WorldWideScience

Sample records for oxidizing bacteria aob

  1. Detection of Ammonia-Oxidizing Bacteria (AOB) Using a Porous Silicon Optical Biosensor Based on a Multilayered Double Bragg Mirror Structure.

    Science.gov (United States)

    Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

    2018-01-01

    We successfully demonstrate a porous silicon (PS) double Bragg mirror by electrochemical etching at room temperature as a deoxyribonucleic acid (DNA) label-free biosensor for detecting ammonia-oxidizing bacteria (AOB). Compared to various other one-dimension photonic crystal configurations of PS, the double Bragg mirror structure is quite easy to prepare and exhibits interesting optical properties. The width of high reflectivity stop band of the PS double Bragg mirror is about 761 nm with a sharp and deep resonance peak at 1328 nm in the reflectance spectrum, which gives a high sensitivity and distinguishability for sensing performance. The detection sensitivity of such a double Bragg mirror structure is illustrated through the investigation of AOB DNA hybridization in the PS pores. The redshifts of the reflectance spectra show a good linear relationship with both complete complementary and partial complementary DNA. The lowest detection limit for complete complementary DNA is 27.1 nM and the detection limit of the biosensor for partial complementary DNA is 35.0 nM, which provides the feasibility and effectiveness for the detection of AOB in a real environment. The PS double Bragg mirror structure is attractive for widespread biosensing applications and provides great potential for the development of optical applications.

  2. Consumption of ammonia-nitrogen by aob in immobilized batch ...

    African Journals Online (AJOL)

    This study investigated the performance of bio-filters immobilized nitrifying bacteria, ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). In particular, it was to assess the consumption of ammonia-nitrogen (NH3-N) by the AOB. The experiment was conducted in a one litre reactor.The reactor consisted of ...

  3. Phenols in anaerobic digestion processes and inhibition of ammonia oxidising bacteria (AOB) in soil

    International Nuclear Information System (INIS)

    Leven, Lotta; Nyberg, Karin; Korkea-aho, Lena; Schnuerer, Anna

    2006-01-01

    This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC 5 = 26 μg phenols g -1 d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC 5 = 43-110 μg g -1 d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem

  4. Quantification of nitrous oxide (N2O) emissions and soluble microbial product (SMP) production by a modified AOB-NOB-N2O-SMP model.

    Science.gov (United States)

    Kim, MinJeong; Wu, Guangxue; Yoo, ChangKyoo

    2017-03-01

    A modified AOB-NOB-N 2 O-SMP model able to quantify nitrous oxide (N 2 O) emissions and soluble microbial product (SMP) production during wastewater treatment is proposed. The modified AOB-NOB-N 2 O-SMP model takes into account: (1) two-step nitrification by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), (2) N 2 O production by AOB denitrification under oxygen-limited conditions and (3) SMP production by microbial growth and endogenous respiration. Validity of the modified model is demonstrated by comparing the simulation results with experimental data from lab-scale sequencing batch reactors (SBRs). To reliably implement the modified model, a model calibration that adjusts model parameters to fit the model outputs to the experimental data is conducted. The results of this study showed that the modeling accuracy of the modified AOB-NOB-N 2 O-SMP model increases by 19.7% (NH 4 ), 51.0% (NO 2 ), 57.8% (N 2 O) and 16.7% (SMP) compared to the conventional model which does not consider the two-step nitrification and SMP production by microbial endogenous respiration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Potential nitrous oxide yield of AOA vs. AOB and utilization of carbon and nitrogen in the ammonia oxidizing process in the Pearl River Estuary

    Science.gov (United States)

    Ma, L.; Dai, M.; Tan, S.; Xia, X.; Liu, H.

    2016-12-01

    Nitrous oxide (N2O), a greenhouse gas, is a by-product during ammonia oxidation process, the production of which is often stimulated under low dissolved oxygen (DO) in the estuarine environment. The potential yield of N2O has been considered to be driven by ammonia-oxidizing bacteria (AOB) of Betaproteobacteria & Gammaproteobacteria and/or ammonia-oxidizing archaea (AOA) of Thaumarchaeota. In order to examine the relative importance of AOA and AOB in producing N2O and in modulating the potential N2O yield, arch-amoA, beta-amoA, gamma-amoA encoding for the alpha subunit of the ammonia monooxygenase (AMO) are used as biomarkers to identify the distributions and bioactivities of AOA and AOB in the Pearl River Estuary (PRE). Size fractionation experiments were conducted to distinguish AOA and AOB on particles in different size-fractions of > 3 μm, 0.45-3 μm, and 0.22-0.45 μm. Pure culture of N. maritimusSCM1 was studied as a model organism to identify the organic carbon production during ammonia oxidation by SCM1 strains. Our results show that AOA distributes largely in the free-living state and could adapt to very limited ammonia substrate and low saturation of DO; AOB mainly distributes at the particle-attached state under relative richer ammonia and high DO conditions; however, the RNA/DNA ratio of AOB was higher than that of AOA under the same conditions suggesting AOB is relatively more actively expressed. In the upper reach of PRE, the dominant microorganism in the water column was AOB and the in situ N2O/NH3 therein ranged 0.73-3.74 ‰. In the lower PRE, AOA was dominated, and the in situ N2O/NH3 was of 1.17- 7.32‰. At selected sites, we estimated isotope effect (e) of AOA (eDIC/bulk) as -23.94‰ and AOB (eDIC/bulk) as -56.6‰ to -44.8‰, which is consistent with the studies of pure cultures. The coefficient of C sequestration "k", defined as (C biomass / DIC in situ) / (N biomass / ammonia in situ) to differ the utilization of carbon and nitrogen, of

  6. Contributions of ammonia-oxidizing archaea and bacteria to nitrification in Oregon forest soils

    Science.gov (United States)

    Xinda Lu; Peter J. Bottomley; David D. Myrold

    2015-01-01

    Ammonia oxidation, the first step of nitrification, is mediated by both ammonia-oxidizing archaea (AOA) and bacteria (AOB); however, the relative contributions of AOA and AOB to soil nitrification are not well understood. In this study we used 1-octyne to discriminate between AOA-and AOB-supported nitrifi-cation determined both in soil-water slurries and in unsaturated...

  7. Determination of Ammonia Oxidizing Bacteria and Nitrate Oxidizing Bacteria in Wastewater and Bioreactors

    Science.gov (United States)

    Francis, Somilez Asya

    2014-01-01

    The process of water purification has many different physical, chemical, and biological processes. One part of the biological process is the task of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Both play critical roles in the treatment of wastewater by oxidizing toxic compounds. The broad term is nitrification, a naturally occurring process that is carried out by AOB and NOB by using oxidation to convert ammonia to nitrite and nitrite to nitrate. To monitor this biological activity, bacterial staining was performed on wastewater contained in inoculum tanks and biofilm samples from bioreactors. Using microscopy and qPCR, the purpose of this experiment was to determine if the population of AOB and NOB in wastewater and membrane bioreactors changed depending on temperature and hibernation conditions to determine the optimal parameters for AOB/NOB culture to effectively clean wastewater.

  8. Ammonia oxidizing bacteria community dynamics in a pilot-scale wastewater treatment plant.

    Directory of Open Access Journals (Sweden)

    Xiaohui Wang

    Full Text Available BACKGROUND: Chemoautotrophic ammonia oxidizing bacteria (AOB have the metabolic ability to oxidize ammonia to nitrite aerobically. This metabolic feature has been widely used, in combination with denitrification, to remove nitrogen from wastewater in wastewater treatment plants (WWTPs. However, the relative influence of specific deterministic environmental factors to AOB community dynamics in WWTP is uncertain. The ecological principles underlying AOB community dynamics and nitrification stability and how they are related are also poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: The community dynamics of ammonia oxidizing bacteria (AOB in a pilot-scale WWTP were monitored over a one-year period by Terminal Restriction Fragment Length Polymorphism (T-RFLP. During the study period, the effluent ammonia concentrations were almost below 2 mg/L, except for the first 60 days, indicting stable nitrification. T-RFLP results showed that, during the test period with stable nitrification, the AOB community structures were not stable, and the average change rate (every 15 days of AOB community structures was 10% ± 8%. The correlations between T-RFLP profiles and 10 operational and environmental parameters were tested by Canonical Correlation Analysis (CCA and Mantel test. The results indicated that the dynamics of AOB community correlated most strongly with Dissolved Oxygen (DO, effluent ammonia, effluent Biochemical Oxygen Demand (BOD and temperature. CONCLUSIONS/SIGNIFICANCE: This study suggests that nitrification stability is not necessarily accompanied by a stable AOB community, and provides insight into parameters controlling the AOB community dynamics within bioreactors with stable nitrification.

  9. [Effects of transgenic Bt + CpTI cotton on rhizosphere bacteria and ammonia oxidizing bacteria population].

    Science.gov (United States)

    Dong, Lianhua; Meng, Ying; Wang, Jing

    2014-03-04

    The effect of transgenic cotton on the rhizosphere bacteria can be important to the risk assessment for the genetically modified crops. We studied the rhizosphere microbial community with cultivating genetically modified cotton. The effects of transgenic Bt + CpTI Cotton (SGK321) and its receptor cotton (SY321) on rhizosphere total bacteria and ammonia oxidizing bacteria population size were studied by using droplet digital PCR. We collected rhizosphere soil before cotton planting and along with the cotton growth stage (squaring stage, flowering stage, belling stage and boll opening stage). There was no significant change on the total bacterial population between the transgenic cotton and the receptor cotton along with the growth stage. However, the abundance of ammonia oxidizing bacteria (AOB) in both type of cottons showed significant difference between different growth stages, and the variation tendency was different. In squaring stage, the numbers of AOB in rhizosphere of SY321 and SGK321 increased 4 and 2 times, respectively. In flowering stage, AOB number in rhizosphere of SY321 significantly decreased to be 5.96 x 10(5) copies/g dry soil, however, that of SGK321 increased to be 1.25 x 10(6) copies/g dry soil. In belling stage, AOB number of SY321 greatly increased to be 1.49 x 10(6) copies/g dry soil, but no significant change was observed for AOB number of SGK321. In boll opening stage, both AOB number of SY321 and SGK321 clearly decreased and they were significantly different from each other. Compared to the non-genetically modified cotton, the change in abundance of ammonia oxidizing bacteria was slightly smooth in the transgenic cotton. Not only the cotton growth stage but also the cotton type caused this difference. The transgenic cotton can slow down the speed of ammonia transformation through impacting the number of AOB, which is advantageous for plant growth.

  10. The reaction of monochloramine and hydroxylamine: implications for ammonia–oxidizing bacteria in chloraminated drinking water

    Science.gov (United States)

    Drinking water chloramine use may promote ammonia–oxidizing bacteria (AOB) growth because of naturally occurring ammonia, residual ammonia remaining from chloramine formation, and ammonia released from chloramine decay and demand. A rapid chloramine residual loss is often associa...

  11. [Distribution and Diversity of Ammonium-oxidizing Archaea and Ammonium-oxidizing Bacteria in Surface Sediments of Oujiang River].

    Science.gov (United States)

    Li, Hu; Huang, Fu-yi; Su, Jian-qiang; Hong, You-wei; Yu, Shen

    2015-12-01

    Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) play important roles in the biogeochemical nitrogen cycle. Rivers are important ecosystems containing a large number of functional microbes in nitrogen cycle. In this study, denaturing gradient gel electrophoresis (DGGE ) and real-time quantitative PCR (qPCR) technology were used to analyze the distribution and diversity of AOA and AOB in sediments from Oujiang. The results showed that the AOA community structure was similar among various sites, while the AOB community structure was significantly different, in which all detected AOB sequences were classified into Nitrosospira and Nitrosomonas, and 90% affiliated to Nitrosospira. The community composition of AOA was influenced by NH₄⁺ and TS, in addition, the AOB composition was affected by NH₄⁺, EC, pH, NO₃⁻, TC and TN. Total sulfur (TS) and electrical conductivity (EC) were the major factors influencing the diversity of AOA and AOB, respectively. AOA abundance was significantly higher than that of AOB. EC, NH₄⁺-N and NO₃⁻-N were the main environmental factors affecting the abundance of AOA and AOB. This study indicated that the community composition and diversity of AOA and AOB were significantly influenced by environmental factors, and AOA might be dominant drivers in the ammonia oxidation process in Oujiang surface sediment.

  12. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2002-01-01

    The influence of environmental factors on the community structure of ammonia-oxidizing bacteria (AOB) was investigated in the Schelde estuary. Simultaneously with the increase of oxygen and salinity, a shift of the dominant AOB was observed. Molecular analysis based on 16S rRNA genes showed that the

  13. Archaea produce lower yields of N2 O than bacteria during aerobic ammonia oxidation in soil.

    Science.gov (United States)

    Hink, Linda; Nicol, Graeme W; Prosser, James I

    2017-12-01

    Nitrogen fertilisation of agricultural soil contributes significantly to emissions of the potent greenhouse gas nitrous oxide (N 2 O), which is generated during denitrification and, in oxic soils, mainly by ammonia oxidisers. Although laboratory cultures of ammonia oxidising bacteria (AOB) and archaea (AOA) produce N 2 O, their relative activities in soil are unknown. This work tested the hypothesis that AOB dominate ammonia oxidation and N 2 O production under conditions of high inorganic ammonia (NH 3 ) input, but result mainly from the activity of AOA when NH 3 is derived from mineralisation. 1-octyne, a recently discovered inhibitor of AOB, was used to distinguish N 2 O production resulting from archaeal and bacterial ammonia oxidation in soil microcosms, and specifically inhibited AOB growth, activity and N 2 O production. In unamended soils, ammonia oxidation and N 2 O production were lower and resulted mainly from ammonia oxidation by AOA. The AOA N 2 O yield relative to nitrite produced was half that of AOB, likely due to additional enzymatic mechanisms in the latter, but ammonia oxidation and N 2 O production were directly linked in all treatments. Relative contributions of AOA and AOB to N 2 O production, therefore, reflect their respective contributions to ammonia oxidation. These results suggest potential mitigation strategies for N 2 O emissions from fertilised agricultural soils. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Substrate and nutrient limitation of ammonia-oxidizing bacteria and archaea in temperate forest soil

    Science.gov (United States)

    J.S. Norman; J.E. Barrett

    2014-01-01

    Ammonia-oxidizing microbes control the rate-limiting step of nitrification, a critical ecosystem process, which affects retention and mobility of nitrogen in soil ecosystems. This study investigated substrate (NH4þ) and nutrient (K and P) limitation of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in temperate forest soils at Coweeta Hydrologic...

  15. Modeling of nitrous oxide production by autotrophic ammonia-oxidizing bacteria with multiple production pathways.

    Science.gov (United States)

    Ni, Bing-Jie; Peng, Lai; Law, Yingyu; Guo, Jianhua; Yuan, Zhiguo

    2014-04-01

    Autotrophic ammonia oxidizing bacteria (AOB) have been recognized as a major contributor to N2O production in wastewater treatment systems. However, so far N2O models have been proposed based on a single N2O production pathway by AOB, and there is still a lack of effective approach for the integration of these models. In this work, an integrated mathematical model that considers multiple production pathways is developed to describe N2O production by AOB. The pathways considered include the nitrifier denitrification pathway (N2O as the final product of AOB denitrification with NO2(-) as the terminal electron acceptor) and the hydroxylamine (NH2OH) pathway (N2O as a byproduct of incomplete oxidation of NH2OH to NO2(-)). In this model, the oxidation and reduction processes are modeled separately, with intracellular electron carriers introduced to link the two types of processes. The model is calibrated and validated using experimental data obtained with two independent nitrifying cultures. The model satisfactorily describes the N2O data from both systems. The model also predicts shifts of the dominating pathway at various dissolved oxygen (DO) and nitrite levels, consistent with previous hypotheses. This unified model is expected to enhance our ability to predict N2O production by AOB in wastewater treatment systems under varying operational conditions.

  16. Spatial distribution of ammonia-oxidizing archaea and bacteria across eight freshwater lakes in sediments from Jiangsu of China

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2014-03-01

    Full Text Available Ammonia-oxidizingarchaea (AOA and ammonia-oxidizing bacteria (AOB play an important role innitrogen transformation in freshwater sediments. However, it is still unclear towhat extent the distribution patterns of these microorganisms are affected bythe freshwater sediment across a large geographical scale. This study wasdesigned to gain insight into the heterogeneity distribution of AOA and AOB in32 freshwater sediments from a wide range of ecologic types. Real-time quantitative polymerasechain reaction PCR(qPCR combined with the terminal restrictionfragment length polymorphism(T-RFLP were employed to characterize the abundance, diversity, and communitystructure of the AOA and AOB in 32 freshwater sediments. AOA and AOB wereubiquitous in all sediments, and archaeal amoA far outnumbered bacterial amoA inmost sediments with lower organic matters. The abundance of AOA and AOB did notvary with the freshwater ecological type (macrophyte dominated region and algaedominated region. Based on  the T-RFLP of an amoA gene, this research found that organicmatters in pore water rather than other factors affect the AOA communitystructure in sediments, while the AOB were not significantly different in thefreshwater sediments. Phylogenetic analysis showed that all archaeal amoAsequences fell within either the Crenarchaeotal Group (CG I.1b or the CGI.1asubgroup, and all AOB clustered with genus Nitrosomonas or Nitrosospira. The data obtained inthis study elucidates the role of ammonia-oxidizing archaea andammonia-oxidizing bacteria in the nitrogen cycle of freshwater ecosystems.

  17. Response of ammonia oxidizing archaea and bacteria to decabromodiphenyl ether and copper contamination in river sediments.

    Science.gov (United States)

    Wang, Linqiong; Li, Yi; Niu, Lihua; Zhang, Wenlong; Zhang, Huanjun; Wang, Longfei; Wang, Peifang

    2018-01-01

    Ammonia oxidation plays a fundamental role in river nitrogen cycling ecosystems, which is normally governed by both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB). Co-contamination of typical emerging pollutant Polybrominated diphenyl ethers (PBDEs) and heavy metal on AOA and AOB communities in river sediments remains unknown. In this study, multiple analytical tools, including high-throughput pyrosequencing and real-time quantitative PCR (qPCR), were used to reveal the ammonia monooxygenase (AMO) activity, subunit alpha (amoA) gene abundance, and community structures of AOA and AOB in river sediments. It was found that the inhibition of AMO activities was increased with the increase of decabromodiphenyl ether (BDE 209, 1-100 mg kg -1 ) and copper (Cu, 50-500 mg kg -1 ) concentrations. Moreover, the synergic effects of BDE 209 and Cu resulted in a higher AMO activity reduction than the individual pollutant BDE 209. The AOA amoA copy number declined by 75.9% and 83.2% and AOB amoA gene abundance declined 82.8% and 90.0% at 20 and 100 mg kg -1 BDE 209 with a 100 mg kg -1 Cu co-contamination, respectively. The pyrosequencing results showed that both AOB and AOA community structures were altered, with a higher change of AOB than that of AOA. The results demonstrated that the AOB microbial community may be better adapted to BDE 209 and Cu pollution, while AOA might possess a greater capacity for stress resistance. Our study provides a better understanding of the ecotoxicological effects of heavy metal and micropollutant combined exposure on AOA and AOB in river sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Mechanisms of Persistence of the Ammonia-Oxidizing Bacteria Nitrosomonas to the Biocide Free Nitrous Acid.

    Science.gov (United States)

    Laloo, Andrew E; Wei, Justin; Wang, Dongbo; Narayanasamy, Shaman; Vanwonterghem, Inka; Waite, David; Steen, Jason; Kaysen, Anne; Heintz-Buschart, Anna; Wang, Qilin; Schulz, Benjamin; Nouwens, Amanda; Wilmes, Paul; Hugenholtz, Philip; Yuan, Zhiguo; Bond, Philip L

    2018-05-01

    Free nitrous acid (FNA) exerts a broad range of antimicrobial effects on bacteria, although susceptibility varies considerably among microorganisms. Among nitrifiers found in activated sludge of wastewater treatment processes (WWTPs), nitrite-oxidizing bacteria (NOB) are more susceptible to FNA compared to ammonia-oxidizing bacteria (AOB). This selective inhibition of NOB over AOB in WWTPs bypasses nitrate production and improves the efficiency and costs of the nitrogen removal process in both the activated sludge and anaerobic ammonium oxidation (Anammox) system. However, the molecular mechanisms governing this atypical tolerance of AOB to FNA have yet to be understood. Herein we investigate the varying effects of the antimicrobial FNA on activated sludge containing AOB and NOB using an integrated metagenomics and label-free quantitative sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) metaproteomic approach. The Nitrosomonas genus of AOB, on exposure to FNA, maintains internal homeostasis by upregulating a number of known oxidative stress enzymes, such as pteridine reductase and dihydrolipoyl dehydrogenase. Denitrifying enzymes were upregulated on exposure to FNA, suggesting the detoxification of nitrite to nitric oxide. Interestingly, proteins involved in stress response mechanisms, such as DNA and protein repair enzymes, phage prevention proteins, and iron transport proteins, were upregulated on exposure to FNA. In addition enzymes involved in energy generation were also upregulated on exposure to FNA. The total proteins specifically derived from the NOB genus Nitrobacter was low and, as such, did not allow for the elucidation of the response mechanism to FNA exposure. These findings give us an understanding of the adaptive mechanisms of tolerance within the AOB Nitrosomonas to the biocidal agent FNA.

  19. The transformation from anammox granules to deammonification granules in micro-aerobic system by facilitating indigenous ammonia oxidizing bacteria.

    Science.gov (United States)

    Wang, Xiaolong; Gao, Dawen

    2018-02-01

    Granular deammonification process is a good way to retain aerobic and anaerobic ammonia oxidizing bacteria (AOB and anammox bacteria) and exhaust flocculent nitrite oxidizing bacteria (NOB). In this study, to facilitate indigenous AOB growth on anammox granules, by stepwise reducing influent nitrite, anammox granules were effectively transformed into deammonification granules in a micro-aerobic EGSB in 100 days. Total nitrogen removal efficiency of 90% and nitrogen removal rate of 2.3 g N/L/d were reached at stable deammonification stage. High influent FA and limited oxygen supply contributed suppression for Nitrospira-like NOB. In transition stages, Proteobacteria and Chloroflexi were always dominated. Anammox abundance decreased, while AOB abundance grew fast. Anammox bacteria and AOB were dominated by Brocadia fulgida and Nitrosomonas europaea, respectively. Denitrification activity and bacteria existed although without influent organic. The final AOB abundance was about 4.55-13.8 times more than anammox bacteria abundance, with almost equal potential activities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

    Science.gov (United States)

    Qian, Wenting; Peng, Yongzhen; Li, Xiyao; Zhang, Qiong; Ma, Bin

    2017-11-01

    The free ammonia (FA) inhibition on ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anaerobic condition was investigated in this study. The results indicated that NOB was more sensitive to the FA anaerobic treatment than AOB. The FA anaerobic inhibition on nitrifier gradually heightened with the increase of FA concentration. Accompanied with FA concentration increase from 0 to 16.82mgNH 3 -N·L -1 (the highest concentration adopted in this study), the activity of AOB reduced by 15.9%, while NOB decreased by 29.2%. After FA anaerobic treatment, nitrite was accumulated during nitrification. However, the nitrite accumulation disappeared on the sixth cycle of activity recovery tests with excessive aeration. Based on this result, a novel strategy for achieving nitritation is proposed, which involves recirculating a portion of the activated sludge through a side-line sludge treatment unit, where the sludge is subjected to treatment with FA under anaerobic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

    Directory of Open Access Journals (Sweden)

    Mariusz Cycoń

    2015-01-01

    Full Text Available The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB in soil using the denaturing gradient gel electrophoresis (DGGE approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S and the Shannon-Wiener index (H values for soil treated with the field rate (FR dosage of imidacloprid (1 mg/kg soil showed no changes in measured indices for the AOA and AOB community members. In turn, the 10*FR dosage of insecticide (10 mg/kg soil negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4+, known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

  2. Diversity of ammonia-oxidizing bacteria in relation to soil environment in Ebinur Lake Wetland

    Directory of Open Access Journals (Sweden)

    Wenge Hu

    2016-03-01

    Full Text Available Ammonia oxidation is the first and rate-limiting step of nitrification and is carried out by ammonia-oxidizing bacteria (AOB. Ebinur Lake Wetland, the most representative temperate arid zone wetland ecosystem in China, is the centre of oasis and desertification of the northern slope of Tianshan conjugate. Soil samples were collected from three sites (Tamarix ramosissima, Halocnemum strobilaceum and Phragmites australis and different soil layers (0–5, 5–15, 15–25 and 25–35 cm in this wetland in spring, summer and autumn and were used to characterize the diversity of AOB based on the ammonia monooxygenase (amoA gene. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE and bivariate correlation analysis were used to analyse the relationship between the diversity of AOB and soil environment factors. The PCR-DGGE indicated that the diversity of AOB was high in the entire sample and the Shannon diversity index varied from 1.369 to 2.471. The phylogenetic analysis showed that the amoA fragments were grouped into Nitrosospira sp. and Nitrosomonas sp. Most amoA gene sequences fell within the Nitrosospira sp. cluster, and only a few sequences were clustered with Nitrosomonas sp., indicating that Nitrosospira sp. may be more adaptable than Nitrosomonas sp. in this area. Bivariate correlation analysis showed that the diversity of AOB was significantly correlated with soil organic matter, conductivity, total phosphorus and nitrate in the Ebinur Lake Wetland in Xinjiang.

  3. Abundance and diversity of ammonia-oxidizing archaea and bacteria in the rhizosphere soil of three plants in the Ebinur Lake wetland.

    Science.gov (United States)

    He, Yuan; Hu, Wenge; Ma, Decao; Lan, Hongzhu; Yang, Yang; Gao, Yan

    2017-07-01

    Ammonia oxidation is carried out by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). The Ebinur Lake wetland is the best example of a temperate arid zone wetland ecosystem in China. Soil samples were collected from rhizosphere and non-rhizosphere soil containing Halocnemum strobilaceum (samples H and H'), Phragmites australis (samples R and R'), and Karelinia caspia (samples K and K') to study the relationship between environmental factors and the community structure of AOB and AOA. Phylogenetic analysis showed that the AOA sequences belonged to the Nitrosopumilus and Nitrososphaera clusters. AOB were grouped into Nitrosospira sp. and Nitrosomonas sp. Quantitative polymerase chain reaction results showed that the AOA abundance ranged from 2.09 × 10 4 to 2.94 × 10 5 gene copies/g soil. The highest number of AOA was detected in sample K, followed by samples R and H. AOB abundance varied between 2.91 × 10 5 and 1.05 × 10 6 gene copies/g soil, which was higher than that of AOA. Redundancy analysis indicated that electrical conductivity, pH, and NH 4 + -N might influence the community structure of AOA and AOB. AOB might play a more crucial role than AOA in ammonia oxidation based on AOB's higher diversity and abundance in the Ebinur Lake wetland in Xinjiang.

  4. Molecular diversity of the ammonia-oxidizing bacteria community in disused tin-mining ponds located within Kampar, Perak, Malaysia.

    Science.gov (United States)

    Sow, S L S; Khoo, G; Chong, L K; Smith, T J; Harrison, P L; Ong, H K A

    2014-02-01

    Disused tin-mining ponds make up a significant amount of water bodies in Malaysia particularly at the Kinta Valley in the state of Perak where tin-mining activities were the most extensive, and these abundantly available water sources are widely used in the field of aquaculture and agriculture. However, the natural ecology and physicochemical conditions of these ponds, many of which have been altered due to secondary post-mining activities, remains to be explored. As ammonia-oxidizing bacteria (AOB) are directly related to the nutrient cycles of aquatic environments and are useful bioindicators of environmental variations, the focus of this study was to identify AOBs associated with disused tin-mining ponds that have a history of different secondary activities in comparison to ponds which were left untouched and remained as part of the landscape. The 16S rDNA gene was used to detect AOBs in the sediment and water sampled from the three types of disused mining ponds, namely ponds without secondary activity, ponds that were used for lotus cultivation and post-aquaculture ponds. When the varying pond types were compared with the sequence and phylogenetic analysis of the AOB clone libraries, both Nitrosomonas and Nitrosospira-like AOB were detected though Nitrosospira spp. was seen to be the most ubiquitous AOB as it was present in all ponds types. However, AOBs were not detected in the sediments of idle ponds. Based on rarefaction analysis and diversity indices, the disused mining pond with lotus culture indicated the highest richness of AOBs. Canonical correspondence analysis indicated that among the physicochemical properties of the pond sites, TAN and nitrite were shown to be the main factors that influenced the community structure of AOBs in these disused tin-mining ponds.

  5. Changes in the ammonia-oxidizing bacteria community in response to operational parameters during the treatment of anaerobic sludge digester supernatant.

    Science.gov (United States)

    Cydzik-Kwiatkowska, Agnieszka; Zielińska, Magdalena; Bernat, Katarzyna; Kulikowska, Dorota; Wojnowska-Baryła, Irena

    2012-07-01

    The understanding of the relationship between ammoniaoxidizing bacteria (AOB) communities in activated sludge and the operational treatment parameters supports the control of the treatment of ammonia-rich wastewater. The modifications of treatment parameters by alteration of the number and length of aerobic and anaerobic stages in the sequencing batch reactor (SBR) working cycle may influence the efficiency of ammonium oxidation and induce changes in the AOB community. Therefore, in the research, the impact of an SBR cycle mode with alternating aeration/ mixing conditions (7 h/1 h vs. 4 h/5.5 h) and volumetric exchange rate (n) on AOB abundance and diversity in activated sludge during the treatment of anaerobic sludge digester supernatant at limited oxygen concentration in the aeration stage (0.7 mg O2/l) was assessed. AOB diversity expressed by the Shannon-Wiener index (H') was determined by the cycle mode. At aeration/mixing stage lengths of 7 h/1 h, H' averaged 2.48 +/- 0.17, while at 4 h/ 5.5 h it was 2.35 +/- 0.16. At the given mode, AOB diversity decreased with increasing n. The cycle mode did not affect AOB abundance; however, a higher AOB abundance in activated sludge was promoted by decreasing the volumetric exchange rate. The sequences clustering with Nitrosospira sp. NpAV revealed the uniqueness of the AOB community and the simultaneously lower ability of adaptation of Nitrosospira sp. to the operational parameters applied in comparison with Nitrosomonas sp.

  6. Ammonia-oxidizing bacteria in a chloraminated distribution system: seasonal occurrence, distribution and disinfection resistance.

    Science.gov (United States)

    Wolfe, R L; Lieu, N I; Izaguirre, G; Means, E G

    1990-02-01

    Nitrification in chloraminated drinking water can have a number of adverse effects on water quality, including a loss of total chlorine and ammonia-N and an increase in the concentration of heterotrophic plate count bacteria and nitrite. To understand how nitrification develops, a study was conducted to examine the factors that influence the occurrence of ammonia-oxidizing bacteria (AOB) in a chloraminated distribution system. Samples were collected over an 18-month period from a raw-water source, a conventional treatment plant effluent, and two covered, finished-water reservoirs that previously experienced nitrification episodes. Sediment and biofilm samples were collected from the interior wall surfaces of two finished-water pipelines and one of the covered reservoirs. The AOB were enumerated by a most-probable-number technique, and isolates were isolated and identified. The resistance of naturally occurring AOB to chloramines and free chlorine was also examined. The results of the monitoring program indicated that the levels of AOB, identified as members of the genus Nitrosomonas, were seasonally dependent in both source and finished waters, with the highest levels observed in the warm summer months. The concentrations of AOB in the two reservoirs, both of which have floating covers made of synthetic rubber (Hypalon; E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.), had most probable numbers that ranged from less than 0.2 to greater than 300/ml and correlated significantly with temperature and levels of heterotrophic plate count bacteria. No AOB were detected in the chloraminated reservoirs when the water temperature was below 16 to 18 degrees C. The study indicated that nitrifiers occur throughout the chloraminated distribution system. Higher concentrations of AOB were found in the reservoir and pipe sediment materials than in the pipe biofilm samples. The AOB were approximately 13 times more resistant to monochloramine than to free chlorine. After 33 min

  7. Substrate availability drives spatial patterns in richness of ammonia-oxidizing bacteria and archaea in temperate forest soils

    Science.gov (United States)

    J.S. Norman; J.E. Barrett

    2016-01-01

    We sought to investigate the drivers of richness of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in temperate forest soils. We sampled soils across four experimental watersheds in the Coweeta Hydrologic Laboratory, North Carolina USA. These watersheds are geographically close, but vary in soil chemistry due to differences in land use history. While we...

  8. Influence of land use intensity on the diversity of ammonia oxidizing bacteria and archaea in soils from grassland ecosystems.

    Science.gov (United States)

    Meyer, Annabel; Focks, Andreas; Radl, Viviane; Welzl, Gerhard; Schöning, Ingo; Schloter, Michael

    2014-01-01

    In the present study, the influence of the land use intensity on the diversity of ammonia oxidizing bacteria (AOB) and archaea (AOA) in soils from different grassland ecosystems has been investigated in spring and summer of the season (April and July). Diversity of AOA and AOB was studied by TRFLP fingerprinting of amoA amplicons. The diversity from AOB was low and dominated by a peak that could be assigned to Nitrosospira. The obtained profiles for AOB were very stable and neither influenced by the land use intensity nor by the time point of sampling. In contrast, the obtained patterns for AOA were more complex although one peak that could be assigned to Nitrosopumilus was dominating all profiles independent from the land use intensity and the sampling time point. Overall, the AOA profiles were much more dynamic than those of AOB and responded clearly to the land use intensity. An influence of the sampling time point was again not visible. Whereas AOB profiles were clearly linked to potential nitrification rates in soil, major TRFs from AOA were negatively correlated to DOC and ammonium availability and not related to potential nitrification rates.

  9. Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

    Science.gov (United States)

    Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

    2012-05-01

    A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

  10. Evaluating four mathematical models for nitrous oxide production by autotrophic ammonia-oxidizing bacteria.

    Science.gov (United States)

    Ni, Bing-Jie; Yuan, Zhiguo; Chandran, Kartik; Vanrolleghem, Peter A; Murthy, Sudhir

    2013-01-01

    There is increasing evidence showing that ammonia-oxidizing bacteria (AOB) are major contributors to N(2)O emissions from wastewater treatment plants (WWTPs). Although the fundamental metabolic pathways for N(2)O production by AOB are now coming to light, the mechanisms responsible for N(2)O production by AOB in WWTP are not fully understood. Mathematical modeling provides a means for testing hypotheses related to mechanisms and triggers for N(2)O emissions in WWTP, and can then also become a tool to support the development of mitigation strategies. This study examined the ability of four mathematical model structures to describe two distinct mechanisms of N(2)O production by AOB. The production mechanisms evaluated are (1) N(2)O as the final product of nitrifier denitrification with NO(2)- as the terminal electron acceptor and (2) N(2)O as a byproduct of incomplete oxidation of hydroxylamine (NH(2)OH) to NO(2)-. The four models were compared based on their ability to predict N(2)O dynamics observed in three mixed culture studies. Short-term batch experimental data were employed to examine model assumptions related to the effects of (1) NH4+ concentration variations, (2) dissolved oxygen (DO) variations, (3) NO(2)- accumulations and (4) NH(2OH as an externally provided substrate. The modeling results demonstrate that all these models can generally describe the NH4+, NO(2)-, and NO(3)- data. However, none of these models were able to reproduce all measured N(2)O data. The results suggest that both the denitrification and NH(2)OH pathways may be involved in N(2)O production and could be kinetically linked by a competition for intracellular reducing equivalents. A unified model capturing both mechanisms and their potential interactions needs to be developed with consideration of physiological complexity. Copyright © 2012 Wiley Periodicals, Inc.

  11. Influence of tropical leaf litter on nitrogen mineralization and community structure of ammonia-oxidizing bacteria

    OpenAIRE

    Diallo, M. D.; Guisse, A.; Sall, S. N.; Dick, R. P.; Assigbetsé, Komi; Dieng, A. L.; Chotte, Jean-Luc

    2015-01-01

    Description of the subject. The present study concerns the relationships among leaf litter decomposition, substrate quality, ammonia-oxidizing bacteria (AOB) community composition and nitrogen (N) availability. Decomposition of organic matter affects the biogeochemical cycling of carbon (C) and N. Since the composition of the soil microbial community can alter the physiological capacity of the community, it is timely to study the litter quality effect on N dynamic in ecosystems. Objectives. T...

  12. High abundances of potentially active ammonia-oxidizing bacteria and archaea in oligotrophic, high-altitude lakes of the Sierra Nevada, California, USA.

    Directory of Open Access Journals (Sweden)

    Curtis J Hayden

    Full Text Available Nitrification plays a central role in the nitrogen cycle by determining the oxidation state of nitrogen and its subsequent bioavailability and cycling. However, relatively little is known about the underlying ecology of the microbial communities that carry out nitrification in freshwater ecosystems--and particularly within high-altitude oligotrophic lakes, where nitrogen is frequently a limiting nutrient. We quantified ammonia-oxidizing archaea (AOA and bacteria (AOB in 9 high-altitude lakes (2289-3160 m in the Sierra Nevada, California, USA, in relation to spatial and biogeochemical data. Based on their ammonia monooxygenase (amoA genes, AOB and AOA were frequently detected. AOB were present in 88% of samples and were more abundant than AOA in all samples. Both groups showed >100 fold variation in abundance between different lakes, and were also variable through time within individual lakes. Nutrient concentrations (ammonium, nitrite, nitrate, and phosphate were generally low but also varied across and within lakes, suggestive of active internal nutrient cycling; AOB abundance was significantly correlated with phosphate (r(2 = 0.32, p<0.1, whereas AOA abundance was inversely correlated with lake elevation (r(2 = 0.43, p<0.05. We also measured low rates of ammonia oxidation--indicating that AOB, AOA, or both, may be biogeochemically active in these oligotrophic ecosystems. Our data indicate that dynamic populations of AOB and AOA are found in oligotrophic, high-altitude, freshwater lakes.

  13. Potential coupling effects of ammonia-oxidizing and anaerobic ammonium-oxidizing bacteria on completely autotrophic nitrogen removal over nitrite biofilm formation induced by the second messenger cyclic diguanylate.

    Science.gov (United States)

    Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhao, Chuanqi; Yang, Fenglin; Wang, Dong

    2017-05-01

    The objective of this study was to investigate the influence of extracellular polymeric substance (EPS) on the coupling effects between ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing (anammox) bacteria for the completely autotrophic nitrogen removal over nitrite (CANON) biofilm formation in a moving bed biofilm reactor (MBBR). Analysis of the quantity of EPS and cyclic diguanylate (c-di-GMP) confirmed that the contents of polysaccharides and c-di-GMP were correlated in the AOB sludge, anammox sludge, and CANON biofilm. The anammox sludge secreted more EPS (especially polysaccharides) than AOB with a markedly higher c-di-GMP content, which could be used by the bacteria to regulate the synthesis of exopolysaccharides that are ultimately used as a fixation matrix, for the adhesion of biomass. Indeed, increased intracellular c-di-GMP concentrations in the anammox sludge enhanced the regulation of polysaccharides to promote the adhesion of AOB and formation of the CANON biofilm. Overall, the results of this study provide new comprehensive information regarding the coupling effects of AOB and anammox bacteria for the nitrogen removal process.

  14. Ammonia-Oxidizing Archaea Show More Distinct Biogeographic Distribution Patterns than Ammonia-Oxidizing Bacteria across the Black Soil Zone of Northeast China.

    Science.gov (United States)

    Liu, Junjie; Yu, Zhenhua; Yao, Qin; Sui, Yueyu; Shi, Yu; Chu, Haiyan; Tang, Caixian; Franks, Ashley E; Jin, Jian; Liu, Xiaobing; Wang, Guanghua

    2018-01-01

    Black soils (Mollisols) of northeast China are highly productive and agriculturally important for food production. Ammonia-oxidizing microbes play an important role in N cycling in the black soils. However, the information related to the composition and distribution of ammonia-oxidizing microbes in the black soils has not yet been addressed. In this study, we used the amoA gene to quantify the abundance and community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) across the black soil zone. The amoA abundance of AOA was remarkably larger than that of AOB, with ratios of AOA/AOB in the range from 3.1 to 91.0 across all soil samples. The abundance of AOA amoA was positively correlated with total soil C content ( p 0.05). In contrast, the abundance of AOB amoA positively correlated with soil pH ( p = 0.009) but not with total soil C. Alpha diversity of AOA did not correlate with any soil parameter, however, alpha diversity of AOB was affected by multiple soil factors, such as soil pH, total P, N, and C, available K content, and soil water content. Canonical correspondence analysis indicated that the AOA community was mainly affected by the sampling latitude, followed by soil pH, total P and C; while the AOB community was mainly determined by soil pH, as well as total P, C and N, water content, and sampling latitude, which highlighted that the AOA community was more geographically distributed in the black soil zone of northeast China than AOB community. In addition, the pairwise analyses showed that the potential nitrification rate (PNR) was not correlated with alpha diversity but weakly positively with the abundance of the AOA community ( p = 0.048), whereas PNR significantly correlated positively with the richness ( p = 0.003), diversity ( p = 0.001) and abundance ( p < 0.001) of the AOB community, which suggested that AOB community might make a greater contribution to nitrification than AOA community in the black soils when

  15. Effect of communities of ammonia-oxidizing bacteria on degradation of 17-alpha-ethynylestradiol by nitrifying activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Limpiyakorn, T.; Sermwaraphan, P.; Kurisu, F.

    2009-07-01

    An endocrine disrupting compound, 17-alpha-ethynylestradiol (EE2), is a synthetic estrogen used as a key ingredient in oral contraceptives pill. this persistent organic pollutant, no biodegradable by most microorganisms, is discharged via municipal waste streams to natural receiving waters. Recently, it was found that ammonia-oxidizing bacteria (AOB) in nitrifying activated sludge (NAS) enriched with high ammonium loads can degrade EE2 via co-metabolism during ammonia oxidation. (Author)

  16. Temporal and Spatial Stability of Ammonia-Oxidizing Archaea and Bacteria in Aquarium Biofilters

    KAUST Repository

    Bagchi, Samik

    2014-12-05

    Nitrifying biofilters are used in aquaria and aquaculture systems to prevent accumulation of ammonia by promoting rapid conversion to nitrate via nitrite. Ammonia-oxidizing archaea (AOA), as opposed to ammonia-oxidizing bacteria (AOB), were recently identified as the dominant ammonia oxidizers in most freshwater aquaria. This study investigated biofilms from fixed-bed aquarium biofilters to assess the temporal and spatial dynamics of AOA and AOB abundance and diversity. Over a period of four months, ammonia-oxidizing microorganisms from six freshwater and one marine aquarium were investigated at 4–5 time points. Nitrogen balances for three freshwater aquaria showed that active nitrification by aquarium biofilters accounted for ≥81–86% of total nitrogen conversion in the aquaria. Quantitative PCR (qPCR) for bacterial and thaumarchaeal ammonia monooxygenase (amoA) genes demonstrated that AOA were numerically dominant over AOB in all six freshwater aquaria tested, and contributed all detectable amoA genes in three aquarium biofilters. In the marine aquarium, however, AOB outnumbered AOA by three to five orders of magnitude based on amoA gene abundances. A comparison of AOA abundance in three carrier materials (fine sponge, rough sponge and sintered glass or ceramic rings) of two three-media freshwater biofilters revealed preferential growth of AOA on fine sponge. Denaturing gel gradient electrophoresis (DGGE) of thaumarchaeal 16S rRNA genes indicated that community composition within a given biofilter was stable across media types. In addition, DGGE of all aquarium biofilters revealed low AOA diversity, with few bands, which were stable over time. Nonmetric multidimensional scaling (NMDS) based on denaturing gradient gel electrophoresis (DGGE) fingerprints of thaumarchaeal 16S rRNA genes placed freshwater and marine aquaria communities in separate clusters. These results indicate that AOA are the dominant ammonia-oxidizing microorganisms in freshwater aquarium

  17. Temporal and Spatial Stability of Ammonia-Oxidizing Archaea and Bacteria in Aquarium Biofilters

    KAUST Repository

    Bagchi, Samik; Vlaeminck, Siegfried E.; Sauder, Laura A.; Mosquera, Mariela; Neufeld, Josh D.; Boon, Nico; Poulain, Alexandre

    2014-01-01

    Nitrifying biofilters are used in aquaria and aquaculture systems to prevent accumulation of ammonia by promoting rapid conversion to nitrate via nitrite. Ammonia-oxidizing archaea (AOA), as opposed to ammonia-oxidizing bacteria (AOB), were recently identified as the dominant ammonia oxidizers in most freshwater aquaria. This study investigated biofilms from fixed-bed aquarium biofilters to assess the temporal and spatial dynamics of AOA and AOB abundance and diversity. Over a period of four months, ammonia-oxidizing microorganisms from six freshwater and one marine aquarium were investigated at 4–5 time points. Nitrogen balances for three freshwater aquaria showed that active nitrification by aquarium biofilters accounted for ≥81–86% of total nitrogen conversion in the aquaria. Quantitative PCR (qPCR) for bacterial and thaumarchaeal ammonia monooxygenase (amoA) genes demonstrated that AOA were numerically dominant over AOB in all six freshwater aquaria tested, and contributed all detectable amoA genes in three aquarium biofilters. In the marine aquarium, however, AOB outnumbered AOA by three to five orders of magnitude based on amoA gene abundances. A comparison of AOA abundance in three carrier materials (fine sponge, rough sponge and sintered glass or ceramic rings) of two three-media freshwater biofilters revealed preferential growth of AOA on fine sponge. Denaturing gel gradient electrophoresis (DGGE) of thaumarchaeal 16S rRNA genes indicated that community composition within a given biofilter was stable across media types. In addition, DGGE of all aquarium biofilters revealed low AOA diversity, with few bands, which were stable over time. Nonmetric multidimensional scaling (NMDS) based on denaturing gradient gel electrophoresis (DGGE) fingerprints of thaumarchaeal 16S rRNA genes placed freshwater and marine aquaria communities in separate clusters. These results indicate that AOA are the dominant ammonia-oxidizing microorganisms in freshwater aquarium

  18. Comparison of the Effects of Phenylhydrazine Hydrochloride and Dicyandiamide on Ammonia-Oxidizing Bacteria and Archaea in Andosols

    Directory of Open Access Journals (Sweden)

    Wenjie Yang

    2017-11-01

    Full Text Available Dicyandiamide, a routinely used commercial nitrification inhibitor (NI, inhibits ammonia oxidation catalyzed by ammonia monooxygenase (AMO. Phenylhydrazine hydrochloride has shown considerable potential for the development of next-generation NIs targeting hydroxylamine dehydrogenase (HAO. The effects of the AMO inhibitor and the HAO inhibitor on ammonia-oxidizing bacteria (AOB and ammonia-oxidizing archaea (AOA present in agricultural soils have not been compared thus far. In the present study, the effects of the two inhibitors on soil nitrification and the abundance of AOA and AOB as well as their community structure were investigated in a soil microcosm using quantitative polymerase chain reaction and pyrosequencing. The net nitrification rates and the growth of AOA and AOB in this soil microcosm were inhibited by both NIs. Both NIs had limited effect on the community structure of AOB and no effect on that of AOA in this soil microcosm. The effects of phenylhydrazine hydrochloride were similar to those of dicyandiamide. These results indicated that organohydrazine-based NIs have potential for the development of next-generation NIs targeting HAO in the future.

  19. Heterotrophs are key contributors to nitrous oxide production in mixed liquor under low C-to-N ratios during nitrification - batch experiments and modelling

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Pellicer i Nàcher, Carles; Petersen, Morten S.

    2017-01-01

    Nitrous oxide (N2O), a by-product of biological nitrogen removal during wastewater treatment, is produced by ammonia-oxidizing bacteria (AOB) and heterotrophic denitrifying bacteria (HB). Mathematical models are used to predict N2O emissions, often including AOB as the main N2O producer. Several...

  20. amoA Gene abundances and nitrification potential rates suggest that benthic ammonia-oxidizing bacteria and not Archaea dominate N cycling in the Colne Estuary, United Kingdom.

    Science.gov (United States)

    Li, Jialin; Nedwell, David B; Beddow, Jessica; Dumbrell, Alex J; McKew, Boyd A; Thorpe, Emma L; Whitby, Corinne

    2015-01-01

    Nitrification, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), is important in global nitrogen cycling. In estuaries where gradients of salinity and ammonia concentrations occur, there may be differential selections for ammonia-oxidizer populations. The aim of this study was to examine the activity, abundance, and diversity of AOA and AOB in surface oxic sediments of a highly nutrified estuary that exhibits gradients of salinity and ammonium. AOB and AOA communities were investigated by measuring ammonia monooxygenase (amoA) gene abundance and nitrification potentials both spatially and temporally. Nitrification potentials differed along the estuary and over time, with the greatest nitrification potentials occurring mid-estuary (8.2 μmol N grams dry weight [gdw](-1) day(-1) in June, increasing to 37.4 μmol N gdw(-1) day(-1) in January). At the estuary head, the nitrification potential was 4.3 μmol N gdw(-1) day(-1) in June, increasing to 11.7 μmol N gdw(-1) day(-1) in January. At the estuary head and mouth, nitrification potentials fluctuated throughout the year. AOB amoA gene abundances were significantly greater (by 100-fold) than those of AOA both spatially and temporally. Nitrosomonas spp. were detected along the estuary by denaturing gradient gel electrophoresis (DGGE) band sequence analysis. In conclusion, AOB dominated over AOA in the estuarine sediments, with the ratio of AOB/AOA amoA gene abundance increasing from the upper (freshwater) to lower (marine) regions of the Colne estuary. These findings suggest that in this nutrified estuary, AOB (possibly Nitrosomonas spp.) were of major significance in nitrification. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Diversity and abundance of ammonia-oxidizing

    NARCIS (Netherlands)

    Cardoso, J.F.M.F.; van Bleijswijk, J.D.L.; Witte, H.; van Duyl, F.C.

    2013-01-01

    We analysed the diversity and abundance of ammonia-oxidizing Archaea (AOA) and Bacteria (AOB) in the shallow warm-water sponge Halisarca caerulea and the deep cold-water sponges Higginsia thielei and Nodastrella nodastrella. The abundance of AOA and AOB was analysed using catalyzed reporter

  2. Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems.

    Science.gov (United States)

    Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

    2011-12-01

    Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO₂⁻) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N₂O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O₂) is associated with N₂O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N₂O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N₂O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N₂O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N₂O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

  3. Application of hierarchical oligonucleotide primer extension (HOPE) to assess relative abundances of ammonia- and nitrite-oxidizing bacteria

    KAUST Repository

    Scarascia, Giantommaso

    2017-04-04

    Background: Establishing an optimal proportion of nitrifying microbial populations, including ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), complete nitrite oxidizers (comammox) and ammonia-oxidizing archaea (AOA), is important for ensuring the efficiency of nitrification in water treatment systems. Hierarchical oligonucleotide primer extension (HOPE), previously developed to rapidly quantify relative abundances of specific microbial groups of interest, was applied in this study to track the abundances of the important nitrifying bacterial populations. Results: The method was tested against biomass obtained from a laboratory-scale biofilm-based trickling reactor, and the findings were validated against those obtained by 16S rRNA gene-based amplicon sequencing. Our findings indicated a good correlation between the relative abundance of nitrifying bacterial populations obtained using both HOPE and amplicon sequencing. HOPE showed a significant increase in the relative abundance of AOB, specifically Nitrosomonas, with increasing ammonium content and shock loading (p < 0.001). In contrast, Nitrosospira remained stable in its relative abundance against the total community throughout the operational phases. There was a corresponding significant decrease in the relative abundance of NOB, specifically Nitrospira and those affiliated to comammox, during the shock loading. Based on the relative abundance of AOB and NOB (including commamox) obtained from HOPE, it was determined that the optimal ratio of AOB against NOB ranged from 0.2 to 2.5 during stable reactor performance. Conclusions: Overall, the HOPE method was developed and validated against 16S rRNA gene-based amplicon sequencing for the purpose of performing simultaneous monitoring of relative abundance of nitrifying populations. Quantitative measurements of these nitrifying populations obtained via HOPE would be indicative of reactor performance and nitrification functionality.

  4. Comparison among amoA Primers Suited for Quantification and Diversity Analyses of Ammonia-Oxidizing Bacteria in Soil

    Science.gov (United States)

    Shimomura, Yumi; Morimoto, Sho; Hoshino, Yuko Takada; Uchida, Yoshitaka; Akiyama, Hiroko; Hayatsu, Masahito

    2012-01-01

    Ammonia monooxygenase subunit A gene (amoA) is frequently used as a functional gene marker for diversity analysis of ammonia-oxidizing bacteria (AOB). To select a suitable amoA primer for real-time PCR and PCR-denaturing gradient gel electrophoresis (DGGE), three reverse primers (degenerate primer amoA-2R; non-degenerate primers amoA-2R-GG and amoA-2IR) were examined. No significant differences were observed among the three primers in terms of quantitative values of amoA from environmental samples using real-time PCR. We found that PCR-DGGE analysis with the amoA-2IR primer gave the best results in this studied soil. These results indicate that amoA-2IR is a suitable primer for community analysis of AOB in the environment. PMID:22075625

  5. Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch.

    Science.gov (United States)

    Guo, Chang-Zi; Fu, Wei; Chen, Xue-Mei; Peng, Dang-Cong; Jin, Peng-Kang

    2013-07-01

    Oxidation-ditch operation modes were simulated using sequencing batch reactors (SBRs) with alternate stirring and aerating. The nitrogen-removal efficiencies and nitrifying characteristics of two aeration modes, point aeration and step aeration, were investigated. Under the same air-supply capacity, oxygen dissolved more efficiently in the system with point aeration, forming a larger aerobic zone. The nitrifying effects were similar in point aeration and step aeration, where the average removal efficiencies of NH4(+) N were 98% and 96%, respectively. When the proportion of anoxic and oxic zones was 1, the average removal efficiencies of total nitrogen (TN) were 45% and 66% under point aeration and step aeration, respectively. Step aeration was more beneficial to both anoxic denitrification and simultaneous nitrification and denitrification (SND). The maximum specific ammonia-uptake rates (AUR) of point aeration and step aeration were 4.7 and 4.9 mg NH4(+)/(gMLVSS h), respectively, while the maximum specific nitrite-uptake rates (NUR) of the two systems were 7.4 and 5.3 mg NO2(-)-N/(gMLVSS h), respectively. The proportions of ammonia-oxidizing bacteria (AOB) to all bacteria were 5.1% under point aeration and 7.0% under step aeration, and the proportions of nitrite-oxidizing bacteria (NOB) reached 6.5% and 9.0% under point and step aeration, respectively. The dominant genera of AOB and NOB were Nitrosococcus and Nitrospira, which accounted for 90% and 91%, respectively, under point aeration, and the diversity of nitrifying bacteria was lower than under step aeration. Point aeration was selective of nitrifying bacteria. The abundance of NOB was greater than that of AOB in both of the operation modes, and complete transformation of NH4(+) N to NO3(-)-N was observed without NO2(-)-N accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Distributions and activities of ammonia oxidizing bacteria and polyphosphate accumulating organisms in a pumped-flow biofilm reactor.

