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1

Impact of mercury on denitrification and denitrifying microbial communities in nitrate enrichments of subsurface sediments.  

UK PubMed Central (United Kingdom)

The contamination of groundwater with mercury (Hg) is an increasing problem worldwide. Yet, little is known about the interactions of Hg with microorganisms and their processes in subsurface environments. We tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge Integrated Field Research Challenge site, where nitrate is a major contaminant and where bioremediation efforts are in progress. We observed an inverse relationship between Hg concentrations and onset and rates of denitrification in nitrate enrichment cultures containing between 53 and 1.1 ?M of inorganic Hg; higher Hg concentrations increasingly extended the time to onset of denitrification and inhibited denitrification rates. Microbial community complexity, as indicated by terminal restriction fragment length polymorphism (tRFLP) analysis of the 16S rRNA genes, declined with increasing Hg concentrations; at the 312 nM Hg treatment, a single tRFLP peak was detected representing a culture of Bradyrhizobium sp. that possessed the merA gene indicating a potential for Hg reduction. A culture identified as Bradyrhizobium sp. strain FRC01 with an identical 16S rRNA sequence to that of the enriched peak in the tRFLP patterns, reduced Hg(II) to Hg(0) and carried merA whose amino acid sequence has 97 % identity to merA from the Proteobacteria and Firmicutes. This study demonstrates that in subsurface sediment incubations, Hg may inhibit denitrification and that inhibition may be alleviated when Hg resistant denitrifying Bradyrhizobium spp. detoxify Hg by its reduction to the volatile elemental form.

Wang Y; Wiatrowski HA; John R; Lin CC; Young LY; Kerkhof LJ; Yee N; Barkay T

2013-02-01

2

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

Science.gov (United States)

Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to 'Candidatus Methylomirabilis oxyfera' were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO(2)(-)-N/Ld (using synthetic medium) and 37.8 mg NO(2)(-)-N/Ld (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass retention. PMID:22657102

Kampman, Christel; Hendrickx, Tim L G; Luesken, Francisca A; van Alen, Theo A; Op den Camp, Huub J M; Jetten, Mike S M; Zeeman, Grietje; Buisman, Cees J N; Temmink, Hardy

2012-05-15

3

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

UK PubMed Central (United Kingdom)

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

Kampman C; Hendrickx TL; Luesken FA; van Alen TA; Op den Camp HJ; Jetten MS; Zeeman G; Buisman CJ; Temmink H

2012-08-01

4

Anaerobic degradation of toluene by pure cultures of denitrifying bacteria.  

UK PubMed Central (United Kingdom)

Several denitrifying Pseudomonas spp., isolated with various aromatic compounds, were tested for the ability to degrade toluene in the absence of molecular oxygen. Four out of seven strains were able to degrade toluene in the presence of N2O. More than 50% of the 14C from ring-labelled toluene was released as CO2, and up to 37% was assimilated into cell material. Furthermore it was demonstrated for two strains that they were able to grow on toluene as the sole carbon and energy source in the presence of N2O. Suspensions of cells pregrown on toluene degraded toluene, benzaldehyde or benzoate without a lag phase and without accumulation of intermediates. p-Cresol, p-hydroxybenzylalcohol, p-hydroxybenzaldehyde or p-hydroxybenzoate was degraded much slower or only after distinct lag times. In the presence of fluoroacetate [14C]toluene was transformed to [14C]benzoate, which suggests that anaerobic toluene degradation proceeds through oxidation of the methyl side chain to benzoate.

Schocher RJ; Seyfried B; Vazquez F; Zeyer J

1991-01-01

5

Enrichment and Molecular Detection of Denitrifying Methanotrophic Bacteria of the NC10 Phylum?  

Science.gov (United States)

Anaerobic methane oxidation coupled to denitrification was recently assigned to bacteria belonging to the uncultured phylum NC10. In this study, we incubated sediment from a eutrophic ditch harboring a diverse community of NC10 bacteria in a bioreactor with a constant supply of methane and nitrite. After 6 months, fluorescence in situ hybridization showed that NC10 bacteria dominated the resulting population. The enrichment culture oxidized methane and reduced nitrite to dinitrogen gas. We assessed NC10 phylum diversity in the inoculum and the enrichment culture, compiled the sequences currently available for this bacterial phylum, and showed that of the initial diversity, only members of one subgroup had been enriched. The growth of this subgroup was monitored by quantitative PCR and correlated to nitrite-reducing activity and the total biomass of the culture. Together, the results indicate that the enriched subgroup of NC10 bacteria is responsible for anaerobic methane oxidation coupled to nitrite reduction. Due to methodological limitations (a strong bias against NC10 bacteria in 16S rRNA gene clone libraries and inhibition by commonly used stopper material) the environmental distribution and importance of these bacteria could be largely underestimated at present.

Ettwig, Katharina F.; van Alen, Theo; van de Pas-Schoonen, Katinka T.; Jetten, Mike S. M.; Strous, Marc

2009-01-01

6

Enrichment and molecular detection of denitrifying methanotrophic bacteria of the NC10 phylum.  

Science.gov (United States)

Anaerobic methane oxidation coupled to denitrification was recently assigned to bacteria belonging to the uncultured phylum NC10. In this study, we incubated sediment from a eutrophic ditch harboring a diverse community of NC10 bacteria in a bioreactor with a constant supply of methane and nitrite. After 6 months, fluorescence in situ hybridization showed that NC10 bacteria dominated the resulting population. The enrichment culture oxidized methane and reduced nitrite to dinitrogen gas. We assessed NC10 phylum diversity in the inoculum and the enrichment culture, compiled the sequences currently available for this bacterial phylum, and showed that of the initial diversity, only members of one subgroup had been enriched. The growth of this subgroup was monitored by quantitative PCR and correlated to nitrite-reducing activity and the total biomass of the culture. Together, the results indicate that the enriched subgroup of NC10 bacteria is responsible for anaerobic methane oxidation coupled to nitrite reduction. Due to methodological limitations (a strong bias against NC10 bacteria in 16S rRNA gene clone libraries and inhibition by commonly used stopper material) the environmental distribution and importance of these bacteria could be largely underestimated at present. PMID:19329658

Ettwig, Katharina F; van Alen, Theo; van de Pas-Schoonen, Katinka T; Jetten, Mike S M; Strous, Marc

2009-03-27

7

IDENTIFICATION AND ECOPHYSIOLOGY OF ACTIVE DENITRIFIERS IN ACTIVATED SLUDGE  

DEFF Research Database (Denmark)

Denitrification is of crucial importance for nitrogen removal in wastewater treatment. However, due to the polyphyletic taxonomy of denitrifiers, little is known about their community composition and ecophysiology and the available knowledge derives mainly from culture-dependent studies or enriched reactor studies. To obtain better identification of active denitrifying communities in full-scale wastewater treatment plants (WWTPs) we applied DNA-SIP with 13C-labelled substrates, and RT-PCR of expressed denitrification genes (nirS, nirK and nosZ) upon various substrate-inductions. To come around the bias of horizontal gene transfer, the identities were verified by microautoradiography (MAR) combined with fluorescence in situ hybridization (FISH) with incorporation of radio-labelled substrates under denitrifying conditions. The in situ abundances of the identified denitrifiers in different WWTPs were determined with quantitative FISH, while their active metabolic pathways were investigated directly in activated sludge with a tag-based metatranscriptomic approach under acetate-utilizing and denitrifying conditions. The different methods revealed a majority of denitrifiers in all WWTPs belonging to Betaproteobacteria (Acidovorax, Azoarcus, Curvibacter and Thauera) and to a lesser extent Alphaproteobacteria (Paracoccus), while few denitrifying Gammaproteobacteria and Firmicutes were identified. A taxonomic discrepancy of the denitrifying communities was highly correlated to the configuration of the WWTPs and when external carbon sources were supplemented to the activated sludge the composition of the denitrifying communities was significantly affected. Transcriptome profiling provided detailed insight in the metabolic pathways in several of the active denitrifiers in activated sludge. In conclusion, this study has provided novel leads for the identity and distribution of denitrifiers in WWTPs as well as their physiological and metabolic capabilities in activated sludge.

Hansen, Aviaja Anna; Le-Quy, Vang

8

Isolation of Oligotrophic Denitrifiers Carrying Previously Uncharacterized Functional Gene Sequences? †  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oligotrophic denitrifying bacteria, including those belonging to the genera Herbaspirillum, Azospirillum, and Bradyrhizobium, were obtained using a single-cell isolation technique. The taxonomic composition of the denitrifier population was similar to those assessed by previous culture-independent s...

Ishii, Satoshi; Ashida, Naoaki; Otsuka, Shigeto; Senoo, Keishi

9

Enrichment and Short Term Culture of the Ovine Gonocyte  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to investigate the effects of two types of ovine testis cells population as feeder cell on in vitro culture of the enriched ovine gonocytes. The feeder cell populations were prepared from 5-6 months old ovine testis. The 1-2 months old neonatal rams were used to isolate germ cells through a two step enzymatic digestion followed by differential plating for SSCs enrichment. Isolated and enriched cells were characterized by using PLZF and VASA antibody. During the 1st week of culture, gonocyte formed pairs and chains of type A spermatogonia. After 1 week, colonies started to increase in size. About 2 weeks later, more colonies in type II feeder group kept undifferentiated and looks more effective regarding colony formation of spermatogonia compared with type I feeder group in the ovine spermatogonial stem cell culture system.

Uyunbilig Borjigin; Xin Zhou; Xuejie Han; Rongfeng Li; Muren Herrid; Shorgan Bou

2011-01-01

10

Enrichment and Short Term Culture of the Ovine Gonocyte  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to investigate the effects of two types of ovine testis cells population as feeder cell on in vitro culture of the enriched ovine gonocytes. The feeder cell populations were prepared from 5-6 months old ovine testis. The 1-2 months old neonatal rams were used to isol...

Uyunbilig Borjigin; Xin Zhou; Xuejie Han; Rongfeng Li; Muren Herrid; Shorgan Bou

11

[Isolation, identification of two aerobic denitrifiers and bioaugmentation for enhancing denitrificaition of biofilm under oligotrophic conditions].  

Science.gov (United States)

Two aerobic denitrifying bacteria were isolated from the sludge of municipal wastewater treatment plant by enrichment, preliminary screening with BTB culture medium and the denitrification potential test and identified through 16S rDNA sequence analysis. Then they were bioaugmented to oligotrophic biofilm system respectively, aiming to enhance the denitrification capacity. The two strains were identified as Pseudomonas aeruginosa and Pseudomonas putida respectively. They could remove 78% or 82% of the total nitrogen in the simulate wastewater when existed alone. And the total nitrogen removal efficiency of the biofilm system reached 68% and 64% after bioaugmentation with two trains, increased by 47% and 43% compared to the control, respectively. Meanwhile, the ammonia nitrogen was nearly 100% removed. It can be concluded that two aerobic denitrifiers can enhance the denitrification of biofilm system significantly under oligotrophic conditions and will not inhibit the nitrification process, therefore can help biofilm system achieve simultaneous nitrification and denitrification. PMID:24028024

Quan, Xiang-Chun; Cen, Yan; Qian, Yin

2013-07-01

12

[Isolation, identification of two aerobic denitrifiers and bioaugmentation for enhancing denitrificaition of biofilm under oligotrophic conditions].  

UK PubMed Central (United Kingdom)

Two aerobic denitrifying bacteria were isolated from the sludge of municipal wastewater treatment plant by enrichment, preliminary screening with BTB culture medium and the denitrification potential test and identified through 16S rDNA sequence analysis. Then they were bioaugmented to oligotrophic biofilm system respectively, aiming to enhance the denitrification capacity. The two strains were identified as Pseudomonas aeruginosa and Pseudomonas putida respectively. They could remove 78% or 82% of the total nitrogen in the simulate wastewater when existed alone. And the total nitrogen removal efficiency of the biofilm system reached 68% and 64% after bioaugmentation with two trains, increased by 47% and 43% compared to the control, respectively. Meanwhile, the ammonia nitrogen was nearly 100% removed. It can be concluded that two aerobic denitrifiers can enhance the denitrification of biofilm system significantly under oligotrophic conditions and will not inhibit the nitrification process, therefore can help biofilm system achieve simultaneous nitrification and denitrification.

Quan XC; Cen Y; Qian Y

2013-07-01

13

Isolation of ioxynil degraders from soil-enrichment cultures.  

UK PubMed Central (United Kingdom)

A soil enrichment technique was used to isolate microorganisms which could degrade ioxynil (3,5-diiodo-4-hydroxybenzonitrile). Many isolates obtained were able to degrade ioxynil to various products. However, only a fungal isolate (Fusarium solani) and a Gram-negative bacterium (Klebsiella ozaenae) released 14CO2 from ring-labeled ioxynil. No appreciable degradation was detected in pure cultures without the addition of exogenous nutrients. Results indicated that the degradation of ioxynil to CO2 proceeded more slowly in pure culture. Ioxynil was degraded in pure culture at a faster rate by F. solani than by K. ozaenae. Analyses of radioactivity distribution in the cultures indicated that a sizable fraction of radioactivity was in the form of polar products. Several degradation products were detected in the ethyl acetate extracts by thin-layer chromatography and subsequent radioautography. Screening of pure cultures of ioxynil degraders revealed that most isolates degraded ioxynil to the same products which were extractable with ethyl acetate.

Hsu JC; Camper ND

1976-04-01

14

Who is actively denitrifying in activated sludge?  

DEFF Research Database (Denmark)

Denitrification is of crucial importance in nitrogen removal from wastewater. However, due to the polyphyletic taxonomy of denitrifiers, little is known about the composition and ecophysiology of the actively denitrifying community in activated sludge. To identify the active denitrifiers in a full-scale wastewater treatment plant the transcripts (mRNA) of the nirS, nirK and nosZ denitrification genes expressed under acetate or amino acid consumption were amplified, sequenced and identified. This revealed that the majority of the denitrifiers belonged to Alpha- and Betaproteobacteria, while only few transcripts came from Gammaproteobacteria. A clear taxonomic discrepancy was observed between the nirS and nirK expressing bacteria, which primarily belonged to Beta- and Alphaproteobacteria, respectively. The nosZ gene was expressed by both taxonomic groups and it was therefore surprising that the highest genetic diversity was observed from the nirS transcripts and not the nosZ transcripts. Likewise, denitrifying cultures obtained from the activated sludge affiliated with the same Alpha- and Betaproteobacteria as detected with the denitrification genes, except one culture, which affiliated with Bacteroidetes. Furthermore, potential denitrifying genera of Alpha- and Betaproteobacteria were quantified in the activated sludge with 16S rRNA gene probes for fluorescence in situ hybridization (FISH). This revealed that Aquaspirillum-related bacteria were dominant followed by bacteria related to Azoarcus, Thauera and Paracoccus, respectively. Few bacteria were related to Acidovorax, Zoogloea and Rhodobacter. Except from Aquaspirillum, these genera were also identified with the denitrification genes. The substrate preferences of the bacteria affiliated with these genera were further evaluated by microautoradiography combined with FISH.

Hansen, Aviaja Anna; Nielsen, Jeppe Lund

15

Anaerobic oxidation of acetylene by estuarine sediments and enrichment cultures  

International Nuclear Information System (INIS)

[en] 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

1981-01-01

16

Characterization of Thauera-dominated hydrogen-oxidizing autotrophic denitrifying microbial communities by using high-throughput sequencing.  

UK PubMed Central (United Kingdom)

The present study, for the first time, reported a Thauera-dominated hydrogen-oxidizing autotrophic denitrifying microbial community enriched from different seed sludges including activated sludge and anaerobic digestion sludge. After 244 days enrichment, nitrogen removal rates reached up to 0.2 mg N/mg VSS/d which were comparable to that of the model organism Paracoccus denitrificans under the same conditions. Furthermore, high-throughput sequencing was applied to characterize and compare the seed sludges and enriched cultures. Operational taxonomic units (OTU)-based analysis (97% similarity cutoff) of total 280,000 16S rRNA gene V6 region sequences from 7 sludge samples (40,000 sequences per sample) revealed that the microbial diversity decreased after the enrichment, indicated by OTU numbers drop of 55-60%. Thauera species in the class of ?-Proteobacteria were enriched into the dominant populations with relative abundances of 47-62%, regardless of seed sludge sources.

Mao Y; Xia Y; Zhang T

2013-01-01

17

Effect of carbon source during enrichment on BTEX degradation by anaerobic mixed bacterial cultures.  

Science.gov (United States)

A comprehensive study on the effects of different carbon sources during the bacterial enrichment on the removal performances of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds when present as a mixture was conducted. Batch BTEX removal kinetic experiments were performed using cultures enriched with individual BTEX compounds or BTEX as a mixture or benzoate alone or benzoate-BTEX mixture. An integrated Monod-type non-linear model was developed and a ratio between maximum growth rate (? max) and half saturation constant (Ks) was used to fit the non-linear model. A higher ? max/Ks indicates a higher affinity to degrade BTEX compounds. Complete removal of BTEX mixture was observed by all the enriched cultures; however, the removal rates for individual compounds varied. Degradation rate and the type of removal kinetics were found to be dependent on the type of carbon source during the enrichment. Cultures enriched on toluene and those enriched on BTEX mixture were found to have the greatest ? max/Ks and cultures enriched on benzoate had the least ? max/Ks. Removal performances of the cultures enriched on all different carbon sources, including the ones enriched on benzoate or benzoate-BTEX mixture were also improved during a second exposure to BTEX. A molecular analysis showed that after each exposure to the BTEX mixture, the cultures enriched on benzoate and those enriched on benzoate-BTEX mixture had increased similarities to the culture enriched on BTEX mixture. PMID:22893304

Kasi, Murthy; Wadhawan, Tanush; McEvoy, John; Padmanabhan, G; Khan, Eakalak

2012-08-15

18

Effect of carbon source during enrichment on BTEX degradation by anaerobic mixed bacterial cultures.  

UK PubMed Central (United Kingdom)

A comprehensive study on the effects of different carbon sources during the bacterial enrichment on the removal performances of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds when present as a mixture was conducted. Batch BTEX removal kinetic experiments were performed using cultures enriched with individual BTEX compounds or BTEX as a mixture or benzoate alone or benzoate-BTEX mixture. An integrated Monod-type non-linear model was developed and a ratio between maximum growth rate (? max) and half saturation constant (Ks) was used to fit the non-linear model. A higher ? max/Ks indicates a higher affinity to degrade BTEX compounds. Complete removal of BTEX mixture was observed by all the enriched cultures; however, the removal rates for individual compounds varied. Degradation rate and the type of removal kinetics were found to be dependent on the type of carbon source during the enrichment. Cultures enriched on toluene and those enriched on BTEX mixture were found to have the greatest ? max/Ks and cultures enriched on benzoate had the least ? max/Ks. Removal performances of the cultures enriched on all different carbon sources, including the ones enriched on benzoate or benzoate-BTEX mixture were also improved during a second exposure to BTEX. A molecular analysis showed that after each exposure to the BTEX mixture, the cultures enriched on benzoate and those enriched on benzoate-BTEX mixture had increased similarities to the culture enriched on BTEX mixture.

Kasi M; Wadhawan T; McEvoy J; Padmanabhan G; Khan E

2013-04-01

19

Isolation of oligotrophic denitrifiers carrying previously uncharacterized functional gene sequences.  

UK PubMed Central (United Kingdom)

Oligotrophic denitrifying bacteria, including those belonging to the genera Herbaspirillum, Azospirillum, and Bradyrhizobium, were obtained using a single-cell isolation technique. The taxonomic composition of the denitrifier population was similar to those assessed by previous culture-independent studies. The sequencing of nitrite reductase and N(2)O reductase genes of these strains revealed previously unknown links between 16S rRNA and the denitrification-functional gene phylogenies. In particular, we identified Bradyrhizobium strains that harbor nirS sequences previously detected only in culture-independent studies.

Ishii S; Ashida N; Otsuka S; Senoo K

2011-01-01

20

Isolation of Oligotrophic Denitrifiers Carrying Previously Uncharacterized Functional Gene Sequences? †  

Science.gov (United States)

Oligotrophic denitrifying bacteria, including those belonging to the genera Herbaspirillum, Azospirillum, and Bradyrhizobium, were obtained using a single-cell isolation technique. The taxonomic composition of the denitrifier population was similar to those assessed by previous culture-independent studies. The sequencing of nitrite reductase and N2O reductase genes of these strains revealed previously unknown links between 16S rRNA and the denitrification-functional gene phylogenies. In particular, we identified Bradyrhizobium strains that harbor nirS sequences previously detected only in culture-independent studies.

Ishii, Satoshi; Ashida, Naoaki; Otsuka, Shigeto; Senoo, Keishi

2011-01-01

 
 
 
 
21

Isolation of oligotrophic denitrifiers carrying previously uncharacterized functional gene sequences.  

Science.gov (United States)

Oligotrophic denitrifying bacteria, including those belonging to the genera Herbaspirillum, Azospirillum, and Bradyrhizobium, were obtained using a single-cell isolation technique. The taxonomic composition of the denitrifier population was similar to those assessed by previous culture-independent studies. The sequencing of nitrite reductase and N(2)O reductase genes of these strains revealed previously unknown links between 16S rRNA and the denitrification-functional gene phylogenies. In particular, we identified Bradyrhizobium strains that harbor nirS sequences previously detected only in culture-independent studies. PMID:21075882

Ishii, Satoshi; Ashida, Naoaki; Otsuka, Shigeto; Senoo, Keishi

2010-11-12

22

Facultative autotrophic denitrifiers in denitrifying sulfide removal granules.  

UK PubMed Central (United Kingdom)

The denitrifying sulfide removal (DSR) process applied autotrophic and heterotrophic denitrification pathways to achieve simultaneous conversion of nitrate to N, sulfide to elementary sulfur, and organic substances to CO. However, autotrophic denitrifiers and heterotrophic denitrifiers have to grow at comparable rates so the long-term DSR stability can be maintained. This work assessed the autotrophic and heterotrophic denitrification activities by 16 isolates from anaerobic granules collected from a DSR-expanded granular sludge bed reactor. A group of strains with closest relatives as Pseudomonas sp. (89.9-98.3% similarity), Agrobacterium sp. (94.6% similarity) and Acinetobacter sp. (96.6% similarity) were identified with both autotrophic and heterotrophic denitrification capabilities. These facultative autotrophic denitrifiers can be applied as potential strains for lifting the limitation by balanced growth of two distinct bacterial groups in the DSR reactor.

Lee DJ; Pan X; Wang A; Ho KL

2013-03-01

23

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

Science.gov (United States)

The ability to detect a specific organism from a complex environment is vitally important to many fields of public health, including food safety. For example, tomatoes have been implicated numerous times as vehicles of foodborne outbreaks due to strains of Salmonella but few studies have ever recovered Salmonella from a tomato phyllosphere environment. Precision of culturing techniques that target agents associated with outbreaks depend on numerous factors. One important factor to better understand is which species co-enrich during enrichment procedures and how microbial dynamics may impede or enhance detection of target pathogens. We used a shotgun sequence approach to describe taxa associated with samples pre-enrichment and throughout the enrichment steps of the Bacteriological Analytical Manual's (BAM) protocol for detection of Salmonella from environmental tomato samples. Recent work has shown that during efforts to enrich Salmonella (Proteobacteria) from tomato field samples, Firmicute genera are also co-enriched and at least one co-enriching Firmicute genus (Paenibacillus sp.) can inhibit and even kills strains of Salmonella. Here we provide a baseline description of microflora that co-culture during detection efforts and the utility of a bioinformatic approach to detect specific taxa from metagenomic sequence data. We observed that uncultured samples clustered together with distinct taxonomic profiles relative to the three cultured treatments (Universal Pre-enrichment broth (UPB), Tetrathionate (TT), and Rappaport-Vassiliadis (RV)). There was little consistency among samples exposed to the same culturing medias, suggesting significant microbial differences in starting matrices or stochasticity associated with enrichment processes. Interestingly, Paenibacillus sp. (Salmonella inhibitor) was significantly enriched from uncultured to cultured (UPB) samples. Also of interest was the sequence based identification of a number of sequences as Salmonella despite indication by all media, that samples were culture negative for Salmonella. Our results substantiate the nascent utility of metagenomic methods to improve both biological and bioinformatic pathogen detection methods. PMID:24039862

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

2013-09-09

24

Selenium reduction by a denitrifying consortium  

Energy Technology Data Exchange (ETDEWEB)

A denitrifying bacterial consortium obtained from the Pullman, Washington wastewater treatment facility was enriched under denitrifying conditions and its ability to reduce selenite and selenate was studied. Replicate experiments at two different experimental conditions were performed. All experiments were performed under electron-acceptor limiting conditions, with acetate as the carbon source and nitrate the electron acceptor, in the first set of experiments, selenite was present, whereas, in the second set, selenate was added. A significant lag period of approximately 150 h was necessary before selenite or selenate reduction was observed. During this lag period, nitrate and nitrite use was observed. Once selenite or selenate reduction had started, nitrate and nitrite reduction was concomitant with selenium species reduction. Trace amounts of selenite were detected during the selenate reduction study. Analysis of the data indicates that, once selenium species reduction was induced, the rate of reduction was proportional to the selenium species concentration and to the biomass concentration. Furthermore, at similar biomass and contaminant concentrations, selenite reduction is approximately four times faster than selenate reduction.

Rege, M.A.; Yonge, D.R.; Mendoza, D.P.; Petersen, J.N.; Bereded-Samuel, Y.; Johnstone, D.L. [Washington State Univ., Pullman, WA (United States). Center for Multiphase Environmental Research; Apel, W.A.; Barnes, J.M. [Idaho National Engineering and Environmental Lab., Idaho Falls, ID (United States). Biotechnologies Dept.

1999-02-20

25

Enrichment methodology to increase the positivity of cultures from body fluids  

Directory of Open Access Journals (Sweden)

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

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

2006-01-01

26

Characterization of an Enriched Anaerobic Culture Having Ability to Dechlorinate TCE  

Science.gov (United States)

An anaerobic mixed microbial culture was enriched from soil and groundwater taken from a site contaminated with trichloroethene (TCE). This enrichment culture could dechlorinate TCE sequentially to cis-dichloroethene (cis-DCE), vinyl chloride (VC), and ethene rapidly within 2 weeks. This enrichment culture could utilize various organic compounds, such as methanol, ethanol, and sodium acetate and so on, as electron donor. This culture had maintained high ability of TCE dechlorination for about 3 years since the start of enrichment cultivation. The optimum pH value for the dechlorination activity of this culture, which reacts from TCE to ethene, was 6.7. However above the pH value 7.1, it lost the dechlorination ability of cis-DCE and VC. So cis-DCE was remained at that pH conditions. From the DNA sequencing analysis of 16SrRNA gene, this enrichment culture includes Dehalococcoides sp. which has the ability to dechlorinate TCE to VC completely with hydrogen. It suggested that this Dehalococcoides sp. takes part in the dechlorination of chloroethenes.

Ise, K.; Suto, K.; Inoue, C.

2007-03-01

27

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

2011-09-29

28

Eureka: The Cross-Cultural Model for Identifying Hidden Talent through Enrichment.  

Science.gov (United States)

Describes the Eureka cross-cultural model that is designed to assist in identification of hidden potential in the visual arts and sciences through the process of enrichment among elementary children from different socioeconomic or cultural backgrounds in Israel. Positive findings from a longitudinal study of the program are discussed. (CR)

Zorman, Rachel

1997-01-01

29

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-12-31

30

Enrichment and characterization of a bacterial culture that can degrade 4-aminopyridine.  

UK PubMed Central (United Kingdom)

BACKGROUND: The agrichemical 4-aminopyridine is used as a bird repellent in crop fields and has an epileptogenic action in a variety of animals, including man and mouse. 4-Aminopyridine is biodegraded in the environment through an unknown mechanism. RESULTS: A 4-aminopyridine-degrading enrichment culture utilized 4-aminopyridine as a carbon, nitrogen, and energy source, generating 4-amino-3-hydroxypyridine, 3,4-dihydroxypyridine, and formate as intermediates. 4-Amino-3-hydroxypyridine could not be further metabolized and probably accumulated as a dead-end product in the culture. Biodegradability tests and partial sequence analysis of the enrichment culture indicated that 4-aminopyridine was mainly degraded via 3,4-dihydroxypyridine and that the metabolite is probably cleaved by 3-hydroxy-4-pyridone dioxygenase. Seven culturable predominant bacterial strains (strains 4AP-A to 4AP-G) were isolated on nutrient agar plates. Changes in the bacterial populations of 4-aminopyridine, 3,4-dihydroxypyridine, or formate/ammonium chloride enrichment cultures were monitored by denaturing gradient gel electrophoresis (DGGE) profiling of PCR-amplified 16S rRNA gene fragments. Sequence analysis of the 16S rRNA gene fragments derived from predominant DGGE bands indicated that Pseudomonas nitroreducens 4AP-A and Enterobacter sp. 4AP-G were predominant in the three tested enrichment cultures and that the unculturable strains Hyphomicrobium sp. 4AP-Y and Elizabethkingia sp. 4AP-Z were predominant in 4-aminopyridine and formate/ammonium chloride enrichment cultures and in the 3,4-dihydroxypyridine enrichment culture, respectively. Among the culturable strains, strain 4AP-A could utilize 3,4-dihydroxypyridine as a growth substrate. Although we could not isolate strain 4AP-Y on several media, PCR-DGGE analysis and microscopy indicated that the unique bi-polar filamentous bacterial cells gradually became more dominant with increasing 4-aminopyridine concentration in the medium. CONCLUSIONS: Hyphomicrobium sp. 4AP-Y, P. nitroreducens 4AP-A, and Elizabethkingia sp. 4AP-Z probably play important roles in 4-aminopyridine degradation in crop fields. In the enrichment culture, 3,4-dihydroxypyridine and its metabolites including formate might be shared as growth substrates and maintain the enrichment culture, including these indispensable strains.

Takenaka S; Nomura R; Minegishi A; Yoshida K

2013-01-01

31

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

UK PubMed Central (United Kingdom)

AIMS: The aim of this study was to enrich, characterize and identify strict anaerobic extreme thermophilic hydrogen (H(2)) producers from digested household solid wastes. METHODS AND RESULTS: A strict anaerobic extreme thermophilic H(2) producing bacterial culture was enriched from a lab-scale digester treating household wastes at 70 degrees C. The enriched mixed culture consisted of two rod-shaped bacterial members growing at an optimal temperature of 80 degrees C and an optimal pH 8.1. The culture was able to utilize glucose, galactose, mannose, xylose, arabinose, maltose, sucrose, pyruvate and glycerol as carbon sources. Growth on glucose produced acetate, H(2) and carbon dioxide. Maximal H(2) production rate on glucose was 1.1 mmol l(-1) h(-1) with a maximum H(2) yield of 1.9 mole H(2) per mole glucose. 16S ribosomal DNA clone library analyses showed that the culture members were phylogenetically affiliated to the genera Bacillus and Clostridium. Relative abundance of the culture members, assessed by fluorescence in situ hybridization, were 87 +/- 5% and 13 +/- 5% for Bacillus and Clostridium, respectively. CONCLUSIONS: An extreme thermophilic, strict anaerobic, mixed microbial culture with H(2)-producing potential was enriched from digested household wastes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided a culture with a potential to be applied in reactor systems for extreme thermophilic H(2) production from complex organic wastes.

Karakashev D; Kotay SM; Trably E; Angelidaki I

2009-03-01

32

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

DEFF Research Database (Denmark)

The aim of this study was to enrich, characterize and identify strict anaerobic extreme thermophilic hydrogen (H-2) producers from digested household solid wastes. A strict anaerobic extreme thermophilic H-2 producing bacterial culture was enriched from a lab-scale digester treating household wastes at 70 degrees C. The enriched mixed culture consisted of two rod-shaped bacterial members growing at an optimal temperature of 80 degrees C and an optimal pH 8.1. The culture was able to utilize glucose, galactose, mannose, xylose, arabinose, maltose, sucrose, pyruvate and glycerol as carbon sources. Growth on glucose produced acetate, H-2 and carbon dioxide. Maximal H-2 production rate on glucose was 1.1 mmol l(-1) h(-1) with a maximum H-2 yield of 1.9 mole H-2 per mole glucose. 16S ribosomal DNA clone library analyses showed that the culture members were phylogenetically affiliated to the genera Bacillus and Clostridium. Relative abundance of the culture members, assessed by fluorescence in situ hybridization, were 87 +/- 5% and 13 +/- 5% for Bacillus and Clostridium, respectively. An extreme thermophilic, strict anaerobic, mixed microbial culture with H-2-producing potential was enriched from digested household wastes. This study provided a culture with a potential to be applied in reactor systems for extreme thermophilic H-2 production from complex organic wastes.

Karakashev, Dimitar Borisov; Kotay, Shireen Meher

2009-01-01

33

Effects of heat treatment on hydrogen production potential and microbial community of thermophilic compost enrichment cultures.  

UK PubMed Central (United Kingdom)

Cellulosic plant and waste materials are potential resources for fermentative hydrogen production. In this study, hydrogen producing, cellulolytic cultures were enriched from compost material at 52, 60 and 70°C. Highest cellulose degradation and highest H(2) yield were 57% and 1.4 mol-H(2) mol-hexose(-1) (2.4 mol-H(2) mol-hexose-degraded(-1)), respectively, obtained at 52°C with the heat-treated (80°C for 20 min) enrichment culture. Heat-treatments as well as the sequential enrichments decreased the diversity of microbial communities. The enrichments contained mainly bacteria from families Thermoanaerobacteriaceae and Clostridiaceae, from which a bacterium closely related to Thermoanaerobium thermosaccharolyticum was mainly responsible for hydrogen production and bacteria closely related to Clostridium cellulosi and Clostridium stercorarium were responsible for cellulose degradation.

Nissilä ME; Tähti HP; Rintala JA; Puhakka JA

2011-03-01

34

Effects of heat treatment on hydrogen production potential and microbial community of thermophilic compost enrichment cultures.  

Science.gov (United States)

Cellulosic plant and waste materials are potential resources for fermentative hydrogen production. In this study, hydrogen producing, cellulolytic cultures were enriched from compost material at 52, 60 and 70°C. Highest cellulose degradation and highest H(2) yield were 57% and 1.4 mol-H(2) mol-hexose(-1) (2.4 mol-H(2) mol-hexose-degraded(-1)), respectively, obtained at 52°C with the heat-treated (80°C for 20 min) enrichment culture. Heat-treatments as well as the sequential enrichments decreased the diversity of microbial communities. The enrichments contained mainly bacteria from families Thermoanaerobacteriaceae and Clostridiaceae, from which a bacterium closely related to Thermoanaerobium thermosaccharolyticum was mainly responsible for hydrogen production and bacteria closely related to Clostridium cellulosi and Clostridium stercorarium were responsible for cellulose degradation. PMID:21251819

Nissilä, Marika E; Tähti, Hanne P; Rintala, Jukka A; Puhakka, Jaakko A

2010-12-24

35

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; Dmitri Sobolev

2013-01-01

36

Enriching Chinese Cultural Heritage at the Queens Library  

Directory of Open Access Journals (Sweden)

Full Text Available ???13-18The Queens Borough Public Library through its New Americans Program has been providing opportunities for the Chinese Community to experience quality library service for many years. By building collections, providing opportunities to learn English, providing job information, coping skills classes, cultural programs and electronic access to Chinese vernacular script, the Library provides a unique public library experience to its many immigrants. Through demographic analysis, the Library places its collections in the communities where immigrants live and provides programs of relevance to celebrate the cultures and traditions of the Chinese community.

? Gary E. Strong

2001-01-01

37

Preparation of rodent primary cultures for neuron-glia, mixed glia, enriched microglia, and reconstituted cultures with microglia.  

UK PubMed Central (United Kingdom)

Microglia, neurons, and macroglia (astrocytes and oligodendrocytes) are the major cell types in the central nervous system. In the past decades, primary microglia-enriched cultures have been widely used to study the biological functions of microglia in vitro. In order to study the interactions between microglia and other brain cells, neuron-glia, neuron-microglia, and mixed glia cultures were developed. The aim of this chapter is to provide basic and adaptable protocols for the preparation of these microglia-containing primary cultures from rodent. Meanwhile, we also want to provide a collection of tips from our collective experiences doing primary brain cell cultures.

Chen SH; Oyarzabal EA; Hong JS

2013-01-01

38

Atrazine degradation by stable mixed cultures enriched from agricultural soil and their characterization.  

UK PubMed Central (United Kingdom)

AIMS: The aim of this work was to enrich stable mixed cultures from atrazine-contaminated soil. The cultures were examined for their atrazine biodegradation efficiencies in comparison with J14a, a known atrazine-degrading strain of Agrobacterium radiobacter. The cultures were also characterized to identify community structure and bacterial species present. METHODS AND RESULTS: The cultures were enriched and then stabilized in bacterial media. The stable mixed cultures and J14a were tested in a medium containing 100 microg l(-1) of atrazine. For all cultures, atrazine was removed 33-51% within 7 days and the cell optical density increased from 0.05 to between 0.50 and 0.70. Four isolates designated ND1, ND2, ND3 and ND4 were purified from the mixed cultures and identified based on sequence analysis of the 16 S rRNA gene as Alcaligenes faecalis, Klebsiella ornithinolytica, Bacillus megaterium and Agrobacterium tumefaciens, respectively. An atrazine-degrading gene, atzA, was present in ND2 and ND4. CONCLUSIONS: The stable mixed cultures obtained could degrade atrazine. Klebsiella ornithinolytica ND2 and Ag. tumefaciens ND4 are atrazine degraders. SIGNIFICANCE AND IMPACT OF THE STUDY: The novel stable mixed cultures could be used for bioremediating crop fields contaminated with atrazine. This is the first report of the atzA gene in Kl. ornithinolytica.

Siripattanakul S; Wirojanagud W; McEvoy J; Limpiyakorn T; Khan E

2009-03-01

39

Tetrachloroethene conversion to ethene by a Dehalococcoides-containing enrichment culture from Bitterfeld.  

Science.gov (United States)

A Dehalococcoides-dominated culture coupling reductive dechlorination of tetrachloroethene (PCE) to ethene to growth was enriched from a European field site for the first time. Microcosms were set up using groundwater from a chlorinated ethene-contaminated anaerobic aquifer in Bitterfeld (Germany). Active, lactate-amended microcosms capable of PCE dechlorination to ethene without the accumulation of intermediates were used for further enrichment. After three transfers on lactate as an electron donor and PCE as an electron acceptor, the enrichment was transferred to parallel cultures with one of the chlorinated ethenes as an electron acceptor and acetate and hydrogen as the carbon and energy source, respectively. After three more transfers, a highly purified culture was derived that was capable of dechlorinating PCE with hydrogen and acetate as the electron donor and carbon source, respectively. PCR, followed by denaturing gradient gel electrophoresis, cloning and sequencing revealed that this culture was dominated by a Dehalococcoides sp. belonging to the Pinellas group. Investigation of substrate specificity in the parallel cultures suggested the presence of a novel Dehalococcoides that can couple all dechlorination steps, from PCE to ethene, to energy conservation. Quantitative real-time PCR confirmed growth with PCE, cis-dichloroethene, 1,1-dichloroethene or vinyl chloride as electron acceptors. The culture was designated BTF08 due to its origin in Bitterfeld. PMID:20507364

Cichocka, Danuta; Nikolausz, Marcell; Haest, Pieter Jan; Nijenhuis, Ivonne

2010-05-01

40

Tetrachloroethene conversion to ethene by a Dehalococcoides-containing enrichment culture from Bitterfeld.  

UK PubMed Central (United Kingdom)

A Dehalococcoides-dominated culture coupling reductive dechlorination of tetrachloroethene (PCE) to ethene to growth was enriched from a European field site for the first time. Microcosms were set up using groundwater from a chlorinated ethene-contaminated anaerobic aquifer in Bitterfeld (Germany). Active, lactate-amended microcosms capable of PCE dechlorination to ethene without the accumulation of intermediates were used for further enrichment. After three transfers on lactate as an electron donor and PCE as an electron acceptor, the enrichment was transferred to parallel cultures with one of the chlorinated ethenes as an electron acceptor and acetate and hydrogen as the carbon and energy source, respectively. After three more transfers, a highly purified culture was derived that was capable of dechlorinating PCE with hydrogen and acetate as the electron donor and carbon source, respectively. PCR, followed by denaturing gradient gel electrophoresis, cloning and sequencing revealed that this culture was dominated by a Dehalococcoides sp. belonging to the Pinellas group. Investigation of substrate specificity in the parallel cultures suggested the presence of a novel Dehalococcoides that can couple all dechlorination steps, from PCE to ethene, to energy conservation. Quantitative real-time PCR confirmed growth with PCE, cis-dichloroethene, 1,1-dichloroethene or vinyl chloride as electron acceptors. The culture was designated BTF08 due to its origin in Bitterfeld.

Cichocka D; Nikolausz M; Haest PJ; Nijenhuis I

2010-05-01

 
 
 
 
41

Biodegradation of endocrine disruptors in solid-liquid two-phase partitioning systems by enrichment cultures.  

UK PubMed Central (United Kingdom)

Naturally occurring and synthetic estrogens and other molecules from industrial sources strongly contribute to the endocrine disruption of urban wastewater. Because of the presence of these molecules in low but effective concentrations in wastewaters, these endocrine disruptors (EDs) are only partially removed after most wastewater treatments, reflecting the presence of these molecules in rivers in urban areas. The development of a two-phase partitioning bioreactor (TPPB) might be an effective strategy for the removal of EDs from wastewater plant effluents. Here, we describe the establishment of three ED-degrading microbial enrichment cultures adapted to a solid-liquid two-phase partitioning system using Hytrel as the immiscible water phase and loaded with estrone, estradiol, estriol, ethynylestradiol, nonylphenol, and bisphenol A. All molecules except ethynylestradiol were degraded in the enrichment cultures. The bacterial composition of the three enrichment cultures was determined using 16S rRNA gene sequencing and showed sequences affiliated with bacteria associated with the degradation of these compounds, such as Sphingomonadales. One Rhodococcus isolate capable of degrading estrone, estradiol, and estriol was isolated from one enrichment culture. These results highlight the great potential for the development of TPPB for the degradation of highly diluted EDs in water effluents.

Villemur R; Dos Santos SC; Ouellette J; Juteau P; Lépine F; Déziel E

2013-08-01

42

Dichloromethane Fermentation by a Dehalobacter sp. in an Enrichment Culture Derived from Pristine River Sediment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dichloromethane (DCM) as the sole substrate supported growth of a Dehalobacter sp. in an enrichment culture derived from noncontaminated river sediment. DCM was not reductively dechlorinated, and acetate was produced, indicating DCM fermentation and further suggesting Dehalobacter growth is not limi...

Justicia-Leon, Shandra D.; Ritalahti, Kirsti M.; Mack, E. Erin; Löffler, Frank E.

43

Biodegradation of endocrine disruptors in solid-liquid two-phase partitioning systems by enrichment cultures.  

Science.gov (United States)

Naturally occurring and synthetic estrogens and other molecules from industrial sources strongly contribute to the endocrine disruption of urban wastewater. Because of the presence of these molecules in low but effective concentrations in wastewaters, these endocrine disruptors (EDs) are only partially removed after most wastewater treatments, reflecting the presence of these molecules in rivers in urban areas. The development of a two-phase partitioning bioreactor (TPPB) might be an effective strategy for the removal of EDs from wastewater plant effluents. Here, we describe the establishment of three ED-degrading microbial enrichment cultures adapted to a solid-liquid two-phase partitioning system using Hytrel as the immiscible water phase and loaded with estrone, estradiol, estriol, ethynylestradiol, nonylphenol, and bisphenol A. All molecules except ethynylestradiol were degraded in the enrichment cultures. The bacterial composition of the three enrichment cultures was determined using 16S rRNA gene sequencing and showed sequences affiliated with bacteria associated with the degradation of these compounds, such as Sphingomonadales. One Rhodococcus isolate capable of degrading estrone, estradiol, and estriol was isolated from one enrichment culture. These results highlight the great potential for the development of TPPB for the degradation of highly diluted EDs in water effluents. PMID:23728808

Villemur, Richard; Dos Santos, Silvia Cristina Cunha; Ouellette, Julianne; Juteau, Pierre; Lépine, François; Déziel, Eric

2013-05-31

44

Phylogenetic and functional diversity of denitrifying bacteria isolated from various rice paddy and rice-soybean rotation fields.  

UK PubMed Central (United Kingdom)

Denitrifiers can produce and consume nitrous oxide (N(2)O). While little N(2)O is emitted from rice paddy soil, the same soil produces N(2)O when the land is drained and used for upland crop cultivation. In this study, we collected soils from two types of fields each at three locations in Japan; one type of field had been used for continuous cultivation of rice and the other for rotational cultivation of rice and soybean. Active denitrifiers were isolated from these soils using a functional single-cell isolation method, and their taxonomy and denitrifying properties were examined. A total of 110 denitrifiers were obtained, including those previously detected by a culture-independent analysis. Strains belonging to the genus Pseudogulbenkiania were dominant at all locations, suggesting that Pseudogulbenkiania denitrifiers are ubiquitous in various rice paddy soils. Potential denitrifying activity was similar among the strains, regardless of the differences in taxonomic position and soil of origin. However, relative amounts of N(2) in denitrification end products varied among strains isolated from different locations. Our results also showed that crop rotation had minimal impact on the functional diversity of the denitrifying strains. These results indicate that soil and other environmental factors, excluding cropping systems, could select for N(2)-producing denitrifiers.

Tago K; Ishii S; Nishizawa T; Otsuka S; Senoo K

2011-01-01

45

Phylogenetic and functional diversity of denitrifying bacteria isolated from various rice paddy and rice-soybean rotation fields.  

Science.gov (United States)

Denitrifiers can produce and consume nitrous oxide (N(2)O). While little N(2)O is emitted from rice paddy soil, the same soil produces N(2)O when the land is drained and used for upland crop cultivation. In this study, we collected soils from two types of fields each at three locations in Japan; one type of field had been used for continuous cultivation of rice and the other for rotational cultivation of rice and soybean. Active denitrifiers were isolated from these soils using a functional single-cell isolation method, and their taxonomy and denitrifying properties were examined. A total of 110 denitrifiers were obtained, including those previously detected by a culture-independent analysis. Strains belonging to the genus Pseudogulbenkiania were dominant at all locations, suggesting that Pseudogulbenkiania denitrifiers are ubiquitous in various rice paddy soils. Potential denitrifying activity was similar among the strains, regardless of the differences in taxonomic position and soil of origin. However, relative amounts of N(2) in denitrification end products varied among strains isolated from different locations. Our results also showed that crop rotation had minimal impact on the functional diversity of the denitrifying strains. These results indicate that soil and other environmental factors, excluding cropping systems, could select for N(2)-producing denitrifiers. PMID:21487200

Tago, Kanako; Ishii, Satoshi; Nishizawa, Tomoyasu; Otsuka, Shigeto; Senoo, Keishi

2011-01-01

46

Identification of triclosan-degrading bacteria in a triclosan enrichment culture using stable isotope probing.  

