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Sample records for aerobic denitrifying bacterium

  1. Anaerobic and aerobic degradation of pyridine by a newly isolated denitrifying bacterium.

    PubMed Central

    Rhee, S K; Lee, G M; Yoon, J H; Park, Y H; Bae, H S; Lee, S T

    1997-01-01

    New denitrifying bacteria that could degrade pyridine under both aerobic and anaerobic conditions were isolated from industrial wastewater. The successful enrichment and isolation of these strains required selenite as a trace element. These isolates appeared to be closely related to Azoarcus species according to the results of 16S rRNA sequence analysis. An isolated strain, pF6, metabolized pyridine through the same pathway under both aerobic and anaerobic conditions. Since pyridine induced NAD-linked glutarate-dialdehyde dehydrogenase and isocitratase activities, it is likely that the mechanism of pyridine degradation in strain pF6 involves N-C-2 ring cleavage. Strain pF6 could degrade pyridine in the presence of nitrate, nitrite, and nitrous oxide as electron acceptors. In a batch culture with 6 mM nitrate, degradation of pyridine and denitrification were not sensitively affected by the redox potential, which gradually decreased from 150 to -200 mV. In a batch culture with the nitrate concentration higher than 6 mM, nitrite transiently accumulated during denitrification significantly inhibited cell growth and pyridine degradation. Growth yield on pyridine decreased slightly under denitrifying conditions from that under aerobic conditions. Furthermore, when the pyridine concentration used was above 12 mM, the specific growth rate under denitrifying conditions was higher than that under aerobic conditions. Considering these characteristics, a newly isolated denitrifying bacterium, strain pF6, has advantages over strictly aerobic bacteria in field applications. PMID:9212408

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

    USGS Publications Warehouse

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

    1993-01-01

    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.

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

    PubMed

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

    2016-03-01

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

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

    SciTech Connect

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

    2012-01-27

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

  5. Aerobic and anoxic growth and nitrate removal capacity of a marine denitrifying bacterium isolated from a recirculation aquaculture system.

    PubMed

    Borges, Maria-Teresa; Sousa, André; De Marco, Paolo; Matos, Ana; Hönigová, Petra; Castro, Paula M L

    2008-01-01

    Bacterial biofilters used in marine recirculation aquaculture systems need improvements to enhance nitrogen removal efficiency. Relatively little is known about biofilter autochthonous population structure and function. The present study was aimed at isolating and characterizing an autochthonous denitrifying bacterium from a marine biofilter installed at a recirculation aquaculture system. Colonization of four different media in a marine fish farm was followed by isolation of various denitrifying strains and molecular classification of the most promising one, strain T2, as a novel member of the Pseudomonas fluorescens cluster. This strain exhibits high metabolic versatility regarding N and C source utilization and environmental conditions for growth. It removed nitrate through aerobic assimilatory metabolism at a specific rate of 116.2 mg NO(3)-N g dw(-1) h(-1). Dissimilatory NO(3)-N removal was observed under oxic conditions at a limited rate, where transient NO(2)-N formed represented 22% (0.17 mg L(-1)) of the maximum transient NO(2)-N observed under anoxic conditions. Dissimilatory NO(3)-N removal under anoxic conditions occurred at a specific rate of 53.5 mg NO(3)-N g dw(-1) h(-1). The isolated denitrifying strain was able to colonize different materials, such as granular activated carbon (GAC), Filtralite and Bioflow plastic rings, which allow the development of a prototype bioreactor for strain characterization under dynamic conditions and mimicking fish-farm operating conditions.

  6. A novel heterotrophic nitrifying and aerobic denitrifying bacterium, Zobellella taiwanensis DN-7, can remove high-strength ammonium.

    PubMed

    Lei, Yu; Wang, Yangqing; Liu, Hongjie; Xi, Chuanwu; Song, Liyan

    2016-05-01

    A novel heterotrophic bacterium capable of heterotrophic nitrification and aerobic denitrification was isolated from ammonium contaminated landfill leachate and physiochemical and phylogenetically identified as Zobellella taiwanensis DN-7. DN-7 converted nitrate, nitrate, and ammonium to N2 as the primary end product. Single factor experiments suggested that the optimal conditions for ammonium removal were trisodium citrate as carbon source, C/N ratio 8, pH 8.0-10.0, salinity less than 3 %, temperature 30 °C, and rotation speed more than 150 rpm. Specifically, DN-7 could remove 1000.0 and 2000.0 mg/L NH4 (+)-N completely within 96 and 216 h, with maximum removal rates of 19.6 and 17.3 mg L(-1) h(-1), respectively. These results demonstrated that DN-7 is a promising candidate for application of high-strength ammonium wastewater treatments.

  7. Ammonium removal at low temperature by a newly isolated heterotrophic nitrifying and aerobic denitrifying bacterium Pseudomonas fluorescens wsw-1001.

    PubMed

    Zhang, Shumei; Sha, Changqing; Jiang, Wei; Li, Weiguang; Zhang, Duoying; Li, Jing; Meng, Liqiang; Piao, Yongjian

    2015-01-01

    A heterotrophic nitrifier wsw-1001 was isolated from Songhua River and identified as Pseudomonas fluorescens. Ammonium removal by the strain at low temperature was investigated. The effect of initial ammonium concentration (from 5 to 1000 mg/L) and culture temperature (from 4°C to 30°C) on ammonium removal efficiency was studied. Biodegradation product, [Formula: see text], [Formula: see text], N2, N2O and intercellular N were monitored. The results indicated that the strain had potential for water and wastewater treatment. Ammonium could be removed by the strain at low temperature. Ammonium removal efficiency increased with temperature from 4°C to 20°C and decreased with ammonium concentration from 5 to 1000 mg/L. The strain exhibited a capability of heterotrophic nitrification and aerobic denitrification using [Formula: see text] as the sole nitrogen source at 8°C. [Formula: see text] and [Formula: see text] were reduced by the strain. Nitrogen balance analysis in the presence of 39.7 mg/L [Formula: see text] indicated that 71.2% [Formula: see text] was removed by converting to N2 (46.3%) and assimilating as biomass (42.5%). Substances such as [Formula: see text], [Formula: see text] and N2O were detected at very low concentrations. Ammonium mono-oxygenase, hydroxylamine oxidase, nitrite reductase and nitrate reductase activity were measured. The ammonium removal pathway of the strain was speculated to be [Formula: see text].

  8. Draft Genome Sequence of Pseudomonas hussainii Strain MB3, a Denitrifying Aerobic Bacterium Isolated from the Rhizospheric Region of Mangrove Trees in the Andaman Islands, India.

    PubMed

    Jaiswal, Shubham K; Saxena, Rituja; Mittal, Parul; Gupta, Ankit; Sharma, Vineet K

    2017-02-02

    The genome sequence of Pseudomonas hussainii MB3, isolated from the rhizospheric region of mangroves in the Andaman Islands, is comprised of 3,644,788 bp and 3,159 protein coding genes. Draft genome analysis indicates that MB3 is an aerobic bacterium capable of performing assimilatory sulfate reduction, dissimilatory nitrate reduction, and denitrification.

  9. Draft Genome Sequence of Pseudomonas hussainii Strain MB3, a Denitrifying Aerobic Bacterium Isolated from the Rhizospheric Region of Mangrove Trees in the Andaman Islands, India

    PubMed Central

    Jaiswal, Shubham K.; Saxena, Rituja; Mittal, Parul; Gupta, Ankit

    2017-01-01

    ABSTRACT The genome sequence of Pseudomonas hussainii MB3, isolated from the rhizospheric region of mangroves in the Andaman Islands, is comprised of 3,644,788 bp and 3,159 protein coding genes. Draft genome analysis indicates that MB3 is an aerobic bacterium capable of performing assimilatory sulfate reduction, dissimilatory nitrate reduction, and denitrification. PMID:28153890

  10. Screening and identification of aerobic denitrifiers

    NASA Astrophysics Data System (ADS)

    Shao, K.; Deng, H. M.; Chen, Y. T.; Zhou, H. J.; Yan, G. X.

    2016-08-01

    With the standards of the effluent quality more stringent, it becomes a quite serious problem for municipalities and industries to remove nitrogen from wastewater. Bioremediation is a potential method for the removal of nitrogen and other pollutants because of its high efficiency and low cost. Seven predominant aerobic denitrifiers were screened and characterized from the activated sludge in the CAST unit. Some of these strains removed 87% nitrate nitrogen at least. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Ralstonia, Achromobacter, Aeromonas and Enterobacter.

  11. Nitrogen-removal efficiency of a novel aerobic denitrifying bacterium, Pseudomonas stutzeri strain ZF31, isolated from a drinking-water reservoir.

    PubMed

    Huang, Tinglin; Guo, Lin; Zhang, Haihan; Su, Junfeng; Wen, Gang; Zhang, Kai

    2015-11-01

    An aerobic denitrifier, identified as Pseudomonas stutzeri strain ZF31, was isolated from the Zhoucun drinking-water reservoir. Strain ZF31 removed 97% of nitrate nitrogen after 16h, without nitrite accumulation. Sequence amplification indicated the presence of the denitrification genes napA, nirS, norB, and nosZ. Nitrogen balance analysis revealed that approximately 75% of the initial nitrogen was removed as gas products. Response surface methodology (RSM) experiments showed that maximum removal of total nitrogen (TN) occurred at pH 8.23, a C/N ratio of 6.68, temperature of 27.72°C, and with shaking at 54.15rpm. The TN removal rate at low C/N ratio (i.e., 3) and low temperature (i.e., 10°C) was 73.30% and 60.08%, respectively. These results suggest that strain ZF31 has potential applications for the bioremediation of slightly polluted drinking-water reservoirs.

  12. Anaerobic and aerobic degradation of cyanophycin by the denitrifying bacterium Pseudomonas alcaligenes strain DIP1 and role of three other coisolates in a mixed bacterial consortium.

    PubMed

    Sallam, Ahmed; Steinbüchel, Alexander

    2008-06-01

    Four bacterial strains were isolated from a cyanophycin granule polypeptide (CGP)-degrading anaerobic consortium, identified by 16S rRNA gene sequencing, and assigned to species of the genera Pseudomonas, Enterococcus, Clostridium, and Paenibacillus. The consortium member responsible for CGP degradation was assigned as Pseudomonas alcaligenes strain DIP1. The growth of and CGP degradation by strain DIP1 under anaerobic conditions were enhanced but not dependent on the presence of nitrate as an electron acceptor. CGP was hydrolyzed to its constituting beta-Asp-Arg dipeptides, which were then completely utilized within 25 and 4 days under anaerobic and aerobic conditions, respectively. The end products of CGP degradation by strain DIP1 were alanine, succinate, and ornithine as determined by high-performance liquid chromatography analysis. The facultative anaerobic Enterococcus casseliflavus strain ELS3 and the strictly anaerobic Clostridium sulfidogenes strain SGB2 were coisolates and utilized the beta-linked isodipeptides from the common pool available to the mixed consortium, while the fourth isolate, Paenibacillus odorifer strain PNF4, did not play a direct role in the biodegradation of CGP. Several syntrophic interactions affecting CGP degradation, such as substrate utilization, the reduction of electron acceptors, and aeration, were elucidated. This study demonstrates the first investigation of CGP degradation under both anaerobic and aerobic conditions by one bacterial strain, with regard to the physiological role of other bacteria in a mixed consortium.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

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

    PubMed

    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

    2012-01-01

    "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.

  16. Microbial community analysis of an aerobic nitrifying-denitrifying MBR treating ABS resin wastewater.

    PubMed

    Chang, Chia-Yuan; Tanong, Kulchaya; Xu, Jia; Shon, Hokyong

    2011-05-01

    A two-stage aerobic membrane bioreactor (MBR) system for treating acrylonitrile butadiene styrene (ABS) resin wastewater was carried out in this study to evaluate the system performance on nitrification. The results showed that nitrification of the aerobic MBR system was significant and the highest TKN removal of approximately 90% was obtained at hydraulic retention time (HRT) 18 h. In addition, the result of nitrogen mass balance revealed that the percentage of TN removal due to denitrification was in the range of 8.7-19.8%. Microbial community analysis based on 16s rDNA molecular approach indicated that the dominant ammonia oxidizing bacteria (AOB) group in the system was a β-class ammonia oxidizer which was identified as uncultured sludge bacterium (AF234732). A heterotrophic aerobic denitrifier identified as Thauera mechernichensis was found in the system. The results indicated that a sole aerobic MBR system for simultaneous removals of carbon and nitrogen can be designed and operated for neglect with an anaerobic unit.

  17. Physiological factors affecting carbon tetrachloride dehalogenation by the denitrifying bacterium Pseudomonas sp. strain KC.

    PubMed Central

    Lewis, T A; Crawford, R L

    1993-01-01

    Pseudomonas sp. strain KC was grown on a medium with a low content of transition metals in order to examine the conditions for carbon tetrachloride (CT) transformation. Several carbon sources, including acetate, glucose, glycerol, and glutamate, were able to support CT transformation. The chelators 2,2'-dipyridyl and 1,10-phenanthroline stimulated CT transformation in a rich medium that otherwise did not support this activity. Low (< 10 microM) additions of dissolved iron(II), iron(III), and cobalt(II), as well as an insoluble iron(III) compound, ferric oxyhydroxide, inhibited CT transformation. The addition of 50 microM iron to actively growing cultures resulted in delayed inhibition of CT transformation. CT transformation was seen in aerobic cultures of KC, but with reduced efficiency compared with denitrifying cultures. Inhibition of CT transformation by iron was also seen in aerobically grown cultures. Optimal conditions were used in searching for effective CT transformation activity among denitrifying enrichments grown from samples of aquifer material. No activity comparable to that of Pseudomonas sp. strain KC was found among 16 samples tested. PMID:8517754

  18. Biodegradation of three- and four-ring polycyclic aromatic hydrocarbons under aerobic and denitrifying conditions

    SciTech Connect

    McNally, D.L.; Mihelcic, J.R.; Lueking, D.R.

    1998-09-01

    PAHs are thought to be particularly persistent in environments where anaerobic conditions exist. This study presents evidence for the biodegradation of three- and four-ringed PAHs (anthracene, phenanthrene, and pyrene) under strict anaerobic, denitrifying conditions. Three pseudomonad strains, isolated from contrasting environments, were used in this study. All three strains were known PAH degraders and denitrifiers. Degradation proceeded to nondetectable levels in 12--80 h for anthracene, 12--44 h for phenanthrene, and 24--72 h for pyrene. The rates of anaerobic degradation were typically slower than under aerobic conditions in almost all cases, except for strain SAG-R which had similar removal rates for all three and four-ring PAHs. Denitrification activity was verified by monitoring nitrate utilization and nitrous oxide production. Although none of the pseudomonads were adapted to the denitrifying conditions, only the pseudomonad isolated from a noncontaminated site consistently exhibited an adaptation period which approximated 12 h. This study supports growing evidence that the degradation of aromatic hydrocarbons coupled to denitrification may be an important factor affecting the fate of these compounds in natural and engineered systems.

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

    SciTech Connect

    Coyne, P.; Smith, G.

    1995-08-15

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

  20. Enhanced performance of denitrifying sulfide removal process at high carbon to nitrogen ratios under micro-aerobic condition.

    PubMed

    Chen, Chuan; Zhang, Ruo-Chen; Xu, Xi-Jun; Fang, Ning; Wang, Ai-Jie; Ren, Nan-Qi; Lee, Duu-Jong

    2017-02-11

    The success of denitrifying sulfide removal (DSR) processes, which simultaneously degrade sulfide, nitrate and organic carbon in the same reactor, counts on synergetic growths of autotrophic and heterotrophic denitrifiers. Feeding wastewaters at high C/N ratio would stimulate overgrowth of heterotrophic bacteria in the DSR reactor so deteriorating the growth of autotrophic denitrifiers. The DSR tests at C/N=1.26:1, 2:1 or 3:1 and S/N =5:6 or 5:8 under anaerobic (control) or micro-aerobic conditions were conducted. Anaerobic DSR process has <50% sulfide removal with no elemental sulfur transformation. Under micro-aerobic condition to remove <5% sulfide by chemical oxidation pathway, 100% sulfide removal is achieved by the DSR consortia. Continuous-flow tests under micro-aerobic condition have 70% sulfide removal and 55% elemental sulfur recovery. Trace oxygen enhances activity of sulfide-oxidizing, nitrate-reducing bacteria to accommodate properly the wastewater with high C/N ratios.

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

    PubMed Central

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

    2015-01-01

    Treatment of micro-polluted source water is receiving increasing attention because of environmental awareness on a global level. We isolated and identified aerobic denitrifying bacteria Zoogloea sp. N299, Acinetobacter sp. G107, and Acinetobacter sp. 81Y and used these to remediate samples of their native source water. We first domesticated the isolated strains in the source water, and the 48-h nitrate removal rates of strains N299, G107, and 81Y reached 33.69%, 28.28%, and 22.86%, respectively, with no nitrite accumulation. We then conducted a source-water remediation experiment and cultured the domesticated strains (each at a dry cell weight concentration of 0.4 ppm) together in a sample of source water at 20–26 °C and a dissolved oxygen concentration of 3–7 mg/L for 60 days. The nitrate concentration of the system decreased from 1.57 ± 0.02 to 0.42 ± 0.01 mg/L and that of a control system decreased from 1.63 ± 0.02 to 1.30 ± 0.01 mg/L, each with no nitrite accumulation. Total nitrogen of the bacterial system changed from 2.31 ± 0.12 to 1.09 ± 0.01 mg/L, while that of the control system changed from 2.51 ± 0.13 to 1.72 ± 0.06 mg/L. The densities of aerobic denitrification bacteria in the experimental and control systems ranged from 2.8 × 104 to 2 × 107 cfu/mL and from 7.75 × 103 to 5.5 × 105 cfu/mL, respectively. The permanganate index in the experimental and control systems decreased from 5.94 ± 0.12 to 3.10 ± 0.08 mg/L and from 6.02 ± 0.13 to 3.61 ± 0.11 mg/L, respectively, over the course of the experiment. Next, we supplemented samples of the experimental and control systems with additional bacteria or additional source water and cultivated the systems for another 35 days. The additional bacteria did little to improve the water quality. The additional source water provided supplemental carbon and brought the nitrate removal rate in the experimental system to 16.97%, while that in the control system reached only 3.01%, with no nitrite

  2. Variovorax ginsengisoli sp. nov., a denitrifying bacterium isolated from soil of a ginseng field.

    PubMed

    Im, Wan-Taek; Liu, Qing-Mei; Lee, Kang-Jin; Kim, Se-Young; Lee, Sung-Taik; Yi, Tae-Hoo

    2010-07-01

    A Gram-negative, aerobic or facultatively anaerobic, non-spore-forming, motile, rod-shaped bacterium (strain Gsoil 3165(T)) was isolated from soil of a ginseng field in Pocheon, South Korea. Its taxonomic position was determined by using a polyphasic approach. On the basis of 16S rRNA gene sequence analysis, strain Gsoil 3165(T) was shown to belong to the family Comamonadaceae, class Betaproteobacteria, and was related most closely to the type strains of Variovorax boronicumulans (98.9 % similarity), Variovorax paradoxus (98.3 %), Variovorax soli (98.2 %) and Variovorax dokdonensis (96.6 %). Levels of 16S rRNA gene sequence similarity between strain Gsoil 3165(T) and the type strains of other species in the family Comamonadaceae were less than 97.0 %. The G+C content of the genomic DNA of strain Gsoil 3165(T) was 66 mol%. Phenotypic and chemotaxonomic data (Q-8 as the major ubiquinone; C(16 : 0) and C(17 : 0) cyclo as major fatty acids) supported the affiliation of strain Gsoil 3165(T) to the genus Variovorax. The results of physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain Gsoil 3165(T) from recognized Variovorax species. Gsoil 3165(T) is therefore considered to represent a novel species of the genus Variovorax, for which the name Variovorax ginsengisoli sp. nov. is proposed. The type strain is Gsoil 3165(T) (=KCTC 12583(T) =LMG 23392(T)).

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

    PubMed

    Guo, Liyun; Chen, Qiankun; Fang, Fei; Hu, Zhixin; Wu, Jun; Miao, Aijun; Xiao, Lin; Chen, Xiaofeng; Yang, Liuyan

    2013-08-01

    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.

  4. Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation by Thiobacillus denitrificans Under Aerobic vs. Denitrifying Conditions

    SciTech Connect

    Beller, H R; Letain, T E; Chakicherla, A; Kane, S R; Legler, T C; Coleman, M A

    2006-04-22

    Thiobacillus denitrificans is one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with ke chemolithoautotrophic functions (such as sulfur-compound oxidation and CO2 fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately ten percent of the genome) as differentially expressed using Robust Multi-array Average statistical analysis and a 2-fold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochrome cbb3 oxidase genes, cbbL and cbbS (encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions included nar, nir, and nor genes (associated respectively with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification), cbbM (encoding form II RubisCO), and genes involved with sulfur-compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and of dsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the order nar > nir > nor > nos. Reverse transcription, quantitative PCR analysis was used to validate these trends.

  5. Interaction of Cadmium With the Aerobic Bacterium Pseudomonas Mendocina

    NASA Astrophysics Data System (ADS)

    Schramm, P. J.; Haack, E. A.; Maurice, P. A.

    2006-05-01

    The fate of toxic metals in the environment can be heavily influenced by interaction with bacteria in the vadose zone. This research focuses on the interactions of cadmium with the strict aerobe Pseudomonas mendocina. P. mendocina is a gram-negative bacterium that has shown potential in the bioremediation of recalcitrant organic compounds. Cadmium is a common environmental contaminant of wide-spread ecological consequence. In batch experiments P. mendocina shows typical bacterial growth curves, with an initial lag phase followed by an exponential phase and a stationary to death phase; concomitant with growth was an increase in pH from initial values of 7 to final values at 96 hours of 8.8. Cd both delays the onset of the exponential phase and decreases the maximum population size, as quantified by optical density and microscopic cell counts (DAPI). The total amount of Cd removed from solution increases over time, as does the amount of Cd removed from solution normalized per bacterial cell. Images obtained with transmission electron microscopy (TEM) showed the production of a cadmium, phosphorus, and iron containing precipitate that was similar in form and composition to precipitates formed abiotically at elevated pH. However, by late stationary phase, the precipitate had been re-dissolved, perhaps by biotic processes in order to obtain Fe. Stressed conditions are suggested by TEM images showing the formation of pili, or nanowires, when 20ppm Cd was present and a marked decrease in exopolysaccharide and biofilm material in comparison to control cells (no cadmium added).

  6. Denitratimonas tolerans gen. nov., sp. nov., a denitrifying bacterium isolated from a bioreactor for tannery wastewater treatment.

    PubMed

    Han, Song-Ih; Kim, Ju-Ok; Lee, Ye-Rim; Ekpeghere, Kalu I; Koh, Sung-Cheol; Whang, Kyung-Sook

    2016-06-01

    A denitrifying bacterium, designated strain E4-1(T), was isolated from a bioreactor for tannery wastewater treatment, and its taxonomic position was investigated using a polyphasic approach. Strain E4-1(T), a facultative anaerobic bacterium, was observed to grow between 0 and 12 % (w/v) NaCl, between pH 3.0 and 12.0. Cells were found to be oxidase-positive and catalase-negative. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain E4-1(T) forms a distinct lineage with respect to closely related genera in the family Xanthomonadaceae, and is closely related to Chiayiivirga, Aquimonas and Dokdonella, and the levels of 16S rRNA gene sequence similarity with respect to the type species of related genera are less than 93.9 %. The predominant respiratory quinone was determined to be ubiquinone-8 (Q-8) and the major cellular fatty acids were determined to be iso-C15:0, iso-C17:1 ω9c, iso-C11:0 and iso-C11:0 3OH. Based on physiological, biochemical and chemotaxonomic properties together with results of comparative 16S rRNA gene sequence analysis, strain E4-1(T) is considered to represent a novel species in a new genus, for which the name Denitratimonas tolerans gen. nov., sp. nov. is proposed. The type strain is E4-1(T) (=KACC 17565(T) = NCAIM B 025327(T)).

  7. The effect of nitrite on aerobic phosphate uptake and denitrifying activity of phosphate-accumulating organisms.

    PubMed

    Yoshida, Y; Takahashi, K; Saito, T; Tanaka, K

    2006-01-01

    An anaerobic/aerobic/anoxic/aerobic sequencing batch reactor (SBR) was operated with municipal wastewater to investigate the effect of nitrite on biological phosphorus removal (BPR). When nitrite accumulated, aerobic phosphate uptake activity significantly decreased and, in case of hard exposure to nitrite, BPR severely deteriorated. The interesting observation was that the relative anoxic activity of phosphate accumulating organisms (PAOs) increased after nitrite exposure. Moreover batch tests of aerobic phosphate uptake in the presence/absence of nitrite indicated that PAOs with the higher relative anoxic activity are less sensitive to nitrite exposure. From these results, we concluded that BPR is sensitive to nitrite exposure, but BPR containing PAOs with the higher relative anoxic activity is possibly more stable against nitrite than BPR containing PAOs with the lower relative anoxic activity.

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

    PubMed

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

    2012-11-01

    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.

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

    PubMed

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

    2016-08-01

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

  10. Nitrogen Removal Characteristics of a Newly Isolated Indigenous Aerobic Denitrifier from Oligotrophic Drinking Water Reservoir, Zoogloea sp. N299.

    PubMed

    Huang, Ting-Lin; Zhou, Shi-Lei; Zhang, Hai-Han; Bai, Shi-Yuan; He, Xiu-Xiu; Yang, Xiao

    2015-05-04

    Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA). Its specific growth rate was 0.22 h-1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53%±1.69% and 58.65%±0.61%, respectively. The ammonia removal rate reached 44.12%±1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5-9 mg/L, pH 8-9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41%±3.17% (sterilized) and 44.88%±4.31% (unsterilized). The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p<0.05). High C/N was beneficial for nitrate reduction (p<0.05). The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p>0.05). Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem.

  11. Brevibacillus ginsengisoli sp. nov., a denitrifying bacterium isolated from soil of a ginseng field.

    PubMed

    Baek, Sang-Hoon; Im, Wan-Taek; Oh, Hyun Woo; Lee, Jung-Sook; Oh, Hee-Mock; Lee, Sung-Taik

    2006-11-01

    A Gram-positive, rod-shaped, spore-forming bacterium, Gsoil 3088T, was isolated from soil from a ginseng field in Pocheon Province in South Korea and characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 3088T was shown to belong to the family Paenibacillaceae, being related to Brevibacillus centrosporus (96.6%), Brevibacillus borstelensis (96.3%), Brevibacillus parabrevis (96.1%), Brevibacillus formosus (96.1%), Brevibacillus brevis (96.1%) and Brevibacillus laterosporus (96.0%). The phylogenetic distances from other validly described species within the genus Brevibacillus were greater than 4.0% (i.e. there was less than 96.0% similarity). The G+C content of the genomic DNA was 52.1 mol%. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; fatty acid profile, iso-C15:0, iso-C14:0 and anteiso-C15:0) supported the affiliation of strain Gsoil 3088T to the genus Brevibacillus. The results of physiological and biochemical tests allowed strain Gsoil 3088T to be distinguished genotypically and phenotypically from Brevibacillus species with validly published names. Strain Gsoil 3088T, therefore, represents a novel species of the genus Brevibacillus, for which the name Brevibacillus ginsengisoli sp. nov. is proposed. The type strain is Gsoil 3088T (=KCTC 13938T=LMG 23403T).

  12. Alcaligenes faecalis subsp. phenolicus subsp. nov. a phenol-degrading, denitrifying bacterium isolated from a graywater bioprocessor.

    PubMed

    Rehfuss, Marc; Urban, James

    2005-07-01

    A Gram (-) coccobacillary bacterium, J(T), was isolated from a graywater bioprocessor. 16S rRNA and biochemical analysis has revealed strain J(T) closely resembles Alcaligenes faecalis ATCC 8750T and A. faecalis subsp. parafaecalis DSM 13975T, but is a distinct, previously uncharacterized isolate. Strain J(T), along with the type strain of A. faecalis and its previously described subspecies share the ability to aerobically degrade phenol. The degradation rates of phenol for strain J(T) and reference phenol degrading bacteria were determined by photometrically measuring the change in optical density when grown on 0.1% phenol as the sole carbon source, followed by addition of Gibb's reagent to measure depletion of substrate. The phenol degradation rates of strain J(T) was found to exceed that of the phenol hydroxylase group III bacterium Pseudomonas pseudoalcaligenes, with isolate J(T) exhibiting a doubling time of 4.5 h. The presence of the large subunit of the multicomponent phenol hydroxylase gene in strain J(T) was confirmed by PCR. The presence of the nirK nitrite reductase gene as demonstrated by PCR as well as results obtained from nitrite media indicated denitrification at least to N2O. Based on phenotypic, phylogenetic, fatty acid analysis and results from DNA DNA hybridization, we propose assigning a novel subspecies of Alcaligenes faecalis, to be named Alcaligenes faecalis subsp. phenolicus with the type strain J(T) (= DSM 16503) (= NRRL B-41076).

  13. MALDI-TOF MS Imaging evidences spatial differences in the degradation of solid polycaprolactone diol in water under aerobic and denitrifying conditions.

    PubMed

    Rivas, Daniel; Ginebreda, Antoni; Pérez, Sandra; Quero, Carmen; Barceló, Damià

    2016-10-01

    Degradation of solid polymers in the aquatic environment encompasses a variety of biotic and abiotic processes giving rise to heterogeneous patterns across the surface of the material, which cannot be investigated using conventional Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that only renders an "average" picture of the sample. In that context, MALDI-TOF MS Imaging (MALDI MSI) provides a rapid and efficient tool to study 2D spatial changes occurred in the chemical composition of the polymer surface. Commercial polycaprolactone diol (average molecular weight of 1250Da) was selected as test material because it had been previously known to be amenable to biological degradation. The test oligomer probe was incubated under aerobic and denitrifying conditions using synthetic water and denitrifying mixed liquor obtained from a wastewater treatment plant respectively. After ca. seven days of exposure the mass spectra obtained by MALDI MSI showed the occurrence of chemical modifications in the sample surface. Observed heterogeneity across the probe's surface indicated significant degradation and suggested the contribution of biotic processes. The results were investigated using different image processing tools. Major changes on the oligomer surface were observed when exposed to denitrifying conditions.

  14. Aerobic Reduction of Arsenate by a Bacterium Isolated From Activated Sludge

    NASA Astrophysics Data System (ADS)

    Kozai, N.; Ohnuki, T.; Hanada, S.; Nakamura, K.; Francis, A. J.

    2006-12-01

    Microlunatus phosphovorus strain NM-1 is a polyphosphate-accumulating bacterium isolated from activated sludge. This bacterium takes up a large amount of polyphosphate under aerobic conditions and release phosphate ions by hydrolysis of polyphosphate to orthophosphate under anaerobic conditions to derive energy for taking up substrates. To understand the nature of this strain, especially, influence of potential contaminants in sewage and wastewater on growth, we have been investigating behavior of this bacterium in media containing arsenic. The present paper mainly reports reduction of arsenate by this bacterium under aerobic conditions. The strain NM-1 (JCM 9379) was aerobically cultured at 30 °C in a nutrient medium containing 2.5 g/l peptone, 0.5 g/l glucose, 1.5 g/l yeast extract, and arsenic [Na2HAsO4 (As(V)) or Na3AsO3 (As(III))] at concentrations between 0 and 50 mM. The cells collected from arsenic-free media were dispersed in buffer solutions containing 2mM HEPES, 10mM NaCl, prescribed concentrations of As(V), and 0-0.2 percent glucose. Then, this cell suspension was kept at 20 °C under aerobic or anaerobic conditions. The speciation of arsenic was carried out by ion chromatography and ICP-MS. The growth of the strain under aerobic conditions was enhanced by the addition of As(V) at the concentration between 1 and 10 mM. The maximum optical density of the culture in the medium containing 5mM As(V) was 1.4 times greater than that of the control culture. Below the As(V) concentration of 10mM, most of the As(V) was reduced to As(III). The growth of the strain under anaerobic conditions has not been observed so far. The cells in the buffer solutions reduced As(V) under aerobic condition. The reduction was enhanced by the addition of glucose. However, the cell did not reduce As(V) under anaerobic conditions. The strain NM-1 showed high resistance to As(V) and As(III). The maximum optical density of the culture grown in a medium containing 50 mM As(V) was only

  15. Degradation of toluene by a mixed population of archetypal aerobes, microaerophiles, and denitrifiers: laboratory sand column experiment and multispecies biofilm model formulation.

    PubMed

    Kim, Hyun-Su; Jaffé, Peter R

    2008-02-01

    An experiment was conducted in a saturated sand column with three bacterial strains that have different growth characteristics on toluene, Pseudomonas putida F1 which degrades toluene only under aerobic conditions, Thauera aromatica T1 which degrades toluene only under denitrifying conditions, and Ralstonia pickettii PKO1 has a facultative nature and can perform nitrate-enhanced biodegradation of toluene under hypoxic conditions (DO <2 mg/L). Steady-state concentration profiles showed that oxygen and nitrate appeared to be utilized simultaneously, regardless of the dissolved oxygen concentration and the results from fluorescent in-situ hybridization (FISH) indicated that PKO1 maintained stable cells numbers throughout the column, even when the pore water oxygen concentration was high. Since PKO1's growth rate under aerobic condition is much lower than that of F1, except under hypoxic conditions, these observations were not anticipated. Therefore these observations require a mechanistic explanation that can account for localized low oxygen concentrations under aerobic conditions. To simulate the observed dynamics, a multispecies biofilm model was implemented. This model formulation assumes the formation of a thin biofilm that is composed of the three bacterial strains. The individual strains grow in response to the substrate and electron acceptor flux from bulk fluid into the biofilm. The model was implemented such that internal changes in bacterial composition and substrate concentration can be simulated over time and space. The model simulations from oxic to denitrifying conditions compared well to the experimental profiles of the chemical species and the bacterial strains, indicating the importance of accounting for the biological activity of individual strains in biofilms that span different redox conditions.

  16. Simultaneous heterotrophic nitrification and aerobic denitrification by the marine origin bacterium Pseudomonas sp. ADN-42.

    PubMed

    Jin, Ruofei; Liu, Tianqi; Liu, Guangfei; Zhou, Jiti; Huang, Jianyu; Wang, Aijie

    2015-02-01

    Recent research has highlighted the existence of some bacteria that are capable of performing heterotrophic nitrification and have a phenomenal ability to denitrify their nitrification products under aerobic conditions. A high-salinity-tolerant strain ADN-42 was isolated from Hymeniacidon perleve and found to display high heterotrophic ammonium removal capability. This strain was identified as Pseudomonas sp. via 16S rRNA gene sequence analysis. Gene cloning and sequencing analysis indicated that the bacterial genome contains N2O reductase function (nosZ) gene. NH3-N removal rate of ADN-42 was very high. And the highest removal rate was 6.52 mg/L · h in the presence of 40 g/L NaCl. Under the condition of pure oxygen (DO >8 mg/L), NH3-N removal efficiency was 56.9 %. Moreover, 38.4 % of oxygen remained in the upper gas space during 72 h without greenhouse gas N2O production. Keeping continuous and low level of dissolved oxygen (DO <3 mg/L) was helpful for better denitrification performance. All these results indicated that the strain has heterotrophic nitrification and aerobic denitrification abilities, which guarantee future application in wastewater treatment.

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

    PubMed Central

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

    2015-01-01

    Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3−-N could be removed or reduced, some amount of NO2−-N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy. PMID:26257096

  18. Dissolution of Fe(III)(hydr)oxides by an Aerobic Bacterium

    SciTech Connect

    Maurice, P.

    2004-12-13

    This project investigated the effects of an aerobic Pseudomonas mendocina bacterium on the dissolution of Fe(III)(hydr)oxides. The research is important because metals and radionuclides that adsorb to Fe(III)(hydr)oxides could potentially be remobilized by dissolving bacteria. We showed that P. mendocina is capable of dissolving Fe-bearing minerals by a variety of mechanisms, including production of siderophores, pH changes, and formation of reductants. The production of siderophores by P. mendocina was quantified under a variety of growth conditions. Finally, we demonstrated that microbial siderophores may adsorb to and enhance dissolution of clay minerals.

  19. Nesterenkonia sp. strain F, a halophilic bacterium producing acetone, butanol, and ethanol under aerobic conditions

    PubMed Central

    Amiri, Hamid; Azarbaijani, Reza; Parsa Yeganeh, Laleh; Shahzadeh Fazeli, Abolhassan; Tabatabaei, Meisam; Hosseini Salekdeh, Ghasem; Karimi, Keikhosro

    2016-01-01

    The moderately halophilic bacterium Nesterenkonia sp. strain F, which was isolated from Aran-Bidgol Lake (Iran), has the ability to produce acetone, butanol, and ethanol (ABE) as well as acetic and butyric acids under aerobic and anaerobic conditions. This result is the first report of ABE production with a wild microorganism from a family other than Clostridia and also the first halophilic species shown to produce butanol under aerobic cultivation. The cultivation of Nesterenkonia sp. strain F under anaerobic conditions with 50 g/l of glucose for 72 h resulted in the production of 105 mg/l of butanol, 122 mg/l of acetone, 0.2 g/l of acetic acid, and 2.5 g/l of butyric acid. Furthermore, the strain was cultivated on media with different glucose concentrations (20, 50, and 80 g/l) under aerobic and anaerobic conditions. Through fermentation with a 50 g/l initial glucose concentration under aerobic conditions, 66 mg/l of butanol, 125 mg/l of acetone, 291 mg/l of ethanol, 5.9 g/l of acetic acid, and 1.2 g/l of butyric acid were produced. The enzymes pertaining to the fermentation pathway in the strain were compared with the enzymes of Clostridium spp., and the metabolic pathway of fermentation used by Nesterenkonia sp. strain F was investigated. PMID:26725518

  20. Nesterenkonia sp. strain F, a halophilic bacterium producing acetone, butanol, and ethanol under aerobic conditions.

    PubMed

    Amiri, Hamid; Azarbaijani, Reza; Parsa Yeganeh, Laleh; Shahzadeh Fazeli, Abolhassan; Tabatabaei, Meisam; Salekdeh, Ghasem Hosseini; Karimi, Keikhosro

    2016-01-04

    The moderately halophilic bacterium Nesterenkonia sp. strain F, which was isolated from Aran-Bidgol Lake (Iran), has the ability to produce acetone, butanol, and ethanol (ABE) as well as acetic and butyric acids under aerobic and anaerobic conditions. This result is the first report of ABE production with a wild microorganism from a family other than Clostridia and also the first halophilic species shown to produce butanol under aerobic cultivation. The cultivation of Nesterenkonia sp. strain F under anaerobic conditions with 50 g/l of glucose for 72 h resulted in the production of 105 mg/l of butanol, 122 mg/l of acetone, 0.2 g/l of acetic acid, and 2.5 g/l of butyric acid. Furthermore, the strain was cultivated on media with different glucose concentrations (20, 50, and 80 g/l) under aerobic and anaerobic conditions. Through fermentation with a 50 g/l initial glucose concentration under aerobic conditions, 66 mg/l of butanol, 125 mg/l of acetone, 291 mg/l of ethanol, 5.9 g/l of acetic acid, and 1.2 g/l of butyric acid were produced. The enzymes pertaining to the fermentation pathway in the strain were compared with the enzymes of Clostridium spp., and the metabolic pathway of fermentation used by Nesterenkonia sp. strain F was investigated.

  1. Isolation and Characterization of Novel Denitrifying Bacterium Geobacillus sp. SG-01 Strain from Wood Chips Composted with Swine Manure

    PubMed Central

    Yang, Seung-Hak; Cho, Jin-Kook; Lee, Soon-Youl; Abanto, Oliver D.; Kim, Soo-Ki; Ghosh, Chiranjit; Lim, Joung-Soo; Hwang, Seong-Gu

    2013-01-01

    Nitrate contamination in ground and surface water is an increasingly serious environmental problem and only a few bacterial strains have been identified that have the ability to remove nitrogen pollutants from wastewater under thermophilic conditions. We therefore isolated thermophilic facultative bacterial strains from wood chips that had been composted with swine manure under aerated high temperature conditions so as to identify strains with denitrifying ability. Nine different colonies were screened and 3 long rod-shaped bacterial strains designated as SG-01, SG-02, and SG-03 were selected. The strain SG-01 could be differentiated from SG-02 and SG-03 on the basis of the method that it used for sugar utilization. The 16S rRNA genes of this strain also had high sequence similarity with Geobacillus thermodenitrificans 465T (99.6%). The optimal growth temperatures (55°C), pH values (pH 7.0), and NaCl concentrations (1%) required for the growth of strain SG-01 were established. This strain reduced 1.18 mM nitrate and 1.45 mM nitrite in LB broth after 48 h of incubation. These results suggest that the G. thermodenitrificans SG-01 strain may be useful in the removal of nitrates and nitrites from wastewater generated as a result of livestock farming. PMID:25049754

  2. A new intra-aerobic metabolism in the nitrite-dependent anaerobic methane-oxidizing bacterium Candidatus 'Methylomirabilis oxyfera'.

    PubMed

    Wu, Ming L; Ettwig, Katharina F; Jetten, Mike S M; Strous, Marc; Keltjens, Jan T; van Niftrik, Laura

    2011-01-01

    Biological methane oxidation proceeds either through aerobic or anaerobic pathways. The newly discovered bacterium Candidatus 'Methylomirabilis oxyfera' challenges this dichotomy. This bacterium performs anaerobic methane oxidation coupled to denitrification, but does so in a peculiar way. Instead of scavenging oxygen from the environment, like the aerobic methanotrophs, or driving methane oxidation by reverse methanogenesis, like the methanogenic archaea in sulfate-reducing systems, it produces its own supply of oxygen by metabolizing nitrite via nitric oxide into oxygen and dinitrogen gas. The intracellularly produced oxygen is then used for the oxidation of methane by the classical aerobic methane oxidation pathway involving methane mono-oxygenase. The present mini-review summarizes the current knowledge about this process and the micro-organism responsible for it.

  3. Metabolism of 2-methylpropene (isobutylene) by the aerobic bacterium Mycobacterium sp. strain ELW1.

    PubMed

    Kottegoda, Samanthi; Waligora, Elizabeth; Hyman, Michael

    2015-03-01

    An aerobic bacterium (Mycobacterium sp. strain ELW1) that utilizes 2-methylpropene (isobutylene) as a sole source of carbon and energy was isolated and characterized. Strain ELW1 grew on 2-methylpropene (growth rate = 0.05 h(-1)) with a yield of 0.38 mg (dry weight) mg 2-methylpropene(-1). Strain ELW1 also grew more slowly on both cis- and trans-2-butene but did not grow on any other C2 to C5 straight-chain, branched, or chlorinated alkenes tested. Resting 2-methylpropene-grown cells consumed ethene, propene, and 1-butene without a lag phase. Epoxyethane accumulated as the only detected product of ethene oxidation. Both alkene consumption and epoxyethane production were fully inhibited in cells exposed to 1-octyne, suggesting that alkene oxidation is initiated by an alkyne-sensitive, epoxide-generating monooxygenase. Kinetic analyses indicated that 1,2-epoxy-2-methylpropane is rapidly consumed during 2-methylpropene degradation, while 2-methyl-2-propen-1-ol is not a significant metabolite of 2-methylpropene catabolism. Degradation of 1,2-epoxy-2-methylpropane by 2-methylpropene-grown cells led to the accumulation and further degradation of 2-methyl-1,2-propanediol and 2-hydroxyisobutyrate, two sequential metabolites previously identified in the aerobic microbial metabolism of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Growth of strain ELW1 on 2-methylpropene, 1,2-epoxy-2-methylpropane, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate was fully inhibited when cobalt ions were omitted from the growth medium, while growth on 3-hydroxybutyrate and other substrates was unaffected by the absence of added cobalt ions. Our results suggest that, like aerobic MTBE- and TBA-metabolizing bacteria, strain ELW1 utilizes a cobalt/cobalamin-dependent mutase to transform 2-hydroxyisobutyrate. Our results have been interpreted in terms of their impact on our understanding of the microbial metabolism of alkenes and ether oxygenates.

  4. Metabolism of 2-Methylpropene (Isobutylene) by the Aerobic Bacterium Mycobacterium sp. Strain ELW1

    PubMed Central

    Kottegoda, Samanthi; Waligora, Elizabeth

    2015-01-01

    An aerobic bacterium (Mycobacterium sp. strain ELW1) that utilizes 2-methylpropene (isobutylene) as a sole source of carbon and energy was isolated and characterized. Strain ELW1 grew on 2-methylpropene (growth rate = 0.05 h−1) with a yield of 0.38 mg (dry weight) mg 2-methylpropene−1. Strain ELW1 also grew more slowly on both cis- and trans-2-butene but did not grow on any other C2 to C5 straight-chain, branched, or chlorinated alkenes tested. Resting 2-methylpropene-grown cells consumed ethene, propene, and 1-butene without a lag phase. Epoxyethane accumulated as the only detected product of ethene oxidation. Both alkene consumption and epoxyethane production were fully inhibited in cells exposed to 1-octyne, suggesting that alkene oxidation is initiated by an alkyne-sensitive, epoxide-generating monooxygenase. Kinetic analyses indicated that 1,2-epoxy-2-methylpropane is rapidly consumed during 2-methylpropene degradation, while 2-methyl-2-propen-1-ol is not a significant metabolite of 2-methylpropene catabolism. Degradation of 1,2-epoxy-2-methylpropane by 2-methylpropene-grown cells led to the accumulation and further degradation of 2-methyl-1,2-propanediol and 2-hydroxyisobutyrate, two sequential metabolites previously identified in the aerobic microbial metabolism of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Growth of strain ELW1 on 2-methylpropene, 1,2-epoxy-2-methylpropane, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate was fully inhibited when cobalt ions were omitted from the growth medium, while growth on 3-hydroxybutyrate and other substrates was unaffected by the absence of added cobalt ions. Our results suggest that, like aerobic MTBE- and TBA-metabolizing bacteria, strain ELW1 utilizes a cobalt/cobalamin-dependent mutase to transform 2-hydroxyisobutyrate. Our results have been interpreted in terms of their impact on our understanding of the microbial metabolism of alkenes and ether oxygenates. PMID:25576605

  5. Characterization of giant spheroplasts generated from the aerobic anoxygenic photosynthetic marine bacterium Roseobacter litoralis.

    PubMed

    Nojiri, Akane; Ogita, Shinjiro; Isogai, Yasuhiro; Nishida, Hiromi

    2015-01-01

    We generated and characterized giant spheroplasts from the aerobic anoxygenic photosynthetic marine bacterium Roseobacter litoralis. The giant spheroplasts contained vacuole-like structures within the cells, mainly consisting of a single membrane. The in vivo absorption spectrum of the giant spheroplasts did not have peaks typically observed for bacteriochlorophyll a. The culture media pH decreased during the growth of the giant spheroplasts. The change in the pH profile for cells grown under light was no different from that for cells grown in the dark. These results showed that the R. litoralis giant spheroplasts formed lost their photosynthetic apparatus in culture. Most of the giant spheroplasts returned to their original size, likely via filamentous cells. The culture media pH increased during the growth of the filamentous cells. Some filamentous cells had septum-like structures. In such filamentous cells, DNA was separated. Initially, the color of the separated cells was white. Two weeks later, the cells changed to red in the dark, and the in vivo absorption spectrum of the cells had peaks typically observed for bacteriochlorophyll a. Our findings strongly suggest that the giant spheroplasts of R. litoralis can control the genetic information, return to their original cell size, and regain their original functions.

  6. Biodegradation of bisphenol A and other bisphenols by a gram-negative aerobic bacterium

    SciTech Connect

    Lobos, J.H.; Leib, T.K. ); Tahmun Su )

    1992-06-01

    A novel bacterium designated strain MV1 was isolated from a sludge enrichmet takes from the wastewater treatment plant at a plastics manufacturing facility and shown to degrade 2,2-bis(4-hydroxyphenyl)propane (4,4[prime]-isopropylidenediphenol or bisphenol A). Strain MV1 is a gram-negative, aerobic bacillus that grows on bisphenol A as a sole source of carbon and energy. Total carbon analysis for bisphenol A degradation demonstrated that 60% of the carbon was mineralized to CO[sub 2], 20% was associated with the bacterial cells, and 20% was converted to soluble organic compounds. Metabolic intermediates detected in the culture medium during growth on bisphenol A were identified as 4-hydroxybenzoic acid, 4-hydroxyacetophenone, 2,2-bis(4-hydroxyphenyl)-1-propanol, and 2,3-bis(4-hydroxyphenyl)-1,2-propanediol. Most of the bisphenol A degraded by strain MV1 is cleaved in some way to form 4-hydroxybenzoic acid and 4-hydroxyacetophenone, which are subsequently mineralized or assimilated into cell carbon. In addition, about 20% of the bisphenol A is hydroxylated to form 2,2-bis(4-hydroxyphenyl)-1-propanol, which is slowly biotransformed to 2,3-bis(4-hydroxyphenyl)-1,2-propanediol. Cells that were grown on bisphenol A degraded a variety of bisphenol alkanes, hydroxylated benzoic acids, and hydroxylated acetophenones during resting-cell assays. Transmission electron microscopy of cells grown on bisphenol A revealed lipid storage granules and intracytoplasmic membranes.

  7. Aerobic degradation of mercaptosuccinate by the gram-negative bacterium Variovorax paradoxus strain B4.

    PubMed

    Carbajal-Rodríguez, Irma; Stöveken, Nadine; Satola, Barbara; Wübbeler, Jan Hendrik; Steinbüchel, Alexander

    2011-01-01

    The Gram-negative bacterium Variovorax paradoxus strain B4 was isolated from soil under mesophilic and aerobic conditions to elucidate the so far unknown catabolism of mercaptosuccinate (MS). During growth with MS this strain released significant amounts of sulfate into the medium. Tn5::mob-induced mutagenesis was successfully employed and yielded nine independent mutants incapable of using MS as a carbon source. In six of these mutants, Tn5::mob insertions were mapped in a putative gene encoding a molybdenum (Mo) cofactor biosynthesis protein (moeA). In two further mutants the Tn5::mob insertion was mapped in the gene coding for a putative molybdopterin (MPT) oxidoreductase. In contrast to the wild type, these eight mutants also showed no growth on taurine. In another mutant a gene putatively encoding a 3-hydroxyacyl-coenzyme A dehydrogenase (paaH2) was disrupted by transposon insertion. Upon subcellular fractionation of wild-type cells cultivated with MS as sole carbon and sulfur source, MPT oxidoreductase activity was detected in only the cytoplasmic fraction. Cells grown with succinate, taurine, or gluconate as a sole carbon source exhibited no activity or much lower activity. MPT oxidoreductase activity in the cytoplasmic fraction of the Tn5::mob-induced mutant Icr6 was 3-fold lower in comparison to the wild type. Therefore, a new pathway for MS catabolism in V. paradoxus strain B4 is proposed: (i) MPT oxidoreductase catalyzes the conversion of MS first into sulfinosuccinate (a putative organo-sulfur compound composed of succinate and a sulfino group) and then into sulfosuccinate by successive transfer of oxygen atoms, (ii) sulfosuccinate is cleaved into oxaloacetate and sulfite, and (iii) sulfite is oxidized to sulfate.

  8. Nitrogen Redox Metabolism of a Heterotrophic, Nitrifying-Denitrifying Alcaligenes sp. from Soil

    PubMed Central

    Castignetti, Domenic; Hollocher, Thomas C.

    1982-01-01

    Metabolic characteristics of a heterotrophic, nitrifier-denitrifier Alcaligenes sp. isolated from soil were further characterized. Pyruvic oxime and hydroxylamine were oxidized to nitrite aerobically by nitrification-adapted cells with specific activities (Vmax) of 0.066 and 0.003 μmol of N × min−1 × mg of protein−1, respectively, at 22°C. Km values were 15 and 42 μM for pyruvic oxime and hydroxylamine, respectively. The greater pyruvic oxime oxidation activity relative to hydroxylamine oxidation activity indicates that pyruvic oxime was a specific substrate and was not oxidized appreciably via its hydrolysis product, hydroxylamine. When grown as a denitrifier on nitrate, the bacterium could not aerobically oxidize pyruvic oxime or hydroxylamine to nitrite. However, hydroxylamine was converted to nearly equimolar amounts of ammonium ion and nitrous oxide, and the nature of this reaction is discussed. Cells grown as heterotrophic nitrifiers on pyruvic oxime contained two enzymes of denitrification, nitrate reductase and nitric oxide reductase. The nitrate reductase was the dissimilatory type, as evidenced by its extreme sensitivity to inhibition by azide and by its ability to be reversibly inhibited by oxygen. Cells grown aerobically on organic carbon sources other than pyruvic oxime contained none of the denitrifying enzymes surveyed but were able to oxidize pyruvic oxime to nitrite and reduce hydroxylamine to ammonium ion. PMID:16346117

  9. Involvement of NarK1 and NarK2 Proteins in Transport of Nitrate and Nitrite in the Denitrifying Bacterium Pseudomonas aeruginosa PAO1

    PubMed Central

    Sharma, Vandana; Noriega, Chris E.; Rowe, John J.

    2006-01-01

    Two transmembrane proteins were tentatively classified as NarK1 and NarK2 in the Pseudomonas genome project and hypothesized to play an important physiological role in nitrate/nitrite transport in Pseudomonas aeruginosa. The narK1 and narK2 genes are located in a cluster along with the structural genes for the nitrate reductase complex. Our studies indicate that the transcription of all these genes is initiated from a single promoter and that the gene complex narK1K2GHJI constitutes an operon. Utilizing an isogenic narK1 mutant, a narK2 mutant, and a narK1K2 double mutant, we explored their effect on growth under denitrifying conditions. While the ΔnarK1::Gm mutant was only slightly affected in its ability to grow under denitrification conditions, both the ΔnarK2::Gm and ΔnarK1K2::Gm mutants were found to be severely restricted in nitrate-dependent, anaerobic growth. All three strains demonstrated wild-type levels of nitrate reductase activity. Nitrate uptake by whole-cell suspensions demonstrated both the ΔnarK2::Gm and ΔnarK1K2::Gm mutants to have very low yet different nitrate uptake rates, while the ΔnarK1::Gm mutant exhibited wild-type levels of nitrate uptake. Finally, Escherichia coli narK rescued both the ΔnarK2::Gm and ΔnarK1K2::Gm mutants with respect to anaerobic respiratory growth. Our results indicate that only the NarK2 protein is required as a nitrate/nitrite transporter by Pseudomonas aeruginosa under denitrifying conditions. PMID:16391109

  10. Shewanella denitrificans sp. nov., a vigorously denitrifying bacterium isolated from the oxic-anoxic interface of the Gotland Deep in the central Baltic Sea.

    PubMed

    Brettar, Ingrid; Christen, Richard; Höfle, Manfred G

    2002-11-01

    Three strains of denitrifying estuarine bacteria, OS217(T), 05220 and OS226, were characterized for their physiological and biochemical features, fatty acid profiles and their phylogenetic position based on 16S rDNA sequences. The strains were isolated from the oxic-anoxic interface of an anoxic basin of the central Baltic Sea. Phylogenetic analyses of the 16S rDNA sequences revealed a clear affiliation with members of the genus Shewanella of the gamma-Proteobacteria. The closest sequence similarity was seen with Shewanella baltica, Shewanella putrefaciens and Shewanella frigidimarina (95-96%). The dominant fatty acids were 16:1omega7c, 15:0 iso, 16:0 and 13:0 iso. The G+C content of the DNA ranged from 46.8 to 48.1 mol%. The strains were unpigmented, polarly flagellated, mesophilic, facultatively anaerobic and able to use nitrate, nitrite and sulphite as electron acceptors. Growth was observed at salinities from 0 to 6%, with an optimum between 1 and 3%. According to their morphology, physiology, fatty acid composition and 16S rRNA sequences, the described bacteria fitted well into the genus Shewanella, but could be easily distinguished from the Shewanella species described to date. Because of their capacity for vigorous denitrification, the name Shewanella denitrificans sp. nov. is suggested for the Baltic isolates, for which the type strain is OS217(T) (= DSM 15013(T) = LMG 21692(T)).

  11. Melatonin production in an aerobic photosynthetic bacterium: an evolutionarily early association with darkness.

    PubMed

    Tilden, A R; Becker, M A; Amma, L L; Arciniega, J; McGaw, A K

    1997-03-01

    Melatonin was measured in a species of aerobic photosynthetic bacteria, Erythrobacter longus, grown in either constant light or constant dark. A radioimmunoassay was used to quantify melatonin levels and thin-layer chromatography to confirm the identity of melatonin immunoactivity. Melatonin levels were significantly higher (nearly 2.3-fold) in the dark-grown than in the light-grown samples. Also, the homogenates of the dark-grown bacteria retained melatonin-producing enzymatic activity, whereas the light-grown homogenates did not; melatonin levels extracted from the dark-grown homogenates increased with increasing extraction time, reaching as high as 29.2 ng.mg-1 protein at 120 min. Removal of membrane fragments from homogenates did not influence melatonin levels in light-grown homogenate, but this procedure increased melatonin levels in dark-grown homogenate, indicating that at least some of the enzymes in the pathway of melatonin production are not membrane-bound. This study is the second to demonstrate the presence of melatonin at the prokaryotic level, supporting the evidence that melatonin appeared very early in evolution. Its function in prokaryotes has not been determined, but may relate to its antioxidative actions.

  12. Aerobic-heterotrophic nitrogen removal through nitrate reduction and ammonium assimilation by marine bacterium Vibrio sp. Y1-5.

    PubMed

    Li, Yating; Wang, Yanru; Fu, Lin; Gao, Yizhan; Zhao, Haixia; Zhou, Weizhi

    2017-04-01

    An aerobic marine bacterium Vibrio sp. Y1-5 was screened to achieve efficient nitrate and ammonium removal simultaneously and fix nitrogen in cells without N loss. Approximately 98.0% of nitrate (100mg/L) was removed in 48h through assimilatory nitrate reduction and nitrate reductase was detected in the cytoplasm. Instead of nitrification, the strain assimilated ammonium directly, and it could tolerate as high as 1600mg/L ammonium concentration while removing 844.6mg/L. In addition, ammonium assimilation occurred preferentially in the medium containing nitrate and ammonium with a total nitrogen (TN) removal efficiency of 80.4%. The results of nitrogen balance and Fourier infrared spectra illustrated that the removed nitrogen was all transformed to protein or stored as organic nitrogen substances in cells and no N was lost in the process. Toxicological studies with the brine shrimp species Artemia naupliia indicated that Vibrio sp. Y1-5 can be applied in aquatic ecosystems safely.

  13. Engineering mediator-based electroactivity in the obligate aerobic bacterium Pseudomonas putida KT2440

    PubMed Central

    Schmitz, Simone; Nies, Salome; Wierckx, Nick; Blank, Lars M.; Rosenbaum, Miriam A.

    2015-01-01

    Pseudomonas putida strains are being developed as microbial production hosts for production of a range of amphiphilic and hydrophobic biochemicals. P. putida's obligate aerobic growth thereby can be an economical and technical challenge because it requires constant rigorous aeration and often causes reactor foaming. Here, we engineered a strain of P. putida KT2440 that can produce phenazine redox-mediators from Pseudomonas aeruginosa to allow partial redox balancing with an electrode under oxygen-limited conditions. P. aeruginosa is known to employ its phenazine-type redox mediators for electron exchange with an anode in bioelectrochemical systems (BES). We transferred the seven core phenazine biosynthesis genes phzA-G and the two specific genes phzM and phzS required for pyocyanin synthesis from P. aeruginosa on two inducible plasmids into P. putida KT2440. The best clone, P. putida pPhz, produced 45 mg/L pyocyanin over 25 h of growth, which was visible as blue color formation and is comparable to the pyocyanin production of P. aeruginosa. This new strain was then characterized under different oxygen-limited conditions with electrochemical redox control and changes in central energy metabolism were evaluated in comparison to the unmodified P. putida KT2440. In the new strain, phenazine synthesis with supernatant concentrations up to 33 μg/mL correlated linearly with the ability to discharge electrons to an anode, whereby phenazine-1-carboxylic acid served as the dominating redox mediator. P. putida pPhz sustained strongly oxygen-limited metabolism for up to 2 weeks at up to 12 μA/cm2 anodic current density. Together, this work lays a foundation for future oxygen-limited biocatalysis with P. putida strains. PMID:25914687

  14. Tumebacillus permanentifrigoris gen. nov., sp. nov., an aerobic, spore-forming bacterium isolated from Canadian high Arctic permafrost.

