonstrate the effect of vegetation on the functioning and structure of bacterial communities involved in the removal of nitrogen in the treatment cells of a CW and point to the use of vegetation coverage to promote nitrification or denitrification in particular areas. PMID:19049502

Ruiz-Rueda, Olaya; Hallin, Sara; Bañeras, Lluis

2009-02-01

267

Quantitative response of nitrifying and denitrifying communities to environmental variables in a full-scale membrane bioreactor.  

Science.gov (United States)

The abundance and transcription levels of specific gene markers of total bacteria, ammonia-oxidizing Betaproteobacteria, nitrite-oxidizing bacteria (Nitrospira-like) and denitrifiers (N2O-reducers) were analyzed using quantitative PCR (qPCR) and reverse-transcription qPCR during 9 months in a full-scale membrane bioreactor treating urban wastewater. A stable community of N-removal key players was developed; however, the abundance of active populations experienced sharper shifts, demonstrating their fast adaptation to changing conditions. Despite constituting a small percentage of the total bacterial community, the larger abundances of active populations of nitrifiers explained the high N-removal accomplished by the MBR. Multivariate analyses revealed that temperature, accumulation of volatile suspended solids in the sludge, BOD5, NH4(+) concentration and C/N ratio of the wastewater contributed significantly (23-38%) to explain changes in the abundance of nitrifiers and denitrifiers. However, each targeted group showed different responses to shifts in these parameters, evidencing the complexity of the balance among them for successful biological N-removal. PMID:25043345

Gómez-Silván, C; Vílchez-Vargas, R; Arévalo, J; Gómez, M A; González-López, J; Pieper, D H; Rodelas, B

2014-10-01

268

Centrifuge enrichment program  

International Nuclear Information System (INIS)

Exxon Nuclear has been active in privately funded research and development of centrifuge enrichment technology since 1972. In October of 1975, Exxon Nuclear submitted a proposal to design, construct, and operate a 3000-MT SWU/yr centrifuge enrichment plant, under the provisions of the proposed Nuclear Fuel Assurance Act of 1975. The U.S. Energy Research and Development Administration (ERDA) accepted the proposal as a basis for negotiation. It was proposed to build a 1000-MT SWU/yr demonstration increment to be operational in 1982; and after successful operation for about one year, expand the facilities into a 3000-MT SWU/yr plant. As part of the overall centrifuge enrichment plant, a dedicated centrifuge manufacturing plant would be constructed; sized to support the full 3000-MT SWU/yr plant. The selection of the centrifuge process by Exxon Nuclear was based on an extremely thorough evaluation of current and projected enrichment technology; results show that the technology is mature and the process will be cost effective. The substantial savings in energy (about 93%) from utilization of the centrifuge option rather than gaseous diffusion is a compelling argument. As part of this program, Exxon Nuclear has a large hardware R and D program, plus a prototype centrifuge manufacturing capability in Malta, New York. To provide a full-scale machine and limited cascade test capability, Exxon Nuclear is constructing a $4,000,000 Centrifuge Test Facility in Richland, Washingtonfuge Test Facility in Richland, Washington. This facility was to initiate operations in the Fall of 1976. Exxon Nuclear is convinced that the centrifuge enrichment process is the rational selection for emergence of a commercial enrichment industry

269

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

270

Everyone Vegetarian, World Enriching  

OpenAIRE

This essay advocates global vegetarian diet. Firstly, seven personal health benefits and four global benefits of vegetarian dinners are specified to enrich the entire globe, and then, secondly, I explore concretely how to overcome internal hurdle and external hurdle, so as to effectively propagate vegetarian dinners throughout the world. Everyone wins, including animals!

Wu, John Y.

2014-01-01

271

Promotion of uranium enrichment business  

International Nuclear Information System (INIS)

The Committee on Nuclear Power has studied on the basic nuclear power policy, establishing its five subcommittees, entrusted by the Ministry of Nternational Trade and Industry. The results of examination by the subcommittee on uranium enrichment business are given along with a report in this connection by the Committee. In order to establish the nuclear fuel cycle, the aspect of uranium enrichment is essential. The uranium enrichment by centrifugal process has proceeded steadily in Power Reactor and Nuclear Fuel Development Corporation. The following matters are described: the need for domestic uranium enrichment, the outlook for overseas enrichment services and the schedule for establishing domestic enrichment business, the current state of technology development, the position of the prototype enrichment plant, the course to be taken to establish enrichment business the main organization operating the prototype and commercial plants, the system of supplying centrifuges, the domestic conversion of natural uranium the subsidies for uranium enrichment business. (J.P.N.)

272

Evaluation of uranium enrichment processes  

International Nuclear Information System (INIS)

Uranium enrichment is an important and complex business characterized by uncertainties in many key variables affecting enrichment program plans. Central to analysis of enrichment plans to meet specific objectives are technical and economic assessments, particularly for new processes. These enrichment process characteristics are considered in the context of enrichment business parameters; such as demand; production capacity and stockpile management; and feed requirements, availability, and costs. This paper presents a description of methodology and current results of evaluation of U.S. enrichment technologies, together with a summary of the strategic implications

273

Autotrophic carbon dioxide fixation via the Calvin-Benson-Bassham cycle by the denitrifying methanotroph "Candidatus Methylomirabilis oxyfera".  

Science.gov (United States)

Methane is an important greenhouse gas and the most abundant hydrocarbon in the Earth's atmosphere. Methanotrophic microorganisms can use methane as their sole energy source and play a crucial role in the mitigation of methane emissions in the environment. "Candidatus Methylomirabilis oxyfera" is a recently described intra-aerobic methanotroph that is assumed to use nitric oxide to generate internal oxygen to oxidize methane via the conventional aerobic pathway, including the monooxygenase reaction. Previous genome analysis has suggested that, like the verrucomicrobial methanotrophs, "Ca. Methylomirabilis oxyfera" encodes and transcribes genes for the Calvin-Benson-Bassham (CBB) cycle for carbon assimilation. Here we provide multiple independent lines of evidence for autotrophic carbon dioxide fixation by "Ca. Methylomirabilis oxyfera" via the CBB cycle. The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), a key enzyme of the CBB cycle, in cell extracts from an "Ca. Methylomirabilis oxyfera" enrichment culture was shown to account for up to 10% of the total methane oxidation activity. Labeling studies with whole cells in batch incubations supplied with either (13)CH4 or [(13)C]bicarbonate revealed that "Ca. Methylomirabilis oxyfera" biomass and lipids became significantly more enriched in (13)C after incubation with (13)C-labeled bicarbonate (and unlabeled methane) than after incubation with (13)C-labeled methane (and unlabeled bicarbonate), providing evidence for autotrophic carbon dioxide fixation. Besides this experimental approach, detailed genomic and transcriptomic analysis demonstrated an operational CBB cycle in "Ca. Methylomirabilis oxyfera." Altogether, these results show that the CBB cycle is active and plays a major role in carbon assimilation by "Ca. Methylomirabilis oxyfera" bacteria. Our results suggest that autotrophy might be more widespread among methanotrophs than was previously assumed and implies that a methanotrophic community in the environment is not necessarily revealed by (13)C-depleted lipids. PMID:24509918

Rasigraf, Olivia; Kool, Dorien M; Jetten, Mike S M; Sinninghe Damsté, Jaap S; Ettwig, Katharina F

2014-04-01

274

Characterization of a murine neuron-enriched model of primary trigeminal ganglia cultures to study the interferon- ? antiviral effect against Herpes Simplex Virus type 1 / Caracterización de un modelo murino de cultivos primarios de ganglio trigeminal enriquecido en neuronas para el estudio del efecto antiviral del interferón- ? frente al virus Herpes simple tipo 1  

Scientific Electronic Library Online (English)

Full Text Available Objetivo: Caracterizar un cultivo primario de ganglio trigeminal (GT) enriquecido en neuronas y evaluar la expresión de interferón- y su actividad frente a la infección con Herpes simple tipo 1 (HSV-1). Materiales y métodos: El porcentaje de neuronas fue determinado por inmunocitoquímica para neurof [...] ilamento. Los cultivos fueron tratados con interferón- ? e infectados con HSV-1, y se cuantificaron las células positivas para antígeno viral por inmunocitoquímica y la expresión de interferón- ? por PCR cuantitativa. Resultados: El cultivo presentó un 15% de neuronas y 85% de células no neuronales. Se encontró efecto citopático, asociado a una alta diseminación de la infección (72,9% neuronas y 48,3% de células no neuronales positivas para antígeno viral). El interferón- ? evitó la aparición de efecto citopático y disminuyó las células infectadas a 16,7% en neuronas y a 7,8% las células no neuronales. La infección viral incrementó la expresión de transcritos de interferón- ? 18,2 veces a las 6 h de infección, mientras que a las 18 h post infección el tratamiento con interferón incrementó esta expresión 3,7 veces. Discusión: Los cultivos presentaron un 15% de neuronas, lo cual es 10 veces más que en otros cultivos reportados. Las células no neuronales representan el 85% de las células del cultivo, y se evidenció que todos los tipos de células se infectaron; similar a lo que ha sido reportado durante infecciones agudas in vivo . Adicionalmente, el interferón- ? disminuyó el porcentaje de células infectadas y evitó la aparición de efecto citopático, similar a lo que ha sido reportado en cultivos de GT porcino. Conclusiones: Se caracterizó un modelo de cultivo primario de GT enriquecido en neuronas. Interferón- ? protegió las células del efecto citopático y la diseminación viral mientras que la infección viral incrementó la expresión de interferón- ?. Por lo tanto, el interferón- ? ejerció un papel antiviral importante frente al HSV-1 en estos cultivos. Abstract in english Objective: To characterize a neuron-enriched primary TG culture and evaluate interferon- ? expression and activity after HSV-1 infection. Materials and methods: The percentage of neurons present in cultures was assessed by neurofilament immunocytochemistry. Cultures were treated with interferon- ? a [...] nd infected with HSV-1, then viral antigen positive cells were counted and interferon- ?expression was assessed by quantitative PCR. Results: The culture contained 15% neurons and 85% non-neuronal cells. A cytopathic effect was observed, associated with high viral spread (72.9% neurons and 48.3% non-neuronal cells were positive for viral antigen). Interferon- ? treatment impaired the cytopathic effect and decreased the infected neurons to 16.7% and infected non-neuronal cells to 7.8%. Viral infection at 6 h postinfection significantly increased the interferon- ? transcripts by 18.2 fold, while at 18 h postinfection Interferon pre-treatment in infected cultures increased interferon- ? transcription by 3.7 fold. Discussion: This culture model contained 15% neurons, which is 10 times higher compared to other reported cultures, and non-neuronal cells comprised 85% of cells in this culture. All types of cells were found to be infected, which is similar to that reported during acute infections in vivo . Additionally, interferon- ?decreased the infected cells, avoiding the cytopathic effect, which is similar to that reported in swine TG cultures. Conclusions: A neuron-enriched primary TG model was characterized. Interferon- ? treatment protected cells from cytopathic effects and viral spread, while viral infection up-regulated interferon- ? expression. This result means that interferon- ? exerts an important antiviral effect against HSV-1 in these cultures.

Ana Maria, Low-Calle; Jeanette, Prada-Arismendy; Jaime E., Castellanos.

2014-06-01

275

South Australia, uranium enrichment  

International Nuclear Information System (INIS)

The Report sets out the salient data relating to the establishment of a uranium processing centre at Redcliff in South Australia. It is conceived as a major development project for the Commonwealth, the South Australian Government and Australian Industry comprising the refining and enrichment of uranium produced from Australian mines. Using the data currently available in respect of markets, demand, technology and possible financial return from overseas sales, the project could be initiated immediately with hexafluoride production, followed rapidly in stages by enrichment production using the centrifuge process. A conceptual development plan is presented, involving a growth pattern that would be closely synchronised with the mining and production of yellowcake. The proposed development is presented in the form of an eight-and-half-year programme. Costs in this Report are based on 1975 values, unless otherwise stated. (Author)

276

Development of enrichment techniques  

International Nuclear Information System (INIS)

The experience accumulated in operating the older uranium enrichment plants in Almelo and Capenhurst was the basis for the construction of the Gronau centrifuge plant commissioned in August 1985 after three and a half years of construction. The total capacity of the three Urenco plants as of late 1992 is 2750 t SWU/a. The goal set at the beginning of centrifuge development, i.e. to achive troublefree operation of the centrifuges for more than ten years, has been attained. Enrichment by centrifuges on the whole consumes less than one permil of the electric power generated. Economic calculations show that a laser plant is hardly able to underrun the costs of separative work of a centrifuge plant. (orig.)

277

Simultaneous removal of organic matter and nitrogen by a heterotrophic nitrifying-aerobic denitrifying bacterial strain in a membrane bioreactor.  