UK PubMed Central (United Kingdom)

Triclosan, a widely used antimicrobial agent, is an emerging contaminant in the environment. Despite its antimicrobial character, biodegradation of triclosan has been observed in pure cultures, soils and activated sludge. However, little is known about the microorganisms responsible for the degradation in mixed cultures. In this study, active triclosan degraders in a triclosan-degrading enrichment culture were identified using stable isotope probing (SIP) with universally (13)C-labeled triclosan. Eleven clones contributed from active microorganisms capable of uptake the (13)C in triclosan were identified. None of these clones were similar to known triclosan-degraders/utilizers. These clones distributed among ?-, ?-, or ?-Proteobacteria: one belonging to Defluvibacter (?-Proteobacteria), seven belonging to Alicycliphilus (?-Proteobacteria), and three belonging to Stenotrophomonas (?-Proteobacteria). Successive additions of triclosan caused a significant shift in the microbial community structure of the enrichment culture, with dominant ribotypes belonging to the genera Alicycliphilus and Defluvibacter. Application of SIP has successfully identified diverse uncultivable triclosan-degrading microorganisms in an activated sludge enrichment culture. The results of this study not only contributed to our understanding of the microbial ecology of triclosan biodegradation in wastewater, but also suggested that triclosan degraders are more phylogenetically diverse than previously reported.

Lee DG; Cho KC; Chu KH

2013-04-01

47

Identification of triclosan-degrading bacteria in a triclosan enrichment culture using stable isotope probing.  

Science.gov (United States)

Triclosan, a widely used antimicrobial agent, is an emerging contaminant in the environment. Despite its antimicrobial character, biodegradation of triclosan has been observed in pure cultures, soils and activated sludge. However, little is known about the microorganisms responsible for the degradation in mixed cultures. In this study, active triclosan degraders in a triclosan-degrading enrichment culture were identified using stable isotope probing (SIP) with universally (13)C-labeled triclosan. Eleven clones contributed from active microorganisms capable of uptake the (13)C in triclosan were identified. None of these clones were similar to known triclosan-degraders/utilizers. These clones distributed among ?-, ?-, or ?-Proteobacteria: one belonging to Defluvibacter (?-Proteobacteria), seven belonging to Alicycliphilus (?-Proteobacteria), and three belonging to Stenotrophomonas (?-Proteobacteria). Successive additions of triclosan caused a significant shift in the microbial community structure of the enrichment culture, with dominant ribotypes belonging to the genera Alicycliphilus and Defluvibacter. Application of SIP has successfully identified diverse uncultivable triclosan-degrading microorganisms in an activated sludge enrichment culture. The results of this study not only contributed to our understanding of the microbial ecology of triclosan biodegradation in wastewater, but also suggested that triclosan degraders are more phylogenetically diverse than previously reported. PMID:23592331

Lee, Do Gyun; Cho, Kun-Ching; Chu, Kung-Hui

2013-04-17

48

Anaerobic degradation of 3-halobenzoates by a denitrifying bacterium.  

UK PubMed Central (United Kingdom)

A denitrifying bacterium was isolated from a river sediment after enrichment on 3-chlorobenzoate under anoxic, denitrifying conditions. The bacterium, designated strain 3CB-1, degraded 3-chlorobenzoate, 3-bromobenzoate, and 3-iodobenzoate with stoichiometric release of halide under conditions supporting anaerobic growth by denitrification. The 3-halobenzoates and 3-hydroxybenzoate were used as growth substrates with nitrate as the terminal electron acceptor. The doubling time when growing on 3-halobenzoates ranged from 18 to 25 h. On agar plates with 1 mM 3-chlorobenzoate as the sole carbon source and 30 mM nitrate as the electron acceptor, strain 3CB-1 formed small colonies (1-2 mm in diameter) in 2 to 3 weeks. Anaerobic degradation of both 3-chlorobenzoate and 3-hydroxybenzoate was dependent on nitrate as an electron acceptor and resulted in nitrate reduction corresponding to the stoichiometric values for complete oxidation of the substrate to CO2. 3-Chlorobenzoate was not degraded in the presence of oxygen. 3-Bromobenzoate and 3-iodobenzoate were also degraded under denitrifying conditions with stoichiometric release of halide, but 3-fluorobenzoate was not utilized by the bacterium. Utilization of 3-chlorobenzoate was inducible, while synthesis of enzymes for 3-hydroxybenzoate degradation was constitutively low, but inducible. Degradation was specific to the positive of the halogen substituent, and strain 3CB-1 did not utilize 2- or 4-chlorobenzoate.

Häggblom MM; Young LY

1999-03-01

49

Prospecting for ice association: characterization of freeze-thaw selected enrichment cultures from latitudinally distant soils.  

UK PubMed Central (United Kingdom)

Freeze-thaw stress has previously been shown to alter soil community structure and function. We sought to further investigate this stress on enriched microbial consortia with the aim of identifying microbes with ice-associating adaptations that facilitate survival. Enrichments were established to obtain culturable psychrotolerant microbes from soil samples from the latitudinal extremes of the Canadian Shield plateau. The resulting consortia were subjected to consecutive freeze-thaw cycles, and survivors were putatively identified by their 16S rRNA gene sequences. Even though the northerly site was exposed to longer, colder winters and large spring-time temperature fluctuations, the selective regime similarly affected both enriched consortia. Quantitative PCR and metagenomic sequencing were used to determine the frequency of a subset of the resistant microbes in the original enrichments. The metagenomes showed 22 initial genera, only 6 survived and these were not dominant prior to selection. When survivors were assayed for ice recrystallization inhibition and ice nucleation activities, over 60% had at least one of these properties. These phenotypes were not more prevalent in the northern enrichment, indicating that regarding these adaptations, the enrichment strategy yielded seemingly functionally similar consortia from each site.

Wilson SL; Grogan P; Walker VK

2012-04-01

50

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

51

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

Energy Technology Data Exchange (ETDEWEB)

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. 33 references.

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

1986-01-01

52

Development and Characterization of Stable Sediment-Free Anaerobic Bacterial Enrichment Cultures That Dechlorinate Aroclor 1260  

Science.gov (United States)

We have developed sediment-free anaerobic enrichment cultures that dechlorinate a broad spectrum of highly chlorinated polychlorinated biphenyls (PCBs). The cultures were developed from Aroclor 1260-contaminated sediment from the Housatonic River in Lenox, MA. Sediment slurries were primed with 2,6-dibromobiphenyl to stimulate Process N dechlorination (primarily meta dechlorination), and sediment was gradually removed by successive transfers (10%) to minimal medium. The cultures grow on pyruvate, butyrate, or acetate plus H2. Gas chromatography-electron capture detector analysis demonstrated that the cultures extensively dechlorinate 50 to 500 ?g/ml of Aroclor 1260 at 22 to 24°C by Dechlorination Process N. Triplicate cultures of the eighth transfer without sediment dechlorinated 76% of the hexa- through nonachlorobiphenyls in Aroclor 1260 (250 ?g/ml) to tri- through pentachlorobiphenyls in 110 days. At least 64 PCB congeners, all of which are chlorinated on both rings and 47 of which have six or more chlorines, were substrates for this dechlorination. To characterize the bacterial diversity in the enrichments, we used eubacterial primers to amplify and clone 16S rRNA genes from DNA extracted from cultures grown on acetate plus H2. Restriction fragment length polymorphism analysis of 107 clones demonstrated the presence of Thauera-like Betaproteobacteria, Geobacter-like Deltaproteobacteria, Pseudomonas species, various Clostridiales, Bacteroidetes, Dehalococcoides of the Chloroflexi group, and unclassified Eubacteria. Our development of highly enriched, robust, stable, sediment-free cultures that extensively dechlorinate a highly chlorinated commercial PCB mixture is a major and unprecedented breakthrough in the field. It will enable intensive study of the organisms and genes responsible for a major PCB dechlorination process that occurs in the environment and could also lead to effective remediation applications.

Bedard, Donna L.; Bailey, Jessica J.; Reiss, Brandon L.; Jerzak, Greta Van Slyke

2006-01-01

53

Cryopreservation of Cortical Tissue Blocks for the Generation of Highly Enriched Neuronal Cultures  

Science.gov (United States)

In this study, we outline a standardized protocol for the successful cryopreservation and thawing of cortical brain tissue blocks to generate highly enriched neuronal cultures. For this protocol the freezing medium used is 10% dimethyl sulfoxide (DMSO) diluted in Hank's Buffered Salt Solution (HBSS). Blocks of cortical tissue are transferred to cryovials containing the freezing medium and slowly frozen at -1°C/min in a rate-controlled freezing container. Post-thaw processing and dissociation of frozen tissue blocks consistently produced neuronal-enriched cultures which exhibited rapid neuritic growth during the first 5 days in culture and significant expansion of the neuronal network within 10 days. Immunocytochemical staining with the astrocytic marker glial fibrillary acidic protein (GFAP) and the neuronal marker beta-tubulin class III, revealed high numbers of neurons and astrocytes in the cultures. Generation of neural precursor cell cultures after tissue block dissociation resulted in rapidly expanding neurospheres, which produced large numbers of neurons and astrocytes under differentiating conditions. This simple cryopreservation protocol allows for the rapid, efficient, and inexpensive preservation of cortical brain tissue blocks, which grants increased flexibility for later generation of neuronal, astrocyte, and neuronal precursor cell cultures.

Rahman, Ardeshir S.; Parvinjah, Shaudee; Hanna, Michael A.; Helguera, Pablo R.; Busciglio, Jorge

2010-01-01

54

Effect of dissolved oxygen concentration (microaerobic and aerobic) on selective enrichment culture for bioaugmentation of acidic industrial wastewater.  

UK PubMed Central (United Kingdom)

The successful application of bioaugmentation is largely dependent on the selective enrichment of culture with regards to pH, temperature, salt, or specific toxic organic pollutants. In this study, we investigated the effect of dissolved oxygen (DO) concentrations (aerobic, >2 mg L(-1); microaerobic, <1 mg L(-1)) on yeast enrichment culture for bioaugmentation of acidic industrial wastewater (pH 3.9-4.7). Clone library analyses revealed that the yeast community shifted in response to different DO levels, and that Candida humilis and Candida pseudolambica were individually dominant in the aerobic and microaerobic enrichment cultures. This would significantly influence the isolation results, and further hinder bioaugmentation due to differences in DO environments during the enrichment and application periods. However, differences in the selective enrichment culture cannot be predicted based on differences in pollutant removal performance. Thus, DO concentrations (aerobic/microaerobic) should be considered a secondary selective pressure to achieve successful bioaugmentation.

Quan Y; Han H; Zheng S

2012-09-01

55

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; Beri? Dejan; Jovi?i? Ana

2013-01-01

56

Role of sulfate concentration in dechlorination of 3,4,5-trichlorocatechol by stable enrichment cultures grown with coumarin and flavanone glycones and aglycones.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Metabolically stable anaerobic enrichment cultures have been obtained from sediment samples contaminated with chlorophenolic compounds. Enrichment was carried out with esculin, esculetin, naringin, naringenin, fraxin, quercetin, and acetate in media with two sulfate concentrations. These cultures we...

Allard, A S; Hynning, P A; Remberger, M; Neilson, A H

57

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

58

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 mammalian intestinal microbiota is fermentation of plant cell wall components. Eight-week continuous culture enrichments of pig feces with cellulose and xylan/pectin were used to isolate bacteria from this community. A total of 575 bacterial isolates were classified phylogenetically using 16S rRNA gene sequencing. Six phyla were represented in the bacterial isolates: Firmicutes (242), Bacteroidetes (185), Proteobacteria (65), Fusobacteria (55), Actinobacteria (23), and Synergistetes (5). The majority of the bacterial isolates had ? 97 % similarity to cultured bacteria with sequences in the RDP, but 179 isolates represent new species and/or genera. Within the Firmicutes isolates, most were classified in the families of Lachnospiraceae, Enterococcaceae, Staphylococcaceae, and Clostridiaceae I. The majority of the Bacteroidetes were most closely related to Bacteroides thetaiotaomicron, Bacteroides ovatus, and B. xylanisolvens. Many of the Firmicutes and Bacteroidetes isolates were identified as species that possess enzymes that ferment plant cell wall components, and the rest likely support these bacteria. The microbial communities that arose in these enrichment cultures had broad bacterial diversity. With over 30 % of the isolates not represented in culture, there are new opportunities to study genomic and metabolic capacities of these members of the complex intestinal microbiota. PMID:23354293

Ziemer, Cherie J

2013-01-29

59

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

UK PubMed Central (United Kingdom)

One of the fascinating functions of mammalian intestinal microbiota is fermentation of plant cell wall components. Eight-week continuous culture enrichments of pig feces with cellulose and xylan/pectin were used to isolate bacteria from this community. A total of 575 bacterial isolates were classified phylogenetically using 16S rRNA gene sequencing. Six phyla were represented in the bacterial isolates: Firmicutes (242), Bacteroidetes (185), Proteobacteria (65), Fusobacteria (55), Actinobacteria (23), and Synergistetes (5). The majority of the bacterial isolates had ? 97 % similarity to cultured bacteria with sequences in the RDP, but 179 isolates represent new species and/or genera. Within the Firmicutes isolates, most were classified in the families of Lachnospiraceae, Enterococcaceae, Staphylococcaceae, and Clostridiaceae I. The majority of the Bacteroidetes were most closely related to Bacteroides thetaiotaomicron, Bacteroides ovatus, and B. xylanisolvens. Many of the Firmicutes and Bacteroidetes isolates were identified as species that possess enzymes that ferment plant cell wall components, and the rest likely support these bacteria. The microbial communities that arose in these enrichment cultures had broad bacterial diversity. With over 30 % of the isolates not represented in culture, there are new opportunities to study genomic and metabolic capacities of these members of the complex intestinal microbiota.

Ziemer CJ

2013-08-01

60

Essential fatty acid enrichment of cultured rotifers (Brachionus plicatilis, Muller) using frozen-concentrated microalgae  

UK PubMed Central (United Kingdom)

There is a growing interest in preserving microalgal preparations to maintain constant properties over a long period. The aim is to ensure sufficient delivery of essential fatty acids (and other key nutrients) to mollusc and crustacean larvae and to zooplankton used as live prey in the first feeding of fish larvae. For example, the rotifer Brachionus plicatilis has to be enriched with polyunsaturated fatty acids (PUFA) prior to fish feeding. We used four microalgal species [Isochrysis galbana (T-ISO), Chaetoceros muelleri (CHGRA), Pavlova lutheri (MONO), and Nannochloropsis sp.] both as fresh culture or in a frozen-concentrated form to enrich rotifers. Overall, rotifers had similar relative fatty acid levels when fed the frozen-concentrated or fresh microalgal diets. The levels of 20:4n-6, 22:6n-3, and 20:5n-3 between B. plicatilis and the microalgal diets were linearly correlated. The fatty acid 20:4n-6 was the most readily assimilated: the content found in rotifers reached half the level measured in the microalgal diets. Our results indicate that both the fresh and frozen-concentrated forms of the four microalgal species can be used to enrich PUFA levels in rotifers. Further experiments should be conducted to test if assimilation differs when rotifers are enriched with mono- or multispecific microalgal preparations.

SEYCHELLES LH; AUDET C; TREMBLAY R; FOURNIER R; PERNET F

2009-08-01

 
 
 
 
61

Biodegradation of munitions compounds by a sulfate reducing bacterial enrichment culture  

Energy Technology Data Exchange (ETDEWEB)

The degradation of several munitions compounds was studied. The compounds included 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine, 2,4,6-trinitrobenzene (TNB), and 2,4-dinitrotoluene. All of the compounds studied were degraded by the sulfate reducing bacterial (SRB) enrichment culture. The SRB culture did not use the munitions compounds as their sole source of carbon. However, all the munitions compounds tested served as the sole source of nitrogen for the SRB culture. Degradation of munitions compounds was achieved by a co-metabolic process. The SRB culture used a variety of carbon sources including pyruvate, ethanol, formate, lactate, and H{sub 2}-CO{sub 2}. The SRB culture was an incomplete oxidizer, unable to carry out the terminal oxidation of organic substrates to CO{sub 2} as the sole product, and it did not use acetate or methanol as a carbon source. In addition to serving as nitrogen sources, the munitions compounds also served as electron acceptors in the absence of sulfate. A soil slurry experiment with 5% and 10% munitions compounds-contaminated soil showed that the contaminant TNT was metabolized by the SRB culture in the presence of pyruvate as electron donor. This culture may be useful in decontaminating munitions compounds-contaminated soil and water under anaerobic conditions.

Boopathy, R.; Manning, J. [Argonne National Lab., IL (United States). Environmental Research Div.

1997-08-01

62

Denaturing gradient gel electrophoresis used to monitor the enrichment culture of aerobic chemoorganotrophic bacteria from a hot spring cyanobacterial mat.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Previous studies investigating microbial diversity in the Octopus Spring cyanobacterial mat community (Yellowstone National Park) have shown a discrepancy between bacterial populations observed by molecular retrieval and cultivation techniques. To investigate how selective enrichment culture techniq...

Santegoeds, C M; Nold, S C; Ward, D M

63

Pentachlorophenol biodegradation kinetics of an oligotrophic fluidized-bed enrichment culture  

Energy Technology Data Exchange (ETDEWEB)

A fluidized-bed reactor (FBR) was used to enrich an aerobic chlorophenol-degrading microbial culture. Long-term continuous-flow operation with low effluent concentrations selected oligotrophic microorganisms producing good-quality effluent for pentachlorophenol(PCP)-contaminated water. PCP biodegradation kinetics was studied using this FBR enrichment culture. The results from FBR batch experiments were modeled using a modified Haldane equation, which resulted in the following kinetic constants: q{sub max}=0.41 mg PCP mg protein{sup -1} day{sup -1}, K{sub S}=16 {mu}g l{sup -1}, K{sub i}=5.3 mg l{sup -1}, and n=3.5. These results show that the culture has a high affinity for PCP but is also inhibited by relatively low PCP concentrations (above 1.1 mg PCP l{sup -1}). This enrichment culture was maintained over 1 year of continuous-flow operation with PCP as the sole source of carbon and energy. During continuous-flow operation, effluent concentrations below 2 {mu}g l{sup -1} were achieved at 268 min hydraulic retention time (t{sub HR}) and 2.5 mg PCP l{sup -1} feed concentration. An increase in loading rate by decreasing t{sub HR} did not significantly deteriorate the effluent quality until a t{sub HR} decrease from 30 min to 21 min resulted in process failure. Recovery from process failure was slow. Decreasing the feed PCP concentration and increasing t{sub HR} resulted in an improved process recovery. (orig.)

Melin, E.S.; Puhakka, J.A. [Tampere Univ. of Technology (Finland). Dept. of Environmental Technology; Ferguson, J.F. [Washington Univ., Seattle, WA (United States). Dept. of Civil Engineering

1997-11-01

64

The effect of BTEX compounds on aerobic cometabolism of vinyl chloride by ethylene grown enrichment cultures  

Energy Technology Data Exchange (ETDEWEB)

There is mounting field evidence that groundwater contaminated with trichloroethylene (TCE) and tetrachloroethylene (PCE) can be efficiently treated in situ by stimulating anaerobic reductive dechlorination, producing primarily ethylene and/or ethane. However, persistence of vinyl chloride (VC), even at low levels, may result in the need for subsequent aerobic treatment. A recent study by Freedman and Herz (1995) indicated that ethylene and ethane can serve as the primary substrates for aerobic cometabolism of VC, thereby avoiding the need to add an exogenous primary substrate. At many sites where PCE and TCE are found, other organic contaminants are also prevalent in mixtures. Chief among these are BTEX compounds (benzene (BEN), toluene (TOL), ethylbenzene (EBZ) and o-xylene (XYL)). Except for TOL, a limited amount of BTEX biodegradation is typically expected under anaerobic conditions, so most of the BTEX that occurs with PCE and TCE is likely to reach the aerobic zone along with VC, ethylene, and ethane. The objective of this study was to determine the effect of BTEX compounds on aerobic biodegradation of ethylene and VC. In an ethylene-grown enrichment culture, addition of BEN, EBZ, and TOL (6-59 mg/L) inhibited the initial rate of ethylene and VC biodegradation by 75% and 67%, respectively. The lower concentration of XYL added (0.80 mg/L) had a minor effect. As the rate of BEN, EBZ, and TOL biodegradation improved with time, no further inhibition of VC and ethylene consumption was observed. A population of BTEX degrading organisms developed in the ethylene-grown culture, but this did not result in a faster rate of VC or ethylene use. Separately developed BEN- and TOL-grown enrichment cultures confirmed this. Neither aromatic enrichment culture was able to biodegrade VC or ethylene, but both were able to consume all of the other aromatic compounds.

Freedman, D.L.; Williamson, A.E.

1996-12-31

65

Properties of a butyrate-forming Clostridium present in cellulose-enriched methanogenic culture  

Energy Technology Data Exchange (ETDEWEB)

Tests were made to determine the cause of butyrate formation in a cellulose-enriched culture from sewage sludge containing celluloytic anaerobes that do not produce this acid. The results showed the presence of a saccharolytic butyrate-forming Clostridium. In pure culture, this Clostridium produced ethanol, acetate and butyrate from a variety of sugars, and was non-motile, without peritrichous flagella. In coculture with celluloytic anaerobes, this Clostridium helped in improving cellulolysis by removing sugars that are not used by these anaerobes but inhibit their growth. In mixed culture fermentations failing because of poor methanogenesis, the H/sub 2/ is not completely removed. The results showed that, unlike cellulolytic anaerobes, the growth of this Clostridium was not affected by the presence of H/sub 2/. It appears its growth in the presence of H/sub 2/ causes the accumulation of butyrate.

Khan, A.W.; Meek, E.; Miller, S.S.

1986-01-01

66

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

67

Batch culture enrichment of ANAMMOX populations from anaerobic and aerobic seed cultures.  

Science.gov (United States)

Discharge of nitrate and ammonia rich wastewaters into the natural waters encourage eutrophication, and contribute to aquatic toxicity. Anaerobic ammonium oxidation process (ANAMMOX) is a novel biological nitrogen removal alternative to nitrification-denitrification, that removes ammonia using nitrite as the electron acceptor. The feasibility of enriching the ANAMMOX bacteria from the anaerobic digester sludge of a biomethanation plant treating vegetable waste and aerobic sludge from an activated sludge process treating domestic sewage is reported in this paper. ANAMMOX bacterial activity was monitored and established in terms of nitrogen transformations to ammonia, nitrite and nitrate along with formation of hydrazine and hydroxylamine. PMID:20729077

Suneethi, S; Joseph, Kurian

2010-08-04

68

Batch culture enrichment of ANAMMOX populations from anaerobic and aerobic seed cultures.  

UK PubMed Central (United Kingdom)

Discharge of nitrate and ammonia rich wastewaters into the natural waters encourage eutrophication, and contribute to aquatic toxicity. Anaerobic ammonium oxidation process (ANAMMOX) is a novel biological nitrogen removal alternative to nitrification-denitrification, that removes ammonia using nitrite as the electron acceptor. The feasibility of enriching the ANAMMOX bacteria from the anaerobic digester sludge of a biomethanation plant treating vegetable waste and aerobic sludge from an activated sludge process treating domestic sewage is reported in this paper. ANAMMOX bacterial activity was monitored and established in terms of nitrogen transformations to ammonia, nitrite and nitrate along with formation of hydrazine and hydroxylamine.

Suneethi S; Joseph K

2011-01-01

69

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

2013-07-03

70

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

UK PubMed Central (United Kingdom)

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.

Matsui H; Kimura J; Higashide M; Takeuchi Y; Okue K; Cui L; Nakae T; Sunakawa K; Hanaki H

2013-09-01

71

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

UK PubMed Central (United Kingdom)

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

Luo G; Angelidaki I

2012-11-01

72

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

DEFF Research Database (Denmark)

Biogas produced by anaerobic digestion, is mainly used in a gas motor for heat and electricity production. However, after removal of CO2, biogas can be upgraded to natural gas quality, giving more utilization possibilities, such as utilization as autogas, or distant utilization by using the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched hydrogenotrophic methanogens and fed with biogas and hydrogen. Both mesophilic- and thermophilic anaerobic cultures were enriched to convert CO2 to CH4 by addition of H2. Enrichment at thermophilic temperature (55°C) resulted in CO2 and H2 bioconversion rate of 320?mL CH4/(gVSS?h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic- and thermophilic-enriched cultures, as revealed by PCR–DGGE. Nonetheless, they all belonged to the order Methanobacteriales, which can mediate hydrogenotrophic methanogenesis. Biogas upgrading was then tested in a thermophilic anaerobic reactor under various operation conditions. By continuous addition of hydrogen in the biogas reactor, high degree of biogas upgrading was achieved. The produced biogas had a CH4 content, around 95% at steady-state, at gas (mixture of biogas and hydrogen) injection rate of 6?L/(L?day). The increase of gas injection rate to 12?L/(L?day) resulted in the decrease of CH4 content to around 90%. Further study showed that by decreasing the gas–liquid mass transfer by increasing the stirring speed of the mixture the CH4 content was increased to around 95%. Finally, the CH4 content around 90% was achieved in this study with the gas injection rate as high as 24?L/(L?day). Biotechnol. Bioeng. 2012; 109: 2729–2736. © 2012 Wiley Periodicals, Inc.

Luo, Gang; Angelidaki, Irini

2012-01-01

73

Molecular-based Detection of Culture-confirmed Bacterial Bloodstream Infections Using Limited Enrichment Time.  

UK PubMed Central (United Kingdom)

Conventional blood culturing using automated instrumentation with phenotypic identification requires a significant amount of time to generate results. This study investigated the speed and accuracy of results generated using PCR and pyrosequencing compared to that required to obtain Gram stain results and final culture identification for cases of culture-confirmed bloodstream infections. Research and physician-ordered blood cultures were drawn concurrently. Aliquots of the incubating research blood culture fluid were removed hourly between 5-8 hours, at 24 hours, and again at 5 days. DNA was extracted from these 6 time point aliquots and analyzed by PCR and pyrosequencing for bacterial rRNA gene target(s). These results were then compared to those of the physician-ordered blood culture. PCR and pyrosequencing accurately identified 92% of all culture-confirmed cases after a mean enrichment time of 5.8 ± 2.9 hrs. When including the time needed to complete sample processing, PCR and pyrosequencing protocols, the molecular approach yielded results in 11.8 ± 2.9 hours compared to means of 27.9 ± 13.6 hours to obtain the Gram stain results and of 81.6 ± 24.0 hours to generate the final culture-based identification. The molecular approach enabled accurate detection of most bacteria present in incubating blood culture bottles on average about 16 hours sooner than Gram stain results became available and approximately 3 days sooner than the phenotypic identification was entered in the Laboratory Information System. If implemented, this more rapid molecular-based approach could minimize the number of doses of unnecessary or ineffective antibiotics administered to patients.

Moore MS; McCann CD; Jordan JA

2013-08-01

74

Biological enrichment of Mycoplasma agents by cocultivation with permissive cell cultures.  

Science.gov (United States)

In this study, we describe our results on the evaluation of the ability of different permissive mammalian cell lines to support the biological enrichment of mycoplasma species known to be bacterial contaminants of cell substrates. The study showed that this approach is able to significantly improve the efficiency of mycoplasma detection based on nucleic acid testing or biochemical technologies (e.g., MycoAlert mycoplasma detection). Of 10 different cell lines (Vero, MDBK, HEK-293, Hep-G2, CV-1, EBTr, WI-38, R9ab, MDCK, and High Five) used in the study, only MDCK cell culture was found to support the efficient growth of all the tested mycoplasmas (Mycoplasma arginini, M. bovis, M. fermentans, M. gallinaceum, M. gallisepticum, M. synoviae, M. hominis, M. hyorhinis, M. orale, M. salivarium, and Acholeplasma laidlawii) known to be most frequently associated with contamination of cell substrates and cell lines in research laboratories or manufacturing facilities. The infection of MDCK cells with serial dilutions of each mycoplasma species demonstrated that these common cell line contaminants can be detected reliably after 7-day enrichment in MDCK cell culture at contamination levels of 0.05 to 0.25 CFU/ml. The High Five insect cell line was also found to be able to support the efficient growth of most mycoplasma species tested, except for M. hyorhinis strain DBS1050. However, mycoplasma growth in insect cell culture was demonstrated to be temperature dependent, and the most efficient growth was observed when the incubation temperature was increased from 28 degrees C to between 35 and 37 degrees C. We believe that this type of mycoplasma enrichment is one of the most promising approaches for improving the purity and safety testing of cell substrates and other cell-derived biologics and pharmaceuticals. PMID:18606798

Volokhov, Dmitriy V; Kong, Hyesuk; George, Joseph; Anderson, Christine; Chizhikov, Vladimir E

2008-07-07

75

Biological Enrichment of Mycoplasma Agents by Cocultivation with Permissive Cell Cultures?  

Science.gov (United States)

In this study, we describe our results on the evaluation of the ability of different permissive mammalian cell lines to support the biological enrichment of mycoplasma species known to be bacterial contaminants of cell substrates. The study showed that this approach is able to significantly improve the efficiency of mycoplasma detection based on nucleic acid testing or biochemical technologies (e.g., MycoAlert mycoplasma detection). Of 10 different cell lines (Vero, MDBK, HEK-293, Hep-G2, CV-1, EBTr, WI-38, R9ab, MDCK, and High Five) used in the study, only MDCK cell culture was found to support the efficient growth of all the tested mycoplasmas (Mycoplasma arginini, M. bovis, M. fermentans, M. gallinaceum, M. gallisepticum, M. synoviae, M. hominis, M. hyorhinis, M. orale, M. salivarium, and Acholeplasma laidlawii) known to be most frequently associated with contamination of cell substrates and cell lines in research laboratories or manufacturing facilities. The infection of MDCK cells with serial dilutions of each mycoplasma species demonstrated that these common cell line contaminants can be detected reliably after 7-day enrichment in MDCK cell culture at contamination levels of 0.05 to 0.25 CFU/ml. The High Five insect cell line was also found to be able to support the efficient growth of most mycoplasma species tested, except for M. hyorhinis strain DBS1050. However, mycoplasma growth in insect cell culture was demonstrated to be temperature dependent, and the most efficient growth was observed when the incubation temperature was increased from 28°C to between 35 and 37°C. We believe that this type of mycoplasma enrichment is one of the most promising approaches for improving the purity and safety testing of cell substrates and other cell-derived biologics and pharmaceuticals.

Volokhov, Dmitriy V.; Kong, Hyesuk; George, Joseph; Anderson, Christine; Chizhikov, Vladimir E.

2008-01-01

76

Biological enrichment of Mycoplasma agents by cocultivation with permissive cell cultures.  

UK PubMed Central (United Kingdom)

In this study, we describe our results on the evaluation of the ability of different permissive mammalian cell lines to support the biological enrichment of mycoplasma species known to be bacterial contaminants of cell substrates. The study showed that this approach is able to significantly improve the efficiency of mycoplasma detection based on nucleic acid testing or biochemical technologies (e.g., MycoAlert mycoplasma detection). Of 10 different cell lines (Vero, MDBK, HEK-293, Hep-G2, CV-1, EBTr, WI-38, R9ab, MDCK, and High Five) used in the study, only MDCK cell culture was found to support the efficient growth of all the tested mycoplasmas (Mycoplasma arginini, M. bovis, M. fermentans, M. gallinaceum, M. gallisepticum, M. synoviae, M. hominis, M. hyorhinis, M. orale, M. salivarium, and Acholeplasma laidlawii) known to be most frequently associated with contamination of cell substrates and cell lines in research laboratories or manufacturing facilities. The infection of MDCK cells with serial dilutions of each mycoplasma species demonstrated that these common cell line contaminants can be detected reliably after 7-day enrichment in MDCK cell culture at contamination levels of 0.05 to 0.25 CFU/ml. The High Five insect cell line was also found to be able to support the efficient growth of most mycoplasma species tested, except for M. hyorhinis strain DBS1050. However, mycoplasma growth in insect cell culture was demonstrated to be temperature dependent, and the most efficient growth was observed when the incubation temperature was increased from 28 degrees C to between 35 and 37 degrees C. We believe that this type of mycoplasma enrichment is one of the most promising approaches for improving the purity and safety testing of cell substrates and other cell-derived biologics and pharmaceuticals.

Volokhov DV; Kong H; George J; Anderson C; Chizhikov VE

2008-09-01

77

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

Science.gov (United States)

Anaerobic ammonium oxidation (anammox) is an emerging technology for nitrogen removal that provides a more environmentally sustainable and cost effective alternative compared to conventional biological treatment methods. The objective of this study was to investigate the inhibitory impact of anammox substrates, metabolites and common wastewater constituents on the microbial activity of two different anammox enrichment cultures (suspended and granular), both dominated by bacteria from the genus Brocadia. Inhibition was evaluated in batch assays by comparing the N(2) production rates in the absence or presence of each compound supplied in a range of concentrations. The optimal pH was 7.5 and 7.3 for the suspended and granular enrichment cultures, respectively. Among the substrates or products, ammonium and nitrate caused low to moderate inhibition, whereas nitrite caused almost complete inhibition at concentrations higher than 15 mM. The intermediate, hydrazine, either stimulated or caused low inhibition of anammox activity up to 3mM. Of the common constituents in wastewater, hydrogen sulfide was the most severe inhibitor, with 50% inhibitory concentrations (IC(50)) as low as 0.03 mM undissociated H(2)S. Dissolved O(2) showed moderate inhibition (IC(50)=2.3-3.8 mg L(-1)). In contrast, phosphate and salinity (NaCl) posed very low inhibition. The suspended- and granular anammox enrichment cultures had similar patterns of response to the various inhibitory stresses with the exception of phosphate. The findings of this study provide comprehensive insights on the tolerance of the anammox process to a wide variety of potential inhibiting compounds. PMID:23245574

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

2012-12-12

78

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

UK PubMed Central (United Kingdom)

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

Carvajal-Arroyo JM; Sun W; Sierra-Alvarez R; Field JA

2013-03-01

79

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

Directory of Open Access Journals (Sweden)

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

Pilehchian Langroudi, R.; Jabbari, A.R.; Moosawi Shoshtari, M.

2012-01-01

80

Effect of dissolved oxygen concentration (microaerobic and aerobic) on selective enrichment culture for bioaugmentation of acidic industrial wastewater.  

Science.gov (United States)

The successful application of bioaugmentation is largely dependent on the selective enrichment of culture with regards to pH, temperature, salt, or specific toxic organic pollutants. In this study, we investigated the effect of dissolved oxygen (DO) concentrations (aerobic, >2 mg L(-1); microaerobic, bioaugmentation of acidic industrial wastewater (pH 3.9-4.7). Clone library analyses revealed that the yeast community shifted in response to different DO levels, and that Candida humilis and Candida pseudolambica were individually dominant in the aerobic and microaerobic enrichment cultures. This would significantly influence the isolation results, and further hinder bioaugmentation due to differences in DO environments during the enrichment and application periods. However, differences in the selective enrichment culture cannot be predicted based on differences in pollutant removal performance. Thus, DO concentrations (aerobic/microaerobic) should be considered a secondary selective pressure to achieve successful bioaugmentation. PMID:22776258

Quan, Ying; Han, Hui; Zheng, Shaokui

2012-06-16

 
 
 
 
81

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

UK PubMed Central (United Kingdom)

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.

Avberšek J; Zajc U; Mi?unovi? J; Ocepek M

2013-05-01

82

Benthic organic enrichment from suspended mussel (Mytilus edulis) culture in Prince Edward Island, Canada  

UK PubMed Central (United Kingdom)

The effects of increased biodeposition within mussel (Mytilus edulis) farms on the benthic environment were investigated using surface sediment samples collected from 11 coastal embayments in Prince Edward Island (PEI), Canada. The degree of organic enrichment, determined using geochemical indicators (total free sulfides (S), redox potentials (EhNHE), water content (WC) and organic matter (OM)), was significantly greater in mussel leases compared to reference sites located both outside lease boundaries and in inlets not used to culture mussel (MANOVA, p <0.001). Post-hoc tests showed that mean WC and OM, EhNHE potentials and S concentration were all significantly different between lease and reference sites (p <=0.009). Temporal changes in organic enrichment conditions were detected by comparing our 2001 data to those previously reported from a 1997 survey of the same sampling sites (MANOVA, p <0.001). This multivariate effect resulted primarily from a 39% increase in mean S concentration between 1997 and 2001 (p =0.029). Surface sediment variables at reference sites were similar between years. Benthic conditions were discriminated along an oxic-anoxic enrichment gradient using multidimensional scaling analysis. Mussel lease sites sampled in 1997 were clustered within predefined oxic sediment classifications along with the majority of reference sites, but were grouped farther along the enrichment gradient in 2001. The significant increase in hypoxic and sulfidic sediments within mussel farms between 1997 and 2001 is consistent with the 43% increase in PEI mussel production--a classic response to excessive organic biodeposition in shallow coastal inlets with relatively low dispersive capacity.

Cranford PJ; Hargrave BT; Doucette LI

2009-07-01

83

Impact of arachidonic acid enrichment of live rotifer prey on bacterial communities in rotifer and larval fish cultures.  

UK PubMed Central (United Kingdom)

Rotifers (Brachionus plicatilis), commonly used at first feeding in commercial fish hatcheries, carry a large bacteria load. Because they are relatively poor in essential fatty acids, it is common practice to enrich them with fatty acids, including arachidonic acid (AA). This study aims to determine whether prey enrichment with AA may act as a prebiotic and modify the microbial community composition either in AA-enriched rotifer cultures or in larval-rearing water using winter flounder (Pseudopleuronectes americanus) as a larval fish model. AA enrichment modified the bacterial community composition in both the rotifer culture tanks and the larval-rearing tanks. We observed an increase in the number of cultivable bacteria on TCBS (thiosulfate-citrate-bile salts-sucrose) agar, used as a proxy for the abundance of Vibrio sp. The results suggest that AA may also play an indirect role in larval health.

Seychelles LH; Doiron K; Audet C; Tremblay R; Pernet F; Lemarchand K

2013-03-01

84

CO/sub 2/ enrichment in vitro. Effect on autotrophic and heterotrophic cultures of Nicotiana tabacum (var. Samsun)  

Energy Technology Data Exchange (ETDEWEB)

Plantlets of Nicotiana tabacum (var. Samsun) were grown under CO/sub 2/ enriched air supplied by a Warburg buffer. Growth of all plant parts was enhanced. The maximum growth increase was found for roots (120%). Addition of 30 g.1/sup -1/ sucrose in the medium resulted in a three time faster growth. However, the effect of CO/sub 2/ enrichment was still positive in these conditions, although less pronounced than in autotrophic cultures.

Mousseau, M.

1986-01-01

85

Combined genomic and proteomic approaches identify gene clusters involved in anaerobic 2-methylnaphthalene degradation in the sulfate-reducing enrichment culture N47.  

Science.gov (United States)

The highly enriched deltaproteobacterial culture N47 anaerobically oxidizes the polycyclic aromatic hydrocarbons naphthalene and 2-methylnaphthalene, with sulfate as the electron acceptor. Combined genome sequencing and liquid chromatography-tandem mass spectrometry-based shotgun proteome analyses were performed to identify genes and proteins involved in anaerobic aromatic catabolism. Proteome analysis of 2-methylnaphthalene-grown N47 cells resulted in the identification of putative enzymes catalyzing the anaerobic conversion of 2-methylnaphthalene to 2-naphthoyl coenzyme A (2-naphthoyl-CoA), as well as the reductive ring cleavage of 2-naphthoyl-CoA, leading to the formation of acetyl-CoA and CO(2). The glycyl radical-catalyzed fumarate addition to the methyl group of 2-methylnaphthalene is catalyzed by naphthyl-2-methyl-succinate synthase (Nms), composed of alpha-, beta-, and gamma-subunits that are encoded by the genes nmsABC. Located upstream of nmsABC is nmsD, encoding the Nms-activating enzyme, which harbors the characteristic [Fe(4)S(4)] cluster sequence motifs of S-adenosylmethionine radical enzymes. The bns gene cluster, coding for enzymes involved in beta-oxidation reactions converting naphthyl-2-methyl-succinate to 2-naphthoyl-CoA, was found four intervening open reading frames further downstream. This cluster consists of eight genes (bnsABCDEFGH) corresponding to 8.1 kb, which are closely related to genes for enzymes involved in anaerobic toluene degradation within the denitrifiers "Aromatoleum aromaticum" EbN1, Azoarcus sp. strain T, and Thauera aromatica. Another contiguous DNA sequence harbors the gene for 2-naphthoyl-CoA reductase (ncr) and 16 additional genes that were found to be expressed in 2-methylnaphthalene-grown cells. These genes code for enzymes that were supposed to catalyze the dearomatization and ring cleavage reactions converting 2-naphthoyl-CoA to acetyl-CoA and CO(2). Comparative sequence analysis of the four encoding subunits (ncrABCD) showed the gene product to have the closest similarity to the Azoarcus type of benzoyl-CoA reductase. The present work provides the first insight into the genetic basis of anaerobic 2-methylnaphthalene metabolism and delivers implications for understanding contaminant degradation. PMID:19854898

Selesi, Drazenka; Jehmlich, Nico; von Bergen, Martin; Schmidt, Frank; Rattei, Thomas; Tischler, Patrick; Lueders, Tillmann; Meckenstock, Rainer U

2010-01-01

86

Combined genomic and proteomic approaches identify gene clusters involved in anaerobic 2-methylnaphthalene degradation in the sulfate-reducing enrichment culture N47.  

UK PubMed Central (United Kingdom)

The highly enriched deltaproteobacterial culture N47 anaerobically oxidizes the polycyclic aromatic hydrocarbons naphthalene and 2-methylnaphthalene, with sulfate as the electron acceptor. Combined genome sequencing and liquid chromatography-tandem mass spectrometry-based shotgun proteome analyses were performed to identify genes and proteins involved in anaerobic aromatic catabolism. Proteome analysis of 2-methylnaphthalene-grown N47 cells resulted in the identification of putative enzymes catalyzing the anaerobic conversion of 2-methylnaphthalene to 2-naphthoyl coenzyme A (2-naphthoyl-CoA), as well as the reductive ring cleavage of 2-naphthoyl-CoA, leading to the formation of acetyl-CoA and CO(2). The glycyl radical-catalyzed fumarate addition to the methyl group of 2-methylnaphthalene is catalyzed by naphthyl-2-methyl-succinate synthase (Nms), composed of alpha-, beta-, and gamma-subunits that are encoded by the genes nmsABC. Located upstream of nmsABC is nmsD, encoding the Nms-activating enzyme, which harbors the characteristic [Fe(4)S(4)] cluster sequence motifs of S-adenosylmethionine radical enzymes. The bns gene cluster, coding for enzymes involved in beta-oxidation reactions converting naphthyl-2-methyl-succinate to 2-naphthoyl-CoA, was found four intervening open reading frames further downstream. This cluster consists of eight genes (bnsABCDEFGH) corresponding to 8.1 kb, which are closely related to genes for enzymes involved in anaerobic toluene degradation within the denitrifiers "Aromatoleum aromaticum" EbN1, Azoarcus sp. strain T, and Thauera aromatica. Another contiguous DNA sequence harbors the gene for 2-naphthoyl-CoA reductase (ncr) and 16 additional genes that were found to be expressed in 2-methylnaphthalene-grown cells. These genes code for enzymes that were supposed to catalyze the dearomatization and ring cleavage reactions converting 2-naphthoyl-CoA to acetyl-CoA and CO(2). Comparative sequence analysis of the four encoding subunits (ncrABCD) showed the gene product to have the closest similarity to the Azoarcus type of benzoyl-CoA reductase. The present work provides the first insight into the genetic basis of anaerobic 2-methylnaphthalene metabolism and delivers implications for understanding contaminant degradation.

Selesi D; Jehmlich N; von Bergen M; Schmidt F; Rattei T; Tischler P; Lueders T; Meckenstock RU

2010-01-01

87

Myasthenia gravis: selective enrichment of antiacetylcholine receptor antibody production in untransformed human B cell cultures.  

Science.gov (United States)

B cells producing antibodies against the acetylcholine receptor (AchR) play a central role in the pathogenesis of myasthenia gravis (MG). Although anti-AchR autoantibodies have been studied extensively, not much is known about autoimmune B cells and their antigen-driven activation. This has mainly been due to difficulties in establishing and maintaining untransformed antigen-specific B cells in vitro. In this study, we show that highly enriched B cells from peripheral blood and thymus of MG patients can be maintained in culture over a period of 4 weeks when grown on the AchR-expressing rhabdomyosarcoma cell line TE671 together with an anti-CD40 stimulus and lymphokines. Anti-AchR antibody secretion could be detected in the majority of B cell cultures on TE671 cells up to 4 weeks. In contrast, B cells cultured on CDw32-transfected L cells binding anti-CD40 antibodies (the CD40 system) produced only small amounts of anti-AchR antibodies at single time points, whereas the overall IgG production was higher than on TE671 cells. The expression of the relevant autoantigen on the adherent cell line in addition to other growth stimuli could account for this difference and may provide a useful tool for investigating antigen-dependent B cell activation in MG and other B cell-mediated autoimmune conditions. PMID:10556808

Padberg, F; Matsuda, M; Fenk, R; Patenge, N; Kubuschok, B; Hohlfeld, R; Wekerle, H; Spuler, S

1999-11-01

88

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

2013-07-27

89

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

UK PubMed Central (United Kingdom)

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.

Cheng L; Cord-Ruwisch R

2013-10-01

90

Study of selenocompounds from selenium-enriched culture of edible sprouts.  

Science.gov (United States)

Selenium is recognised as an essential micronutrient for humans and animals. One of the main sources of selenocompounds in the human diet is vegetables. Therefore, this study deals with the Se species present in different edible sprouts grown in Se-enriched media. We grew alfalfa, lentil and soy in a hydroponic system amended with soluble salts, containing the same proportion of Se, in the form of Se(VI) and Se(IV). Total Se in the sprouts was determined by acidic digestion in a microwave system and by ICP/MS. Se speciation was carried out by enzymatic extraction (Protease XIV) and measured by LC-ICP/MS. The study shows that the Se content of plants depends on the content in the growth culture, and that part of the inorganic Se was biotransformed mainly into SeMet. These results contribute to our understanding of the uptake of inorganic Se and its biotransformation by edible plants. PMID:23993543

Funes-Collado, Virginia; Morell-Garcia, Albert; Rubio, Roser; López-Sánchez, José Fermín

2013-06-28

91

Study of selenocompounds from selenium-enriched culture of edible sprouts.  

UK PubMed Central (United Kingdom)

Selenium is recognised as an essential micronutrient for humans and animals. One of the main sources of selenocompounds in the human diet is vegetables. Therefore, this study deals with the Se species present in different edible sprouts grown in Se-enriched media. We grew alfalfa, lentil and soy in a hydroponic system amended with soluble salts, containing the same proportion of Se, in the form of Se(VI) and Se(IV). Total Se in the sprouts was determined by acidic digestion in a microwave system and by ICP/MS. Se speciation was carried out by enzymatic extraction (Protease XIV) and measured by LC-ICP/MS. The study shows that the Se content of plants depends on the content in the growth culture, and that part of the inorganic Se was biotransformed mainly into SeMet. These results contribute to our understanding of the uptake of inorganic Se and its biotransformation by edible plants.