    PubMed

    Steven, Blaire; Chen, Min Qun; Greer, Charles W; Whyte, Lyle G; Niederberger, Thomas D

    2008-06-01

    A Gram-positive, aerobic, rod-shaped bacterium (strain Eur1 9.5(T)) was isolated from a 9-m-deep permafrost sample from the Canadian high Arctic. Strain Eur1 9.5(T) could not be cultivated in liquid medium and grew over the temperature range 5-37 degrees C; no growth was observed at 42 degrees C and only slow growth was observed at 5 degrees C following 1 month of incubation. Eur1 9.5(T) grew over the pH range 5.5-8.9 and tolerated NaCl concentrations of 0-0.5 % (w/v). Eur1 9.5(T) grew heterotrophically on complex carbon substrates and chemolithoautotrophically on inorganic sulfur compounds, as demonstrated by growth on sodium thiosulfate and sulfite as sole electron donors. Eur1 9.5(T) contained iso-C(15 : 0) as the major cellular fatty acid and menaquinone 7 (MK-7) as the major respiratory quinone. The cell-wall peptidoglycan was of type A1gamma. The DNA G+C content was 53.1 mol%. The 16S rRNA gene sequence of strain Eur1 9.5(T) was only distantly related (

  15. Biological removal of nitrate and ammonium under aerobic atmosphere by Paracoccus versutus LYM.

    PubMed

    Shi, Zhuang; Zhang, Yu; Zhou, Jiti; Chen, Mingxiang; Wang, Xiaojun

    2013-11-01

    The bacterium isolated from sea sludge Paracoccus versutus LYM was characterized with the ability of aerobic denitrification. Strain LYM performs perfect activity in aerobically converting over 95% NO3(-)-N (approximate 400mg L(-1)) to gaseous products via nitrite with maximum reduction rate 33 mg NO3(-)-N L(-1) h(-1). Besides characteristic of aerobic denitrification, strain LYM was confirmed in terms of the ability to be heterotrophic nitrification and aerobic denitrification (HNAD) with few accumulations of intermediates. After the nitrogen balance and enzyme assays, the putative nitrogen pathway of HNAD could be NH4(+) → NH2OH → NO2(-)→ NO3(-), then NO3(-) was denitrified to gaseous products via nitrite. N2 was sole denitrification product without any detection of N2O by gas chromatography. Strain LYM could also simultaneously remove ammonium and additional nitrate. Meanwhile, the accumulated nitrite had inhibitory effect on ammonium reduction rate.

  16. Anoxybacillus kamchatkensis sp. nov., a novel thermophilic facultative aerobic bacterium with a broad pH optimum from the Geyser valley, Kamchatka.

    PubMed

    Kevbrin, Vadim V; Zengler, Karsten; Lysenko, Anatolii M; Wiegel, Juergen

    2005-10-01

    A facultative aerobic, moderately thermophilic, spore forming bacterium, strain JW/VK-KG4 was isolated from an enrichment culture obtained from the Geyser valley, a geo-thermally heated environment located in the Kamchatka peninsula (Far East region of Russia). The cells were rod shaped, motile, peritrichous flagellated stained Gram positive and had a Gram positive type cell wall. Aerobically, the strain utilized a range of carbohydrates including glucose, fructose, trehalose, proteinuous substrates, and pectin as well. Anaerobically, only carbohydrates are utilized. When growing on carbohydrates, the strain required yeast extract and vitamin B(12). Anaerobically, glucose was fermented to lactate as main product and acetate, formate, ethanol as minor products. Aerobically, even in well-aerated cultures (agitated at 500 rpm), glucose oxidation was incomplete and lactate and acetate were found in culture supernatants as by-products. Optimal growth of the isolate was observed at pH(25 C) 6.8-8.5 and 60 degrees C. The doubling times on glucose at optimal growth conditions were 34 min (aerobically) and 40 min (anaerobically). The G+C content was 42.3 mol% as determined by T(m) assay. Sequence analysis of the 16S rRNA gene indicated an affiliation of strain JW/VK-KG4 with Anoxybacillus species. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA homology with validly published species of Anoxybacillus, it is proposed that strain JW/VK-KG4 represents a new species in the genus Anoxybacillus as A. kamchatkensis sp. nov. The type strain for the novel species is JW/VK-KG4(T) (=DSM 14988, =ATCC BAA-549). The GenBank accession number for the 16S rDNA sequence is AF510985.

  17. Microbiology and potential applications of aerobic methane oxidation coupled to denitrification (AME-D) process: A review.

    PubMed

    Zhu, Jing; Wang, Qian; Yuan, Mengdong; Tan, Giin-Yu Amy; Sun, Faqian; Wang, Cheng; Wu, Weixiang; Lee, Po-Heng

    2016-03-01

    Aerobic methane oxidation coupled to denitrification (AME-D) is an important link between the global methane and nitrogen cycles. This mini-review updates discoveries regarding aerobic methanotrophs and denitrifiers, as a prelude to spotlight the microbial mechanism and the potential applications of AME-D. Until recently, AME-D was thought to be accomplished by a microbial consortium where denitrifying bacteria utilize carbon intermediates, which are excreted by aerobic methanotrophs, as energy and carbon sources. Potential carbon intermediates include methanol, citrate and acetate. This mini-review presents microbial thermodynamic estimations and postulates that methanol is the ideal electron donor for denitrification, and may serve as a trophic link between methanotrophic bacteria and denitrifiers. More excitingly, new discoveries have revealed that AME-D is not only confined to the conventional synergism between methanotrophic bacteria and denitrifiers. Specifically, an obligate aerobic methanotrophic bacterium, Methylomonas denitrificans FJG1, has been demonstrated to couple partial denitrification with methane oxidation, under hypoxia conditions, releasing nitrous oxide as a terminal product. This finding not only substantially advances the understanding of AME-D mechanism, but also implies an important but unknown role of aerobic methanotrophs in global climate change through their influence on both the methane and nitrogen cycles in ecosystems. Hence, further investigation on AME-D microbiology and mechanism is essential to better understand global climate issues and to develop niche biotechnological solutions. This mini-review also presents traditional microbial techniques, such as pure cultivation and stable isotope probing, and powerful microbial techniques, such as (meta-) genomics and (meta-) transcriptomics, for deciphering linked methane oxidation and denitrification. Although AME-D has immense potential for nitrogen removal from wastewater, drinking

  18. Acquisition of Fe from Natural Organic Matter by an Aerobic Pseudomonas Bacterium: Siderophores and Cellular Fe Status

    NASA Astrophysics Data System (ADS)

    Koehn, K.; Dehner, C.; Dubois, J.; Maurice, P. A.

    2010-12-01

    Aerobic microorganisms have evolved various strategies to acquire nutrient Fe, including release of Fe-chelating siderophores. The potential importance of siderophores in Fe acquisition from natural organic matter (NOM) (reverse osmosis, RO; and XAD-8 samples with naturally associated Fe) was investigated using a wild type strain (WT) of aerobic Pseudomonas mendocina that produces siderophore(s) and an engineered mutant that cannot. Microbial growth under Fe-limited batch conditions was monitored via optical density, and a β-galactosidase biosensor assay was used to quantify cellular Fe status. Both WT and mutant strains acquired Fe from NOM. Fe ‘stress’ in the presence of the RO sample decreased with increasing [Fe] (as determined by different [DOC]s) and was consistently less for the WT. For both WT and mutant, maximum growth in the presence of RO sample increased as: 1 mgC/L (0.2μM Fe) < 100 mgC/L (20μM Fe) < 10 mgC/L (2μM Fe). Comparison of XAD-8 and RO samples ([DOC] varied to give 2μM [Fe]total for each), showed that although there were no apparent differences in internal Fe status, growth was better on the XAD-8 sample. Chelex treatment to partially remove metals associated with the RO sample increased Fe stress but did not substantially affect growth. Results demonstrated that: (1) siderophores are useful but not necessary for Fe acquisition from NOM by P. mendocina and (2) NOM may have complex effects on microbial growth, related not just to Fe content but potentially to the presence of other (trace)metals such as Al and/or to effects on biofilm development.

  19. Magnesium insertion by magnesium chelatase in the biosynthesis of zinc bacteriochlorophyll a in an aerobic acidophilic bacterium Acidiphilium rubrum.

    PubMed

    Masuda, T; Inoue, K; Masuda, M; Nagayama, M; Tamaki, A; Ohta, H; Shimada, H; Takamiya, K

    1999-11-19

    To elucidate the mechanism for formation of zinc-containing bacteriochlorophyll a in the photosynthetic bacterium Acidiphilium rubrum, we isolated homologs of magnesium chelatase subunits (bchI, -D, and -H). A. rubrum bchI and -H were encoded by single genes located on the clusters bchP-orf168-bchI-bchD-orf320-crtI and bchF-N-B-H-L as in Rhodobacter capsulatus, respectively. The deduced sequences of A. rubrum bchI, -D, and -H had overall identities of 59. 8, 40.5, and 50.7% to those from Rba. capsulatus, respectively. When these genes were introduced into bchI, bchD, and bchH mutants of Rba. capsulatus for functional complementation, all mutants were complemented with concomitant synthesis of bacteriochlorophyll a. Analyses of bacteriochlorophyll intermediates showed that A. rubrum cells accumulate magnesium protoporphyrin IX monomethyl ester without detectable accumulation of zinc protoporphyrin IX or its monomethyl ester. These results indicate that a single set of magnesium chelatase homologs in A. rubrum catalyzes the insertion of only Mg(2+) into protoporphyrin IX to yield magnesium protoporphyrin IX monomethyl ester. Consequently, it is most likely that zinc-containing bacteriochlorophyll a is formed by a substitution of Zn(2+) for Mg(2+) at a step in the bacteriochlorophyll biosynthesis after formation of magnesium protoporphyrin IX monomethyl ester.

  20. Systems biology defines the biological significance of redox-active proteins during cellulose degradation in an aerobic bacterium.

    PubMed

    Gardner, Jeffrey G; Crouch, Lucy; Labourel, Aurore; Forsberg, Zarah; Bukhman, Yury V; Vaaje-Kolstad, Gustav; Gilbert, Harry J; Keating, David H

    2014-10-08

    Microbial depolymerization of plant cell walls contributes to global carbon balance and is a critical component of renewable energy. The genomes of lignocellulose degrading microorganisms encode diverse classes of carbohydrate modifying enzymes, although currently there is a paucity of knowledge on the role of these proteins in vivo. We report the comprehensive analysis of the cellulose degradation system in the saprophytic bacterium Cellvibrio japonicus. Gene expression profiling of C. japonicus demonstrated that three of the 12 predicted β-1,4 endoglucanases (cel5A, cel5B, and cel45A) and the sole predicted cellobiohydrolase (cel6A) showed elevated expression during growth on cellulose. Targeted gene disruptions of all 13 predicted cellulase genes showed that only cel5B and cel6A were required for optimal growth on cellulose. Our analysis also identified three additional genes required for cellulose degradation: lpmo10B encodes a lytic polysaccharide monooxygenase (LPMO), while cbp2D and cbp2E encode proteins containing carbohydrate binding modules and predicted cytochrome domains for electron transfer. CjLPMO10B oxidized cellulose and Cbp2D demonstrated spectral properties consistent with redox function. Collectively, this report provides insight into the biological role of LPMOs and redox proteins in cellulose utilization and suggests that C. japonicus utilizes a combination of hydrolytic and oxidative cleavage mechanisms to degrade cellulose.

  1. Variovorax guangxiensis sp. nov., an aerobic, 1-aminocyclopropane-1-carboxylate deaminase producing bacterium isolated from banana rhizosphere.

    PubMed

    Gao, Jun-lian; Yuan, Mei; Wang, Xu-ming; Qiu, Tian-lei; Li, Ji-wei; Liu, Hong-can; Li, Xiu-ai; Chen, Jian; Sun, Jian-guang

    2015-01-01

    A 1-aminocyclopropane-1-carboxylate deaminase producing bacterium, designated GXGD002(T), was isolated from the rhizosphere of banana plants cultivated in Guangxi province, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain GXGD002(T) is a member of the genus Variovorax. High levels of 16S rRNA gene sequence similarity are found between strain GXGD002(T) and Variovorax paradoxus DSM 30034(T) (99.4 %), Variovorax ginsengisoli KCTC 12583(T) (99.1 %), Variovorax boronicumulans KCTC 22010(T) (99.0 %), Variovorax soli DSM18216(T) (98.7 %), Variovorax defluvii DSM 27259(T) (98.1 %) and Variovorax dokdonensis KCTC 12544(T) (97.4 %) respectively. However, the DNA-DNA hybridization values between strain GXGD002(T) and its closely related species V. paradoxus DSM 30034(T), V. ginsengisoli KCTC 12583(T) and V. boronicumulans KCTC 22010(T) were found to be 40.7, 30.9 and 23.7 %, respectively. The DNA G + C content of strain GXGD002(T) was found to be 67.8 mol%. The major fatty acids of strain GXGD002(T) are C16:0 (20.3 %), C10:0 3OH (18.4 %), C17:0 cyclo (18.9 %), C18:1w7c (12.3 %) and summed feature 3 (13.9 %). The predominant respiratory quinone was identified as ubiquinone-8 (Q-8) and the major polar lipids as phosphatidylethanolamine and phosphatidylglycerol. The results of polyphasic taxonomic study including physiological and biochemical tests, whole-cell SDS-PAGE profiles and chemotaxonomic analysis allowed a clear differentiation of strain GXGD002(T) from the other species in the genus Variovorax. Based on these results, a new species, Variovorax guangxiensis, is proposed. The type strain is GXGD002(T) (=DSM 27352(T) = ACCC 05911(T)).

  2. Heterotrophic nitrification among denitrifiers.

    PubMed Central

    Castignetti, D; Hollocher, T C

    1984-01-01

    Twelve denitrifying bacteria representing six genera were tested for an ability to nitrify pyruvic oxime heterotrophically. Six of these bacteria exhibited appreciable nitrification activity, yielding as much as 5.8 mM nitrite and little or no nitrate when grown in a mineral salts medium containing 7 mM pyruvic oxime and 0.05% yeast extract. Of the six active bacteria, four (Pseudomonas denitrificans, Pseudomonas aeruginosa, and two strains of Pseudomonas fluorescens) could grow on yeast extract but not pyruvic oxime, one (Pseudomonas aureofaciens) could grow slowly on pyruvic oxime, and one (Alcaligenes faecalis) could apparently grow on pyruvic oxime in the presence of yeast extract but not in its absence. Eight of the twelve bacteria in the resting state could oxidize hydroxylamine to nitrite, and P. aureofaciens was remarkably active in this regard. In general, those denitrifiers active in the nitrification of pyruvic oxime or hydroxylamine or both are abundant in soils. A possible advantage of having nitrification and denitrification capabilities in the same organism is discussed. PMID:6721486

  3. Competition between Two Isolates of Denitrifying Bacteria Added to Soil

    PubMed Central

    Murray, Robert E.; Parsons, Laura L.; Smith, M. Scott

    1992-01-01

    We examined the competitive relationship between two isolates of denitrifying bacteria, both of which grow well under aerobic conditions but differ in their ability to grow under denitrifying conditions. The growth and persistence of the two isolates, added to sterile soil or added to soil previously colonized by the other isolate, were monitored under aerobic and denitrifying (anaerobic) conditions. When isolates were added together to sterile soil, the isolate added at the higher density reduced the growth of the isolate added at the lower density. The magnitude of the growth reduction varied depending on the competitive abilities of the individual isolates and the aeration state of the soil. Prior colonization of soil with one of the isolates conferred a competitive advantage on the colonized isolate but did not lead to the disappearance of the challenging isolate. Fluctuations in aeration state caused large changes in the population density of one isolate and altered the competitive relationship between the two isolates. The competitive effectiveness of each isolate varied with cell density, the degree of prior colonization of the soil by the other isolate, and the aeration state of the soil. PMID:16348820

  4. Aerobic biodegradation of Azo dye by Bacillus cohnii MTCC 3616; an obligately alkaliphilic bacterium and toxicity evaluation of metabolites by different bioassay systems.

    PubMed

    Prasad, A S Arun; Rao, K V Bhaskara

    2013-08-01

    An obligate alkaliphilic bacterium Bacillus cohnii MTCC 3616 aerobically decolorized a textile azo dye Direct Red-22 (5,000 mg l⁻¹) with 95 % efficiency at 37 °C and pH 9 in 4 h under static conditions. The decolorization of Direct Red-22 (DR-22) was possible through a broad pH (7-11), temperature (10-45 °C), salinity (1-7 %), and dye concentration (5-10 g l⁻¹) range. Decolorization of dye was assessed by UV-vis spectrophotometer with reduction of peak intensity at 549 nm (λ(max)). Biodegradation of dye was analyzed by Fourier transform infrared spectroscopy (FTIR) and high-performance liquid chromatography (HPLC). The FTIR spectrum revealed that B. cohnii specifically targeted azo bond (N=N) at 1,614.42 cm⁻¹ to break down Direct Red-22. Formation of metabolites with different retention times in HPLC analysis further confirmed the degradation of dye. The phytotoxicity test with 5,000 mg l⁻¹ of untreated dye showed 80 % germination inhibition in Vigna mungo, 70 % in Sorghum bicolor and 80 % in Vigna radiata. No germination inhibition was noticed in all three plants by DR-22 metabolites at 5,000 mg l⁻¹. Biotoxicity test with Artemia salina proved the lethality of the azo dye at LC₅₀ of 4 and 8 % for degraded metabolites by causing death of its nauplii compared to its less toxic-degraded metabolites. Bioaccumulation of dye was observed in the mid-gut of A. salina. The cytogenotoxicity assay on the meristematic root tip cells of Allium cepa further confirmed the cytotoxic nature of azo dye (DR-22) with decrease in mitotic index (0.5 % at 500 ppm) and increase in aberrant index (4.56 %) over 4-h exposure period. Genotoxic damages (lagging chromosome, metaphase cluster, chromosome bridges, and dye accumulation in cytoplasm) were noticed at different stages of cell cycle. The degraded metabolites had negligible cytotoxic and genotoxic effects.

  5. Anaerobic arsenite oxidation by an autotrophic arsenite-oxidizing bacterium from an arsenic-contaminated paddy soil.

    PubMed

    Zhang, Jun; Zhou, Wuxian; Liu, Bingbing; He, Jian; Shen, Qirong; Zhao, Fang-Jie

    2015-05-19

    Microbe-mediated arsenic (As) redox reactions play an important role in the biogeochemical cycling of As. Reduction of arsenate [As(V)] generally leads to As mobilization in paddy soils and increased As availability to rice plants, whereas oxidation of arsenite [As(III)] results in As immobilization. A novel chemoautotrophic As(III)-oxidizing bacterium, designated strain SY, was isolated from an As-contaminated paddy soil. The isolate was able to derive energy from the oxidation of As(III) to As(V) under both aerobic and anaerobic conditions using O2 or NO3(-) as the respective electron acceptor. Inoculation of the washed SY cells into a flooded soil greatly enhanced As(III) oxidation to As(V) both in the solution and adsorbed phases of the soil. Strain SY is phylogenetically closely related to Paracoccus niistensis with a 16S rRNA gene similarity of 96.79%. The isolate contains both the denitrification and ribulose 1,5-bisphosphate carboxylase/oxygenase gene clusters, underscoring its ability to denitrify and to fix CO2 while coupled to As(III) oxidation. Deletion of the aioA gene encoding the As(III) oxidase subunit A abolished the As(III) oxidation ability of strain SY and led to increased sensitivity to As(III), suggesting that As(III) oxidation is a detoxification mechanism in this bacterium under aerobic and heterotrophic growth conditions. Analysis of the aioA gene clone library revealed that the majority of the As(III)-oxidizing bacteria in the soil were closely related to the genera Paracoccus of α-Proteobacteria. Our results provide direct evidence for As(III) oxidation by Paracoccus species and suggest that these species may play an important role in As(III) oxidation in paddy soils under both aerobic and denitrifying conditions.

  6. Mineralization and kinetics of Reactive Brilliant Red X-3B by a combined anaerobic-aerobic bioprocess inoculated with the coculture of fungus and bacterium.

    PubMed

    Shi, Shengnan; Ma, Fang; Sun, Tieheng; Li, Ang; Zhou, Jiti; Qu, Yuanyuan

    2014-01-01

    Mineralization of Reactive Brilliant Red X-3B by a combined anaerobic-aerobic process which was inoculated with the co-culture of Penicillium sp. QQ and Exiguobacterium sp. TL was studied. The optimal conditions of decolorization were investigated by response surface methodology as follows: 132.67 g/L of strain QQ wet spores, 1.09 g/L of strain TL wet cells, 2.25 g/L of glucose, 2.10 g/L of yeast extract, the initial dye concentration of 235.14 mg/L, pH 6.5, and 33 °C. The maximal decolorization rate was about 96 % within 12 h under the above conditions. According to the Haldane kinetic equation, the maximal specific decolorization rate was 89.629 mg/g˙h. It was suggested that in the anaerobic-aerobic combined process, decolorization occurred in the anaerobic unit and chemical oxygen demand (COD) was mainly removed in the aerobic one. Inoculation of fungus QQ in the anaerobic unit was important for mineralization of X-3B. Besides, the divided anaerobic-aerobic process showed better performance of COD removal than the integrated one. It was suggested that the combined anaerobic-aerobic process which was inoculated with co-culture was potentially useful for the field application.

  7. [Denitrifying and phosphorus accumulating mechanisms of denitrifying phosphorus accumulating organisms (DPAOs) for wastewater treatment--a review].

    PubMed

    Yu, Hongting; Li, Min

    2015-03-04

    Eutrophication has raised increasing concerns due to its adverse effects on creatures. It is widely accepted that microbes are capable of removing nitrogen (N) and phosphate (P) via denitrification and P accumulation. So far, several strains can do this work. Therefore, more studies are focused on looking for micro-organisms that have both denitrification and P accumulation ability. Whether exposed to aerobic or anaerobic environment, microbial N and P removal mechanisms differ. Proton Motive Force and Electron Acceptor Theory are involved in the chemical process, whereas denitrifying enzymes polyphosphate kinases are regarded as the leading participators in the enzymatic systems. Studies have shown the influences of N on P accumulation, but further investigation should identify the influences of P on N removal. Here we reviewed the aspects of N and P removal mechanisms in denitrifying phosphorus accumulating organisms (DPAOs) and their potential to remove N and P from water system. Moreover, future works on clarifying denitrifying phosphorus accumulating mechanisms in depth and improving efficiency of removing N and P by DPAOs are provided.

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

    PubMed

    Reza, Maryam; Alvarez Cuenca, Manuel

    2016-01-01

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

  9. Genome Sequence of the Deep-Sea Denitrifier Pseudomonas sp. Strain MT-1, Isolated from the Mariana Trench.

    PubMed

    Fujinami, Shun; Oikawa, Yuji; Araki, Takuma; Shinmura, Yui; Midorikawa, Ryota; Ishizaka, Hikari; Kato, Chiaki; Horikoshi, Koki; Ito, Masahiro; Tamegai, Hideyuki

    2014-12-18

    Pseudomonas sp. strain MT-1 was the first deep-sea denitrifier isolated and characterized from mud recovered from a depth of 11,000 m in the Mariana Trench. We report here the genome sequence of this bacterium, which contributes to our understanding of denitrification and bioenergetics in the deep sea.

  10. The effects of Lactobacillus buchneri with or without a homolactic bacterium on the fermentation and aerobic stability of corn silages made at different locations.

    PubMed

    Schmidt, R J; Kung, L

    2010-04-01

    Whole-plant corn (31 to 39% dry matter) from several locations was chopped, treated with nothing (U), Lactobacillus buchneri 40788 (4 x 10(5) cfu/g; LB), or L. buchneri (4 x 10(5) cfu/g) and Pediococcus pentosaceus (1 x 10(5) cfu/g; LBPP), and packed into quadruplicate 20-L silos to determine their effects on silage fermentation and aerobic stability after 120 d of storage. The experiment was a randomized complete block design with main effects of treatment (T), block (location; L), and T x L interaction. Dry matter recovery was different among locations but unaffected by T. The population of lactic acid bacteria was greater in LB and LBPP than in U, and the opposite was true regarding the population of yeasts. Numbers of L. buchneri (colony-forming unit equivalents), determined by a real-time quantitative polymerase chain reaction, were higher in 4 of 5 locations for LB and LBPP compared with U (T x L interaction) with an average 6.70 log cfu/g for LB and LBPP versus 4.87 log cfu/g for U. Silages inoculated with LB and LBPP had higher silage pH and higher concentrations of acetic acid and 1,2 propanediol but lower concentrations of ethanol and water-soluble carbohydrates; there was a T x L interaction for all these variables. Aerobic stability was improved by LB and LBPP (mean of 136 h) compared with U (44 h), but there was an interaction between T x L. In general, locations with the highest population of L. buchneri had the largest increases in acetic acid and, consequently, the greatest improvements in aerobic stability. The addition of L. buchneri 40788 alone or with P. pentosaceus resulted in similar effects on silage fermentation and aerobic stability, but the effects were variable among locations, suggesting that unidentified factors; for example, in the field or on the forage crop, may alter the effectiveness of microbial inoculation.

  11. Kinetics of Denitrifying Growth by Fast-Growing Cowpea Rhizobia

    PubMed Central

    El Hassan, G. A.; Zablotowicz, R. M.; Focht, D. D.

    1985-01-01

    Two fast-growing strains of cowpea rhizobia (A26 and A28) were found to grow anaerobically at the expense of NO3−, NO2−, and N2O as terminal electron acceptors. The two major differences between aerobic and denitrifying growth were lower yield coefficients (Y) and higher saturation constants (Ks) with nitrogenous oxides as electron acceptors. When grown aerobically, A26 and A28 adhered to Monod kinetics, respectively, as follows: Ks, 3.4 and 3.8 μM; Y, 16.0 and 14.0 g · cells eq−1; μmax, 0.41 and 0.33 h−1. Yield coefficients for denitrifying growth ranged from 40 to 70% of those for aerobic growth. Only A26 adhered to Monod kinetics with respect to growth on all three nitrogenous oxides. The apparent Ks values were 41, 270, and 460 μM for nitrous oxide, nitrate, and nitrite, respectively; the Ks for A28 grown on nitrate was 250 μM. The results are kinetically and thermodynamically consistent in explaining why O2 is the preferred electron acceptor. Although no definitive conclusions could be drawn regarding preferential utilization of nitrogenous oxides, nitrite was inhibitory to both strains and effected slower growth. However, growth rates were identical (μmax, 0.41 h−1) when A26 was grown with either O2 or NO3− as an electron acceptor and were only slightly reduced when A28 was grown with NO3− (0.25 h−1) as opposed to O2 (0.33 h−1). PMID:16346745

  12. The metabolic impact of extracellular nitrite on aerobic metabolism of Paracoccus denitrificans.

    PubMed

    Hartop, K R; Sullivan, M J; Giannopoulos, G; Gates, A J; Bond, P L; Yuan, Z; Clarke, T A; Rowley, G; Richardson, D J

    2017-02-07

    Nitrite, in equilibrium with free nitrous acid (FNA), can inhibit both aerobic and anaerobic growth of microbial communities through bactericidal activities that have considerable potential for control of microbial growth in a range of water systems. There has been much focus on the effect of nitrite/FNA on anaerobic metabolism and so, to enhance understanding of the metabolic impact of nitrite/FNA on aerobic metabolism, a study was undertaken with a model denitrifying bacterium Paracoccus denitrificans PD1222. Extracellular nitrite inhibits aerobic growth of P. denitrificans in a pH-dependent manner that is likely to be a result of both nitrite and free nitrous acid (pKa = 3.25) and subsequent reactive nitrogen oxides generated from the intracellular passage of FNA into P. denitrificans. Increased expression of a gene encoding a flavohemoglobin protein (Fhp) (Pden_1689) was observed in response to extracellular nitrite. Construction and analysis of a deletion mutant established Fhp to be involved in endowing nitrite/FNA resistance at high extracellular nitrite concentrations. Global transcriptional analysis confirmed nitrite-dependent expression of fhp and indicated that P. denitrificans expressed a number of stress response systems associated with protein, DNA and lipid repair. It is therefore suggested that nitrite causes a pH-dependent stress response that is due to the production of associated reactive nitrogen species, such as nitric oxide from the internalisation of FNA.

  13. Isolation and characterization of a nitrite reductase gene and its use as a probe for denitrifying bacteria.

    PubMed Central

    Smith, G B; Tiedje, J M

    1992-01-01

    The dissimilatory nitrite reductase gene (nir) from denitrifying bacterium Pseudomonas stutzeri JM300 was isolated and sequenced. In agreement with recent sequence information from another strain of P. stutzeri (strain ZoBell), strain JM300 nir is the first gene in an operon and is followed immediately by a gene which codes for a tetraheme protein; 2.5 kb downstream from the nitrite reductase carboxyl terminus is the cytochrome c551 gene. P. stutzeri JM300 nir is 67% homologous to P. aeruginosa nir and 88% homologous to P. stutzeri ZoBell nir. Within the nitrite reductase promoter region is an fnr-like operator very similar to an operator upstream of a separate anaerobic pathway, that for arginine catabolism in P. aeruginosa. The denitrification genes in P. stutzeri thus may be under the same regulatory control as that found for other anaerobic pathways of pseudomonads. We have generated gene probes from restriction fragments within the nitrite reductase operon to evaluate their usefulness in ecology studies of denitrification. Probes generated from the carboxyl terminus region hybridized to denitrifying bacteria from five separate genera and did not cross-hybridize to any nondenitrifying bacteria among six genera tested. The denitrifier probes were successful in detecting denitrifying bacteria from samples such as a bioreactor consortium, aquifer microcosms, and denitrifying toluene-degrading enrichments. The probes also were used to reveal restriction fragment length polymorphism patterns indicating the diversity of denitrifiers present in these mixed communities. Images PMID:1539983

  14. A marine inducible prophage vB_CibM-P1 isolated from the aerobic anoxygenic phototrophic bacterium Citromicrobium bathyomarinum JL354

    NASA Astrophysics Data System (ADS)

    Zheng, Qiang; Zhang, Rui; Xu, Yongle; , Richard Allen White, III; Wang, Yu; Luo, Tingwei; Jiao, Nianzhi

    2014-11-01

    A prophage vB_CibM-P1 was induced by mitomycin C from the epipelagic strain Citromicrobium bathyomarinum JL354, a member of the alpha-IV subcluster of marine aerobic anoxygenic phototrophic bacteria (AAPB). The induced bacteriophage vB_CibM-P1 had Myoviridae-like morphology and polyhedral heads (approximately capsid 60-100 nm) with tail fibers. The vB_CibM-P1 genome is ~38 kb in size, with 66.0% GC content. The genome contains 58 proposed open reading frames that are involved in integration, DNA packaging, morphogenesis and bacterial lysis. VB_CibM-P1 is a temperate phage that can be directly induced in hosts. In response to mitomycin C induction, virus-like particles can increase to 7 × 109 per ml, while host cells decrease an order of magnitude. The vB_CibM-P1 bacteriophage is the first inducible prophage from AAPB.

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

    SciTech Connect

    Song, Hyun-Seob; Liu, Chongxuan

    2015-06-29

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

  16. Performance of Denitrifying Microbial Fuel Cell with Biocathode over Nitrite

    PubMed Central

    Zhao, Huimin; Zhao, Jianqiang; Li, Fenghai; Li, Xiaoling

    2016-01-01

    Microbial fuel cell (MFC) with nitrite as an electron acceptor in cathode provided a new technology for nitrogen removal and electricity production simultaneously. The influences of influent nitrite concentration and external resistance on the performance of denitrifying MFC were investigated. The optimal effectiveness were obtained with the maximum total nitrogen (TN) removal rate of 54.80 ± 0.01 g m−3 d−1. It would be rather desirable for the TN removal than electricity generation at lower external resistance. Denaturing gradient gel electrophoresis suggested that Proteobacteria was the predominant phylum, accounting for 35.72%. Thiobacillus and Afipia might benefit to nitrite removal. The presence of nitrifying Devosia indicated that nitrite was oxidized to nitrate via a biochemical mechanism in the cathode. Ignavibacterium and Anaerolineaceae was found in the cathode as a heterotrophic bacterium with sodium acetate as substrate, which illustrated that sodium acetate in anode was likely permeated through proton exchange membrane to the cathode. PMID:27047462

  17. OPTIMIZING BTEX BIODEGRADATION UNDER DENITRIFYING CONDITIONS

    EPA Science Inventory

    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, Mic...

  18. Thermalkalibacillus uzonensis gen. nov. sp. nov, a novel aerobic alkali-tolerant thermophilic bacterium isolated from a hot spring in Uzon Caldera, Kamchatka.

    PubMed

    Zhao, Weidong; Weber, Carolyn; Zhang, Chuanlun L; Romanek, Christopher S; King, Gary M; Mills, Gary; Sokolova, Tatyana; Wiegel, Juergen

    2006-08-01

    A novel thermophilic, alkali-tolerant, and CO-tolerant strain JW/WZ-YB58(T) was isolated from green mat samples obtained from the Zarvarzin II hot spring in the Uzon Caldera, Kamchatka (Far East Russia). Cells were Gram-type and Gram stain-positive, strictly aerobic, 0.7-0.8 mum in width and 5.5-12 mum in length and produced terminal spherical spores of 1.2-1.6 mum in diameter with the mother cell swelling around 2 mum in diameter (drumstick-type morphology). Cells grew optimally at pH(25 degrees C) 8.2-8.4 and temperature 50-52 degrees C and tolerated maximally 6% (w/v) NaCl. They were strict heterotrophs and could not use either CO or CO(2 )(both with or without H(2)) as sole carbon source, but tolerated up to 90% (v/v) CO in the headspace. The isolate grew on various complex substrates such as yeast extract, on carbohydrates, and organic acids, which included starch, D: -galactose, D: -mannose, glutamate, fumarate and acetate. Catalase reaction was negative. The membrane polar lipids were dominated by branched saturated fatty acids, which included iso-15:0 (24.5%), anteiso-15:0 (18.3%), iso-16:0 (9.9%), iso-17:0 (17.5%) and anteiso-17:0 (9.7%) as major constituents. The DNA G+C content of the strain is 45 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain JW/WZ-YB58(T) is distantly (<93% similarity) related to members of Bacillaceae. On the basis of 16S rRNA gene sequence, physiological and phenotypic characteristics, the isolate JW/WZ-YB58(T) (ATCC BAA-1258; DSM 17740) is proposed to be the type strain for the type species of the new taxa within the family Bacillaceae, Thermalkalibacillus uzoniensis gen. nov. sp. nov. The Genbank accession number for the 16S rRNA gene sequence is DQ221694.

  19. Fertilization stimulates anaerobic fuel degradation of antarctic soils by denitrifying microorganisms.

    PubMed

    Powell, Shane M; Ferguson, Susan H; Snape, Ian; Siciliano, Steven D

    2006-03-15

    Human activities in the Antarctic have resulted in hydrocarbon contamination of these fragile polar soils. Bioremediation is one of the options for remediation of these sites. However, little is known about anaerobic hydrocarbon degradation in polar soils and the influence of bioremediation practices on these processes. Using a field trial at Old Casey Station, Antarctica, we assessed the influence of fertilization on the anaerobic degradation of a 20-year old fuel spill. Fertilization increased hydrocarbon degradation in both anaerobic and aerobic soils when compared to controls, but was of most benefit for anaerobic soils where evaporation was negligible. This increased biodegradation in the anaerobic soils corresponded with a shift in the denitrifier community composition and an increased abundance of denitrifiers and benzoyl-CoA reductase. A microcosm study using toluene and hexadecane confirmed the degradative capacity within these soils under anaerobic conditions. It was observed that fertilized anaerobic soil degraded more of this hydrocarbon spike when incubated anaerobically than when incubated aerobically. We conclude that denitrifiers are actively involved in hydrocarbon degradation in Antarctic soils and that fertilization is an effective means of stimulating their activity. Further, when communities stimulated to degrade hydrocarbons under anaerobic conditions are exposed to oxygen, hydrocarbon degradation is suppressed. The commonly accepted belief that remediation of polar soils requires aeration needs to be reevaluated in light of this new data.

  20. Effects of heavy metals on aerobic denitrification by strain Pseudomonas stutzeri PCN-1.

    PubMed

    Gui, Mengyao; Chen, Qian; Ma, Tao; Zheng, Maosheng; Ni, Jinren

    2017-02-01

    Effects of heavy metals on aerobic denitrification have been poorly understood compared with their impacts on anaerobic denitrification. This paper presented effects of four heavy metals (Cd(II), Cu(II), Ni(II), and Zn(II)) on aerobic denitrification by a novel aerobic denitrifying strain Pseudomonas stutzeri PCN-1. Results indicated that aerobic denitrifying activity decreased with increasing heavy metal concentrations due to their corresponding inhibition on the denitrifying gene expression characterized by a time lapse between the expression of the nosZ gene and that of the cnorB gene by PCN-1, which led to lower nitrate removal rate (1.67∼6.67 mg L(-1) h(-1)), higher nitrite accumulation (47.3∼99.8 mg L(-1)), and higher N2O emission ratios (5∼283 mg L(-1)/mg L(-1)). Specially, promotion of the nosZ gene expression by increasing Cu(II) concentrations (0∼0.05 mg L(-1)) was found, and the absence of Cu resulted in massive N2O emission due to poor synthesis of N2O reductase. The inhibition effect for both aerobic denitrifying activity and denitrifying gene expression was as follows from strongest to least: Cd(II) (0.5∼2.5 mg L(-1)) > Cu(II) (0.5∼5 mg L(-1)) > Ni(II) (2∼10 mg L(-1)) > Zn(II) (25∼50 mg L(-1)). Furthermore, sensitivity of denitrifying gene to heavy metals was similar in order of nosZ > nirS ≈ cnorB > napA. This study is of significance in understanding the potential application of aerobic denitrifying bacteria in practical wastewater treatment.

  1. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    NASA Technical Reports Server (NTRS)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  2. Oligoflexus tunisiensis gen. nov., sp. nov., a Gram-negative, aerobic, filamentous bacterium of a novel proteobacterial lineage, and description of Oligoflexaceae fam. nov., Oligoflexales ord. nov. and Oligoflexia classis nov.

    PubMed Central

    Nakai, Ryosuke; Nishijima, Miyuki; Tazato, Nozomi; Handa, Yutaka; Karray, Fatma; Sayadi, Sami; Isoda, Hiroko

    2014-01-01

    A phylogenetically novel proteobacterium, strain Shr3T, was isolated from sand gravels collected from the eastern margin of the Sahara Desert. The isolation strategy targeted bacteria filterable through 0.2-µm-pore-size filters. Strain Shr3T was determined to be a Gram-negative, aerobic, non-motile, filamentous bacterium. Oxidase and catalase reactions were positive. Strain Shr3T showed growth on R2A medium, but poor or no growth on nutrient agar, trypticase soy agar and standard method agar. The major isoprenoid quinone was menaquinone-7. The dominant cellular fatty acids detected were C16 : 1ω5c and C16 : 0, and the primary hydroxy acid present was C12 : 0 3-OH. The DNA G+C content was 54.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Shr3T was affiliated with an uncultivated lineage of the phylum Proteobacteria; the nearest known type strain, with 83 % sequence similarity, was Desulfomicrobium orale DSM 12838T in the class Deltaproteobacteria. The isolate and closely related environmental clones formed a novel class-level clade in the phylum Proteobacteria with high bootstrap support (96–99 %). Based on these results, the novel class Oligoflexia classis nov. in the phylum Proteobacteria and the novel genus and species Oligoflexus tunisiensis gen. nov., sp. nov. are proposed for strain Shr3T, the first cultivated representative of the Oligoflexia. The type strain of Oligoflexus tunisiensis is Shr3T ( = JCM 16864T = NCIMB 14846T). We also propose the subordinate taxa Oligoflexales ord. nov. and Oligoflexaceae fam. nov. in the class Oligoflexia. PMID:25013226

  3. Denitrifying kinetics and nitrous oxide emission under different copper concentrations.

    PubMed

    Wu, Guangxue; Zhai, Xiaofeng; Jiang, Chengai; Guan, Yuntao

    2014-01-01

    Denitrifying activities and nitrous oxide (N2O) emission during denitrification can be affected by copper concentrations. Different denitrifiers were acclimated in sequencing batch reactors with acetate or methanol as the electron donor and nitrate as the electron acceptor. The effect of copper concentrations on the denitrifying activity and N2O emission for the acclimated denitrifiers was examined in batch experiments. Denitrifying activities of the acclimated denitrifiers declined with increasing copper concentrations, and the copper concentration exhibited a higher effect on denitrifiers acclimated with acetate than those acclimated with methanol. Compared with the control without the addition of copper, at the copper concentration of 1 mg/L, the acetate utilization rate reduced by 89% for acetate-acclimated denitrifiers, while the methanol utilization rate only reduced by 15% for methanol-acclimated denitrifiers. Copper also had different effects on N2O emission during denitrification carried out by various types of denitrifiers. For the acetate-acclimated denitrifiers, N2O emission initially increased and then decreased with increasing copper concentrations, while for the methanol-acclimated denitrifiers, N2O emission decreased with increasing copper concentrations.

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

    PubMed

    Wong, Biing-Teo; Lee, Duu-Jong

    2014-01-01

    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.

  5. Natural attenuation of perchlorate in denitrified groundwater.

    PubMed

    Robertson, William D; Roy, James W; Brown, Susan J; Van Stempvoort, Dale R; Bickerton, Greg

    2014-01-01

    Monitoring of a well-defined septic system groundwater plume and groundwater discharging to two urban streams located in southern Ontario, Canada, provided evidence of natural attenuation of background low level (ng/L) perchlorate (ClO4⁻) under denitrifying conditions in the field. The septic system site at Long Point contains ClO4⁻ from a mix of waste water, atmospheric deposition, and periodic use of fireworks, while the nitrate plume indicates active denitrification. Plume nitrate (NO3⁻ -N) concentrations of up to 103 mg/L declined with depth and downgradient of the tile bed due to denitrification and anammox activity, and the plume was almost completely denitrified beyond 35 m from the tile bed. The ClO4⁻ natural attenuation occurs at the site only when NO3⁻ -N concentrations are <0.3 mg/L, after which ClO4⁻ concentrations decline abruptly from 187 ± 202 to 11 ± 15 ng/L. A similar pattern between NO3⁻ -N and ClO4⁻ was found in groundwater discharging to the two urban streams. These findings suggest that natural attenuation (i.e., biodegradation) of ClO4⁻ may be commonplace in denitrified aquifers with appropriate electron donors present, and thus, should be considered as a remediation option for ClO4⁻ contaminated groundwater.

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

    PubMed

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

    2015-03-01

    Aerobic denitrification is the main process for high N2O production in acid tea field soil. However, the biological mechanisms for the high emission are not fully understood. In this study, we examined N2O emission and denitrifier communities in 100-year-old tea soils with four pH levels (3.71, 5.11, 6.19, and 7.41) and four nitrate concentration (0, 50, 200, and 1000 mg kg(-1) of NO3 (-)-N) addition. Results showed the highest N2O emission (10.1 mg kg(-1) over 21 days) from the soil at pH 3.71 with 1000 mg kg(-1) NO3 (-) addition. The N2O reduction and denitrification enzyme activity in the acid soils (pH <7.0) were significantly higher than that of soils at pH 7.41. Moreover, TRF 78 of nirS and TRF 187 of nosZ dominated in soils of pH 3.71, suggesting an important role of acidophilic denitrifiers in N2O production and reduction. CCA analysis also showed a negative correlation between the dominant denitrifier ecotypes (nirS TRF 78, nosZ TRF 187) and soil pH. The representative sequences were identical to those of cultivated denitrifiers from acidic soils via phylogenetic tree analysis. Our results showed that the acidophilic denitrifier adaptation to the acid environment results in high N2O emission in this highly acidic tea soil.

  7. Site-specific variability in BTEX biodegradation under denitrifying conditions

    SciTech Connect

    Kao, C.M.; Borden, R.C.

    1997-03-01

    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.

  8. Comparative Analysis of Denitrifying Activities of Hyphomicrobium nitrativorans, Hyphomicrobium denitrificans, and Hyphomicrobium zavarzinii

    PubMed Central

    Martineau, Christine; Mauffrey, Florian

    2015-01-01

    Hyphomicrobium spp. are commonly identified as major players in denitrification systems supplied with methanol as a carbon source. However, denitrifying Hyphomicrobium species are poorly characterized, and very few studies have provided information on the genetic and physiological aspects of denitrification in pure cultures of these bacteria. This is a comparative study of three denitrifying Hyphomicrobium species, H. denitrificans ATCC 51888, H. zavarzinii ZV622, and a newly described species, H. nitrativorans NL23, which was isolated from a denitrification system treating seawater. Whole-genome sequence analyses revealed that although they share numerous orthologous genes, these three species differ greatly in their nitrate reductases, with gene clusters encoding a periplasmic nitrate reductase (Nap) in H. nitrativorans, a membrane-bound nitrate reductase (Nar) in H. denitrificans, and one Nap and two Nar enzymes in H. zavarzinii. Concurrently with these differences observed at the genetic level, important differences in the denitrification capacities of these Hyphomicrobium species were determined. H. nitrativorans grew and denitrified at higher nitrate and NaCl concentrations than did the two other species, without significant nitrite accumulation. Significant increases in the relative gene expression levels of the nitrate (napA) and nitrite (nirK) reductase genes were also noted for H. nitrativorans at higher nitrate and NaCl concentrations. Oxygen was also found to be a strong regulator of denitrification gene expression in both H. nitrativorans and H. zavarzinii, although individual genes responded differently in these two species. Taken together, the results presented in this study highlight the potential of H. nitrativorans as an efficient and adaptable bacterium that is able to perform complete denitrification under various conditions. PMID:25979892

  9. Molecular characterization of denitrifying bacteria isolated from the anoxic reactor of a modified DEPHANOX plant performing enhanced biological phosphorus removal.

    PubMed

    Zafiriadis, Ilias; Ntougias, Spyridon; Mirelis, Paraskevi; Kapagiannidis, Anastasios G; Aivasidis, Alexander

    2012-06-01

    Enhanced Biological Phosphorus Removal (EBPR) under anoxic conditions was achieved using a Biological Nutrient Removal (BNR) system based on a modification of the DEPHANOX configuration. Double-probe Fluorescence in Situ Hybridization (FISH) revealed that Polyphosphate Accumulating Organisms (PAOs) comprised 12.3 +/- 3.2% of the total bacterial population in the modified DEPHANOX plant. The growing bacterial population on blood agar and Casitone Glycerol Yeast Autolysate agar (CGYA) medium was 16.7 +/- 0.9 x 10(5) and 3.0 +/- 0.6 x 10(5) colony forming units (cfu) mL(-1) activated sludge, respectively. A total of 121 bacterial isolates were characterized according to their denitrification ability, with 26 bacterial strains being capable of reducing nitrate to gas. All denitrifying isolates were placed within the alpha-, beta-, and gamma-subdivisions of Proteobacteria and the family Flavobacteriaceae. Furthermore, a novel denitrifying bacterium within the genus Pseudomonas was identified. This is the first report on the isolation and molecular characterization of denitrifying bacteria from EBPR sludge using a DEPHANOX-type plant.

  10. Predicting N2O emissions from nitrifying and denitrifying biofilms: a modeling study.

    PubMed

    Sabba, Fabrizio; Picioreanu, Cristian; Boltz, Joshua P; Nerenberg, Robert

    2017-02-01

    Wastewater treatment plants can be significant sources of nitrous oxide (N2O), a potent greenhouse gas. While our understanding of N2O emissions from suspended-growth processes has advanced significantly, less is known about emissions from biofilm processes. Biofilms may behave differently due to their substrate gradients and microbial stratification. In this study, we used mathematical modeling to explore the mechanisms of N2O emissions from nitrifying and denitrifying biofilms. Our ammonia-oxidizing bacteria biofilm model suggests that N2O emissions from biofilm can be significantly greater than from suspended-growth systems. The driving factor is the diffusion of hydroxylamine, a nitrification intermediate, from the aerobic to the anoxic regions of the biofilm. The presence of nitrite-oxidizing bacteria further increased emissions. For denitrifying biofilms, our results suggest that emissions are generally greater than for suspended-growth systems. However, the magnitude of the difference depends on the bulk dissolved oxygen, chemical oxygen demand, and nitrate concentrations, as well as the biofilm thickness. Overall, the accumulation and diffusion of key intermediates, i.e. hydroxylamine and nitrite, distinguish biofilms from suspended-growth systems. Our research suggests that the mechanisms of N2O emissions from biofilms are much more complex than suspended-growth systems, and that emissions may be higher in many cases.

  11. Denitratisoma oestradiolicum gen. nov., sp. nov., a 17beta-oestradiol-degrading, denitrifying betaproteobacterium.

    PubMed

    Fahrbach, Michael; Kuever, Jan; Meinke, Ruth; Kämpfer, Peter; Hollender, Juliane

    2006-07-01

    A Gram-negative, motile, denitrifying bacterium (strain AcBE2-1(T)) was isolated from activated sludge of a municipal wastewater treatment plant using 17beta-oestradiol (E2) as sole source of carbon and energy. Cells were curved rods, 0.4-0.8 x 0.8-2.0 microm in size, non-fermentative, non-spore-forming, oxidase-positive and catalase-negative. E2 was oxidized completely to carbon dioxide and water by reduction of nitrate to a mixture of dinitrogen monoxide and dinitrogen, with the intermediate accumulation of nitrite. Electron recoveries were between 90 and 100 %, taking assimilated E2 into account. With nitrate as the electron acceptor, the bacterium also grew on fatty acids (C(2) to C(6)), isobutyrate, crotonate, dl-lactate, pyruvate, fumarate and succinate. Phylogenetic analysis of its 16S rRNA gene sequence revealed that strain AcBE2-1(T) represents a separate line of descent within the family Rhodocyclaceae (Betaproteobacteria). The closest relatives are the cholesterol-degrading, denitrifying bacteria Sterolibacterium denitrificans DSM 13999(T) and strain 72Chol (=DSM 12783), with <93.9 % sequence similarity. The G+C content of the DNA was 61.4 mol%. Detection of a quinone system with ubiquinone Q-8 as the predominant compound and a fatty acid profile that included high concentrations of C(16 : 1)omega7c/iso-C(15 : 0) 2-OH and C(16 : 0), in addition to C(18 : 1)omega7c and small amounts of C(8 : 0) 3-OH, supported the results of the phylogenetic analysis. On the basis of 16S rRNA gene sequence data in combination with chemotaxonomic and physiological data, strain AcBE2-1(T) (=DSM 16959(T)=JCM 12830(T)) is placed in a new genus Denitratisoma gen. nov. as the type strain of the type species Denitratisoma oestradiolicum gen. nov., sp. nov.

  12. Role of chemotaxis in the ecology of denitrifiers

    NASA Technical Reports Server (NTRS)

    Kennedy, M. J.; Lawless, J. G.

    1985-01-01

    It has been recognized that the process of denitrification represents a major sequence in the nitrogen cycle. It involves the anaerobic reduction of nitrate or nitrite to nitrous oxide or elemental nitrogen. This process is responsible for significant losses of nitrogen from agricultural soils. Up to now, little attention has been paid to the ecology of the organisms responsible for denitrification. It is pointed out that chemotaxis would probably offer a strong competitive mechanism for denitrifiers, since chemotaxis would allow denitrifiers to actively reach nitrate by directed motility, rather than by random movement or diffusion of nitrate. The present investigation was initiated to examine the chemotactic responses of several denitrifiers to nitrate and nitrite. Attention is given to bacterial strains, culture media and cell preparation, chemotaxis assays, and competition experiments. It was found that several denitrifiers, including P. aeruginosa, P. fluorescens, and P. Stutzeri, were strongly attracted to NO3(-) and NO2(-).

  13. Aerobic Tennis.

    ERIC Educational Resources Information Center

    Stewart, Michael J.; Ahlschwede, Robert

    1989-01-01

    Increasing the aerobic nature of tennis drills in the physical education class may be necessary if tennis is to remain a part of the public school curriculum. This article gives two examples of drills that can be modified by teachers to increase activity level. (IAH)

  14. Characterization of a novel extremely alkalophilic bacterium

    NASA Technical Reports Server (NTRS)

    Souza, K. A.; Deal, P. H.

    1977-01-01

    A new alkalophilic bacterium, isolated from a natural spring of high pH is characterized. It is a Gram-positive, non-sporulating, motile rod requiring aerobic and alkaline conditions for growth. The characteristics of this organism resemble those of the coryneform group of bacteria; however, there are no accepted genera within this group with which this organism can be closely matched. Therefore, a new genus may be warranted.

  15. Taxonomic characterization of the cellulose-degrading bacterium NCIB 10462

    SciTech Connect

    Dees, C.; Ringleberg, D.; Scott, T.C.; Phelps, T.

    1994-06-01

    The gram negative cellulase-producing bacterium NCIB 10462 has been previously named Pseudomonas fluorescens subsp. or var. cellulosa. Since there is renewed interest in cellulose-degrading bacteria for use in bioconversion of cellulose to chemical feed stocks and fuels, we re-examined the characteristics of this microorganism to determine its proper taxonomic characterization and to further define it`s true metabolic potential. Metabolic and physical characterization of NCIB 10462 revealed that this was an alkalophilic, non-fermentative, gram negative, oxidase positive, motile, cellulose-degrading bacterium. The aerobic substrate utilization profile of this bacterium was found to have few characteristics consistent with a classification of P. fluorescens with a very low probability match with the genus Sphingomonas. Total lipid analysis did not reveal that any sphingolipid bases are produced by this bacterium. NCIB 10462 was found to grow best aerobically but also grows well in complex media under reducing conditions. NCIB 10462 grew slowly under full anaerobic conditions on complex media but growth on cellulosic media was found only under aerobic conditions. Total fatty acid analysis (MIDI) of NCIB 10462 failed to group this bacterium with a known pseudomonas species. However, fatty acid analysis of the bacteria when grown at temperatures below 37{degrees}C suggest that the organism is a pseudomonad. Since a predominant characteristic of this bacterium is it`s ability to degrade cellulose, we suggest it be called Pseudomonas cellulosa.

  16. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers. [Pseudomonas fluorescens; Serratia marcescens; Alcaligenes faecalis

    SciTech Connect

    Anderson, I.C.; Levine, J.S.

    1986-05-01

    The authors investigated the effect of the partial pressure of oxygen (pO/sub 2/) on the production of NO and N/sub 2/O by a wide variety of common soil nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The production of NO per cell was highest by autotrophic nitrifiers and was independent of pO/sub 2/ in the range tested (0.5 to 10%), whereas N/sub 2/O production was inversely proportional to pO/sub 2/. Nitrous oxide production was highest in the denitrifier Pseudomonas fluorescens, but only under anaerobic conditions. The molar ratio of NO/N/sub 2/O produced was usually greater than unity for nitrifiers and much less than unity for denitrifiers. Chemodenitrification was the major source of both the NO and N/sub 2/O produced by the nitrate respirer Serratia marcescens. Chemodenitrification was also a possible source of NO and N/sub 2/O produced by the nitrate respirer Serratia marcescens. Chemodenitrification was also a possible source of No and N/sub 2/O in nitrifier cultures but only when high concentrations of nitrite had accumulated or were added to the medium. Although most of the denitrifiers produced NO and N/sub 2/O only under anaerobic conditions, chemostat cultures of Alcaligenes faecalis continued to emit these gases even when the cultures were sprayed with air. Based upon these results, we predict that aerobic soils are primary sources of NO and that N/sub 2/O is produced only when there is sufficient soil moisture to provide the anaerobic microsites necessary for denitrification by either denitrifiers or nitrifiers.

  17. Calibration of denitrifying activity of polyphosphate accumulating organisms in an extended ASM2d model.

    PubMed

    García-Usach, F; Ribes, J; Ferrer, J; Seco, A

    2010-10-01

    This paper presents the results of an experimental study for the modelling and calibration of denitrifying activity of polyphosphate accumulating organisms (PAOs) in full-scale WWTPs that incorporate simultaneous nitrogen and phosphorus removal. The convenience of using different yields under aerobic and anoxic conditions for modelling biological phosphorus removal processes with the ASM2d has been demonstrated. Thus, parameter η(PAO) in the model is given a physical meaning and represents the fraction of PAOs that are able to follow the DPAO metabolism. Using stoichiometric relationships, which are based on assumed biochemical pathways, the anoxic yields considered in the extended ASM2d can be obtained as a function of their respective aerobic yields. Thus, this modification does not mean an extra calibration effort to obtain the new parameters. In this work, an off-line calibration methodology has been applied to validate the model, where general relationships among stoichiometric parameters are proposed to avoid increasing the number of parameters to calibrate. The results have been validated through a UCT scheme pilot plant that is fed with municipal wastewater. The good concordance obtained between experimental and simulated values validates the use of anoxic yields as well as the calibration methodology. Deterministic modelling approaches, together with off-line calibration methodologies, are proposed to assist in decision-making about further process optimization in biological phosphate removal, since parameter values obtained by off-line calibration give valuable information about the activated sludge process such as the amount of DPAOs in the system.

  18. Diversity and activity of denitrifiers of chilean arid soil ecosystems.

    PubMed

    Orlando, Julieta; Carú, Margarita; Pommerenke, Bianca; Braker, Gesche

    2012-01-01

    The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular.

  19. Diversity and Activity of Denitrifiers of Chilean Arid Soil Ecosystems

    PubMed Central

    Orlando, Julieta; Carú, Margarita; Pommerenke, Bianca; Braker, Gesche

    2012-01-01

    The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  1. Anoxic Androgen Degradation by the Denitrifying Bacterium Sterolibacterium denitrificans via the 2,3-seco Pathway

    PubMed Central

    Wang, Po-Hsiang; Yu, Chang-Ping; Lee, Tzong-Huei; Lin, Ching-Wen; Ismail, Wael; Wey, Shiaw-Pyng; Kuo, An-Ti

    2014-01-01

    The biodegradation of steroids is a crucial biochemical process mediated exclusively by bacteria. So far, information concerning the anoxic catabolic pathways of androgens is largely unknown, which has prevented many environmental investigations. In this work, we show that Sterolibacterium denitrificans DSMZ 13999 can anaerobically mineralize testosterone and some C19 androgens. By using a 13C-metabolomics approach and monitoring the sequential appearance of the intermediates, we demonstrated that S. denitrificans uses the 2,3-seco pathway to degrade testosterone under anoxic conditions. Furthermore, based on the identification of a C17 intermediate, we propose that the A-ring cleavage may be followed by the removal of a C2 side chain at C-5 of 17-hydroxy-1-oxo-2,3-seco-androstan-3-oic acid (the A-ring cleavage product) via retro-aldol reaction. The androgenic activities of the bacterial culture and the identified intermediates were assessed using the lacZ-based yeast androgen assay. The androgenic activity in the testosterone-grown S. denitrificans culture decreased significantly over time, indicating its ability to eliminate androgens. The A-ring cleavage intermediate (≤500 μM) did not exhibit androgenic activity, whereas the sterane-containing intermediates did. So far, only two androgen-degrading anaerobes (Sterolibacterium denitrificans DSMZ 13999 [a betaproteobacterium] and Steroidobacter denitrificans DSMZ 18526 [a gammaproteobacterium]) have been isolated and characterized, and both of them use the 2,3-seco pathway to anaerobically degrade androgens. The key intermediate 2,3-seco-androstan-3-oic acid can be used as a signature intermediate for culture-independent environmental investigations of anaerobic degradation of C19 androgens. PMID:24657867

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  3. Denitrifying bioreactors for nitrate removal from tile drained cropland

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Trace Gas Emission from in-Situ Denitrifying Bioreactors

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Effect of NaCl on aerobic denitrification by strain Achromobacter sp. GAD-3.

    PubMed

    Gui, Mengyao; Chen, Qian; Ni, Jinren

    2017-03-01

    This paper presents the effect of NaCl on aerobic denitrification by a novel aerobic denitrifier strain Achromobacter sp. GAD-3. Results indicated that the aerobic denitrification process was inhibited by NaCl concentrations ≥20 g L(-1), leading to lower nitrate removal rates (1.67∼4.0 mg L(-1) h(-1)), higher nitrite accumulation (50.2∼87.4 mg L(-1)), and increasing N2O emission ratios (13∼72 mg L(-1)/mg L(-1)). Poor performance of aerobic denitrification at high salinity was attributed to the suppression of active microbial biomass and electron donating capacity of strain GAD-3. Further studies on the corresponding inhibition of the denitrifying gene expression by higher salinities revealed the significant sensitivity order of nosZ (for N2O reductase) > cnorB (for NO reductase) ≈ nirS (for cytochrome cd(1) nitrite reductase) > napA (for periplasmic nitrate reductase), accompanied with a time-lapse expression between nosZ and cnorB based on reverse transcription and real-time quantitative polymerase chain reaction (RT-qPCR) analysis. The insights into the effect of NaCl on aerobic denitrification are of great significance to upgrade wastewater treatment plants (WWTPs) containing varying levels of salinity.

  6. Comparison of endogenous metabolism during long-term anaerobic starvation of nitrite/nitrate cultivated denitrifying phosphorus removal sludges.