Science.gov (United States)

A heterotrophic nitrifying-aerobic denitrifying bacterial strain, Bacillus methylotrophicus L7, was inoculated solely into a submerged membrane bioreactor (MBR) for continuous treatment of artificial sewage. The running conditions were also optimized for improvement of the treatment efficiency. The results indicated that inoculation of this single strain in a single reactor under constant aerobic conditions resulted in simultaneous removal of organic matter and nitrogen, in striking contrast to traditional aerobic nitrification-anaerobic denitrification treatment system and the sequencing batch reactor (SBR) systems. The optimal running conditions for the MBR were dissolved oxygen (DO) 4.5 mg/L, pH 7.5, loading ammonia <100 mg/L, and C/N ratio 3.5. Under these conditions, the removal percentages of chemical oxygen demand (COD), NH4(+)-N, and TN as high as 96%, 77.5% and 53%, respectively, were achieved without nitrite accumulation. PMID:23792656

Yao, Yan-Chun; Zhang, Qing-Ling; Liu, Ying; Liu, Zhi-Pei

2013-09-01

278

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

Science.gov (United States)

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 tea soil. PMID:25273518

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

2015-03-01

279

Transitions in nirS-type Denitrifier Diversity, Community Composition, and Biogeochemical Activity along the Chesapeake Bay Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Chesapeake Bay, the largest estuary in North America, can be characterized as having steep and opposing gradients in salinity and dissolved inorganic nitrogen along the main axis of the Bay. In this study, the diversity of nirS gene fragments (encoding cytochrome cd1-type nitrite reductase, physical/chemical parameters, and benthic N2-fluxes were analyzed in order to determine how denitrifier communities and biogeochemical activity vary along the estuary salinity gradient. The nirS gene fragments were PCR-amplified, cloned, and sequenced from sediment cores collected at five stations. Sequence analysis of 96 to 123 nirS clones from each station revealed extensive overall diversity in this estuary, as well as distinct spatial structure in the nirS sequence distributions. Both nirS-based richness and community composition varied among stations, with the most dramatic shifts occurring between low-salinity (oligohaline and moderate-salinity (mesohaline sites. For four samples collected in April, the nirS-based richness, nitrate concentrations, and N2-fluxes all decreased in parallel along the salinity gradient from the oligohaline northernmost station to the highest salinity (polyhaline station near the mouth of the Bay. The vast majority of the 550 nirS sequences were distinct from cultivated denitrifiers, although many were closely related to environmental clones from other coastal and estuarine systems. Interestingly, 8 of the 172 OTUs identified accounted for 42% of the total nirS clones, implying the presence of a few dominant and many rare genotypes, which were distributed in a non-random manner along the salinity gradient of Chesapeake Bay. These data, comprising the largest dataset to investigate nirS clone sequence diversity from an estuarine environment, also provided information that was required for the development of nirS microarrays to investigate the interaction of microbial diversity, environmental gradients, and biogeochemical activity.

ChristopherAFrancis

2013-08-01

280

Denitrification of groundwater using a sulfur-oxidizing autotrophic denitrifying anaerobic fluidized-bed MBR: performance and bacterial community structure.  

Science.gov (United States)

This paper investigates a novel sulfur-oxidizing autotrophic denitrifying anaerobic fluidized bed membrane bioreactor (AnFB-MBR) that has the potential to overcome the limitations of conventional sulfur-oxidizing autotrophic denitrification systems. The AnFB-MBR produced consistent high-quality product water when fed by a synthetic groundwater with NO3 (-)-N ranging 25-80 mg/L and operated at hydraulic retention times of 0.5-5.0 h. A nitrate removal rate of up to 4.0 g NO3 (-)-N/Lreactord was attained by the bioreactor, which exceeded any reported removal capacity. The flux of AnFB-MBR was maintained in the range of 1.5-15 L m(-2) h(-1). Successful membrane cleaning was practiced with cleaning cycles of 35-81 days, which had no obvious effect on the AnFB-MBR performance. The (15)?N-tracer analyses elucidated that nitrogen was converted into (15)?N2-N and (15)?N-biomass accounting for 88.1-93.1 % and 6.4-11.6 % of the total nitrogen produced, respectively. Only 0.3-0.5 % of removed nitrogen was in form of (15)N2O-N in sulfur-oxidizing autotrophic denitrification process, reducing potential risks of a significant amount of N2O emissions. The sulfur-oxidizing autotrophic denitrifying bacterial consortium was composed mainly of bacteria from Proteobacteria, Chlorobi, and Chloroflexi phyla, with genera Thiobacillus, Sulfurimonas, and Ignavibacteriales dominating the consortium. The pyrosequencing assays also suggested that the stable microbial communities corresponded to the elevated performance of the AnFB-MBR. Overall, this research described relatively high nitrate removal, acceptable flux, indicating future potential for the technology in practice. PMID:25343972

Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Qu, Jiuhui

2015-03-01

281

Spatiotemporal relationships between the abundance, distribution, and potential activities of ammonia-oxidizing and denitrifying microorganisms in intertidal sediments.  

Science.gov (United States)

The primary objective of this study was to gain an understanding of how key microbial communities involved in nitrogen cycling in estuarine sediments vary over a 12-month period. Furthermore, we sought to determine whether changes in the size of these communities are related to, or indicative of, seasonal patterns in fixed nitrogen dynamics in Elkhorn Slough--a small, agriculturally impacted estuary with a direct connection to Monterey Bay. We assessed sediment and pore water characteristics, abundance of functional genes for nitrification (bacterial and archaeal amoA, encoding ammonia monooxygenase subunit A) and denitrification (nirS and nirK, encoding nitrite reductase), and measurements of potential nitrification and denitrification activities at six sites. No seasonality in the abundance of denitrifier or ammonia oxidizer genes was observed. A strong association between potential nitrification activity and the size of ammonia-oxidizing bacterial communities was observed across the estuary. In contrast, ammonia-oxidizing archaeal abundances remained relatively constant in space and time. Unlike many other estuaries, salinity does not appear to regulate the distribution of ammonia-oxidizing communities in Elkhorn Slough. Instead, their distributions appear to be governed over two different time scales. Long-term niche characteristics selected for the gross size of archaeal and bacterial ammonia-oxidizing communities, yet covariation in their abundances between monthly samples suggests that they respond in a similar manner to short-term changes in their environment. Abundances of denitrifier and ammonia oxidizer genes also covaried, but site-specific differences in this relationship suggest differing levels of interaction (or coupling) between nitrification and denitrification. PMID:25038845

Smith, Jason M; Mosier, Annika C; Francis, Christopher A

2015-01-01

282

Community structures and activity of denitrifying microbes in a forested catchment in central Japan: survey using nitrite reductase genes  

Science.gov (United States)

To elucidate the mechanisms of denitrification processes in the forested catchment, microbial ecological approaches have been applied in an experimental watershed that has previously investigated its hydrological processes. The study catchment is located in the Chiba prefecture in central Japan under the temperate Asian monsoon climate. Potential activities of denitrification of soil samples were measured by incubation experiments under anoxic condition associated with Na15NO3 addition. Existence and variety of microbes having nitrite reductase genes were investigated by PCR amplification, cloning and sequencings of nirK and nirS fragments after DNA extraction. Contrary to our early expectation that the potential denitrification activity was higher at deeper soil horizon with consistent groundwater residence than that in the surface soil, denitrification potential was higher in shallower soil horizons than deeper soils. This suggested that the deficiency of NO3- as a respiratory substrate for denitrifier occurred in deeper soils especially in the summer. However, high denitrification activity and presence of microbes having nirK and nirS in surface soils usually under aerobic condition was explainable by the fact that the majority of denitrifying bacteria have been recognized as a facultative anaerobic bacterium. This also suggests the possibility of that denitrification occurs even in the surface soils if the wet condition is provided by rainwater during and after a storm event. Community structures of microbes having nirK were different between near surface and deeper soil horizons, and ones having nirS was different between saturated zone (under groundwater table) and unsaturated soil horizons. These imply that microbial communities with nisK are sensitive to the concentration of soil organic matters and ones with nirS is sensitive to soil moisture contents.

Ohte, N.; Aoki, M.; Katsuyama, C.; Suwa, Y.; Tange, T.

2012-12-01

283

Fostering Earth Science Inquiry From Within a Native Hawaiian Cultural Framework In O`ahu (Hawai`i) Through A Multidisciplinary Place-Based High School Summer Enrichment Program  

Science.gov (United States)

During the summer of 2010, twenty-five public high school students from underrepresented communities and ethnicities (Hawaiian, part-Hawaiian, S?moan, Filipino, Pacific Islander) in O`ahu (Hawai`i) participated in the M?lama Ke Ahupua`a (protecting our watershed) program. This rigorous three-week hands-on, place-based multidisciplinary program provided students with the opportunity of visiting the M?noa Valley watershed (O`ahu, Hawaii) for learning and experiencing the Earth Science System dynamics that comprises it, while simultaneously exploring the significance of the ahupua`a (watershed) as related to native Hawaiian history and culture. While earning Hawaii DOE-approved academic credit, students utilized GPS/GIS technology, quantitative water quality testing equipment, and environmental monitoring tools for performing a watershed survey and water quality study of M?noa Stream (M?noa Valley) from its inception in the mountains, its advance through Honolulu’s urbanized areas, and its convergence with the Pacific Ocean. Through this hands-on field-based study, students documented changes in the watershed’s environment as reflected in declining water quality induced by anthropogenic pollution sources and urbanization. Students also visited relevant native Hawaiian cultural sites in M?noa, and explored their direct links with the historical sustainable usage of the watershed’s natural resources, both from a cultural and science-based perspective. Finally, traditional wa`a (native Hawaiian outrigger canoes) were used as both cultural resources for discussing ancient Polynesian exploration, as well as scientific research platforms for conducting near-shore reef surveys & assessments. This program served to promote not only Earth Science literacy and STEM skills, but also contributed to further environmental stewardship while fostering native Hawaiian & Polynesian cultural identities.

Moxey, L.; Dias, R.; Legaspi, E.

2010-12-01

284

Beta activity of enriched uranium  

International Nuclear Information System (INIS)

Use of enriched uranium as reactor fuel necessitates its handling in various forms. For purposes of planning and organising radiation protection measures in enriched uranium handling facilities, it is necessary to have a basic knowledge of the radiation status of enriched uranium systems. The theoretical variations in beta activity and energy with U235 enrichment are presented. Depletion is considered separately. Beta activity build up is also studied for two specific enrichments, in respect of which experimental values for specific alpha activity are available. (author)

285

Evaluation of the microbial diversity in sequencing batch reactor treating linear alkylbenzene sulfonate under denitrifying and mesophilic conditions using swine sludge as inoculum  

Scientific Electronic Library Online (English)

Full Text Available The objective of this study was to evaluate the degradation of Linear Alkylbenzene Sulfonate (LAS) in anaerobic sequencing batch reactor (ASBR) under denitrifying conditions using swine sludge as inoculum. The reactor was operated for 104 days with synthetic substrate containing nitrate, and LAS was [...] added later (22 mg/L). Considering the added mass of the LAS, the adsorbed mass in the sludge and discarded along with the effluent, degradation of the surfactant at the end of operation was 87%, removal of chemical oxygen demand was 86% and nitrate was 98%. The bacterial community was evaluated by cutting the bands and sequencing of polymerase chain reaction (PCR) fragments and denaturing gradient gel electrophoresis (DGGE). The sequences obtained were related to the phylum Proteobacteria and the alpha-and beta-proteobacteria classes, these bacteria were probably involved in the degradation of LAS. The efficiently degraded LAS in the reactor was operated in batch sequences in denitrifying conditions.

Iolanda Cristina Silveira, Duarte; Lorena Lima de, Oliveira; Dagoberto Yukio, Okada; Pierre Ferreira do, Prado; Maria Bernadete Amâncio, Varesche.

286

Rectoanal Mucosal Swab Culture Is More Sensitive Than Fecal Culture and Distinguishes Escherichia coli O157:H7-Colonized Cattle and Those Transiently Shedding the Same Organism  

OpenAIRE

Enrichment and direct (nonenrichment) rectoanal mucosal swab (RAMS) culture techniques were developed and compared to traditional fecal culture for the detection of Escherichia coli O157:H7 in experimentally infected and naturally infected cattle. Holstein steers (n = 16) orally dosed with E. coli O157:H7 were sampled after bacterial colonization starting 15 days postinoculation. Enrichment RAMS cultures (70.31% positive) were more sensitive than enrichment fecal cultures with 10 g of feces (...

Rice, Daniel H.; Sheng, Haiqing Q.; Wynia, Stacey A.; Hovde, Carolyn J.

2003-01-01

287

Structural Monitoring of Oligosaccharides through 13C Enrichment and NMR Observation of Acetyl Groups  

OpenAIRE

Structural characterization of biomolecules by NMR methods frequently requires the enrichment of magnetically active isotopes at particular molecular sites. Introduction is usually achieved biosynthetically through the use of bacterial cultures grown on isotopically enriched media, but for certain types of molecules—cell-surface carbohydrates of mammalian origin, for example—this is not practical. Here we explore a means of introducing 13C-enriched sites, postisolation in natural carbohyd...

Yu, Fei; Prestegard, J. H.

2006-01-01

288

Abundance and Diversity of Bacterial Nitrifiers and Denitrifiers and Their Functional Genes in Tannery Wastewater Treatment Plants Revealed by High-Throughput Sequencing  

OpenAIRE

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 ch...

Wang, Zhu; Zhang, Xu-xiang; Lu, Xin; Liu, Bo; Li, Yan; Long, Chao; Li, Aimin

2014-01-01

289

Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.  

Science.gov (United States)

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, whereas changes in microbial abundance play a major role for non-facultative activities such as nitrification. PMID:23613785

Le Roux, Xavier; Schmid, Bernhard; Poly, Franck; Barnard, Romain L; Niklaus, Pascal A; Guillaumaud, Nadine; Habekost, Maike; Oelmann, Yvonne; Philippot, Laurent; Salles, Joana Falcao; Schloter, Michael; Steinbeiss, Sibylle; Weigelt, Alexandra

2013-01-01

290

Insights into the effect of soil pH on N2O and N2 emissions and denitrifier community size and activity.  

Czech Academy of Sciences Publication Activity Database

Ro?. 76, ?. 6 (2010), s. 1870-1878. ISSN 0099-2240 R&D Projects: GA MŠk MEB020726; GA MŠk LC06066; GA AV ?R IAA600660605 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil pH * N 2 O and N 2 emissions * denitrifier community Subject RIV: EH - Ecology, Behaviour Impact factor: 3.778, year: 2010

?uhel, Ji?í; Šimek, Miloslav; Laughlin, R.J.; Bru, D.; Chéneby, D.; Watson, C.J.; Philippot, L.