    Science.gov (United States)

    Wu, Guangxue; Nielsen, Michael; Sorensen, Ketil; Zhan, Xinmin; Rodgers, Michael

    2009-10-01

    The spatial distributions and activities of ammonia oxidizing bacteria (AOB) and polyphosphate accumulating organisms (PAOs) were investigated for a novel laboratory-scale sequencing batch pumped-flow biofilm reactor (PFBR) system that was operated for carbon, nitrogen and phosphorus removal. The PFBR comprised of two 16.5l tanks (Reactors 1 and 2), each with a biofilm module of 2m(2) surface area. To facilitate the growth of AOB and PAOs in the reactor biofilms, the influent wastewater was held in Reactor 1 under stagnant un-aerated conditions for 6 h after feeding, and was then pumped over and back between Reactors 1 and 2 for 12 h, creating aerobic conditions in the two reactors during this period; as a consequence, the biofilm in Reactor 2 was in an aerobic environment for almost all the 18.2 h operating cycle. A combination of micro-sensor measurements, molecular techniques, batch experiments and reactor studies were carried out to analyse the performance of the PFBR system. After 100 days operation at a filtered chemical oxygen demand (COD(f)) loading rate of 3.46 g/m(2) per day, the removal efficiencies were 95% COD(f), 87% TN(f) and 74% TP(f). While the PFBR microbial community structure and function were found to be highly diversified with substantial AOB and PAO populations, about 70% of the phosphorus release potential and almost 100% of the nitrification potential were located in Reactors 1 and 2, respectively. Co-enrichment of AOB and PAOs was realized in the Reactor 2 biofilm, where molecular analyses revealed unexpected microbial distributions at micro-scale, with population peaks of AOB in a 100-250 microm deep sub-surface zone and of PAOs in the 0-150 microm surface zone. The micro-distribution of AOB coincided with the position of the nitrification peak identified during micro-sensor analyses. The study demonstrates that enrichment of PAOs can be realized in a constant or near constant aerobic biofilm environment. Furthermore, the findings suggest

  7. Use of aliphatic n-alkynes to discriminate soil nitrification activities of ammonia-oxidizing thaumarchaea and bacteria.

    Science.gov (United States)

    Taylor, Anne E; Vajrala, Neeraja; Giguere, Andrew T; Gitelman, Alix I; Arp, Daniel J; Myrold, David D; Sayavedra-Soto, Luis; Bottomley, Peter J

    2013-11-01

    Ammonia (NH3)-oxidizing bacteria (AOB) and thaumarchaea (AOA) co-occupy most soils, yet no short-term growth-independent method exists to determine their relative contributions to nitrification in situ. Microbial monooxygenases differ in their vulnerability to inactivation by aliphatic n-alkynes, and we found that NH3 oxidation by the marine thaumarchaeon Nitrosopumilus maritimus was unaffected during a 24-h exposure to ≤ 20 μM concentrations of 1-alkynes C8 and C9. In contrast, NH3 oxidation by two AOB (Nitrosomonas europaea and Nitrosospira multiformis) was quickly and irreversibly inactivated by 1 μM C8 (octyne). Evidence that nitrification carried out by soilborne AOA was also insensitive to octyne was obtained. In incubations (21 or 28 days) of two different whole soils, both acetylene and octyne effectively prevented NH4(+)-stimulated increases in AOB population densities, but octyne did not prevent increases in AOA population densities that were prevented by acetylene. Furthermore, octyne-resistant, NH4(+)-stimulated net nitrification rates of 2 and 7 μg N/g soil/day persisted throughout the incubation of the two soils. Other evidence that octyne-resistant nitrification was due to AOA included (i) a positive correlation of octyne-resistant nitrification in soil slurries of cropped and noncropped soils with allylthiourea-resistant activity (100 μM) and (ii) the finding that the fraction of octyne-resistant nitrification in soil slurries correlated with the fraction of nitrification that recovered from irreversible acetylene inactivation in the presence of bacterial protein synthesis inhibitors and with the octyne-resistant fraction of NH4(+)-saturated net nitrification measured in whole soils. Octyne can be useful in short-term assays to discriminate AOA and AOB contributions to soil nitrification.

  8. Bacteria, not archaea, restore nitrification in a zinc contaminated soil.

    NARCIS (Netherlands)

    Mertens, J.; Broos, K.; Wakelin, S.A.; Kowalchuk, G.A.; Springael, D.; Smolders, E.

    2009-01-01

    Biological ammonia oxidation had long been thought to be mediated solely by discrete clades of Β- and γ-proteobacteria (ammonia-oxidizing bacteria; AOB). However, ammonia-oxidizing Crenarchaeota (ammonia-oxidizing archaea; AOA) have recently been identified and proposed to be the dominant agents of

  9. Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

    Science.gov (United States)

    Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

    2014-12-01

    This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2002-01-01

    The influence of environmental factors on the community structure of ammoniaoxidizing bacteria (AOB) was investigated in the Schelde estuary. Simultaneously with the increase of oxygen and salinity, a shift of the dominant AOB was observed. Molecular analysis based on 16S rRNA genes showed that

  11. Shifts in Abundance and Diversity of Soil Ammonia-Oxidizing Bacteria and Archaea Associated with Land Restoration in a Semi-Arid Ecosystem.

    Directory of Open Access Journals (Sweden)

    Zhu Chen

    Full Text Available The Grain to Green Project (GGP is an unprecedented land restoration action in China. The project converted large areas (ca 10 million ha of steep-sloped/degraded farmland and barren land into forest and grassland resulting in ecological benefits such as a reduction in severe soil erosion. It may also affect soil microorganisms involved in ammonia oxidization, which is a key step in the global nitrogen cycle. The methods for restoration that are typically adopted in semi-arid regions include abandoning farmland and growing drought tolerant grass (Lolium perenne L. or shrubs (Caragana korshinskii Kom.. In the present study, the effects of these methods on the abundance and diversity of ammonia-oxidizing bacteria (AOB and ammonia-oxidizing archaea (AOA were evaluated via quantitative real-time PCR, terminal restriction fragment length polymorphism and clone library analysis of amoA genes. Comparisons were made between soil samples from three restored lands and the adjacent farmland in Inner Mongolia. Both the abundance and community composition of AOB were significantly different between the restored lands and the adjacent control. Significantly lower nitrification activity was observed for the restored land. Clone library analysis revealed that all AOB amoA gene sequences were affiliated with Nitrosospira. Abundance of the populations that were associated with Nitrosospira sp. Nv6 which had possibly adapted to high concentrations of inorganic nitrogen, decreased on the restored land. Only a slight difference in the AOB communities was observed between the restored land with and without the shrub (Caragana korshinskii Kom.. A minor effect of land restoration on AOA was observed. In summary, land restoration negatively affected the abundance of AOB and soil nitrification activities, suggesting the potential role of GGP in the leaching of nitrates, and in the emission of N2O in related terrestrial ecosystems.

  12. Reverse-transcriptional gene expression of anammox and ammonia-oxidizing archaea and bacteria in soybean and rice paddy soils of Northeast China.

    Science.gov (United States)

    Wang, Jing; Dong, Hailiang; Wang, Weidong; Gu, Ji-Dong

    2014-03-01

    The relative gene expression of hydrazine oxidoreductase encoding gene (hzo) for anaerobic ammonium oxidizing bacteria (anammox) and ammonia monooxygenase encoding gene (amoA) for both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in Sanjiang Plain soybean and rice paddy soils of Northeast China was investigated by using real-time reverse-transcriptional quantitative PCR. Metabolically active populations of anammox, AOA, and AOB in rice paddy soils were evident by the presence and successful quantification of hzo mRNA and amoA mRNA genes. The expression ratio of amoA gene for both AOA and AOB varied between soybean soils and different rice paddy soils while the expression of hzo gene for anammox was detectable only in rice paddy soils by showing a diverse relative expression ratio in each soil sample. Gene expression of both archaeal and bacterial amoA genes in rice paddy soils differed among the three sampling depths, but that of hzo was not. Both archaeal and bacterial amoA genes showed an increase trend of expression level with continuation of rice paddy cultivation, but the low expression ratio of hzo gene indicated a relatively small contribution of anammox in overall removal of inorganic nitrogen through N2 even under anoxic and high nitrogen input in agriculture. Bacterial amoA gene from two soybean fields and three rice paddy fields were also analyzed for community composition by denaturing gradient gel electrophoresis fingerprint. Community shift was observed between soybean and paddy fields and within each of them. The consistent occurrence of three bands 5, 6, and 7 in all samples showed their high adaptability for both arid cultivation and continuous rice paddy cultivation. Our data suggest that AOA and AOB are playing a more important role in nitrogen transformation in agricultural soils in oxic or anoxic environment and anammox bacteria may also contribute but in a less extent to N transformation in these agricultural soils

  13. Relative contributions of archaea and bacteria to microbial ammonia oxidation differ under different conditions during agricultural waste composting.

    Science.gov (United States)

    Zeng, Guangming; Zhang, Jiachao; Chen, Yaoning; Yu, Zhen; Yu, Man; Li, Hui; Liu, Zhifeng; Chen, Ming; Lu, Lunhui; Hu, Chunxiao

    2011-10-01

    The aim of this study was to compare the relative contribution of ammonia-oxidizing archaea (AOA) and bacteria (AOB) to nitrification during agricultural waste composting. The AOA and AOB amoA gene abundance and composition were determined by quantitative PCR and denaturing gradient gel electrophoresis (DGGE), respectively. The results showed that the archaeal amoA gene was abundant throughout the composting process, while the bacterial amoA gene abundance decreased to undetectable level during the thermophilic and cooling stages. DGGE showed more diverse archaeal amoA gene composition when the potential ammonia oxidation (PAO) rate reached peak values. A significant positive relationship was observed between the PAO rate and the archaeal amoA gene abundance (R²=0.554; Parchaea dominated ammonia oxidation during the thermophilic and cooling stages. Bacteria were also related to ammonia oxidation activity (R²=0.503; P=0.03) especially during the mesophilic and maturation stages. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Influence of tropical leaf litter on nitrogen mineralization and community structure of ammonia-oxidizing bacteria

    Directory of Open Access Journals (Sweden)

    Diallo, MD.

    2015-01-01

    Full Text Available Description of the subject. The present study concerns the relationships among leaf litter decomposition, substrate quality, ammonia-oxidizing bacteria (AOB community composition and nitrogen (N availability. Decomposition of organic matter affects the biogeochemical cycling of carbon (C and N. Since the composition of the soil microbial community can alter the physiological capacity of the community, it is timely to study the litter quality effect on N dynamic in ecosystems. Objectives. The aim of this study was to determine the influence of leaf litter decomposition on N mineralization. The specific objectives of this study were to evaluate the influence of the litter biochemistry of five plants species (Faidherbia albida A.Chev., Azadirachta indica A.Juss., Casuarina equisetifolia L., Andropogon gayanus Kunth and Eragrostis tremula Hochst. ex Steud. on N mineralization in a tropical ferrous soil (Lixisol, nitrification, and genetic diversity of ammonia-oxidizing bacteria. Denaturing gradient gel electrophoresis (DGGE of amplified fragments of genes coding for 16S rRNA was used to study the development of bacterial communities during decomposition of leaf litter in soils. Method. Community structure of AOB was determined at two time periods: day 0 and day 140. Ten strains were tested and each of these strains produced a single band. Thus, DGGE DNA band patterns were used to estimate bacterial diversity. Plant secondary compounds such as polyphenols are purported to influence nutrient cycling by affecting organic matter degradation, mineralization rates, N availability and humus formation. In a laboratory study, we investigated the influence of six phenolic acids (ferulic, gallic, vanillic, syringic, p-coumaric and p-HBA acids commonly found in the plant residues on N mineralization and NH4+ and NO3- production in soils. Results. The results showed that litter type did affect soil nitrification. Faidherbia albida litter was associated with

  15. Spatial interaction of archaeal ammonia-oxidizers and nitrite-oxidizing bacteria in an unfertilized grassland soil

    Directory of Open Access Journals (Sweden)

    Barbara eStempfhuber

    2016-01-01

    Full Text Available Interrelated successive transformation steps of nitrification are performed by distinct microbial groups – the ammonia-oxidizers, comprising ammonia-oxidizing archaea (AOA and bacteria (AOB, and nitrite-oxidizers such as Nitrobacter and Nitrospira, which are the dominant genera in the investigated soils. Hence, not only their presence and activity in the investigated habitat is required for nitrification, but also their temporal and spatial interactions. To demonstrate the interdependence of both groups and to address factors promoting putative niche differentiation within each group, temporal and spatial changes in nitrifying organisms were monitored in an unfertilized grassland site over an entire vegetation period at the plot scale of 10 m². Nitrifying organisms were assessed by measuring the abundance of marker genes (amoA for AOA and AOB, nxrA for Nitrobacter, 16S rRNA gene for Nitrospira selected for the respective sub-processes. A positive correlation between numerically dominant AOA and Nitrospira, and their co-occurrence at the same spatial scale in August and October, suggests that the nitrification process is predominantly performed by these groups and is restricted to a limited timeframe. Amongst nitrite-oxidizers, niche differentiation was evident in observed seasonally varying patterns of co-occurrence and spatial separation. While their distributions were most likely driven by substrate concentrations, oxygen availability may also have played a role under substrate-limited conditions. Phylogenetic analysis revealed temporal shifts in Nitrospira community composition with an increasing relative abundance of OTU03 assigned to sublineage V from August onwards, indicating its important role in nitrite oxidation.

  16. Bacteria, not archaea, restore nitrification in a zinc-contaminated soil

    NARCIS (Netherlands)

    Mertens, J.; Broos, K.; Wakelin, S.A.; Kowalchuk, G.A.; Springael, D.; Smolders, E.

    2009-01-01

    Biological ammonia oxidation had long been thought to be mediated solely by discrete clades of - and -proteobacteria (ammonia-oxidizing bacteria; AOB). However, ammonia-oxidizing Crenarchaeota (ammonia-oxidizing archaea; AOA) have recently been identified and proposed to be the dominant agents of

  17. Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    was on the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that nitritation...... strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE than the co...

  18. Ammonia-oxidizing bacteria and archaea in wastewater treatment plant sludge and nearby coastal sediment in an industrial area in China.

    Science.gov (United States)

    Zhang, Yan; Chen, Lujun; Sun, Renhua; Dai, Tianjiao; Tian, Jinping; Wen, Donghui

    2015-05-01

    Under the increasing pressure of human activities, Hangzhou Bay has become one of the most seriously polluted waters along China's coast. Considering the excessive inorganic nitrogen detected in the bay, in this study, the impact of an effluent from a coastal industrial park on ammonia-oxidizing microorganisms (AOMs) of the receiving area was interpreted for the first time by molecular technologies. Revealed by real-time PCR, the ratio of archaeal amoA/bacterial amoA ranged from 5.68 × 10(-6) to 4.79 × 10(-5) in the activated sludge from two wastewater treatment plants (WWTPs) and 0.54-3.44 in the sediments from the effluent receiving coastal area. Analyzed by clone and pyrosequencing libraries, genus Nitrosomonas was the predominant ammonia-oxidizing bacteria (AOB), but no ammonia-oxidizing archaea (AOA) was abundant enough for sequencing in the activated sludge from the WWTPs; genus Nitrosomonas and Nitrosopumilus were the dominant AOB and AOA, respectively, in the coastal sediments. The different abundance of AOA but similar structure of AOB between the WWTPs and nearby coastal area probably indicated an anthropogenic impact on the microbial ecology in Hangzhou Bay.

  19. Halophilic and haloalkaliphilic sulfur-oxidizing bacteria

    NARCIS (Netherlands)

    Sorokin, D.Y.; Banciu, H.; Robertson, L.A.; Kuenen, J.G.; Muntyan, M.S.; Muyzer, G.; Rosenberg, E.; DeLong, F.; Delong, E.; Lory, S.; Stackebrandt, E.; Thompson, F.

    2013-01-01

    Chemotrophic sulfur-oxidizing bacteria (SOB) represent an important functional group of microorganisms responsible for the dark oxidation of reduced sulfur compounds generated by sulfidogens. Until recently, only a single genus of halophilic SOB (Halothiobacillus) has been described, and nothing was

  20. Identification of novel potential acetate-oxidizing bacteria in an acetate-fed methanogenic chemostat based on DNA stable isotope probing.

    Science.gov (United States)

    Wang, Hui-Zhong; Gou, Min; Yi, Yue; Xia, Zi-Yuan; Tang, Yue-Qin

    2018-05-11

    Acetate is a significant intermediate of anaerobic fermentation. There are two pathways for converting acetate to CH 4 and CO 2 : acetoclastic methanogenesis by acetoclastic methanogens, and syntrophic acetate oxidation by acetate-oxidizing bacteria (AOB) and hydrogenotrophic methanogens. Detailed investigations of syntrophic acetate-oxidizing bacteria (SAOB) should contribute to the elucidation of the microbial mechanisms of methanogenesis. In this study, we investigated the major phylogenetic groups of acetate-utilizing bacteria (AUB) in a mesophilic methanogenic chemostat fed with acetate as the sole carbon source by using DNA stable isotope probing (SIP) technology. The results indicated that acetoclastic methanogenesis and acetate oxidization/hydrogenotrophic methanogenesis coexisted in the mesophilic chemostat fed with acetate, operated at a dilution rate of 0.1 d -1 . OTU Ace13(9-17) (KU869530), Ace13(9-4) (KU667241), and Ace13(9-23) (KU667236), assigned to the phyla Firmicutes and Bacteroidetes, were probably potential SAOB in the chemostat, which needs further investigation. Species in the phyla Proteobacteria, Deferribacteres, Acidobacteria, Spirochaetes and Actinobacteria were probably capable of utilizing acetate for their growth. Methanoculleus was likely to be the preferred hydrogenotrophic methanogen for syntrophy with AOB in the chemostat.

  1. Abundance and diversity of ammonia-oxidizing archaea and bacteria on granular activated carbon and their fates during drinking water purification process.

    Science.gov (United States)

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki; Takahashi, Kazuhiko

    2016-01-01

    Ammonia is a precursor to trichloramine, which causes an undesirable chlorinous odor. Granular activated carbon (GAC) filtration is used to biologically oxidize ammonia during drinking water purification; however, little information is available regarding the abundance and diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) associated with GAC. In addition, their sources and fates in water purification process remain unknown. In this study, six GAC samples were collected from five full-scale drinking water purification plants in Tokyo during summer and winter, and the abundance and community structure of AOA and AOB associated with GAC were studied in these two seasons. In summer, archaeal and bacterial amoA genes on GACs were present at 3.7 × 10(5)-3.9 × 10(8) gene copies/g-dry and 4.5 × 10(6)-4.2 × 10(8) gene copies/g-dry, respectively. In winter, archaeal amoA genes remained at the same level, while bacterial amoA genes decreased significantly for all GACs. No differences were observed in the community diversity of AOA and AOB from summer to winter. Phylogenetic analysis revealed high AOA diversity in group I.1a and group I.1b in raw water. Terminal-restriction fragment length polymorphism analysis of processed water samples revealed that AOA diversity decreased dramatically to only two OTUs in group I.1a after ozonation, which were identical to those detected on GAC. It suggests that ozonation plays an important role in determining AOA diversity on GAC. Further study on the cell-specific activity of AOA and AOB is necessary to understand their contributions to in situ nitrification performance.

  2. Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria.

    Science.gov (United States)

    Lang, Longqi; Pocquet, Mathieu; Ni, Bing-Jie; Yuan, Zhiguo; Spérandio, Mathieu

    2017-02-01

    The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N 2 O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N 2 O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.

  3. Intensive Ammonia and Methane Oxidation in Organic Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas

    methane oxidizing bacteria (MOB) and are known to accumulate nitrite and nitrate, indicating the presence of ammonia oxidizers (AOB). We have surveyed six manure tanks with organic covers to investigate the prevalence of MOB and AOB and to link the potential activity with physical and chemical aspects...... characterized with respect to O2 availability by in situ profiling with electrochemical microsensors. Results show that oxygen penetration increased from few micrometers up to several centimetres with crust age. AOB and ammonium oxidation are ubiquitously present in well-developed manure crusts whereas MOB were...... also CH4 emission mitigation, an organic surface crust can be effective if populations of MOB and AOB are allowed to build up....

  4. Enhanced sulfamethoxazole degradation through ammonia oxidizing bacteria co-metabolism and fate of transformation products.

    Science.gov (United States)

    Kassotaki, Elissavet; Buttiglieri, Gianluigi; Ferrando-Climent, Laura; Rodriguez-Roda, Ignasi; Pijuan, Maite

    2016-05-01

    The occurrence of the widely-used antibiotic sulfamethoxazole (SFX) in wastewaters and surface waters has been reported in a large number of studies. However, the results obtained up-to-date have pointed out disparities in its removal. This manuscript explores the enhanced biodegradation potential of an enriched culture of Ammonia Oxidizing Bacteria (AOB) towards SFX. Several sets of batch tests were conducted to establish a link between SFX degradation and specific ammonia oxidation rate. The occurrence, degradation and generation of SFX and some of its transformation products (4-Nitro SFX, Desamino-SFX and N(4)-Acetyl-SFX) was also monitored. A clear link between the degradation of SFX and the nitrification rate was found, resulting in an increased SFX removal at higher specific ammonia oxidation rates. Moreover, experiments conducted under the presence of allylthiourea (ATU) did not present any removal of SFX, suggesting a connection between the AMO enzyme and SFX degradation. Long term experiments (up to 10 weeks) were also conducted adding two different concentrations (10 and 100 μg/L) of SFX in the influent of a partial nitrification sequencing batch reactor, resulting in up to 98% removal. Finally, the formation of transformation products during SFX degradation represented up to 32%, being 4-Nitro-SFX the most abundant. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Intermittent Aeration Suppresses Nitrite-Oxidizing Bacteria in Membrane-Aerated Biofilms: A Model-Based Explanation

    DEFF Research Database (Denmark)

    Ma, Yunjie; Domingo Felez, Carlos; Plósz, Benedek G.

    2017-01-01

    . On the basis of dissolved oxygen (DO), ammonium, nitrite, and nitrate profiles within the biofilm and in the bulk, a 1-dimensional nitrifying biofilm model was developed and calibrated. The model was utilized to explore the potential mechanisms of NOB suppression associated with intermittent aeration...... nitritation, strategies to suppress nitrite-oxidizing bacteria (NOB) are needed, which are ideally grounded on an understanding of underlying mechanisms. In this study, a nitrifying MABR was operated under intermittent aeration. During eight months of operation, AOB dominated, while NOB were suppressed...... during intermittent aeration was mostly explained by periodic inhibition caused by free ammonia due to periodic transient pH upshifts. Dissolved oxygen limitation did not govern NOB suppression. Different intermittent aeration strategies were then evaluated for nitritation success in intermittently...

  6. Anaerobic sulfide-oxidation in marine colorless sulfur-oxidizing bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    Colorless sulfur-oxidizing bacteria are ubiquitous in Indian waters and have the ability to oxidize sulfide under anaerobic conditions. These bacteria can not only mediate the sulfur cycle oxidatively but also the nitrogen cycle reductively without...

  7. Different Recovery Processes of Soil Ammonia Oxidizers from Flooding Disturbance.

    Science.gov (United States)

    Ye, Fei; Ma, Mao-Hua; Op den Camp, Huub J M; Chatzinotas, Antonis; Li, Lei; Lv, Ming-Quan; Wu, Sheng-Jun; Wang, Yu

    2018-04-11

    Understanding how microorganisms respond to environmental disturbance is one of the key focuses in microbial ecology. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are responsible for ammonia oxidation which is a crucial step in the nitrogen cycle. Although the physiology, distribution, and activity of AOA and AOB in soil have been extensively investigated, their recovery from a natural disturbance remains largely unknown. To assess the recovery capacities, including resistance and resilience, of AOA and AOB, soil samples were taken from a reservoir riparian zone which experienced periodically water flooding. The samples were classified into three groups (flooding, recovery, and control) for a high-throughput sequencing and quantitative PCR analysis. We used a relative quantitative index of both the resistance (RS) and resilience (RL) to assess the variation of gene abundance, alpha-diversity, and community composition. The AOA generally demonstrated a better recovery capability after the flooding disturbance compared to AOB. In particular, AOA were more resilient after the flooding disturbance. Taxa within the AOA and AOB showed different RS and RL values, with the most abundant taxa showing in general the highest RS indices. Soil NH 4 + and Fe 2+ /Fe 3+ were the main variables controlling the key taxa of AOA and AOB and probably influenced the resistance and resilience properties of AOA and AOB communities. The distinct mechanisms of AOA and AOB in maintaining community stability against the flooding disturbance might be linked to the different life-history strategies: the AOA community was more likely to represent r-strategists in contrast to the AOB community following a K-life strategy. Our results indicated that the AOA may play a vital role in ammonia oxidation in a fluctuating habitat and contribute to the stability of riparian ecosystem.

  8. Nitric oxide is an obligate bacterial nitrification intermediate produced by hydroxylamine oxidoreductase.

    Science.gov (United States)

    Caranto, Jonathan D; Lancaster, Kyle M

    2017-08-01

    Ammonia (NH 3 )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N 2 O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH 3 oxidation to nitrite (NO 2 - ) via a single obligate intermediate, hydroxylamine (NH 2 OH). Within this model, the multiheme enzyme hydroxylamine oxidoreductase (HAO) catalyzes the four-electron oxidation of NH 2 OH to NO 2 - We provide evidence that HAO oxidizes NH 2 OH by only three electrons to NO under both anaerobic and aerobic conditions. NO 2 - observed in HAO activity assays is a nonenzymatic product resulting from the oxidation of NO by O 2 under aerobic conditions. Our present study implies that aerobic NH 3 oxidation by AOB occurs via two obligate intermediates, NH 2 OH and NO, necessitating a mediator of the third enzymatic step.

  9. Shifts in the abundance and community structure of soil ammonia oxidizers in a wet sclerophyll forest under long-term prescribed burning.

    Science.gov (United States)

    Long, Xi-En; Chen, Chengrong; Xu, Zhihong; He, Ji-Zheng

    2014-02-01

    Fire shapes global biome distribution and promotes the terrestrial biogeochemical cycles. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play a vital role in the biogeochemical cycling of nitrogen (N). However, behaviors of AOB and AOA under long-term prescribed burning remain unclear. This study was to examine how fire affected the abundances and communities of soil AOB and AOA. A long-term repeated forest fire experiment with three burning treatments (never burnt, B0; biennially burnt, B2; and quadrennially burnt, B4) was used in this study. The abundances and community structure of soil AOB and AOA were determined using quantitative PCR, restriction fragment length polymorphism and clone library. More frequent fires (B2) increased the abundance of bacterium amoA gene, but tended to decrease archaeal amoA genes. Fire also modified the composition of AOA and AOB communities. Canonical correspondence analysis showed soil pH and dissolved organic C (DOC) strongly affected AOB genotypes, while nitrate-N and DOC shaped the AOA distribution. The increased abundance of bacterium amoA gene by fires may imply an important role of AOB in nitrification in fire-affected soils. The fire-induced shift in the community composition of AOB and AOA demonstrates that fire can disturb nutrient cycles. © 2013.

  10. Quantitative analysis of ammonia-oxidizing bacteria in a combined system of MBR and worm reactors treating synthetic wastewater.

    Science.gov (United States)

    Liu, Jia; Tian, Yu; Wang, Dezhen; Lu, Yaobin; Zhang, Jun; Zuo, Wei

    2014-12-01

    The Static Sequencing Batch Worm Reactor (SSBWR) followed by the MBR (S-MBR) is one of the advanced excess sludge treatments. In this paper, the control MBR (C-MBR) and the SSBWR-MBR were operated in parallel to study the changes of NH3-N removal and ammonia oxidizing bacteria (AOB). The results showed that the capacity of NH3-N removal of the S-MBR was improved by the worm reactors along with the operation. The S-MBR was favorable because it selected for the higher activity of the ammonia oxidization and better cells appearance of the sludge. The five species (Nitrosomonas, Betaproteobacteria, Clostridium, Dechloromonas and Bacteria) were found to be significantly correlate with the ammonia oxidization functions and performance of NH3-N removal in the C-MBR and S-MBR. The Nitrosomonas, Betaproteobacteria and Dechloromonas remained and eventually enriched in the S-MBR played a primary role in the NH3-N removal of the S-MBR. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Shifts in the pelagic ammonia-oxidizing microbial communities along the eutrophic estuary of Yong River in Ningbo City, China

    NARCIS (Netherlands)

    Zhang, Qiufang; Tang, Fang-Yuan; Zhou, Yang-Jing; Xu, Jirong; Chen, Heping; Wang, Ming-Juang; Laanbroek, H.J.

    2015-01-01

    BACKGROUND: Aerobic ammonia oxidation plays a key role in the nitrogen cycle, and the diversity of the responsible microorganisms is regulated by environmental factors. Abundance and composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated in the surface

  12. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils

    Science.gov (United States)

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-01-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3−-N g−1 dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in 13C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of 13CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the 13C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The 13C-NOB was overwhelmingly

  13. Manganese Oxidation by Bacteria: Biogeochemical Aspects

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; LokaBharathi, P.A.

    Manganese is an essential trace metal that is not as readily oxidizable like iron. Several bacterial groups posses the ability to oxidize Mn effectively competing with chemical oxidation. The oxides of Mn are the strongest of the oxidants, next...

  14. Diversity, abundance and niche differentiation of ammonia-oxidizing prokaryotes in mud deposits of the eastern China marginal seas

    Directory of Open Access Journals (Sweden)

    Shaolan eYu

    2016-02-01

    Full Text Available The eastern China marginal seas are prominent examples of river-dominated ocean margins, whose most characteristic feature is the existence of isolated mud patches on sandy sediments. Ammonia-oxidizing prokaryotes play a crucial role in the nitrogen cycles of many marine environments, including marginal seas. However, few studies have attempted to address the distribution patterns of ammonia-oxidizing prokaryotes in mud deposits of these seas. The horizontal and vertical community composition and abundance of ammonia-oxidizing archaea (AOA and bacteria (AOB were investigated in mud deposits of the South Yellow Sea (SYS and the East China Sea (ECS by using amoA clone libraries and quantitative PCR. The diversity of AOB was comparable or higher in the mud zone of SYS and lower in ECS when compared with AOA. Vertically, surface sediments had generally higher diversity of AOA and AOB than middle and bottom layers. Diversity of AOA and AOB showed significant correlation with latitude. Nitrosopumilus and Nitrosospira lineages dominated AOA and AOB communities, respectively. Both AOA and AOB assemblages exhibited greater variations across different sites than those among various depths at one site. The abundance of bacterial amoA was generally higher than that of archaeal amoA, and both of them decreased with depth. Niche differentiation, which was affected by dissolved oxygen, salinity, ammonia and silicate (SiO32-, was observed between AOA and AOB and among different groups of them. The spatial distribution of AOA and AOB was significantly correlated with δ15NTN and SiO32-, and nitrate and δ13C, respectively. Both archaeal and bacterial amoA abundance correlated strongly with SiO32-. This study improves our understanding of spatial distribution of AOA and AOB in ecosystems featuring oceanic mud deposits.

  15. Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

    Science.gov (United States)

    Yao, Huaiying; Huang, Sha; Qiu, Qiongfen; Li, Yaying; Wu, Lianghuan; Mi, Wenhai; Dai, Feng

    2016-08-01

    Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community.

  16. Diversity, Abundance, and Niche Differentiation of Ammonia-Oxidizing Prokaryotes in Mud Deposits of the Eastern China Marginal Seas.

    Science.gov (United States)

    Yu, Shaolan; Yao, Peng; Liu, Jiwen; Zhao, Bin; Zhang, Guiling; Zhao, Meixun; Yu, Zhigang; Zhang, Xiao-Hua

    2016-01-01

    The eastern China marginal seas (ECMS) are prominent examples of river-dominated ocean margins, whose most characteristic feature is the existence of isolated mud patches on sandy sediments. Ammonia-oxidizing prokaryotes play a crucial role in the nitrogen cycles of many marine environments, including marginal seas. However, few studies have attempted to address the distribution patterns of ammonia-oxidizing prokaryotes in mud deposits of these seas. The horizontal and vertical community composition and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were investigated in mud deposits of the South Yellow Sea (SYS) and the East China Sea (ECS) by using amoA clone libraries and quantitative PCR. The diversity of AOB was comparable or higher in the mud zone of SYS and lower in ECS when compared with AOA. Vertically, surface sediments had generally higher diversity of AOA and AOB than middle and bottom layers. Diversity of AOA and AOB showed significant correlation with latitude. Nitrosopumilus and Nitrosospira lineages dominated AOA and AOB communities, respectively. Both AOA and AOB assemblages exhibited greater variations across different sites than those among various depths at one site. The abundance of bacterial amoA was generally higher than that of archaeal amoA, and both of them decreased with depth. Niche differentiation, which was affected by dissolved oxygen, salinity, ammonia, and silicate (SiO[Formula: see text]), was observed between AOA and AOB and among different groups of them. The spatial distribution of AOA and AOB was significantly correlated with δ(15)NTN and SiO[Formula: see text], and nitrate and δ(13)C, respectively. Both archaeal and bacterial amoA abundance correlated strongly with SiO[Formula: see text]. This study improves our understanding of spatial distribution of AOA and AOB in ecosystems featuring oceanic mud deposits.

  17. Distribution and abundance of archaeal and bacterial ammonia oxidizers in the sediments of the Dongjiang River, a drinking water supply for Hong Kong.

    Science.gov (United States)

    Sun, Wei; Xia, Chunyu; Xu, Meiying; Guo, Jun; Wang, Aijie; Sun, Guoping

    2013-01-01

    Ammonia-oxidizing archaea (AOA) and bacteria (AOB) play important roles in nitrification. However, limited information about the characteristics of AOA and AOB in the river ecosystem is available. The distribution and abundance of AOA and AOB in the sediments of the Dongjiang River, a drinking water source for Hong Kong, were investigated by clone library analysis and quantitative real-time PCR. Phylogenetic analysis showed that Group 1.1b- and Group 1.1b-associated sequences of AOA predominated in sediments with comparatively high carbon and nitrogen contents (e.g. total carbon (TC) >13 g kg(-1) sediment, NH4(+)-N >144 mg kg(-1) sediment), while Group 1.1a- and Group 1.1a-associated sequences were dominant in sediments with opposite conditions (e.g. TC <4 g kg(-1) sediment, NH4(+)-N <93 mg kg(-1) sediment). Although Nitrosomonas- and Nitrosospira-related sequences of AOB were detected in the sediments, nearly 70% of the sequences fell into the Nitrosomonas-like B cluster, suggesting similar sediment AOB communities along the river. Higher abundance of AOB than AOA was observed in almost all of the sediments in the Dongjiang River, while significant correlations were only detected between the distribution of AOA and the sediment pH and TC, which suggested that AOA responded more sensitively than AOB to variations of environmental factors. These results extend our knowledge about the environmental responses of ammonia oxidizers in the river ecosystem.

  18. Physiology of alkaliphilic sulfur-oxidizing bacteria from soda lakes

    NARCIS (Netherlands)

    Banciu, H.L.

    2004-01-01

    The inorganic sulfur oxidation by obligate haloalkaliphilic chemolithoautotrophs was only recently discovered and investigated. These autotrophic sulfur oxidizing bacteria (SOB), capable of oxidation of inorganic sulfur compounds at moderate to high salt concentration and at high pH, can be divided

  19. Tracking and quantification of nitrifying bacteria in biofilm and mixed liquor of a partial nitrification MBBR pilot plant using fluorescence in situ hybridization

    International Nuclear Information System (INIS)

    Abzazou, Tarik; Araujo, Rosa M.; Auset, María; Salvadó, Humbert

    2016-01-01

    A moving bead biofilm reactor (MBBR) pilot plant was implemented as a partial nitrification process for pre-treatment of ammonium-rich liquors (676 ± 195 mg L"−"1), and studied for 479 days under variations in hydraulic retention time. The main purpose of this work, was the study of dynamics abundance of total bacteria and single-cells nitrifying bacteria belonging to ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in biofilms and mixed liquor of the plant. The microbial monitoring was successfully achieved using fluorescence in situ hybridization combined with flocs disaggregation protocol as a useful microbial monitoring tool. A partial nitrification process with a N-NH_4"+ removal rate of about 38.6 ± 14.8% was successfully achieved at 211 days after start-up, with a clear dominance of AOB, which accounted for 11.3 ± 17.0% of total bacterial cells compared with only 2.1 ± 4.0% of NOB. The effluent obtained was subsequently supplied to an Anammox reactor for complete ammonium treatment. - Highlights: • Partial nitrification process in a MBBR fed with ammonium-rich liquor was achieved. • The operational key parameters were the HRT and temperature. • DAPI and FISH were useful to monitoring microbial composition of MBBR pilot plant. • The AOB were the dominant nitrifying bacteria, presenting 11.3% of total bacteria. • A significant correlation (R = 0.68) between AOB and ammonia removal was found.

  20. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating

    NARCIS (Netherlands)

    Daebeler, A.; Abell, G.C.J.; Bodelier, P.L.E.; Bodrossy, L.; Frampton, D.M.; Hefting, M.M.; Laanbroek, H.J.

    2012-01-01

    The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively) to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of

  1. Interactions among sulfide-oxidizing bacteria

    Science.gov (United States)

    Poplawski, R.

    1985-01-01

    The responses of different phototrophic bacteria in a competitive experimental system are studied, one in which primary factors such as H2S or light limited photometabolism. Two different types of bacteria shared one limited source of sulfide under specific conditions of light. The selection of a purple and a green sulfur bacteria and the cyanobacterium was based on their physiological similarity and also on the fact that they occur together in microbial mats. They all share anoxygenic photosynthesis, and are thus probably part of an evolutionary continuum of phototrophic organisms that runs from, strictly anaerobic physiology to the ability of some cyanobacteria to shift between anoxygenic bacterial style photosynthesis and the oxygenic kind typical of eukaryotes.

  2. Community structure analysis of soil ammonia oxidizers during vegetation restoration in southwest China.

    Science.gov (United States)

    Liang, Yueming; He, Xunyang; Liang, Shichu; Zhang, Wei; Chen, Xiangbi; Feng, Shuzheng; Su, Yirong

    2014-03-01

    Soil ammonia oxidizers play a critical role in nitrogen cycling and ecological restoration. The composition and structure of soil ammonia oxidizers and their impacting factors were studied in four typical ecosystem soils, tussock (T), shrub (S), secondary forest (SF), and primary forest (PF), during vegetation restoration in the Karst region of Southwest China. The composition and structure of the ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities were characterized by sequencing the amoA and arch-amoA genes, respectively. The diversity of soil ammonia oxidizers (except in S) and plant Shannon diversity index gradually increased with vegetation restoration, and the ammonia oxidizer communities differed significantly (p soils. AOB Nitrosospira cluster 3b only appeared in PF and SF soils, while Nitrosospira cluster 3a species were found in all soils. Changes in AOB paralleled the changes in soil ammonium content that occurred with vegetation restoration. Redundancy analysis showed that the distribution of dominant AOB species was linked to pH, soil urease activity, and soil C/N ratio, whereas the distribution of dominant AOA species was mainly influenced by litter nitrogen content and C/N ratio. These results suggested that the composition and structure of the AOB community were more sensitive to changes in vegetation and soil ammonium content, and may be an important indicator of nitrogen availability in Karst ecosystem soils. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

    DEFF Research Database (Denmark)

    Miot, Jennyfer; Benzerara, Karim; Morin, Guillaume

    2009-01-01

    Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent ......Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate...... precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria...... and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All...

  4. On bacteria oxidizing enlargement scale test for uranium in-situ leaching at. 381 mine

    International Nuclear Information System (INIS)

    Hu Kaiguang; Wang Qingliang; Liu Yingjiu; Shi Wenge; Hu Shihe; Hu Yincai; Fang Qiu

    1999-01-01

    The results of enlarged scale test of bacteria as oxidizer for uranium in-situ leaching at No 381 mine showed that redox potential of the oxidized absorbed tailing water by bacteria is more than 510 mV, without any effects on after treatments by using bacteria as oxidizer and reduce oxidizer costs 70% compared with H 2 O 2 as oxidizer

  5. Physiology and genetics of sulfur-oxidizing bacteria.

    Science.gov (United States)

    Friedrich, C G

    1998-01-01

    Reduced inorganic sulfur compounds are oxidized by members of the domains Archaea and Bacteria. These compounds are used as electron donors for anaerobic phototrophic and aerobic chemotrophic growth, and are mostly oxidized to sulfate. Different enzymes mediate the conversion of various reduced sulfur compounds. Their physiological function in sulfur oxidation is considered (i) mostly from the biochemical characterization of the enzymatic reaction, (ii) rarely from the regulation of their formation, and (iii) only in a few cases from the mutational gene inactivation and characterization of the resulting mutant phenotype. In this review the sulfur-metabolizing reactions of selected phototrophic and of chemotrophic prokaryotes are discussed. These comprise an archaeon, a cyanobacterium, green sulfur bacteria, and selected phototrophic and chemotrophic proteobacteria. The genetic systems are summarized which are presently available for these organisms, and which can be used to study the molecular basis of their dissimilatory sulfur metabolism. Two groups of thiobacteria can be distinguished: those able to grow with tetrathionate and other reduced sulfur compounds, and those unable to do so. This distinction can be made irrespective of their phototrophic or chemotrophic metabolism, neutrophilic or acidophilic nature, and may indicate a mechanism different from that of thiosulfate oxidation. However, the core enzyme for tetrathionate oxidation has not been identified so far. Several phototrophic bacteria utilize hydrogen sulfide, which is considered to be oxidized by flavocytochrome c owing to its in vitro activity. However, the function of flavocytochrome c in vivo may be different, because it is missing in other hydrogen sulfide-oxidizing bacteria, but is present in most thiosulfate-oxidizing bacteria. A possible function of flavocytochrome c is discussed based on biophysical studies, and the identification of a flavocytochrome in the operon encoding enzymes involved

  6. Nitrosospira sp. Govern Nitrous Oxide Emissions in a Tropical Soil Amended With Residues of Bioenergy Crop

    Directory of Open Access Journals (Sweden)

    Késia S. Lourenço

    2018-04-01

    Full Text Available Organic vinasse, a residue produced during bioethanol production, increases nitrous oxide (N2O emissions when applied with inorganic nitrogen (N fertilizer in soil. The present study investigated the role of the ammonia-oxidizing bacteria (AOB community on the N2O emissions in soils amended with organic vinasse (CV: concentrated and V: non-concentrated plus inorganic N fertilizer. Soil samples and N2O emissions were evaluated at 11, 19, and 45 days after fertilizer application, and the bacterial and archaea gene (amoA encoding the ammonia monooxygenase enzyme, bacterial denitrifier (nirK, nirS, and nosZ genes and total bacteria were quantified by real time PCR. We also employed a deep amoA amplicon sequencing approach to evaluate the effect of treatment on the community structure and diversity of the soil AOB community. Both vinasse types applied with inorganic N application increased the total N2O emissions and the abundance of AOB. Nitrosospira sp. was the dominant AOB in the soil and was correlated with N2O emissions. However, the diversity and the community structure of AOB did not change with vinasse and inorganic N fertilizer amendment. The results highlight the importance of residues and fertilizer management in sustainable agriculture and can be used as a reference and an input tool to determine good management practices for organic fertilization.

  7. Cultivation, detection, and ecophysiology of anaerobic ammonium-oxidizing bacteria.

    Science.gov (United States)

    Kartal, Boran; Geerts, Wim; Jetten, Mike S M

    2011-01-01

    Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite under anoxic conditions. The anammox process is currently used to remove ammonium from wastewater and contributes significantly to the loss of fixed nitrogen from the oceans. In this chapter, we focus on the ecophysiology of anammox bacteria and describe new methodologies to grow these microorganisms. Now, it is possible to enrich anammox bacteria up to 95% with a membrane bioreactor that removes forces of selection for fast settling aggregates and facilitates the growth of planktonic cells. The biomass from this system has a high anaerobic ammonium oxidation rate (50 fmol NH(4)(+) · cell(-1) day(-1)) and is suitable for many ecophysiological and molecular experiments. A high throughput Percoll density gradient centrifugation protocol may be applied on this biomass for further enrichment (>99.5%) of anammox bacteria. Furthermore, we provide an up-to-date list of commonly used primers and introduce protocols for quantification and detection of functional genes of anammox bacteria in their natural environment. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Ammonia-oxidizing bacteria: A model for molecular microbial ecology

    NARCIS (Netherlands)

    Kowalchuk, G.A.; Stephen, J.R.

    2001-01-01

    The eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important

  9. Cell biology of anaerobic ammonium-oxidizing bacteria

    NARCIS (Netherlands)

    Niftrik, L.A.M.P. van

    2008-01-01

    Anammox bacteria perform anaerobic ammonium oxidation to dinitrogen gas and belong to the phylum Planctomycetes. Whereas most Prokaryotes consist of one compartment, the cytoplasm bounded by the cytoplasmic membrane and cell wall, the species within this phylum are compartmentalized by intracellular

  10. Evaluation of autotrophic growth of ammonia-oxidizers associated with granular activated carbon used for drinking water purification by DNA-stable isotope probing.

    Science.gov (United States)

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki

    2013-12-01

    Nitrification is an important biological function of granular activated carbon (GAC) used in advanced drinking water purification processes. Newly discovered ammonia-oxidizing archaea (AOA) have challenged the traditional understanding of ammonia oxidation, which considered ammonia-oxidizing bacteria (AOB) as the sole ammonia-oxidizers. Previous studies demonstrated the predominance of AOA on GAC, but the contributions of AOA and AOB to ammonia oxidation remain unclear. In the present study, DNA-stable isotope probing (DNA-SIP) was used to investigate the autotrophic growth of AOA and AOB associated with GAC at two different ammonium concentrations (0.14 mg N/L and 1.4 mg N/L). GAC samples collected from three full-scale drinking water purification plants in Tokyo, Japan, had different abundance of AOA and AOB. These samples were fed continuously with ammonium and (13)C-bicarbonate for 14 days. The DNA-SIP analysis demonstrated that only AOA assimilated (13)C-bicarbonate at low ammonium concentration, whereas AOA and AOB exhibited autotrophic growth at high ammonium concentration. This indicates that a lower ammonium concentration is preferable for AOA growth. Since AOA could not grow without ammonium, their autotrophic growth was coupled with ammonia oxidation. Overall, our results point towards an important role of AOA in nitrification in GAC filters treating low concentration of ammonium. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    Substrates that contain high ammonia levels can cause inhibition on anaerobic digestion process and unstable biogas production. The aim of the current study was to assess the effects of different ammonia levels on pure strains of (syntrophic acetate oxidizing) SAO bacteria and hydrogenotrophic...... methanogens. Two pure strains of hydrogenotrophic methanogens (i.e: Methanoculleus bourgensis and Methanoculleus thermophiles) and two pure strains of SAO bacteria (i.e: Tepidanaerobacter acetatoxydans and Thermacetogenium phaeum) were inoculated under four different ammonia (0.26, 3, 5 and 7g NH4+-N......, the total incubation periods of hydrogenotrophic methanogens were significantly shorter compared to the SAO bacteria incubation periods. Thus, it seems that hydrogenotrophic methanogens could be equally, if not more, tolerant to high ammonia levels compared to SAO bacteria....

  12. Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System

    OpenAIRE

    Regan, John M.; Harrington, Gregory W.; Noguera, Daniel R.

    2002-01-01

    Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammon...

  13. Evaluation of different nitrous oxide production models with four continuous long-term wastewater treatment process data series.

    Science.gov (United States)

    Spérandio, Mathieu; Pocquet, Mathieu; Guo, Lisha; Ni, Bing-Jie; Vanrolleghem, Peter A; Yuan, Zhiguo

    2016-03-01

    Five activated sludge models describing N2O production by ammonium oxidising bacteria (AOB) were compared to four different long-term process data sets. Each model considers one of the two known N2O production pathways by AOB, namely the AOB denitrification pathway and the hydroxylamine oxidation pathway, with specific kinetic expressions. Satisfactory calibration could be obtained in most cases, but none of the models was able to describe all the N2O data obtained in the different systems with a similar parameter set. Variability of the parameters can be related to difficulties related to undescribed local concentration heterogeneities, physiological adaptation of micro-organisms, a microbial population switch, or regulation between multiple AOB pathways. This variability could be due to a dependence of the N2O production pathways on the nitrite (or free nitrous acid-FNA) concentrations and other operational conditions in different systems. This work gives an overview of the potentialities and limits of single AOB pathway models. Indicating in which condition each single pathway model is likely to explain the experimental observations, this work will also facilitate future work on models in which the two main N2O pathways active in AOB are represented together.

  14. Fact and Fiction of Nitrous Oxide Production By Nitrification

    Science.gov (United States)

    Stein, L. Y.; Kozlowski, J.; Stieglmeier, M.; Klotz, M. G.; Schleper, C.

    2014-12-01

    An accepted dogma in nitrification research is that ammonia-oxidizing bacteria (AOB) produce a modicum of nitrous oxide (N2O) during nitritation via incomplete oxidation of hydroxylamine, and substantially more at low oxygen concentrations via nitrifier denitrification.The nitrifier denitrification pathway involves the reduction of nitrite to N2O via nitric oxide and was thought to require activities of a copper-containing nitrite reductase (NirK) and nitric oxide reductase (NorB); inventory encoded in most, but not all AOB genome sequences. The discovery of nirK genes in ammonia-oxidizing Thaumarchaeota (AOA) resulted in a slew of publications stating that AOA must also perform nitrifier denitrification and, due to their high abundance, must control the majority of nitrification-linked N2O emissions. Prior to a publication by Stieglmeier et al. (2014), which definitively showed a lack of nitrifier denitrification by two axenic AOA cultures, other researchers relied on enrichment cultures, negative data, and heavy inferencing without direct demonstration of either a functional pathway or involvement of specific genes or enzymes. AOA genomes lack recognizable nitric oxide reductases and thermophilic AOA also lack nirK genes. Physiological and microrespirometry experiments with axenic AOB and AOA cultures allowed us to demonstrate that: 1) AOB produce N2O via nitrifier denitrification even though some lack annotated nirK and/or norB genes; 2) nitrifier denitrification by AOB is reliant on nitric oxide but ammonia oxidation is not; 3) ammonia oxidation by AOA is reliant on production of nitric oxide; 4) AOA are incapable of generating N2O via nitrifier denitrification; 5) N2O production by AOA is from chemical interactions between NO and media components, most likely not by enzyme activity. Our results reveal operation of different N oxide transformation pathways in AOB and AOA governed by different environmental controls and involving different mechanisms of N2O

  15. Anaerobic Ammonium-Oxidizing Bacteria in Cow Manure Composting.

    Science.gov (United States)

    Wang, Tingting; Cheng, Lijun; Zhang, Wenhao; Xu, Xiuhong; Meng, Qingxin; Sun, Xuewei; Liu, Huajing; Li, Hongtao; Sun, Yu

    2017-07-28

    Composting is widely used to transform waste into valuable agricultural organic fertilizer. Anaerobic ammonium-oxidizing (anammox) bacteria play an important role in the global nitrogen cycle, but their role in composting remains poorly understood. In the present study, the community structure, diversity, and abundance of anammox bacteria were analyzed using cloning and sequencing methods by targeting the 16S rRNA gene and the hydrazine oxidase gene ( hzo ) in samples isolated from compost produced from cow manure and rice straw. A total of 25 operational taxonomic units were classified based on 16S rRNA gene clone libraries, and 14 operational taxonomic units were classified based on hzo gene clone libraries. The phylogenetic tree analysis of the 16S rRNA gene and deduced HZO protein sequences from the corresponding encoding genes indicated that the majority of the obtained clones were related to the known anammox bacteria Candidatus "Brocadia," Candidatus "Kuenenia," and Candidatus "Scalindua." The abundances of anammox bacteria were determined by quantitative PCR, and between 2.13 × 10 5 and 1.15 × 10 6 16S rRNA gene copies per gram of compost were found. This study provides the first demonstration of the existence of anammox bacteria with limited diversity in cow manure composting.

  16. Anaerobic Ammonium-Oxidizing Bacteria: Unique Microorganisms with Exceptional Properties

    Science.gov (United States)

    Jetten, Mike S. M.

    2012-01-01

    Summary: Anaerobic ammonium-oxidizing (anammox) bacteria defy many microbiological concepts and share numerous properties with both eukaryotes and archaea. Among their most intriguing characteristics are their compartmentalized cell plan and archaeon-like cell wall. Here we review our current knowledge about anammox cell biology. The anammox cell is divided into three separate compartments by bilayer membranes. The anammox cell consists of (from outside to inside) the cell wall, paryphoplasm, riboplasm, and anammoxosome. Not much is known about the composition or function of both the anammox cell wall and the paryphoplasm compartment. The cell wall is proposed to be proteinaceous and to lack both peptidoglycan and an outer membrane typical of Gram-negative bacteria. The function of the paryphoplasm is unknown, but it contains the cell division ring. The riboplasm resembles the standard cytoplasmic compartment of other bacteria; it contains ribosomes and the nucleoid. The anammoxosome occupies most of the cell volume and is a so-called “prokaryotic organelle” analogous to the eukaryotic mitochondrion. This is the site where the anammox reaction takes place, coupled over the curved anammoxosome membrane, possibly giving rise to a proton motive force and subsequent ATP synthesis. With these unique properties, anammox bacteria are food for thought concerning the early evolution of the domains Bacteria, Archaea, and Eukarya. PMID:22933561

  17. Niche specificity of ammonia-oxidizing archaeal and bacterial communities in a freshwater wetland receiving municipal wastewater in Daqing, Northeast China.

    Science.gov (United States)

    Lee, Kwok-Ho; Wang, Yong-Feng; Li, Hui; Gu, Ji-Dong

    2014-12-01

    Ecophysiological differences between ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) enable them to adapt to different niches in complex freshwater wetland ecosystems. The community characters of AOA and AOB in the different niches in a freshwater wetland receiving municipal wastewater, as well as the physicochemical parameters of sediment/soil samples, were investigated in this study. AOA community structures varied and separated from each other among four different niches. Wetland vegetation including aquatic macrophytes and terrestrial plants affected the AOA community composition but less for AOB, whereas sediment depths might contribute to the AOB community shift. The diversity of AOA communities was higher than that of AOB across all four niches. Archaeal and bacterial amoA genes (encoding for the alpha-subunit of ammonia monooxygenases) were most diverse in the dry-land niche, indicating O2 availability might favor ammonia oxidation. The majority of AOA amoA sequences belonged to the Soil/sediment Cluster B in the freshwater wetland ecosystems, while the dominant AOB amoA sequences were affiliated with Nitrosospira-like cluster. In the Nitrosospira-like cluster, AOB amoA gene sequences affiliated with the uncultured ammonia-oxidizing beta-proteobacteria constituted the largest portion (99%). Moreover, independent methods for phylogenetic tree analysis supported high parsimony bootstrap values. As a consequence, it is proposed that Nitrosospira-like amoA gene sequences recovered in this study represent a potentially novel cluster, grouping with the sequences from Gulf of Mexico deposited in the public databases.