    PubMed

    Wang, Yayi; Zhou, Shuai; Wang, Hong; Ye, Liu; Qin, Jian; Lin, Ximao

    2015-01-01

    Denitrifying phosphorus removal (DPR) by denitrifying phosphorus-accumulating organisms (DPAOs) is a promising approach for reducing energy and carbon usage. However, influent fluctuations or interruptions frequently expose the DPAOs biomass to starvation conditions, reducing biomass activity and amount, and ultimately degrading the performance of DPR. Therefore, a better understanding of the endogenous metabolism and recovery ability of DPAOs is urgently required. In the present study, anaerobic starvation (12 days) and recovery were investigated in nitrite- and nitrate-cultivated DPAOs at 20 ± 1 °C. The cell decay rates in nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were 0.008 day⁻¹ and 0.007 day⁻¹, respectively, being 64% and 68% lower than those of nitrate-DPAOs sludges. Nitrite-DPAOs sludges also recovered more rapidly than nitrate-DPAOs sludge after 12 days of starvation. The maintenance energy of nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were approximately 31% and 34% lower, respectively, than those of nitrate-DPAOs sludges. Glycogen and polyphosphate (poly-P) sequentially served as the main maintenance energy sources in both nitrite-and nitrate-DPAOs sludges. However, the transformation pathway of the intracellular polymers during starvation differed between them. Nitrate-DPAOs sludge used extracellular polymeric substances (EPS) (mainly polysaccharides) as an additional maintenance energy source during the first 3 days of starvation. During this phase, EPS appeared to contribute to 19-27% of the ATP production in nitrate-DPAOs, but considerably less to the cell maintenance of nitrite-DPAOs. The high resistance of nitrite-DPAOs to starvation might be attributable to frequent short-term starvation and exposure to toxic substances such as nitrite/free nitrous acids in the parent nitrite-fed reactor. The strong resistance of nitrite-DPAOs sludge to anaerobic starvation may be exploited in P removal

  7. The Denitrification Characteristics and Microbial Community in the Cathode of an MFC with Aerobic Denitrification at High Temperatures

    PubMed Central

    Zhao, Jianqiang; Wu, Jinna; Li, Xiaoling; Wang, Sha; Hu, Bo; Ding, Xiaoqian

    2017-01-01

    Microbial fuel cells (MFCs) have attracted much attention due to their ability to generate electricity while treating wastewater. The performance of a double-chamber MFC with simultaneous nitrification and denitrification (SND) in the cathode for treating synthetic high concentration ammonia wastewater was investigated at different dissolved oxygen (DO) concentrations and high temperatures. The results showed that electrode denitrification and traditional heterotrophic denitrification co-existed in the cathode chamber. Electrode denitrification by aerobic denitrification bacterium (ADB) is beneficial for achieving a higher voltage of the MFC at high DO concentrations (3.0–4.2 mg/L), while traditional heterotrophic denitrification is conducive to higher total nitrogen (TN) removal at low DO (0.5–1.0 mg/L) concentrations. Under high DO conditions, the nitrous oxide production and TN removal efficiency were higher with a 50 Ω external resistance than with a 100 Ω resistance, which demonstrated that electrode denitrification by ADB occurred in the cathode of the MFC. Sufficient electrons were inferred to be provided by the electrode to allow ADB survival at low carbon:nitrogen ratios (≤0.3). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results showed that increasing the DO resulted in a change of the predominant species from thermophilic autotrophic nitrifiers and facultative heterotrophic denitrifiers at low DO concentrations to thermophilic ADB at high DO concentrations. The predominant phylum changed from Firmicutes to Proteobacteria, and the predominant class changed from Bacilli to Alpha, Beta, and Gamma Proteobacteria. PMID:28154554

  8. Optimal cultivation of simultaneous ammonium and phosphorus removal aerobic granular sludge in A/O/A sequencing batch reactor and the assessment of functional organisms.

    PubMed

    Zhang, Cuiya; Zhang, Hanmin; Yang, Fenglin

    2014-08-01

    In this study, sequencing batch reactor (SBR) with an anaerobic/aerobic/anoxic operating mode was used to culture granular sludge. Optimal adjustment of cycle duration was achieved by the direction ofpH, oxidation reduction potential and dissolved oxygen parameters. The results showed that the treating efficiency was significantly improved as the cycle was shortened from 450 to 360 min and further to 200 min. Nitrogen and phosphorus removal were nearly quantitative after 50 days operation and maintained stable to the end of the study period. The typical cycle tests revealed that simultaneous denitrification and phosphorus removal occurred when aerobic granules were gradually formed. The nitrite effect tests showed that less than 4.8 mg N/L of the nitrite could enhance superficial specific aerobic phosphate uptake rate (SAPUR) under aerobic condition, indicating that the traditional method to evaluate the capability of total phosphate-accumulating organisms (PAOs) was inaccurate. Additionally, a high level of nitrite was detrimental to PAOs. A novel method was developed to determine the activity of each kind of PAOs and other denitrifying organisms. The results showed that (1) nitrate, besides nitrite, could also enhance SAPUR and (2) aerobic granular sludge could perform denitrification even when phosphate was not supplied under anoxic condition, suggesting that other denitrifying organisms besides denitrifying phosphate-accumulating organisms also contributed to denitrification.

  9. Diversity of Denitrifying Bacteria in the San Francisco Bay

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Teaching Aerobic Fitness Concepts.

    ERIC Educational Resources Information Center

    Sander, Allan N.; Ratliffe, Tom

    2002-01-01

    Discusses how to teach aerobic fitness concepts to elementary students. Some of the K-2 activities include location, size, and purpose of the heart and lungs; the exercise pulse; respiration rate; and activities to measure aerobic endurance. Some of the 3-6 activities include: definition of aerobic endurance; heart disease risk factors;…

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

    PubMed Central

    Langone, Michela; Yan, Jia; Haaijer, Suzanne C. M.; Op den Camp, Huub J. M.; Jetten, Mike S. M.; Andreottola, Gianni

    2014-01-01

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

  12. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions

    PubMed Central

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD. PMID:24245852

  13. Genes Involved in Anaerobic Metabolism of Phenol in the Bacterium Thauera aromatica

    PubMed Central

    Breinig, Sabine; Schiltz, Emile; Fuchs, Georg

    2000-01-01

    Genes involved in the anaerobic metabolism of phenol in the denitrifying bacterium Thauera aromatica have been studied. The first two committed steps in this metabolism appear to be phosphorylation of phenol to phenylphosphate by an unknown phosphoryl donor (“phenylphosphate synthase”) and subsequent carboxylation of phenylphosphate to 4-hydroxybenzoate under release of phosphate (“phenylphosphate carboxylase”). Both enzyme activities are strictly phenol induced. Two-dimensional gel electrophoresis allowed identification of several phenol-induced proteins. Based on N-terminal and internal amino acid sequences of such proteins, degenerate oligonucleotides were designed to identify the corresponding genes. A chromosomal DNA segment of about 14 kbp was sequenced which contained 10 genes transcribed in the same direction. These are organized in two adjacent gene clusters and include the genes coding for five identified phenol-induced proteins. Comparison with sequences in the databases revealed the following similarities: the gene products of two open reading frames (ORFs) are each similar to either the central part and N-terminal part of phosphoenolpyruvate synthases. We propose that these ORFs are components of the phenylphosphate synthase system. Three ORFs showed similarity to the ubiD gene product, 3-octaprenyl-4-hydroxybenzoate carboxy lyase; UbiD catalyzes the decarboxylation of a 4-hydroxybenzoate analogue in ubiquinone biosynthesis. Another ORF was similar to the ubiX gene product, an isoenzyme of UbiD. We propose that (some of) these four proteins are involved in the carboxylation of phenylphosphate. A 700-bp PCR product derived from one of these ORFs cross-hybridized with DNA from different Thauera and Azoarcus strains, even from those which have not been reported to grow with phenol. One ORF showed similarity to the mutT gene product, and three ORFs showed no strong similarities to sequences in the databases. Upstream of the first gene cluster, an

  14. Characteristics of Biological Nitrogen Removal in a Multiple Anoxic and Aerobic Biological Nutrient Removal Process

    PubMed Central

    Wang, Huoqing; Guan, Yuntao; Li, Li; Wu, Guangxue

    2015-01-01

    Two sequencing batch reactors, one with the conventional anoxic and aerobic (AO) process and the other with the multiple AO process, were operated to examine characteristics of biological nitrogen removal, especially of the multiple AO process. The long-term operation showed that the total nitrogen removal percentage of the multiple AO reactor was 38.7% higher than that of the AO reactor. In the multiple AO reactor, at the initial SBR cycle stage, due to the occurrence of simultaneous nitrification and denitrification, no nitrite and/or nitrate were accumulated. In the multiple AO reactor, activities of nitrite oxidizing bacteria were inhibited due to the multiple AO operating mode applied, resulting in the partial nitrification. Denitrifiers in the multiple AO reactor mainly utilized internal organic carbon for denitrification, and their activities were lower than those of denitrifiers in the AO reactor utilizing external organic carbon. PMID:26491676

  15. Performance of agricultural residue media in laboratory denitrifying bioreactors at low temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Woodchip denitrifying bioreactors can remove a substantial fraction of nitrate from agricultural tile drainage; however, questions about cold springtime performance persist. The objectives of this study were to improve the nitrate removal rate of denitrifying bioreactors at warm and cold temperature...

  16. Isolation and Characterization of a Chlorinated-Pyridinol-Degrading Bacterium

    PubMed Central

    Feng, Y.; Racke, K. D.; Bollag, J.

    1997-01-01

    The isolation of a pure culture of bacteria able to use 3,5,6-trichloro-2-pyridinol (TCP) as a sole source of carbon and energy under aerobic conditions was achieved for the first time. The bacterium was identified as a Pseudomonas sp. and designated ATCC 700113. [2,6-(sup14)C]TCP degradation yielded (sup14)CO(inf2), chloride, and unidentified polar metabolites. PMID:16535719

  17. Effects of elevated CO2 concentrations on denitrifying and nitrifying popualtions at terrestrial CO2 leakeage analogous sites

    NASA Astrophysics Data System (ADS)

    Christine, Dictor Marie; Catherine, Joulian; Valerie, Laperche; Stephanie, Coulon; Dominique, Breeze

    2010-05-01

    CO2 capture and geological storage (CCS) is recognized to be an important option for carbon abatement in Europe. One of the risks of CCS is the leakage from storage site. A laboratory was conducted on soil samples sampled near-surface from a CO2 leakage analogous site (Latera, Italy) in order to evaluate the impact of an elevated soil CO2 concentration on terrestrial bacterial ecosystems form near surface terrestrial environments and to determine a potential bacterial indicator of CO2 leakage from storage site. Surveys were conducted along a 50m long transect across the vent centre, providing a spectrum of CO2 flux rates, soil gas concentrations and compositions (Beaubien et al., 2007). A bacterial diversity studies, performed by CE-SSCP technique, on a soil profile with increasing CO2 soil concentrations (from 0.3% to 100%) showed that a change on bacterial diversity was noted when CO2 concentration was above 50 % of CO2. From this result, 3 soil samples were taken at 70 cm depth in 3 distinct zones (background soil CO2 content, soil CO2 content of 20% and soil CO2 content of 50%). Then theses soil samples were incubated under closed jars flushed with different air atmospheres (20, 50 and 90 % of CO2) during 18 months. At initial, 3, 6, 12 and 18 months, some soil samples were collected in order to estimate the denitrifying, nitrifying activities as a function of CO2 concentration content and times. Theses enzymatic activities were chosen because one occurs under anaerobic conditions (denitrification) and the other occurs under aerobic conditions (nitrification). Both of them were involved in the nitrogen cycle and are major actors of soil function and groundwater quality preservation. Metabolic diversity using BIOLOG Ecoplates was determined on every soil samples. Physico-chemical parameters (e.g. pH, bulk chemistry, mineralogy) were analyzed to have some information about the evolution of the soil during the incubation with increasing soil CO2 concentrations

  18. Effects of inorganic salts on denitrifying granular sludge: The acute toxicity and working mechanisms.

    PubMed

    Wang, Ru; Zheng, Ping; Ding, A-qiang; Zhang, Meng; Ghulam, Abbas; Yang, Cheng; Zhao, He-Ping

    2016-03-01

    It is highly significant to investigate the toxicity of inorganic salts to denitrifying granular sludge (DGS) and its mechanism since the application of high-rate denitrification is seriously limited in the treatment of saline nitrogen-rich wastewaters. The batch experiments showed that the IC50 (half inhibition concentration) and LC50 (half lethal concentration) of NaCl, Na2SO4 and Na3PO4 on DGS were 11.46, 21.72, 7.46 g/L and 77.35, 100.58, 67.92 g/L respectively. Based on the analysis of specific denitrifying activity, the live cell percentage, the cell structure, and the DNA leakage, the toxicity of low salinity was ascribed to the inhibition of denitrifying activity and the toxicity of high salinity was ascribed to both the inhibition of denitrifying activity and the lethality of denitrifying cell.

  19. Characterization of nitrifying, denitrifying, and overall bacterial communities in permeable marine sediments of the northeastern Gulf of Mexico.

    PubMed

    Mills, Heath J; Hunter, Evan; Humphrys, Mike; Kerkhof, Lee; McGuinness, Lora; Huettel, Markus; Kostka, Joel E

    2008-07-01

    Sandy or permeable sediment deposits cover the majority of the shallow ocean seafloor, and yet the associated bacterial communities remain poorly described. The objective of this study was to expand the characterization of bacterial community diversity in permeable sediment impacted by advective pore water exchange and to assess effects of spatial, temporal, hydrodynamic, and geochemical gradients. Terminal restriction fragment length polymorphism (TRFLP) was used to analyze nearly 100 sediment samples collected from two northeastern Gulf of Mexico subtidal sites that primarily differed in their hydrodynamic conditions. Communities were described across multiple taxonomic levels using universal bacterial small subunit (SSU) rRNA targets (RNA- and DNA-based) and functional markers for nitrification (amoA) and denitrification (nosZ). Clonal analysis of SSU rRNA targets identified several taxa not previously detected in sandy sediments (i.e., Acidobacteria, Actinobacteria, Chloroflexi, Cyanobacteria, and Firmicutes). Sequence diversity was high among the overall bacterial and denitrifying communities, with members of the Alphaproteobacteria predominant in both. Diversity of bacterial nitrifiers (amoA) remained comparatively low and did not covary with the other gene targets. TRFLP fingerprinting revealed changes in sequence diversity from the family to species level across sediment depth and study site. The high diversity of facultative denitrifiers was consistent with the high permeability, deeper oxygen penetration, and high rates of aerobic respiration determined in these sediments. The high relative abundance of Gammaproteobacteria in RNA clone libraries suggests that this group may be poised to respond to short-term periodic pulses of growth substrates, and this observation warrants further investigation.

  20. Archaeal ammonia oxidizers and nirS-type denitrifiers dominate sediment nitrifying and denitrifying populations in a subtropical macrotidal estuary.

    PubMed

    Abell, Guy C J; Revill, Andrew T; Smith, Craig; Bissett, Andrew P; Volkman, John K; Robert, Stanley S

    2010-02-01

    Nitrification and denitrification are key steps in nitrogen (N) cycling. The coupling of these processes, which affects the flow of N in ecosystems, requires close interaction of nitrifying and denitrifying microorganisms, both spatially and temporally. The diversity, temporal and spatial variations in the microbial communities affecting these processes was examined, in relation to N cycling, across 12 sites in the Fitzroy river estuary, which is a turbid subtropical estuary in central Queensland. The estuary is a major source of nutrients discharged to the Great Barrier Reef near-shore zone. Measurement of nitrogen fluxes showed an active denitrifying community during all sampling months. Archaeal ammonia monooxygenase (amoA of AOA, functional marker for nitrification) was significantly more abundant than Betaproteobacterial (beta-AOB) amoA. Nitrite reductase genes, functional markers for denitrification, were dominated by nirS and not nirK types at all sites during the year. AOA communities were dominated by the soil/sediment cluster of Crenarchaeota, with sequences found in estuarine sediment, marine and terrestrial environments, whereas nirS sequences were significantly more diverse (where operational taxonomic units were defined at both the threshold of 5% and 15% sequence similarity) and were closely related to sequences originating from estuarine sediments. Terminal-restriction fragment length polymorphism (T-RFLP) analysis revealed that AOA population compositions varied spatially along the estuary, whereas nirS populations changed temporally. Statistical analysis of individual T-RF dominance suggested that salinity and C:N were associated with the community succession of AOA, whereas the nirS-type denitrifier communities were related to salinity and chlorophyll-alpha in the Fitzroy river estuary.

  1. Effect of dissolved oxygen on nitrate removal using polycaprolactone as an organic carbon source and biofilm carrier in fixed-film denitrifying reactors.

    PubMed

    Luo, Guozhi; Xu, Guimei; Gao, Jinfang; Tan, Hongxin

    2016-05-01

    Nitrate-nitrogen (NO3(-)-N) always accumulates in commercial recirculating aquaculture systems (RASs) with aerobic nitrification units. The ability to reduce NO3(-)-N consistently and confidently could help RASs to become more sustainable. The rich dissolved oxygen (DO) content and sensitive organisms stocked in RASs increase the difficulty of denitrifying technology. A denitrifying process using biologically degradable polymers as an organic carbon source and biofilm carrier was proposed because of its space-efficient nature and strong ability to remove NO3(-)-N from RASs. The effect of dissolved oxygen (DO) levels on heterotrophic denitrification in fixed-film reactors filled with polycaprolactone (PCL) was explored in the current experiment. DO conditions in the influent of the denitrifying reactors were set up as follows: the anoxic treatment group (Group A, average DO concentration of 0.28±0.05mg/L), the low-oxygen treatment DO group (Group B, average DO concentration of 2.50±0.24mg/L) and the aerated treatment group (Group C, average DO concentration of 5.63±0.57mg/L). Feeding with 200mg/L of NO3(-)-N, the NO3(-)-N removal rates were 1.53, 1.60 and 1.42kg/m(3) PCL/day in Groups A, B and C, respectively. No significant difference in NO3(-)-N removal rates was observed among the three treatments. It was concluded that the inhibitory effects of DO concentrations lower than 6mg/L on heterotrophic denitrification in the fixed-film reactors filled with PCL can be mitigated.

  2. Degradation of triclosan under aerobic, anoxic, and anaerobic conditions.

    PubMed

    Gangadharan Puthiya Veetil, Prajeesh; Vijaya Nadaraja, Anupama; Bhasi, Arya; Khan, Sudheer; Bhaskaran, Krishnakumar

    2012-07-01

    Triclosan (2, 4, 4'-trichloro-2'-hydroxyl diphenyl ether) is a broad-spectrum antimicrobial agent present in a number of house hold consumables. Aerobic and anaerobic enrichment cultures tolerating triclosan were developed and 77 bacterial strains tolerating triclosan at different levels were isolated from different inoculum sources. Biodegradation of triclosan under aerobic, anoxic (denitrifying and sulphate reducing conditions), and anaerobic conditions was studied in batch cultures with isolated pure strains and enrichment consortium developed. Under aerobic conditions, the isolated strains tolerated triclosan up to 1 g/L and degraded the compound in inorganic-mineral-broth and agar media. At 10 mg/L level triclosan, 95 ± 1.2% was degraded in 5 days, producing phenol, catechol and 2, 4-dichlorophenol as the degradation products. The strains were able to metabolize triclosan and its degradation products in the presence of monooxygenase inhibitor 1-pentyne. Under anoxic/anaerobic conditions highest degradation (87%) was observed in methanogenic system with acetate as co-substrate and phenol, catechol, and 2, 4-dichlorophenol were among the products. Three of the isolated strains tolerating 1 g/L triclosan were identified as Pseudomonas sp. (BDC 1, 2, and 3).

  3. Greenhouse Gas Emission from In-situ Denitrifying Bioreactors

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Nitrogen removal by Providencia rettgeri strain YL with heterotrophic nitrification and aerobic denitrification.

    PubMed

    Ye, Jun; Zhao, Bin; An, Qiang; Huang, Yuan-Sheng

    2016-09-01

    Providencia rettgeri strain YL shows the capability of nitrogen removal under sole aerobic conditions. By using isotope ratio mass spectrometry, (15)N-labelled N2O and N2 were detected in aerobic batch cultures containing [Formula: see text], [Formula: see text] or [Formula: see text]. Strain YL converted [Formula: see text], [Formula: see text] and [Formula: see text] to produce more N2O than N2 in the presence of [Formula: see text]. An (15)N isotope tracing experiment confirmed that the nitrogen removal pathway of strain YL was heterotrophic nitrification-aerobic denitrification. The optimal treatment conditions for nitrogen removal were pH of 8, C/N ratio of 12, temperature of 25°C and shaking speed of 105 rpm. A continuous aerobic bioreactor inoculated with strain YL was developed. With an influent [Formula: see text] concentration of 90-200 mg/L, the [Formula: see text] removal efficiency ranged from 80% to 97% and the total nitrogen removal efficiency ranged from 72% to 95%. The nitrogen balance in the continuous bioreactor revealed that approximately 35-52% of influent [Formula: see text] was denitrified aerobically to form gaseous nitrogen. These findings show that the P. rettgeri strain YL has potential application in wastewater treatment for nitrogen removal under sole aerobic conditions.

  5. Agrobacterium tumefaciens is a diazotrophic bacterium

    SciTech Connect

    Kanvinde, L.; Sastry, G.R.K. )

    1990-07-01

    This is the first report that Agrobacterium tumefaciens can fix nitrogen in a free-living condition as shown by its abilities to grown on nitrogen-free medium, reduce acetylene to ethylene, and incorporate {sup 15}N supplied as {sup 15}N{sub 2}. As with most other well-characterized diazotrophic bacteria, the presence of NH{sub 4}{sup +} in the medium and aerobic conditions repress nitrogen fixation by A. tumefaciens. The system requires molybdenum. No evidence for nodulation was found with pea, peanut, or soybean plants. Further understanding of the nitrogen-fixing ability of this bacterium, which has always been considered a pathogen, should cast new light on the evolution of a pathogenic versus symbiotic relationship.

  6. Optical sorting and cultivation of denitrifying anaerobic methane oxidation archaea

    PubMed Central

    Qi, Xiaoqiong; Carberry, David M.; Cai, Chen; Hu, Shihu; Yuan, Zhiguo; Dunlop, Halin Rubinsztein; Guo, Jianhua

    2017-01-01

    Denitrifying anaerobic methane oxidizing (DAMO) microorganisms play an important role in the global carbon and nitrogen cycles as they are able to mediate methane oxidation using nitrite/nitrate under anoxic conditions. However, the physiological properties of DAMO microorganisms remain poorly understood, partially since the organisms are difficult to isolate or cultivate in pure culture and partially because of their long cultivation time. In this study, DAMO cell sorting has been conducted by integrating optical tweezers within enclosed microfluidic chips. This integrated cell sorting method has high purity, low infection rates, and causes no discernable harm to cell viability. The purity of the sorted cells was controlled by the microfluidic chip structure design and operation, while the cell viability was verified by imaging the cultured DAMO archaea after 420 days. PMID:28270994

  7. Impact of nitrite on aerobic phosphorus uptake by poly-phosphate accumulating organisms in enhanced biological phosphorus removal sludges.

    PubMed

    Zeng, Wei; Li, Boxiao; Yang, Yingying; Wang, Xiangdong; Li, Lei; Peng, Yongzhen

    2014-02-01

    Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5% of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10(-3) mg HNO₂-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10(-3) mg HNO2-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10(-3) and 2.13 × 10(-3) mg HNO₂-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite.

  8. Imprint of denitrifying bacteria on the global terrestrial biosphere.

    PubMed

    Houlton, Benjamin Z; Bai, Edith

    2009-12-22

    Loss of nitrogen (N) from land limits the uptake and storage of atmospheric CO(2) by the biosphere, influencing Earth's climate system and myriads of the global ecological functions and services on which humans rely. Nitrogen can be lost in both dissolved and gaseous phases; however, the partitioning of these vectors remains controversial. Particularly uncertain is whether the bacterial conversion of plant available N to gaseous forms (denitrification) plays a major role in structuring global N supplies in the nonagrarian centers of Earth. Here, we use the isotope composition of N ((15)N/(14)N) to constrain the transfer of this nutrient from the land to the water and atmosphere. We report that the integrated (15)N/(14)N of the natural terrestrial biosphere is elevated with respect to that of atmospheric N inputs. This cannot be explained by preferential loss of (14)N to waterways; rather, it reflects a history of low (15)N/(14)N gaseous N emissions to the atmosphere owing to denitrifying bacteria in the soil. Parameterizing a simple model with global N isotope data, we estimate that soil denitrification (including N(2)) accounts for approximately 1/3 of the total N lost from the unmanaged terrestrial biosphere. Applying this fraction to estimates of N inputs, N(2)O and NO(x) fluxes, we calculate that approximately 28 Tg of N are lost annually via N(2) efflux from the natural soil. These results place isotopic constraints on the widely held belief that denitrifying bacteria account for a significant fraction of the missing N in the global N cycle.

  9. Draft Genome Sequence of the Efficient Bioflocculant-Producing Bacterium Paenibacillus sp. Strain A9

    PubMed Central

    Liu, Jin-liang; Hu, Xiao-min

    2013-01-01

    Paenibacillus sp. strain A9 is an important bioflocculant-producing bacterium, isolated from a soil sample, and is pale pink-pigmented, aerobic, and Gram-positive. Here, we report the draft genome sequence and the initial findings from a preliminary analysis of strain A9, which is a novel species of Paenibacillus. PMID:23618713

  10. Draft Genome Sequence of the Efficient Bioflocculant-Producing Bacterium Paenibacillus sp. Strain A9.

    PubMed

    Jiang, Bin-Hui; Liu, Jin-Liang; Hu, Xiao-Min

    2013-04-25

    Paenibacillus sp. strain A9 is an important bioflocculant-producing bacterium, isolated from a soil sample, and is pale pink-pigmented, aerobic, and Gram-positive. Here, we report the draft genome sequence and the initial findings from a preliminary analysis of strain A9, which is a novel species of Paenibacillus.

  11. Genome Sequence of a Strain of the Human Pathogenic Bacterium Pseudomonas alcaligenes That Caused Bloodstream Infection.

    PubMed

    Suzuki, Masato; Suzuki, Satowa; Matsui, Mari; Hiraki, Yoichi; Kawano, Fumio; Shibayama, Keigo

    2013-10-31

    Pseudomonas alcaligenes, a Gram-negative aerobic bacterium, is a rare opportunistic human pathogen. Here, we report the whole-genome sequence of P. alcaligenes strain MRY13-0052, which was isolated from a bloodstream infection in a medical institution in Japan and is resistant to antimicrobial agents, including broad-spectrum cephalosporins and monobactams.

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

    EPA Science Inventory

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

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

    EPA Science Inventory

    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 degr...

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

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

    2001-01-01

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

  15. What Is Aerobic Dancing?

    MedlinePlus

    ... aerobics can reach up to six times the force of gravity, which is transmitted to each of the 26 bones in the foot. Because of the many side-to-side motions, shoes need an arch design that will compensate ...

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

    PubMed

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

    2016-10-01

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

  17. Identification of the autotrophic denitrifying community in nitrate removal reactors by DNA-stable isotope probing.

    PubMed

    Xing, Wei; Li, Jinlong; Cong, Yuan; Gao, Wei; Jia, Zhongjun; Li, Desheng

    2017-04-01

    Autotrophic denitrification has attracted increasing attention for wastewater with insufficient organic carbon sources. Nevertheless, in situ identification of autotrophic denitrifying communities in reactors remains challenging. Here, a process combining micro-electrolysis and autotrophic denitrification with high nitrate removal efficiency was presented. Two batch reactors were fed organic-free nitrate influent, with H(13)CO3(-) and H(12)CO3(-) as inorganic carbon sources. DNA-based stable-isotope probing (DNA-SIP) was used to obtain molecular evidence for autotrophic denitrifying communities. The results showed that the nirS gene was strongly labeled by H(13)CO3(-), demonstrating that the inorganic carbon source was assimilated by autotrophic denitrifiers. High-throughput sequencing and clone library analysis identified Thiobacillus-like bacteria as the most dominant autotrophic denitrifiers. However, 88% of nirS genes cloned from the (13)C-labeled "heavy" DNA fraction showed low similarity with all culturable denitrifiers. These findings provided functional and taxonomical identification of autotrophic denitrifying communities, facilitating application of autotrophic denitrification process for wastewater treatment.

  18. Abundance, diversity and functional gene expression of denitrifier communities in adjacent riparian and agricultural zones.

    PubMed

    Dandie, Catherine E; Wertz, Sophie; Leclair, Caissie L; Goyer, Claudia; Burton, David L; Patten, Cheryl L; Zebarth, Bernie J; Trevors, Jack T

    2011-07-01

    Lands under riparian and agricultural management differ in soil properties, water content, plant species and nutrient content and are therefore expected to influence denitrifier communities, denitrification and nitrous oxide (N(2) O) emissions. Denitrifier community abundance, denitrifier community structure, denitrification gene expression and activity were quantified on three dates in a maize field and adjacent riparian zone. N(2) O emissions were greater in the agricultural zone, whereas complete denitrification to N(2) was greater in the riparian zone. In general, the targeted denitrifier community abundance did not change between agricultural and riparian zones. However, nosZ gene expression was greater in the riparian zone than the agricultural zone. The community structure of nirS-gene-bearing denitrifiers differed in June only, whereas the nirK-gene-bearing community structure differed significantly between the riparian and the agricultural zones at all dates. The nirK-gene-bearing community structure was correlated with soil pH, while no significant correlations were found between nirS-gene-bearing community structure and soil environmental variables or N(2) O emissions, denitrification or denitrifier enzyme activity. The results suggested for the nirK and nirS-gene-bearing communities different factors control abundance vs. community structure. The nirK-gene-bearing community structure was also more responsive than the nirS-gene-bearing community structure to change between the two ecosystems.

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

    PubMed Central

    Linchangco, Richard

    2014-01-01

    Heterotrophic nitrifiers synthesize nitrogenous gasses when nitrifying ammonium ion. A Cupriavidus pauculus, previously thought an Alcaligenes sp. and noted as an active heterotrophic nitrifier-denitrifier, was examined for its ability to produce nitrogen gas (N2) and nitrous oxide (N2O) while heterotrophically nitrifying the organic substrate pyruvic oxime [CH3–C(NOH)–COOH]. Neither N2 nor N2O were produced. Nucleotide and phylogenetic analyses indicated that the organism is a member of a genus (Cupriavidus) known for its resistance to metals and its metabolism of xenobiotics. The microbe (a Cupriavidus pauculus designated as C. pauculus strain UM1) was examined for its ability to perform heterotrophic nitrification in the presence of Cu2+ and Ni2+ and to metabolize the xenobiotic phenol. The bacterium heterotrophically nitrified well when either 1 mM Cu2+ or 0.5 mM Ni2+ was present in either enriched or minimal medium. The organism also used phenol as a sole carbon source in either the presence or absence of 1 mM Cu2+ or 0.5 mM Ni2+. The ability of this isolate to perform a number of different metabolisms, its noteworthy resistance to copper and nickel, and its potential use as a bioremediation agent are discussed. PMID:25580463

  20. Biodegradability of some nitrogenous heterocyclic compounds and co-degradation with phenol by denitrifiers in anoxic sludge reactor.

    PubMed

    Wang, Zixing; Xu, Xiaochen; Yang, Fenglin; Tan, Zhongxia; Chen, Jie

    2015-01-01

    Phenol and nitrogenous heterocyclic compounds (NHCs) are typical organic pollutants in coal gasification wastewater which are difficult to deal with. Unlike phenol, the stable molecular structure of NHCs make them nearly impossible to degrade under aerobic or anaerobic condition. In this paper, biodegradation of phenol and NHCs as carbon sources for denitrification was studied in a laboratory-scale anoxic reactor. Denitrifiers could degrade 490 mg/L phenol and 321.5 mg/L NO3(-)-N within 12 hours with removal efficiencies of 99.8% and 99.6%, respectively. The inhibition of pyridine on the microbes could be reduced by adding phenol into influent and the experimental results showed that pyridine could be degraded as the sole carbon source with the maximum organic loading rate of 4.38 mg/(g MLSS·h) (MLSS: mixed liquor suspended solids). When phenol was included as a growth substrate, the degradation performance of quinoline and pyrrole was improved due to co-degradation, and removal rate of NHCs increased according with increment of phenol in influent.

  1. Investigating the nitrification and denitrification kinetics under aerobic and anaerobic conditions by Paracoccus denitrificans ISTOD1.

    PubMed

    Medhi, Kristina; Singhal, Anjali; Chauhan, D K; Thakur, Indu Shekhar

    2017-03-16

    Municipal wastewater contains multiple nitrogen contaminants such as ammonia, nitrate and nitrite. Two heterotrophic nitrifier and aerobic denitrifiers, bacterial isolates ISTOD1 and ISTVD1 were isolated from domestic wastewater. On the basis of removal efficiency of ammonia, nitrate and nitrite under both aerobic and anaerobic conditions, ISTOD1 was selected and identified as Paracoccus denitrificans. Aerobically, NH4(+)-N had maximum specific nitrogen removal rate (Rxi) of 7.6g/gDCW/h and anaerobically, NO3(-)N showed Rxi of 2.5*10(-1)g/g DCW/h. Monod equation described the bioprocess kinetic coefficients, µmax and Ks, obtained by regression. Error functions were calculated to validate the Monod equation experimental data. Aerobic NO3(-)N showed the highest YW of 0.372mg DCW/mg NO3(-)N among the five conditions. ISTOD1 serves as a potential candidate for treating nitrogen rich wastewater using simultaneous nitrification and aerobic denitrification. It can be used in bioaugmentation studies under varied condition.

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

    SciTech Connect

    Green, Stefan; Prakash, Om; Gihring, Thomas; Akob, Denise M.; Jasrotia, Puja; Jardine, Philip M; Watson, David B; Brown, Steven D; Palumbo, Anthony Vito; Kostka, Joel

    2010-01-01

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

  3. Denitrifier Community in the Oxygen Minimum Zone of a Subtropical Deep Reservoir

    PubMed Central

    Yu, Zheng; Yang, Jun; Liu, Lemian

    2014-01-01

    Denitrification is an important pathway for nitrogen removal from aquatic systems and this could benefit water quality. However, little is known about the denitrifier community composition and key steps of denitrification in the freshwater environments, and whether different bacteria have a role in multiple processes of denitrification reduction. In this study, quantitative PCR, quantitative RT-PCR, clone library and 454 pyrosequencing were used together to investigate the bacterial and denitrifier community in a subtropical deep reservoir during the strongly stratified period. Our results indicated that the narG gene recorded the highest abundance among the denitrifying genes (2.76×109 copies L−1 for DNA and 4.19×108 copies L−1 for RNA), and the lowest value was nosZ gene (7.56×105 copies L−1 for DNA and undetected for RNA). The RNA: DNA ratios indicated that narG gene was the most active denitrifying gene in the oxygen minimum zone of Dongzhen Reservoir. Further, α-, β- and γ- Proteobacteria were the overwhelmingly dominant classes of denitrifier communities. Each functional gene had its own dominant groups which were different at the genus level: the narG gene was dominated by Albidiferax, while nirS gene was dominated by Dechloromonas. The main OTU of nirK gene was Rhodopseudomonas palustris, but for norB and nosZ genes, they were Bacillus and Bradyrhizobium, respectively. These results contribute to the understanding of linkages between denitrifier community, function and how they work together to complete the denitrification process. Studies on denitrifier community and activity may be useful in managing stratified reservoirs for the ecosystem services and aiding in constructing nitrogen budgets. PMID:24664112

  4. Anaerobic metabolism of catechol by the denitrifying bacterium Thauera aromatica--a result of promiscuous enzymes and regulators?

    PubMed

    Ding, Bin; Schmeling, Sirko; Fuchs, Georg

    2008-03-01

    The anaerobic metabolism of catechol (1,2-dihydroxybenzene) was studied in the betaproteobacterium Thauera aromatica that was grown with CO2 as a cosubstrate and nitrate as an electron acceptor. Based on different lines of evidence and on our knowledge of enzymes and genes involved in the anaerobic metabolism of other aromatic substrates, the following pathway is proposed. Catechol is converted to catechylphosphate by phenylphosphate synthase, which is followed by carboxylation by phenylphosphate carboxylase at the para position to the phosphorylated phenolic hydroxyl group. The product, protocatechuate (3,4-dihydroxybenzoate), is converted to its coenzyme A (CoA) thioester by 3-hydroxybenzoate-CoA ligase. Protocatechuyl-CoA is reductively dehydroxylated to 3-hydroxybenzoyl-CoA, possibly by 4-hydroxybenzoyl-CoA reductase. 3-Hydroxybenzoyl-CoA is further metabolized by reduction of the aromatic ring catalyzed by an ATP-driven benzoyl-CoA reductase. Hence, the promiscuity of several enzymes and regulatory proteins may be sufficient to create the catechol pathway that is made up of elements of phenol, 3-hydroxybenzoate, 4-hydroxybenzoate, and benzoate metabolism.

  5. INITIAL REACTIONS IN ANAEROBIC ETHYLBENZENE OXIDATION BY A DENITRIFYING BACTERIUM, STRAIN EB1. (R825689C070)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  6. Biodegradation of aromatic hydrocarbons by aquifer microorganisms under denitrifying conditions

    SciTech Connect

    Hutchins, S.R.; Sewell, G.W.; Kovacs, D.A.; Smith, G.A.

    1991-01-01

    Laboratory tests were conducted to evaluate whether denitrification would be a suitable alternative for biorestoration of an aquifer contaminated with JP-4 jet fuel. Microcosms were prepared from uncontaminated and contaminated aquifer material, amended with nitrate, nutrients, and aromatic hydrocarbons, and incubated under a nitrogen atmosphere at 12 C. With uncontaminated core material, there was no observable lag period prior to removal of toluene whereas 30 days was required before biodegradation commenced for xylenes, ethylbenzene, and 1,2,4-trimethylbenzene. An identical test with contaminated aquifer material exhibited not only much longer lag periods but decreased rates of biodegradation; benzene, ethylbenzene, and o-xylene were not significantly degraded within the 6-month time period even though active denitrification occurred at this time. First-order biodegradation rate constants ranged from 0.016 to 0.38/day for uncontaminated core material and from 0.022 to 0.067/day for contaminated core material. Tests with individual compounds in uncontaminated core indicated that benzene and m-xylene inhibited the basal rate of denitrification. These data demonstrate that several aromatic compounds are degraded under denitrifying conditions, but rates of biodegradation may be lower in material contaminated with JP-4 jet fuel.

  7. Phosphorus removal and N₂O production in anaerobic/anoxic denitrifying phosphorus removal process: long-term impact of influent phosphorus concentration.

    PubMed

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

    2015-03-01

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

  8. Seasonal Patterns in Microbial Community Composition in Denitrifying Bioreactors Treating Subsurface Agricultural Drainage.

    PubMed

    Porter, Matthew D; Andrus, J Malia; Bartolerio, Nicholas A; Rodriguez, Luis F; Zhang, Yuanhui; Zilles, Julie L; Kent, Angela D

    2015-10-01

    Denitrifying bioreactors, consisting of water flow control structures and a woodchip-filled trench, are a promising approach for removing nitrate from agricultural subsurface or tile drainage systems. To better understand the seasonal dynamics and the ecological drivers of the microbial communities responsible for denitrification in these bioreactors, we employed microbial community "fingerprinting" techniques in a time-series examination of three denitrifying bioreactors over 2 years, looking at bacteria, fungi, and the denitrifier functional group responsible for the final step of complete denitrification. Our analysis revealed that microbial community composition responds to depth and seasonal variation in moisture content and inundation of the bioreactor media, as well as temperature. Using a geostatistical analysis approach, we observed recurring temporal patterns in bacterial and denitrifying bacterial community composition in these bioreactors, consistent with annual cycling. The fungal communities were more stable, having longer temporal autocorrelations, and did not show significant annual cycling. These results suggest a recurring seasonal cycle in the denitrifying bioreactor microbial community, likely due to seasonal variation in moisture content.

  9. Impact of Land Use Management and Soil Properties on Denitrifier Communities of Namibian Savannas.

    PubMed

    Braker, Gesche; Matthies, Diethart; Hannig, Michael; Brandt, Franziska Barbara; Brenzinger, Kristof; Gröngröft, Alexander

    2015-11-01

    We studied potential denitrification activity and the underlying denitrifier communities in soils from a semiarid savanna ecosystem of the Kavango region in NE Namibia to help in predicting future changes in N(2)O emissions due to continuing changes of land use in this region. Soil type and land use (pristine, fallow, and cultivated soils) influenced physicochemical characteristics of the soils that are relevant to denitrification activity and N(2)O fluxes from soils and affected potential denitrification activity. Potential denitrification activity was assessed by using the denitrifier enzyme activity (DEA) assay as a proxy for denitrification activity in the soil. Soil type and land use influenced C and N contents of the soils. Pristine soils that had never been cultivated had a particularly high C content. Cultivation reduced soil C content and the abundance of denitrifiers and changed the composition of the denitrifier communities. DEA was strongly and positively correlated with soil C content and was higher in pristine than in fallow or recently cultivated soils. Soil type and the composition of both the nirK- and nirS-type denitrifier communities also influenced DEA. In contrast, other soil characteristics like N content, C:N ratio, and pH did not predict DEA. These findings suggest that due to greater availability of soil organic matter, and hence a more effective N cycling, the natural semiarid grasslands emit more N(2)O than managed lands in Namibia.

  10. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  11. Implementation of Aerobic Programs.

    ERIC Educational Resources Information Center

    American Alliance for Health, Physical Education, Recreation and Dance (AAHPERD).

    This information is intended for health professionals interested in implementing aerobic exercise programs in public schools, institutions of higher learning, and business and industry workplaces. The papers are divided into three general sections. The introductory section presents a basis for adhering to a health fitness lifestyle, using…

  12. Aerobic Anoxygenic Phototrophic Bacteria

    PubMed Central

    Yurkov, Vladimir V.; Beatty, J. Thomas

    1998-01-01

    The aerobic anoxygenic phototrophic bacteria are a relatively recently discovered bacterial group. Although taxonomically and phylogenetically heterogeneous, these bacteria share the following distinguishing features: the presence of bacteriochlorophyll a incorporated into reaction center and light-harvesting complexes, low levels of the photosynthetic unit in cells, an abundance of carotenoids, a strong inhibition by light of bacteriochlorophyll synthesis, and the inability to grow photosynthetically under anaerobic conditions. Aerobic anoxygenic phototrophic bacteria are classified in two marine (Erythrobacter and Roseobacter) and six freshwater (Acidiphilium, Erythromicrobium, Erythromonas, Porphyrobacter, Roseococcus, and Sandaracinobacter) genera, which phylogenetically belong to the α-1, α-3, and α-4 subclasses of the class Proteobacteria. Despite this phylogenetic information, the evolution and ancestry of their photosynthetic properties are unclear. We discuss several current proposals for the evolutionary origin of aerobic phototrophic bacteria. The closest phylogenetic relatives of aerobic phototrophic bacteria include facultatively anaerobic purple nonsulfur phototrophic bacteria. Since these two bacterial groups share many properties, yet have significant differences, we compare and contrast their physiology, with an emphasis on morphology and photosynthetic and other metabolic processes. PMID:9729607

  13. Aerobic Dance in Public Schools.

    ERIC Educational Resources Information Center

    Chiles, Barbara Ann; Moore, Suzanne

    1981-01-01

    Aerobic dance offers a challenging workout in a social atmosphere. Though some physical education instructors tend to exclude dance units from the curriculum, most could teach aerobic dance if they had a basic knowledge of aerobic routines. The outline for a unit to be used in the class is presented. (JN)

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

    PubMed

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

    2011-01-01

    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.

  15. Simultaneous nitrification and denitrification by EPSs in aerobic granular sludge enhanced nitrogen removal of ammonium-nitrogen-rich wastewater.

    PubMed

    Yan, Lilong; Zhang, Shaoliang; Hao, Guoxin; Zhang, Xiaolei; Ren, Yuan; Wen, Yan; Guo, Yihan; Zhang, Ying

    2016-02-01

    In this study, role of extracellular polymeric substances (EPSs) in enhancing nitrogen-removal from ammonium-nitrogen-rich wastewater using aerobic granular sludge (AGS) technology were analyzed. AGS enabled ammonium oxidation and denitrification to occur simultaneously. Air stripping and simultaneous nitrification-denitrification contributed to total-nitrogen removal. Clone-library analysis revealed that close relatives of Nitrosomonas eutropha and heterotrophic denitrifiers were dominant in the AGS, whereas anammox bacteria were not detected. EPSs adsorption of ammonium, nitrite, and nitrate nitrogen results in improved removal of nitrogen in batch experiments.

  16. Environmental controls on denitrifying communities and denitrification rates--Insights from molecular methods

    USGS Publications Warehouse

    Wallenstein, Matthew D.; Myrold, David D.; Firestone, Mary; Voytek, Mary

    2006-01-01

    The advent of molecular techniques has improved our understanding of the microbial communities responsible for denitrification and is beginning to address their role in controlling denitrification processes. There is a large diversity of bacteria, archaea, and fungi capable of denitrification, and their community composition is structured by long-term environmental drivers. The range of temperature and moisture conditions, substrate availability, competition, and disturbances have long-lasting legacies on denitrifier community structure. These communities may differ in physiology, environmental tolerances to pH and O2, growth rate, and enzyme kinetics. Although factors such as O2, pH, C availability, and NO3− pools affect instantaneous rates, these drivers act through the biotic community. This review summarizes the results of molecular investigations of denitrifier communities in natural environments and provides a framework for developing future research for addressing connections between denitrifier community structure and function.

  17. Carbon amendment and soil depth affect the distribution and abundance of denitrifiers in agricultural soils.

    PubMed

    Barrett, M; Khalil, M I; Jahangir, M M R; Lee, C; Cardenas, L M; Collins, G; Richards, K G; O'Flaherty, V

    2016-04-01

    The nitrite reductase (nirS and nirK) and nitrous oxide reductase-encoding (nosZ) genes of denitrifying populations present in an agricultural grassland soil were quantified using real-time polymerase chain reaction (PCR) assays. Samples from three separate pedological depths at the chosen site were investigated: horizon A (0-10 cm), horizon B (45-55 cm), and horizon C (120-130 cm). The effect of carbon addition (treatment 1, control; treatment 2, glucose-C; treatment 3, dissolved organic carbon (DOC)) on denitrifier gene abundance and N2O and N2 fluxes was determined. In general, denitrifier abundance correlated well with flux measurements; nirS was positively correlated with N2O, and nosZ was positively correlated with N2 (P < 0.03). Denitrifier gene copy concentrations per gram of soil (GCC) varied in response to carbon type amendment (P < 0.01). Denitrifier GCCs were high (ca. 10(7)) and the bac:nirK, bac:nirS, bac:nir (T) , and bac:nosZ ratios were low (ca. 10(-1)/10) in horizon A in all three respective treatments. Glucose-C amendment favored partial denitrification, resulting in higher nir abundance and higher N2O fluxes compared to the control. DOC amendment, by contrast, resulted in relatively higher nosZ abundance and N2 emissions, thus favoring complete denitrification. We also noted soil depth directly affected bacterial, archaeal, and denitrifier abundance, possibly due to changes in soil carbon availability with depth.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  19. Biodegradation of a surrogate naphthenic acid under denitrifying conditions.

    PubMed

    Gunawan, Yetty; Nemati, Mehdi; Dalai, Ajay

    2014-03-15

    Extraction of bitumen from the shallow oil sands generates extremely large volumes of waters contaminated by naphthenic acid which pose severe environmental and ecological risks. Aerobic biodegradation of NA in properly designed bioreactors has been investigated in our earlier works. In the present work, anoxic biodegradation of trans-4-methyl-1-cyclohexane carboxylic acid (trans-4MCHCA) coupled to denitrification was investigated as a potential ex situ approach for the treatment of oil sand process waters in bioreactors whereby excessive aeration cost could be eliminated, or as an in situ alternative for the treatment of these waters in anoxic stabilization ponds amended with nitrate. Using batch and continuous reactors (CSTR and biofilm), effects of NA concentration (100-750mgL(-1)), NA loading rate (up to 2607.9mgL(-1)h(-1)) and temperature (10-35°C) on biodegradation and denitrification processes were evaluated. In the batch system biodegradation of trans-4MCHCA coupled to denitrification occurred even at the highest concentration of 750mgL(-1). Consistent with the patterns reported for aerobic biodegradation, increase in initial concentration of NA led to higher biodegradation and denitrification rates and the optimum temperature was determined as 23-24°C. In the CSTR, NA removal and nitrate reduction rates passed through a maximum due to increases in NA loading rate. NA loading rate of 157.8mgL(-1)h(-1) at which maximum anoxic NA and nitrate removal rates (105.3mgL(-1)h(-1) and 144.5mgL(-1)h(-1), respectively) occurred was much higher than those reported for the aerobic alternative (NA loading and removal rates: 14.2 and 9.6mgL(-1)h(-1), respectively). In the anoxic biofilm reactor removal rates of NA and nitrate were dependent on NA loading rate in a linear fashion for the entire range of applied loading rates. The highest loading and removal rates for NA were 2607.9 and 2028.1mgL(-1)h(-1), respectively which were at least twofold higher than the values

  20. [Isolation and identification of electrochemically active microorganism from micro-aerobic environment].

    PubMed

    Wu, Song; Xiao, Yong; Zheng, Zhi-Yong; Zheng, Yue; Yang, Zhao-Hui; Zhao, Feng

    2014-10-01

    Extracellular electron transfer of electrochemically active microorganism plays vital role in biogeochemical cycling of metals and carbon and in biosynthesis of bioenergy. Compared to anaerobic anode, micro-aerobic anode captures more energy from microbial fuel cell. However, most of previous researches focused on functioning bacteria in anaerobic anode, functioning bacteria in micro-aerobic anode was rarely studied. Herein, we used the traditional aerobic screening technology to isolate functioning bacteria from a micro-aerobic anode. Three pure cultures Aeromonas sp. WS-XY2, Citrobacter sp. WS-XY3 and Bacterium strain WS-XY4 were obtained. WS-XY2 and WS-XY3 were belonged to Proteobacteria, whereas WS-XY4 was possibly a new species. Cyclic voltammetry and chronoamperometry analysis demonstrated all of them showed the electrochemical activity by direct extracellular electron transfer, and micro-aerobic anode could select bacteria that have similar electrochemical activity to proliferate on the anode. We further conclude that functioning bacteria in micro-aerobic anode are more efficient than that of anaerobic anode may be the reason that micro-aerobic anode has better performance than anaerobic anode. Therefore, a thorough study of functioning bacteria in micro-aerobic anode will significantly promote the energy recovery from microbial fuel cell.

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

    PubMed

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

    2016-07-01

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

  2. Biodegradation of Asphalt Cement-20 by Aerobic Bacteria

    PubMed Central

    Pendrys, John P.

    1989-01-01

    Seven gram-negative, aerobic bacteria were isolated from a mixed culture enriched for asphalt-degrading bacteria. The predominant genera of these isolates were Pseudomonas, Acinetobacter, Alcaligenes, Flavimonas, and Flavobacterium. The mixed culture preferentially degraded the saturate and naphthene aromatic fractions of asphalt cement-20. A residue remained on the surface which was resistant to biodegradation and protected the underlying asphalt from biodegradation. The most potent asphalt-degrading bacterium, Acinetobacter calcoaceticus NAV2, excretes an emulsifier which is capable of emulsifying the saturate and naphthene aromatic fractions of asphalt cement-20. This emulsifier is not denatured by phenol. PMID:16347928

  3. Microbial community composition and denitrifying enzyme activities in salt marsh sediments.

    PubMed

    Cao, Yiping; Green, Peter G; Holden, Patricia A

    2008-12-01

    Denitrifying microbial communities and denitrification in salt marsh sediments may be affected by many factors, including environmental conditions, nutrient availability, and levels of pollutants. The objective of this study was to examine how microbial community composition and denitrification enzyme activities (DEA) at a California salt marsh with high nutrient loading vary with such factors. Sediments were sampled from three elevations, each with different inundation and vegetation patterns, across 12 stations representing various salinity and nutrient conditions. Analyses included determination of cell abundance, total and denitrifier community compositions (by terminal restriction fragment length polymorphism), DEA, nutrients, and eluted metals. Total bacterial (16S rRNA) and denitrifier (nirS) community compositions and DEA were analyzed for their relationships to environmental variables and metal concentrations via multivariate direct gradient and regression analyses, respectively. Community composition and DEA were highly variable within the dynamic salt marsh system, but each was strongly affected by elevation (i.e., degree of inundation) and carbon content as well as by selected metals. Carbon content was highly related to elevation, and the relationships between DEA and carbon content were found to be elevation specific when evaluated across the entire marsh. There were also lateral gradients in the marsh, as evidenced by an even stronger association between community composition and elevation for a marsh subsystem. Lastly, though correlated with similar environmental factors and selected metals, denitrifier community composition and function appeared uncoupled in the marsh.

  4. Expression of Bradyrhizobium japonicum cbb(3) terminal oxidase under denitrifying conditions is subjected to redox control.

    PubMed

    Bueno, Emilio; Richardson, David J; Bedmar, Eulogio J; Delgado, María J

    2009-09-01

    Bradyrhizobium japonicum utilizes cytochrome cbb(3) oxidase encoded by the fixNOQP operon to support microaerobic respiration under free-living and symbiotic conditions. It has been previously shown that, under denitrifying conditions, inactivation of the cycA gene encoding cytochrome c(550), the electron donor to the Cu-containing nitrite reductase, reduces cbb(3) expression. In order to establish the role of c(550) in electron transport to the cbb(3) oxidase, in this work, we have analyzed cbb(3) expression and activity in the cycA mutant grown under microaerobic or denitrifying conditions. Under denitrifying conditions, mutation of cycA had a negative effect on cytochrome c oxidase activity, heme c (FixP and FixO) and heme b cytochromes as well as expression of a fixP'-'lacZ fusion. Similarly, cbb(3) oxidase was expressed very weakly in a napC mutant lacking the c-type cytochrome, which transfers electrons to the NapAB structural subunit of the periplasmic nitrate reductase. These results suggest that a change in the electron flow through the denitrification pathway may affect the cellular redox state, leading to alterations in cbb(3) expression. In fact, levels of fixP'-'lacZ expression were largely dependent on the oxidized or reduced nature of the carbon source in the medium. Maximal expression observed in cells grown under denitrifying conditions with an oxidized carbon source required the regulatory protein RegR.

  5. EFFECTS OF MICROCOSM PREPARATION ON RATES OF TOLUENE BIODEGRADATION UNDER DENITRIFYING CONDITIONS

    EPA Science Inventory

    Microcosms were prepared with subsurface material from two aquifers to examine the effects of preparation methods on rates of toluene biodegradation under denitrifying conditions. In both cases, the data fit a zero-order kinetics plot. However, rates of removal were generally pro...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. Denitrifying Bioreactors – An Approach for Reducing Nitrate Loads to Receiving Waters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low-cost and simple technologies are needed to reduce watershed export of excess nitrogen to sensitive aquatic ecosystems. Denitrifying bioreactors are an approach where solid carbon substrates are added into the flow path of contaminated water. These carbon substrates (often fragmented wood-product...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    PubMed Central

    Lipsewers, Yvonne A.; Hopmans, Ellen C.; Meysman, Filip J. R.; Sinninghe Damsté, Jaap S.; Villanueva, Laura

    2016-01-01

    Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers, and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen-, and sulfur cycling in Lake Grevelingen sediments. PMID:27812355

  10. Draft Genome Sequence of Pseudomonas frederiksbergensis SI8, a Psychrotrophic Aromatic-Degrading Bacterium

    PubMed Central

    Brown, Lisa M.; Striebich, Richard C.; Mueller, Susan S.; Gunasekera, Thusitha S.

    2015-01-01

    Pseudomonas frederiksbergensis strain SI8 is a psychrotrophic bacterium capable of efficient aerobic degradation of aromatic hydrocarbons. The draft genome of P. frederiksbergensis SI8 is 6.57 Mb in size, with 5,904 coding sequences and 60.5% G+C content. The isopropylbenzene (cumene) degradation pathway is predicted to be present in P. frederiksbergensis SI8. PMID:26184950

  11. Draft Genome Sequence of Agarivorans albus Strain MKT 106T, an Agarolytic Marine Bacterium.

    PubMed

    Yasuike, Motoshige; Nakamura, Yoji; Kai, Wataru; Fujiwara, Atushi; Fukui, Youhei; Satomi, Masataka; Sano, Motohiko

    2013-07-18

    Agarivorans albus is a Gram-negative, strictly aerobic, and agar-hydrolyzing marine bacterium. We present the draft genome sequence of the A. albus strain MKT 106(T), which is composed of 67 contigs (>500 bp) totaling 4,734,285 bp and containing 4,397 coding DNA sequences (CDSs), four rRNAs, and 64 tRNA sequences.

  12. Draft Genome Sequence of Gordonia sihwensis Strain 9, a Branched Alkane-Degrading Bacterium

    PubMed Central

    Brown, Lisa M.; Gunasekera, Thusitha S.; Striebich, Richard C.

    2016-01-01

    Gordonia sihwensis strain 9 is a Gram-positive bacterium capable of efficient aerobic degradation of branched and normal alkanes. The draft genome of G. sihwensis S9 is 4.16 Mb in size, with 3,686 coding sequences and 68.1% G+C content. Alkane monooxygenase and P-450 cytochrome genes required for alkane degradation are predicted in G. sihwensis S9. PMID:27340079

  13. Soil denitrifier community size changes with land use change to perennial bioenergy cropping systems

    NASA Astrophysics Data System (ADS)

    Thompson, Karen A.; Deen, Bill; Dunfield, Kari E.

    2016-10-01

    Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn-soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus, on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn-soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n  =  30), with miscanthus and switchgrass grown alongside corn-soybean rotations at different N rates (0 and 160 kg N ha-1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011 to 2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA) and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn-soybean rotations regardless of management, indicating large-scale LUC from corn-soybean to miscanthus may be suitable in variable Ontario climatic conditions and under varied management, while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRNA) and denitrifying bacterial communities changed differently over time and in response to LUC, indicating varying controls on these communities.

  14. Aerobic landfill bioreactor

    SciTech Connect

    Hudgins, Mark P; Bessette, Bernard J; March, John; McComb, Scott T.

    2000-01-01

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  15. Aerobic landfill bioreactor

    SciTech Connect

    Hudgins, Mark P; Bessette, Bernard J; March, John C; McComb, Scott T.

    2002-01-01

    The present invention includes a system of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  16. Aerobic landfill bioreactor

    SciTech Connect

    Hudgins, M.P.; Bessette, B.J.; March, J.; McComb, S.T.

    2000-02-15

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120 F and 140 F in steady state.

  17. Anaerobic Degradation of Cyanuric Acid, Cysteine, and Atrazine by a Facultative Anaerobic Bacterium

    PubMed Central

    Jessee, J. A.; Benoit, R. E.; Hendricks, A. C.; Allen, G. C.; Neal, J. L.

    1983-01-01

    A facultative anaerobic bacterium that rapidly degrades cyanuric acid (CA) was isolated from the sediment of a stream that received industrial wastewater effluent. CA decomposition was measured throughout the growth cycle by using a high-performance liquid chromatography assay, and the concomitant production of ammonia was also measured. The bacterium used CA or cysteine as a major, if not the sole, carbon and energy source under anaerobic, but not aerobic, conditions in a defined medium. The cell yield was greatly enhanced by the simultaneous presence of cysteine and CA in the medium. Cysteine was preferentially used rather than CA early in the growth cycle, but all of the CA was used without an apparent lag after the cysteine was metabolized. Atrazine was also degraded by this bacterium under anaerobic conditions in a defined medium. PMID:16346187

  18. Single Bacterium Detection Using Sers

    NASA Astrophysics Data System (ADS)

    Gonchukov, S. A.; Baikova, T. V.; Alushin, M. V.; Svistunova, T. S.; Minaeva, S. A.; Ionin, A. A.; Kudryashov, S. I.; Saraeva, I. N.; Zayarny, D. A.

    2016-02-01

    This work is devoted to the study of a single Staphylococcus aureus bacterium detection using surface-enhanced Raman spectroscopy (SERS) and resonant Raman spectroscopy (RS). It was shown that SERS allows increasing sensitivity of predominantly low frequency lines connected with the vibrations of Amide, Proteins and DNA. At the same time the lines of carotenoids inherent to this kind of bacterium are well-detected due to the resonance Raman scattering mechanism. The reproducibility and stability of Raman spectra strongly depend on the characteristics of nanostructured substrate, and molecular structure and size of the tested biological object.

  19. Exercise, Animal Aerobics, and Interpretation?

    ERIC Educational Resources Information Center

    Oliver, Valerie

    1996-01-01

    Describes an aerobic activity set to music for children that mimics animal movements. Example exercises include walking like a penguin or jumping like a cricket. Stresses basic aerobic principles and designing the program at the level of children's motor skills. Benefits include reaching people who normally don't visit nature centers, and bridging…

  20. Novel P450nor Gene Detection Assay Used To Characterize the Prevalence and Diversity of Soil Fungal Denitrifiers

    PubMed Central

    Novinscak, Amy; Goyer, Claudia; Zebarth, Bernie J.; Burton, David L.; Chantigny, Martin H.