2010-01-01

291

Enrichment and activity of methanotrophic microorganisms from municipal wastewater sludge.  

Science.gov (United States)

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

Siniscalchi, Luciene Alves Batista; Vale, Isabel Campante; Dell'Isola, Jéssica; Chernicharo, Carlos Augusto; Calabria Araujo, Juliana

2015-06-01

292

Biomedical advances from tissue culture  

OpenAIRE

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 ...

Okamoto, Tetsuji; Sato, J. Denry; Barnes, David W.; Sato, Gordon H.

2013-01-01

293

Tissue culture: the unrealized potential  

OpenAIRE

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...

Sato, Gordon

2007-01-01

294

Abundance and Diversity of Bacterial Nitrifiers and Denitrifiers and Their Functional Genes in Tannery Wastewater Treatment Plants Revealed by High-Throughput Sequencing  

Science.gov (United States)

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. PMID:25420093

Wang, Zhu; Zhang, Xu-Xiang; Lu, Xin; Liu, Bo; Li, Yan; Long, Chao; Li, Aimin

2014-01-01

295

Enrichment of boron 10  

International Nuclear Information System (INIS)

A isotopic separation pilot plant with five ion exchange columns interconnected in series were designed and built in the IEN. The columns are charged with a strong anionic resin in its alkaline form. The boric acid solution is introduced in the separation columns until it reaches a absorbing zone length which is sufficient to obtain the desired boron-10 isotopic concentration. The boric acid absorbing zone movement is provided by the injection of a diluted hydrochloric acid solution, which replace the boric acid throughout the columns. The absorbing zone equilibrium length is proportional to its total length. The enriched boron-10 and the depleted boron are located in the final boundary and in the initial position of the absorbing zones, respectively. (author)

296

Mineralization of Diethylthiophosphoric Acid by an Enriched Consortium from Cattle Dip  

OpenAIRE

Enrichment cultures were initiated from cattle dip solution with diethylthiophosphoric acid (DETP) as the carbon and energy source. An enriched consortium consisting of at least six distinct bacterial species was subsequently obtained. The consortium mineralized DETP to sulfate and phosphate while utilizing ethyl moieties as a carbon and energy source. These data demonstrate that DETP can be metabolized under environmentally realistic conditions.

Shelton, Daniel R.

1988-01-01

297

Industrial aspects in uranium enrichment  

International Nuclear Information System (INIS)

Characteristics of isotope separation processes in operation and under development are discussed. These include the number of stages in series, the number of components, the component unit capacity and enery requirements. The implementation of an enrichment process and the question of an enrichment plant in Australia are also considered

298

A cytochrome cd1-type nitrite reductase isolated from the marine denitrifier Pseudomonas nautica 617: purification and characterization.  

Science.gov (United States)

Nitrite reductase (cytochrome cd1) was purified to electrophoretic homogeneity from the soluble extract of the marine denitrifying bacterium Pseudomonas nautica strain 617. Cells were anaerobically grown with 10 mM nitrate as final electron acceptor. The soluble fraction was purified by four successive chromatographic steps and the purest cytochrome cd1 exhibited an A280 nm(oxidized)/A410nm(oxidized) coefficient of 0.90. In the course of purification, cytochrome cd1 specific activity presented a maximum value of 0.048 units/mg of protein. This periplasmic enzyme is a homodimer and each 60 kDa subunit contains one heme c and one heme d1 as prosthetic moieties, both in a low spin state. Redox potentials of hemes c and d1 were determined at three different pH values (6.6, 7.6 and 8.6) and did not show any pH dependence. The first 20 amino acids of the NH2-terminal region of the protein were identified and the sequence showed 45% identity with the corresponding region of Pseudomonas aeruginosa nitrite reductase but no homology to Pseudomonas stutzeri and Paracoccus denitrificans enzymes. Spectroscopic properties of Pseudomonas nautica 617 cytochrome cd1 in the ultraviolet-visible range and in electron paramagnetic resonance are described. The formation of a heme d1 -nitric-oxide complex as an intermediate of nitrite reduction was demonstrated by electron paramagnetic resonance experiments. PMID:16887530

Besson, S; Carneiro, C; Moura, J J; Moura, I; Fauque, G

1995-08-01

299

Characterization of a 7Fe ferredoxin isolated from the marine denitrifier Pseudomonas nautica strain 617: spectroscopic and electrochemical studies.  

Science.gov (United States)

A 7Fe ferredoxin, isolated from the marine denitrifier Pseudomonas nautica strain 617, was characterized. The NH2-terminal sequence analysis, performed until residue number 56, shows a high similarity with the 7Fe ferredoxins isolated from Azotobacter vinelandii, Pseudomonas putida, and Pseudomonas stutzeri. EPR and NMR spectroscopies identify the presence of both [3Fe-4S] and [4Fe-4S] clusters, with cysteinyl coordination. The electrochemical studies on [Fe-S] clusters show that a fast diffusion-dominated electron transfer, promoted by Mg(II), takes place between the ferredoxin and the glassy carbon electrode. Square wave voltammetry studies gave access to the electrosynthesis of a 4Fe center formed within the [3Fe-4S] core. The [3Fe-4S] cluster exhibited two reduction potentials at -175 and -680 +/- 10 mV and the [4Fe-4S] cluster was characterized by an unusually low reduction potential of -715 +/- 10 mV, at pH 7.6 PMID:8954931

Macedo, A L; Besson, S; Moreno, C; Fauque, G; Moura, J J; Moura, I

1996-12-13

300

New generation enrichment monitoring technology for gas centrifuge enrichment plants  

Energy Technology Data Exchange (ETDEWEB)

The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF{sub 6} containing low enriched (approximately 4% {sup 235}U) and highly enriched (above 20% {sup 235}U) uranium. This instrument used the 22-keV line from a {sup 109}Cd source as a transmission source to achieve a high sensitivity to the UF{sub 6} gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF{sub 6} product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

Ianakiev, Kiril D [Los Alamos National Laboratory; Alexandrov, Boian S. [Los Alamos National Laboratory; Boyer, Brian D. [Los Alamos National Laboratory; Hill, Thomas R. [Los Alamos National Laboratory; Macarthur, Duncan W. [Los Alamos National Laboratory; Marks, Thomas [Los Alamos National Laboratory; Moss, Calvin E. [Los Alamos National Laboratory; Sheppard, Gregory A. [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory

2008-06-13

301

New generation enrichment monitoring technology for gas centrifuge enrichment plants  

International Nuclear Information System (INIS)

The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF6 containing low enriched (approximately 4% 235U) and highly enriched (above 20% 235U) uranium. This instrument used the 22-keV line from a 109Cd source as a transmission source to achieve a high sensitivity to the UF6 gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF6 product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

302

Uranium enrichment by centrifuges  

International Nuclear Information System (INIS)

After having built the pilot plants and industrial demonstration plants in Great Britain and the Netherlands, now, besides the British and Dutch plants being built, another plant with an annual capacity of 1000 t UTA with centrifuge is planned on a German site. After having examined a number of potential sites, Gronau in the region Muensterland was selected. In March 1979, a settling contract was signed by the city of Gronau and the Uranit Company for the Urenco Deutschland oHG and the M.A.N.-Uranit Gronau GmbH. By the end of 1980, within the frame of the licensing procedure the expert's report on the 1st TEG covering the conventional technique and the operational part was finished. According to the time schedule, the 1st TEG is expected in the second quarter of 1981. Thus, the start-up might take place in the first quarter of 1984. The plant concept which the uranium enrichment plant Gronau was based on and which is dealt with closely allows a step-by-step construction with the first section of 400 t UTA possibly ready for start-up by the mid eighties. The development potential of the centrifuges seems to allow an essential reduction in the plant expenses from the mid of the eighties on. (orig./UA)

303

Analysis of enrichment factor of uranium enrichment by Redox chromatography  

International Nuclear Information System (INIS)

Experiments and computer simulation show that the uranium enrichment factor in redox chromatography is determined substantially be electron exchange, isotope adsorption-desorption, and oxidation state adsorption-desorption equilibria. Computer simulation utilizing the theoretical model closely predicts the difference between the value of an enrichment factor derived from the solution equilibrium and that observed in the chromatographic isotope separation, which is attributable to a biased distribution of uranium ions between the solid and liquid phases and a nonequilibrium state in the separation column, thus allowing elucidation of the separation mechanism. A theoretical description of the central role of this enrichment factor in determining plant size and economics is presented

304

Bacterivory by benthic organisms in sediment : Quantification using 15N-enriched bacteria  

OpenAIRE

The fate of benthic bacterial biomass in benthic food webs is a topic of major importance but poorly described. This paper describes an alternative method for evaluation of bacterial grazing rate by meiofauna and macrofauna using bacteria pre-enriched with stable isotopes. Natural bacteria from the sediment of an intertidal mudflat were cultured in a liquid medium enriched with 15NH4Cl. Cultured bacteria contained 2.9% of 15N and were enriched sufficiently to be used as tracers during grazing...

Pascal, P. Y.; Dupuy, C.; Mallet, C.; Richard, P.; Niquil, N.

2008-01-01

305

Enrichment and terminal differentiation of striated muscle progenitors in vitro  

International Nuclear Information System (INIS)

Enrichment and terminal differentiation of mammalian striated muscle cells is severely hampered by fibroblast overgrowth, de-differentiation and/or lack of functional differentiation. Herein we report a new, reproducible and simple method to enrich and terminally differentiate muscle stem cells and progenitors from mice and humans. We show that a single gamma irradiation of muscle cells induces their massive differentiation into structurally and functionally intact myotubes and cardiomyocytes and that these cells can be kept in culture for many weeks. Similar results are also obtained when treating skeletal muscle-derived stem cells and progenitors with Mitomycin C.

306

Hydrogen-enriched fuels  

Energy Technology Data Exchange (ETDEWEB)

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.

Roser, R. [NRG Technologies, Inc., Reno, NV (United States)

1998-08-01

307

Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria  

Directory of Open Access Journals (Sweden)

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.

T. Yamazaki

2013-10-01

308

Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria  

Science.gov (United States)

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.

Yamazaki, T.; Hozuki, T.; Arai, K.; Toyoda, S.; Koba, K.; Fujiwara, T.; Yoshida, N.

2014-05-01

309

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)

310

High enrichment to low enrichment core's conversion. Accidents analysis  

International Nuclear Information System (INIS)

This work analyzes the different accidents that may occur in the reactor's facility after the 20% high-enriched uranium core's conversion. 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 %. This analysis includes: a) accidents by reactivity insertion; b) accidents by coolant loss; c) analysis by flow loss and d) fission products release. (Author)

311

31 CFR 540.316 - Uranium enrichment.  

Science.gov (United States)

...2010-07-01 2010-07-01 false Uranium enrichment. 540.316 Section 540.316 Money...REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium enrichment means the process of increasing the...

2010-07-01

312

Enriching rotifers with "premium" microalgae. Nannochloropsis gaditana.  

Science.gov (United States)

The nutritive quality of Nannochloropsis gaditana cultured semicontinuously with different daily renewal rates was tested as a diet for short-term enrichment of the rotifer Brachionus plicatilis. After 24 h, dramatic differences in the survival, dry weight, and biochemical composition of the rotifers depending on the renewal rate of microalgal cultures were observed. Survival after the feeding period increased with increasing renewal rates. Rotifers fed microalgae from low renewal rate, nutrient-deficient cultures showed low dry weight and organic contents very similar to those of the initial rotifers that were starved for 12 h before the start of the feeding period. On the contrary, rotifers fed nutrient-sufficient microalgal cells underwent up to twofold increases of dry weight and protein, lipid, and carbohydrate contents with regard to rotifers fed nutrient-depleted N. gaditana. Consequently, feed conversion rate decreased in these conditions, indicating a better assimilation of the microalgal biomass obtained at high renewal rates. No single microalgal biochemical parameter among those studied can explain the response of the filter feeder. Similarly to gross composition, EPA and n-3 contents in rotifers fed microalgae from nutrient-sufficient cultures were double than the contents found in rotifers fed nutrient-limited microalgae. In addition, very high positive correlations between the contents of EPA and n-3 in N. gaditana and B. plicatilis were observed. These results demonstrate that selecting the appropriate conditions of semicontinuous culture can strongly enhance the nutritional value of microalgae that is reflected in the growth and biochemical composition of the filter-feeder even in short exposure periods. PMID:19153793

Ferreira, Martiña; Coutinho, Paula; Seixas, Pedro; Fábregas, Jaime; Otero, Ana

2009-01-01

313

Uranium enrichment by chemical exchange  

International Nuclear Information System (INIS)

This article presents the new French process for enriching uranium by chemical methods, the development of which was announced at the international conference on the Fuel Cycle, in Salzburg in May 1977. After a brief summary of the necessity for using nuclear energy, the importance of the fuel cycle, and the position of uranium enrichment in this cycle, the situation in the enrichment market is described together with the various enriching processes which are being or can soon be developed industrially on a large scale. A more detailed description is given of the principle of chemical exchange processes. A few important features of the French process from the economical or political aspect are then explained, in particular its non-proliferating nature

314

Tritium enrichment by gas chromatography  

International Nuclear Information System (INIS)

Hydrogen gas was used in the enrichment. Molecular sieve 4A was found to be the most suitable adsorbent. The chosen adsorption temperature is approximately 630K. The column is cooled down and filled with helium to operating pressure (approximately 150 mm Hg). The system should be capable to give 100-fold enrichment, starting from some 100 litres of hydrogen (5 to 10 moles) within 3 hours and a tritium recovery near unity