  18. Environmental factors determining ammonia-oxidizing organism distribution and diversity in marine environments.

    Science.gov (United States)

    Bouskill, Nicholas J; Eveillard, Damien; Chien, Diana; Jayakumar, Amal; Ward, Bess B

    2012-03-01

    Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play a vital role in bridging the input of fixed nitrogen, through N-fixation and remineralization, to its loss by denitrification and anammox. Yet the major environmental factors determining AOB and AOA population dynamics are little understood, despite both groups having a wide environmental distribution. This study examined the relative abundance of both groups of ammonia-oxidizing organisms (AOO) and the diversity of AOA across large-scale gradients in temperature, salinity and substrate concentration and dissolved oxygen. The relative abundance of AOB and AOA varied across environments, with AOB dominating in the freshwater region of the Chesapeake Bay and AOA more abundant in the water column of the coastal and open ocean. The highest abundance of the AOA amoA gene was recorded in the oxygen minimum zones (OMZs) of the Eastern Tropical South Pacific (ETSP) and the Arabian Sea (AS). The ratio of AOA : AOB varied from 0.7 in the Chesapeake Bay to 1600 in the Sargasso Sea. Relative abundance of both groups strongly correlated with ammonium concentrations. AOA diversity, as determined by phylogenetic analysis of clone library sequences and archetype analysis from a functional gene DNA microarray, detected broad phylogenetic differences across the study sites. However, phylogenetic diversity within physicochemically congruent stations was more similar than would be expected by chance. This suggests that the prevailing geochemistry, rather than localized dispersal, is the major driving factor determining OTU distribution. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  19. Propionate oxidation by and methanol inhibition of anaerobic ammonium-oxidizing bacteria.

    Science.gov (United States)

    Güven, Didem; Dapena, Ana; Kartal, Boran; Schmid, Markus C; Maas, Bart; van de Pas-Schoonen, Katinka; Sozen, Seval; Mendez, Ramon; Op den Camp, Huub J M; Jetten, Mike S M; Strous, Marc; Schmidt, Ingo

    2005-02-01

    Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min(-1) mg of protein(-1)) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO(2), with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed.

  20. Role of copper oxides in contact killing of bacteria.

    Science.gov (United States)

    Hans, Michael; Erbe, Andreas; Mathews, Salima; Chen, Ying; Solioz, Marc; Mücklich, Frank

    2013-12-31

    The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.

  1. Oxidation of inorganic compounds of sulphur by various sulphur bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Parker, C D; Prisk, J

    1953-01-01

    Cultures of thiobacillus thiooxidans, Th. thioparus, Th. novellus, Thiobacillus b strains t and kand Th. concretivorus, Thiobacillus x and the m strains, organisms isolated from concrete were examined to elucidate the mode of oxidation and to establish the identity of the organisms recently isolated from corroded concrete. Thiosulphate was oxidized by all these bacteria. Th. thiooxidans, Th. concretivorus and Thiobacillus x first converted it to tetrathionate and sulphate and then oxidized the tetrathionate to sulphate and free sulphuric acid. Thiobaciullus x differed from the other two in that, owing to a lesser acid tolerance, some tetrathionate was found in the final products of oxidation. Th. Thioparus converted thiosulphate to sulphate and sulphur, followed by partial oxidation of the sulphur to sulphuric acid. Th. novellus produced sulphate and sulphuric acid. Thiobacillus b, the t and k strains and the m strains formed sulphate and tetrathionate with temporary increase in pH value; only Thiobacillus x oxidized tetrationate, yielding sulphate and sulphuric acid. Elementary sulphur was oxidized by Th. thiooxidans, th. Concretivorus, thiobacillus x and Th. thioparus; the rates of oxidation decreased in that order, and the only product was sulphuric acid. Hydrogen sulphide was oxidized only at low concentrations and only by th. Concretivorus and Thiobacillus x; sulphuric acid was the end-product, and elementary sulphur may have been an intermediate. Thiobacillus x differed from Th. thiooxidans in pH range for growth and from Th. thioparus in its method of oxidation of thiosulphate, tetrathionate and H/sub 2/S. The m strains were similar to thiobacillus b and the t and k strains of trautwein.

  2. The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria.

    Science.gov (United States)

    Zhang, Zhennan; Yin, Naiyi; Du, Huili; Cai, Xiaolin; Cui, Yanshan

    2016-05-01

    Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10(9) colony-forming units (CFUs)·ml(-1)) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L(-1)) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 μmol h(-1)) was much slower than the rate in the aqueous phase (96.2 μmol h(-1)). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Oxygen Distribution and Potential Ammonia Oxidation in Floating, Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas

    2010-01-01

    Floating, organic crusts on liquid manure, stored as a result of animal production, reduce emission of ammonia (NH3) and other volatile compounds during storage. The occurrence of NO2- and NO3- in the crusts indicate the presence of actively metabolizing NH3 oxidizing bacteria (AOB) which may...... be partly responsible for this mitigation effect. Six manure tanks with organic covers (straw and natural) were surveyed to investigate the prevalence and potential activity of AOB and its dependence on the O2 availability in the crust matrix as studied by electrochemical profiling. Oxygen penetration...... microorganisms, including AOB. The microbial activity may thus contribute to a considerable reduction of ammonia emissions from slurry tanks with well-developed crusts....

  4. Community Composition and Transcriptional Activity of Ammonia-Oxidizing Prokaryotes of Seagrass Thalassia hemprichii in Coral Reef Ecosystems

    Directory of Open Access Journals (Sweden)

    Juan Ling

    2018-01-01

    Full Text Available Seagrasses in coral reef ecosystems play important ecological roles by enhancing coral reef resilience under ocean acidification. However, seagrass primary productivity is typically constrained by limited nitrogen availability. Ammonia oxidation is an important process conducted by ammonia-oxidizing archaea (AOA and bacteria (AOB, yet little information is available concerning the community structure and potential activity of seagrass AOA and AOB. Therefore, this study investigated the variations in the abundance, diversity and transcriptional activity of AOA and AOB at the DNA and transcript level from four sample types: the leaf, root, rhizosphere sediment and bulk sediment of seagrass Thalassia hemprichii in three coral reef ecosystems. DNA and complementary DNA (cDNA were used to prepare clone libraries and DNA and cDNA quantitative PCR (qPCR assays, targeting the ammonia monooxygenase-subunit (amoA genes as biomarkers. Our results indicated that the closest relatives of the obtained archaeal and bacterial amoA gene sequences recovered from DNA and cDNA libraries mainly originated from the marine environment. Moreover, all the obtained AOB sequences belong to the Nitrosomonadales cluster. Nearly all the AOA communities exhibited higher diversity than the AOB communities at the DNA level, but the qPCR data demonstrated that the abundances of AOB communities were higher than that of AOA communities based on both DNA and RNA transcripts. Collectively, most of the samples shared greater community composition similarity with samples from the same location rather than sample type. Furthermore, the abundance of archaeal amoA gene in rhizosphere sediments showed significant relationships with the ammonium concentration of sediments and the nitrogen content of plant tissue (leaf and root at the DNA level (P < 0.05. Conversely, no such relationships were found for the AOB communities. This work provides new insight into the nitrogen cycle

  5. Bacteria in non-woven textile filters for domestic wastewater treatment.

    Science.gov (United States)

    Spychała, Marcin; Starzyk, Justyna

    2015-01-01

    The objective of this study was preliminary identification of heterotrophic and ammonia oxidizing bacteria (AOB) cell concentration in the cross-sectional profile of geotextile filters for wastewater treatment. Filters of thicknesses 3.6 and 7.2 mm, made of non-woven textile TS20, were supplied with septic tank effluent and intermittently dosed and filtered under hydrostatic pressure. The cumulative loads of chemical oxygen demand (COD) and total solids were about 1.36 and 1.06 kg/cm2, respectively. The filters under analysis reached a relatively high removal efficiency for organic pollution 70-90% for biochemical oxygen demand (BOD5) and 60-85% for COD. The ammonia nitrogen removal efficiency level proved to be unstable (15-55%). Biomass samples for dry mass identification were taken from two regions: continuously flooded with wastewater and intermittently flooded with wastewater. The culturable heterotrophic bacteria were determined as colony-forming units (CFUs) on microbiological-selective media by means of the plate method. AOB and nitrite oxidizing bacteria (NOB) were examined using the FISH technique. A relatively wide range of heterotrophic bacteria was observed from 7.4×10(5)/cm2 to 3.8×10(6)/cm2 in geotextile layers. The highest concentration of heterotrophic bacteria (3.8×10(6)/cm2) was observed in the first layer of the textile filter. AOB were identified occasionally--about 8-15% of all bacteria colonizing the last filter layer, but occasionally much higher concentrations and ammonia nitrogen efficiency were achieved. Bacteria oxidizing nitrite to nitrate were not observed. The relation of total and organic fraction of biomass to culturable heterotrophic bacteria was also found.

  6. Ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system.

    Science.gov (United States)

    Regan, John M; Harrington, Gregory W; Noguera, Daniel R

    2002-01-01

    Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammonia oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay.

  7. Tracking and quantification of nitrifying bacteria in biofilm and mixed liquor of a partial nitrification MBBR pilot plant using fluorescence in situ hybridization

    Energy Technology Data Exchange (ETDEWEB)

    Abzazou, Tarik, E-mail: tabzazou@ub.edu [Department of Microbiology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona (Spain); Araujo, Rosa M., E-mail: raraujo@ub.edu [Department of Microbiology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona (Spain); Auset, María, E-mail: maria.auset.vallejo@acciona.com [ACCIONA AGUA, S.A., Av de les Garrigues 22, El Prat de Llobregat, 08820 Barcelona (Spain); Salvadó, Humbert, E-mail: hsalvado@ub.edu [Department of Animal Biology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona (Spain)

    2016-01-15

    A moving bead biofilm reactor (MBBR) pilot plant was implemented as a partial nitrification process for pre-treatment of ammonium-rich liquors (676 ± 195 mg L{sup −1}), and studied for 479 days under variations in hydraulic retention time. The main purpose of this work, was the study of dynamics abundance of total bacteria and single-cells nitrifying bacteria belonging to ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in biofilms and mixed liquor of the plant. The microbial monitoring was successfully achieved using fluorescence in situ hybridization combined with flocs disaggregation protocol as a useful microbial monitoring tool. A partial nitrification process with a N-NH{sub 4}{sup +} removal rate of about 38.6 ± 14.8% was successfully achieved at 211 days after start-up, with a clear dominance of AOB, which accounted for 11.3 ± 17.0% of total bacterial cells compared with only 2.1 ± 4.0% of NOB. The effluent obtained was subsequently supplied to an Anammox reactor for complete ammonium treatment. - Highlights: • Partial nitrification process in a MBBR fed with ammonium-rich liquor was achieved. • The operational key parameters were the HRT and temperature. • DAPI and FISH were useful to monitoring microbial composition of MBBR pilot plant. • The AOB were the dominant nitrifying bacteria, presenting 11.3% of total bacteria. • A significant correlation (R = 0.68) between AOB and ammonia removal was found.

  8. Wastewater treatment plant effluents change abundance and composition of ammonia-oxidizing microorganisms in mediterranean urban stream biofilms.

    Science.gov (United States)

    Merbt, Stephanie N; Auguet, Jean-Christophe; Blesa, Alba; Martí, Eugènia; Casamayor, Emilio O

    2015-01-01

    Streams affected by wastewater treatment plant (WWTP) effluents are hotspots of nitrification. We analyzed the influence of WWTP inputs on the abundance, distribution, and composition of epilithic ammonia-oxidizing (AO) assemblages in five Mediterranean urban streams by qPCR and amoA gene cloning and sequencing of both archaea (AOA) and bacteria (AOB). The effluents significantly modified stream chemical parameters, and changes in longitudinal profiles of both NH(4)(+) and NO(3)(-) indicated stimulated nitrification activity. WWTP effluents were an allocthonous source of both AOA, essentially from the Nitrosotalea cluster, and mostly of AOB, mainly Nitrosomonas oligotropha, Nitrosomonas communis, and Nitrosospira spp. changing the relative abundance and the natural composition of AO assemblages. Under natural conditions, Nitrososphaera and Nitrosopumilus AOA dominated AO assemblages, and AOB were barely detected. After the WWTP perturbation, epilithic AOB increased by orders of magnitude whereas AOA did not show quantitative changes but a shift in population composition to dominance of Nitrosotalea spp. The foraneous AOB successfully settled in downstream biofilms and probably carried out most of the nitrification activity. Nitrosotalea were only observed downstream and only in biofilms exposed to either darkness or low irradiance. In addition to other potential environmental limitations for AOA distribution, this result suggests in situ photosensitivity as previously reported for Nitrosotalea under laboratory conditions.

  9. Culture-Independent Techniques for Rapid Detection of Bacteria Associated with Loss of Chloramine Residual in a Drinking Water System

    Science.gov (United States)

    Hoefel, Daniel; Monis, Paul T.; Grooby, Warwick L.; Andrews, Stuart; Saint, Christopher P.

    2005-01-01

    Chloramination is often the disinfection regimen of choice for extended drinking water systems. However, this process is prone to instability due to the growth of nitrifying bacteria. This is the first study to use alternative approaches for rapid investigation of chloraminated drinking water system instability in which flow cytometric cell sorting of bacteria with intact membranes (membrane-intact fraction) (BacLight kit) or with active esterases (esterase-active fraction) (carboxyfluorescein diacetate) was combined with 16S rRNA gene-directed PCR and denaturing gradient gel electrophoresis (DGGE). No active bacteria were detected when water left the water treatment plant (WTP), but 12 km downstream the chloramine residual had diminished and the level of active bacteria in the bulk water had increased to more than 1 × 105 bacteria ml−1. The bacterial diversity in the system was represented by six major DGGE bands for the membrane-intact fraction and 10 major DGGE bands for the esterase-active fraction. PCR targeting of the 16S rRNA gene of chemolithotrophic ammonia-oxidizing bacteria (AOB) and subsequent DGGE and DNA sequence analysis revealed the presence of an active Nitrosospira-related species and Nitrosomonas cryotolerans in the system, but no AOB were detected in the associated WTP. The abundance of active AOB was then determined by quantitative real-time PCR (qPCR) targeting the amoA gene; 3.43 × 103 active AOB ml−1 were detected in the membrane-intact fraction, and 1.40 × 104 active AOB ml−1 were detected in the esterase-active fraction. These values were several orders of magnitude greater than the 2.5 AOB ml−1 detected using a routine liquid most-probable-number assay. Culture-independent techniques described here, in combination with existing chemical indicators, should allow the water industry to obtain more comprehensive data with which to make informed decisions regarding remedial action that may be required either prior to or during an

  10. Nitrite oxidizing bacteria for water treatment in coastal aquaculture system

    Science.gov (United States)

    Noorak, S.; Rakkhiaw, S.; Limjirakhajornt, K.; Uppabullung, A.; Keawtawee, T.; Sangnoi, Y.

    2018-04-01

    This research aimed to isolate and characterize nitrite oxidizing bacteria and to study their capability for water quality improvement. Fourteen strains of bacteria with nitrite-oxidizing character were isolated after 21 days of enrichment in Pep-Beef-NOB medium contained NaNO2. Two strains, SF-1 and SF-5, showed highest nitrite removal rate for 42.42% and 37.2%, respectively. These strains were determined an efficiency of open-system wastewater treatment for 14 days. The results showed that control, SF-1 and SF-5 had remove ammonia from day 1 to day 6. At the end of the study, ammonia was removed by the control, SF-1 and SF-5 for 81.27%, 70.1% and 69.82%, respectively. Nitrite concentration was lowest at day 8 with removal rate of 98.73%, 98.3% and 97.24% from control, SF-1 and SF-5, respectively. However, nitrite concentration in control experiment was increased again at day 11 whereas in SF-1 and SF-5 were increased at day 13. Chemical Oxygen Demand (COD) was decreased by 77.78%, 73.50% and 78.63% in the control, SF-1 and SF-5, respectively. Biological Oxygen Demand (BOD) in the control, SF-1 and SF-5 were reduced by 85.92%, 79.53% and 82.09%, respectively. Based on 16S rRNA gene, SF-1 and SF-5 were identified as Bacillus vietnamensis and B. firmus, respectively.

  11. [Ammonia-oxidizing archaea and their important roles in nitrogen biogeochemical cycling: a review].

    Science.gov (United States)

    Liu, Jing-Jing; Wu, Wei-Xiang; Ding, Ying; Shi, De-Zhi; Chen, Ying-Xu

    2010-08-01

    As the first step of nitrification, ammonia oxidation is the key process in global nitrogen biogeochemical cycling. So far, the autotrophic ammonia-oxidizing bacteria (AOB) in the beta- and gamma-subgroups of proteobacteria have been considered as the most important contributors to ammonia oxidation, but the recent researches indicated that ammonia-oxidizing archaea (AOA) are widely distributed in various kinds of ecosystems and quantitatively predominant, playing important roles in the global nitrogen biogeochemical cycling. This paper reviewed the morphological, physiological, and ecological characteristics and the molecular phylogenies of AOA, and compared and analyzed the differences and similarities of the ammonia monooxygenase (AMO) and its encoding genes between AOA and AOB. In addition, the potential significant roles of AOA in nitrogen biogeochemical cycling in aquatic and terrestrial ecosystems were summarized, and the future research directions of AOA in applied ecology and environmental protection were put forward.

  12. Regulation of adrenomedullin and nitric oxide production by periodontal bacteria.

    Science.gov (United States)

    Hussain, Q A; McKay, I J; Gonzales-Marin, C; Allaker, R P

    2015-10-01

    In periodontitis the host response to bacterial challenge includes activity of the multifunctional molecules adrenomedullin (AM) and nitric oxide (NO). The aim of this study was to investigate the role of periodontal bacteria in regulating the production of these molecules from cultured cells. Regulation of AM and NO production from oral keratinocytes when challenged with culture supernatants from Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Veillonella atypica, Streptococcus salivarius and Candida albicans was examined. AM and NO were measured in cell culture supernatants using an enzyme-linked immunosorbent assay and the nitrate/nitrite (NO metabolites) Griess assay respectively. Cellular production of AM and inducible NO synthase was also analysed in target cells by immunofluorescence and Western blot analysis. The inter-relationship of AM and NO production were further investigated with macrophages. A. actinomycetemcomitans and C. rectus induced maximal levels of both AM and NO after 6 and 48 h respectively from oral keratinocytes. AM production in macrophages was upregulated in response to the NO donor S-nitrosoglutathione and partially blocked by the inducible NO synthase inhibitor, N(ω) -Nitro-l-arginine methyl ester hydrochloride. Likewise, NO production was increased upon exposure to AM, while the AM receptor antagonist AM 22-52 reduced the release of NO. Pathogens associated with aggressive periodontitis, A. actinomycetemcomitans and C. rectus, were more effective than those associated with chronic periodontitis, P. gingivalis and Prev. intermedia, and commensals, S. salivarius and V. atypica, as regards the upregulation of AM and NO production from oral keratinocytes. Interaction between these molecules was also demonstrated with macrophages. Understanding the coordinated regulation of AM and NO production in response to periodontal bacteria may identify

  13. Oxidation of methane in biotrickling filters inoculated with methanotrophic bacteria.

    Science.gov (United States)

    Cáceres, Manuel; Dorado, Antonio D; Gentina, Juan C; Aroca, Germán

    2017-11-01

    The oxidation of methane (CH 4 ) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH 4 that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH 4 elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH 4 in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO 2 production (pCO 2 ) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH 4 . A dynamic mathematical model that describes the CH 4 abatement in the BTFs was developed and validated using mass transfer and kinetic parameters estimated independently. The results showed that EC and pCO 2 of the BTFs are not identical but very similar for all the conditions tested. The use of specific inoculum has shown a faster startup and higher EC per unit area (0.019 gCH 4  m -2  h -1 ) in comparison to most of the previous studies at the same CH 4 load rate (23.2 gCH 4  m -3  h -1 ). Global mass balance showed that the maximum reduction of CO 2 equivalents was 98.5 gCO 2eq  m -3  h -1 . The developed model satisfactorily described CH 4 abatement in BTFs for a wide range of conditions.

  14. The response of ammonia-oxidizing microorganisms to trace metals and urine in two grassland soils in New Zealand.

    Science.gov (United States)

    Wang, Pengcheng; Di, Hong J; Cameron, Keith C; Tan, Qiling; Podolyan, Andriy; Zhao, Xiaohu; McLaren, Ron G; Hu, Chengxiao

    2017-01-01

    An incubation experiment was conducted to investigate the response of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and the nitrification rate to the contamination of Cu, Zn, and Cd in two New Zealand grassland soils. The soils spiked with different concentrations of Cu (20 and 50 mg kg -1 ), Zn (20 and 50 mg kg -1 ), and Cd (2 and 10 mg kg -1 ) were incubated for 14 days and then treated with 500 mg kg -1 urine-N before continuing incubation for a total of 115 days. Soils were sampled at intervals throughout the incubation. The nitrification rate in soils at each sampling period was determined, and the abundance of AOB and AOA was measured by real-time quantification polymerase chain reaction (qPCR) assay of the amoA gene copy numbers. The results revealed that moderate trace metal stress did not significantly affect the abundance of AOB and AOA in the two soils, probably due to the high organic matter content of the soils which would have reduced the toxic effect of the metals. Nitrification rates were much greater and the observable nitrification period was much shorter in the dairy farm (DF) soil, in which the AOB and AOA abundances were greater than those of the mixed cropping farm (MF) soil. AOB were shown to grow under high nitrogen conditions, whereas AOA were shown to grow under low N environments, with different metal concentrations. Therefore, nitrogen status rather than metal applications was the main determining factor for AOB and AOA growth in the two soils studied.

  15. Biochemical and chemical characterization of pink-pigmented oxidative bacteria.

    Science.gov (United States)

    Wallace, P L; Hollis, D G; Weaver, R E; Moss, C W

    1990-04-01

    The biochemical and chemical characteristics were determined for 156 clinical isolates of pink-pigmented bacteria that are similar to but distinct from Methylobacterium extorquens (synonymous with Pseudomonas mesophilica). These isolates were gram-negative, nonfermentative, usually nonvacuolated, coccoid rods; all grew at 35 degrees C and were catalase and urease positive; the majority grew on MacConkey agar and were variable for oxidase production and motility. On the basis of oxidation of xylose and mannitol and hydrolysis of esculin, these 156 strains were subdivided into four groups that were designated "pink coccoid" groups I, II, III, and IV. Groups I, II, and III are similar to an unnamed taxon described by Gilardi and Faur in 1984; only strains of group IV hydrolyze esculin. The cellular fatty acid compositions of strains of groups I, II, and III were essentially identical and differed from strains of group IV by the absence of 3-OH-C14:0 and the presence of C19:0 delta and 2-OH-C19:0 delta. The fatty acid composition of group IV strains was most similar to that of M. extorquens but differed by the presence of small amounts of two C17:1 acids, 3-OH-C16:0, and 2-OH-C18:1.

  16. Responses of bacterial and archaeal ammonia oxidizers to soil organic and fertilizer amendments under long-term management

    Energy Technology Data Exchange (ETDEWEB)

    Wessen, E.; Nyberg, K.; Jansson, J.K.; Hallin, S.

    2010-05-01

    Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) co-exist in soil, but their relative distribution may vary depending on the environmental conditions. Effects of changes in soil organic matter and nutrient content on the AOB and AOA are poorly understood. Our aim was to compare effects of long-term soil organic matter depletion and amendments with labile (straw) and more recalcitrant (peat) organic matter, with and without easily plant-available nitrogen, on the activities, abundances and community structures of AOB and AOA. Soil was sampled from a long-term field site in Sweden that was established in 1956. The potential ammonia oxidation rates, the AOB and AOA amoA gene abundances and the community structures of both groups based on T-RFLP of amoA genes were determined. Straw amendment during 50 years had not altered any of the measured soil parameters, while the addition of peat resulted in a significant increase of soil organic carbon as well as a decrease in pH. Nitrogen fertilization alone resulted in a small decrease in soil pH, organic carbon and total nitrogen, but an increase in primary production. Type and amount of organic matter had an impact on the AOB and AOA community structures and the AOA abundance. Our findings confirmed that AOA are abundant in soil, but showed that under certain conditions the AOB dominate, suggesting niche differentiation between the two groups at the field site. The large differences in potential rates between treatments correlated to the AOA community size, indicating that they were functionally more important in the nitrification process than the AOB. The AOA abundance was positively related to addition of labile organic carbon, which supports the idea that AOA could have alternative growth strategies using organic carbon. The AOB community size varied little in contrast to that of the AOA. This indicates that the bacterial ammonia oxidizers as a group have a greater ecophysiological diversity and

  17. Heterotrophs are key contributors to nitrous oxide production in activated sludge under low C-to-N ratios during nitrification-Batch experiments and modeling.

    Science.gov (United States)

    Domingo-Félez, Carlos; Pellicer-Nàcher, Carles; Petersen, Morten S; Jensen, Marlene M; Plósz, Benedek G; Smets, Barth F

    2017-01-01

    Nitrous oxide (N 2 O), a by-product of biological nitrogen removal during wastewater treatment, is produced by ammonia-oxidizing bacteria (AOB) and heterotrophic denitrifying bacteria (HB). Mathematical models are used to predict N 2 O emissions, often including AOB as the main N 2 O producer. Several model structures have been proposed without consensus calibration procedures. Here, we present a new experimental design that was used to calibrate AOB-driven N 2 O dynamics of a mixed culture. Even though AOB activity was favoured with respect to HB, oxygen uptake rates indicated HB activity. Hence, rigorous experimental design for calibration of autotrophic N 2 O production from mixed cultures is essential. The proposed N 2 O production pathways were examined using five alternative process models confronted with experimental data inferred. Individually, the autotrophic and heterotrophic denitrification pathway could describe the observed data. In the best-fit model, which combined two denitrification pathways, the heterotrophic was stronger than the autotrophic contribution to N 2 O production. Importantly, the individual contribution of autotrophic and heterotrophic to the total N 2 O pool could not be unambiguously elucidated solely based on bulk N 2 O measurements. Data on NO would increase the practical identifiability of N 2 O production pathways. Biotechnol. Bioeng. 2017;114: 132-140. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. Nitrous oxide emission from polyculture constructed wetlands: Effect of plant species

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanhua [School of Environmental Science and Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Min Hang, Shanghai 200240 (China); Inamori, Ryuhei [Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Kong Hainan [School of Environmental Science and Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Min Hang, Shanghai 200240 (China)], E-mail: remanda@126.com; Xu Kaiqin [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506 (Japan); State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan Unviversity, Wuhan 430072 (China); Inamori, Yuhei [Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Kondo, Takashi [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506 (Japan); Zhang Jixiang [School of Economics and Management, Southeast University, Nanjing, Jiangsu 210096 (China)

    2008-03-15

    Loss of nitrogen from the soil-plant system has raised environmental concern. This study assessed the fluxes of nitrous oxide (N{sub 2}O) in the subsurface flow constructed wetlands (CWs). To better understand the mechanism of N{sub 2}O emission, spatial distribution of ammonia-oxidizing bacteria (AOB) in four kinds of wetlands soil were compared. N{sub 2}O emission data showed large temporal and spatial variation ranging from -5.5 to 32.7 mg N{sub 2}O m{sup -2} d{sup -1}. The highest N{sub 2}O emission occurred in the cell planted with Phragmites australis and Zizania latifolia. Whereas, the lower emission rate were obtained in the cell planted with P. australis and Typha latifolia. These revealed that Z. latifolia stimulated the N{sub 2}O emission. Transportation of more organic matter and oxygen for AOB growth may be the reason. The study of AOB also supported this result, indicating that the root structure of Z. latifolia was favored by AOB for N{sub 2}O formation. - Zizania latifolia has a large contribution to global warming.

  19. Toxicity and transformation of graphene oxide and reduced graphene oxide in bacteria biofilm.

    Science.gov (United States)

    Guo, Zhiling; Xie, Changjian; Zhang, Peng; Zhang, Junzhe; Wang, Guohua; He, Xiao; Ma, Yuhui; Zhao, Bin; Zhang, Zhiyong

    2017-02-15

    Impact of graphene based material (GNMs) on bacteria biofilm has not been well understood yet. In this study, we compared the impact of graphene oxide (GO) and reduced graphene oxide (rGO) on biofilm formation and development in Luria-Bertani (LB) medium using Escherichia coli and Staphylococcus aureus as models. GO significantly enhanced the cell growth, biofilm formation, and biofilm development even up to a concentration of 500mg/L. In contrast, rGO (≥50mg/L) strongly inhibited cell growth and biofilm formation. However, the inhibitory effects of rGO (50mg/L and 100mg/L) were attenuated in the mature phase (>24h) and eliminated at 48h. GO at 250mg/L decreased the reactive oxygen species (ROS) levels in biofilm and extracellular region at mature phase. ROS levels were significantly increased by rGO at early phase, while they returned to the same levels as control at mature phase. These results suggest that oxidative stress contributed to the inhibitory effect of rGO on bacterial biofilm. We further found that supplement of extracellular polymeric substances (EPS) in the growth medium attenuated the inhibitory effect of rGO on the growth of developed biofilm. XPS results showed that rGO were oxidized to GO which can enhance the bacterial growth. We deduced that the elimination of the toxicity of rGO at mature phase was contributed by EPS protection and the oxidation of rGO. This study provides new insights into the interaction of GNMs with bacteria biofilm. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Microbial activities in boreal soils: Biodegradation of organic contaminants at low temperature and ammonia oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kurola, J. (University of Helsinki, Faculty of Biosciences, Department of Ecological and Environmental Sciences, Lahti (FI))

    2006-07-01

    This thesis deals with the response of biodegradation of selected anthropogenic organic contaminants and natural autochthonous organic matter to low temperature in boreal surface soils. Furthermore, the thesis describes activity, diversity and population size of autotrophic ammonia-oxidizing bacteria (AOB) in a boreal soil used for landfarming of oil-refinery wastes, and presents a new approach, in which the particular AOB were enriched and cultivated in situ from the landfarming soil onto cation exchange membranes. This thesis demonstrates that rhizosphere fraction of natural forest humus soil and agricultural clay loam soil from Helsinki Metropolitan area were capable of degrading of low to moderate concentrations (0.2 - 50 mug cm-3) of PCP, phenanthrene and 2,4,5-TCP at temperatures realistic to boreal climate (-2.5 to +15 deg C). At the low temperatures, the biodegradation of PCP, phenanthrene and 2,4,5-TCP was more effective (Q10-values from 1.6 to 7.6) in the rhizosphere fraction of the forest soil than in the agricultural soil. Q10-values of endogenous soil respiration (carbon dioxide evolution) and selected hydrolytic enzyme activities (acetate-esterase, butyrate-esterase and beta-glucosidase) in acid coniferous forest soil were 1.6 to 2.8 at temperatures from -3 to +30 deg C. The results indicated that the temperature dependence of decomposition of natural autochthonous soil organic matter in the studied coniferous forest was only moderate. The numbers of AOB in the landfarming (sandy clay loam) soil were determined with quantitative polymerase chain reaction (real-time PCR) and with Most Probable Number (MPN) methods, and potential ammonium oxidation activity was measured with the chlorate inhibition technique. The results indicated presence of large and active AOB populations in the heavily oil-contaminated and urea-fertilised landfarming soil. Assessment of the populations of AOB with denaturing gradient gel electrophoresis (DGGE) profiling and sequence

  1. Immobilization of ammonia-oxidizing bacteria by polyvinyl alcohol and sodium alginate.

    Science.gov (United States)

    Dong, Yuwei; Zhang, Yanqiu; Tu, Baojun

    Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30°C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  2. Different Abilities of Eight Mixed Cultures of Methane-oxidizing Bacteria to Degrade TCE

    DEFF Research Database (Denmark)

    Broholm, Kim; Christensen, Thomas Højlund; Jensen, Bjørn K.

    1993-01-01

    The ability of eight mixed cultures of methane-oxidizing bacteria to degrade trichloroethylene (TCE) was examined in laboratory batch experiments. This is one of the first reported works studying TCE degradation by mixed cultures of methane-oxidizing bacteria at 10°C, a common temperature for soils...... methanol, but only for a limited time period of about 5 days. Several explanations for the discontinued degradation of TCE are given. An experiment carried out to re-activate the methane-oxidizing bacteria after 8 days of growth on methanol by adding methane did not immediately result in degradation...... of methane and TCE. During the first 10–15 days after the addition of methane a significant degradation of methane and a minor degradation of TCE were observed. This experiment revealed that the ability of mixed cultures of methane-oxidizing bacteria to degrade TCE varied significantly even though...

  3. Mechanisms and evolution of oxidative sulfur metabolism in green sulfur bacteria

    DEFF Research Database (Denmark)

    Gregersen, Lea Haarup; Bryant, Donald A.; Frigaard, Niels-Ulrik

    2011-01-01

    Green sulfur bacteria (GSB) constitute a closely related group of photoautotrophic and thiotrophic bacteria with limited phenotypic variation. They typically oxidize sulfide and thiosulfate to sulfate with sulfur globules as an intermediate. Based on genome sequence information from 15 strains...... product is further oxidized to sulfite by the dissimilatory sulfite reductase (DSR) system. This system consists of components horizontally acquired partly from sulfide-oxidizing and partly from sulfate-reducing bacteria. Depending on the strain, the sulfite is probably oxidized to sulfate by one of two...... in sulfate formation in other bacteria has been replaced by the DSR system in GSB. Sequence analyses suggested that the conserved soxJXYZAKBW gene cluster was horizontally acquired by Chlorobium phaeovibrioides DSM 265 from the Chlorobaculum lineage and that this acquisition was mediated by a mobile genetic...

  4. Detection, phylogeny and population dynamics of syntrophic propionate - oxidizing bacteria in anaerobic granular sludge

    NARCIS (Netherlands)

    Harmsen, H.J.M.

    1996-01-01


    The research described this thesis concerns the diversity and phylogeny of syntrophic propionate-oxidizing bacteria and their ecology in granular sludge, from which they were obtained. 16S rRNA was used as a molecular marker to study both the phylogeny and the ecology of these bacteria.

  5. Inhibition of bacterial ammonia oxidation by organohydrazines in soil microcosms

    Directory of Open Access Journals (Sweden)

    Yucheng eWu

    2012-01-01

    Full Text Available Hydroxylamine oxidation by hydroxylamine oxidoreductase (HAO is a key step for energy-yielding in support of the growth of ammonia-oxidizing bacteria (AOB. Organohydrazines have been shown to inactivate HAO from Nitrosomonas europaea, and may serve as selective inhibitors to differentiate bacterial from archaeal ammonia oxidation due to the absence of bacterial HAO gene homologue in known ammonia-oxidizing archaea (AOA. In this study, the effects of three organohydrazines on activity, abundance and composition of AOB and AOA were evaluated in soil microcosms. The results indicate that phenylhydrazine and methylhydrazine at the concentration of 100 mol per gram dry weight soil completely suppressed the activity of soil nitrification. DGGE fingerprinting and sequencing analysis of bacterial ammonia monooxygenase subunit A gene (amoA clearly demonstrated that nitrification activity change is well paralleled with the growth of Nitrosomonas europaea-like AOB in soil microcosms. No significant correlation between AOA community structure and nitrification activity was observed among all treatments during the incubation period, although incomplete inhibition of nitrification activity occurred in 2-hydroxyethylhydrazine-amended soil microcosms. These findings show that the HAO-targeted organohydrazines can effectively inhibit bacterial nitrification in soil, and the mechanism of organohydrazine affecting AOA remains unclear.

  6. Weakened activity of starved ammonia-oxidizing bacteria by the presence of pre-activated Nitrobacter winogradskyi

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.

    2002-01-01

    Ammonia-oxidizing bacteria are able to maintain a high oxidizing potential during starvation. nitrite has a short-lasting stimulatory effect on the oxidation of ammonia after starvation when supplied simultaneously with fresh ammonium. To examine whether nitrite-oxidizing bacteria as partners in

  7. Weakened activity of starved ammonia-oxidizing bacteria by the presence of pre-activated Nitrobacter winogradskyi

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.

    2002-01-01

    Ammonia-oxidizing bacteria are able to maintain a high oxidizing potential during starvation. Nitrite has a short-lasting stimulatory effect on the oxidation of ammonia after starvation when supplied simultaneously with fresh ammonium9). To examine whether nitrite-oxidizing bacteria as partners in

  8. Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics.

    Science.gov (United States)

    Xu, Sai; Lu, Wenjing; Mustafa, Muhammad Farooq; Caicedo, Luis Miguel; Guo, Hanwen; Fu, Xindi; Wang, Hongtao

    2017-11-01

    Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures and their abundance in sewage sludge collected from wastewater treatment plants were analysed. Results indicated that ANAMMOX and DAMO bacteria co-existed in sewage sludge in different seasons and their abundance was positively correlated (P bacteria in autumn and winter indicated that these seasons were the preferred time to favour the growth of ANAMMOX and DAMO bacteria. The community structure of ANNAMOX and DAMO bacteria could also shift with seasonal changes. The "Candidatus Brocadia" genus of ANAMMOX bacteria was mainly recovered in spring and summer, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion. The redundancy analysis revealed that pH and nitrate were the most significant factors affecting community structures of these two groups (P < 0.01). This study reported the diversity of ANAMMOX and DAMO in wastewater treatment plants that may be the basis for new nitrogen removal technologies.

  9. Emergent macrophytes modify the abundance and community composition of ammonia oxidizers in their rhizosphere sediments.

    Science.gov (United States)

    Zhao, Dayong; He, Xiaowei; Huang, Rui; Yan, Wenming; Yu, Zhongbo

    2017-07-01

    Ammonia oxidation is a crucial process in global nitrogen cycling, which is catalyzed by the ammonia oxidizers. Emergent plants play important roles in the freshwater ecosystem. Therefore, it is meaningful to investigate the effects of emergent macrophytes on the abundance and community composition of ammonia oxidizers. In the present study, two commonly found emergent macrophytes (Zizania caduciflora and Phragmitas communis) were obtained from freshwater lakes and the abundance and community composition of the ammonia-oxidizing prokaryotes in the rhizosphere sediments of these emergent macrophytes were investigated. The abundance of the bacterial amoA gene was higher in the rhizosphere sediments of the emergent macrophytes than those of bulk sediments. Significant positive correlation was found between the potential nitrification rates (PNRs) and the abundance of bacterial amoA gene, suggesting that ammonia-oxidizing bacteria (AOB) might play an important role in the nitrification process of the rhizosphere sediments of emergent macrophytes. The Nitrosotalea cluster is the dominant ammonia-oxidizing archaea (AOA) group in all the sediment samples. Analysis of AOB group showed that the N. europaeal cluster dominated the rhizosphere sediments of Z. caduciflora and the bulk sediments, whereas the Nitrosospira cluster was the dominant AOB group in the rhizosphere sediments of P. communis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Differentiation in the microbial ecology and activity of suspended and attached bacteria in a nitritation-anammox process.

    Science.gov (United States)

    Park, Hongkeun; Sundar, Suneethi; Ma, Yiwei; Chandran, Kartik

    2015-02-01

    A directed differentiation between the biofilm and suspension was observed in the molecular microbial ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the microbial ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation. © 2014 Wiley Periodicals, Inc.

  11. Anaerobic ammonium oxidation by Anammox bacteria in the Black Sea

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kuypers, M.M.M.; Sliekers, O.; Lavik, G.; Schmid, M.; Jørgensen, B.B.; Kuenen, J.G.; Strous, M.; Jetten, M.S.M.

    2003-01-01

    The availability of fixed inorganic nitrogen (nitrate, nitrite and ammonium) limits primary productivity in many oceanic regions1. The conversion of nitrate to N2 by heterotrophic bacteria (denitrification) is believed to be the only important sink for fixed inorganic nitrogen in the ocean2. Here we

  12. Oxidative Stress Parameters in Saliva and Its Association with Periodontal Disease and Types of Bacteria.

    Science.gov (United States)

    Almerich-Silla, Jose Manuel; Montiel-Company, Jose María; Pastor, Sara; Serrano, Felipe; Puig-Silla, Miriam; Dasí, Francisco

    2015-01-01

    To determine the association between oxidative stress parameters with periodontal disease, bleeding, and the presence of different periodontal bacteria. A cross-sectional study in a sample of eighty-six patients, divided into three groups depending on their periodontal status. Thirty-three with chronic periodontitis, sixteen with gingivitis, and thirty-seven with periodontal healthy as control. Oxidative stress biomarkers (8-OHdG and MDA), total antioxidant capacity (TAOC), and the activity of two antioxidant enzymes (GPx and SOD) were determined in saliva. Subgingival plaque samples were obtained from the deepest periodontal pocket and PCR was used to determine the presence of the 6 fimA genotypes of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Treponema denticola. Periodontal disease was found to be associated with increased oxidative stress parameter levels. These levels rose according to the number and type of different periodontal bacteria found in the periodontal pockets. The presence of different types of periodontal bacteria is predictive independent variables in linear regresion models of oxidative stress parameters as dependent variable, above all 8-OHdG. Oxidative stress parameter levels are correlated with the presence of different types of bacteria. Determination of these levels and periodontal bacteria could be a potent tool for controlling periodontal disease development.

  13. Comparison of partial and full nitrification processes applied for treating high-strength nitrogen wastewaters: microbial ecology through nitrous oxide production.

    Science.gov (United States)

    Ahn, Joon Ho; Kwan, Tiffany; Chandran, Kartik

    2011-04-01

    The goal of this study was to compare the microbial ecology, gene expression, biokinetics, and N2O emissions from a lab-scale bioreactor operated sequentially in full-nitrification and partial-nitrification modes. Based on sequencing of 16S rRNA and ammonia monooxygenase subunit A (amoA) genes, ammonia oxidizing bacteria (AOB) populations during full- and partial-nitrification modes were distinct from one another. The concentrations of AOB (XAOB) and their respiration rates during full- and partial-nitrification modes were statistically similar, whereas the concentrations of nitrite oxidizing bacteria (XNOB) and their respiration rates declined significantly after the switch from full- to partial-nitrification. The transition from full-nitrification to partial nitrification resulted in a protracted transient spike of nitrous oxide (N2O) and nitric oxide (NO) emissions, which later stabilized. The trends in N2O and NO emissions correlated well with trends in the expression of nirK and norB genes that code for the production of these gases in AOB. Both the transient and stabilized N2O and NO emissions during partial nitrification were statistically higher than those during steady-state full-nitrification. Based on these results, partial nitrification strategies for biological nitrogen removal, although attractive for their reduced operating costs and energy demand, may need to be optimized against the higher carbon foot-print attributed to their N2O emissions.

  14. Iron oxide deposits associated with the ectosymbiotic bacteria in the hydrothermal vent shrimp Rimicaris exoculata

    Directory of Open Access Journals (Sweden)

    P. Compère

    2008-09-01

    Full Text Available The Rimicaris exoculata shrimp is considered as a primary consumer that dominates the fauna of most Mid-Atlantic Ridge (MAR hydrothermal ecosystems. These shrimps harbour in their gill chambers an important ectosymbiotic community of chemoautotrophic bacteria associated with iron oxide deposits. The structure and elemental composition of the mineral concretions associated with these bacteria have been investigated by using LM, ESEM, TEM STEM and EDX microanalyses. The nature of the iron oxides in shrimps obtained from the Rainbow vent field has also been determined by Mössbauer spectroscopy. This multidisciplinary approach has revealed that the three layers of mineral crust in the Rimicaris exoculata shrimps consist of large concretions formed by aggregated nanoparticles of two-line ferrihydrite and include other minor elements as Si, Ca, Mg, S and P, probably present as silicates cations, sulphates or phosphates respectively that may contribute to stabilise the ferrihydrite form of iron oxides. TEM-observations on the bacteria have revealed their close interactions with these minerals. Abiotic and biotic precipitation could occur within the gill chamber of Rimicaris exoculata, suggesting the biologically-mediated formation of the iron oxide deposits. The difference of the bacterial density in the three-mineral crust layers could be correlated to the importance of the iron oxide concretions and suggest that the first mineral particles precipitates on the lower layer which could be considered as the most likely location of iron-oxidizing bacteria.

  15. Presence of Nitrosospiral cluster 2 bacteria corresponds to N transformation rates in nine acid Scots pine forest soils.

    NARCIS (Netherlands)

    Nugroho, R. Adi; Roling, W.F.M.; Laverman, A.M.; Zoomer, R.; Verhoef, H.A.

    2005-01-01

    The relation between environmental factors and the presence of ammonia-oxidising bacteria (AOB), and its consequences for the N transformation rates were investigated in nine Scots pine (Pinus sylvestris L.) forest soils. In general, the diversity in AOB appears to be strikingly low compared to

  16. The role of sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering

    International Nuclear Information System (INIS)

    Sasaki, K.; Tsunekawa, M.; Ohtsuka, T.; Konno, H.

    1998-01-01

    The paper investigates the role of the sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering in order to clarify the effects of the bacteria on the dissolution behavior of pyrite and the formation of secondary minerals using Raman spectroscopy and powder X-ray diffraction (XRD) in addition to solution analysis. It was found that T. thiooxidans, when present with the iron-oxidizing bacteria Thiobacillus ferrooxidans, enhanced the dissolution of Fe and S species for pyrite, whereas T. thiooxidans alone did not oxidize pyrite. Enhancement of the consumption of elemental sulfur and regeneration of Fe(II) ions were also observed with T. thiooxidans together with T. ferrooxidans, while this did not occur with T. ferrooxidans alone

  17. Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics

    DEFF Research Database (Denmark)

    Xu, Sai; Lu, Wenjing; Mustafa, Muhammad Farooq

    2017-01-01

    Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures......, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion...

  18. Electron uptake by iron-oxidizing phototrophic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Bose, A; Gardel, EJ; Vidoudez, C; Parra, EA; Girguis, PR

    2014-02-26

    Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.

  19. Neutrophilic iron-oxidizing bacteria: occurrence and relevance in biological drinking water treatment

    DEFF Research Database (Denmark)

    Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

    2013-01-01

    Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully...... role of FeOB in iron removal at waterworks using RSF technologies....... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

  20. Water addition regulates the metabolic activity of ammonia oxidizers responding to environmental perturbations in dry subhumid ecosystems.

    Science.gov (United States)

    Hu, Hang-Wei; Macdonald, Catriona A; Trivedi, Pankaj; Holmes, Bronwyn; Bodrossy, Levente; He, Ji-Zheng; Singh, Brajesh K

    2015-02-01

    Terrestrial arid and semi-arid ecosystems (drylands) constitute about 41% of the Earth's land surface and are predicted to experience increasing fluctuations in water and nitrogen availability. Mounting evidence has confirmed the significant importance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in nitrification, plant nitrogen availability and atmospheric N2 O emissions, but their responses to environmental perturbations in drylands remain largely unknown. Here we evaluate how the factorial combinations of irrigation and fertilization in forests and land-use change from grassland to forest affects the dynamics of AOA and AOB following a 6-year dryland field study. Potential nitrification rates and AOA and AOB abundances were significantly higher in the irrigated plots, accompanied by considerable changes in community compositions, but their responses to fertilization alone were not significant. DNA-stable isotope probing results showed increased (13) CO2 incorporation into the amoA gene of AOA, but not of AOB, in plots receiving water addition, coupled with significantly higher net mineralization and nitrification rates. High-throughput microarray analysis revealed that active AOA assemblages belonging to Nitrosopumilus and Nitrosotalea were increasingly labelled by (13) CO2 following irrigation. However, no obvious effects of land-use changes on nitrification rates or metabolic activity of AOA and AOB could be observed under dry conditions. We provide evidence that water addition had more important roles than nitrogen fertilization in influencing the autotrophic nitrification in dryland ecosystems, and AOA are increasingly involved in ammonia oxidation when dry soils become wetted. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Solubilization of plutonium hydrous oxide by iron-reducing bacteria

    International Nuclear Information System (INIS)

    Rusin, P.A.; Quintana, L.; Brainard, J.R.; Strietelmeler, B.A.; Tait, C.D.; Ekberg, S.A.; Palmer, P.D.; Newton, T.W.; Clark, D.L.

    1994-01-01

    The removal of plutonium from soils id challenging because of its strong sorption to soils and limited solubility, Microbial reduction of metals is known to affect the speciation and solubility of sparingly soluble metals in the environment, notably iron and manganese. The similarity in reduction potential for α-FeOOH(s) and hydrous PuO 2 (s) suggests that iron-reducing bacteria may also reduce and solubilize plutonium. Bacillus strains were used to demonstrate that iron-reducing bacteria mediate the solubilization of hydrous PuO 2 (s) under anaerobic conditions. Up to ∼90% of the PuO 2 was biosolubilized in the presence of nitrilotriacetic acid (NTA) within 6-7 days. Biosolubilization occurred to a lesser extent (∼ 40%) in the absence of NTA. Little PuO 2 solubilization occurred in sterile culture media or in the presence of a non-iron-reducing Escherichia coli. These observations suggest a potentially attractive, environmentally benign strategy for the remediation of Pu-contaminated soils. 26 refs., 5 figs., 2 tabs

  2. FORMALDEHYDE DISMUTASE ACTIVITIES IN GRAM-POSITIVE BACTERIA OXIDIZING METHANOL

    NARCIS (Netherlands)

    BYSTRYKH, LV; GOVORUKHINA, NI; VANOPHEM, PW; HEKTOR, HJ; DIJKHUIZEN, L; DUINE, JA; Govorukhina, Natalya; Ophem, Peter W. van; Duine, Johannis A.

    Extracts of methanol-grown cells of Amycolatopsis methanolica and Mycobacterium gastri oxidized methanol and ethanol with concomitant reduction of N,N'-dimethyl-4-nitrosoaniline (NDMA). Anion-exchange chromatography revealed the presence of a single enzyme able to catalyse this activity in methanol-

  3. Metagenomic analysis of nitrate-reducing bacteria in the oral cavity: implications for nitric oxide homeostasis.

    Science.gov (United States)

    Hyde, Embriette R; Andrade, Fernando; Vaksman, Zalman; Parthasarathy, Kavitha; Jiang, Hong; Parthasarathy, Deepa K; Torregrossa, Ashley C; Tribble, Gena; Kaplan, Heidi B; Petrosino, Joseph F; Bryan, Nathan S

    2014-01-01

    The microbiota of the human lower intestinal tract helps maintain healthy host physiology, for example through nutrient acquisition and bile acid recycling, but specific positive contributions of the oral microbiota to host health are not well established. Nitric oxide (NO) homeostasis is crucial to mammalian physiology. The recently described entero-salivary nitrate-nitrite-nitric oxide pathway has been shown to provide bioactive NO from dietary nitrate sources. Interestingly, this pathway is dependent upon oral nitrate-reducing bacteria, since humans lack this enzyme activity. This pathway appears to represent a newly recognized symbiosis between oral nitrate-reducing bacteria and their human hosts in which the bacteria provide nitrite and nitric oxide from nitrate reduction. Here we measure the nitrate-reducing capacity of tongue-scraping samples from six healthy human volunteers, and analyze metagenomes of the bacterial communities to identify bacteria contributing to nitrate reduction. We identified 14 candidate species, seven of which were not previously believed to contribute to nitrate reduction. We cultivated isolates of four candidate species in single- and mixed-species biofilms, revealing that they have substantial nitrate- and nitrite-reduction capabilities. Colonization by specific oral bacteria may thus contribute to host NO homeostasis by providing nitrite and nitric oxide. Conversely, the lack of specific nitrate-reducing communities may disrupt the nitrate-nitrite-nitric oxide pathway and lead to a state of NO insufficiency. These findings may also provide mechanistic evidence for the oral systemic link. Our results provide a possible new therapeutic target and paradigm for NO restoration in humans by specific oral bacteria.

  4. Metagenomic analysis of nitrate-reducing bacteria in the oral cavity: implications for nitric oxide homeostasis.

    Directory of Open Access Journals (Sweden)

    Embriette R Hyde

    Full Text Available The microbiota of the human lower intestinal tract helps maintain healthy host physiology, for example through nutrient acquisition and bile acid recycling, but specific positive contributions of the oral microbiota to host health are not well established. Nitric oxide (NO homeostasis is crucial to mammalian physiology. The recently described entero-salivary nitrate-nitrite-nitric oxide pathway has been shown to provide bioactive NO from dietary nitrate sources. Interestingly, this pathway is dependent upon oral nitrate-reducing bacteria, since humans lack this enzyme activity. This pathway appears to represent a newly recognized symbiosis between oral nitrate-reducing bacteria and their human hosts in which the bacteria provide nitrite and nitric oxide from nitrate reduction. Here we measure the nitrate-reducing capacity of tongue-scraping samples from six healthy human volunteers, and analyze metagenomes of the bacterial communities to identify bacteria contributing to nitrate reduction. We identified 14 candidate species, seven of which were not previously believed to contribute to nitrate reduction. We cultivated isolates of four candidate species in single- and mixed-species biofilms, revealing that they have substantial nitrate- and nitrite-reduction capabilities. Colonization by specific oral bacteria may thus contribute to host NO homeostasis by providing nitrite and nitric oxide. Conversely, the lack of specific nitrate-reducing communities may disrupt the nitrate-nitrite-nitric oxide pathway and lead to a state of NO insufficiency. These findings may also provide mechanistic evidence for the oral systemic link. Our results provide a possible new therapeutic target and paradigm for NO restoration in humans by specific oral bacteria.

  5. Adaptation of ammonia-oxidizing microorganisms to environment shift of paddy field soil.

    Science.gov (United States)

    Ke, Xiubin; Lu, Yahai

    2012-04-01

    Adaptation of microorganisms to the environment is a central theme in microbial ecology. The objective of this study was to investigate the response of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) to a soil medium shift. We employed two rice field soils collected from Beijing and Hangzhou, China. These soils contained distinct AOB communities dominated by Nitrosomonas in Beijing rice soil and Nitrosospira in Hangzhou rice soil. Three mixtures were generated by mixing equal quantities of Beijing soil and Hangzhou soil (BH), Beijing soil with sterilized Hangzhou soil (BSH), and Hangzhou soil with sterilized Beijing soil (HSB). Pure and mixed soils were permanently flooded, and the surface-layer soil where ammonia oxidation occurred was collected to determine the response of AOB and AOA to the soil medium shift. AOB populations increased during the incubation, and the rates were initially faster in Beijing soil than in Hangzhou soil. Nitrosospira (cluster 3a) and Nitrosomonas (communis cluster) increased with time in correspondence with ammonia oxidation in the Hangzhou and Beijing soils, respectively. The 'BH' mixture exhibited a shift from Nitrosomonas at day 0 to Nitrosospira at days 21 and 60 when ammonia oxidation became most active. In 'HSB' and 'BSH' mixtures, Nitrosospira showed greater stimulation than Nitrosomonas, both with and without N amendment. These results suggest that Nitrosospira spp. were better adapted to soil environment shifts than Nitrosomonas. Analysis of the AOA community revealed that the composition of AOA community was not responsive to the soil environment shifts or to nitrogen amendment. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. Ammonia-Oxidizing β-Proteobacteria from the Oxygen Minimum Zone off Northern Chile▿

    Science.gov (United States)

    Molina, Verónica; Ulloa, Osvaldo; Farías, Laura; Urrutia, Homero; Ramírez, Salvador; Junier, Pilar; Witzel, Karl-Paul

    2007-01-01

    The composition of ammonia-oxidizing bacteria from the β-Proteobacteria subclass (βAOB) was studied in the surface and upper-oxycline oxic waters (2- to 50-m depth, ∼200 to 44 μM O2) and within the oxygen minimum zone (OMZ) suboxic waters (50- to 400-m depth, ≤10 μM O2) of the eastern South Pacific off northern Chile. This study was carried out through cloning and sequencing of genes coding for 16S rRNA and the ammonia monooxygenase enzyme active subunit (amoA). Sequences affiliated with Nitrosospira-like cluster 1 dominated the 16S rRNA gene clone libraries constructed from both oxic and suboxic waters. Cluster 1 consists exclusively of yet-uncultivated βAOB from marine environments. However, a single clone, out of 224 obtained from the OMZ, was found to belong to Nitrosospira lineage cluster 0. To our knowledge, cluster 0 sequences have been derived from βAOB isolated only from sand, soil, and freshwater environments. Sequences in clone libraries of the amoA gene from the surface and upper oxycline could be grouped in a marine subcluster, also containing no cultured representatives. In contrast, all 74 amoA sequences originating from the OMZ were either closely affiliated with cultured Nitrosospira spp. from clusters 0 and 2 or with other yet-uncultured βAOB from soil and an aerated-anoxic Orbal process waste treatment plant. Our results reveal the presence of Nitrosospira-like βAOB in both oxic and suboxic waters associated with the OMZ but with a clear community shift at the functional level (amoA) along the strong oxygen gradient. PMID:17416686

  7. Enrichment of Thermophilic Propionate-Oxidizing Bacteria in Syntrophy with Methanobacterium thermoautotrophicum or Methanobacterium thermoformicicum

    OpenAIRE

    Stams, Alfons J. M.; Grolle, Katja C. F.; Frijters, Carla T. M.; Van Lier, Jules B.