    2016-01-01

    ABSTRACT Denitrifying fungi produce nitrous oxide (N2O), a potent greenhouse gas, as they generally lack the ability to convert N2O to dinitrogen. Contrary to the case for bacterial denitrifiers, the prevalence and diversity of denitrifying fungi found in the environment are not well characterized. In this study, denitrifying fungi were isolated from various soil ecosystems, and novel PCR primers targeting the P450nor gene, encoding the enzyme responsible for the conversion of nitric oxide to N2O, were developed, validated, and used to study the diversity of cultivable fungal denitrifiers. This PCR assay was also used to detect P450nor genes directly from environmental soil samples. Fungal denitrification capabilities were further validated using an N2O gas detection assay and a PCR assay targeting the nirK gene. A collection of 492 facultative anaerobic fungi was isolated from 15 soil ecosystems and taxonomically identified by sequencing the internal transcribed spacer sequence. Twenty-seven fungal denitrifiers belonging to 10 genera had the P450nor and the nirK genes and produced N2O from nitrite. N2O production is reported in strains not commonly known as denitrifiers, such as Byssochlamys nivea, Volutella ciliata, Chloridium spp., and Trichocladium spp. The prevalence of fungal denitrifiers did not follow a soil ecosystem distribution; however, a higher diversity was observed in compost and agricultural soils. The phylogenetic trees constructed using partial P450nor and nirK gene sequences revealed that both genes clustered taxonomically closely related strains together. IMPORTANCE A PCR assay targeting the P450nor gene involved in fungal denitrification was developed and validated. The newly developed P450nor primers were used on fungal DNA extracted from a collection of fungi isolated from various soil environments and on DNA directly extracted from soil. The results indicated that approximatively 25% of all isolated fungi possessed this gene and were able to

  1. Response of Spatial Patterns of Denitrifying Bacteria Communities to Water Properties in the Stream Inlets at Dianchi Lake, China

    PubMed Central

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Wang, Yan; Liu, Xinhong; Zhang, Li; Yan, Shaohua

    2015-01-01

    Streams are an important sink for anthropogenic N owing to their hydrological connections with terrestrial systems, but main factors influencing the community structure and abundance of denitrifiers in stream water remain unclear. To elucidate the potential impact of varying water properties of different streams on denitrifiers, the abundance and community of three denitrifying genes coding for nitrite (nirK, nirS) and nitrous oxide (nosZ) reductase were investigated in 11 streams inlets at the north part of Dianchi Lake. The DGGE results showed the significant pairwise differences in community structure of nirK, nirS, and nosZ genes among different streams. The results of redundancy analysis (RDA) confirmed that nitrogen and phosphorus concentrations, pH, and temperature in waters were the main environmental factors leading to a significant alteration in the community structure of denitrifiers among different streams. The denitrifying community size was assessed by quantitative PCR (qPCR) of the nirS, nirK, and nosZ genes. The abundance of nirK, nirS, and nosZ was positively associated with concentrations of total N (TN) and PO43− (p < 0.001). The difference in spatial patterns between nirK and nirS community diversity, in combination with the spatial distribution of the nirS/nirK ratio, indicated the occurrence of habitat selection for these two types of denitrifiers in the different streams. The results indicated that the varying of N species and PO43− together with pH and temperature would be the main factors shaping the community structure of denitrifiers. Meanwhile, the levels of N in water, together with PO43−, tend to affect the abundance of denitrifiers. PMID:26504771

  2. Characteristics of ammonium removal by heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis No. 4.

    PubMed

    Joo, Hung-Soo; Hirai, Mitsuyo; Shoda, Makoto

    2005-08-01

    Alcaligenes faecalis no. 4 has heterotrophic nitrification and aerobic denitrification abilities. By taking the nitrogen balance under different culture conditions, 40-50% of removed NH4+-N was denitrified and about one-half of removed NH4+-N was converted to intracellular nitrogen. The maximum ammonium removal rate of no. 4 (28.9 mg-N/l/h) and its denitrification rate at high-strength NH4+-N of about 1200 ppm in aerated batch experiments at a C/N ratio of 10 were 5-40 times higher than those of other bacteria with the same ability. Only a few percent of the removed ammonium was converted to nitrite, and the main denitrification process was speculated to be via hydroxylamine which was produced by ammonium oxidation.

  3. Isotopic evidence for an aerobic nitrogen cycle in the latest Archean.

    PubMed

    Garvin, Jessica; Buick, Roger; Anbar, Ariel D; Arnold, Gail L; Kaufman, Alan J

    2009-02-20

    The nitrogen cycle provides essential nutrients to the biosphere, but its antiquity in modern form is unclear. In a drill core though homogeneous organic-rich shale in the 2.5-billion-year-old Mount McRae Shale, Australia, nitrogen isotope values vary from +1.0 to +7.5 per mil (per thousand) and back to +2.5 per thousand over approximately 30 meters. These changes evidently record a transient departure from a largely anaerobic to an aerobic nitrogen cycle complete with nitrification and denitrification. Complementary molybdenum abundance and sulfur isotopic values suggest that nitrification occurred in response to a small increase in surface-ocean oxygenation. These data imply that nitrifying and denitrifying microbes had already evolved by the late Archean and were present before oxygen first began to accumulate in the atmosphere.

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

    PubMed

    Kampman, Christel; Piai, Laura; Hendrickx, Tim L G; Temmink, Hardy; Zeeman, Grietje; Buisman, Cees J N

    2014-01-01

    The activity of denitrifying methanotrophic bacteria at 11-30 °C was assessed in short-term experiments. The aim was to determine the feasibility of applying denitrifying methanotrophic bacteria in low-temperature anaerobic wastewater treatment. This study showed that biomass enriched at 21 °C had an optimum temperature of 20-25 °C and that activity dropped as temperature was increased to 30 °C. Biomass enriched at 30 °C had an optimum temperature of 25-30 °C. These results indicated that biomass from low-temperature inocula adjusted to the enrichment temperature and that low-temperature enrichment is suitable for applications in low-temperature wastewater treatment. Biomass growth at ≤20 °C still needs to be studied.

  5. Taxis response of various denitrifying bacteria to nitrate and nitrite.

    PubMed

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

    2002-05-01

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

  6. Taxis Response of Various Denitrifying Bacteria to Nitrate and Nitrite

    PubMed Central

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

    2002-01-01

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

  7. Soil nitrifying and denitrifying capacities are altered by global change factors in a California annual grassland

    NASA Astrophysics Data System (ADS)

    Niboyet, A.; Le Roux, X.; Barthes, L.; Hungate, B.; Dijkstra, P.; Blankinship, J. C.; Brown, J. R.; Field, C. B.; Leadley, P. W.

    2009-12-01

    Nitrification and denitrification are key mediators of nitrogen (N) cycling, especially N losses, in terrestrial ecosystems, yet little is known about the long-term, in situ responses of these two microbial processes to the simultaneous and interacting global changes likely to occur this century. We investigated the responses of the two steps of nitrification - ammonia oxidation and nitrite oxidation - and of denitrification to the interactive effects of elevated CO2, warming, increased precipitation and N deposition as part of the Jasper Ridge Global Change Experiment. We followed these responses over two growing seasons of the experiment using measures of potential rates of ammonia oxidation, nitrite oxidation, and denitrification, along with key correlates of these activities (gross N mineralization, gross nitrification, soil moisture, soil NH4+ and NO3- concentrations, soil pH, soil temperature, soil CO2 and N2O effluxes, and root and shoot biomass). Across all dates, soil ammonia and nitrite oxidizing capacities responded very differently to global change treatments: soil ammonia oxidizing capacities were increased by 59% in the high N deposition treatment (likely as a result of higher substrate availability for ammonia-oxidizers), while soil nitrite oxidizing capacities did not respond to the N deposition treatment but were reduced by 10% in the increased precipitation treatment. Soil denitrifying capacities were increased by 26% in the high N deposition treatment (likely as a result of higher substrate availability for denitrifiers) and by 15% in the increased precipitation treatment (likely as a result of higher soil water content). Overall, elevated CO2 and warming were found to have little effects on soil nitrifying and denitrifying capacities, and interactive effects between global change components were rare when analyzed across multiple sampling dates. Thus, our results suggest that increased atmospheric N deposition and changes in precipitation

  8. Utilization of alkylbenzenes during anaerobic growth of pure cultures of denitrifying bacteria on crude oil

    SciTech Connect

    Rabus, R.; Widdel, F.

    1996-04-01

    Leakage from oil pipelines and underground fuel tanks may result in contamination of soils and deeper horizons. Even though the equilibrium partitioning of BTEX (benzene, toluene, ethylbenzene, and xylenes) between oil and water is largely on the side of the hydrophobic phase, BTEX exhibit a certain water solubility higher than other oil hydrocarbons. This study evaluates the growth of four strains of denitrifying bacteria on crude oil and the resulting, strain-specific depletion of alkylbenzenes.

  9. Algal exudates and stream organic matter influence the structure and function of denitrifying bacterial communities.

    PubMed

    Kalscheur, Kathryn N; Rojas, Miguel; Peterson, Christopher G; Kelly, John J; Gray, Kimberly A

    2012-11-01

    Within aquatic ecosystems, periphytic biofilms can be hot spots of denitrification, and previous work has suggested that algal taxa within periphyton can influence the species composition and activity of resident denitrifying bacteria. This study tested the hypothesis that algal species composition within biofilms influences the structure and function of associated denitrifying bacterial communities through the composition of organic exudates. A mixed population of bacteria was incubated with organic carbon isolated from one of seven algal species or from one of two streams that differed in anthropogenic inputs. Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) revealed differences in the organic composition of algal exudates and stream waters, which, in turn, selected for distinct bacterial communities. Organic carbon source had a significant effect on potential denitrification rates (DNP) of the communities, with organics isolated from a stream with high anthropogenic inputs resulting in a bacterial community with the highest DNP. There was no correlation between DNP and numbers of denitrifiers (based on nirS copy numbers), but there was a strong relationship between the species composition of denitrifier communities (as indicated by tag pyrosequencing of nosZ genes) and DNP. Specifically, the relative abundance of Pseudomonas stutzeri-like nosZ sequences across treatments correlated significantly with DNP, and bacterial communities incubated with organic carbon from the stream with high anthropogenic inputs had the highest relative abundance of P. stutzeri-like nosZ sequences. These results demonstrate a significant relationship between bacterial community composition and function and provide evidence of the potential impacts of anthropogenic inputs on the structure and function of stream microbial communities.

  10. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils.

  11. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

    PubMed Central

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils. PMID:26739424

  12. Isolation and physiological characterization of psychrophilic denitrifying bacteria from permanently cold Arctic fjord sediments (Svalbard, Norway).

    PubMed

    Canion, Andy; Prakash, Om; Green, Stefan J; Jahnke, Linda; Kuypers, Marcel M M; Kostka, Joel E

    2013-05-01

    A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(3) -10(6) cells of psychrophilic nitrate-respiring bacteria g(-1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40°C demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15°C, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

  13. Isolation and Physiological Characterization of Psychrophilic Denitrifying Bacteria from Permanently Cold Arctic Fjord Sediments (Svalbard, Norway)

    NASA Technical Reports Server (NTRS)

    Canion, Andy; Prakash, Om; Green, Stefan J.; Jahnke, Linda; Kuypers, Marcel M. M.; Kostka, Joel E.

    2013-01-01

    A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(sup 3)-10(sup 6) cells of psychrophilic nitrate-respiring bacteria g(sup -1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40 degC demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15 degC, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

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

    PubMed

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

    2014-09-17

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

  15. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils.

    PubMed

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-07

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils.

  16. Savagea faecisuis gen. nov., sp. nov., a tylosin- and tetracycline-resistant bacterium isolated from a swine-manure storage pit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A polyphasic taxonomic study using morphological, biochemical, chemotaxonomic and molecular methods was performed on three strains of an unknown Gram-positive staining, nonspore-forming, motile aerobic rod-shaped bacterium resistant to tetracycline and tylosin isolated from a swine-manure storage pi...

  17. Draft Genome Sequence of Aeribacillus pallidus Strain 8m3, a Thermophilic Hydrocarbon-Oxidizing Bacterium Isolated from the Dagang Oil Field (China)

    PubMed Central

    Poltaraus, Andrey B.; Sokolova, Diyana S.; Grouzdev, Denis S.; Ivanov, Timophey M.; Malakho, Sophia G.; Korshunova, Alena V.; Rozanov, Aleksey S.; Tourova, Tatiyana P.

    2016-01-01

    The draft genome sequence of Aeribacillus pallidus strain 8m3, a thermophilic aerobic oil-oxidizing bacterium isolated from production water from the Dagang high-temperature oil field, China, is presented here. The genome is annotated to provide insights into the genomic and phenotypic diversity of the genus Aeribacillus. PMID:27284131

  18. The fate of a nitrobenzene-degrading bacterium in pharmaceutical wastewater treatment sludge.

    PubMed

    Ren, Yuan; Yang, Juan; Chen, Shaoyi

    2015-12-01

    This paper describes the fate of a nitrobenzene-degrading bacterium, Klebsiella oxytoca NBA-1, which was isolated from a pharmaceutical wastewater treatment facility. The 90-day survivability of strain NBA-1 after exposure to sludge under anaerobic and aerobic conditions was investigated. The bacterium was inoculated into sludge amended with glucose and p-chloronitrobenzene (p-CNB) to compare the bacterial community variations between the modified sludge and nitrobenzene amendment. The results showed that glucose had no obvious effect on nitrobenzene biodegradation in the co-metabolism process, regardless of the presence/absence of oxygen. When p-CNB was added under anaerobic conditions, the biodegradation rate of nitrobenzene remained unchanged although p-CNB inhibited the production of aniline. The diversity of the microbial community increased and NBA-1 continued to be one of the dominant strains. Under aerobic conditions, the degradation rate of both nitrobenzene and p-CNB was only 20% of that under anaerobic conditions. p-CNB had a toxic effect on the microorganisms in the sludge so that most of the DGGE (denaturing gradient gel electrophoresis) bands, including that of NBA-1, began to disappear under aerobic conditions after 90days of exposure. These data show that the bacterial community was stable under anaerobic conditions and the microorganisms, including NBA-1, were more resistant to the adverse environment.

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

    PubMed

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

    2015-11-01

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

  20. Effect of nitrogen and waterlogging on denitrifier gene abundance, community structure and activity in the rhizosphere of wheat.

    PubMed

    Hamonts, Kelly; Clough, Tim J; Stewart, Alison; Clinton, Peter W; Richardson, Alan E; Wakelin, Steven A; O'Callaghan, Maureen; Condron, Leo M

    2013-03-01

    Microbial denitrification plays a key role in determining the availability of soil nitrogen (N) to plants. However, factors influencing the structure and function of denitrifier communities in the rhizosphere remain unclear. Waterlogging can result in root anoxia and increased denitrification, leading to significant N loss from soil and potential nitrous oxide (N(2)O) emissions. This study investigated denitrifier gene abundance, community structure and activity in the rhizosphere of wheat in response to anoxia and N limitation. Denitrifier community structure in the rhizosphere differed from that in bulk soil, and denitrifier gene copy numbers (nirS, nirK, nosZ) and potential denitrification activity were greater in the rhizosphere. Anoxia and N limitation, and in particular a combination of both, reduced the magnitude of this effect on gene abundance (in particular nirS) and activity, with N limitation having greater impact than waterlogging in rhizosphere soil, in contrast to bulk soil where the impact of waterlogging was greater. Increased N supply to anoxic plants improved plant health and increased rhizosphere soil pH, which resulted in enhanced reduction of N(2)O. Both anoxia and N limitation significantly influenced the structure and function of denitrifier communities in the rhizosphere, with reduced root-derived carbon postulated to play an important role.

  1. Model based evaluation of a contaminant plume development under aerobic and anaerobic conditions in 2D bench-scale tank experiments.

    PubMed

    Ballarini, E; Beyer, C; Bauer, R D; Griebler, C; Bauer, S

    2014-06-01

    The influence of transverse mixing on competitive aerobic and anaerobic biodegradation of a hydrocarbon plume was investigated using a two-dimensional, bench-scale flow-through laboratory tank experiment. In the first part of the experiment aerobic degradation of increasing toluene concentrations was carried out by the aerobic strain Pseudomonas putida F1. Successively, ethylbenzene (injected as a mixture of unlabeled and fully deuterium-labeled isotopologues) substituted toluene; nitrate was added as additional electron acceptor and the anaerobic denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic /anaerobic conditions. The spatial distribution of anaerobic degradation was resolved by measurements of compound-specific stable isotope fractionation induced by the anaerobic strain as well as compound concentrations. A fully transient numerical reactive transport model was employed and calibrated using measurements of electron donors, acceptors and isotope fractionation. The aerobic phases of the experiment were successfully reproduced using a double Monod kinetic growth model and assuming an initial homogeneous distribution of P. putida F1. Investigation of the competitive degradation phase shows that the observed isotopic pattern cannot be explained by transverse mixing driven biodegradation only, but also depends on the inoculation process of the anaerobic strain. Transient concentrations of electron acceptors and donors are well reproduced by the model, showing its ability to simulate transient competitive biodegradation.

  2. Draft Genome Sequence of Nocardioides luteus Strain BAFB, an Alkane-Degrading Bacterium Isolated from JP-7-Polluted Soil

    PubMed Central

    Brown, Lisa M.; Gunasekera, Thusitha S.

    2017-01-01

    ABSTRACT Nocardioides luteus strain BAFB is a Gram-positive bacterium that efficiently degrades C8 to C11 alkanes aerobically. The draft genome of N. luteus BAFB is 5.76 Mb in size, with 5,358 coding sequences and 69.9% G+C content. The genes responsible for alkane degradation are present in this strain. PMID:28126947

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Nitrous oxide (N2O) fluxes from soils result from its production by nitrification and denitrification and reduction during denitrification. The structure of the denitrifying microbial community contributes to the control of net N2O fluxes. Although molecular techniques are promising for identifying the active community of N2O producers, there are few data until now because methods to explore gene expression of N2O production are laborious and disregard regulation of activity at the enzyme level. The isotopologue signatures of N2O including δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) have been used to estimate the contribution of partial processes to net N2O fluxes to the atmosphere. However, the use of this approach to study N2O dynamics in soils requires knowledge of isotopic signatures of N2O precursors and isotopologue fractionation factors (ɛ) of all processes of N2O production and consumption. In contrast to δ18O and δ15Nbulk, SP is independent of precursor signatures and hence is a promising parameter here. It is assumed that SP of produced N2O is almost exclusively controlled by the enzymatic isotope effects of NO reductases (NOR). These enzymes are known to be structurally different between certain classes of N2O producers with each class causing different isotope effects (Schmidt et al., 2004). The NH2OH-to-N2O step of nitrifiers and the NO3-to-N2O step of fungal denitrifiers are associated with large site-specific 15N effects with SP of 33 to 37 ‰ (Sutka et al., 2006, 2008) while the few tested species of gram-negative bacterial denitrifiers (cNOR group) exhibited low SP of -5 to 0‰ (Sutka et al., 2006; Toyoda et al., 2005). The aim of our study was to determine site-specific fractionation factors of the NO3-to-N2O step (ɛSP) for several species of denitrifiers representing each of the known NOR-types of bacteria, i.e. cNOR, q

  4. Feasibility of enhancing the DEnitrifying AMmonium OXidation (DEAMOX) process for nitrogen removal by seeding partial denitrification sludge.

    PubMed

    Cao, Shenbin; Peng, Yongzhen; Du, Rui; Wang, Shuying

    2016-04-01

    The recently proposed DEnitrifying AMmonium OXidation (DEAMOX) process combined anaerobic ammonia oxidation (ANAMMOX) with denitrification to convert nitrate to nitrite, which was a promising way for treating wastewater containing nitrate and ammonia. This study investigated the feasibility of establishing DEAMOX process by seeding partial denitrification sludge (NO3(-) → NO2(-)) using sodium acetate as an electron donor in a sequencing batch reactor. Results showed that the DEAMOX process was established successfully and operated stably in 114-days operation. The average effluent total nitrogen concentration was below 5 mg L(-1) and TN removal efficiency reached up to 97% at COD/NO3(-) ratio of 3.0 under initial NH4(+) concentration of 25 mg L(-1) and NO3(-) of 30 mg L(-1). It suggested that the presence of NO2(-) in the system supplied for ANAMMOX and the relatively long sludge retention time (SRT) for denitrifiers were attributed to commendable coexistence of ANAMMOX and denitrifying bacteria.

  5. Characteristics of self-alkalization in high-rate denitrifying automatic circulation (DAC) reactor fed with methanol and sodium acetate.

    PubMed

    Li, Wei; Zheng, Ping; Guo, Jun; Ji, Junyuan; Zhang, Meng; Zhang, Zonghe; Zhan, Enchao; Abbas, Ghulam

    2014-02-01

    Denitrification is a self-alkalization process. In this experiment, the characteristics of self-alkalization in high-rate heterotrophic denitrifying automatic circulation (DAC) reactor fed with methanol and sodium acetate were investigated, respectively. The results showed that, (1) The self-alkalization of high-rate denitrifying reactors was remarkably strong both with methanol and sodium acetate as carbon sources, while the effluent pH was much lower than the stoichiometric values and the malfunction from self-alkalization of denitrification was far less serious than expected. (2) The self-adaptation of the reactors was attributed to the neutralization of carbon dioxide (oxidization product of organic matter) and the self-adaptation of denitrifying sludge. The formation and discharge of calcium carbonate precipitates gave rise to lower effluent pH and alkalinity than the stoichiometric values.

  6. Selective Pressure of Temperature on Competition and Cross-Feeding within Denitrifying and Fermentative Microbial Communities

    PubMed Central

    Hanke, Anna; Berg, Jasmine; Hargesheimer, Theresa; Tegetmeyer, Halina E.; Sharp, Christine E.; Strous, Marc

    2016-01-01

    In coastal marine sediments, denitrification and fermentation are important processes in the anaerobic decomposition of organic matter. Microbial communities performing these two processes were enriched from tidal marine sediments in replicated, long term chemostat incubations at 10 and 25°C. Whereas denitrification rates at 25°C were more or less stable over time, at 10°C denitrification activity was unstable and could only be sustained either by repeatedly increasing the amount of carbon substrates provided or by repeatedly decreasing the dilution rate. Metagenomic and transcriptomic sequencing was performed at different time points and provisional whole genome sequences (WGS) and gene activities of abundant populations were compared across incubations. These analyses suggested that a temperature of 10°C selected for populations related to Vibrionales/Photobacterium that contributed to both fermentation (via pyruvate/formate lyase) and nitrous oxide reduction. At 25°C, denitrifying populations affiliated with Rhodobacteraceae were more abundant. The latter performed complete denitrification, and may have used carbon substrates produced by fermentative populations (cross-feeding). Overall, our results suggest that a mixture of competition—for substrates between fermentative and denitrifying populations, and for electrons between both pathways active within a single population –, and cross feeding—between fermentative and denitrifying populations—controlled the overall rate of denitrification. Temperature was shown to have a strong selective effect, not only on the populations performing either process, but also on the nature of their ecological interactions. Future research will show whether these results can be extrapolated to the natural environment. PMID:26779132

  7. Relating Phylogenetic and Functional Diversity among Denitrifiers and Quantifying their Capacity to Predict Community Functioning.

    PubMed

    Salles, Joana Falcão; Le Roux, Xavier; Poly, Franck

    2012-01-01

    Genetic diversity of phylogenetic or functional markers is widely used as a proxy of microbial diversity. However, it remains unclear to what extent functional diversity (FD), gene sequence diversity and community functioning are linked. For a range of denitrifying bacteria, we analyzed the relationships between (i) the similarity of functional traits evaluated from metabolic profiles (BIOLOG plates) or from N(2)O accumulation patterns on different carbon sources and (ii) the similarity of phylogenetic (16S rRNA gene) or functional (nir gene) markers. We also calculated different proxies for the diversity of denitrifier community based on taxa richness, phylogenetic (16S rRNA gene) or functional similarities (based either on metabolic profiles or N(2)O accumulation patterns), and evaluated their performance in inferring the functioning of assembled denitrifying communities. For individual strains, the variation in the 16S rRNA gene sequence was weakly correlated with the variation in metabolic patterns (ρ = 0.35) and was not related to N(2)O accumulation. The latter was correlated with the similarity of nitrite reductase residues. When nir genes were analyzed separately, the similarity in amino acids coded by the nirS genes was highly correlated with the observed patterns of N(2)O accumulation (ρ = 0.62), whereas nirK amino acid residues were unrelated to N(2)O accumulation. For bacterial assemblages, phylogenetic diversity (average similarity among species in a community) and mean community dissimilarity (average distance between species) calculated using 16S rRNA gene sequences, and FD measures associated with metabolic profiles, poorly predicted the variation in the functioning of assembled communities (≤15%). In contrast, the proxies of FD based on N(2)O accumulation patterns performed better and explained from 23 to 42% of the variation in denitrification. Amongst those, community niche was the best metric, indicating the importance of

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

    PubMed Central

    Song, Bongkeun; Ward, Bess B.

    2005-01-01

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

  9. Selective Pressure of Temperature on Competition and Cross-Feeding within Denitrifying and Fermentative Microbial Communities.

    PubMed

    Hanke, Anna; Berg, Jasmine; Hargesheimer, Theresa; Tegetmeyer, Halina E; Sharp, Christine E; Strous, Marc

    2015-01-01

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

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

    PubMed

    Christianson, Laura E; Schipper, Louis A

    2016-05-01

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

  11. Changes in Bacterial Denitrifier Community Abundance over Time in an Agricultural Field and Their Relationship with Denitrification Activity▿

    PubMed Central

    Dandie, Catherine E.; Burton, David L.; Zebarth, Bernie J.; Henderson, Sherri L.; Trevors, Jack T.; Goyer, Claudia

    2008-01-01

    This study measured total bacterial and denitrifier community abundances over time in an agricultural soil cropped to potatoes (Solanum tuberosum L.) by using quantitative PCR. Samples were collected on 10 dates from spring to autumn and from three spatial locations: in the potato “hill” between plants (H), close to the plant (Hp), and in the “furrow” (F). The denitrification rates, N2O emissions, and environmental parameters were also measured. Changes in denitrifier abundance over time and spatial location were small (1.7- to 2.7-fold for the nirK, nosZ, and cnorBB guilds), whereas the cnorBP community (Pseudomonas mandelii and closely related spp.) showed an ∼4.6-fold change. The seasonal patterns of denitrifier gene numbers varied with the specific community: lower nosZ gene numbers in April and May than in June and July, higher cnorBP gene numbers in May and June than in March and April and September and November, higher nirK gene numbers in early spring than in late autumn, and no change in cnorBB gene numbers. Gene numbers were higher for the Hp than the H location for the nosZ and nirK communities and for the cnorBP community on individual dates, presumably indicating an effect of the plant on denitrifier abundance. Higher cnorBP gene numbers for the H location than the F location and for nosZ and cnorBB on individual dates reflect the effect of spatial location on abundance. Denitrifier abundance changes were not related to any environmental parameter, although a weak relationship exists between cnorBP gene numbers, extractable organic carbon values, and temperature. Denitrification and N2O emissions were mostly regulated by inorganic nitrogen availability and water-filled pore space but were uncoupled from denitrifier community abundances measured in this system. PMID:18689522

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Nitrous oxide emissions from an aerobic granular sludge system treating low-strength ammonium wastewater.

    PubMed

    Gao, Mingming; Yang, Sen; Wang, Mingyu; Wang, Xin-Hua

    2016-11-01

    Aerobic granular sludge is a promising technology in wastewater treatment process. Its special microorganism structure could make the emissions of greenhouse gas nitrous oxide (N2O) more complicated. This study investigated the N2O emissions from a batch-fed aerobic granular sludge system during nitrification of low-strength synthetic ammonium wastewater. The N2O emission was 2.72 ± 0.52% of the oxidized ammonium during the whole anoxic-oxic sequencing batch reactor (SBR) cycle. Under nitrification batch test with sole ammonium substrate (50 mg N/L), N2O emission factor was 1.82% (N2ON/NH4(+)-Nox) and ammonia-oxidizing bacteria (AOB) was the responsible microorganism. The presence of high ammonium concentration (or high ammonium oxidation rate (AOR)) and accumulation of nitrite would lead to significant N2O emissions. AOB denitrification pathway was speculated to contribute more to the N2O emissions under nitrification conditions. While under simultaneous nitrification and denitrification condition with carbon source of 500 mg COD/L, the N2O emission factor increased to 2.76%. Both AOB and heterotrophic denitrifiers were responsible for N2O emission and heterotrophic denitrification enhances N2O emission. Step feeding of organic carbon source declined N2O emission factor to 1.60%, which underlined the role of storage substance consumption in N2O generation during denitrification.

  14. Nitrate and COD removal in an upflow biofilter under an aerobic atmosphere.

    PubMed

    Ji, Bin; Wang, Hongyu; Yang, Kai

    2014-04-01

    A continuous-upflow submerged biofilter packed with ceramsite was constructed for nitrate removal under an aerobic atmosphere. Pseudomonas stutzeri X31, an aerobic denitrifier isolate, was added to the bioreactor as an inoculum. The influent NO3(-)-N concentrations were 63.0-73.8 mg L(-1). The best results were achieved when dissolved oxygen level was 4.6 mg L(-1) and C/N ratio was 4.5. The maximum removal efficiencies of carbon oxygen demand (COD) and NO3(-)-N were 94.04% and 98.48%, respectively at 30°C, when the hydraulic load was 0.75 m h(-1). The top section of the bioreactor possessed less biofilm but higher COD and NO3(-)-N removal rates than the bottom section. Polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) technique combined with electron microscopic examination indicated P. stutzeri X31 and Paracoccus versutus were the most dominant bacteria. Amoeba sp., Vorticella sp., Philodina sp., and Stephanodiscus sp. were also found in the bioreactor.

  15. Distribution of nitrogenous nutrients and denitrifiers strains in estuarine sediment profiles of the Tanshui River, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Fan, L. F.; Shieh, W. Y.; Wu, W. F.; Chen, C.-P.

    2006-09-01

    Chemical profiles of both oxidized (nitrate and sulfate) and reduced (ammonium, sulfide, acid-volatile sulfide [AVS], and pyrite) materials and the corresponding distribution of denitrifier microbial communities were measured at low tide in sediments at Guandu in the estuary of the Tanshui River, northern Taiwan in August 2002. Denitrifier strains were isolated for physiological and phylogenic analyses. Based on the distribution of nitrogenous compounds and denitrifier abundances, the vertical profile of Guandu sediments could be separated into four layers: a mixed layer (the top 1 cm of depth, respectively containing 0.82-2.37 and 535.9-475.0 μM of nitrate and ammonium), a nitrate-concentrated layer (1-5 cm in depth, 2.37-0.53 and 475.0-1192.1 μM, respectively), a denitrifier-aggregation layer (5-7 cm in depth, 0.53-0.72 and 1192.1-1430.1 μM, respectively), and an ammonium-enriched layer (7-12 cm in depth, 0.72-0.78 and 1430.1-2196.6 μM, respectively). Denitrifier strains were detected in all layers except for the mixed layer. A variety of metabolic processes by these strains may occur in different layers. Bacillus jeotgali-, Bacillus sphaericus-, and Bacillus firmus-related strains isolated from the nitrate-concentrated layer may be involved in the nitrification-denitrification coupling process due to the relatively low nitrate concentrations (maximum = 2.37 μM), and may contribute to denitrification not nitrification. Bacillus bataviensis- and B. jeotgali-related strains isolated from the denitrifier-aggregation layer comprised the predominant denitrifier population (3.64 × 10 4 cells/g of denitrifier abundance). They possess the ability of dissimilatory nitrate reduction to ammonium (DNRA). Bacillus jeotgali-related strains and two newly identified strains of GD0705 and GD0706 isolated from the ammonium-enriched layer possibly use fermentative processes as the main metabolic pathway instead of denitrification when nitrate is scarce, and this further

  16. Die aerobe Glykolyse der Tumorzelle

    NASA Astrophysics Data System (ADS)

    Schneider, Friedhelm

    1981-01-01

    A high aerobic glycolysis (aerobic lactate production) is the most significant feature of the energy metabolism of rapidly growing tumor cells. Several mechanisms, which may be different in different cell lines, seem to be involved in this characteristic of energy metabolism of the tumor cell. Changes in the cell membrane leading to increased uptake and utilization of glucose, a high level of fetal types of isoenzymes, a decreased number of mitochondria and a reduced capacity to metabolize pyruvate are some factors which must be taken into consideration. It is not possible to favour one of them at the present time.

  17. "Bacillus hackensackii" sp. nov., a novel carbon dioxide sensitive bacterium isolated from blood culture.

    PubMed

    Hong, Tao; Heibler, Nueda; Tang, Y i-Wei

    2003-02-01

    An endospore-forming, gram-positive bacillus was isolated from a patient's blood culture. This bacillus did not grow in the presence of 5% carbon dioxide although it grew well in ambient air at 37 degrees C. Although the organism thus is an aerobic bacterium, its sensitivity to increased carbon dioxide concentration places it in a distinct category of gaseous atmospheric requirement: capnophobic. Based on its morphology, growth characteristics, biochemical reactions and a complete 16S rRNA gene nucleotide sequence analysis, this microorganism represents a novel Bacillus species. The clinical significance of this isolate is unknown. It is proposed that the bacterium be classified in the genus Bacillus as "Bacillus hackensackii".

  18. Study on EDTA-degrading bacterium Burkholderia cepacia YL-6 for bioaugmentation.

    PubMed

    Chen, Shih-Chin; Chen, Szu-Lin; Fang, Hung-Yuan

    2005-11-01

    Bioaugmentation production of EDTA-degrading bacterium Burkholderia cepacia YL-6 was carried out in an aerobic fermentor. Three different carbon sources (ferric-ethylenediaminetetraacetate (Fe-EDTA), potassium acetate, and ethylamine) were used. The bacterium cultivated with Fe-EDTA and maintained in the growth phase could reach the maximum cell concentration on the 38th day. Whereas, the bacterium cultivated with potassium acetate and ethylamine reach the maximum cell concentration at the 76th and 100th hour. The viable-cell counts of the augmentation agents made by feeding Fe-EDTA, potassium acetate, and ethylamine were 8.2x10(10), 6.8x10(11), and 4.3x10(11) CFU/g agent, respectively. The EDTA-degradation time required for the afore-mentioned bioaugmentation agents made by feeding various carbon sources lay in the following order: ethylaminebacterium B. cepacia YL-6.

  19. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  20. Exoelectrogenic bacterium phylogenetically related to Citrobacter freundii, isolated from anodic biofilm of a microbial fuel cell.

    PubMed

    Huang, Jianjian; Zhu, Nengwu; Cao, Yanlan; Peng, Yue; Wu, Pingxiao; Dong, Wenhao

    2015-02-01

    An electrogenic bacterium, named Citrobacter freundii Z7, was isolated from the anodic biofilm of microbial fuel cell (MFC) inoculated with aerobic sewage sludge. Cyclic voltammetry (CV) analysis exhibited that the strain Z7 had relatively high electrochemical activity. When the strain Z7 was inoculated into MFC, the maximum power density can reach 204.5 mW/m(2) using citrate as electron donor. Series of substrates including glucose, glycerol, lactose, sucrose, and rhammose could be utilized to generate power. CV tests and the addition of anode solution as well as AQDS experiments indicated that the strain Z7 might transfer electrons indirectly via secreted mediators.

  1. Complete Genome Sequence of the Filamentous Anoxygenic Phototrophic Bacterium Chloroflexus aurantiacus

    SciTech Connect

    Tang, Kuo-Hsiang; Barry, Kerrie; Chertkov, Olga; Dalin, Eileen; Han, Cliff; Hauser, Loren John; Honchak, Barbara M; Karbach, Lauren E; Land, Miriam L; Lapidus, Alla L.; Larimer, Frank W; Mikhailova, Natalia; Pitluck, Sam; Pierson, Beverly K

    2011-01-01

    Chloroflexus aurantiacus is a thermophilic filamentous anoxygenic phototrophic (FAP) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions. According to 16S rRNA analysis, Chloroflexi species are the earliest branching bacteria capable of photosynthesis, and Cfl. aurantiacus has been long regarded as a key organism to resolve the obscurity of the origin and early evolution of photosynthesis. Cfl. aurantiacus contains a chimeric photosystem that comprises some characters of green sulfur bacteria and purple photosynthetic bacteria, and also has some unique electron transport proteins compared to other photosynthetic bacteria.

  2. Community size and composition of ammonia oxidizers and denitrifiers in an alluvial intertidal wetland ecosystem

    PubMed Central

    Hu, Ziye; Meng, Han; Shi, Jin-Huan; Bu, Nai-Shun; Fang, Chang-Ming; Quan, Zhe-Xue

    2014-01-01

    Global nitrogen cycling is mainly mediated by the activity of microorganisms. Nitrogen cycle processes are mediated by functional groups of microorganisms that are affected by constantly changing environmental conditions and substrate availability. In this study, we investigated the temporal and spatial patterns of nitrifier and denitrifier communities in an intertidal wetland. Soil samples were collected over four distinct seasons from three locations with different vegetative cover. Multiple environmental factors and process rates were measured and analyzed together with the community size and composition profiles. We observed that the community size and composition of the nitrifiers and denitrifiers are affected significantly by seasonal factors, while vegetative cover affected the community composition. The seasonal impacts on the community size of ammonia oxidizing archaea (AOA) are much higher than that of ammonia oxidizing bacteria (AOB). The seasonal change was a more important indicator for AOA community composition patterns, while vegetation was more important for the AOB community patterns. The microbial process rates were correlated with both the community size and composition. PMID:25101072

  3. Autotrophic, hydrogen-oxidizing, denitrifying bacteria in groundwater, potential agents for bioremediation of nitrate contamination

    USGS Publications Warehouse

    Smith, R.L.; Ceazan, M.L.; Brooks, M.H.

    1994-01-01

    Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent K(m) of 0.45 to 0.60 ??M and a V(max) of 18.7 nmol cm-3 h-1 at 30??C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the K(m)s ranged from 0.30 to 3.32 ??M, with V(max)s of 1.85 to 13.29 fmol cell-1 h-1. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater.

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

    PubMed

    Weigelhofer, Gabriele; Hein, Thomas

    2015-09-01

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

  5. Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

    PubMed Central

    Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

    2016-01-01

    Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3–64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7–25.4%), Firmicutes (3.0–20.1%), Acidobacteria (2.7–15.7%), Actinobacteria (2.2–8.7%), Bacteroidetes (0.5–9.7%), and Verrucomicrobia (2.4–5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen. PMID:27782192

  6. Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

    NASA Astrophysics Data System (ADS)

    Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

    2016-10-01

    Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3–64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7–25.4%), Firmicutes (3.0–20.1%), Acidobacteria (2.7–15.7%), Actinobacteria (2.2–8.7%), Bacteroidetes (0.5–9.7%), and Verrucomicrobia (2.4–5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

  7. Simultaneous domestic wastewater and nitrate sewage treatment by DEnitrifying AMmonium OXidation (DEAMOX) in sequencing batch reactor.

    PubMed

    Du, Rui; Cao, Shenbin; Li, Baikun; Wang, Shuying; Peng, Yongzhen

    2017-05-01

    A novel DEAMOX system was developed for nitrogen removal from domestic wastewater and nitrate (NO3(-)-N) sewage in sequencing batch reactor (SBR). High nitrite (NO2(-)-N) was produced from NO3(-)-N reduction in partial-denitrification process, which served as electron acceptor for anammox and was removed with ammonia (NH4(+)-N) in domestic wastewater simultaneously. A 500-days operation demonstrated that the efficient and stable nitrogen removal performance could be achieved by DEAMOX. The total nitrogen (TN) removal efficiency was as high as 95.8% with influent NH4(+)-N of 63.58 mg L(-1) and NO3(-)-N of 69.24 mg L(-1). The maximum NH4(+)-N removal efficiency reached up to 94.7%, corresponding to the NO3(-)-N removal efficiency of 97.8%. The biomass of partial-denitrification and anammox bacteria was observed to be wall-growth. The deteriorated nitrogen removal performance occurred due to excess denitrifying microbial growth in the outer layer of sludge consortium, which prevented the substrate transfer for anammox inside. However, an excellent nitrogen removal could be guaranteed by scrapping the superficial denitrifying biomass at regular intervals. Furthermore, the high-throughput sequencing analysis revealed that the Thauera genera (26.33%) was possibly responsible for the high NO2(-)-N accumulation in partial-denitrification and Candidatus Brocadia (1.7%) was the major anammox species.

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

    SciTech Connect

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

    2006-08-01

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

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

    PubMed Central

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

    1994-01-01

    Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent Km of 0.45 to 0.60 μM and a Vmax of 18.7 nmol cm-3 h-1 at 30°C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the Kms ranged from 0.30 to 3.32 μM, with Vmaxs of 1.85 to 13.29 fmol cell-1 h-1. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater. PMID:16349284

  10. A "MICROTUBULE" IN A BACTERIUM

    PubMed Central

    van Iterson, Woutera; Hoeniger, Judith F. M.; van Zanten, Eva Nijman

    1967-01-01

    A study of the anchorage of the flagella in swarmers of Proteus mirabilis led to the incidental observation of microtubules. These microtubules were found in thin sections and in whole mount preparations of cells from which most of the content had been released by osmotic shock before staining negatively with potassium phosphotungstate (PTA). The microtubules are in negatively stained preparations about 200 A wide, i.e. somewhat thicker than the flagella (approximately 130 A). They are thus somewhat thinner than most microtubules recorded for other cells. They are referred to as microtubules because of their smooth cylindrical wall, or cortex, surrounding a hollow core which is readily filled with PTA when stained negatively. Since this is probably the first time that such a structure is described inside a bacterium, we do not know for certain whether it represents a normal cell constituent or an abnormality, for instance of the type of "polysheaths" (16). PMID:10976198

  11. Arthritis and Aerobic Exercise: A Review.

    ERIC Educational Resources Information Center

    Ike, Robert W.; And Others

    1989-01-01

    Arthritic patients who regularly do aerobic exercise make significant gains in aerobic and functional status, and in subjective areas like pain tolerance and mood. Still, they are often advised to curtail physical activity. Guidelines are presented for physicians prescribing aerobic exercise. An exercise tolerance test is recommended. (SM)

  12. Simultaneous denitrification and denitrifying phosphorus removal in a full-scale anoxic-oxic process without internal recycle treating low strength wastewater.

    PubMed

    Wang, Qibin; Chen, Qiuwen

    2016-01-01

    Performance of a full-scale anoxic-oxic activated sludge treatment plant (4.0×10(5) m(3)/day for the first-stage project) was followed during a year. The plant performed well for the removal of carbon, nitrogen and phosphorus in the process of treating domestic wastewater within a temperature range of 10.8°C to 30.5°C. Mass balance calculations indicated that COD utilization mainly occurred in the anoxic phase, accounting for 88.2% of total COD removal. Ammonia nitrogen removal occurred 13.71% in the anoxic zones and 78.77% in the aerobic zones. The contribution of anoxic zones to total nitrogen (TN) removal was 57.41%. Results indicated that nitrogen elimination in the oxic tanks was mainly contributed by simultaneous nitrification and denitrification (SND). The reduction of phosphorus mainly took place in the oxic zones, 61.46% of the total removal. Denitrifying phosphorus removal was achieved biologically by 11.29%. Practical experience proved that adaptability to gradually changing temperature of the microbial populations was important to maintain the plant overall stability. Sudden changes in temperature did not cause paralysis of the system just lower removal efficiency, which could be explained by functional redundancy of microorganisms that may compensate the adverse effects of temperature changes to a certain degree. Anoxic-oxic process without internal recycling has great potential to treat low strength wastewater (i.e., TN<35 mg/L) as well as reducing operation costs.

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

    PubMed

    Bremer, Christina; Braker, Gesche; Matthies, Diethart; Reuter, Andreas; Engels, Christof; Conrad, Ralf

    2007-11-01

    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.

  14. Water Properties Influencing the Abundance and Diversity of Denitrifiers on Eichhornia crassipes Roots: A Comparative Study from Different Effluents around Dianchi Lake, China

    PubMed Central

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Shao, Hongbo; Yan, Shaohua

    2015-01-01

    To evaluate effects of environmental conditions on the abundance and communities of three denitrifying genes coding for nitrite (nirK, nirS) reductase and nitrous oxide (nosZ) reductase on the roots of Eichhornia crassipes from 11 rivers flowing into the northern part of Dianchi Lake. The results showed that the abundance and community composition of denitrifying genes on E. crassipes root varied with different rivers. The nirK gene copies abundance was always greater than that of nirS gene on the roots of E. crassipes, suggesting that the surface of E. crassipes roots growth in Dianchi Lake was more suitable for the growth of nirK-type denitrifying bacteria. The DGGE results showed significant differences in diversity of denitrifying genes on the roots of E. crassipes among the 11 rivers. Using redundancy analysis (RDA), the correlations of denitrifying microbial community compositions with environmental factors revealed that water temperature (T), dissolved oxygen (DO), and pH were relatively important environmental factors to modifying the community structure of the denitrifying genes attached to the root of E. crassipes. The results indicated that the specific environmental conditions related to different source of rivers would have a stronger impact on the development of denitrifier communities on E. crassipes roots. PMID:26495277

  15. Water Properties Influencing the Abundance and Diversity of Denitrifiers on Eichhornia crassipes Roots: A Comparative Study from Different Effluents around Dianchi Lake, China.

    PubMed

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Shao, Hongbo; Yan, Shaohua

    2015-01-01

    To evaluate effects of environmental conditions on the abundance and communities of three denitrifying genes coding for nitrite (nirK, nirS) reductase and nitrous oxide (nosZ) reductase on the roots of Eichhornia crassipes from 11 rivers flowing into the northern part of Dianchi Lake. The results showed that the abundance and community composition of denitrifying genes on E. crassipes root varied with different rivers. The nirK gene copies abundance was always greater than that of nirS gene on the roots of E. crassipes, suggesting that the surface of E. crassipes roots growth in Dianchi Lake was more suitable for the growth of nirK-type denitrifying bacteria. The DGGE results showed significant differences in diversity of denitrifying genes on the roots of E. crassipes among the 11 rivers. Using redundancy analysis (RDA), the correlations of denitrifying microbial community compositions with environmental factors revealed that water temperature (T), dissolved oxygen (DO), and pH were relatively important environmental factors to modifying the community structure of the denitrifying genes attached to the root of E. crassipes. The results indicated that the specific environmental conditions related to different source of rivers would have a stronger impact on the development of denitrifier communities on E. crassipes roots.

  16. Mathematic Modeling for Optimum Conditions on Aflatoxin B1 Degradation by the Aerobic Bacterium Rhodococcus erythropolis

    PubMed Central

    Kong, Qing; Zhai, Cuiping; Guan, Bin; Li, Chunjuan; Shan, Shihua; Yu, Jiujiang

    2012-01-01

    Response surface methodology was employed to optimize the degradation conditions of AFB1 by Rhodococcus erythropolis in liquid culture. The most important factors that influence the degradation, as identified by a two-level Plackett-Burman design with six variables, were temperature, pH, liquid volume, inoculum size, agitation speed and incubation time. Central composite design (CCD) and response surface analysis were used to further investigate the interactions between these variables and to optimize the degradation efficiency of R. erythropolis based on a second-order model. The results demonstrated that the optimal parameters were: temperature, 23.2 °C; pH, 7.17; liquid volume, 24.6 mL in 100-mL flask; inoculum size, 10%; agitation speed, 180 rpm; and incubation time, 81.9 h. Under these conditions, the degradation efficiency of R. erythropolis could reach 95.8% in liquid culture, which was increased by about three times as compared to non-optimized conditions. The result by mathematic modeling has great potential for aflatoxin removal in industrial fermentation such as in food processing and ethanol production. PMID:23202311

  17. Genome sequence of the aerobic bacterium Bacillus sp. strain FJAT-13831.

    PubMed

    Liu, Guohong; Liu, Bo; Lin, Naiquan; Tang, Weiqi; Tang, Jianyang; Lin, Yingzhi

    2012-12-01

    Bacillus sp. strain FJAT-13831 was isolated from the no. 1 pit soil of Emperor Qin's Terracotta Warriors in Xi'an City, People's Republic of China. The isolate showed a close relationship to the Bacillus cereus group. The draft genome sequence of Bacillus sp. FJAT-13831 was 4,425,198 bp in size and consisted of 5,567 genes (protein-coding sequences [CDS]) with an average length of 782 bp and a G+C value of 36.36%.

  18. Genome Sequence of the Aerobic Bacterium Bacillus sp. Strain FJAT-13831

    PubMed Central

    Liu, Guohong; Lin, Naiquan; Tang, Weiqi; Tang, Jianyang; Lin, Yingzhi

    2012-01-01

    Bacillus sp. strain FJAT-13831 was isolated from the no. 1 pit soil of Emperor Qin's Terracotta Warriors in Xi'an City, People's Republic of China. The isolate showed a close relationship to the Bacillus cereus group. The draft genome sequence of Bacillus sp. FJAT-13831 was 4,425,198 bp in size and consisted of 5,567 genes (protein-coding sequences [CDS]) with an average length of 782 bp and a G+C value of 36.36%. PMID:23144388

  19. Genome Sequence of Chthoniobacter flavus Ellin428, an aerobic heterotrophic soil bacterium

    SciTech Connect

    Kant, Ravi; Van Passel, Mark W.J.; Palva, Airi; Lucas, Susan; Copeland, A; Lapidus, Alla L.; Glavina Del Rio, Tijana; Dalin, Eileen; Tice, Hope; Bruce, David; Goodwin, Lynne A.; Pitluck, Sam; Larimer, Frank W; Land, Miriam L; Hauser, Loren John; De Vos, Willem M.; Janssen, Peter H.; Smidt, Hauke

    2011-01-01

    Chthoniobacter flavusis Ellin428 is the first isolate from subdivision 2 of the bacterial phylum Verrucomicrobia. C. flavusis Ellin428 can metabolize many of the saccharide components of plant biomass but does not grow with amino acids or organic acids other than pyruvate.

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

    PubMed Central

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

    2011-01-01

    Real-time quantitative PCR assays, targeting part of the ammonia-monooxygenase (amoA), nitrous oxide reductase (nosZ), and 16S rRNA genes were coupled with 15N pool dilution techniques to investigate the effects of long-term agricultural management practices on potential gross N mineralization and nitrification rates, as well as ammonia-oxidizing bacteria (AOB), denitrifier, and total bacterial community sizes within different soil microenvironments. Three soil microenvironments [coarse particulate organic matter (cPOM; >250 μm), microaggregate (53–250 μm), and silt-and-clay fraction (<53 μm)] were physically isolated from soil samples collected across the cropping season from conventional, low-input, and organic maize-tomato systems (Zea mays L.- Lycopersicum esculentum L.). We hypothesized that (i) the higher N inputs and soil N content of the organic system foster larger AOB and denitrifier communities than in the conventional and low-input systems, (ii) differences in potential gross N mineralization and nitrification rates across the systems correspond with AOB and denitrifier abundances, and (iii) amoA, nosZ, and 16S rRNA gene abundances are higher in the microaggregates than in the cPOM and silt-and-clay microenvironments. Despite 13 years of different soil management and greater soil C and N content in the organic compared to the conventional and low-input systems, total bacterial communities within the whole soil were similar in size across the three systems (~5.15×108 copies g−1 soil). However, amoA gene densities were ~2 times higher in the organic (1.75×108 copies g−1 soil) than the other systems at the start of the season and nosZ gene abundances were ~2 times greater in the conventional (7.65×107 copies g−1 soil) than in the other systems by the end of the season. Because organic management did not consistently lead to larger AOB and denitrifier communities than the other two systems, our first hypothesis was not corroborated. Our second

  1. Detection and quantification of copper-denitrifying bacteria by quantitative competitive PCR.

    PubMed

    Qiu, X-Y; Hurt, R A; Wu, L-Y; Chen, C-H; Tiedje, J M; Zhou, J-Z

    2004-11-01

    We developed a quantitative competitive PCR (QC-PCR) system to detect and quantify copper-denitrifying bacteria in environmental samples. The primers were specific to copper-dependent nitrite reductase gene (nirK). We were able to detect about 200 copeis of nirK in the presence of abundant non-specific target DNA and about 1.2 x 10(3)Pseudomonas sp. G-179 cells from one gram of sterilized soil by PCR amplification. A 312-bp nirK internal standard (IS) was constructed, which showed very similar amplification efficiency with the target nirKfragment (349 bp) over 4 orders of magnitude (10(3)-10(6)). The accuracy of this system was evaluated by quantifying various known amount of nirK DNA. The linear regressions were obtained with a R(2) of 0.9867 for 10(3)copies of nirK, 0.9917 for 10(4) copies of nirK, 0.9899 for 10(5) copies of nirK and 0.9846 for 10(6) copies of nirK. A high correlation between measured nirK and calculated nirK (slope of 1.0398, R(2)=0.9992) demonstrated that an accurate measurement could be achieved with this system. Using this method, we quantified nirK in several A-horizon and stream sediment samples from eastern Tennessee. In general, the abundance of nirK was in the range of 10(8)-10(9) copies g soil(-1) dry weight. The nirK content in the soil samples appeared correlated with NH(4)(N) content in the soil. The activities of copper-denitrifying bacteria were evaluated by quantifying cDNA of nirK. In most of sample examined, the content of nirK cDNA was less than 10(5) copies g soil(-1) dry weight. Higher nirK cDNA content (>10(6) copies g soil(-1) dry weight) was detected from both sediment samples at Rattlebox Creek and the Walker Branch West Ridge. Although the stream sediment samples at the Walker Branch West Ridge contained less half of the nirK gene content as compared to A-horizon sample, the activities of copper-denitrifying bacteria were almost 600 times higher than in the A-horizon sample.

  2. Community composition of nirS-type denitrifier in a shallow eutrophic lake.

    PubMed

    Yang, Jiang-Ke; Cheng, Zhan-Bing; Li, Jia; Miao, Li-Hong

    2013-11-01

    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

  3. Decolorizing and detoxifying textile wastewater, containing both soluble and insoluble dyes, in a full scale combined anaerobic/aerobic system.

    PubMed

    Frijters, C T M J; Vos, R H; Scheffer, G; Mulder, R

    2006-03-01

    The wastewater originating from the bleaching and dyeing processes in the textile factory Ten Cate Protect in Nijverdal (the Netherlands) was successfully treated in a sequential anaerobic/aerobic system. In the system, a combination of an anaerobic 70-m3 fluidized bed reactor and a 450-m3 aerobic basin with integrated tilted plate settlers, 80-95% of the color was removed. The color was largely removed in the preacidification basin and the anaerobic reactor. Color, deriving from both reactive as well as disperse, was anaerobically removed, indicating that these type of dyes were reduced to colorless products. Interestingly, the vat dyes, the anthraquinones and indigoids, which were thought to be removed mainly aerobically, were largely anaerobically decolorized. Apparently the anaerobic system is capable of effectively removing the color of both soluble as insoluble dyes. The treated effluent of the sequential anaerobic/aerobic treatment showed no toxicity towards the bioluminescent bacterium Vibrio fisheri (EC20 (95%) > 45%). Partially bypassing the anaerobic stage resulted in increased toxicity (EC20 (95%) of 9% and 14%) in the effluent of the aerobic treatment and caused significant decrease of color removal. The results of this study show a main contribution of anaerobic treatment in decolorizing and detoxifying the textile wastewater in the sequential anaerobic/aerobic system.

  4. Calcium precipitate induced aerobic granulation.

    PubMed

    Wan, Chunli; Lee, Duu-Jong; Yang, Xue; Wang, Yayi; Wang, Xingzu; Liu, Xiang

    2015-01-01

    Aerobic granulation is a novel biotechnology for wastewater treatment. This study refined existing aerobic granulation mechanisms as a sequencing process including formation of calcium precipitate under alkaline pH to form inorganic cores, followed by bacterial attachment and growth on these cores to form the exopolysaccharide matrix. Mature granules comprised an inner core and a matrix layer and a rim layer with enriched microbial strains. The inorganic core was a mix of different crystals of calcium and phosphates. Functional strains including Sphingomonas sp., Paracoccus sp. Sinorhizobium americanum strain and Flavobacterium sp. attached onto the cores. These functional strains promote c-di-GMP production and the expression by Psl and Alg genes for exopolysaccharide production to enhance formation of mature granules.

  5. Aerobic microbial enhanced oil recovery

    SciTech Connect

    Torsvik, T.; Gilje, E.; Sunde, E.

    1995-12-31

    In aerobic MEOR, the ability of oil-degrading bacteria to mobilize oil is used to increase oil recovery. In this process, oxygen and mineral nutrients are injected into the oil reservoir in order to stimulate growth of aerobic oil-degrading bacteria in the reservoir. Experiments carried out in a model sandstone with stock tank oil and bacteria isolated from offshore wells showed that residual oil saturation was lowered from 27% to 3%. The process was time dependent, not pore volume dependent. During MEOR flooding, the relative permeability of water was lowered. Oxygen and active bacteria were needed for the process to take place. Maximum efficiency was reached at low oxygen concentrations, approximately 1 mg O{sub 2}/liter.

  6. Degradative capacities and bioaugmentation potential of an anaerobic benzene-degrading bacterium strain DN11

    SciTech Connect

    Yuki Kasai; Yumiko Kodama; Yoh Takahata; Toshihiro Hoaki; Kazuya Watanabe

    2007-09-15

    Azoarcus sp. strain DN11 is a denitrifying bacterium capable of benzene degradation under anaerobic conditions. The present study evaluated strain DN11 for its application to bioaugmentation of benzene-contaminated underground aquifers. Strain DN11 could grow on benzene, toluene, m-xylene, and benzoate as the sole carbon and energy sources under nitrate-reducing conditions, although o- and p-xylenes were transformed in the presence of toluene. Phenol was not utilized under anaerobic conditions. Kinetic analysis of anaerobic benzene degradation estimated its apparent affinity and inhibition constants to be 0.82 and 11 {mu}M, respectively. Benzene-contaminated groundwater taken from a former coal-distillation plant site in Aichi, Japan was anaerobically incubated in laboratory bottles and supplemented with either inorganic nutrients (nitrogen, phosphorus, and nitrate) alone, or the nutrients plus strain DN11, showing that benzene was significantly degraded only when DN11 was introduced. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments, and quantitative PCR revealed that DN11 decreased after benzene was degraded. Following the decrease in DN11 16S rRNA gene fragments corresponding to bacteria related to Owenweeksia hongkongensis and Pelotomaculum isophthalicum, appeared as strong bands, suggesting possible metabolic interactions in anaerobic benzene degradation. Results suggest that DN11 is potentially useful for degrading benzene that contaminates underground aquifers at relatively low concentrations. 50 refs., 6 figs., 1 tab.

  7. Degradative capacities and bioaugmentation potential of an anaerobic benzene-degrading bacterium strain DN11.

    PubMed

    Kasai, Yuki; Kodama, Yumiko; Takahata, Yoh; Hoaki, Toshihiro; Watanabe, Kazuya

    2007-09-01

    Azoarcus sp. strain DN11 is a denitrifying bacterium capable of benzene degradation under anaerobic conditions. The present study evaluated strain DN11 for its application to bioaugmentation of benzene-contaminated underground aquifers. Strain DN11 could grow on benzene, toluene, m-xylene, and benzoate as the sole carbon and energy sources under nitrate-reducing conditions, although o- and p-xylenes were transformed in the presence of toluene. Phenol was not utilized under anaerobic conditions. Kinetic analysis of anaerobic benzene degradation estimated its apparent affinity and inhibition constants to be 0.82 and 11 microM, respectively. Benzene-contaminated groundwater taken from a former coal-distillation plant site was anaerobically incubated in laboratory bottles and supplemented with either inorganic nutrients (nitrogen, phosphorus, and nitrate) alone, or the nutrients plus strain DN11, showing that benzene was significantly degraded only when DN11 was introduced. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments, and quantitative PCR revealed that DN11 decreased after benzene was degraded. Following the decrease in DN11 16S rRNA gene fragments corresponding to bacteria related to Owenweeksia hongkongensis and Pelotomaculum isophthalicum, appeared as strong bands, suggesting possible metabolic interactions in anaerobic benzene degradation. Results suggest that DN11 is potentially useful for degrading benzene that contaminates underground aquifers at relatively low concentrations.

  8. WWOX loss activates aerobic glycolysis.

    PubMed

    Abu-Remaileh, Muhannad; Seewaldt, Victoria L; Aqeilan, Rami I

    2015-01-01

    Cancer cells undergo reprogramming of glucose metabolism to limit energy production to glycolysis-a state known as "aerobic glycolysis." Hypoxia-inducible factor 1 (HIF1α) is a transcription factor that regulates many genes responsible for this switch. As discussed here, new data suggest that the tumor suppressor WW domain-containing oxidoreductase (WWOX) modulates HIF1α, thereby regulating this metabolic state.