315

Uranium enrichment by displacement chromatography  

International Nuclear Information System (INIS)

Natural Uranium contains 0.72% of fissile isotope 235U. Need for 235U enriched uranium for light water moderated reactors and other uses are well known. Uranium enrichment is a highly complex and tedious process owing to extremely small separation factor. Several processes have been tried; however, gaseous diffusion and centrifugation techniques based on mass dependent isotope effect are being exploited for producing enriched uranium. In the recent past, Isotope fractionation based on mass independent isotope effect such as LASER technique, ion exchange displacement chromatography etc. have drawn the attention of separation scientist and efforts are being made for development and industrial deployment of these technologies. Indian Nuclear Power Programme is based on use of natural uranium (PHWRs) and slightly enriched uranium (BWRs, PWRs) with emphasis on use of vast resources of thorium. Spent fuel from PHWRs, which is depleted in 235U (0.2 to 0.3%), appears to be a promising source of slightly enriched uranium (1 to 3% 235U). Harnessing this source for 235U enrichment would augment fuel supply for PHWR and light water reactors. Ion exchange displacement chromatography is a proliferation resistant novel technique for 235U enrichment. It is based on nuclear field shift - an isotope shift in orbital electrons resulting from the isotopic difference in nuclear size and shape. Due to this effect lighter isotope (235U) exhibits a stronger tendency for a higher valence i.e. UO22+ as compared to heavier isotope (238U). Preliminary laboratory study is being carried out at HWP, Manuguru for exploring feasibility of using ion exchange displacement chromatography for enriching 235U using 4-vinyl pyridine based anion exchange resin

316

Anaerobic Initial Reaction of n-Alkanes in a Denitrifying Bacterium: Evidence for (1-Methylpentyl)succinate as Initial Product and for Involvement of an Organic Radical in n-Hexane Metabolism†  

Science.gov (United States)

A novel type of denitrifying bacterium (strain HxN1) with the capacity to oxidize n-alkanes anaerobically with nitrate as the electron acceptor to CO2 formed (1-methylpentyl)succinate (MPS) during growth on n-hexane as the only organic substrate under strict exclusion of air. Identification of MPS by gas chromatography-mass spectrometry was based on comparison with a synthetic standard. MPS was not formed during anaerobic growth on n-hexanoate. Anaerobic growth with [1-13C]n-hexane or d14-n-hexane led to a 1-methylpentyl side chain in MPS with one 13C atom or 13 deuterium atoms, respectively. This indicates that the 1-methylpentyl side chain originates directly from n-hexane. Electron paramagnetic resonance spectroscopy revealed the presence of an organic radical in n-hexane-grown cells but not in n-hexanoate-grown cells. Results point at a mechanistic similarity between the anaerobic initial reaction of n-hexane and that of toluene, even though n-hexane is much less reactive; the described initial reaction of toluene in anaerobic bacteria is an addition to fumarate via a radical mechanism yielding benzylsuccinate. We conclude that n-hexane is activated at its second carbon atom by a radical reaction and presumably added to fumarate as a cosubstrate, yielding MPS as the first stable product. When 2,3-d2-fumarate was added to cultures growing on unlabeled n-hexane, 3-d1-MPS rather than 2,3-d2-MPS was detected, indicating loss of one deuterium atom by an as yet unknown mechanism. PMID:11160102

Rabus, Ralf; Wilkes, Heinz; Behrends, Astrid; Armstroff, Antje; Fischer, Thomas; Pierik, Antonio J.; Widdel, Friedrich

2001-01-01

317

Quantitative molecular biology and gas flux measurements demonstrate soil treatment and depth affects on the distribution and activity of denitrifiers  

Science.gov (United States)

The growing industrialisation of agriculture has led to a dramatic increase in organic and inorganic nitrogen (N) fertiliser inputs to agro-ecosystems. This increase has had negative effects on the quality of water ecosystems and greenhouse gas emissions.The study objective was to quantify denitrification and denitrifying microorganisms, using real-time PCR assays of the nitrite reductase(nir) and nitrous oxide reductase(nos) functional gene copy concentrations (GCC g[soil]-1) in Irish agricultural surface and subsoils. Soil cores from 3 soil horizons (A:0-10 cm; B:45-55 cm; C:120-130cm) were amended with 3 alternate N- and C-source amendments (NO3-; NO3-+glucose-C; NO3-+Dissolved Organic Carbon (DOC). Real-time production of N2O and N2 was recorded by gas chromatography in a specialized He/O2 environment. N2O and Total Denitrification (TDN) (N2O+N2) production was generally greater in surface soil (2.052 mg/kg/d TDN) than in subsoils (0.120 mg/kg/d TDN). The abundance of denitrifying nirS, nirK (nir) and nos genes was higher in the surface soil, decreasing with soil depth, except in incubations amended with NO3- and DOC, where the carbon source directly positively affected gene copy numbers and fluxes of N2O and N2 production. C addition increased soil denitrification rates, and resulted in higher N2O/(N2O+N2) ratios in surface soil (0.39) than subsoils (0.005), indicating that the subsoil had higher potential for complete reduction of N2O to N2. In the subsoils, complete reduction of NO3- due to glucose-C and DOC addition was observed. Interestingly, at all 3 soil depths, lower nirK abundance (2.78 105 GCC) was recorded, compared to nirS (1.45 107 GCC), but the overall abundance of nir (S+K) i.e. (1.54 107GCC), corresponded with N2O emission fluxes (3.34 mg/kg/d) Statistical analysis indicates negative correlation between nirK GCC and N2O production, but a strong positive correlation was observed between nirS GCC and N2O. We therefore hypothesize that the potential for complete nitrate reduction can be inferred using the relationship - ([nirS + nirK] - nosZ): (nosZ). Specifically, at 45-55 cm depth ([nirS + nirK] - nosZ): (nosZ) ratios were lower (2.13) compared to 120-130cm (94.4), overall the ([nirS + nirK] - nosZ): (nosZ) ratios for horizons A, B and C, was 27.9, 40.3, 69.4, respectively, thus decreasing potential for full microbial denitrification with decreasing depth. Mean Bac:nir and Bac:nosZ gene copy ratios g[soil]-1 increased from horizon A(Bac:nir - 3.91) (Bac:nosZ - 111.24) to horizon B (Bac:nir - 8.89) (Bac:nosZ -295.0 ), and decreased again in horizon C (Bac:nir - 0.723) (Bac:nosZ - 46.2) . Overall, denitrification in subsoils occurs at a lower rate than surface soils, but the microbial populations favored more complete reduction thus reducing emissions of NO3- to water and N2O to the atmosphere. The gene copy ratio suggests that the soil microbial community containing nirs and nosZ genes act as the driving force, and in the partitioning of N2O and N2 emissions from soil.

Barrett, M. M.; Jahangir, M.; Cardenas, L.; Khalil, M.; Richards, K. R.; O'Flaherty, V.

2010-12-01

318

Phylogenetic and functional diversity within toluene-degrading, sulphate-reducing consortia enriched from a contaminated aquifer.  

Science.gov (United States)

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. PMID:24623528

Kuppardt, Anke; Kleinsteuber, Sabine; Vogt, Carsten; Lüders, Tillmann; Harms, Hauke; Chatzinotas, Antonis

2014-08-01

319

Do freshwater macrophytes influence the community structure of ammonia-oxidizing and denitrifying bacteria in the rhizospere?  

DEFF Research Database (Denmark)

DO FRESHWATER MACROPHYTES INFLUENCE THE COMMUNITY STRUCTURE OF AMMONIA-OXIDIZING AND DENITRIFYING BACTERIA IN THE RHIZOSPHERE? M. Herrmann, A. Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Aarhus, Denmark Aquatic macrophytes such as Littorella uniflora and Lobelia dortmanna have been shown to release oxygen from their roots and to stimulate nitrification and coupled nitrification-denitrification in the rhizosphere. Together with the excretion of root exudates, this effect leads to strongly modified microenvironments at the root surface and in the rhizosphere compared to unvegetated sediment, especially with respect to the availability of oxygen, organic carbon, and inorganic nitrogen. We hypothesize that macrophyte species create specific niches for ammonia oxidizing and nitrate-reducing bacteria in their rhizosphere, leading to plant-dependant differences in abundance, activity and composition of these microbial communities between root surface (rhizoplane), rhizosphere and unvegetated sediment. Comparative investigations are carried out focussing on the macrophyte species Littorella uniflora, Juncus bulbosus and Myriophyllum spicatum. Microsensor measurements confirmed the photosynthesis-dependant, species-specific release of oxygen into the rhizosphere; batch incubations indicated a higher nitrification potential in the rhizosphere of Littorella uniflora compared to unvegetated sediment, and will be complemented with the determination of rates of coupled nitrification-denitrification using the 15N isotope pairing technique. Ammonia-oxidizing and nitrate-reducing populations are analyzed based on the ammonia monooxygenase gene (amoA) and the nitrate reductase gene (narG) as functional markers. Preliminary data indicate that there in fact exist differences in the community composition of ammonia oxidizing bacteria between the root surface, the rhizosphere and unvegetated sediment and between plant species, however, differences in the community composition among sampling sites also suggest a strong impact of the chemical properties of the sediment.

Herrmann, Martina; Schramm, Andreas

2006-01-01

320

Evaluation of droplet digital PCR for characterizing plasmid reference material used for quantifying ammonia oxidizers and denitrifiers.  

Science.gov (United States)

DNA reference materials of certified value have a critical function in many analytical processes of DNA measurement. Quantification of amoA genes in ammonia oxidizing bacteria (AOB) and archaea (AOA), and of nirS and nosZ genes in the denitrifiers is very important for determining their distribution and abundance in the natural environment. A plasmid reference material containing nirS, nosZ, amoA-AOB, and amoA-AOA is developed to provide a DNA standard with copy number concentration for ensuring comparability and reliability of quantification of these genes. Droplet digital PCR (ddPCR) was evaluated for characterization of the plasmid reference material. The result revealed that restriction endonuclease digestion of plasmids can improve amplification efficiency and minimize the measurement bias of ddPCR. Compared with the conformation of the plasmid, the size of the DNA fragment containing the target sequence and the location of the restriction site relative to the target sequence are not significant factors affecting plasmid quantification by ddPCR. Liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) was used to provide independent data for quantifying the plasmid reference material. The copy number concentration of the digested plasmid determined by ddPCR agreed well with that determined by LC-IDMS, improving both the accuracy and reliability of the plasmid reference material. The reference value, with its expanded uncertainty (k?=?2), of the plasmid reference material was determined to be (5.19?±?0.41)?×?10(9) copies ?L(-1) by averaging the results of two independent measurements. Consideration of the factors revealed in this study can improve the reliability and accuracy of ddPCR; thus, this method has the potential to accurately quantify DNA reference materials. PMID:24493332

Dong, Lianhua; Meng, Ying; Wang, Jing; Liu, Yingying

2014-02-01

321

Diagnosis and quantification of glycerol assimilating denitrifying bacteria in an integrated fixed-film activated sludge reactor via 13C DNA stable-isotope probing.  

Science.gov (United States)

Glycerol, a byproduct of biodiesel and oleo-chemical manufacturing operations, represents an attractive alternate to methanol as a carbon and electron donor for enhanced denitrification. However, unlike methanol, little is known about the diversity and activity of glycerol assimilating bacteria in activated sludge. In this study, the microbial ecology of glycerol assimilating denitrifying bacteria in a sequencing batch integrated fixed film activated sludge (SB-IFAS) reactor was investigated using (13)C-DNA stable isotope probing (SIP). During steady state SB-IFAS reactor operation, near complete nitrate removal (92.7 ± 5.8%) was achieved. Based on (13)C DNA clone libraries obtained after 360 days of SB-IFAS reactor operation, bacteria related to Comamonas spp. and Diaphorobacter spp. dominated in the suspended phase communities. (13)C assimilating members in the biofilm community were phylogenetically more diverse and were related to Comamonas spp., Bradyrhizobium spp., and Tessaracoccus spp. Possibly owing to greater substrate availability in the suspended phase, the glycerol-assimilating denitrifying populations (quantified by real-time PCR) were more abundant therein than in the biofilm phase. The biomass in the suspended phase also had a higher specific denitrification rate than the biofilm phase (p = 4.33e-4), and contributed to 69.7 ± 4.5% of the overall N-removal on a mass basis. The kinetics of glycerol based denitrification by suspended phase biomass were approximately 3 times higher than with methanol. Previously identified methanol assimilating denitrifying bacteria were not associated with glycerol assimilation, thereby suggesting limited cross-utilization of these two substrates for denitrification in the system tested. PMID:21053955

Lu, Huijie; Chandran, Kartik

2010-12-01

322

Laboratory and field studies on BTEX biodegradation in a fuel-contaminated aquifer under denitrifying conditions. Book chapter, May 88-Dec 92  

International Nuclear Information System (INIS)

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Of the approximately 1.4 million underground tanks storing gasoline in the United States, some petroleum experts estimate that 75,000 to 100,000 are leaking (Feliciano 1984). Gasoline and other fuels contain benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX), which are hazardous compounds regulated by the U.S. Environmental Protection Agency (EPA 1977). Laboratory studies were conducted in conjunction with a field demonstration project on nitrate-mediated biorestoration of a fuel-contaminated aquifer at a U.S. Coast Guard facility in Traverse City, MI. Microcosms were prepared under either aerobic or strictly anaerobic, denitrifying conditions using core samples aseptically obtained from the aquifer. The microcosms were spiked with aromatic hydrocarbons (BTEX) and incubated as 12 C. Virtually all of the aromatic hydrocarbons, including benzene, were degraded to below detection limits within seven days under aerobic conditions, although o-xylene was somewhat more recalcitrant. Under denitrifying conditions, toluene, ethylbenzene, m-xylene, and 1,2,4-trimethylbenzene were also degraded to below detection limits, although this occurred between two to three weeks. o-Xylene was only slowly degraded and benzene was recalcitrant under denitrifying conditions. In the field demonstration project, an infiltration gallery was used to recirculate wateation gallery was used to recirculate water at a rate sufficient to create a water table mound encompassing the contaminated interval. After hydraulic equilbrium was achieved nitrate and nutrients were added to the recharge water. Benzene removal occurred before nitrate addition; mass balances indicated that sufficient oxygen was recirculated to account for complete biodegradation aerobically

323

Biotransformation of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) by Denitrifying Pseudomonas sp. Strain FA1  

OpenAIRE

The microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source, Pseudomonas sp. strain FA1, was isolated from a garden soil. Studies with i...