    1992-01-01

    Thermophilic propionate-oxidizing, proton-reducing bacteria were enriched from the granular methanogenic sludge of a bench-scale upflow anaerobic sludge bed reactor operated at 55°C with a mixture of volatile fatty acids as feed. Thermophilic hydrogenotrophic methanogens had a high decay rate. Therefore, stable, thermophilic propionate-oxidizing cultures could not be obtained by using the usual enrichment procedures. Stable and reproducible cultivation was possible by enrichment in hydrogen-p...

  8. Oxidative Stress Parameters in Saliva and Its Association with Periodontal Disease and Types of Bacteria

    OpenAIRE

    Almerich-Silla, Jose Manuel; Montiel-Company, Jose María; Pastor, Sara; Serrano, Felipe; Puig-Silla, Miriam; Dasí, Francisco

    2015-01-01

    Objective. To determine the association between oxidative stress parameters with periodontal disease, bleeding, and the presence of different periodontal bacteria. Methods. A cross-sectional study in a sample of eighty-six patients, divided into three groups depending on their periodontal status. Thirty-three with chronic periodontitis, sixteen with gingivitis, and thirty-seven with periodontal healthy as control. Oxidative stress biomarkers (8-OHdG and MDA), total antioxidant capacity (TAOC)...

  9. Diversity and distribution of planktonic anaerobic ammonium-oxidizing bacteria in the Dongjiang River, China.

    Science.gov (United States)

    Sun, Wei; Xia, Chunyu; Xu, Meiying; Guo, Jun; Wang, Aijie; Sun, Guoping

    2014-12-01

    Anaerobic ammonium-oxidizing (anammox) process has recently been recognized as an important pathway for removing fixed nitrogen (N) from aquatic ecosystems. Anammox organisms are widely distributed in freshwater environments. However, little is known about their presence in the water column of riverine ecosystems. Here, the existence of a diverse anammox community was revealed in the water column of the Dongjiang River by analyzing 16S rRNA and hydrazine oxidation (hzo) genes of anammox bacteria. Phylogenetic analyses of hzo genes showed that Candidatus Jettenia related clades of anammox bacteria were dominant in the river, suggesting the ecological microniche distinction from freshwater/estuary and marine anammox bacteria with Ca. Brocadia and Kuenenia genera mainly detected in freshwater/estuary ecosystems, and Ca. Scalindua genus mainly detected in marine ecosystems. The abundance and diversity of anammox bacteria along the river were both significantly correlated with concentrations of NH4(+)-N based on Pearson and partial correlation analyses. Redundancy analyses showed the contents of NH4(+)-N, NO3(-)-N and the ratio of NH4(+)-N to NO2(-)-N significantly influenced the spatial distributions of anammox bacteria in the water column of the Dongjiang River. These results expanded our understanding of the distribution and potential roles of anammox bacteria in the water column of the river ecosystem. Copyright © 2014 Elsevier GmbH. All rights reserved.

  10. Growth kinetics of hydrogen sulfide oxidizing bacteria in corroded concrete from sewers

    International Nuclear Information System (INIS)

    Jensen, Henriette Stokbro; Lens, Piet N.L.; Nielsen, Jeppe L.; Bester, Kai; Nielsen, Asbjorn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2011-01-01

    Hydrogen sulfide oxidation by microbes present on concrete surfaces of sewer pipes is a key process in sewer corrosion. The growth of aerobic sulfur oxidizing bacteria from corroded concrete surfaces was studied in a batch reactor. Samples of corrosion products, containing sulfur oxidizing bacteria, were suspended in aqueous solution at pH similar to that of corroded concrete. Hydrogen sulfide was supplied to the reactor to provide the source of reduced sulfur. The removal of hydrogen sulfide and oxygen was monitored. The utilization rates of both hydrogen sulfide and oxygen suggested exponential bacterial growth with median growth rates of 1.25 d -1 and 1.33 d -1 as determined from the utilization rates of hydrogen sulfide and oxygen, respectively. Elemental sulfur was found to be the immediate product of the hydrogen sulfide oxidation. When exponential growth had been achieved, the addition of hydrogen sulfide was terminated leading to elemental sulfur oxidation. The ratio of consumed sulfur to consumed oxygen suggested that sulfuric acid was the ultimate oxidation product. To the knowledge of the authors, this is the first study to determine the growth rate of bacteria involved in concrete corrosion with hydrogen sulfide as source of reduced sulfur.

  11. Bacteria-mediated arsenic oxidation and reduction in the growth media of arsenic hyperaccumulator Pteris vittata.

    Science.gov (United States)

    Wang, Xin; Rathinasabapathi, Bala; de Oliveira, Letuzia Maria; Guilherme, Luiz R G; Ma, Lena Q

    2012-10-16

    Microbes play an important role in arsenic transformation and cycling in the environment. Microbial arsenic oxidation and reduction were demonstrated in the growth media of arsenic hyperaccumulator Pteris vittata L. All arsenite (AsIII) at 0.1 mM in the media was oxidized after 48 h incubation. Oxidation was largely inhibited by antibiotics, indicating that bacteria played a dominant role. To identify AsIII oxidizing bacteria, degenerate primers were used to amplify ∼500 bp of the AsIII oxidase gene aioA (aroA) using DNA extracted from the media. One aioA (aroA)-like sequence (MG-1, tentatively identified as Acinetobacter sp.) was amplified, exhibiting 82% and 91% identity in terms of gene and deduced protein sequence to those from Acinetobacter sp. 33. In addition, four bacterial strains with different arsenic tolerance were isolated and identified as Comamonas sp.C-1, Flavobacterium sp. C-2, Staphylococcus sp. C-3, and Pseudomonas sp. C-4 using carbon utilization, fatty acid profiles, and/or sequencing 16s rRNA gene. These isolates exhibited dual capacity for both AsV reduction and AsIII oxidation under ambient conditions. Arsenic-resistant bacteria with strong AsIII oxidizing ability may have potential to improve bioremediation of AsIII-contaminated water using P. vittata and/or other biochemical strategies.

  12. Microbial resource management for the mitigation of nitrous oxide emissions from the Partial Nitritation- Anammox process

    DEFF Research Database (Denmark)

    Blum, Jan-Michael

    Urban wastewater treatment plants are designed to remove pathogens and pollutants from wastewater in order to provide sanitation and to protect receiving water bodies from eutrophication. Reactive nitrogen, mainly in the form of ammonium, is one of the components in wastewater that is converted...... to dinitrogen gas during treatment. The Partial Nitritation-Anammox process (PNA) uses the capacity of autotrophic aerobic and anaerobic ammonia oxidizing bacteria (AOB and AnAOB) to perform this task. The process is mainly applied to treat ammonium-rich wastewater streams with low concentrations of organic...... with the specific ammonia removal rate, while during non-aerated phases net N2O production rates were positively correlated with the nitrite concentration (NO2-). Operation of PNA at reduced specific ammonia removal rates is, therefore, a feasible strategy to mitigate N2O emissions. However, when high ammonium...

  13. Anaerobic ammonium oxidation by anammox bacteria in the Black Sea RID B-8834-2011

    DEFF Research Database (Denmark)

    Kuypers, MMM; Sliekers, AO; Lavik, G.

    2003-01-01

    The availability of fixed inorganic nitrogen (nitrate, nitrite and ammonium) limits primary productivity in many oceanic regions(1). The conversion of nitrate to N(2) by heterotrophic bacteria (denitrification) is believed to be the only important sink for fixed inorganic nitrogen in the ocean(2......). Here we provide evidence for bacteria that anaerobically oxidize ammonium with nitrite to N(2) in the world's largest anoxic basin, the Black Sea. Phylogenetic analysis of 16S ribosomal RNA gene sequences shows that these bacteria are related to members of the order Planctomycetales performing...... the anammox (anaerobic ammonium oxidation) process in ammonium-removing bioreactors(3). Nutrient profiles, fluorescently labelled RNA probes, (15)N tracer experiments and the distribution of specific 'ladderane' membrane lipids(4) indicate that ammonium diffusing upwards from the anoxic deep water is consumed...

  14. Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation

    NARCIS (Netherlands)

    Pachiadaki, M.G.; Sintes, E.; Bergauer, K.; Brown, J.M.; Record, N.R.; Swan, B.K.; Mathyer, M.E.; Hallam, S.J.; López-Garcìa, P.; Takaki, Y.; Nunoura, T.; Woyke, T.; Herndl, G.J.; Stepanauskas, R.

    2017-01-01

    Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean’s interior, but the relevant taxa and energy sources remain enigmatic.We show evidence that nitrite-oxidizing bacteria affiliated with the

  15. Characterization of sulfur-oxidizing bacteria isolated from acid mine drainage and black shale samples

    International Nuclear Information System (INIS)

    Sajjad, W.; Bhatti, T. M.; Hasan, F.; Khan, S.; Badshah, M.

    2016-01-01

    Acid mine drainage (AMD) and black shale (BS) are the main habitats of sulfur-oxidizing bacteria. The aim of this study was to isolate and characterize sulfur-oxidizing bacteria from extreme acidic habitats (AMD and BS). Concentration of metals in samples from AMD and BS varied significantly from the reference samples and exceeded the acceptable limits set by the Environmental Protection Agency (EPA) and the World Health Organization (WHO). A total of 24 bacteria were isolated from these samples that were characterized both morphologically as well as through biochemical tests. All the bacteria were gram-negative rods that could efficiently oxidize sulfur into sulfate ions (SO/sub 4/-2), resulted into decrease in pH up to 1.0 when grown in thiosulfate medium with initial pH 4.0. Out of 24, only 06 isolates were selected for phylogenetic analysis through 16S rRNA sequencing, on the basis of maximum sulfur-oxidizing efficiency. The isolates were identified as the species from different genera such as Alcaligenes, Pseudomonas, Bordetella, and Stenotrophomonas on the basis of maximum similarity index. The concentration of sulfate ions produced was estimated in the range of 179-272 mg/L. These acidophiles might have various potential applications such as biological leaching of metals from low-grade ores, alkali soil reclamation and to minimize the use of chemical S-fertilizers and minimize environmental pollution. (author)

  16. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials

    NARCIS (Netherlands)

    Ganendra, G; De Muynck, W; Ho, A.; Hoefman, S.; De Vos, P.; Boeckx, P.; Boon, N.

    2014-01-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (similar to 20 % (v/v)) and low (similar to 100 ppmv) methane

  17. Continuous culture enrichments of ammonia-oxidizing bacteria at low ammonium concentrations

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2001-01-01

    Until now enrichments of ammonia-oxidizing bacteria from natural ammonium-limited environments have been performed mainly in the presence of much higher ammonia concentrations than those present in the natural environment and many have resulted in the enrichment and isolation of environmentally less

  18. Continuous culture enrichments of ammonia-oxidizing bacteria at low ammonium concentrations

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2001-01-01

    Until now enrichments of ammonia-oxidizing bacteria from natural ammonium-limited environments have been performed mainly in the presence of much higher ammonia concentrations than those present in the natural environment and many have resulted in the enrichment and isolation of environmentally

  19. Differential oxidative and antioxidative response of duckweed Lemna minor toward plant growth promoting/inhibiting bacteria.

    Science.gov (United States)

    Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

    2017-09-01

    Bacteria colonizing the plant rhizosphere are believed to positively or negatively affect the host plant productivity. This feature has inspired researchers to engineer such interactions to enhance crop production. However, it remains to be elucidated whether rhizobacteria influences plant oxidative stress vis-a-vis other environmental stressors, and whether such influence is associated with their growth promoting/inhibiting ability. In this study, two plant growth-promoting bacteria (PGPB) and two plant growth-inhibiting bacteria (PGIB) were separately inoculated into axenic duckweed (Lemna minor) culture under laboratory conditions for 4 and 8 days in order to investigate their effects on plant oxidative stress and antioxidant activities. As previously characterized, the inoculation of PGPB and PGIB strains accelerated and reduced the growth of L. minor, respectively. After 4 and 8 days of cultivation, compared to the PGPB strains, the PGIB strains induced larger amounts of O 2 •- , H 2 O 2 , and malondialdehyde (MDA) in duckweed, although all bacterial strains consistently increased O 2 •- content by two times more than that in the aseptic control plants. Activities of five antioxidant enzymes were also elevated by the inoculation of PGIB, confirming the severe oxidative stress condition in plants. These results suggest that the surface attached bacteria affect differently on host oxidative stress and its response, which degree correlates negatively to their effects on plant growth. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Anaerobic Oxidization of Methane in a Minerotrophic Peatland: Enrichment of Nitrite-Dependent Methane-Oxidizing Bacteria

    Science.gov (United States)

    Zhu, Baoli; van Dijk, Gijs; Fritz, Christian; Smolders, Alfons J. P.; Pol, Arjan; Jetten, Mike S. M.

    2012-01-01

    The importance of anaerobic oxidation of methane (AOM) as a methane sink in freshwater systems is largely unexplored, particularly in peat ecosystems. Nitrite-dependent anaerobic methane oxidation (n-damo) was recently discovered and reported to be catalyzed by the bacterium “Candidatus Methylomirabilis oxyfera,” which is affiliated with the NC10 phylum. So far, several “Ca. Methylomirabilis oxyfera” enrichment cultures have been obtained using a limited number of freshwater sediments or wastewater treatment sludge as the inoculum. In this study, using stable isotope measurements and porewater profiles, we investigated the potential of n-damo in a minerotrophic peatland in the south of the Netherlands that is infiltrated by nitrate-rich ground water. Methane and nitrate profiles suggested that all methane produced was oxidized before reaching the oxic layer, and NC10 bacteria could be active in the transition zone where countergradients of methane and nitrate occur. Quantitative PCR showed high NC10 bacterial cell numbers at this methane-nitrate transition zone. This soil section was used to enrich the prevalent NC10 bacteria in a continuous culture supplied with methane and nitrite at an in situ pH of 6.2. An enrichment of nitrite-reducing methanotrophic NC10 bacteria was successfully obtained. Phylogenetic analysis of retrieved 16S rRNA and pmoA genes showed that the enriched bacteria were very similar to the ones found in situ and constituted a new branch of NC10 bacteria with an identity of less than 96 and 90% to the 16S rRNA and pmoA genes of “Ca. Methylomirabilis oxyfera,” respectively. The results of this study expand our knowledge of the diversity and distribution of NC10 bacteria in the environment and highlight their potential contribution to nitrogen and methane cycles. PMID:23042166

  1. Production and consumption of nitric oxide by three methanotrophic bacteria.

    Science.gov (United States)

    Ren, T; Roy, R; Knowles, R

    2000-09-01

    We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N(2)O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 x 10(-17) mol of NO cell(-1) day(-1), mostly after a culture became O(2) limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O(2), and required CH(4). Denitrification (methanol-supported N(2)O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd(1) and Cu nitrite reductases, NO reductase, and N(2)O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O(2) and nitrate availability occur.

  2. New molecular method to detect denitrifying anaerobic methane oxidation bacteria from different environmental niches.

    Science.gov (United States)

    Xu, Sai; Lu, Wenjing; Muhammad, Farooq Mustafa; Liu, Yanting; Guo, Hanwen; Meng, Ruihong; Wang, Hongtao

    2018-03-01

    The denitrifying anaerobic methane oxidation is an ecologically important process for reducing the potential methane emission into the atmosphere. The responsible bacterium for this process was Candidatus Methylomirabilis oxyfera belonging to the bacterial phylum of NC10. In this study, a new pair of primers targeting all the five groups of NC10 bacteria was designed to amplify NC10 bacteria from different environmental niches. The results showed that the group A was the dominant NC10 phylum bacteria from the sludges and food waste digestate while in paddy soil samples, group A and group B had nearly the same proportion. Our results also indicated that NC10 bacteria could exist in a high pH environment (pH9.24) from the food waste treatment facility. The Pearson relationship analysis showed that the pH had a significant positive relationship with the NC10 bacterial diversity (pbacteria. Copyright © 2017. Published by Elsevier B.V.

  3. Assessment of nitric oxide (NO) redox reactions contribution to nitrous oxide (N2 O) formation during nitrification using a multispecies metabolic network model.

    Science.gov (United States)

    Perez-Garcia, Octavio; Chandran, Kartik; Villas-Boas, Silas G; Singhal, Naresh

    2016-05-01

    Over the coming decades nitrous oxide (N2O) is expected to become a dominant greenhouse gas and atmospheric ozone depleting substance. In wastewater treatment systems, N2O is majorly produced by nitrifying microbes through biochemical reduction of nitrite (NO2(-)) and nitric oxide (NO). However it is unknown if the amount of N2O formed is affected by alternative NO redox reactions catalyzed by oxidative nitrite oxidoreductase (NirK), cytochromes (i.e., P460 [CytP460] and 554 [Cyt554 ]) and flavohemoglobins (Hmp) in ammonia- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In this study, a mathematical model is developed to assess how N2O formation is affected by such alternative nitrogen redox transformations. The developed multispecies metabolic network model captures the nitrogen respiratory pathways inferred from genomes of eight AOB and NOB species. The performance of model variants, obtained as different combinations of active NO redox reactions, was assessed against nine experimental datasets for nitrifying cultures producing N2O at different concentration of electron donor and acceptor. Model predicted metabolic fluxes show that only variants that included NO oxidation to NO2(-) by CytP460 and Hmp in AOB gave statistically similar estimates to observed production rates of N2O, NO, NO2(-) and nitrate (NO3(-)), together with fractions of AOB and NOB species in biomass. Simulations showed that NO oxidation to NO2(-) decreased N2O formation by 60% without changing culture's NO2(-) production rate. Model variants including NO reduction to N2O by Cyt554 and cNor in NOB did not improve the accuracy of experimental datasets estimates, suggesting null N2O production by NOB during nitrification. Finally, the analysis shows that in nitrifying cultures transitioning from dissolved oxygen levels above 3.8 ± 0.38 to <1.5 ± 0.8 mg/L, NOB cells can oxidize the NO produced by AOB through reactions catalyzed by oxidative NirK. © 2015 Wiley Periodicals, Inc.

  4. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor.

    Science.gov (United States)

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-04-29

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5-1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L.

  5. Enhance wastewater biological treatment through the bacteria induced graphene oxide hydrogel.

    Science.gov (United States)

    Shen, Liang; Jin, Ziheng; Wang, Dian; Wang, Yuanpeng; Lu, Yinghua

    2018-01-01

    The interaction between bacteria and graphene-family materials like pristine graphene, graphene oxide (GO) and reduced graphene oxide (rGO) is such an elusive issue that its implication in environmental biotechnology is unclear. Herein, two kinds of self-assembled bio-rGO-hydrogels (BGHs) were prepared by cultivating specific Shewanella sp. strains with GO solution for the first time. The microscopic examination by SEM, TEM and CLSM indicated a porous 3D structure of BGHs, in which live bacteria firmly anchored and extracellular polymeric substances (EPS) abundantly distributed. Spectra of XRD, FTIR, XPS and Raman further proved that GO was reduced to rGO by bacteria along with the gelation process, which suggests a potential green technique to produce graphene. Based on the characterization results, four mechanisms for the BGH formation were proposed, i.e., stacking, bridging, rolling and cross-linking of rGO sheets, through the synergistic effect of activities and EPS from special bacteria. More importantly, the BGHs obtained in this study were found able to achieve unique cleanup performance that the counterpart free bacteria could not fulfill, as exemplified in Congo red decolorization and Cr(VI) bioreduction. These findings therefore enlighten a prospective application of graphene materials for the biological treatment of wastewaters in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Oxidative Damage Caused by Common Foodborne Pathogenic Bacteria in Egg Yolk

    Directory of Open Access Journals (Sweden)

    Reyhaneh Afshordi

    2016-02-01

    Full Text Available Background: Bacteria in foodstuff are the most important agent of foodborne disease. Aside from their infectious effects, obligate aerobes have a respiratory metabolism with oxygen as the terminal electron acceptor. Therefore, they can produce reactive oxygen species and free radicals in contaminated food. Malondialdehyde (MDA is a product of lipid peroxidation used as an indicator of oxidative stress. Objectives: This study aimed to evaluate the oxidative damage produced by two common food pathogenic bacteria in foodstuff. Materials and Methods: The egg yolks were incubated with different dilutions (105,106, and 107 of Staphylococcus aureus and Salmonella enteritidis at 37°C for 20 hours. The level of MDA in egg yolk was measured by fast and simple enzymatic or colorimetric methods, such as the thiobarbituric acid reactive species method. Results: The high group (107 had a higher MDA level of 1.97 ± 0.11 (μg MDA/g in S. aureus and 1.65 ± 0.27 (mg MDA/L in S. enteritidis than the control (0.90 ± 0.13 mg MDA/L. Conclusions: We concluded that common food pathogenic bacteria can induce oxidative damage in foodstuff aside from other common problems. Heating or sterilization methods cannot protect foodstuff from the damage caused by the presence of pathogenic bacteria.

  7. Anaerobic Oxidation of Methane Coupled to Nitrite Reduction by Halophilic Marine NC10 Bacteria.

    Science.gov (United States)

    He, Zhanfei; Geng, Sha; Cai, Chaoyang; Liu, Shuai; Liu, Yan; Pan, Yawei; Lou, Liping; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-08-15

    Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Neutrophilic Iron Oxidizing Bacteria: Occurrence and Relevance in Biological Drinking Water Treatment

    DEFF Research Database (Denmark)

    Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

    Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully......, neutrophilic iron oxidizers were present at the level of up to 7 105 cells per gram sediment. The spatial abundance and diversity of FeOB inferred by DGGE fingerprinting differed greatly both between and within individual sand filters. The results suggest a larger than assumed role of FeOB in iron removal...... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

  9. Nitrogen source effects on the denitrifying anaerobic methane oxidation culture and anaerobic ammonium oxidation bacteria enrichment process.

    Science.gov (United States)

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

    2017-05-01

    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 NO 3 - , NO 2 - , and NH 4 + 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.

  10. Pseudomonas mesophilica and an unnamed taxon, clinical isolates of pink-pigmented oxidative bacteria.

    Science.gov (United States)

    Gilardi, G L; Faur, Y C

    1984-10-01

    Twenty-one strains of pink-pigmented bacteria, isolated from human clinical specimens and an environmental source, were compared with Pseudomonas mesophilica ATCC 29983 and Protaminobacter ruber ATCC 8457. These isolates were gram-negative, oxidative rods which were motile by means of a single polar flagellum; gave positive catalase, indophenol oxidase, urease, and amylase reactions; and grew slowly at 30 degrees C. Fourteen isolates conformed to the designated type strains Pseudomonas mesophilica ATCC 29983 and Protaminobacter ruber ATCC 8457. The remaining seven strains represented an undescribed taxon. These pink bacteria appear to be invaders of debilitated patients with an underlying chronic disease.

  11. Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.

    Science.gov (United States)

    Zhang, Haiming; Yu, Xinzhi; Guo, Di; Qu, Baihua; Zhang, Ming; Li, Qiuhong; Wang, Taihong

    2013-08-14

    Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-μm structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors.

  12. Treatment of high-salinity chemical wastewater by indigenous bacteria--bioaugmented contact oxidation.

    Science.gov (United States)

    Li, Qiang; Wang, Mengdi; Feng, Jun; Zhang, Wei; Wang, Yuanyuan; Gu, Yanyan; Song, Cunjiang; Wang, Shufang

    2013-09-01

    A 90 m(3) biological contact oxidation system in chemical factory was bioaugmented with three strains of indigenous salt-tolerant bacteria. These three strains were screened from contaminative soil in situ. Their activity of growth and degradation was investigated with lab-scale experiments. Their salt-tolerant mechanism was confirmed to be compatible-solutes strategy for moderately halophilic bacteria, with amino acid and betaine playing important roles. The running conditions of the system were recorded for 150 days. The indigenous bacteria had such high suitability that the reactor got steady rapidly and the removal of COD maintained above 90%. It was introduced that biofilm fragments in sedimentation tank were inversely flowed to each reaction tank, and quantitative PCR demonstrated that this process could successfully maintain the bacterial abundance in the reaction tanks. In addition, the T-RFLP revealed that bioaugmented strains dominated over others in the biofilm. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Fossilization of Iron-Oxidizing Bacteria at Hydrothermal Vents: a Useful Biosignature on Mars?

    Science.gov (United States)

    Leveille, R. J.; Lui, S.

    2009-05-01

    Iron oxidizing bacteria are ubiquitous in marine and terrestrial environments on Earth, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Putative microfossils of iron oxidizing bacteria have been found in jaspers as old as 490Ma and microbial iron oxidation may be an ancient metabolic pathway. In order to investigate the usefulness of mineralized iron oxidizing bacteria as a biosignature, we have examined mineral samples collected from relict hydrothermal systems along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic, neutrophilic iron oxidizing bacteria, isolated from Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and oxygen concentration (5 percent) in a controlled bioreactor system. Both natural samples and experimental products were examined with a combination of variable pressure scanning electron microscopy (SEM), field emission gun SEM, and in some cases by preparing samples with a focused ion beam (FIB) milling system. Natural seafloor samples display abundant filamentous forms often resembling, in both size and shape, the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Generally, these filamentous features are 1-5 microns in diameter and up to several microns in length. Some samples consist entirely of low- density, porous masses of silica encrusted filamentous forms. Presumably, these masses were formed by a rapid precipitation by the influx of silica-rich fluids into a microbial mat dominated by bacteria with filamentous morphologies. The presence of rare, amorphous (unmineralized) filamentous matter rich in C and Fe suggests that these bacteria were iron oxidizers. There is no evidence that sulfur oxidizers were present. Filamentous features sectioned by FIB milling show internal material within semi-hollow tubular-like features. Silica encrustations also show pseudo

  14. A mathematical model of bacteria capable of complete oxidation of ammonium predicts improved nitrogen removal and reduced production of nitrous oxide

    OpenAIRE

    Pokhilko, Alexandra; Ebenhöh, Oliver

    2017-01-01

    The removal of excess nutrients\\ud from water ecosystems requires oxidation of toxic\\ud ammonium by two types of bacteria; one oxidizes\\ud ammonium to nitrite and the other oxidizes nitrite\\ud to nitrate. The oxidation of ammonium is often\\ud incomplete and nitrite accumulates. Nitrite is also\\ud toxic, and is converted by the ammoniumoxidizing\\ud bacteria to nitrous oxide, a powerful\\ud greenhouse gas. Here we use mathematical\\ud modeling to analyze a potential solution to the\\ud problems re...

  15. Prevention by lactic acid bacteria of the oxidation of human LDL.

    Science.gov (United States)

    Terahara, M; Kurama, S; Takemoto, N

    2001-08-01

    Ether extracts of lactic acid bacteria were analyzed for prevention of the oxidation of erythrocyte membrane and human low-density lipoprotein in vivo. Streptococcus thermophilus 1131 and Lactobacillus delbrueckii subsp. bulgaricus 2038, yogurt starters, were chosen as test-strains, and ether extracts of these cultures were used as samples. Both strain 1131 and strain 2038 produced radical scavengers and inhibited oxidation of erythrocyte membranes and low-density lipoproteins. The antioxidative activity of strain 2038 was higher than that of strain 1131.

  16. Bacteria dominate ammonia oxidation in soils used for outdoor cattle overwintering

    Czech Academy of Sciences Publication Activity Database

    Radl, V.; Chroňáková, Alica; Čuhel, Jiří; Šimek, Miloslav; Elhottová, Dana; Welzl, G.; Schloter, M.

    2014-01-01

    Roč. 77, May (2014), s. 68-71 ISSN 0929-1393 R&D Projects: GA MŠk LC06066 Grant - others:Akademie věd ČR(CZ) D-CZ 45:05/06 Institutional support: RVO:60077344 Keywords : ammonia oxidation * bacteria * archaea * amoA diversity * urea * pasture Subject RIV: EH - Ecology, Behaviour Impact factor: 2.644, year: 2014

  17. Pseudomonas mesophilica and an unnamed taxon, clinical isolates of pink-pigmented oxidative bacteria.

    OpenAIRE

    Gilardi, G L; Faur, Y C

    1984-01-01

    Twenty-one strains of pink-pigmented bacteria, isolated from human clinical specimens and an environmental source, were compared with Pseudomonas mesophilica ATCC 29983 and Protaminobacter ruber ATCC 8457. These isolates were gram-negative, oxidative rods which were motile by means of a single polar flagellum; gave positive catalase, indophenol oxidase, urease, and amylase reactions; and grew slowly at 30 degrees C. Fourteen isolates conformed to the designated type strains Pseudomonas mesoph...

  18. Development of hydrogen oxidizing bacteria using hydrogen from radiolysis or metal corrosion

    International Nuclear Information System (INIS)

    Libert, M.F.; Sellier, R.; Marty, V.; Camaro, S.

    2000-01-01

    The effect of many parameters need to be studied to characterize the long term behavior of nuclear waste in a deep repository. These parameters concern the chemical effects, radiolytic effects, mechanical properties, water composition, and microbiological activity. To evaluate microbial activity in such an environment, work was focused on an inventory of key nutrients (C, H, 0, N, P, S) and energy sources required for bacterial growth. The production of hydrogen in the nuclear waste environment leads to the growth of hydrogen oxidizing bacteria, which modify the gas production balance. A deep repository containing bituminized waste drums implies several sources of hydrogen: - water radiolysis; -corrosion of metal containers; - radiolysis of the embedding matrix (bitumen). Two deep geological disposal conditions leading to H 2 production in a bituminized nuclear waste environment were simulated in the present study: - H 2 production by iron corrosion under anaerobic conditions was simulated by adding 10% of H 2 in the atmosphere; - H 2 production by radiolysis of bitumen matrix was approached by subjecting this material to external gamma irradiation with a dose rate near real conditions (6 Gy/h). The presence of dissolved H 2 in water allows the growth of hydrogen oxidizing bacteria leading to: - CO 2 and N 2 production; - H 2 consumption; - lower NO 3 - concentration caused by reduction to nitrogen. In the first case, hydrogen consumption is limited by the NO 3 - release rate from the bitumen matrix. In the second case, however, under gamma radiation at a low dose rate, hydrogen production is weak, and the hydrogen is completely consumed by microorganisms. Knowledge about these hydrogen oxidizing bacteria is just beginning to emerge. Heterotrophic denitrifying bacteria adapt well to hydrogen metabolism (autotrophic metabolism) by oxidizing H 2 instead of hydrocarbons. (authors)

  19. Life on the energetic edge: Iron oxidation by circumneutral lithotrophic bacteria in the wetland plant rhizosphere

    Science.gov (United States)

    Neubauer, S. C.; Emerson, D.; Megonigal, J. P.; Weiss, J. V.

    2002-05-01

    We have discovered a phylogenetically and genotypically coherent group of obligately lithotrophic Fe-oxidizing bacteria that grow at neutral pH and are globally distributed in a range of habitats, from the rhizosphere of freshwater wetlands to deep-sea hydrothermal vents. We have initiated bioreactor studies using pure cultures of these organisms to determine the significance of microbial Fe(II) oxidation at circumneutral pH and identify the biotic and abiotic variables that affect the partitioning between microbial and chemical oxidation. These studies have focused on strain BrT, which was isolated from an iron oxide precipitate in rhizosphere of a wetland plant. In one set of experiments, Fe(II) oxidation rates were measured before and after cultures of strain BrT were poisoned with sodium azide. These experiments indicated that 18 to 53 % of total iron oxidation was due to microbial metabolism. In a second set of experiments, Fe(II) was constantly added to bioreactors inoculated with live cells, killed cells, or no cells. A statistical model fit to the experimental data demonstrated that metabolic Fe(II) oxidation accounted for up to 62 % of total oxidation. Total Fe(II) oxidation rates in these experiments were strongly limited by the rate of Fe(II) delivery to the system, and were also influenced by O2 and total iron concentrations. Additionally, the model suggested that the microbes inhibited rates of abiotic Fe(II) oxidation, perhaps by binding Fe(II) to bacterial exopolymers. The net effect of strain BrT was to accelerate total oxidation rates by up to 18 % versus cell-free treatments. Using two independent techniques, we demonstrated that strain BrT actively metabolizes Fe(II) and can account for up to 50 to 60 % of total Fe(II) oxidation in laboratory cultures. These results suggest that neutrophilic Fe(II)-oxidizing bacteria may compete for limited O2 in the rhizosphere and influence the biogeochemistry of other elements including carbon, phosphorus, and

  20. Transformation of vivianite by anaerobic nitrate-reducing iron-oxidizing bacteria.

    Science.gov (United States)

    Miot, J; Benzerara, K; Morin, G; Bernard, S; Beyssac, O; Larquet, E; Kappler, A; Guyot, F

    2009-06-01

    In phosphate-rich environments, vivianite (Fe(II)(3)(PO(4))(2), 8H(2)O) is an important sink for dissolved Fe(II) and is considered as a very stable mineral due to its low solubility at neutral pH. In the present study, we report the mineralogical transformation of vivianite in cultures of the nitrate-reducing iron-oxidizing bacterial strain BoFeN1 in the presence of dissolved Fe(II). Vivianite was first transformed into a greenish phase consisting mostly of an amorphous mixed valence Fe-phosphate. This precipitate became progressively orange and the final product of iron oxidation consisted of an amorphous Fe(III)-phosphate. The sub-micrometer analysis by scanning transmission X-ray microscopy of the iron redox state in samples collected at different stages of the culture indicated that iron was progressively oxidized at the contact of the bacteria and at a distance from the cells in extracellular minerals. Iron oxidation in the extracellular minerals was delayed by a few days compared with cell-associated Fe-minerals. This led to strong differences of Fe redox in between these two types of minerals and finally to local heterogeneities of redox within the sample. In the absence of dissolved Fe(II), vivianite was not significantly transformed by BoFeN1. Whereas Fe(II) oxidation at the cell contact is most probably directly catalyzed by the bacteria, vivianite transformation at a distance from the cells might result from oxidation by nitrite. In addition, processes leading to the export of Fe(III) from bacterial oxidation sites to extracellular minerals are discussed including some involving colloids observed by cryo-transmission electron microscopy in the culture medium.

  1. Identification of Antimony- and Arsenic-Oxidizing Bacteria Associated with Antimony Mine Tailing

    Science.gov (United States)

    Hamamura, Natsuko; Fukushima, Koh; Itai, Takaaki

    2013-01-01

    Antimony (Sb) is a naturally occurring toxic element commonly associated with arsenic (As) in the environment and both elements have similar chemistry and toxicity. Increasing numbers of studies have focused on microbial As transformations, while microbial Sb interactions are still not well understood. To gain insight into microbial roles in the geochemical cycling of Sb and As, soils from Sb mine tailing were examined for the presence of Sb- and As-oxidizing bacteria. After aerobic enrichment culturing with AsIII (10 mM) or SbIII (100 μM), pure cultures of Pseudomonas- and Stenotrophomonas-related isolates with SbIII oxidation activities and a Sinorhizobium-related isolate capable of AsIII oxidation were obtained. The AsIII-oxidizing Sinorhizobium isolate possessed the aerobic arsenite oxidase gene (aioA), the expression of which was induced in the presence of AsIII or SbIII. However, no SbIII oxidation activity was detected from the Sinorhizobium-related isolate, suggesting the involvement of different mechanisms for Sb and As oxidation. These results demonstrate that indigenous microorganisms associated with Sb mine soils are capable of Sb and As oxidation, and potentially contribute to the speciation and mobility of Sb and As in situ. PMID:23666539

  2. Full-Scale Modeling Explaining Large Spatial Variations of Nitrous Oxide Fluxes in a Step-Feed Plug-Flow Wastewater Treatment Reactor.

    Science.gov (United States)

    Ni, Bing-Jie; Pan, Yuting; van den Akker, Ben; Ye, Liu; Yuan, Zhiguo

    2015-08-04

    Nitrous oxide (N2O) emission data collected from wastewater treatment plants (WWTPs) show huge variations between plants and within one plant (both spatially and temporarily). Such variations and the relative contributions of various N2O production pathways are not fully understood. This study applied a previously established N2O model incorporating two currently known N2O production pathways by ammonia-oxidizing bacteria (AOB) (namely the AOB denitrification and the hydroxylamine pathways) and the N2O production pathway by heterotrophic denitrifiers to describe and provide insights into the large spatial variations of N2O fluxes in a step-feed full-scale activated sludge plant. The model was calibrated and validated by comparing simulation results with 40 days of N2O emission monitoring data as well as other water quality parameters from the plant. The model demonstrated that the relatively high biomass specific nitrogen loading rate in the Second Step of the reactor was responsible for the much higher N2O fluxes from this section. The results further revealed the AOB denitrification pathway decreased and the NH2OH oxidation pathway increased along the path of both Steps due to the increasing dissolved oxygen concentration. The overall N2O emission from this step-feed WWTP would be largely mitigated if 30% of the returned sludge were returned to the Second Step to reduce its biomass nitrogen loading rate.

  3. The Bacterial Communities of Full-Scale Biologically Active, Granular Activated Carbon Filters Are Stable and Diverse and Potentially Contain Novel Ammonia-Oxidizing Microorganisms

    Science.gov (United States)

    Hope Wilkinson, Katheryn; Strait, Jacqueline M.; Hozalski, Raymond M.; Sadowksy, Michael J.; Hamilton, Matthew J.

    2015-01-01

    The bacterial community composition of the full-scale biologically active, granular activated carbon (BAC) filters operated at the St. Paul Regional Water Services (SPRWS) was investigated using Illumina MiSeq analysis of PCR-amplified 16S rRNA gene fragments. These bacterial communities were consistently diverse (Shannon index, >4.4; richness estimates, >1,500 unique operational taxonomic units [OTUs]) throughout the duration of the 12-month study period. In addition, only modest shifts in the quantities of individual bacterial populations were observed; of the 15 most prominent OTUs, the most highly variable population (a Variovorax sp.) modulated less than 13-fold over time and less than 8-fold from filter to filter. The most prominent population in the profiles was a Nitrospira sp., representing 13 to 21% of the community. Interestingly, very few of the known ammonia-oxidizing bacteria (AOB; <0.07%) and no ammonia-oxidizing Archaea were detected in the profiles. Quantitative PCR of amoA genes, however, suggested that AOB were prominent in the bacterial communities (amoA/16S rRNA gene ratio, 1 to 10%). We conclude, therefore, that the BAC filters at the SPRWS potentially contained significant numbers of unidentified and novel ammonia-oxidizing microorganisms that possess amoA genes similar to those of previously described AOB. PMID:26209671

  4. Changes in N-transforming archaea and bacteria in soil during the establishment of bioenergy crops.

    Directory of Open Access Journals (Sweden)

    Yuejian Mao

    Full Text Available Widespread adaptation of biomass production for bioenergy may influence important biogeochemical functions in the landscape, which are mainly carried out by soil microbes. Here we explore the impact of four potential bioenergy feedstock crops (maize, switchgrass, Miscanthus X giganteus, and mixed tallgrass prairie on nitrogen cycling microorganisms in the soil by monitoring the changes in the quantity (real-time PCR and diversity (barcoded pyrosequencing of key functional genes (nifH, bacterial/archaeal amoA and nosZ and 16S rRNA genes over two years after bioenergy crop establishment. The quantities of these N-cycling genes were relatively stable in all four crops, except maize (the only fertilized crop, in which the population size of AOB doubled in less than 3 months. The nitrification rate was significantly correlated with the quantity of ammonia-oxidizing archaea (AOA not bacteria (AOB, indicating that archaea were the major ammonia oxidizers. Deep sequencing revealed high diversity of nifH, archaeal amoA, bacterial amoA, nosZ and 16S rRNA genes, with 229, 309, 330, 331 and 8989 OTUs observed, respectively. Rarefaction analysis revealed the diversity of archaeal amoA in maize markedly decreased in the second year. Ordination analysis of T-RFLP and pyrosequencing results showed that the N-transforming microbial community structures in the soil under these crops gradually differentiated. Thus far, our two-year study has shown that specific N-transforming microbial communities develop in the soil in response to planting different bioenergy crops, and each functional group responded in a different way. Our results also suggest that cultivation of maize with N-fertilization increases the abundance of AOB and denitrifiers, reduces the diversity of AOA, and results in significant changes in the structure of denitrification community.

  5. Controls of nitrite oxidation in ammonia-removing biological air filters

    DEFF Research Database (Denmark)

    Juhler, Susanne; Ottosen, Lars Ditlev Mørck; Nielsen, Lars Peter

    2008-01-01

    in accumulation of nitrate rather than nitrite and a significant decline in pH. As a consequence, ammonia is removed more efficiently, but heterotrophic oxidation of odorous compounds might be inhibited.  To identify the controlling mechanisms of nitrite oxidation, full-scale biological air filters were...... activity resulting in a lowered pH and thus a decreased FA concentration, promoting further growth of NOB. Yet, in some cases a situation with a nitrate-to-nitrite ratio of 1 and moderate pH remained stable even under varying air load and water supply, suggesting that additional mechanisms were involved......In biological air filters ammonia is removed due to the action of Ammonia Oxidizing Bacteria (AOB) resulting in nitrite accumulation exceeding 100 mM. Among filters treating exhaust air from pig facilities successful establishment of Nitrite Oxidizing Bacteria (NOB) sometimes occurs, resulting...

  6. Arsenite-oxidizing and arsenate-reducing bacteria associated with arsenic-rich groundwater in Taiwan

    Science.gov (United States)

    Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Hsiao, Sung-Yun; Wei, Chia-Cheng; Liu, Chen-Wuing; Liao, Chung-Min; Shen, Wei-Chiang; Chang, Fi-John

    2011-04-01

    Drinking highly arsenic-contaminated groundwater is a likely cause of blackfoot disease in Taiwan, but microorganisms that potentially control arsenic mobility in the subsurface remain unstudied. The objective of this study was to investigate the relevant arsenite-oxidizing and arsenate-reducing microbial community that exists in highly arsenic-contaminated groundwater in Taiwan. We cultured and identified arsenic-transforming bacteria, analyzed arsenic resistance and transformation, and determined the presence of genetic markers for arsenic transformation. In total, 11 arsenic-transforming bacterial strains with different colony morphologies and varying arsenic transformation abilities were isolated, including 10 facultative anaerobic arsenate-reducing bacteria and one strictly aerobic arsenite-oxidizing bacterium. All of the isolates exhibited high levels of arsenic resistance with minimum inhibitory concentrations of arsenic ranging from 2 to 200 mM. Strain AR-11 was able to rapidly oxidize arsenite to arsenate at concentrations relevant to environmental groundwater samples without the addition of any electron donors or acceptors. We provide evidence that arsenic-reduction activity may be conferred by the ars operon(s) that were not amplified by the designed primers currently in use. The 16S rRNA sequence analysis grouped the isolates into the following genera: Pseudomonas, Bacillus, Psychrobacter, Vibrio, Citrobacter, Enterobacter, and Bosea. Among these genera, we present the first report of the genus Psychrobacter being involved in arsenic reduction. Our results further support the hypothesis that bacteria capable of either oxidizing arsenite or reducing arsenate coexist and are ubiquitous in arsenic-contaminated groundwater.

  7. Advances in methods for detection of anaerobic ammonium oxidizing (anammox) bacteria.

    Science.gov (United States)

    Li, Meng; Gu, Ji-Dong

    2011-05-01

    Anaerobic ammonium oxidation (anammox), the biochemical process oxidizing ammonium into dinitrogen gas using nitrite as an electron acceptor, has only been recognized for its significant role in the global nitrogen cycle not long ago, and its ubiquitous distribution in a wide range of environments has changed our knowledge about the contributors to the global nitrogen cycle. Currently, several groups of methods are used in detection of anammox bacteria based on their physiological and biochemical characteristics, cellular chemical composition, and both 16S rRNA gene and selective functional genes as biomarkers, including hydrazine oxidoreductase and nitrite reductase encoding genes hzo and nirS, respectively. Results from these methods coupling with advances in quantitative PCR, reverse transcription of mRNA genes and stable isotope labeling have improved our understanding on the distribution, diversity, and activity of anammox bacteria in different environments both natural and engineered ones. In this review, we summarize these methods used in detection of anammox bacteria from various environments, highlight the strengths and weakness of these methods, and also discuss the new development potentials on the existing and new techniques in the future.

  8. Aerobic nitrous oxide production through N-nitrosating hybrid formation in ammonia-oxidizing archaea.

    Science.gov (United States)

    Stieglmeier, Michaela; Mooshammer, Maria; Kitzler, Barbara; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Richter, Andreas; Schleper, Christa

    2014-05-01

    Soil emissions are largely responsible for the increase of the potent greenhouse gas nitrous oxide (N2O) in the atmosphere and are generally attributed to the activity of nitrifying and denitrifying bacteria. However, the contribution of the recently discovered ammonia-oxidizing archaea (AOA) to N2O production from soil is unclear as is the mechanism by which they produce it. Here we investigate the potential of Nitrososphaera viennensis, the first pure culture of AOA from soil, to produce N2O and compare its activity with that of a marine AOA and an ammonia-oxidizing bacterium (AOB) from soil. N. viennensis produced N2O at a maximum yield of 0.09% N2O per molecule of nitrite under oxic growth conditions. N2O production rates of 4.6±0.6 amol N2O cell(-1) h(-1) and nitrification rates of 2.6±0.5 fmol NO2(-) cell(-1) h(-1) were in the same range as those of the AOB Nitrosospira multiformis and the marine AOA Nitrosopumilus maritimus grown under comparable conditions. In contrast to AOB, however, N2O production of the two archaeal strains did not increase when the oxygen concentration was reduced, suggesting that they are not capable of denitrification. In (15)N-labeling experiments we provide evidence that both ammonium and nitrite contribute equally via hybrid N2O formation to the N2O produced by N. viennensis under all conditions tested. Our results suggest that archaea may contribute to N2O production in terrestrial ecosystems, however, they are not capable of nitrifier-denitrification and thus do not produce increasing amounts of the greenhouse gas when oxygen becomes limiting.

  9. Quantification of syntrophic fatty acid-beta-oxidizing bacteria in a mesophilic biogas reactor by oligonucleotide probe hybridization

    DEFF Research Database (Denmark)

    Hansen, K.W.; Ahring, Birgitte Kiær; Raskin, L.

    1999-01-01

    Small-subunit rRNA sequences were obtained for two saturated fatty acid-beta-oxidizing syntrophic bacteria, Syntrophomonas sapovorans and Syntrophomonas wolfei LYE, and sequence analysis confirmed their classification as members of the family Syntrophomonadaceae. S, wolfei LYE was closely related...... fatty acid-beta-oxidizing syntrophic bacteria in methanogenic environments, the microbial community structure of a sample from a full-scale biogas plant was determined. Hybridization results with probes for syntrophic bacteria-and methanogens were compared to specific methanogenic activities...

  10. Ammonia-oxidizing Bacteria and Archaea in the Rhizosphere of Freshwater Macrophytes

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2007-01-01

    AMMONIA-OXIDIZING ARCHAEA AND BACTERIA IN THE RHIZOSPHERE OF FRESHWATER MACROPHYTES Martina Herrmann and Andreas Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Denmark Aquatic macrophytes such as Littorella uniflora and Lobelia dortmanna release oxygen from...... their roots and thereby stimulate nitrification and coupled nitrification-denitrification in their rhizosphere. However, oxygen release and inorganic nitrogen concentrations differ markedly between macrophyte species. We therefore propose (i) that the rhizosphere of freshwater macrophytes harbours a species......-specific microbial community distinct from that of unvegetated sediment and (ii) that aquatic macrophytes have an impact on abundance and activity of nitrifying and denitrifying bacteria in freshwater sediment. The goal of this study was to test these hypotheses for the key functional group for coupled nitrification...

  11. Identification and characterization of epoxide hydrolase activity of polycyclic aromatic hydrocarbon-degrading bacteria for biocatalytic resolution of racemic styrene oxide and styrene oxide derivatives.

    Science.gov (United States)

    Woo, Jung-Hee; Kwon, Tae-Hyung; Kim, Jun-Tae; Kim, Choong-Gon; Lee, Eun Yeol

    2013-04-01

    A novel epoxide hydrolase (EHase) from polycyclic aromatic hydrocarbon (PAH)-degrading bacteria was identified and characterized. EHase activity was identified in four strains of PAH-degrading bacteria isolated from commercial gasoline and oil-contaminated sediment based on their growth on styrene oxide and its derivatives, such as 2,3- and 4-chlorostyrene oxides, as a sole carbon source. Gordonia sp. H37 exhibited high enantioselective hydrolysis activity for 4-chlorostyrene oxide with an enantiomeric ratio of 27. Gordonia sp. H37 preferentially hydrolyzed the (R)-enantiomer of styrene oxide derivatives resulting in the preparation of a (S)-enantiomer with enantiomeric excess greater than 99.9 %. The enantioselective EHase activity was identified and characterized in various PAH-degrading bacteria, and whole cell Gordonia sp. H37 was employed as a biocatalyst for preparing enantiopure (S)-styrene oxide derivatives.

  12. Population structure of manganese-oxidizing bacteria in stratified soils and properties of manganese oxide aggregates under manganese-complex medium enrichment.

    Directory of Open Access Journals (Sweden)

    Weihong Yang

    Full Text Available Manganese-oxidizing bacteria in the aquatic environment have been comprehensively investigated. However, little information is available about the distribution and biogeochemical significance of these bacteria in terrestrial soil environments. In this study, stratified soils were initially examined to investigate the community structure and diversity of manganese-oxidizing bacteria. Total 344 culturable bacterial isolates from all substrata exhibited Mn(II-oxidizing activities at the range of 1 µM to 240 µM of the equivalent MnO2. The high Mn(II-oxidizing isolates (>50 mM MnO2 were identified as the species of phyla Actinobacteria, Firmicutes and Proteobacteria. Seven novel Mn(II-oxidizing bacterial genera (species, namely, Escherichia, Agromyces, Cellulomonas, Cupriavidus, Microbacterium, Ralstonia, and Variovorax, were revealed via comparative phylogenetic analysis. Moreover, an increase in the diversity of soil bacterial community was observed after the combined enrichment of Mn(II and carbon-rich complex. The phylogenetic classification of the enriched bacteria represented by predominant denaturing gradient gel electrophoresis bands, was apparently similar to culturable Mn(II-oxidizing bacteria. The experiments were further undertaken to investigate the properties of the Mn oxide aggregates formed by the bacterial isolates with high Mn(II-oxidizing activity. Results showed that these bacteria were closely encrusted with their Mn oxides and formed regular microspherical aggregates under prolonged Mn(II and carbon-rich medium enrichment for three weeks. The biotic oxidation of Mn(II to Mn(III/IV by these isolates was confirmed by kinetic examinations. X-ray diffraction assays showed the characteristic peaks of several Mn oxides and rhodochrosite from these aggregates. Leucoberbelin blue tests also verified the Mn(II-oxidizing activity of these aggregates. These results demonstrated that Mn oxides were formed at certain amounts under the

  13. Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

    Science.gov (United States)

    Nowka, Boris; Daims, Holger

    2014-01-01

    Nitrification has an immense impact on nitrogen cycling in natural ecosystems and in wastewater treatment plants. Mathematical models function as tools to capture the complexity of these biological systems, but kinetic parameters especially of nitrite-oxidizing bacteria (NOB) are lacking because of a limited number of pure cultures until recently. In this study, we compared the nitrite oxidation kinetics of six pure cultures and one enrichment culture representing three genera of NOB (Nitrobacter, Nitrospira, Nitrotoga). With half-saturation constants (Km) between 9 and 27 μM nitrite, Nitrospira bacteria are adapted to live under significant substrate limitation. Nitrobacter showed a wide range of lower substrate affinities, with Km values between 49 and 544 μM nitrite. However, the advantage of Nitrobacter emerged under excess nitrite supply, sustaining high maximum specific activities (Vmax) of 64 to 164 μmol nitrite/mg protein/h, contrary to the lower activities of Nitrospira of 18 to 48 μmol nitrite/mg protein/h. The Vmax (26 μmol nitrite/mg protein/h) and Km (58 μM nitrite) of “Candidatus Nitrotoga arctica” measured at a low temperature of 17°C suggest that Nitrotoga can advantageously compete with other NOB, especially in cold habitats. The kinetic parameters determined represent improved basis values for nitrifying models and will support predictions of community structure and nitrification rates in natural and engineered ecosystems. PMID:25398863

  14. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Directory of Open Access Journals (Sweden)

    Mauro Tiso

    Full Text Available The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in

  15. Nitrate Reduction to Nitrite, Nitric Oxide and Ammonia by Gut Bacteria under Physiological Conditions

    Science.gov (United States)

    Tiso, Mauro; Schechter, Alan N.

    2015-01-01

    The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome

  16. Molecular detection of anaerobic ammonium-oxidizing (anammox) bacteria in high-temperature petroleum reservoirs.

    Science.gov (United States)

    Li, Hui; Chen, Shuo; Mu, Bo-Zhong; Gu, Ji-Dong

    2010-11-01

    Anaerobic ammonium-oxidizing (anammox) process plays an important role in the nitrogen cycle of the worldwide anoxic and mesophilic habitats. Recently, the existence and activity of anammox bacteria have been detected in some thermophilic environments, but their existence in the geothermal subterranean oil reservoirs is still not reported. This study investigated the abundance, distribution and functional diversity of anammox bacteria in nine out of 17 high-temperature oil reservoirs by molecular ecology analysis. High concentration (5.31-39.2 mg l(-1)) of ammonium was detected in the production water from these oilfields with temperatures between 55°C and 75°C. Both 16S rRNA and hzo molecular biomarkers indicated the occurrence of anammox bacteria in nine out of 17 samples. Most of 16S rRNA gene phylotypes are closely related to the known anammox bacterial genera Candidatus Brocadia, Candidatus Kuenenia, Candidatus Scalindua, and Candidatus Jettenia, while hzo gene phylotypes are closely related to the genera Candidatus Anammoxoglobus, Candidatus Kuenenia, Candidatus Scalindua, and Candidatus Jettenia. The total bacterial and anammox bacterial densities were 6.4 ± 0.5 × 10(3) to 2.0 ± 0.18 × 10(6) cells ml(-1) and 6.6 ± 0.51 × 10(2) to 4.9 ± 0.36 × 10(4) cell ml(-1), respectively. The cluster I of 16S rRNA gene sequences showed distant identity (<92%) to the known Candidatus Scalindua species, inferring this cluster of anammox bacteria to be a new species, and a tentative name Candidatus "Scalindua sinooilfield" was proposed. The results extended the existence of anammox bacteria to the high-temperature oil reservoirs.