Funes-Collado V; Morell-Garcia A; Rubio R; López-Sánchez JF

2013-12-01

92

Inhibitory effect of 5- and 6-ring PAHs on pyrene mineralization by a mixed enrichment culture  

Energy Technology Data Exchange (ETDEWEB)

This research investigates the mineralization of pyrene in mixtures of PAHs to identify potential synergistic or antagonistic interactions that affect the degradation of individual compounds. Mineralization of {sup 14}C pyrene (25 RM) by a mixed enrichment culture was studied in systems containing mixtures of 5- and 6-ring PAHs in minimal salts medium (MSM). In the absence of the High Molecular Weight (HMW)-PAHs, the culture mineralized 62% of the added pyrene. Addition of an equal mixture of benzo(a)pyrene, dibenzanthracene, and benzo(g,h,i)peryiene (25 {micro}M total concentration) reduced pyrene mineralization to 25% after a 9-day lag phase. An increase on the molar concentration of the HMW-PAH mixture to 75 and 125 {micro}M decreased pyrene mineralization to 9.2 and 1%, respectively. Results from treatments containing individual (25 {micro}M each), or pairs of the HMW-compounds demonstrated that none of the three individual compounds caused a significant reduction in the extent of pyrene mineralization. However, the combination of benzo(a)pyrene and benzanthracene significantly inhibited pyrene activity. In addition, the presence of both benzo(a)pyrene and benzo(g,h,i)peryiene reduced mineralization by almost 23%. Determination of bacterial density by epifluorescence microscopy showed that mineralization of pyrene coincides with growth of the bacterial culture; presence of the 5- and 6-ring PAHs delayed growth with a concurrent inhibition of mineralization. When growth resumes, the inhibitory effect is reduced. A decrease of pyrene inhibition was also noted when MSM was replaced with sediment extract, or when sediment (1 {micro}g/ml) was added to the medium. These results suggest a synergistic inhibitory effect by combinations of specific HMW-PAHs rather than inhibition by individual compounds of the mixture on both the growth of the bacterial culture and the extent of pyrene mineralization.

Molina, M.; Agraujo, R. [Environmental Protection Agency, Athens, GA (United States)

1995-12-31

93

RDX biodegradation by a methanogenic enrichment culture obtained from an explosives manufacturing wastewater treatment plant  

Energy Technology Data Exchange (ETDEWEB)

This study examined the biodegradation of RDX in wastewater from an industrial wastewater treatment plant at the Holston Army Ammunition Plant in Kingsport, TN. Serum bottles containing 100 ml of a basal salts medium amended with 10 percent (v/v) sludge from the anoxic filter at the plant were amended with RDX and incubated under methanogenic conditions. Biodegradation intermediates corresponding to the mono-, di-, and trinitroso- RDX were observed. A methanogenic enrichment culture, derived from the wastewater, biodegraded 25% micrometer RDX in less than 16 days when ethanol was supplied as an electron donor. Methane production in the ethanol amended bottles was only observed after RDX had been depleted, while RDX unamended controls experienced no lag in methane production. The addition of 5 mM BESA to the culture inhibited methane production, but not RDX and ethanol degradation. These findings demonstrate the importance of adding reduced cosubstrates to enhance RDX biodegradation, and support the hypothesis that RDX is serving as a terminal electron acceptor in methanogenic environments.

Adrian, N.R.; Sutherland, K.

1998-12-01

94

Denitrifying bacteria in bulk and maize-rhizospheric soil: diversity and N2O-reducing abilities.  

Science.gov (United States)

The aim of this study was to determine the effect of the rhizosphere of maize on the diversity of denitrifying bacteria. Community structure comparison was performed by constructing a collection of isolates recovered from bulk and maize planted soil. A total of 3240 nitrate-reducing isolates were obtained and 188 of these isolates were identified as denitrifiers based on their ability to reduce nitrate to N2O or N2. 16S rDNA fragments amplified from the denitrifying isolates were analysed by restriction fragment length polymorphism. Isolates were grouped according to their restriction patterns, and 16S rDNA of representatives from each group were sequenced. A plant dependent enrichment of Agrobacterium-related denitrifiers has been observed resulting in a modification of the structure of the denitrifying community between planted and bulk soil. In addition, the predominant isolates in the rhizosphere soil were not able to reduce N2O while dominant isolates in the bulk soil evolve N2 as a denitrification product. PMID:15381970

Chèneby, D; Perrez, S; Devroe, C; Hallet, S; Couton, Y; Bizouard, F; Iuretig, G; Germon, J C; Philippot, L

2004-07-01

95

Denitrifying bacteria in bulk and maize-rhizospheric soil: diversity and N2O-reducing abilities.  

UK PubMed Central (United Kingdom)

The aim of this study was to determine the effect of the rhizosphere of maize on the diversity of denitrifying bacteria. Community structure comparison was performed by constructing a collection of isolates recovered from bulk and maize planted soil. A total of 3240 nitrate-reducing isolates were obtained and 188 of these isolates were identified as denitrifiers based on their ability to reduce nitrate to N2O or N2. 16S rDNA fragments amplified from the denitrifying isolates were analysed by restriction fragment length polymorphism. Isolates were grouped according to their restriction patterns, and 16S rDNA of representatives from each group were sequenced. A plant dependent enrichment of Agrobacterium-related denitrifiers has been observed resulting in a modification of the structure of the denitrifying community between planted and bulk soil. In addition, the predominant isolates in the rhizosphere soil were not able to reduce N2O while dominant isolates in the bulk soil evolve N2 as a denitrification product.

Chèneby D; Perrez S; Devroe C; Hallet S; Couton Y; Bizouard F; Iuretig G; Germon JC; Philippot L

2004-07-01

96

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; Gut Ian M; Lyman Megan E; Tuznik Kaylie M; Mesngon Mariano T; McNutt Patrick M

2012-01-01

97

N-acyl homoserine lactone-degrading microbial enrichment cultures isolated from Penaeus vannamei shrimp gut and their probiotic properties in Brachionus plicatilis cultures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Three bacterial enrichment cultures (ECs) were isolated from the digestive tract of Pacific white shrimp Penaeus vannamei, by growing the shrimp microbial communities in a mixture of N-acyl homoserine lactone (AHL) molecules. The ECs, characterized by denaturing gradient gel electrophoresis a...

Tinh, N.T.N.; Asanka Gunasekara, R.A.Y.S.; Boon, N.; Dierckens, K.; Sorgeloos, P.; Bossier, P.

98

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

Energy Technology Data Exchange (ETDEWEB)

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 [mu]M, a stable situation was established in the nutristat, with an average dilution rate of 0.035 [+-] 0.003 h[sup [minus]1]. Compared with those of fed-batch cultures and chemostat cultures, the growth rates of microorganisms in the PCP nutristat were significantly higher, leading to considerable time savings in the enrichment procedure. In addition, PCP accumulation to severe inhibitory levels in the culture is prevented because the set point determines the (maximum) PCP concentration in the culture. The use of the nutristat as a tool for the growth of bacteria that degrade toxic compounds is discussed.

Rutgers, M.; Bogte, J.J.; Breure, A.M.; Van Andel, J.G. (National Institute of Public Health and Environmental Protection, Bilthoven (Netherlands))

1993-10-01

99

Biodegradation of tributyl phosphate by novel bacteria isolated from enrichment cultures.  

UK PubMed Central (United Kingdom)

Tributyl phosphate (TBP) is an organophosphorous compound, used extensively (3000-5000 tonnes/annum) as a solvent for nuclear fuel processing and as a base stock in the formulation of fire-resistant aircraft hydraulic fluids and other applications. Because of its wide applications and relative stability in the natural environment TBP poses the problem of pollution and health hazards. In the present study, fifteen potent bacterial strains capable of using tributyl phosphate (TBP) as sole carbon and phosphorus source were isolated from enrichment cultures. These isolates were identified on the basis of biochemical and morphological characteristics and 16S rRNA gene sequence analysis. Phylogenetic analysis of 16S rRNA gene sequences revealed that two isolates belonged to class Bacilli and thirteen to ? and ?-Proteobacteria. All these isolates were found to be members of genera Alcaligenes, Providencia, Delftia, Ralstonia, and Bacillus. These isolates were able to tolerate and degrade up to 5 mM TBP, the highest concentration reported to date. The GC-MS method was developed to monitor TBP degradation. Two strains, Providencia sp. BGW4 and Delftia sp. BGW1 showed respectively, 61.0 ± 2.8% and 57.0 ± 2.0% TBP degradation within 4 days. The degradation rate constants, calculated by first order kinetic model were between 0.0024 and 0.0099 h(-1). These bacterial strains are novel for TBP degradation and could be used as an important bioresource for efficient decontamination of TBP polluted waste streams.

Ahire KC; Kapadnis BP; Kulkarni GJ; Shouche YS; Deopurkar RL

2012-02-01

100

Biodegradation of tributyl phosphate by novel bacteria isolated from enrichment cultures.  

Science.gov (United States)

Tributyl phosphate (TBP) is an organophosphorous compound, used extensively (3000-5000 tonnes/annum) as a solvent for nuclear fuel processing and as a base stock in the formulation of fire-resistant aircraft hydraulic fluids and other applications. Because of its wide applications and relative stability in the natural environment TBP poses the problem of pollution and health hazards. In the present study, fifteen potent bacterial strains capable of using tributyl phosphate (TBP) as sole carbon and phosphorus source were isolated from enrichment cultures. These isolates were identified on the basis of biochemical and morphological characteristics and 16S rRNA gene sequence analysis. Phylogenetic analysis of 16S rRNA gene sequences revealed that two isolates belonged to class Bacilli and thirteen to ? and ?-Proteobacteria. All these isolates were found to be members of genera Alcaligenes, Providencia, Delftia, Ralstonia, and Bacillus. These isolates were able to tolerate and degrade up to 5 mM TBP, the highest concentration reported to date. The GC-MS method was developed to monitor TBP degradation. Two strains, Providencia sp. BGW4 and Delftia sp. BGW1 showed respectively, 61.0 ± 2.8% and 57.0 ± 2.0% TBP degradation within 4 days. The degradation rate constants, calculated by first order kinetic model were between 0.0024 and 0.0099 h(-1). These bacterial strains are novel for TBP degradation and could be used as an important bioresource for efficient decontamination of TBP polluted waste streams. PMID:21755325

Ahire, Kedar C; Kapadnis, Balu P; Kulkarni, Girish J; Shouche, Yogesh S; Deopurkar, Rajendra L

2011-07-14

 
 
 
 
101

Growth kinetic studies on phenol degradation under denitrifying conditions  

Energy Technology Data Exchange (ETDEWEB)

The paper reports on the results of growth kinetic studies for anoxic phenol degradation by mixed cultures. In the present study, phenolytic anoxic enriched cultures were developed using sludge from the coke oven phenolic waste water treatment site from the steel industry at Durgapur. Batch kinetics of anoxic phenol degradation with the enriched culture showed that time required for complete degradation was dependent on the phenol concentration. 14 refs., 4 figs.

Sarfaraz, S.; Thomas, S.; Tewari, U.K.; Iyengar, L. [Indian Institute of Technology, Kanpur (India). Biotechnology Lab.

2001-07-01

102

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

103

Recovery of thermophilic campylobacters from pond water and sediment and the problem of interference by background bacteria in enrichment culture.  

UK PubMed Central (United Kingdom)

The aim of this study was to address problems in the determination of thermophilic campylobacters in turbid pond water and sediment. Thirty sets of three samples of pond water (volumes 10, 100, 1000 ml) or sediment (0.1, 1.0, 5.0 ml) were examined for the presence of thermophilic campylobacters. The different volumes of pond water were processed by membrane filtration followed by selective enrichment. The samples of sediment were subjected directly to selective enrichment. Presumptive isolates were confirmed by Gram stain, cell morphology, presence of oxidase and catalase, growth under microaerobic but not aerobic conditions, and PCR. Confirmed Campylobacter species were recovered only from 10 and 100 ml samples of water and from 0.1 and 1.0 ml samples of sediments. The 1000 ml samples of water and 5.0 ml samples of sediment never gave positive isolates. PCR indicated that the confirmed isolates were all either Campylobacter jejuni or C. coli. Enrichment cultures from 1000 ml filtrations contained the highest number of background bacteria. It is suggested that the processing of large volumes of turbid environmental water samples or of sediment is counterproductive and may not yield positive Campylobacter cultures. This is probably due to antagonistic effects of large numbers of background bacteria out-competing campylobacters during the enrichment stage. Pilot studies to establish appropriate volumes of pond water or sediment samples should be undertaken before routine determination of campylobacters is begun.

Abulreesh HH; Paget TA; Goulder R

2005-08-01

104

Effectiveness of heat treatment to protect introduced denitrifying bacteria from eukaryotic predatory microorganisms in a pilot-scale bioreactor.  

UK PubMed Central (United Kingdom)

Bioaugmentation of bioreactor systems with pre-cultured bacteria has proven difficult because inoculated bacteria are easily eliminated by predatory eukaryotic-microorganisms. Here, we demonstrated an intermediate thermal treatment was effective for protecting introduced denitrifying bacteria from eukaryotic predators and consequently allowed the inoculated bacteria to survive longer in a denitrification reactor.

Ikeda-Ohtsubo W; Miyahara M; Yamada T; Watanabe A; Fushinobu S; Wakagi T; Shoun H; Miyauchi K; Endo G

2013-06-01

105

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

106

A Novel Reductive Dehalogenase, Identified in a Contaminated Groundwater Enrichment Culture and in Desulfitobacterium dichloroeliminans Strain DCA1, Is Linked to Dehalogenation of 1,2-Dichloroethane?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A mixed culture dechlorinating 1,2-dichloroethane (1,2-DCA) to ethene was enriched from groundwater that had been subjected to long-term contamination. In the metagenome of the enrichment, a 7-kb reductive dehalogenase (RD) gene cluster sequence was detected by inverse and direct PCR. The RD gene cl...

Marzorati, Massimo; de Ferra, Francesca; Van Raemdonck, Hilde; Borin, Sara; Allifranchini, Elena; Carpani, Giovanna

107

Site-specific variability in BTEX biodegradation under denitrifying conditions  

Energy Technology Data Exchange (ETDEWEB)

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 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.

Kao, C.M. [Geophex, Ltd., Raleigh, NC (United States); Borden, R.C. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Civil Engineering

1997-03-01

108

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 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.

1997-01-01

109

Enrichment and dynamics of novel syntrophs in a methanogenic hexadecane-degrading culture from a Chinese oilfield.  

Science.gov (United States)

Methanogenic communities that degrade alkanes have been reported. However, little is known about the key players involved in the process. Methanogenic hexadecane-degrading consortia were enriched from an oilfield (Shengli, China). The microbial dynamics during the transfer incubations were monitored using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of 16S rRNA genes in combination with cloning and sequencing. The archaeal community shifted from a predominance of aceticlastic Methanosaeta during early cultivation to a substantial increase in hydrogenotrophic Methanoculleus in the highly enriched culture. Bacterial T-RFs 161 and 164 bp were consistently detected during the incubation and became dominant in the highly enriched culture. T-RF 161 bp primarily represented uncultured Waste Water of Evry 1 bacterium, which was possibly associated with Candidatus Cloacamonas acidaminovorans (99.7% sequence similarity). T-RF 164 bp could be assigned to both Thermotogaceae, with the closest relative being Candidatus Mesotoga sulfurreducens (similarity of 97%) and Syntrophaceae, with Smithella propionica as the closest relative (similarity of 96-97%). These bacterial lineages were potentially capable of syntrophic interactions with methanogen partners during hexadecane degradation. Partial assA genes (encoding the ?-subunit of alkylsuccinate synthase) were also detected, implying that the mechanism of fumarate addition may function in the hexadecane activation. PMID:23066709

Cheng, Lei; Rui, Junpeng; Li, Qiang; Zhang, Hui; Lu, Yahai

2012-11-07

110

Enrichment and dynamics of novel syntrophs in a methanogenic hexadecane-degrading culture from a Chinese oilfield.  

UK PubMed Central (United Kingdom)

Methanogenic communities that degrade alkanes have been reported. However, little is known about the key players involved in the process. Methanogenic hexadecane-degrading consortia were enriched from an oilfield (Shengli, China). The microbial dynamics during the transfer incubations were monitored using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of 16S rRNA genes in combination with cloning and sequencing. The archaeal community shifted from a predominance of aceticlastic Methanosaeta during early cultivation to a substantial increase in hydrogenotrophic Methanoculleus in the highly enriched culture. Bacterial T-RFs 161 and 164 bp were consistently detected during the incubation and became dominant in the highly enriched culture. T-RF 161 bp primarily represented uncultured Waste Water of Evry 1 bacterium, which was possibly associated with Candidatus Cloacamonas acidaminovorans (99.7% sequence similarity). T-RF 164 bp could be assigned to both Thermotogaceae, with the closest relative being Candidatus Mesotoga sulfurreducens (similarity of 97%) and Syntrophaceae, with Smithella propionica as the closest relative (similarity of 96-97%). These bacterial lineages were potentially capable of syntrophic interactions with methanogen partners during hexadecane degradation. Partial assA genes (encoding the ?-subunit of alkylsuccinate synthase) were also detected, implying that the mechanism of fumarate addition may function in the hexadecane activation.

Cheng L; Rui J; Li Q; Zhang H; Lu Y

2013-03-01

111

Metabolites detected during biodegradation of 13C6-benzene in nitrate-reducing and methanogenic enrichment cultures.  

UK PubMed Central (United Kingdom)

The mechanism for anaerobic metabolism of benzene remains unknown. To date, there have been only a few studies reporting metabolites of anaerobic benzene biodegradation, in part because anaerobic benzene-degrading enrichment cultures are not very common and only two isolates have been characterized to date. Phenol and benzoate, metabolites consistent with benzene hydroxylation or benzene carboxylation, have been identified previously in mixed cultures, and more recently benzene methylation to toluene has been proposed as another possible mechanism for anaerobic benzene degradation. In this study, 13C6-benzene was added to nitrate-reducing and methanogenic enrichment cultures and specific 13C-labeled metabolites were monitored over time. The putative metabolites were detected by gas chromatography/mass spectrometry in ether extracts of 100-mL samples of culture taken at each time point. This method of analysis provided the sensitivity required to accurately quantify low concentrations of these compounds. In addition, benzoate trapping was used in an attemptto increase concentrations of upstream metabolites. In both cultures, in the presence and absence of unlabeled benzoate (trap), [ring-13C]-toluene and [ring-13C]benzoate were detected transiently during degradation. The data strongly support initial methylation of benzene to toluene, followed bytransformation to benzoate. Although benzene methylation has been proposed previously, this is the first direct evidence to supportthis pathway. In the methanogenic culture only, 13C6-phenol was also detected. The transient appearance of phenol, which appeared to be further transformed to benzoate, suggests that a pathway involving hydroxylation to phenol, as proposed in other studies, was also operative.

Ulrich AC; Beller HR; Edwards EA

2005-09-01

112

Denitrifying Bacteria in the Earthworm Gastrointestinal Tract and In Vivo Emission of Nitrous Oxide (N(inf2)O) by Earthworms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Earthworms (Lumbricus rubellus and Octolasium lacteum) and gut homogenates did not produce CH(inf4), and methanogens were not readily culturable from gut material. In contrast, the numbers of culturable denitrifiers averaged 7 x 10(sup7) and 9 x 10(sup6) per g (dry weight) of gut material for L. rub...

Karsten, G. R.; Drake, H. L.

113

Denitrification by intact soybean nodules in relation to natural 15N enrichment of nodules  

International Nuclear Information System (INIS)

[en] The natural 15N abundance of nodules of soybeans (Glycine max (L.) Merrill) which are actively fixing N2 is considerably higher than other tissues. To investigate the question of whether isotopic fractionation associated with denitrification by bacteroids causes this 15N enrichment, we inoculated soybeans with two strains of Rhizobium japonicum. Free-living cultures of one of these (strain USDA 33) were unable to denitrify or respire NO3-, while free-living cultures of the second (strain USDA 138) were capable of denitrification. USDA 138 formed nodules which fixed N2 very efficiently. The N of these nodules was enriched in 15N and the nodules reduced a substantial amount of NO3- to NO2- and N2O. Nodules infected with USDA 33 fixed about half as much N2 as those infected with USDA 138. The former nodules were enriched in 15N (although less so than nodules infected with USDA 138), despite the fact that the nodules formed by USDA 33 did not reduce NO3-. Clearly denitrification could not have been the cause of 15N enrichment of nodules infected with strain USDA 33. Alternative causes of 15N enrichment of soybean nodules and their possible metabolic significance are discussed

1985-01-01

114

Biotransformation of halogenated nonylphenols with sphingobium xenophagum bayram and a nonylphenol-degrading soil-enrichment culture.  

UK PubMed Central (United Kingdom)

When discharged in chlorinated wastewater, alkylphenol ethoxylate metabolites (APEMs) are often discharged in halogenated form (XAPEMs, X = Cl, or Br). The potential environmental impact of XAPEM release was assessed by studying the biotransformation of halogenated nonylphenol by Sphingobium xenophagum Bayram and a soil-enrichment culture. S. xenophagum Bayram transformed chlorinated nonylphenol (ClNP) slowly and nearly completely to form nonyl alcohol; the monobrominated nonylphenol (BrNP) and dibrominated nonylphenol were transformed cometabolically with nonylphenol (NP) as the primary substrate. The presence of either ClNP or BrNP in the S. xenophagum Bayram cultures retarded the transformation of nonhalogenated NP. NP-degrading soil cultures transformed nonhalogenated NP to a mixture of nonyl alcohols but were not capable of transforming either ClNP or BrNP. The presence of either ClNP or BrNP retarded the transformation of nonhalogenated NP in the soil cultures, as was observed in S. xenophagum Bayram cultures. Predicting the environmental fate of alkylphenol ethoxylate residues requires considering APEM halogenation during effluent chlorination and inhibitory effects as well as the refractory nature of halogenated metabolites.

Li Y; Montgomery-Brown J; Reinhard M

2011-02-01

115

Phosphodiesterase inhibition induces retinal degeneration, oxidative stress and inflammation in cone-enriched cultures of porcine retina.  

UK PubMed Central (United Kingdom)

Inherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the phototransduction and, mutations in genes related to its metabolism are responsible for different retinal dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4-5% of the retinitis pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether pharmacological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, thus replacing or reducing animal experiments.

Martínez-Fernández de la Cámara C; Sequedo MD; Gómez-Pinedo U; Jaijo T; Aller E; García-Tárraga P; García-Verdugo JM; Millán JM; Rodrigo R

2013-06-01

116

The confounding effect of nitrite on N2O production by an enriched ammonia-oxidizing culture.  

UK PubMed Central (United Kingdom)

The effect of nitrite (NO2(-)) on the nitrous oxide (N2O) production rate of an enriched ammonia-oxidizing bacteria (AOB) culture was characterized over a concentration range of 0-1000 mg N/L. The AOB culture was enriched in a nitritation system fed with synthetic anaerobic digester liquor. The N2O production rate was highest at NO2(-) concentrations of less than 50 mg N/L. At dissolved oxygen (DO) concentration of 0.55 mg O2/L, further increases in NO2(-) concentration from 50 to 500 mg N/L resulted in a gradual decrease in N2O production rate, which maintained at its lowest level of 0.20 mg N2O-N/h/g VSS in the NO2(-) concentration range of 500-1000 mg N/L. The observed NO2(-)-induced decrease in N2O production was even more apparent at increased DO concentration. At DO concentrations of 1.30 and 2.30 mg O2/L, the lowest N2O production rate (0.25 mg N2O-N/h/g VSS) was attained at a lower NO2(-) concentration of 200-250 mg N/L. These observations suggest that N2O production by the culture is diminished by both high NO2(-) and high DO concentrations. Collectively, the findings show that exceedingly high NO2(-) concentrations in nitritation systems could lead to decreased N2O production. Further studies are required to determine the extent to which the same response to NO2(-) is observed across different AOB cultures.

Law Y; Lant P; Yuan Z

2013-07-01

117

Characterization of an H2-utilizing enrichment culture that reductively dechlorinates tetrachloroethene to vinyl chloride and ethene in the absence of methanogenesis and acetogenesis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have been studying an anaerobic enrichment culture which, by using methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to vinyl chloride and ethene. Our previous results indicated that H2 was the direct electron donor for rductive dechlorination of PCE by the methanol-PCE culture...

Maymó-Gatell, X; Tandoi, V; Gossett, J M; Zinder, S H

118

Short-term in-vitro culture of goat enriched spermatogonial stem cells using different serum concentrations.  

UK PubMed Central (United Kingdom)

PURPOSE: To investigate the effect of serum supplementing on short-term culture, fate determination and gene expression of goat spermatogonial stem cells (SSCs). METHODS: Crude testicular cells were plated over Datura-Stramonium Agglutinin (DSA) for 1 h, and non-adhering cells were cultured in the presence of different serum concentrations (1, 5, 10, and 15%) for 7 days in a highly enriched medium initially developed in mice. Colonies developed in each group were used for the assessment of morphology, immunocytochemistry, and gene expression. RESULTS: Brief incubation of testicular cells with DSA resulted in a significant increase in the number of cells that expressed the germ cell marker (VASA). The expression of THY1, a specific marker of undifferentiated spermatogonia, was significantly higher in colonies developed in the presence of 1% rather than 5, 10 and 15% serum. CONCLUSION: Goat SSCs could proliferate and maintain in SSC culture media for 1 week at serum concentrations as low as 1%, while higher concentrations had detrimental effects on SSC culture/expansion.

Bahadorani M; Hosseini SM; Abedi P; Hajian M; Hosseini SE; Vahdati A; Baharvand H; Nasr-Esfahani MH

2012-01-01

119

Culturing bias in marine heterotrophic flagellates analyzed through seawater enrichment incubations.  

UK PubMed Central (United Kingdom)

The diversity of heterotrophic flagellates is generally based on cultivated strains, on which ultrastructural, physiological, and molecular studies have been performed. However, the relevance of these cultured strains as models of the dominant heterotrophic flagellates in the marine planktonic environment is unclear. In fact, molecular surveys typically recover novel eukaryotic lineages that have refused cultivation so far. This study was designed to directly address the culturing bias in planktonic marine heterotrophic flagellates. Several microcosms were established adding increasing amounts and sources of organic matter to a confined natural microbial community pre-filtered by 3 ?m. Growth dynamics were followed by epifluorescence microscopy and showed the expected higher yield of bacteria and heterotrophic flagellates at increased organic matter additions. Moreover, protist diversity analyzed by molecular tools showed a clear substitution in the community, which differed more and more from the initial sample as the organic matter increased. Within this gradient, there was also an increase of sequences related to cultured organisms as well as a decrease in diversity. Culturing bias is partly explained by the use of organic matter in the isolation process, which drives a shift in the community to conditions closer to laboratory cultures. An intensive culturing effort using alternative isolation methods is necessary to allow the access to the missing heterotrophic flagellates that constitute the abundant and active taxa in marine systems.

Del Campo J; Balagué V; Forn I; Lekunberri I; Massana R

2013-10-01

120

Stable Nitrogen and Oxygen Isotope Analysis of Nitrate using Denitrifying Bacteria  

Science.gov (United States)

The total isotopic composition of nitrate is used for identifying the origin and fate of nitrate in atmospheric, terrestrial and aquatic systems. The analysis of ? 18O, ?15N, and ?17O values each give important and unique information about the sources and sinks of nitrate in these systems. Currently, there is no published method that allows for the simultaneous determination of ?18O, ?15N, and ?17O of nitrate. Cascotti designed a novel method for measurement of ?18O and ?15N in nitrate but not ?17O. This denitrifier method is based on the isotope ratio analysis of nitrous oxide generated by reduction of nitrate by cultured denitrifying bacteria. Kaiser then altered Cascotti's denitrifier method by converting N2O into O2 followed by the quantitative measurement ?18O and ?17O, however ?15N was not measured. Here we present preliminary data on ?15N, ?18O, ?17O values of N2 and O2 generated by the disproportionation of bacterial produced N2O. During the process of denitrification, nitrates are converted to nitrogen gas via a series of intermediate gaseous nitrogen oxide products. This is possible due to the presence of heterotrophic bacteria or autotrophic denitrifiers in select bacteria. Thus, we have chosen three distinct bacteria for the investigation of nitrate reduction for this study: Pseudomonas aureofaciens, Bacillus halodenitrificans, and Achromobacter cycloclastes. They each contain the copper-containing nitrite reductase necessary for the catalyzation of nitrate in order to complete the nitrogen cycle by returning N2 to the atmosphere. Bacillus halodenitrificans has the advantage of being an anaerobic halotolerant (salt-tolerant) denitrifier. Many of our samples have a high saline content; also, pre-concentration techniques using anion resin require elution using high ionic strength solutions. Further, high saline growth solutions limit contamination from other bacteria or organisms. Our efforts also focus on the conversion of N2O over a gold tube into both O2 and N2 using techniques adapted from Cascotti and Kaiser. Our instrument utilizes an extended 11-cup multi-collector feature which does not require a peak jump during analysis on the continuous flow IRMS. Although this is not the first method to study independent measurements of ?18O, ?17O, ?15N, or ?17O, this is first technique that simultaneously detects the stable isotope composition of oxygen and nitrogen in a given nitrate sample. Tests of the impact on isotopic composition by pre-concentration methods have been performed including freeze-drying/evaporation, column chromatography and ion chromatography.

Edenburn, L.; Michalski, G. M.

2009-12-01

 
 
 
 
121

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; Hossein Movahedian Attar; Mahnaz Nikaeen

2013-01-01

122

Anaerobic Oxidation of Ethene Coupled to Sulfate Reduction in Microcosms and Enrichment Cultures.  

UK PubMed Central (United Kingdom)

Ethene is considered recalcitrant under anaerobic conditions, but biological reduction to ethane and oxidation to CO2 have been reported; however, little is known about these processes or the organisms carrying them out. In this report we describe sulfate dependent ethene consumption in microcosms prepared with sediments from a freshwater canal. A first dose of 0.6 mmol/L ethene was consumed within 77 days, and a second dose was largely consumed twelve days later. Material from this microcosm was transferred into growth medium with ethene as the only electron donor (except for trace amounts of vitamins) and sulfate as the electron acceptor. Four doses of ethene were consumed at increasing rates, and the cultures have been transferred at least eight times in this medium. Conversion of [14C]ethene primarily to 14CO2 was demonstrated in fifth and sixth generation cultures, as well as production of sulfide in other cultures, confirming the ethene/sulfate couple. Ovoid cells 1-2 ?m in diameter were found in cultures containing ethene and sulfate, and quantitative PCR showed large increases in bacterial 16S rRNA gene copy number. Over half of a 16S rRNA gene clone library from a sixth-generation culture was a phylotype with a sequence ca. 90% identical with a clade of Deltaproteobacteria that includes Desulfovirga adipica and several Syntrophobacter spp. These studies have solidified the concept that deficits in mass balances for chloroethene fate in sulfate reducing zones of contaminated groundwater sites may be due to ethene oxidation, and suggest a unique phylotype is involved in this process.

Fullerton H; Crawford M; Bakenne A; Freedman DL; Zinder S

2013-09-01

123

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

UK PubMed Central (United Kingdom)

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 (P<0.05) in chicks fed 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.

Chen CM; Cheng WT; Chang YC; Chang TJ; Chen HL

2000-09-01

124

An anaerobic continuous-flow fixed-bed reactor sustaining a 3-chlorobenzoate-degrading denitrifying population utilizing versatile electron donors and acceptors.  

UK PubMed Central (United Kingdom)

An anaerobic continuous-flow fixed-bed column reactor capable of degrading 3-chlorobenzoate (3-CBA) under denitrifying conditions was established, and its rate reached 2.26 mM d(-1). The denitrifying population completely degraded 3-CBA when supplied at 0.1-0.54 mM, but its activity was partly suppressed when 3-CBA was supplied at 0.89 mM. Nitrate was concomitantly consumed throughout the operation of the reactor, the amount of which was similar to or up to 35% higher than the theoretical stoichiometric value that was calculated by assuming that 3-CBA degradation is coupled with denitrification. Batch incubation experiments proved that nitrate is strictly required for 3-CBA degradation in the absence of molecular oxygen. The population also degraded 3-CBA aerobically. Benzoate and 4-CBA were degraded under denitrifying conditions as well as 3-CBA, but 2-CBA was not. Considering that the previously reported denitrifying 3-CBA-degrading cultures do not exhibit 4-CBA degradation under denitrifying conditions, nor aerobic 3-CBA degradation [FEMS Microbiol. Lett. 144 (1996) 213, Appl. Environ. Microbiol. 66 (2000) 3446], the microbial population developed in this experiment was physiologically versatile with respect to the utilization of both electron donors and electron acceptors.

Bae HS; Yamagishi T; Suwa Y

2004-04-01

125

Activin-A binding and biochemical effects in osteoblast-enriched cultures from fetal-rat parietal bone.  

UK PubMed Central (United Kingdom)

Activin, a disulfide-linked polypeptide dimer first isolated from gonadal tissue extracts, has amino acid sequence and structural homology with transforming growth factor beta (TGF beta). Along with other activities, TGF beta regulates replication and differentiation and interacts with a defined set of binding sites on isolated bone cells. To determine if activin shares these properties, recombinant human activin-A (A-chain homodimer) was examined in osteoblast-enriched cultures obtained from fetal-rat parietal bone. After 23 h of treatment, 60 to 6,000 pM activin-A increased the rate of [3H]thymidine incorporation into DNA 1.5- to 4.0-fold, and at 600 to 6,000 pM, it enhanced the rate of [3H]proline incorporation into collagen and noncollagen protein by up to 1.7-fold. Like earlier studies with TGF beta in primary osteoblast-enriched cultures, the stimulatory effects of activin-A on DNA and protein synthesis were opposed by parathyroid hormone, and the influence of activin-A on collagen synthesis was independent of cell replication. Binding studies with 125I-activin-A indicated approximately 8,000 high-affinity (Kd = 0.4 nM) and 300,000 low-affinity (Kd = 40 to 50 nM) binding sites per cell. Polyacrylamide gel analysis revealed 125I-activin-A-binding complexes of Mr greater than 200,000 and 73,000 which did not appear to correspond to primary TGF beta-binding sites. These results indicate that activin-A produces TGF beta-like effects in bone and that some of these effects may be mediated, at least in part, by distinct activin receptors on bone cells.

Centrella M; McCarthy TL; Canalis E

1991-01-01

126

[Formation of a methylotrophic denitrifying biocenosis in a system of sewage treatment for nitrates  

UK PubMed Central (United Kingdom)

A methylotrophic denitrifying bioenosis composed of hyphomicrobes and paracocci was isolated from the active ooze in a system of sewage purification from nitrates. The morphological and physiological characteristics of the isolated Hyphomicrobium sp. Z-115 and Paracoccus denitrificans Z-100 and Z-121 strains differed from those of the type strains, which made it difficult to identify them and to isolate them as a pure culture. This should be taken into account while determining the agents operating in such purification systems. The rate of growth, the rate of nitrate reduction and the activity of enzymes involved in methanol assimilation are higher in the anabolic syntrophic bicenosis than in its components in pure culture. A combined culture composed of the collection Hyphomicrobium and Paracoccus strains was neither effective nor stable under the conditions of anaerobic growth with nitrate and methanol. Therefore, the natural biocenosis af the purification system cannot be substituted by an artificial one composed of the collection cultures.

Vedenina IIa; Govorukhina NI

1988-03-01

127

Characterization of efficient aerobic denitrifiers isolated from two different sequencing batch reactors by 16S-rRNA analysis.  

UK PubMed Central (United Kingdom)

By adopting two sequencing batch reactors (SBRs) A and B, nitrate as the substrate, and the intermittent aeration mode, activated sludge was domesticated to enrich aerobic denitrifiers. The pHs of reactor A were approximately 6.3 at DOs 2.2-6.1 mg/l for a carbon source of 720 mg/l COD; the pHs of reactor B were 6.8-7.8 at DOs 2.2-3.0 mg/l for a carbon source of 1500 mg/l COD. Both reactors maintained an influent nitrate concentration of 80 mg/l NO3- -N. When the total inorganic nitrogen (TIN) removal efficiency of both reactors reached 60%, aerobic denitrifier accumulation was regarded completed. By bromthymol blue (BTB) medium, 20 bacteria were isolated from the two SBRs and DNA samples of 8 of these 20 strains were amplified by PCR and processed for 16SrRNA sequencing. The obtained results were analysed by a Blast similarity search of the GenBank database, and constructing a phylogenetic tree for identification by comparison. The 8 bacteria were found to belong to the genera Pseudomonas, Delftia, Herbaspirillum and Comamonas. At present, no Delftia has been reported to be an aerobic denitrifier.

Wang P; Li X; Xiang M; Zhai Q

2007-06-01

128

Enrichment and clonal culture of hepatic stem/progenitor cells during mouse liver development.  

UK PubMed Central (United Kingdom)

Liver regenerates after hepatectomy or chemical-induced injury. In contrast to cells in other tissues that can regenerate, mature cells (hepatocytes), but not undifferentiated stem cells, are mainly responsible for acute liver regeneration. Liver stem cells take part in liver regeneration in some forms of chronic liver injury, when the proliferative ability of differentiated hepatocytes is impaired. During liver development, both hepatocytes and cholangiocytes are differentiated from common precursor cells, called hepatoblasts. By combining fluorescence-activated cell sorting (FACS) and an in vitro clonal culture system for stem/progenitor cells, we established a method to isolate stem/progenitor cells prospectively from mouse fetal and adult livers. FACS clone-sorted single CD45(-)Ter119(-)c-kit(-)CD13(+)CD133(+) cells (from fetal mid-gestational livers) or CD45(-)Ter119(-)c-kit(-)Sca1(-)CD13(+)CD49f(+)CD133(+) cells (from adult livers) can form a colony containing both albumin-positive hepatocytes and cytokeratin 19-positive bile ductal cells, indicating that these cells have the characters of liver stem/progenitor cells (proliferative capability and bipotency for hepatic and for biliary epithelial differentiation). These cells can maintain these capabilities for several months in culture.

Kamiya A; Nakauchi H

2013-01-01

129

Effects of deflazacort on aspects of bone formation in cultures of intact calvariae and osteoblast-enriched cells.  

UK PubMed Central (United Kingdom)

Deflazacort, a synthetic glucocorticoid reported to have bone-sparing properties in vivo, and cortisol were compared for their effects on bone formation in vitro. Deflazacort and cortisol were studied for their effects on DNA and collagen synthesis in cultures of intact fetal rat calvariae and of osteoblast-enriched (Ob) cells from 21- to 22-day-old fetal rat parietal bone. Both steroids were also examined for their effects on skeletal insulin-like growth factor (IGF) I production, which is decreased by cortisol and appears relevant to its mode of action. After 24 h of culture, deflazacort and cortisol had limited effects on the parameters studied, although cortisol at 100 nM decreased [3H]proline incorporation into collagen in intact calvariae. In contrast, after 72 h deflazacort and cortisol at 1-100 nM inhibited the incorporation of [3H]thymidine into DNA and at 100 nM decreased the incorporation of [3H]proline into collagen and noncollagen protein in intact calvariae. Deflazacort and cortisol at 10-1000 nM decreased calvarial collagen degradation to a similar extent. Both steroids had a similar activity, and at 100 nM for 72 h they decreased IGF-I production by calvariae; however, cortisol at 10 nM was somewhat more effective than deflazacort in decreasing IGF-I levels. Deflazacort and cortisol had analogous effects in Ob cell cultures. After 24 h of treatment, deflazacort at 100-1000 nM and cortisol at 10-1000 nM decreased the labeling of DNA, and both steroids at 100-1000 nM caused a similar decrease in [3H]proline incorporation into collagen in Ob cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Canalis E; Avioli L

1992-09-01

130

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

2013-07-24

131

Effects of oxygen on biodegradation of benzoate and 3-chlorobenzoate in a denitrifying chemostat.  

UK PubMed Central (United Kingdom)

A mixed microbial culture degraded a mixture of benzoate (863 mg/L), 3-chlorobenzoate (3-CB) (69.7 mg/L), and pyruvate (244 mg/L) under denitrifying conditions in a chemostat. Biodegradation under denitrifying conditions was stable, complete (effluent concentrations below detection limits), and proceeded without the production of toxic intermediates like chlorocatechols. The addition of oxygen at mass input rates of 6.2%, 15.5%, and 43.9% of the mass input rate of chemical oxygen demand (COD) (337 mg COD/h) did not induce the synthesis of aerobic biodegradation pathways and thus did not disrupt biodegradation. Rather, the oxygen was used as a terminal electron acceptor, displacing a stoichiometric amount of nitrate, leading to microaerobic conditions (dissolved oxygen concentration <0.050 mg/L) in which oxygen utilization and denitrification occurred simultaneously. The reduction of nitrate occurred fully to N(2) gas with no accumulation of nitrite, nitrous oxide, or nitric oxide, although the ability of the culture to transfer electrons to the nitrogen oxides decreased as the oxygen input was increased. The anoxic benzoate uptake capability was unaffected by the increase in oxygen addition, but the anoxic 3-CB uptake capability increased, as did the level of benzoyl-CoA reductase in the cells.

Deniz T; Cinar O; Grady CP Jr

2004-12-01

132

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

UK PubMed Central (United Kingdom)

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.

Dolhi JM; Ketchum N; Morgan-Kiss RM

2012-01-01

133

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

UK PubMed Central (United Kingdom)

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

Nájera-Fernández C; Zafrilla B; Bonete MJ; Martínez-Espinosa RM

2012-09-01

134

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

International Nuclear Information System (INIS)

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

2011-01-01

135

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-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.

1991-01-01

136

Nitrogen fixation in denitrified marine waters.  

Science.gov (United States)

Nitrogen fixation is an essential process that biologically transforms atmospheric dinitrogen gas to ammonia, therefore compensating for nitrogen losses occurring via denitrification and anammox. Currently, inputs and losses of nitrogen to the ocean resulting from these processes are thought to be spatially separated: nitrogen fixation takes place primarily in open ocean environments (mainly through diazotrophic cyanobacteria), whereas nitrogen losses occur in oxygen-depleted intermediate waters and sediments (mostly via denitrifying and anammox bacteria). Here we report on rates of nitrogen fixation obtained during two oceanographic cruises in 2005 and 2007 in the eastern tropical South Pacific (ETSP), a region characterized by the presence of coastal upwelling and a major permanent oxygen minimum zone (OMZ). Our results show significant rates of nitrogen fixation in the water column; however, integrated rates from the surface down to 120 m varied by ?30 fold between cruises (7.5±4.6 versus 190±82.3 µmol m(-2) d(-1)). Moreover, rates were measured down to 400 m depth in 2007, indicating that the contribution to the integrated rates of the subsurface oxygen-deficient layer was ?5 times higher (574±294 µmol m(-2) d(-1)) than the oxic euphotic layer (48±68 µmol m(-2) d(-1)). Concurrent molecular measurements detected the dinitrogenase reductase gene nifH in surface and subsurface waters. Phylogenetic analysis of the nifH sequences showed the presence of a diverse diazotrophic community at the time of the highest measured nitrogen fixation rates. Our results thus demonstrate the occurrence of nitrogen fixation in nutrient-rich coastal upwelling systems and, importantly, within the underlying OMZ. They also suggest that nitrogen fixation is a widespread process that can sporadically provide a supplementary source of fixed nitrogen in these regions. PMID:21687726

Fernandez, Camila; Farías, Laura; Ulloa, Osvaldo

2011-06-07

137

Nitrogen fixation in denitrified marine waters.  

UK PubMed Central (United Kingdom)

Nitrogen fixation is an essential process that biologically transforms atmospheric dinitrogen gas to ammonia, therefore compensating for nitrogen losses occurring via denitrification and anammox. Currently, inputs and losses of nitrogen to the ocean resulting from these processes are thought to be spatially separated: nitrogen fixation takes place primarily in open ocean environments (mainly through diazotrophic cyanobacteria), whereas nitrogen losses occur in oxygen-depleted intermediate waters and sediments (mostly via denitrifying and anammox bacteria). Here we report on rates of nitrogen fixation obtained during two oceanographic cruises in 2005 and 2007 in the eastern tropical South Pacific (ETSP), a region characterized by the presence of coastal upwelling and a major permanent oxygen minimum zone (OMZ). Our results show significant rates of nitrogen fixation in the water column; however, integrated rates from the surface down to 120 m varied by ?30 fold between cruises (7.5±4.6 versus 190±82.3 µmol m(-2) d(-1)). Moreover, rates were measured down to 400 m depth in 2007, indicating that the contribution to the integrated rates of the subsurface oxygen-deficient layer was ?5 times higher (574±294 µmol m(-2) d(-1)) than the oxic euphotic layer (48±68 µmol m(-2) d(-1)). Concurrent molecular measurements detected the dinitrogenase reductase gene nifH in surface and subsurface waters. Phylogenetic analysis of the nifH sequences showed the presence of a diverse diazotrophic community at the time of the highest measured nitrogen fixation rates. Our results thus demonstrate the occurrence of nitrogen fixation in nutrient-rich coastal upwelling systems and, importantly, within the underlying OMZ. They also suggest that nitrogen fixation is a widespread process that can sporadically provide a supplementary source of fixed nitrogen in these regions.

Fernandez C; Farías L; Ulloa O

2011-01-01

138

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

2012-04-20

139

Isolation and culture of highly enriched populations of Leydig cells from guinea-pig (Cavia porcellus) testes.  

UK PubMed Central (United Kingdom)

Leydig cells were isolated from adult male guinea-pig testes using a multi-step procedure involving enzymatic dissociation and Percoll-gradient centrifugation. The following description is the first account of a successful isolation of adolescent guinea-pig Leydig cells. The enriched Leydig-cell preparation routinely isolated from six intact testicles yielded approximately 5.0 x 10(6) +/- 0.7 x 10(6) (+/- SEM) Leydig cells with a viability of 98.0 +/- 0.4% as determined using the trypan-blue exclusion method. The purity of the isolated cell population as assessed by 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) staining averaged 82.5 +/- 0.8%. Under light microscopy, guinea-pig Leydig cells were polyhedral in shape with a large prominent nucleus and a distinct nucleolus. The acidophilic cytoplasm contained numerous lipid-filled vesicles. Ultrastructurally, guinea-pig Leydig cells displayed an eccentrically located ovoid nucleus with dark-staining peripheral heterochromatin. Large quantities of mitochondria, smooth endoplasmic reticulum and particulate-laden lipid droplets were also evident. The steroidogenic potential of the isolated Leydig cells was verified using a maximally stimulating dose of ovine LH (100 ng ml-1) and human CG (200 mIU ml-1). Leydig cells incubated in a shaking (120 cycles min-1) water bath for 3 h at 37 degrees C in capped polypropylene microcentrifuge tubes produced 233 +/- 21 ng and 223 +/- 18 ng testosterone per 1 x 10(6) cells when maximally stimulated with oLH or hCG, respectively. The inclusion of low (1-5 microM) levels of sodium ascorbate during culture enhanced significantly Leydig-cell viability vs. control values.