Bhushan, Bharat; Paquet, Louise; Spain, Jim C.; Hawari, Jalal

2003-01-01

324

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

325

Why is Brazil enriching uranium?  

International Nuclear Information System (INIS)

In Brazil construction began in 1971 on Angra 1, a 626 MW Westinghouse pressurized water reactor (PWR). It was completed in 1984. Later, Angra 2 (a Kraftwerk Union PWR) achieved commercial operation in 2000. Brazil is considering the construction of seven nuclear power plants over the next 15 years. In preparation for this nuclear industry expansion, Brazil is building a uranium enrichment facility to provide nuclear fuel for Angra 1 and 2 starting in 2010 at Resende in the state of Rio de Janeiro, and collated with nuclear fuel fabrication facilities. This paper investigates whether the Resende Enrichment Facility will be able to provide uranium enrichment services at a cost lower than the international market price. We find that while Brazil is unlikely to be internationally competitive in the enrichment market, the Resende Enrichment Facility completes the front end of Brazil's nuclear fuel cycle. This assures uninterrupted nuclear fuel to its currently operating light water reactors, while providing the option of expanding capacity, lowering cost, and competing in the international nuclear fuel market after 2020

326

Gaseous diffusion -- the enrichment workhorse  

International Nuclear Information System (INIS)

Construction of the first large-scale gaseous diffusion facility was started as part of the Manhattan Project in Oak Ridge, Tennessee, in 1943. This facility, code named ''K-25,'' began operation in January 1945 and was fully on stream by September 1945. Four additional process buildings were later added in Oak Ridge as the demand for enriched uranium escalated. New gaseous diffusion plants were constructed at Paducah, Kentucky, and Portsmouth, Ohio, during this period. The three gaseous diffusion plants were the ''workhorses'' which provided the entire enriched uranium demand for the United States during the 1950s and 1960s. As the demand for enriched uranium for military purposes decreased during the early 1960s, power to the diffusion plants was curtailed to reduce production. During the 1960s, as plans for the nuclear power industry were formulated, the role of the diffusion plants gradually changed from providing highly-enriched uranium for the military to providing low-enriched uranium for power reactors

327

Enrichment of light hydrocarbon mixture  

Science.gov (United States)

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.

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

328

PC based uranium enrichment analyser  

International Nuclear Information System (INIS)

It is important to measure enrichment of unirradiated nuclear fuel elements during production as a quality control measure. An IBM PC based system has recently been tested for enrichment measurements for Nuclear Fuel Complex (NFC), Hyderabad. As required by NFC, the system has ease of calibration. It is easy to switch the system from measuring enrichment of fuel elements to pellets and also automatically store the data and the results. The system uses an IBM PC plug in card to acquire data. The card incorporates programmable interval timers (8253-5). The counter/timer devices are executed by I/O mapped I/O's. A novel algorithm has been incorporated to make the system more reliable. The application software has been written in BASIC. (author). 9 refs., 1 fig

329

The uranium enrichment services market  

International Nuclear Information System (INIS)

There are two main processes for the enrichment of uranium, to give uranium with a higher U235 content than occurs naturally (usually 2 to 4% of the total). One is gaseous diffusion, the other is the gas centrifuge process. These and other less common methods (which are not used commercially), are described. The role of Urenco in the supply of enriched uranium is explained. Financed by the UK, Netherlands and Federal Republic of Germany, it has uranium enrichment plants at Capenhurst in England, Urenco Nederland at Almelo and Urenco Deutschland at Gronau. Other suppliers are also mentioned. Demand fluctuations are discussed. Price developments and the total demand and contracts signed by the supplier up to the year 2000 are illustrated. (UK)

330

Potential exposures from uranium enrichment  

International Nuclear Information System (INIS)

Public radiation doses resulting from gaseous diffusion enrichment facility effluents can be assessed by considering the potential environmental exposure pathways. These exposure pathways result from releases to both air and water, and rely on model evaluations to predict environmental transport. For most airborne releases, inhalation is the primary exposure pathway. Secondary pathways, including external exposure during plume passage, ingestion of uranium deposited on or contained in vegetation, and external exposure to uranium deposited /on land surfaces also contribute. For liquid effluents, the primary exposure pathway is ingestion of aquatic biota and ingestion of irrigated begetation. This paper contains a review of the important considerations for conducting collective dose assessments for gaseous diffusion enrichment facility operations, including discussions of the dosimetric considerations for uranium, and a summary of estimated collective doses resulting from gaseous diffusion enrichment in the United States

331

Diversity of bacterial community and detection of nirS- and nirK-encoding denitrifying bacteria in sandy intertidal sediments along Laizhou Bay of Bohai Sea, China.  

Science.gov (United States)

The microbial community and the nirS- and nirK-encoding denitrifiers in the intertidal sediments along Laizhou Bay in China were studied using pyrosequencing and real-time quantitative PCR (qPCR), respectively. There were three primary intertidal zones: Laizhou (La), Weifang Harbor (We), and Dongying (Do). Significant differences in composition and abundances at the different taxonomic levels were observed among the three bacterial communities. The qPCR results indicated that the nirS gene abundance varied from 8.67 × 10(5) to 5.68 × 10(6)copies/gwet weight (ww), whereas the nirK gene abundance varied from 1.26 × 10(5) to 1.89 × 10(6)copies/gww. The canonical correlation analysis (CCA) indicated that the sand percentage was the most important factor in shaping the bacterial community followed by silt percentage, NO2(-), TOC, DO, pH, and clay percentage, whereas the clay percentage, pH, NO3(-), DO, NO2(-), TOC, silt percentage, and sand percentage were the most important factors associated with regulating the abundance of nirS- and nirK-encoding denitrifiers. PMID:25256298

Wang, Liping; Zheng, Binghui; Nan, Bingxu; Hu, Peilong

2014-11-15

332

Selective enrichment of a methanol-utilizing consortium using pulp & paper mill waste streams  

Energy Technology Data Exchange (ETDEWEB)

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. Waste activated 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 four 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 hour 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.

Gregory R. Mockos; William A. Smith; Frank J. Loge; David N. Thompson

2007-04-01

333

Selective Enrichment of a Methanol-Utilizing Consortium Using Pulp and Paper Mill Waste Streams  

Science.gov (United States)

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.

Mockos, Gregory R.; Smith, William A.; Loge, Frank J.; Thompson, David N.

334

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

335

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

336

Uranium enriched granites in Sweden  

International Nuclear Information System (INIS)

Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

337

Two-Stage Mineralization of Phenanthrene by Estuarine Enrichment Cultures  

OpenAIRE

The polycyclic aromatic hydrocarbon phenanthrene was mineralized in two stages by soil, estuarine water, and sediment microbial populations. At high concentrations, phenanthrene was degraded, with the concomitant production of biomass and accumulation of Folin-Ciocalteau-reactive aromatic intermediates. Subsequent consumption of these intermediates resulted in a secondary increase in biomass. Analysis of intermediates by high-performance liquid chromatography, thin-layer chromatography, and U...

Guerin, William F.; Jones, Galen E.

1988-01-01

338

Anaerobic Oxidation of Acetylene by Estuarine Sediments and Enrichment Cultures  

OpenAIRE

Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for th...

Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

1981-01-01

339

AN ENRICHMENT CULTURE THAT DEGRADES MTBE UNDER ANAEROBIC CONDITIONS  

Science.gov (United States)

Biodegradation of MTBE in ground water may be a significant factor helping to reduce MTBE contamination from gasoline spills. Previously, decreases in MTBE concentrations in wells at release sites were thought to be due exclusively to dispersion and dilution. Researchers have i...

340

Relationship between N2O Fluxes from an Almond Soil and Denitrifying Bacterial Populations Estimated by Quantitative PCR  

Science.gov (United States)

Cultivated soils emit substantial quantities of nitrous oxide (N2O), a greenhouse gas with almost 300 times the radiative forcing potential of CO2. Agriculture-related activities generate from 6 to 35 Tg N2O-N per year, or about 60 to 70% of global production. The microbial processes of nitrification, denitrification and nitrifier denitrification are major biogenic sources of N2O to the atmosphere from soils. Denitrification is considered the major source of N2O especially when soils are wet. The microbial N transformations that produce N2O depend primarily on nitrogen (N) fertilizer, with water content, available carbon and soil temperature being secondary controllers. Despite the fact that microbial processes are responsible for N2O emissions, very little is known about the numbers or types of populations involved. The objective of this study was to relate changes in denitrifying population densities, using quantitative PCR (qPCR) of functional genes, to N2O emissions in a fertilized almond orchard. Quantitative PCR targeted three specific genes involved in denitrification: nirS, nirK and nosZ. Copy numbers of the genes were related back to population densities and the portion of organisms likely to produce nitrous oxide. The study site, a 21.7 acre almond orchard fitted with micro-sprinklers, was fertigated (irrigated and fertilized simultaneously) with 50 lbs/acre sodium nitrate in late March 2008, then irrigated weekly. Immediately after the initial fertigation, fluxes of N2O and CO2, moisture content, inorganic N and denitrification gene copy numbers were measured 6 times over 24 days. Despite the fact that N2O emissions increased following fertigation, there was no consistent increase in any of the targeted genes. The genes nirK and nirS ranged from 0.4-1.4 × 107 and 0.4-1.4 × 108, whereas nosZ ranged from 2-8 × 106 copy numbers per g soil, respectively. Considerable variation, compounded by the small sample sizes used for DNA analysis, made it difficult to discern trends over time. High spatial variability was also observed with one of the field replicates have a substantially higher flux of N2O. This replicate also had the highest water filled pore space (WFPS) and water content, factors that likely favored denitrification. Water saturation of soil air space, optimal at >60% for denitrification to occur, was relatively low in the other field replicates. Thus, the low N2O flux measurements and gene copy numbers agreed in supporting the hypothesis denitrification was relatively low under the environmental conditions of these particular almond soils.

Matiasek, M.; Suddick, E. C.; Smart, D. R.; Scow, K. M.

2008-12-01

341

Nitrogen removal and spatial distribution of denitrifier and anammox communities in a bioreactor for mine drainage treatment.  

Science.gov (United States)

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 design favored preferential flow along these flowpaths, away from the sides of the bioreactor. An improved bioreactor design should consider the role of preferential flowpaths and the heterogeneous distribution of the genetic potential for denitrification, nitrous oxide reduction and anammox on bioreactor function. PMID:25233117

Herbert, Roger B; Winbjörk, Harry; Hellman, Maria; Hallin, Sara

2014-12-01

342

Identification of the function of extracellular polymeric substances (EPS) in denitrifying phosphorus removal sludge in the presence of copper ion.  

Science.gov (United States)

Industrial wastewater containing heavy metals that enters municipal wastewater treatment plants inevitably has a toxic impact on biological treatment processes. In this study, the impact of Cu(II) (0, 1.5, 2, 2.5, 3 mg/L) on the performance of denitrifying phosphorus removal (DPR) and microbial community structures was investigated. Particularly, the dynamic change in the amount and composition of extracellular polymeric substances (EPS), and the role of EPS in P removal, were assessed using three-dimensional excitation-emission matrix fluorescence spectroscopy combined with parallel factor (PARAFAC) analysis. The results showed that, after long-term adjustment, the P removal efficiency was maintained at 95 ± 2.7% at Cu(II) addition up to 2.5 mg/L, but deteriorated when the Cu(II) addition was 3 mg/L. The EPS content, including proteins and humic substances, increased with increasing Cu(II) additions at concentrations ?2.5 mg/L. This property of EPS was beneficial for protecting phosphate-accumulating organisms (PAOs) against heavy metals, as both proteins and humic substances are strong ligands for Cu(II). Therefore, the PAOs abundance was still relatively high (67 ± 3%) when Cu(II) accumulation in sludge was up to 10 mg/g SS. PARAFAC confirmed that aromatic proteins could be transformed into soluble microbial byproduct-like material when microorganisms were subjected to Cu(II) stress, owing to their strong metal ion complexing capacity. The increase in the percentage of humic-like substances enhanced the detoxification function of the sludge EPS. EPS accounted for approximately 26-47% of P removed by adsorption when Cu(II) additions were between 0 and 2.5 mg/L. The EPS function, including binding toxic heavy metals and P storage, enhanced the operating stability of DPR systems. This study provides us with a better understanding of (1) the tolerance of DPR sludge to copper toxicity and (2) the function of sludge EPS in the presence of heavy metals in biological P removal systems. PMID:25697691

Wang, Yayi; Qin, Jian; Zhou, Shuai; Lin, Ximao; Ye, Liu; Song, Chengkang; Yan, Yuan

2015-04-15

343

Centrifuge enrichment: benefits and risks  

International Nuclear Information System (INIS)

The President decided to use the new centrifuge technology instead of the proven diffusion technology for the uranium enrichment plant to be built at Portsmouth, Ohio. This report addresses the appropriateness of (1) substituting the new technology and (2) building the plant away from the centrifuge development facilities at Oak Ridge, Tennessee

344

Enriched Fell Bundles and Spaceoids  

OpenAIRE

We propose a definition of involutive categorical bundle (Fell bundle) enriched in an involutive monoidal category and we argue that such a structure is a possible suitable environment for the formalization of different equivalent versions of spectral data for commutative C*-categories.