  17. Impact of chemical oxidation on indigenous bacteria and mobilization of nutrients and subsequent bioremediation of crude oil-contaminated soil.

    Science.gov (United States)

    Xu, Jinlan; Deng, Xin; Cui, Yiwei; Kong, Fanxing

    2016-12-15

    Fenton pre-oxidation provides nutrients to promote bioremediation. However, the effects of the indigenous bacteria that remain following Fenton oxidation on nutrient mobilization and subsequent bioremediation remain unclear. Experiments were performed with inoculation with native bacteria and foreign bacteria or without inoculation after four regimens of stepwise pre-oxidations. The effects of the indigenous bacteria remaining after stepwise oxidation on nutrient mobilization and subsequent bioremediation over 80 days were investigated. After stepwise Fenton pre-oxidation at a low H 2 O 2 concentration (225×4), the remaining indigenous bacterial populations reached their peak (4.8±0.17×10 6 CFU/g), the nutrients were mobilized rapidly, and the subsequent bioremediation of crude oil was improved (biodegradation efficiency of 35%). However, after stepwise Fenton pre-oxidation at a high H 2 O 2 concentration (450×4), only 3.6±0.16×10 3 CFU/g of indigenous bacteria remained, and the indigenous bacteria that degrade C 15 -C 30 alkanes were inhibited. The nutrient mobilization was then highly limited, and only 19% of total petroleum hydrocarbon was degraded. Furthermore, the recovery period after the low H 2 O 2 concentration stepwise Fenton pre-oxidation (225×4) was less than 20 days, which was 20-30 days shorter than with the other pre-oxidation treatments. Therefore, stepwise Fenton pre-oxidation at a low H 2 O 2 concentration protects indigenous bacterial populations and improves the nutrient mobilization and subsequent bioremediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Evaluating primers for profiling anaerobic ammonia oxidizing bacteria within freshwater environments.

    Directory of Open Access Journals (Sweden)

    Puntipar Sonthiphand

    Full Text Available Anaerobic ammonia oxidizing (anammox bacteria play an important role in transforming ammonium to nitrogen gas and contribute to fixed nitrogen losses in freshwater environments. Understanding the diversity and abundance of anammox bacteria requires reliable molecular tools, and these are not yet well established for these important Planctomycetes. To help validate PCR primers for the detection of anammox bacteria within freshwater ecosystems, we analyzed representative positive controls and selected samples from Grand River and groundwater sites, both from Ontario, Canada. The objectives of this study were to identify a suitable anammox denaturing gradient gel electrophoresis (DGGE fingerprint method by using GC-clamp modifications to existing primers, and to verify the specificity of anammox-specific primers used for DGGE, cloning and qPCR methods. Six primer combinations were tested from four published primer sets (i.e. A438f/A684r, Amx368f/Amx820r, An7f/An1388r, and Pla46/1392r for both direct and nested PCR amplifications. All PCR products were run subsequently on DGGE gels to compare the resulting patterns. Two anammox-specific primer combinations were also used to generate clone libraries and quantify anammox bacterial 16S rRNA genes with qPCR. The primer set A438f/A684r was highly specific to anammox bacteria, provided reliable DGGE fingerprints and generated a high proportion of anammox-related clones. A second primer set (Amx368f/Amx820r was anammox specific, based on clone library analysis, but PCR products from different candidate species of anammox bacteria resolved poorly using DGGE analysis. Both DGGE and cloning results revealed that Ca. Brocadia and an uncharacterized anammox bacterial cluster represented the majority of anammox bacteria found in Grand River sediment and groundwater samples, respectively. Together, our results demonstrate that although Amx368f/Amx820r was useful for anammox-specific qPCR and clone library

  19. Linking Mn(II)-oxidizing bacteria to natural attenuation at a former U mining site

    Science.gov (United States)

    Akob, D.; Bohu, T.; Beyer, A.; Schäffner, F.; Händel, M.; Johnson, C.; Merten, D.; Büchel, G.; Totsche, K.; Küsel, K.

    2012-04-01

    Uranium mining near Ronneburg, Germany resulted in widespread environmental contamination with acid mine drainage (AMD) and high concentrations of heavy metals and radionuclides. Despite physical remediation of the area, groundwater is still a source of heavy metal contaminants, e.g., Cd, Ni, Co, Cu and Zn, to nearby ecosystems. However, natural attenuation of heavy metals is occurring in Mn oxide rich soils and sediments ranging in pH from 5 to 7. While microorganisms readily oxidize Mn(II) and precipitate Mn oxides at pH ~7 under oxic conditions, few studies describe Mn(II)-oxidizing bacteria (MOB) at pH ~5 and/or in the presence of heavy metals. In this study we (1) isolated MOB from the contaminated Ronneburg area at pH 5.5 and 7 and (2) evaluated the biological formation of Mn oxides. We isolated nine MOB strains at pH 7 (members of the Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes phyla) and a single isolate at pH 5.5 (Oxalobacteraceae isolate AB_14, within the β-Proteobacteria). LA-ICP-MS showed that all isolates accumulated Mn and Fe in their biomass. However, the Oxalobacteraceae isolate AB_14 oxidizes more Mn without additional Fe in the medium. Preliminary FTIR analysis indicated that all isolates formed precipitates, which showed absorption bands that were characteristic for birnessite. High resolution TEM showed variable morphology of precipitates and EDS confirmed the presence of Mn oxides. Isolate AB_14 was not surrounded with precipitates whereas our Actinobacteria isolate AB_18 was encrusted with Mn oxides. Electron diffraction is currently being used to confirm the presence of birnessite and other Mn oxide phases. This, the first known report of any organism capable of Mn oxidation at low pH, demonstrated that MOB can be involved in the natural attenuation of both moderately acidic and neutral pH soils and sediments via the formation of biogenic Mn oxides. Future work will fully evaluate the minerals formed in this process as well

  20. Spatial distribution of archaeal and bacterial ammonia oxidizers in the littoral buffer zone of a nitrogen-rich lake.

    Science.gov (United States)

    Wang, Yu; Zhu, Guibing; Ye, Lei; Feng, Xiaojuan; Op den Camp, Huub J M; Yin, Chengqing

    2012-01-01

    The spatial distribution and diversity of archaeal and bacterial ammonia oxidizers (AOA and AOB) were evaluated targeting amoA genes in the gradient of a littoral buffer zone which has been identified as a hot spot for N cycling. Here we found high spatial heterogeneity in the nitrification rate and abundance of ammonia oxidizers in the five sampling sites. The bacterial amoA gene was numerically dominant in most of the surface soil but decreased dramatically in deep layers. Higher nitrification potentials were detected in two sites near the land/water interface at 4.4-6.1 microg NO(2-)-N/(g dry weight soil x hr), while only 1.0-1.7 microg NO(2-)-N/(g dry weight soil x hr) was measured at other sites. The potential nitrification rates were proportional to the amoA gene abundance for AOB, but with no significant correlation with AOA. The NH4+ concentration was the most determinative parameter for the abundance of AOB and potential nitrification rates in this study. Higher richness in the surface layer was found in the analysis of biodiversity. Phylogenetic analysis revealed that most of the bacterial amoA sequences in surface soil were affiliated with the genus of Nitrosopira while the archaeal sequences were almost equally affiliated with Candidatus 'Nitrososphaera gargensis' and Candidatus 'Nitrosocaldus yellowstonii'. The spatial distribution of AOA and AOB indicated that bacteria may play a more important role in nitrification in the littoral buffer zone of a N-rich lake.

  1. Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria: Physiology and Regulatory Mechanisms.

    Science.gov (United States)

    Torres, M J; Simon, J; Rowley, G; Bedmar, E J; Richardson, D J; Gates, A J; Delgado, M J

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation. © 2016 Elsevier Ltd. All rights reserved.

  2. Peptidoglycan recognition proteins kill bacteria by inducing oxidative, thiol, and metal stress.

    Directory of Open Access Journals (Sweden)

    Des Raj Kashyap

    2014-07-01

    Full Text Available Mammalian Peptidoglycan Recognition Proteins (PGRPs are a family of evolutionary conserved bactericidal innate immunity proteins, but the mechanism through which they kill bacteria is unclear. We previously proposed that PGRPs are bactericidal due to induction of reactive oxygen species (ROS, a mechanism of killing that was also postulated, and later refuted, for several bactericidal antibiotics. Here, using whole genome expression arrays, qRT-PCR, and biochemical tests we show that in both Escherichia coli and Bacillus subtilis PGRPs induce a transcriptomic signature characteristic of oxidative stress, as well as correlated biochemical changes. However, induction of ROS was required, but not sufficient for PGRP killing. PGRPs also induced depletion of intracellular thiols and increased cytosolic concentrations of zinc and copper, as evidenced by transcriptome changes and supported by direct measurements. Depletion of thiols and elevated concentrations of metals were also required, but by themselves not sufficient, for bacterial killing. Chemical treatment studies demonstrated that efficient bacterial killing can be recapitulated only by the simultaneous addition of agents leading to production of ROS, depletion of thiols, and elevation of intracellular metal concentrations. These results identify a novel mechanism of bacterial killing by innate immunity proteins, which depends on synergistic effect of oxidative, thiol, and metal stress and differs from bacterial killing by antibiotics. These results offer potential targets for developing new antibacterial agents that would kill antibiotic-resistant bacteria.

  3. Anaerobic ammonium-oxidizing bacteria gain antibiotic resistance during long-term acclimatization.

    Science.gov (United States)

    Zhang, Zheng-Zhe; Zhang, Qian-Qian; Guo, Qiong; Chen, Qian-Qian; Jiang, Xiao-Yan; Jin, Ren-Cun

    2015-09-01

    Three broad-spectrum antibiotics, amoxicillin (AMX), florfenicol (FF) and sulfamethazine (SMZ), that inhibit bacteria via different target sites, were selected to evaluate the acute toxicity and long-term effects on anaerobic ammonium oxidation (anammox) granules. The specific anammox activity (SAA) levels reduced by approximately half within the first 3 days in the presence of antibiotics but no nitrite accumulation was observed in continuous-flow experiments. However, the SAA levels and heme c content gradually recovered as the antibiotic concentrations increased. Extracellular polymeric substances (EPS) analysis suggested that anaerobic ammonium-oxidizing bacteria gradually developed a better survival strategy during long-term acclimatization, which reduced the antibiotic stress via increased EPS secretion that provided a protective 'cocoon.' In terms of nitrogen removal efficiency, anammox granules could resist 60 mg-AMX L(-1), 10 mg-FF L(-1) and 100 mg-SMZ L(-1). This study supported the feasibility of using anammox granules to treat antibiotic-containing wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. IDENTITY OF THE PINK-PIGMENTED METHANOL-OXIDIZING BACTERIA AS VIBRIO EXTORQUENS.

    Science.gov (United States)

    STOCKS, P K; MCCLESKEY, C S

    1964-10-01

    Stocks, Peter K. (Louisiana State University, Baton Rouge), and C. S. McCleskey. Identity of the pink-pigmented methanol-oxidizing bacteria as Vibrio extorquens. J. Bacteriol. 88:1065-1070. 1964.-Pink-pigmented bacteria isolated from enrichment cultures of methane oxidizers were found to possess similar morphological, cultural, and physiological characteristics. All the strains utilized methanol, formate, oxalate, succinate, glycerol, and benzene as sole carbon sources; methanol, formate, and glycerol afforded best growth. Most strains utilized fructose and ribose; other carbohydrates tested were not available as carbon and energy sources. There was strain variation in the use of hexane, heptane, n-propanol, n-butanol, acetate, and propionate. Methane, ethane, n-propane, and n-butane were not utilized. Our isolates, and Pseudomonas methanica of Harrington and Kallio (not the methane-dependent P. methanica of Dworkin and Foster), Pseudomonas AM1 of Peele and Quayle, Pseudomonas PRL-W4 of Kaneda and Roxburgh, and Protaminobacter ruber den Dooren de Jong are nearly identical with Vibrio extorquens (Bassalik) Bhat and Barker, and should be considered the same species.

  5. Effect of inoculum sources on the enrichment of nitrite-dependent anaerobic methane-oxidizing bacteria.

    Science.gov (United States)

    He, Zhanfei; Cai, Chen; Shen, Lidong; Lou, Liping; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is a newly discovered biological process that couples anaerobic oxidation of methane (AOM) to nitrite reduction. In this study, three different inocula, methanogenic sludge, paddy soil, and freshwater sediment were used to enrich n-damo bacteria in three sequencing batch reactors (SBRs), and three n-damo enrichment cultures, C1, C2 and C3, were obtained, respectively. After 500 days of incubation, Methylomirabilis oxyfera-like bacteria and n-damo activities were observed in cultures C1, C2, and C3, and the specific activities were 0.8 ± 0.1, 1.4 ± 0.1, and 1.0 ± 0.1 μmol CH4 h(-1) g(-1) VSS, respectively. The copy numbers of 16S rRNA genes from cultures C1, C2, and C3 were 5.0 ± 0.4 × 10(8), 6.1 ± 0.1 × 10(9), and 1.0 ± 0.2 × 10(9) copies g(-1) dry weight, respectively. The results indicated that paddy soil is an excellent inoculum for n-damo bacterial enrichment. This work expanded the alternative source of n-damo inoculum and benefited the further research of n-damo process.

  6. Antimicrobial Effect of Copper Oxide Nanoparticles on Some Oral Bacteria and Candida Species

    Directory of Open Access Journals (Sweden)

    Amiri M

    2017-03-01

    Full Text Available Statement of Problem: Acid producing bacteria including Streptococcus mutans and lactobacilli cause tooth demineralization and lead to tooth decay. Also, oral colonization of the species of Candida has been reported in many studies that are resistant to antifungal agents. Objectives: In this study, antibacterial and antifungal effects of nano-CuO were studied against some oral bacteria and yeast fungi. Materials and Methods: The minimum inhibitory concentrations (MICs of copper oxide nanoparticles (CuO NPs for oral bacterial and fungal test strains were determined in 96-well microtiter plate technique. The agar diffusion test (ADT was employed to assess the antifungal properties of nystatin. Results: The MIC50 value of CuO NPs was determined at the range of 1–10 µg/ml for S. mutans, < 1 µg/ml for L. acidophilus, and 10 µg/ml for L. casei. Higher concentrations of CuO NPs (100-1000 µg/ml were effective on the bacterial cell growth, resulting in 100% reduction in the optical density in TSB medium. The cells of Candida albicans, C. krusei and C. glabrata were treated with CuO NPs and the results showed a decrease in fungal growth at a concentration of 1-1000 µg/ml in TSB medium. The MIC50 value of CuO NPs was determined 1000 µg/ml for three species of Candida. The diameter of growth inhibition zones of 1100 µg/ml nystatin was obtained 15-21 mm for clinical isolates of three species of Candida. Conclusions: With respect to the potential bactericidal activity of CuO NPs on various cariogenic bacteria examined in this study, these NPs could be introduce as a candidate control agent for preventing dental caries or dental infections. In our study, on the other hand, Nano copper oxide had a weak effect on the candida species.

  7. Electrochemical disinfection of bacteria-laden water using antimony-doped tin-tungsten-oxide electrodes.

    Science.gov (United States)

    Ghasemian, Saloumeh; Asadishad, Bahareh; Omanovic, Sasha; Tufenkji, Nathalie

    2017-12-01

    Electrochemical disinfection has been shown to be an efficient method with a shortrequired contact time for treatment of drinking water supplies, industrial raw water supplies, liquid foodstuffs, and wastewater effluents. In the present work, the electrochemical disinfection of saline water contaminated with bacteria was investigated in chloride-containing solutions using Sb-doped Sn 80% -W 20% -oxide anodes. The influence of current density, bacterial load, initial chloride concentration, solution pH, and the type of bacteria (E. coli D21, E. coli O157:H7, and E. faecalis) on disinfection efficacy was systematically examined. The impact of natural organic matter and a radical scavenger on the disinfection process was also examined. The electrochemical system was highly effective in bacterial inactivation for a 0.1 M NaCl solution contaminated with ∼10 7  CFU/mL bacteria by applying a current density ≥1 mA/cm 2 through the cell.100% inactivation of E. coli D21 was achieved with a contact time of less than 60 s and power consumption of 48 Wh/m 3 , by applying a current density of 6 mA/cm 2 in a 0.1 M NaCl solution contaminated with ∼10 7 CFU/mL. Reactive chlorine species as well as reactive oxygen species (e.g. hydroxyl radicals) generated in situ during the electrochemical process were determined to be responsible for inactivation of bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    Directory of Open Access Journals (Sweden)

    C. R. Löscher

    2012-07-01

    Full Text Available The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA over their bacterial counterparts (AOB in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O.

    Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA were detectable throughout the water column of the eastern tropical North Atlantic (ETNA and eastern tropical South Pacific (ETSP Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved

  9. Activity, Microenvironments, and Community Structure of Aerobic and Anaerobic Ammonium Oxidizing Prokaryotes in Estuarine Sediment (Randers Fjord, DK)

    DEFF Research Database (Denmark)

    Schramm, Andreas; Revsbech, Niels Peter; Dalsgaard, Tage

    2006-01-01

    ACTIVITY, MICROENVIRONMENTS, AND COMMUNITY STRUCTURE OF AEROBIC AND ANAEROBIC AMMONIUM OXIDIZING PROKARYOTES IN ESTUARINE SEDIMENT (RANDERS FJORD, DK) A. Schramm 1, N.P. Revsbech 1, T. Dalsgaard 2, E. Piña-Ochoa 3, J. de la Torré 4, D.A. Stahl 4, N. Risgaard-Petersen 2 1 Department of Biological...... conversion of ammonium with nitrite to N2, is increasingly recognized as link in the aquatic nitrogen cycle. However, factors regulating the occurrence and activity of anammox bacteria are still poorly understood. Besides the influence of abiotic factors, anammox might be controlled by either aerobic ammonia...... oxidizing bacteria and archaea (AOB and AOA) or nitrate-reducing/denitrifying bacteria via their supply of nitrite. Along the Randers Fjord estuary (Denmark), gradients of salinity, nutrients, and organic loading can be observed, and anammox has been detected previously at some sites. The aim of this study...

  10. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

    Science.gov (United States)

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-11-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments.

  11. Interactions between ammonia and nitrite oxidizing bacteria in co-cultures: Is there evidence for mutualism, commensalism, or competition?

    Energy Technology Data Exchange (ETDEWEB)

    Sayavedra-Soto, Luis [Oregon State Univ., Corvallis, OR (United States); Arp, Daniel [Oregon State Univ., Corvallis, OR (United States)

    2017-08-01

    Nitrification is a two-step environmental microbial process in the nitrogen cycle in which ammonia is oxidized to nitrate. Ammonia-oxidizing bacteria and archaea oxidize ammonia to nitrite and nitrite is oxidized to nitrate by nitrite-oxidizing bacteria. These microorganisms, which likely act in concert in a microbial community, play critical roles in the movement of inorganic N in soils, sediments and waters and are essential to the balance of the nitrogen cycle. Anthropogenic activity has altered the balance of the nitrogen cycle through agriculture practices and organic waste byproducts. Through their influence on available N for plant growth, nitrifying microorganisms influence plant productivity for food and fiber production and the associated carbon sequestration. N Fertilizer production, primarily as ammonia, requires large inputs of natural gas and hydrogen. In croplands fertilized with ammonia-based fertilizers, nitrifiers contribute to the mobilization of this N by producing nitrate (NO3-), wasting the energy used in the production and application of ammonia-based fertilizer. The resulting nitrate is readily leached from these soils, oxidized to gaseous N oxides (greenhouse gases), and denitrified to N2 (which is no longer available as a plant N source). Still, ammonia oxidizers are beneficial in the treatment of wastewater and they also show potential to contribute to microbial bioremediation strategies for clean up of environments contaminated with chlorinated hydrocarbons. Mitigation of the negative effects and exploitation of the beneficial effects of nitrifiers will be facilitated by a systems-level understanding of the interactions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria with the environment and with each other.

  12. Carbon isotope fractionation by sulfate-reducing bacteria using different pathways for the oxidation of acetate.

    Science.gov (United States)

    Goevert, Dennis; Conrad, Ralf

    2008-11-01

    Acetate is a key intermediate in the anaerobic degradation of organic matter. In anoxic environments, available acetate is a competitive substrate for sulfate-reducing bacteria (SRB) and methane-producing archaea. Little is known about the fractionation of carbon isotopes by sulfate reducers. Therefore, we determined carbon isotope compositions in cultures of three acetate-utilizing SRB, Desulfobacter postgatei, Desulfobacter hydrogenophilus, and Desulfobacca acetoxidans. We found that these species showed strong differences in their isotope enrichment factors (epsilon) of acetate. During the consumption of acetate and sulfate, acetate was enriched in 13C by 19.3% per hundred in Desulfobacca acetoxidans. By contrast, both D. postgatei and D. hydrogenophilus showed a slight depletion of 13C resulting in epsilon(ac)-values of 1.8 and 1.5% per hundred, respectively. We suggest that the different isotope fractionation is due to the different metabolic pathways for acetate oxidation. The strongly fractionating Desulfobacca acetoxidans uses the acetyl-CoA/carbon monoxide dehydrogenase pathway, which is also used by acetoclastic methanogens that show a similar fractionation of acetate (epsilon(ac) = -21 to -27% per hundred). In contrast, Desulfobacter spp. oxidize acetate to CO2 via the tricarboxylic acid (TCA) cycle and apparently did not discriminate against 13C. Our results suggestthat carbon isotope fractionation in environments with sulfate reduction will strongly depend on the composition of the sulfate-reducing bacterial community oxidizing acetate.

  13. Hydroxylamine addition impact to Nitrosomonas europaea activity in the presence of monochloramine

    Science.gov (United States)

    In drinking water, monochloramine may promote ammonia–oxidizing bacteria (AOB) growth because of concurrent ammonia presence. AOB use (i) ammonia monooxygenase for biological ammonia oxidation to hydroxylamine and (ii) hydroxylamine oxidoreductase for hydroxylamine oxidation to ...

  14. Bio-dissolution of Ni, V and Mo from spent petroleum catalyst using iron oxidizing bacteria.

    Science.gov (United States)

    Pradhan, Debabrata; Kim, Dong J; Roychaudhury, Gautam; Lee, Seoung W

    2010-01-01

    Bioleaching studies of spent petroleum catalyst containing Ni, V and Mo were carried out using iron oxidizing bacteria. Various leaching parameters such as Fe(II) concentration, pulp density, pH, temperature and particle size were studied to evaluate their effects on the leaching efficiency as well as the kinetics of dissolution. The percentage of leaching of Ni and V were higher than Mo. The leaching process followed a diffusion controlled model and the product layer was observed to be impervious due to formation of ammonium jarosite (NH(4))Fe(3)(SO(4))(2)(OH)(6). Apart from this, the lower leaching efficiency of Mo was due to a hydrophobic coating of elemental sulfur over Mo matrix in the spent catalyst. The diffusivities of the attacking species for Ni, V and Mo were also calculated.

  15. Improved methane removal in exhaust gas from biogas upgrading process using immobilized methane-oxidizing bacteria.

    Science.gov (United States)

    Sun, Meng-Ting; Yang, Zhi-Man; Fu, Shan-Fei; Fan, Xiao-Lei; Guo, Rong-Bo

    2018-05-01

    Methane in exhaust gas from biogas upgrading process, which is a greenhouse gas, could cause global warming. The biofilter with immobilized methane-oxidizing bacteria (MOB) is a promising approach for methane removal, and the selections of inoculated MOB culture and support material are vital for the biofilter. In this work, five MOB consortia were enriched at different methane concentrations. The MOB-20 consortium enriched at the methane concentration of 20.0% (v/v) was then immobilized on sponge and two particle sizes of volcanic rock in biofilters to remove methane in exhaust gas from biogas upgrading process. Results showed that the immobilized MOB performed more admirable methane removal capacity than suspended cells. The immobilized MOB on sponge reached the highest methane removal efficiency (RE) of 35%. The rough surface, preferable hydroscopicity, appropriate pore size and particle size of support material might favor the MOB immobilization and accordingly methane removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. From bacteria to mollusks: the principles underlying the biomineralization of iron oxide materials.

    Science.gov (United States)

    Faivre, Damien; Godec, Tina Ukmar

    2015-04-13

    Various organisms possess a genetic program that enables the controlled formation of a mineral, a process termed biomineralization. The variety of biological material architectures is mind-boggling and arises from the ability of organisms to exert control over crystal nucleation and growth. The structure and composition of biominerals equip biomineralizing organisms with properties and functionalities that abiotically formed materials, made of the same mineral, usually lack. Therefore, elucidating the mechanisms underlying biomineralization and morphogenesis is of interdisciplinary interest to extract design principles that will enable the biomimetic formation of functional materials with similar capabilities. Herein, we summarize what is known about iron oxides formed by bacteria and mollusks for their magnetic and mechanical properties. We describe the chemical and biological machineries that are involved in controlling mineral precipitation and organization and show how these organisms are able to form highly complex structures under physiological conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Toxicity of graphene oxide on intestinal bacteria and Caco-2 cells.

    Science.gov (United States)

    Nguyen, Trang H D; Lin, Mengshi; Mustapha, Azlin

    2015-05-01

    In recent years, novel nanomaterials have received much attention due to their great potential for applications in agriculture, food safety, and food packaging. Among them, graphene and graphene oxide (GO) are emerging as promising nanomaterials that may have a profound impact on food packaging. However, there are some concerns from consumers and the scientific community about the potential toxicity and biocompatibility of nanomaterials. In this study, we investigated the antibacterial properties of GO against human intestinal bacteria. The cytotoxicity of GO was also studied in vitro using the Caco-2 cell line derived from a colon carcinoma. Electron microscopy was used to investigate the morphology of GO and the interaction between GO flakes and Caco-2 cells. GO at different concentrations (10 to 500 μg/ml) exhibited no toxicity against the selected bacteria and a mild cytotoxic action on Caco-2 cells after 24 h of exposure. The results show that weak adsorption of medium nutrients may contribute to GO's low toxicity. This study suggests that GO is biocompatible and has a potential to be used in agriculture and food science, indicating that more studies are needed to exploit its potential applications.

  18. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

    Science.gov (United States)

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

    2014-04-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

  19. Temporal and Spatial Dynamics of Sediment Anaerobic Ammonium Oxidation (Anammox) Bacteria in Freshwater Lakes.

    Science.gov (United States)

    Yang, Yuyin; Dai, Yu; Li, Ningning; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-02-01

    Anaerobic ammonium-oxidizing (anammox) process can play an important role in freshwater nitrogen cycle. However, the distribution of anammox bacteria in freshwater lake and the associated environmental factors remain essentially unclear. The present study investigated the temporal and spatial dynamics of sediment anammox bacterial populations in eutrotrophic Dianchi Lake and mesotrophic Erhai Lake on the Yunnan Plateau (southwestern China). The remarkable spatial change of anammox bacterial abundance was found in Dianchi Lake, while the relatively slight spatial shift occurred in Erhai Lake. Dianchi Lake had greater anammox bacterial abundance than Erhai Lake. In both Dianchi Lake and Erhai Lake, anammox bacteria were much more abundant in summer than in spring. Anammox bacterial community richness, diversity, and structure in these two freshwater lakes were subjected to temporal and spatial variations. Sediment anammox bacterial communities in Dianchi Lake and Erhai Lake were dominated by Candidatus Brocadia and a novel phylotype followed by Candidatus Kuenenia; however, these two lakes had distinct anammox bacterial community structure. In addition, trophic status determined sediment anammox bacterial community structure.

  20. Dissimilatory metabolism of nitrogen oxides in bacteria: comparative reconstruction of transcriptional networks.

    Directory of Open Access Journals (Sweden)

    2005-10-01

    Full Text Available Bacterial response to nitric oxide (NO is of major importance since NO is an obligatory intermediate of the nitrogen cycle. Transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is diverse and involves FNR-like transcription factors HcpR, DNR, and NnrR; two-component systems NarXL and NarQP; NO-responsive activator NorR; and nitrite-sensitive repressor NsrR. Using comparative genomics approaches, we predict DNA-binding motifs for these transcriptional factors and describe corresponding regulons in available bacterial genomes. Within the FNR family of regulators, we observed a correlation of two specificity-determining amino acids and contacting bases in corresponding DNA recognition motif. Highly conserved regulon HcpR for the hybrid cluster protein and some other redox enzymes is present in diverse anaerobic bacteria, including Clostridia, Thermotogales, and delta-proteobacteria. NnrR and DNR control denitrification in alpha- and beta-proteobacteria, respectively. Sigma-54-dependent NorR regulon found in some gamma- and beta-proteobacteria contains various enzymes involved in the NO detoxification. Repressor NsrR, which was previously known to control only nitrite reductase operon in Nitrosomonas spp., appears to be the master regulator of the nitric oxides' metabolism, not only in most gamma- and beta-proteobacteria (including well-studied species such as Escherichia coli, but also in Gram-positive Bacillus and Streptomyces species. Positional analysis and comparison of regulatory regions of NO detoxification genes allows us to propose the candidate NsrR-binding motif. The most conserved member of the predicted NsrR regulon is the NO-detoxifying flavohemoglobin Hmp. In enterobacteria, the regulon also includes two nitrite-responsive loci, nipAB (hcp-hcr and nipC (dnrN, thus confirming the identity of the effector, i.e. nitrite. The proposed NsrR regulons in Neisseria and some other species are extended to include

  1. Dissimilatory Metabolism of Nitrogen Oxides in Bacteria:Comparative Reconstruction of Transcriptional Networks

    Energy Technology Data Exchange (ETDEWEB)

    Rodionov, Dmitry A.; Dubchak, Inna L.; Arkin, Adam P.; Alm, EricJ.; Gelfand, Mikhail S.

    2005-09-01

    Bacterial response to nitric oxide (NO) is of major importance since NO is an obligatory intermediate of the nitrogen cycle. Transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is diverse and involves FNR-like transcription factors HcpR, DNR and NnrR, two-component systems NarXL and NarQP, NO-responsive activator NorR, and nitrite sensitive repressor NsrR. Using comparative genomics approaches we predict DNA-binding signals for these transcriptional factors and describe corresponding regulons in available bacterial genomes. Within the FNR family of regulators, we observed a correlation of two specificity-determining amino acids and contacting bases in corresponding DNA signal. Highly conserved regulon HcpR for the hybrid cluster protein and some other redox enzymes is present in diverse anaerobic bacteria including Clostridia, Thermotogales and delta-proteobacteria. NnrR and DNR control denitrification in alpha- and beta-proteobacteria, respectively. Sigma-54-dependent NorR regulon found in some gamma- and beta-proteobacteria contains various enzymes involved in the NO detoxification. Repressor NsrR, which was previously known to control only nitrite reductase operon in Nitrosomonas spp., appears to be the master regulator of the nitric oxides metabolism not only in most gamma- and beta-proteobacteria (including well-studied species like Escherichia coli), but also in Gram-positive Bacillus and Streptomyces species. Positional analysis and comparison of regulatory regions of NO detoxification genes allows us to propose the candidate NsrR-binding signal. The most conserved member of the predicted NsrR regulon is the NO-detoxifying flavohemoglobin Hmp. In enterobacteria, the regulon includes also two nitrite-responsive loci, nipAB (hcp-hcr) and nipC(dnrN), thus confirming the identity of the effector, i.e., nitrite. The proposed NsrR regulons in Neisseria and some other species are extended to include denitrification genes. As the

  2. Effects of reforestation on ammonia-oxidizing microbial community composition and abundance in subtropical acidic forest soils.

    Science.gov (United States)

    Wu, Ruo-Nan; Meng, Han; Wang, Yong-Feng; Gu, Ji-Dong

    2018-06-01

    Forest ecosystems have great ecological values in mitigation of climate change and protection of biodiversity of flora and fauna; re-forestry is commonly used to enhance the sequestration of atmospheric CO 2 into forest storage biomass. Therefore, seasonal and spatial dynamics of the major microbial players in nitrification, ammonia-oxidizing archaea (AOA) and bacteria (AOB), in acidic soils of young and matured revegetated forests were investigated to elucidate the changes of microbial communities during forest restoration, and compared to delineate the patterns of community shifts under the influences of environmental factors. AOA were more abundant than AOB in both young and matured revegetated forest soils in both summer and winter seasons. In summer, however, the abundance of amoA-AOA decreased remarkably (p < 0.01), ranging from 1.90 (± 0.07) × 10 8 copies per gram dry soil in matured forest to 5.04 (± 0.43) × 10 8 copies per gram dry soil in young forest, and amoA-AOB was below detection limits to obtain any meaningful values. Moreover, exchangeable Al 3+ and organic matter were found to regulate the physiologically functional nitrifiers, especially AOA abundance in acidic forest soils. AOB community in winter showed stronger correlation with the restoration status of revegetated forests and AOA community dominated by Nitrosotalea devanaterra, in contrast, was more sensitive to the seasonal and spatial variations of environmental factors. These results enrich the current knowledge of nitrification during re-forestry and provide valuable information to developmental status of revegetated forests for management through microbial analysis.

  3. Antimicrobial activities of the Streptomyces ceolicolor strain AOB KF977550 isolated from a tropical estuary

    Directory of Open Access Journals (Sweden)

    Bamidele T. Odumosu

    2017-11-01

    Full Text Available The aim of this study was to screen for important antibiotic producing species of the genus Streptomyces from a tropical estuary. Five bacterial strains were isolated from the Lagos lagoon and identified by 16S rDNA gene sequencing as Streptomyces albogriseolus, S. aureus, S. coelicolor, S. albus, and S. pseudogriseolus. Ethyl acetate extracts of Streptomyces spp. fermented broths were evaluated against laboratory strains of MRSA Methicillin-resistant Staphyloccus aureus (MRSA 144 m, Bacillus coagulans UL001, and Escherichia coli as well as the standard strains Klebsiella pneumonia ATCC 8308, Gardnerella vaginalis ATCC 27853 and Salmonella typhi ATCC 13311 using the well diffusion method. The presence of secondary metabolites was determined and analysed using gas chromatography-mass spectrometry (GC-MS. A broad spectrum of activity was only observed for S. coelicolor on all of the tested bacteria except S. typhi, ant GC-MS analysis revealed the presence of 16 secondary metabolites with relevant antibiotic properties. The result of this study suggest that Lagos Lagoon is a potential source and reservoir of novel antibiotics. Keywords: Streptomyces, Antibiotics, Resistance, Secondary Metabolites

  4. Lithotrophic iron-oxidizing bacteria produce organic stalks to control mineral growth: implications for biosignature formation

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Clara S; Fakra, Sirine C; Emerson, David; Fleming, Emily J; Edwards, Katrina J

    2011-07-01

    Neutrophilic Fe-oxidizing bacteria (FeOB) are often identified by their distinctive morphologies, such as the extracellular twisted ribbon-like stalks formed by Gallionella ferruginea or Mariprofundus ferrooxydans. Similar filaments preserved in silica are often identified as FeOB fossils in rocks. Although it is assumed that twisted iron stalks are indicative of FeOB, the stalk's metabolic role has not been established. To this end, we studied the marine FeOB M. ferrooxydans by light, X-ray and electron microscopy. Using time-lapse light microscopy, we observed cells excreting stalks during growth (averaging 2.2 {micro}m h(-1)). Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy show that stalks are Fe(III)-rich, whereas cells are low in Fe. Transmission electron microscopy reveals that stalks are composed of several fibrils, which contain few-nanometer-sized iron oxyhydroxide crystals. Lepidocrocite crystals that nucleated on the fibril surface are much larger ({approx}100 nm), suggesting that mineral growth within fibrils is retarded, relative to sites surrounding fibrils. C and N 1s NEXAFS spectroscopy and fluorescence probing show that stalks primarily contain carboxyl-rich polysaccharides. On the basis of these results, we suggest a physiological model for Fe oxidation in which cells excrete oxidized Fe bound to organic polymers. These organic molecules retard mineral growth, preventing cell encrustation. This model describes an essential role for stalk formation in FeOB growth. We suggest that stalk-like morphologies observed in modern and ancient samples may be correlated confidently with the Fe-oxidizing metabolism as a robust biosignature.

  5. Identification of Mn(II)-oxidizing bacteria from a low-pH contaminated former uranium mine.

    Science.gov (United States)

    Akob, Denise M; Bohu, Tsing; Beyer, Andrea; Schäffner, Franziska; Händel, Matthias; Johnson, Carol A; Merten, Dirk; Büchel, Georg; Totsche, Kai Uwe; Küsel, Kirsten

    2014-08-01

    Biological Mn oxidation is responsible for producing highly reactive and abundant Mn oxide phases in the environment that can mitigate metal contamination. However, little is known about Mn oxidation in low-pH environments, where metal contamination often is a problem as the result of mining activities. We isolated two Mn(II)-oxidizing bacteria (MOB) at pH 5.5 (Duganella isolate AB_14 and Albidiferax isolate TB-2) and nine strains at pH 7 from a former uranium mining site. Isolate TB-2 may contribute to Mn oxidation in the acidic Mn-rich subsoil, as a closely related clone represented 16% of the total community. All isolates oxidized Mn over a small pH range, and isolates from low-pH samples only oxidized Mn below pH 6. Two strains with different pH optima differed in their Fe requirements for Mn oxidation, suggesting that Mn oxidation by the strain found at neutral pH was linked to Fe oxidation. Isolates tolerated Ni, Cu, and Cd and produced Mn oxides with similarities to todorokite and birnessite, with the latter being present in subsurface layers where metal enrichment was associated with Mn oxides. This demonstrates that MOB can be involved in the formation of biogenic Mn oxides in both moderately acidic and neutral pH environments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  6. Identification of Mn(II)-oxidizing bacteria from a low-pH contaminated former uranium mine

    Science.gov (United States)

    Akob, Denise M.; Bohu, Tsing; Beyer, Andrea; Schäffner, Franziska; Händel, Matthias; Johnson, Carol A.; Merten, Dirk; Büchel, Georg; Totsche, Kai Uwe; Küsel, Kirsten

    2014-01-01

    Biological Mn oxidation is responsible for producing highly reactive and abundant Mn oxide phases in the environment that can mitigate metal contamination. However, little is known about Mn oxidation in low-pH environments, where metal contamination often is a problem as the result of mining activities. We isolated two Mn(II)-oxidizing bacteria (MOB) at pH 5.5 (Duganella isolate AB_14 and Albidiferax isolate TB-2) and nine strains at pH 7 from a former uranium mining site. Isolate TB-2 may contribute to Mn oxidation in the acidic Mn-rich subsoil, as a closely related clone represented 16% of the total community. All isolates oxidized Mn over a small pH range, and isolates from low-pH samples only oxidized Mn below pH 6. Two strains with different pH optima differed in their Fe requirements for Mn oxidation, suggesting that Mn oxidation by the strain found at neutral pH was linked to Fe oxidation. Isolates tolerated Ni, Cu, and Cd and produced Mn oxides with similarities to todorokite and birnessite, with the latter being present in subsurface layers where metal enrichment was associated with Mn oxides. This demonstrates that MOB can be involved in the formation of biogenic Mn oxides in both moderately acidic and neutral pH environments.

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

    Directory of Open Access Journals (Sweden)

    Michela eLangone

    2014-02-01

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

  8. Behavior of Copper Oxide Nanoparticles in Soil Pore Waters as Influenced by Soil Characteristics, Bacteria, and Wheat Roots

    OpenAIRE

    Hortin, Joshua

    2017-01-01

    The goal of this project was to study the behavior of copper oxide nanoparticles in soil environments. Copper oxide nanoparticles have antimicrobial properties and may also be used in agricultural settings to provide a source of copper for plant health, but accidental or misapplication of these nanoparticles to soil may be damaging to the plant and its associated bacteria. Dissolved soil organic matter that is present in soil pore waters dissolved nanoparticles, but did not dissolve the ex...

  9. Sulfur-oxidizing bacteria dominate the microbial diversity shift during the pyrite and low-grade pyrolusite bioleaching process.

    Science.gov (United States)

    Han, Yifan; Ma, Xiaomei; Zhao, Wei; Chang, Yunkang; Zhang, Xiaoxia; Wang, Xingbiao; Wang, Jingjing; Huang, Zhiyong

    2013-10-01

    The microbial ecology of the pyrite-pyrolusite bioleaching system and its interaction with ore has not been well-described. A 16S rRNA gene clone library was created to evaluate changes in the microbial community at different stages of the pyrite-pyrolusite bioleaching process in a shaken flask. The results revealed that the bacterial community was disturbed after 5 days of the reaction. Phylogenetic analysis of 16S rRNA sequences demonstrated that the predominant microorganisms were members of a genus of sulfur-oxidizing bacteria, Thiomonas sp., that subsequently remained dominant during the bioleaching process. Compared with iron-oxidizing bacteria, sulfur-oxidizing bacteria were more favorable to the pyrite-pyrolusite bioleaching system. Decreased pH due to microbial acid production was an important condition for bioleaching efficiency. Iron-oxidizing bacteria competed for pyrite reduction power with Mn(IV) in pyrolusite under specific conditions. These results extend our knowledge of microbial dynamics during pyrite-pyrolusite bioleaching, which is a key issue to improve commercial applications. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  10. Remarkable recovery and colonization behaviour of methane oxidizing bacteria in soil after disturbance is controlled by methane source only

    NARCIS (Netherlands)

    Pan, Y.; Abell, G.C.J.; Bodelier, P.L.E.; Meima-Franke, M.; Sessitsch, A.; Bodrossy, L.

    2014-01-01

    Little is understood about the relationship between microbial assemblage history, the composition and function of specific functional guilds and the ecosystem functions they provide. To learn more about this relationship we used methane oxidizing bacteria (MOB) as model organisms and performed soil

  11. Mathematical modeling of nitrous oxide production in an anaerobic/oxic/anoxic process.

    Science.gov (United States)

    Ding, Xiaoqian; Zhao, Jianqiang; Hu, Bo; Chen, Ying; Ge, Guanghuan; Li, Xiaoling; Wang, Sha; Gao, Kun; Tian, Xiaolei

    2016-12-01

    This study incorporates three currently known nitrous oxide (N 2 O) production pathways: ammonium-oxidizing bacteria (AOB) denitrification, incomplete hydroxylamine (NH 2 OH) oxidation, and heterotrophic denitrification on intracellular polymers, into a mathematical model to describe N 2 O production in an anaerobic/oxic/anoxic (AOA) process for the first time. The developed model was calibrated and validated by four experimental cases, then evaluated by two independent anaerobic/aerobic (AO) studies from literature. The modeling results displayed good agreement with the measured data. N 2 O was primarily generated in the aerobic stage by AOB denitrification (67.84-81.64%) in the AOA system. Smaller amounts of N 2 O were produced via incomplete NH 2 OH oxidation (15.61-32.17%) and heterotrophic denitrification on intracellular polymers (0-12.47%). The high nitrite inhibition on N 2 O reductase led to the increased N 2 O accumulation in heterotrophic denitrification on intracellular polymers. The new model was capable of modeling nitrification-denitrification dynamics and heterotrophic denitrification on intracellular polymers in the AOA system. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.

    Science.gov (United States)

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-04-03

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N 2 O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N 2 O model, which incorporated two N 2 O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH 2 OH) oxidation). The two-pathway model was used to describe N 2 O production from a granule-based partial nitritation (PN) reactor and provide insights into the N 2 O distribution inside granules. The model was evaluated by comparing simulation results with N 2 O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N 2 O dynamics and provided useful information about the shift of N 2 O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N 2 O production. The results further revealed a linear relationship between N 2 O production and ammonia oxidation rate (AOR) (R 2  = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N 2 O production by causing a change in AOR.

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

    Science.gov (United States)

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

    2016-01-01

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

  14. Iodine from bacterial iodide oxidization by Roseovarius spp. inhibits the growth of other bacteria.

    Science.gov (United States)

    Zhao, Dan; Lim, Choon-Ping; Miyanaga, Kazuhiko; Tanji, Yasunori

    2013-03-01

    Microbial activities in brine, seawater, or estuarine mud are involved in iodine cycle. To investigate the effects of the microbiologically induced iodine on other bacteria in the environment, a total of 13 bacteria that potentially participated in the iodide-oxidizing process were isolated from water or biofilm at a location containing 131 μg ml(-1) iodide. Three distinct strains were further identified as Roseovarius spp. based on 16 S rRNA gene sequences after being distinguished by restriction fragment length polymorphism analysis. Morphological characteristics of these three Roseovarius spp. varied considerably across and within strains. Iodine production increased with Roseovarius spp. growth when cultured in Marine Broth with 200 μg ml(-1) iodide (I(-)). When 10(6) CFU/ml Escherichia coli, Pseudomonas aeruginosa, and Bacillus pumilus were exposed to various concentrations of molecular iodine (I(2)), the minimum inhibitory concentrations (MICs) were 0.5, 1.0, and 1.0 μg ml(-1), respectively. However, fivefold increases in the MICs for Roseovarius spp. were obtained. In co-cultured Roseovarius sp. IOB-7 and E. coli in Marine Broth containing iodide (I(-)), the molecular iodine concentration was estimated to be 0.76 μg ml(-1) after 24 h and less than 50 % of E. coli was viable compared to that co-cultured without iodide. The growth inhibition of E. coli was also observed in co-cultures with the two other Roseovarius spp. strains when the molecular iodine concentration was assumed to be 0.52 μg ml(-1).

  15. Respiratory transformation of nitrous oxide (N2O) to dinitrogen by Bacteria and Archaea.

    Science.gov (United States)

    Zumft, Walter G; Kroneck, Peter M H

    2007-01-01

    N2O is a potent greenhouse gas and stratospheric reactant that has been steadily on the rise since the beginning of industrialization. It is an obligatory inorganic metabolite of denitrifying bacteria, and some production of N2O is also found in nitrifying and methanotrophic bacteria. We focus this review on the respiratory aspect of N2O transformation catalysed by the multicopper enzyme nitrous oxide reductase (N2OR) that provides the bacterial cell with an electron sink for anaerobic growth. Two types of Cu centres discovered in N2OR were both novel structures among the Cu proteins: the mixed-valent dinuclear Cu(A) species at the electron entry site of the enzyme, and the tetranuclear Cu(Z) centre as the first catalytically active Cu-sulfur complex known. Several accessory proteins function as Cu chaperone and ABC transporter systems for the biogenesis of the catalytic centre. We describe here the paradigm of Z-type N2OR, whose characteristics have been studied in most detail in the genera Pseudomonas and Paracoccus. Sequenced bacterial genomes now provide an invaluable additional source of information. New strains harbouring nos genes and capability of N2O utilization are being uncovered. This reveals previously unknown relationships and allows pattern recognition and predictions. The core nos genes, nosZDFYL, share a common phylogeny. Most principal taxonomic lineages follow the same biochemical and genetic pattern and share the Z-type enzyme. A modified N2OR is found in Wolinella succinogenes, and circumstantial evidence also indicates for certain Archaea another type of N2OR. The current picture supports the view of evolution of N2O respiration prior to the separation of the domains Bacteria and Archaea. Lateral nos gene transfer from an epsilon-proteobacterium as donor is suggested for Magnetospirillum magnetotacticum and Dechloromonas aromatica. In a few cases, nos gene clusters are plasmid borne. Inorganic N2O metabolism is associated with a diversity of

  16. Isotopologue signatures of nitrous oxide produced by nitrate-ammonifying bacteria isolated from soil

    Science.gov (United States)

    Behrendt, Undine; Well, Reinhard; Giesemann, Anette; Ulrich, Andreas; Augustin, Jürgen

    2015-04-01

    21to36o [3] ,which are much closer to the values of N2O from the investigated DNRA bacteria. However, the N2O formed under denitrifying conditions by organisms investigated so far can be distinguished with respect to its source (DNRA or denitrification) but a broader database is needed which cover a larger spectrum of taxa. [1] Sutka et al. Distinguishing nitrous oxide production from nitrification and denitrification on the basis of isotopomer abundances. Appl. Env. Microbiol. 2006, 72, 638. [2] Toyoda et al. Fractionation of N2O isotopomers during production by denitrifier. Soil Biol. Biochem. 2005, 37, 1535. [3] Rohe et al. Dual isotope and isotopomer signatures of nitrous oxide from fungal denitrification - a pure culture study. Rapid Commun. Mass Spectrom. 2014, 28, 1893

  17. Hybrid Nitrous Oxide Production from a Partial Nitrifying Bioreactor: Hydroxylamine Interactions with Nitrite.

    Science.gov (United States)

    Terada, Akihiko; Sugawara, Sho; Hojo, Keisuke; Takeuchi, Yuki; Riya, Shohei; Harper, Willie F; Yamamoto, Tomoko; Kuroiwa, Megumi; Isobe, Kazuo; Katsuyama, Chie; Suwa, Yuichi; Koba, Keisuke; Hosomi, Masaaki

    2017-03-07

    The goal of this study was to elucidate the mechanisms of nitrous oxide (N 2 O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched from a sequencing batch reactor (SBR) were subjected to N 2 O production pathway tests. The N 2 O pathway test was initiated by supplying an inorganic medium to ensure an initial NH 4 + -N concentration of 160 mg-N/L, followed by 15 NO 2 - (20 mg-N/L) and dual 15 NH 2 OH (each 17 mg-N/L) spikings to quantify isotopologs of gaseous N 2 O ( 44 N 2 O, 45 N 2 O, and 46 N 2 O). N 2 O production was boosted by 15 NH 2 OH spiking, causing exponential increases in mRNA transcription levels of AOB functional genes encoding hydroxylamine oxidoreductase (haoA), nitrite reductase (nirK), and nitric oxide reductase (norB) genes. Predominant production of 45 N 2 O among N 2 O isotopologs (46% of total produced N 2 O) indicated that coupling of 15 NH 2 OH with 14 NO 2 - produced N 2 O via N-nitrosation hybrid reaction as a predominant pathway. Abiotic hybrid N 2 O production was also observed in the absence of the AOB-enriched biomass, indicating multiple pathways for N 2 O production in a PN bioreactor. The additional N 2 O pathway test, where 15 NH 4 + was spiked into 400 mg-N/L of NO 2 - concentration, confirmed that the hybrid N 2 O production was a dominant pathway, accounting for approximately 51% of the total N 2 O production.

  18. Quantification of syntrophic fatty acid-{beta}-oxidizing bacteria in a mesophilic biogas reactor by oligonucleotide probe hybridization

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, K.H.; Ahring, B.K.; Raskin, L.

    1999-11-01

    Small-subunit rRNA sequences were obtained for two saturated fatty acid-{beta}-oxidizing syntrophic bacteria, Syntrophomonas sapovorans and Syntrophomonas wolfei LYB, and sequence analysis confirmed their classification as members of the family Syntrophomonadaceae. S.wolfei LYB was closely related to S.wolfei subsp. solfei, but S. sapovorans did not cluster with the other members of the genus Syntrophomonas. Five oligonucleotide probes targeting the small-subunit rRNA of different groups within the family Syntrophomonadaceae, which contains all currently known saturated fatty acid-{beta}-oxidizing syntrophic bacteria, were developed and characterized. The probes were designed to be specific at the family, genus, and species levels and were characterized by temperature-of-dissociation and specificity studies. To demonstrate the usefulness of the probes for the detection and quantification of saturated fatty acid-{beta}-oxidizing syntrophic bacteria in methanogenic environments, the microbial community structure of a sample from a full-scale biogas plant was determined. Hybridization results with probes for syntrophic bacteria and methanogens were compared to specific methanogenic activities and microbial numbers determined with most-probable-number estimates. Most of the methanogenic rRNA was comprised of Methanomicrobiales rRNA, suggesting that members of this order served as the main hydrogen-utilizing microorganisms. Between 0.2 and 1% of the rRNA was attributed to the Syntrophomonadaceae, or which the majority was accounted for by the genus Syntrophomonas.

  19. The potential of methane-oxidizing bacteria for applications in environmental biotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Wendlandt, Karin-Dagmar; Stottmeister, Ulrich; Jechorek, Mirko [Helmholtz-Center for Environmental Research UFZ, Leipzig (Germany); Helm, Jana [School of Physics and Astronomy, The University of Edinburgh, Edinburgh (United Kingdom); Soltmann, Bettina [Institute for Materials Science, Dresden University of Technology, Dresden (Germany); Beck, Matthias [Oncotec, Pharma Production GmbH, Dessau-Rosslau (Germany)

    2010-04-15

    Methanotrophic bacteria possess a unique set of enzymes enabling them to oxidize, degrade and transform organic molecules and synthesize new compounds. Therefore, they have great potential in environmental biotechnology. The application of these unique properties was demonstrated in three case studies: (i) Methane escaping from leaky gas pipes may lead to massive mortality of trees in urban areas. Lack of oxygen within the soil surrounding tree roots caused by methanotrophic activity was identified as one of the reasons for this phenomenon. The similarity between metabolic reactions performed by the key enzymes of methanotrophs (methane monooxygenase) and ammonium oxidizers (ammonium monooxygenase) might offer a solution to this problem by applying commercially available nitrification and urease inhibitors. (ii) Methanotrophs are able to co-metabolically degrade contaminants such as low-molecular-weight-chlorinated hydrocarbons in soil and water in the presence of methane. Batch and continuous trichloroethylene degradation experiments in laboratory-scale reactors using Methylocystis sp. GB 14 were performed, partly with cells entrapped in a polymer matrix. (iii) Using a short, two-stage pilot-scale process, the intracellular polymer accumulation of poly-{beta}-hydroxybutyrate (PHB) in methanotrophs reached a maximum of 52%. Interestingly, an ultra-high-molecular-weight PHB of 3.1 MDa was accumulated under potassium deficiency. Under strictly controlled conditions (temperature, pH and methane supply) this process can be nonsterile because of the establishment of a stable microbial community (dominant species Methylocystis sp. GB 25 {>=}86% by biomass). The possibility to substitute methane with biogas from renewable sources facilitates the development of a methane-based PHB production process that yields a high-quality biopolymer at competitive costs. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Potential Role of Nitrite for Abiotic Fe(II) Oxidation and Cell Encrustation during Nitrate Reduction by Denitrifying Bacteria

    Science.gov (United States)

    Klueglein, Nicole; Zeitvogel, Fabian; Stierhof, York-Dieter; Floetenmeyer, Matthias; Konhauser, Kurt O.; Obst, Martin

    2014-01-01

    Microorganisms have been observed to oxidize Fe(II) at neutral pH under anoxic and microoxic conditions. While most of the mixotrophic nitrate-reducing Fe(II)-oxidizing bacteria become encrusted with Fe(III)-rich minerals, photoautotrophic and microaerophilic Fe(II) oxidizers avoid cell encrustation. The Fe(II) oxidation mechanisms and the reasons for encrustation remain largely unresolved. Here we used cultivation-based methods and electron microscopy to compare two previously described nitrate-reducing Fe(II) oxidizers ( Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002) and two heterotrophic nitrate reducers (Paracoccus denitrificans ATCC 19367 and P. denitrificans Pd 1222). All four strains oxidized ∼8 mM Fe(II) within 5 days in the presence of 5 mM acetate and accumulated nitrite (maximum concentrations of 0.8 to 1.0 mM) in the culture media. Iron(III) minerals, mainly goethite, formed and precipitated extracellularly in close proximity to the cell surface. Interestingly, mineral formation was also observed within the periplasm and cytoplasm; intracellular mineralization is expected to be physiologically disadvantageous, yet acetate consumption continued to be observed even at an advanced stage of Fe(II) oxidation. Extracellular polymeric substances (EPS) were detected by lectin staining with fluorescence microscopy, particularly in the presence of Fe(II), suggesting that EPS production is a response to Fe(II) toxicity or a strategy to decrease encrustation. Based on the data presented here, we propose a nitrite-driven, indirect mechanism of cell encrustation whereby nitrite forms during heterotrophic denitrification and abiotically oxidizes Fe(II). This work adds to the known assemblage of Fe(II)-oxidizing bacteria in nature and complicates our ability to delineate microbial Fe(II) oxidation in ancient microbes preserved as fossils in the geological record. PMID:24271182

  1. Mechanical properties of bio self-healing concrete containing immobilized bacteria with iron oxide nanoparticles.

    Science.gov (United States)

    Seifan, Mostafa; Sarmah, Ajit K; Samani, Ali Khajeh; Ebrahiminezhad, Alireza; Ghasemi, Younes; Berenjian, Aydin

    2018-05-01

    Concrete is arguably one of the most important and widely used materials in the world, responsible for the majority of the industrial revolution due to its unique properties. However, it is susceptible to cracking under internal and external stresses. The generated cracks result in a significant reduction in the concrete lifespan and an increase in maintenance and repair costs. In recent years, the implementation of bacterial-based healing agent in the concrete matrix has emerged as one of the most promising approaches to address the concrete cracking issue. However, the bacterial cells need to be protected from the high pH content of concrete as well as the exerted shear forces during preparation and hardening stages. To address these issues, we propose the magnetic immobilization of bacteria with iron oxide nanoparticles (IONs). In the present study, the effect of the designed bio-agent on mechanical properties of concrete (compressive strength and drying shrinkage) is investigated. The results indicate that the addition of immobilized Bacillus species with IONs in concrete matrix contributes to increasing the compressive strength. Moreover, the precipitates in the bio-concrete specimen were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The characterization studies confirm that the precipitated crystals in bio-concrete specimen were CaCO 3 , while no precipitation was observed in the control sample.