Kukucka MA; Misra HP

1994-07-01

140

Mechanism of hydrogen utilization by anaerobic cis-1,2-dichlorothylene-degrading enrichment cultures; Cis-1,2-dichloroehylene bunkai kenkisei shuseki baiyokin no suiso riyo kiko  

Energy Technology Data Exchange (ETDEWEB)

cis-1,2-Dichloroethylene (cis-DCE) is frequently found as a groundwater contaminant. cis-DCE can be biotransformed via reductive dechlorination to ethylene under anaerobic conditions. We have recently reported a high-rate transformation of cis-DCE to ethylene by an-aerobic enrichment cultures. A small part of ethylene was further reduced to ethane. Hydrogen appeared to be the actual electron donor for reductive transformation of cis-DCE in these cultures. In this study, batch experiments were conducted for investigating the mechanism of cis-DCE transformation by these anaerobic enrichment cultures. Hydrogen was used as an electron donor. Addition of 2-bromoethanesulfonate (BES), a specific inhibitor of methanogenesis, did not inhibit reductive dechlorination of cis-DCE. The major organisms utilizing hydrogen were not methanogens but homoacetogens. These results suggest that the dechlorinating organisms were homoacetogens. On the other hand, reduction of ethylene to ethane was inhibited in the presence of BES, suggesting a role of methanogens in this transformation. Batch experiments examining the biodegradability of tetrachloroethylene (PCE) by these cultures were also conducted and it was found that the cultures were able to transform PCE to ethylene at high rates. 17 refs., 8 figs., 1 tab.

Komatsu, T.; Momonoi, K. [Nagaoka University of Technology, Niigata (Japan); Matsuo, T. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering; Hanaki, K. [The University of Tokyo, Tokyo (Japan). Research Center for Advanced Science and Technology

1995-07-10

 
 
 
 
141

Keratinocyte serum-free medium maintains long-term liver gene expression and function in cultured rat hepatocytes by preventing the loss of liver-enriched transcription factors  

Science.gov (United States)

Freshly isolated hepatocytes rapidly lose their differentiated properties when placed in culture. Therefore, production of a simple culture system for maintaining the phenotype of hepatocytes in culture would greatly facilitate their study. Our aim was to identify conditions that could maintain the differentiated properties of hepatocytes for up to 28 days of culture. Adult rat hepatocytes were isolated and attached in Williams’ medium E containing 10% serum. The medium was changed to either fresh Williams’ medium E or keratinocyte serum-free medium supplemented with dexamethasone, epidermal growth factor and pituitary gland extract. The hepatic phenotype was then analysed using RT-PCR, immunohistochemistry, Western blotting and assays of liver function. Cells cultured in keratinocyte serum-free medium supplemented with dexamethasone, epidermal growth factor and pituitary gland extract maintained their phenotype for 3–4 weeks, based on expression of liver proteins, ureagensis and response to xenobiotics. In contrast, hepatocytes cultured in Williams’ medium E rapidly lost the expression of liver proteins after 3 days. Cells cultured in keratinocyte serum-free medium supplemented with dexamethasone, epidermal growth factor and pituitary gland extract maintained their expression of liver-enriched transcription factors (C/EBP? and ?, HNF4? and RXR?) while expression was either lost or reduced in cells cultured in Williams’ medium E. These results suggest that keratinocyte serum-free medium supplemented with dexamethasone, epidermal growth factor and pituitary gland extract can maintain the hepatic phenotype for a prolonged period and that this is probably related to the continued expression of the liver-enriched transcription factors.

Li, Wan-Chun; Ralphs, Kate L.; Slack, Jonathan M.W.; Tosh, David

2007-01-01

142

Characterization of an H{sub 2}-utilizing enrichment culture that reductivity dechlorinates tetrachloroethene to vinyl chloride and ethene in the absence of methanogenesis and acetogenesis  

Energy Technology Data Exchange (ETDEWEB)

We have been studying an anaerobic enrichment culture which, by using methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to vinyl chloride and ethene. Our previous results indicated that H{sub 2} was the direct electron donor for reductive dechlorination of PCE by the methanol-PCE culture. Most-probable-number counts performed on this culture indicated low numbers ({le}10{sup 4}/ml) of sulfidogens, methanol-utilizing acetogens, fermentative heterotrophs, and PCE dechlorinators using H{sub 2}{center_dot}-PCE culture used PCE at increasing rates over time when transferred to fresh medium and could be transferred indefinitely with H{sub 2} as the electron donor-acceptor pair for energy conservation growth. Sustained PCE dechlorination by this culture was supported by supplementation with 0.05 mg of vitamin B{sub 12} per liter, 25% (vol/vol) anaerobic digestor sludge supernatant,and 2 mM acetate, which presumably served as a carbon source. Neither methanol nor acetate could serve as an electron donor for dechlorination by the H{sub 2}-PCE culture, and it did not produce CH{sub 4} or acetate from H{sub 2}-CO{sub 2} or methanol, indicating the absense of methanogenic and acetogenic bacteria. Microscopic observations of the purified H{sub 2}-PCE culture showed only two major morphotypes: irregular cocci and small rods. 31 refs., 6 figs., 2 tabs.

Maymo-Gatell, X.; Tandoi, V.; Zinder, S.H. [Cornell Univ., Ithaca, NY (United States)] [and others

1995-11-01

143

Biosynthesis of highly enriched 13C-lycopene for human metabolic studies using repeated batch tomato cell culturing with 13C-glucose.  

UK PubMed Central (United Kingdom)

While putative disease-preventing lycopene metabolites are found in both tomato (Solanum lycopersicum) products and in their consumers, mammalian lycopene metabolism is poorly understood. Advances in tomato cell culturing techniques offer an economical tool for generation of highly-enriched (13)C-lycopene for human bioavailability and metabolism studies. To enhance the (13)C-enrichment and yields of labelled lycopene from the hp-1 tomato cell line, cultures were first grown in (13)C-glucose media for three serial batches and produced increasing proportions of uniformly labelled lycopene (14.3±1.2%, 39.6±0.5%, and 48.9±1.5%) with consistent yields (from 5.8 to 9 mg/L). An optimised 9-day-long (13)C-loading and 18-day-long labelling strategy developed based on glucose utilisation and lycopene yields, yielded (13)C-lycopene with 93% (13)C isotopic purity, and 55% of isotopomers were uniformly labelled. Furthermore, an optimised acetone and hexane extraction led to a fourfold increase in lycopene recovery from cultures compared to a standard extraction.

Moran NE; Rogers RB; Lu CH; Conlon LE; Lila MA; Clinton SK; Erdman JW Jr

2013-08-01

144

Biosynthesis of highly enriched 13C-lycopene for human metabolic studies using repeated batch tomato cell culturing with 13C-glucose.  

Science.gov (United States)

While putative disease-preventing lycopene metabolites are found in both tomato (Solanum lycopersicum) products and in their consumers, mammalian lycopene metabolism is poorly understood. Advances in tomato cell culturing techniques offer an economical tool for generation of highly-enriched (13)C-lycopene for human bioavailability and metabolism studies. To enhance the (13)C-enrichment and yields of labelled lycopene from the hp-1 tomato cell line, cultures were first grown in (13)C-glucose media for three serial batches and produced increasing proportions of uniformly labelled lycopene (14.3±1.2%, 39.6±0.5%, and 48.9±1.5%) with consistent yields (from 5.8 to 9 mg/L). An optimised 9-day-long (13)C-loading and 18-day-long labelling strategy developed based on glucose utilisation and lycopene yields, yielded (13)C-lycopene with 93% (13)C isotopic purity, and 55% of isotopomers were uniformly labelled. Furthermore, an optimised acetone and hexane extraction led to a fourfold increase in lycopene recovery from cultures compared to a standard extraction. PMID:23561155

Moran, Nancy Engelmann; Rogers, Randy B; Lu, Chi-Hua; Conlon, Lauren E; Lila, Mary Ann; Clinton, Steven K; Erdman, John W

2013-01-23

145

COLLABORATIVE PLANNING FOR FORMATIVE ASSESSMENT AND CULTURAL APPROPRIATENESS IN THE GIRLS HEALTH ENRICHMENT MULTI-SITE STUDIES (GEMS): A RETROSPECTION.  

Science.gov (United States)

The Girls health Enrichment Multi-site Studies (GEMS), Phase 1, developed and pilot-tested interventions to prevent obesity in African-American preadolescent girls. This article describes the collaborative planning process undertaken to take full advantage of formative assessment activities for impr...

146

Alternative anaerobic enrichments to the bacteriological analytical manual culture method for isolation of Shigella sonnei from selected types of fresh produce.  

UK PubMed Central (United Kingdom)

Alternative methods of reducing oxygen during anaerobic enrichment in the Bacteriological Analytical Manual (BAM) Shigella culture method were evaluated and compared to the current and less practical GasPak method. The alternative anaerobic methods included the use of reducing agents in Shigella broth and reducing culture container headspace volume to minimize atmospheric effects on oxygen concentration in Shigella broth during enrichment. The reducing agents evaluated were sodium thioglycollate, L-cystine, L-cysteine, titanium(III) citrate, and dithiothreitol, each at concentrations of 0.1, 0.05, and 0.01%. The use of Oxyrase for Broth with the enrichment medium (Shigella broth) was evaluated at concentrations of 10, 20 and 30 microL/mL. Recoveries of chill- and freeze-stressed S. sonnei strains 357 and 20143 were determined with each anaerobic method, including the GasPak method, using inoculation levels ranging from 10(0)to 10(3) cells. For each anaerobic method, strain, inoculation level, and stress type, 5 replicate enrichments were evaluated by streaking to MacConkey agar for isolation. The numbers of cultures with each method from which S. sonnei was isolated were used to compare the alternative anaerobic methods to the GasPak method. The alternative anaerobic method with which chill- and freeze-stressed S. sonnei strains 357 and 20143 were isolated most consistently was the use of Oxyrase for Broth in Shigella broth at a concentration of 20 microL/mL. This method was compared to the GasPak anaerobic method in evaluations on the recovery of S. sonnei strains 357 and 20143 from artificially contaminated test portions of parsley, cilantro, green onions, strawberries, carrots, and celery. A third anaerobic method included the use of 0.5 cm mineral oil overlay on cultures containing Oxyrase for Broth at concentrations of 20 microL/mL. Recovery rates of strain 357 were significantly greater (p < 0.05) with the GasPak method than with Oxyrase for Broth, with and without the 0.5 cm mineral oil overlay, for test portions of parsley, cilantro, and celery. When Oxyrase for Broth was used with Shigella broth, strain 357 was isolated at higher rates from all produce types, except cilantro, when 0.5 cm mineral oil overlay was applied to enrichment cultures. The use of mineral oil overlay with Oxyrase for Broth also improved recovery of strain 20143 from test portions of all produce types except green onion and strawberries. These differences were significant (p < 0.05) with parsley, carrots, and cilantro (1 of 2 evaluations). No statistically significant differences (p > 0.05) between the GasPak and Oxyrase for Broth anaerobic methods occurred when mineral oil overlay was used with Oxyrase for Broth. The use of Oxyrase for Broth with a 0.5 cm mineral oil overlay is a practical alternative for anaerobic enrichment with the BAM method in the analysis of some produce types. Differences in recovery among the different produce types and methods occurred between S. sonnei strains 357 and 20143, emphasizing the need for additional S. sonnei strains in future evaluations.

Jacobson AP; Thunberg RL; Johnson ML; Hammack TS; Andrews WH

2004-09-01

147

Alternative anaerobic enrichments to the bacteriological analytical manual culture method for isolation of Shigella sonnei from selected types of fresh produce.  

Science.gov (United States)

Alternative methods of reducing oxygen during anaerobic enrichment in the Bacteriological Analytical Manual (BAM) Shigella culture method were evaluated and compared to the current and less practical GasPak method. The alternative anaerobic methods included the use of reducing agents in Shigella broth and reducing culture container headspace volume to minimize atmospheric effects on oxygen concentration in Shigella broth during enrichment. The reducing agents evaluated were sodium thioglycollate, L-cystine, L-cysteine, titanium(III) citrate, and dithiothreitol, each at concentrations of 0.1, 0.05, and 0.01%. The use of Oxyrase for Broth with the enrichment medium (Shigella broth) was evaluated at concentrations of 10, 20 and 30 microL/mL. Recoveries of chill- and freeze-stressed S. sonnei strains 357 and 20143 were determined with each anaerobic method, including the GasPak method, using inoculation levels ranging from 10(0)to 10(3) cells. For each anaerobic method, strain, inoculation level, and stress type, 5 replicate enrichments were evaluated by streaking to MacConkey agar for isolation. The numbers of cultures with each method from which S. sonnei was isolated were used to compare the alternative anaerobic methods to the GasPak method. The alternative anaerobic method with which chill- and freeze-stressed S. sonnei strains 357 and 20143 were isolated most consistently was the use of Oxyrase for Broth in Shigella broth at a concentration of 20 microL/mL. This method was compared to the GasPak anaerobic method in evaluations on the recovery of S. sonnei strains 357 and 20143 from artificially contaminated test portions of parsley, cilantro, green onions, strawberries, carrots, and celery. A third anaerobic method included the use of 0.5 cm mineral oil overlay on cultures containing Oxyrase for Broth at concentrations of 20 microL/mL. Recovery rates of strain 357 were significantly greater (p cilantro, and celery. When Oxyrase for Broth was used with Shigella broth, strain 357 was isolated at higher rates from all produce types, except cilantro, when 0.5 cm mineral oil overlay was applied to enrichment cultures. The use of mineral oil overlay with Oxyrase for Broth also improved recovery of strain 20143 from test portions of all produce types except green onion and strawberries. These differences were significant (p cilantro (1 of 2 evaluations). No statistically significant differences (p > 0.05) between the GasPak and Oxyrase for Broth anaerobic methods occurred when mineral oil overlay was used with Oxyrase for Broth. The use of Oxyrase for Broth with a 0.5 cm mineral oil overlay is a practical alternative for anaerobic enrichment with the BAM method in the analysis of some produce types. Differences in recovery among the different produce types and methods occurred between S. sonnei strains 357 and 20143, emphasizing the need for additional S. sonnei strains in future evaluations. PMID:15493668

Jacobson, Andrew P; Thunberg, Richard L; Johnson, Mildred L; Hammack, Thomas S; Andrews, Wallace H

148

Azoarcus taiwanensis sp. nov., a denitrifying species isolated from a hot spring.  

UK PubMed Central (United Kingdom)

The strain NSC3(T), a novel, facultative, chemolithotrophic, denitrifying, alkaliphilic, sulfide-oxidizing bacterium isolated from a hot spring in Yang-Ming Mountain, Taiwan, was Gram negative, rod shaped, and motile by single polar flagella and grew facultatively by adopting a denitrifying metabolism. The 16S rRNA sequence analysis revealed that strain NSC3(T) belongs to beta subclass of the Proteobacteria and most closely related to Azoarcus evansii KB740(T) (95.44 %), Azoarcus toluvorans Td-21(T) (95.21 %), Azoarcus tolulyticus Tol-4(T) (95.08 %), and Azoarcus toluclasticus MF63(T) (94.94 %). The phylogenetic analyses based on 16S rRNA gene sequences indicated that the strain NSC3(T) formed a distinct lineage in the Betaproteobacteria and that it exhibited the highest level of sequence similarity with species of the genera Azoarcus (95.28-93.13 %). The major fatty acids of the type strain were C16:0 (26.9 %), C16:1w7c (28.9 %), C18:0 (9.6 %), and C18:1w7c/w6c (29.9 %). The DNA G+C content of genomic DNA was 63.7 mol%. On the basis of the 16S rRNA sequence similarity, phenotypic and genotypic characteristics, and chemotaxonomic data, the strain NSC3(T) could be differentiated from other species of the genus Azoarcus. Therefore, strain NSC3(T) (equal to BCRC 80111(T) and DSM 24109(T)) is proposed as a novel species in genus Azoarcus, for which the name Azoarcus taiwanensis sp. nov. is proposed. The strain NSC3(T) is deposited in Bioresource Collection and Research Center, Taiwan, under the reference number BCRC 80111(T), and German Collection of Microorganisms and Cell Cultures, Germany (DSMZ), with DSM 24109(T).

Lee DJ; Wong BT; Adav SS

2013-05-01

149

Azoarcus taiwanensis sp. nov., a denitrifying species isolated from a hot spring.  

Science.gov (United States)

The strain NSC3(T), a novel, facultative, chemolithotrophic, denitrifying, alkaliphilic, sulfide-oxidizing bacterium isolated from a hot spring in Yang-Ming Mountain, Taiwan, was Gram negative, rod shaped, and motile by single polar flagella and grew facultatively by adopting a denitrifying metabolism. The 16S rRNA sequence analysis revealed that strain NSC3(T) belongs to beta subclass of the Proteobacteria and most closely related to Azoarcus evansii KB740(T) (95.44 %), Azoarcus toluvorans Td-21(T) (95.21 %), Azoarcus tolulyticus Tol-4(T) (95.08 %), and Azoarcus toluclasticus MF63(T) (94.94 %). The phylogenetic analyses based on 16S rRNA gene sequences indicated that the strain NSC3(T) formed a distinct lineage in the Betaproteobacteria and that it exhibited the highest level of sequence similarity with species of the genera Azoarcus (95.28-93.13 %). The major fatty acids of the type strain were C16:0 (26.9 %), C16:1w7c (28.9 %), C18:0 (9.6 %), and C18:1w7c/w6c (29.9 %). The DNA G+C content of genomic DNA was 63.7 mol%. On the basis of the 16S rRNA sequence similarity, phenotypic and genotypic characteristics, and chemotaxonomic data, the strain NSC3(T) could be differentiated from other species of the genus Azoarcus. Therefore, strain NSC3(T) (equal to BCRC 80111(T) and DSM 24109(T)) is proposed as a novel species in genus Azoarcus, for which the name Azoarcus taiwanensis sp. nov. is proposed. The strain NSC3(T) is deposited in Bioresource Collection and Research Center, Taiwan, under the reference number BCRC 80111(T), and German Collection of Microorganisms and Cell Cultures, Germany (DSMZ), with DSM 24109(T). PMID:23695778

Lee, Duu-Jong; Wong, Biing-Teo; Adav, Sunil S

2013-05-22

150

Molecular and Stable Isotope Investigation of Nitrite Respiring Bacterial Communities Capable of Anaerobic Ammonium Oxidation (ANAMMOX) and Denitrifying Anaerobic Methane Oxidation (DAMO) in Nitrogen Contaminated Groundwater  

Science.gov (United States)

Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) are two recently discovered N2 production pathways in the microbial nitrogen cycle. ANAMMOX has been relatively well investigated in various aquatic ecosystems, while DAMO has been examined only in freshwater wetlands. However, neither ANAMMOX nor DAMO have been studied in groundwater ecosystems as microbial N removal processes where they could compliment or compete with denitrification to remediate N contaminated aquifers. Thus, we conducted molecular and stable isotope analyses to detect and measure ANAMMOX and DAMO in a nitrogen contaminated aquifer on Cape Cod, Massachusetts. The study site has a plume of nitrogen contaminated groundwater as a result of continuous discharge of treated wastewater over 60 years. Groundwater was collected from multiport sampling devices installed at two sites, near the waste-water disposal location (A) and more than 3 km down gradient (B) along the contamination plume. Biomass was collected from water samples for DNA extraction and 15N tracer incubation experiments. PCR with specific 16S rRNA gene primers detected the presence of ANAMMOX and DAMO bacteria at both sites. Phylogenetic analysis of 16S rRNA genes revealed that the ANAMMOX community at site A was most associated with Kuenenia spp. while site B had a community more closely related to Brocadia spp. The DAMO communities at the two sites were quite different based on 16S rRNA gene analysis. The communities at site B are closely associated with Candidatus “Methylomirabilis oxyfera”, which is the first enriched DAMO culture. Most of the 16S rRNA sequences detected in site A were related to those found in other DAMO enrichment cultures established from a eutrophic ditch sediment. In order to determine active members of ANAMMOX communities, the transcriptional expression of hydrazine oxidase (hzo) and hydrazine hydrolase (hh) genes was examined at both sites. In addition, 15N tracer incubation experiments were used to measure the rates of ANAMMOX and denitrification. ANAMMOX was found to be higher than denitrification at site A where ANAMMOX accounted for 60% of the 15N2 production. In contrast, denitrification was higher than ANAMMOX at site B where Methylomirabilis spp. were found. Thus, this study clearly demonstrates the potential importance of ANAMMOX and DAMO in the nitrogen removal from groundwater and suggests that detailed characterization of the processes under in situ subsurface conditions could provide new information regarding the ecology of these microbes.

Song, B.; Hirsch, M.; Taylor, J.; Smith, R. L.; Repert, D.; Tobias, C. R.

2010-12-01

151

Community Composition and Functioning of Denitrifying Bacteria from Adjacent Meadow and Forest Soils  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigated communities of denitrifying bacteria from adjacent meadow and forest soils. Our objectives were to explore spatial gradients in denitrifier communities from meadow to forest, examine whether community composition was related to ecological properties (such as vegetation type and proce...

Rich, J. J.; Heichen, R. S.; Bottomley, P. J.; Cromack, K.; Myrold, D. D.

152

Neuron-enriched cultures of adult rat dorsal root ganglia: establishment, characterization, survival, and neuropeptide expression in response to trophic factors.  

UK PubMed Central (United Kingdom)

It is unknown whether adult dorsal root ganglion (DRG) neurons require trophic factors for their survival and maintenance of neuropeptide phenotypes. We have established and characterized neuron-enriched cultures of adult rat DRGs and investigated their responses to nerve growth factor (NGF), ciliary neuronotrophic factor (CNTF), pig brain extract (PBE, crude fraction of brain-derived neuronotrophic factor, BDNF), and laminin (LN). DRGs were dissected from levels C1 through L6 and dissociated and freed from myelin fragments and most satellite (S-100-immunoreactive) cells by centrifugation on Percoll and preplating. The enriched neurons, characterized by their morphology and immunoreactivity for neuron-specific enolase, constituted a population representative of the in vivo situation with regard to expression of substance P (SP), somatostatin (SOM), and cholecystokinin-8 (CCK) immunoreactivities. In the absence of trophic factors and using polyornithine (PORN) as a substratum, 60-70% of the neurons present initially (0.5 days) had died after 7 days. LN as a substratum did not prevent a 30% loss of neurons up to day 4.5, but it subsequently maintained DRG neurons at a plateau. This behavior might reflect a cotrophic effect of LN and factors provided by non-neuronal cells, whose proliferation between 4.5 and 7 days could not be prevented by addition of mitotic inhibitors of gamma-irradiation. CNTF, but not NGF, slightly enhanced survival at 7 days on either PORN or LN. No neuronal losses were found in non-enriched cultures or when enriched neurons were supplemented with PBE, indicating that non-neuronal cells and PBE provide factor(s) essential for adult DRG neuron survival. Proportions of SP-, SOM-, and CCK-immunoreactive cells were unaltered under any experimental condition, with the exception of a numerical decline in SP cells in 7-day cultures with LN, but not PORN, as the substratum. Our data, considered in the context of recent in vivo and vitro studies, suggest that a combination of trophic factors or an unidentified factor, rather than the established molecules NGF, CNTF, and BDNF, which address embryonic and neonatal DRG neurons, are required for the in vitro maintenance of adult DRG neurons.

Grothe C; Unsicker K

1987-01-01

153

Biodegradation of cis-1,2-dichloroethylene and vinyl chloride in anaerobic cultures enriched from landfill leachate sediment under Fe(III)-reducing conditions.  

UK PubMed Central (United Kingdom)

An anaerobic, Fe(III)-reducing enrichment culture, which originated from a sediment sample collected at a landfill in Nanji-do, Seoul, Korea, was capable of degrading cis-1,2-dichloroethylene (cis-DCE) and vinyl chloride (VC). Although it exhibited the ability under Fe(III)-reducing conditions, the chlorinated ethenes degradation was not linked to the Fe(III) reduction. During cis-DCE degradation, no VC, ethene, or ethane was detected through the experimental period. Also, this culture did not accumulate ethene and ethane during the VC degradation. It was unlikely that cis-DCE was reductively dechlorinated to VC and then the VC formed was dechlorinated fast enough. Because the kinetic data showed that the rate of cis-DCE degradation was 3.5 times higher than that of VC. Whereas glucose supported the culture growth and the degradation, formate, acetate, butyrate, propionate, lactate, pyruvate, and yeast extract did not. The results appeared consistent with the involvement of oxidative degradation mechanism rather than reductive dechlorination mechanism. The traits of the culture described here are unusual in the anaerobic degradation of chlorinated ethenes and may be useful for searching an effective organism and mechanism regarding anaerobic cis-DCE and VC degradation.

Hata J; Takamizawa K; Miyata N; Iwahori K

2003-08-01

154

Dehalogenation of diverse halogenated substrates by a highly enriched Dehalococcoides-containing culture derived from the contaminated mega-site in Bitterfeld.  

UK PubMed Central (United Kingdom)

An enrichment culture dominated by one type of Dehalococcoides sp. (83% of clones) was characterised. This culture, originally derived from contaminated groundwater from the area of Bitterfeld-Wolfen (Saxony-Anhalt, Germany), dehalogenates chlorinated ethenes to ethene. Further, the culture also dehalogenated vinyl bromide (VB) and 1,2-dichloroethane (DCA) to ethene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzene (TeCB), penta- and hexachlorobenzene (PeCB and HCB) to trichlorobenzenes (TCB), lindane to monochlorobenzene (MCB) and pentachlorophenol (PCP) to 2,3,4,6-tetrachlorophenol (TeCP). Growth was proven by quantitative PCR for all active cultures, except for those with TeCB, lindane and PCP. The growth yields obtained ranged from (2.9 ± 0.7) × 10(7) cells ?mol(-1) Br(-) released on VB to (34.8 ± 5.4) × 10(7) cells ?mol(-1) Cl(-) released on VC. Genes coding for nine putative reductive dehalogenases, the enzymes that mediate the respiratory process of dehalogenation, were identified. Phylogenetic analysis revealed eight reductive dehalogenases with similar sequences in other Dehalococcoides strains and one unique sequence.

Kaufhold T; Schmidt M; Cichocka D; Nikolausz M; Nijenhuis I

2013-01-01

155

Dehalogenation of diverse halogenated substrates by a highly enriched Dehalococcoides-containing culture derived from the contaminated mega-site in Bitterfeld.  

Science.gov (United States)

An enrichment culture dominated by one type of Dehalococcoides sp. (83% of clones) was characterised. This culture, originally derived from contaminated groundwater from the area of Bitterfeld-Wolfen (Saxony-Anhalt, Germany), dehalogenates chlorinated ethenes to ethene. Further, the culture also dehalogenated vinyl bromide (VB) and 1,2-dichloroethane (DCA) to ethene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzene (TeCB), penta- and hexachlorobenzene (PeCB and HCB) to trichlorobenzenes (TCB), lindane to monochlorobenzene (MCB) and pentachlorophenol (PCP) to 2,3,4,6-tetrachlorophenol (TeCP). Growth was proven by quantitative PCR for all active cultures, except for those with TeCB, lindane and PCP. The growth yields obtained ranged from (2.9 ± 0.7) × 10(7) cells ?mol(-1) Br(-) released on VB to (34.8 ± 5.4) × 10(7) cells ?mol(-1) Cl(-) released on VC. Genes coding for nine putative reductive dehalogenases, the enzymes that mediate the respiratory process of dehalogenation, were identified. Phylogenetic analysis revealed eight reductive dehalogenases with similar sequences in other Dehalococcoides strains and one unique sequence. PMID:22845344

Kaufhold, Theresa; Schmidt, Marie; Cichocka, Danuta; Nikolausz, Marcell; Nijenhuis, Ivonne

2012-08-29

156

Modeling denitrifying sulfide removal process using artificial neural networks.  

UK PubMed Central (United Kingdom)

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)<7h, influent sulfide concentration markedly affects reactor performance.

Wang A; Liu C; Han H; Ren N; Lee DJ

2009-09-01

157

Relative binding and biochemical effects of heterodimeric and homodimeric isoforms of platelet-derived growth factor in osteoblast-enriched cultures from fetal rat bone  

Energy Technology Data Exchange (ETDEWEB)

Platelet-derived growth factor (PDGF) exists as a homodimer or a heterodimer comprising either PDGF-A or PDGF-B subunits, and each isoform occurs in various tissues, including bone. Although the stimulatory effects of PDGF-BB have been studied in cultures of bone cells and intact bone fragments, the influence of other isoforms that may arise locally or systematically in vivo, has not been reported. Therefore recombinant human PDGF-BB, PDGF-AB, and PDGF-AA were evaluated in osteoblast-enriched cultures from fetal rat bone. Within 24 hours these factors produced a graded response in bone cell DNA and protein synthesis, with half-maximal effects at approximately 0.6, 2.1, and 4.8 nM PDGF-BB, PDGF-AB, and PDGF-AA, respectively. Increases in collagen and noncollagen protein synthesis were abrogated when DNA synthesis was blocked with hydroxyurea. Furthermore, each factor reduced alkaline phosphatase activity, PDGF-BB being the most inhibitory. Binding studies with 125I-PDGF-BB or 125I-PDGF-AA and each unlabeled PDGF isoform produced discrete ligand binding and displacement patterns: 125I-PDGF-BB binding was preferentially displaced by PDGF-BB (Ki approximately 0.7 nM), less by PDGF-AB (Ki approximately 2.3 nM) and poorly by PDGF-AA. In contrast, 125I-PDGF-AA binding was measurably reduced by PDGF-AA (Ki approximately 4.0 nM), but was more effectively displaced by PDGF-BB or PDGF-AB (each with Ki approximately 0.7 nM). These studies indicate that each PDGF isoform produces biochemical effects proportional to binding site occupancy and suggest that receptors that favor PDGF-B subunit binding preferentially mediate these results in osteoblast-enriched bone cell cultures.

Centrella, M.; McCarthy, T.L.; Kusmik, W.F.; Canalis, E. (Department of Research, Saint Francis Hospital and Medical Center, Hartford, CT (USA))

1991-06-01

158

Relative binding and biochemical effects of heterodimeric and homodimeric isoforms of platelet-derived growth factor in osteoblast-enriched cultures from fetal rat bone  

International Nuclear Information System (INIS)

Platelet-derived growth factor (PDGF) exists as a homodimer or a heterodimer comprising either PDGF-A or PDGF-B subunits, and each isoform occurs in various tissues, including bone. Although the stimulatory effects of PDGF-BB have been studied in cultures of bone cells and intact bone fragments, the influence of other isoforms that may arise locally or systematically in vivo, has not been reported. Therefore recombinant human PDGF-BB, PDGF-AB, and PDGF-AA were evaluated in osteoblast-enriched cultures from fetal rat bone. Within 24 hours these factors produced a graded response in bone cell DNA and protein synthesis, with half-maximal effects at approximately 0.6, 2.1, and 4.8 nM PDGF-BB, PDGF-AB, and PDGF-AA, respectively. Increases in collagen and noncollagen protein synthesis were abrogated when DNA synthesis was blocked with hydroxyurea. Furthermore, each factor reduced alkaline phosphatase activity, PDGF-BB being the most inhibitory. Binding studies with 125I-PDGF-BB or 125I-PDGF-AA and each unlabeled PDGF isoform produced discrete ligand binding and displacement patterns: 125I-PDGF-BB binding was preferentially displaced by PDGF-BB (Ki approximately 0.7 nM), less by PDGF-AB (Ki approximately 2.3 nM) and poorly by PDGF-AA. In contrast, 125I-PDGF-AA binding was measurably reduced by PDGF-AA (Ki approximately 4.0 nM), but was more effectively displaced by PDGF-BB or PDGF-AB (each with Ki approximately 0.7 nM). These studies indicate that each PDGF isoform produces biochemical effects proportional to binding site occupancy and suggest that receptors that favor PDGF-B subunit binding preferentially mediate these results in osteoblast-enriched bone cell cultures

1991-01-01

159

Denitrifying bacteria anaerobically oxidize methane in the absence of Archaea.  

Science.gov (United States)

Recently, a microbial consortium was shown to couple the anaerobic oxidation of methane to denitrification, predominantly in the form of nitrite reduction to dinitrogen gas. This consortium was dominated by bacteria of an as yet uncharacterized division and archaea of the order Methanosarcinales. The present manuscript reports on the upscaling of the enrichment culture, and addresses the role of the archaea in methane oxidation. The key gene of methanotrophic and methanogenic archaea, mcrA, was sequenced. The associated cofactor F(430) was shown to have a mass of 905 Da, the same as for methanogens and different from the heavier form (951 Da) found in methanotrophic archaea. After prolonged enrichment (> 1 year), no inhibition of anaerobic methane oxidation was observed in the presence of 20 mM bromoethane sulfonate, a specific inhibitor of MCR. Optimization of the cultivation conditions led to higher rates of methane oxidation and to the decline of the archaeal population, as shown by fluorescence in situ hybridization and quantitative MALDI-TOF analysis of F(430). Mass balancing showed that methane oxidation was still coupled to nitrite reduction in the total absence of oxygen. Together, our results show that bacteria can couple the anaerobic oxidation of methane to denitrification without the involvement of Archaea. PMID:18721142

Ettwig, Katharina F; Shima, Seigo; van de Pas-Schoonen, Katinka T; Kahnt, Jörg; Medema, Marnix H; Op den Camp, Huub J M; Jetten, Mike S M; Strous, Marc

2008-08-20

160

Isotope enrichment  

International Nuclear Information System (INIS)

In this chapter of the textbook for chemists the isotope enrichment methods are overviewed. The subsections are: General characterization of the methods used for isotope enrichment, Distillation and chemical exchange, Electrochemical methods, Diffusion methods, Isotope enrichment through centrifugation, Single-stage methods, Cascades.

1987-01-01

 
 
 
 
161

Comparative analysis of tertiary alcohol esterase activity in bacterial strains isolated from enrichment cultures and from screening strain libraries.  

UK PubMed Central (United Kingdom)

The preparation of enantiopure tertiary alcohols is of great contemporary interest due to the application of these versatile building blocks in organic synthesis and as precursors towards high value pharmaceutical compounds. Herein, we describe two approaches taken towards the discovery of novel biocatalysts for the synthesis of these valuable compounds. The first approach was initiated with screening of 47 bacterial strains for hydrolytic activity towards the simple tertiary alcohol ester tert-butyl acetate. In conjunction, a second method focussed on the isolation of strains competent for growth on tert-butyl acetate as the sole source of carbon and energy. From functional screening, 10 Gram-positive Actinomycetes showed hydrolytic activity, whilst enrichment selection resulted in the identification of 14 active strains, of which five belong to the Gram-negative cell-wall type. Bacterial strains obtained from both approaches were viable for enantioselective hydrolysis of pyridine substituted tertiary alcohol esters in addition to bulky aliphatic and keto-derived substrates from the same class. Activity towards each of the test substrates was uncovered, with promising enantioselectivities of up to E = 71 in the hydrolysis of a para-substituted pyridine tertiary alcohol ester using a strain of Rhodococcus ruber. Interestingly strains of Microbacterium and Alcaligenes sp. gave opposite enantiopreference in the hydrolysis of a meta-substituted pyridine tertiary alcohol ester with E values of 17 and 54. These approaches show that via both possibilities, screening established strain collections and performing enrichment selection, it is possible to identify novel species which show activity towards sterically challenging substrates.

Herter S; Nguyen GS; Thompson ML; Steffen-Munsberg F; Schauer F; Bornscheuer UT; Kourist R

2011-05-01

162

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)

2008-09-00

163

Identification of Staphylococcus aureus from enriched nasal swabs within 24 h is improved with use of multiple culture media.  

UK PubMed Central (United Kingdom)

Nasal carriage of Staphylococcus aureus is commonly evaluated via culture-based methods. We found that parallel use of two media, Baird-Parker and CHROMagar™ Staph aureus, increased detection of S. aureus from a healthy population by 29?%. We suggest use of both media for optimal identification of S. aureus from healthy cohorts.

Nadimpalli M; Heaney C; Stewart JR

2013-09-01

164

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

165

Comparative analysis of 16S rRNA and amoA genes from archaea selected with organic and inorganic amendments in enrichment culture.  

UK PubMed Central (United Kingdom)

We took advantage of a plant-root enrichment culture system to characterize mesophilic soil archaea selected through the use of organic and inorganic amendments. Comparative analysis of 16S rRNA and amoA genes indicated that specific archaeal clades were selected under different conditions. Three amoA sequence clades were identified, while for a fourth group, identified by 16S rRNA gene analysis alone and referred to as the "root" clade, we detected no corresponding amoA gene. The amoA-containing archaea were present in media with either organic or inorganic amendments, whereas archaea representing the root clade were present only when organic amendment was used. Analysis of amoA gene abundance and expression, together with nitrification-coupled growth assays, indicated potential growth by autotrophic ammonia oxidation for members of two group 1.1b clades. Increased abundance of one of these clades, however, also occurred upon the addition of organic amendment. Finally, although amoA-containing group 1.1a archaea were present in enrichments, we detected neither expression of amoA genes nor evidence for nitrification-coupled growth of these organisms. These data support a model of a diverse metabolic community in mesophilic soil archaea that is just beginning to be characterized.

Xu M; Schnorr J; Keibler B; Simon HM

2012-04-01

166

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

UK PubMed Central (United Kingdom)

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 DJ; Lee CY; Chang JS

2012-12-01

167

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; Suaad E.H. Adam; Misa Takahashi; Atsushi Sakamoto; Hirofumi Shoun; Hiromichi Morikawa

2008-01-01

168

Identification of bacteria in enrichment cultures of sulfate reducers in the Cariaco Basin water column employing Denaturing Gradient Gel Electrophoresis of 16S ribosomal RNA gene fragments.  

UK PubMed Central (United Kingdom)

BACKGROUND: The Cariaco Basin is characterized by pronounced and predictable vertical layering of microbial communities dominated by reduced sulfur species at and below the redox transition zone. Marine water samples were collected in May, 2005 and 2006, at the sampling stations A (10[degree sign]30[prime] N, 64[degree sign]40[prime] W), B (10[degree sign]40[prime] N, 64[degree sign]45[prime] W) and D (10o43'N, 64o32'W) from different depths, including surface, redox interface, and anoxic zones. In order to enrich for sulfate reducing bacteria (SRB), water samples were inoculated into anaerobic media amended with lactate or acetate as carbon source. To analyze the composition of enrichment cultures, we performed DNA extraction, PCR-DGGE, and sequencing of selected bands. RESULTS: DGGE results indicate that many bacterial genera were present that are associated with the sulfur cycle, including Desulfovibrio spp., as well as heterotrophs belonging to Vibrio, Enterobacter, Shewanella, Fusobacterium, Marinifilum, Mariniliabilia, and Spirochaeta. These bacterial populations are related to sulfur coupling and carbon cycles in an environment of variable redox conditions and oxygen availability. CONCLUSIONS: In our studies, we found an association of SRB-like Desulfovibrio with Vibrio species and other genera that have a previously defined relevant role in sulfur transformation and coupling of carbon and sulfur cycles in an environment where there are variable redox conditions and oxygen availability. This study provides new information about microbial species that were culturable on media for SRB at anaerobic conditions at several locations and water depths in the Cariaco Basin.

Bozo-Hurtado L; García-Amado MA; Chistoserdov A; Varela R; Narvaez JJ; Colwell R; Suárez P

2013-08-01

169

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

Energy Technology Data Exchange (ETDEWEB)

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 activities of microorganisms that degrade alkylbenzenes under denitrifying conditions may be suppressed if the standard acetylene block technique is used to verify denitrifying activity.

Hutchins, S.R. (U.S. Environmental Protection Agency, Ada, OK (United States))

1992-10-01

170

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

International Nuclear Information System (INIS)

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

2010-07-15

171

Enrichment and Molecular Detection of Denitrifying Methanotrophic Bacteria of the NC10 Phylum?  

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Anaerobic methane oxidation coupled to denitrification was recently assigned to bacteria belonging to the uncultured phylum NC10. In this study, we incubated sediment from a eutrophic ditch harboring a diverse community of NC10 bacteria in a bioreactor with a constant supply of methane and nitrite. ...

Ettwig, Katharina F.; van Alen, Theo; van de Pas-Schoonen, Katinka T.; Jetten, Mike S. M.; Strous, Marc

172

Pandoraea oxalativorans sp. nov., Pandoraea faecigallinarum sp. nov. and Pandoraea vervacti sp. nov., isolated from oxalate-enriched culture.  

Science.gov (United States)

Five isolates, designated TA2, TA4, TA25(T), KOx(T) and NS15(T) were isolated in previous studies by enrichment in mineral medium with potassium oxalate as the sole carbon source and were characterized using a polyphasic approach. The isolates were Gram-reaction-negative, aerobic, non-spore-forming rods. Phylogenetic analyses based on 16S rRNA and DNA gyrase B subunit (gyrB) gene sequences confirmed that the isolates belonged to the genus Pandoraea and were most closely related to Pandoraea sputorum and Pandoraea pnomenusa (97.2-99.7?% 16S rRNA gene sequence similarity). The isolates could be differentiated from their closest relatives on the basis of several phenotypic characteristics. The major cellular fatty acid profiles of the isolates comprised C??:?, C??:??7c, C??:? cyclo and summed feature 3 (C??:??7c and/or iso-C??:? 2-OH). On the basis of DNA-DNA hybridization studies and phylogenetic analyses, the isolates represent three novel species within the genus Pandoraea, for which the names Pandoraea oxalativorans sp. nov. (TA25(T) ?=?NBRC 106091(T) ?=?CCM 7677(T) ?=?DSM 23570(T)), Pandoraea faecigallinarum sp. nov. (KOx(T) ?=?NBRC 106092(T) ?=?CCM 2766(T) ?=?DSM 23572(T)) and Pandoraea vervacti sp. nov. (NS15(T) ?=?NBRC 106088(T) ?=?CCM 7667(T) ?=?DSM 23571(T)) are proposed. PMID:20952546

Sahin, Nurettin; Tani, Akio; Kotan, Recep; Sedlácek, Ivo; Kimbara, Kazuhide; Tamer, Abdurrahman U

2010-10-15

173

Pandoraea oxalativorans sp. nov., Pandoraea faecigallinarum sp. nov. and Pandoraea vervacti sp. nov., isolated from oxalate-enriched culture.  

UK PubMed Central (United Kingdom)

Five isolates, designated TA2, TA4, TA25(T), KOx(T) and NS15(T) were isolated in previous studies by enrichment in mineral medium with potassium oxalate as the sole carbon source and were characterized using a polyphasic approach. The isolates were Gram-reaction-negative, aerobic, non-spore-forming rods. Phylogenetic analyses based on 16S rRNA and DNA gyrase B subunit (gyrB) gene sequences confirmed that the isolates belonged to the genus Pandoraea and were most closely related to Pandoraea sputorum and Pandoraea pnomenusa (97.2-99.7?% 16S rRNA gene sequence similarity). The isolates could be differentiated from their closest relatives on the basis of several phenotypic characteristics. The major cellular fatty acid profiles of the isolates comprised C??:?, C??:??7c, C??:? cyclo and summed feature 3 (C??:??7c and/or iso-C??:? 2-OH). On the basis of DNA-DNA hybridization studies and phylogenetic analyses, the isolates represent three novel species within the genus Pandoraea, for which the names Pandoraea oxalativorans sp. nov. (TA25(T) ?=?NBRC 106091(T) ?=?CCM 7677(T) ?=?DSM 23570(T)), Pandoraea faecigallinarum sp. nov. (KOx(T) ?=?NBRC 106092(T) ?=?CCM 2766(T) ?=?DSM 23572(T)) and Pandoraea vervacti sp. nov. (NS15(T) ?=?NBRC 106088(T) ?=?CCM 7667(T) ?=?DSM 23571(T)) are proposed.

Sahin N; Tani A; Kotan R; Sedlácek I; Kimbara K; Tamer AU

2011-09-01

174

Serial enrichment of spermatogonial stem and progenitor cells (SSCs) in culture for derivation of long-term adult mouse SSC lines.  

UK PubMed Central (United Kingdom)

Spermatogonial stem and progenitor cells (SSCs) of the testis represent a classic example of adult mammalian stem cells and preserve fertility for nearly the lifetime of the animal. While the precise mechanisms that govern self-renewal and differentiation in vivo are challenging to study, various systems have been developed previously to propagate murine SSCs in vitro using a combination of specialized culture media and feeder cells(1-3). Most in vitro forays into the biology of SSCs have derived cell lines from neonates, possibly due to the difficulty in obtaining adult cell lines(4). However, the testis continues to mature up until ~5 weeks of age in most mouse strains. In the early post-natal period, dramatic changes occur in the architecture of the testis and in the biology of both somatic and spermatogenic cells, including alterations in expression levels of numerous stem cell-related genes. Therefore, neonatally-derived SSC lines may not fully recapitulate the biology of adult SSCs that persist after the adult testis has reached a steady state. Several factors have hindered the production of adult SSC lines historically. First, the proportion of functional stem cells may decrease during adulthood, either due to intrinsic or extrinsic factors(5,6). Furthermore, as with other adult stem cells, it has been difficult to enrich SSCs sufficiently from total adult testicular cells without using a combination of immunoselection or other sorting strategies(7). Commonly employed strategies include the use of cryptorchid mice as a source of donor cells due to a higher ratio of stem cells to other cell types(8). Based on the hypothesis that removal of somatic cells from the initial culture disrupts interactions with the stem cell niche that are essential for SSC survival, we previously developed methods to derive adult lines that do not require immunoselection or cryptorchid donors but rather employ serial enrichment of SSCs in culture, referred to hereafter as SESC(2,3). The method described below entails a simple procedure for deriving adult SSC lines by dissociating adult donor seminiferous tubules, followed by plating of cells on feeders comprised of a testicular stromal cell line (JK1)(3). Through serial passaging, strongly adherent, contaminating non-germ cells are depleted from the culture with concomitant enrichment of SSCs. Cultures produced in this manner contain a mixture of spermatogonia at different stages of differentiation, which contain SSCs, based on long-term self renewal capability. The crux of the SESC method is that it enables SSCs to make the difficult transition from self-renewal in vivo to long-term self-renewal in vitro in a radically different microenvironment, produces long-term SSC lines, free of contaminating somatic cells, and thereby enables subsequent experimental manipulation of SSCs.

Martin LA; Seandel M

2013-01-01

175

Serial enrichment of spermatogonial stem and progenitor cells (SSCs) in culture for derivation of long-term adult mouse SSC lines.  