Bertozzini, Paolo; Conti, Roberto; Lewkeeratiyutkul, Wicharn

2011-01-01

345

Enrichment and characterization of sulfate reducing, naphthalene degrading microorganisms  

Science.gov (United States)

Polycyclic aromatic hydrocarbons (PAH) are pollutants of great concern due to their potential toxicity, mutagenicity and carcinogenicity. PAH are widely distributed in the environment by accidental discharges during the transport, use and disposal of petroleum products, and during forest and grass fires. Caused by their hydrophobic nature, PAH basically accumulate in sediments from where they are slowly released into the groundwater. Although generally limited by the low water solubility of PAH, microbial degradation is one of the major mechanisms leading to the complete clean-up of PAH-contaminated sites. Whereas organisms and biochemical pathways responsible for the aerobic breakdown of PAH are well known, anaerobic PAH biodegradation is less understood; only a few anaerobic PAH degrading cultures have been described. We studied the anaerobic PAH degradation in a microcosm approach to enrich anaerobic PAH degraders. Anoxic groundwater and sediment samples were used as inoculum. Groundwater samples were purchased from the erstwhile gas works facility and a former wood impregnation site. In contrast, sources of sediment samples were a former coal refining area and an old fuel depot. Samples were incubated in anoxic mineral salt medium with naphthalene as sole carbon source and sulfate as terminal electron acceptor. Grown cultures were characterized by feeding with 13C-labeled naphthalene, 16S rRNA gene sequencing using an Illumina® approach, and functional proteome analyses. Finally, six enrichment cultures able to degrade naphthalene under anoxic conditions were established. First results point to a dominance of identified sequences affiliated to the freshwater sulfate-reducing strain N47, which is a known anaerobic naphthalene degrader, in four out of the six enrichments. In those enrichments, peptides related to the pathway of anoxic naphthalene degradation in N47 were abundant. Overall the data underlines the importance of Desulfobacteria for natural attenuation of environmental contaminants. Understanding of diversity and physiology of anaerobic PAH degradation will contribute to remediation efforts of low-oxygen environments such as aquifers or river sediments.

Steffen, Kümmel; Florian-Alexander, Herbst; Márcia, Duarte; Dietmar, Pieper; Jana, Seifert; Bergen Martin, von; Hans-Hermann, Richnow; Carsten, Vogt

2014-05-01

346

Enrichment, Isolation, and Phylogenetic Identification of Polycyclic Aromatic Hydrocarbon-Degrading Bacteria from Elizabeth River Sediments? † §  

OpenAIRE

The diversity of indigenous bacteria in sediments from several sites in the Elizabeth River (Virginia) able to degrade multiple polycyclic aromatic hydrocarbons (PAHs) was investigated by the use of classical selective enrichment and molecular analyses. Enrichment cultures containing naphthalene, phenanthrene, fluoranthene, or pyrene as a sole carbon and energy source were monitored by denaturing gradient gel electrophoresis (DGGE) to detect changes in the bacterial-community profile during e...

Hilyard, Edward J.; Jones-meehan, Joanne M.; Spargo, Barry J.; Hill, Russell T.

2007-01-01

347

Enrichment into the 21st century  

International Nuclear Information System (INIS)

This article discusses the future of the enrichment services market into the next century. It is estimated that demand for enrichment services will reach 31 million SWU by the end of the century and remain constant for the following 10 years. The current world enrichment capacity is 44 million SWU, or some 50% ahead of the demand. This oversupply is projected to continue into the next century, but in spite of this, several suppliers are planning new enrichment facilities. HEU as a source of enriched uranium is examined. Overall, long-term prices for enrichment services are expected to decline in the coming decade

348

Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors  

International Nuclear Information System (INIS)

Highlights: ? Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. ? Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. ? Several species from classes ?-, ?- and ?-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 ?M of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (?Eq) L-1, linked to the reduction of 619 ± 81 ?Eq L-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 ?-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the pediment sample showed the prevalence of different species from classes ?-, ?- and ?-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

349

Nitrous oxide nitrification and denitrification 15N enrichment factors from Amazon forest soils.  

Science.gov (United States)

The isotopic signatures of 15N and 18O in N2O emitted from tropical soils vary both spatially and temporally, leading to large uncertainty in the overall tropical source signature and thereby limiting the utility of isotopes in constraining the global N2O budget. Determining the reasons for spatial and temporal variations in isotope signatures requires that we know the isotope enrichment factors for nitrification and denitrification, the two processes that produce N2O in soils. We have devised a method for measuring these enrichment factors using soil incubation experiments and report results from this method for three rain forest soils collected in the Brazilian Amazon: soil with differing sand and clay content from the Tapajos National Forest (TNF) near Santarém, Pará, and Nova Vida Farm, Rondônia. The 15N enrichment factors for nitrification and denitrification differ with soil texture and site: -111 per thousand +/- 12 per thousand and -31 per thousand +/- 11 per thousand for a clay-rich Oxisol (TNF), -102 per thousand +/- 5 per thousand and -45 per thousand +/- 5 per thousand for a sandier Ultisol (TNF), and -10.4 per thousand +/- 3.5 per thousand (enrichment factor for denitrification) for another Ultisol (Nova Vida) soil, respectively. We also show that the isotopomer site preference (delta15Nalpha - delta15Nbeta, where alpha indicates the central nitrogen atom and beta the terminal nitrogen atom in N2O) may allow differentiation between processes of production and consumption of N2O and can potentially be used to determine the contributions of nitrification and denitrification. The site preferences for nitrification and denitrification from the TNF-Ultisol incubated soils are: 4.2 per thousand +/- 8.4 per thousand and 31.6 per thousand +/- 8.1 per thousand, respectively. Thus, nitrifying and denitrifying bacteria populations under the conditions of our study exhibit significantly different 15N site preference fingerprints. Our data set strongly suggests that N2O isotopomers can be used in concert with traditional N2O stable isotope measurements as constraints to differentiate microbial N2O processes in soil and will contribute to interpretations of the isotopic site preference N2O values found in the free troposphere. PMID:17205894

Pérez, Tibisay; Garcia-Montiel, Diana; Trumbore, Susan; Tyler, Stanley; de Camargo, Plínio; Moreira, Marcelo; Piccolo, Marisa; Cerri, Carlos

2006-12-01

350

Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors.  

Science.gov (United States)

Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system [Formula: see text] was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to [Formula: see text] was 11 mg NO2(-)-N/L in the bulk, and a total of 34 mg NO2(-)-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in [Formula: see text] , approximately 13.6% higher than that in a parallel P removal SBR using nitrate [Formula: see text] . Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in [Formula: see text] , contributing 72% to total PAOs. Compared with [Formula: see text] , [Formula: see text] biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in [Formula: see text] after each pulse of nitrite. Peak N2O concentrations in the bulk for [Formula: see text] were generally 6-11 times higher than that in [Formula: see text] ; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2(-)-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2(-)-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in [Formula: see text] reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite. PMID:25261626

Wang, Yayi; Zhou, Shuai; Ye, Liu; Wang, Hong; Stephenson, Tom; Jiang, Xuxin

2014-12-15

351

Sulfide enhances methanogenesis in nitrate-containing methanogenic cultures.  

Science.gov (United States)

The effects of sulfide on nitrate reduction and methanogenesis using butyrate as a carbon source were investigated in a mixed mesophilic, methanogenic culture. In the sulfide-free medium, 25-75 mg l(-1) nitrate markedly inhibited the efficiencies of acetogenesis and methanogenesis processes. Adding 25 mg-S l(-1) increased methane production in nitrate-amended medium. Low sulfide levels shifted the nitrate reduction pathway from denitrification to dissimilatory nitrate reduction to ammonia (DNRA), thereby reducing the amounts of toxic nitric oxide and nitrous oxide produced that inhibit methanogenesis. The dose of 25 mg l(-1) sulfide was oxidized completely, during which heterotrophic DNRA predominated. The oxidized forms of sulfide reformed, limiting induction of the heterotrophic denitrification pathway. The actions of heterotrophic and autotrophic DNRA bacteria, denitrifiers, sulfate-reducing bacteria and methanogens mitigate nitrate toxicity during methanogenesis in an anaerobic process. PMID:21087858

Wong, Biing-Teo; Lee, Duu-Jong

2011-02-01

352

Trace elements affect methanogenic activity and diversity in enrichments from subsurface coal bed produced water  

Directory of Open Access Journals (Sweden)

Full Text Available Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After seven days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R2=0.95. Metabolically-active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of coal bed methane production and alter the composition of the active methanogenic community.

KlausNüsslein

2012-05-01

353

Trace elements affect methanogenic activity and diversity in enrichments from subsurface coal bed produced water.  

Science.gov (United States)

Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients) are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper) on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane (CBM) well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After 7?days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R(2)?=?0.95). Metabolically active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of CBM production and alter the composition of the active methanogenic community. PMID:22590465

Unal, Burcu; Perry, Verlin Ryan; Sheth, Mili; Gomez-Alvarez, Vicente; Chin, Kuk-Jeong; Nüsslein, Klaus

2012-01-01

354

Urine culture  

Science.gov (United States)

Culture and sensitivity - urine ... when urinating. You may also have a urine culture after you have been treated for an infection. ... when bacteria or yeast are found in the culture. This most often means that you have a ...

355

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)

356

Enrichment demand boosts SWU prices  

International Nuclear Information System (INIS)

The enrichment market is picking up significantly on very brisk demand. US utilities, which normally purchase material nine months to a year ahead of time, are already hitting the market to fill their 1996 requirements. In June, two non-US utilities, one European entity and a US utility bought SWUs, the entity in an off-market deal. But that doesn't tell the whole story. Three other US utilities entered the market during the month. Meanwhile, we count 13 more utilities getting ready to hit the market for more than 4 million SWUs. Why the surge in demand? Utilities, uncertain of the role to be played by the new US Enrichment Corp. and seeking to take advantage of low interest rates, are implementing buy and hold strategies. As a result, the upper end of NUKEM's SWU price range inched up to $78. The lower end dipped to $67 based on the European deal

357

Safeguards Culture  

Energy Technology Data Exchange (ETDEWEB)

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.

Frazar, Sarah L.; Mladineo, Stephen V.

2012-07-01

358

Uranium enrichment plans and policies  

International Nuclear Information System (INIS)

Significant progress has been made in US efforts to expand its enrichment capacity. The Cascade Improvement Program (CIP) and Cascade Upgrading Program (CUP) are now complete at Oak Ridge and Paducah and almost complete at Portsmouth. Considerable progress has also been made in constructing the Gas Centrifuge Enrichment Plant (GCEP), and physical construction of the first process building is well under way. Current plans are to have two process buildings on-line by 1989 with the remaining six buildings to be added sequentially as needed to meet demand. The status of DOE enrichment services contracts is essentially unchanged from that reported at last year's seminar. The OUEA latest forecast of nuclear power growth, however, is considerably lower than reported last year, although a leveling trend is becoming apparent. The Variable Tails Assay Option (VTAO) of the AFC contract was made available for the third time for FY 1983. The DOE inventories of natural uranium still remain high. The Department of Energy will dispose of this material by using it for Government programs and for enrichment plant operations. It appears that Government inventories of uranium are adequate through at least the mid-1990s. It remains DOE policy not to dispose of its natural uranium stocks through direct sales in the marketplace, except for very small quantities or if an emergency situation would exist and all reasonable attempts had been made, without success, to obtain natural uranium fromut success, to obtain natural uranium from commercial sources. Finally, with regard to DOE plans on future transaction tails assays, it still appears likely that the current 0.20 percent uranium-235 reference tails assay will be maintained until well into the 1990s, at which time it might be increased up to 0.25 percent uranium-235

359

Enrichment techniques employed in phosphoproteomics.  

Czech Academy of Sciences Publication Activity Database

Ro?. 43, ?. 3 (2012), s. 1025-1047. ISSN 0939-4451 R&D Projects: GA ?R(CZ) GAP501/11/1462; GA ?R GA522/09/0858; GA ?R GA525/09/0994; GA MŠk OC08011 Institutional research plan: CEZ:AV0Z50380511 Keywords : Phosphoproteomics * Enrichment * IMAC Subject RIV: ED - Physiology Impact factor: 3.914, year: 2012

Fíla, Jan; Honys, David

2012-01-01

360

Organizational Culture  

Directory of Open Access Journals (Sweden)

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.

Adrian HUDREA

2006-02-01

361

Urenco's contribution to the enrichment market  

International Nuclear Information System (INIS)

The paper deals with the Present status of Urenco Enrichment Plants and Order Book, Urenco's future development, The Western World enrichment supply situation, Urenco's Policy on the reliability of enrichment supplies, and its contribution to a reliable, stable and competitive world enrichment market. Urenco's current plant capacity and forward committed expansion plans up to 1990 and its present position in the western world enrichment market are described. The application of Urenco's centrifuge technology to the enrichment of recycles uranium and the relevance of laser enrichment development to Urenco are discussed. The paper next discusses the structure and main characteristics of the major sectional markets of the western world enrichment market, i.e. particularly in the United States, Western Europe and Asia (Japan, Korea and Taiwan). Urenco's contractual approach regarding the reliability of enrichment supplies is discussed, it is shown that Urenco's development of the centrifuge process to the point of economic maturity, Urenco's establishment of a multi-national commercial enrichment organization, Urenco's achievement in the world enrichment market by a commercial and competitive approach, Urenco's preparedness to negotiate suitable supply arrangements including the establishment of plants in other market areas have vastly contributed to a stabilisation of the world enrichment market. (J.P.N.)