  9. WWOX loss activates aerobic glycolysis

    PubMed Central

    Abu-Remaileh, Muhannad; Seewaldt, Victoria L; Aqeilan, Rami I

    2015-01-01

    Cancer cells undergo reprogramming of glucose metabolism to limit energy production to glycolysis—a state known as “aerobic glycolysis.” Hypoxia-inducible factor 1 (HIF1α) is a transcription factor that regulates many genes responsible for this switch. As discussed here, new data suggest that the tumor suppressor WW domain-containing oxidoreductase (WWOX) modulates HIF1α, thereby regulating this metabolic state. PMID:27308416

  10. Aerobic Metabolism of Streptococcus agalactiae

    PubMed Central

    Mickelson, M. N.

    1967-01-01

    Streptococcus agalactiae cultures possess an aerobic pathway for glucose oxidation that is strongly inhibited by cyanide. The products of glucose oxidation by aerobically grown cells of S. agalactiae 50 are lactic and acetic acids, acetylmethylcarbinol, and carbon dioxide. Glucose degradation products by aerobically grown cells, as percentage of glucose carbon, were 52 to 61% lactic acid, 20 to 23% acetic acid, 5.5 to 6.5% acetylmethylcarbinol, and 14 to 16% carbon dioxide. There was no evidence for a pentose cycle or a tricarboxylic acid cycle. Crude cell-free extracts of S. agalactiae 50 possessed a strong reduced nicotinamide adenine dinucleotide (NADH2) oxidase that is also cyanide-sensitive. Dialysis or ultrafiltration of the crude, cell-free extract resulted in loss of NADH2 oxidase activity. Oxidase activity was restored to the inactive extract by addition of the ultrafiltrate or by addition of menadione or K3Fe(CN)6. Noncytochrome iron-containing pigments were present in cell-free extracts of S. agalactiae. The possible participation of these pigments in the respiration of S. agalactiae is presently being studied. PMID:4291090

  11. Nitrate removal by nitrate-dependent Fe(II) oxidation in an upflow denitrifying biofilm reactor.

    PubMed

    Zhou, Jun; Wang, Hongyu; Yang, Kai; Sun, Yuchong; Tian, Jun

    2015-01-01

    A continuous upflow biofilm reactor packed with ceramsite was constructed for nitrate removal under an anaerobic atmosphere without an organic carbon source. Denitrifying bacteria, Pseudomonas sp. W1, Pseudomonas sp. W2 and Microbacterium sp. W5, were added to the bioreactor as inocula. Nitrate concentration, nitrite accumulation and nitrogen removal efficiency in the effluent were investigated under various conditions set by several parameters including pH, hydraulic retention time (HRT), ratios of carbon to nitrogen (C/N) and temperature. The results illustrated that the maximum removal efficiency of nitrogen was 85.39%, under optimum reaction parameters, approximately pH 6.5-7, HRT = 48 hours and C/N = 13.1:1 at temperature of 30 °C, which were determined by experiment.

  12. Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method

    USGS Publications Warehouse

    Casciotti, K.L.; Sigman, D.M.; Hastings, M. Galanter; Böhlke, J.K.; Hilkert, A.

    2002-01-01

    We report a novel method for measurement of the oxygen isotopic composition (18O/16O) of nitrate (NO3-) from both seawater and freshwater. The denitrifier method, based on the isotope ratio analysis of nitrous oxide generated from sample nitrate by cultured denitrifying bacteria, has been described elsewhere for its use in nitrogen isotope ratio (15N/14N) analysis of nitrate.1Here, we address the additional issues associated with 18O/16O analysis of nitrate by this approach, which include (1) the oxygen isotopic difference between the nitrate sample and the N2O analyte due to isotopic fractionation associated with the loss of oxygen atoms from nitrate and (2) the exchange of oxygen atoms with water during the conversion of nitrate to N2O. Experiments with 18O-labeled water indicate that water exchange contributes less than 10%, and frequently less than 3%, of the oxygen atoms in the N2O product for Pseudomonas aureofaciens. In addition, both oxygen isotope fractionation and oxygen atom exchange are consistent within a given batch of analyses. The analysis of appropriate isotopic reference materials can thus be used to correct the measured 18O/16O ratios of samples for both effects. This is the first method tested for 18O/16O analysis of nitrate in seawater. Benefits of this method, relative to published freshwater methods, include higher sensitivity (tested down to 10 nmol and 1 μM NO3-), lack of interference by other solutes, and ease of sample preparation.

  13. Rate of denitrification and the accumulation of intermediates in a denitrifying bioreactor

    NASA Astrophysics Data System (ADS)

    Parsignault, D. R.; Gursky, H.; Kellogg, E. M.; Matilsky, T.; Murray, S.; Schreier, E.; Tananbaum, H.; Giacconi, R.; Brinkman, A. C.

    2012-12-01

    Denitrifying bioreactors (DNBRs) are an emerging mechanism to mitigate the impact of excess reactive nitrogen by harnessing the activity of ubiquitous denitrifying soil microbes. DNBRs fundamentally consist of an organic carbon energy source sufficiently saturated to develop anaerobic conditions and support heterotrophic reduction of nitrate to dinitrogen. Although recent research has well established achievable nitrate removal in DNBRs upwards of 90%, few studies experimentally determine the fate of nitrogen in these systems. This study differentiates between denitrification to inert nitrogen gas, which permanently removes reactive nitrogen from an enriched ecosystem, and transformation of nitrate to another bioavailable form (such as N2O or NOX, powerful greenhouse gases). Previous research has failed to make this distinction and as both are perceived as a reduction in nitrate concentration at the outlet, the utility of DNBRs in reducing downstream reactive nitrogen has not been sufficiently established. In order to quantify the rate of nitrate removal and the products produced, dissolved gas samples are collected from the DNBR with passive diffusion gas samplers while the influent and effluent nitrate concentration and chemical oxygen demand are monitored in real time with spectrometer probes. Nitrate removal is compared with the denitrification rate and the ratio of dinitrogen to nitrous oxide is reported. Denitrification is quantified from the proportion of nitrogen gas products produced from the nitrate pool, indicated by the negative congruence of the regression of 15N enrichment in the nitrate pool and temporal depletion in the gaseous products. The proportion of nitrous oxide to dinitrogen is examined with respect to saturation and redox potential. This research informs the interpretation of previous studies as well as advises the focus of long-term system level monitoring that will provide further information on the design and application of DNBRs to

  14. Drivers of the dynamics of diazotrophs and denitrifiers in North Sea bottom waters and sediments

    PubMed Central

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

    2015-01-01

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

  15. Biotransformation of explosive-grade nitrocellulose under denitrifying and sulfidogenic conditions.

    PubMed

    Freedman, David L; Cashwell, James M; Kim, Byung J

    2002-01-01

    Waste nitrocellulose (NC) is regulated as a hazardous material. The objective of this study was to determine if NC exposed to denitrifying and sulfidogenic conditions would undergo sufficient removal of the nitro groups to yield a material that is no longer explosive. Enrichment cultures were established with methanol as the electron donor for nitrate-reducing conditions and lactate for sulfate-reducing conditions. NC was added to the cultures at 10 g/l. A statistically significant decrease in the nitrogen (N) content of NC occurred in both enrichment cultures, from approximately 13.1-13.2% in virgin NC to 12.2-12.4%. This was accompanied by an increase in nitrogen gas formation. The presence of a primary substrate (methanol and lactate) was necessary to affect this change; NC itself did not serve as an electron donor. In cultures that were carrying out denitrification but were then depleted of nitrate, with methanol still present, a slightly greater removal of nitro groups from NC occurred along with additional formation of nitrogen gas. NC did not have an inhibitory affect on the denitrification process but it did significantly slow the rate of lactate consumption and sulfate reduction. Fourier Transform Infrared Spectroscopy (FTIR) results indicated that NC exposed to denitrifying conditions was enriched in hydroxyl groups, consistent with removal of some of the nitro groups by hydrolysis of the nitrate esters. NC exposed to nitrate- and sulfate-reducing conditions and virgin NC were also compared based on their explosive properties using a small-scale burning test. The biologically treated NC exhibited somewhat less reactivity, but was still rated as explosive. The decrease in%N, increase in N2, and FTIR results demonstrated that NC does undergo biotransformation in the presence of nitrate- and sulfate-reducing enrichment cultures, but the extent of denitration does not appear to be adequate to yield a nonhazardous product.

  16. Granulation in high-load denitrifying upflow sludge bed (USB) pulsed reactors.

    PubMed

    Franco, A; Roca, E; Lema, J M

    2006-03-01

    In this work, the effect of the application of a pulse system to anoxic upflow sludge bed (USB) denitrifying reactors for enhancing sludge granulation was studied. In all, three 0.8 L reactors (two operated with flow pulsation, P1 with effluent recycling and P2 without recycling, and one without pulsation and effluent recycling, no pulsation (NP)) were fed with a mixture of NaNO3 and glucose and inoculated with methanogenic granular sludge. The organic loading rate (OLR) and the nitrogen loading rate (NLR) were progressively increased and, at the end of the experiment, extremely high values were obtained (67.5 kgCOD/m3d and 11.25 kgN-NO3-/m3 d). Ammonia and nitrite accumulation in reactor NP were important in the maturation stage, decreasing the denitrification efficiency to 90%, while in reactor P1 only low nitrite values were obtained in the last few days of the experiment. In reactor P2, nitrogen removal was 100% most of the time. Several operational problems (flotation and the subsequent wash out of biomass) appeared in the NP reactor when working at high denitrifying loading rates, while in reactors P1 and P2 there were no notable problems, mainly due to the good characteristics of the sludge developed and the efficient degasification produced by the pulsing flow. The sludge formed in the NP reactor presented a flocculent structure and a total disintegration of the initial methanogenic granules occurred, while a small-sized granular biomass with a high specific density was developed in the pulsed reactors due to the shear stress produced.

  17. Quantity-activity relationship of denitrifying bacteria and environmental scaling in streams of a forested watershed

    USGS Publications Warehouse

    O'Connor, B.L.; Hondzo, Miki; Dobraca, D.; LaPara, T.M.; Finlay, J.A.; Brezonik, P.L.

    2006-01-01

    The spatial variability of subreach denitrification rates in streams was evaluated with respect to controlling environmental conditions, molecular examination of denitrifying bacteria, and dimensional analysis. Denitrification activities ranged from 0 and 800 ng-N gsed-1 d-1 with large variations observed within short distances (<50 m) along stream reaches. A log-normal probability distribution described the range in denitrification activities and was used to define low (16% of the probability distributibn), medium (68%), and high (16%) denitrification potential groups. Denitrifying bacteria were quantified using a competitive polymerase chain reaction (cPCR) technique that amplified the nirK gene that encodes for nitrite reductase. Results showed a range of nirK quantities from 103 to 107 gene-copy-number gsed.-1 A nonparametric statistical test showed no significant difference in nirK quantifies among stream reaches, but revealed that samples with a high denitrification potential had significantly higher nirK quantities. Denitrification activity was positively correlated with nirK quantities with scatter in the data that can be attributed to varying environmental conditions along stream reaches. Dimensional analysis was used to evaluate denitrification activities according to environmental variables that describe fluid-flow properties, nitrate and organic material quantities, and dissolved oxygen flux. Buckingham's pi theorem was used to generate dimensionless groupings and field data were used to determine scaling parameters. The resulting expressions between dimensionless NO3- flux and dimensionless groupings of environmental variables showed consistent scaling, which indicates that the subreach variability in denitrification rates can be predicted by the controlling physical, chemical, and microbiological conditions. Copyright 2006 by the American Geophysical Union.

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

    PubMed Central

    Vilar-Sanz, Ariadna; Puig, Sebastià; García-Lledó, Arantzazu; Trias, Rosalia; Balaguer, M. Dolors; Colprim, Jesús; Bañeras, Lluís

    2013-01-01

    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. PMID:23717427

  19. Cytochromes c-552 from two strains of the hydrogenotrophic bacterium Alcaligenes eutrophus are sequence homologs of the cytochromes c8 from the denitrifying pseudomonads.

    PubMed

    Klarskov, K; Bartsch, R G; Meyer, T E; Cusanovich, M A; Van Beeumen, J J

    1997-12-05

    Soluble cytochromes c-552 were purified from two strains of the hydrogenothrophic species Alcaligenes eutrophus and their amino acid sequences determined. The two cytochromes were found to have 5 differences out of a total of 89 residues. The proteins are clearly related to the cytochromes c8 (formerly called Pseudomonas cytochromes c-551), but require a single residue insertion after the methionine sixth heme ligand relative to the Pseudomonas aeruginosa protein. The consensus residues Trp56 and Trp77, characteristic for the c8 family, are also present in the Alcaligenes proteins. Overall, the Alcaligenes cytochromes are only 43% identical to the Pseudomonas proteins which average 68% identity to one another. They are also only 45% identical to cytochrome c8 from Hydrogenobacter thermophilus, another hydrogenothrophic species, which indicates that the hydrogen utilizing bacteria are not more closely related to one another than they are to other species. The finding of cytochrome c8 in Alcaligenes eutrophus completes the recent characterization of a cytochrome cd1-nitrite reductase from this bacterial species and suggests the existence of the same denitrification pathway as in Pseudomonas where these two proteins are reaction partners.

  20. Draft Genome Sequence of Marinobacter hydrocarbonoclasticus Strain STW2, a Polycyclic Aromatic Hydrocarbon-Degrading and Denitrifying Bacterium from the Rhizosphere of Seagrass Enhalus acodoides

    PubMed Central

    Ling, Juan; Lin, Liyun; Zhang, Yanying; Lin, Xiancheng; Ahamad, Manzoor; Zhou, Weiguo

    2017-01-01

    ABSTRACT Here, we report the draft genome sequence of Marinobacter hydrocarbonoclasticus strain STW2, which was isolated from the rhizosphere of seagrass Enhalus acodoides. This study will facilitate future studies on the genetic pathways of marine microbes capable of both polycyclic aromatic hydrocarbon degradation and nitrate reduction. PMID:28232431

  1. A survey of culturable aerobic and anaerobic marine bacteria in de novo biofilm formation on natural substrates in St. Andrews Bay, Scotland.

    PubMed

    Finnegan, Lucy; Garcia-Melgares, Manuel; Gmerek, Tomasz; Huddleston, W Ryan; Palmer, Alexander; Robertson, Andrew; Shapiro, Sarah; Unkles, Shiela E

    2011-10-01

    This study reports a novel study of marine biofilm formation comprising aerobic and anaerobic bacteria. Samples of quartz and feldspar, minerals commonly found on the earth, were suspended 5 m deep in the North Sea off the east coast of St. Andrews, Scotland for 5 weeks. The assemblage of organisms attached to these stones was cultivated under aerobic and anaerobic conditions in the laboratory. Bacteria isolated on Marine Agar 2216 were all Gram-negative and identified to genus level by sequencing the gene encoding 16S rRNA. Colwellia, Maribacter, Pseudoaltermonas and Shewanella were observed in aerobically-grown cultures while Vibrio was found to be present in both aerobic and anaerobic cultures. The obligate anaerobic bacterium Psychrilyobacter atlanticus, a recently defined genus, was identified as a close relative of isolates grown anaerobically. The results provide valuable information as to the main players that attach and form de novo biofilms on common minerals in sea water.

  2. Aerobic and anaerobic biosynthesis of nano-selenium for remediation of mercury contaminated soil.

    PubMed

    Wang, Xiaonan; Zhang, Daoyong; Pan, Xiangliang; Lee, Duu-Jong; Al-Misned, Fahad A; Mortuza, M Golam; Gadd, Geoffrey Michael

    2017-03-01

    Selenium (Se) nanoparticles are often synthesized by anaerobes. However, anaerobic bacteria cannot be directly applied for bioremediation of contaminated top soil which is generally aerobic. In this study, a selenite-reducing bacterium, Citrobacter freundii Y9, demonstrated high selenite reducing power and produced elemental nano-selenium nanoparticles (nano-Se(0)) under both aerobic and anaerobic conditions. The biogenic nano-Se(0) converted 45.8-57.1% and 39.1-48.6% of elemental mercury (Hg(0)) in the contaminated soil to insoluble mercuric selenide (HgSe) under anaerobic and aerobic conditions, respectively. Addition of sodium dodecyl sulfonate enhanced Hg(0) remediation, probably owing to the release of intracellular nano-Se(0) from the bacterial cells for Hg fixation. The reaction product after remediation was identified as non-reactive HgSe that was formed by amalgamation of nano-Se(0) and Hg(0). Biosynthesis of nano-Se(0) both aerobically and anaerobically therefore provides a versatile and cost-effective remediation approach for Hg(0)-contaminated surface and subsurface soils, where the redox potential often changes dramatically.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

    Bañeras, Luís; Ruiz-Rueda, Olaya; López-Flores, Rocío; Quintana, Xavier D; Hallin, Sara

    2012-06-01

    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 μM 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.

  6. Lower limb loading in step aerobic dance.

    PubMed

    Wu, H-W; Hsieh, H-M; Chang, Y-W; Wang, L-H

    2012-11-01

    Participation in aerobic dance is associated with a number of lower extremity injuries, and abnormal joint loading seems to be a factor in these. However, information on joint loading is limited. The purpose of this study was to investigate the kinetics of the lower extremity in step aerobic dance and to compare the differences of high-impact and low-impact step aerobic dance in 4 aerobic movements (mambo, kick, L step and leg curl). 18 subjects were recruited for this study. High-impact aerobic dance requires a significantly greater range of motion, joint force and joint moment than low-impact step aerobic dance. The peak joint forces and moments in high-impact step aerobic dance were found to be 1.4 times higher than in low-impact step aerobic dance. Understanding the nature of joint loading may help choreographers develop dance combinations that are less injury-prone. Furthermore, increased knowledge about joint loading may be helpful in lowering the risk of injuries in aerobic dance instructors and students.

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

    PubMed

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

    2011-06-01

    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.

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

    PubMed

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

    2010-09-01

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

  9. Bacterial community and groundwater quality changes in an anaerobic aquifer during groundwater recharge with aerobic recycled water.

    PubMed

    Ginige, Maneesha P; Kaksonen, Anna H; Morris, Christina; Shackelton, Mark; Patterson, Bradley M

    2013-09-01

    Managed aquifer recharge offers the opportunity to manage groundwater resources by storing water in aquifers when in surplus and thus increase the amount of groundwater available for abstraction during high demand. The Water Corporation of Western Australia (WA) is undertaking a Groundwater Replenishment Trial to evaluate the effects of recharging aerobic recycled water (secondary treated wastewater subjected to ultrafiltration, reverse osmosis, and ultraviolet disinfection) into the anaerobic Leederville aquifer in Perth, WA. Using culture-independent methods, this study showed the presence of Actinobacteria, Alphaproteobacteria, Bacilli, Betaproteobacteria, Cytophaga, Flavobacteria, Gammaproteobacteria, and Sphingobacteria, and a decrease in microbial diversity with an increase in depth of aquifer. Assessment of physico-chemical and microbiological properties of groundwater before and after recharge revealed that recharging the aquifer with aerobic recycled water resulted in elevated redox potentials in the aquifer and increased bacterial numbers, but reduced microbial diversity. The increase in bacterial numbers and reduced microbial diversity in groundwater could be a reflection of an increased denitrifier and sulfur-oxidizing populations in the aquifer, as a result of the increased availability of nitrate, oxygen, and residual organic matter. This is consistent with the geochemical data that showed pyrite oxidation and denitrification within the aquifer after recycled water recharge commenced.

  10. Laboratory simulation of the successive aerobic and anaerobic degradation of oil products in oil-contaminated high-moor peat

    NASA Astrophysics Data System (ADS)

    Tolpeshta, I. I.; Trofimov, S. Ya.; Erkenova, M. I.; Sokolova, T. A.; Stepanov, A. L.; Lysak, L. V.; Lobanenkov, A. M.

    2015-03-01

    A model experiment has been performed on the successive aerobic and anaerobic degradation of oil products in samples of oil-contaminated peat sampled from a pine-subshrub-sphagnum bog near the Sutormin oilfield pipeline in the Yamal-Nenets autonomous district. During the incubation of oil-contaminated peat with lime and mineral fertilizers under complete flooding, favorable conditions are created for the aerobic oxidation of oil products at the beginning of the experiment and, as the redox potential decreases, for the anaerobic degradation of oil products conjugated with the reduction of N5+ and S+6 and methanogenesis. From the experimental data on the dynamics of the pH; Eh; and the NO{3/-}, NO{2/-}, and SO{4/2-} concentrations in the liquid phase of the samples, it has been found that denitrifiers significantly contributed to the biodegradation of oil products under the experimental conditions. After the end of the experiment, the content of oil products in the contaminated samples decreased by 21-26%.

  11. Effect of gradual-increasing aeration mode in an aerobic tank on nutrients' removal and functional microbial communities.

    PubMed

    Zhao, Yang-Guo; Guo, Xiaoma; She, Zonglian; Gao, Mengchun; Guo, Liang

    2016-12-30

    Different aeration rates and modes in an aerobic tank of an anaerobic/anoxic/aerobic (A(2)O) process were investigated to reveal their influence on nitrogen and phosphorus removal efficiency. Meanwhile, Illumina high-throughput sequencing of partial 16S rRNA gene of bacteria was conducted to monitor the abundance and composition of microbial communities. The results showed that higher aeration rate led to better nutrients' removal efficiency. The gradual-increasing aeration mode along the wastewater stream enhanced the contaminants' removal and the system achieved chemical oxygen demand, [Formula: see text]-N, total nitrogen (TN) removal rates of 72%, 96% and 51%, respectively. However, the gradual-decreasing or uniform aeration modes resulted in inefficient removal of TN, especially the ammonia due to low DO in the end parts of A(2)O. Microbial community analysis indicated that denitrifying phosphorus-accumulating bacteria Acinetobacter spp. were the most dominant groups under the gradual-increasing aeration mode in all tanks of the A(2)O bioreactor. Moreover, the members of genera Clostridium, Thauera and Dechloromonas also largely existed in the system. The gradual-increasing aeration mode and cooperation of different groups of bacteria made the system stable and high-performance.

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

    PubMed

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

    2015-01-01

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

  13. Treatment of phenolics, aromatic hydrocarbons, and cyanide-bearing wastewater in individual and combined anaerobic, aerobic, and anoxic bioreactors.

    PubMed

    Sharma, Naresh K; Philip, Ligy

    2015-01-01

    Studies were conducted on a mixture of pollutants commonly found in coke oven wastewater (CWW) to evaluate the biodegradation of various pollutants under anaerobic, aerobic, and anoxic conditions. The removal of the pollutants was monitored during individual bioreactor operation and using a combination of bioreactors operating in anaerobic-aerobic-anoxic sequence. While studying the performance of individual reactors, it was observed that cyanide removal (83.3 %) was predominant in the aerobic bioreactor, while much of the chemical oxygen demand (COD) (69 %) was consumed in the anoxic bioreactor. With the addition of cyanide, the COD removal efficiency was affected in all the bioreactors, and several intermediates were detected. While treating synthetic CWW using the combined bioreactor system, the overall COD removal efficiency was 86.79 % at an OLR of 2.4 g COD/L/day and an HRT of 96 h. The removal efficiency of 3,5-xylenol and cyanide, with inlet concentration of 150 and 10 mg/L, was found to be 91.8 and 93.6 % respectively. It was found that the impact of xylenol on the performance of the bioreactors was less than cyanide toxicity. Molecular analysis using T-RFLP revealed the dominance of strictly aerobic, mesophilic proteobacterium, Bosea minatitlanensis, in the aerobic bioreactor. The anoxic bioreactor was dominant with Rhodococcus pyridinivorans, known for its remarkable aromatic decomposing activity, while an unclassified Myxococcales bacterium was identified as the predominant bacterial species in the anaerobic bioreactor.

  14. Skeletal Muscle Hypertrophy after Aerobic Exercise Training

    PubMed Central

    Konopka, Adam R.; Harber, Matthew P.

    2014-01-01

    Current dogma suggests aerobic exercise training has minimal effect on skeletal muscle size. We and others have demonstrated that aerobic exercise acutely and chronically alters protein metabolism and induces skeletal muscle hypertrophy. These findings promote an antithesis to the status quo by providing novel perspective on skeletal muscle mass regulation and insight into exercise-countermeasures for populations prone to muscle loss. PMID:24508740

  15. Aerobic rice mechanization: techniques for crop establishment

    NASA Astrophysics Data System (ADS)

    Khusairy, K. M.; Ayob, H.; Chan, C. S.; Fauzi, M. I. Mohamed; Mohamad Fakhrul, Z. O.; Shahril Shah, G. S. M.; Azlan, O.; Rasad, M. A.; Hashim, A. M.; Arshad, Z.; E, E. Ibrahim; Saifulizan, M. N.

    2015-12-01

    Rice being the staple food crops, hundreds of land races in it makes the diversity of rice crops. Aerobic rice production was introduced which requires much less water input to safeguard and sustain the rice production and conserve water due to decreasing water resources, climatic changes and competition from urban and industrial users. Mechanization system plays an important role for the success of aerobic rice cultivation. All farming activities for aerobic rice production are run on aerobic soil conditions. Row seeder mechanization system is developed to replace conventional seeding technique on the aerobic rice field. It is targeted for small and the large scale aerobic rice farmers. The aero - seeder machine is used for the small scale aerobic rice field, while the accord - seeder is used for the large scale aerobic rice field. The use of this mechanization machine can eliminate the tedious and inaccurate seeding operations reduce labour costs and increases work rate. The machine is easy to operate and it can increase crop establishment rate. It reduce missing hill, increasing planting and crop with high yield can be produce. This machine is designed for low costs maintenance and it is easy to dismantle and assemble during maintenance and it is safe to be used.

  16. Aerobic Fitness for the Moderately Retarded.

    ERIC Educational Resources Information Center

    Bauer, Dan

    1981-01-01

    Intended for physical education teachers, the booklet offers ideas for incorporating aerobic conditioning into programs for moderately mentally retarded students. An explanation of aerobic fitness and its benefits is followed by information on initiating a fitness program with evaluation of height, weight, body fat, resting heart rate, and…

  17. Aerobic Dancing--A Rhythmic Sport.

    ERIC Educational Resources Information Center

    Sorensen, Jacki

    Fitness programs now and in the future must offer built-in cardiovascular conditioning, variety, novelty, and change to meet the physical, mental, and emotional needs of our society. Aerobic dancing (dancing designed to train and strengthen the heart, lungs, and vascular system) is one of the first indoor group Aerobic exercise programs designed…

  18. Aerobic salivary bacteria in wild and captive Komodo dragons.

    PubMed

    Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

    2002-07-01

    During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals.

  19. Stimulating in situ denitrification in an aerobic, highly permeable municipal drinking water aquifer.

    PubMed

    Critchley, K; Rudolph, D L; Devlin, J F; Schillig, P C

    2014-12-15

    A preliminary trial of a cross-injection system (CIS) was designed to stimulate in situ denitrification in an aquifer servicing an urban community in southern Ontario. It was hypothesized that this remedial strategy could be used to reduce groundwater nitrate in the aquifer such that it could remain in use as a municipal supply until the beneficial effects of local reduced nutrient loadings lead to long-term water quality improvement at the wellfield. The CIS application involved injecting a carbon source (acetate) into the subsurface using an injection-extraction well pair positioned perpendicular to the regional flow direction, up-gradient of the water supply wells, with the objective of stimulating native denitrifying bacteria. The pilot remedial strategy was targeted in a high nitrate flux zone within an aerobic and heterogeneous section of the glacial sand and gravel aquifer. Acetate injections were performed at intervals ranging from daily to bi-daily. The carbon additions led to general declines in dissolved oxygen concentrations; decreases in nitrate concentration were localized in aquifer layers where velocities were estimated to be less than 0.5m/day. NO3-(15)N and NO3-(18)O isotope data indicated the nitrate losses were due to denitrification. Relatively little nitrate was removed from groundwater in the more permeable strata, where velocities were estimated to be on the order of 18 m/day or greater. Overall, about 11 percent of the nitrate mass passing through the treatment zone was removed. This work demonstrates that stimulating in situ denitrification in an aerobic, highly conductive aquifer is challenging but achievable. Further work is needed to increase rates of denitrification in the most permeable units of the aquifer.

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

    PubMed

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

    2011-11-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate (NO(3)(-)) from point source discharges into non-reactive dinitrogen (N(2)) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO(3)(-) removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m(3)) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO(3)(-) enriched water (14.38 mg N L(-1) and 17.15 mg N L(-1)). After 2.5 years of incubation measurements were made of NO(3)(-)-N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO(3)(-), nitrite and ammonia), copy number of nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ) genes, and greenhouse gas production (dissolved nitrous oxide (N(2)O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO(3)(-)-N removal. Nitrate-N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m(-3) d(-1) (maize cobs), and were predominantly limited by C availability and temperature (Q(10) = 1.2) when NO(3)(-)-N outlet concentrations remained above 1 mg L(-1). The NO(3)(-)-N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N(2)O emission in

  1. Denitrification Activity of a Remarkably Diverse Fen Denitrifier Community in Finnish Lapland Is N-Oxide Limited

    PubMed Central

    Palmer, Katharina; Horn, Marcus A.

    2015-01-01

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

  2. Isolation and identification of Sphingomonas sp. that yields tert-octylphenol monoethoxylate under aerobic conditions.

    PubMed

    Nishio, Eriko; Yoshikawa, Hiromichi; Wakayama, Manabu; Tamura, Hiroto; Morita, Shiro; Tomita, Yoshifumi

    2005-07-01

    Topsoil samples were collected from eight golf courses in Yamaguchi Prefecture, Japan, and enrichment cultures were carried out with a basal-salt medium containing 0.2% 4-tert-octylphenol polyethoxylate (OPPEO) as sole carbon source. OPPEO-degrading activity was detected in one of the samples, from which a strain of OPPEO-degrading bacterium was isolated. The isolated bacterium grew on a nutritionally enriched medium (NE medium) containing 0.2% OPPEO as sole carbon source, and accumulated 4-tert-octylphenol diethoxylate (OP2EO) (63%), 4-tert-octylphenol triethoxylate (OP3EO) (14%), and 4-tert-octylphenol monoethoxylate (OP1EO) (2%) after 7 d cultivation under aerobic conditions. The addition of clay mineral (vermiculite) to the medium accelerated the degradation of OP2EO (40%) and OP3EO (4%) to OP1EO (23%). This is the first report about bacteria that can degrade OPPEO to OP1EO under aerobic conditions. The strain was identified as Sphingomonas macrogoltabidus, based on the homology of a 16S rDNA sequence.

  3. Inactivation of Mg chelatase during transition from anaerobic to aerobic growth in Rhodobacter capsulatus.

    PubMed

    Willows, Robert D; Lake, Vanessa; Roberts, Thomas Hugh; Beale, Samuel I

    2003-06-01

    The facultative photosynthetic bacterium Rhodobacter capsulatus can adapt from an anaerobic photosynthetic mode of growth to aerobic heterotrophic metabolism. As this adaptation occurs, the cells must rapidly halt bacteriochlorophyll synthesis to prevent phototoxic tetrapyrroles from accumulating, while still allowing heme synthesis to continue. A likely control point is Mg chelatase, the enzyme that diverts protoporphyrin IX from heme biosynthesis toward the bacteriochlorophyll biosynthetic pathway by inserting Mg(2+) to form Mg-protoporphyrin IX. Mg chelatase is composed of three subunits that are encoded by the bchI, bchD, and bchH genes in R. capsulatus. We report that BchH is the rate-limiting component of Mg chelatase activity in cell extracts. BchH binds protoporphyrin IX, and BchH that has been expressed and purified from Escherichia coli is red in color due to the bound protoporphyrin IX. Recombinant BchH is rapidly inactivated by light in the presence of O(2), and the inactivation results in the formation of a covalent adduct between the protein and the bound protoporphyrin IX. When photosynthetically growing R. capsulatus cells are transferred to aerobic conditions, Mg chelatase is rapidly inactivated, and BchH is the component that is most rapidly inactivated in vivo when cells are exposed to aerobic conditions. The light- and O(2)-stimulated inactivation of BchH could account for the rapid inactivation of Mg chelatase in vivo and provide a mechanism for inhibiting the synthesis of bacteriochlorophyll during adaptation of photosynthetically grown cells to aerobic conditions while still allowing heme synthesis to occur for aerobic respiration.

  4. Initial reactions in the anaerobic oxidation of toluene and m-xylene by denitrifying bacteria.

    PubMed

    Seyfried, B; Glod, G; Schocher, R; Tschech, A; Zeyer, J

    1994-11-01

    Pseudomonas sp. strain T and Pseudomonas sp. strain K172 grow with toluene under denitrifying conditions. We demonstrated that anaerobic degradation of toluene was initiated by direct oxidation of the methyl group. Benzaldehyde and benzoate accumulated sequentially after toluene was added when cell suspensions were incubated at 5 degrees C. Strain T also grows anaerobically with m-xylene, and we demonstrated that degradation was initiated by oxidation of one methyl group. In cell suspensions incubated at 5 degrees C 3-methylbenzaldehyde and 3-methylbenzoate accumulated after m-xylene was added. Toluene- or m-xylene-grown strain T cells were induced to the same extent for oxidation of both hydrocarbons. In addition, the methyl group-oxidizing enzyme system of strain T also catalyzed the oxidation of each isomer of the chloro- and fluorotoluenes to the corresponding halogenated benzoate derivatives. In contrast, strain K172 only oxidized 4-fluorotoluene to 4-fluorobenzoate, probably because of the narrow substrate specificity of the methyl group-oxidizing enzymatic system. During anaerobic growth with toluene strains T and K172 produced two transformation products, benzylsuccinate and benzylfumarate. About 0.5% of the toluene carbon was converted to these products.

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

    PubMed

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

    2013-03-01

    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.

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

    PubMed

    Jin, Xibiao; Wang, Feng; Liu, Guohong; Liu, Yongdi

    2012-01-01

    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 μm, which could be classified as Nitrosomonas-like species based on our analysis of 16 S rDNA sequences.

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

    PubMed

    Han, Minqi; Li, Zhiyong; Zhang, Fengli

    2013-08-01

    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.

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

    PubMed

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

    2015-02-01

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

  9. Formaldehyde and urea removal in a denitrifying granular sludge blanket reactor.

    PubMed

    Eiroa, M; Kennes, C; Veiga, M C

    2004-09-01

    Simultaneous formaldehyde biodegradation, urea hydrolysis and denitrification in anoxic batch assays and in a continuous laboratory anoxic reactor were investigated. In batch assays, the initial formaldehyde biodegradation rate was around 0.7 g CH(2)Og VSS(-1)d(-1) and independent of the urea concentration (90- 370 mg N-NH(2)CONH(2)l(-1)). Urea was completely hydrolyzed to ammonium in the presence of 430 mg l(-1) formaldehyde and complete denitrification took place in all cases (125 mg N-NO(-)(3)l(-1)). Formaldehyde removal efficiencies above 99.5% were obtained in a lab-scale denitrifying upflow sludge blanket reactor at organic loading rates between 0.37 and 2.96 kg CODm(-3)d(-1) (625-5000 mg CH(2)Ol(-1)). The urea loading rate was increased from 0.06 to 0.44 kg Nm(-3)d(-1) (100-800 mg N-NH(2)CONH(2)l(-1)) and hydrolysis to ammonium was around 77.5% at all loading rates. The denitrification process was always almost complete (100-800 mg N-NO(3)(-)l(-1)), due to the high COD/N ratio of 6.7 in the influent. A minimum value of 3.5 was found to be required for full denitrification. The composition of the biogas indicated that denitrification and methanogenesis occurred simultaneously in the same unit. A good granulation of the sludge was observed.

  10. Adaptation of a phenol-degrading denitrifying bacteria to high concentration of phenol in the medium.

    PubMed

    Son, T T; Błaszczyk, M; Mycielski, R

    1998-01-01

    The growth and uptake of phenol by 8 strains isolated from wastewater sediments in stationary cultures in medium with increasing concentrations of phenol (from 100 to 600 mg/L) under denitrifying conditions were studied. All the strains grew in media containing 250 mg phenol/L and only strains 101/1, 83/2 and 21/1/ in consecutive passages visibly increased both specific growth rate (mu day-1) as well as phenol-degrading activity (mg/L x day). Consecutive passages of the culture in medium containing 400 mg phenol/L resulted in the elimination of 3 out of the 5 strains growing in the medium in the first passage. Only strain 101/1 demonstrated high specific growth rate and phenol-degrading activity in medium containing 600 mg phenol/L. In consecutive passages in medium containing 250, 400 and 600 mg phenol/L the specific growth (mu day-1) and phenol-degrading activity (mg/L x day) of P. aeruginosa 101/1 were 0.38 and 36; 0.12 and 19; 0.09 and 20, respectively.

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

    PubMed

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

    2015-02-01

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

  12. Aerobic fitness testing: an update.

    PubMed

    Stevens, N; Sykes, K

    1996-12-01

    This study confirms that all three tests are reliable tools for the assessment of cardiorespiratory fitness and the prediction of aerobic capacity. While this particular study consisted of active, youthful subjects, subsequent studies at University College Chester have found similar findings with larger databases and a wider cross-section of subjects. The Astrand cycle test and Chester step test are submaximal tests with error margins of 5-15 per cent and therefore, not as precise as maximal testing. However, they still give a reasonably accurate reflection of an individual's fitness without the cost, time, effort and risk on the part of the subject. The bleep test is a low-cost maximal test designed for well-motivated, active individuals who are used to running to physical exhaustion. Used on other groups, results will not accurately reflect cardiorespiratory fitness values. While all three tests have inherent advantages and disadvantages, perhaps the most important factors are the knowledge and skills of the tester. Without a sound understanding of the physiological principles underlying these tests, and the ability to conduct an accurate assessment and evaluation of results in a knowledgeable and meaningful way, then the credibility of the tests and the results become suspect. However, used correctly, aerobic capacity tests can provide valuable baseline data about the fitness levels of individuals and data from which exercise programmes may be developed. The tests also enable fitness improvements to be monitored, help to motivate participants by establishing reasonable and achievable goals, assist in risk stratification and facilitate participants' education about the importance of physical fitness for work and for life. Since this study was completed, further tests have been repeated on 140 subjects of a wider age and ability range. This large database confirms the results found in this study.

  13. Aerobic glycolysis and lymphocyte transformation

    PubMed Central

    Hume, David A.; Radik, Judith L.; Ferber, Ernst; Weidemann, Maurice J.

    1978-01-01

    1. The role of enhanced aerobic glycolysis in the transformation of rat thymocytes by concanavalin A has been investigated. Concanavalin A addition doubled [U-14C]glucose uptake by rat thymocytes over 3h and caused an equivalent increased incorporation into protein, lipids and RNA. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin A also caused a specific increase in pyruvate oxidation, leading to an increase in the percentage contribution of glucose to the respiratory fuel. 2. Acetoacetate metabolism, which was not affected by concanavalin A, strongly suppressed pyruvate oxidation in the presence of [U-14C]glucose, but did not prevent the concanavalin A-induced stimulation of this process. Glucose uptake was not affected by acetoacetate in the presence or absence of concanavalin A, but in each case acetoacetate increased the percentage of glucose uptake accounted for by lactate production. 3. [3H]Thymidine incorporation into DNA in concanavalin A-treated thymocyte cultures was sensitive to the glucose concentration in the medium in a biphasic manner. Very low concentrations of glucose (25μm) stimulated DNA synthesis half-maximally, but maximum [3H]thymidine incorporation was observed only when the glucose concentration was raised to 1mm. Lactate addition did not alter the sensitivity of [3H]-thymidine uptake to glucose, but inosine blocked the effect of added glucose and strongly inhibited DNA synthesis. 4. It is suggested that the major function of enhanced aerobic glycolysis in transforming lymphocytes is to maintain higher steady-state amounts of glycolytic intermediates to act as precursors for macromolecule synthesis. PMID:310305

  14. Fit women are not able to use the whole aerobic capacity during aerobic dance.

    PubMed

    Edvardsen, Elisabeth; Ingjer, Frank; Bø, Kari

    2011-12-01

    Edvardsen, E, Ingjer, F, and Bø, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (VO(2)max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to ≤0.05. The results (mean ± SD) showed a lower VO(2)max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15 b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.

  15. Temporal Changes Rather than Long-Term Repeated Burning Predominately Control the Shift in the Abundance of Soil Denitrifying Community in an Australian Sclerophyll Forest.

    PubMed

    Liu, Xian; Chen, C R; Hughes, J M; Wang, W J; Lewis, Tom

    2017-01-01

    To understand the temporal dynamics of soil bacterial denitrifying community in response to long-term prescribed burning and its resilience and recovery following a fire, a wet sclerophyll forest study site under two treatments (2 yearly burning (2YB) and no burning (NB)) and with 40-year-old burning history was used. Similar temporal patterns in the abundance of total (16S rRNA) and denitrifying (narG, nirK, nirS, nosZ) bacteria between two burning treatments revealed strong temporal influences. The magnitude of burning impacts on the abundance of 16S rRNA and denitrification genes was smaller compared with the impact of sampling time, but significant burning and temporal impacts were recorded for all (P < 0.001)-except for the nirS gene. Impacts of prescribed fire on the abundance of soil denitrifying community could be observed immediately after fire, and this impact diminished over a 24-month period prior to the next prescribed burning event. In conclusion, temporal changes govern the fluctuations of the abundance of soil denitrifying genes over the sampling period and the denitrifying community can recover after fire, suggesting that this community is resilient to the effects of prescribed burning. A combination of biotic and abiotic factors may account for the different temporal dynamics of denitrification gene abundance.

  16. Novel Waddlia Intracellular Bacterium in Artibeus intermedius Fruit Bats, Mexico

    PubMed Central

    Pierlé, Sebastián Aguilar; Morales, Cirani Obregón; Martínez, Leonardo Perea; Ceballos, Nidia Aréchiga; Rivero, Juan José Pérez; Díaz, Osvaldo López; Brayton, Kelly A.

    2015-01-01

    An intracellular bacterium was isolated from fruit bats (Artibeus intermedius) in Cocoyoc, Mexico. The bacterium caused severe lesions in the lungs and spleens of bats and intracytoplasmic vacuoles in cell cultures. Sequence analyses showed it is related to Waddlia spp. (order Chlamydiales). We propose to call this bacterium Waddlia cocoyoc. PMID:26583968

  17. Volatile dimethyl polonium produced by aerobic marine microorganisms.

    PubMed

    Bahrou, Andrew S; Ollivier, Patrick R L; Hanson, Thomas E; Tessier, Emmanuel; Amouroux, David; Church, Thomas M

    2012-10-16

    The production of volatile polonium (Po(v)), a naturally occurring radioactive element, by pure cultures of aerobic marine tellurite-resistant microorganisms was investigated. Rhodotorula mucilaginosa, a carotogenic yeast, and a Bacillus sp. strain, a Gram-positive bacterium, generated approximately one and 2 orders of magnitude, respectively, greater amounts of Po(v) compared to the other organisms tested. Gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) analysis identified dimethyl polonide (DMPo) as the predominant volatile Po compound in culture headspace of the yeast. This species assignment is based on the exact relation between GC retention times and boiling points of this and other Group VI B analogues (S, Se, and Te). The extent of the biotic Po(v) production correlates exponentially with elevated particulate Po (Po(p)): dissolved Po (Po(aq)) ratios in the cultures, consistent with efficient Po bioaccumulation. Further experimentation demonstrated that some abiotic Po(v) generation is possible. However, high-level Po(v) generation in these cultures is predominantly biotic.

  18. Hydrogen evolution by strictly aerobic hydrogen bacteria under anaerobic conditions.

    PubMed

    Kuhn, M; Steinbüchel, A; Schlegel, H G

    1984-08-01

    When strains and mutants of the strictly aerobic hydrogen-oxidizing bacterium Alcaligenes eutrophus are grown heterotrophically on gluconate or fructose and are subsequently exposed to anaerobic conditions in the presence of the organic substrates, molecular hydrogen is evolved. Hydrogen evolution started immediately after the suspension was flushed with nitrogen, reached maximum rates of 70 to 100 mumol of H2 per h per g of protein, and continued with slowly decreasing rates for at least 18 h. The addition of oxygen to an H2-evolving culture, as well as the addition of nitrate to cells (which had formed the dissimilatory nitrate reductase system during the preceding growth), caused immediate cessation of hydrogen evolution. Formate is not the source of H2 evolution. The rates of H2 evolution with formate as the substrate were lower than those with gluconate. The formate hydrogenlyase system was not detectable in intact cells or crude cell extracts. Rather the cytoplasmic, NAD-reducing hydrogenase is involved by catalyzing the release of excessive reducing equivalents under anaerobic conditions in the absence of suitable electron acceptors. This conclusion is based on the following experimental results. H2 is formed only by cells which had synthesized the hydrogenases during growth. Mutants lacking the membrane-bound hydrogenase were still able to evolve H2. Mutants lacking the NAD-reducing or both hydrogenases were unable to evolve H2.

  19. Anaerobic growth of a "strict aerobe" (Bacillus subtilis).

    PubMed

    Nakano, M M; Zuber, P

    1998-01-01

    There was a long-held belief that the gram-positive soil bacterium Bacillus subtilis is a strict aerobe. But recent studies have shown that B. subtilis will grow anaerobically, either by using nitrate or nitrite as a terminal electron acceptor, or by fermentation. How B. subtilis alters its metabolic activity according to the availability of oxygen and alternative electron acceptors is but one focus of study. A two-component signal transduction system composed of a sensor kinase, ResE, and a response regulator, ResD, occupies an early stage in the regulatory pathway governing anaerobic respiration. One of the essential roles of ResD and ResE in anaerobic gene regulation is induction of fnr transcription upon oxygen limitation. FNR is a transcriptional activator for anaerobically induced genes, including those for respiratory nitrate reductase, narGHJI.B. subtilis has two distinct nitrate reductases, one for the assimilation of nitrate nitrogen and the other for nitrate respiration. In contrast, one nitrite reductase functions both in nitrite nitrogen assimilation and nitrite respiration. Unlike many anaerobes, which use pyruvate formate lyase, B. subtilis can carry out fermentation in the absence of external electron acceptors wherein pyruvate dehydrogenase is utilized to metabolize pyruvate.

  20. Comparison of aerobic and photosynthetic Rhodobacter sphaeroides 2.4.1 proteomes

    SciTech Connect

    Callister, Stephen J.; Nicora, Carrie D.; Zeng, Xiaohua; Roh, Jung Hyeob; Dominguez, Migual; Tavano, Christine; Monroe, Matthew E.; Kaplan, Samuel; Donohue, Timothy; Smith, Richard D.; Lipton, Mary S.

    2006-07-05

    Proteomes from aerobic and photosynthetic grown Rhodobacter sphaeroides 2.4.1 cell cultures were characterized using liquid chromatography-mass spectrometry in conjunction with an accurate mass and elution time (AMT) tag approach. Roughly 8000 high quality peptides were detected that represented 1,445 gene products and 34% of the predicted proteins. The identified proteins corresponded primarily to open reading frames (ORFs) contained within the two chromosomal elements of this bacterium, but a significant number were also observed from ORFs associated with 5 naturally occurring plasmids. Data mining of peptides revealed a number of proteins uniquely detected within the photosynthetic cell culture. Proteins observed in both aerobic respiratory and photosynthetic grown cultures were analyzed semi-quantitatively by comparing their estimated abundances to provide insights into bioenergetic models for aerobic respiration and photosynthesis. Additional emphasis was placed on gene products annotated as hypothetical to gain information as to their potential roles within these two growth conditions. Where possible, transcriptome data for R. sphaeroides obtained under the same culture conditions were compared with these results. This comparative study demonstrated the applicability of the AMT tag approach for high-throughput proteomic analyses of pathways associated with the photosynthetic lifestyle.

  1. The effects of aerobic training on children's creativity, self-perception, and aerobic power.

    PubMed

    Herman-Tofler, L R; Tuckman, B W

    1998-10-01

    The article examines whether participation in an aerobic exercise program (AE), as compared with a traditional physical education class (PE), significantly increased children's perceived athletic competence, physical appearance, social acceptance, behavioral conduct, and global self-worth; increased their figural creativity; and improved aerobic power as measured by an 800-meter run around a track. Further research on the effects of different types of AE is discussed, as well as the need for aerobic conditioning in the elementary school.

  2. Utilization of Phenylpropanoids by Newly Isolated Bacterium Pseudomonas sp. TRMK1.

    PubMed

    T R, Monisha; I, Mukram; B, Kirankumar; Reddy, Pooja V; Nayak, Anand S; Karegoudar, T B

    2017-01-25

    A bacterium Pseudomonas sp. TRMK1 capable of utilizing various phenylpropanoids was isolated from agro-industrial waste by enrichment culture technique. It is gram-negative, motile, aerobic, and able to utilize three different phenolic acids such as p-coumaric, ferulic, and caffeic acids at concentrations of 5, 10, and 15 mM in 18 h of incubation. The residual concentration of phenolic acids was analyzed by HPLC. The catabolic pathway of p-coumaric, ferulic, and caffeic acids is suggested based on the characterization of metabolic intermediates by GC, GC-HRMS, and different enzymatic assays. Further, Pseudomonas sp. TRMK1 utilizes a wide range of mixture of phenolic acids present in the synthetic effluent.

  3. Characterization of a halotolerant-psychroloterant bacterium from dry valley Antarctic soil.

    PubMed

    Miller, K J; Leschine, S B; Huguenin, R L

    1983-01-01

    The saline soils of the ice free dry valleys of Victoria Land, Antarctica may provide the closest analog on Earth to Martian conditions. We have initiated a study aimed at examining microbial adaptations to the harsh environment of these dry valley soils. In this report we describe the characterization of one bacterium, strain A4a, isolated from Taylor Valley soil. Strain A4a was an obligately aerobic, orange-pigmented, Gram-positive coccus that grew over wide ranges of both temperature (0 degrees C-40 degrees C) and sodium chloride concentration (0-2.0M). The optimal temperature for growth at all NaCl concentrations was 25 degrees C. Phospholipid composition and guanine plus cytosine content of the DNA of the isolate indicate a close relation to the genus Planococcus.

  4. Novel Metal Cation Resistance Systems from Mutant Fitness Analysis of Denitrifying Pseudomonas stutzeri

    PubMed Central

    Vaccaro, Brian J.; Lancaster, W. Andrew; Thorgersen, Michael P.; Zane, Grant M.; Younkin, Adam D.; Kazakov, Alexey E.; Wetmore, Kelly M.; Deutschbauer, Adam; Arkin, Adam P.; Novichkov, Pavel S.; Wall, Judy D.

    2016-01-01

    ABSTRACT Metal ion transport systems have been studied extensively, but the specificity of a given transporter is often unclear from amino acid sequence data alone. In this study, predicted Cu2+ and Zn2+ resistance systems in Pseudomonas stutzeri strain RCH2 are compared with those experimentally implicated in Cu2+ and Zn2+ resistance, as determined by using a DNA-barcoded transposon mutant library. Mutant fitness data obtained under denitrifying conditions are combined with regulon predictions to yield a much more comprehensive picture of Cu2+ and Zn2+ resistance in strain RCH2. The results not only considerably expand what is known about well-established metal ion exporters (CzcCBA, CzcD, and CusCBA) and their accessory proteins (CzcI and CusF), they also reveal that isolates with mutations in some predicted Cu2+ resistance systems do not show decreased fitness relative to the wild type when exposed to Cu2+. In addition, new genes are identified that have no known connection to Zn2+ (corB, corC, Psest_3226, Psest_3322, and Psest_0618) or Cu2+ resistance (Mrp antiporter subunit gene, Psest_2850, and Psest_0584) but are crucial for resistance to these metal cations. Growth of individual deletion mutants lacking corB, corC, Psest_3226, or Psest_3322 confirmed the observed Zn-dependent phenotypes. Notably, to our knowledge, this is the first time a bacterial homolog of TMEM165, a human gene responsible for a congenital glycosylation disorder, has been deleted and the resulting strain characterized. Finally, the fitness values indicate Cu2+- and Zn2+-based inhibition of nitrite reductase and interference with molybdenum cofactor biosynthesis for nitrate reductase. These results extend the current understanding of Cu2+ and Zn2+ efflux and resistance and their effects on denitrifying metabolism. IMPORTANCE In this study, genome-wide mutant fitness data in P. stutzeri RCH2 combined with regulon predictions identify several proteins of unknown function that are involved

  5. Conditioning and Aerobics for Older Americans.

    ERIC Educational Resources Information Center

    Hansen, Joyce

    1980-01-01

    A class designed for the maintenance and gradual improvement of senior citizens' physical fitness includes relaxation training, flexibility and stretching exercises, interval training activities (designed as a link between less strenuous exercise and more strenuous activities), and aerobic exercises. (CJ)

  6. The rise of oxygen and aerobic biochemistry.

    PubMed

    Saito, Mak A

    2012-01-11

    Analysis of conserved protein folding domains across extant genomes by Kim et al. in this issue of Structure provides insights into the timing of some of the earliest aerobic metabolisms to arise on Earth.

  7. Neuromodulation of Aerobic Exercise—A Review

    PubMed Central

    Heijnen, Saskia; Hommel, Bernhard; Kibele, Armin; Colzato, Lorenza S.

    2016-01-01

    Running, and aerobic exercise in general, is a physical activity that increasingly many people engage in but that also has become popular as a topic for scientific research. Here we review the available studies investigating whether and to which degree aerobic exercise modulates hormones, amino acids, and neurotransmitters levels. In general, it seems that factors such as genes, gender, training status, and hormonal status need to be taken into account to gain a better understanding of the neuromodular underpinnings of aerobic exercise. More research using longitudinal studies and considering individual differences is necessary to determine actual benefits. We suggest that, in order to succeed, aerobic exercise programs should include optimal periodization, prevent overtraining and be tailored to interindividual differences, including neuro-developmental and genetically-based factors. PMID:26779053

  8. The Energetics of Aerobic versus Anaerobic Respiration.

    ERIC Educational Resources Information Center

    Champion, Timothy D.; Schwenz, Richard W.

    1990-01-01

    Background information, laboratory procedures, and a discussion of the results of an experiment designed to investigate the difference in energy gained from the aerobic and anaerobic oxidation of glucose are presented. Sample experimental and calculated data are included. (CW)

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

    PubMed

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

    2016-05-01

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

  10. Anaerobic Activation of p-Cymene in Denitrifying Betaproteobacteria: Methyl Group Hydroxylation versus Addition to Fumarate

    PubMed Central

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

    2014-01-01

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

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

    PubMed

    Penton, Christopher R; St Louis, Derek; Pham, Amanda; Cole, James R; Wu, Liyou; Luo, Yiqi; Schuur, E A G; Zhou, Jizhong; Tiedje, James M

    2015-01-01

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only 1 year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations.

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

    DOE PAGES

    Penton, Christopher R.; St. Louis, Derek; Pham, Amanda; ...

    2015-07-21

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming ismore » under investigation, a tallgrass prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only 1 year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Lastly, prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations.« less

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

    PubMed Central

    Pajares, Silvia; Bohannan, Brendan J. M.

    2016-01-01

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

  14. Nitrate reduction by denitrifying anaerobic methane oxidizing microorganisms can reach a practically useful rate.

    PubMed

    Cai, Chen; Hu, Shihu; Guo, Jianhua; Shi, Ying; Xie, Guo-Jun; Yuan, Zhiguo

    2015-12-15

    Methane in biogas has been proposed to be an electron donor to facilitate complete nitrogen removal using denitrifying anaerobic methane oxidizing (DAMO) microorganisms in an anaerobic ammonium oxidation (anammox) reactor, by reducing the nitrate produced. However, the slow growth and the low activity of DAMO microorganisms cast a serious doubt about the practical usefulness of such a process. In this study, a previously established lab-scale membrane biofilm reactor (MBfR), with biofilms consisting of a coculture of DAMO and anammox microorganisms, was operated to answer if the DAMO reactor can achieve a nitrate reduction rate that can potentially be applied for wastewater treatment. Through progressively increasing nitrate and ammonium loading rates to the reactor, a nitrate removal rate of 684 ± 10 mg-N L(-1) d(-1) was achieved after 453 days of operation. This rate is, to our knowledge, by far the highest reported for DAMO reactors, and far exceeds what is predicted to be required for nitrate removal in a sidestream (5.6-135 mg-N L(-1) d(-1)) or mainstream anammox reactor (3.2-124 mg-N L(-1) d(-1)). Mass balance analysis showed that the nitrite produced by nitrate reduction was jointly reduced by anammox bacteria at a rate of 354 ± 3 mg-N L(-1) d(-1), accompanied by an ammonium removal rate of 268 ± 2 mg-N L(-1) d(-1), and DAMO bacteria at a rate of 330 ± 9 mg-N L(-1) d(-1). This study shows that the nitrate reduction rate achieved by the DAMO process can be high enough for removing nitrate produced by anammox process, which would enable complete nitrogen removal from wastewater.

  15. Molecular Characterization of Diazotrophic and Denitrifying Bacteria Associated with Mangrove Roots▿

    PubMed Central

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

    2007-01-01

    An analysis of the molecular diversity of N2 fixers and denitrifiers associated with mangrove roots was performed using terminal restriction length polymorphism (T-RFLP) of nifH (N2 fixation) and nirS and nirK (denitrification), and the compositions and structures of these communities among three sites were compared. The number of operational taxonomic units (OTU) for nifH was higher than that for nirK or nirS at all three sites. Site 3, which had the highest organic matter and sand content in the rhizosphere sediment, as well as the lowest pore water oxygen concentration, had the highest nifH diversity. Principal component analysis of biogeochemical parameters identified soil texture, organic matter content, pore water oxygen concentration, and salinity as the main variables that differentiated the sites. Nonmetric multidimensional scaling (MDS) analyses of the T-RFLP data using the Bray-Curtis coefficient, group analyses, and pairwise comparisons between the sites clearly separated the OTU of site 3 from those of sites 1 and 2. For nirS, there were statistically significant differences in the composition of OTU among the sites, but the variability was less than for nifH. OTU defined on the basis of nirK were highly similar, and the three sites were not clearly separated on the basis of these sequences. The phylogenetic trees of nifH, nirK, and nirS showed that most of the cloned sequences were more similar to sequences from the rhizosphere isolates than to those from known strains or from other environments. PMID:17827324

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

    SciTech Connect

    Penton, Christopher R.; St. Louis, Derek; Pham, Amanda; Cole, James R.; Wu, Liyou; Luo, Yiqi; Schuur, E. A. G.; Zhou, Jizhong; Tiedje, James M.

    2015-07-21

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only 1 year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Lastly, prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations.

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

    PubMed

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

    2015-10-01

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

  18. Surface Structure of Aerobically Oxidized Diamond Nanocrystals

    DTIC Science & Technology

    2014-10-27

    distribution is unlimited. Surface Structure of Aerobically Oxidized Diamond Nanocrystals The views, opinions and/or findings contained in this report...2211 diamond nanocrystals, REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING...Room 254, Mail Code 8725 New York, NY 10027 -7922 ABSTRACT Surface Structure of Aerobically Oxidized Diamond Nanocrystals Report Title We investigate

  19. Aerobic biodegradation of selected monoterpenes.

    PubMed

    Misra, G; Pavlostathis, S G; Perdue, E M; Araujo, R

    1996-07-01

    Batch experiments were conducted to assess the biotransformation potential of four hydrocarbon monoterpenes (d-limonene, alpha-pinene, gamma-terpinene, and terpinolene) and four alcohols (arbanol, linalool, plinol, and alpha-terpineol) under aerobic conditions at 23 degrees C. Both forest-soil extract and enriched cultures were used as inocula for the biodegradation experiments conducted first without, then with prior microbial acclimation to the monoterpenes tested. All four hydrocarbons and two alcohols were readily degraded. The increase in biomass and headspace CO2 concentrations paralleled the depletion of monoterpenes, thus confirming that terpene disappearance was the result of biodegradation accompanied by microbial growth and mineralization. Plinol resisted degradation in assays using inocula from diverse sources, while arbanol degraded very slowly. A significant fraction of d-limonene-derived carbon was accounted for as non-extractable, dissolved organic carbon, whereas terpineol exhibited a much higher degree of utilization. The rate and extent of monoterpene biodegradation were not significantly affected by the presence of dissolved natural organic matter.