Science.gov (United States)

Spermatogonial stem and progenitor cells (SSCs) of the testis represent a classic example of adult mammalian stem cells and preserve fertility for nearly the lifetime of the animal. While the precise mechanisms that govern self-renewal and differentiation in vivo are challenging to study, various systems have been developed previously to propagate murine SSCs in vitro using a combination of specialized culture media and feeder cells(1-3). Most in vitro forays into the biology of SSCs have derived cell lines from neonates, possibly due to the difficulty in obtaining adult cell lines(4). However, the testis continues to mature up until ~5 weeks of age in most mouse strains. In the early post-natal period, dramatic changes occur in the architecture of the testis and in the biology of both somatic and spermatogenic cells, including alterations in expression levels of numerous stem cell-related genes. Therefore, neonatally-derived SSC lines may not fully recapitulate the biology of adult SSCs that persist after the adult testis has reached a steady state. Several factors have hindered the production of adult SSC lines historically. First, the proportion of functional stem cells may decrease during adulthood, either due to intrinsic or extrinsic factors(5,6). Furthermore, as with other adult stem cells, it has been difficult to enrich SSCs sufficiently from total adult testicular cells without using a combination of immunoselection or other sorting strategies(7). Commonly employed strategies include the use of cryptorchid mice as a source of donor cells due to a higher ratio of stem cells to other cell types(8). Based on the hypothesis that removal of somatic cells from the initial culture disrupts interactions with the stem cell niche that are essential for SSC survival, we previously developed methods to derive adult lines that do not require immunoselection or cryptorchid donors but rather employ serial enrichment of SSCs in culture, referred to hereafter as SESC(2,3). The method described below entails a simple procedure for deriving adult SSC lines by dissociating adult donor seminiferous tubules, followed by plating of cells on feeders comprised of a testicular stromal cell line (JK1)(3). Through serial passaging, strongly adherent, contaminating non-germ cells are depleted from the culture with concomitant enrichment of SSCs. Cultures produced in this manner contain a mixture of spermatogonia at different stages of differentiation, which contain SSCs, based on long-term self renewal capability. The crux of the SESC method is that it enables SSCs to make the difficult transition from self-renewal in vivo to long-term self-renewal in vitro in a radically different microenvironment, produces long-term SSC lines, free of contaminating somatic cells, and thereby enables subsequent experimental manipulation of SSCs. PMID:23462452

Martin, Laura A; Seandel, Marco

2013-02-25

176

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

International Nuclear Information System (INIS)

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

2010-01-01

177

A simple method to quickly and simultaneously purify and enrich intact rat brain microcapillaries and endothelial and glial cells for ex vivo studies and cell culture.  

Science.gov (United States)

The blood-brain barrier is morphologically composed of cerebral microcapillary endothelium through its tight junctions. It serves as a mechanical, metabolic and cellular barrier and can also protect the brain from pathogen invasion. Many brain diseases involve a disturbance of blood-brain barrier function either as a consequence of a noxa or as primary failure. In vitro models of the blood-brain barrier are suitable tools to study drug transport, pathogen transmigration and leukocyte diapedesis across the cerebral endothelium. Such models have previously been derived mainly from porcine or bovine brain tissues. We describe here a simple method by which rat cerebral microcapillaries and cells of glial origin can be quickly and simultaneously purified. By using a capillary fragment size restriction method based on glass bead columns different fractions can be separated: vital, long capillary fragments for ex vivo uptake studies and smaller capillary fragments for endothelial culture. Furthermore, fractions can be obtained for astroglial and oligodendroglial cell cultures. With this method both microcapillary enrichment and glial cell purification are quickly achieved, which reduces expenditure, number of required animals and laboratory working time. PMID:23665392

Lenhard, Thorsten; Hülsermann, Uta; Martinez-Torres, Francisco; Fricker, Gert; Meyding-Lamadé, Uta

2013-05-09

178

Effect of prefermentation on denitrifying phosphorus removal in slaughterhouse wastewater.  

Science.gov (United States)

An anaerobic-anoxic sequencing batch reactor (A2 SBR) coupled with a fixed-bed nitrification reactor for simultaneous carbon, nitrogen and phosphorus removal was evaluated using slaughterhouse wastewater. Whereas the treatment could not be successfully carried out on the raw wastewater, the process showed very good nutrient removal performances after prefermentation. The removals of COD, N-NH4 and P-PO4 achieved were 99%, 85% and 99%, respectively. The increase in volatile fatty acid (VFA) and phosphate concentrations in the effluent after prefermentation may explain the high levels of biological carbon, nitrogen and phosphorus removal observed. A simple prefermentation is, therefore, necessary but sufficient to ensure good performances of the denitrifying enhanced biological phosphorus removal (EBPR) process. PMID:15792577

Merzouki, M; Bernet, N; Delgenès, J P; Benlemlih, M

2005-01-20

179

Effect of prefermentation on denitrifying phosphorus removal in slaughterhouse wastewater.  

UK PubMed Central (United Kingdom)

An anaerobic-anoxic sequencing batch reactor (A2 SBR) coupled with a fixed-bed nitrification reactor for simultaneous carbon, nitrogen and phosphorus removal was evaluated using slaughterhouse wastewater. Whereas the treatment could not be successfully carried out on the raw wastewater, the process showed very good nutrient removal performances after prefermentation. The removals of COD, N-NH4 and P-PO4 achieved were 99%, 85% and 99%, respectively. The increase in volatile fatty acid (VFA) and phosphate concentrations in the effluent after prefermentation may explain the high levels of biological carbon, nitrogen and phosphorus removal observed. A simple prefermentation is, therefore, necessary but sufficient to ensure good performances of the denitrifying enhanced biological phosphorus removal (EBPR) process.

Merzouki M; Bernet N; Delgenès JP; Benlemlih M

2005-08-01

180

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...

 
 
 
 
181

Physical characteristics and formation mechanism of denitrifying granular sludge in high-load reactor.  

UK PubMed Central (United Kingdom)

The physical characteristics of denitrifying granular sludge and their granulation mechanism were investigated in two denitrifying reactors (R1 and R2). The results showed that the denitrifying granular sludge was streamlined in shape with the aspect ratio (AR) of 0.62 ± 0.05, large in size with the diameter of 2.39 ± 0.05 mm, and fast in settlement with the average settling velocity (VS) of 126.36 ± 13.32 m/h at the nitrate loading rate (NLR) of 35.14 ± 0.38 kg/(m(3)d). The dominance of denitrifying granular sludge with good settleability was attributed to the enhanced growth of granular sludge by extracellular polymers (EPS) and the shaping of granular sludge by shear force.

Li W; Zheng P; Wang L; Zhang M; Lu H; Xing Y; Zhang J; Wang R; Song J; Ghulam A

2013-08-01

182

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

Directory of Open Access Journals (Sweden)

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

D. Munsel; U. Kramar; D. Dissard; G. Nehrke; Z. Berner; J. Bijma; G.-J. Reichart; T. Neumann

2010-01-01

183

Spatial Variation in the Bacterial and Denitrifying Bacterial Community in a Biofilter Treating Subsurface Agricultural Drainage.  

UK PubMed Central (United Kingdom)

Denitrifying biofilters can remove agricultural nitrates from subsurface drainage, reducing nitrate pollution that contributes to coastal hypoxic zones. The performance and reliability of natural and engineered systems dependent upon microbially mediated processes, such as the denitrifying biofilters, can be affected by the spatial structure of their microbial communities. Furthermore, our understanding of the relationship between microbial community composition and function is influenced by the spatial distribution of samples. In this study we characterized the spatial structure of bacterial communities in a denitrifying biofilter in central Illinois. Bacterial communities were assessed using automated ribosomal intergenic spacer analysis for bacteria and terminal restriction fragment length polymorphism of nosZ for denitrifying bacteria. Non-metric multidimensional scaling and analysis of similarity (ANOSIM) analyses indicated that bacteria showed statistically significant spatial structure by depth and transect, while denitrifying bacteria did not exhibit significant spatial structure. For determination of spatial patterns, we developed a package of automated functions for the R statistical environment that allows directional analysis of microbial community composition data using either ANOSIM or Mantel statistics. Applying this package to the biofilter data, the flow path correlation range for the bacterial community was 6.4 m at the shallower, periodically inundated depth and 10.7 m at the deeper, continually submerged depth. These spatial structures suggest a strong influence of hydrology on the microbial community composition in these denitrifying biofilters. Understanding such spatial structure can also guide optimal sample collection strategies for microbial community analyses.

Andrus JM; Porter MD; Rodríguez LF; Kuehlhorn T; Cooke RA; Zhang Y; Kent AD; Zilles JL

2013-09-01

184

Aerobic and anaerobic degradation of a range of alkyl sulfides by a denitrifying marine bacterium  

Science.gov (United States)

A pure culture of a bacterium was obtained from a marine microbial mat by using an anoxic medium containing dimethyl sulfide (DMS) and nitrate. The isolate grew aerobically or anaerobically as a denitrifier on alkyl sulfides, including DMS, dimethyl disulfide, diethyl sulfide (DES), ethyl methyl sulfide, dipropyl sulfide, dibutyl sulfide, and dibutyl disulfide. Cells grown on an alkyl sulfide or disulfide also oxidized the corresponding thiols, namely, methanethiol, ethanethiol, propanethiol, or butanethiol. Alkyl sulfides were metabolized by induced or derepressed cells with oxygen, nitrate, or nitrite as electron acceptor. Cells grown on DMS immediately metabolized DMS, but there was a lag before DES was consumed; with DES-grown cells, DES was immediately used but DMS was used only after a lag. Chloramphenicol prevented the eventual use of DES by DMS-grown cells and DMS use by DES-grown cells, respectively, indicating separate enzymes for the metabolism of methyl and ethyl groups. Growth was rapid on formate, acetate, propionate, and butyrate but slow on methanol. The organism also grew chemolithotrophically on thiosulfate with a decrease in pH; growth required carbonate in the medium. Growth on sulfide was also carbonate dependent but slow. The isolate was identified as a Thiobacillus sp. and designated strain ASN-1. It may have utility for removing alkyl sulfides, and also nitrate, nitrite, and sulfide, from wastewaters.

Visscher, P. T.; Taylor, B. F.

1993-01-01

185

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

UK PubMed Central (United Kingdom)

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 21days) 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.

Boulêtreau S; Lyautey E; Dubois S; Compin A; Delattre C; Touron-Bodilis A; Mastrorillo S; Garabetian F

2013-08-01

186

Application potential of a newly isolated indigenous aerobic denitrifier for nitrate and ammonium removal of eutrophic lake water.  

UK PubMed Central (United Kingdom)

The aim of this work was to evaluate the utilization potential of a newly isolated indigenous aerobic denitrifier, Pseudomonas stutzeri strain T1, for nitrogen removal from the eutrophic Lake Taihu in China. The strain was capable of conducting heterotrophic nitrification-aerobic denitrification and had both excellent nitrate and ammonium removal without nitrite build-up. The characteristics of P. stutzeri strain T1 were studied under different cultural conditions. Furthermore, under the optimized cultivation conditions, strain T1 was added into the water samples from Lake Taihu, the ammonium and nitrate removal rates of the strain reached to 60% and 75%, respectively. Via adding this strain, the water qualities of the sample ameliorated from Grade V to Grade II. Thus, the strain T1 should be an useful biological tool to remediate eutrophic lakes and do not meet acclimation problems.

Guo L; Chen Q; Fang F; Hu Z; Wu J; Miao A; Xiao L; Chen X; Yang L

2013-08-01

187

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

188

Enrichment availability  

International Nuclear Information System (INIS)

[en] Within the overall scope of INFCE, Working Group 2, devoted to uranium enrichment, was mandated to study the following six subjects: (1) Enrichment needs and availability according to various fuel cycle strategies: joint planning of future capacities; opportunities for cross-investment; freedom of choice for customers in an open market. (2) Technical and economic assessment of the different enrichment technologies. (3) Assessment and comparison of the proliferation risks of the various enrichment techniques. (4) Safeguards aspects specific to enrichment. (5) Multinational or regional fuel cycle centres or similar arrangements. (6) Special needs of developing countries. To carry out some of these tasks, Working Group 2 created two subgroups: WG 2A for the assessment of the enrichment needs; WG 2B for dealing with the technical, economic, commercial, safeguards and non-proliferation aspects of enrichment. Sub-group 2A, working jointly with subgroup 1A of Working Group 1 on account of their common preliminary objective of reviewing existing nuclear power forecasts, chose to solicit, through a questionnaire, new national data on primary energy, electrical energy and nuclear power growth estimates for all nations up to the year 2025, to be used as a base for the forecast of world-wide natural uranium and separative work demand

1980-01-01

189

Combined extrinsic and intrinsic manipulations exert complementary neuronal enrichment in embryonic rat neural precursor cultures: an in vitro and in vivo analysis.  

Science.gov (United States)

Numerous central nervous system (CNS) disorders share a common pathology in dysregulation of gamma-aminobutyric acid (GABA) inhibitory signaling. Transplantation of GABA-releasing cells at the site of disinhibition holds promise for alleviating disease symptoms with fewer side effects than traditional drug therapies. We manipulated fibroblast growth factor (FGF)-2 deprivation and mammalian achaete-scute homolog (MASH)1 transcription factor levels in an attempt to amplify the default GABAergic neuronal fate in cultured rat embryonic neural precursor cells (NPCs) for use in transplantation studies. Naïve and MASH1 lentivirus-transduced NPCs were maintained in FGF-2 or deprived of FGF-2 for varying lengths of time. Immunostaining and quantitative analysis showed that GABA- and beta-III-tubulin-immunoreactive cells generally decreased through successive passages, suggesting a loss of neurogenic potential in rat neurospheres expanded in vitro. However, FGF-2 deprivation resulted in a small, but significantly increased population of GABAergic cells derived from passaged neurospheres. In contrast to naïve and GFP lentivirus-transduced clones, MASH1 transduction resulted in increased bromodeoxyuridine (BrdU) incorporation and clonal colony size. Western blotting showed that MASH1 overexpression and FGF-2 deprivation additively increased beta-III-tubulin and decreased cyclic nucleotide phosphodiesterase (CNPase) expression, whereas FGF-2 deprivation alone attenuated glial fibrillary acidic protein (GFAP) expression. These results suggest that low FGF-2 signaling and MASH1 activity can operate in concert to enrich NPC cultures for a GABA neuronal phenotype. When transplanted into the adult rat spinal cord, this combination also yielded GABAergic neurons. These findings indicate that, even for successful utilization of the default GABAergic neuronal precursor fate, a combination of both extrinsic and intrinsic manipulations will likely be necessary to realize the full potential of NSC grafts in restoring function. PMID:19399893

Furmanski, Orion; Gajavelli, Shyam; Lee, Jeung Woon; Collado, Maria E; Jergova, Stanislava; Sagen, Jacqueline

2009-07-01

190

Combined extrinsic and intrinsic manipulations exert complementary neuronal enrichment in embryonic rat neural precursor cultures: an in vitro and in vivo analysis.  

UK PubMed Central (United Kingdom)

Numerous central nervous system (CNS) disorders share a common pathology in dysregulation of gamma-aminobutyric acid (GABA) inhibitory signaling. Transplantation of GABA-releasing cells at the site of disinhibition holds promise for alleviating disease symptoms with fewer side effects than traditional drug therapies. We manipulated fibroblast growth factor (FGF)-2 deprivation and mammalian achaete-scute homolog (MASH)1 transcription factor levels in an attempt to amplify the default GABAergic neuronal fate in cultured rat embryonic neural precursor cells (NPCs) for use in transplantation studies. Naïve and MASH1 lentivirus-transduced NPCs were maintained in FGF-2 or deprived of FGF-2 for varying lengths of time. Immunostaining and quantitative analysis showed that GABA- and beta-III-tubulin-immunoreactive cells generally decreased through successive passages, suggesting a loss of neurogenic potential in rat neurospheres expanded in vitro. However, FGF-2 deprivation resulted in a small, but significantly increased population of GABAergic cells derived from passaged neurospheres. In contrast to naïve and GFP lentivirus-transduced clones, MASH1 transduction resulted in increased bromodeoxyuridine (BrdU) incorporation and clonal colony size. Western blotting showed that MASH1 overexpression and FGF-2 deprivation additively increased beta-III-tubulin and decreased cyclic nucleotide phosphodiesterase (CNPase) expression, whereas FGF-2 deprivation alone attenuated glial fibrillary acidic protein (GFAP) expression. These results suggest that low FGF-2 signaling and MASH1 activity can operate in concert to enrich NPC cultures for a GABA neuronal phenotype. When transplanted into the adult rat spinal cord, this combination also yielded GABAergic neurons. These findings indicate that, even for successful utilization of the default GABAergic neuronal precursor fate, a combination of both extrinsic and intrinsic manipulations will likely be necessary to realize the full potential of NSC grafts in restoring function.

Furmanski O; Gajavelli S; Lee JW; Collado ME; Jergova S; Sagen J

2009-07-01

191

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.

2007-02-09

192

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

Energy Technology Data Exchange (ETDEWEB)

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 IC{sub 50} values, was Cu, Te > Cd > Fe, Co, Mn > F, Se > Ni, Al, Li > Zn.

Azabou, Samia [Laboratoire des Bioprocedes, Centre de Biotechnologie de Sfax, BP ' K' , 3038 Sfax (Tunisia); Mechichi, Tahar [Laboratoire des Bioprocedes, Centre de Biotechnologie de Sfax, BP ' K' , 3038 Sfax (Tunisia)]. E-mail: mechichi.tahar@cbs.rnrt.tn; Patel, Bharat K.C. [Microbial Gene Research and Resources Facility, School of Biomolecular and Biomedical Sciences, Faculty of Science, Griffith University, Brisbane, Queensland 4111 (Australia); Eskitis Institute, Griffith University, Brisbane, Queensland 4111 (Australia); Sayadi, Sami [Laboratoire des Bioprocedes, Centre de Biotechnologie de Sfax, BP ' K' , 3038 Sfax (Tunisia)

2007-02-09

193

Contrasting denitrifier communities relate to contrasting N2O emission patterns from acidic peat soils in arctic tundra.  

UK PubMed Central (United Kingdom)

Cryoturbated peat circles (that is, bare surface soil mixed by frost action; pH 3-4) in the Russian discontinuous permafrost tundra are nitrate-rich 'hotspots' of nitrous oxide (N(2)O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N(2)O was produced and subsequently consumed at pH 4 in unsupplemented anoxic microcosms with cryoturbated but not in those with unturbated peat soil. Nitrate, nitrite and acetylene stimulated net N(2)O production of both soils in anoxic microcosms, indicating denitrification as the source of N(2)O. Up to 500 and 10??M nitrate stimulated denitrification in cryoturbated and unturbated peat soils, respectively. Apparent maximal reaction velocities of nitrite-dependent denitrification were 28 and 18?nmol N(2)O?g(DW)(-1)?h(-1), for cryoturbated and unturbated peat soils, respectively. Barcoded amplicon pyrosequencing of narG, nirK/nirS and nosZ (encoding nitrate, nitrite and N(2)O reductases, respectively) yielded ?49?000 quality-filtered sequences with an average sequence length of 444?bp. Up to 19 species-level operational taxonomic units were detected per soil and gene, many of which were distantly related to cultured denitrifiers or environmental sequences. Denitrification-associated gene diversity in cryoturbated and in unturbated peat soils differed. Quantitative PCR (inhibition-corrected per DNA extract) revealed higher copy numbers of narG in cryoturbated than in unturbated peat soil. Copy numbers of nirS were up to 1000 × higher than those of nirK in both soils, and nirS nirK(-1) copy number ratios in cryoturbated and unturbated peat soils differed. The collective data indicate that the contrasting N(2)O emission patterns of cryoturbated and unturbated peat soils are associated with contrasting denitrifier communities.

Palmer K; Biasi C; Horn MA

2012-05-01

194

Studies on the enrichment culture of hydrocarbon oxidizing bacteria for MEOR. 1st Report. ; Development of cultures and screening. Sekiyu no zoukaishu wo mokuteki toshita tankasuiso riyo kin no shuseki baiyo ni kansuru kenkyu. Dai ippo. ; Tankasuiso riyo kin no tansaku taisha kino ni yoru screening  

Energy Technology Data Exchange (ETDEWEB)

Screening based on culture development and metabolism of hydrocarbon oxidizing bacteria was carried out for 49 samples collected from agricultural fields, oil fields and small rivers running through cities. As a result, 41 out of 49 samples cultivated enrichment cultures are increased with the use of kerosene as substrates. When culture is carried out at 50{degree}C, 3 types have grown out of which two cultures are due to the direct source of oil stratum water. As the influence of salinity on culture, no growth has been found at more than 5% NaCl, however at 2 % salinity 8 out of 9 cultures have grown. In case of culture where kerosene based bacteria have grown, metabolism( value of pH of the culture solution) and oil-water interfacial tension after 7days from the start of the culture are measured. The decrease of the interfacial tension as well as the selection of the enriched culture that are possible to be used for oil recovery are described. 6 refs., 11 tabs.

Kishita, A. (Nippon Steel Corp., Tokyo (Japan)); Enomoto, H.; Kounosu, A.; Chida, T. (Tohoku Univ., Sendai (Japan). Faculty of Engineering)

1992-03-01

195

Concurrent activity of anammox and denitrifying bacteria in the Black Sea  

Science.gov (United States)

After the discovery of ANaerobic AMMonium OXidation (anammox) in the environment, the role of heterotrophic denitrification as the main marine pathway for fixed N loss has been questioned. A 3 part, 15 month time series investigating nitrite reductase (nirS) mRNA transcripts at a single location in the Black Sea 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, differed in that only expression of denitrification-type nirS was seen in the upper suboxic zone, where geochemistry was 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 16 S rDNA gene profiles. By contrast, denitrifier-type nirS sequence groups were mixed; some groups exhibited consistent expression in the lower suboxic zone, while others appeared less consistent. 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). Six major groups of denitrifier-type nirS transcripts were identified, and 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 a small increase in mixed layer net community productivity (NCP) as measured by O2/Ar gas ratios, as well as to an increase in N2 concentrations in the suboxic zone. Taken together, the variations in expression patterns between anammox and denitrification provide one possible explanation as to how near instantaneous rate measurements, such as isotope spike experiments, may regularly detect anammox activity but underreport denitrification.

Kirkpatrick, John B.; Fuchsman, Clara A.; Yakushev, Evgeniy; Staley, James T.; Murray, James W.

2012-01-01

196

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

International Nuclear Information System (INIS)

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

1000-01-00

197

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

Energy Technology Data Exchange (ETDEWEB)

Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene to a series of concentrations (0-500 mg kg{sup -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 EC{sub 50} 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 EC{sub 50} concentration of pyrene, denitrifiers diversity decreased and community composition changed in comparison with the control. Phylogenetic analyses of three genes showed that the addition of pyrene increased the proportion of Bradyrhizobiaceae, Rhodospirillales, Burkholderiales and Pseudomonadales. Some species belonging to these groups were reported to be able to degrade PAHs. - Highlights: > Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene. > PDA was positively correlated with the abundance of denitrifiers harboring nirK, nirS or nosZ gene. > Both PDA and the abundance of denitrifiers were negatively correlated with pyrene concentrations. > Denitrifiers harboring nirk, nirS or nosZ gene are more sensitive to pyrene than PDA in soils. - Denitrifiers harboring nirK, nirS or nosZ gene are more sensitive to pyrene contamination than potential denitrification activity in soils.

Guo Guangxia; Deng Huan; Qiao Min; Mu Yujing [State Key Lab of Regional and Urban Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Zhu Yongguan, E-mail: ygzhu@rcees.ac.cn [State Key Lab of Regional and Urban Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)

2011-07-15

198

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

199

Uranium enrichment  

International Nuclear Information System (INIS)

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

1991-01-01

200

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two upflow anaerobic sludge blanket (UASB) reactors were operated to investigate the fate of aromatic amines under denitrifying conditions. The feed consisted of synthetic wastewater containing aniline and/or sulfanilic acid and a mixture of volatile fatty acids (VFA) as the primary electron donors....

Pereira, Raquel; Pereira, Luciana; Van der Zee, F. P.; Alves, M. M.

 
 
 
 
201

Detection and diversity of nitrifying and denitrifying functional genes in coastal aquaculture  

UK PubMed Central (United Kingdom)

Nucleic acid methods based on sequencing of clone libraries provide sequence and the phylogenetic information of an individual clone. In the present study, ammonia monooxygenase (amoA), nitrite-oxido-reductase(norB), nitrite reductase (nirS) and nitrous oxide reductase (nosZ) genes are chosen to detect nitrifiers and denitrifiers in coastal aquaculture using gene-specific primers. The abundance of these functional genes revealed the presence of nitrifying and denitrifying organisms in coastal aquaculture. Nitrifying and denitrifying communities were analyzed by parallel DNA extractions and clone library construction for amoA, norB, nirS and nosZ obtained from coastal aquaculture soil. Amino acids in parts of the amoA, norB, nirS and nosZ encoded proteins were aligned to know conserved amino acid residues. The amoA genes exhibited 81-82% identity to Nitrosomonas europaea, Nitrosococcus mobilis and Nitrosomonas eutropha which were also similar to particulate methane monooxygenase (pmoA) gene sequences. The norB genes are closely affiliated with Nitrobacter winogradskyi and other uncultured beta-proteobacteria. The nosZ genes exhibited 78-82% identity with Marinobacter sp. and other uncultured denitrifying gamma-proteobacteria. The present study could be useful for making bioremediation strategy for nitrogenous metabolites and understanding of nitrogen fluxes generated through these two functional groups in coastal shrimp aquaculture.

Krishnani KK

2010-04-01

202

Aerobic and Anaerobic Toluene Degradation by a Newly Isolated Denitrifying Bacterium, Thauera sp. Strain DNT-1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A newly isolated denitrifying bacterium, Thauera sp. strain DNT-1, grew on toluene as the sole carbon and energy source under both aerobic and anaerobic conditions. When this strain was cultivated under oxygen-limiting conditions with nitrate, first toluene was degraded as oxygen was consumed, while...

Shinoda, Yoshifumi; Sakai, Yasuyoshi; Uenishi, Hiroshi; Uchihashi, Yasumitsu; Hiraishi, Akira; Yukawa, Hideaki

203

[Isolation and characterization of the salt-tolerant aerobic denitrifying bacterial strain A-13].  

UK PubMed Central (United Kingdom)

OBJECTIVE: This study is aimed to isolate and identify an aerobic denitrifying bacterium with high ability for nitrogen removing, and optimize its growing and denitrifying conditions to obtain the theory basis for controlling the eutrophic artificial lake. METHODS: Aerobic denitrifying bacterium strain A-13 was screened by denitrifying medium. Strain identification was carried out through morphological, biochemical and physiological characteristics, 16S rRNA gene and periplasm nitrate reductase gene analysis. The optimal pH, temperature, carbon source, dissolved oxygen (DO), inoculum ratio were tested as well. RESULTS: Strain A-13 isolated from a drain outlet located in Gaoqi village, Shangjie town, Minhou county, Fuzhou, China, was a member of Pseudomonas stutzeri and its DNA sequence was most closely related to Pseudomonas stutzeri DSM 50283. The optimal conditions for its growth and denitrification were followed as: pH 6.5, 33 degrees C, 150 r/min, 5% inoculum rate and the best carbon source was sodium succinate. Under these conditions, the maximum removal capacity for NO3- was approximately 1900 mg/L. The strain could grow well in the medium with high salinity (10%) and could also use NO2- and NH(4+)-H as the sole nitrogen source. CONCLUSION: The isolated P. stutzeri, A-13 is a potential strain to treat wastewater with high salinity and/or eutrophication.

Han Y; Zhang W; Zhuang Z; Zhou Z; Xu X; Li M

2013-01-01

204

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

205

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Horn, Marcus A.; Mertel, Ralph; Gehre, Matthias; Kästner, Matthias; Drake, Harold L.

206

Culture.  

UK PubMed Central (United Kingdom)

This article summarizes the definitions, means, and research of adapting psychotherapy to clients' cultural backgrounds. We begin by reviewing the prevailing definitions of cultural adaptation and providing a clinical example. We present an original meta-analysis of 65 experimental and quasi-experimental studies involving 8,620 participants. The omnibus effect size of d = .46 indicates that treatments specifically adapted for clients of color were moderately more effective with that clientele than traditional treatments. The most effective treatments tended to be those with greater numbers of cultural adaptations. Mental health services targeted to a specific cultural group were several times more effective than those provided to clients from a variety of cultural backgrounds. We recommend a series of research-supported therapeutic practices that account for clients' culture, with culture-specific treatments being more effective than generally culture-sensitive treatments.

Smith TB; Rodríguez MD; Bernal G

2011-02-01

207

Quantitative Proteomics Reveals that Plasma Membrane Microdomains from Poplar Cell Suspension Cultures are Enriched in Markers of Signal Transduction, Molecular Transport and Callose Biosynthesis.  

UK PubMed Central (United Kingdom)

The plasma membrane (PM) is a highly dynamic interface that contains detergent-resistant microdomains (DRM). The aim of this work was to determine the main functions of such microdomains in poplar through a proteomic analysis using gel-based and solution (iTRAQ) approaches. Compared to PM, a total of 80 proteins from a limited number of functional classes were found to be significantly enriched in DRM. The enriched proteins are markers of signal transduction, molecular transport at the PM or cell wall biosynthesis. Their intrinsic properties are presented and discussed together with the biological significance of their enrichment in DRM. Of particular importance is the significant and specific enrichment of several callose [(1?3)-?-glucan] synthase isoforms, whose catalytic activity represents a final response to stress, leading to the deposition of callose plugs at the surface of the PM. An integrated functional model that connects all DRM-enriched proteins identified is proposed. This report is the only quantitative analysis available to date of the protein composition of membrane microdomains from a tree species.

Srivastava V; Malm E; Sundqvist G; Bulone V

2013-09-01

208

Effect of H2S on N2O Reduction and Accumulation during Denitrification by Methanol Utilizing Denitrifiers.  

UK PubMed Central (United Kingdom)

Sulfide is produced in sewer networks, and previous studies suggest that sulfide in sewage could alter the activity of heterotrophic denitrification and lead to N2O accumulation during biological wastewater treatment. However, the details of this phenomenon are poorly understood. In this study, the potential inhibitory effects of sulfide on nitrate, nitrite, and N2O reduction were assessed with a methanol-utilizing denitrifying culture both prior to and after its exposure and adaptation to sulfide. Hydrogen sulfide was found to be strongly inhibitory to N2O reduction, with 50% inhibition observed at H2S concentrations of 0.04 mg H2S-S/L and 0.1 mg H2S-S/L for the unadapted and adapted cultures, respectively. In comparison, both nitrate and nitrite reduction was more tolerant to H2S. A 50% inhibition of nitrite reduction was observed at approximately 2.0 mg H2S-S/L for both unadapted and adapted cultures, while no inhibition of nitrate reduction occurred at the highest H2S concentrations applied (2.0 mg H2S-S/L) to either culture. N2O accumulation was observed during nitrate and nitrite reduction by the adapted culture when H2S concentrations were above 0.5 and 0.2 mg H2S-S/L, respectively. Additionally, we reveal that hydrogen sulfide (H2S), rather than sulfide, was likely the true inhibitor of N2O reduction, and the inhibitory effect was reversible. These findings suggest that sulfide management in sewers could potentially have a significant impact on N2O emission from wastewater treatment plants.

Pan Y; Ye L; Yuan Z

2013-08-01

209

Crop residue influence on denitrification, N2O emissions and denitrifier community abundance in soil  

UK PubMed Central (United Kingdom)

Bacterial denitrification plays an important role in the global nitrogen cycle and is a principal contributor of nitrous oxide (N2O) to the atmosphere. The influence of simple (glucose) and complex (red clover and barley residue) carbon (C) sources on the amount of denitrification, N2O molar ratio (N2O:(N2 + N2O)), and abundance of soil total bacterial and denitrifier communities was investigated using repacked soil cores. Quantitative PCR was used to determine the abundance of the total bacterial community (16S rRNA gene) and components of the denitrifier community, cnorBP (Pseudomonas mandelii and related species), cnorBB (Bosea/Bradyrhizobium/Ensifer spp.) and nosZ gene bearing communities. The relationship between the supply of, and demand for, terminal electron acceptors (TEAs), as determined by the relative availability of C and nitrate (NO3(-)), influenced the amount of denitrification and the N2O molar ratio for both simple and complex C sources. Addition of glucose and red clover to the soil increased microbial activity, leading to NO3(-) depletion and an increased consumption of N2O, whereas in soil amended with barley straw, there was not sufficient stimulation of microbial activity to create sufficient TEA demand to cause a measurable increase in emissions. This resulted in a higher N2O molar ratio at the end of the incubation for the barley straw amended soil. A significant relationship (R2 = 0.83) was found between respiration and cumulative denitrification, suggesting that the available C increased microbial activity and O2 consumption, which led to conditions favorable for denitrification. The source of C did not significantly affect the total bacterial community or the nosZ copy numbers with an average of 4.9 x 10(7) 16S rRNA gene copies g-1 dry soil and 4.6 x 10(6) nosZ gene copies g-1 dry soil, respectively. The addition of red clover plus NO3(-) significantly increased the cnorBP denitrifier community in comparison with the unamended control while the density of the cnorBP denitrifier community increased from 3.9 x 10(4) copies g-1 dry soil to a maximum of 8.7 x 10(5) copies g-1 dry soil following addition of glucose plus NO3(-) to soil. No significant correlations were found between the denitrifier community densities and cumulative denitrification or N2O emissions, suggesting that the denitrification activity was decoupled from the denitrifier community abundance.

Miller MN; Zebarth BJ; Dandie CE; Burton DL; Goyer C; Trevors JT

2008-10-01

210

Performance of a reactor containing denitrifying immobilized biomass in removing ethanol and aromatic hydrocarbons (BTEX) in a short operating period  

International Nuclear Information System (INIS)

A horizontal-flow anaerobic immobilized biomass reactor (HAIB) containing denitrifying biomass was evaluated with respect to its ability to remove, separately and in a short operating period (30 days), organic matter, nitrate, and the hydrocarbons benzene (41.4 mg L-1), toluene (27.8 mg L-1), ethylbenzene (31.1 mg L-1), o-xylene (28.5 mg L-1), m-xylene (28.4 mg L-1) and p-xylene (32.1 mg L-1). The purified culture, which was grown in the presence of the specific hydrocarbon, was used as the source of cells to be immobilized in the polyurethane foam. After 30 days of operation, the foam was removed and a new immobilized biomass was grown in the presence of another hydrocarbon. The average hydrocarbon removal efficiency attained was 97%. The organic matter, especially ethanol, was removed with an average efficiency of 83% at a mean influent concentration of 1185.0 mg L-1. A concomitant removal of 97% of nitrate was observed for a mean influent concentration of 423.4 mg L-1. The independent removal of each hydrocarbon demonstrated that these contaminants can be biodegraded separately, without the need for a compound to be the primary substrate for the degradation of another. This study proposes the application of the system for treatment of areas contaminated with these compounds, with substitution and formation of a biofilm in a 30-day period.

2007-01-10

211

CULTURE  

UK PubMed Central (United Kingdom)

Provided is an aquiculture device using wet fog in which culture fluid and pure water are alternately sprayed by two spraying device, room humidification effect is provided by device of spraying pure water, and device of spraying the culture fluid is washed with water, and thus vibrator is not impaired by the culture fluid. The aquiculture device comprises a body(1) a water storage part(2) for storing a pure water at the bottom of the body(1) a culture fluid storage part(3) at the upper part of one side of the body(1) a culturing room(4) formed at the upper part of the other side of the body(1) a double structure of support layer(41) and a filtering layer(42) which have space(43) therebetween a first spray device(5) and a second spray device(6) installed in the water storage part(2). In the device, pure water and culture fluid are alternately supplied from the water storage part(2) and the culture fluid storage part(3).

CHOI JIN YOUNG; PARK DEOK JAE

212

Isolation of aerobic denitrifiers and characterization for their potential application in the bioremediation of oligotrophic ecosystem.  

UK PubMed Central (United Kingdom)

In recent years, nitrogen pollution has been increasingly serious in environmental waters in China, especially in drinking source. Seven predominant aerobic denitrifiers were isolated and characterized from the oligotrophic ecosystems. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Pseudomonas, Achromobacter and Acinetobacter, and all isolates could express periplasmic nitrate reductase which was essential for the aerobic denitrification. The growth rates of the isolates were at 0.30-0.83 h(-1), and obvious denitrification occurred when the dissolved oxygen (DO) level maintained at 3-10 mg L(-1). The isolates were able to conduct heterotrophic nitrification for realizing completely nitrogen removal in aerobic oligotrophic niche. Furthermore, three strains especially Pseudomonas sp.3-7 showed outstanding capacities of extracellular polymeric substances (EPS) secretion and aggregation. Results demonstrated that the isolation of aerobic denitrifiers favored the bioremediation of oligotrophic ecosystems.

Zhu L; Ding W; Feng LJ; Kong Y; Xu J; Xu XY

2012-03-01

213

Bioavailability and biodegradation of weathered diesel fuel in aquifer material under denitrifying conditions  

International Nuclear Information System (INIS)

During the in situ bioremediation of a diesel fuel-contaminated aquifer in Menziken, Switzerland, aquifer material containing weathered diesel fuel (WDF) and indigenous microorganisms was excavated. This material was used to identify factors limiting WDF biodegradation under denitrifying conditions. Incubations of this material for 360 to 390 d under denitrifying conditions resulted in degradation of 23% of the WDF with concomitant consumption of NO3- and production of inorganic carbon. The biodegradation of WDF and the rate of NO3- consumption was stimulated by agitation of the microcosms. Biodegradation was not stimulated by the addition of a biosurfactant (rhamnolipids) or a synthetic surfactant (Triton X-100) at concentrations above their critical micelle concentrations. The rhamnolipids were biodegraded preferentially to WDF, whereas Triton X-100 was not degraded. Both surfactants reduced the surface tension of the growth medium from 72 to

1998-01-01

214

Identification of active denitrifiers in rice paddy soil by DNA- and RNA-based analyses.  

UK PubMed Central (United Kingdom)

Denitrification occurs markedly in rice paddy fields; however, few microbes that are actively involved in denitrification in these environments have been identified. In this study, we used a laboratory soil microcosm system in which denitrification activity was enhanced. DNA and RNA were extracted from soil at six time points after enhancing denitrification activity, and quantitative PCR and clone library analyses were performed targeting the 16S rRNA gene and denitrification functional genes (nirS, nirK and nosZ) to clarify which microbes are actively involved in denitrification in rice paddy soil. Based on the quantitative PCR results, transcription levels of the functional genes agreed with the denitrification activity, although gene abundance did not change at the DNA level. Diverse denitrifiers were detected in clone library analysis, but comparative analysis suggested that only some of the putative denitrifiers, especially those belonging to the orders Neisseriales, Rhodocyclales and Burkholderiales, were actively involved in denitrification in rice paddy soil.

Yoshida M; Ishii S; Fujii D; Otsuka S; Senoo K

2012-01-01

215

A technique for measuring nitrogen isotopic composition of nitrate using the denitrifier method  

International Nuclear Information System (INIS)

A measurement technique of the denitrifier method, which was developed for seawater isotopic analysis, was established for analyzing nitrogen isotopic composition of nitrate in groundwater and the vadose zone sediments. Experiments were conducted using international isotopic standards of IAEA-N3 and USGS34 and field samples. ?15N analyses of the two isotopic standards showed good reproducibility, with an average precision of 0.25 per thousand (ranging from 0.1 per thousand to 0.5 per thousand). Groundwater and sediment extracts were accurately reproduced, with precisions of better 0.5 per thousand. The results showed that the measurement technique of the denitrifier method could be used for analyzing nitrogen isotopic composition of nitrate in groundwater and sediments. A case study using the technique showed that a thick vadose zone sediment profile had no increase trend of ?15N values in depths below the vadose zone, indicating little denitrification occurrence. (authors)

2011-01-01

216

Promotion of oil hydrocarbon degradation in fine-grained marsh soils under aerobic and denitrifying conditions  

Energy Technology Data Exchange (ETDEWEB)

The goal of the laboratory studies was to prove oil hydrocarbon degradation in fine-grained marsh soils under denitrifying conditions and to compare it with the degradation under aerobic conditions. In order to accelerate the bioremediation process in soils with redox potentials < + 200 mV (pH 7) the use of different additives and oxidizing agents was tested. Fine-grained soil materials from marsh soils was treated with KNO{sub 3}, fertilizers or a mixture of both for the hydrocarbon degradation under anoxic denitrifying conditions as well as the addition of hydrogen peroxide or an oil binder to improve the soil structure to promote aerobic hydrocarbon degradation. During the incubation period, soil respiration (CO{sub 2}-production) was measured nearly every day, the content of hydrocarbons as well as the number of microbial hydrocarbon degraders (aerobic, anaerobic), NH{sub 4}{sup +}-N, NO{sub 3}{sup -}-N and total N was measured at the beginning of the test and after two and four weeks. There were several indicators for the hydrocarbon degradation under denitrifying conditions: high denitrification rates, an increase in colonization with denitrifying bacteria, higher respiratory quotients and higher degradation rates compared to the reference. At the end of the test period the oil binder treated soil had the highest degradation rate, but there were severe differences in the degradation rate between the first and second fortnight of all treatments. Our investigation suggests that combined KNO{sub 3} and fertilizer treatment is the most promising treatment to accelerate biological hydrocarbon degradation in fine-grained marsh soils and should be tested in the near future in biopiles. (orig.)

Brecht, M.; Beyer, L.; Huettmann, S. [Groth und Co. GmbH, Itzehoe. Abt. Umwelttechnik und Consult (Germany)

2000-07-01

217

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; Margaret R. Mulholland; Feixue Fu

2009-01-01

218

Nitrogen Removal by a Fungal Aerobic Denitrifier of Penicillium Strain  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A kind of aerobic Penicillium that can remove ammonia, nitrite and nitrate was isolated through an improved bromothymol blue (BTB) selective culture medium method in this experiment and then the nitrogen removal by the strain was detailedly investigated. The results showed that this strain wa...

Weisi Li; Chaocheng Zhao

219

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

220

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

UK PubMed Central (United Kingdom)

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.

Lee SH; Kim SY; Kang H

2012-08-01

 
 
 
 
221

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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)...

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

222

Nitrosamine formation by denitrifying and non-denitrifying bacteria: implication of nitrite reductase and nitrate reductase in nitrosation catalysis.  

UK PubMed Central (United Kingdom)

Biochemical, microbiological and genetic studies were done to characterize the mechanism of bacterial formation of N-nitrosomorpholine (NMOR) from morpholine and nitrite at neutral pH. In Escherichia coli and Proteus morganii, the nitrosating activity was markedly induced when bacteria were cultured under anaerobiosis in minimal medium containing nitrate, while in the presence of nitrite there was no induction. However, induction of the nitrosating activity in Pseudomonas aeruginosa occurred in anaerobic cultures in the presence of either nitrate or nitrite. The nitrosation capacity was also examined in various E. coli K12 mutants whose structural gene of either nitrate reductase or nitrite reductase was deleted. Nitrosation was not linked to the three (NADH-, formate- and glucose-dependent) nitrite reductases but was directly dependent on the presence of a nitrate reductase.

Calmels S; Ohshima H; Bartsch H

1988-01-01

223

Nitrosamine formation by denitrifying and non-denitrifying bacteria: implication of nitrite reductase and nitrate reductase in nitrosation catalysis.  

Science.gov (United States)

Biochemical, microbiological and genetic studies were done to characterize the mechanism of bacterial formation of N-nitrosomorpholine (NMOR) from morpholine and nitrite at neutral pH. In Escherichia coli and Proteus morganii, the nitrosating activity was markedly induced when bacteria were cultured under anaerobiosis in minimal medium containing nitrate, while in the presence of nitrite there was no induction. However, induction of the nitrosating activity in Pseudomonas aeruginosa occurred in anaerobic cultures in the presence of either nitrate or nitrite. The nitrosation capacity was also examined in various E. coli K12 mutants whose structural gene of either nitrate reductase or nitrite reductase was deleted. Nitrosation was not linked to the three (NADH-, formate- and glucose-dependent) nitrite reductases but was directly dependent on the presence of a nitrate reductase. PMID:3141563

Calmels, S; Ohshima, H; Bartsch, H

1988-01-01

224

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

Science.gov (United States)

Denitrification in the ocean is a major sink for fixed nitrogen in the global N budget, but the process is geographically restricted to a few oceanic regions, including three oceanic oxygen minimum zones (OMZ) and hemipelagic sediments worldwide. Here, we describe the diversity and community composition of microbes responsible for denitrification in the OMZ using polymerase chain reaction, sequence and fragment analysis of clone libraries of the signature genes (nirK and nirS) that encode the enzyme nitrite reductase, responsible for key denitrification transformation steps. We show that denitrifying assemblages vary in space and time and exhibit striking changes in diversity associated with the progression of denitrification from initial anoxia through nitrate depletion. The initial denitrifying assemblage is highly diverse, but succession on the scale of 3-12 days leads to a much less diverse assemblage and dominance by one or a few phylotypes. This progression occurs in the natural environment as well as in enclosed incubations. The emergence of dominants from a vast reservoir of rare types has implications for the maintenance of diversity of the microbial population and suggests that a small number of microbial dominants may be responsible for the greatest rates of transformations involving nitrous oxide and global fixed nitrogen loss. Denitrifying blooms, driven by a few types responding to episodic environmental changes and distributed unevenly in time and space, are consistent with the sampling effect model of diversity-function relationships. Canonical denitrification thus appears to have important parallels with both primary production and nitrogen fixation, which are typically dominated by regionally and temporally restricted blooms that account for a disproportionate share of these processes worldwide. PMID:19238477

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

2009-02-24

225

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

UK PubMed Central (United Kingdom)

Denitrification in the ocean is a major sink for fixed nitrogen in the global N budget, but the process is geographically restricted to a few oceanic regions, including three oceanic oxygen minimum zones (OMZ) and hemipelagic sediments worldwide. Here, we describe the diversity and community composition of microbes responsible for denitrification in the OMZ using polymerase chain reaction, sequence and fragment analysis of clone libraries of the signature genes (nirK and nirS) that encode the enzyme nitrite reductase, responsible for key denitrification transformation steps. We show that denitrifying assemblages vary in space and time and exhibit striking changes in diversity associated with the progression of denitrification from initial anoxia through nitrate depletion. The initial denitrifying assemblage is highly diverse, but succession on the scale of 3-12 days leads to a much less diverse assemblage and dominance by one or a few phylotypes. This progression occurs in the natural environment as well as in enclosed incubations. The emergence of dominants from a vast reservoir of rare types has implications for the maintenance of diversity of the microbial population and suggests that a small number of microbial dominants may be responsible for the greatest rates of transformations involving nitrous oxide and global fixed nitrogen loss. Denitrifying blooms, driven by a few types responding to episodic environmental changes and distributed unevenly in time and space, are consistent with the sampling effect model of diversity-function relationships. Canonical denitrification thus appears to have important parallels with both primary production and nitrogen fixation, which are typically dominated by regionally and temporally restricted blooms that account for a disproportionate share of these processes worldwide.

Jayakumar A; O'Mullan GD; Naqvi SW; Ward BB

2009-08-01

226

Pseudomonas yangmingensis sp. nov., an alkaliphilic denitrifying species isolated from a hot spring.  