362

Enriching Music and Language Arts Experiences  

Science.gov (United States)

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…

Flohr, John W.

2006-01-01

363

Differential regulation of periplasmic nitrate reductase gene (napKEFDABC) expression between aerobiosis and anaerobiosis with nitrate in a denitrifying phototroph Rhodobacter sphaeroides f. sp. denitrificans.  

Science.gov (United States)

A denitrifying phototroph, Rhodobacter sphaeroides f. sp. denitrificans, has the ability to denitrify by respiring nitrate. The periplasmic respiratory nitrate reductase (Nap) catalyses the first step in denitrification and is encoded by the genes, napKEFDABC. By assaying the ss-galactosidase activity of napKEFD-lacZ fusions in wild type and nap mutant cells grown under various growth conditions, the environmental signal for inducing nap expression was examined. Under anoxic conditions with nitrate, nap genes expression in the wild-type strain was highest in the dark, and somewhat lowered by incident light, but that of the napA, napB, and napC mutant strains was low, showing that nap expression is dependent on nitrate respiration. Under oxic conditions, both the wild type and nap mutant cells showed high ss-galactosidase activities, comparable to the wild-type grown under anoxic conditions with nitrate. Myxothiazol, a specific inhibitor of the cytochrome bc (1) complex, did not affect the beta-galactosidase activity in the wild-type cells grown aerobically, suggesting that the redox state of the quinone pool was not a candidate for the activation signal for aerobic nap expression. These results suggested that the trans-acting regulatory signals for nap expression differ between anoxic and oxic conditions. Deletion analysis showed that the nucleotide sequence from -135 to -88 with respect to the translational start point is essential for nap expression either under anoxic or oxic conditions, suggesting that the same cis-acting element is involved in regulating nap expression under either anoxic with nitrate or oxic conditions. PMID:16136296

Tabata, Atsuya; Yamamoto, Isamu; Matsuzaki, Masahiro; Satoh, Toshio

2005-11-01

364

Using Salt-Enriched Diets to Reduce Stress in Trout  

Directory of Open Access Journals (Sweden)

Full Text Available Chronically stressful conditions in fish culture facilities can lead to outbreaks of disease and reductions in growth and performance. A secondary response to stress in fish is the sudden and significant loss of plasma chloride ions, a condition known as hypochloremia. This loss of plasma chloride has been implicated as a cause of mortality in severely stressed fish. The effect of increased dietary salt on reducing hypochloremia in rainbow trout (Onchorynchus mykiss subjected to a confinement challenge was investigated. Experimental diets included added NaCl or CaCl2. Trout fed salt-enriched diets suffered less hypochloremia in the early hours or confinement. Trout fed a higher level of NaCl had significantly higher recovery plasma chloride levels post-stress. Salt-enriched diets containing moderate levels of NaCl may offer some benefit in recovering trout that have been exposed to stress.

Amanda E. Smith

2005-01-01

365

Decoding cultural landscapes: guiding principles for the management of interpretation in cultural world heritage sites  

OpenAIRE

Conserving the cultural significance of heritage sites - as the guardians of social unity, place identity, and national pride - plays an essential role in maintaining sustainable social development, as well as preserving the variations identifying cultural groups and enriching the interaction between them. Consequently, and considering the importance of the built environment in communicating, as well as documenting, cultural messages, this research project, started in 2007, develops a set of ...

Kamel, Ehab

2011-01-01

366

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 t 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

367

Enrichment planting without soil treatment  

Energy Technology Data Exchange (ETDEWEB)

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

Hagner, Mats

1998-12-31

368

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

369

77 FR 13367 - General Electric-Hitachi Global Laser Enrichment, LLC, Proposed Laser-Based Uranium Enrichment...  

Science.gov (United States)

...LLC, Proposed Laser-Based Uranium Enrichment Facility, Wilmington, NC...Laser Enrichment, LLC (GLE) Uranium Enrichment Facility. On June 26, 2009...decommissioning of a laser-based uranium enrichment facility (the...

2012-03-06

370

75 FR 10525 - In the Matter of: AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility) and All Other...  

Science.gov (United States)

...Enrichment Services, LLC (Eagle Rock Enrichment Facility) and All Other Persons...Effective Immediately) I AREVA Enrichment Services, LLC (AES), has...it to construct and operate a uranium enrichment facility in Bonneville...

2010-03-08

371

Culture Machine  

Science.gov (United States)

Culture Machine is a new, refereed, electronic journal encompassing cultural studies and cultural theory. The international editorial board of the interactive journal aims to "generat[e] research in culture and theory" by promoting and publishing "the most provocative of new work." The theme of the inaugural issue is Taking Risks with the Future. Content includes articles such as Life After Death of the Text by Johan Fornas, Cultural Studies in the Clouds: Mourning for Detail by Tadeusz Slawek, and The Future States of Politics by Kenneth Surin. Culture Machine is hosted by the University of Teesside, England.

372

Virtual Interaction through Video-Web Communication: A Step towards Enriching and Internationalizing Language Learning Programs  

Science.gov (United States)

This paper describes an intercontinental project with the use of interactive tools, both synchronous and asynchronous, which was set up to internationalize academic learning of Spanish language and culture. The objective of this case study was to investigate whether video-web communication tools can contribute to enriching the quality of foreign…

Jauregi, Kristi; Banados, Emerita

2008-01-01

373

Priming tissue cultured propagules  

International Nuclear Information System (INIS)

Priming of in vitro propagules refers to the manipulation of the growing environment, prior to and upon transplanting, and is an integral part of tissue culture propagation. Tissue-cultured propagules are produced under controlled environment. Such plantlets have small juvenile leaves with reduced photosynthetic capacity, and malfunctioning stomata. Priming for rooting, shooting, and improved photosynthesis can be achieved with growth regulators and simple adjustment to the growing conditions that affect the post-transplanting performance of the propagules. Vented closures with microbial filters have been used to facilitate gas exchange to reduce ethylene build-up that stunts plant growth, reduces leaf-size, and causes leaf drop in tissue culture containers. Plantlets produced under photoautotrophic culture systems on media with or without sucrose but CO2-enrichment, increased light intensity, good gas exchange and reduced humidity are more vigorous, have larger root- systems, and are less susceptible to microbial contamination. Plants adapted gradually to the ex-vitro environment have improved survival upon transfer to soil. Plants in their natural environment are colonized with many bacteria, fungi, and mycorrhizae. In-vitro or ex-vitro biopriming of micropropagated plants with such organisms can improve plant performance under stress environments, and consequently enhances yield. (author)

374

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by microbial consortia enriched from mangrove sediments.  

Science.gov (United States)

Surface sediments from two mangrove swamps in Hong Kong were enriched to obtain PAH-degrading microbial consortia. The consortium from sediments enriched with phenanthrene (Phe) in Ma Wan, a mangrove swamp next to a boat anchorage, was effective in degrading PAH with 96.7% and 89.9% Phe degradation at 0 and 10 ppt salinities, respectively. The Phe-enriched microbial consortium could also use pyrene (Pyr) as the sole carbon source but the degradation was much less (around 15%). On the other hand, the Phe-enriched consortium from sediments in Yi O, a mangrove swamp recently polluted by an oil spill, completely removed Phe and Pyr at both 0 and 10 ppt salinities. This suggests that different consortia were selected in two sediments using the same PAH substrate. Not only sediments, PAH substrate used for enrichment also selected different consortia. The Pyr- and Fla-enriched Yi O consortia only achieved 10.5 and 4.5% Phe degradation, respectively and the corresponding pyrene degradation was 7 and 40%. Among the three PAH compounds, fluoranthene (Fla) was most difficult to degrade, and 21.1, 11.3, and 36.8% Fla were degraded by Phe-, Fla- and Pyr-enriched cultures, respectively. PMID:14682585

Tam, N F Y; Guo, C L; Yau, C; Ke, L; Wong, Y S

2003-01-01

375

Evaluación del crecimiento de un cultivo de Daphnia magna alimentado con Saccharomyces cereviseae y un enriquecimiento con avena soya / Growth culture evaluation of Daphnia magna feed with Saccharomyces cereviseae enrichment with oat soy / Avaliação do crescimento de um cultivo de Daphnia magna alimentada con Saccharomyces cereviseae e um meio enrriquecido com aveia soja  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in portuguese O objetivo do experimento foi avaliar o efeito das gorduras saturadas e insaturadas e seu grau de proteção (protegidas e sem proteção) sob a cinética e a extensão da degradação in vitro da matéria seca (MS) em dietas para ruminantes. Quatro dietas foram formuladas para conter o mesmo nível de energi [...] a (3200 Kcal ED /Kg MS) e proteína (13%PC) a ração total misturada (RTM), de acordo com as necessidades nutricionais de ovelhas em fase de finalização, quatro tipos de gorduras foram feitas com 8% de MS e foram testados tipos de gorduras foram testados: 1) gordura saturada sem proteção (GSSP), 2) gordura saturada protegida (GSP), 3) gordura insaturada sem proteção (GISP) e 4) gordura insaturada protegida (GIP). Para estimar a cinética e a extensão da degradação da MS e cinética da produção de gás, as rações foram avaliadas mediante a técnica in vitro de produção de gás, seguindo os modelos propostos por Orskov e McDonald (1979) y France et al (1993), para isto foi empregado o procedimento PROC NLIN de SAS (2001). Ao mesmo tempo, foi realizado um analise de medidas repetidas no tempo para verificar o efeito dos tratamentos sobre a produção de gás e a degradação da MS no tempo com ajuda do procedimento PROC MIXED do SAS (2001.) Neste experimento verificou-se que a utilização de gorduras insaturadas protegidas não afetou a degradação de MS quando comparadas com as não protegidas. No caso das gorduras saturadas, não houve um claro efeito da proteção sob a degradação e a cinética de fermentação da MS. Abstract in spanish Se realizó el cultivo experimental de cladócero Daphnia magna alimentado con probióticos. Se realizaron 16 ensayos experimentales, en el laboratorio de larvicultura de peces y alimento vivo (Larpeali) de la Facultad de Ciencias Agrarias de la Universidad de Antioquia, bajo condiciones controladas de [...] temperatura ambiente (21 - 25 °C), temperatura del agua (22 - 23 °C) y pH (7.6). Empleando una dieta de Saccharomyces cereviseae y un medio de enriquecimiento con ácidos grasos (n-6) proveniente de harina avena-soya. Las concentraciones de dieta y enriquecimiento fueron de 25 ppm y 12.5 ppm, en arreglo factorial 2x2 (2 niveles de dieta con levadura y 2 niveles dieta con avena de soya), los cultivos de Daphnia por tratamiento se realizaron con cuatro replicas con el fin de determinar su efecto sobre el desempeño de la población. Se alimentaron cada tercer día, durante 15 días, evaluándose el número de organismos al final del período. Se obtuvieron diferencias altamente significativas (p0.05). Se evidenció que la combinación de estos componentes en sus concentraciones más altas potenció el crecimiento de la Daphnia magna, alcanzando un número de microcrustáceos de 826ª Daphnias/L ± 9.57. Se puede concluir que los cladóceros por sus características de crecimiento en cultivo, presentan adaptación favorable a las condiciones de manejo para la producción de biomasa útil como alimento vivo en acuicultura. Abstract in english Experimental cultivate cladocerans Daphnia magna feed with probiotics was realized. At University of Antioquia, Faculty of Agrarian Science, Larviculture, fish and food live Laboratory (Larpeali), under controlled conditions of environmental temperature between (21 - 25 °C), water temperature (22 - [...] 23°C) and pH (7.6), were performed. One diet of Saccharomyces cereviseae was used and one enriched medium of oat-soy flour (fatty acid, n-6) to concentrations of diet and enriched medium were the same, 25 ppm and 12.5 ppm, 2x2 factorial treatment arrangements (2 levels of Saccharomyces cereviseae and 2 levels of oat-soy flour, diets was fed to four replicates of Daphnia culture per treatment in order to determine their effects on the populations cultivated. A 15-days feeding, each third day, trial were conducted, to assess the organisms at final period. The results showed significant high difference (p0.05). The results showed that the c

Lucía E, Ocampo; Mónica C, Botero; Luis F, Restrepo.

2010-03-01

376

Cultural Pluralism  

Science.gov (United States)

This comment examines the roles of cultural pluralism and assimilation as guiding values in American law. In particular, it investigates the ways in which the legal system both implicitly and explicitly recognizes the value of cultural pluralism. (Author/AM)

Fong, Kevin M.

1978-01-01

377

Throat Culture  

Science.gov (United States)

... this website will be limited. 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 ...

378

Gastric culture  

Science.gov (United States)

Gastric culture is a test to check a child's stomach contents for the bacteria that cause tuberculosis (TB). ... is placed in a special dish called a culture medium and watched for the growth of bacteria.