  2. Isolation and Characterization of PHA-Producing Bacteria from Propylene Oxide Saponification Wastewater Residual Sludge.

    Science.gov (United States)

    Li, Ruirui; Gu, Pengfei; Fan, Xiangyu; Shen, Junyu; Wu, Yulian; Huang, Lixuan; Li, Qiang

    2018-03-21

    A polyhydroxyalkanoate (PHA)-producing strain was isolated from propylene oxide (PO) saponification wastewater activated sludge and was identified as Brevundimonas vesicularis UJN1 through 16S rDNA sequencing and Biolog microbiological identification. Single-factor and response surface methodology experiments were used to optimize the culture medium and conditions. The optimal C/N ratio was 100/1.04, and the optimal carbon and nitrogen sources were sucrose (10 g/L) and NH 4 Cl (0.104 g/L) respectively. The optimal culture conditions consisted of initial pH of 6.7 and an incubation temperature of 33.4 °C for 48 h, with 15% inoculum and 100 mL medium at an agitation rate of 180 rpm. The PHA concentration reached 34.1% of the cell dry weight and increased three times compared with that before optimization. The only report of PHA-producing bacteria by Brevundimonas vesicularis showed that the conversion rate of PHAs using glucose as the optimal carbon source was 1.67%. In our research, the conversion rate of PHAs with sucrose as the optimal carbon source was 3.05%, and PHA production using sucrose as the carbon source was much cheaper than that using glucose as the carbon source.

  3. Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria.

    Science.gov (United States)

    Wu, Ya-Min; Yang, Jing; Fan, Xiao-Lei; Fu, Shan-Fei; Sun, Meng-Ting; Guo, Rong-Bo

    2017-05-01

    Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 13molh -1 m -3 , which was more 4 times higher than that of MOB without immobilization. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. [Isolation and identification of hydrogen-oxidizing bacteria producing 1-aminocyclopropane-1-carboxylate deaminase and the determination of enzymatic activity].

    Science.gov (United States)

    Fu, Bo; Wang, Weiwei; Tang, Ming; Chen, Xingdu

    2009-03-01

    We used Medicago sativa rhizosphere in Shaanxi province of China to isolate and identify hydrogen-oxidizing bacteria that produced ACC (1-aminocyclopropane-1-carboxylate) deaminase, and then studied the mechanism why they can promote the growth of plants. Hydrogen-oxidizing bacteria were isolated by gas-cycle incubation system. We studied the morphological character, physiological characteristics, 16S rDNA sequence analysis and built the phylogenic tree. Thin layer chromatography was used to isolate the strain that produced ACC deaminase. Ninhydrin reaction was used to test the enzyme activity. In total 37 strains were isolated, 8 of which could oxidize H2 strongly and grow chemolithoautotrophically. We initially identified them as hydrogen-oxidizing bacteria. Only strain WMQ-7 produced ACC deaminase among these 8 strains. Morphological and physiological characteristics analysis showed that strain WMQ-7 was essentially consistent with Pseudomonas putida. The 16S rDNA sequence analysis (GenBank accession number EU807744) suggested that strain WMQ-7 was clustered together with Pseudomonas putida in phylogenetic tree, with the sequence identity of 99%. Based on all these results, strain WMQ-7 was identified as Pseudomonas putida. The enzyme activity of strain WMQ-7 was 0.671 U/microg. A strain producing ACC deaminase was identified and tested.

  5. Biokinetics and bacterial communities of propionate oxidizing bacteria in phased anaerobic sludge digestion systems.

    Science.gov (United States)

    Zamanzadeh, Mirzaman; Parker, Wayne J; Verastegui, Yris; Neufeld, Josh D

    2013-03-15

    Phased anaerobic digestion is a promising technology and may be a potential source of bio-energy production. Anaerobic digesters are widely used for sewage sludge stabilization and thus a better understanding of the microbial process and kinetics may allow increased volatile solids reduction and methane production through robust process operation. In this study, we analyzed the impact of phase separation and operational conditions on the bio-kinetic characteristics and communities of bacteria associated with four phased anaerobic digestion systems. In addition to significant differences between bacterial communities associated with different digester operating temperatures, our results also revealed that bacterial communities in the phased anaerobic digestion systems differed between the 1st and 2nd phase digesters and we identified strong community composition correlations with several measured physicochemical parameters. The maximum specific growth rates of propionate oxidizing bacteria (POB) in the mesophilic and thermophilic 1st phases were 11 and 23.7 mgCOD mgCOD(-1) d(-1), respectively, while those of the mesophilic and thermophilic 2nd-phase digesters were 6.7 and 18.6 mgCOD mgCOD(-1) d(-1), respectively. Hence, the biokinetic characteristics of the POB population were dependent on the digester loading. In addition, we observed that the temperature dependency factor (θ) values were higher for the less heavily loaded digesters as compared to the values obtained for the 1st-phase digesters. Our results suggested the appropriate application of two sets of POB bio-kinetic that reflect the differing growth responses as a function of propionate concentration (and/or organic loading rates). Also, modeling acetogenesis in phased anaerobic sludge digestion systems will be improved considering a population shift in separate phases. On the basis of the bio-kinetic values estimated in various digesters, high levels of propionate in the thermophilic digesters may be

  6. Preparation and characterization of vanadia-titania mixed oxide for immobilization of Serratia rubidaea CCT 5732 and Klebsiella marcescens bacteria

    International Nuclear Information System (INIS)

    Saragiotto Colpini, Leda Maria; Correia Goncalves, Regina A.; Goncalves, Jose Eduardo; Maieru Macedo Costa, Creusa

    2008-01-01

    Vanadia-titania mixed oxide was synthesized by sol-gel method and characterized by several techniques. Texturally, it is formed by mesopores and presents high-specific surface area and controlled porosity. Scanning electron microscopy revealed that vanadium is homogeneously distributed in the material. Structurally, it was possible to identify characteristic V=O stretching bands by IR. The analysis of X-ray diffraction showed that the material, particularly vanadium, is highly dispersed. Application experiments were carried out through the immobilization of Serratia rubidae CCT 5732 and Klebsiella marcescens bacteria by adsorption on the surface of mixed oxide. The micrographies revealed that the bacteria were adsorbed on the entire support, with average surface densities of 8.55 x 10 11 cells/m 2 (Serratia rubidae CCT 5732) and 3.40 x 10 11 cells/m 2 (K. marcescens)

  7. Mtr Extracellular Electron Transfer Pathways in Fe(III)-reducing or Fe(II)-oxidizing Bacteria: A Genomic Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Liang; Rosso, Kevin M.; Zachara, John M.; Fredrickson, Jim K.

    2012-12-01

    Originally discovered in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), the Mtr (i.e., metal-reducing) pathway exists in all characterized strains of metal-reducing Shewanella. The protein components identified to date for the Mtr pathway of MR-1 include four multi-heme c-type cytochromes (c-Cyts), CymA, MtrA, MtrC and OmcA, and a porin-like, outer membrane protein MtrB. They are strategically positioned along the width of the MR-1 cell envelope to mediate electron transfer from the quinone/quinol pool in the inner-membrane to the Fe(III)-containing minerals external to the bacterial cells. A survey of microbial genomes revealed homologues of the Mtr pathway in other dissimilatory Fe(III)-reducing bacteria, including Aeromonas hydrophila, Ferrimonas balearica and Rhodoferax ferrireducens, and in the Fe(II)-oxidizing bacteria Dechloromonas aromatica RCB, Gallionella capsiferriformans ES-2 and Sideroxydans lithotrophicus ES-1. The widespread distribution of Mtr pathways in Fe(III)-reducing or Fe(II)-oxidizing bacteria emphasizes the importance of this type of extracellular electron transfer pathway in microbial redox transformation of Fe. Their distribution in these two different functional groups of bacteria also emphasizes the bi-directional nature of electron transfer reactions carried out by the Mtr pathways. The characteristics of the Mtr pathways may be shared by other pathways used by microorganisms for exchanging electrons with their extracellular environments.

  8. In Situ Bioremediation of 1,4-Dioxane by Methane Oxidizing Bacteria in Coupled Anaerobic-Aerobic Zones

    Science.gov (United States)

    2016-02-11

    FINAL REPORT In Situ Bioremediation of 1,4-Dioxane by Methane Oxidizing Bacteria in Coupled Anaerobic-Aerobic Zones SERDP Project ER-2306...volatile organic compound (CVOCs), ethene and ethane in groundwater at Raritan Arsenal Area 18C after in situ bioremediation . 4 List of...aquifers, the bioremediation approach most commonly used for chlorinated solvents. The ability of methanotrophs to biodegrade 1,4-dioxane was

  9. Development of a simultaneous partial nitrification and anaerobic ammonia oxidation process in a single reactor.

    Science.gov (United States)

    Cho, Sunja; Fujii, Naoki; Lee, Taeho; Okabe, Satoshi

    2011-01-01

    Up-flow oxygen-controlled biofilm reactors equipped with a non-woven fabric support were used as a single reactor system for autotrophic nitrogen removal based on a combined partial nitrification and anaerobic ammonium oxidation (anammox) reaction. The up-flow biofilm reactors were initiated as either a partial nitrifying reactor or an anammox reactor, respectively, and simultaneous partial nitrification and anammox was established by careful control of the aeration rate. The combined partial nitrification and anammox reaction was successfully developed in both biofilm reactors without additional biomass inoculation. The reactor initiated as the anammox reactor gave a slightly higher and more stable mean nitrogen removal rate of 0.35 (±0.19) kg-N m(-3) d(-1) than the reactor initiated as the partial nitrifying reactor (0.23 (±0.16) kg-N m(-3) d(-1)). FISH analysis revealed that the biofilm in the reactor started as the anammox reactor were composed of anammox bacteria located in inner anoxic layers that were surrounded by surface aerobic AOB layers, whereas AOB and anammox bacteria were mixed without a distinguishable niche in the biofilm in the reactor started as the partial nitrifying reactor. However, it was difficult to efficiently maintain the stable partial nitrification owing to inefficient aeration in the reactor, which is a key to development of the combined partial nitrification and anammox reaction in a single biofilm reactor. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Electro-responsive supramolecular graphene oxide hydrogels for active bacteria adsorption and removal

    Science.gov (United States)

    Xue, Bin; Cao, Yi; Wang, Wei

    Bacteria are major contaminations in drinking water and healthcare products. Bacteria contamination may cause severe health problems, including food poisoning and diseases. Currently water sterilization and purification methods to remove contaminated bacteria are mainly based on the size-exclusion mechanism. In order to completely remove all bacteria in water, the pore sizes of the membranes or cartilages should be comparable to the size of bacteria, which inevitable leads to high cross-membrane water pressure and slow purification speed. Moreover, the membranes can easily get clogged. Therefore it is highly demanded to develop efficient methods and novel materials for water purification. Recently, Cui and coworker have introduced a bacteria inactivation method with high efficiency and fast purification speed based on a kind of complex materials made of silver nanofibers, carbon nanotubes and cotton, operating in an electric field. With the help of electric field, the bacteria can be efficiently kill when passing through the membrance even the pore sizes are larger than bacteria. Inspired by their work, here we report a proof-of-principle demonstration of bacteria removal using electro-reponsive hydrogels. This work is funded by Six talent peaks project in Jiangsu Province, the National Natural Science Foundation of China (Nos. 11304156, 11334004, 31170813, 81421091 and 91127026), the 973 Program of China (No. 2012CB921801 and 2013CB834100), the Priority Ac.

  11. High abundance and diversity of nitrite-dependent anaerobic methane-oxidizing bacteria in a paddy field profile.

    Science.gov (United States)

    Zhou, Leiliu; Wang, Yu; Long, Xi-En; Guo, Jianhua; Zhu, Guibing

    2014-11-01

    The discovery of nitrite-dependent anaerobic methane oxidation (n-damo) mediated by 'Candidatus Methylomirabilis oxyfera' with nitrite and methane as substrates has connected biogeochemical carbon and nitrogen cycles in a new way. The paddy fields often carry substantial methane and nitrate, thus may be a favorable habitat for n-damo bacteria. In this paper, the vertical-temporal molecular fingerprints of M. oxyfera-like bacteria, including abundance and community composition, were investigated in a paddy soil core in Jiangyin, near the Yangtze River. Through qPCR investigation, high abundance of M. oxyfera-like bacteria up to 1.0 × 10(8) copies (g d.w.s.)(-1) in summer and 8.5 × 10(7) copies (g d.w.s.)(-1) in winter was observed in the ecotone of soil and groundwater in the paddy soil core, which was the highest in natural environments to our knowledge. In the ecotone, the ratio of M. oxyfera-like bacteria to total bacteria reached peak values of 2.80% in summer and 4.41% in winter. Phylogenetic analysis showed n-damo bacteria in the paddy soil were closely related to M. oxyfera and had high diversity in the soil/groundwater ecotone. All of the results indicated the soil/groundwater ecotone of the Jiangyin paddy field was a favorable environment for the growth of n-damo bacteria. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. Activity and diversity of methane-oxidizing bacteria in glacier forefields on siliceous and calcareous bedrock

    Directory of Open Access Journals (Sweden)

    P. A. Nauer

    2012-06-01

    Full Text Available The global methane (CH4 cycle is largely driven by methanogenic archaea and methane-oxidizing bacteria (MOB, but little is known about their activity and diversity in pioneer ecosystems. We conducted a field survey in forefields of 13 receding Swiss glaciers on both siliceous and calcareous bedrock to investigate and quantify CH4 turnover based on soil-gas CH4 concentration profiles, and to characterize the MOB community by sequencing and terminal restriction fragment length polymorphism (T-RFLP analysis of pmoA. Methane turnover was fundamentally different in the two bedrock categories. Of the 36 CH4 concentration profiles from siliceous locations, 11 showed atmospheric CH4 consumption at concentrations of ~1–2 μL L−1 with soil-atmosphere CH4 fluxes of –0.14 to –1.1 mg m−2 d−1. Another 11 profiles showed no apparent activity, while the remaining 14 exhibited slightly increased CH4 concentrations of ~2–10 μL L−1 , most likely due to microsite methanogenesis. In contrast, all profiles from calcareous sites suggested a substantial, yet unknown CH4 source below our sampling zone, with soil-gas CH4 concentrations reaching up to 1400 μL L−1. Remarkably, most soils oxidized ~90 % of the deep-soil CH4, resulting in soil-atmosphere fluxes of 0.12 to 31 mg m−2 d−1. MOB showed limited diversity in both siliceous and calcareous forefields: all identified pmoA sequences formed only 5 operational taxonomic units (OTUs at the species level and, with one exception, could be assigned to either Methylocystis or the as-yet-uncultivated Upland Soil Cluster γ (USCγ. The latter dominated T-RFLP patterns of all siliceous and most calcareous samples, while Methylocystis dominated in 4 calcareous samples. Members of Upland Soil

  13. 3,4-Dimethylpyrazole phosphate (DMPP) reduces activity of ammonia oxidizers without adverse effects on non-target soil microorganisms and functions

    DEFF Research Database (Denmark)

    Kong, Xianwang; Duan, Yun-Feng (Kevin); Schramm, Andreas

    2016-01-01

    , dehydrogenase activity, phospholipid fatty acid composition and potential ammonia oxidation. DMPP showed no significant nontarget effects (p > 0.05), but a possible stress response in HD was indicated by a factor analysis of phospholipid fatty acid composition. There was a strong DMPP inhibition on potential...... of ammonia oxidation. We investigated effects of DMPP amendment equivalent to 0 (Control), 1 (regular dose, RD) or 10 (high dose, HD) kg ha1 in a sandy loam grassland soil at 50% water-filled pore space. Following incubation for 1, 7 or 14 d, soil was analyzed for fluorescein diacetate hydrolysis...... ammonia oxidation which was still significant (p HD after 14 d. In separate treatments receiving 50 mg NH4 +-N kg1 dry soil in addition to DMPP, the inhibition of nitrate accumulation was similar in RD and HD at around 75%. Abundances of the gene amoA from ammonia oxidizing bacteria (AOB...

  14. Fluctuations in ammonia oxidizing communities across agricultural soils are driven by soil structure and pH

    Directory of Open Access Journals (Sweden)

    Michele C ePereira e Silva

    2012-03-01

    Full Text Available The milieu in soil in which microorganisms dwell is never constant. Conditions such as temperature, water availability, pH and nutrients frequently change, impacting the overall functioning of the soil system. To understand the effects of such factors on soil functioning, proxies (indicators of soil function are needed that, in a sensitive manner, reveal normal amplitude of variation. Thus, the so-called normal operating range (NOR of soil can be defined. In this study we determined different components of nitrification by analyzing, in eight agricultural soils, how the community structures and sizes of ammonia oxidizing bacteria and archaea (AOB and AOA, respectively, and their activity, fluctuate over spatial and temporal scales. The results indicated that soil pH and soil type are the main factors that influence the size and structure of the AOA and AOB, as well as their function. The nitrification rates varied between 0.11 ± 0.03 µgN.h-1.gdw-1 and 1.68 ± 0.11 µgN.h-1.gdw-1, being higher in soils with higher clay content (1.09 ± 0.12 µgN.h-1.gdw-1 and lower in soils with lower clay percentages (0.27 ± 0.04 µgN.h-1.gdw-1. Nitrifying activity was driven by soil pH, mostly related to its effect on AOA but not on AOB abundance. Regarding the influence of soil parameters, clay content was the main soil factor shaping the structure of both the AOA and AOB communities. Overall, the potential nitrifying activities were higher and more variable over time in the clayey than in the sandy soils. Whereas the structure of AOB fluctuated more (62.7 ± 2.10% the structure of AOA communities showed lower amplitude of variation (53.65 ± 3.37%. Similar trends were observed for the sizes of these communities. The present work represents a first step towards defining a NOR for soil nitrification. Moreover, the clear effect of soil texture established here suggests that the NOR should be defined in a soil-type-specific manner.

  15. Dynamics of nitrification and denitrification in root- oxygenated sediments and adaptation of ammonia-oxidizing bacteria to low-oxygen or anoxic habitats

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Libochant, J.A.; Blom, C.W.P.M.; Laanbroek, H.J.

    1996-01-01

    Oxygen-releasing plants may provide aerobic niches in anoxic sediments and soils for ammonia-oxidizing bacteria, The oxygen- releasing, aerenchymatous emergent macrophyte Glycerin maxima had a strong positive effect on numbers and activities of the nitrifying bacteria in its root zone in spring and

  16. Dynamics of nitrification and denitrification in root- oxygenated sediments and adaptation of ammonia-oxidizing bacteria to low-oxygen or anoxic habitats

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Libochant, J.A.; Blom, C.W.P.M.; Laanbroek, H.J.

    1996-01-01

    Oxygen-releasing plants may provide aerobic niches in anoxic sediments and soils for ammonia-oxidizing bacteria. The oxygen-releasing, aerenchymatous emergent macrophyte Glyceria maxima had a strong positive effect on numbers and activities of the nitrifying bacteria in its root zone in spring and

  17. Quantitative analysis of O-2 and Fe2+ profiles in gradient tubes for cultivation of microaerophilic Iron(II)-oxidizing bacteria

    DEFF Research Database (Denmark)

    Lueder, U.; Druschel, G.; Emerson, D.

    2018-01-01

    The classical approach for the cultivation of neutrophilic microaerophilic Fe(II)-oxidizing bacteria is agar-based gradient tubes where these bacteria find optimal growth conditions in opposing gradients of oxygen (O-2) and dissolved Fe(II) (Fe2+). The goals of this study were to quantify...... imply that transfer of cultures to fresh tubes within 48-72 h is crucial to provide optimal growth conditions for microaerophilic Fe(II)-oxidizers, particularly for the isolation of new strains....

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

    Directory of Open Access Journals (Sweden)

    Ziye eHu

    2014-07-01

    Full Text Available 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.

  19. Identification of anaerobic arsenite-oxidizing and arsenate-reducing bacteria associated with an alkaline saline lake in Khovsgol, Mongolia.

    Science.gov (United States)

    Hamamura, Natsuko; Itai, Takaaki; Liu, Yitai; Reysenbach, Anna-Louise; Damdinsuren, Narantuya; Inskeep, William P

    2014-10-01

    Microbial arsenic transformation pathways associated with a saline lake located in northern Mongolia were examined using molecular biological and culturing approaches. Bacterial 16S rRNA gene sequences recovered from saline lake sediments and soils were affiliated with haloalkaliphiles, including Bacillus and Halomonas spp. Diverse sequences of arsenate respiratory reductase (arrA) and a new group of arsenite oxidase (arxA) genes were also identified. Pure cultures of arsenate-reducing Nitrincola strain and anaerobic arsenite-oxidizing Halomonas strain were isolated. The chemoorganotrophic Halomonas strain contains arxA gene similar to that of a chemoautotrophic arsenite-oxidizing Alkalilimnicola ehrlichii strain MLHE-1. These results revealed the diversity of arsenic transformation pathways associated with a geographically distinct saline system and the potential contribution of arx-dependent arsenite oxidation by heterotrophic bacteria.

  20. Enrichment and cultivation of a sulfide-oxidizing bacteria consortium for its deploying in full-scale biogas desulfurization

    International Nuclear Information System (INIS)

    González Sánchez, Armando; Flores Márquez, Trinidad Eliseo; Revah, Sergio; Morgan Sagastume, Juan Manuel

    2014-01-01

    Operational experiences and strategies to get suitable chemolithoautotrophic sulfide-oxidizing biomass from activated sludge wastewater treatment plant for its deploying in a full-scale biogas desulfurization plant are described. An economic nutrient source was applied to foster microbial selection and rapid growth. Respirometry was implemented on full-scale installations to monitor the ability of the specialized bacteria consortium to oxidize reduced sulfur i.e. H 2 S. During the deployment in the full-scale desulfurization reactor, intermittent sulfide feed from biogas scrubbing was performed to accelerate the startup the desulfurization process. - Highlights: • A simple method for reaching high amounts of specialized sulfide-oxidizing bacterial consortium from activated sludge was developed. • The full-scale desulfurization process can be continuously monitored by respirometry allowing fast decision making if problems arise. • The dissolved sulfide concentration was estimated with an empirical correlation between measurements of ORP, dissolved oxygen and pH

  1. Dynamic transition of chemolithotrophic sulfur-oxidizing bacteria in response to amendment with nitrate in deposited marine sediments

    Directory of Open Access Journals (Sweden)

    Tomo eAoyagi

    2015-05-01

    Full Text Available Although environmental stimuli are known to affect the structure and function of microbial communities, their impact on the metabolic network of microorganisms has not been well investigated. Here, geochemical analyses, high-throughput sequencing of 16S rRNA genes and transcripts, and isolation of potentially relevant bacteria were carried out to elucidate the anaerobic respiration processes stimulated by nitrate (20 mM amendment of marine sediments. Marine sediments deposited by the Great East Japan Earthquake in 2011 were incubated anaerobically in the dark at 25°C for 5 days. Nitrate in slurry water decreased gradually for 2 days, then more rapidly until its complete depletion at day 5; production of N2O followed the same pattern. From day 2 to 5, the sulfate concentration increased and the sulfur content in solid-phase sediments significantly decreased. These results indicated that denitrification and sulfur oxidation occurred simultaneously. Illumina sequencing revealed the proliferation of known sulfur oxidizers, i.e., Sulfurimonas spp. and Chromatiales bacteria, which accounted for approximately 43.5% and 14.8% of the total population at day 5, respectively. They also expressed 16S rRNA to a considerable extent, whereas the other microorganisms, e.g., iron(III reducers and methanogens, became metabolically active at the end of the incubation. Extinction dilution culture in a basal-salts medium supplemented with sulfur compounds and nitrate successfully isolated the predominant sulfur oxidizers: Sulfurimonas sp. strain HDS01 and Thioalkalispira sp. strain HDS22. Their 16S rRNA genes showed 95.2−96.7% sequence similarity to the closest cultured relatives and they grew chemolithotrophically on nitrate and sulfur. Novel sulfur-oxidizing bacteria were thus directly involved in carbon fixation under nitrate-reducing conditions, activating anaerobic respiration processes and the reorganization of microbial communities in the deposited marine

  2. Molecular Analysis of Ammonia-Oxidizing Bacteria of the β Subdivision of the Class Proteobacteria in Compost and Composted Materials

    Science.gov (United States)

    Kowalchuk, George A.; Naoumenko, Zinaida S.; Derikx, Piet J. L.; Felske, Andreas; Stephen, John R.; Arkhipchenko, Irina A.

    1999-01-01

    Although the practice of composting animal wastes for use as biofertilizers has increased in recent years, little is known about the microorganisms responsible for the nitrogen transformations which occur in compost and during the composting process. Ammonia is the principle available nitrogenous compound in composting material, and the conversion of this compound to nitrite in the environment by chemolithotrophic ammonia-oxidizing bacteria is an essential step in nitrogen cycling. Therefore, the distribution of ammonia-oxidizing members of the β subdivision of the class Proteobacteria in a variety of composting materials was assessed by amplifying 16S ribosomal DNA (rDNA) and 16S rRNA by PCR and reverse transcriptase PCR (RT-PCR), respectively. The PCR and RT-PCR products were separated by denaturing gradient gel electrophoresis (DGGE) and were identified by hybridization with a hierarchical set of oligonucleotide probes designed to detect ammonia oxidizer-like sequence clusters in the genera Nitrosospira and Nitrosomonas. Ammonia oxidizer-like 16S rDNA was detected in almost all of the materials tested, including industrial and experimental composts, manure, and commercial biofertilizers. A comparison of the DGGE and hybridization results after specific PCR and RT-PCR suggested that not all of the different ammonia oxidizer groups detected in compost are equally active. amoA, the gene encoding the active-site-containing subunit of ammonia monooxygenase, was also targeted by PCR, and template concentrations were estimated by competitive PCR. Detection of ammonia-oxidizing bacteria in the composts tested suggested that such materials may not be biologically inert with respect to nitrification and that the fate of nitrogen during composting and compost storage may be affected by the presence of these organisms. PMID:9925559

  3. Response to UVB radiation and oxidative stress of marine bacteria isolated from South Pacific Ocean and Mediterranean Sea.

    Science.gov (United States)

    Matallana-Surget, S; Villette, C; Intertaglia, L; Joux, F; Bourrain, M; Lebaron, P

    2012-12-05

    Marine bacterial strains isolated from South Pacific and Mediterranean Sea were studied for their resistance to UVB radiation, their repair capacity under photoreactivating light, as well as their oxidative stress response using concentrated hydrogen peroxide (H(2)O(2)), as an oxidizer. A total of 30 marine bacteria were isolated from the hyper-oligotrophic waters of the South Pacific Gyre to the eutrophic waters of the Chilean coast during the BIOSOPE cruise (2004), and 10 strains from surface Mediterranean coastal waters. One third of bacteria presented a high resistance to UVB and almost all isolates presented an efficient post-irradiation recovery. Only few strains showed cell survival to high concentration of H(2)O(2). No correlation between the sampling sites and the bacterial UVB resistance was observed. Two marine bacteria, Erythrobacter flavus and Ruegeria mobilis, were of particular interest, presenting a good response to the three parameters (UVB and H(2)O(2) resistance/efficient repair). Unexpectedly, two resistant strains were again identified as Ruegeria species underlining that this geographically widespread genus, resist to UVB regardless the environment from which the isolates originate. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Simultaneous enrichment of denitrifying anaerobic methane-oxidizing microorganisms and anammox bacteria in a hollow-fiber membrane biofilm reactor.

    Science.gov (United States)

    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. Microbiological oxidation of antimony(III) with oxygen or nitrate by bacteria isolated from contaminated mine sediments

    Science.gov (United States)

    Terry, Lee R.; Kulp, Thomas R.; Wiatrowski, Heather A.; Miller, Laurence G.; Oremland, Ronald S.

    2015-01-01

    Bacterial oxidation of arsenite [As(III)] is a well-studied and important biogeochemical pathway that directly influences the mobility and toxicity of arsenic in the environment. In contrast, little is known about microbiological oxidation of the chemically similar anion antimonite [Sb(III)]. In this study, two bacterial strains, designated IDSBO-1 and IDSBO-4, which grow on tartrate compounds and oxidize Sb(III) using either oxygen or nitrate, respectively, as a terminal electron acceptor, were isolated from contaminated mine sediments. Both isolates belonged to the Comamonadaceae family and were 99% similar to previously described species. We identify these novel strains as Hydrogenophagataeniospiralis strain IDSBO-1 and Variovorax paradoxus strain IDSBO-4. Both strains possess a gene with homology to the aioA gene, which encodes an As(III)-oxidase, and both oxidize As(III) aerobically, but only IDSBO-4 oxidized Sb(III) in the presence of air, while strain IDSBO-1 could achieve this via nitrate respiration. Our results suggest that expression of aioA is not induced by Sb(III) but may be involved in Sb(III) oxidation along with an Sb(III)-specific pathway. Phylogenetic analysis of proteins encoded by the aioA genes revealed a close sequence similarity (90%) among the two isolates and other known As(III)-oxidizing bacteria, particularly Acidovorax sp. strain NO1. Both isolates were capable of chemolithoautotrophic growth using As(III) as a primary electron donor, and strain IDSBO-4 exhibited incorporation of radiolabeled [14C]bicarbonate while oxidizing Sb(III) from Sb(III)-tartrate, suggesting possible Sb(III)-dependent autotrophy. Enrichment cultures produced the Sb(V) oxide mineral mopungite and lesser amounts of Sb(III)-bearing senarmontite as precipitates.

  6. A novel surface-enhanced Raman scattering (SERS) detection for natural gas exploration using methane-oxidizing bacteria.

    Science.gov (United States)

    Liang, Weiwei; Chen, Qiao; Peng, Fang; Shen, Aiguo; Hu, Jiming

    2018-07-01

    Methane-oxidizing bacteria (MOB), a unique group of Gram-negative bacteria utilizing methane as a sole source of carbon and energy, have been proved to be a biological indicator for gas prospecting. Field and cultivation-free detection of MOB is important but still challenging in current microbial prospecting of oil and gas (MPOG) system. Herein, SERS was used for the first time to our knowledge to investigate two species of methanotrophs and four closely relevant bacteria that universally coexisted in the upper soil of natural gas. A special but very simple approach was utilized to make silver nanoparticles (Ag NPs) sufficiently contact with every single bacterial cell, and highly strong and distinct Raman signals free from any native fluorescence have been obtained, and successfully utilized for distinguishing MOB from other species. A more convincing multi-Raman criterion based on single Raman bands, and further the entire Raman spectrum in combination with statistical analysis (e.g., principal component analysis (PCA)), which were found capable of classifying MOB related bacterial cells in soil with an accuracy of 100%. This study therefore demonstrated sensitive and rapid SERS measurement technique accompanied by complete Raman database of various gas reservoirs related bacteria could aid field exploration of natural gas reservoir. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Current advances in molecular methods for detection of nitrite-dependent anaerobic methane oxidizing bacteria in natural environments.

    Science.gov (United States)

    Chen, Jing; Dick, Richard; Lin, Jih-Gaw; Gu, Ji-Dong

    2016-12-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) process uniquely links microbial nitrogen and carbon cycles. Research on n-damo bacteria progresses quickly with experimental evidences through enrichment cultures. Polymerase chain reaction (PCR)-based methods for detecting them in various natural ecosystems and engineered systems play a very important role in the discovery of their distribution, abundance, and biodiversity in the ecosystems. Important characteristics of n-damo enrichments were obtained and their key significance in microbial nitrogen and carbon cycles was investigated. The molecular methods currently used in detecting n-damo bacteria were comprehensively reviewed and discussed for their strengths and limitations in applications with a wide range of samples. The pmoA gene-based PCR primers for n-damo bacterial detection were evaluated and, in particular, several incorrectly stated PCR primer nucleotide sequences in the published papers were also pointed out to allow correct applications of the PCR primers in current and future investigations. Furthermore, this review also offers the future perspectives of n-damo bacteria based on current information and methods available for a better acquisition of new knowledge about this group of bacteria.

  8. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria

    OpenAIRE

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-01-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the p...

  9. Mobilization of manganese by basalt associated Mn(II)-oxidizing bacteria from the Indian Ridge System

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; Mourya, B.S.; Krishnamurthi, S.; Meena, R.M.; LokaBharathi, P.A.

    The Indian Ridge System basalt bearing Mn-oxide coatings had todorokite as the major and birnesite as the minor mineral. We posit that microorganisms associated with these basalts participate in the oxidation of Mn and contribute to mineral...

  10. Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

    International Nuclear Information System (INIS)

    Li, F.B.; Li, X.M.; Zhou, S.G.; Zhuang, L.; Cao, F.; Huang, D.Y.; Xu, W.; Liu, T.X.; Feng, C.H.

    2010-01-01

    The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (α-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of α-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe 2+ + α-FeOOH and the system of DIRB + α-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of α-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

  11. Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, F.B., E-mail: cefbli@soil.gd.c [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Li, X.M. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhou, S.G.; Zhuang, L. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Cao, F. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Huang, D.Y.; Xu, W.; Liu, T.X. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Feng, C.H. [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China)

    2010-05-15

    The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (alpha-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of alpha-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe{sup 2+} + alpha-FeOOH and the system of DIRB + alpha-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of alpha-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

  12. Community Composition of Nitrous Oxide Consuming Bacteria in the Oxygen Minimum Zone of the Eastern Tropical South Pacific

    Directory of Open Access Journals (Sweden)

    Xin Sun

    2017-06-01

    Full Text Available The ozone-depleting and greenhouse gas, nitrous oxide (N2O, is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA and transcriptionally active (RNA nitrous oxide reductase (nosZ genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments. In addition to nosZ genes related to those of known marine denitrifiers, atypical nosZ genes, related to those of soil bacteria that do not possess a complete denitrification pathway, were also detected, especially in surface waters. The community composition of the total nosZ assemblage was significantly different from the active assemblage. The community composition of the total nosZ assemblage was significantly different between coastal and off-shore stations. The low oxygen assemblages from both stations were similar to each other, while the higher oxygen assemblages were more variable. Community composition of the active nosZ assemblage was also significantly different between stations, and varied with N2O concentration but not O2. Notably, nosZ assemblages were not only present but also active in oxygenated seawater: the abundance of total and active nosZ bacteria from oxygenated surface water (indicated by nosZ gene copy number was similar to or even larger than in anoxic waters, implying the potential for N2O consumption even in the oxygenated surface water.

  13. Community Composition of Nitrous Oxide Consuming Bacteria in the Oxygen Minimum Zone of the Eastern Tropical South Pacific

    Science.gov (United States)

    Sun, Xin; Jayakumar, Amal; Ward, Bess B.

    2017-01-01

    The ozone-depleting and greenhouse gas, nitrous oxide (N2O), is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA) and transcriptionally active (RNA) nitrous oxide reductase (nosZ) genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments. In addition to nosZ genes related to those of known marine denitrifiers, atypical nosZ genes, related to those of soil bacteria that do not possess a complete denitrification pathway, were also detected, especially in surface waters. The community composition of the total nosZ assemblage was significantly different from the active assemblage. The community composition of the total nosZ assemblage was significantly different between coastal and off-shore stations. The low oxygen assemblages from both stations were similar to each other, while the higher oxygen assemblages were more variable. Community composition of the active nosZ assemblage was also significantly different between stations, and varied with N2O concentration but not O2. Notably, nosZ assemblages were not only present but also active in oxygenated seawater: the abundance of total and active nosZ bacteria from oxygenated surface water (indicated by nosZ gene copy number) was similar to or even larger than in anoxic waters, implying the potential for N2O consumption even in the oxygenated surface water. PMID:28702012

  14. Ammonia oxidation driven by archaea rather than bacteria in the hot spring at Tengchong geothermal field, China.

    Science.gov (United States)

    Chen, Shun; Peng, Xiaotong; Xu, Hengchao; Li, Jiwei; Ta, Kaiwen

    2015-04-01

    The occurrence of microbial mediated ammonia oxidation and these organisms are present in large numbers in natural environments indicated a potential biogeochemical role for them in the global nitrogen cycle. However, very little is understood about their role and contribution to nitrification in the high temperature extreme environments. Here we explore the ammonia oxidation rates and abundance of potential ammonia-oxidizing archaea (AOA) in upper and bottom sediments from Gongxiaoshe hot spring, Tengchong, Yunnan, China. The 15N-incorporating AOA cells and cell aggregated were detected with Fluorescence in situ hybridization (FISH) and Nano secondary ion mass spectrometry (Nano-SIMS). Ammonia oxidation rates measured using 15N-NO3- pool dilution in upper and bottom sediments (without NH4+ stimulated) were 4.8 and 5.3 nmol N g-1h-1, respectively. Close relatives of the autotrophic, ammonia-oxidizing archaeon 'Candidatus Nitrosocaldus yellowstonii' represented the most abundant OTU in both of the two spring sediments by 16S rRNA gene analysis. Furthermore, it should be noted that no ammonia-oxidizing bacterial clones detected in this study. Quantitative PCR (qPCR) indicated that AOA and 16S rRNA genes were present at 2.75-9.80×105 and 0.128-1.96×108 gene copies g-1 sediment. Based on the reaction rates and AOA abundance, we estimated the cell-specific nitrification rates were 0.41 to 0.79 fmol N archaeal cell-1 h-1, which are comparable to those observed in estuary environment. We suggest that AOA have the responsibility in nitrification in this hot spring, and these archaea rather than bacteria may be considered as a driver in nitrogen cycling in terrestrial hot ecosystems. Key words: ammonia-oxidizing archaea (AOA); nitrification; ammonia-oxidizing rate; hot spring;

  15. Investigation of Combination Effect of Magnesium Oxide and Iron Oxide Nanoparticles on the Growth And Morphology of the Bacteria Staphylococcus Aureus and Escherichia Coli in Juice

    Directory of Open Access Journals (Sweden)

    mahdi torabi zarchi

    2017-02-01

    Full Text Available Introduction: Nanoparticles (NPs are one of the antibacterial substances, among them nanoparticles type MgO and Fe2O3 are less toxic to mammalian cells. So, the aim of this study was investigation of combination effects of iron oxide and magnesium oxide nanoparticles on the growth of Staphylococcus aureus and Escherichia coli (E.coli to achieve the optimum combination of nanoparticles inhibit the growth of Staphylococcus aureus and Escherichia coli in food (juice. Methods: In this experimental research, the effect of MgO and Fe2O3 Nanoparticles compound on Staphylococcus aureus and Escherichia coli bacteria in liquid environment was investigated, and then their effect was investigated separately in juices of carrot, pomegranate and apple via colony count approach. Also, scanning electron microscopy was used to characterize the morphological changes of Staphylococcus aureus and Escherichia coli after antimicrobial treatments. The results of the research were analyzed using one way ANNOVA. Results: The results of the research indicated that in liquid medium, these nanoparticles lead to reduce the growth of both bacteria. compound of 1.5Mg+0.5Fe2O3 was introduced as the most appropriate antibacterial compounds; Staphylococcus aureus sensitivity to Escherichia coli was higher against nanoparticles. The findings of research about the juices revealed that the combined effect of nanoparticles reduced the growth of both bacteria. the combined effect of Fe2o3 and MgO nanoparticles treatments distorted and damaged the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. Conclusion: Nanoparticles in the allowed concentrations have significant effect on Staphylococcus aureus and Escherichia coli bacteria.

  16. Improved enrichment culture technique for methane-oxidizing bacteria from marine ecosystems: the effect of adhesion material and gas composition.

    Science.gov (United States)

    Vekeman, Bram; Dumolin, Charles; De Vos, Paul; Heylen, Kim

    2017-02-01

    Cultivation of microbial representatives of specific functional guilds from environmental samples depends largely on the suitability of the applied growth conditions. Especially the cultivation of marine methanotrophs has received little attention, resulting in only a limited number of ex situ cultures available. In this study we investigated the effect of adhesion material and headspace composition on the methane oxidation activity in methanotrophic enrichments obtained from marine sediment. Addition of sterilized natural sediment or alternatively the addition of acid-washed silicon dioxide significantly increased methane oxidation. This positive effect was attributed to bacterial adhesion on the particles via extracellular compounds, with a minimum amount of particles required for effect. As a result, the particles were immobilized, thus creating a stratified environment in which a limited diffusive gas gradients could build up and various microniches were formed. Such diffusive gas gradient might necessitate high headspace concentrations of CH 4 and CO 2 for sufficient concentrations to reach the methane-oxidizing bacteria in the enrichment culture technique. Therefore, high concentrations of methane and carbon dioxide, in addition to the addition of adhesion material, were tested and indeed further stimulated methane oxidation. Use of adhesion material in combination with high concentrations of methane and carbon dioxide might thus facilitate the cultivation and subsequent enrichment of environmentally important members of this functional guild. The exact mechanism of the observed positive effects on methane oxidation and the differential effect on methanotrophic diversity still needs to be explored.

  17. Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

    Directory of Open Access Journals (Sweden)

    Azam A

    2012-12-01

    Full Text Available Ameer Azam,1,2 Arham S Ahmed,2 Mohammad Oves,3 Mohammad S Khan,3 Sami S Habib,1 Adnan Memic11Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Centre of Excellence in Materials Science (Nanomaterials, 3Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaBackground: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria.Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3 were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa and Gram-positive (Staphylococcus aureus and Bacillus subtilis bacteria.Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3

  18. Characterization of specific membrane fatty acids as chemotaxonomic markers for sulfate-reducing bacteria involved in anaerobic oxidation of methane

    DEFF Research Database (Denmark)

    Elvert, M.; Boetius, A.; Knittel, K.

    2003-01-01

    Membrane fatty acids were extracted from a sediment core above marine gas hydrates at Hydrate Ridge, NE Pacific. Anaerobic sediments from this environment are characterized by high sulfate reduction rates driven by the anaerobic oxidation of methane (AOM). The assimilation of methane carbon......-reducing bacteria (SRB) of the Desulfosarcina/Desulfococcus group, which are present in the aggregates of AOM consortia in extremely high numbers, these specific fatty acids appear to provide a phenotypic fingerprint indicative for SRB of this group. Correlating depth profiles of specific fatty acid content...

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

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2006-01-01

    to unvegetated sediment, especially with respect to the availability of oxygen, organic carbon, and inorganic nitrogen. We hypothesize that macrophyte species create specific niches for ammonia oxidizing and nitrate-reducing bacteria in their rhizosphere, leading to plant-dependant differences in abundance...... dortmanna have been shown to release oxygen from their roots and to stimulate nitrification and coupled nitrification-denitrification in the rhizosphere. Together with the excretion of root exudates, this effect leads to strongly modified microenvironments at the root surface and in the rhizosphere compared......-denitrification using the 15N isotope pairing technique. Ammonia-oxidizing and nitrate-reducing populations are analyzed based on the ammonia monooxygenase gene (amoA) and the nitrate reductase gene (narG) as functional markers. Preliminary data indicate that there in fact exist differences in the community composition...

  20. Presence, distribution, and diversity of iron-oxidizing bacteria at a landfill leachate-impacted groundwater surface water interface

    DEFF Research Database (Denmark)

    Yu, R.; Gan, P.; Mackay, A.A.

    2010-01-01

    ) were dominated by members of the Bradyrhizobiaceae and Comamonadaceae; clones from the deeper sediments were phylogenetically more diverse, dominated by members of the Rhodocyclaceae. The iron deposition profiles indicated that active iron oxidation occurred only within the near-to-surface GSI......We examined the presence of iron-oxidizing bacteria (IOB) at a groundwater surface water interface (GSI) impacted by reduced groundwater originating as leachate from an upgradient landfill. IOB enrichments and quantifications were obtained, at high vertical resolution, by an iron/oxygen opposing...... site mirrored the IOB distribution. Clone libraries from two separate IOB enrichments indicated a stratified IOB community with clear differences at short vertical distances. Alpha- and Betaproteobacteria were the dominant phylotypes. Clones from the near-surface sediment (1-2 cm below ground surface...

  1. Bio-Reduction of Graphene Oxide Using Sulfate-Reducing Bacteria and Its Implication on Anti-Biocorrosion.

    Science.gov (United States)

    Song, Tian-Shun; Tan, Wei-Min; Xie, Jingjing

    2018-08-01

    In this paper, we developed an environmental friendly, cost effective, simple and green approach to reduce graphene oxide (GO) by a sulfate-reducing bacterium Desulfovibrio desulfuricans. The D. desulfuricans reduces exfoliated GO to reduced graphene oxide (rGO) at 25 °C in an aqueous solution without any toxic and environmentally harmful reducing agents. The rGO was characterized with X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscope, X-ray Photoelectron Spectroscopy and Raman Spectroscopy. The analysis results showed that rGO had excellent properties and multi-layer graphene sheets structure. Furthermore, we demonstrated that D. desulfuricans, one of the primary bacteria responsible for the biocorrosion of various metals, might reduce GO to rGO on the surface of copper and prevented the corrosion of copper, which confirmed that electrophoretic deposition of GO on the surface of metals had great potential on the anti-biocorrosion applications.

  2. Effect of Gaseous Ozone Exposure on the Bacteria Counts and Oxidative Properties of Ground Hanwoo Beef at Refrigeration Temperature.

    Science.gov (United States)

    Cho, Youngjae; Muhlisin; Choi, Ji Hye; Hahn, Tae-Wook; Lee, Sung Ki

    2014-01-01

    This study was designed to elucidate the effect of ozone exposure on the bacteria counts and oxidative properties of ground Hanwoo beef contaminated with Escherichia coli O157:H7 at refrigeration temperature. Ground beef was inoculated with 7 Log CFU/g of E. coli O157:H7 isolated from domestic pigs and was then subjected to ozone exposure (10×10(-6) kg O3 h(-1)) at 4℃ for 3 d. E. coli O157:H7, total aerobic and anaerobic bacterial growth and oxidative properties including instrumental color changes, TBARS, catalase (CAT) and glutathione peroxidase (GPx) activity were evaluated. Ozone exposure significantly prohibited (pgenerator inside a refrigerator. Further studies regarding the ozone concentrations and exposure times are needed.

  3. Nitrous oxide production in soil isolates of nitrate-ammonifying bacteria

    NARCIS (Netherlands)

    Streminska, M.A.; Felgate, H.; Rowley, G.; Richardson, D.J.; Baggs, E.M.

    2012-01-01

    Here we provide the first demonstration of the potential for N2O production by soil-isolated nitrate-ammonifying bacteria under different C and N availabilities, building on characterizations informed from model strains. The potential for soil-isolated Bacillus sp. and Citrobacter sp. to reduce

  4. Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments

    Directory of Open Access Journals (Sweden)

    François eThomas

    2014-06-01

    Full Text Available Salt marshes are highly productive ecosystems hosting an intense sulfur (S cycle, yet little is known about S-oxidizing microorganisms in these ecosystems. Here, we studied the diversity and transcriptional activity of S-oxidizers in salt marsh sediments colonized by the plant Spartina alterniflora, and assessed variations with sediment depth and small-scale compartments within the rhizosphere. We combined next-generation amplicon sequencing of 16S rDNA and rRNA libraries with phylogenetic analyses of marker genes for two S-oxidation pathways (soxB and rdsrAB. Gene and transcript numbers of soxB and rdsrAB phylotypes were quantified simultaneously, using newly designed (RT-qPCR assays. We identified a diverse assemblage of S-oxidizers, with Chromatiales and Thiotrichales being dominant. The detection of transcripts from S-oxidizers was mostly confined to the upper 5 cm sediments, following the expected distribution of root biomass. A common pool of species dominated by Gammaproteobacteria transcribed S-oxidation genes across roots, rhizosphere, and surrounding sediment compartments, with rdsrAB transcripts prevailing over soxB. However, the root environment fine-tuned the abundance and transcriptional activity of the S-oxidizing community. In particular, the global transcription of soxB was higher on the roots compared to mix and rhizosphere samples. Furthermore, the contribution of Epsilonproteobacteria-related S-oxidizers tended to increase on Spartina roots compared to surrounding sediments. These data shed light on the under-studied oxidative part of the sulfur cycle in salt marsh sediments and indicate small-scale heterogeneities are important factors shaping abundance and potential activity of S-oxidizers in the rhizosphere.

  5. Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus Nitrospira

    DEFF Research Database (Denmark)

    Koch, Hanna; Lücker, Sebastian; Albertsen, Mads

    2015-01-01

    , we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia...... oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers...

  6. Nitrous oxide emission related to ammonia-oxidizing bacteria and mitigation options from N fertilization in a tropical soil

    NARCIS (Netherlands)

    Soares, Johnny R.; Cassman, N.; Kielak, A.M.; Pijl, A.S.; do Carmo, J.B.; Lourenço, Késia S.; Laanbroek, H.J.; Cantarella, H.; Kuramae, E.E.

    2016-01-01

    Nitrous oxide (N2O) from nitrogen fertilizers applied to sugarcane has high environmental impact on ethanol production. This study aimed to determine the main microbial processes responsible for the N2O emissions from soil fertilized with different N sources, to identify options to mitigate N2O

  7. Iron oxides in acid mine drainage environments and their association with bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Ferris, F G; Tazaki, K; Fyfe, W S

    1989-01-20

    A variety of iron oxides were identified by X-ray diffraction in sediments receiving acid drainage from mine tailing and coal refuse impoundments. Small amounts of goethite and hematite were found in the sediment samples. However, the major iron oxide species was ferrihydrite which gave diffuse diffraction bands at angles corresponding to d2.5, 2.2 and 1.5 Angstrom. Main core line binding energies in Fe (2p) and O (1s) X-ray photoelectron spectra were consistent with the hydrous nature and predominance of ferrihydrite. Electron microscopy and energy-dispersive X-ray spectroscopy also showed that individual bacterial cells promoted the development of iron oxide mineralization. The bacterial associated iron oxides were similar to those in the bulk sediment samples, and exhibited structures conforming to the presence of chemisorbed sulfate or silicate anions. 23 refs., 3 figs.

  8. Nitrous oxide metabolism in nitrate-reducing bacteria: Physiology and regulatory mechanisms

    OpenAIRE

    Torres, Maria; Simon, Jorg; Rowley, Gary; Bedmar, Eulogio; Richardson, David; Gates, Andrew; Delgado, Maria

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nit- ric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the appli- cation of synthetic nitrogen-containing fertilizers. Thus, mitigation stra...

  9. Identification of Novel Methane-, Ethane-, and Propane-Oxidizing Bacteria at Marine Hydrocarbon Seeps by Stable Isotope Probing ▿ †

    Science.gov (United States)

    Redmond, Molly C.; Valentine, David L.; Sessions, Alex L.

    2010-01-01

    Marine hydrocarbon seeps supply oil and gas to microorganisms in sediments and overlying water. We used stable isotope probing (SIP) to identify aerobic bacteria oxidizing gaseous hydrocarbons in surface sediment from the Coal Oil Point seep field located offshore of Santa Barbara, California. After incubating sediment with 13C-labeled methane, ethane, or propane, we confirmed the incorporation of 13C into fatty acids and DNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis and sequencing of the 16S rRNA and particulate methane monooxygenase (pmoA) genes in 13C-DNA revealed groups of microbes not previously thought to contribute to methane, ethane, or propane oxidation. First, 13C methane was primarily assimilated by Gammaproteobacteria species from the family Methylococcaceae, Gammaproteobacteria related to Methylophaga, and Betaproteobacteria from the family Methylophilaceae. Species of the latter two genera have not been previously shown to oxidize methane and may have been cross-feeding on methanol, but species of both genera were heavily labeled after just 3 days. pmoA sequences were affiliated with species of Methylococcaceae, but most were not closely related to cultured methanotrophs. Second, 13C ethane was consumed by members of a novel group of Methylococcaceae. Growth with ethane as the major carbon source has not previously been observed in members of the Methylococcaceae; a highly divergent pmoA-like gene detected in the 13C-labeled DNA may encode an ethane monooxygenase. Third, 13C propane was consumed by members of a group of unclassified Gammaproteobacteria species not previously linked to propane oxidation. This study identifies several bacterial lineages as participants in the oxidation of gaseous hydrocarbons in marine seeps and supports the idea of an alternate function for some pmoA-like genes. PMID:20675448

  10. Identification of novel methane-, ethane-, and propane-oxidizing bacteria at marine hydrocarbon seeps by stable isotope probing.

    Science.gov (United States)

    Redmond, Molly C; Valentine, David L; Sessions, Alex L

    2010-10-01

    Marine hydrocarbon seeps supply oil and gas to microorganisms in sediments and overlying water. We used stable isotope probing (SIP) to identify aerobic bacteria oxidizing gaseous hydrocarbons in surface sediment from the Coal Oil Point seep field located offshore of Santa Barbara, California. After incubating sediment with (13)C-labeled methane, ethane, or propane, we confirmed the incorporation of (13)C into fatty acids and DNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis and sequencing of the 16S rRNA and particulate methane monooxygenase (pmoA) genes in (13)C-DNA revealed groups of microbes not previously thought to contribute to methane, ethane, or propane oxidation. First, (13)C methane was primarily assimilated by Gammaproteobacteria species from the family Methylococcaceae, Gammaproteobacteria related to Methylophaga, and Betaproteobacteria from the family Methylophilaceae. Species of the latter two genera have not been previously shown to oxidize methane and may have been cross-feeding on methanol, but species of both genera were heavily labeled after just 3 days. pmoA sequences were affiliated with species of Methylococcaceae, but most were not closely related to cultured methanotrophs. Second, (13)C ethane was consumed by members of a novel group of Methylococcaceae. Growth with ethane as the major carbon source has not previously been observed in members of the Methylococcaceae; a highly divergent pmoA-like gene detected in the (13)C-labeled DNA may encode an ethane monooxygenase. Third, (13)C propane was consumed by members of a group of unclassified Gammaproteobacteria species not previously linked to propane oxidation. This study identifies several bacterial lineages as participants in the oxidation of gaseous hydrocarbons in marine seeps and supports the idea of an alternate function for some pmoA-like genes.