UK PubMed Central (United Kingdom)

This study isolated and identified a facultative, alkaliphilic, denitrifying Pseudomonas strain designed as CRS1 from a hot spring, Yang-Ming Mountain, Taiwan. The biochemical characterization, phenotypic characteristics and phylogenetic relationship of strain CRS1 were studied. On the basis of the 16S rRNA sequence similarity, phenotypic and genotypic characteristics and chemotaxonomic data, the strain CRS1 represents a novel species of the genus Pseudomonas, for which the name Pseudomonas yangmingensis sp. nov., is proposed. The strain CRS1 is a facultative autotrophic bacterium that has capability of mixotrophic and heterotrophic denitrification.

Wong BT; Lee DJ

2013-07-01

227

Nitrogen Removal by a Fungal Aerobic Denitrifier of Penicillium Strain  

Directory of Open Access Journals (Sweden)

Full Text Available A kind of aerobic Penicillium that can remove ammonia, nitrite and nitrate was isolated through an improved bromothymol blue (BTB) selective culture medium method in this experiment and then the nitrogen removal by the strain was detailedly investigated. The results showed that this strain was able to make use of many kinds of organic carbon compounds as sole carbon source for the removal of the three types of inorganic nitrogen compounds but the way of removal was different. Ammonia was assimilated for forming cell components such as amino acid and protein, different from which, nitrite and nitrate were eliminated by the aid of dual assimilation and denitrification. When the three types of nitrogen coexist, the removal order was as follows: ammonia>nitrite>nitrate. Type of carbon source, initial nitrogen concentration and carbon nitrogen ratio (C/N) all had different effect on final solution pH, dry weight, nitrogen removal rate and removal ability of the strain. It was tested that non-polar organic carbon source containing -CH3 group like sucrose was inclined to be used by the strain. When sucrose was carbon source, the optimum C/N of ammonia, nitrite and nitrate removal were separate 4-6, 8-12 and 12-16. In addition, it was demonstrated with calculation that the removal abilities of the above mentioned three nitrogen of the strain were about 50, 60 and 90 mg g-1 respectively, showing its tremendous capability of nitrogen removal.

Weisi Li; Chaocheng Zhao

2012-01-01

228

Aerobic and Anaerobic Toluene Degradation by a Newly Isolated Denitrifying Bacterium, Thauera sp. Strain DNT-1  

Science.gov (United States)

A newly isolated denitrifying bacterium, Thauera sp. strain DNT-1, grew on toluene as the sole carbon and energy source under both aerobic and anaerobic conditions. When this strain was cultivated under oxygen-limiting conditions with nitrate, first toluene was degraded as oxygen was consumed, while later toluene was degraded as nitrate was reduced. Biochemical observations indicated that initial degradation of toluene occurred through a dioxygenase-mediated pathway and the benzylsuccinate pathway under aerobic and denitrifying conditions, respectively. Homologous genes for toluene dioxygenase (tod) and benzylsuccinate synthase (bss), which are the key enzymes in aerobic and anaerobic toluene degradation, respectively, were cloned from genomic DNA of strain DNT-1. The results of Northern blot analyses and real-time quantitative reverse transcriptase PCR suggested that transcription of both sets of genes was induced by toluene. In addition, the tod genes were induced under aerobic conditions, whereas the bss genes were induced under both aerobic and anaerobic conditions. On the basis of these results, it is concluded that strain DNT-1 modulates the expression of two different initial pathways of toluene degradation according to the availability of oxygen in the environment.

Shinoda, Yoshifumi; Sakai, Yasuyoshi; Uenishi, Hiroshi; Uchihashi, Yasumitsu; Hiraishi, Akira; Yukawa, Hideaki; Yurimoto, Hiroya; Kato, Nobuo

2004-01-01

229

Aerobic and anaerobic toluene degradation by a newly isolated denitrifying bacterium, Thauera sp. strain DNT-1.  

UK PubMed Central (United Kingdom)

A newly isolated denitrifying bacterium, Thauera sp. strain DNT-1, grew on toluene as the sole carbon and energy source under both aerobic and anaerobic conditions. When this strain was cultivated under oxygen-limiting conditions with nitrate, first toluene was degraded as oxygen was consumed, while later toluene was degraded as nitrate was reduced. Biochemical observations indicated that initial degradation of toluene occurred through a dioxygenase-mediated pathway and the benzylsuccinate pathway under aerobic and denitrifying conditions, respectively. Homologous genes for toluene dioxygenase (tod) and benzylsuccinate synthase (bss), which are the key enzymes in aerobic and anaerobic toluene degradation, respectively, were cloned from genomic DNA of strain DNT-1. The results of Northern blot analyses and real-time quantitative reverse transcriptase PCR suggested that transcription of both sets of genes was induced by toluene. In addition, the tod genes were induced under aerobic conditions, whereas the bss genes were induced under both aerobic and anaerobic conditions. On the basis of these results, it is concluded that strain DNT-1 modulates the expression of two different initial pathways of toluene degradation according to the availability of oxygen in the environment.

Shinoda Y; Sakai Y; Uenishi H; Uchihashi Y; Hiraishi A; Yukawa H; Yurimoto H; Kato N

2004-03-01

230

Evaluation of the microbial diversity of denitrifying bacteria in batch reactor  

Scientific Electronic Library Online (English)

Full Text Available 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 the biological process of denitrification. Ethanol is an economically viable alternative as a carbon source in tropical countries like Brazil, with large-scale production from su (more) garcane. 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.

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

2013-09-01

231

Identification of active denitrifiers in rice paddy soil by DNA- and RNA-based analyses.  

Science.gov (United States)

Denitrification occurs markedly in rice paddy fields; however, few microbes that are actively involved in denitrification in these environments have been identified. In this study, we used a laboratory soil microcosm system in which denitrification activity was enhanced. DNA and RNA were extracted from soil at six time points after enhancing denitrification activity, and quantitative PCR and clone library analyses were performed targeting the 16S rRNA gene and denitrification functional genes (nirS, nirK and nosZ) to clarify which microbes are actively involved in denitrification in rice paddy soil. Based on the quantitative PCR results, transcription levels of the functional genes agreed with the denitrification activity, although gene abundance did not change at the DNA level. Diverse denitrifiers were detected in clone library analysis, but comparative analysis suggested that only some of the putative denitrifiers, especially those belonging to the orders Neisseriales, Rhodocyclales and Burkholderiales, were actively involved in denitrification in rice paddy soil. PMID:22972387

Yoshida, Megumi; Ishii, Satoshi; Fujii, Daichi; Otsuka, Shigeto; Senoo, Keishi

2012-09-05

232

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

UK PubMed Central (United Kingdom)

This work evaluated N dynamics that occurs over time within swine slurry composting piles. Real-time quantitative PCR (qPCR) analyzes were conducted to estimate concentrations of bacteria community harboring specific catabolic nitrifying-ammonium monooxygenase (amoA), and denitrifying nitrate- (narG), nitrite- (nirS and nirG), nitric oxide- (norB) and nitrous oxide reductases (nosZ) genes. NH3-N, N2O-N, N2-N emissions represented 15.4 ± 1.9%, 5.4 ± 0.9%, and 79.1 ± 2.0% of the total nitrogen losses, respectively. Among the genes tested, temporal distribution of narG, nirS, and nosZ concentration correlated significantly (p<0.05) with the estimated N2 emissions. Denitrifying catabolic gene ratio (cnorB+qnorB)/nosZ ? 100 was indicative of N2O emission potential from the compost pile. Considering our current empirical limitations to accurately measure N2 emissions from swine slurry composting at field scale the use of these catabolic genes could represent a promising monitoring tool to aid minimize our uncertainties on biological N mass balances in these systems.

Angnes G; Nicoloso RS; da Silva ML; de Oliveira PA; Higarashi MM; Mezzari MP; Miller PR

2013-07-01

233

Impact of plant functional group, plant species, and sampling time on the composition of nirK-type denitrifier communities in soil.  

UK PubMed Central (United Kingdom)

We studied the influence of eight nonleguminous grassland plant species belonging to two functional groups (grasses and forbs) on the composition of soil denitrifier communities in experimental microcosms over two consecutive years. Denitrifier community composition was analyzed by terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified nirK gene fragments coding for the copper-containing nitrite reductase. The impact of experimental factors (plant functional group, plant species, sampling time, and interactions between them) on the structure of soil denitrifier communities (i.e., T-RFLP patterns) was analyzed by canonical correspondence analysis. While the functional group of a plant did not affect nirK-type denitrifier communities, plant species identity did influence their composition. This effect changed with sampling time, indicating community changes due to seasonal conditions and a development of the plants in the microcosms. Differences in total soil nitrogen and carbon, soil pH, and root biomass were observed at the end of the experiment. However, statistical analysis revealed that the plants affected the nirK-type denitrifier community composition directly, e.g., through root exudates. Assignment of abundant T-RFs to cloned nirK sequences from the soil and subsequent phylogenetic analysis indicated a dominance of yet-unknown nirK genotypes and of genes related to nirK from denitrifiers of the order Rhizobiales. In conclusion, individual species of nonleguminous plants directly influenced the composition of denitrifier communities in soil, but environmental conditions had additional significant effects.

Bremer C; Braker G; Matthies D; Reuter A; Engels C; Conrad R

2007-11-01

234

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

2007-01-01

235

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

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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 treatme...

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

236

Use of a chemiluminescent detector for quantitation of nitric oxide produced in assays of denitrifying enzymes. [Achromobacter cycloblastes; Pseudomonas perfectomarini  

Energy Technology Data Exchange (ETDEWEB)

The authors developed a closed-flow system that continuously sweeps away gases evolved in enzyme assay mixtures into a commercially available oxides of nitrogen analyzer for the quantitation of any nitric oxide (NO) present in these gases. The system is particularly useful for the study of both the stoichiometry and kinetics of NO production from nitrite by cell-free extracts of denitrifying bacteria and by the purified denitrifying nitrite reductases. In addition to its much greater sensitivity when compared to standard gas chromatographic techniques, the method offers some unique advantages since it allows measurements of initial reaction velocities, without the problems of product inhibition, which often limit kinetic studies of denitrifying enzymes. The system also allows the immediate quantitation of any NO produced and so would be useful in detecting the transient presence of this very reactive free radical, if it is produced as a free intermediate in whole cell suspensions of denitrifying bacteria respiring nitrate. The apparatus has been calibrated using a purified copper nitrite reductase from Achromobacter cycloclastes and cell-free extracts from Pseudomonas Perfectomarini, and its utility in studies of the kinetics and stoichiometry of NO production from nitrite confirmed by comparison with results obtained using manometric and gas chromatographic techniques.

Pai, G.; Payne, W.J.; Le Gall, J.

1987-05-01

237

Genome Sequences for Three Denitrifying Bacterial Strains Isolated from a Uranium- and Nitrate-Contaminated Subsurface Environment  

Science.gov (United States)

Genome sequences for three strains of denitrifying bacteria (Alphaproteobacteria—Afipia sp. strain 1NLS2 and Hyphomicrobium denitrificans strain 1NES1; Firmicutes—Bacillus sp. strain 1NLA3E) isolated from the nitrate- and uranium-contaminated subsurface of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site, Oak Ridge Reservation, TN, are reported.

Venkatramanan, Raghavee; Prakash, Om; Woyke, Tanja; Chain, Patrick; Goodwin, Lynne A.; Watson, David; Brooks, Scott; Kostka, Joel E.

2013-01-01

238

Polyphosphate-accumulating and denitrifying bacteria isolated from anaerobic-anoxic and anaerobic-aerobic sequencing batch reactors  

Science.gov (United States)

In this study, phosphate-accumulating bacteria achieved complete phosphate removal in two different systems: an anaerobic-anoxic sequencing batch reactor and an anaerobic-aerobic sequencing batch reactor. This result shows that phosphate-accumulating bacteria in the A2 SBR can use nitrate as terminal electron acceptor instead of oxygen. Phosphate-accumulating bacteria accumulated phosphate with a rates between 30 and 70 mg P/L/h in the A/O SBR and between 15 and 32 mg P/L/h in the A2 SBR. Twenty denitrifying isolates were screened from A2 SBR and nine from A/O SBR. Identification of these isolates by the Biolog system and the API 20 NE identification kit revealed that the most active denitrifiers in both SBRs reactors were species of Ochrobactrum, Pseudomonas, Corynebacterium, Agrobacterium, Aquaspirillum, Haemophilus, Xanthomonas, Aeromonas, and Shewanella. The most active phosphate accumulating and denitrifying bacteria were identified as Agrobacterium tumefaciens B, Aquaspirillum dispar, and Agrobacterium radiobacter. This study showed that the active phosphate accumulating-bacteria were also the most efficient denitrifying bacteria in both reactors. PMID:9841775

Merzouki; Delgenes; Bernet; Moletta; Benlemlih

1999-01-01

239

Genome sequences for three denitrifying bacterial strains isolated from a uranium- and nitrate-contaminated subsurface environment.  

UK PubMed Central (United Kingdom)

Genome sequences for three strains of denitrifying bacteria (Alphaproteobacteria-Afipia sp. strain 1NLS2 and Hyphomicrobium denitrificans strain 1NES1; Firmicutes-Bacillus sp. strain 1NLA3E) isolated from the nitrate- and uranium-contaminated subsurface of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site, Oak Ridge Reservation, TN, are reported.

Venkatramanan R; Prakash O; Woyke T; Chain P; Goodwin LA; Watson D; Brooks S; Kostka JE; Green SJ

2013-01-01

240

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

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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 s...

Barak, Yoram; van Rijn, Jaap

 
 
 
 
241

Association of Earthworm-Denitrifier Interactions with Increased Emission of Nitrous Oxide from Soil Mesocosms Amended with Crop Residue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Earthworm activity is known to increase emissions of nitrous oxide (N2O) from arable soils. Earthworm gut, casts, and burrows have exhibited higher denitrification activities than the bulk soil, implicating priming of denitrifying organisms as a possible mechanism for this effect. Furthermore, the e...

Nebert, L.D.; Bloem, J.; Lubbers, I.M.; Groenigen, J.W., van

242

Association of Earthworm-Denitrifier Interactions with Increased Emission of Nitrous Oxide from Soil Mesocosms Amended with Crop Residue?†  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Earthworm activity is known to increase emissions of nitrous oxide (N2O) from arable soils. Earthworm gut, casts, and burrows have exhibited higher denitrification activities than the bulk soil, implicating priming of denitrifying organisms as a possible mechanism for this effect. Furthermore, the e...

Nebert, Lucas D.; Bloem, Jaap; Lubbers, Ingrid M.; van Groenigen, Jan Willem

243

Complete Genome Sequence of the Denitrifying and N2O-Reducing Bacterium Azoarcus sp. Strain KH32C  

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We report the finished and annotated genome sequence of a denitrifying and N2O-reducing betaproteobacterium, Azoarcus sp. strain KH32C. The genome is composed of one chromosome and one megaplasmid and contains genes for plant-microbe interactions and the gene clusters for aromatic-compound degradati...

Nishizawa, Tomoyasu; Tago, Kanako; Oshima, Kenshiro; Hattori, Masahira; Ishii, Satoshi; Otsuka, Shigeto; Senoo, Keishi

244

Complete genome sequence of the denitrifying and N2O-reducing bacterium Azoarcus sp. strain KH32C.  

UK PubMed Central (United Kingdom)

We report the finished and annotated genome sequence of a denitrifying and N(2)O-reducing betaproteobacterium, Azoarcus sp. strain KH32C. The genome is composed of one chromosome and one megaplasmid and contains genes for plant-microbe interactions and the gene clusters for aromatic-compound degradations.

Nishizawa T; Tago K; Oshima K; Hattori M; Ishii S; Otsuka S; Senoo K

2012-03-01

245

Complete genome sequence of the denitrifying and N2O-reducing bacterium Azoarcus sp. strain KH32C.  

Science.gov (United States)

We report the finished and annotated genome sequence of a denitrifying and N(2)O-reducing betaproteobacterium, Azoarcus sp. strain KH32C. The genome is composed of one chromosome and one megaplasmid and contains genes for plant-microbe interactions and the gene clusters for aromatic-compound degradations. PMID:22328754

Nishizawa, Tomoyasu; Tago, Kanako; Oshima, Kenshiro; Hattori, Masahira; Ishii, Satoshi; Otsuka, Shigeto; Senoo, Keishi

2012-03-01

246

Development of a cell culture method to isolate and enrich Salmonella enterica serotype enteritidis from shell eggs for subsequent detection by real-time PCR.  

UK PubMed Central (United Kingdom)

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 method of the International Organization for Standardization (Anonymous, Microbiology of food and animal feeding stuffs-horizontal method for the detection of Salmonella, 2002). The novel technique utilizes a mouse macrophage cell line (RAW 264.7) as the host for the isolation and intracellular replication of Salmonella serotype Enteritidis. Exposure of macrophages to Salmonella serotype Enteritidis-contaminated eggs results in uptake and intracellular replication of the bacterium, which can subsequently be detected by real-time PCR analysis of the DNA released after disruption of infected macrophages. Macrophage monolayers were exposed to eggs contaminated with various quantities of Salmonella serotype Enteritidis. As few as 10 CFU/ml was detected in cell lysates from infected macrophages after 10 h by real-time PCR using primer and probe sets specific for DNA segments located on the Salmonella serotype Enteritidis genes sefA and orgC. Salmonella serotype Enteritidis could also be distinguished from other non-serogroup D Salmonella serotypes by using the sefA- and orgC-specific primer and probe sets. Confirmatory identification of Salmonella serotype Enteritidis in eggs was also achieved by isolation of intracellular bacteria from lysates of infected macrophages on xylose lysine deoxycholate medium. This method identifies Salmonella serotype Enteritidis from eggs in less than 10 h compared to the more than 5 days required for the standard reference microbiological method of the International Organization for Standardization (Microbiology of food and animal feeding stuffs-horizontal method for the detection of Salmonella, 2002).

Day JB; Basavanna U; Sharma SK

2009-08-01

247

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

Science.gov (United States)

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 method of the International Organization for Standardization (Anonymous, Microbiology of food and animal feeding stuffs—horizontal method for the detection of Salmonella, 2002). The novel technique utilizes a mouse macrophage cell line (RAW 264.7) as the host for the isolation and intracellular replication of Salmonella serotype Enteritidis. Exposure of macrophages to Salmonella serotype Enteritidis-contaminated eggs results in uptake and intracellular replication of the bacterium, which can subsequently be detected by real-time PCR analysis of the DNA released after disruption of infected macrophages. Macrophage monolayers were exposed to eggs contaminated with various quantities of Salmonella serotype Enteritidis. As few as 10 CFU/ml was detected in cell lysates from infected macrophages after 10 h by real-time PCR using primer and probe sets specific for DNA segments located on the Salmonella serotype Enteritidis genes sefA and orgC. Salmonella serotype Enteritidis could also be distinguished from other non-serogroup D Salmonella serotypes by using the sefA- and orgC-specific primer and probe sets. Confirmatory identification of Salmonella serotype Enteritidis in eggs was also achieved by isolation of intracellular bacteria from lysates of infected macrophages on xylose lysine deoxycholate medium. This method identifies Salmonella serotype Enteritidis from eggs in less than 10 h compared to the more than 5 days required for the standard reference microbiological method of the International Organization for Standardization (Microbiology of food and animal feeding stuffs—horizontal method for the detection of Salmonella, 2002).

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

2009-01-01

248

Development of a cell culture method to isolate and enrich Salmonella enterica serotype enteritidis from shell eggs for subsequent detection by real-time PCR.  

Science.gov (United States)

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 method of the International Organization for Standardization (Anonymous, Microbiology of food and animal feeding stuffs-horizontal method for the detection of Salmonella, 2002). The novel technique utilizes a mouse macrophage cell line (RAW 264.7) as the host for the isolation and intracellular replication of Salmonella serotype Enteritidis. Exposure of macrophages to Salmonella serotype Enteritidis-contaminated eggs results in uptake and intracellular replication of the bacterium, which can subsequently be detected by real-time PCR analysis of the DNA released after disruption of infected macrophages. Macrophage monolayers were exposed to eggs contaminated with various quantities of Salmonella serotype Enteritidis. As few as 10 CFU/ml was detected in cell lysates from infected macrophages after 10 h by real-time PCR using primer and probe sets specific for DNA segments located on the Salmonella serotype Enteritidis genes sefA and orgC. Salmonella serotype Enteritidis could also be distinguished from other non-serogroup D Salmonella serotypes by using the sefA- and orgC-specific primer and probe sets. Confirmatory identification of Salmonella serotype Enteritidis in eggs was also achieved by isolation of intracellular bacteria from lysates of infected macrophages on xylose lysine deoxycholate medium. This method identifies Salmonella serotype Enteritidis from eggs in less than 10 h compared to the more than 5 days required for the standard reference microbiological method of the International Organization for Standardization (Microbiology of food and animal feeding stuffs-horizontal method for the detection of Salmonella, 2002). PMID:19561188

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

2009-06-26

249

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

Energy Technology Data Exchange (ETDEWEB)

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

Yoshito, Daniele

2011-07-01

250

Advenella faeciporci sp. nov., a nitrite-denitrifying bacterium isolated from nitrifying-denitrifying activated sludge collected from a laboratory-scale bioreactor treating piggery wastewater.  

UK PubMed Central (United Kingdom)

Strain M-07(T) was isolated from nitrifying-denitrifying activated sludge treating piggery wastewater. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain M-07(T) belonged to the genus Advenella. 16S rRNA gene sequence similarity between M-07(T) and Advenella incenata CCUG 45225(T), Advenella mimigardefordensis DPN7(T) and Advenella kashmirensis WT001(T) was 96.5, 97.3 and 96.9%, respectively. The DNA G+C content of strain M-07(T) was 49.5 mol%, which was approximately 5 mol% lower than the range for the genus Advenella (53.5-58.0 mol%). The predominant cellular fatty acids of strain M-07(T) were C(16:0), summed feature 3 (comprising C(16:1)?7c and/or iso-C(15:0) 2-OH), C(17:0) cyclo and summed feature 2 (comprising one or more of C(14:0) 3-OH, iso-C(16:1) I, an unidentified fatty acid with an equivalent chain-length of 10.928 and C(12:0) alde). The isoprenoid quinone was Q-8. On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness, strain M-07(T) should be classified as a novel species of the genus Advenella, for which the name Advenella faeciporci sp. nov. is proposed. The type strain is M-07(T) (?= JCM 17746(T) ?= KCTC 23732(T)).

Matsuoka M; Park S; An SY; Miyahara M; Kim SW; Kamino K; Fushinobu S; Yokota A; Wakagi T; Shoun H

2012-12-01

251

Community Composition of NirS-Type Denitrifier in a Shallow Eutrophic Lake.  

UK PubMed Central (United Kingdom)

Denitrification is a major biological process to reduce nitrate to molecular nitrogen (N2). In shallow eutrophic lakes, this process can remove the largest portion of fixed nitrogen and plays an important role in self-purification of this ecosystem. To understand the structure of denitrifying communities in a shallow eutrophic lake, denitrifier communities in four sub-lakes of East Lake in Wuhan, China, were explored by restriction fragment length polymorphisms (RFLP) analysis and sequencing of nirS gene clone libraries. nirS is a functional marker gene for denitrification encoding cytochrome cd 1-containing nitrite reductase, which catalyzes the reduction of nitrite to nitric oxide. Both RFLP fingerprints clustering analysis and phylogeny analysis based on the amino acid sequences of NirS revealed that NirS-type communities in East Lake sediment could be roughly divided into three clusters. Cluster I accounted for 74-82 % of clones from the moderately eutrophic sub-lakes Tuan, Tang Ling, and Guo Zheng. Cluster II accounted for 76 % of the communities in hypertrophic sub-lake Miao Lake and cluster III as a minor group (7 % of the total), mainly presented in Miao Lake. Phylogenetic analysis revealed that cluster I was related to the reference clones from a broad range of ecological environments, and clusters II and III were more phylogenetically related to the reference clones from entrophic environments. Canonical correspondence analysis indicated that total nitrogen, total phosphate, total organic carbon, and NH4-N and NO2-N were important environmental factors affecting the dispersion of NirS-type denitrifier in the sediments. Cluster I showed a weak relationship with the nutrient content, while cluster II and III were positively related with the nutrient content. Principal coordinates analysis indicated that NirS-type communities from Tuan Lake, Tang Ling Lake, and Guo Zheng Lake sediments were divergent from those found in river, estuary sediment, and forest soil but similar to communities in constructed wetland sediment despite large geographic distances. The communities from the hypertrophic sub-lake Miao Lake deviated from other sub-lakes and the reference communities and clustered independently. Our results support the argument that environmental factors regulate the composition and distribution of the functional bacterial groups.

Yang JK; Cheng ZB; Li J; Miao LH

2013-11-01

252

Community Composition of NirS-Type Denitrifier in a Shallow Eutrophic Lake.  

UK PubMed Central (United Kingdom)

Denitrification is a major biological process to reduce nitrate to molecular nitrogen (N2). In shallow eutrophic lakes, this process can remove the largest portion of fixed nitrogen and plays an important role in self-purification of this ecosystem. To understand the structure of denitrifying communities in a shallow eutrophic lake, denitrifier communities in four sub-lakes of East Lake in Wuhan, China, were explored by restriction fragment length polymorphisms (RFLP) analysis and sequencing of nirS gene clone libraries. nirS is a functional marker gene for denitrification encoding cytochrome cd 1-containing nitrite reductase, which catalyzes the reduction of nitrite to nitric oxide. Both RFLP fingerprints clustering analysis and phylogeny analysis based on the amino acid sequences of NirS revealed that NirS-type communities in East Lake sediment could be roughly divided into three clusters. Cluster I accounted for 74-82 % of clones from the moderately eutrophic sub-lakes Tuan, Tang Ling, and Guo Zheng. Cluster II accounted for 76 % of the communities in hypertrophic sub-lake Miao Lake and cluster III as a minor group (7 % of the total), mainly presented in Miao Lake. Phylogenetic analysis revealed that cluster I was related to the reference clones from a broad range of ecological environments, and clusters II and III were more phylogenetically related to the reference clones from entrophic environments. Canonical correspondence analysis indicated that total nitrogen, total phosphate, total organic carbon, and NH4-N and NO2-N were important environmental factors affecting the dispersion of NirS-type denitrifier in the sediments. Cluster I showed a weak relationship with the nutrient content, while cluster II and III were positively related with the nutrient content. Principal coordinates analysis indicated that NirS-type communities from Tuan Lake, Tang Ling Lake, and Guo Zheng Lake sediments were divergent from those found in river, estuary sediment, and forest soil but similar to communities in constructed wetland sediment despite large geographic distances. The communities from the hypertrophic sub-lake Miao Lake deviated from other sub-lakes and the reference communities and clustered independently. Our results support the argument that environmental factors regulate the composition and distribution of the functional bacterial groups.

Yang JK; Cheng ZB; Li J; Miao LH

2013-07-01

253

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

UK PubMed Central (United Kingdom)

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.

Palmer K; Horn MA

2012-08-01

254

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.

1995-01-01

255

[Screening and denitrification characteristics of a heterotrophic nitrification-aerobic denitrifier bacteria].  

Science.gov (United States)

A heterotrophic nitrification-aerobic denitrifier bacteria CPZ24 was isolated form the livestock wastewater by way of the limiting dilution combined with the chromogenic medium screening methods. This bacterium was Gram positive, rod. The colonies of the strain were orange-red.It was identified as Rhodococuus pyridinivorans according to its morphological and physiological properties and the analysis of its 16S rDNA gene. Studied on its function of heterotrophic nitrification and aerobic denitrification,the results show that all NH4+ -N is removed and the removal rate of TN is 98.70% in heterotrophic nitrification; the removal rate of NO3- -N by this strain is 66.74% and the removal rate of TN is 64.27%. This high effective microorganisms with nitrogen removed is able to realize simultaneous nitrification and denitrification. It can perform the whole process of bacteria denitrification independently. PMID:20187396

Chen, Pei-zhen; Wang, Li-gang; Wang, Ying-chun; Li, Ji; Ding, Wei; Ren, Tian-zhi; Li, Shao-peng

2009-12-01

256

[Screening and denitrification characteristics of a heterotrophic nitrification-aerobic denitrifier bacteria].  

UK PubMed Central (United Kingdom)

A heterotrophic nitrification-aerobic denitrifier bacteria CPZ24 was isolated form the livestock wastewater by way of the limiting dilution combined with the chromogenic medium screening methods. This bacterium was Gram positive, rod. The colonies of the strain were orange-red.It was identified as Rhodococuus pyridinivorans according to its morphological and physiological properties and the analysis of its 16S rDNA gene. Studied on its function of heterotrophic nitrification and aerobic denitrification,the results show that all NH4+ -N is removed and the removal rate of TN is 98.70% in heterotrophic nitrification; the removal rate of NO3- -N by this strain is 66.74% and the removal rate of TN is 64.27%. This high effective microorganisms with nitrogen removed is able to realize simultaneous nitrification and denitrification. It can perform the whole process of bacteria denitrification independently.

Chen PZ; Wang LG; Wang YC; Li J; Ding W; Ren TZ; Li SP

2009-12-01

257

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

UK PubMed Central (United Kingdom)

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

Hallin S; Welsh A; Stenström J; Hallet S; Enwall K; Bru D; Philippot L

2012-01-01

258

Anaerobic metabolism of phthalate and other aromatic compounds by a denitrifying bacterium. [Pseudomonas sp  

Energy Technology Data Exchange (ETDEWEB)

The anaerobic metabolism of phthalate and other aromatic compounds by the denitrifying bacterium Pseudomonas sp. strain P136 was studied. Benzoate, cyclohex-1-ene-carboxylate, 2-hydroxycyclohexanecarboxylate, and pimelate were detected as predominant metabolic intermediates during the metabolism of three isomers of phthalate, m-hydroxybenzoate, p-hydroxybenzoate, and cyclohex-3-ene-carboxylate. Inducible acyl-coeznyme A synthetase activities for phthalates, benzoate, cyclohex-1-ene-carboxylate, and cyclohex-3-ene-carboxylate were detected in the cells grown on aromatic compounds. Simultaneous adaptation to these aromatic compounds also occurred. A similar phenomenon was observed in the aerobic metabolism of aromatic compounds by this strain. A new pathway for the anaerobic metabolism of phthalate and a series of other aromatic compounds by this strain was proposed. Some properties of the regulation of this pathway were also discussed.

Nozawa, T.; Maruyama, Y. (Univ. of Tokyo (Japan))

1988-12-01

259

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

Science.gov (United States)

This work evaluated N dynamics that occurs over time within swine slurry composting piles. Real-time quantitative PCR (qPCR) analyzes were conducted to estimate concentrations of bacteria community harboring specific catabolic nitrifying-ammonium monooxygenase (amoA), and denitrifying nitrate- (narG), nitrite- (nirS and nirG), nitric oxide- (norB) and nitrous oxide reductases (nosZ) genes. NH3-N, N2O-N, N2-N emissions represented 15.4 ± 1.9%, 5.4 ± 0.9%, and 79.1 ± 2.0% of the total nitrogen losses, respectively. Among the genes tested, temporal distribution of narG, nirS, and nosZ concentration correlated significantly (pcomposting at field scale the use of these catabolic genes could represent a promising monitoring tool to aid minimize our uncertainties on biological N mass balances in these systems. PMID:23711942

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

2013-05-07

260

Anaerobic degradation of ethylbenzene and other aromatic hydrocarbons by new denitrifying bacteria.  

UK PubMed Central (United Kingdom)

Anaerobic degradation of alkylbenzenes with side chains longer than that of toluene was studied in freshwater mud samples in the presence of nitrate. Two new denitrifying strains, EbN1 and PbN1, were isolated on ethylbenzene and n-propylbenzene, respectively. For comparison, two further denitrifying strains, ToN1 and mXyN1, were isolated from the same mud with toluene and m-xylene, respectively. Sequencing of 16SrDNA revealed a close relationship of the new isolates to Thauera selenatis. The strains exhibited different specific capacities for degradation of alkylbenzenes. In addition to ethylbenzene, strain EbN1 utilized toluene, but not propylbenzene. In contrast, propylbenzene-degrading strain PbN1 did not grow on toluene, but was able to utilize ethylbenzene. Strain ToN1 used toluene as the only hydrocarbon substrate, whereas strain mXyN1 utilized both toluene and m-xylene. Measurement of the degradation balance demonstrated complete oxidation of ethylbenzene to CO2 by strain EbN1. Further characteristic substrates of strains EbN1 and PbN1 were 1-phenylethanol and acetophenone. In contrast to the other isolates, stain mXyN1 did not grow on benzyl alcohol. Benzyl alcohol (also m-methyl-benzyl alcohol) was even a specific inhibitor of toluene and m-xylene utilization by strain mXyN1. None of the strains was able to grow on any of the alkylbenzenes with oxygen as electron acceptor. However, polar aromatic compounds such as benzoate were utilized under both oxic and anoxic conditions. All four isolates grew anaerobically on crude oil. Gas chromatographic analysis of crude oil after growth of strain ToN1 revealed specific depletion of toluene.

Rabus R; Widdel F

1995-02-01

 
 
 
 
261

Anaerobic degradation of ethylbenzene and other aromatic hydrocarbons by new denitrifying bacteria.  

Science.gov (United States)

Anaerobic degradation of alkylbenzenes with side chains longer than that of toluene was studied in freshwater mud samples in the presence of nitrate. Two new denitrifying strains, EbN1 and PbN1, were isolated on ethylbenzene and n-propylbenzene, respectively. For comparison, two further denitrifying strains, ToN1 and mXyN1, were isolated from the same mud with toluene and m-xylene, respectively. Sequencing of 16SrDNA revealed a close relationship of the new isolates to Thauera selenatis. The strains exhibited different specific capacities for degradation of alkylbenzenes. In addition to ethylbenzene, strain EbN1 utilized toluene, but not propylbenzene. In contrast, propylbenzene-degrading strain PbN1 did not grow on toluene, but was able to utilize ethylbenzene. Strain ToN1 used toluene as the only hydrocarbon substrate, whereas strain mXyN1 utilized both toluene and m-xylene. Measurement of the degradation balance demonstrated complete oxidation of ethylbenzene to CO2 by strain EbN1. Further characteristic substrates of strains EbN1 and PbN1 were 1-phenylethanol and acetophenone. In contrast to the other isolates, stain mXyN1 did not grow on benzyl alcohol. Benzyl alcohol (also m-methyl-benzyl alcohol) was even a specific inhibitor of toluene and m-xylene utilization by strain mXyN1. None of the strains was able to grow on any of the alkylbenzenes with oxygen as electron acceptor. However, polar aromatic compounds such as benzoate were utilized under both oxic and anoxic conditions. All four isolates grew anaerobically on crude oil. Gas chromatographic analysis of crude oil after growth of strain ToN1 revealed specific depletion of toluene. PMID:7710331

Rabus, R; Widdel, F

1995-02-01

262

Phylogenetically Diverse Denitrifying and Ammonia-Oxidizing Bacteria in Corals Alcyonium gracillimum and Tubastraea coccinea.  

Science.gov (United States)

To date, the association of coral-bacteria and the ecological roles of bacterial symbionts in corals remain largely unknown. In particular, little is known about the community components of bacterial symbionts of corals involved in the process of denitrification and ammonia oxidation. In this study, the nitrite reductase (nirS and nirK) and ammonia monooxygenase subunit A (amoA) genes were used as functional markers. Diverse bacteria with the potential to be active as denitrifiers and ammonia-oxidizing bacteria (AOB) were found in two East China Sea corals: stony coral Alcyonium gracillimum and soft coral Tubastraea coccinea. The 16S rRNA gene library analysis demonstrated different communities of bacterial symbionts in these two corals of the same location. Nitrite reductase nirK gene was found only in T. coccinea, while both nirK and nirS genes were detected in A. gracillimum, which might be the result of the presence of different bacterial symbionts in these two corals. AOB rather than ammonia-oxidizing archaea were detected in both corals, suggesting that AOB might play an important role in the ammonia oxidation process of the corals. This study indicates that the coral bacterial symbionts with the potential for nitrite reduction and ammonia oxidation might have multiple ecological roles in the coral holobiont, which promotes our understanding of bacteria-mediated nitrogen cycling in corals. To our knowledge, this study is the first assessment of the community structure and phylogenetic diversity of denitrifying bacteria and AOB in corals based on nirK, nirS, and amoA gene library analysis. PMID:23564007

Yang, Shan; Sun, Wei; Zhang, Fengli; Li, Zhiyong

2013-04-06

263

Denitrifying Bacterial Communities Affect Current Production and Nitrous Oxide Accumulation in a Microbial Fuel Cell  

Science.gov (United States)

The biocathodic reduction of nitrate in Microbial Fuel Cells (MFCs) is an alternative to remove nitrogen in low carbon to nitrogen wastewater and relies entirely on microbial activity. In this paper the community composition of denitrifiers in the cathode of a MFC is analysed in relation to added electron acceptors (nitrate and nitrite) and organic matter in the cathode. Nitrate reducers and nitrite reducers were highly affected by the operational conditions and displayed high diversity. The number of retrieved species-level Operational Taxonomic Units (OTUs) for narG, napA, nirS and nirK genes was 11, 10, 31 and 22, respectively. In contrast, nitrous oxide reducers remained virtually unchanged at all conditions. About 90% of the retrieved nosZ sequences grouped in a single OTU with a high similarity with Oligotropha carboxidovorans nosZ gene. nirS-containing denitrifiers were dominant at all conditions and accounted for a significant amount of the total bacterial density. Current production decreased from 15.0 A·m?3 NCC (Net Cathodic Compartment), when nitrate was used as an electron acceptor, to 14.1 A·m?3 NCC in the case of nitrite. Contrarily, nitrous oxide (N2O) accumulation in the MFC was higher when nitrite was used as the main electron acceptor and accounted for 70% of gaseous nitrogen. Relative abundance of nitrite to nitrous oxide reducers, calculated as (qnirS+qnirK)/qnosZ, correlated positively with N2O emissions. Collectively, data indicate that bacteria catalysing the initial denitrification steps in a MFC are highly influenced by main electron acceptors and have a major influence on current production and N2O accumulation.

Vilar-Sanz, Ariadna; Puig, Sebastia; Garcia-Lledo, Arantzazu; Trias, Rosalia; Balaguer, M. Dolors; Colprim, Jesus; Baneras, Lluis

2013-01-01

264

Isolation and functional analysis of denitrifiers in an aquifer with high potential for denitrification.  

UK PubMed Central (United Kingdom)

Aquifers are among the main freshwater sources. The Raigón aquifer is susceptible to contamination, mainly by nitrate and pesticides, such as atrazine, due to increasing agricultural activities in the area. The capacity of indigenous bacteria to attenuate nitrate contamination in different wells of this aquifer was assessed by measuring denitrification rates with either acetate plus succinate or nitrate amendments. Denitrification activity in nitrate-amended assays was significantly higher than in unamended assays, particularly in groundwater from wells where nitrate concentration was 33.5mgL(-1) or lower. Furthermore, groundwater denitrifiers capable of using acetate or succinate as electron donors were isolated, identified by 16S rRNA gene sequencing and evaluated for functional denitrification genes (nirS, nirK and nosZ). Phylogenetic affiliation of 54 isolates showed that all members belonged to nine different genera within the Proteobacteria (Bosea, Ochrobactrum, Azospira, Zoogloea, Acidovorax, Achromobacter, Vogesella, Stenotrophomonas and Pseudomonas). In addition, isolate AR28 that clustered separately from validly described species could potentially belong to a new genus. The majority of the isolates were related to species belonging to previously reported denitrifying genera. However, the phylogeny of the nirS and nosZ genes revealed new sequences of these functional genes. To our knowledge, this is the first isolation and sequencing of the nirS gene from the genus Vogesella, as well as the nosZ gene from the genera Acidovorax and Zoogloea. The results indicated that indigenous bacteria in the Raigón aquifer had the capacity to overcome high nitrate contamination and exhibited functional gene diversity.

Bellini MI; Gutiérrez L; Tarlera S; Scavino AF

2013-10-01

265

Isolation and functional analysis of denitrifiers in an aquifer with high potential for denitrification.  

Science.gov (United States)

Aquifers are among the main freshwater sources. The Raigón aquifer is susceptible to contamination, mainly by nitrate and pesticides, such as atrazine, due to increasing agricultural activities in the area. The capacity of indigenous bacteria to attenuate nitrate contamination in different wells of this aquifer was assessed by measuring denitrification rates with either acetate plus succinate or nitrate amendments. Denitrification activity in nitrate-amended assays was significantly higher than in unamended assays, particularly in groundwater from wells where nitrate concentration was 33.5mgL(-1) or lower. Furthermore, groundwater denitrifiers capable of using acetate or succinate as electron donors were isolated, identified by 16S rRNA gene sequencing and evaluated for functional denitrification genes (nirS, nirK and nosZ). Phylogenetic affiliation of 54 isolates showed that all members belonged to nine different genera within the Proteobacteria (Bosea, Ochrobactrum, Azospira, Zoogloea, Acidovorax, Achromobacter, Vogesella, Stenotrophomonas and Pseudomonas). In addition, isolate AR28 that clustered separately from validly described species could potentially belong to a new genus. The majority of the isolates were related to species belonging to previously reported denitrifying genera. However, the phylogeny of the nirS and nosZ genes revealed new sequences of these functional genes. To our knowledge, this is the first isolation and sequencing of the nirS gene from the genus Vogesella, as well as the nosZ gene from the genera Acidovorax and Zoogloea. The results indicated that indigenous bacteria in the Raigón aquifer had the capacity to overcome high nitrate contamination and exhibited functional gene diversity. PMID:23972399

Bellini, M Inés; Gutiérrez, Lucía; Tarlera, Silvana; Scavino, Ana Fernández

2013-08-21

266

[Diversity and quantification analysis of functional genes in a lab scale denitrifying quinoline-degrading bioreactor].  

UK PubMed Central (United Kingdom)

OBJECTIVE: In order to study the diversity and distribution of Benzoyl coenzyme A reductase (bcrA) and oxygenase components of 1H-2-oxoquinoline 8-monooxygenase (oxoO) gene in a lab scale denitrifying bioreactors for treating quinoline-containing wastewater. METHODS: Genomic microbial DNA was extracted from the biofilm samples of bioreactor. Based on the known oxoO genes sequences in GenBank, we designed primers for oxoO gene amplification. Using our designed oxoO gene primers and a pair of degenerate primers of bcrA gene obtained from literature, we amplified the DNA samples. And the amplicons were used for constructing clone libraries of oxoO and bcrA gene. We also performed quantification analysis of these two genes in bioreactor by using Real-time qPCR method. RESULTS: The quantification analysis showed gradual increase of the bcrA gene abundance and reduction of the oxoO gene abundance along with time. The clone library analysis of these two genes indicated that most clones in bcrA gene clone library having more than 97% sequence similarities to the known bcrA gene of Thauera bacteria and others only having 74% - 86% sequence similarities to bcrA gene sequences. Whereas, only a few clones in the oxoO gene clone library have 99% sequence similarities to that gene of Pseudomonas putida. But the sequences of most clones only distantly related with known oxoO genes. CONCLUSIONS: This study showed a high bcrA and oxoO gene diversity, with some new gene sequences, in the lab scale denitrifying bioreactors. The abundance of bcrA and oxoO gene changed remarkably during the running of bioreactor, and closely related with the performance of bioreactor. Therefore, bcrA and oxoO genes have potential to be used as molecule markers to monitor the process of treating quinoline containing wastewater.

Xia X; Zhang X; Feng H; Zhao L

2010-12-01

267

Denitrifying bacterial communities affect current production and nitrous oxide accumulation in a microbial fuel cell.  

UK PubMed Central (United Kingdom)

The biocathodic reduction of nitrate in Microbial Fuel Cells (MFCs) is an alternative to remove nitrogen in low carbon to nitrogen wastewater and relies entirely on microbial activity. In this paper the community composition of denitrifiers in the cathode of a MFC is analysed in relation to added electron acceptors (nitrate and nitrite) and organic matter in the cathode. Nitrate reducers and nitrite reducers were highly affected by the operational conditions and displayed high diversity. The number of retrieved species-level Operational Taxonomic Units (OTUs) for narG, napA, nirS and nirK genes was 11, 10, 31 and 22, respectively. In contrast, nitrous oxide reducers remained virtually unchanged at all conditions. About 90% of the retrieved nosZ sequences grouped in a single OTU with a high similarity with Oligotropha carboxidovorans nosZ gene. nirS-containing denitrifiers were dominant at all conditions and accounted for a significant amount of the total bacterial density. Current production decreased from 15.0 A · m(-3) NCC (Net Cathodic Compartment), when nitrate was used as an electron acceptor, to 14.1 A · m(-3) NCC in the case of nitrite. Contrarily, nitrous oxide (N2O) accumulation in the MFC was higher when nitrite was used as the main electron acceptor and accounted for 70% of gaseous nitrogen. Relative abundance of nitrite to nitrous oxide reducers, calculated as (qnirS+qnirK)/qnosZ, correlated positively with N2O emissions. Collectively, data indicate that bacteria catalysing the initial denitrification steps in a MFC are highly influenced by main electron acceptors and have a major influence on current production and N2O accumulation.

Vilar-Sanz A; Puig S; García-Lledó A; Trias R; Balaguer MD; Colprim J; Bañeras L

2013-01-01

268

BTEX removal in a horizontal-flow anaerobic immobilized biomass reactor under denitrifying conditions.  

Science.gov (United States)

Because benzene, toluene, ethylbenzene, and xylenes (BTEX) and ethanol are important contaminants present in Brazilian gasoline, it is essential to develop technology that can be used in the bioremediation of gasoline-contaminated aquifers. This paper evaluates the performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor fed with water containing gasoline constituents under denitrifying conditions. Two HAIB reactors filled with polyurethane foam matrices (5 mm cubes, 23 kg/m(3) density and 95 % porosity) for biomass attachment were assayed. The reactor fed with synthetic substrate containing protein, carbohydrates, sodium bicarbonate and BTEX solution in ethanol, at an Hydraulic retention time (HRT) of 13.5 h, presented hydrocarbon removal efficiencies of 99 % at the following initial concentrations: benzene 6.7 mg/L, toluene 4.9 mg/L, m-xylene and p-xylene 7.2 mg/L, ethylbenzene 3.7 mg/L, and nitrate 60 mg N/L. The HAIB reactor fed with gasoline-contaminated water at an HRT of 20 h showed hydrocarbon removal efficiencies of 96 % at the following initial concentrations: benzene, 4.9 mg/L; toluene, 7.2 mg/L; m-xylene, 3.7 mg/L; and nitrate 400 mg N/L. Microbiological observations along the length of the HAIB reactor fed with gasoline-contaminated water confirmed that in the first segment of the reactor, denitrifying metabolism predominated, whereas from the first sampling port on, the metabolism observed was predominantly methanogenic. PMID:22910812

Ribeiro, Rogers; de Nardi, Ivana Ribeiro; Fernandes, Bruna Soares; Foresti, Eugenio; Zaiat, Marcelo

2012-08-22

269

Phylogenetically Diverse Denitrifying and Ammonia-Oxidizing Bacteria in Corals Alcyonium gracillimum and Tubastraea coccinea.  