  20. Aerobic catabolism of bile acids.

    PubMed Central

    Leppik, R A; Park, R J; Smith, M G

    1982-01-01

    Seventy-eight stable cultures obtained by enrichment on media containing ox bile or a single bile acid were able to utilize one or more bile acids, as well as components of ox bile, as primary carbon sources for growth. All isolates were obligate aerobes, and most (70) were typical (48) or atypical (22) Pseudomonas strains, the remainder (8) being gram-positive actinomycetes. Of six Pseudomonas isolates selected for further study, five produced predominantly acidic catabolites after growth on glycocholic acid, but the sixth, Pseudomonas sp. ATCC 31752, accumulated as the principal product a neutral steroid catabolite. Optimum growth of Pseudomonas sp. ATCC 31752 on ox bile occurred at pH 7 to 8 and from 25 to 30 degrees C. No additional nutrients were required to sustain good growth, but growth was stimulated by the addition of ammonium sulfate and yeast extract. Good growth was obtained with a bile solids content of 40 g/liter in shaken flasks. A near-theoretical yield of neutral steroid catabolites, comprising a major (greater than 50%) and three minor products, was obtained from fermentor growth of ATCC 31752 in 6.7 g of ox bile solids per liter. The possible commercial exploitation of these findings to produce steroid drug intermediates for the pharmaceutical industry is discussed. PMID:7149711

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

    PubMed

    Liu, Yuan; Liu, Yongzhuo; Ding, Yuanjun; Zheng, Jinwei; Zhou, Tong; Pan, Genxing; Crowley, David; Li, Lianqing; Zheng, Jufeng; Zhang, Xuhui; Yu, Xinyan; Wang, Jiafang

    2014-01-01

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

  2. Diversity, Abundance, and Distribution of nirS-Harboring Denitrifiers in Intertidal Sediments of the Yangtze Estuary.

    PubMed

    Zheng, Yanling; Hou, Lijun; Liu, Min; Gao, Juan; Yin, Guoyu; Li, Xiaofei; Deng, Fengyu; Lin, Xianbiao; Jiang, Xiaofen; Chen, Fei; Zong, Haibo; Zhou, Junliang

    2015-07-01

    Denitrification plays a critical role in nitrogen removal in estuarine and coastal ecosystems. In this study, the community composition, diversity, abundance, and distribution of cytochrome cd1-type nitrite reductase gene (nirS)-harboring denitrifiers in intertidal sediments of the Yangtze Estuary were analyzed using polymerase chain reaction (PCR)-based clone libraries and quantitative PCR techniques. Clone library analysis showed that the nirS-encoding bacterial biodiversity was significantly higher at the lower salinity sites than at the higher salinity sites. However, there was no significant seasonal difference in the nirS gene diversity between summer and winter. Phylogenetic analysis revealed that the nirS-harboring denitrifier communities at the study area had distinctive spatial heterogeneity along the estuary. At the lower salinity sites, the nirS-harboring bacterial community was co-dominated by clusters III and VII; while at the higher salinity sites, it was dominated by cluster I. Canonical correspondence analysis indicated that the community compositions of nirS-type denitrifiers were significantly correlated with salinity, ammonium, and nitrate. Quantitative PCR results showed that the nirS gene abundance was in the range of 1.01 × 10(6) to 9.00 × 10(7) copies per gram dry sediment, without significant seasonal variation. Among all the environmental factors, the nirS gene abundance was only significantly related to the change of salinity. These results can extend our current knowledge about the composition and dynamics of denitrification microbial community in the estuarine ecosystem.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. Spatiotemporal Characterization of San Francisco Bay Denitrifying Communities: a Comparison of nirK and nirS Diversity and Abundance.

    PubMed

    Lee, Jessica A; Francis, Christopher A

    2017-02-01

    Denitrifying bacteria play a critical role in the estuarine nitrogen cycle. Through the transformation of nitrate into nitrogen gas, these organisms contribute to the loss of bioavailable (i.e., fixed) nitrogen from low-oxygen environments such as estuary sediments. Denitrifiers have been shown to vary in abundance and diversity across the spatial environmental gradients that characterize estuaries, such as salinity and nitrogen availability; however, little is known about how their communities change in response to temporal changes in those environmental properties. Here, we present a 1-year survey of sediment denitrifier communities along the estuarine salinity gradient of San Francisco Bay. We used quantitative PCR and sequencing of functional genes coding for a key denitrifying enzyme, dissimilatory nitrite reductase, to compare two groups of denitrifiers: those with nirK (encoding copper-dependent nitrite reductase) and those with nirS (encoding the cytochrome-cd 1-dependent variant). We found that nirS was consistently more abundant and more diverse than nirK in all parts of the estuary. The abundances of the two genes were tightly linked across space but differed temporally, with nirK peaking when temperature was low and nirS peaking when nitrate was high. Likewise, the diversity and composition of nirK- versus nirS-type communities differed in their responses to seasonal variations, though both were strongly determined by site. Furthermore, our sequence libraries detected deeply branching clades with no cultured isolates, evidence of enormous diversity within the denitrifiers that remains to be explored.

  5. Evidence of carbon fixation pathway in a bacterium from candidate phylum SBR1093 revealed with genomic analysis.

    PubMed

    Wang, Zhiping; Guo, Feng; Liu, Lili; Zhang, Tong

    2014-01-01

    Autotrophic CO2 fixation is the most important biotransformation process in the biosphere. Research focusing on the diversity and distribution of relevant autotrophs is significant to our comprehension of the biosphere. In this study, a draft genome of a bacterium from candidate phylum SBR1093 was reconstructed with the metagenome of an industrial activated sludge. Based on comparative genomics, this autotrophy may occur via a newly discovered carbon fixation path, the hydroxypropionate-hydroxybutyrate (HPHB) cycle, which was demonstrated in a previous work to be uniquely possessed by some genera from Archaea. This bacterium possesses all of the thirteen enzymes required for the HPHB cycle; these enzymes share 30∼50% identity with those in the autotrophic species of Archaea that undergo the HPHB cycle and 30∼80% identity with the corresponding enzymes of the mixotrophic species within Bradyrhizobiaceae. Thus, this bacterium might have an autotrophic growth mode in certain conditions. A phylogenetic analysis based on the 16S rRNA gene reveals that the phylotypes within candidate phylum SBR1093 are primarily clustered into 5 clades with a shallow branching pattern. This bacterium is clustered with phylotypes from organically contaminated environments, implying a demand for organics in heterotrophic metabolism. Considering the types of regulators, such as FnR, Fur, and ArsR, this bacterium might be a facultative aerobic mixotroph with potential multi-antibiotic and heavy metal resistances. This is the first report on Bacteria that may perform potential carbon fixation via the HPHB cycle, thus may expand our knowledge of the distribution and importance of the HPHB cycle in the biosphere.

  6. Evidence of Carbon Fixation Pathway in a Bacterium from Candidate Phylum SBR1093 Revealed with Genomic Analysis

    PubMed Central

    Wang, Zhiping; Guo, Feng; Liu, Lili; Zhang, Tong

    2014-01-01

    Autotrophic CO2 fixation is the most important biotransformation process in the biosphere. Research focusing on the diversity and distribution of relevant autotrophs is significant to our comprehension of the biosphere. In this study, a draft genome of a bacterium from candidate phylum SBR1093 was reconstructed with the metagenome of an industrial activated sludge. Based on comparative genomics, this autotrophy may occur via a newly discovered carbon fixation path, the hydroxypropionate-hydroxybutyrate (HPHB) cycle, which was demonstrated in a previous work to be uniquely possessed by some genera from Archaea. This bacterium possesses all of the thirteen enzymes required for the HPHB cycle; these enzymes share 30∼50% identity with those in the autotrophic species of Archaea that undergo the HPHB cycle and 30∼80% identity with the corresponding enzymes of the mixotrophic species within Bradyrhizobiaceae. Thus, this bacterium might have an autotrophic growth mode in certain conditions. A phylogenetic analysis based on the 16S rRNA gene reveals that the phylotypes within candidate phylum SBR1093 are primarily clustered into 5 clades with a shallow branching pattern. This bacterium is clustered with phylotypes from organically contaminated environments, implying a demand for organics in heterotrophic metabolism. Considering the types of regulators, such as FnR, Fur, and ArsR, this bacterium might be a facultative aerobic mixotroph with potential multi-antibiotic and heavy metal resistances. This is the first report on Bacteria that may perform potential carbon fixation via the HPHB cycle, thus may expand our knowledge of the distribution and importance of the HPHB cycle in the biosphere. PMID:25310003

  7. Aerobic and heterotrophic nitrogen removal by Enterobacter cloacae CF-S27 with efficient utilization of hydroxylamine.

    PubMed

    Padhi, Soumesh Kumar; Tripathy, Swetaleena; Mohanty, Sriprakash; Maiti, Nikhil Kumar

    2017-05-01

    Heterotrophic bacterium, Enterobacter cloacae CF-S27 exhibited simultaneous nitrification and aerobic denitrification in presence of high concentration of hydroxylamine. With the initial nitrogen concentration of 100mgL(-1)h(-1), ammonium, nitrate and nitrite removal efficiencies were 81%, 99.9% and 92.8%, while the corresponding maximum removal rates reached as high as 11.6, 15.1 and 11.2mgL(-1)h(-1) respectively. Quantitative amplification by real time PCR and enzyme assay demonstrated that hydroxylamine reductase gene (hao) is actively involved in hetrotrophic nitrification and aerobic denitrification process of Enterobacter cloacae CF-S27. PCR primers were designed targeting amplification of hao gene from diversified environmental soil DNA. The strain Enterobacter cloacae CF-S27 significantly maintained the undetectable amount of dissolved nitrogen throughout 60days of zero water exchange fish culture experiment in domestic wastewater.

  8. Paradigms: examples from the bacterium Xylella fastidiosa.

    PubMed

    Purcell, Alexander

    2013-01-01

    The history of advances in research on Xylella fastidiosa provides excellent examples of how paradigms both advance and limit our scientific understanding of plant pathogens and the plant diseases they cause. I describe this from a personal perspective, having been directly involved with many persons who made paradigm-changing discoveries, beginning with the discovery that a bacterium, not a virus, causes Pierce's disease of grape and other plant diseases in numerous plant species, including important crop and forest species.

  9. Pneumonia caused by a previously undescribed bacterium.

    PubMed Central

    Hopfer, R L; Mills, K; Fainstein, V; Fischer, H E; Luna, M P

    1982-01-01

    A new and as yet unidentified bacterium was isolated from the lung tissue of a cancer patient with bilateral pneumonia. Clinically, the pneumonia was consistent with legionellosis; the organism cultured from the lung grew only on the charcoal-yeast extract agar routinely used for Legionella isolation. Subsequent testing, however, showed the organism to be quite distinct from the known Legionella species in its biochemical, antigenic, and growth characteristics. Images PMID:7130363

  10. pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil

    PubMed Central

    Brenzinger, Kristof; Dörsch, Peter; Braker, Gesche

    2015-01-01

    Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production. Little is known about how complex soil denitrifier communities respond to pH change and whether their ability to maintain denitrification over a wider pH range relies on phenotypic redundancy. In the present study, we followed the abundance and composition of an overall and transcriptionally active denitrifier community extracted from a farmed organic soil in Sweden (pHH2O = 7.1) when exposed to pH 5.4 and drifting back to pH 6.6. The soil was previously shown to retain much of its functioning (low N2O/N2 ratios) over a wide pH range, suggesting a high functional versatility of the underlying community. We found that denitrifier community composition, abundance and transcription changed throughout incubation concomitant with pH change in the medium, allowing for complete reduction of nitrate to N2 with little accumulation of intermediates. When exposed to pH 5.4, the denitrifier community was able to grow but reduced N2O to N2 only when near-neutral pH was reestablished by the alkalizing metabolic activity of an acid-tolerant part of the community. The genotypes proliferating under these conditions differed from those dominant in the control experiment run at neutral pH. Denitrifiers of the nirS-type appeared to be severely suppressed by low pH and nirK-type and nosZ-containing denitrifiers showed strongly reduced transcriptional activity and growth, even after restoration of neutral pH. Our study suggests that low pH episodes alter transcriptionally active populations which shape denitrifier communities and determine their gas kinetics. PMID:26441895

  11. pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil.

    PubMed

    Brenzinger, Kristof; Dörsch, Peter; Braker, Gesche

    2015-01-01

    Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production. Little is known about how complex soil denitrifier communities respond to pH change and whether their ability to maintain denitrification over a wider pH range relies on phenotypic redundancy. In the present study, we followed the abundance and composition of an overall and transcriptionally active denitrifier community extracted from a farmed organic soil in Sweden (pH H2O = 7.1) when exposed to pH 5.4 and drifting back to pH 6.6. The soil was previously shown to retain much of its functioning (low N2O/N2 ratios) over a wide pH range, suggesting a high functional versatility of the underlying community. We found that denitrifier community composition, abundance and transcription changed throughout incubation concomitant with pH change in the medium, allowing for complete reduction of nitrate to N2 with little accumulation of intermediates. When exposed to pH 5.4, the denitrifier community was able to grow but reduced N2O to N2 only when near-neutral pH was reestablished by the alkalizing metabolic activity of an acid-tolerant part of the community. The genotypes proliferating under these conditions differed from those dominant in the control experiment run at neutral pH. Denitrifiers of the nirS-type appeared to be severely suppressed by low pH and nirK-type and nosZ-containing denitrifiers showed strongly reduced transcriptional activity and growth, even after restoration of neutral pH. Our study suggests that low pH episodes alter transcriptionally active populations which shape denitrifier communities and determine their gas kinetics.

  12. System-level approach to studying oxygen stress and acclimation of Shewanella oneidensis to growth under aerobic conditions

    NASA Astrophysics Data System (ADS)

    Beliaev, A.

    2008-12-01

    Systems-level approaches have been proven extremely useful in elucidating the mechanisms involved in stress response and acclimation of microorganisms to different environments. Recent studies of Shewanella oneidensis, a dissimilatory metal reducer catalyzing biogeochemical cycling of Fe and Mn, demonstrate that this facultatively aerobic bacterium is inhibited by high concentrations of oxygen. Physiological and genomic studies demonstrated that growth under aerobic conditions triggers autoaggregation of S. oneidensis leading to significant physiological and morphological changes which are consistent with biofilm mode of growth. Global transcriptome profiling of the aggregates revealed coordinated upregulation of various attachment and adhesion factors which is governed through coordinate regulation by the RpoS, SpoIIA, and Crp transcription factors. The aerobic aggregated cells also revealed increased expression of putative anaerobic electron transfer and homologs of metal reduction genes. The experimental evidence indicates that aggregate formation in S. oneidensis may serve as an alternative or an addition to biochemical detoxification to reduce the oxidative stress associated with production of reactive oxygen species during aerobic metabolism while facilitating the development of hypoxic conditions within the aggregate interior.

  13. Removal of arsenic from groundwater by using a native isolated arsenite-oxidizing bacterium

    NASA Astrophysics Data System (ADS)

    Kao, An-Chieh; Chu, Yu-Ju; Hsu, Fu-Lan; Liao, Vivian Hsiu-Chuan

    2013-12-01

    Arsenic (As) contamination of groundwater is a significant public health concern. In this study, the removal of arsenic from groundwater using biological processes was investigated. The efficiency of arsenite (As(III)) bacterial oxidation and subsequent arsenate (As(V)) removal from contaminated groundwater using bacterial biomass was examined. A novel As(III)-oxidizing bacterium (As7325) was isolated from the aquifer in the blackfoot disease (BFD) endemic area in Taiwan. As7325 oxidized 2300 μg/l As(III) using in situ As(III)-contaminated groundwater under aerobic conditions within 1 d. After the oxidation of As(III) to As(V), As(V) removal was further examined using As7325 cell pellets. The results showed that As(V) could be adsorbed efficiently by lyophilized As7325 cell pellets, the efficiency of which was related to lyophilized cell pellet concentration. Our study conducted the examination of an alternative technology for the removal of As(III) and As(V) from groundwater, indicating that the oxidation of As(III)-contaminated groundwater by native isolated bacterium, followed by As(V) removal using bacterial biomass is a potentially effective technology for the treatment of As(III)-contaminated groundwater.

  14. Asticcacaulis benevestitus sp. nov., a psychrotolerant, dimorphic, prosthecate bacterium from tundra wetland soil.

    PubMed

    Vasilyeva, Lina V; Omelchenko, Marina V; Berestovskaya, Yulia Y; Lysenko, Anatolii M; Abraham, Wolf-Rainer; Dedysh, Svetlana N; Zavarzin, George A

    2006-09-01

    A Gram-negative, aerobic, heterotrophic, non-pigmented, dimorphic prosthecate bacterium was isolated from tundra wetland soil and designated strain Z-0023(T). Cells of this strain had a dimorphic life cycle and developed a non-adhesive stalk at a site not coincident with the centre of the cell pole, a characteristic typical of representatives of the genus Asticcacaulis. A highly distinctive feature of cells of strain Z-0023(T) was the presence of a conical, bell-shaped sheath when grown at low temperature. This prosthecate bacterium was a psychrotolerant, moderately acidophilic organism capable of growth between 4 and 28 degrees Celsius (optimum 15-20 degrees Celsius) and between pH 4.5 and 8.0 (optimum 5.6-6.0). The major phospholipid fatty acid was 18 : 1omega7c and the major phospholipids were phosphatidylglycerols. The G+C content of the DNA was 60.4 mol%. On the basis of 16S rRNA gene sequence similarity, strain Z-0023(T) was most closely related to Asticcacaulis biprosthecium (98 % similarity), Asticcacaulis taihuensis (98 %) and Asticcacaulis excentricus (95 %). However, low levels of DNA-DNA relatedness to these organisms and a number of distinctive features of the tundra wetland isolate indicated that it represented a novel species of the genus Asticcacaulis, for which the name Asticcacaulis benevestitus sp. nov. is proposed. The type strain is Z-0023(T) (=DSM 16100(T)=ATCC BAA-896(T)).

  15. The Complete Genome Sequence of the Lactic Acid Bacterium Lactococcus lactis ssp. lactis IL1403

    PubMed Central

    Bolotin, Alexander; Wincker, Patrick; Mauger, Stéphane; Jaillon, Olivier; Malarme, Karine; Weissenbach, Jean; Ehrlich, S. Dusko; Sorokin, Alexei

    2001-01-01

    Lactococcus lactis is a nonpathogenic AT-rich gram-positive bacterium closely related to the genus Streptococcus and is the most commonly used cheese starter. It is also the best-characterized lactic acid bacterium. We sequenced the genome of the laboratory strain IL1403, using a novel two-step strategy that comprises diagnostic sequencing of the entire genome and a shotgun polishing step. The genome contains 2,365,589 base pairs and encodes 2310 proteins, including 293 protein-coding genes belonging to six prophages and 43 insertion sequence (IS) elements. Nonrandom distribution of IS elements indicates that the chromosome of the sequenced strain may be a product of recent recombination between two closely related genomes. A complete set of late competence genes is present, indicating the ability of L. lactis to undergo DNA transformation. Genomic sequence revealed new possibilities for fermentation pathways and for aerobic respiration. It also indicated a horizontal transfer of genetic information from Lactococcus to gram-negative enteric bacteria of Salmonella-Escherichia group. [The sequence data described in this paper has been submitted to the GenBank data library under accession no. AE005176.] PMID:11337471

  16. Extreme furfural tolerance of a soil bacterium Enterobacter cloacae GGT036.

    PubMed

    Choi, Sun Young; Gong, Gyeongtaek; Park, Hong-Sil; Um, Youngsoon; Sim, Sang Jun; Woo, Han Min

    2015-01-10

    Detoxification process of cellular inhibitors including furfural is essential for production of bio-based chemicals from lignocellulosic biomass. Here we isolated an extreme furfural-tolerant bacterium Enterobacter cloacae GGT036 from soil sample collected in Mt. Gwanak, Republic of Korea. Among isolated bacteria, only E. cloacae GGT036 showed cell growth with 35 mM furfural under aerobic culture. Compared to the maximal half inhibitory concentration (IC50) of well-known industrial strains Escherichia coli (24.9 mM furfural) and Corynebacterium glutamicum (10 mM furfural) based on the cell density, IC50 of E. cloacae GGT036 (47.7 mM) was significantly higher after 24 h, compared to E. coli and C. glutamicum. Since bacterial cell growth was exponentially inhibited depending on linearly increased furfural concentrations in the medium, we concluded that E. cloacae GGT036 is an extreme furfural-tolerant bacterium. Recently, the complete genome sequence of E. cloacae GGT036 was announced and this could provide an insight for engineering of E. cloacae GGT036 itself or other industrially relevant bacteria.

  17. Alicyclobacillus vulcanalis sp. nov., a thermophilic, acidophilic bacterium isolated from Coso Hot Springs, California, USA.

    PubMed

    Simbahan, Jessica; Drijber, Rhae; Blum, Paul

    2004-09-01

    A thermo-acidophilic Gram-positive bacterium, strain CsHg2T, which grows aerobically at 35-65 degrees C (optimum 55 degrees C) and at pH 2.0-6.0 (optimum 4.0), was isolated from a geothermal pool located in Coso Hot Springs in the Mojave Desert, California, USA. Phylogenetic analysis of 16S rRNA gene sequences showed that this bacterium was most closely related to the type strains of Alicyclobacillus acidocaldarius (97.8 % identity) and Alicyclobacillus sendaiensis (96.9 %), three Japanese strains denoted as UZ-1, KHA-31 and MIH 332 (96.1-96.5 %) and Alicyclobacillus genomic species FR-6 (96.3 %). Phenotypic characteristics including temperature and pH optima, G+C composition, acid production from a variety of carbon sources and sensitivity to different metal salts distinguished CsHg2T from A. acidocaldarius, A. sendaiensis and FR-6. The cell lipid membrane was composed mainly of omega-cyclohexyl fatty acid, consistent with membranes from other Alicyclobacillus species. Very low DNA-DNA hybridization values between CsHg2T and the type strains of Alicyclobacillus indicate that CsHg2T represents a distinct species. On the basis of these results, the name Alicyclobacillus vulcanalis sp. nov. is proposed for this organism. The type strain is CsHg2T (ATCC BAA-915T = DSM 16176T).

  18. Aerobic Degradation of N-Methyl-4-Nitroaniline (MNA) by Pseudomonas sp. Strain FK357 Isolated from Soil

    PubMed Central

    Khan, Fazlurrahman; Vyas, Bhawna; Pal, Deepika; Cameotra, Swaranjit Singh

    2013-01-01

    N-Methyl-4-nitroaniline (MNA) is used as an additive to lower the melting temperature of energetic materials in the synthesis of insensitive explosives. Although the biotransformation of MNA under anaerobic condition has been reported, its aerobic microbial degradation has not been documented yet. A soil microcosms study showed the efficient aerobic degradation of MNA by the inhabitant soil microorganisms. An aerobic bacterium, Pseudomonas sp. strain FK357, able to utilize MNA as the sole carbon, nitrogen, and energy source, was isolated from soil microcosms. HPLC and GC-MS analysis of the samples obtained from growth and resting cell studies showed the formation of 4-nitroaniline (4-NA), 4-aminophenol (4-AP), and 1, 2, 4-benzenetriol (BT) as major metabolic intermediates in the MNA degradation pathway. Enzymatic assay carried out on cell-free lysates of MNA grown cells confirmed N-demethylation reaction is the first step of MNA degradation with the formation of 4-NA and formaldehyde products. Flavin-dependent transformation of 4-NA to 4-AP in cell extracts demonstrated that the second step of MNA degradation is a monooxygenation. Furthermore, conversion of 4-AP to BT by MNA grown cells indicates the involvement of oxidative deamination (release of NH2 substituent) reaction in third step of MNA degradation. Subsequent degradation of BT occurs by the action of benzenetriol 1, 2-dioxygenase as reported for the degradation of 4-nitrophenol. This is the first report on aerobic degradation of MNA by a single bacterium along with elucidation of metabolic pathway. PMID:24116023

  19. Aerobic methanotrophic communities at the Red Sea brine-seawater interface

    PubMed Central

    Abdallah, Rehab Z.; Adel, Mustafa; Ouf, Amged; Sayed, Ahmed; Ghazy, Mohamed A.; Alam, Intikhab; Essack, Magbubah; Lafi, Feras F.; Bajic, Vladimir B.; El-Dorry, Hamza; Siam, Rania

    2014-01-01

    The central rift of the Red Sea contains 25 brine pools with different physicochemical conditions, dictating the diversity and abundance of the microbial community. Three of these pools, the Atlantis II, Kebrit and Discovery Deeps, are uniquely characterized by a high concentration of hydrocarbons. The brine-seawater interface, described as an anoxic-oxic (brine-seawater) boundary, is characterized by a high methane concentration, thus favoring aerobic methane oxidation. The current study analyzed the aerobic free–living methane-oxidizing bacterial communities that potentially contribute to methane oxidation at the brine-seawater interfaces of the three aforementioned brine pools, using metagenomic pyrosequencing, 16S rRNA pyrotags and pmoA library constructs. The sequencing of 16S rRNA pyrotags revealed that these interfaces are characterized by high microbial community diversity. Signatures of aerobic methane-oxidizing bacteria were detected in the Atlantis II Interface (ATII-I) and the Kebrit Deep Upper (KB-U) and Lower (KB-L) brine-seawater interfaces. Through phylogenetic analysis of pmoA, we further demonstrated that the ATII-I aerobic methanotroph community is highly diverse. We propose four ATII-I pmoA clusters. Most importantly, cluster 2 groups with marine methane seep methanotrophs, and cluster 4 represent a unique lineage of an uncultured bacterium with divergent alkane monooxygenases. Moreover, non-metric multidimensional scaling (NMDS) based on the ordination of putative enzymes involved in methane metabolism showed that the Kebrit interface layers were distinct from the ATII-I and DD-I brine-seawater interfaces. PMID:25295031

  20. Isolation and characterization of comprehensive polychlorinated biphenyl degrading bacterium, Enterobacter sp. LY402.

    PubMed

    Jia, Ling-Yun; Zheng, Ai-Ping; Xu, Li; Huang, Xiao-Dong; Zhang, Qing; Yang, Feng-Lin

    2008-05-01

    A Gram-negative bacterium, named LY402, was isolated from contaminated soil. 16S rDNA sequencing and measurement of the physiological and biochemical characteristics identified it as belonging to the genus Enterobacter. Degradation experiments showed that LY402 had the ability to aerobically transform 79 of the 91 major congeners of Aroclor 1242, 1254, and 1260. However, more interestingly, the strain readily degraded certain highly chlorinated and recalcitrant polychlorinated biphenyls (PCBs). Almost all the tri- and tetra-chlorobiphenyls (CBs), except for 3,4,3',4'-CB, were degraded in 3 days, whereas 73% of 3,4,3',4'-, 92% of the penta-, 76% of the hexa-, and 37% of the hepta-CBs were transformed after 6 days. In addition, among 12 octa-CBs, 2,2',3,3',5,5',6,6- CB was obviously degraded, and 2,2',3,3',4,5,6,6'- and 2,2',3,3',4,5,5',6'-CB were slightly transformed. In a metabolite analysis, mono- and di-chlorobenzoic acids (CBAs) were identified, and parts of them were also transformed by strain LY402. Analysis of PCB degradation indicated that strain LY402 could effectively degrade PCB congeners with chlorine substitutions in both ortho- and para-positions. Consequently, this is the first report of an Enterobacteria that can efficiently degrade both low and highly chlorinated PCBs under aerobic conditions.

  1. Aerobic Excercise and Research Opportunities to Benefit Impaired Children. (Project AEROBIC). Final Report.

    ERIC Educational Resources Information Center

    Idaho Univ., Moscow.

    The final report summarizes accomplishments of Project AEROBIC (Aerobic Exercise and Research Opportunities to Benefit Impaired Children), which provided a physical education exercise program for severely, profoundly, and multiply handicapped children aged 10-21. Activities are outlined for the 3 year period and include modification of exercise…

  2. Effect of long term anaerobic and intermittent anaerobic/aerobic starvation on aerobic granules.

    PubMed

    Pijuan, Maite; Werner, Ursula; Yuan, Zhiguo

    2009-08-01

    The effect of long term anaerobic and intermittent anaerobic/aerobic starvation on the structure and activity of aerobic granules was studied. Aerobic granular sludge treating abattoir wastewater and achieving high levels of nutrient removal was subjected to 4-5 week starvation under anaerobic and intermittent anaerobic/aerobic conditions. Microscopic pictures of granules at the beginning of the starvation period presented a round and compact surface morphology with a much defined external perimeter. Under both starvation conditions, the morphology changed at the end of starvation with the external border of the granules surrounded by floppy materials. The loss of granular compactness was faster and more pronounced under anaerobic/aerobic starvation conditions. The release of Ca(2+) at the onset of anaerobic/aerobic starvation suggests a degradation of extracellular polymeric substances. The activity of ammonia oxidizing bacteria was reduced by 20 and 36% during anaerobic and intermittent anaerobic/aerobic starvation, respectively. When fresh wastewater was reintroduced, the granules recovered their initial morphology within 1 week of normal operation and the nutrient removal activity recovered fully in 3 weeks. The results show that both anaerobic and intermittent anaerobic/aerobic conditions are suitable for maintaining granule structure and activity during starvation.

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

    PubMed

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

    2014-10-01

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

  4. Impacts of nitrogen application rates on the activity and diversity of denitrifying bacteria in the Broadbalk Wheat Experiment

    PubMed Central

    Clark, Ian M.; Buchkina, Natalya; Jhurreea, Deveraj; Goulding, Keith W. T.; Hirsch, Penny R.

    2012-01-01

    Bacterial denitrification results in the loss of fertilizer nitrogen and greenhouse gas emissions as nitrous oxides, but ecological factors in soil influencing denitrifier communities are not well understood, impeding the potential for mitigation by land management. Communities vary in the relative abundance of the alternative dissimilatory nitrite reductase genes nirK and nirS, and the nitrous oxide reductase gene nosZ; however, the significance for nitrous oxide emissions is unclear. We assessed the influence of different long-term fertilization and cultivation treatments in a 160-year-old field experiment, comparing the potential for denitrification by soil samples with the size and diversity of their denitrifier communities. Denitrification potential was much higher in soil from an area left to develop from arable into woodland than from a farmyard manure-fertilized arable treatment, which in turn was significantly higher than inorganic nitrogen-fertilized and unfertilized arable plots. This correlated with abundance of nirK but not nirS, the least abundant of the genes tested in all soils, showing an inverse relationship with nirK. Most genetic variation was seen in nirK, where sequences resolved into separate groups according to soil treatment. We conclude that bacteria containing nirK are most probably responsible for the increased denitrification potential associated with nitrogen and organic carbon in this soil. PMID:22451109

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

    SciTech Connect

    Green, Stefan; Prakash, Om; Jasrotia, Puja; Overholt, Will; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M.; Watson, David B; Schadt, Christopher Warren; Brooks, Scott C; Kostka, Joel

    2011-01-01

    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 ribosomal RNA 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 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 concentration of nitrogen species, oxygen and sampling season did not appear to strongly influence the distribution of Rhodanobacter. 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.

  6. Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria.

    PubMed

    Ghafari, Shahin; Hasan, Masitah; Aroua, Mohamed Kheireddine

    2009-03-15

    Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO(2) and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO(2), (II) bicarbonate plus continuous sparging of CO(2), and (III) only bicarbonate. The pH-reducing nature of CO(2) showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO(3)(-)-N/g MLVSS/h for degrading 20 and 30 mg NO(3)(-)-N/L and 9.09 mg NO(3)(-)-N/g MLVSS/h for degrading 50mg NO(3)(-)-N/L.

  7. Continuous rhamnolipid production using denitrifying Pseudomonas aeruginosa cells in hollow-fiber bioreactor.

    PubMed

    Pinzon, Neissa M; Cook, Aaron G; Ju, Lu-Kwang

    2013-01-01

    Rhamnolipids are high-value effective biosurfactants produced by Pseudomonas aeruginosa. Large-scale production of rhamnolipids is still challenging especially under free-cell aerobic conditions in which the highly foaming nature of the culture broth reduces the productivity of the process. Immobilized systems relying on oxygen as electron acceptor have been previously investigated but oxygen transfer limitation presents difficulties for continuous rhamnolipid production. A coupled system using immobilized cells and nitrate instead of oxygen as electron acceptor taking advantage of the ability of P. aeruginosa to perform nitrate respiration was evaluated. This denitrification-based immobilized approach based on a hollow-fiber setup eliminated the transfer limitation problems and was found suitable for continuous rhamnolipid production in a period longer than 1,500 h. It completely eliminated the foaming difficulties related to aerobic systems with a comparable specific productivity of 0.017 g/(g dry cells)-h and allowed easy recovery of rhamnolipids from the cell-free medium.

  8. Genomic analysis of Melioribacter roseus, facultatively anaerobic organotrophic bacterium representing a novel deep lineage within Bacteriodetes/Chlorobi group.

    PubMed

    Kadnikov, Vitaly V; Mardanov, Andrey V; Podosokorskaya, Olga A; Gavrilov, Sergey N; Kublanov, Ilya V; Beletsky, Alexey V; Bonch-Osmolovskaya, Elizaveta A; Ravin, Nikolai V

    2013-01-01

    Melioribacter roseus is a moderately thermophilic facultatively anaerobic organotrophic bacterium representing a novel deep branch within Bacteriodetes/Chlorobi group. To better understand the metabolic capabilities and possible ecological functions of M. roseus and get insights into the evolutionary history of this bacterial lineage, we sequenced the genome of the type strain P3M-2(T). A total of 2838 open reading frames was predicted from its 3.30 Mb genome. The whole proteome analysis supported phylum-level classification of M. roseus since most of the predicted proteins had closest matches in Bacteriodetes, Proteobacteria, Chlorobi, Firmicutes and deeply-branching bacterium Caldithrix abyssi, rather than in one particular phylum. Consistent with the ability of the bacterium to grow on complex carbohydrates, the genome analysis revealed more than one hundred glycoside hydrolases, glycoside transferases, polysaccharide lyases and carbohydrate esterases. The reconstructed central metabolism revealed pathways enabling the fermentation of complex organic substrates, as well as their complete oxidation through aerobic and anaerobic respiration. Genes encoding the photosynthetic and nitrogen-fixation machinery of green sulfur bacteria, as well as key enzymes of autotrophic carbon fixation pathways, were not identified. The M. roseus genome supports its affiliation to a novel phylum Ignavibateriae, representing the first step on the evolutionary pathway from heterotrophic ancestors of Bacteriodetes/Chlorobi group towards anaerobic photoautotrophic Chlorobi.

  9. Therapeutic aspects of aerobic dance participation.

    PubMed

    Estivill, M

    1995-01-01

    An ethnographic analysis of aerobic dance exercise culture was conducted to determine the impact of the culture on the mind-body connection. After a review of the predominant theories on the relationship between vigorous exercise and elevated mood, aerobic dance participants' experiences are reported to illustrate how cognitive experience and self-esteem may be influenced. Interviews revealed that some participants achieved a pleasantly altered state of consciousness and respite from depression and stress. The relationship of the work ethic to achievement of participant satisfaction is underscored.

  10. Detection of Salmonella bacterium in drinking water using microring resonator.

    PubMed

    Bahadoran, Mahdi; Noorden, Ahmad Fakhrurrazi Ahmad; Mohajer, Faeze Sadat; Abd Mubin, Mohamad Helmi; Chaudhary, Kashif; Jalil, Muhammad Arif; Ali, Jalil; Yupapin, Preecha

    2016-01-01

    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU.

  11. Insights into the effect of soil pH on N(2)O and N(2) emissions and denitrifier community size and activity.

    PubMed

    Cuhel, Jirí; Simek, Miloslav; Laughlin, Ronnie J; Bru, David; Chèneby, Dominique; Watson, Catherine J; Philippot, Laurent

    2010-03-01

    The objective of this study was to investigate how changes in soil pH affect the N(2)O and N(2) emissions, denitrification activity, and size of a denitrifier community. We established a field experiment, situated in a grassland area, which consisted of three treatments which were repeatedly amended with a KOH solution (alkaline soil), an H(2)SO(4) solution (acidic soil), or water (natural pH soil) over 10 months. At the site, we determined field N(2)O and N(2) emissions using the (15)N gas flux method and collected soil samples for the measurement of potential denitrification activity and quantification of the size of the denitrifying community by quantitative PCR of the narG, napA, nirS, nirK, and nosZ denitrification genes. Overall, our results indicate that soil pH is of importance in determining the nature of denitrification end products. Thus, we found that the N(2)O/(N(2)O + N(2)) ratio increased with decreasing pH due to changes in the total denitrification activity, while no changes in N(2)O production were observed. Denitrification activity and N(2)O emissions measured under laboratory conditions were correlated with N fluxes in situ and therefore reflected treatment differences in the field. The size of the denitrifying community was uncoupled from in situ N fluxes, but potential denitrification was correlated with the count of NirS denitrifiers. Significant relationships were observed between nirS, napA, and narG gene copy numbers and the N(2)O/(N(2)O + N(2)) ratio, which are difficult to explain. However, this highlights the need for further studies combining analysis of denitrifier ecology and quantification of denitrification end products for a comprehensive understanding of the regulation of N fluxes by denitrification.

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

    PubMed Central

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

    1996-01-01

    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

  13. ANAEROBIC AND AEROBIC TREATMENT OF CHLORINATED ALIPHATIC COMPOUNDS

    EPA Science Inventory

    Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential-anaerobic-aerobic (sequential). Glucose,...

  14. [Long-Term Inhibition of FNA on Aerobic Phosphate Uptake and Variation of Phosphorus Uptake Properties of the Sludge].

    PubMed

    Ma, Juan; Li, Lu; Yu, Xiao-jun; Sun, Lei-jun; Sun, Hong-wei; Chen, Yong-zhi

    2015-10-01

    An alternating anaerobic/oxic ( An/O) sequencing batch reactor (SBR) was employed to investigate the long-term inhibitory effect of free nitrous acid (FNA) on aerobic phosphorus uptake performance and variation of phosphorus uptake properties of the sludge by adding nitrite. The reactor was started up under the condition of 21-23 degrees C. The results showed that FNA had no impact on phosphate release and uptake capacities of the sludge. However, the specific phosphate release/uptake rates was found to be higher. As FNA concentration (measure by HNO2-N) was lower than 0.53 x 10(-3) mg x L(-1), phosphorus removal efficiency of the system was higher than 96.9%. When the FNA concentration was increased to 0.99 x 10(-3) mg x L(-1), 1.46 x 10(-3) mg x L(-1) and 1.94 x 10(-3) mg x L(-1), the phosphorus removal performance deteriorated rapidly. The phosphorus removal efficiency was recovered to 64.42%, 67.33% and 44.14% after 50, 12 and 30 days, respectively, which implied the deterioration of phosphorus removal performance caused by FNA inhibition could be recovered and long-term acclimation could shorten the recovery process. Notably, increasing nitrite consumption appeared during aerobic phase with the concentration of FNA below 1.46 x 10(-3) mg x L(-1). It was also observed that the phosphorus uptake properties of the sludge varied after long-term inhibition. Nitrate and nitrite type anoxic phosphorus uptake capacity was increased by 3.35 and 3.86 times, respectively, suggesting long-term dosing FNA may facilitate the denitrifying of polyphosphate in organisms utilizing nitrite as electron acceptor. Moreover, long-term acclimation favored sludge settling.

  15. Anaerobic and aerobic transformation of TNT

    SciTech Connect

    Kulpa, C.F.; Boopathy, R.; Manning, J.

    1996-12-31

    Most studies on the microbial metabolism of nitroaromatic compounds have used pure cultures of aerobic microorganisms. In many cases, attempts to degrade nitroaromatics under aerobic conditions by pure cultures result in no mineralization and only superficial modifications of the structure. However, mixed culture systems properly operated result in the transformation of 2,4,6-trinitrotoluene (TNT) and in some cases mineralization of TNT occurs. In this paper, the mixed culture system is described with emphasis on intermediates and the characteristics of the aerobic microbial process including the necessity for a co-substrate. The possibility of removing TNT under aerobic/anoxic conditions is described in detail. Another option for the biodegradation of TNT and nitroaromatics is under anaerobic, sulfate reducing conditions. In this instance, the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. TNT under sulfate reducing conditions is reduced to triaminotoluene presumably by the enzyme nitrite reductase, which is commonly found in many Desulfovibrio spp. The removal of nitro groups from TNT is achieved by a series of reductive reactions with the formation of ammonia and toluene by Desulfovibrio sp. (B strain). These metabolic processes could be applied to other nitroaromatic compounds like nitrobenzene, nitrobenzoic acids, nitrophenols, and aniline. The data supporting the anaerobic transformation of TNT under different growth condition are reviewed in this report.

  16. Aerobic Exercise Prescription for Rheumatoid Arthritics.

    ERIC Educational Resources Information Center

    Evans, Blanche W.; Williams, Hilda L.

    The use of exercise as a general treatment for rheumatoid arthritics (RA) has included range of motion, muscular strength, water exercise and rest therapy while virtually ignoring possible benefits of aerobic exercise. The purposes of this project were to examine the guidelines for exercise prescription in relation to this special population and…

  17. Reflections on Psychotherapy and Aerobic Exercise.

    ERIC Educational Resources Information Center

    Silverman, Wade

    This document provides a series of reflections by a practicing psychologist on the uses of aerobic workouts in psychotherapy. Two case histories are cited to illustrate the contention that the mode of exercise, rather than simply its presence or absence, is the significant indicator of a patient's emotional well-being or psychopathology. The first…

  18. AEROBIC DENITRIFICATION: IMPLICATIONS FOR NITROGEN FATE MODELING

    EPA Science Inventory

    In the Mississippi, as well as most nitrogen-degraded rivers and streams, NO3- is the dominant N species and therefore understanding its biogeochemical behavior is critical for accurate nitrogen fate modeling. To our knowledge this is the first work to report aerobic denitrificat...

  19. Aerobic exercise in fibromyalgia: a practical review.

    PubMed

    Thomas, Eric N; Blotman, Francis

    2010-07-01

    The objective of the study was to determine the current evidence to support guidelines for aerobic exercise (AE) and fibromyalgia (FM) in practice, and to outline specific research needs in these areas. Data sources consisted of a PubMed search, 2007 Cochrane Data Base Systematic review, 2008 Ottawa panel evidence-based clinical practice guidelines, as well as additional references found from the initial search. Study selection included randomized clinical trials that compared an aerobic-only exercise intervention (land or pool based) with an untreated control, a non-exercise intervention or other exercise programs in patients responding to the 1990 American College of Rheumatology criteria for FM. The following outcome data were obtained: pain, tender points, perceived improvement in FM symptoms such as the Fibromyalgia Impact Questionnaire total score (FIQ), physical function, depression (e.g., Beck Depression Inventory, FIQ subscale for depression), fatigue and sleep were extracted from 19 clinical trials that considered the effects of aerobic-only exercise in FM patients. Data synthesis shows that there is moderate evidence of important benefit of aerobic-only exercise in FM on physical function and possibly on tender points and pain. It appears to be sufficient evidence to support the practice of AE as a part of the multidisciplinary management of FM. However, future studies must be more adequately sized, homogeneously assessed, and monitored for adherence, to draw definitive conclusions.

  20. Media for the aerobic growth of campylobacter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of agar and sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in a fumarate-pyruvate medium was examined. The broth medium was supplemented with 0.0 to 0.2% agar and inoculated with 106 CFU/ml of Campylobacter coli 33559, Campylobacter fetus 27349, Campylobacter...

  1. Adolescents' Interest and Performances in Aerobic Fitness Testing

    ERIC Educational Resources Information Center

    Zhu, Xihe; Chen, Senlin; Parrott, James

    2014-01-01

    This study examined adolescents' interest in aerobic fitness testing and its relation to the test performances. Adolescents (N = 356) from three middle schools participated in the study. The participants took two aerobic fitness tests: the Progressive Aerobic Cardiovascular Endurance Run (PACER) and One-Mile Run (1MR) with a two-day interval, and…

  2. Ventilation and Speech Characteristics during Submaximal Aerobic Exercise

    ERIC Educational Resources Information Center

    Baker, Susan E.; Hipp, Jenny; Alessio, Helaine

    2008-01-01

    Purpose: This study examined alterations in ventilation and speech characteristics as well as perceived dyspnea during submaximal aerobic exercise tasks. Method: Twelve healthy participants completed aerobic exercise-only and simultaneous speaking and aerobic exercise tasks at 50% and 75% of their maximum oxygen consumption (VO[subscript 2] max).…

  3. Is denitrifying anaerobic methane oxidation-centered technologies a solution for the sustainable operation of wastewater treatment Plants?

    PubMed

    Wang, Dongbo; Wang, Yali; Liu, Yiwen; Ngo, Huu Hao; Lian, Yu; Zhao, Jianwei; Chen, Fei; Yang, Qi; Zeng, Guangming; Li, Xiaoming

    2017-06-01

    With the world's increasing energy crisis, society is growingly considered that the operation of wastewater treatment plants (WWTPs) should be shifted in sustainable paradigms with low energy input, or energy-neutral, or even energy output. There is a lack of critical thinking on whether and how new paradigms can be implemented in WWTPs based on the conventional process. The denitrifying anaerobic methane oxidation (DAMO) process, which uses methane and nitrate (or nitrite) as electron donor and acceptor, respectively, has recently been discovered. Based on critical analyses of this process, DAMO-centered technologies can be considered as a solution for sustainable operation of WWTPs. In this review, a possible strategy with DAMO-centered technologies was outlined and illustrated how this applies for the existing WWTPs energy-saving and newly designed WWTPs energy-neutral (or even energy-producing) towards sustainable operations.

  4. A novel process combining simultaneous partial nitrification, anammox and denitrification (SNAD) with denitrifying phosphorus removal (DPR) to treat sewage.

    PubMed

    Wen, Xin; Zhou, Jian; Li, Yancheng; Qing, Xiaoxia; He, Qiang

    2016-12-01

    In this study, a novel process combined simultaneous partial nitrification, anammox and denitrification (SNAD) with denitrifying phosphorus removal (DPR) was proposed for advanced nitrogen removal. Firstly simulating sewage was introduced to a sequencing batch reactor (SBR) for organic matter removal and anaerobic phosphorus release (stage 1). Then effluent of stage 1 with low COD was discharged to a sequencing biofilm batch reactor (SBBR) for partial nitrification, anammox and partial denitrification (stage 2). The nitrate produced in SBBR was fed into SBR again, in which the nitrate was removed by DPR process (stage 3). The performance of the SNAD-DPR process was investigated. And effects of carbon source addition during start-up period on microbial community were discussed based on 16S rRNA amplicon pyrosequencing.

  5. [The new bacteriochlorophyll a-containing bacterium Roseinatronobacter monicus sp. nov. from the hypersaline soda Mono Lake (California, United States)].

    PubMed

    Boldareva, E N; Briantseva, I A; Tsapin, A; Nelson, K; Sorokin, D Iu; Turova, T P; Boĭchenko, V A; Stadnichuk, I N; Gorlenko, V M

    2007-01-01

    Two strains of pink-colored aerobic bacteriochlorophyll a-containing bacteria were isolated from aerobic (strain ROS 10) and anaerobic (strain ROS 35) zones of the water column of Mono Lake (California, United States). Cells of the bacteria were nonmotile oval gram-negative rods multiplying by binary fission by means of a constriction. No intracellular membranes were detected. Polyphosphates and poly-1-hydroxybutyric acid were the storage compounds. Pigments were represented by bacteriochlorophyll a and carotenoids of the spheroidene series. The strains were obligately aerobic, mesophilic (temperature optimum of 25-30 degrees C), alkaliphilic (pH optimum of 8.5-9.5), and halophilic (optimal NaCl concentration of 40-60 g/l). They were obligately heterotrophic and grew aerobically in the dark and in the light. Respiration was inhibited by light at wavelengths corresponding to the absorption of the cellular pigments. The substrate utilization spectra were strain-specific. In the course of organotrophic growth, the bacteria could oxidize thiosulfate to sulfate; sulfide and polysulfide could also be oxidized. The DNA G+C content was 59.4 mol % in strain ROS 10 and 59 mol % in strain ROS 35. In their phenotypic properties, the new strains were close but not identical to the alkaliphilic bacterium Roseinatronobacter thiooxidans. The distinctions in the nucleotide sequences of the 16S rRNA genes (2%) and low DNA-DNA hybridization level with Rna. thiooxidans (22-25%) allow the new strains to be assigned to a new species of the genus Roseinatronobacter, Roseinatronobacter monicus sp. nov.

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

    PubMed

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A

    2012-05-01

    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 μM 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.

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

    PubMed

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

    2015-03-01

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

  8. Spatial Distribution of Total, Ammonia-Oxidizing, and Denitrifying Bacteria in Biological Wastewater Treatment Reactors for Bioregenerative Life Support

    PubMed Central

    Sakano, Yuko; Pickering, Karen D.; Strom, Peter F.; Kerkhof, Lee J.

    2002-01-01

    Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project—Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation. PMID:11976099

  9. Nitrogen removal from synthetic wastewater using single and mixed culture systems of denitrifying fungi, bacteria, and actinobacteria.

    PubMed

    Wang, Wenfeng; Cao, Lixiang; Tan, Hongming; Zhang, Renduo

    2016-11-01

    The aim of this study was to investigate the effects of single and mixed culture of denitrifying fungi, bacteria, and actinobacteria on nitrogen removal and N2O emission in treatment of wastewater. Denitrifying endophytes of Pseudomonas sp. B2, Streptomyces sp. A9, and Fusarium sp. F3 isolated from rice plants were utilized for treatment of synthetic wastewater containing nitrate and nitrite. Experiments were conducted under shaking and static conditions. Results showed that under the static condition, more than 97 % of nitrate removal efficiencies were reached in all the treatments containing B2. The nitrate removal rates within the first 12 h in the treatments of B2, B2+A9, B2+F3, and B2+A9+F3 were 7.3, 9.8, 11, and 11 mg L(-1) h(-1), respectively. Under the shaking condition, 100 % of nitrite was removed in all the treatments containing B2. The presence of A9 and F3 with B2 increased the nitrite removal rates under both the shaking and static conditions. Compared to the B2 system, the mixed systems of B2+A9, B2+F3, and B2+A9+F3 reduced N2O emission (78.4 vs. 19.4, 1.80, and 0.03 μM in 4 weeks, respectively). Our results suggested that B2 is an important strain that enhances nitrogen removal from wastewater. Mixed cultures of B2 with A9 and F3 can remove more nitrate and nitrite from wastewater and reduce nitrite accumulation and N2O emission in the denitrification process.

  10. Transitions in nirS-type denitrifier diversity, community composition, and biogeochemical activity along the Chesapeake Bay estuary

    PubMed Central

    Francis, Christopher A.; O'Mullan, Gregory D.; Cornwell, Jeffrey C.; Ward, Bess B.

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    PubMed Central

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A

    2012-01-01

    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 (N2O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N2O 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 N2O production of both soils in anoxic microcosms, indicating denitrification as the source of N2O. Up to 500 and 10 μ nitrate stimulated denitrification in cryoturbated and unturbated peat soils, respectively. Apparent maximal reaction velocities of nitrite-dependent denitrification were 28 and 18 nmol N2O gDW−1 h−1, for cryoturbated and unturbated peat soils, respectively. Barcoded amplicon pyrosequencing of narG, nirK/nirS and nosZ (encoding nitrate, nitrite and N2O 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 N2O emission patterns of cryoturbated and unturbated peat soils are associated with contrasting denitrifier communities. PMID:22134649

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

    PubMed

    Green, Stefan J; Prakash, Om; Jasrotia, Puja; Overholt, Will A; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M; Watson, David B; Schadt, Christopher W; Brooks, Scott C; Kostka, Joel E

    2012-02-01

    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.

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

    PubMed

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

    2015-01-01

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

  15. Aerobic exercise training in modulation of aerobic physical fitness and balance of burned patients.

    PubMed

    Ali, Zizi M Ibrahim; El-Refay, Basant H; Ali, Rania Reffat

    2015-03-01

    [Purpose] This study aimed to determine the impact of aerobic exercise on aerobic capacity, balance, and treadmill time in patients with thermal burn injury. [Subjects and Methods] Burned adult patients, aged 20-40 years (n=30), from both sexes, with second degree thermal burn injuries covering 20-40% of the total body surface area (TBSA), were enrolled in this trial for 3 months. Patients were randomly divided into; group A (n=15), which performed an aerobic exercise program 3 days/week for 60 min and participated in a traditional physical therapy program, and group B (n=15), which only participated in a traditional exercise program 3 days/week. Maximal aerobic capacity, treadmill time, and Berg balance scale were measured before and after the study. [Results] In both groups, the results revealed significant improvements after treatment in all measurements; however, the improvement in group A was superior to that in group B. [Conclusion] The results provide evidence that aerobic exercises for adults with healed burn injuries improve aerobic physical fitness and balance.

  16. Draft Genome Sequence of the Suttonella ornithocola Bacterium

    PubMed Central

    Waldman Ben-Asher, Hiba; Yerushalmi, Rebecca; Wachtel, Chaim; Barbiro-Michaely, Efrat

    2017-01-01

    ABSTRACT   We report here the draft genome sequence of the Suttonella ornithocola bacterium. To date, this bacterium, found in birds, passed only phylogenetic and phenotypic analyses. To our knowledge, this is the first publication of the Suttonella ornithocola genome sequence. The genetic profile provides a basis for further analysis of its infection pathways. PMID:28209820

  17. Genome Sequence of Azotobacter vinelandii, an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes▿ †

    PubMed Central

    Setubal, João C.; dos Santos, Patricia; Goldman, Barry S.; Ertesvåg, Helga; Espin, Guadelupe; Rubio, Luis M.; Valla, Svein; Almeida, Nalvo F.; Balasubramanian, Divya; Cromes, Lindsey; Curatti, Leonardo; Du, Zijin; Godsy, Eric; Goodner, Brad; Hellner-Burris, Kaitlyn; Hernandez, José A.; Houmiel, Katherine; Imperial, Juan; Kennedy, Christina; Larson, Timothy J.; Latreille, Phil; Ligon, Lauren S.; Lu, Jing; Mærk, Mali; Miller, Nancy M.; Norton, Stacie; O'Carroll, Ina P.; Paulsen, Ian; Raulfs, Estella C.; Roemer, Rebecca; Rosser, James; Segura, Daniel; Slater, Steve; Stricklin, Shawn L.; Studholme, David J.; Sun, Jian; Viana, Carlos J.; Wallin, Erik; Wang, Baomin; Wheeler, Cathy; Zhu, Huijun; Dean, Dennis R.; Dixon, Ray; Wood, Derek

    2009-01-01

    Azotobacter vinelandii is a soil bacterium related to the Pseudomonas genus that fixes nitrogen under aerobic conditions while simultaneously protecting nitrogenase from oxygen damage. In response to carbon availability, this organism undergoes a simple differentiation process to form cysts that are resistant to drought and other physical and chemical agents. Here we report the complete genome sequence of A. vinelandii DJ, which has a single circular genome of 5,365,318 bp. In order to reconcile an obligate aerobic lifestyle with exquisitely oxygen-sensitive processes, A. vinelandii is specialized in terms of its complement of respiratory proteins. It is able to produce alginate, a polymer that further protects the organism from excess exogenous oxygen, and it has multiple duplications of alginate modification genes, which may alter alginate composition in response to oxygen availability. The genome analysis identified the chromosomal locations of the genes coding for the three known oxygen-sensitive nitrogenases, as well as genes coding for other oxygen-sensitive enzymes, such as carbon monoxide dehydrogenase and formate dehydrogenase. These findings offer new prospects for the wider application of A. vinelandii as a host for the production and characterization of oxygen-sensitive proteins. PMID:19429624

  18. Aerobic degradation of BDE-209 by Enterococcus casseliflavus: Isolation, identification and cell changes during degradation process.

    PubMed

    Tang, Shaoyu; Yin, Hua; Chen, Shuona; Peng, Hui; Chang, Jingjing; Liu, Zehua; Dang, Zhi

    2016-05-05

    Decabromodiphenyl ether (BDE-209) is one of the most commonly used brominated flame retardants that have contaminated the environment worldwide. Microbial bioremediation has been considered as an effective technique to remove these sorts of persistent organic pollutants. Enterococcus casseliflavus, a gram-positive bacterium capable of aerobically transforming BDE-209, was isolated by our team from sediments in Guiyu, an e-waste dismantling area in Guangdong Province, China. To promote microbial bioremediation of BDE-209 and elucidate the mechanism behind its aerobic degradation, the effects of BDE-209 on the cell changes of E. casseliflavus were examined in this study. The experimental results demonstrated that the high cell surface hydrophobicity (CSH) of E. casseliflavus made the bacteria absorb hydrophobic BDE-209 more easily. E. casseliflavus responded to BDE-209 stress, resulting in an increase in cell membrane permeability and accumulation of BDE-209 inside the cell. The differential expression of intracellular protein was analyzed through two-dimensional gel electrophoresis (2-DE). More than 50 differentially expressed protein spots were reproducibly detected, including 25 up, and 25 down regulated after a 4 days exposure. Moreover, the apoptotic-like cell changes were observed during E. casseliflavus mediated degradation of BDE-209 by means of flow cytometry.

  19. Effects of hexavalent chromium on performance and microbial community of an aerobic granular sequencing batch reactor.

    PubMed

    Wang, Zichao; Gao, Mengchun; She, Zonglian; Jin, Chunji; Zhao, Yangguo; Yang, Shiying; Guo, Liang; Wang, Sen

    2015-03-01

    The performance and microbial community of an aerobic granular sequencing batch reactor (GSBR) were investigated at different hexavalent chromium (Cr(VI)) concentrations. The COD and NH4 (+)-N removal efficiencies decreased with the increase in Cr(VI) concentration from 0 to 30 mg/L. The specific oxygen utilization rate (SOUR) decreased from 34.86 to 12.18 mg/(g mixed liquor suspended sludge (MLSS)·h) with the increase in Cr(VI) concentration from 0 to 30 mg/L. The specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR), and specific nitrate reduction rate (SNRR) decreased with the increase in Cr(VI) concentration, whereas the SNRR was always higher than the sum of SAOR and SNOR at 0-30 mg/L Cr(VI). The scanning electron micrographs (SEM) showed some undefined particles on the surface of filamentous bacteria that might be the chelation of chromium and macromolecular organics at 30 mg/L Cr(VI). The denaturing gradient gel electrophoresis (DGGE) profiles revealed that some microorganisms adapting to high Cr(VI) concentration gradually became the predominant bacteria, while others without Cr(VI)-tolerance capacity tended to deplete or weaken. Some bacteria could tolerate the toxicity of high Cr(VI) concentration in the aerobic GSBR, such as Propionibacteriaceae bacterium, Ochrobactrum anthropi, and Micropruina glycogenica.

  20. A Novel Denitrifying Extreme Halophile That Grows in a Simple Mineral Salts Medium

    NASA Technical Reports Server (NTRS)

    Hochstein, L. I.; Oremland, R. S.; Gherna, R.; Cote, R.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    An extremely halophilic bacterium (strain CH-1) was isolated from a saltern adjacent to San Francisco Bay. It grew in a mineral salts medium with ammonium and glucose as sole sources of nitrogen and carbon as well as energy, respectively Cells lysed at less than 10% NaCl and growth was most rapid in medium containing 20% NaCl. Cells were pieomorphic ranging from disc to ovoid-shaved and used a variety of carbohydrates as sole carbon sources. the utilization of certain carbon sources was controlled by temperature with some used at 37 degrees but not 45 C. CH-1 grew between 30 degrees and 50 C with the optimum at 45 C in the presence of 20% NaCl. CH-1 contained 2,3-di-O-isoprenyl glcerol diethers and was sensitive to aphidicofin. The major polar lipid was glucosyl-mannosyl-alucosyl diether, which is diagnostic of the Haloarcula. Thus CH-1 is an extreme halophile and a member of this genus. Among the novel characteristics of this organism was its ability to grow anaerobically in synthetic medium when nitrate was present which was only reduced to nitrous oxide. This organism should prove useful for studying denitrification and carbohydrate metabolism in the extreme halophiles; and to be a valuable resource for generic studies.

  1. Partial Nitrification and Denitrifying Phosphorus Removal in a Pilot-Scale ABR/MBR Combined Process.

    PubMed

    Wu, Peng; Xu, Lezhong; Wang, Jianfang; Huang, Zhenxing; Zhang, Jiachao; Shen, Yaoliang

    2015-11-01

    A pilot-scale combined process consisting of an anaerobic baffled reactor (ABR) and an aerobic membrane bioreactor (MBR) for the purpose of achieving easy management, low energy demands, and high efficiencies on nutrient removal from municipal wastewater was investigated. The process operated at room temperature with hydraulic retention time (HRT) of 7.5 h, recycle ratio 1 of 200%, recycle ratio 2 of 100%, and dissolved oxygen (DO) of 1 mg/L and achieved good effluent quality with chemical oxygen demand (COD) of 25 mg/L, NH4 (+)-N of 4 mg/L, total nitrogen (TN) of 11 mg/L, and total phosphorus (TP) of 0.7 mg/L. The MBR achieved partial nitrification, and NO2 (-)-N has been accumulated (4 mg/L). Efficient short-cut denitrification was occurred in the ABR with a TN removal efficiency of 51%, while the role of denitrification and phosphorus removal removed partial TN (14%). Furthermore, nitrogen was further removed (11%) by simultaneous nitrification and denitrification in the MBR. In addition, phosphorus accumulating organisms in the MBR sufficiently uptake phosphorus; thus, effluent TP further reduced with a TP removal efficiency of 84%. Analysis of fluorescence in situ hybridization (FISH) showed that ammonia oxidizing bacteria (AOB) and phosphorus accumulating organisms (PAOs) were enriched in the process. In addition, the accumulation of NO2 (-)-N was contributed to the inhibition on the activities of the NOB rather than its elimination.