  11. Constraining the role of anoxygenic phototrophic Fe(II)-oxidizing bacteria in deposition of BIFs

    Science.gov (United States)

    Kappler, A.; Posth, N. R.; Hegler, F.; Wartha, E.; Huelin, S.

    2007-12-01

    Banded Iron Formations (BIFs) are Precambrian sedimentary deposits of alternating iron oxide and silica mineral layers. Their presence in the rock record ca.3.8-2.2 Ga makes them particularly intriguing formations for the debate over when oxygen became dominant on Earth. The mechanism(s) of BIF deposition is still unclear; suggestions including both abiotic and biotic processes. We are interested in constraining one of these proposed mechanisms; the direct biological oxidation of Fe(II) via anoxygenic Fe(II)-oxidizing autophototrophs. In order to find the limitations of photoferrotrophic BIF deposition, we take a holistic approach, investigating the oxidation of Fe(II) by modern Fe(II)-oxidizing phototrophs, the precipitation of Fe(III) (hydr)oxides, and the fate of the cell-mineral aggregates in the water column and at the basin floor. Specifically, physiology experiments with Fe(II)-oxidizing phototrophs under various conditions of light intensity, pH, Fe(II) concentration and temperature allow us to determine the environmental limits of such organisms. We carry out precipitation experiments to characterize the sedimentation rates, aggregate size and composition in order to resolve the effect of reactions in the water column. Finally, we simulate the diagenetic fate of these aggregates on the basin floor by placing them in gold capsules under T and P conditions relevant for the Transvaal Supergroup BIFs of South Africa. Recently, we have developed a tank simulating the Archean ocean in which the strains grow in continuous culture and collect the aggregates formed under various geochemical conditions. We aim to model the extent of and limitations to photoferrotrophs in BIF deposition. This information will help constrain whether biotic processes were dominant in the Archean ocean and will offer insight to the evolution of the early biogeosphere.

  12. Real-time investigation of antibiotics-induced oxidative stress and superoxide release in bacteria using an electrochemical biosensor.

    Science.gov (United States)

    Liu, Xiaobo; Marrakchi, Mouna; Jahne, Michael; Rogers, Shane; Andreescu, Silvana

    2016-02-01

    The involvement of oxidative stress in the mechanism of antibiotics-meditated cell death is unclear and subject to debate. The kinetic profile and a quantitative relationship between the release of reactive oxygen species (ROS), bacteria and antibiotic type remain elusive. Here we report direct measurements and analytical quantification of the release of superoxide radicals (O2(·-)), a major contributor to ROS, in antibiotics-treated bacterial cultures using a cytochrome c electrochemical biosensor. The specificity of electrochemical measurements was established by the addition of superoxide dismutase (SOD) which decreased the O2(·-) signal. Measurements using a general ROS-specific fluorescence dye and colony forming units (CFU) assays were performed side-by-side to determine the total ROS and establish the relationship between ROS and the degree of lethality. Exposure of Escherichia coli and Listeria monocytogenes cultures to antibiotics increased the release of O2(·-) radicals in a dose-dependent manner, suggesting that the transmembrane generation of ROS may occur as part of the antibiotic action. The study provides a quantitative methodology and fundamental knowledge to further explore the role of oxidative stress in antibiotics-meditated bacterial death and to assess physiological changes associated with the complex metabolic events related to oxidative stress and bacterial resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Synergistic Application of Black Tea Extracts and Lactic Acid Bacteria in Protecting Human Colonocytes against Oxidative Damage.

    Science.gov (United States)

    Zhao, Danyue; Shah, Nagendra P

    2016-03-23

    In view of the potential of lactic acid bacteria (LAB) to enhance the antioxidant activity of food products, this work explored the effectiveness of LAB fermented black tea samples in alleviating H2O2-induced oxidative stress in human colonocytes. The antioxidant capacity of tea samples was evaluated in terms of cyto-protectiveness, mitochondria membrane potential (Δψm)-stabilizing activity, ROS-inhibitory effect, and antioxidant enzyme-modulating activity. The effect on oxidative DNA damage and repair was studied in CCD 841 by comet assay. Results showed that the protective effect of tea pretreatment was more pronounced in normal cells (CCD 841) than in carcinomas (Caco-2), and fermented samples were invariably more effective. Higher cell viability and Δψm were maintained and ROS production was markedly inhibited with tea pretreatment. The fermented tea samples also remarkably stimulated DNA repair, resulting in fewer strand breaks and oxidative lesions. Our study implied that LAB fermentation may be an efficient way to enhance the antioxidative effectiveness of black tea flavonoid-enriched foods.

  14. Protection of Nitrate-Reducing Fe(II)-Oxidizing Bacteria from UV Radiation by Biogenic Fe(III) Minerals

    Science.gov (United States)

    Gauger, Tina; Konhauser, Kurt; Kappler, Andreas

    2016-04-01

    Due to the lack of an ozone layer in the Archean, ultraviolet radiation (UVR) reached early Earth's surface almost unattenuated; as a consequence, a terrestrial biosphere in the form of biological soil crusts would have been highly susceptible to lethal doses of irradiation. However, a self-produced external screen in the form of nanoparticular Fe(III) minerals could have effectively protected those early microorganisms. In this study, we use viability studies by quantifying colony-forming units (CFUs), as well as Fe(II) oxidation and nitrate reduction rates, to show that encrustation in biogenic and abiogenic Fe(III) minerals can protect a common soil bacteria such as the nitrate-reducing Fe(II)-oxidizing microorganisms Acidovorax sp. strain BoFeN1 and strain 2AN from harmful UVC radiation. Analysis of DNA damage by quantifying cyclobutane pyrimidine dimers (CPD) confirmed the protecting effect by Fe(III) minerals. This study suggests that Fe(II)-oxidizing microorganisms, as would have grown in association with mafic and ultramafic soils/outcrops, would have been able to produce their own UV screen, enabling them to live in terrestrial habitats on early Earth.

  15. Detection by denaturing gradient gel electrophoresis of ammonia-oxidizing bacteria in microcosms of crude oil-contaminated mangrove sediments.

    Science.gov (United States)

    dos Santos, A C F; Marques, E L S; Gross, E; Souza, S S; Dias, J C T; Brendel, M; Rezende, R P

    2012-01-27

    Currently, the effect of crude oil on ammonia-oxidizing bacterium communities from mangrove sediments is little understood. We studied the diversity of ammonia-oxidizing bacteria in mangrove microcosm experiments using mangrove sediments contaminated with 0.1, 0.5, 1, 2, and 5% crude oil as well as non-contaminated control and landfarm soil from near an oil refinery in Camamu Bay in Bahia, Brazil. The evolution of CO(2) production in all crude oil-contaminated microcosms showed potential for mineralization. Cluster analysis of denaturing gradient gel electrophoresis-derived samples generated with primers for gene amoA, which encodes the functional enzyme ammonia monooxygenase, showed differences in the sample contaminated with 5% compared to the other samples. Principal component analysis showed divergence of the non-contaminated samples from the 5% crude oil-contaminated sediment. A Venn diagram generated from the banding pattern of PCR-denaturing gradient gel electrophoresis was used to look for operational taxonomic units (OTUs) in common. Eight OTUs were found in non-contaminated sediments and in samples contaminated with 0.5, 1, or 2% crude oil. A Jaccard similarity index of 50% was found for samples contaminated with 0.1, 0.5, 1, and 2% crude oil. This is the first study that focuses on the impact of crude oil on the ammonia-oxidizing bacterium community in mangrove sediments from Camamu Bay.

  16. Remarkable recovery and colonization behaviour of methane oxidizing bacteria in soil after disturbance is controlled by methane source only.

    Science.gov (United States)

    Pan, Yao; Abell, Guy C J; Bodelier, Paul L E; Meima-Franke, Marion; Sessitsch, Angela; Bodrossy, Levente

    2014-08-01

    Little is understood about the relationship between microbial assemblage history, the composition and function of specific functional guilds and the ecosystem functions they provide. To learn more about this relationship we used methane oxidizing bacteria (MOB) as model organisms and performed soil microcosm experiments comprised of identical soil substrates, hosting distinct overall microbial diversities(i.e., full, reduced and zero total microbial and MOB diversities). After inoculation with undisturbed soil, the recovery of MOB activity, MOB diversity and total bacterial diversity were followed over 3 months by methane oxidation potential measurements and analyses targeting pmoA and 16S rRNA genes. Measurement of methane oxidation potential demonstrated different recovery rates across the different treatments. Despite different starting microbial diversities, the recovery and succession of the MOB communities followed a similar pattern across the different treatment microcosms. In this study we found that edaphic parameters were the dominant factor shaping microbial communities over time and that the starting microbial community played only a minor role in shaping MOB microbial community.

  17. Community composition and activity of anaerobic ammonium oxidation bacteria in the rhizosphere of salt-marsh grass Spartina alterniflora.

    Science.gov (United States)

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

    2016-09-01

    Anaerobic ammonium oxidation (anammox) as an important nitrogen removal pathway has been investigated in intertidal marshes. However, the rhizosphere-driven anammox process in these ecosystems is largely overlooked so far. In this study, the community dynamics and activities of anammox bacteria in the rhizosphere and non-rhizosphere sediments of salt-marsh grass Spartina alterniflora (a widely distributed plant in estuaries and intertidal ecosystems) were investigated using clone library analysis, quantitative PCR assay, and isotope-tracing technique. Phylogenetic analysis showed that anammox bacterial diversity was higher in the non-rhizosphere sediments (Scalindua and Kuenenia) compared with the rhizosphere zone (only Scalindua genus). Higher abundance of anammox bacteria was detected in the rhizosphere (6.46 × 10(6)-1.56 × 10(7) copies g(-1)), which was about 1.5-fold higher in comparison with that in the non-rhizosphere zone (4.22 × 10(6)-1.12 × 10(7) copies g(-1)). Nitrogen isotope-tracing experiments indicated that the anammox process in the rhizosphere contributed to 12-14 % N2 generation with rates of 0.43-1.58 nmol N g(-1) h(-1), while anammox activity in the non-rhizosphere zone contributed to only 4-7 % N2 production with significantly lower activities (0.28-0.83 nmol N g(-1) h(-1)). Overall, we propose that the rhizosphere microenvironment in intertidal marshes might provide a favorable niche for anammox bacteria and thus plays an important role in nitrogen cycling.

  18. Cobalt immobilization by manganese oxidizing bacteria from the Indian ridge system

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, R.; Sujith, P.P.; Fernandes, S.O.; Verma, P.; Khedekar, V.D.; LokaBharathi, P.A.

    Co immobilization by two manganese oxidizing isolates from Carlsberg Ridge waters (CR35 and CR48) was compared with that of Mn at same molar concentrations. At a lower concentration of 10 mu M, CR35 and CR48 immobilized 22 and 23 fM Co cell-1...

  19. Genes for Uranium Bioremediation in the Anaerobic Sulfate-Reducing Bacteria: Desulfovibrio mutants with altered sensitivity to oxidative stress

    International Nuclear Information System (INIS)

    Payne, Rayford B.; Ringbauer, Joseph A. Jr.; Wall, Judy D.

    2006-01-01

    Sulfate-reducing bacteria of the genus Desulfovibrio are ubiquitous in anaerobic environments such as groundwater, sediments, and the gastrointestinal tract of animals. Because of the ability of Desulfovibrio to reduce radionuclides and metals through both enzymatic and chemical means, they have been proposed as a means to bioremediate heavy metal contaminated sites. Although classically thought of as strict anaerobes, Desulfovibrio species are surprisingly aerotolerant. Our objective is to understand the response of Desulfovibrio to oxidative stress so that we may more effectively utilize them in bioremediation of heavy metals in mixed aerobic-anaerobic environments. The enzymes superoxide dismutase, superoxide reductase, catalase, and rubrerythrin have been shown by others to be involved in the detoxification of reactive oxygen species in Desulfovibrio. Some members of the genus Desulfovibrio can even reduce molecular oxygen to water via a membrane bound electron transport chain with the concomitant production of ATP, although their ability to grow with oxygen as the sole electron acceptor is still questioned.

  20. Identification of syntrophic acetate-oxidizing bacteria in anaerobic digesters by combined protein-based stable isotope probing and metagenomics.

    Science.gov (United States)

    Mosbæk, Freya; Kjeldal, Henrik; Mulat, Daniel G; Albertsen, Mads; Ward, Alastair J; Feilberg, Anders; Nielsen, Jeppe L

    2016-10-01

    Inhibition of anaerobic digestion through accumulation of volatile fatty acids occasionally occurs as the result of unbalanced growth between acidogenic bacteria and methanogens. A fast recovery is a prerequisite for establishing an economical production of biogas. However, very little is known about the microorganisms facilitating this recovery. In this study, we investigated the organisms involved by a novel approach of mapping protein-stable isotope probing (protein-SIP) onto a binned metagenome. Under simulation of acetate accumulation conditions, formations of (13)C-labeled CO2 and CH4 were detected immediately following incubation with [U-(13)C]acetate, indicating high turnover rate of acetate. The identified (13)C-labeled peptides were mapped onto a binned metagenome for improved identification of the organisms involved. The results revealed that Methanosarcina and Methanoculleus were actively involved in acetate turnover, as were five subspecies of Clostridia. The acetate-consuming organisms affiliating with Clostridia all contained the FTFHS gene for formyltetrahydrofolate synthetase, a key enzyme for reductive acetogenesis, indicating that these organisms are possible syntrophic acetate-oxidizing (SAO) bacteria that can facilitate acetate consumption via SAO, coupled with hydrogenotrophic methanogenesis (SAO-HM). This study represents the first study applying protein-SIP for analysis of complex biogas samples, a promising method for identifying key microorganisms utilizing specific pathways.

  1. Identification of syntrophic acetate-oxidizing bacteria in anaerobic digesters by combined protein-based stable isotope probing and metagenomics

    Science.gov (United States)

    Mosbæk, Freya; Kjeldal, Henrik; Mulat, Daniel G; Albertsen, Mads; Ward, Alastair J; Feilberg, Anders; Nielsen, Jeppe L

    2016-01-01

    Inhibition of anaerobic digestion through accumulation of volatile fatty acids occasionally occurs as the result of unbalanced growth between acidogenic bacteria and methanogens. A fast recovery is a prerequisite for establishing an economical production of biogas. However, very little is known about the microorganisms facilitating this recovery. In this study, we investigated the organisms involved by a novel approach of mapping protein-stable isotope probing (protein-SIP) onto a binned metagenome. Under simulation of acetate accumulation conditions, formations of 13C-labeled CO2 and CH4 were detected immediately following incubation with [U-13C]acetate, indicating high turnover rate of acetate. The identified 13C-labeled peptides were mapped onto a binned metagenome for improved identification of the organisms involved. The results revealed that Methanosarcina and Methanoculleus were actively involved in acetate turnover, as were five subspecies of Clostridia. The acetate-consuming organisms affiliating with Clostridia all contained the FTFHS gene for formyltetrahydrofolate synthetase, a key enzyme for reductive acetogenesis, indicating that these organisms are possible syntrophic acetate-oxidizing (SAO) bacteria that can facilitate acetate consumption via SAO, coupled with hydrogenotrophic methanogenesis (SAO-HM). This study represents the first study applying protein-SIP for analysis of complex biogas samples, a promising method for identifying key microorganisms utilizing specific pathways. PMID:27128991

  2. Characterization of arsenite-oxidizing bacteria isolated from arsenic-contaminated groundwater of West Bengal.

    Science.gov (United States)

    Paul, Dhiraj; Poddar, Soumya; Sar, Pinaki

    2014-01-01

    Nine arsenic (As)-resistant bacterial strains isolated from As-rich groundwater samples of West Bengal were characterized to elucidate their potential in geomicrobial transformation and bioremediation aspects. The 16S rRNA gene-based phylogenetic analysis revealed that the strains were affiliated with genera Actinobacteria, Microbacterium, Pseudomonas and Rhizobium. The strains exhibited high resistance to As [Minimum inhibitory concentration (MIC) ≥ 10 mM As(3+) and MIC ≥ 450 mM As(5+)] and other heavy metals, e.g., Cu(2+), Cr(2+), Ni(2+), etc. (MIC ≥ 2 mM) as well as As transformation (As(3+) oxidation and As(5+) reduction) capabilities. Their ability to utilize diverse carbon source(s) including hydrocarbons and different alternative electron acceptor(s) (As(5+), SO4(2-), S2O3(2-), etc.) during anaerobic growth was noted. Growth at wide range of pH, temperature and salinity, production of siderophore and biofilm were observed. Together with these, growth pattern and transformation kinetics indicated a high As(3+) oxidation activity of the isolates Rhizobium sp. CAS934i, Microbacterium sp. CAS905i and Pseudomonas sp. CAS912i. A positive relation between high As(3+) resistance and As(3+) oxidation and the supportive role of As(3+) in bacterial growth was noted. The results highlighted As(3+) oxidation process and metabolic repertory of strains indigenous to contaminated groundwater and indicates their potential in As(3+) detoxification. Thus, such metabolically well equipped bacterial strains with highest As(3+) oxidation activities may be used for bioremediation of As contaminated water and effluents in the near future.

  3. Identification of the intermediates of in vivo oxidation of 1 ,4-dioxane by monooxygenase-containing bacteria.

    Science.gov (United States)

    Mahendra, Shaily; Petzold, Christopher J; Baidoo, Edward E; Keasling, Jay D; Alvarez-Cohen, Lisa

    2007-11-01

    1,4-dioxane is a probable human carcinogen and an emerging water contaminant. Monooxygenase-expressing bacteria have been shown to degrade dioxane via growth-supporting as well as cometabolic mechanisms. In this study, the intermediates of dioxane degradation by monooxygenase-expressing bacteria were determined by triple quadrupole-mass spectrometry and Fourier transform ion cyclotron resonance-mass spectrometry. The major intermediates were identified as 2-hydroxyethoxyacetic acid (HEAA), ethylene glycol, glycolate, and oxalate. Studies with uniformly labeled 14C dioxane showed that over 50% of the dioxane was mineralized to CO2 by CB1190, while 5% became biomass-associated after 48 h. Volatile organic acids and non-volatiles, respectively, accounted for 20 and 11% of the radiolabeled carbon. Although strains cometabolizing dioxane exhibited limited transformation capacities, nearly half of the initial dioxane was recovered as CO2. On the basis of these analytical results, we propose a pathway for dioxane oxidation by monooxygenase-expressing cells in which dioxane is first converted to 2-hydroxy-1,4-dioxane, which is spontaneously oxidized to HEAA. During a second monooxygenation step, HEAA is further hydroxylated, resulting in a mixture of dihydroxyethoxyacetic acids with a hydroxyl group at the ortho or para position. After cleavage of the second ether bond, small organic molecules such as ethylene glycol, glycolate, glyoxalate, and oxalate are progressively formed, which are then mineralized to CO2 via common cellular metabolic pathways. Bioremediation of dioxane via this pathway is not expected to cause an accumulation of toxic compounds in the environment.

  4. Optimization of three FISH procedures for in situ detection of anaerobic ammonium oxidizing bacteria in biological wastewater treatment.

    Science.gov (United States)

    Pavlekovic, Marko; Schmid, Markus C; Schmider-Poignee, Nadja; Spring, Stefan; Pilhofer, Martin; Gaul, Tobias; Fiandaca, Mark; Löffler, Frank E; Jetten, Mike; Schleifer, K-H; Lee, Natuschka M

    2009-08-01

    Fluorescence in situ hybridization (FISH) using fluorochrome-labeled DNA oligonucleotide probes has been successfully applied for in situ detection of anaerobic ammonium oxidizing (anammox) bacteria. However, application of the standard FISH protocols to visualize anammox bacteria in biofilms from a laboratory-scale wastewater reactor produced only weak signals. Increased signal intensity was achieved either by modifying the standard FISH protocol, using peptide nucleic acid probes (PNA FISH), or applying horse radish peroxidase- (HRP-) labeled probes and subsequent catalyzed reporter deposition (CARD-FISH). A comparative analysis using anammox biofilm samples and suspended anammox biomass from different laboratory wastewater bioreactors revealed that the modified standard FISH protocol and the PNA FISH probes produced equally strong fluorescence signals on suspended biomass, but only weak signals were obtained with the biofilm samples. The probe signal intensities in the biofilm samples could be enhanced by enzymatic pre-treatment of fixed cells, and by increasing the hybridization time of the PNA FISH protocol. CARD-FISH always produced up to four-fold stronger fluorescent signals but unspecific fluorescence signals, likely caused by endogenous peroxidases as reported in several previous studies, compromised the results. Interference of the development of fluorescence intensity with endogenous peroxidases was also observed in cells of aerobic ammonium oxidizers like Nitrosomonas europea, and sulfate-reducers like Desulfobacter postgatei. Interestingly, no interference was observed with other peroxidase-positive microorganisms, suggesting that CARD-FISH is not only compromised by the mere presence of peroxidases. Pre-treatment of cells to inactivate peroxidase with HCl or autoclavation/pasteurization failed to inactive peroxidases, but H(2)O(2) significantly reduced endogenous peroxidase activity. However, for optimal inactivation, different H(2)O(2

  5. Modelling TCE degradation by a mixed culture of methane-oxidizing bacteria

    DEFF Research Database (Denmark)

    Broholm, Kim; Christensen, Thomas Højlund; Jensen, Bjørn K.

    1992-01-01

    A model describing the growth of bacteria and the degradation of methane and trichloroethylene (TCE) based on the concept of competitive inhibition is proposed. The model has been applied to laboratory batch experiments representing different initial TCE concentrations (50–4300 μg/l) and initial...... methane concentrations (0.53–3.2 mg/l). The proposed model simulated successfully the data obtained for initial methane concentration (less than 1.8 mg/l), causing constant experimental growth conditions during the experiments. This indicates that the interactions between methane and TCE degradation can...... be explained as competitive inhibition. The model simulations of the results from the experiments with the highest initial methane concentration of 3.2 mg/l failed, supposedly because the growth conditions changed during the experiments. The proposed model is a useful engineering tool for design of treatment...

  6. Isolation and characterization of ferrous- and sulfur-oxidizing bacteria from Tengchong solfataric region, China.

    Science.gov (United States)

    Jiang, Chengying; Liu, Ying; Liu, Yanyang; Guo, Xu; Liu, Shuang-Jiang

    2009-01-01

    Microbial oxidation and reduction of iron and sulfur are important parts of biogeochemical cycles in acidic environments such as geothermal solfataric regions. Species of Acidithiobacillus and Leptospirillum are the common ferrous-iron and sulfur oxidizers from such environments. This study focused on the Tengchong sofataric region, located in Yunnan Province, Southwest China. Based on cultivation, 9 strains that grow on ferrous-iron and sulfuric compounds were obtained. Analysis of 16S rRNA genes of the 9 strains indicated that they were affiliated to Acidithiobacillus, Alicyclobacillus, Sulfobacillus, Leptospirillum and Acidiphilium. Physiological and phylogenetic studies indicated that two strains (TC-34 and TC-71) might represent two novel members of Alicyclobacillus. Strain TC-34 and TC-71 showed 94.8%-97.1% 16S rRNA gene identities to other species of Alicyclobacillus. Different from the previously described Alicyclobacillus species, strains TC-34 and TC-71 were mesophilic and their cellular fatty acids do not contain omega-cyclic fatty acids. Strain TC-71 was obligately dependent on ferrous-iron for growth. It was concluded that the ferrous-iron oxidizers were diversified and Alicyclobacillus species were proposed to take part in biochemical geocycling of iron in the Tengchong solfataric region.

  7. Hopanoid-producing bacteria in the Red Sea include the major marine nitrite-oxidizers

    KAUST Repository

    Kharbush, Jenan J

    2018-04-10

    Hopanoids, including the extended side chain-containing bacteriohopanepolyols (BHPs), are bacterial lipids found abundantly in the geological record and across Earth\\'s surface environments. However, the physiological roles of this biomarker remain uncertain, limiting interpretation of their presence in current and past environments. Recent work investigating the diversity and distribution of hopanoid producers in the marine environment implicated low-oxygen regions as important loci of hopanoid production, and data from marine oxygen minimum zones (OMZs) suggested that the dominant hopanoid producers in these environments are nitrite-utilizing organisms, revealing a potential connection between hopanoid production and the marine nitrogen cycle. Here we use metagenomic data from the Red Sea to investigate the ecology of hopanoid producers in an environmental setting that is biogeochemically distinct from those investigated previously. The distributions of hopanoid production and nitrite oxidation genes in the Red Sea are closely correlated, and the majority of hopanoid producers are taxonomically affiliated with the major marine nitrite oxidizers, Nitrospinae and Nitrospirae. These results suggest that the relationship between hopanoid production and nitrite oxidation is conserved across varying biogeochemical conditions in dark ocean microbial ecosystems.

  8. Hopanoid-producing bacteria in the Red Sea include the major marine nitrite-oxidizers

    KAUST Repository

    Kharbush, Jenan J; Thompson, Luke R; Haroon, Mohamed; Knight, Rob; Aluwihare, Lihini I

    2018-01-01

    Hopanoids, including the extended side chain-containing bacteriohopanepolyols (BHPs), are bacterial lipids found abundantly in the geological record and across Earth's surface environments. However, the physiological roles of this biomarker remain uncertain, limiting interpretation of their presence in current and past environments. Recent work investigating the diversity and distribution of hopanoid producers in the marine environment implicated low-oxygen regions as important loci of hopanoid production, and data from marine oxygen minimum zones (OMZs) suggested that the dominant hopanoid producers in these environments are nitrite-utilizing organisms, revealing a potential connection between hopanoid production and the marine nitrogen cycle. Here we use metagenomic data from the Red Sea to investigate the ecology of hopanoid producers in an environmental setting that is biogeochemically distinct from those investigated previously. The distributions of hopanoid production and nitrite oxidation genes in the Red Sea are closely correlated, and the majority of hopanoid producers are taxonomically affiliated with the major marine nitrite oxidizers, Nitrospinae and Nitrospirae. These results suggest that the relationship between hopanoid production and nitrite oxidation is conserved across varying biogeochemical conditions in dark ocean microbial ecosystems.

  9. Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM) Like Instrument Protocols

    Science.gov (United States)

    Glavin, D. P.; Popa, R.; Martin, M. G.; Freissinet, C.; Fisk, M. R.; Dworkin, J. P.; Mahaffy, P. R.

    2012-01-01

    Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from approx 10(exp 2) to 10(exp 7) cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500 C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20 C followed by trap heating and analysis by GC/Ms. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The distribution of pyrolysis products extracted from the

  10. Nitrospina-like bacteria are the main drivers of nitrite oxidation in the seasonal upwelling area of the Eastern South Pacific (Central Chile ∼36°S).

    Science.gov (United States)

    Levipan, Héctor A; Molina, Verónica; Fernandez, Camila

    2014-12-01

    Aerobic nitrite oxidation in marine environments plays a key role in the nitrification process. Marine bacteria involved in this nitrate-producing process have however been seldom studied compared with the ammonia-oxidizing community. Here, we report for the first time the community structure of aerobic nitrite-oxidizing bacteria (NOB) in the seasonal upwelling and oxygen-deficient area off Central Chile. Analysis of 16S rRNA by tag pyrosequencing was combined with specific quantitative polymerase chain reaction (qPCR) and reverse transcription qPCR in summer and wintertime. Nitrospina-like bacteria were the only known NOB detected by means of pyrosequencing between 30 and 80 m depth, accounting for up to 5% of total bacteria. This guild was represented by 11 and 7 operational taxonomic units (97% cut-off) in winter and summertime respectively. Nitrospina-like bacteria were phylogenetically related to sequences retrieved from coastal upwelling, oxygen minimum zones and deep-sea environments. This group was also detected by qPCR with abundances that increased with depth throughout the water column. Importantly, Nitrospina from surface layers showed low abundances but high 16S rRNA : rDNA ratios and mainly in summertime. Overall, our results highlight the seasonal variability between the structure and physiological state of this community and suggest a significant role of Nitrospina in the nitrogen cycle of seasonal upwelling areas.

  11. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating

    Science.gov (United States)

    Daebeler, Anne; Abell, Guy C. J.; Bodelier, Paul L. E.; Bodrossy, Levente; Frampton, Dion M. F.; Hefting, Mariet M.; Laanbroek, Hendrikus J.

    2012-01-01

    The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively) to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of ammonia oxidation as a function of environmental conditions including the ecophysiology of associated organisms. We examined the discrete and combined effects of mineral nitrogen deposition and geothermal heating on ammonia-oxidizing communities by sampling soils from a long-term fertilization site along a temperature gradient in Icelandic grasslands. Microarray, clone library and quantitative PCR analyses of the ammonia monooxygenase subunit A (amoA) gene accompanied by physico-chemical measurements of the soil properties were conducted. In contrast to most other terrestrial environments, the ammonia-oxidizing communities consisted almost exclusively of archaea. Their bacterial counterparts proved to be undetectable by quantitative polymerase chain reaction suggesting AOB are only of minor relevance for ammonia oxidation in these soils. Our results show that fertilization and local, geothermal warming affected detectable ammonia-oxidizing communities, but not soil chemistry: only a subset of the detected AOA phylotypes was present in higher temperature soils and AOA abundance was increased in the fertilized soils, while soil physio-chemical properties remained unchanged. Differences in distribution and structure of AOA communities were best explained by soil pH and clay content irrespective of temperature or fertilizer treatment in these grassland soils, suggesting that these factors have a greater potential for ecological niche-differentiation of AOA in soil than temperature and N fertilization. PMID:23060870

  12. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating

    Directory of Open Access Journals (Sweden)

    Anne eDaebeler

    2012-10-01

    Full Text Available The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of ammonia oxidation as a function of environmental conditions including the ecophysiology of the associated organisms. We examined the discrete and combined effects of mineral nitrogen deposition and geothermal heating on ammonia-oxidizing communities by sampling soils from a long-term fertilisation site along a temperature gradient in Icelandic grasslands. Microarray, clone library and quantitative PCR analyses of the ammonia monooxygenase subunit A (amoA gene accompanied by physico-chemical measurements of the soil properties were conducted. In contrast to most other terrestrial environments, the ammonia-oxidizing communities consisted almost exclusively of archaea. Their bacterial counterparts proved to be undetectable by quantitative PCR suggesting AOB are only of minor relevance for ammonia oxidation in these soils. Our results show that fertilization and local, geothermal warming affected detectable ammonia-oxidizing communities, but not soil chemistry: only a subset of the detected AOA phylotypes was present in higher temperature soils and AOA abundance was increased in the fertilized soils, while the measured soil physico-chemical properties remained unchanged. Differences in distribution and structure of AOA communities were best explained by soil pH and clay content irrespective of temperature or fertilizer treatment in these grassland soils, suggesting that these factors have a greater potential for ecological niche-differentiation of AOA in soil than temperature and N fertilization.

  13. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating.

    Science.gov (United States)

    Daebeler, Anne; Abell, Guy C J; Bodelier, Paul L E; Bodrossy, Levente; Frampton, Dion M F; Hefting, Mariet M; Laanbroek, Hendrikus J

    2012-01-01

    The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively) to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of ammonia oxidation as a function of environmental conditions including the ecophysiology of associated organisms. We examined the discrete and combined effects of mineral nitrogen deposition and geothermal heating on ammonia-oxidizing communities by sampling soils from a long-term fertilization site along a temperature gradient in Icelandic grasslands. Microarray, clone library and quantitative PCR analyses of the ammonia monooxygenase subunit A (amoA) gene accompanied by physico-chemical measurements of the soil properties were conducted. In contrast to most other terrestrial environments, the ammonia-oxidizing communities consisted almost exclusively of archaea. Their bacterial counterparts proved to be undetectable by quantitative polymerase chain reaction suggesting AOB are only of minor relevance for ammonia oxidation in these soils. Our results show that fertilization and local, geothermal warming affected detectable ammonia-oxidizing communities, but not soil chemistry: only a subset of the detected AOA phylotypes was present in higher temperature soils and AOA abundance was increased in the fertilized soils, while soil physio-chemical properties remained unchanged. Differences in distribution and structure of AOA communities were best explained by soil pH and clay content irrespective of temperature or fertilizer treatment in these grassland soils, suggesting that these factors have a greater potential for ecological niche-differentiation of AOA in soil than temperature and N fertilization.

  14. Distinctive Oxidative Stress Responses to Hydrogen Peroxide in Sulfate Reducing Bacteria Desulfovibrio vulgaris Hildenborough

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Aifen; He, Zhili; Redding, A.M.; Mukhopadhyay, Aindrila; Hemme, Christopher L.; Joachimiak, Marcin P.; Bender, Kelly S.; Keasling, Jay D.; Stahl, David A.; Fields, Matthew W.; Hazen, Terry C.; Arkin, Adam P.; Wall, Judy D.; Zhou, Jizhong

    2009-01-01

    Response of Desulfovibrio vulgaris Hildenborough to hydrogen peroxide (H2O2, 1 mM) was investigated with transcriptomic, proteomic and genetic approaches. Microarray data demonstrated that gene expression was extensively affected by H2O2 with the response peaking at 120 min after H2O2 treatment. Genes affected include those involved with energy production, sulfate reduction, ribosomal structure and translation, H2O2 scavenging, posttranslational modification and DNA repair as evidenced by gene coexpression networks generated via a random matrix-theory based approach. Data from this study support the hypothesis that both PerR and Fur play important roles in H2O2-induced oxidative stress response. First, both PerR and Fur regulon genes were significantly up-regulated. Second, predicted PerR regulon genes ahpC and rbr2 were derepressedin Delta PerR and Delta Fur mutants and induction of neither gene was observed in both Delta PerR and Delta Fur when challenged with peroxide, suggesting possible overlap of these regulons. Third, both Delta PerR and Delta Fur appeared to be more tolerant of H2O2 as measured by optical density. Forth, proteomics data suggested de-repression of Fur during the oxidative stress response. In terms of the intracellular enzymatic H2O2 scavenging, gene expression data suggested that Rdl and Rbr2 may play major roles in the detoxification of H2O2. In addition, induction of thioredoxin reductase and thioredoxin appeared to be independent of PerR and Fur. Considering all data together, D. vulgaris employed a distinctive stress resistance mechanism to defend against increased cellular H2O2, and the temporal gene expression changes were consistent with the slowdown of cell growth at the onset of oxidative stress.

  15. Concentration-dependent behaviors of bone marrow derived mesenchymal stem cells and infectious bacteria toward magnesium oxide nanoparticles.

    Science.gov (United States)

    Wetteland, Cheyann Lee; Nguyen, Nhu-Y Thi; Liu, Huinan

    2016-04-15

    This article reports the quantitative relationship between the concentration of magnesium oxide (MgO) nanoparticles and its distinct biological activities towards mammalian cells and infectious bacteria for the first time. The effects of MgO nanoparticles on the viability of bone marrow derived mesenchymal stem cells (BMSCs) and infectious bacteria (both gram-negative Escherichia coli and gram-positive Staphylococcus epidermidis) showed a concentration-dependent behavior in vitro. The critical concentrations of MgO nanoparticles identified in this study provided valuable guidelines for biomaterial design toward potential clinical translation. BMSCs density increased significantly when cultured in 200μg/mL of MgO in comparison to the Cells Only control without MgO. The density of BMSCs decreased significantly after culture in the media with 500μg/mL or more of MgO. Concentrations at or above 1000μg/mL of MgO resulted in complete BMSCs death. Quantification of colony forming units (CFU) revealed that the minimum bactericidal concentration (MBC) of MgO for E. coli and S. epidermidis was 1200μg/mL. The addition of MgO nanoparticles into the cultures increased the pH and Mg(2+) ion concentration in the respective culture media, which might have played a role in the observed cell responses but not the main factors. E. coli and S. epidermidis still proliferated significantly at alkaline pH up to 10 or with supplemental Mg(2+) dosages up to 50mM, indicating bactericidal properties of MgO are beyond the effects of increased media pH and Mg(2+) ion concentrations. MgO nanoparticles at a concentration of 200μg/mL provided dual benefits of promoting BMSC proliferation while reducing bacterial adhesion, which should be further studied for potential medical implant applications. The use of free MgO nanoparticles yielded detrimental effects to BMSCs in concentrations above 300μg/mL. We recommend further study into MgO nanoparticle as a coating material or as a part of a

  16. A twisted tale - how biocorrosion communities yield new insight on the distribution of marine iron-oxidizing bacteria

    Science.gov (United States)

    McBeth, J. M.; Emerson, D.

    2011-12-01

    Microbiologically influenced corrosion (MIC) of mild steel is a complex process involving biogeochemical interactions between bacteria, steel surfaces, and biogenic and abiotically produced minerals. The role of neutrophilic iron-oxidizing bacteria (FeOB) in this process is poorly understood, and surprisingly, little is known about the microbial ecology of corroding steel in marine environments. Based on previous work (McBeth et al 2011), we hypothesized that coastal sediments act as reservoirs for marine FeOB of the candidatus class 'Zetaproteobacteria', and that these bacteria will colonize and become numerically abundant on steel surfaces. To test this, mild steel coupons were incubated in a salt marsh and sampled over 40 days in summer 2010. DNA extracted from the steel surfaces was analyzed for overall bacterial diversity by pyrosequencing of the V4 variable region of the 16S rRNA gene, and relevant communities were quantified using qPCR. The qPCR analyses were done using 16S primers specific to prokaryotes (Takai & Horikoshi 2000) and Zetaproteobacteria (Kato et al 2009), and a dsrA gene specific primer (Ben-Dov et al 2007) to assess the population of sulfate-reducing bacteria (SRB). Pyrosequencing data analyses showed Zetaproteobacteria were present on steel samples throughout the incubations and were also present in adjacent sediments; however, the diversity of Zetaproteobacteria was lower on the steel in comparison with sediments, indicating specific populations were enriched on the steel coupons. Iron oxyhydroxide stalk biosignatures were observed on the steel and in enrichment cultures, evidence that the Zetaproteobacteria identified using molecular techniques were likely FeOB. Relatives of the H2-oxidizing genus Hydrogenophaga and members of the family Rhodobacterales were also identified as important members of the biocorrosion community and were present both on steel and in sediments. The diversity of these organisms on steel surfaces increased with

  17. [Analysis of phylogenetic criteria for estimation of the rank of taxa in methane-oxidizing bacteria].

    Science.gov (United States)

    Romanovskaia, V A; Rokitko, P V

    2011-01-01

    To determine a possibility of application of phylogenetic criteria for estimating the taxa rank, the intra- and interspecies, as well as intergeneric relatedness of methanotrophs on the basis of 16S rRNA gene sequences was estimated. We used sequences of 16S rRNA genes of the studied isolates of obligate methanotrophs which have been deposited in UCM (Ukrainian Collection of Microorganisms), and of type strains of other obligate methanotrophs species (from GenBank database). It is shown, that the levels of interspecies and intergeneric relatedness in different families of methanotrophs are not identical, and therefore they can be used for differentiation of taxa only within one family. The carried out analysis has shown, that it is necessary to reconsider taxonomic position: (1) of two phenotypically similar species of Methylomonas (M. aurantiaca and M. fodinarum), similarity of 16S rRNA genes which is 99.4%, similarity of their total DNA--up to 80% that rather testifies to strain differences, than to species differences; (2) of species Methylomicrobium agile and M album which are phylogenetically more related to genus Methylobacter (97% of affinity), than Methylomicrobium (94% of affinity); (3) of genera of the family Beijerinckiaceae (Methylocella and Methylocapsa), and also genera of the family Methylocystaceae (Methylosinus and Methylocystis), whereas high level of relatedness (97% and more) of these bacteria with other methanotrophic genera (within one family) practically corresponds to a range of relatedness of species (within some genera) in the family Methylococcaceae. When determining phylogenetic criteria which can characterize the ranks of taxa, it was revealed, that the levels of interspecies relatedness of methanotrophic genera of the families Methylocystaceae and Beijerinckiaceae (97.8-99.1% and 97.8%, accordingly) considerably exceed the level of genera formation in the family Methylococcaceae (94.0-98.2%) and, moreover, approach the value of

  18. Bioprospecting arsenite oxidizing bacteria in the soil of the Comarca Lagunera

    Directory of Open Access Journals (Sweden)

    Edelweiss A. Rangel-Montoya

    2015-01-01

    Full Text Available Resumen El arsénico es uno de los metaloides más tóxicos presente en el ambiente y la exposición prolongada a este metal causa efectos crónicos en la salud. Por ello, la búsqueda de alternativas amigables con el medio ambiente, para el tratamiento de agua y suelos contaminados con arsénico es importante. En este trabajo se aislaron cepas bacterianas de suelos con presencia de arsénico en la Comarca Lagunera, para analizar aquellas con capacidad oxidante de arsenito. Las cepas 04-SP1qa y 14-SP1qh de metabolismo quimiolitoautotrófico y quimioheterotrófico, respectivamente, tuvieron mayor actividad de la enzima arsenito oxidasa. Las condiciones óptimas de crecimiento y la actividad enzimática de dichas cepas se investigaron. La cepa 04-SP1qa presentó actividad enzimática específica de 0.162 μmol·min- 1 ·mg-1, constante de Michaelis-Menten (Km de 3.37 μM y velocidad máxima (Vmax de 5.20 μM·min-1·mg-1 en condiciones óptimas de pH 8.0 y 40 °C. La cepa 14-SP1qh presentó actividad enzimática específica de 0.16 μmol·min-1·mg-1, Km de 3.70 μM y Vmax de 14.39 μM·min-1·mg-1 a pH 7.0 y 40 °C. Los resultados demostraron la presencia de bacterias oxidantes de arsenito con actividad enzimática en suelos de la Comarca Lagunera, identificando potencial para desarrollar nuevas tecnologías de biorremediación de aguas y suelos contaminados con arsénico en la región.

  19. Impacts of organic and inorganic fertilizers on nitrification in a cold climate soil are linked to the bacterial ammonia oxidizer community.

    Science.gov (United States)

    Fan, Fenliang; Yang, Qianbao; Li, Zhaojun; Wei, Dan; Cui, Xi'an; Liang, Yongchao

    2011-11-01

    The microbiology underpinning soil nitrogen cycling in northeast China remains poorly understood. These agricultural systems are typified by widely contrasting temperature, ranging from -40 to 38°C. In a long-term site in this region, the impacts of mineral and organic fertilizer amendments on potential nitrification rate (PNR) were determined. PNR was found to be suppressed by long-term mineral fertilizer treatment but enhanced by manure treatment. The abundance and structure of ammonia-oxidizing bacterial (AOB) and archaeal (AOA) communities were assessed using quantitative polymerase chain reaction and denaturing gradient gel electrophoresis techniques. The abundance of AOA was reduced by all fertilizer treatments, while the opposite response was measured for AOB, leading to a six- to 60-fold reduction in AOA/AOB ratio. The community structure of AOA exhibited little variation across fertilization treatments, whereas the structure of the AOB community was highly responsive. PNR was correlated with community structure of AOB rather than that of AOA. Variation in the community structure of AOB was linked to soil pH, total carbon, and nitrogen contents induced by different long-term fertilization regimes. The results suggest that manure amendment establishes conditions which select for an AOB community type which recovers mineral fertilizer-suppressed soil nitrification.

  20. [Comparative characterization of cultured methane-oxidizing bacteria by serological and molecular methods].

    Science.gov (United States)

    Slobodova, N V; Kolganova, T V; Bulygina, E S; Kuznetsov, B B; Turova, T P; Kravchenko, I K

    2006-01-01

    Three stable methane-oxidizing enrichment cultures, SB26, SB31, and SB31A were analyzed by transmission electron microscopy and by serological and molecular techniques. Electron microscopy revealed the presence of both type I and type II methanotrophs in SB31 and SB31A enrichments; only type II methanotrophs were found in SB26 enrichment. Methylosinus trichosporium was detected in all three enrichments by the application of species-specific antibodies. Additionally, Methylocystis echinoides was found in SB26 culture; Methylococcus capsulatus, in SB31 and SB31A; and Methylomonas methanica, in SB31. The analysis with pmoA and nifH gene sequences as phylogenetic markers revealed the presence of Methylosinus/Methylocystis group in all communities. Moreover, the analysis of pmoA sequences revealed the presence of Methylomonas in SB31. Methylocella was detected in SB31 and SB31A enrichments only by nifH analysis. It was concluded that the simultaneous application of different approaches reveals more reliable information on the diversity of methanotrophs.

  1. Activity and diversity of methane-oxidizing bacteria along a Norwegian sub-Arctic glacier forefield.

    Science.gov (United States)

    Mateos-Rivera, Alejandro; Øvreås, Lise; Wilson, Bryan; Yde, Jacob C; Finster, Kai W

    2018-05-01

    Methane (CH4) is one of the most abundant greenhouse gases in the atmosphere and identification of its sources and sinks is crucial for the reliability of climate model outputs. Although CH4 production and consumption rates have been reported from a broad spectrum of environments, data obtained from glacier forefields are restricted to a few locations. We report the activities of methanotrophic communities and their diversity along a chronosequence in front of a sub-Arctic glacier using high-throughput sequencing and gas flux measurements. CH4 oxidation rates were measured in the field throughout the growing season during three sampling times at eight different sampling points in combination with laboratory incubation experiments. The overall results showed that the methanotrophic community had similar trends of increased CH4 consumption and increased abundance as a function of soil development and time of year. Sequencing results revealed that the methanotrophic community was dominated by a few OTUs and that a short-term increase in CH4 concentration, as performed in the field measurements, altered slightly the relative abundance of the OTUs.

  2. Oral bacteria--the missing link to ambiguous findings of exhaled nitrogen oxides in cystic fibrosis.

    Science.gov (United States)

    Zetterquist, Wilhelm; Marteus, Helena; Kalm-Stephens, Pia; Näs, Elisabeth; Nordvall, Lennart; Johannesson, Marie; Alving, Kjell

    2009-02-01

    Nitrite in exhaled breath condensate (EBC) has been shown to be elevated in cystic fibrosis (CF), while exhaled nitric oxide (FENO) is paradoxically low. This has been argued to reflect increased metabolism of NO while its diffusion is obstructed by mucus. However, we wanted to study the possible influence of salivary nitrite and bacterial nitrate reduction on these parameters in CF patients by the intervention of an anti-bacterial mouthwash. EBC and saliva were collected from 15 CF patients (10-43 years) and 15 controls (9-44 years) before and 5 min after a 30s chlorhexidine mouthwash, in parallel with measurements of FENO. Nitrite and nitrate concentrations were measured fluorometrically. EBC nitrite, but not nitrate, was significantly higher in the CF patients (median 3.6 vs 1.3 microM in controls, p<0.05) and decreased after mouthwash in both groups (3.6-1.4 microM, p<0.01; 1.3-0.5 microM, p<0.01). Salivary nitrite correlated significantly to EBC nitrite (r=0.60, p<0.001) and decreased correspondingly after chlorhexidine, whereas salivary nitrate increased. FENO was lower in CF and the difference between patients and controls was accentuated after mouthwash (5.4 vs 8.4 ppb in controls, p<0.05). EBC nitrite mainly originates in the pharyngo-oral tract and its increase in CF is possibly explained by a regional change in bacterial activity. The limited lower airway contribution supports the view of a genuinely impaired formation and metabolism of NO in CF, rather than poor diffusion of the molecule.

  3. Distribution and characteristic of nitrite-dependent anaerobic methane oxidation bacteria by comparative analysis of wastewater treatment plants and agriculture fields in northern China

    Directory of Open Access Journals (Sweden)

    Zhen Hu

    2016-12-01

    Full Text Available Nitrite-dependent anaerobic methane oxidation (n-damo is a recently discovered biological process which has been arousing global attention because of its potential in minimizing greenhouse gases emissions. In this study, molecular biological techniques and potential n-damo activity batch experiments were conducted to investigate the presence and diversity of M. oxyfera bacteria in paddy field, corn field, and wastewater treatment plant (WWTP sites in northern China, as well as lab-scale n-damo enrichment culture. N-damo enrichment culture showed the highest abundance of M. oxyfera bacteria, and positive correlation was observed between potential n-damo rate and abundance of M. oxyfera bacteria. Both paddy field and corn field sites were believed to be better inoculum than WWTP for the enrichment of M. oxyfera bacteria due to their higher abundance and the diversity of M. oxyfera bacteria. Comparative analysis revealed that long biomass retention time, low NH ${}_{4}^{+}$ 4 + and high NO ${}_{2}^{-}$ 2 − content were suitable for the growth of M. oxyfera bacteria.

  4. Bioleaching of ilmenite and basalt in the presence of iron-oxidizing and iron-scavenging bacteria

    Science.gov (United States)

    Navarrete, Jesica U.; Cappelle, Ian J.; Schnittker, Kimberlin; Borrok, David M.

    2013-04-01

    Bioleaching has been suggested as an alternative to traditional mining techniques in extraterrestrial environments because it does not require extensive infrastructure and bulky hardware. In situ bioleaching of silicate minerals, such as those found on the moon or Mars, has been proposed as a feasible alternative to traditional extraction techniques that require either extreme heat and/or substantial chemical treatment. In this study, we investigated the biotic and abiotic leaching of basaltic rocks (analogues to those found on the moon and Mars) and the mineral ilmenite (FeTiO3) in aqueous environments under acidic (pH ˜ 2.5) and circumneutral pH conditions. The biological leaching experiments were conducted using Acidithiobacillus ferrooxidans, an iron (Fe)-oxidizing bacteria, and Pseudomonas mendocina, an Fe-scavenging bacteria. We found that both strains were able to grow using the Fe(II) derived from the tested basaltic rocks and ilmenite. Although silica leaching rates were the same or slightly less in the bacterial systems with A. ferrooxidans than in the abiotic control systems, the extent of Fe, Al and Ti released (and re-precipitated in new solid phases) was actually greater in the biotic systems. This is likely because the Fe(II) leached from the basalt was immediately oxidized by A. ferrooxidans, and precipitated into Fe(III) phases which causes a change in the equilibrium of the system, i.e. Le Chatelier's principle. Iron(II) in the abiotic experiment was allowed to build up in solution which led to a decrease in its overall release rate. For example, the percentage of Fe, Al and Ti leached (dissolved + reactive mineral precipitates) from the Mars simulant in the A. ferrooxidans experimental system was 34, 41 and 13% of the total Fe, Al and Ti in the basalt, respectively, while the abiotic experimental system released totals of only 11, 25 and 2%. There was, however, no measurable difference in the amounts of Fe and Ti released from ilmenite in the

  5. Lactic Acid Bacteria Protects Caenorhabditis elegans from Toxicity of Graphene Oxide by Maintaining Normal Intestinal Permeability under different Genetic Backgrounds

    Science.gov (United States)

    Zhao, Yunli; Yu, Xiaoming; Jia, Ruhan; Yang, Ruilong; Rui, Qi; Wang, Dayong

    2015-11-01

    Lactic acid bacteria (LAB) is safe and useful for food and feed fermentation. We employed Caenorhabditis elegans to investigate the possible beneficial effect of LAB (Lactobacillus bulgaricus) pretreatment against toxicity of graphene oxide (GO) and the underlying mechanisms. LAB prevented GO toxicity on the functions of both primary and secondary targeted organs in wild-type nematodes. LAB blocked translocation of GO into secondary targeted organs through intestinal barrier by maintaining normal intestinal permeability in wild-type nematodes. Moreover, LAB prevented GO damage on the functions of both primary and secondary targeted organs in exposed nematodes with mutations of susceptible genes (sod-2, sod-3, gas-1, and aak-2) to GO toxicity by sustaining normal intestinal permeability. LAB also sustained the normal defecation behavior in both wild-type nematodes and nematodes with mutations of susceptible genes. Therefore, the beneficial role of LAB against GO toxicity under different genetic backgrounds may be due to the combinational effects on intestinal permeability and defecation behavior. Moreover, the beneficial effects of LAB against GO toxicity was dependent on the function of ACS-22, homologous to mammalian FATP4 to mammalian FATP4. Our study provides highlight on establishment of pharmacological strategy to protect intestinal barrier from toxicity of GO.

  6. Repeatedly evolved host-specific ectosymbioses between sulfur-oxidizing bacteria and amphipods living in a cave ecosystem.

    Directory of Open Access Journals (Sweden)

    Jan Bauermeister

    Full Text Available Ectosymbioses between invertebrates and sulfur-oxidizing bacteria are widespread in sulfidic marine environments and have evolved independently in several invertebrate phyla. The first example from a freshwater habitat, involving Niphargus ictus amphipods and filamentous Thiothrix ectosymbionts, was recently reported from the sulfide-rich Frasassi caves in Italy. Subsequently, two new Niphargus species, N. frasassianus and N. montanarius, were discovered within Frasassi and found to co-occur with N. ictus. Using a variety of microscopic and molecular techniques, we found that all three Frasassi-dwelling Niphargus species harbor Thiothrix ectosymbionts, which belong to three distinct phylogenetic clades (named T1, T2, and T3. T1 and T3 Thiothrix dominate the N. frasassianus ectosymbiont community, whereas T2 and T3 are prevalent on N. ictus and N. montanarius. Relative distribution patterns of the three ectosymbionts are host species-specific and consistent over different sampling locations and collection years. Free-living counterparts of T1-T3 are rare or absent in Frasassi cave microbial mats, suggesting that ectosymbiont transmission among Niphargus occurs primarily through inter- or intraspecific inoculations. Phylogenetic analyses indicate that the Niphargus-Thiothrix association has evolved independently at least two times. While ectosymbioses with T1 and T2 may have been established within Frasassi, T3 ectosymbionts seem to have been introduced to the cave system by Niphargus.

  7. Application of a novel functional gene microarray to probe the functional ecology of ammonia oxidation in nitrifying activated sludge.

    Directory of Open Access Journals (Sweden)

    Michael D Short

    Full Text Available We report on the first study trialling a newly-developed, functional gene microarray (FGA for characterising bacterial and archaeal ammonia oxidisers in activated sludge. Mixed liquor (ML and media biofilm samples from a full-scale integrated fixed-film activated sludge (IFAS plant were analysed with the FGA to profile the diversity and relative abundance of ammonia-oxidising archaea and bacteria (AOA and AOB respectively. FGA analyses of AOA and AOB communities revealed ubiquitous distribution of AOA across all samples - an important finding for these newly-discovered and poorly characterised organisms. Results also revealed striking differences in the functional ecology of attached versus suspended communities within the IFAS reactor. Quantitative assessment of AOB and AOA functional gene abundance revealed a dominance of AOB in the ML and approximately equal distribution of AOA and AOB in the media-attached biofilm. Subsequent correlations of functional gene abundance data with key water quality parameters suggested an important functional role for media-attached AOB in particular for IFAS reactor nitrification performance and indicate possible functional redundancy in some IFAS ammonia oxidiser communities. Results from this investigation demonstrate the capacity of the FGA to resolve subtle ecological shifts in key microbial communities in nitrifying activated sludge and indicate its value as a tool for better understanding the linkages between the ecology and performance of these engineered systems.