UK PubMed Central (United Kingdom)

To date, the association of coral-bacteria and the ecological roles of bacterial symbionts in corals remain largely unknown. In particular, little is known about the community components of bacterial symbionts of corals involved in the process of denitrification and ammonia oxidation. In this study, the nitrite reductase (nirS and nirK) and ammonia monooxygenase subunit A (amoA) genes were used as functional markers. Diverse bacteria with the potential to be active as denitrifiers and ammonia-oxidizing bacteria (AOB) were found in two East China Sea corals: stony coral Alcyonium gracillimum and soft coral Tubastraea coccinea. The 16S rRNA gene library analysis demonstrated different communities of bacterial symbionts in these two corals of the same location. Nitrite reductase nirK gene was found only in T. coccinea, while both nirK and nirS genes were detected in A. gracillimum, which might be the result of the presence of different bacterial symbionts in these two corals. AOB rather than ammonia-oxidizing archaea were detected in both corals, suggesting that AOB might play an important role in the ammonia oxidation process of the corals. This study indicates that the coral bacterial symbionts with the potential for nitrite reduction and ammonia oxidation might have multiple ecological roles in the coral holobiont, which promotes our understanding of bacteria-mediated nitrogen cycling in corals. To our knowledge, this study is the first assessment of the community structure and phylogenetic diversity of denitrifying bacteria and AOB in corals based on nirK, nirS, and amoA gene library analysis.

Yang S; Sun W; Zhang F; Li Z

2013-10-01

270

Nitrogen cycling and relationships between ammonia oxidizers and denitrifiers in a clay-loam soil.  

UK PubMed Central (United Kingdom)

This study investigated the effect of municipal solid waste (MSW) compost (0, 50, and 100 t/ha) on N cycling and the microorganisms involved in it, in a clay-loam soil. After a release of nitrates (NO3(-)-N) in the first 6 days after compost incorporation, soil NO3(-)-N content remained constant in all the treatments until day?62, suggesting N immobilization induced by the soil used in this study. Then, soil NO3(-)-N content increased in all treatments and especially in the highest compost dose, providing evidence that immobilization effect has been at least partially relieved. amoA gene copies of ammonia-oxidizing archaea (AOA) and bacteria (AOB) followed the overall pattern of soil NO3(-)-N content; however, no differences were found in amoA gene copies among treatments, except in the last sampling, an effect attributed to the slight differences in the potential nitrification rate among them. Ammonia oxidizer pattern provided evidence that both groups were involved in ammonia oxidation and changes in their abundance can be used as 'indicator' to predict changes in soil nitrification status. Moreover, the strong correlation between AOA and AOB amoA copies (R(2)?=?0.94) and the high slope (13) of the curve suggest that AOA had probably an important role on ammonia oxidation. Denitrifying genes (nirS, nirK, nosZ) also followed the general pattern of soil NO3(-)-N, and they were strongly correlated with both groups of ammonia oxidizers, and particularly AOA, suggesting strong interrelationships among them. Losses of N through denitrification, as they were estimated by total nitrogen, were inversely related to soil NO3(-)-N content. Similar to ammonia oxidizers, denitrifying gene copies did not differ among compost treatments an effect that could be probably explained by the low availability of organic-C in the MSW compost and hence the competition with aerobic heterotrophs.

Paranychianakis NV; Tsiknia M; Giannakis G; Nikolaidis NP; Kalogerakis N

2013-06-01

271

The role of plant type and salinity in the selection for the denitrifying community structure in the rhizosphere of wetland vegetation.  

UK PubMed Central (United Kingdom)

Coastal wetlands, as transient links from terrestrial to marine environments, are important for nitrogen removal by denitrification. Denitrification strongly depends on both the presence of emergent plants and the denitrifier communities selected by different plant species. In this study, the effects of vegetation and habitat heterogeneity on the community of denitrifying bacteria were investigated in nine coastal wetlands in two preserved areas of Spain. Sampling locations were selected to cover a range of salinity (0.81 to 31.3 mS/cm) and nitrate concentrations (0.1 to 303 ?M NO3-), allowing the evaluation of environmental variables that select for denitrifier communities in the rhizosphere of Phragmites sp., Ruppia sp., and Paspalum sp. Potential nitrate reduction rates were found to be dependent on the sampling time and plant species and related to the denitrifier community structure, which was assessed by terminal restriction fragment length polymorphism analysis of the functional genes nirS, nirK and nosZ. The results showed that denitrifier community structure was also governed by plant species and salinity, with significant influences of other variables, such as sampling time and location. Ruppia sp. and Phragmites sp. selected for certain communities, whereas this was not the case for Paspalum sp. The plant species effect was strongest on nirK-type denitrifiers, whereas water carbon content was a significant factor defining the structure of the nosZ-harboring community. The differences recognized using the three functional gene markers indicated that different drivers act on denitrifying populations capable of complete denitrification, compared to the overall denitrifier community. This finding may have implications for emissions of the greenhouse gas nitrous oxide.

Bañeras L; Ruiz-Rueda O; López-Flores R; Quintana XD; Hallin S

2012-06-01

272

Alternative isotope enrichment processes  

Energy Technology Data Exchange (ETDEWEB)

Alternative processes such as gas centrifugation, plasma separation, and laser excited separation are evaluated for use at the ORNL Stable Isotope Enrichment Facility. The applicabiliy of each process to the isotopic enrichment of the calutron feed material and to the selective production of isotopes is determined. The process energy demands are compared to those of the existing facilities. The isotopic enrichment of the feed material prior to a first-pass through the calutrons can result in a significant saving in energy.

Terry, J.W.

1983-01-01

273

Temporal dynamics of ammonia oxidizer (amoA) and denitrifier (nirK) communities in the rhizosphere of a rice ecosystem from Tai Lake region, China  

UK PubMed Central (United Kingdom)

A field experiment was conducted to investigate the abundance and dynamics of ammonia oxidizer (ammonia oxidizing archaea - AOA and ammonia oxidizing bacteria - AOB) and denitrifier communities in the rhizosphere at four growing stages of rice using PCR-denaturing gradient gel electrophoresis (DGGE) and real-time PCR approaches. Rice plantation promoted greater abundance of amoA (AOA and AOB) and nirK (denitrifiers) genes in the rhizosphere than in the bulk soil, showing a profound rhizosphere effect. Rice growing stages significantly affected the structures and abundances of AOB and denitrifier (nirK) communities in the rhizosphere, whereas no effect was observed on the community structure and abundance of AOA in the rhizosphere. Moreover, the amoA gene copy numbers of AOA were more than those of AOB in all soil samples. However, denitrifier (nirK) generally dominated the ammonia oxidizer (amoA) in the rhizosphere during all growth stages, suggesting better adaptability of denitrifier in the rice rhizosphere environment. These results further suggest that AOB and denitrifier (nirK) communities associated with rice rhizosphere are highly dynamic in response to prevailing plant and soil conditions over a rice crop season, whereas AOA showed higher stability throughout the rice growing period.

Hussain Q; Liu Y; Jin Z; Zhang A; Pan G; Li L; Crowley D; Zhang X; Song X; Cui L

2011-06-01

274

Bryocella elongata gen. nov., sp. nov., a member of subdivision 1 of the Acidobacteria isolated from a methanotrophic enrichment culture, and emended description of Edaphobacter aggregans Koch et al. 2008.  

Science.gov (United States)

An aerobic, pink-pigmented, chemo-organotrophic bacterium, designated strain SN10(T), was isolated from a methanotrophic enrichment culture obtained from an acidic Sphagnum peat. This isolate was represented by Gram-negative, non-motile rods that multiply by normal cell division and form rosettes. Strain SN10(T) is an obligately acidophilic, mesophilic bacterium capable of growth at pH 3.2-6.6 (with an optimum at pH 4.7-5.2) and at 6-32 °C (with an optimum at 20-24 °C). The preferred growth substrates are sugars and several heteropolysaccharides of plant and microbial origin, such as pectin, lichenan, fucoidan and gellan gum. While not being capable of growth on C(1) compounds, strain SN10(T) can develop in co-culture with exopolysaccharide-producing methanotrophs by utilization of their capsular material. The major fatty acids determined in strain SN10(T) using the conventional lipid extraction procedure are iso-C(15:0) and C(16:1)?7c. Upon hydrolysis of total cell material, substantial amounts of the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (isodiabolic acid) were also detected. The polar lipids are two phosphohexoses, phosphatidylethanolamine, phosphatidylglycerol and several phospholipids of unknown structure. The major quinone is MK-8. Pigments are carotenoids. The G+C content of the DNA is 60.7 mol%. Strain SN10(T) forms a separate lineage within subdivision 1 of the phylum Acidobacteria and displays 94.0-95.4% 16S rRNA gene sequence similarity to members of the genera Edaphobacter and Granulicella, 93.0-93.7% similarity to members of the genus Terriglobus and 92.2-92.3?% similarity to the type strains of Telmatobacter bradus and Acidobacterium capsulatum. Therefore, strain SN10(T) is classified within a novel genus and species, for which the name Bryocella elongata gen. nov., sp. nov. is proposed. Strain SN10(T) (=LMG 25276(T) =DSM 22489(T)) is the type strain of Bryocella elongata. An emended description of Edaphobacter aggregans Koch et al. 2008 is also given. PMID:21551329

Dedysh, Svetlana N; Kulichevskaya, Irina S; Serkebaeva, Yulia M; Mityaeva, Maria A; Sorokin, Vladimir V; Suzina, Natalia E; Rijpstra, W Irene C; Damsté, Jaap S Sinninghe

2011-05-06

275

Bryocella elongata gen. nov., sp. nov., a member of subdivision 1 of the Acidobacteria isolated from a methanotrophic enrichment culture, and emended description of Edaphobacter aggregans Koch et al. 2008.  

UK PubMed Central (United Kingdom)

An aerobic, pink-pigmented, chemo-organotrophic bacterium, designated strain SN10(T), was isolated from a methanotrophic enrichment culture obtained from an acidic Sphagnum peat. This isolate was represented by Gram-negative, non-motile rods that multiply by normal cell division and form rosettes. Strain SN10(T) is an obligately acidophilic, mesophilic bacterium capable of growth at pH 3.2-6.6 (with an optimum at pH 4.7-5.2) and at 6-32 °C (with an optimum at 20-24 °C). The preferred growth substrates are sugars and several heteropolysaccharides of plant and microbial origin, such as pectin, lichenan, fucoidan and gellan gum. While not being capable of growth on C(1) compounds, strain SN10(T) can develop in co-culture with exopolysaccharide-producing methanotrophs by utilization of their capsular material. The major fatty acids determined in strain SN10(T) using the conventional lipid extraction procedure are iso-C(15:0) and C(16:1)?7c. Upon hydrolysis of total cell material, substantial amounts of the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (isodiabolic acid) were also detected. The polar lipids are two phosphohexoses, phosphatidylethanolamine, phosphatidylglycerol and several phospholipids of unknown structure. The major quinone is MK-8. Pigments are carotenoids. The G+C content of the DNA is 60.7 mol%. Strain SN10(T) forms a separate lineage within subdivision 1 of the phylum Acidobacteria and displays 94.0-95.4% 16S rRNA gene sequence similarity to members of the genera Edaphobacter and Granulicella, 93.0-93.7% similarity to members of the genus Terriglobus and 92.2-92.3?% similarity to the type strains of Telmatobacter bradus and Acidobacterium capsulatum. Therefore, strain SN10(T) is classified within a novel genus and species, for which the name Bryocella elongata gen. nov., sp. nov. is proposed. Strain SN10(T) (=LMG 25276(T) =DSM 22489(T)) is the type strain of Bryocella elongata. An emended description of Edaphobacter aggregans Koch et al. 2008 is also given.

Dedysh SN; Kulichevskaya IS; Serkebaeva YM; Mityaeva MA; Sorokin VV; Suzina NE; Rijpstra WI; Damsté JS

2012-03-01

276

Association of earthworm-denitrifier interactions with increased emission of nitrous oxide from soil mesocosms amended with crop residue.  

Science.gov (United States)

Earthworm activity is known to increase emissions of nitrous oxide (N(2)O) from arable soils. Earthworm gut, casts, and burrows have exhibited higher denitrification activities than the bulk soil, implicating priming of denitrifying organisms as a possible mechanism for this effect. Furthermore, the earthworm feeding strategy may drive N(2)O emissions, as it determines access to fresh organic matter for denitrification. Here, we determined whether interactions between earthworm feeding strategy and the soil denitrifier community can predict N(2)O emissions from the soil. We set up a 90-day mesocosm experiment in which (15)N-labeled maize (Zea mays L.) was either mixed in or applied on top of the soil in the presence or absence of the epigeic earthworm Lumbricus rubellus and/or the endogeic earthworm Aporrectodea caliginosa. We measured N(2)O fluxes and tested the bulk soil for denitrification enzyme activity and the abundance of 16S rRNA and denitrifier genes nirS and nosZ through real-time quantitative PCR. Compared to the control, L. rubellus increased denitrification enzyme activity and N(2)O emissions on days 21 and 90 (day 21, P = 0.034 and P = 0.002, respectively; day 90, P = 0.001 and P = 0.007, respectively), as well as cumulative N(2)O emissions (76%; P = 0.014). A. caliginosa activity led to a transient increase of N(2)O emissions on days 8 to 18 of the experiment. Abundance of nosZ was significantly increased (100%) on day 90 in the treatment mixture containing L. rubellus alone. We conclude that L. rubellus increased cumulative N(2)O emissions by affecting denitrifier community activity via incorporation of fresh residue into the soil and supplying a steady, labile carbon source. PMID:21515716

Nebert, Lucas D; Bloem, Jaap; Lubbers, Ingrid M; van Groenigen, Jan Willem

2011-04-22

277

Association of earthworm-denitrifier interactions with increased emission of nitrous oxide from soil mesocosms amended with crop residue.  

UK PubMed Central (United Kingdom)

Earthworm activity is known to increase emissions of nitrous oxide (N(2)O) from arable soils. Earthworm gut, casts, and burrows have exhibited higher denitrification activities than the bulk soil, implicating priming of denitrifying organisms as a possible mechanism for this effect. Furthermore, the earthworm feeding strategy may drive N(2)O emissions, as it determines access to fresh organic matter for denitrification. Here, we determined whether interactions between earthworm feeding strategy and the soil denitrifier community can predict N(2)O emissions from the soil. We set up a 90-day mesocosm experiment in which (15)N-labeled maize (Zea mays L.) was either mixed in or applied on top of the soil in the presence or absence of the epigeic earthworm Lumbricus rubellus and/or the endogeic earthworm Aporrectodea caliginosa. We measured N(2)O fluxes and tested the bulk soil for denitrification enzyme activity and the abundance of 16S rRNA and denitrifier genes nirS and nosZ through real-time quantitative PCR. Compared to the control, L. rubellus increased denitrification enzyme activity and N(2)O emissions on days 21 and 90 (day 21, P = 0.034 and P = 0.002, respectively; day 90, P = 0.001 and P = 0.007, respectively), as well as cumulative N(2)O emissions (76%; P = 0.014). A. caliginosa activity led to a transient increase of N(2)O emissions on days 8 to 18 of the experiment. Abundance of nosZ was significantly increased (100%) on day 90 in the treatment mixture containing L. rubellus alone. We conclude that L. rubellus increased cumulative N(2)O emissions by affecting denitrifier community activity via incorporation of fresh residue into the soil and supplying a steady, labile carbon source.

Nebert LD; Bloem J; Lubbers IM; van Groenigen JW

2011-06-01

278

Association of Earthworm-Denitrifier Interactions with Increased Emission of Nitrous Oxide from Soil Mesocosms Amended with Crop Residue? †  

Science.gov (United States)

Earthworm activity is known to increase emissions of nitrous oxide (N2O) from arable soils. Earthworm gut, casts, and burrows have exhibited higher denitrification activities than the bulk soil, implicating priming of denitrifying organisms as a possible mechanism for this effect. Furthermore, the earthworm feeding strategy may drive N2O emissions, as it determines access to fresh organic matter for denitrification. Here, we determined whether interactions between earthworm feeding strategy and the soil denitrifier community can predict N2O emissions from the soil. We set up a 90-day mesocosm experiment in which 15N-labeled maize (Zea mays L.) was either mixed in or applied on top of the soil in the presence or absence of the epigeic earthworm Lumbricus rubellus and/or the endogeic earthworm Aporrectodea caliginosa. We measured N2O fluxes and tested the bulk soil for denitrification enzyme activity and the abundance of 16S rRNA and denitrifier genes nirS and nosZ through real-time quantitative PCR. Compared to the control, L. rubellus increased denitrification enzyme activity and N2O emissions on days 21 and 90 (day 21, P = 0.034 and P = 0.002, respectively; day 90, P = 0.001 and P = 0.007, respectively), as well as cumulative N2O emissions (76%; P = 0.014). A. caliginosa activity led to a transient increase of N2O emissions on days 8 to 18 of the experiment. Abundance of nosZ was significantly increased (100%) on day 90 in the treatment mixture containing L. rubellus alone. We conclude that L. rubellus increased cumulative N2O emissions by affecting denitrifier community activity via incorporation of fresh residue into the soil and supplying a steady, labile carbon source.

Nebert, Lucas D.; Bloem, Jaap; Lubbers, Ingrid M.; van Groenigen, Jan Willem

2011-01-01

279

Direct seeding mulch-based cropping increases both the activity and the abundance of denitrifier communities in a tropical soil  

UK PubMed Central (United Kingdom)

This study evaluated the impact of direct seeding mulch-based cropping (DMC), as an alternative to conventional tilling (CT), on a functional community involved in N cycling and emission of greenhouse gas nitrous oxide (N2O). The study was carried out for annual soybean/rice crop rotation in the Highlands of Madagascar. The differences between the two soil management strategies (direct seeding with mulched crop residues versus tillage without incorporation of crop residues) were studied along a fertilization gradient (no fertilizer, organic fertilizer, organic plus mineral fertilizers). The activity and size of the denitrifier community were determined by denitrification enzyme activity assays and by real-time PCR quantification of the denitrification genes. Denitrification activity and total C and N content in the soil were significantly increased by DMC both years, whereas the fertilization regime and sampling year (crop and mulch types, climatic conditions) had very little effect. Similar results were also observed for denitrification gene densities. Denitrification enzyme activity was more closely correlated with C content than with N content in the soil and denitrification gene densities. Principal component analysis confirmed that soil management had the strongest impact on the soil denitrifier community and total C and N content for both years and further indicated that changes in microbial and chemical soil parameters induced by the use of fertilizer were favored in DMC plots. Overall, the alternative DMC system had a significant positive effect on denitrifier densities and potential activities, which was not altered by crop rotation and the level of fertilization. These data also suggest that in these clayey soils, the DMC system simultaneously increased the size of the soil N pool and accelerated the N cycle, by stimulating the denitrifier community. Complementary investigations should further determine in greater detail the influence of DMC on in situ N-fluxes caused by denitrification.

Baudoin Eze?kiel; Philippot Laurent; Che?neby Dominique; Chapuis-Lardy Lydie; Fromin Nathalie; Bru David; Rabary Bodovololona; Brauman Alain

2009-08-01

280

Studies on the enrichment culture of hydrocarbon oxidizing bacteria for MEOR. Part 4. ; Utilization of 2F-NW 8901 bacterium. Sekiyu no zokaishu wo mokuteki to shita tanka suiso riyokin no shuseki baiyo ni kansuru kenkyu. 4. ; 2F-NW 8901 kinkabu no riyo ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

The present report explains study of the promising 2F-NW 8901 bacterium which has crude oil utilized as a carbon/energy source in the oil reservoir for the microbial enhanced oil recovery (MEOR). The study was made of the condition for enrichment culture of the present bacterium to increase the oil recovery, dependency of enrichment on the oxygen and sugar-based matter, and previously reported condition for culture in the oil reservoir. For the active growth of bacterium, it is necessary to supply air by pneumatic or other transmission. It is not necessary to add sugar. The bacterium grows rapidly and lives even in an anaerobic ambience so that a short-time cyclic air feed is sufficient for its growth. In the process of hydrocarbon oxidation, surface active agent is produced as a sole metabolite. It is effective in promoting the MEOR to add yeast extract or its alternate to the liquid medium. In the general oil reservoir water, the ionic concentration of Fe[sup 2+] is lower than that required for the growth of bacterium so that the ionic addition of Fe[sup 2+] is effective in enriching the bacterium. Because of its resistivity to Al[sup 3-]to a certain extent, the bacterium can serve for the condensation culture and control the other microbes. 4 refs., 6 figs., 4 tabs.

Kinoshita, A. (Nippon Steel Corp., Tokyo (Japan)); Enomoto, H.; Chida, T. (Tohoku University, Sendai (Japan). Faculty of Engineering)

1994-03-01

 
 
 
 
281

Activity of denitrifying bacteria on the biological activated carbon; Seibutsu kasseitan ni okeru datsuchisso saikin no kassei  

Energy Technology Data Exchange (ETDEWEB)

The effect of the adsorption capacity of activated carbon in biological activated carbon (BAC) in a fluidized bed reactor on denitrifying activity is studied through experimentation. Experiments are conducted, which cover continuous denitrification, adsorption capacity of activated carbon and artificial light aggregate (ALA), batch-based adsorption performance of BAC in a continuous reactor at its steady state, measurement of the number of bacteria, and batch-based denitrifying activity. Findings obtained are as stated hereunder. BAC at the steady state exhibits an adsorption capacity as high as 80.0-81.2% of that of new activated carbon, and the adsorption rate 48.3% of that of the same. In BAC, adsorption capacity and rate are lower when the biological membrane is thicker. The adhesion of protein per milligram to ALA and that to BAC are approximately the same in the same empty bed contact time (EBCT), and the number of bacteria per milligram of protein is approximately the same irrespective of the kinds of EBCTs or carriers. The reduction of nitric acid and nitrous acid in denitrifying reaction may be described by means of a first-order reaction, and it is found that in all EBCTs the nitrous acid reduction rate is approximately two times higher than the nitric acid reduction rate. 31 refs., 11 figs., 2 tabs.

Miyahara, T.; Noike, T. [Tohoku University, Sendai (Japan); Kim, D.

1998-02-22

282

A Cultural Classroom Library  

Science.gov (United States)

Native American and other cultural stories provide students with a broader perspective on the world. In addition, cultural stories connect science content and knowledge about the world to cultural interpretations and people's life ways. By implementing the ideas suggested in this article, you can select books that both enrich your science library and help students begin to appreciate the science contributions and connections from various cultures while enhancing cultural literacy among students.

Lawrence, Maria

2007-11-01

283

Removal of pharmaceutical and personal care products (PPCPs) under nitrifying and denitrifying conditions.  

UK PubMed Central (United Kingdom)

The contribution of volatilization, sorption and transformation to the removal of 16 Pharmaceutical and Personal Care Products (PPCPs) in two lab-scale conventional activated sludge reactors, working under nitrifying (aerobic) and denitrifying (anoxic) conditions for more than 1.5 years, have been assessed. Pseudo-first order biological degradation rate constants (k(biol)) were calculated for the selected compounds in both reactors. Faster degradation kinetics were measured in the nitrifying reactor compared to the denitrifying system for the majority of PPCPs. Compounds could be classified according to their k(biol) into very highly (k(biol)>5Lg(SS)(-1)d(-1)), highly (175%) and anoxic (>65%) conditions, whereas naproxen (NPX), ethinylestradiol (EE2), roxithromycin (ROX) and erythromycin (ERY) were only significantly transformed in the aerobic reactor (>80%). The anti-depressant citalopram (CTL) was moderately biotransformed under both, aerobic and anoxic conditions (>60% and >40%, respectively). Some compounds, as carbamazepine (CBZ), diazepam (DZP), sulfamethoxazole (SMX) and trimethoprim (TMP), manifested high resistance to biological transformation. Solids Retention Time (SRT(aerobic) >50d and <50d; SRT(anoxic) >20d and <20d) had a slightly positive effect on the removal of FLX, NPX, CTL, EE2 and natural estrogens (increase in removal efficiencies <10%). Removal of diclofenac (DCF) in the aerobic reactor was positively affected by the development of nitrifying biomass and increased from 0% up to 74%. Similarly, efficient anoxic transformation of ibuprofen (75%) was observed after an adaptation period of 340d. Temperature (16-26 degrees C) only had a slight effect on the removal of CTL which increased in 4%.

Suarez S; Lema JM; Omil F

2010-05-01

284

Uranium conversion and enrichment  

International Nuclear Information System (INIS)

A description is given of the Atomic Energy Corporation's uranium conversion and enrichment plants at Valinda ba, including a brief discussion of problems encountered and plans for future developments. (author)

1990-01-01

285

Uranium conversion and enrichment  

International Nuclear Information System (INIS)

The uranium conversion and enrichment plants of the Atomic Energy Corporation of South Africa are described. A brief discussion of the problems encountered at the plants and the plans for future development are included. 3 refs., 6 figs.

1990-01-01

286

Uranium enrichment plant  

International Nuclear Information System (INIS)

The invention is concerned with improvements in the separating nozzle approach to uranium enrichment employing an upright column of tower-like construction formed as a wholly vacuum-tight partitioned container

1976-09-22

287

The ammonia oxidizing and denitrifying prokaryotes associated with sponges from different sea areas.  

Science.gov (United States)

Marine sponges have been suggested to play an important role in the marine nitrogen cycling. However, the role of sponge microbes in the nitrogen transformation remains limited, especially on the bacterial ammonia oxidization and denitrification. Hence, in the present study, using functional genes (amoA, nirS, nirK, and nxrA) involved in ammonia oxidization and denitrification and 16S rRNA genes for specific bacterial groups as markers, phylogenetically diverse prokaryotes including bacteria and archaea, which may be involved in the ammonia oxidization and denitrification processes in sponges, were revealed in seven sponge species. Ammonia oxidizers were found in all species, whereas three sponges (Placospongia sp., Acanthella sp., and Pericharax heteroraphis) harbor only ammonia-oxidizing bacteria (AOB), two sponges (Spirastrellidae diplastrella and Mycale fibrexilis) host only ammonia-oxidizing archaea (AOA), while the remaining two sponges (Haliclona sp. and Lamellomorpha sp.) harbor both AOB and AOA. S. diplastrella and Lamellomorpha sp. also harbor denitrifying bacteria. Nitrite reductase gene nirK was detected only in Lamellomorpha sp. with higher phylogenetic diversity than nirS gene observed only in S. diplastrella. The detected functional genes related to the ammonia oxidization and nitrite reduction in deep-sea and shallow-water sponges highlighted the potential ecological roles of prokaryotes in sponge-related nitrogen transformation. PMID:23435827

Han, Minqi; Li, Zhiyong; Zhang, Fengli

2013-02-23

288

Nitrifiers and denitrifiers respond rapidly to changed moisture and increasing temperature in a pristine forest soil.  

UK PubMed Central (United Kingdom)

Complete cycling of mineral nitrogen (N) in soil requires the interplay of microorganisms performing nitrification and denitrification, whose activity is increasingly affected by extreme rainfall or heat brought about by climate change. In a pristine forest soil, a gradual increase in soil temperature from 5 to 25 degrees C in a range of water contents stimulated N turnover rates, and N gas emissions were determined by the soil water-filled pore space (WFPS). NO and N(2)O emissions dominated at 30% WFPS and 55% WFPS, respectively, and the step-wise temperature increase resulted in a threefold increase in the NO(3)(-) concentrations and a decrease in the NH(4)(+) concentration. At 70% WFPS, NH(4)(+) accumulated while NO(3)(-) pools declined, indicating gaseous N loss. AmoA- and nirK-gene-based analysis revealed increasing abundance of bacterial ammonia oxidizers (AOB) with increasing soil temperature and a decrease in the abundance of archaeal ammonia oxidizers (AOA) in wet soil at 25 degrees C, suggesting the sensitivity of the latter to anaerobic conditions. Denitrifier (nirK) community structure was most affected by the water content and nirK gene abundance rapidly increased in response to wet conditions until the substrate (NO(3)(-)) became limiting. Shifts in the community structure were most pronounced for nirK and most rapid for AOA, indicating dynamic populations, whereas distinct adaptation of the AOB communities required 5 weeks, suggesting higher stability.

Szukics U; Abell GC; Hödl V; Mitter B; Sessitsch A; Hackl E; Zechmeister-Boltenstern S

2010-06-01

289

Characteristics of denitrifying granular sludge grown on nitrite medium in an upflow sludge blanket (USB) reactor.  

UK PubMed Central (United Kingdom)

While inoculating pre-acclimatized floccular sludge, nitrite-denitrifying granular sludge was obtained after approximately 40 days of cultivation in a 10 L upflow sludge blanket (USB) reactor. The nitrite removal efficiency was approximately 95% when the nitrite concentration was 50 mg L(-1)at an influent flow rate of 20 L h(-1). The nitrite granular sludge had several notable features including good settleability (110 m h(-1)), high ash content (79%), and high density (1.248 g cm(-3)). The mixed liquor suspended solids (MLSS) of the sludge bed remained at 130.04 g L(-1), at a hydraulic upflow velocity of 2 m h(-1). These interesting characteristics were attributed to a high effluent pH (9.7) caused by the release of alkalinity during the nitrite denitrification process. The surfaces of the granules were dominated by cocci bacteria with a diameter of approximately 3 ?m, which could be classi?ed as Nitrosomonas-like species based on our analysis of 16 S rDNA sequences.

Jin X; Wang F; Liu G; Liu Y

2012-01-01

290

Ultrastructure of the denitrifying methanotroph "Candidatus Methylomirabilis oxyfera," a novel polygon-shaped bacterium.  

Science.gov (United States)

"Candidatus Methylomirabilis oxyfera" is a newly discovered denitrifying methanotroph that is unrelated to previously known methanotrophs. This bacterium is a member of the NC10 phylum and couples methane oxidation to denitrification through a newly discovered intra-aerobic pathway. In the present study, we report the first ultrastructural study of "Ca. Methylomirabilis oxyfera" using scanning electron microscopy, transmission electron microscopy, and electron tomography in combination with different sample preparation methods. We observed that "Ca. Methylomirabilis oxyfera" cells possess an atypical polygonal shape that is distinct from other bacterial shapes described so far. Also, an additional layer was observed as the outermost sheath, which might represent a (glyco)protein surface layer. Further, intracytoplasmic membranes, which are a common feature among proteobacterial methanotrophs, were never observed under the current growth conditions. Our results indicate that "Ca. Methylomirabilis oxyfera" is ultrastructurally distinct from other bacteria by its atypical cell shape and from the classical proteobacterial methanotrophs by its apparent lack of intracytoplasmic membranes. PMID:22020652

Wu, Ming L; van Teeseling, Muriel C F; Willems, Marieke J R; van Donselaar, Elly G; Klingl, Andreas; Rachel, Reinhard; Geerts, Willie J C; Jetten, Mike S M; Strous, Marc; van Niftrik, Laura

2011-10-21

291

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

UK PubMed Central (United Kingdom)

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.

Tang Y; Ontiveros-Valencia A; Feng L; Zhou C; Krajmalnik-Brown R; Rittmann BE

2013-03-01

292

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

2012-11-01

293

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

Science.gov (United States)

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 dilution (APD) methods and compared in this study. The proportion of denitrifying bacteria in the total isolates was more than 6-fold larger with FSC isolation (57.1%) compared with the APD method (9.2%). Denitrifying bacteria belonging to Alphaproteobacteria and Bacilli were commonly isolated using both methods, whereas those belonging to Betaproteobacteria, which had been found to be active in the denitrification-inductive paddy soil, were isolated only with the FSC method. On the other hand, Actinobacteria were only isolated using the APD method. The mean potential denitrification activity of the FSC isolates was higher than that of the APD isolates. Overall, FSC isolation was confirmed to be an excellent method for studying denitrifying bacteria compared with the standard agar plate dilution method. PMID:22985609

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

2012-09-18

294

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

UK PubMed Central (United Kingdom)

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 dilution (APD) methods and compared in this study. The proportion of denitrifying bacteria in the total isolates was more than 6-fold larger with FSC isolation (57.1%) compared with the APD method (9.2%). Denitrifying bacteria belonging to Alphaproteobacteria and Bacilli were commonly isolated using both methods, whereas those belonging to Betaproteobacteria, which had been found to be active in the denitrification-inductive paddy soil, were isolated only with the FSC method. On the other hand, Actinobacteria were only isolated using the APD method. The mean potential denitrification activity of the FSC isolates was higher than that of the APD isolates. Overall, FSC isolation was confirmed to be an excellent method for studying denitrifying bacteria compared with the standard agar plate dilution method.

Nishizawa T; Tago K; Uei Y; Ishii S; Isobe K; Otsuka S; Senoo K

2012-01-01

295

Influences of quinclorac on culturable microorganisms and soil respiration in flooded paddy soil.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To investigate the potential effects of herbicide quinclorac (3,7-dichloro-8-quinoline-carboxylic) on the culturable microorganisms in flooded paddy soil. METHODS: Total soil aerobic bacteria, actinomycetes and fungi were counted by a 10-fold serial dilution plate technique. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN) methods with anaerobic liquid enrichment media. The number of methanogenic bacteria (MB) and nitrogen-fixing bacteria (NFB) was determined by the rolling tube method in triplicate. Soil respiration was monitored by a 102G-type gas chromatography with a stainless steel column filled with GDX-104 and a thermal conductivity detector. RESULTS: Quinclorac concentration was an important factor affecting the populations of various culturable microorganisms. There were some significant differences in the aerobic heterotrophic bacteria. AFB and DNB between soils were supplemented with quinclorac and non-quinclorac at the early stage of incubation, but none of them was persistent. The number of fungi and DNB was increased in soil samples treated by lower than 1.33 micro x g(-1) dried soil, while the CFU of fungi and HPAB was inhibited in soil samples treated by higher than 1.33 microg x g(-1) dried soil. The population of actinomycete declined in negative proportion to the concentrations of quinclorac applied after 4 days. However, application of quinclorac greatly stimulated the growth of AFB and NFB. MB was more sensitive to quinclorac than the others, and the three soil samples with concentrations higher than 1 microg x g(-1) dried soil declined significantly to less than 40% of that in the control, but the number of samples with lower concentrations of quinclorac was nearly equal to that in the control at the end of experiments. CONCLUSION: Quinclorac is safe to the soil microorganisms when applied at normal concentrations (0.67 microg x g(-1)).

Lu ZM; Min H; Ye YF

2003-12-01

296

Oxygen enrichment incineration  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2000-10-01

297

FCC regenerator oxygen enrichment  

Energy Technology Data Exchange (ETDEWEB)

A direct, cost-effective method to debottleneck cracking units, which are constrained by air-blower capacity, velocity or pressure considerations in the regenerator or downstream units, or coke combustion kinetics, is to enrich the combustion air with a higher purity oxygen gas stream. Presented in this paper are: (1) a summary of the recent advances in air separations technology for the production of medium-purity oxygen, which combined with the increasing requirement for higher sulfur recovery in refineries, have considerably improved the economic benefits of using oxygen-enriched air, (2) a summary of materials combustibility studies targeted at safety considerations for refining application, especially catalytic cracking, and (3) a summary of laboratory studies which were aimed at understanding the effect of oxygen enrichment on regenerator nitrogen and sulfur chemistry.

Menon, R.; Hull, R.; Tamhankar, S.; Ramachandran, R. [BOC Group, Murray Hill, NJ (United States); Watson, R. [BOC Gases-Europe, Guildford (United Kingdom)

1995-09-01

298

Sub-parts-per-billion nitrate method: use of an N2O-producing denitrifier to convert NO2- or 15NO2- to N2O  

International Nuclear Information System (INIS)

[en] A sensitive analytical method for NO2- was developed based on the conversion of NO2- to N2O by a denitrifier that could not reduce N2O further. The improved detectability resulted from the high sensitivity of the 63Ni electron capture gas chromatographic detector for N2O and the purification of the nitrogen afforded by the transformation of the N to a gaseous product with a low atmospheric background. The selected denitrifier quantitatively converted NO3- to N2O within 10 min. The optimum measurement range was from 0.5 to 50 ppb (50 +g/liter) of NO3- N, and the detection limit was 0.2 ppm of N. To illustrate the use of the denitrifier method, NO3- concentrations of 3- N were measured in distilled and deionized purified water samples and in anaerobic lake water samples, but were not detected at the surface of the sediment. The denitrifier method was also used to measure the atom% of 15N in NO3-. This method avoids the incomplete reduction and contamination of the NO3--N by the NH4+ and N2 pools which can occur by the conventional method of 15NO3- analysis. N2O-producing denitrifier strains were also used to measure the apparent K/sub m/ values for NO3- use by these organisms. Analysis of N2O production by use of a progress curve yielded K/sub m/ values of 1.7 and 1.8 ?M NO3- for the two denitrifier strains studied

1988-01-01

299

Many forms of culture.  

UK PubMed Central (United Kingdom)

Psychologists interested in culture have focused primarily on East-West differences in individualism-collectivism, or independent-interdependent self-construal. As important as this dimension is, there are many other forms of culture with many dimensions of cultural variability. Selecting from among the many understudied cultures in psychology, the author considers three kinds of cultures: religion, socioeconomic status, and region within a country. These cultures vary in a number of psychologically interesting ways. By studying more types of culture, psychologists stand to enrich how they define culture, how they think about universality and cultural specificity, their views of multiculturalism, how they do research on culture, and what dimensions of culture they study. Broadening the study of culture will have far-reaching implications for clinical issues, intergroup relations, and applied domains.

Cohen AB

2009-04-01

300

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

1986-01-01

 
 
 
 
301

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

Science.gov (United States)

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

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

2010-12-01

302

Method for producing germanium-enriched glossy ganoderma mycelium  

UK PubMed Central (United Kingdom)

The invention discloses a method for producing germanium-enriched glossy ganoderma mycelium, which is characterized by comprising the steps: germanium-enriched maize soak solution is prepared the germanium-enriched maize soak solution is added with carbon source, nitrogen source, medium elements and bean oil to prepare culture medium which is then sterilized and cooled glossy ganoderma liquid spawn cultured by an inclined plane is inoculated in the culture medium, and the strain is cultured until the glossy ganoderma mycelium is generated. Organic germanium element (maize germanium) can be converted into glossy ganoderma germanium biological macromolecule, so that the content of the organic germanium in the glossy ganoderma can be obviously increased, and the glossy ganoderma can fully exert the function of the organic germanium on the premise of effectively exerting the function of ganoderma lucidum polysaccharide.

PING YANG; XINGUO TAN

303

Enriched Reedy categories  

CERN Document Server

We define the notion of an enriched Reedy category, and show that if A is a C-Reedy category for some symmetric monoidal model category C and M is a C-model category, the category of C-functors and C-natural transformations from A to M is again a model category.

Angeltveit, V

2006-01-01

304

Enrichment: Dealing with overcapacity  

Energy Technology Data Exchange (ETDEWEB)

Today`s surplus of enrichment capacity will continue until at least the end of this century. This will challenge the ingenuity of the SWU suppliers as they attempt to keep market share and remain profitable in a very competitive marketplace. The utilities will be faced with attractive choices, but making the best choice will require careful analysis and increased attention to market factors. National markets served by many government-controlled enrichment suppliers have replaced the international market dominance that the US Government once enjoyed. Today customers give their national suppliers special preference. A customer`s loyalty may arise out of equity participation in the producer, nationalistic feelings, a position as a subcontractor, or simply a preference for firms serving the local area. The suppliers with relatively secure national markets include URANSERVICE in the USSR and in the eastern European countries; China Nuclear Energy Industry Corporation in the Peoples Republic of China; EURODIF in France, Italy, Spain, and Belgium; URENCO in the United Kingdom, The Netherlands, and Germany; and the domestic suppliers in Japan, Argentina, Brazil, and South Africa. Competition in the SWU market is concentrated in the USA where the US DOE may not be able to maintain its traditional share of its domestic market, and in countries that are not self-sufficient in enrichment. Competition also exists in the countries served by EURODIF and URENCO, but the uncommitted market is smaller and the enrichment suppliers are maintaining a high degree of customer loyalty.

NONE

1988-12-01

305

Toxicology Enrichment Materials  

Science.gov (United States)

The series contains fact sheets on toxicology, introductory exercises to familiarize students with the study of toxicology and student assignments addressing specific issues in toxicology. The assignments are designed to enrich typical course curricula and give students practice using information from both library and internet sources.

Suzanne Conklin (Rhode Island College;)

2007-06-14

306

Availability of enrichment services  

International Nuclear Information System (INIS)

The report summarizes major uncertainties which are likely to influence future demands for uranium isotopic enrichment. Since for the next decade the development of nuclear power will be largely concerned with the increment in demand the timely need for enrichment capacity will be particularly sensitive to assumptions about growth rates. Existing worldwide capacity together with capacities under construction will be sufficient well into the 1980's. However, long decision and construction leadtime, uncertainty as to future demand as well as other factors, specifically high capital need, all of which entail financial risks, create hindrances to a timely development of increment. The adequacy of current technology is well demonstrated in plant operation and new technology is under way. Technology is, however, not freely available on a purely commercial basis. Commercial willingness, which anticipates a limited degree of financial risk, is requesting both long term back-up from the utilities that would parallel their firm decisions on the acquisition of nuclear power units, and a protective government umbrella. This situation depends on the symbiotic relationship that exists between the nuclear power generating organizations, the enrichment undertakings and the governments involved. The report accordingly stresses the need for a more cooperative approach and this, moreover, at the multinational level. There is otherwise a risk that proper resources and financing means will not be allocated to the enrichment sector. Export limitations that request the highest degree of industrial processing of nuclear fuel, i.e. the compulsory enrichment of natural uranium, do not serve the interests of overall industrial efficiency

1977-05-13

307

A two-stage aerobic/anaerobic denitrifying horizontal bioreactor designed for treating ammonium and H(2)S simultaneously.  

UK PubMed Central (United Kingdom)

A two-stage bioreactor was operated for a period of 140 days in order to develop a post-treatment process based on anaerobic bioxidation of sulfite. This process was designed for simultaneously treating the effluent and biogas of a full-scale UASB reactor, containing significant concentrations of NH(4) and H(2)S, respectively. The system comprised of two horizontal-flow bed-packed reactors operated with different oxygen concentrations. Ammonium present in the effluent was transformed into nitrates in the first aerobic stage. The second anaerobic stage combined the treatment of nitrates in the liquor with the hydrogen sulfide present in the UASB-reactor biogas. Nitrates were consumed with a significant production of sulfate, resulting in a nitrate removal rate of 0.43 kgNm(3)day(-1) and ?92 % efficiency. Such a removal rate is comparable to those achieved by heterotrophic denitrifying systems. Polymeric forms of sulfur were not detected (elementary sulfur); sulfate was the main product of the sulfide-based denitrifying process. S-sulfate was produced at a rate of about 0.35 kgm(3)day(-1). Sulfur inputs as S-H(2)S were estimated at about 0.75 kgm(3)day(-1) and Chemical Oxygen Demand (COD) removal rates did not vary significantly during the process. DGGE profiling and 16S rRNA identified Halothiobacillus-like species as the key microorganism supporting this process; such a strain has not yet been previously associated with such bioengineered systems.

Chinalia FA; Garbossa LH; Rodriguez JA; Lapa KR; Foresti E

2012-11-01

308

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; Gianotti Eloisa Pozzi; Campos José Roberto; Pires Roberto Cleto; Moraes Elizabeth de Mattos

2003-01-01

309

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

Science.gov (United States)

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 (15)N 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. PMID:23416476

Maeda, Koki; Toyoda, Sakae; Hanajima, Dai; Yoshida, Naohiro

2013-01-28

310

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

311

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

UK PubMed Central (United Kingdom)

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 (15)N 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.

Maeda K; Toyoda S; Hanajima D; Yoshida N

2013-03-01

312

South Australia, uranium enrichment  

International Nuclear Information System (INIS)

[en] 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)

1976-01-01

313

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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). T...

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

314

Effects of temperatures near the freezing point on N2O emissions, denitrification and on the abundance and structure of nitrifying and denitrifying soil communities.  

Science.gov (United States)

Climate warming in temperate regions may lead to decreased soil temperatures over winter as a result of reduced snow cover. We examined the effects of temperatures near the freezing point on N(2)O emissions, denitrification, and on the abundance and structure of soil nitrifiers and denitrifiers. Soil microcosms supplemented with NO3 - and/or NO3 - plus red clover residues were incubated for 120 days at -4 °C, -1 °C, +2 °C or +5 °C. Among microcosms amended with residues, N(2)O emission and/or denitrification increased with increasing temperature on Days 2 and 14. Interestingly, N(2)O emission and/or denitrification after Day 14 were the greatest at -1 °C. Substantial N(2) O emissions were only observed on Day 2 at +2 °C and +5 °C, while at -1 °C, N(2)O emissions were consistently detected over the duration of the experiment. Abundances of ammonia oxidizing bacteria (AOB) and archaea (AOA), Nitrospira-like bacteria and nirK denitrifiers were the lowest in soils at -4 °C, while abundances of Nitrobacter-like bacteria and nirS denitrifiers did not vary among temperatures. Community structures of nirK and nirS denitrifiers and Nitrobacter-like bacteria shifted between below-zero and above-zero temperatures. Structure of AOA and AOB communities also changed but not systematically among frozen and unfrozen temperatures. Results indicated shifts in some nitrifier and denitrifier communities with freezing and a surprising stimulation of N(2)O emissions at -1 °C when NO3 - and C are present. PMID:22882277

Wertz, Sophie; Goyer, Claudia; Zebarth, Bernie J; Burton, David L; Tatti, Enrico; Chantigny, Martin H; Filion, Martin

2012-08-29

315

Effects of temperatures near the freezing point on N2O emissions, denitrification and on the abundance and structure of nitrifying and denitrifying soil communities.  

UK PubMed Central (United Kingdom)

Climate warming in temperate regions may lead to decreased soil temperatures over winter as a result of reduced snow cover. We examined the effects of temperatures near the freezing point on N(2)O emissions, denitrification, and on the abundance and structure of soil nitrifiers and denitrifiers. Soil microcosms supplemented with NO3 - and/or NO3 - plus red clover residues were incubated for 120 days at -4 °C, -1 °C, +2 °C or +5 °C. Among microcosms amended with residues, N(2)O emission and/or denitrification increased with increasing temperature on Days 2 and 14. Interestingly, N(2)O emission and/or denitrification after Day 14 were the greatest at -1 °C. Substantial N(2) O emissions were only observed on Day 2 at +2 °C and +5 °C, while at -1 °C, N(2)O emissions were consistently detected over the duration of the experiment. Abundances of ammonia oxidizing bacteria (AOB) and archaea (AOA), Nitrospira-like bacteria and nirK denitrifiers were the lowest in soils at -4 °C, while abundances of Nitrobacter-like bacteria and nirS denitrifiers did not vary among temperatures. Community structures of nirK and nirS denitrifiers and Nitrobacter-like bacteria shifted between below-zero and above-zero temperatures. Structure of AOA and AOB communities also changed but not systematically among frozen and unfrozen temperatures. Results indicated shifts in some nitrifier and denitrifier communities with freezing and a surprising stimulation of N(2)O emissions at -1 °C when NO3 - and C are present.