  2. Fatiguing upper body aerobic exercise impairs balance.

    PubMed

    Douris, Peter C; Handrakis, John P; Gendy, Joseph; Salama, Mina; Kwon, Dae; Brooks, Richard; Salama, Nardine; Southard, Veronica

    2011-12-01

    Douris, PC, Handrakis, JP, Gendy, J, Salama, M, Kwon, D, Brooks, R, Salama, N, and Southard, V. Fatiguing upper body aerobic exercise impairs balance. J Strength Cond Res 25(12): 3299-3305, 2011-There are many studies that have examined the effects of selectively fatiguing lower extremity muscle groups with various protocols, and they have all shown to impair balance. There is limited research regarding the effect of fatiguing upper extremity exercise on balance. Muscle fiber-type recruitment patterns may be responsible for the difference between balance impairments because of fatiguing aerobic and anaerobic exercise. The purpose of our study was to investigate the effect that aerobic vs. anaerobic fatigue, upper vs. lower body fatigue will have on balance, and if so, which combination will affect balance to a greater degree. Fourteen healthy subjects, 7 men and 7 women (mean age 23.5 ± 1.7 years) took part in this study. Their mean body mass index was 23.6 ± 3.2. The study used a repeated-measures design. The effect on balance was documented after the 4 fatiguing conditions: aerobic lower body (ALB), aerobic upper body (AUB), anaerobic lower body, anaerobic upper body (WUB). The aerobic conditions used an incremental protocol performed to fatigue, and the anaerobic used the Wingate protocol. Balance was measured as a single-leg stance stability score using the Biodex Balance System. A stability score for each subject was recorded immediately after each of the 4 conditions. A repeated-measures analysis of variance with the pretest score as a covariate was used to analyze the effects of the 4 fatiguing conditions on balance. There were significant differences between the 4 conditions (p = 0.001). Post hoc analysis revealed that there were significant differences between the AUB, mean score 4.98 ± 1.83, and the WUB, mean score 4.09 ± 1.42 (p = 0.014) and between AUB and ALB mean scores 4.33 ± 1.40 (p = 0.029). Normative data for single-leg stability testing for

  3. Molecular and Cellular Fundamentals of Aerobic Cometabolism

    DTIC Science & Technology

    1998-10-01

    1 99 1 ) Butane Pseudomonas butane monooxygenase (Hamamura, et al . , butanovorars (BMO) 1 997) 2,4-Dichloro Alcaligenes eutrophus...Leadbetter and Foster, 1 960). These studies initially revealed that the methane-utilizing bacterium Pseudomonas (Methylomonas) methanica could not grow...enzyme is required for each insertion. Pseudomonas mendocina KR 1 toluene-4-monooxygenase (T4MO) produces p-cresol ; Pseudomonas picketii toluene

  4. Small-scale, hydrogen-oxidizing-denitrifying bioreactor for treatment of nitrate-contaminated drinking water.

    PubMed

    Smith, Richard L; Buckwalter, Seanne P; Repert, Deborah A; Miller, Daniel N

    2005-05-01

    Nitrate removal by hydrogen-coupled denitrification was examined using flow-through, packed-bed bioreactors to develop a small-scale, cost effective system for treating nitrate-contaminated drinking-water supplies. Nitrate removal was accomplished using a Rhodocyclus sp., strain HOD 5, isolated from a sole-source drinking-water aquifer. The autotrophic capacity of the purple non-sulfur photosynthetic bacterium made it particularly adept for this purpose. Initial tests used a commercial bioreactor filled with glass beads and countercurrent, non-sterile flow of an autotrophic, air-saturated, growth medium and hydrogen gas. Complete removal of 2 mM nitrate was achieved for more than 300 days of operation at a 2-h retention time. A low-cost hydrogen generator/bioreactor system was then constructed from readily available materials as a water treatment approach using the Rhodocyclus strain. After initial tests with the growth medium, the constructed system was tested using nitrate-amended drinking water obtained from fractured granite and sandstone aquifers, with moderate and low TDS loads, respectively. Incomplete nitrate removal was evident in both water types, with high-nitrite concentrations in the bioreactor output, due to a pH increase, which inhibited nitrite reduction. This was rectified by including carbon dioxide in the hydrogen stream. Additionally, complete nitrate removal was accomplished with wastewater-impacted surface water, with a concurrent decrease in dissolved organic carbon. The results of this study using three chemically distinct water supplies demonstrate that hydrogen-coupled denitrification can serve as the basis for small-scale remediation and that pilot-scale testing might be the next logical step.

  5. Small-scale, hydrogen-oxidizing-denitrifying bioreactor for treatment of nitrate-contaminated drinking water

    USGS Publications Warehouse

    Smith, R.L.; Buckwalter, S.P.; Repert, D.A.; Miller, D.N.

    2005-01-01

    Nitrate removal by hydrogen-coupled denitrification was examined using flow-through, packed-bed bioreactors to develop a small-scale, cost effective system for treating nitrate-contaminated drinking-water supplies. Nitrate removal was accomplished using a Rhodocyclus sp., strain HOD 5, isolated from a sole-source drinking-water aquifer. The autotrophic capacity of the purple non-sulfur photosynthetic bacterium made it particularly adept for this purpose. Initial tests used a commercial bioreactor filled with glass beads and countercurrent, non-sterile flow of an autotrophic, air-saturated, growth medium and hydrogen gas. Complete removal of 2 mM nitrate was achieved for more than 300 days of operation at a 2-h retention time. A low-cost hydrogen generator/bioreactor system was then constructed from readily available materials as a water treatment approach using the Rhodocyclus strain. After initial tests with the growth medium, the constructed system was tested using nitrate-amended drinking water obtained from fractured granite and sandstone aquifers, with moderate and low TDS loads, respectively. Incomplete nitrate removal was evident in both water types, with high-nitrite concentrations in the bioreactor output, due to a pH increase, which inhibited nitrite reduction. This was rectified by including carbon dioxide in the hydrogen stream. Additionally, complete nitrate removal was accomplished with wastewater-impacted surface water, with a concurrent decrease in dissolved organic carbon. The results of this study using three chemically distinct water supplies demonstrate that hydrogen-coupled denitrification can serve as the basis for small-scale remediation and that pilot-scale testing might be the next logical step.

  6. Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice.

    PubMed

    Vance, Tyler D R; Olijve, Luuk L C; Campbell, Robert L; Voets, Ilja K; Davies, Peter L; Guo, Shuaiqi

    2014-07-04

    The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches.

  7. Osmoregulation in the Halophilic Bacterium Halomonas elongata: A Case Study for Integrative Systems Biology

    PubMed Central

    Knabe, Nicole; Siedler, Frank; Scheffer, Beatrix; Pflüger-Grau, Katharina; Pfeiffer, Friedhelm; Oesterhelt, Dieter; Marin-Sanguino, Alberto

    2017-01-01

    Halophilic bacteria use a variety of osmoregulatory methods, such as the accumulation of one or more compatible solutes. The wide diversity of compounds that can act as compatible solute complicates the task of understanding the different strategies that halophilic bacteria use to cope with salt. This is specially challenging when attempting to go beyond the pathway that produces a certain compatible solute towards an understanding of how the metabolic network as a whole addresses the problem. Metabolic reconstruction based on genomic data together with Flux Balance Analysis (FBA) is a promising tool to gain insight into this problem. However, as more of these reconstructions become available, it becomes clear that processes predicted by genome annotation may not reflect the processes that are active in vivo. As a case in point, E. coli is unable to grow aerobically on citrate in spite of having all the necessary genes to do it. It has also been shown that the realization of this genetic potential into an actual capability to metabolize citrate is an extremely unlikely event under normal evolutionary conditions. Moreover, many marine bacteria seem to have the same pathways to metabolize glucose but each species uses a different one. In this work, a metabolic network inferred from genomic annotation of the halophilic bacterium Halomonas elongata and proteomic profiling experiments are used as a starting point to motivate targeted experiments in order to find out some of the defining features of the osmoregulatory strategies of this bacterium. This new information is then used to refine the network in order to describe the actual capabilities of H. elongata, rather than its genetic potential. PMID:28081159

  8. Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice

    PubMed Central

    Vance, Tyler D. R.; Olijve, Luuk L. C.; Campbell, Robert L.; Voets, Ilja K.; Davies, Peter L.; Guo, Shuaiqi

    2014-01-01

    The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches. PMID:24892750

  9. Production of polyhydroxybutyrate by the marine photosynthetic bacterium Rhodovulum sulfidophilum P5

    NASA Astrophysics Data System (ADS)

    Cai, Jinling; Wei, Ying; Zhao, Yupeng; Pan, Guanghua; Wang, Guangce

    2012-07-01

    The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate (PHB) production were studied in batch cultures of the marine photosynthetic bacterium Rhodovulum sulfidophilum P5 under aerobic-dark conditions. The results show that the accumulation of PHB in strain P5 is a growth-associated process. Strain P5 had maximum biomass and PHB accumulation at 2%-3% NaCl, suggesting that the bacterium can maintain growth and potentially produce PHB at natural seawater salinity. In the nitrogen source test, the maximum biomass accumulation (8.10±0.09 g/L) and PHB production (1.11±0.13 g/L and 14.62%±2.2 of the cell dry weight) were observed when peptone and ammonium chloride were used as the sole nitrogen source. NH{4/+}-N was better for PHB production than other nitrogen sources. In the carbon source test, the maximum biomass concentration (7.65±0.05 g/L) was obtained with malic acid as the sole carbon source, whereas the maximum yield of PHB (5.03±0.18 g/L and 66.93%±1.69% of the cell dry weight) was obtained with sodium pyruvate as the sole carbon source. In the carbon to nitrogen ratios test, sodium pyruvate and ammonium chloride were selected as the carbon and nitrogen sources, respectively. The best carbon to nitrogen molar ratio for biomass accumulation (8.77±0.58 g/L) and PHB production (6.07±0.25 g/L and 69.25%±2.05% of the cell dry weight) was 25. The results provide valuable data on the production of PHB by R. sulfidophilum P5 and further studies are on-going for best cell growth and PHB yield.

  10. Flavobacterium arsenitoxidans sp. nov., an arsenite-oxidizing bacterium from Thai soil.

    PubMed

    Khianngam, Saowapar; Akaracharanya, Ancharida; Lee, Jung-Sook; Lee, Keun Chul; Kim, Kyoung-Woong; Tanasupawat, Somboon

    2014-12-01

    An arsenite-oxidizing bacterium, strain S2-3H(T), was isolated from arsenic-contaminated soil sample collected from Dantchaeng district, Suphanburi province, Thailand and was characterized based on polyphasic taxonomic study. The strain was observed to be a Gram-stain negative, aerobic, yellow pigmented, non-spore forming and rod-shaped bacterium. Major menaquinone was MK-6. Iso-C15:0, iso-C15:0 3OH, C16:1 ω7c/C16:1 ω6c, C16:0, iso-C17:0 3OH, and C16:0 3OH were the predominant cellular fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, unidentified phospholipids and unidentified aminophospholipids. The DNA G+C content was 37.0 mol%. Phylogenetic analysis using 16S rRNA sequence showed that strain S2-3H(T) is affiliated to the genus Flavobacterium, and is closely related to F. defluvii KCTC 12612(T) (97.0 %) and F. johnsoniae NBRC 14942(T) (97.0 %). The strain S2-3H(T) could be clearly distinguished from the related Flavobacterium species by its physiological and biochemical characteristics as well as its phylogenetic position and DNA-DNA relatedness. Therefore, the strain represents a novel species of the genus Flavobacterium, for which the name Flavobacterium arsenitoxidans sp. nov. (type strain S2-3H(T) = KCTC 22507(T) = NBRC 109607(T) = PCU 331(T) = TISTR 2238(T)) is proposed.

  11. Aerobic and two-stage anaerobic-aerobic sludge digestion with pure oxygen and air aeration.

    PubMed

    Zupancic, Gregor D; Ros, Milenko

    2008-01-01

    The degradability of excess activated sludge from a wastewater treatment plant was studied. The objective was establishing the degree of degradation using either air or pure oxygen at different temperatures. Sludge treated with pure oxygen was degraded at temperatures from 22 degrees C to 50 degrees C while samples treated with air were degraded between 32 degrees C and 65 degrees C. Using air, sludge is efficiently degraded at 37 degrees C and at 50-55 degrees C. With oxygen, sludge was most effectively degraded at 38 degrees C or at 25-30 degrees C. Two-stage anaerobic-aerobic processes were studied. The first anaerobic stage was always operated for 5 days HRT, and the second stage involved aeration with pure oxygen and an HRT between 5 and 10 days. Under these conditions, there is 53.5% VSS removal and 55.4% COD degradation at 15 days HRT - 5 days anaerobic, 10 days aerobic. Sludge digested with pure oxygen at 25 degrees C in a batch reactor converted 48% of sludge total Kjeldahl nitrogen to nitrate. Addition of an aerobic stage with pure oxygen aeration to the anaerobic digestion enhances ammonium nitrogen removal. In a two-stage anaerobic-aerobic sludge digestion process within 8 days HRT of the aerobic stage, the removal of ammonium nitrogen was 85%.

  12. Nitrification and aerobic denitrification in anoxic-aerobic sequencing batch reactor.

    PubMed

    Alzate Marin, Juan C; Caravelli, Alejandro H; Zaritzky, Noemí E

    2016-01-01

    The aim of this study was to evaluate the feasibility of achieving nitrogen (N) removal using a lab-scale sequencing batch reactor (SBR) exposed to anoxic/aerobic (AN/OX) phases, focusing to achieve aerobic denitrification. This process will minimize emissions of N2O greenhouse gas. The effects of different operating parameters on the reactor performance were studied: cycle duration, AN/OX ratio, pH, dissolved oxygen concentration (DOC), and organic load. The highest inorganic N removal (NiR), close to 70%, was obtained at pH=7.5, low organic load (440mgCOD/(Lday)) and high aeration given by 12h cycle, AN/OX ratio=0.5:1.0 and DOC higher than 4.0mgO2/L. Nitrification followed by high-rate aerobic denitrification took place during the aerobic phase. Aerobic denitrification could be attributed to Tetrad-forming organisms (TFOs) with phenotype of glycogen accumulating organisms using polyhydroxyalkanoate and/or glycogen storage. The proposed AN/OX system constitutes an eco-friendly N removal process providing N2 as the end product.

  13. Complete genome of Streptomyces hygroscopicus subsp. limoneus KCTC 1717 (=KCCM 11405), a soil bacterium producing validamycin and diverse secondary metabolites.

    PubMed

    Lee, Sang-Heon; Choe, Hanna; Bae, Kyung Sook; Park, Doo-Sang; Nasir, Arshan; Kim, Kyung Mo

    2016-02-10

    Streptomyces hygroscopicus subsp. limoneus is a Gram-positive, aerobic, aerial mycelial, spore-forming bacterium that was first isolated from a soil sample in Akashi City, Hyogo Prefecture, Japan. We here report the complete genome of S. hygroscopicus subsp. limoneus KCTC 1717 (=KCCM 11405=IFO 12704=ATCC 21432), which consists of 10,537,932 bp (G+C content of 71.96%) with two linear chromosomes, 8983 protein-coding genes, 67 tRNAs and 6 rRNA operons. Genes related to biosynthesis of validamycin, valienamine and diverse secondary metabolites were detected in this genome. Genomic data is thus expected to considerably improve our understanding of how industrially important aminocyclitols are biosynthesized by microbial cells.

  14. Noncontiguous finished genome sequence and description of Virgibacillus massiliensis sp. nov., a moderately halophilic bacterium isolated from human gut

    PubMed Central

    Khelaifia, S.; Croce, O.; Lagier, J.-C.; Robert, C.; Couderc, C.; Di Pinto, F.; Davoust, B.; Djossou, F.; Raoult, D.; Fournier, P.-E.

    2015-01-01

    Strain Vm-5T was isolated from the stool specimen of a 10-year-old Amazonian boy. This bacterium is a Gram-positive, strictly aerobic rod, motile by a polar flagellum. Here we describe its phenotypic characteristics and complete genome sequence. The 4 353 177 bp long genome exhibits a G + C content of 36.87% and contains 4394 protein-coding and 125 predicted RNA genes. Phylogenetically and genetically, strain Vm-c is a member of the genus Virgibacillus but is distinct enough to be classified as a new species. We propose the creation of V. massiliensis sp. nov., whose type strain is strain Vm-5T (CSUR P971 = DSM 28587). PMID:26649181

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification by various microorganisms. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathways. To determine representative SP values for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans. The SP value for NOR reaction (-5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2-) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for the NH2OH oxidation pathway possibly due to a small contribution of NO2- reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification in environmental nitrogen cycle by various microorganism. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathway. To determine representative SP value for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans, respectively. The SP value for NOR reaction (-5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2-) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for NH2OH oxidation pathway possibly due to a small contribution of NO2- reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

  17. Genome-enabled studies of anaerobic, nitrate-dependent iron oxidation in the chemolithoautotrophic bacterium Thiobacillus denitrificans

    PubMed Central

    Beller, Harry R.; Zhou, Peng; Legler, Tina C.; Chakicherla, Anu; Kane, Staci; Letain, Tracy E.; A. O’Day, Peggy

    2013-01-01

    Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV) and Fe(II) oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV) oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II) oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II)-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II) oxidation, namely (a) whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV) oxides as electron donors under denitrifying conditions], (b) Fe(II) oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c) random transposon-mutagenesis studies with screening for Fe(II) oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II) oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III), which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II) oxidation and to current concepts of reverse electron transfer. A transposon mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I) was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II) oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV) oxidation, nor have other c-type cytochromes yet been implicated in the process. PMID:24065960

  18. Characterization of the norCBQD genes, encoding nitric oxide reductase, in the nitrogen fixing bacterium Bradyrhizobium japonicum.

    PubMed

    Mesa, Socorro; Velasco, Leonardo; Manzanera, Maximino E; Delgado, María J; Bedmar, Eulogio J

    2002-11-01

    The genes norCBQD that encode the bc-type nitric oxide reductase from Bradyrhizobium japonicum USDA110 have been isolated and characterized. norC and norB encode the cytochrome c-containing subunit II and cytochrome b-containing subunit I of nitric oxide reductase, respectively. norQ encodes a protein with an ATP/GTP-binding motif, and the predicted norD gene product shows similarity with NorD from other denitrifiers. Mutational analysis indicates that the two structural norC and norB genes are required for microaerobic growth under nitrate-respiring conditions. A mutant strain lacking a functional norC gene also lacked the 16 kDa c-type cytochrome that is normally detectable by haem-staining of proteins from membranes of microaerobically grown wild-type cells. Expression of a transcriptional fusion of the nor promoter region to the reporter gene lacZ (P(norC)-lacZ) was not detected in aerobically grown cells of USDA110, but the fusion was induced threefold when the cells were cultured under microaerobic conditions (1% O(2)) with either nitrite or nitric oxide, and about 18-fold when nitrate was the N oxide present in the medium. The P(norC)-lacZ fusion was not expressed in the B. japonicum fixK(2) mutant strain 9043, but complementation of the mutant with the fixK(2) gene restored beta-galactosidase activity to levels similar to those found in the parental strain. The promoter region of the norCBQD genes has been characterized by primer extension. A major transcript initiates 45.5 bp downstream of the centre of a putative binding site for the transcription factor FixK(2).

  19. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR).

    PubMed

    Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

    2016-03-17

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10-50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera.

  20. A Doubling of Microphytobenthos Biomass Coincides with a Tenfold Increase in Denitrifier and Total Bacterial Abundances in Intertidal Sediments of a Temperate Estuary

    PubMed Central

    Decleyre, Helen; Heylen, Kim; Sabbe, Koen; Tytgat, Bjorn; Deforce, Dieter; Van Nieuwerburgh, Filip; Van Colen, Carl; Willems, Anne

    2015-01-01

    Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB) biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS) and competition for nutrients (including nitrogen). Pyrosequencing and qPCR was performed on two intertidal surface sediments of the Westerschelde estuary characterized by a two-fold difference in MPB biomass but no difference in MPB composition. Doubling of MPB biomass was accompanied by a disproportionately (ten-fold) increase in total bacterial abundances while, unexpectedly, no difference in general community structure was observed, despite significantly lower bacterial richness and distinct community membership, mostly for non-abundant taxa. Denitrifier abundances corresponded likewise while community structure, both for nirS and nirK denitrifiers, remained unchanged, suggesting that competition with diatoms for nitrate is negligible at concentrations in the investigated sediments (appr. 1 mg/l NO3-). This study indicates that MPB biomass increase has a general, significantly positive effect on total bacterial and denitrifier abundances, with stimulation or inhibition of specific bacterial groups that however do not result in a re-structured community. PMID:25961719

  1. Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land-use.

    PubMed

    Keil, Daniel; Niklaus, Pascal A; von Riedmatten, Lars R; Boeddinghaus, Runa S; Dormann, Carsten F; Scherer-Lorenzen, Michael; Kandeler, Ellen; Marhan, Sven

    2015-07-01

    Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity.

  2. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

    PubMed Central

    Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

    2016-01-01

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10–50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera. PMID:26983801

  3. Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

    NASA Astrophysics Data System (ADS)

    Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

    2016-03-01

    In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10–50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera.

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

    PubMed

    Depkat-Jakob, Peter S; Brown, George G; Tsai, Siu M; Horn, Marcus A; Drake, Harold L

    2013-02-01

    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.

  5. Characterizations of intracellular arsenic in a bacterium

    NASA Astrophysics Data System (ADS)

    Wolfe-Simon, F.; Yannone, S. M.; Tainer, J. A.

    2011-12-01

    Life requires a key set of chemical elements to sustain growth. Yet, a growing body of literature suggests that microbes can alter their nutritional requirements based on the availability of these chemical elements. Under limiting conditions for one element microbes have been shown to utilize a variety of other elements to serve similar functions often (but not always) in similar molecular structures. Well-characterized elemental exchanges include manganese for iron, tungsten for molybdenum and sulfur for phosphorus or oxygen. These exchanges can be found in a wide variety of biomolecules ranging from protein to lipids and DNA. Recent evidence suggested that arsenic, as arsenate or As(V), was taken up and incorporated into the cellular material of the bacterium GFAJ-1. The evidence was interpreted to support As(V) acting in an analogous role to phosphate. We will therefore discuss our ongoing efforts to characterize intracellular arsenate and how it may partition among the cellular fractions of the microbial isolate GFAJ-1 when exposed to As(V) in the presence of various levels of phosphate. Under high As(V) conditions, cells express a dramatically different proteome than when grown given only phosphate. Ongoing studies on the diversity and potential role of proteins and metabolites produced in the presence of As(V) will be reported. These investigations promise to inform the role and additional metabolic potential for As in biology. Arsenic assimilation into biomolecules contributes to the expanding set of chemical elements utilized by microbes in unusual environmental niches.

  6. Nitrite production in a partial denitrifying upflow sludge bed (USB) reactor equipped with gas automatic circulation (GAC).

    PubMed

    Cao, Shenbin; Li, Baikun; Du, Rui; Ren, Nanqi; Peng, Yongzhen

    2016-03-01

    Nitrite production in a partial denitrifying (NO3(-)-N→NO2(-)-N) upflow sludge bed (USB) reactor equipped with gas automatic circulation (GAC) was investigated at ambient temperature (28.8-14.1 °C). The nitrite production rate (NPR) increased with the nitrate loading rate (NLR). Average NPR of 6.63 kgN m(-3) d(-1) was obtained at 28.0 °C with the organic loading rate (OLR) and NLR of 25.38 KgCOD∙m(-3)∙d(-1) and 10.82 kgN m(-3) d(-1), respectively. However, serious sludge floatation was observed when the NLR increased to 13.18 kgN m(-3) d(-1), which might be attributed to sludge bulking at high NLR. The USB reactor recovered rapidly when seeded with the sludge discharged before the deteriorated period, and a stable NPR of ∼4.35 kgN m(-3) d(-1) was achieved at 14.1-15.7 °C in the following 100-day operation, during which the maximum nitrate-to-nitrite transformation ratio (NTR) of 81.4% was achieved at the GAC rate of 1.08 L h(-1). The application of GAC in the partial denitrifying USB reactor enhanced mass transfer, which effectively avoided the channel and dead space, and improved the nitrate transform to nitrite. Moreover, it was found that the GAC system played an important role in promoting the stability of the USB reactor by preventing the sludge floatation. The Illumina high-throughput sequencing analysis revealed that the genus of Thauera was dominate in the USB reactor (67.2-50.2%), which may be responsible for the high nitrite accumulation. Results in this study have an important application in treating nitrate wastewater with an economic and efficient way by combining with ANAMMOX process.

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

    PubMed

    Lee, Seung-Hoon; Kang, Hojeong

    2016-02-01

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

  8. [Rhodobaculum claviforme gen. nov., sp. nov., a New Alkaliphilic Nonsulfur Purple Bacterium].

    PubMed

    Bryantseva, I A; Gaisin, V A; Gorlenko, V M

    2015-01-01

    Two alkaliphilic strains of nonsulfur purple bacteria (NPB), B7-4 and B8-2, were isolated from southeast Siberia moderately saline alkaline steppe lakes with pH values above 9.0. The isolates were motile, polymorphous cells (from short rods to long spindly cells) 2.0-3.2 x 9.6-20.0 μm. Intracellular membranes of vesicular type were mostly located at the cell periphery. The microorganisms contained bacteriochlorophyll a and carotenoids of the spheroidene and spirilloxanthin series. The photosynthetic apparatus was represented by LH2 and LH1 light-harvesting complexes. In the presence of organic compounds, the strains grew aerobically in the dark or anaerobically in the light. Capacity for photo- and chemoautotrophic growth was not detected. The cbbl gene encoding RuBisCO was not revealed. Optimal growth of both strains occurred at 2% NaCl (range from 0.5 to 4%), pH 8.0-8.8 (range from 7.5 to 9.7), and 25-35 degrees C. The DNA G+C content was 67.6-69.8 mol %. Pairwise comparison of the nucleotides of the 16S rRNA genes revealed that strains B7-4 and B8-2 belonged to the same species (99.9% homology) and were most closely related to the aerobic alkaliphilic bacteriochlorophyll a-containing anoxygenic phototrophic bacterium (APB) Roseibacula alcaliphilum De (95.2%) and to NPB strains Rhodobaca barguzinensis VKM B-2406(T) (94.2%) and Rbc. bogoriensis LBB1(T) (93.9%). The isolates were closely related to the NPB Rhodobacter veldkampii DSM 11550(T) (94.8%) and to aerobic bacteriochlorophyll a-containing bacteria Roseinatronobacter monicus ROS 35(T) and Roseicitreum antarcticul ZS2-28(T) (93.5 and 93.9%, respectively). New strains were described as a new NPB genus and species of the family Rhodobacteriaceae, Rhodobaculum claviforme gen. nov., sp. nov., with B7-4(T) (VKM B-2708, LMG 28126) as the type strain.

  9. Bacillus coreaensis sp. nov.: a xylan-hydrolyzing bacterium isolated from the soil of Jeju Island, Republic of Korea.

    PubMed

    Chi, Won-Jae; Youn, Young Sang; Park, Jae-Seon; Hong, Soon-Kwang

    2015-07-01

    A xylan-degrading bacterium, designated as MS5(T) strain, was isolated from soil collected from the Jeju Island, Republic of Korea. Strain MS5(T) was Gram-stain-positive, aerobic, and motile by polar flagellum. The major fatty acids identified in this bacterium were iso-C15:0 (32.3%), C16:0 (27.3%), and anteiso-C15:0 (10.2%). A similarity search based on the 16S rRNA gene sequence revealed that the strain belongs to the class Bacilli and shared the highest similarity with the type strains Bacillus beringensis BR035(T) (98.7%) and Bacillus korlensis ZLC-26(T) (98.6%) which form a coherent cluster in a neighbor-joining phylogenetic tree. The DNA G+C content of strain MS5(T) was 43.0 mol%. The major menaquinone was MK-7 and the diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The DNADNA relatedness values between strain MS5(T) and two closely related species, B. beringensis BR035(T) and B. korlensis ZLC-26(T), were less than 70%. DNA-DNA relatedness analysis and 16S rRNA sequence similarity, as well as phenotypic and chemotaxonomic characteristics suggest that the strain MS5(T) constitutes a novel Bacillus species, for which the name Bacillus coreaensis sp. nov. is proposed. The type strain is MS5(T) (=DSM25506(T) =KCTC13895(T)).

  10. Gene function analysis in environmental isolates: The nif regulon of the strict iron oxidizing bacterium Leptospirillum ferrooxidans

    PubMed Central

    Parro, Víctor; Moreno-Paz, Mercedes

    2003-01-01

    A random genomic library from an environmental isolate of the Gram-negative bacterium Leptospirillum ferrooxidans has been printed on a microarray. Gene expression analysis was carried out with total RNA extracted from L. ferrooxidans cultures in the presence or absence of ammonium as nitrogen source under aerobic conditions. Although practically nothing is known about the genome sequence of this bacterium, this approach allowed us the selection and sequencing of only those clones bearing genes that showed an altered expression pattern. By sequence comparison, we have identified most of the genes of nitrogen fixation regulon in L. ferrooxidans, like the nifHDKENX operon, encoding the structural components of Mo-Fe nitrogenase; nifSU-hesB-hscBA-fdx operon, for Fe-S cluster assembly; the amtB gene (ammonium transporter); modA (molybdenum ABC type transporter); some regulatory genes like ntrC, nifA (the specific activator of nif genes); or two glnB-like genes (encoding the PII regulatory protein). Our results show that shotgun DNA microarrays are very powerful tools to accomplish gene expression studies with environmental bacteria whose genome sequence is still unknown, avoiding the time and effort necessary for whole genome sequencing projects. PMID:12808145

  11. Isolation and characterization of a bacterium capable of removing taste- and odor-causing 2-methylisoborneol from water.

    PubMed

    Lauderdale, Chance V; Aldrich, Henry C; Lindner, Angela S

    2004-11-01

    2-Methylisoborneol (MIB), a metabolite of blue-green algae, has been implicated in causing unpalatable drinking water throughout the world. Current non-biological water treatment technologies are ineffective in removing MIB from potable water or are cost-prohibitive, and biological applications may address these problems. We have isolated and characterized a bacterium derived from lake water and capable of aerobically degrading MIB. Light microscopy and transmission electron microscopy revealed that this strain is a spore-forming, flagellated bacterium that is bacilloid in shape, and 16S rRNA phylogenetic analysis determined that it is most closely related to Bacillus fusiformis and Bacillus sphaericus, both members of the Bacillus sphaericus senso lato taxon. While the growth and oxidation potential of this strain was shown to be affected beyond certain MIB concentrations in the mg/l range, it was capable of depleting MIB at mg/l and ng/l concentrations and of removing MIB to concentrations yielding no observed odor.

  12. Legacy effects of simulated short-term climate change on ammonia oxidisers, denitrifiers, and nitrous oxide emissions in an acid soil.

    PubMed

    Xu, Xiaoya; Liu, Xiaorui; Li, Yong; Ran, Yu; Liu, Yapeng; Zhang, Qichun; Li, Zheng; He, Yan; Xu, Jianming; Di, Hongjie

    2017-03-21

    Although the effect of simulated climate change on nitrous oxide (N2O) emissions and on associated microbial communities has been reported, it is not well understood if these effects are short-lived or long-lasting. Here, we conducted a field study to determine the interactive effects of simulated warmer and drier conditions on nitrifier and denitrifier communities and N2O emissions in an acidic soil and the longevity of the effects. A warmer (+2.3 °C) and drier climate (-7.4% soil moisture content) was created with greenhouses. The variation of microbial population abundance and community structure of ammonia-oxidizing archaea (AOA), bacteria (AOB), and denitrifiers (nirK/S, nosZ) were determined using real-time PCR and high-throughput sequencing. The results showed that the simulated warmer and drier conditions under the greenhouse following urea application significantly increased N2O emissions. There was also a moderate legacy effect on the N2O emissions when the greenhouses were removed in the urea treatment, although this effect only lasted a short period of time (about 60 days). The simulated climate change conditions changed the composition of AOA with the species affiliated to marine group 1.1a-associated lineage increasing significantly. The abundance of all the functional denitrifier genes decreased significantly under the simulated climate change conditions and the legacy effect, after the removal of greenhouses, significantly increased the abundance of AOB, AOA (mainly the species affiliated to marine group 1.1a-associated lineage), and nirK and nosZ genes in the urea-treated soil. In general, the effect of the simulated climate change was short-lived, with the denitrifier communities being able to return to ambient levels after a period of adaptation to ambient conditions. Therefore, the legacy effect of simulated short-time climate change conditions on the ammonia oxidizer and denitrifier communities and N2O emissions were temporary and once the

  13. [Sulfa-drug wastewater treatment with anaerobic/aerobic process].

    PubMed

    Wu, L; Zhang, H; Zhu, H; Zhang, Z; Zhuang, Y; Dai, S

    2001-09-01

    Sulfa drug wastewater was treated with anaerobic/aerobic process. The removal ratios of TOC reached about 50% in anaerobic phase and about 70% in aerobic phase respectively, while volume loading rate of TOC was about 1.2 kg/(m3.d) in anaerobic phase and about 0.6 kg/(m3.d) in aerobic phase. Removal of TOC in anaerobic phase was attributed to the reduction of sulfate.

  14. [Cardiovascular protection and mechanisms of actions of aerobic exercise].

    PubMed

    Hou, Zuo-Xu; Zhang, Yuan; Gao, Feng

    2014-08-01

    It is well established that aerobic exercise exerts beneficial effect on cardiovascular system, but the underlying mechanisms are yet to be elucidated. Recent studies have shown that aerobic exercise ameliorates insulin resistance, inflammation and mitochondrial dysfunction which play important roles in the development of cardiovascular disease. In this review, we discussed the underlying mechanisms of the cardioprotective role of aerobic exercise, especially the latest progress in this field.

  15. [Influences of long-term application of organic and inorganic fertilizers on the composition and abundance of nirS-type denitrifiers in black soil].

    PubMed

    Yin, Chang; Fan, Fen-Liang; Li, Zhao-Jun; Song, A-Lin; Zhu, Ping; Peng, Chang; Liang, Yong-Chao

    2012-11-01

    The objectives of this study were to explore the effects of long-term organic and inorganic fertilizations on the composition and abundance of nirS-type denitrifiers in black soil. Soil samples were collected from 4 treatments (i. e. no fertilizer treatment, CK; organic manure treatment, OM; chemical fertilizer treatment (NPK) and combination of organic and chemical fertilizers treatment (MNPK)) in Gongzhuling Long-term Fertilization Experiment Station. Composition and abundance of nirS-type denitrifiers were analyzed with terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR (Q-PCR), respectively. Denitrification enzyme activity (DEA) and soil properties were also measured. Application of organic fertilizers (OM and MNPK) significantly increased the DEAs of black soil, with the DEAs in OM and MNPK being 5.92 and 6.03 times higher than that in CK treatment, respectively, whereas there was no significant difference between NPK and CK. OM and MNPK treatments increased the abundances of nirS-type denitrifiers by 2.73 and 3.83 times relative to that of CK treatment, respectively. The abundance of nirS-type denitrifiers in NPK treatment was not significantly different from that of CK. The T-RFLP analysis of nirS genes showed significant differences in community composition between organic and inorganic treatments, with the emergence of a 79 bp T-RF, a significant decrease in relative abundance of the 84 bp T-RF and a loss of the 99 bp T-RF in all organic treatments. Phylogenetic analysis indicated that the airS-type denitrifiers in the black soil were mainly composed of alpha, beta and gamma-Proteobacteria. The 79 bp-type denitrifiers inhabiting exclusively in organic treatments (OM and MNPK) were affiliated to Pseudomonadaceae in gamma-Proteobacteria and Burkholderiales in beta-Proteobacteria. The 84 bp-types were related to Burkholderiales and Rhodocyclales. Correlation analysis indicated that pH, concentrations of total nitrogen

  16. Biotransformation of phytosterols under aerobic conditions.

    PubMed

    Dykstra, Christy M; Giles, Hamilton D; Banerjee, Sujit; Pavlostathis, Spyros G

    2014-07-01

    Phytosterols are plant-derived sterols present in pulp and paper wastewater and have been implicated in the endocrine disruption of aquatic species. Bioassays were performed to assess the effect of an additional carbon source and/or solubilizing agent on the aerobic biotransformation of a mixture of three common phytosterols (β-sitosterol, stigmasterol and campesterol). The aerobic biotransformation of the phytosterol mixture by a mixed culture developed from a pulp and paper wastewater treatment system was examined under three separate conditions: with phytosterols as the sole added carbon source, with phytosterols and dextrin as an additional carbon source, and with phytosterols added with ethanol as an additional carbon source and solubilizing agent. Significant phytosterol removal was not observed in assays set up with phytosterol powder, either with or without an additional carbon source. In contrast, all three phytosterols were aerobically degraded when added as a dissolved solution in ethanol. Thus, under the experimental conditions of this study, the bioavailability of phytosterols was limited without the presence of a solubilizing agent. The total phytosterol removal rate was linear for the first six days before re-spiking, with a rate of 0.47 mg/L-d (R(2) = 0.998). After the second spiking, the total phytosterol removal rate was linear for seven days, with a rate of 0.32 mg/L-d (R(2) = 0.968). Following the 7th day, the phytosterol removal rate markedly accelerated, suggesting two different mechanisms are involved in phytosterol biotransformation, more likely related to the production of enzyme(s) involved in phytosterol degradation, induced under different cell growth conditions. β-sitosterol was preferentially degraded, as compared to stigmasterol and campesterol, although all three phytosterols fell below detection limits by the 24th day of incubation.

  17. Aerobic Capacity and Postprandial Flow Mediated Dilation.

    PubMed

    Ballard, Kevin D; Miller, James J; Robinson, James H; Olive, Jennifer L

    The consumption of a high-fat meal induces transient vascular dysfunction. Aerobic exercise enhances vascular function in healthy individuals. Our purpose was to determine if different levels of aerobic capacity impact vascular function, as measured by flow mediated dilation, following a high-fat meal. Flow mediated dilation of the brachial artery was determined before, two- and four-hours postprandial a high-fat meal in young males classified as highly trained (n = 10; VO2max = 74.6 ± 5.2 ml·kg·min(-1)) or moderately active (n = 10; VO2max = 47.3 ± 7.1 ml·kg·min(-1)). Flow mediated dilation was reduced at two- (p < 0.001) and four-hours (p < 0.001) compared to baseline for both groups but was not different between groups at any time point (p = 0.108). Triglycerides and insulin increased at two- (p < 0.001) and four-hours (p < 0.05) in both groups. LDL-C was reduced at four-hours (p = 0.05) in highly trained subjects, and two- and four-hours (p ≤ 0.01) in moderately active subjects. HDL-C decreased at two- (p = 0.024) and four-hours (p = 0.014) in both groups. Glucose increased at two-hours postprandial for both groups (p = 0.003). Our results indicate that a high-fat meal results in reduced endothelium-dependent vasodilation in highly trained and moderately active individuals with no difference between groups. Thus, high aerobic capacity does not protect against transient reductions in vascular function after the ingestion of a single high-fat meal compared to individuals who are moderately active.

  18. Design and evaluation of primers targeting genes encoding NO-forming nitrite reductases: implications for ecological inference of denitrifying communities

    PubMed Central

    Bonilla-Rosso, Germán; Wittorf, Lea; Jones, Christopher M.; Hallin, Sara

    2016-01-01

    The detection of NO-forming nitrite reductase genes (nir) has become the standard when studying denitrifying communities in the environment, despite well-known amplification biases in available primers. We review the performance of 35 published and 121 newly designed primers targeting the nirS and nirK genes, against sequences from complete genomes and 47 metagenomes from three major habitats where denitrification is important. There were no optimal universal primer pairs for either gene, although published primers targeting nirS displayed up to 75% coverage. The alternative is clade-specific primers, which show a trade-off between coverage and specificity. The test against metagenomic datasets showed a distinct performance of primers across habitats. The implications of clade-specific nir primers choice and their performance for ecological inference when used for quantitative estimates and in sequenced-based community ecology studies are discussed and our phylogenomic primer evaluation can be used as a reference along with their environmental specificity as a guide for primer selection. Based on our results, we also propose a general framework for primer evaluation that emphasizes the testing of coverage and phylogenetic range using full-length sequences from complete genomes, as well as accounting for environmental range using metagenomes. This framework serves as a guideline to simplify primer performance comparisons while explicitly addressing the limitations and biases of the primers evaluated. PMID:27966627

  19. Nitrogen source effects on the denitrifying anaerobic methane oxidation culture and anaerobic ammonium oxidation bacteria enrichment process.

    PubMed

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

    2017-02-06

    The co-culture system of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) has a potential application in wastewater treatment plant. This study explored the effects of permutation and combination of nitrate, nitrite, and ammonium on the culture enrichment from freshwater sediments. The co-existence of NO3(-), NO2(-), and NH4(+) shortened the enrichment time from 75 to 30 days and achieved a total nitrogen removal rate of 106.5 mg/L/day on day 132. Even though ammonium addition led to Anammox bacteria increase and a higher nitrogen removal rate, DAMO bacteria still dominated in different reactors with the highest proportion of 64.7% and the maximum abundance was 3.07 ± 0.25 × 10(8) copies/L (increased by five orders of magnitude) in the nitrite reactor. DAMO bacteria showed greater diversity in the nitrate reactor, and one was similar to M. oxyfera; DAMO bacteria in the nitrite reactor were relatively unified and similar to M. sinica. Interestingly, no DAMO archaea were found in the nitrate reactor. This study will improve the understanding of the impact of nitrogen source on DAMO and Anammox co-culture enrichment.

  20. Pollutant removal characteristics of a two-influent-line BNR process performing denitrifying phosphorus removal: role of sludge recycling ratios.

    PubMed

    Liu, Hongbo; Leng, Feng; Chen, Piao; Kueppers, Stephan

    2016-11-01

    This paper studied denitrifying phosphorus removal of a novel two-line biological nutrient removal process treating low strength domestic wastewater under different sludge recycling ratios. Mass balance of intracellular compounds including polyhydroxyvalerate, polyhydroxybutyrate and glycogen was investigated together with total nitrogen (TN) and total phosphorus (TP). Results showed that sludge recycling ratios had a significant influence on the use of organics along bioreactors and 73.6% of the average removal efficiency was obtained when the influent chemical oxygen demand (COD) ranged from 175.9 mgL(-1) to 189.9 mgL(-1). The process performed better under a sludge recycling ratio of 100% compared to 25% and 50% in terms of ammonia and COD removal rates. Overall, TN removal efficiency for 50% and 100% sludge recycling ratios were 56.4% and 61.9%, respectively, unlike the big gap for carbon utilization and the TP removal rates, indicating that the effect of sludge recycling ratio on the anaerobic compartments had been counteracted by change in the efficiency of other compartments. The higher ratio of sludge recycling was conducive to the removal of TN, not in favor of TP, and less influence on COD. Thus, 25% was considered to be the optimal sludge recycling ratio.

  1. [Characteristics of soil denitrifying enzyme activity in riparian zones with different land use types in Chongming Island, Shanghai of China].

    PubMed

    Chen, Gang-Liang; Li, Jian-Hua; Yang, Chang-Ming

    2013-10-01

    By using acetylene inhibition method, this paper studied the soil denitrifying enzyme activity (DEA) and its affecting factors in the riparian zone with different land use types (cropland riparian, forested riparian, and grassy riparian zones) in Chongming Island, Shanghai of China. The riparian soil DEA was (0.69 +/- 0.11)--(134.93 +/- 33.72) microg N x kg(-1) x h(-1), which differed obviously among different land types, with a decreasing trend of forested riparian zone > cropland riparian zone > grassy riparian zone. The soil DEA was significantly (P < 0.05) higher in 0-10 cm in 10-30, 30-50, and 50-70 cm layers. There were significant positive relationships between soil DEA and soil TOC, TN, and NO(3-)-N (P < 0.01). Land use change mainly altered the soil natural structure and soil physical and chemical properties, decreased the accumulation of soil organic carbon, and affected the soil nitrogen transformation, and thus, inhibited the occurrence of riparian soil denitrification.

  2. Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor.

    PubMed

    Hwang, C; Wu, W-M; Gentry, T J; Carley, J; Carroll, S L; Schadt, C; Watson, D; Jardine, P M; Zhou, J; Hickey, R F; Criddle, C S; Fields, M W

    2006-08-01

    High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n = 500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.

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

    PubMed

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

    2016-01-01

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

  4. Simultaneous enrichment of denitrifying anaerobic methane-oxidizing microorganisms and anammox bacteria in a hollow-fiber membrane biofilm reactor.

    PubMed

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

    2017-01-01

    In this study, the coculture system of denitrifying anaerobic methane oxidation (DAMO) microbes and anaerobic ammonium oxidation (anammox) bacteria was successfully enriched in a hollow-fiber membrane biofilm reactor (HfMBR) using freshwater sediment as the inoculum. The maximal removal rates of nitrate and ammonium were 78 mg N/L/day (131 mg N/m(2)/day) and 26 mg N/L/day (43 mg N/m(2)/day), respectively. Due to the high rate of methane mass transfer in HfMBR, the activity of DAMO archaea continued to increase during the enrichment period, indicating that HfMBR could be a powerful tool to enrich DAMO microorganisms. Effects of partial methane pressure, temperature, and pH on the cocultures were obvious. However, the microbial activity in HfMBR could be recovered quickly after the shock change of environmental factors. Furthermore, the result also found that DAMO bacteria likely had a stronger competitive advantage than anammox bacteria under the operating conditions in this study. High-throughput sequencing 16S rRNA genes illustrated that the dominant microbes were NC10, Euryarchaeota, Proteobacteria, Planctomycetes, and Chlorobi with relative abundance of 38.8, 26.2, 13.78, 6.2, and 3.6 %, respectively.

  5. A laboratory investigation of interactions between denitrifying anaerobic methane oxidation (DAMO) and anammox processes in anoxic environments.

    PubMed

    Hu, Shihu; Zeng, Raymond J; Haroon, Mohamed F; Keller, Jurg; Lant, Paul A; Tyson, Gene W; Yuan, Zhiguo

    2015-03-03

    This study investigates interactions between recently identified denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (anammox) processes in controlled anoxic laboratory reactors. Two reactors were seeded with the same inocula containing DAMO organisms Candidatus Methanoperedens nitroreducens and Candidatus Methylomirabilis oxyfera, and anammox organism Candidatus Kuenenia stuttgartiensis. Both were fed with ammonium and methane, but one was also fed with nitrate and the other with nitrite, providing anoxic environments with different electron acceptors. After steady state reached in several months, the DAMO process became solely/primarily responsible for nitrate reduction while the anammox process became solely responsible for nitrite reduction in both reactors. 16S rRNA gene amplicon sequencing showed that the nitrate-driven DAMO organism M. nitroreducens dominated both the nitrate-fed (~70%) and the nitrite-fed (~26%) reactors, while the nitrite-driven DAMO organism M. oxyfera disappeared in both communities. The elimination of M. oxyfera from both reactors was likely the results of this organism being outcompeted by anammox bacteria for nitrite. K. stuttgartiensis was detected at relatively low levels (1-3%) in both reactors.

  6. High efficiency of inorganic nitrogen removal by integrating biofilm-electrode with constructed wetland: Autotrophic denitrifying bacteria analysis.

    PubMed

    Wang, Junfeng; Wang, Yuhui; Bai, Junhong; Liu, Zhaowei; Song, Xinshan; Yan, Dengming; Abiyu, Asaminew; Zhao, Zhimiao; Yan, Denghua

    2017-03-01

    The constructed wetland coupled with biofilm-electrode reactor (CW-BER) is a novel technology to treat wastewater with a relatively high level of total inorganic nitrogen (TIN) concentration. The main objective of this study is to investigate the effects of C/Ns, TIN concentrations, current intensities, and pH on the removal of nitrogen in CW-BER; a control system (CW) was also constructed and operated with similar influent conditions. Results indicated that the current, inorganic carbon source and hydrogen generated by the micro-electric field could significantly improve the inorganic nitrogen removal with in CW-BER, and the enhancement of average removal rate on NH3-N, NO3-N, and TIN was approximately maintained at 5-28%, 5-26%, and 3-24%, respectively. The appropriate operation conditions were I=10mA and pH=7.5 in CW-BER. In addition, high-throughput sequencing analysis implied that the CW-BER reactor has been improved with the relative abundance of autotrophic denitrifying bacteria (Thiobacillus sp.).

  7. Pangenome Evolution in the Marine Bacterium Alteromonas

    PubMed Central

    López-Pérez, Mario; Rodriguez-Valera, Francisco

    2016-01-01

    We have examined a collection of the free-living marine bacterium Alteromonas genomes with cores diverging in average nucleotide identities ranging from 99.98% to 73.35%, i.e., from microbes that can be considered members of a natural clone (like in a clinical epidemiological outbreak) to borderline genus level. The genomes were largely syntenic allowing a precise delimitation of the core and flexible regions in each. The core was 1.4 Mb (ca. 30% of the typical strain genome size). Recombination rates along the core were high among strains belonging to the same species (37.7–83.7% of all nucleotide polymorphisms) but they decreased sharply between species (18.9–5.1%). Regarding the flexible genome, its main expansion occurred within the boundaries of the species, i.e., strains of the same species already have a large and diverse flexible genome. Flexible regions occupy mostly fixed genomic locations. Four large genomic islands are involved in the synthesis of strain-specific glycosydic receptors that we have called glycotypes. These genomic regions are exchanged by homologous recombination within and between species and there is evidence for their import from distant taxonomic units (other genera within the family). In addition, several hotspots for integration of gene cassettes by illegitimate recombination are distributed throughout the genome. They code for features that give each clone specific properties to interact with their ecological niche and must flow fast throughout the whole genus as they are found, with nearly identical sequences, in different species. Models for the generation of this genomic diversity involving phage predation are discussed. PMID:27189983

  8. Aurantibacter crassamenti gen. nov., sp. nov., a bacterium isolated from marine sediment.

    PubMed

    Yoon, Jaewoo; Kasai, Hiroaki

    2017-01-01

    A Gram-stain-negative, strictly aerobic, orange-colored, rod-shaped, chemoheterotrophic bacterium, designated HG732(T), was isolated from marine sediment in Japan. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the novel marine strain was affiliated with the family Flavobacteriaceae of the phylum Bacteroidetes and that it shared the highest (94.1 %) sequence similarity with Kriegella aquimaris KMM 3665(T). The strain could be differentiated phenotypically from related members of the family Flavobacteriaceae. Major fatty acids of strain HG732(T) were iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH. The polar lipid profile consisted of phosphatidylglycerol, three unidentidied aminolipids and two unidentified lipids. The DNA G+C content of the strain was determined to be 35.2 mol%, and the major respiratory quinone was identified as menaquinone 6 (MK-6). From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus in the family Flavobacteriaceae, for which the name Aurantibacter crassamenti gen. nov., sp. nov. is proposed. The type strain of A. crassamenti gen. nov., sp. nov. is HG732(T) (= KCTC 52207(T) = NBRC 112211(T)).

  9. Sphingomonas psychrolutea sp. nov., a psychrotolerant bacterium isolated from glacier ice.

    PubMed

    Liu, Qing; Liu, Hong-Can; Zhang, Jian-Li; Zhou, Yu-Guang; Xin, Yu-Hua

    2015-09-01

    A Gram-stain-negative, rod-shaped, orange bacterium (strain MDB1-A(T)) was isolated from ice samples collected from Midui glacier in Tibet, south-west China. Cells were aerobic and psychrotolerant (growth occurred at 0-25 °C). Phylogenetic analysis based on 16S rRNA gene sequences showed that it was a member of the genus Sphingomonas, with its closest relative being Sphingomonas glacialis C16y(T) (98.9% similarity). Q-10 was the predominant ubiquinone. C17 : 1ω6c and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) were the major cellular fatty acids. The predominant polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and sphingoglycolipid. The polyamines detected were sym-homospermidine, spermidine and spermine. The G+C content of the genomic DNA was 63.6%. Based on data from this polyphasic analysis, strain MDB1-A(T) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas psychrolutea sp. nov. is proposed. The type strain is MDB1-A(T) ( = CGMCC 1.10106(T) = NBRC 109639(T)).

  10. Bacillus seohaeanensis sp. nov., a halotolerant bacterium that contains L-lysine in its cell wall.

    PubMed

    Lee, Jae-Chan; Lim, Jee-Min; Park, Dong-Jin; Jeon, Che Ok; Li, Wen-Jun; Kim, Chang-Jin

    2006-08-01

    A halotolerant, round-endospore-forming, aerobic, Gram-positive bacterium, designated BH724(T), was isolated from a solar saltern at Taean in Korea. Cells of this strain were rod-shaped and found to be non-motile. Strain BH724(T) grew at salinities of 0-10 % (w/v) NaCl with an optimum of 3 % (w/v) NaCl and at temperatures of 15-50 degrees C with an optimum of 40 degrees C. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BH724(T) belonged to the genus Bacillus and that Bacillus aquimaris TF-12(T), Bacillus marisflavi TF-11(T) and Bacillus vietnamensis JCM 11124(T) were its closest neighbours, sharing 97.3, 97.2 and 97.0 % 16S rRNA gene sequence similarity, respectively. The genomic DNA G+C content was 39 mol% and the predominant menaquinone was MK-7. Its major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0), iso-C(16 : 0) and iso-C(14 : 0). The peptidoglycan type was A1alpha, linked directly through l-lysine. On the basis of morphological, chemotaxonomic, physiological and phylogenetic properties, strain BH724(T) represents a novel species of the genus Bacillus, for which the name Bacillus seohaeanensis sp. nov. is proposed. The type strain is BH724(T) (=KCTC 3913(T)=DSM 16464(T)).

  11. Lysinibacillus tabacifolii sp. nov., a novel endophytic bacterium isolated from Nicotiana tabacum leaves.

    PubMed

    Duan, Yan-Qing; He, Song-Tao; Li, Qing-Qing; Wang, Ming-Feng; Wang, Wen-Yuan; Zhe, Wei; Cao, Yong-Hong; Mo, Ming-He; Zhai, Yu-Long; Li, Wen-Jun

    2013-06-01

    A Gram-positive, catalase- and oxidase-positive, strictly aerobic, endospore-forming rod bacterium, designated K3514(T), was isolated from the leaves of Nicotiana tabacum. The strain was able to grow at temperatures of 8-40°C, pH 5.0-10.0 and NaCl concentrations of 0-7%. The predominant quinones (>30%) of this strain were MK-7(H2) and MK-7. Phylogenetic analysis of 16S rRNA gene sequence showed that strain K3514(T) was affiliated to the genus Lysinibacillus, with its closest relatives being Lysinibacillus mangiferihumi (98.3% sequence similarity), Lysinibacillus sphaericus (97.9% sequence similarity), Lysinibacillus fusiformis (97.4% sequence similarity), and Lysinibacillus xylanilyticus (97.3% sequence similarity). However, low levels of DNA-DNA relatedness values suggested that the isolate was distinct from the other closest Lysinibacillus species. Additionally, based on analysis of morphological, physiological, and biochemical characteristics, the isolate could be differentiated from the closest known relatives. Therefore, based on polyphasic taxonomic data, the novel isolate likely represents a novel species, for which the name Lysinibacillus tabacifolii sp. nov. and the type strain K3514(T) (=KCTC 33042(T) =CCTCC AB 2012050(T)) are proposed.

  12. Genome reduction in an abundant and ubiquitous soil bacterium 'Candidatus Udaeobacter copiosus'.

    PubMed

    Brewer, Tess E; Handley, Kim M; Carini, Paul; Gilbert, Jack A; Fierer, Noah

    2016-10-31

    Although bacteria within the Verrucomicrobia phylum are pervasive in soils around the world, they are under-represented in both isolate collections and genomic databases. Here, we describe a single verrucomicrobial group within the class Spartobacteria that is not closely related to any previously described taxa. We examined more than 1,000 soils and found this spartobacterial phylotype to be ubiquitous and consistently one of the most abundant soil bacterial phylotypes, particularly in grasslands, where it was typically the most abundant. We reconstructed a nearly complete genome of this phylotype from a soil metagenome for which we propose the provisional name 'Candidatus Udaeobacter copiosus'. The Ca. U. copiosus genome is unusually small for a cosmopolitan soil bacterium, estimated by one measure to be only 2.81 Mbp, compared to the predicted effective mean genome size of 4.74 Mbp for soil bacteria. Metabolic reconstruction suggests that Ca. U. copiosus is an aerobic heterotroph with numerous putative amino acid and vitamin auxotrophies. The large population size, relatively small genome and multiple putative auxotrophies characteristic of Ca. U. copiosus suggest that it may be undergoing streamlining selection to minimize cellular architecture, a phenomenon previously thought to be restricted to aquatic bacteria. Although many soil bacteria need relatively large, complex genomes to be successful in soil, Ca. U. copiosus appears to use an alternative strategy, sacrificing metabolic versatility for efficiency to become dominant in the soil environment.

  13. Paenibacillus pinihumi sp. nov., a cellulolytic bacterium isolated from the rhizosphere of Pinus densiflora.

    PubMed

    Kim, Byung-Chun; Lee, Kang Hyun; Kim, Mi Na; Kim, Eun-Mi; Rhee, Moon-Soo; Kwon, O-Yu; Shin, Kee-Sun

    2009-10-01

    A novel cellulolytic bacterium, strain S23(T), was isolated from the rhizosphere of the pine trees in Daejeon, Republic of Korea. This isolate was Gram-positive, strictly aerobic, rod-shaped, catalase-negative, oxidase-positive, motile by means of peritrichous flagella, and tested positive for alkaline phosphatase, esterase lipase, leucine arylamidase, alpha-galactosidase, and beta-galactosidase activities. The DNA G+C content was 49.5 mol%. The main cellular fatty acids were anteiso-C(15:0) (51.9%), iso-C(16:0) (14.7%), and iso-C(15:0) (13.2%). The major isoprenoid quinone was menaquinone 7 (MK-7). Diagnostic diamino acid in the cell-wall pepti-doglycan was meso-diaminopimelic acid. Comparative 16S rRNA gene sequence analysis showed that this strain clustered with Paenibacillus species. The 16S rRNA gene sequence similarity values between S23(T) and other Paenibacillus species were between 89.9% and 95.9%, and S23(T) was most closely related to Paenibacillus tarimensis SA-7-6(T). On the basis of phylogenetic and phenotypic properties of strain S23(T), the isolate is considered as a novel species belonging to the genus Paenibacillus. Therefore, the name, Paenibacillus pinihumi sp. nov., is proposed for the rhizosphere isolate; the type strain is S23(T) (=KCTC 13695(T) =KACC 14199(T) =JCM 16419(T)).

  14. Paenibacillus puernese sp. nov., a β-glucosidase-producing bacterium isolated from Pu'er tea.

    PubMed

    Wang, Dan-Dan; Kim, Yeon-Ju; Hoang, Van-An; Nguyen, Ngoc-Lan; Singh, Priyanka; Wang, Chao; Chun-Yang, Deok

    2016-04-01

    A Gram-staining-positive, endospore-forming, aerobic, rod-shaped bacterium, designated as DCY97(T), was isolated from ripened Pu'er tea and was identified by using a polyphasic approach. 16S rRNA gene sequence analysis showed that strain DCY97(T) was closely related to Paenibacillus dongdonensis KUDC0114(T) (98.0 %), Paenibacillus oceanisediminis L10(T) (97.7 %), and Paenibacillus barcinonensis BP-23(T) (97.2 %). The phenotypic and chemotaxonomic characteristics of strain DCY97(T) matched with the characteristics of members belonging to the genus Paenibacillus. The major identified polar lipids included phosphatidylglycerol, phosphatidylethanolamine, and diphosphatidylglycerol. The predominant quinone was MK-7. The major fatty acids were anteiso-C15:0 (35.1 %), anteiso-C16:0 (19.0 %), and iso-C16:0 (13.9 %). The peptidoglycan cell wall was composed of meso-diaminopimelic acids, alanine, and D-glutamic acid. The genomic DNA G + C content was determined to be 46.7 mol%. The DNA-DNA relatedness between strain DCY97(T) and Paenibacillus dongdonensis KCTC 33221(T), Paenibacillus oceanisediminis KACC 16023(T), Paenibacillus barcinonensis KCTC 13019(T) were 27, 19, and 10 %, respectively. Based on the genotypic, phenotypic, and chemotaxonomic characteristics, strain DCY97(T) is considered as a novel species of the genus Paenibacillus, for which the name Paenibacillus puernese sp. nov. is proposed. The type strain is DCY97(T) (=KCTC 33596(T) = JCM 140369(T)).