379

Enrichment study gets go-ahead  

International Nuclear Information System (INIS)

A full feasibility study into the establishment of a uranium enrichment industry in Australia is to be carried out by the Uranium Enrichment Group (UEGA). This follows a pre-feasibility study by the group, made up of BHP, CSR, Peko Wallsend and Western Mining Corporation, which found that Australia could sustain an enrichment industry in the 1990s. The pre-feasibility study identified centrifuge and chemical exchange technology as suitable for Australian conditions

380

Improved methods for enrichment (including reprocessed uranium)  

International Nuclear Information System (INIS)

Centrifuges are, and will remain, the future uranium enrichment technology for natural, and particulary reprocessed, uranium. As a result of an extensive trial giving comprehensive experience of the behaviour of reprocessed uranium during enrichment, Urenco is well placed to receive increasing quantities in the coming years. Utilities can rely in complete confidence on Urenco's technology and processes for the safe, efficient and flexible enrichment of reprocessed uranium to satisfactory standards. (orig./HP)

381

Safety culture  

International Nuclear Information System (INIS)

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)

382

CULTURAL VALUES  

OpenAIRE

ABSTRACT SUDARMIN HARUN. Cultural Values in Buginese Traditional Songs (supervised by Burhanuddin Arafah, Marthen L. Manda, and Stanislaus Sandarupa). This study aimed at finding and elaborating: (1) the cultural symbols, their kinds, their morphemic, literal, and idiomatic meanings, applied in BTS; (2) the aspect of values and their significant meanings, reflected by the cultural symbols in BTS; (3) The significant meanings and the aims of cultural symbols used by Buginese community...

Harun, Sudarmin

2012-01-01

383

Enriched natural zeolites ? mineral fertilizer  

Directory of Open Access Journals (Sweden)

Full Text Available Clinoptilolit belongs to the big group of minerals called zeolites. Chemically they are alumosilicates and have a very difficult crystal structure. Nature zeolites are used as sorbents, molecular sieves and catalyzators. Their application is also in agriculture and horticulture. Endeavour of all agricurtural subjects from the plant area is to reach a maximum efficiency and production.Charges for the fertilization are 14 ? 40% of all charges depending on the structure of product, intensity of production and share of nutrition in soil. For the elimination of the loss in the nutrition matter, it is possible to use a ?porter?, which secures a regular and inteligent supply of nutrition to plants.Regarding the physical and chemical properties is good to use natural zeolites as a ?porter?.The experiments were made with enriched zeolites, and their influences an vegetables and flowers roots was reserched. Results were positive.

Rybárová Lucia

2001-12-01

384

The Gronau uranium enrichment plant  

International Nuclear Information System (INIS)

The German uranium enrichment plant at Gronau is part of British-German-Netherlands cooperation in the field of uranium isotope separation. The three companies of Urenco had an aggregate capacity of some 1500 t SWU/a in operation in late 1985, which is to be doubled in order to meet requirements. The delivery contracts entered into by Urenco make it necessary that the German plant, operating at 150 t SWU/a at the moment, go beyond the presently licensed capacity of 400 t SWU/a already around mid-1988 and attain its full capacity of 1000 t SWU/a around 1992. The steady improvement in performance of the centrifuges and their high availability ensures the international competitiveness of the Urenco facilities. (orig.)

385

The future cost of uranium enrichment  

International Nuclear Information System (INIS)

The cost of uranium enrichment is the most important factor determining the fuel cost of nuclear energy. This paper attempts to forecast the future direction of the price of separative work by examining the forces that determine it. It is argued that the interplay among the characteristics of enrichment technologies, the structure of the international market, and the balance of supply and demand determine the enrichment price. The analysis indicates that all forces point towards a price much lower than the current one. It is predicted that, depending on the technological advances, the price of separative work unit for uranium enrichment will range between $40 and $90 by the year 2000. (author)

386

Development of an enrichment monitor on pipes for the gas centrifuge enrichment plant  

International Nuclear Information System (INIS)

Verification that material production is in the range of declared enrichment (5 wt%) is one of the most important objectives for a gas centrifuge enrichment plant in implementation of safeguards. It was agreed upon in the Hexapartite Safeguards Project that a NDA enrichment monitor on cascade header pipes would be an important measure to achieve the above-mentioned objective. Therefore, the enrichment monitor has been developed at the Ningyo-Toge Uranium Enrichment Pilot Plant. Tests of the enrichment monitor was performed on the test loop system and on the cascade header pipes inside cascade area. The enrichment of UF6 gas was determined by combining following three techniques. 1. passive ?-ray measurement, 2. X-ray fluorescent measurement, 3. 2-geometry measurement. The results showed that the measurement accuracy of the monitor was high enough to verify no production of uranium higher than declared enrichment. (author)

387

Core and Intact Polar Glycerol Dibiphytanyl Glycerol Tetraether Lipids of Ammonia-Oxidizing Archaea Enriched from Marine and Estuarine Sediments ? ¶  

OpenAIRE

Glycerol dibiphytanyl glycerol tetraether (GDGT)-based intact membrane lipids are increasingly being used as complements to conventional molecular methods in ecological studies of ammonia-oxidizing archaea (AOA) in the marine environment. However, the few studies that have been done on the detailed lipid structures synthesized by AOA in (enrichment) culture are based on species enriched from nonmarine environments, i.e., a hot spring, an aquarium filter, and a sponge. Here we have analyzed co...

Pitcher, Angela; Hopmans, Ellen C.; Mosier, Annika C.; Park, Soo-je; Rhee, Sung-keun; Francis, Christopher A.; Schouten, Stefan; Sinninghe Damste?, Jaap S.

2011-01-01

388

A combined enrichment/polymerase chain reaction based method for the routine screening of Streptococcus agalactiae in pregnant women  

OpenAIRE

Group B Streptococcus (GBS) is the most common cause of life-threatening infection in neonates. Guidelines from CDC recommend universal screening of pregnant women for rectovaginal GBS colonization. The objective of this study was to compare the performance of a combined enrichment/PCR based method targeting the atr gene in relation to culture using enrichment with selective broth medium (standard method) to identify the presence of GBS in pregnant women. Rectovaginal GBS samples from women a...

Munari, F. M.; De-paris, F.; Salton, G. D.; Lora, P. S.; Giovanella, P.; Machado, A. B. M. P.; Laybauer, L. S.; Oliveira, K. R. P.; Ferri, C.; Silveira, J. L. S.; Laurino, C. C. F. C.; Xavier, R. M.; Barth, A. L.; Echeverrigaray, S.; Laurino, J. P.

2012-01-01

389

21 CFR 137.350 - Enriched rice.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Enriched rice. 137.350 Section 137.350 Food...Related Products § 137.350 Enriched rice. (a) The foods for which definitions...prescribed by this section are forms of milled rice (except rice coated with talc and...

2010-04-01

390

URENCO-CENTEC wins enrichment technology stakes  

International Nuclear Information System (INIS)

The Australian Government has agreed to recommendations made by the Uranium Enrichment Group of Australia regarding the establishment of a uranium enrichment plant. The gas centrifuge technology developed by URENCO-CENTEC was recommended because of its economic superiority, proven technical and commercial capability and flexibility for modular growth

391

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)

392

Inoculation stress hypothesis of environmental enrichment.  

Science.gov (United States)

One hallmark of psychiatric conditions is the vast continuum of individual differences in susceptibility vs. resilience resulting from the interaction of genetic and environmental factors. The environmental enrichment paradigm is an animal model that is useful for studying a range of psychiatric conditions, including protective phenotypes in addiction and depression models. The major question is how environmental enrichment, a non-drug and non-surgical manipulation, can produce such robust individual differences in such a wide range of behaviors. This paper draws from a variety of published sources to outline a coherent hypothesis of inoculation stress as a factor producing the protective enrichment phenotypes. The basic tenet suggests that chronic mild stress from living in a complex environment and interacting non-aggressively with conspecifics can inoculate enriched rats against subsequent stressors and/or drugs of abuse. This paper reviews the enrichment phenotypes, mulls the fundamental nature of environmental enrichment vs. isolation, discusses the most appropriate control for environmental enrichment, and challenges the idea that cortisol/corticosterone equals stress. The intent of the inoculation stress hypothesis of environmental enrichment is to provide a scaffold with which to build testable hypotheses for the elucidation of the molecular mechanisms underlying these protective phenotypes and thus provide new therapeutic targets to treat psychiatric/neurological conditions. PMID:25449533

Crofton, Elizabeth J; Zhang, Yafang; Green, Thomas A

2015-02-01

393

Current perspective of the uranium enrichment market  

International Nuclear Information System (INIS)

Over the past several years, developments in the uranium enrichment market have required the Department of Energy (DOE) to make a number of changes in the U.S. enrichment enterprise. These changes have been made to allow DOE to conduct our enrichment business so as to be more responsive to changing market forces. Needless to say, some of these changes have been difficult, but they have been necessary if they are to conduct a healthy and competitive uranium enrichment business in the United States. This paper discusses several topics, including: The Uranium Enrichment Market, Utility Services (US) Contracts, Reduced Prices, Incentive Pricing, Better Customer Services, and Advanced Technology. In addition to these topics, information is provided on the recent court action regarding the US Contracts and the viability finding on the uranium mining industry

394

Automatic stop type SPE tritium enrichment apparatus  

International Nuclear Information System (INIS)

A water sensor was attached to the tritium enrichment apparatus which we had developed with solid polymer electrolyte. When water is decomposed to a constant volume, the sensor cut the electric source off automatically. The function enabled to get enriched water at the same volume for every electrolysis run. Associated to the function, a tritium measurement without enriched water volume data was proposed. The tritium concentration Ti was expressed as follows. Ti=Tf/{10[A·log(Vi)+B]}, Tf: enriched tritium concentration, Vi: sample water volume, A and B: constants. By this, we solved the problem about the enriched water volume that had been held in porous electrodes. The reliability of the apparatus was improved in addition to advantages; the reduction of electrolysis time, easy and safe procedure. (author)

395

Stable isotope inventory requirements and enrichment capabilities  

International Nuclear Information System (INIS)

The electromagnetic isotope enrichment program established in 1945 has since then continued to provide enriched stable, actinide, and selected radioactive isotopes. These unique materials used in research and medicine and for industrial applications are made available throughout the world by direct sales and/or on a loan basis. In recent years, the primary effort of the program has been directed toward providing enriched stable isotopes necessary to replenish the sales inventory. This document presents a summary of the stable isotope sales requirements and the capabilities of the electromagnetic isotope separators for providing the quantity and quality of enriched products to meet those needs. Special enrichment and actinide separations or Research Materials Collection (loan program) needs are not addressed

396

Uranium enrichment capacity: public versus private ownership  

International Nuclear Information System (INIS)

Continual growth of conventional nuclear capacity requires an assured supply of enriched uranium and, hence, potential expansion of domestic uranium enrichment capacity. The question of ownership of new enrichment capacity, i.e., public or private, entails not only the social-opportunity costs of alternative investments but also technical parameters of uranium utilization and advanced reactor development. Inclusion of risk preferences in both the public and private sectors produces interesting results in terms of optimal investment strategies with respect to choice of technology and scale of investment. Utilization of a nuclear fuel cycle requirements process model allows explicit specification of production technology. Integration of process model output with a least-cost investment model permits flexibility in parametric analysis. Results indicate minimum incentive for Government subsidy of a private enrichment sector through 2000 given moderate to low nuclear growth assumptions. The long-run scenario, to 2020, exhibits potentially greater incentives for private enrichment investment

397

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

398

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

399

Mortality among uranium enrichment workers  

International Nuclear Information System (INIS)

A retrospective cohort mortality study was conducted on workers at the Portsmouth Uranium Enrichment facility in Pike County, Ohio, in response to a request from the Oil, Chemical and Atomic Workers International Local 3-689 for information on long-term health effects. Primary hazards included inhalation exposure to uranyl fluoride containing uranium-235 and uranium-234, technetium-99 compounds, and hydrogen-fluoride. Uranium-238 presented a nephrotoxic hazard. Statistically significant mortality deficits based on U.S. death rates were found for all causes, accidents, violence, and diseases of nervous, circulatory, respiratory, and digestive systems. Standardized mortality rates were 85 and 54 for all malignant neoplasms and for other genitourinary diseases, respectively. Deaths from stomach cancer and lymphatic/hematopoietic cancers were insignificantly increased. A subcohort selected for greatest potential uranium exposure has reduced deaths from these malignancies. Insignificantly increased stomach cancer mortality was found after 15 years employment and after 15 years latency. Routine urinalysis data suggested low internal uranium exposures

400

Uranium enrichment by diffusion process  

International Nuclear Information System (INIS)

A brief history of the process is given, and existing facilities are described, and the possibility of this process meeting the needs for enriched uranium in the future is discussed. It is concluded that, since other separation techniques have not yet been proven to be competitive, the gaseous diffusion process must be relied on to meet most of these needs. However, because of the high energy consumption required by this process, attempts to improve the technology must be continued. Is the gaseous diffusion process able to meet this challenge. Considering the technical viewpoint, there is no doubt about it. From the economical standpoint, this process is mainly characterized by an important energy consumption and the necessity to build large plants, thus leading to an important investment, at least for the first plant. Other processes have been developed with a view to reduce both the energy and capital needs. However, in spite of continuous studies and technological progress no process has yet been proven to be competitive. Large increments in capacities are still expected to come from the gaseous diffusion and several projects taking into acount the improvements in the flexibility, automatization, reliability and a reduced investment, will be analysed. Coupling of new facilities to existing plants has already proven to be of great interest. This situation explains why further investigations concerning the gaseous diffusion are being carried on, together with the study of new processes

401

Student science enrichment training program  

Energy Technology Data Exchange (ETDEWEB)

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.

Sandhu, S.S.

1994-08-01

402

Enriching the hot circumgalactic medium  

CERN Document Server

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...

Crain, Robert A; Schaye, Joop; Frenk, Carlos S; Theuns, Tom

2013-01-01