Wertz S; Goyer C; Zebarth BJ; Burton DL; Tatti E; Chantigny MH; Filion M

2013-01-01

316

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)

1975-01-01

317

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

UK PubMed Central (United Kingdom)

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 denitrifying isolates indicated the occurrence of Paracoccus spp. in the sand filter. 16S rRNA-targeted probes were designed for this genus and the species cluster Paracoccus denitrificans-Paracoccus versutus and tested for specificity by whole-cell hybridization. Stringency requirements for the probes were adjusted by use of a formamide concentration gradient to achieve complete discrimination of even highly similar target sequences. Whole-cell hybridization confirmed that members of the genus Paracoccus were abundant among the isolates. Twenty-seven of the 56 isolates hybridized with the genus-specific probes. In situ hybridization identified dense aggregates of paracocci in detached biofilms. Probes complementary to the type strains of P. denitrificans and P. versutus did not hybridize to cells in the biofilms, suggesting the presence of a new Paracoccus species in the sand filter. Analysis using confocal laser scanning microscopy detected spherical aggregates of morphologically identical cells exhibiting a uniform fluorescence. Cell quantification was performed after thorough disruption of the biofilms and filtration onto polycarbonate filters. An average of 3.5% of total cell counts corresponded to a Paracoccus sp., whereas in a parallel sand filter with no supplemented methanol, and no measurable denitrification, only very few paracocci (0.07% of cells stained with 4',6-diamidino-2-phenylindole) could be detected. Hyphomicrobium spp. constituted approximately 2% of all cells in the denitrifying unit and could not be detected in the regular sand filter. This clear link between in situ abundance and denitrification suggests an active participation of paracocci and hyphomicrobia in the process. Possible selective advantages favoring the paracocci in this habitat are discussed.

Neef A; Zaglauer A; Meier H; Amann R; Lemmer H; Schleifer KH

1996-12-01

318

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

DEFF Research Database (Denmark)

DIVERSITY OF NITRATE-REDUCING AND DENITRIFYING BACTERIA IN A MARINE AQUACULTURE BIOFILTER AND THEIR RESPONSE TO SULFIDE B.U. Krieger 1,5, C. Schwermer 2, N. Rezakhani 5, M.A. Horn 1, A. Gieseke 2, E. Cytryn 3, D. Minz 3, J. van Rijn 4, H.L. Drake 1, A. Schramm 5 1 Dept. of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany; 2 Max Planck Institute for Marine Microbiology, Bremen, Germany; 3 Institute for Soil, Water and Environmental Sciences, ARO, The Volcani Center, Bet Dagan, Israel; 4 Faculty of Agricultural, Food And Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel; 5 Dept of Biological Sciences, Microbiology, University of Aarhus, Denmark Conventional aquaculture systems release nitrogen compounds and organic matter into marine environments. As an environmentally-friendly alternative, a zero-discharge mariculture system recently was developed containing a 3-stage biofilter for nitrification, denitrification/anaerobic sludge digestion, and sulfide oxidation. Sulfate reduction in the anaerobic part of the system leads to sulfide concentrations exceeding 5 mM, which may affect nitrate reduction and denitrification. Sulfide can inhibit nitrous oxide reductase, trigger a shift from denitrification to dissimilatory nitrate reduction to ammonium (DNRA), or be used as electron donor for nitrate reduction. The goal of this study was to identify and isolate nitrate-reducing and denitrifying bacteria from the biofilter and to investigate their response to sulfide concentrations relevant for the system. Almost 500 nitrate-consuming isolates were screened by 16S rRNA gene-RFLP; for each RFLP pattern representatives were sequenced. In total, 40 different strains were identified, some of them novel species, mostly affiliating with Alphaproteobacteria but also including Beta- and Gammaproteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. The diversity of the isolates was compared to the cultivation-independent diversity of nitrate-reducing and denitrifying bacteria based on narG and nosZ as functional marker genes. Growth experiments revealed great differences in sulfide-tolerance among isolates, ranging from < 50 µM to 5 mM; some strains were also able to oxidize sulfide. Increasing sulfide concentrations generally resulted in increased nitrous oxide production. Batch incubations of anaerobic sludge with 15N-nitrate confirmed the in situ relevance of these results and indicated a sulfide-induced shift from denitrification to DNRA.

Krieger, Bärbel; Schwermer, Carsten U.

2006-01-01

319

EnRICH: E  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background High throughput screening technologies enable biologists to generate candidate genes at a rate that, due to time and cost constraints, cannot be studied by experimental approaches in the laboratory. Thus, it has become increasingly important to prioritize candidate genes for experiments. To accomplish this, researchers need to apply selection requirements based on their knowledge, which necessitates qualitative integration of heterogeneous data sources and filtration using multiple criteria. A similar approach can also be applied to putative candidate gene relationships. While automation can assist in this routine and imperative procedure, flexibility of data sources and criteria must not be sacrificed. A tool that can optimize the trade-off between automation and flexibility to simultaneously filter and qualitatively integrate data is needed to prioritize candidate genes and generate composite networks from heterogeneous data sources. Results We developed the java application, EnRICH (Extraction and Ranking using Integration and Criteria Heuristics), in order to alleviate this need. Here we present a case study in which we used EnRICH to integrate and filter multiple candidate gene lists in order to identify potential retinal disease genes. As a result of this procedure, a candidate pool of several hundred genes was narrowed down to five candidate genes, of which four are confirmed retinal disease genes and one is associated with a retinal disease state. Conclusions We developed a platform-independent tool that is able to qualitatively integrate multiple heterogeneous datasets and use different selection criteria to filter each of them, provided the datasets are tables that have distinct identifiers (required) and attributes (optional). With the flexibility to specify data sources and filtering criteria, EnRICH automatically prioritizes candidate genes or gene relationships for biologists based on their specific requirements. Here, we also demonstrate that this tool can be effectively and easily used to apply highly specific user-defined criteria and can efficiently identify high quality candidate genes from relatively sparse datasets.

Zhang Xia; Greenlee M Heather West; Serb Jeanne M

2013-01-01

320

Oxygen enriched fireflooding  

Energy Technology Data Exchange (ETDEWEB)

Both pure oxygen and enriched air have been considered in fireflooding for enhanced oil recovery. Laboratory and field testing have conclusively shown that oxygen is practical and cost effective for this application. For reservoirs that require a large volume of high pressure gas, oxygen is cheaper than air simply based on compression costs. Additional process benefits with oxygen include: Faster Oil Production; Lower Injection Pressure; Greater Well Spacing; Increased Carbon Dioxide Partial Pressure; Lower Gas-to-Oil Ratios; and Purer Produced Gas. These features provide a compelling case for oxygen, once the safety and materials compatibility issues are properly addressed.

Shahani, G.H.; Gunardson, H.H. [Air Products and Chemicals, Allentown, PA (United States)

1995-02-01

 
 
 
 
321

Development of enrichment techniques  

International Nuclear Information System (INIS)

[en] 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.)[de] Die mit den aelteren Urananreicherungsanlagen in Almelo und Capenhurst gesammelten Erfahrungen waren die Grundlage fuer den Bau der Zentrifugenanlage in Gronau, die im August 1985 nach dreieinhalb Jahren Bauzeit in Betrieb genommen wurde. Die Gesamtkapazitaet der drei Urenco-Anlagen betraegt Ende 1992 2750 t UTA/a. Das am Anfang der Zentrifugenentwicklung gesetzte Ziel eines ueber mehr als zehn Jahre stoerungsfreien Betriebes der Zentrifugen wurde voll erreicht. Die Wirtschaftlichkeitsrechnungen zeigen, dass mit einer Laseranlage die Trennarbeitskosten einer Zentrifugenanlage kaum unterschritten werden koennen. (orig.)

1993-01-01

322

KEA: kinase enrichment analysis.  

UK PubMed Central (United Kingdom)

MOTIVATION: Multivariate experiments applied to mammalian cells often produce lists of proteins/genes altered under treatment versus control conditions. Such lists can be projected onto prior knowledge of kinase-substrate interactions to infer the list of kinases associated with a specific protein list. By computing how the proportion of kinases, associated with a specific list of proteins/genes, deviates from an expected distribution, we can rank kinases and kinase families based on the likelihood that these kinases are functionally associated with regulating the cell under specific experimental conditions. Such analysis can assist in producing hypotheses that can explain how the kinome is involved in the maintenance of different cellular states and can be manipulated to modulate cells towards a desired phenotype. SUMMARY: Kinase enrichment analysis (KEA) is a web-based tool with an underlying database providing users with the ability to link lists of mammalian proteins/genes with the kinases that phosphorylate them. The system draws from several available kinase-substrate databases to compute kinase enrichment probability based on the distribution of kinase-substrate proportions in the background kinase-substrate database compared with kinases found to be associated with an input list of genes/proteins. AVAILABILITY: The KEA system is freely available at http://amp.pharm.mssm.edu/lib/kea.jsp

Lachmann A; Ma'ayan A

2009-03-01

323

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

UK PubMed Central (United Kingdom)

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.

Yao YC; Zhang QL; Liu Y; Liu ZP

2013-09-01

324

A two-stage aerobic/anaerobic denitrifying horizontal bioreactor designed for treating ammonium and H(2)S simultaneously.  

Science.gov (United States)

A two-stage bioreactor was operated for a period of 140 days in order to develop a post-treatment process based on anaerobic bioxidation of sulfite. This process was designed for simultaneously treating the effluent and biogas of a full-scale UASB reactor, containing significant concentrations of NH(4) and H(2)S, respectively. The system comprised of two horizontal-flow bed-packed reactors operated with different oxygen concentrations. Ammonium present in the effluent was transformed into nitrates in the first aerobic stage. The second anaerobic stage combined the treatment of nitrates in the liquor with the hydrogen sulfide present in the UASB-reactor biogas. Nitrates were consumed with a significant production of sulfate, resulting in a nitrate removal rate of 0.43 kgNm(3)day(-1) and ?92 % efficiency. Such a removal rate is comparable to those achieved by heterotrophic denitrifying systems. Polymeric forms of sulfur were not detected (elementary sulfur); sulfate was the main product of the sulfide-based denitrifying process. S-sulfate was produced at a rate of about 0.35 kgm(3)day(-1). Sulfur inputs as S-H(2)S were estimated at about 0.75 kgm(3)day(-1) and Chemical Oxygen Demand (COD) removal rates did not vary significantly during the process. DGGE profiling and 16S rRNA identified Halothiobacillus-like species as the key microorganism supporting this process; such a strain has not yet been previously associated with such bioengineered systems. PMID:22956302

Chinalia, F A; Garbossa, L H P; Rodriguez, J A; Lapa, K R; Foresti, E

2012-09-07

325

Denitrifying bacteria from the genus Rhodanobacter dominate bacterial communities in the highly contaminated subsurface of a nuclear legacy waste site.  

UK PubMed Central (United Kingdom)

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of Rhodanobacter bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment.

Green SJ; Prakash O; Jasrotia P; Overholt WA; Cardenas E; Hubbard D; Tiedje JM; Watson DB; Schadt CW; Brooks SC; Kostka JE

2012-02-01

326

Thermal breeder fuel enrichment zoning  

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus for improving the performance of a thermal breeder reactor having regions of higher than average moderator concentration are disclosed. The fuel modules of the reactor core contain at least two different types of fuel elements, a high enrichment fuel element and a low enrichment fuel element. The two types of fuel elements are arranged in the fuel module with the low enrichment fuel elements located between the high moderator regions and the high enrichment fuel elements. Preferably, shim rods made of a fertile material are provided in selective regions for controlling the reactivity of the reactor by movement of the shim rods into and out of the reactor core. The moderation of neutrons adjacent the high enrichment fuel elements is preferably minimized as by reducing the spacing of the high enrichment fuel elements and/or using a moderator having a reduced moderating effect.

Capossela, Harry J. (Schenectady, NY); Dwyer, Joseph R. (Albany, NY); Luce, Robert G. (Schenectady, NY); McCoy, Daniel F. (Latham, NY); Merriman, Floyd C. (Rotterdam, NY)

1992-01-01

327

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)

1990-01-01

328

Uranium enrichment device  

International Nuclear Information System (INIS)

A device for enriching uranium by the separating-nozzle process is claimed. The device includes a plurality of separating-stage units, upstream coolers, associated compressors and duct means for supplying the starting gas and for incorporating the separating-stage units into a cascade. A vacuum-tight vessel having a circular cross-section is divided by radial partitions into sectors for the individual stages in cascade. The duct means include gas ducts disposed centrally in the sectors and in the lower part of the vessel. The vessel is spherical in shape, strengthened by the radial partitions and mounted on a central cruciform support defining four cross-sectional regions, the separating-stage units and the coolers being disposed in the sectors. The compressors are divided into four sets forming independent structures and are removably disposed in the cross-sectional regions beneath the vessel

1978-03-17

329

Effects of Heavy Metal Contamination upon Soil Microbes: Lead-induced Changes in General and Denitrifying Microbial Communities as Evidenced by Molecular Markers  

Directory of Open Access Journals (Sweden)

Full Text Available Lead (Pb) is a common environmental contaminant found in soils. Unlike other metals, Pb has no biological role, and is potentially toxic to microorganisms. Effects of low (1 ppm) and high (500-2000) levels of lead (Pb) upon the soil microbial community was investigated by the PCR/DGGE analysis of the 16S and nirK gene markers, indicative of general microbial community and denitrifying community, respectively. Community analysis by use of those markers had shown that Pb has detectable effects upon the community diversity even at the lowest concentration tested. Analysis of sample diversity and similarity between the samples suggested that there are several thresholds crossed as metal concentration increase, each causing a substantial change in microbial diversity. Preliminary data obtained in this study suggest that the denitrifying microbial community adapts to elevated levels of Pb by selecting for metal-resistant forms of nitrite reductases.

Dmitri Sobolev; Maria Begonia

2008-01-01

330

Communities of purple sulfur bacteria in a Baltic Sea coastal lagoon analyzed by puf LM gene libraries and the impact of temperature and NaCl concentration in experimental enrichment cultures.  

UK PubMed Central (United Kingdom)

Shallow coastal waters, where phototrophic purple sulfur bacteria (PSB) regularly form massive blooms, are subjected to massive diurnal and event-driven changes of physicochemical conditions including temperature and salinity. To analyze the ability of PSB to cope with these environmental factors and to compete in complex communities we have studied changes of the environmental community of PSB of a Baltic Sea lagoon under experimental enrichment conditions with controlled variation of temperature and NaCl concentration. For the first time, changes within a community of PSB were specifically analyzed using the photosynthetic reaction center genes pufL and M by RFLP and cloning experiments. The most abundant PSB phylotypes in the habitat were found along the NaCl gradient from freshwater conditions up to 7.5% NaCl. They were accompanied by smaller numbers of purple nonsulfur bacteria and aerobic anoxygenic phototrophic bacteria. Major components of the PSB community of the brackish lagoon were affiliated to PSB genera and species known as marine, halophilic or salt-tolerant, including species of M arichromatium, H alochromatium, T hiorhodococcus, A llochromatium, T hiocapsa, T hiorhodovibrio, and T hiohalocapsa. A dramatic shift occurred at elevated temperatures of 41 and 44°C when M arichromatium gracile became most prominent which was not detected at lower temperatures.

Tank M; Blümel M; Imhoff JF

2011-12-01

331

Work Enrichment for Academic Libraries.  

Science.gov (United States)

|Explores important quality of work life strategy--job redesign--and discusses job enlargement and job enrichment. A case study of academic library personnel demonstrates how introduction of automated systems at University of California, Berkeley led to restructuring and enrichment of jobs. References and list of selected resources are appended.…

Martell, Charles; Untawale, Mercedes

1983-01-01

332

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

1982-05-14

333

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.

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

334

Ferrioxamine E-supplemented pre-enrichment and enrichment media improve various isolation methods for Salmonella.  

Science.gov (United States)

Supplementation of pre-enrichment broth and enrichment broth media with ferrioxamine E (1 microgram/ml) significantly improved the recovery of Salmonella from artificially or naturally contaminated foods. Based on the selectivity of ferrioxamine E, Salmonella enteritidis and S. typhimurium could be isolated also from various mixed cultures (one Salmonella cell in 10(3)-10(4)-fold concentration of cells of competitors) by shaking for 6 h in supplemented buffered peptone water followed by cultivation on XLD- or XLT-4 agars. Isolation of Salmonella from these pre-enrichment cultures by use of Dynabeads-Anti-Salmonella was highly effective. 27 S. typhimurium strains were isolated from 762 naturally infected chicken giblets by use of unsupplemented Tetrathionate broth. However, 33 S. typhimurium isolates were obtained with ferrioxamine E-supplemented Tetrathionate broth from the same samples. Three Salmonella isolates out of 50 evenly divided meat meal samples were obtained by use of ferrioxamine E-supplemented buffered peptone water followed by direct streaking onto XLD- and Rambach agars, no Salmonella isolates could be detected by the conventional method. PMID:8722189

Reissbrodt, R; Vielitz, E; Kormann, E; Rabsch, W; Kühn, H

1996-02-01

335

Emission of nitrous oxide and dinitrogen by diverse earthworm families from Brazil and resolution of associated denitrifying and nitrate-dissimilating taxa.  

UK PubMed Central (United Kingdom)

The anoxic earthworm gut augments the activity of ingested microorganisms capable of anaerobiosis. Small earthworms (Lumbricidae) emit denitrification-derived N(2)O, whereas the large Octochaetus multiporus (Megascolecidae) does not. To examine this paradox, differently sized species of the families Glossoscolecidae (Rhinodrilus, Glossoscolex, Pontoscolex), Megascolecidae (Amynthas, Perionyx), Acanthodrilidae (Dichogaster), and Eudrilidae (Eudrilus) from Brazil were analyzed. Small species and the large Rhinodrilus alatus emitted N(2)O, whereas the large Glossoscolex paulistus did not, even though its gut could denitrify. N(2) and N(2)O were emitted concomitantly, and R. alatus emitted the highest amount of N(2). Denitrifiers and dissimilatory nitrate reducers were analyzed by barcoded amplicon pyrosequencing of narG, nirK, and nosZ. Gene sequences in gut and soil of the large G. paulistus were similar, whereas sequences in gut and soil of the small Amynthas gracilis were different and were also different compared with those of the gut and soil of G. paulistus. However, the denitrifying gut microbiota for both earthworms appeared to be soil-derived and dominated by Rhizobiales. The results demonstrated that (1) the emission of denitrification-derived N(2)O is widespread in different earthworm families, (2) large earthworms can also emit nitrogenous gases, and (3) ingested members of Rhizobiales are associated with this emission.

Depkat-Jakob PS; Brown GG; Tsai SM; Horn MA; Drake HL

2013-02-01

336

Communities of nirS-type denitrifiers in the water column of the oxygen minimum zone in the eastern South Pacific.  

Science.gov (United States)

The major sites of water column denitrification in the ocean are oxygen minimum zones (OMZ), such as one in the eastern South Pacific (ESP). To understand the structure of denitrifying communities in the OMZ off Chile, denitrifier communities at two sites in the Chilean OMZ (Antofagasta and Iquique) and at different water depths were explored by terminal restriction fragment length polymorphism analysis and cloning of polymerase chain reaction (PCR)-amplified nirS genes. NirS is a functional marker gene for denitrification encoding cytochrome cd1-containing nitrite reductase, which catalyses the reduction of nitrite to nitric oxide, the key step in denitrification. Major differences were found between communities from the two geographic locations. Shifts in community structure occurred along a biogeochemical gradient at Antofagasta. Canonical correspondence analysis indicated that O2, NO3-, NO2- and depth were important environmental factors governing these communities along the biogeochemical gradient in the water column. Phylogenetic analysis grouped the majority of clones from the ESP in distinct clusters of genes from presumably novel and yet uncultivated denitrifers. These nirS clusters were distantly related to those found in the water column of the Arabian Sea but the phylogenetic distance was even higher compared with environmental sequences from marine sediments or any other habitat. This finding suggests similar environmental conditions trigger the development of denitrifiers with related nirS genotypes despite large geographic distances. PMID:16104853

Castro-González, Maribeb; Braker, Gesche; Farías, Laura; Ulloa, Osvaldo

2005-09-01

337

Communities of nirS-type denitrifiers in the water column of the oxygen minimum zone in the eastern South Pacific.  

UK PubMed Central (United Kingdom)

The major sites of water column denitrification in the ocean are oxygen minimum zones (OMZ), such as one in the eastern South Pacific (ESP). To understand the structure of denitrifying communities in the OMZ off Chile, denitrifier communities at two sites in the Chilean OMZ (Antofagasta and Iquique) and at different water depths were explored by terminal restriction fragment length polymorphism analysis and cloning of polymerase chain reaction (PCR)-amplified nirS genes. NirS is a functional marker gene for denitrification encoding cytochrome cd1-containing nitrite reductase, which catalyses the reduction of nitrite to nitric oxide, the key step in denitrification. Major differences were found between communities from the two geographic locations. Shifts in community structure occurred along a biogeochemical gradient at Antofagasta. Canonical correspondence analysis indicated that O2, NO3-, NO2- and depth were important environmental factors governing these communities along the biogeochemical gradient in the water column. Phylogenetic analysis grouped the majority of clones from the ESP in distinct clusters of genes from presumably novel and yet uncultivated denitrifers. These nirS clusters were distantly related to those found in the water column of the Arabian Sea but the phylogenetic distance was even higher compared with environmental sequences from marine sediments or any other habitat. This finding suggests similar environmental conditions trigger the development of denitrifiers with related nirS genotypes despite large geographic distances.

Castro-González M; Braker G; Farías L; Ulloa O

2005-09-01

338

Caseinophosphopeptide enrichment and identification  

UK PubMed Central (United Kingdom)

Caseinophosphopeptides (CPPs) were generated via tryptic hydrolysis of sodium caseinate followed by heat treatment (75?°C) at pH 6.0, 7.0 and 8.0. Calcium aggregation, ethanol precipitation and gallium immobilised metal affinity chromatography (IMAC) were applied to enrich the CPPs. Nano?liquid chromatography electrospray ionisation?quadrupole time?of?flight tandem mass spectrometry was used for phosphopeptide separation and identification. The combination of gallium IMAC isolation with calcium and ethanol precipitation appears to be a useful tool in characterising the fate of CPPs in CN hydrolysates during thermal processing. CPPs appeared to be less susceptible to thermal modification when heat?treated at pH 7.0 than at pH 6.0 and 8.0. Different extents of methionine oxidation occurred in the CPPs depending on heat?treatment pH. The results herein may have important implications for the manufacture of CPPs and for the quality control of CPP products.

Zhu Y; FitzGerald RJ

2012-10-01

339

A coal enrichment method  

Energy Technology Data Exchange (ETDEWEB)

For coals which contain a large quantity of easily washed off clay admixtures, it is proposed to add inorganic salts of two and three valent metals, A12(SO4)3, MgSO4, Ca(NO3)2 and so on, and best of all, chlorides, CaC12 or MgC12 in a volume of 5 to 10 kilograms per cubic meter to the water in which the enrichment process occurs in order to limit the wash off of barren rock. With the addition of inorganic salts of single valent metals, for instance, NaBr, KC1, NaCl and KN03, to water, their optimal expenditure was 30 to 50 kilograms per cubic meter. The use of saline solutions of stratum waters in such a way that after they are mixed with the industrial water of the plant, the content of soluble salts is more than 5 kilograms per cubic meter and the optimal is from 30 to 50 kilograms per cubic meter, is also possible.

Kurczabinski, L.; Kozlowski, C.; Nowak, Z.; Tobiczyk, A.

1983-02-25

340

CLEAN: CLustering Enrichment ANalysis  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Integration of biological knowledge encoded in various lists of functionally related genes has become one of the most important aspects of analyzing genome-wide functional genomics data. In the context of cluster analysis, functional coherence of clusters established through such analyses have been used to identify biologically meaningful clusters, compare clustering algorithms and identify biological pathways associated with the biological process under investigation. Results We developed a computational framework for analytically and visually integrating knowledge-based functional categories with the cluster analysis of genomics data. The framework is based on the simple, conceptually appealing, and biologically interpretable gene-specific functional coherence score (CLEAN score). The score is derived by correlating the clustering structure as a whole with functional categories of interest. We directly demonstrate that integrating biological knowledge in this way improves the reproducibility of conclusions derived from cluster analysis. The CLEAN score differentiates between the levels of functional coherence for genes within the same cluster based on their membership in enriched functional categories. We show that this aspect results in higher reproducibility across independent datasets and produces more informative genes for distinguishing different sample types than the scores based on the traditional cluster-wide analysis. We also demonstrate the utility of the CLEAN framework in comparing clusterings produced by different algorithms. CLEAN was implemented as an add-on R package and can be downloaded at http://Clusteranalysis.org. The package integrates routines for calculating gene specific functional coherence scores and the open source interactive Java-based viewer Functional TreeView (FTreeView). Conclusion Our results indicate that using the gene-specific functional coherence score improves the reproducibility of the conclusions made about clusters of co-expressed genes over using the traditional cluster-wide scores. Using gene-specific coherence scores also simplifies the comparisons of clusterings produced by different clustering algorithms and provides a simple tool for selecting genes with a "functionally coherent" expression profile.

Freudenberg Johannes M; Joshi Vineet K; Hu Zhen; Medvedovic Mario

2009-01-01

 
 
 
 
341

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

342

Predominance of ammonia-oxidizing archaea and nirK-gene-bearing denitrifiers among ammonia-oxidizing and denitrifying populations in sediments of a large urban eutrophic lake (Lake Donghu).  

UK PubMed Central (United Kingdom)

The coupled nitrification-denitrification process plays a pivotal role in cycling and removal of nitrogen in aquatic ecosystems. In the present study, the communities of ammonia oxidizers and denitrifiers in the sediments of 2 basins (Guozhenghu Basin and Tuanhu Basin) of a large urban eutrophic lake (Lake Donghu) were determined using the ammonia monooxygenase subunit A (amoA) gene and the nitrite reductase gene. At all sites of this study, the archaeal amoA gene predominated over the bacterial amoA gene, whereas the functional gene for denitrification nirK gene far outnumbered the nirS gene. Spatially, compared with the Tuanhu Basin, the Guozhenghu Basin showed a significantly greater abundance of the archaeal amoA gene but less abundance of the nirK and nirS genes, while there was no significant difference of bacterial amoA gene copy numbers between the 2 basins. Unlike the archaeal amoA gene, the nirK gene showed a significant difference in community structure between the 2 basins. Archaeal amoA diversity was limited to the water-sediment cluster of Crenarchaeota, in sharp contrast with nirK for which 22 distinct operational taxonomic units were found. Accumulation of organic substances were found to be positively related to nirK and nirS gene copy numbers but negatively related to archaeal amoA gene copy numbers, whereas the abundance of the bacterial amoA gene was related to ammonia concentration.

Hou J; Cao X; Song C; Zhou Y

2013-07-01

343

Enrichment and identification of polycyclic aromatic compound-degrading bacteria enriched from sediment samples.  

UK PubMed Central (United Kingdom)

The degradation of polycyclic aromatic compounds (PACs) has been widely studied. Knowledge of the degradation of PACs by microbial populations can be utilized in the remediation of contaminated sites. To isolate and identify PAC-degrading bacteria for potential use in future bioremediation programmes, we established a series of PAC enrichments under the same experimental conditions from a single sediment sample taken from a highly polluted estuarine site. Enrichment cultures were established using the pollutants: anthracene, phenanthrene and dibenzothiophene as a sole carbon source. The shift in microbial community structure on each of these carbon sources was monitored by analysis of a time series of samples from each culture using 16S rRNA polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Significantly, our findings demonstrate that shifts in the constituent species within each degradative community are directly attributable to enrichment with different PACs. Subsequently, we characterized the microorganisms comprising the degradative communities within each enrichment using 16S rRNA sequence data. Our findings demonstrate that the ability to degrade PACs is present in five divisions of the Proteobacteria and Actinobacteria. By determining the precise identity of the PAC-degrading bacterial species isolated from a single sediment sample, and by comparing our findings with previously published research, we demonstrate how bacteria with similar PAC degrading capabilities and 16S rRNA signatures are found in similarly polluted environments in geographically very distant locations, e.g., China, Italy, Japan and Hawaii. Such a finding suggests that geographical barriers do not limit the distribution of key PAC-degrading bacteria; this finding is in accordance with the Baas-Becking hypothesis "everything is everywhere; the environment selects" and may have significant consequences for the global distribution of PAC-degrading bacteria and their use in bioremediation.

Long RM; Lappin-Scott HM; Stevens JR

2009-07-01

344

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).

1990-01-01

345

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)

1990-01-01

346

Factorizable enriched categories and applications  

CERN Multimedia

We define the twisted tensor product of two enriched categories, which generalizes various sorts of `products' of algebraic structures, including the bicrossed product of groups, the twisted tensor product of (co)algebras and the double cross product of bialgebras. The key ingredient in the definition is the notion of simple twisting systems between two enriched categories. To give examples of simple twisted tensor products we introduce matched pairs of enriched categories. Several other examples related to ordinary categories, posets and groupoids are also discussed.

Bârde?, Aura

2011-01-01

347

Flocculant for enriching coal sludge  

Energy Technology Data Exchange (ETDEWEB)

It has been suggested that a styrene-indene resin be used as the flocculant for enriching coal sludge. The styrene-indene resin in this case manifests itself in a new quality, as a flocculant, which is considerably higher in selectivity than the known flocculants used for this purpose. In addition, the styrene-indene resin is not soluble in water, therefore in enriching sludges the circulating water will not be contaminated. This is also one of the significant advantages of this reagent. Thus, the primary advantage of this invention is improvement in the technological indicators of coal sludge enrichment.

Nikitin, I.N.; Andreveva, V.S.; Gryanko, V.I.; Lyadov, V.V.; Preobrazhenskiy, B.P.; Vinarskiy, N.S.

1980-08-15

348

Poster 1. Enriched boron products  

International Nuclear Information System (INIS)

Eagle-Picher can produce large quantities of isotopically enriched boron up to 99 at % boron 10. Two products are of particular interest for the water chemistry in nuclear reactors. Enriched sodium pentaborate can be stored in the standby liquid control tank of the boiling water reactors. It allows the operator to employ more active fuels and still have sufficient shut down capabilities. Enriched boric acid can be used as a chemical shim in the primary cooling system of pressurized water reactors. It provides the benefits associated with high pH without sacrificing the boron 10 content or increasing the lithium content. (author).

1992-01-01

349

Culture's Unacknowledged Iron Grip  

Science.gov (United States)

|Ideally, education provides mutual enrichment for professor and students. In this article, the author often fears that he is learning far more than his students are in a course on intercultural communication. Its real subject sometimes seems to be the iron grip of American culture upon his students. What is most fascinating is that the power of…

Engle, John

2007-01-01

350

Kinetics of p-aminoazobenzene degradation by Bacillus subtilis under denitrifying conditions  

Energy Technology Data Exchange (ETDEWEB)

Bacillus subtilis is an organism capable of degrading an azo dye, such as p-aminoazobenzene (pAAB), under both aerobic and anoxic conditions. In both cases, pAAB is co-metabolized with a main carbon source and under anoxic conditions denitrification is observed. Kinetic experiments were carried out with a pure culture of B. subtilis and a mathematical model that accurately describes both biodegradation of pAAB under anoxic conditions and the denitrification process under both carbon- and nitrate- or nitrite-limited conditions is developed. Presence of pAAB in culture medium causes an inhibition of bacterial growth and of nitrite accumulation. Bacterial growth and pAAB degradation rates are found to be slower under anoxic conditions compared to the corresponding rates under aerobic conditions.

Zissi, U.S.; Kornaros, M.E.; Lyberatos, G.C.

1999-05-01

351

Exome sequencing by targeted enrichment.  

UK PubMed Central (United Kingdom)

This unit describes methods for targeted enrichment of the exon-coding portions of the genome using Agilent SureSelect Human All Exon 50 Mb and Roche Nimblegen SeqCap EZ Exome platforms. Each platform targets and enriches a large overlapping portion of the greater human exome. The protocols here describe the biochemical procedures used to enrich exomic DNA with each platform, including recommended modifications to the manufacturers' protocols. In addition, a brief description of the sequencing protocol and estimation of the needed amount of sequencing for each platform is included. Finally, a detailed analytical pipeline for processing the subsequent data is described. These protocols focus specifically on human exome sequencing platforms, but can be applied with some modification to other organisms and targeted enrichment approaches.

Clark MJ; Chen R; Snyder M

2013-01-01

352

Comparison between aerobic and anoxic metabolism of denitrifying-EBPR sludge: effect of biomass poly-hydroxyalkanoates content.  

UK PubMed Central (United Kingdom)

Biomass with denitrifying phosphate uptake ability was tested under sequencing anaerobic-aerobic and anaerobic-anoxic conditions. The initial dose of acetate, under anaerobic conditions varied to achieve different PHA (poly-hydroxyalkanoates) saturation of PAO (polyphosphate accumulating organisms) cells. Increased acetate dosage under anaerobic conditions led to higher phosphate release and increased PHA storage by PAOs and, also, to greater phosphate uptake rates under the following aerobic and/or anoxic conditions. The experimental results also indicated that when organic carbon is limited under anaerobic conditions, more internal glycogen supplementary to polyphosphate cleavage is utilized by the biomass, resulting in less phosphate release and more PHA stored per acetate taken up. In the subsequent aerobic and/or anoxic phase PAOs demonstrate an improved EBPR (enhanced biological phosphorus removal) performance, with regard to PHA consumption per phosphate taken up, for reduced initial biomass PHA content under both aerobic and anoxic conditions. The examination of EBPR biomass under controlled operational conditions, where experimental analysis of the relevant compounds in the bulk phase (PO(4)(3-), NO(3)(-) and/or O(2)) in conjunction with the biomass intracellular products (PHA, glycogen), contributes to an improved understanding of the PAOs metabolic behavior, with regard to organic substrate availability.

Kapagiannidis AG; Zafiriadis I; Aivasidis A

2013-01-01

353

Meadow Enriched ACP Process Algebras  

CERN Multimedia

We introduce the notion of an ACP process algebra. The models of the axiom system ACP are the origin of this notion. ACP process algebras have to do with processes in which no data are involved. We also introduce the notion of a meadow enriched ACP process algebra, which is a simple generalization of the notion of an ACP process algebra to processes in which data are involved. In meadow enriched ACP process algebras, the mathematical structure for data is a meadow.

Bergstra, J A

2009-01-01

354

Importance of pre-enrichment media for isolation of Salmonella spp. from swine and poultry  

DEFF Research Database (Denmark)

The performance of two new (1-day) culture methods, Salmonella Enrichment Broth (SEB) and Revive, and an alternative pre-enrichment broth, designated Universal pre-enrichment broth (UB), was compared to the internationally accepted buffered peptone water (BPW). The study was directed towards detection of Salmonella in 100 faecal samples from porcine and 100 neck-skin samples from poultry. The sensitivity (number of positive cases per method among all the positive cases) of the conventional pre-enrichment in BPW was found to be 0.77 for swine and 0.66 for poultry samples, while a combination of the BPW method with parallel pre-enrichment of the same sample in UB resulted in high sensitivity for swine (0.92) and poultry (0.95) samples. A 2-h pre-enrichment in the non-selective Revive, followed by overnight enrichment in selective broth, resulted in a low sensitivity, particularly for the neck-skin samples (0.16, P = 0.001). The SEE method in the porcine samples resulted in a sensitivity (0.71) comparable to thestandard method (P = 0.31). In conclusion, additional pre-enrichment of samples in UB may substantially increase the culture sensitivity. During routine screening of large numbers of samples, it may be advantageous to use SEE rather than standard culturing. (C) 1998 Federation of European Microbiological Societies.

Hoorfar, Jeffrey; Baggesen, Dorte Lau

1998-01-01

355

Enrichment of an anammox bacterial community from a flooded paddy soil.  

Science.gov (United States)

This study describes the enrichment of anammox bacteria in a column simulating oxygen limited flooded paddy soils, which are important man-made ecosystems that receive substantial amounts of fixed nitrogen. The upper 50 cm of the paddy soil, containing a high amount of ammonium [1.6-10.4 mmol N kg (dry weight)(-1)], was selected as the inoculum for anammox enrichment. After 18 months of incubation with freshwater from the paddy soil ecosystem, the enrichment culture consumed approximately 4 mmol ammonium l(-1) day(-1) and 5 mmol nitrite l(-1) day(-1). The maximum specific anammox activity of the culture was 35.7 ?mol N g (dry weight)(-1) h(-1). Fluorescence in situ hybridization indicated that anammox cells constituted 50% ± 10% of the enrichment culture. The phylogenetic analyses of 16S rRNA and the diagnostic hydrazine synthase (hzsA) genes showed that two dominant anammox species were enriched from paddy soil. The enriched Candidatus Anammoxoglobus-like organisms showed a 16S rRNA gene similarity of 97.5-99.2% to Candidatus Anammoxoglobus propionicus and the Candidatus Jettenia-like organisms showed 92.1-93.1% 16S rRNA gene identity to Candidatus Jettenia asiatica. Real-time quantitative PCR of hzsA gene suggested that up to 10(10) copies g (dry weight)(-1) of soil anammox bacteria were present in the enrichment culture. PMID:23754729

Hu, Bao-lan; Shen, Li-dong; Liu, Shuai; Cai, Chen; Chen, Ting-ting; Kartal, Boran; Harhangi, Harry R; Op den Camp, Huub J M; Lou, Li-ping; Xu, Xiang-yang; Zheng, Ping; Jetten, Mike S M

2013-02-28

356

Enrichment of an anammox bacterial community from a flooded paddy soil.  

UK PubMed Central (United Kingdom)

This study describes the enrichment of anammox bacteria in a column simulating oxygen limited flooded paddy soils, which are important man-made ecosystems that receive substantial amounts of fixed nitrogen. The upper 50 cm of the paddy soil, containing a high amount of ammonium [1.6-10.4 mmol N kg (dry weight)(-1)], was selected as the inoculum for anammox enrichment. After 18 months of incubation with freshwater from the paddy soil ecosystem, the enrichment culture consumed approximately 4 mmol ammonium l(-1) day(-1) and 5 mmol nitrite l(-1) day(-1). The maximum specific anammox activity of the culture was 35.7 ?mol N g (dry weight)(-1) h(-1). Fluorescence in situ hybridization indicated that anammox cells constituted 50% ± 10% of the enrichment culture. The phylogenetic analyses of 16S rRNA and the diagnostic hydrazine synthase (hzsA) genes showed that two dominant anammox species were enriched from paddy soil. The enriched Candidatus Anammoxoglobus-like organisms showed a 16S rRNA gene similarity of 97.5-99.2% to Candidatus Anammoxoglobus propionicus and the Candidatus Jettenia-like organisms showed 92.1-93.1% 16S rRNA gene identity to Candidatus Jettenia asiatica. Real-time quantitative PCR of hzsA gene suggested that up to 10(10) copies g (dry weight)(-1) of soil anammox bacteria were present in the enrichment culture.

Hu BL; Shen LD; Liu S; Cai C; Chen TT; Kartal B; Harhangi HR; Op den Camp HJ; Lou LP; Xu XY; Zheng P; Jetten MS

2013-06-01

357

Enrichment of anaerobic syngas converting bacteria from thermophilic bioreactor sludge.  

UK PubMed Central (United Kingdom)

Thermophilic (55°C) anaerobic microbial communities were enriched with a synthetic syngas mixture (composed of CO, H2 and CO2 ) or with CO alone. Cultures T-Syn and T-CO were incubated and successively transferred with syngas (16 transfers) or CO (9 transfers), respectively, with increasing CO partial pressures from 0.09 to 0.88 bar. Culture T-Syn, after 4 successive transfers with syngas, was also incubated with CO and subsequently transferred (9 transfers) with solely this substrate - cultures T-Syn-CO. Incubation with syngas and CO caused a rapid decrease in the microbial diversity of the anaerobic consortium. T-Syn and T-Syn-CO showed identical microbial composition, and were dominated by Desulfotomaculum and Caloribacterium species. Incubation initiated with CO resulted in the enrichment of bacteria from the genera Thermincola and Thermoanaerobacter. Methane was detected in the first two to three transfers of T-Syn, but production ceased afterwards. Acetate was the main product formed by T-Syn and T-Syn-CO. Enriched T-CO cultures showed a two-phase conversion, in which H2 was formed first and then converted to acetate. This research provides insight into how thermophilic anaerobic communities develop using syngas/CO as sole energy and carbon source can be steered for specific end products and subsequent microbial synthesis of chemicals. This article is protected by copyright. All rights reserved.

Alves JI; Stams AJ; Plugge CM; Alves MM; Sousa DZ

2013-07-01

358

Neuroprotective effects of cognitive enrichment.  

Science.gov (United States)

Cognitive enrichment early in life, as indicated by level of education, complexity of work environment or nature of leisure activities, appears to protect against the development of age-associated cognitive decline and also dementia. These effects are more robust for measures of crystallized intelligence than for measures of fluid intelligence and depend on the ability of the brain to compensate for pathological changes associated with aging. This compensatory ability is referred to as cognitive reserve. The cognitive reserve hypothesis suggests that cognitive enrichment promotes utilization of available functions. Alternatively, late life cognitive changes in cognition may be linked to a factor, such as cholinergic dysfunction, that is also present early in life and contributes to the reduced levels of early life cognitive enrichment. Beneficial effects of environmental enrichment early in life have also been observed in rodents and primates. Research with rodents indicates that these changes have structural correlates, which likely include increased synapses in specific brain regions. Dogs also show age-dependent cognitive decline, and both longitudinal and cross-sectional studies indicate that this decline can be attenuated by cognitive enrichment. Furthermore, cognitive enrichment has differential effects, improving some functions more than others. From a neurobiological perspective, behavioral enrichment in the dog may act to promote neurogenesis later in life. This can be distinguished from nutritional interventions with antioxidants, which appear to attenuate the development of neuropathology. These results suggest that a combination of behavioral and nutritional or pharmacological interventions may be optimal for reducing the rate of age-dependent cognitive decline. PMID:16949888

Milgram, Norton W; Siwak-Tapp, Christina T; Araujo, Joseph; Head, Elizabeth

2006-09-01

359

Molecular characterization of nosRZDFYLX genes coding for denitrifying nitrous oxide reductase of Bradyrhizobium japonicum.  

UK PubMed Central (United Kingdom)

The nosRZDFYLX gene cluster for the respiratory nitrous oxide reductase from Bradyrhizobium japonicum strain USDA110 has been cloned and sequenced. Seven protein coding regions corresponding to nosR, nosZ, the structural gene, nosD, nosF, nosY, nosL, and nosX were detected. The deduced amino acid sequence exhibited a high degree of similarity to other nitrous oxide reductases from various sources. The NosZ protein included a signal peptide for protein export. Mutant strains carrying either a nosZ or a nosR mutation accumulated nitrous oxide when cultured microaerobically in the presence of nitrate. Maximal expression of a P nosZ-lacZ fusion in strain USDA110 required simultaneously both low level oxygen conditions and the presence of nitrate. Microaerobic activation of the fusion required FixLJ and FixK(2).

Velasco L; Mesa S; Xu CA; Delgado MJ; Bedmar EJ

2004-04-01

360

Enrichment of light hydrocarbon mixture  

Energy Technology Data Exchange (ETDEWEB)

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

 
 
 
 
361

Enrichment of light hydrocarbon mixture  

Energy Technology Data Exchange (ETDEWEB)

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)

2010-08-10

362

Bioaugmentation of a wastewater bioreactor system with the nitrous oxide-reducing denitrifier Pseudomonas stutzeri strain TR2.  

UK PubMed Central (United Kingdom)

In bioaugmentation technology, survival of inoculant in the treatment system is prerequisite but remains to be a crucial hurdle. In this study, we bioaugmented the denitrification tank of a piggery wastewater treatment system with the denitrifying bacterium Pseudomonas stutzeri strain TR2 in two pilot-scale experiments, with the aim of reducing nitrous oxide (N(2)O), a gas of environmental concern. In the laboratory, strain TR2 grew well and survived with high concentrations of nitrite (5-10 mM) at a wide range of temperatures (28-40°C). In the first augmentation of the pilot-scale experiment, strain TR2 inoculated into the denitrification tank with conditions (30°C, ~0.1 mM nitrite) survived only 2-5 days. In contrast, in the second augmentation with conditions determined to be favorable for the growth of the bacterium in the laboratory (40-45°C, 2-5 mM nitrite), strain TR2 survived longer than 32 days. During the time when the presence of strain TR2 was confirmed by quantitative real-time PCR, N(2)O emission was maintained at a low level even under nitrite-accumulating conditions in the denitrification and nitrification tanks, which provided indirect evidence that strain TR2 can reduce N(2)O in the pilot-scale system. Our results documented the effective application of growth conditions favorable for strain TR2 determined in the laboratory to maintain growth and performance of this strain in the pilot-scale reactor system and the decrease of N(2)O emission as the consequence.

Ikeda-Ohtsubo W; Miyahara M; Kim SW; Yamada T; Matsuoka M; Watanabe A; Fushinobu S; Wakagi T; Shoun H; Miyauchi K; Endo G

2013-01-01

363

Bioaugmentation of a wastewater bioreactor system with the nitrous oxide-reducing denitrifier Pseudomonas stutzeri strain TR2.  

Science.gov (United States)

In bioaugmentation technology, survival of inoculant in the treatment system is prerequisite but remains to be a crucial hurdle. In this study, we bioaugmented the denitrification tank of a piggery wastewater treatment system with the denitrifying bacterium Pseudomonas stutzeri strain TR2 in two pilot-scale experiments, with the aim of reducing nitrous oxide (N(2)O), a gas of environmental concern. In the laboratory, strain TR2 grew well and survived with high concentrations of nitrite (5-10 mM) at a wide range of temperatures (28-40°C). In the first augmentation of the pilot-scale experiment, strain TR2 inoculated into the denitrification tank with conditions (30°C, ~0.1 mM nitrite) survived only 2-5 days. In contrast, in the second augmentation with conditions determined to be favorable for the growth of the bacterium in the laboratory (40-45°C, 2-5 mM nitrite), strain TR2 survived longer than 32 days. During the time when the presence of strain TR2 was confirmed by quantitative real-time PCR, N(2)O emission was maintained at a low level even under nitrite-accumulating conditions in the denitrification and nitrification tanks, which provided indirect evidence that strain TR2 can reduce N(2)O in the pilot-scale system. Our results documented the effective application of growth conditions favorable for strain TR2 determined in the laboratory to maintain growth and performance of this strain in the pilot-scale reactor system and the decrease of N(2)O emission as the consequence. PMID:22999357

Ikeda-Ohtsubo, Wakako; Miyahara, Morio; Kim, Sang-Wan; Yamada, Takeshi; Matsuoka, Masaki; Watanabe, Akira; Fushinobu, Shinya; Wakagi, Takayoshi; Shoun, Hirofumi; Miyauchi, Keisuke; Endo, Ginro

2012-09-19

364

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

365