  15. Pseudomonas glareae sp. nov., a marine sediment-derived bacterium with antagonistic activity.

    PubMed

    Romanenko, Lyudmila A; Tanaka, Naoto; Svetashev, Vassilii I; Mikhailov, Valery V

    2015-06-01

    An aerobic, Gram-negative, motile, rod-shaped bacterium designated KMM 9500(T) was isolated from a sediment sample collected from the Sea of Japan seashore. Comparative 16S rRNA gene sequence analysis affiliated strain KMM 9500(T) to the genus Pseudomonas as a distinct subline clustered with Pseudomonas marincola KMM 3042(T) and Pseudomonas segetis KCTC 12331(T) sharing the highest similarities of 98 and 97.9 %, respectively. Strain KMM 9500(T) was characterized by mainly possessing ubiquinone Q-9, and by the predominance of C18:1 ω7c, C16:1 ω7c, and C16:0 followed by C12:0 in its fatty acid profile. Polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an unknown aminophospholipid, and unknown phospholipids. Strain KMM 9500(T) was found to inhibit growth of Gram-negative and Gram-positive indicatory microorganisms. Based on the phylogenetic analysis and distinctive phenotypic characteristics, strain 9500(T) is concluded to represent a novel species of the genus Pseudomonas, for which the name Pseudomonas glareae sp. nov. is proposed. The type strain of the species is strain KMM 9500(T) (=NRIC 0939(T)).

  16. Melghiribacillus thermohalophilus gen. nov., sp. nov., a novel filamentous, endospore-forming, thermophilic and halophilic bacterium.

    PubMed

    Addou, Nariman Ammara; Schumann, Peter; Spröer, Cathrin; Ben Hania, Wajdi; Hacene, Hocine; Fauque, Guy; Cayol, Jean-Luc; Fardeau, Marie-Laure

    2015-04-01

    A novel filamentous, endospore-forming, thermophilic and moderately halophilic bacterium designated strain Nari2A(T) was isolated from soil collected from an Algerian salt lake, Chott Melghir. The novel isolate was Gram-staining-positive, aerobic, catalase-negative and oxidase-positive. Optimum growth occurred at 50-55 °C, 7-10% (w/v) NaCl and pH 7-8. The strain exhibited 95.4, 95.4 and 95.2% 16S rRNA gene sequence similarity to Thalassobacillus devorans G19.1(T), Sediminibacillus halophilus EN8d(T) and Virgibacillus kekensis YIM-kkny16(T), respectively. The major menaquinone was MK-7. The polar lipid profile consisted of phosphatidylglycerol, diphosphatidylglycerol, three unknown phosphoglycolipids and two unknown phospholipids. The predominant cellular fatty acids were iso-C(15 : 0) and iso-C(17 : 0). The DNA G+C content was 41.9 mol%. Based on the phenotypic, chemotaxonomic and phylogenetic data, strain Nari2A(T) is considered to represent a novel species of a new genus in the family Bacillaceae , order Bacillales , for which the name Melghiribacillus thermohalophilus gen. nov., sp. nov. is proposed. The type strain of Melghiribacillus thermohalophilus is Nari2A(T) ( = DSM 25894(T) = CCUG 62543(T)).

  17. Enhanced reductive dechlorination of polychlorinated biphenyl impacted sediment by bioaugmentation with a dehalorespiring bacterium

    PubMed Central

    Payne, Rayford B; May, Harold D; Sowers, Kevin R

    2011-01-01

    Anaerobic reductive dehalogenation of commercial PCBs such as Aroclor 1260 has a critical role of transforming highly chlorinated congeners to less chlorinated congeners that are then susceptible to aerobic degradation. The efficacy of bioaugmentation with the dehalorespiring bacterium “Dehalobium chlorocoercia” DF1 was tested in 2-liter laboratory mesocosms containing sediment contaminated with weathered Aroclor 1260 (1.3 ppm) from Baltimore Harbor, MD. Total penta- and higher chlorinated PCBs decreased by approximately 56% (by mass) in bioaugmented mesocosms after 120 days compared with no activity observed in unamended controls. Bioaugmentation with DF-1 enhanced the dechlorination of doubly flanked chlorines and stimulated the dechlorination of single flanked chlorines as a result of an apparent synergistic effect on the indigenous population. Addition of granulated activated carbon had a slight stimulatory effect indicating that anaerobic reductive dechlorination of PCBs at low concentrations was not inhibited by a high background of inorganic carbon that could affect bioavailability. The total number of dehalorespiring bacteria was reduced by approximately half after 60 days. However, a steady state level was maintained that was greater than the indigenous population of putative dehalorespiring bacteria in untreated sediments and DF1 was maintained within the indigenous population after 120 days. The results of this study demonstrate that bioaugmentation with dehalorespiring bacteria has a stimulatory effect on the dechlorination of weathered PCBs and supports the feasibility of using in situ bioaugmentation as an environmentally less invasive and lower cost alternate to dredging for treatment of PCB impacted sediments. PMID:21902247

  18. Toxic and inhibitory effects of trichloroethylene aerobic co-metabolism on phenol-grown aerobic granules.

    PubMed

    Zhang, Yi; Tay, JooHwa

    2015-04-09

    Aerobic granule, a form of microbial aggregate, exhibits good potential in degrading toxic and recalcitrant substances. In this study, the inhibitory and toxic effects of trichloroethylene (TCE), a model compound for aerobic co-metabolism, on phenol-grown aerobic granules were systematically studied, using respiratory activities after exposure to TCE as indicators. High TCE concentration did not exert positive or negative effects on the subsequent endogenous respiration rate or phenol dependent specific oxygen utilization rate (SOUR), indicating the absence of solvent stress and induction effect on phenol-hydroxylase. Phenol-grown aerobic granules exhibited a unique response to TCE transformation product toxicity, that small amount of TCE transformation enhanced the subsequent phenol SOUR. Granules that had transformed between 1.3 and 3.7 mg TCE gSS(-1) showed at most 53% increase in the subsequent phenol SOUR, and only when the transformation exceeded 6.6 mg TCE gSS(-1) did the SOUR dropped below that of the control. This enhancing effect was found to sustain throughout several phenol dosages, and TCE transformation below the toxicity threshold also lessened the granules' sensitivity to higher phenol concentration. The unique toxic effect was possibly caused by the granule's compact structure as a protection barrier against the diffusive transformation product(s) of TCE co-metabolism.

  19. Characterization and aerobic biodegradation of selected monoterpenes

    SciTech Connect

    Misra, G.; Pavlostathis, S.G.; Li, J.; Purdue, E.M.

    1996-12-31

    Monoterpenes are biogenic chemicals and occur in abundance in nature. Large-scale industrial use of these chemicals has recently been initiated in an attempt to replace halogenated solvents and chlorofluorocarbons which have been implicated in the stratospheric depletion of ozone. This study examined four hydrocarbon monoterpenes (d-limonene, {alpha}-pinene, {gamma}-terpinene, and terpinolene) and four alcohols (arbanol, linalool, plinol, and {alpha}-terpineol). Water solubility, vapor pressure, and octanol/water partition coefficients were estimated. Aerobic biodegradability tests were conducted in batch reactors by utilizing forest soil extract and enriched cultures as inoculum. The hydrophobic nature and high volatility of the hydrocarbons restricted the investigation to relatively low aqueous concentrations. Each monoterpene was analyzed with a gas chromatograph equipped with a flame ionization detector after extraction from the aqueous phase with isooctane. Terpene mineralization was tested by monitoring liquid-phase carbon, CO{sub 2} production and biomass growth. All four hydrocarbons and two alcohols readily degraded under aerobic conditions. Plinol resisted degradation in assays using inocula from diverse sources, while arbanol degraded very slowly. The intrinsic biokinetics coefficients for the degradation of d-limonene and {alpha}-terpineol were estimated by using cultures enriched with the respective monoterpenes. Monoterpene biodegradation followed Monod kinetics.

  20. Aerobic treatment of wine-distillery wastewaters

    SciTech Connect

    Sales, D.; Valcarcel, M.J.; Perez, L.; de la Ossa, E.M.

    1987-01-01

    Waste from food-processing and allied industries is largely made up of organic compounds which can be metabolized by aerobic or anaerobic means. However, these wastes present a series of problems to biological depuration plants, such as the need for prior treatment to establish conditions suitable for the development of the microorganisms responsible for the process; and the long retention time of the biomass if acceptable effluents are to be obtained. Again, the seasonal nature of many of these industries makes for very heterogeneous waste. This means that treatment plant must be versatile and are subject to rapid successions of close-down and start-up interspersed with long intervals of inactivity. All these difficulties oblige the industries in the sector to adapt depurative technology to their particular needs. Wine distilleries fall into this general category. Their waste (called vinasses) is acidic, has a high organic content and varies widely according to the raw matter distilled: wine, lies, etc. This paper studies the start-up of digestors for aerobic treatment of vinasses and the establishment of optimum operating conditions for an adequate depurative performance.

  1. Acute effects of aerobic exercise promote learning.

    PubMed

    Perini, Renza; Bortoletto, Marta; Capogrosso, Michela; Fertonani, Anna; Miniussi, Carlo

    2016-05-05

    The benefits that physical exercise confers on cardiovascular health are well known, whereas the notion that physical exercise can also improve cognitive performance has only recently begun to be explored and has thus far yielded only controversial results. In the present study, we used a sample of young male subjects to test the effects that a single bout of aerobic exercise has on learning. Two tasks were run: the first was an orientation discrimination task involving the primary visual cortex, and the second was a simple thumb abduction motor task that relies on the primary motor cortex. Forty-four and forty volunteers participated in the first and second experiments, respectively. We found that a single bout of aerobic exercise can significantly facilitate learning mechanisms within visual and motor domains and that these positive effects can persist for at least 30 minutes following exercise. This finding suggests that physical activity, at least of moderate intensity, might promote brain plasticity. By combining physical activity-induced plasticity with specific cognitive training-induced plasticity, we favour a gradual up-regulation of a functional network due to a steady increase in synaptic strength, promoting associative Hebbian-like plasticity.

  2. Nitrogen Removal Characteristics of Pseudomonas putida Y-9 Capable of Heterotrophic Nitrification and Aerobic Denitrification at Low Temperature

    PubMed Central

    He, Tengxia; Ye, Qing; Chen, Yanli; Xie, Enyu; Zhang, Xue

    2017-01-01

    The cold-adapted bacterium Pseudomonas putida Y-9 was investigated and exhibited excellent capability for nitrogen removal at 15°C. The strain capable of heterotrophic nitrification and aerobic denitrification could efficiently remove ammonium, nitrate, and nitrite at an average removal rate of 2.85 mg, 1.60 mg, and 1.83 mg NL−1 h−1, respectively. Strain Y-9 performed nitrification in preference to denitrification when ammonium and nitrate or ammonium and nitrite coexisted in the solution. Meantime, the presence of nitrate had no effect on the ammonium removal rate of strain Y-9, and yet the presence of high concentration of nitrite would inhibit the cell growth and decrease the nitrification rate. The experimental results indicate that P. putida Y-9 has potential application for the treatment of wastewater containing high concentrations of ammonium along with its oxidation products at low temperature. PMID:28293626

  3. Aerobic Physical Activity and the Leadership of Principals

    ERIC Educational Resources Information Center

    Kiser, Kari

    2016-01-01

    The purpose of this study was to explore if there was a connection between regular aerobic physical activity and the stress and energy levels of principals as they reported it. To begin the research, the current aerobic physical activity level of principals was discovered. Additionally, the energy and stress levels of the principals who do engage…

  4. The Effectiveness of Aerobic Exercise Instruction for Totally Blind Women.

    ERIC Educational Resources Information Center

    Ponchillia, S. V.; And Others

    1992-01-01

    A multifaceted method (involving verbal and hands-on training) was used to teach aerobic exercises to 3 totally blind women (ages 24-37). All three women demonstrated positive gains in their performance, physical fitness, and attitudes toward participating in future mainstream aerobic exercise classes. (DB)

  5. Aerobic Activity--Do Physical Education Programs Provide Enough?

    ERIC Educational Resources Information Center

    McGing, Eileen

    1989-01-01

    High school physical education curricula should concentrate less on sport skill development and competition, and more on health-related fitness and aerobic activity. Results are reported from a study of the type and amount of aerobic exercise provided in 29 high school physical education programs in a large metropolitan area. (IAH)

  6. Aerobic Digestion. Student Manual. Biological Treatment Process Control.

    ERIC Educational Resources Information Center

    Klopping, Paul H.

    This manual contains the textual material for a single-lesson unit on aerobic sludge digestion. Topic areas addressed include: (1) theory of aerobic digestion; (2) system components; (3) performance factors; (4) indicators of stable operation; and (5) operational problems and their solutions. A list of objectives, glossary of key terms, and…

  7. p53 aerobics: the major tumor suppressor fuels your workout.

    PubMed

    Kruse, Jan-Philipp; Gu, Wei

    2006-07-01

    In addition to its role as the central regulator of the cellular stress response, p53 can regulate aerobic respiration via the novel transcriptional target SCO2, a critical regulator of the cytochrome c oxidase complex (Matoba et al., 2006). Loss of p53 results in decreased oxygen consumption and aerobic respiration and promotes a switch to glycolysis, thereby reducing endurance during physical exercise.

  8. The Acute Effect of Aerobic Exercise on Measures of Stress.

    ERIC Educational Resources Information Center

    Fort, Inza L.; And Others

    The immediate response of stress to aerobic exercise was measured by utilizing the Palmar Sweat Index (PSI) and the State-Trait Anxiety Inventory (STAI). Forty subjects (20 male and 20 female) from the ages of 18-30 sustained a single bout of aerobic activity for 30 minutes at 60 percent of their maximum heart rate. Pre-treatment procedures…

  9. High skin temperature and hypohydration impair aerobic performance.

    PubMed

    Sawka, Michael N; Cheuvront, Samuel N; Kenefick, Robert W

    2012-03-01

    This paper reviews the roles of hot skin (>35°C) and body water deficits (>2% body mass; hypohydration) in impairing submaximal aerobic performance. Hot skin is associated with high skin blood flow requirements and hypohydration is associated with reduced cardiac filling, both of which act to reduce aerobic reserve. In euhydrated subjects, hot skin alone (with a modest core temperature elevation) impairs submaximal aerobic performance. Conversely, aerobic performance is sustained with core temperatures >40°C if skin temperatures are cool-warm when euhydrated. No study has demonstrated that high core temperature (∼40°C) alone, without coexisting hot skin, will impair aerobic performance. In hypohydrated subjects, aerobic performance begins to be impaired when skin temperatures exceed 27°C, and even warmer skin exacerbates the aerobic performance impairment (-1.5% for each 1°C skin temperature). We conclude that hot skin (high skin blood flow requirements from narrow skin temperature to core temperature gradients), not high core temperature, is the 'primary' factor impairing aerobic exercise performance when euhydrated and that hypohydration exacerbates this effect.

  10. Aerobic Fitness Thresholds Associated with Fifth Grade Academic Achievement

    ERIC Educational Resources Information Center

    Wittberg, Richard; Cottrell, Lesley A.; Davis, Catherine L.; Northrup, Karen L.

    2010-01-01

    Background: Whereas effects of physical fitness and physical activity on cognitive function have been documented, little is known about how they are related. Purpose: This study assessed student aerobic fitness measured by FITNESSGRAM Mile times and/or Pacer circuits and whether the nature of the association between aerobic fitness and…

  11. Factors associated with low levels of aerobic fitness among adolescents

    PubMed Central

    Gonçalves, Eliane Cristina de Andrade; Silva, Diego Augusto Santos

    2016-01-01

    Abstract Objective: To evaluate the prevalence of low aerobic fitness levels and to analyze the association with sociodemographic factors, lifestyle and excess body fatness among adolescents of southern Brazil. Methods: The study included 879 adolescents aged 14-19 years the city of São José/SC, Brazil. The aerobic fitness was assessed by Canadian modified test of aerobic fitness. Sociodemographic variables (skin color, age, sex, study turn, economic level), sexual maturation and lifestyle (eating habits, screen time, physical activity, consumption of alcohol and tobacco) were assessed by a self-administered questionnaire. Excess body fatness was evaluated by sum of skinfolds triceps and subscapular. We used logistic regression to estimate odds ratios and 95% confidence intervals. Results: Prevalence of low aerobic fitness level was 87.5%. The girls who spent two hours or more in front screen, consumed less than one glass of milk by day, did not smoke and had an excess of body fatness had a higher chance of having lower levels of aerobic fitness. White boys with low physical activity had had a higher chance of having lower levels of aerobic fitness. Conclusions: Eight out of ten adolescents were with low fitness levels aerobic. Modifiable lifestyle factors were associated with low levels of aerobic fitness. Interventions that emphasize behavior change are needed. PMID:26743851

  12. The use of aerobic exercise training in improving aerobic capacity in individuals with stroke: a meta-analysis

    PubMed Central

    Pang, Marco YC; Eng, Janice J; Dawson, Andrew S; Gylfadóttir, Sif

    2011-01-01

    Objective To determine whether aerobic exercise improves aerobic capacity in individuals with stroke. Design A systematic review of randomized controlled trials. Databases searched MEDLINE, CINAHL, EMBASE, Cochrane Database of Systematic Reviews, Physiotherapy Evidence Database were searched. Inclusion criteria Design: randomized controlled trials; Participants: individuals with stroke; Interventions: aerobic exercise training aimed at improving aerobic capacity; Outcomes Primary outcomes: aerobic capacity [peak oxygen consumption (VO2), peak workload); Secondary outcomes: walking velocity, walking endurance. Data Analysis The methodological quality was assessed by the PEDro scale. Meta-analyses were performed for all primary and secondary outcomes. Results Nine articles (seven RCTs) were identified. The exercise intensity ranged from 50% to 80% heart rate reserve. Exercise duration was 20–40 minutes for 3–5 days a week. The total number of subjects included in the studies was 480. All studies reported positive effects on aerobic capacity, regardless of the stage of stroke recovery. Meta-analysis revealed a significant homogeneous standardized effect size (SES) in favour of aerobic exercise to improve peak VO2 (SES, 0.42; 95%CI, 0.15 to 0.69; p=0.001) and peak workload (SES, 0.50; 95%CI, 0.26 to 0.73; p<0.001). There was also a significant homogeneous SES in favour of aerobic training to improve walking velocity (SES, 0.26; 95%CI, 0.05 to 0.48; p=0.008) and walking endurance (SES, 0.30; 95%CI, 0.06to 0.55; p=0.008). Conclusions There is good evidence that aerobic exercise is beneficial for improving aerobic capacity in people with mild and moderate stroke. Aerobic exercise should be an important component of stroke rehabilitation. PMID:16541930

  13. Modeling the influence of varying hydraulic conditions on aerobic respiration and denitrification in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Trauth, N.; Schmidt, C.; Fleckenstein, J. H.

    2013-12-01

    Exchange of water and solutes across the stream-sediment interface is an important control for biogeochemical transformations in the hyporheic zone (HZ) with measurable impacts on nutrient cycling and solute attenuation in fluvial systems. Here we investigate the interplay between turbulent stream flow and HZ flow under various hydraulic conditions applied to two cases: a) three-dimensional generic pool-riffle sequences with different morphological properties, and b) a real mid-stream gravel-bar. Stream flow is simulated by the open source computational fluid dynamics (CFD) software OpenFOAM which provides the hydraulic head distribution at the streambed. It is sequentially coupled to the top of the groundwater model code MIN3P, simulating flow, solute transport, aerobic respiration (AR) and denitrification (DN) in the HZ. Flow in the HZ is directly influenced by the hydraulic head distribution at the streambed surface and the ambient groundwater flow. Three reactive transport scenarios are considered: 1) stream water as the primary source of dissolved oxygen (DO), nitrate (NO3) and dissolved organic carbon (DOC), 2) upwelling groundwater as an additionally source of NO3, and 3) upwelling groundwater as an additional source of DO in various concentrations. Results show an increase in hyporheic exchange flow for increasing stream discharge with a concurrent decrease in residence time. The fraction of circulating stream water through the HZ is in the range of 1x10-5 to 1x10-6 per unit stream length, decreasing with increasing discharge. Ambient groundwater flow in both the up- and downwelling direction diminishes significantly the hyporheic exchange flow and extent. Biogeochemical processes in the HZ are strongly controlled by ambient groundwater flow, even more so than by changes in stream discharge. AR and DN efficiencies of the HZ are significantly reduced by up- and downwelling groundwater and are positively correlated with median residence times. AR occurs in

  14. Isolation of high-salinity-tolerant bacterial strains, Enterobacter sp., Serratia sp., Yersinia sp., for nitrification and aerobic denitrification under cyanogenic conditions.

    PubMed

    Mpongwana, N; Ntwampe, S K O; Mekuto, L; Akinpelu, E A; Dyantyi, S; Mpentshu, Y

    2016-01-01

    Cyanides (CN(-)) and soluble salts could potentially inhibit biological processes in wastewater treatment plants (WWTPs), such as nitrification and denitrification. Cyanide in wastewater can alter metabolic functions of microbial populations in WWTPs, thus significantly inhibiting nitrifier and denitrifier metabolic processes, rendering the water treatment processes ineffective. In this study, bacterial isolates that are tolerant to high salinity conditions, which are capable of nitrification and aerobic denitrification under cyanogenic conditions, were isolated from a poultry slaughterhouse effluent. Three of the bacterial isolates were found to be able to oxidise NH(4)-N in the presence of 65.91 mg/L of free cyanide (CN(-)) under saline conditions, i.e. 4.5% (w/v) NaCl. The isolates I, H and G, were identified as Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Results showed that 81% (I), 71% (G) and 75% (H) of 400 mg/L NH(4)-N was biodegraded (nitrification) within 72 h, with the rates of biodegradation being suitably described by first order reactions, with rate constants being: 4.19 h(-1) (I), 4.21 h(-1) (H) and 3.79 h(-1) (G), respectively, with correlation coefficients ranging between 0.82 and 0.89. Chemical oxygen demand (COD) removal rates were 38% (I), 42% (H) and 48% (G), over a period of 168 h with COD reduction being highest at near neutral pH.

  15. Effects of rapid temperature rising on nitrogen removal and microbial community variation of anoxic/aerobic process for ABS resin wastewater treatment.

    PubMed

    Luo, Huilong; Song, Yudong; Zhou, Yuexi; Yang, Liwei; Zhao, Yaqian

    2017-02-01

    ABS resin wastewater is a high-temperature nitrogenous organic wastewater. It can be successfully treated with anoxic/aerobic (A/O) process. In this study, the effect of temperature on nitrogen removal and microbial community after quick temperature rise (QTR) was investigated. It was indicated that QTR from 25 to 30 °C facilitated the microbial growth and achieved a similar effluent quality as that at 25 °C. QTR from 25 to 35 °C or 40 °C resulted in higher effluent concentration of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP). Illumina MiSeq pyrosequencing analysis illustrated that the richness and diversity of the bacterial community was decreased as the temperature was increased. The percentage of many functional groups was changed significantly. QTR from 25 to 40 °C also resulted in the inhibition of ammonia oxidation rate and high concentration of free ammonia, which then inhibited the growth of NOB (Nitrospira), and thus resulted in nitrite accumulation. The high temperature above 35 °C promoted the growth of a denitrifying bacterial genus, Denitratisoma, which might increase N2O production during the denitrification process.

  16. Muscle deoxygenation in aerobic and anaerobic exercise.

    PubMed

    Nioka, S; Moser, D; Lech, G; Evengelisti, M; Verde, T; Chance, B; Kuno, S

    1998-01-01

    It has been generally accepted that the use of oxygen is a major contributor of ATP synthesis in endurance exercise but not in short sprints. In anaerobic exercise, muscle energy is thought to be initially supported by the PCr-ATP system followed by glycolysis, not through mitochondrial oxidative phosphorylation. However, in real exercise practice, we do not know how much of this notion is true when an athlete approaches his/her maximal capacity of aerobic and anaerobic exercise, such as during a graded VO2max test. This study investigates the use of oxygen in aerobic and anaerobic exercise by monitoring oxygen concentration of the vastus lateralis muscle at maximum intensity using Near Infra-red Spectroscopy (NIRS). We tested 14 sprinters from the University of Penn track team, whose competitive events are high jump, pole vault, 100 m, 200 m, 400 m, and 800 m. The Wingate anaerobic power test was performed on a cycle ergometer with 10% body weight resistance for 30 seconds. To compare oxygenation during aerobic exercise, a steady-state VO2max test with a cycle ergometer was used with 25 watt increments every 2 min. until exhaustion. Results showed that in the Wingate test, total power reached 774 +/- 86 watt, about 3 times greater than that in the VO2max test (270 +/- 43 watt). In the Wingate test, the deoxygenation reached approximately 80% of the established maximum value, while in the VO2max test resulted in approximately 36% deoxygenation. There was no delay in onset of deoxygenation in the Wingate test, while in the VO2max test, deoxygenation did not occur under low intensity work. The results indicate that oxygen was used from the beginning of sprint test, suggesting that the mitochondrial ATP synthesis was triggered after a surprisingly brief exercise duration. One explanation is that prior warm-up (unloaded exercise) was enough to provide the mitochondrial substrates; ADP and Pi to activate oxidative phosphorylation by the type II a and type I myocytes. In

  17. Carbon availability and the distribution of denitrifying organisms influence N2O production in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Farrell, T. B.; Quick, A. M.; Reeder, W. J.; Tonina, D.; Benner, S. G.; Feris, K. P.

    2013-12-01

    It has been estimated that 10% of greenhouse gas N2O emissions take place within river networks, with the majority of these processes occurring in the hyporheic zone (HZ). These emissions are the result of microbially-mediated nitrogen transformations (i.e. nitrification and denitrification) and yet the role of microbial distribution and function in this complex system is not well understood. We hypothesized that the concentration and availability of organic carbon influences the production of redox gradients, DIN (via mineralization, nitrification, and loss of DIN via denitrification), and ultimately N2O production in the HZ by controlling the distribution and activity of denitrifying microbial communities. Further, we hypothesized that by linking the distribution of denitrifying microbial communities and their associated functional genes (i.e. the relative abundance of N2O vs. N2 producing genetic elements) to flow dynamics and biogeochemical processes, we can begin to better understand what controls N2O production in hyporheic networks. To address these hypotheses we performed a series of column experiments designed to determine the influence of carbon concentration on redox gradient development and N2O flux along a one-dimensional flow path. Intact sediment cores were amended with 0.01%, 0.05%, 0.15%, and 0.5% dry mass riparian vegetation (>90% Populus sp.) to serve as an endogenous particulate organic matter (POM) source. During quasi-steady state conditions dissolved oxygen (DO), NH4+, NO3-, and N2O levels were measured. As predicted, a positive relationship between the level of POM amendment and development of a gradient of oxic and anoxic conditions was observed. There was negligible N2O production within columns inoculated with 0.01% and 0.05% DOC likely because these POC treatments were too low to create anoxic conditions necessary to stimulate denitrification. Maximum N2O flux was observed with the 0.15% POC treatment. Both oxic and anoxic conditions

  18. Effectiveness of the modified progressive aerobic capacity endurance run test for assessing aerobic fitness in Hispanic children who are obese

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to evaluate the effectiveness of the progressive aerobic capacity endurance run (PACER) and a newly designed modified PACER (MPACER) for assessing aerobic fitness in Hispanic children who are obese. Thirty-nine (aged 7-12 years) children who were considered obese (= 95 ...

  19. Purification, Characterization, and Genetic Analysis of Cu-Containing Dissimilatory Nitrite Reductase from a Denitrifying Halophilic Archaeon, Haloarcula marismortui

    PubMed Central

    Ichiki, Hirotaka; Tanaka, Yoko; Mochizuki, Kiyotaka; Yoshimatsu, Katsuhiko; Sakurai, Takeshi; Fujiwara, Taketomo

    2001-01-01

    Cu-containing dissimilatory nitrite reductase (CuNiR) was purified from denitrifying cells of a halophilic archaeon, Haloarcula marismortui. The purified CuNiR appeared blue in the oxidized state, possessing absorption peaks at 600 and 465 nm in the visible region. Electron paramagnetic resonance spectroscopy suggested the presence of type 1 Cu (gII = 2.232; AII = 4.4 mT) and type 2 Cu centers (gII = 2.304; AII = 13.3 mT) in the enzyme. The enzyme contained two subunits, whose apparent molecular masses were 46 and 42 kDa, according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N-terminal amino acid sequence analysis indicated that the two subunits were identical, except that the 46-kDa subunit was 16 amino acid residues longer than the 42-kDa subunit in the N-terminal region. A nirK gene encoding the CuNiR was cloned and sequenced, and the deduced amino acid sequence with a residual length of 361 amino acids was homologous (30 to 41%) with bacterial counterparts. Cu-liganding residues His-133, Cys-174, His-182, and Met-187 (for type 1 Cu) and His-138, His-173, and His-332 (for type 2 Cu) were conserved in the enzyme. As generally observed in the halobacterial enzymes, the enzymatic activity of the purified CuNiR was enhanced during increasing salt concentration and reached its maximum in the presence of 2 M NaCl with the value of 960 μM NO2− · min−1 · mg−1. PMID:11418554

  20. Functional gene pyrosequencing and network analysis: an approach to examine the response of denitrifying bacteria to increased nitrogen supply in salt marsh sediments

    PubMed Central

    Bowen, Jennifer L.; Byrnes, Jarrett E. K.; Weisman, David; Colaneri, Cory

    2013-01-01

    Functional gene pyrosequencing is emerging as a useful tool to examine the diversity and abundance of microbes that facilitate key biogeochemical processes. One such process, denitrification, is of particular importance because it converts fixed nitrate (NO−3) to N2 gas, which returns to the atmosphere. In nitrogen limited salt marshes, removal of NO−3 prior to entering adjacent waters helps prevent eutrophication. Understanding the dynamics of salt marsh microbial denitrification is thus imperative for the maintenance of healthy coastal ecosystems. We used pyrosequencing of the nirS gene to examine the denitrifying community response to fertilization in experimentally enriched marsh plots. A key challenge in the analysis of sequence data derived from pyrosequencing is understanding whether small differences in gene sequences are ecologically meaningful. We applied a novel approach from information theory to determine that the optimal similarity level for clustering DNA sequences into OTUs, while still capturing the ecological complexity of the system, was 88%. With this clustering, phylogenetic analysis yielded 6 dominant clades of denitrifiers, the largest of which, accounting for more than half of all the sequences collected, had no close cultured representatives. Of the 638 OTUs identified, only 11 were present in all plots and no single OTU was dominant. We did, however, find a large number of specialist OTUs that were present only in a single plot. The high degree of endemic OTUs, while accounting for a large proportion of the nirS diversity in the plots, were found in lower abundance than the generalist taxa. The proportion of specialist taxa increased with increasing supply of nutrients, suggesting that addition of fertilizer may create conditions that expand the niche space for denitrifying organisms and may enhance the genetic capacity for denitrification. PMID:24348464

  1. Investigation of an acetate-fed denitrifying microbial community by stable isotope probing, full-cycle rRNA analysis, and fluorescent in situ hybridization-microautoradiography.

    PubMed

    Ginige, Maneesha P; Keller, Jürg; Blackall, Linda L

    2005-12-01

    The acetate-utilizing microbial consortium in a full-scale activated sludge process was investigated without prior enrichment using stable isotope probing (SIP). [13C]acetate was used in SIP to label the DNA of the denitrifiers. The [13C]DNA fraction that was extracted was subjected to a full-cycle rRNA analysis. The dominant 16S rRNA gene phylotypes in the 13C library were closely related to the bacterial families Comamonadaceae and Rhodocyclaceae in the class Betaproteobacteria. Seven oligonucleotide probes for use in fluorescent in situ hybridization (FISH) were designed to specifically target these clones. Application of these probes to the sludge of a continuously fed denitrifying sequencing batch reactor (CFDSBR) operated for 16 days revealed that there was a significant positive correlation between the CFDSBR denitrification rate and the relative abundance of all probe-targeted bacteria in the CFDSBR community. FISH-microautoradiography demonstrated that the DEN581 and DEN124 probe-targeted cells that dominated the CFDSBR were capable of taking up [14C]acetate under anoxic conditions. Initially, DEN444 and DEN1454 probe-targeted bacteria also dominated the CFDSBR biomass, but eventually DEN581 and DEN124 probe-targeted bacteria were the dominant bacterial groups. All probe-targeted bacteria assessed in this study were denitrifiers capable of utilizing acetate as a source of carbon. The rapid increase in the number of organisms positively correlated with the immediate increase in denitrification rates observed by plant operators when acetate is used as an external source of carbon to enhance denitrification. We suggest that the impact of bacteria on activated sludge subjected to intermittent acetate supplementation should be assessed prior to the widespread use of acetate in the wastewater industry to enhance denitrification.

  2. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2012-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  3. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2013-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  4. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana

    PubMed Central

    Pradhan, Nirakar; Dipasquale, Laura; d’Ippolito, Giuliana; Panico, Antonio; Lens, Piet N. L.; Esposito, Giovanni; Fontana, Angelo

    2015-01-01

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production. PMID:26053393

  5. Hydrogen Production by the Thermophilic Bacterium Thermotoga neapolitana.

    PubMed

    Pradhan, Nirakar; Dipasquale, Laura; d'Ippolito, Giuliana; Panico, Antonio; Lens, Piet N L; Esposito, Giovanni; Fontana, Angelo

    2015-06-04

    As the only fuel that is not chemically bound to carbon, hydrogen has gained interest as an energy carrier to face the current environmental issues of greenhouse gas emissions and to substitute the depleting non-renewable reserves. In the last years, there has been a significant increase in the number of publications about the bacterium Thermotoga neapolitana that is responsible for production yields of H2 that are among the highest achievements reported in the literature. Here we present an extensive overview of the most recent studies on this hyperthermophilic bacterium together with a critical discussion of the potential of fermentative production by this bacterium. The review article is organized into sections focused on biochemical, microbiological and technical issues, including the effect of substrate, reactor type, gas sparging, temperature, pH, hydraulic retention time and organic loading parameters on rate and yield of gas production.

  6. Surface Structure of Aerobically Oxidized Diamond Nanocrystals.

    PubMed

    Wolcott, Abraham; Schiros, Theanne; Trusheim, Matthew E; Chen, Edward H; Nordlund, Dennis; Diaz, Rosa E; Gaathon, Ophir; Englund, Dirk; Owen, Jonathan S

    2014-11-20

    We investigate the aerobic oxidation of high-pressure, high-temperature nanodiamonds (5-50 nm dimensions) using a combination of carbon and oxygen K-edge X-ray absorption, wavelength-dependent X-ray photoelectron, and vibrational spectroscopies. Oxidation at 575 °C for 2 h eliminates graphitic carbon contamination (>98%) and produces nanocrystals with hydroxyl functionalized surfaces as well as a minor component (<5%) of carboxylic anhydrides. The low graphitic carbon content and the high crystallinity of HPHT are evident from Raman spectra acquired using visible wavelength excitation (λexcit = 633 nm) as well as carbon K-edge X-ray absorption spectra where the signature of a core-hole exciton is observed. Both spectroscopic features are similar to those of chemical vapor deposited (CVD) diamond but differ significantly from the spectra of detonation nanodiamond. The importance of these findings to the functionalization of nanodiamond surfaces for biological labeling applications is discussed.

  7. Magnesium carbonate precipitate strengthened aerobic granules.

    PubMed

    Lee, Duu-Jong; Chen, Yu-You

    2015-05-01

    Aerobic granules were precipitated internally with magnesium carbonate to enhance their structural stability under shear. The strengthened granules were tested in continuous-flow reactors for 220 days at organic loadings of 6-39 kg/m(3)/day, hydraulic retention times of 0.44-19 h, and temperatures of 10 or 28°C. The carbonate salt had markedly improved the granule strength without significant changes in granule morphology or microbial communities (with persistent strains Streptomyces sp., Rhizobium sp., Brevundimonas sp., and Nitratireductor sp.), or sacrifice in biological activity for organic degradation. MgCO3 precipitated granules could be used in continuous-flow reactor for wastewater treatment at low cost and with easy processing efforts.

  8. Surface Structure of Aerobically Oxidized Diamond Nanocrystals

    PubMed Central

    2015-01-01

    We investigate the aerobic oxidation of high-pressure, high-temperature nanodiamonds (5–50 nm dimensions) using a combination of carbon and oxygen K-edge X-ray absorption, wavelength-dependent X-ray photoelectron, and vibrational spectroscopies. Oxidation at 575 °C for 2 h eliminates graphitic carbon contamination (>98%) and produces nanocrystals with hydroxyl functionalized surfaces as well as a minor component (<5%) of carboxylic anhydrides. The low graphitic carbon content and the high crystallinity of HPHT are evident from Raman spectra acquired using visible wavelength excitation (λexcit = 633 nm) as well as carbon K-edge X-ray absorption spectra where the signature of a core–hole exciton is observed. Both spectroscopic features are similar to those of chemical vapor deposited (CVD) diamond but differ significantly from the spectra of detonation nanodiamond. The importance of these findings to the functionalization of nanodiamond surfaces for biological labeling applications is discussed. PMID:25436035

  9. Brain aerobic glycolysis and motor adaptation learning

    PubMed Central

    Shannon, Benjamin J.; Vaishnavi, Sanjeev Neil; Vlassenko, Andrei G.; Shimony, Joshua S.; Rutlin, Jerrel; Raichle, Marcus E.

    2016-01-01

    Ten percent to 15% of glucose used by the brain is metabolized nonoxidatively despite adequate tissue oxygenation, a process termed aerobic glycolysis (AG). Because of the known role of glycolysis in biosynthesis, we tested whether learning-induced synaptic plasticity would lead to regionally appropriate, learning-dependent changes in AG. Functional MRI (fMRI) before, during, and after performance of a visual–motor adaptation task demonstrated that left Brodmann area 44 (BA44) played a key role in adaptation, with learning-related changes to activity during the task and altered resting-state, functional connectivity after the task. PET scans before and after task performance indicated a sustained increase in AG in left BA 44 accompanied by decreased oxygen consumption. Intersubject variability in behavioral adaptation rate correlated strongly with changes in AG in this region, as well as functional connectivity, which is consistent with a role for AG in synaptic plasticity. PMID:27217563

  10. Biology of Moderately Halophilic Aerobic Bacteria

    PubMed Central

    Ventosa, Antonio; Nieto, Joaquín J.; Oren, Aharon

    1998-01-01

    The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms. PMID:9618450

  11. Aerobic Microbial Degradation of Glucoisosaccharinic Acid

    PubMed Central

    Strand, S. E.; Dykes, J.; Chiang, V.

    1984-01-01

    α-Glucoisosaccharinic acid (GISA), a major by-product of kraft paper manufacture, was synthesized from lactose and used as the carbon source for microbial media. Ten strains of aerobic bacteria capable of growth on GISA were isolated from kraft pulp mill environments. The highest growth yields were obtained with Ancylobacter spp. at pH 7.2 to 9.5. GISA was completely degraded by cultures of an Ancylobacter isolate. Ancylobacter cell suspensions consumed oxygen and produced carbon dioxide in response to GISA addition. A total of 22 laboratory strains of bacteria were tested, and none was capable of growth on GISA. GISA-degrading isolates were not found in forest soils. Images PMID:16346467

  12. Effects of Kettlebell Training on Aerobic Capacity.

    PubMed

    Falatic, J Asher; Plato, Peggy A; Holder, Christopher; Finch, Daryl; Han, Kyungmo; Cisar, Craig J

    2015-07-01

    This study examined the effects of a kettlebell training program on aerobic capacity. Seventeen female National Collegiate Athletic Association Division I collegiate soccer players (age: 19.7 ± 1.0 years, height: 166.1 ± 6.4 cm, weight: 64.2 ± 8.2 kg) completed a graded exercise test to determine maximal oxygen consumption (V̇O2max). Participants were assigned to a kettlebell intervention group (KB) (n = 9) or a circuit weight-training (CWT) control group (n = 8). Participants in the KB group completed a kettlebell snatch test to determine individual snatch repetitions. Both groups trained 3 days a week for 4 weeks in addition to their off-season strength and conditioning program. The KB group performed the 15:15 MVO2 protocol (20 minutes of kettlebell snatching with 15 seconds of work and rest intervals). The CWT group performed multiple free-weight and dynamic body-weight exercises as part of a continuous circuit program for 20 minutes. The 15:15 MVO2 protocol significantly increased V̇O2max in the KB group. The average increase was 2.3 ml·kg⁻¹·min⁻¹, or approximately a 6% gain. There was no significant change in V̇O2max in the CWT control group. Thus, the 4-week 15:15 MVO2 kettlebell protocol, using high-intensity kettlebell snatches, significantly improved aerobic capacity in female intercollegiate soccer players and could be used as an alternative mode to maintain or improve cardiovascular conditioning.

  13. Molecular diversity of denitrifying genes in continental margin sediments within the oxygen-deficient zone off the Pacific coast of Mexico.

    PubMed

    Liu, Xueduan; Tiquia, Sonia M; Holguin, Gina; Wu, Liyou; Nold, Stephen C; Devol, Allan H; Luo, Kuan; Palumbo, Anthony V; Tiedje, James M; Zhou, Jizhong

    2003-06-01

    To understand the composition and structure of denitrifying communities in the oxygen-deficient zone off the Pacific coast of Mexico, the molecular diversity of nir genes from sediments obtained at four stations was examined by using a PCR-based cloning approach. A total of 50 operational taxonomic units (OTUs) for nirK and 82 OTUs for nirS were obtained from all samples. Forty-four of the nirS clones and 31 of the nirK clones were sequenced; the levels of similarity of the nirS clones were 52 to 92%, and the levels of similarity of the nirS clones were 50 to 99%. The percentages of overlapping OTUs between stations were 18 to 30% for nirS and 5 to 8% for nirK. Sequence analysis revealed that 26% of the nirS clones were related to the nirS genes of Alcaligenes faecalis (80 to 94% similar) and Pseudomonas stutzeri (80 to 99%), whereas 3 to 31% of the nirK clones were closely related to the nirK genes of Pseudomonas sp. strain G-179 (98 to 99%), Bradyrhizobium japonicum (91%), Blastobacter denitrificans (83%), and Alcaligenes xylosoxidans (96%). The rest of the clones, however, were less than 80% similar to nirS and nirK sequences available in sequence databases. The results of a principal-component analysis (PCA) based on the percentage of OTUs and biogeochemical data indicated that the nitrate concentration and oxygen have an effect on the denitrifying communities. The communities at the stations in oxygen-deficient zones were more similar than the communities at the stations in the oxygenated zone. The denitrifying communities were more similar at the stations that were closer together and had similar nitrate levels. Also, the results of PCA based on biogeochemical properties suggest that geographic location and biogeochemical conditions, especially the nitrate and oxygen levels, appear to be the key factors that control the structure of denitrifying communities.

  14. Phenotypic and genotypic properties of Microbacterium yannicii, a recently described multidrug resistant bacterium isolated from a lung transplanted patient with cystic fibrosis in France

    PubMed Central

    2013-01-01

    Background Cystic fibrosis (CF) lung microbiota consists of diverse species which are pathogens or opportunists or have unknown pathogenicity. Here we report the full characterization of a recently described multidrug resistant bacterium, Microbacterium yannicii, isolated from a CF patient who previously underwent lung transplantation. Results Our strain PS01 (CSUR-P191) is an aerobic, rod shaped, non-motile, yellow pigmented, gram positive, oxidase negative and catalase positive bacterial isolate. Full length 16S rRNA gene sequence showed 98.8% similarity with Microbacterium yannicii G72T type strain, which was previously isolated from Arabidopsis thaliana. The genome size is 3.95Mb, with an average G+C content of 69.5%. In silico DNA-DNA hybridization analysis between our Microbacterium yannicii PS01isolate in comparison with Microbacterium testaceum StLB037 and Microbacterium laevaniformans OR221 genomes revealed very weak relationship with only 28% and 25% genome coverage, respectively. Our strain, as compared to the type strain, was resistant to erythromycin because of the presence of a new erm 43 gene encoding a 23S rRNA N-6-methyltransferase in its genome which was not detected in the reference strain. Interestingly, our patient received azithromycin 250 mg daily for bronchiolitis obliterans syndrome for more than one year before the isolation of this bacterium. Conclusions Although significance of isolating this bacterium remains uncertain in terms of clinical evolution, this bacterium could be considered as an opportunistic human pathogen as previously reported for other species in this genus, especially in immunocompromised patients. PMID:23642186

  15. Development of Aerobic Fitness in Young Team Sport Athletes.

    PubMed

    Harrison, Craig B; Gill, Nicholas D; Kinugasa, Taisuke; Kilding, Andrew E

    2015-07-01

    The importance of a high level of aerobic fitness for team sport players is well known. Previous research suggests that aerobic fitness can be effectively increased in adults using traditional aerobic conditioning methods, including high-intensity interval and moderate-intensity continuous training, or more recent game-based conditioning that involves movement and skill-specific tasks, e.g. small-sided games. However, aerobic fitness training for youth team sport players has received limited attention and is likely to differ from that for adults due to changes in maturation. Given young athletes experience different rates of maturation and technical skill development, the most appropriate aerobic fitness training modes and loading parameters are likely to be specific to the developmental stage of a player. Therefore, we analysed studies that investigated exercise protocols to enhance aerobic fitness in young athletes, relative to growth and maturation, to determine current best practice and limitations. Findings were subsequently used to guide an evidence-based model for aerobic fitness development. During the sampling stage (exploration of multiple sports), regular participation in moderate-intensity aerobic fitness training, integrated into sport-specific drills, activities and skill-based games, is recommended. During the specialisation stage (increased commitment to a chosen sport), high-intensity small-sided games should be prioritised to provide the simultaneous development of aerobic fitness and technical skills. Once players enter the investment stage (pursuit of proficiency in a chosen sport), a combination of small-sided games and high-intensity interval training is recommended.

  16. A Novel Treatment Protects Chlorella at Commercial Scale from the Predatory Bacterium Vampirovibrio chlorellavorus

    PubMed Central

    Ganuza, Eneko; Sellers, Charles E.; Bennett, Braden W.; Lyons, Eric M.; Carney, Laura T.

    2016-01-01

    The predatory bacterium, Vampirovibrio chlorellavorus, can destroy a Chlorella culture in just a few days, rendering an otherwise robust algal crop into a discolored suspension of empty cell walls. Chlorella is used as a benchmark for open pond cultivation due to its fast growth. In nature, V. chlorellavorus plays an ecological role by controlling this widespread terrestrial and freshwater microalga, but it can have a devastating effect when it attacks large commercial ponds. We discovered that V. chlorellavorus was associated with the collapse of four pilot commercial-scale (130,000 L volume) open-pond reactors. Routine microscopy revealed the distinctive pattern of V. chlorellavorus attachment to the algal cells, followed by algal cell clumping, culture discoloration and ultimately, growth decline. The “crash” of the algal culture coincided with increasing proportions of 16s rRNA sequencing reads assigned to V. chlorellavorus. We designed a qPCR assay to predict an impending culture crash and developed a novel treatment to control the bacterium. We found that (1) Chlorella growth was not affected by a 15 min exposure to pH 3.5 in the presence of 0.5 g/L acetate, when titrated with hydrochloric acid and (2) this treatment had a bactericidal effect on the culture (2-log decrease in aerobic counts). Therefore, when qPCR results indicated a rise in V. chlorellavorus amplicons, we found that the pH-shock treatment prevented the culture crash and doubled the productive longevity of the culture. Furthermore, the treatment could be repeatedly applied to the same culture, at the beginning of at least two sequential batch cycles. In this case, the treatment was applied preventively, further increasing the longevity of the open pond culture. In summary, the treatment reversed the infection of V. chlorellavorus as confirmed by observations of bacterial attachment to Chlorella cells and by detection of V. chlorellavorus by 16s rRNA sequencing and qPCR assay. The p

  17. Evaluation of Biodegradability of Waste Before and After Aerobic Treatment

    NASA Astrophysics Data System (ADS)

    Suchowska-Kisielewicz, Monika; Jędrczak, Andrzej; Sadecka, Zofia

    2014-12-01

    An important advantage of use of an aerobic biostabilization of waste prior to its disposal is that it intensifies the decomposition of the organic fraction of waste into the form which is easily assimilable for methanogenic microorganisms involved in anaerobic decomposition of waste in the landfill. In this article it is presented the influence of aerobic pre-treatment of waste as well as leachate recirculation on susceptibility to biodegradation of waste in anaerobic laboratory reactors. The research has shown that in the reactor with aerobically treated waste stabilized with recilculation conversion of the organic carbon into the methane is about 45% higher than in the reactor with untreated waste stabilized without recirculation.

  18. Considerations in prescribing preflight aerobic exercise for astronauts

    NASA Technical Reports Server (NTRS)

    Frey, Mary Anne Bassett

    1987-01-01

    The physiological effects of prolonged exposure to weightlessness are discussed together with the effects of aerobic exercise on human characteristics affected by weightlessness. It is noted that, although early data on orthostatic intolerance after spaceflight led to a belief that a high level of aerobic fitness for astronauts was detrimental to orthostatic tolerance on return to earth, most of the data available today do not suport this contention. Aerobic fitness was found to be beneficial to cardiovascular function and to mental performance; therefore, it may be important in performing extravehicular activities during flight.

  19. Role of Aerobic Microbial Populations in Cellulose Digestion by Desert Millipedes

    PubMed Central

    Taylor, Elsa C.

    1982-01-01

    I examined the role of aerobic microbial populations in cellulose digestion by two sympatric species of desert millipedes, Orthoporus ornatus and Comanchelus sp. High numbers of bacteria able to grow on media containing cellulose, carboxymethyl cellulose, or cellobiose as the substrate were found in the alimentary tracts of the millipedes. Enzyme assays indicated that most cellulose and hemicellulose degradation occurred in the midgut, whereas the hindgut was an important site for pectin degradation. Hemicellulase and β-glucosidase in both species and possibly Cx-cellulase and pectinase in O. ornatus were of possible microbial origin. Degradation of [14C]cellulose by millipedes whose gut floras were reduced by antibiotic treatment and starvation demonstrated a reduction in 14CO2 release and 14C assimilation and an increase in 14C excretion over values for controls. It appears that the millipede-bacterium association is mutualistic and makes available to millipedes an otherwise mostly unutilizable substrate. Such an association may be an important pathway for decomposition in desert ecosystems. Images PMID:16346074

  20. Strategies of aerobic microbial Fe acquisition from Fe-bearing montmorillonite clay

    NASA Astrophysics Data System (ADS)

    Kuhn, Keshia M.; DuBois, Jennifer L.; Maurice, Patricia A.

    2013-09-01

    This research investigated strategies used by the common aerobic soil bacterium Pseudomonas mendocina to acquire Fe associated with Fe(III)-bearing montmorillonite (MMT) clay. Given the known importance of Fe(III)-chelating siderophores, Fe-limited batch experiments were conducted using a wild-type (WT) strain that produces siderophores and a ΔpmhA mutant with a siderophore(-) phenotype. Growth measurements were coupled with a transcriptional biosensor assay that monitors the siderophore biosynthesis gene pmhA, measurements of cells' reducing ability, and quantification of exopolymeric substance (EPS) production. WT cells actively grow when MMT is the sole Fe source, but sorption to MMT may decrease the concentration of dissolved Fe-siderophore complex accessible to cells. Cells also obtain Fe by reducing MMT-associated Fe(III), but because P. mendocina lacks a secreted/diffusible reductant, direct physical contact is required. Dual strategies for Fe acquisition—a reducing mechanism that requires contact and that is likely facilitated by biofilm production and a siderophore related mechanism that does not require contact—provide flexibility to address the environmental Fe challenge.

  1. Efficient production and secretion of pyruvate from Halomonas sp. KM-1 under aerobic conditions.

    PubMed

    Kawata, Yoshikazu; Nishimura, Taku; Matsushita, Isao; Tsubota, Jun

    2016-03-01

    The alkaliphilic, halophilic bacterium Halomonas sp. KM-1 can utilize both hexose and pentose sugars for the intracellular storage of bioplastic poly-(R)-3-hydroxybutyric acid (PHB) under aerobic conditions. In this study, we investigated the effects of the sodium nitrate concentration on PHB accumulation in the KM-1 strain. Unexpectedly, we observed the secretion of pyruvate, a central intermediate in carbon- and energy-metabolism processes in all organisms; therefore, pyruvate is widely used as a starting material in the industrial biosynthesis of pharmaceuticals and is employed for the production of crop-protection agents, polymers, cosmetics, and food additives. We then further analyzed pyruvate productivity following changes in culture temperature and the buffer concentration. In 48-h batch-cultivation experiments, we found that wild-type Halomonas sp. KM-1 secreted 63.3 g/L pyruvate at a rate of 1.32 g/(L·h), comparable to the results of former studies using mutant and recombinant microorganisms. Thus, these data provided important insights into the production of pyruvate using this novel strain.

  2. Understanding the physiological roles of polyhydroxybutyrate (PHB) in Rhodospirillum rubrum S1 under aerobic chemoheterotrophic conditions.

    PubMed

    Narancic, Tanja; Scollica, Elisa; Kenny, Shane T; Gibbons, Helena; Carr, Eibhlin; Brennan, Lorraine; Cagney, Gerard; Wynne, Kieran; Murphy, Cormac; Raberg, Matthias; Heinrich, Daniel; Steinbüchel, Alexander; O'Connor, Kevin E

    2016-10-01

    Polyhydroxybutyrate (PHB) is an important biopolymer accumulated by bacteria and associated with cell survival and stress response. Here, we make two surprising findings in the PHB-accumulating species Rhodospirillum rubrum S1. We first show that the presence of PHB promotes the increased assimilation of acetate preferentially into biomass rather than PHB. When R. rubrum is supplied with (13)C-acetate as a PHB precursor, 83.5 % of the carbon in PHB comes from acetate. However, only 15 % of the acetate ends up in PHB with the remainder assimilated as bacterial biomass. The PHB-negative mutant of R. rubrum assimilates 2-fold less acetate into biomass compared to the wild-type strain. Acetate assimilation proceeds via the ethylmalonyl-CoA pathway with (R)-3-hydroxybutyrate as a common intermediate with the PHB pathway. Secondly, we show that R. rubrum cells accumulating PHB have reduced ribulose 1,5-bisphosphate carboxylase (RuBisCO) activity. RuBisCO activity reduces 5-fold over a 36-h period after the onset of PHB. In contrast, a PHB-negative mutant maintains the same level of RuBisCO activity over the growth period. Since RuBisCO controls the redox potential in R. rubrum, PHB likely replaces RuBisCO in this role. R. rubrum is the first bacterium found to express RuBisCO under aerobic chemoheterotrophic conditions.

  3. Complete Genome of the Cellulolytic Ruminal Bacterium Ruminococcus albus 7

    SciTech Connect

    Suen, Garret; Stevenson, David M; Bruce, David; Chertkov, Olga; Copeland, A; Cheng, Jan-Fang; Detter, J. Chris; Goodwin, Lynne A.; Han, Cliff; Hauser, Loren John; Ivanova, N; Kyrpides, Nikos C; Land, Miriam L; Lapidus, Alla L.; Lucas, Susan; Ovchinnikova, Galina; Pitluck, Sam; Tapia, Roxanne; Woyke, Tanja; Boyum, Julie; Mead, David; Weimer, Paul J

    2011-01-01

    Ruminococcus albus 7 is a highly cellulolytic ruminal bacterium that is a member of the phylum Firmicutes. Here, we describe the complete genome of this microbe. This genome will be useful for rumen microbiology and cellulosome biology and in biofuel production, as one of its major fermentation products is ethanol.

  4. Complete genome of the cellulolytic ruminal bacterium Ruminococcus albus 7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ruminococcus albus 7 is a highly cellulolytic rumen bacterium that is a member of the phylum Firmicutes. Here, we describe the complete genome for this microbe. This genome will be useful for rumen microbiology, cellulosome biology, and in biofuel production, as one of its major fermentation product...

  5. Gut bacterium of Dendrobaena veneta (Annelida: Oligochaeta) possesses antimycobacterial activity.

    PubMed

    Fiołka, Marta J; Zagaja, Mirosław P; Piersiak, Tomasz D; Wróbel, Marek; Pawelec, Jarosław

    2010-09-01

    The new bacterial strain with antimycobacterial activity has been isolated from the midgut of Dendrobaena veneta (Annelida). Biochemical and molecular characterization of isolates from 18 individuals identified all as Raoultella ornithinolytica genus with 99% similarity. The bacterium is a possible symbiont of the earthworm D. veneta. The isolated microorganism has shown the activity against four strains of fast-growing mycobacteria: Mycobacterium butiricum, Mycobacterium jucho, Mycobacterium smegmatis and Mycobacterium phlei. The multiplication of the gut bacterium on plates with Sauton medium containing mycobacteria has caused a lytic effect. After the incubation of the cell free extract prepared from the gut bacterium with four strains of mycobacteria in liquid Sauton medium, the cells of all tested strains were deformed and divided to small oval forms and sometimes created long filaments. The effect was observed by the use of light, transmission and scanning microscopy. Viability of all examined species of mycobacteria was significantly decreased. The antimycobacterial effect was probably the result of the antibiotic action produced by the gut bacterium of the earthworm. The application of ultrafiltration procedure allowed to demonstrate that antimicrobial substance with strong antimycobacterial activity from bacterial culture supernatant, is a protein with the molecular mass above 100 kDa.

  6. Hydrogenotrophic denitrification process efficiency and the number of denitrifying bacteria (MPN) in the sequencing batch biofilm reactor (SBBR) with platinum and carbon anodes.

    PubMed

    Kłodowska, Izabella; Rodziewicz, Joanna; Janczukowicz, Wojciech; Gotkowska-Płachta, Anna; Cydzik-Kwiatkowska, Agnieszka

    2016-01-01

    This work reports on the effect of electric current density and anode material (platinum, carbon) on the concentration of oxidized and mineral forms of nitrogen, on physical parameters (pH, redox potential, electrical conductivity) and the number of denitrifying bacteria in the biofilm (MPN). Experiments were conducted under anaerobic conditions without and with the flow of electric current (with density of 79 mA · m(-2) and 132 mA · m(-2)). Results obtained in the study enabled concluding that increasing density of electric current caused a decreasing concentration of nitrate in the reactor with platinum anode (R1) and carbon anode (R2). Its concentration depended on anode material. The highest hydrogenotrophic denitrification efficiency was achieved in R2 in which the process was aided by inorganic carbon (CO2) that originated from carbon anode oxidation and the electrical conductivity of wastewater increased as a result of the presence of HCO3(-) and CO3(2-) ions. Strong oxidizing properties of the platinum anode (R1) prevented the accumulation of adverse forms of nitrogen, including nitrite and ammonia. The increase in electric current density affected also a lower number of denitrifying bacteria (MPN) in the biofilm in both reactors (R1 and R2). Metal oxides accumulated on the surface of the cathode had a toxic effect upon microorganisms and impaired the production of a hydrogen donor.

  7. The contrast study of anammox-denitrifying system in two non-woven fixed-bed bioreactors (NFBR) treating different low C/N ratio sewage.

    PubMed

    Gao, Fan; Zhang, Hanmin; Yang, Fenglin; Qiang, Hong; Zhang, Guangyi

    2012-06-01

    Two non-woven fixed-bed bioreactors (NFBR) based on different substrates (nitrite and nitrate) were constructed to study the environmental adaptability for temperature and organic matter of anammox-denitrifying system and nitrogen removal performance. The two reactors were successfully operated for 200 days. The average removal rates of nitrogen and COD of R2 were 81% and 93%, respectively. Besides, the nitrogen removal rate of R1 was 95% under not more than 105 mg/l of COD. The experimental results indicated that the R2 based on nitrate had a good nitrogen removal performance at room temperature (25 °C). Additionally, the analysis results of fluorescence in situ hybridization (FISH) showed that the percentage compositions of anammox in R1 and R2 were 84% and 65% on day 189. Finally, the possible nitrogen removal model of anammox-denitrifying system was constructed. According to nitrogen balance and C/N ratios of denitrification, the nitrogen removal approaches of R1 and R2 were obtained.

  8. Impact of electro-stimulation on denitrifying bacterial growth and analysis of bacterial growth kinetics using a modified Gompertz model in a bio-electrochemical denitrification reactor.

    PubMed

    Liu, Hengyuan; Chen, Nan; Feng, Chuanping; Tong, Shuang; Li, Rui

    2017-05-01

    This study aimed to investigate the effect of electro-stimulation on denitrifying bacterial growth in a bio-electrochemical reactor, and the growth were modeled using modified Gompertz model under different current densities at three C/Ns. It was found that the similar optimum current density of 250mA/m(2) was obtained at C/N=0.75, 1.00 and 1.25, correspondingly the maximum nitrate removal efficiencies were 98.0%, 99.2% and 99.9%. Moreover, ATP content and cell membrane permeability of denitrifying bacteria were significantly increased at optimum current density. Furthermore, modified Gompertz model fitted well with the microbial growth curves, and the highest maximum growth rates (µmax) and shorter lag time were obtained at the optimum current density for all C/Ns. This study demonstrated that the modified Gompertz model could be used for describing microbial growth under