  8. Intestinal bacteria in bioaerosols and factors affecting their survival in two oxidation ditch process municipal wastewater treatment plants located in different regions.

    Science.gov (United States)

    Wang, Yanjie; Li, Lin; Han, Yunping; Liu, Junxin; Yang, Kaixiong

    2018-06-15

    Samples from two oxidation ditch process municipal wastewater treatment plants (MWTPs) (HJK and GXQ) in two regions of China were analysed for bacteria, particles, total organic carbon, and water-soluble ions in bioaerosols. Diversity and potential pathogen populations were evaluated by high-throughput sequencing. Bioaerosol sources, factors affecting intestinal bacterial survival, and the relationship between bioaerosols and water were analysed by Source tracker and partial least squares-discriminant, principal component, and canonical correspondence analyses. Culturable bacteria concentrations were 110-846 and 27-579 CFU/m 3 at HJK and GXQ, respectively. Intestinal bacteria constituted 6-33% of bacteria. Biochemical reaction tank, sludge dewatering house (SDH), and fine screen samples showed the greatest contribution to bioaerosol contamination. Enterobacter aerogenes was the main intestinal bacteria (> 99.5%) in HJK and detected at each sampling site. Enterobacter aerogenes (98.67% in SDH), Aeromonas sp. (76.3% in biochemical reaction tank), and Acinetobacter baumannii (99.89% in fine screens) were the main intestinal bacteria in GXQ. Total suspended particulate masses in SDH were 229.46 and 141.6 μg/m 3 in HJK and GXQ, respectively. Percentages of insoluble compounds in total suspended particulates decreased as height increased. The main soluble ions in bioaerosols were Ca 2+ , Na + , Cl - , and SO 4 2- , which ranged from 3.8 to 27.55 μg/m 3 in the MWTPs. Water was a main source of intestinal bacteria in bioaerosols from the MWTPs. Bioaerosols in HJK but not in GXQ were closely related. Relative humidity and some ions positively influenced intestinal bacteria in bioaerosols, while wind speed and solar illumination had a negative influence. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Continuously Monocropped Jerusalem Artichoke Changed Soil Bacterial Community Composition and Ammonia-Oxidizing and Denitrifying Bacteria Abundances.

    Science.gov (United States)

    Zhou, Xingang; Wang, Zhilin; Jia, Huiting; Li, Li; Wu, Fengzhi

    2018-01-01

    Soil microbial communities have profound effects on the growth, nutrition and health of plants in agroecosystems. Understanding soil microbial dynamics in cropping systems can assist in determining how agricultural practices influence soil processes mediated by microorganisms. In this study, soil bacterial communities were monitored in a continuously monocropped Jerusalem artichoke (JA) system, in which JA was successively monocropped for 3 years in a wheat field. Soil bacterial community compositions were estimated by amplicon sequencing of the 16S rRNA gene. Abundances of ammonia-oxidizing and denitrifying bacteria were estimated by quantitative PCR analysis of the amoA , nirS , and nirK genes. Results showed that 1-2 years of monocropping of JA did not significantly impact the microbial alpha diversity, and the third cropping of JA decreased the microbial alpha diversity ( P < 0.05). Principal coordinates analysis and permutational multivariate analysis of variance analyses revealed that continuous monocropping of JA changed soil bacterial community structure and function profile ( P < 0.001). At the phylum level, the wheat field was characterized with higher relative abundances of Latescibacteria , Planctomycetes , and Cyanobacteria , the first cropping of JA with Actinobacteria , the second cropping of JA with Acidobacteria , Armatimonadetes , Gemmatimonadetes , and Proteobacteria . At the genus level, the first cropping of JA was enriched with bacterial species with pathogen-antagonistic and/or plant growth promoting potentials, while members of genera that included potential denitrifiers increased in the second and third cropping of JA. The first cropping of JA had higher relative abundances of KO terms related to lignocellulose degradation and phosphorus cycling, the second cropping of JA had higher relative abundances of KO terms nitrous-oxide reductase and nitric-oxide reductase, and the third cropping of JA had higher relative abundances of KO terms

  10. Continuously Monocropped Jerusalem Artichoke Changed Soil Bacterial Community Composition and Ammonia-Oxidizing and Denitrifying Bacteria Abundances

    Directory of Open Access Journals (Sweden)

    Xingang Zhou

    2018-04-01

    Full Text Available Soil microbial communities have profound effects on the growth, nutrition and health of plants in agroecosystems. Understanding soil microbial dynamics in cropping systems can assist in determining how agricultural practices influence soil processes mediated by microorganisms. In this study, soil bacterial communities were monitored in a continuously monocropped Jerusalem artichoke (JA system, in which JA was successively monocropped for 3 years in a wheat field. Soil bacterial community compositions were estimated by amplicon sequencing of the 16S rRNA gene. Abundances of ammonia-oxidizing and denitrifying bacteria were estimated by quantitative PCR analysis of the amoA, nirS, and nirK genes. Results showed that 1–2 years of monocropping of JA did not significantly impact the microbial alpha diversity, and the third cropping of JA decreased the microbial alpha diversity (P < 0.05. Principal coordinates analysis and permutational multivariate analysis of variance analyses revealed that continuous monocropping of JA changed soil bacterial community structure and function profile (P < 0.001. At the phylum level, the wheat field was characterized with higher relative abundances of Latescibacteria, Planctomycetes, and Cyanobacteria, the first cropping of JA with Actinobacteria, the second cropping of JA with Acidobacteria, Armatimonadetes, Gemmatimonadetes, and Proteobacteria. At the genus level, the first cropping of JA was enriched with bacterial species with pathogen-antagonistic and/or plant growth promoting potentials, while members of genera that included potential denitrifiers increased in the second and third cropping of JA. The first cropping of JA had higher relative abundances of KO terms related to lignocellulose degradation and phosphorus cycling, the second cropping of JA had higher relative abundances of KO terms nitrous-oxide reductase and nitric-oxide reductase, and the third cropping of JA had higher relative abundances of KO

  11. Development of hydrogen oxidizing bacteria using hydrogen from radiolysis or metal corrosion; Developpement de populations microbiennes oxydant l'hydrogene produit par radiolyse ou par corrosion des metaux

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M F; Sellier, R; Marty, V; Camaro, S [CEA Cadarache, Dept. d' Entreposage et de Stockage des Dechets (DCC/DESD/SEP), 13 - Saint-Paul-lez-Durance (France)

    2000-07-01

    The effect of many parameters need to be studied to characterize the long term behavior of nuclear waste in a deep repository. These parameters concern the chemical effects, radiolytic effects, mechanical properties, water composition, and microbiological activity. To evaluate microbial activity in such an environment, work was focused on an inventory of key nutrients (C, H, 0, N, P, S) and energy sources required for bacterial growth. The production of hydrogen in the nuclear waste environment leads to the growth of hydrogen oxidizing bacteria, which modify the gas production balance. A deep repository containing bituminized waste drums implies several sources of hydrogen: - water radiolysis; -corrosion of metal containers; - radiolysis of the embedding matrix (bitumen). Two deep geological disposal conditions leading to H{sub 2} production in a bituminized nuclear waste environment were simulated in the present study: - H{sub 2} production by iron corrosion under anaerobic conditions was simulated by adding 10% of H{sub 2} in the atmosphere; - H{sub 2} production by radiolysis of bitumen matrix was approached by subjecting this material to external gamma irradiation with a dose rate near real conditions (6 Gy/h). The presence of dissolved H{sub 2} in water allows the growth of hydrogen oxidizing bacteria leading to: - CO{sub 2} and N{sub 2} production; - H{sub 2} consumption; - lower NO{sub 3}{sup -} concentration caused by reduction to nitrogen. In the first case, hydrogen consumption is limited by the NO{sub 3}{sup -} release rate from the bitumen matrix. In the second case, however, under gamma radiation at a low dose rate, hydrogen production is weak, and the hydrogen is completely consumed by microorganisms. Knowledge about these hydrogen oxidizing bacteria is just beginning to emerge. Heterotrophic denitrifying bacteria adapt well to hydrogen metabolism (autotrophic metabolism) by oxidizing H{sub 2} instead of hydrocarbons. (authors)

  12. EFFECT OF SOLE AND ASSOCIATIVE ACTIONS OF ELEMENTAL SULFUR AND INOCULATION SULFUR OXIDIZING BACTERIA ON GROWTH AND NUTRIENTS CONTENTS OF PEPPER PLANTS AND THE USED SOILS

    Directory of Open Access Journals (Sweden)

    S. A. Ibrahim

    2011-12-01

    Full Text Available A pot experiment was conducted to study the effect of elemental sulfur (E.S rate (2.5 g/kg soil and sulfur oxidizing bacteria on pepper plant and some chemical properties of two representative soil samples varying in their texture and CaCO3 content. Pepper was grown in Shobrakheet clay loam and Nobaria sandy loam soils for 50 days. Each soil was treated with elemental sulfur (2.5 g kg-1 soil and inoculated with two sulfur oxidizing bacteria (S.O.B. No.8 and S.O.B. ATCC 8158. Elemental sulfur with or without sulfur oxidizing bacteria increased shoot dry weights of pepper plants as compared with control. The highest effect was observed with E.S + ATCC 8158 treatment which resulted in increasing the pepper shoot dry weights from 1.36 to 2.08 g pot-1 with the clay loam soil and from 0.77 to 1.37 g pot-1 with the sandy loam soil. The same treatment resulted in the highest plant content of S, N, P, K and micronutrients.

  13. Metal oxide/hydroxide-coated dual-media filter for simultaneous removal of bacteria and heavy metals from natural waters.

    Science.gov (United States)

    Ahammed, M Mansoor; Meera, V

    2010-09-15

    The present study was conducted to compare the performance of a dual-media filter consisting of manganese oxide-coated (MOCS) and iron hydroxide-coated sand (IOCS) with that of IOCS filter and uncoated sand filter in treating water contaminated by microorganisms, heavy metals and turbidity with a view to its use in simple household water purification devices in developing countries. Long-duration column tests were conducted using two natural waters namely, roof-harvested rainwater and canal water. Performance of the filters showed that dual-media filter was more efficient in removing bacteria and heavy metals compared to IOCS filter, while uncoated sand filter showed very poor performance. The average effluent levels for dual-media filter when tested with rainwater were: turbidity 1.0+/-0.1 NTU; total coliforms 3+/-2 MPN/100 mL; heterotrophic plate count 170+/-20 CFU/mL; zinc 0.06+/-0.01 mg/L, while that for IOCS filter were: turbidity 1.0+/-0.1 NTU; total coliforms 4+/-2 MPN/100 mL; heterotrophic plate count 181+/-37 CFU/mL; zinc 0.20+/-0.07 mg/L. Similar results were obtained for canal water also. Up to 900 bed volumes (BV) could be treated without affecting the efficiency in the case of rainwater, while the filter operation had to be terminated after 500 BV due to excessive headloss in the case of canal water. The study thus showed the potential of the dual-media for use in low-cost household water filters for purification of natural waters. Copyright 2010 Elsevier B.V. All rights reserved.

  14. Mathematical modeling of nitrous oxide (N2O) emissions from full-scale wastewater treatment plants.

    Science.gov (United States)

    Ni, Bing-Jie; Ye, Liu; Law, Yingyu; Byers, Craig; Yuan, Zhiguo

    2013-07-16

    Mathematical modeling of N2O emissions is of great importance toward understanding the whole environmental impact of wastewater treatment systems. However, information on modeling of N2O emissions from full-scale wastewater treatment plants (WWTP) is still sparse. In this work, a mathematical model based on currently known or hypothesized metabolic pathways for N2O productions by heterotrophic denitrifiers and ammonia-oxidizing bacteria (AOB) is developed and calibrated to describe the N2O emissions from full-scale WWTPs. The model described well the dynamic ammonium, nitrite, nitrate, dissolved oxygen (DO) and N2O data collected from both an open oxidation ditch (OD) system with surface aerators and a sequencing batch reactor (SBR) system with bubbling aeration. The obtained kinetic parameters for N2O production are found to be reasonable as the 95% confidence regions of the estimates are all small with mean values approximately at the center. The model is further validated with independent data sets collected from the same two WWTPs. This is the first time that mathematical modeling of N2O emissions is conducted successfully for full-scale WWTPs. While clearly showing that the NH2OH related pathways could well explain N2O production and emission in the two full-scale plants studied, the modeling results do not prove the dominance of the NH2OH pathways in these plants, nor rule out the possibility of AOB denitrification being a potentially dominating pathway in other WWTPs that are designed or operated differently.

  15. Characterization of 16S rRNA genes from oil field microbial communities indicates the presence of a variety of sulfate-reducing, fermentative, and sulfide-oxidizing bacteria.

    OpenAIRE

    Voordouw, G; Armstrong, S M; Reimer, M F; Fouts, B; Telang, A J; Shen, Y; Gevertz, D

    1996-01-01

    Oil field bacteria were characterized by cloning and sequencing of PCR-amplified 16S rRNA genes. A variety of gram-negative, sulfate-reducing bacteria was detected (16 members of the family Desulfovibrionaceae and 8 members of the family Desulfobacteriaceae). In contrast, a much more limited number of anaerobic, fermentative, or acetogenic bacteria was found (one Clostridium sp., one Eubacterium sp., and one Synergistes sp.). Potential sulfide oxidizers and/or microaerophiles (Thiomicrospira,...

  16. Biofabrication of zinc oxide nanoparticles using fruit extract of Rosa canina and their toxic potential against bacteria: A mechanistic approach

    International Nuclear Information System (INIS)

    Jafarirad, Saeed; Mehrabi, Meysam; Divband, Baharak; Kosari-Nasab, Morteza

    2016-01-01

    The use of plant extract in the biosynthesis of nanoparticles (NPs) can be an eco-friendly approach and have been suggested as a possible alternative to classic methods namely physical and chemical procedures. In this study, the biosynthesis of zinc oxide (ZnO) NPs by both “conventional heating” (CH) and “microwave irradiation” (MI) methods has been reported. Stable and spherical ZnONPs were produced using zinc nitrate and flesh extract of Rosa canina fruit (rosehip) which was used as a precursor. The flesh extract acts as a reducing and capping agent for generation of ZnONPs. The structural, morphological and colloidal properties of the as-synthesized NPs have been confirmed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier transform Infrared (FT-IR) and Dynamic Light Scattering (DLS). In comparison with the CH method, the MI method has some advantages such as significantly short reaction time (within 8 min) owing to the high heating rate and thus the accelerated reaction rate. Both methods led to the synthesis of nearly identical NPs with respect to shape and size according to the results of DLS, XRD and SEM techniques. The possible mechanism for synthesis pathway has been proposed based on FT IR results, XRD patterns, potentiometric data and antioxidant activity. In addition, the antibacterial activity of as-prepared ZnONPs was investigated against several bacteria such as Listeria monocytogenes, Escherichia coli, Salmonella typhimurium. Moreover, the efficacy of ZnONPs to treat cancer cell lines were measured by means of cell viability test via MTT assay in which concentrations of 0.05 and 0.1 mg/mL of ZnONPs induced a very low toxicity. Thus, the present investigation reveals that ZnONPs have the potential for various medical and industrial applications. - Highlights: • We report a green producing route from biomaterials to potentially biomedical applications. • We comprise two methods in respect

  17. Biofabrication of zinc oxide nanoparticles using fruit extract of Rosa canina and their toxic potential against bacteria: A mechanistic approach

    Energy Technology Data Exchange (ETDEWEB)

    Jafarirad, Saeed; Mehrabi, Meysam [Research Institute for Fundamental Sciences (RIFS), University of Tabriz, Tabriz (Iran, Islamic Republic of); Divband, Baharak [Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Inorganic Chemistry Department, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Kosari-Nasab, Morteza [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of)

    2016-02-01

    The use of plant extract in the biosynthesis of nanoparticles (NPs) can be an eco-friendly approach and have been suggested as a possible alternative to classic methods namely physical and chemical procedures. In this study, the biosynthesis of zinc oxide (ZnO) NPs by both “conventional heating” (CH) and “microwave irradiation” (MI) methods has been reported. Stable and spherical ZnONPs were produced using zinc nitrate and flesh extract of Rosa canina fruit (rosehip) which was used as a precursor. The flesh extract acts as a reducing and capping agent for generation of ZnONPs. The structural, morphological and colloidal properties of the as-synthesized NPs have been confirmed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier transform Infrared (FT-IR) and Dynamic Light Scattering (DLS). In comparison with the CH method, the MI method has some advantages such as significantly short reaction time (within 8 min) owing to the high heating rate and thus the accelerated reaction rate. Both methods led to the synthesis of nearly identical NPs with respect to shape and size according to the results of DLS, XRD and SEM techniques. The possible mechanism for synthesis pathway has been proposed based on FT IR results, XRD patterns, potentiometric data and antioxidant activity. In addition, the antibacterial activity of as-prepared ZnONPs was investigated against several bacteria such as Listeria monocytogenes, Escherichia coli, Salmonella typhimurium. Moreover, the efficacy of ZnONPs to treat cancer cell lines were measured by means of cell viability test via MTT assay in which concentrations of 0.05 and 0.1 mg/mL of ZnONPs induced a very low toxicity. Thus, the present investigation reveals that ZnONPs have the potential for various medical and industrial applications. - Highlights: • We report a green producing route from biomaterials to potentially biomedical applications. • We comprise two methods in respect

  18. Anaerobic bacteria

    Science.gov (United States)

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Brook I. Diseases caused by non-spore-forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  19. Spatial and temporal distribution of nitrite-dependent anaerobic methane-oxidizing bacteria in an intertidal zone of the East China Sea.

    Science.gov (United States)

    Wang, Jiaqi; Shen, Lidong; He, Zhanfei; Hu, Jiajie; Cai, Zhaoyang; Zheng, Ping; Hu, Baolan

    2017-11-01

    Nitrite-dependent anaerobic methane oxidation (N-DAMO), which couples anaerobic methane oxidation and nitrite reduction, is a recently discovered bioprocess coupling microbial nitrogen and carbon cycles. The discovery of this microbial process challenges the traditional knowledge of global methane sinks and nitrogen losses. In this study, the abundance and activity of N-DAMO bacteria were investigated and their contributions to methane sink and nitrogen loss were estimated in different seasons and different partitions of an intertidal zone of the East China Sea. The results showed that N-DAMO bacteria were extensively and continuously present in the intertidal zone, with the number of cells ranging from 5.5 × 10 4 to 2.8 × 10 5 copy g -1 soil and the potential activity ranging from 0.52 to 5.7 nmol CO 2  g -1 soil day -1 , contributing 5.0-36.6% of nitrite- and sulfate-dependent anaerobic methane oxidation in the intertidal zone. The N-DAMO activity and its contribution to the methane consumption were highest in the spring and in the low intertidal zone. These findings showed that the N-DAMO process is an important methane and nitrogen sink in the intertidal zone and varies with the seasons and the partitions of the intertidal zone.

  20. Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

    Directory of Open Access Journals (Sweden)

    B. Orcutt

    2008-11-01

    Full Text Available Anaerobic oxidation of methane (AOM is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H2, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal were examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species can cause the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007, none of the potential intermediates considered here is able to support metabolic activity matching the measured rates.

  1. Molecular and stable isotopic evidence for the occurrence of nitrite-dependent anaerobic methane-oxidizing bacteria in the mangrove sediment of Zhangjiang Estuary, China.

    Science.gov (United States)

    Zhang, Manping; Luo, Yi; Lin, Li'an; Lin, Xiaolan; Hetharua, Buce; Zhao, Weijun; Zhou, Mengkai; Zhan, Qing; Xu, Hong; Zheng, Tianling; Tian, Yun

    2018-03-01

    Nitrite-dependent anaerobic methane oxidation (n-damo), which is mediated by "Candidatus Methylomirabilis oxyfera-like" bacteria, is unique in linking the carbon and nitrogen cycles. However, the niche and activity of n-damo bacteria in the mangrove ecosystem have not been confirmed. Here, we report the occurrence of the n-damo process in the mangrove wetland of the Zhangjiang Estuary, China. The widespread occurrence of n-damo bacteria in mangrove wetland was confirmed using real-time quantitative polymerase chain reaction (qPCR) assay, which showed that the abundance of Methylomirabilis oxyfera-like bacterial 16S rRNA and pmoA genes ranged from 2.43 × 10 6 to 2.09 × 10 7 and 2.07 × 10 6 to 3.38 × 10 7 copies per gram of dry soil in the examined sediment cores. The highest amount of targeting genes was all detected in the upper layer (0-20 cm). Phylogenetic analyses of n-damo bacterial 16S rRNA and pmoA genes illustrated the depth-specific distribution and high diversity of n-damo bacteria in the mangrove wetland. Stable isotope experiments further confirmed the occurrence of n-damo in the examined mangrove sediments, and the potential n-damo rates ranged from 25.93 to 704.08 nmol CO 2 per gram of dry soil per day at different depths of the sediment cores, with the n-damo being more active in the upper layer of the mangrove sediments. These results illustrate the existence of active M. oxyfera-like bacteria and indicate that the n-damo process is a previously overlooked microbial methane sink in the mangrove wetlands.

  2. A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions

    Science.gov (United States)

    Drinking water monochloramine (NH2Cl) use may promote ammonia–oxidizing bacteria (AOB) growth. For biological ammonia (NH3) oxidation, AOB use (i) ammonia monooxygenase for NH3 oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrit...

  3. Antioxidant efficacy of crude methanol extract of ashitaba green tea against radiation induced oxidative stress in E.coli K12 bacteria

    International Nuclear Information System (INIS)

    Darshan Raj, C.G.; Sindhu Priya, E.S.; Sarojini, B.K.

    2013-01-01

    This study was undertaken to evaluate the antioxidant activity of methanol crude extract of ashitaba green tea (G). The DPPH scavenging assay was evaluated for green tea extract to determine its radical scavenging capacity. The bacteria was pretreated with ashitaba green tea extract, quercetin (Q) and (-) epigallocatechin -3-gallate (E) at below MIC level. Oxidative stress was induced at 0.4 Gy using gamma radiation. The antioxidant efficacy of ashitaba green tea was evaluated through enzyme antioxidant studies like SOD (Superoxidedismutase) and CAT (Catalase). The oxidative stress marker Thiobarbituric acid-reactive substance (TBARS) was also evaluated. Further the protective efficacy of the(G) was confirmed by colony forming units (CFU) study. Among the tested compounds the crude extract of ashitaba (G) exhibited excellent antioxidant activity in comparison with quercetin and (-) epigallocatechin -3-gallate. (abstract)

  4. Potato cultivar type affects the structure of ammonia oxidizer communities in field soil under potato beyond the rhizosphere

    NARCIS (Netherlands)

    Cavalcante Franco Dias, A.; Hoogwout, E.F.; de Cassia Pereira e Silva, M.; Falcão Salles, J.; van Overbeek, L.S.; van Elsas, J.D.

    The effects of plants on the microbiota involved in the oxidation of ammonia in soils have been controversial. Here, we investigated the dynamics in the abundances and community structures of the bacterial and archaeal ammonia oxidizers (AOB and AOA, respectively) in two fields that were cropped

  5. Native plant growth promoting bacteria Bacillus thuringiensis and mixed or individual mycorrhizal species improved drought tolerance and oxidative metabolism in Lavandula dentata plants.

    Science.gov (United States)

    Armada, E; Probanza, A; Roldán, A; Azcón, R

    2016-03-15

    This study evaluates the responses of Lavandula dentata under drought conditions to the inoculation with single autochthonous arbuscular mycorrhizal (AM) fungus (five fungal strains) or with their mixture and the effects of these inocula with a native Bacillus thuringiensis (endophytic bacteria). These microorganisms were drought tolerant and in general, increased plant growth and nutrition. Particularly, the AM fungal mixture and B. thuringiensis maximized plant biomass and compensated drought stress as values of antioxidant activities [superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase APX)] shown. The AMF-bacteria interactions highly reduced the plant oxidative damage of lipids [malondialdehyde (MDA)] and increased the mycorrhizal development (mainly arbuscular formation representative of symbiotic functionality). These microbial interactions explain the highest potential of dually inoculated plants to tolerate drought stress. B. thuringiensis "in vitro" under osmotic stress does not reduce its PGPB (plant growth promoting bacteria) abilities as indole acetic acid (IAA) and ACC deaminase production and phosphate solubilization indicating its capacity to improve plant growth under stress conditions. Each one of the autochthonous fungal strains maintained their particular interaction with B. thuringiensis reflecting the diversity, intrinsic abilities and inherent compatibility of these microorganisms. In general, autochthonous AM fungal species and particularly their mixture with B. thuringiensis demonstrated their potential for protecting plants against drought and helping plants to thrive in semiarid ecosystems. Copyright © 2015 Elsevier GmbH. All rights reserved.

  6. Iron-Oxidizing Bacteria Found at Slow-Spreading Ridge: a Case Study of Capelinhos Hydrothermal Vent (Lucky Strike, MAR 37°N)

    Science.gov (United States)

    Henri, P. A.; Rommevaux, C.; Lesongeur, F.; Emerson, D.; Leleu, T.; Chavagnac, V.

    2015-12-01

    Iron-oxidizing bacteria becomes increasingly described in different geological settings from volcanically active seamounts, coastal waters, to diffuse hydrothermal vents near seafloor spreading centers [Emerson et al., 2010]. They have been mostly identified and described in Pacific Ocean, and have been only recently found in hydrothermal systems associated to slow spreading center of the Mid-Atlantic Ridge (MAR) [Scott et al., 2015]. During the MoMARSAT'13 cruise at Lucky Strike hydrothermal field (MAR), a new hydrothermal site was discovered at about 1.5 km eastward from the lava lake and from the main hydrothermal vents. This active venting site, named Capelinhos, is therefore the most distant from the volcano, features many chimneys, both focused and diffuses. The hydrothermal end-member fluids from Capelinhos are different from those of the other sites of Lucky Strike, showing the highest content of iron (Fe/Mn≈3.96) and the lowest chlorinity (270 mmol/l) [Leleu et al., 2015]. Most of the chimneys exhibit rust-color surfaces and bacterial mats near diffuse flows. During the MoMARSAT'15 cruise, an active chimney, a small inactive one, and rust-color bacterial mat near diffuse flow were sampled at Capelinhos. Observations by SEM of the hydrothermal samples revealed the presence of iron oxides in an assemblage of tubular "sheaths", assembled "stalks", helical "stalks" and amorphous aggregates. These features are similar to those described from the Loihi iron-mats deposits and argue for the occurrence of iron-oxidizing bacteria. Cultures under micro-aerobic and neutral pH conditions allowed us to isolate strains from the small inactive chimney. Pyrosequencing of the 16S rRNA gene of the isolates and environmental samples will soon be performed, which should confirm the presence of iron-oxidizing bacteria and reveal the organization of bacterial communities in this original and newly discovered hydrothermal site of the slow spreading Mid-Atlantic Ridge. Emerson

  7. Role of a unique population of lithotrophic, Fe-oxidizing bacteria in forming microbial Fe-mats at the Loihi Seamount.

    Science.gov (United States)

    Emerson, D.; Rentz, J. A.; Moyer, C. L.

    2005-12-01

    The Loihi Seamount, located 30 km SE of the island of Hawai'i, is among the most active volcanos on Earth. The summit, at a depth of 1100m, includes a 250m deep caldera (Pele's Pit) formed by an eruption in 1996. The summit, and especially Pele's Pit, are the site of extensive low to intermediate temperature (10° to 65°C) hydrothermal venting, emanating both from diffuse fissures and orifices that have substantial flow rates. The vent fluid is characterized by a low sulfide content, high CO2 concentrations and Fe(II) amounts in the 10s to 100s of μM. Associated with all vents are extensive deposits of iron oxyhydroxides that typically have 107 to 108 bacterial cells/cc associated with them. The morphology of the Fe-oxides are indicative of biological origins. We have isolated microaerophilic, obligately lithotrophic Fe-oxidizing bacteria from Loihi and describe here `Mariprofundus ferroxydans' a unique bacterium that forms a filamentous iron oxide mineral. `M. ferroxydans' is the first cultured representative of a novel division of the Proteobacteria, known previously only from clones from different hydrothermal vent sites. Molecular evidence from Loihi mats based on clone libraries and terminal restriction length polymorphism (T-RFLP) analysis of 16S rRNA genes indicate that this lineage of Fe-oxidizing organisms are common inhabitants at Loihi. We speculate that this organism and its relatives form the basis of an active microbial mat community that owe their existence to the inherent gradients of Fe(II) and O2 that exist at the Loihi vents. In a geological context this is interesting because the Loihi summit and caldera are in an O2-minima zone; O2 concentrations in the bulk seawater are around 0.5 mg/l. In effect, Loihi could serve as a proxy for the late Archaean and early Proterozoic periods when the Earth's atmosphere went from reducing to oxidizing, and it is speculated that abundant Fe(II) in the Earth's oceans served as a major sink for O2 production

  8. Effects of combination of magnesium and zinc oxide nanoparticles and heat on Escherichia coli and Staphylococcus aureus bacteria in milk

    Directory of Open Access Journals (Sweden)

    M. Kimiaee Sadr

    2016-01-01

    Full Text Available Objective: The objective of this study was to investigate the antibacterial activities of combination of MgO and ZnO nanoparticles in the presence of heat against Escherichia coli and Staphylococcus aureus. Materials and Methods:Bacteria were grown on either agar or broth media followed by the addition of ZnO and MgO nanoparticles. Then the combined effect of ZnO and MgO nanoparticles was investigated.  Furthermore, the media containing nanoparticles were treated with mild heat and their synergistic antibacterial activity was investigated against E. coli and S. aureus in milk. Results: The data showed that the nanoparticles used in this study had no effect on the bacteria in the agar medium. However, the results showed that ZnO and MgO nanoparticles resulted in a significant decrease in the number of E. coli (P

  9. Ecophysiology of the Anammox Bacteria

    NARCIS (Netherlands)

    Kartal, M.B.

    2008-01-01

    Anaerobic ammonium oxidizing (anammox) bacteria oxidize ammonium to dinitrogen gas with nitrite as the electron acceptor. These bacteria are the key players in the global nitrogen cycle, responsible for the most of nitrogen production in natural ecosystems. The anammox process is also a

  10. Identification of syntrophic acetate-oxidizing bacteria in anaerobic digesters by combined protein-based stable isotope probing and metagenomics

    OpenAIRE

    Mosbæk, Freya; Kjeldal, Henrik; Mulat, Daniel G; Albertsen, Mads; Ward, Alastair J; Feilberg, Anders; Nielsen, Jeppe L

    2016-01-01

    Inhibition of anaerobic digestion through accumulation of volatile fatty acids occasionally occurs as the result of unbalanced growth between acidogenic bacteria and methanogens. A fast recovery is a prerequisite for establishing an economical production of biogas. However, very little is known about the microorganisms facilitating this recovery. In this study, we investigated the organisms involved by a novel approach of mapping protein-stable isotope probing (protein-SIP) onto a binned meta...

  11. Effects of the conversion of cropland to forest on the CH4 oxidation capacity in soils.

    Science.gov (United States)

    Bárcena, Teresa G.; D'Imperio, Ludovica; Priemé, Anders; Gundersen, Per; Vesterdal, Lars; Christiansen, Jesper R.

    2013-04-01

    As the second most important greenhouse gas (GHG) in the atmosphere, methane (CH4) plays a central role in global warming. Diverse types of soil have been reported as potential CH4 sinks due to the activity of methane oxidizing bacteria (MOB), underlining the importance of this functional group of microorganisms on a global basis. Agricultural practices are known to negatively affect CH4 oxidation in soil, while afforestation of former agricultural soils has been shown to enhance CH4 oxidation over time. However, knowledge is scarce with regard to the mechanisms driving the process of CH4 oxidation in different land uses. Our aim was to study the changes in CH4 uptake capacity in soils along a land-use change gradient from cropland to forest. We performed an incubation experiment to study the CH4 oxidation capacity of the top mineral soil (0-5 cm and 5-15 cm depth) for sites representing the transition from agriculture to afforestation based on monoculture of three tree species with different stand ages: pedunculate oak (4, 19, 42 and >200 years old), European larch (22 and 41 years old) and Norway spruce (15 and 43 years old). Main soil parameters were also measured to determine differences in soil properties between sites. Methane oxidation rates were related to the abundance of the soil methanotrophic community based on quantitative PCR (qPCR). In addition, we also estimated the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA), in order to investigate the link between these two similar functional groups. Although present, the abundance of AOB was under detection limit. The effects and interactions among all measured variables were summarized by Principal Component Analysis (PCA). Along the gradient, CH4 oxidation increased with increasing stand age in both soil layers (ranging from 0-1.3 nmol g-1dw d-1). However, we detected significant differences, in particular between oak and spruce, suggesting a possible tree species effect on the CH4

  12. In-depth characterization of the fluorescent signal of HyPer, a probe for hydrogen peroxide, in bacteria exposed to external oxidative stress.

    Science.gov (United States)

    Lim, Joseph B; Barker, Kimberly A; Huang, Beijing K; Sikes, Hadley D

    2014-11-01

    Genetically encoded, fluorescent biosensors have been developed to probe the activities of various signaling molecules inside cells ranging from changes in intracellular ion concentrations to dynamics of lipid second messengers. HyPer is a member of this class of biosensors and is the first to dynamically respond to hydrogen peroxide (H2O2), a reactive oxygen species that functions as a signaling molecule. However, detailed characterization of HyPer's signal is not currently available within the context of bacteria exposed to external oxidative stress, which occurs in the immunological response of higher organisms against invasive pathogenic bacteria. Here, we performed this characterization, specifically in Escherichia coli exposed to external H2O2. We found that the temporal behavior of the signal does not correspond exactly to peroxide concentration in the system as a function of time and expression of the sensor decreases the peroxide scavenging activity of the cell. We also determined the effects of cell number, both before and after normalization of externally added H2O2 to the number of cells. Finally, we report quantitative characteristics of HyPer's signal in this context, including the dynamic range of the signal, the signal-to-noise ratio, and the half saturation constant. These parameters show statistically meaningful differences in signal between two commonly used strains of E. coli, demonstrating how signal can vary with strain. Taken together, our results establish a systematic, quantitative framework for researchers seeking to better understand the role of H2O2 in the immunological response against bacteria, and for understanding potential differences in the details of HyPer's quantitative performance across studies. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Bioenergetic studies of coal sulfur oxidation by extremely thermophilic bacteria. Final report, September 15, 1992--August 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.M.; Han, C.J.

    1997-12-31

    Thermoacidophilic microorganisms have been considered for inorganic sulfur removal from coal because of expected improvements in rates of both biotic and abiotic sulfur oxidation reactions with increasing temperature. In this study, the bioenergetic response of the extremely thermoacidophilic archaeon, Metallosphaera sedula, to environmental changes have been examined in relation to its capacity to catalyze pyrite oxidation in coal. Given an appropriate bioenergetic challenge, the metabolic response was to utilize additional amounts of energy sources (i.e., pyrite) to survive. Of particular interest were the consequences of exposing the organism to various forms of stress (chemical, nutritional, thermal, pH) in the presence of coal pyrite. Several approaches to take advantage of stress response to accelerate pyrite oxidation by this organism were examined, including attempts to promote acquired thermal tolerance to extend its functional range, exposure to chemical uncouplers and decouplers, and manipulation of heterotrophic and chemolithotrophic tendencies to optimize biomass concentration and biocatalytic activity. Promising strategies were investigated in a continuous culture system. This study identified environmental conditions that promote better coupling of biotic and abiotic oxidation reactions to improve biosulfurization rates of thermoacidophilic microorganisms.

  14. Chemical Modification and Detoxification of the Pseudomonas aeruginosa Toxin 2-Heptyl-4-hydroxyquinoline N-Oxide by Environmental and Pathogenic Bacteria.

    Science.gov (United States)

    Thierbach, Sven; Birmes, Franziska S; Letzel, Matthias C; Hennecke, Ulrich; Fetzner, Susanne

    2017-09-15

    2-Heptyl-4-hydroxyquinoline N-oxide (HQNO), a major secondary metabolite and virulence factor produced by the opportunistic pathogen Pseudomonas aeruginosa, acts as a potent inhibitor of respiratory electron transfer and thereby affects host cells as well as microorganisms. In this study, we demonstrate the previously unknown capability of environmental and pathogenic bacteria to transform and detoxify this compound. Strains of Arthrobacter and Rhodococcus spp. as well as Staphylococcus aureus introduced a hydroxyl group at C-3 of HQNO, whereas Mycobacterium abscessus, M. fortuitum, and M. smegmatis performed an O-methylation, forming 2-heptyl-1-methoxy-4-oxoquinoline as the initial metabolite. Bacillus spp. produced the glycosylated derivative 2-heptyl-1-(β-d-glucopyranosydyl)-4-oxoquinoline. Assaying the effects of these metabolites on cellular respiration and on quinol oxidase activity of membrane fractions revealed that their EC 50 values were up to 2 orders of magnitude higher than that of HQNO. Furthermore, cellular levels of reactive oxygen species were significantly lower in the presence of the metabolites than under the influence of HQNO. Therefore, the capacity to transform HQNO should lead to a competitive advantage against P. aeruginosa. Our findings contribute new insight into the metabolic diversity of bacteria and add another layer of complexity to the metabolic interactions which likely contribute to shaping polymicrobial communities comprising P. aeruginosa.

  15. Insights into high-temperature nitrogen cycling from studies of the thermophilic ammonia-oxidizing archaeon Nitrosocaldus yellowstonii. (Invited)

    Science.gov (United States)

    de la Torre, J. R.

    2010-12-01

    Our understanding of the nitrogen cycle has advanced significantly in recent years with the discovery of new metabolic processes and the recognition that key processes such as aerobic ammonia oxidation are more broadly distributed among extant organisms and habitat ranges. Nitrification, the oxidation of ammonia to nitrite and nitrate, is a key component of the nitrogen cycle and, until recently, was thought to be mediated exclusively by the ammonia-oxidizing bacteria (AOB). The discovery that mesophilic marine archaea, some of the most abundant microorganisms on the planet, are capable of oxidizing ammonia to nitrite fundamentally changed our perception of the global nitrogen cycle. Ammonia-oxidizing archaea (AOA) are now thought to be significant drivers of nitrification in many marine and terrestrial environments. Most studies, however, have focused on the contribution of AOA to nitrogen cycling in mesophilic environments. Our recent discovery of a thermophilic AOA, Nitrosocaldus yellowstonii, has expanded the role and habitat range of AOA to include high temperature environments. Numerous studies have shown that AOA are widely distributed in geothermal habitats with a wide range of temperature and pH. The availability of multiple AOA genome sequences, combined with metagenomic studies from mesophilic and thermophilic environments gives us a better understanding of the physiology, ecology and evolution of these organisms. Recent studies have proposed that the AOA represent the most deeply branching lineage within the Archaea, the Thaumarchaeota. Furthermore, genomic comparisons between AOA and AOB reveal significant differences in the proposed pathways for ammonia oxidation. These genetic differences likely explain fundamental physiological differences such as the resistance of N. yellowstonii and other AOA to the classical nitrification inhibitors allylthiourea and acetylene. Physiological studies suggest that the marine AOA are adapted to oligotrophic

  16. Benthic Ammonia Oxidizers Differ in Community Structure and Biogeochemical Potential Across a Riverine Delta

    Directory of Open Access Journals (Sweden)

    Julian eDamashek

    2015-01-01

    Full Text Available Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California’s Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the massive discharge of ammonium into the Sacramento River has altered this ecosystem by increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (encoding the α-subunit of ammonia monooxygenase. There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB outnumbering ammonia-oxidizing archaea (AOA only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The community structure and biogeochemical function of benthic ammonia oxidizers appears related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways is a critical step toward understanding how such ecosystems respond to the changing environmental conditions wrought by human development and climate change.

  17. Enriquecimento de bactérias anaeróbias oxidadoras de amônia - anammox Enrichment of anaerobic ammonium oxidizing bacteria - anammox

    Directory of Open Access Journals (Sweden)

    Juliana Calábria de Araújo

    2010-06-01

    Full Text Available Bactérias anaeróbias oxidadoras de amônia (bactérias Anammox, do inglês anaerobic ammonium oxidizing bacteria foram enriquecidas em reator em batelada sequencial (RBS, a partir de lodo proveniente de um sistema convencional de lodos ativados tratando esgoto doméstico de Belo Horizonte (MG. Após três meses de cultivo, atividade Anammox foi detectada no sistema pelo consumo de quantidades estequiométricas de NO2- e NH4+. Análises de hibridação in situ fluorescente (FISH, do inglês fluorescent in situ hybridization confirmaram a presença de bactérias Anammox, provavelmente Candidatus Brocadia anammoxidans, e revelaram que estas representavam 53% do total de células (após 6 meses de cultivo. O desempenho do reator ao longo dos sete meses de operação demonstrou remoção quase que total de nitrito, baseada em concentração afluente de 61 a 95 mg N-NO2-/L. A eficiência máxima de remoção de amônia alcançada foi de 95%, a partir de concentração afluente de 55 a 82 mg N-NH4+/L.Anaerobic ammonium-oxidizing (Anammox bacteria were enriched from sludge collected at a conventional activated sludge system treating domestic wastewater of Belo Horizonte(MG, Brazil, employing a sequencing batch reactor (SBR. After three months of cultivation, Anammox activity was detected in the system by the consumption of stoichiometric amounts of NO2- and NH4+. Fluorescent in situ hybridization (FISH results revealed the presence of Anammox bacteria (probably Candidatus Brocadia anammoxidans and showed that they accounted for 53% of the total bacterial population (after 6 months of cultivation. The reactor performance during the seven months of operation showed a near perfect removal of nitrite, based on the influent NO2--N concentration of 61-95 mg/L. The maximum ammonia removal efficiency was 95% from the influent N-NH4+ concentration of 55-82 mg/L.

  18. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production

    Science.gov (United States)

    Venterea, R. T.; Sadowsky, M.; Breuillin-Sessoms, F.; Wang, P.; Clough, T. J.; Coulter, J. A.

    2015-12-01

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted 'hot spots' and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and genes associated with nitrification in two soils ('L' and 'W') having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH3) was also calculated accounting for non-linear ammonium (NH4+) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO3-) levels than soil L, but was more resistant to nitrite (NO2-) accumulation and produced two to ten times less N2O than soil L. Genes associated with NO2- oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO2- was strongly correlated with N2O production, and cumulative (c-) slNH3 explained 87% of the variance in c-NO2-. Differences between soils were explained by greater slNH3 in soil L which inhibited NO2- oxidization leading to greater NO2- levels and N2O production. This is the first study to correlate the dynamics of soil slNH3, NO2-, N2O and nitrifier genes, and the first to show how ASC can regulate NO2- levels and N2O production.

  19. From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources.

    Science.gov (United States)

    Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

    2015-01-01

    At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe(2+) ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD(+) through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

  20. Start-up strategies of membrane-aerated biofilm reactor (MABR) for completely autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Sun, Sheng-Peng; Pellicer i Nàcher, Carles; Terada, Akihiko

    2009-01-01

    Completely autotrophic nitrogen removal, coupling aerobic and anaerobic ammonium oxidation, can be achieved via redox stratified biofilms growing on gas-permeable membranes. These sequential reactions are mediated by aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB). The major...

  1. Concomitant ingestion of lactic acid bacteria and black tea synergistically enhances flavonoid bioavailability and attenuates d-galactose-induced oxidative stress in mice via modulating glutathione antioxidant system.

    Science.gov (United States)

    Zhao, Danyue; Shah, Nagendra P

    2016-12-01

    Black tea (BT) has been positively linked to improved redox status, while its efficacy is limited due to the low bioavailability of BT flavonoids. In addition to the direct antioxidant activity, flavonoids regulate redox balance via inducing endogenous antioxidants, particularly glutathione (GSH) and GSH-dependent antioxidant enzymes. This work first examined the effect of lactic acid bacteria (LAB) and BT alone or in combination on flavonoid bioavailability and metabolism; next, the effect of LAB-fermented BT diet in attenuating oxidative stress in mice and the underlying mechanisms were studied. Phenolic profiles of plasma, urine and feces from healthy mice consuming plain yogurt, BT milk (BTM) or BT yogurt (BTY) were acquired using LC-MS/MS. Plasma antioxidant capacity, lipid peroxidation level, content of nonprotein thiols and expression of GSH-related antioxidant enzymes and Nrf2 were examined in d-galactose-treated mice. Total flavonoid content in plasma following a single dose of BTY attained 0.657 μmol/l, increased by 50% compared with the BTM group. Increased excretion of phenolic metabolite and hippuric acid in urine and feces indicated enhanced metabolism of flavonoids in BTY-fed mice. In the second study, 8-week concomitant LAB-BT treatment of oxidatively stressed mice effectively restored plasma antioxidant capacity and GSH levels, and mitigated lipid peroxidation, which were associated with significant induction of GSH-dependent antioxidant enzymes and nuclear accumulation of Nrf2. Our results demonstrated the effect of LAB fermentation in enhancing BT flavonoid bioavailability in vivo. The synergistic antioxidant efficacy of LAB-BT diet implied its therapeutic potential in enhancing antioxidant defenses and protecting organisms from oxidative damage. Copyright © 2016. Published by Elsevier Inc.

  2. Nitrite-Oxidizing Bacteria Community Composition and Diversity Are Influenced by Fertilizer Regimes, but Are Independent of the Soil Aggregate in Acidic Subtropical Red Soil.

    Science.gov (United States)

    Han, Shun; Li, Xiang; Luo, Xuesong; Wen, Shilin; Chen, Wenli; Huang, Qiaoyun

    2018-01-01

    and Mantel test indicated that soil nitrogen, carbon, phosphorus, and available potassium content were important environmental attributes that control the Nitrobacter - and Nitrospira -like NOB community structure across different fertilization treatments under aggregate levels in the red soil. In general, nitrite-oxidizing bacteria community composition and alpha-diversity are depending on fertilizer regimes, but independent of the soil aggregate.

  3. Molecular Fingerprint and Dominant Environmental Factors of Nitrite-Dependent Anaerobic Methane-Oxidizing Bacteria in Sediments from the Yellow River Estuary, China.

    Directory of Open Access Journals (Sweden)

    Pengze Yan

    Full Text Available Nitrite-dependent anaerobic methane oxidation (n-damo is performed by "Candidatus Methylomirabilis oxyfera" (M. oxyfera, which connects the carbon and nitrogen global nutrient cycles. In the present study, M. oxyfera-like bacteria sequences were successfully recovered from Yellow River Estuary sediments using specific primers for 16S rRNA and pmoA genes. A M. oxyfera-like sequences analysis based on the 16S rRNA gene revealed greater diversity compared with the pmoA gene; the 16S rRNA gene sequences retrieved from the Yellow River Estuary sediments belong to groups A as well as B and were mainly found in freshwater habitats. Quantitative PCR showed that 16S rRNA gene abundance varied from 9.28±0.11×10(3 to 2.10±0.13×10(5 copies g(-1 (dry weight, and the pmoA gene abundance ranged from 8.63±0.50×10(3 to 1.83±0.18×10(5 copies g(-1 (dry weight. A correlation analysis showed that the total organic carbon (TOC and ammonium (NH4(+ as well as the ratio of total phosphorus to total nitrogen (TP/TN influenced the M. oxyfera-like bacteria distribution in the Yellow River Estuary sediments. These findings will aid in understanding the n-damo bacterial distribution pattern as well as their correlation with surrounding environmental factors in temperate estuarine ecosystems.

  4. Molecular Fingerprint and Dominant Environmental Factors of Nitrite-Dependent Anaerobic Methane-Oxidizing Bacteria in Sediments from the Yellow River Estuary, China.

    Science.gov (United States)

    Yan, Pengze; Li, Mingcong; Wei, Guangshan; Li, Han; Gao, Zheng

    2015-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is performed by "Candidatus Methylomirabilis oxyfera" (M. oxyfera), which connects the carbon and nitrogen global nutrient cycles. In the present study, M. oxyfera-like bacteria sequences were successfully recovered from Yellow River Estuary sediments using specific primers for 16S rRNA and pmoA genes. A M. oxyfera-like sequences analysis based on the 16S rRNA gene revealed greater diversity compared with the pmoA gene; the 16S rRNA gene sequences retrieved from the Yellow River Estuary sediments belong to groups A as well as B and were mainly found in freshwater habitats. Quantitative PCR showed that 16S rRNA gene abundance varied from 9.28±0.11×10(3) to 2.10±0.13×10(5) copies g(-1) (dry weight), and the pmoA gene abundance ranged from 8.63±0.50×10(3) to 1.83±0.18×10(5) copies g(-1) (dry weight). A correlation analysis showed that the total organic carbon (TOC) and ammonium (NH4(+)) as well as the ratio of total phosphorus to total nitrogen (TP/TN) influenced the M. oxyfera-like bacteria distribution in the Yellow River Estuary sediments. These findings will aid in understanding the n-damo bacterial distribution pattern as well as their correlation with surrounding environmental factors in temperate estuarine ecosystems.

  5. Applying Molecular Tools for Monitoring Inhibition of Nitrification by Heavy Metals

    Science.gov (United States)

    The biological removal of ammonia in conventional wastewater treatment plants (WWTPs) is performed by promoting nitrification and denitrification as sequential steps. The first step in nitrification, the oxidation of ammonia to nitrite by ammonia oxidizing bacteria (AOB), is sens...

  6. Comparison of nitrogen removal rates and nitrous oxide production from enriched anaerobic ammonium oxidizing bacteria in suspended and attached growth reactors.

    Science.gov (United States)

    Panwivia, Supaporn; Sirvithayapakorn, Sanya; Wantawin, Chalermraj; Noophan, Pongsak Lek; Munakata-Marr, Junko

    2014-01-01

    Attached growth-systems for the anaerobic ammonium oxidation (anammox) process have been postulated for implementation in the field. However, information about the anammox process in attached growth-systems is limited. This study compared nitrogen removal rates and nitrous oxide (N2O) production of enriched anammox cultures in both suspended and attached growth sequencing batch reactors (SBRs). Suspended growth reactors (SBR-S) and attached growth reactors using polystyrene sponge as a medium (SBR-A) were used in these experiments. After inoculation with an enriched anammox culture, significant nitrogen removals of ammonium (NH4 (+)) and nitrite (NO2 (-)) were observed under NH4 (+):NO2 (-) ratios ranging from 1:1 to 1:2 in both types of SBRs. The specific rates of total nitrogen removal in SBR-S and SBR-A were 0.52 mg N/mg VSS-d and 0.44 mg N/mg VSS-d, respectively, at an NH4 (+):NO2 (-) ratio of 1:2. N2O production by the enriched anammox culture in both SBR-S and SBR-A was significantly higher at NH4 (+):NO2 (-) ratio of 1:2 than at NH4 (+):NO2 (-) ratios of 1:1 and 1:1.32. In addition, N2O production was higher at a pH of 6.8 than at pH 7.3, 7.8, and 8.3 in both SBR-S and SBR-A. The results of this investigation demonstrate that the anammox process may avoid N2O emission by maintaining an NH4 (+):NO2 (-) ratio of less than 1:2 and pH higher than 6.8.

  7. Mechanistic study of the visible-light-driven photocatalytic inactivation of bacteria by graphene oxide–zinc oxide composite

    International Nuclear Information System (INIS)

    Wu, Dan; An, Taicheng; Li, Guiying; Wang, Wei; Cai, Yuncheng; Yip, Ho Yin; Zhao, Huijun; Wong, Po Keung

    2015-01-01

    Graphical abstract: - Highlights: • The GO–ZnO composites exhibited efficient VLD bacterial inactivation performance. • Strong interfacial interaction existed between GO and ZnO. • GO served as a photosensitizer in the inactivation process. • Excellent antibacterial activity by GO–ZnO composite was shown under sunlight. • An inactivation mechanism based on the GO photosensitizer induction was proposed. - Abstract: The visible-light-driven (VLD) photocatalytic activity of graphene oxide–zinc oxide (GO–ZnO) composite prepared by a simple hydrothermal method was evaluated toward the inactivation of Escherichia coli K-12. The results showed that GO–ZnO composite had excellent VLD photocatalytic bacterial inactivation activity, comparing with those of ZnO and GO, which was attributed to the strong interaction between ZnO and GO in the composite. Accordingly, an interaction induced VLD photocatalytic inactivation mechanism of the strong interaction of GO with ZnO within the GO–ZnO composite was proposed. GO served as a photosensitizer and facilitated the charge separation and transfer, thus boosted the massive production of reactive oxygen species such as ·OH bulk , which was identified as the major reactive species from conduction band of ZnO, and resulted in a remarkable enhancement of bacterial inactivation efficiency. Moreover, GO–ZnO composite showed obviously superior photocatalytic bacterial inactivation within 10 min under natural solar light irradiation, indicating that GO–ZnO composite has great potential in wastewater treatment and environmental protection.

  8. Source of Nitrous Oxide Emissions during the Cow Manure Composting Process as Revealed by Isotopomer Analysis of and amoA Abundance in Betaproteobacterial Ammonia-Oxidizing Bacteria▿ †

    Science.gov (United States)

    Maeda, Koki; Toyoda, Sakae; Shimojima, Ryosuke; Osada, Takashi; Hanajima, Dai; Morioka, Riki; Yoshida, Naohiro

    2010-01-01

    A molecular analysis of betaproteobacterial ammonia oxidizers and a N2O isotopomer analysis were conducted to study the sources of N2O emissions during the cow manure composting process. Much NO2−-N and NO3−-N and the Nitrosomonas europaea-like amoA gene were detected at the surface, especially at the top of the composting pile, suggesting that these ammonia-oxidizing bacteria (AOB) significantly contribute to the nitrification which occurs at the surface layer of compost piles. However, the 15N site preference within the asymmetric N2O molecule (SP = δ15Nα − δ15Nβ, where 15Nα and 15Nβ represent the 15N/14N ratios at the center and end sites of the nitrogen atoms, respectively) indicated that the source of N2O emissions just after the compost was turned originated mainly from the denitrification process. Based on these results, the reduction of accumulated NO2−-N or NO3−-N after turning was identified as the main source of N2O emissions. The site preference and bulk δ15N results also indicate that the rate of N2O reduction was relatively low, and an increased value for the site preference indicates that the nitrification which occurred mainly in the surface layer of the pile partially contributed to N2O emissions between the turnings. PMID:20048060

  9. Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake.

    Science.gov (United States)

    Zhao, Da-yong; Luo, Juan; Zeng, Jin; Wang, Meng; Yan, Wen-ming; Huang, Rui; Wu, Qinglong L

    2014-01-01

    Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56 × 10(6) copies to 1.06 × 10(7) copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13 × 10(5) to 3.21 × 10(6) copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.

  10. Effect of Tidal Cycling Rate on the Distribution and Abundance of Nitrogen-Oxidizing Bacteria in a Bench-Scale Fill-and-Drain Bioreactor

    Directory of Open Access Journals (Sweden)

    Joseph M. Battistelli

    2018-04-01

    Full Text Available Most domestic wastewater can be effectively treated for secondary uses by engineered biological systems. These systems rely on microbial activity to reduce nitrogen (N content of the reclaimed water. Such systems often employ a tidal-flow process to minimize space requirements for the coupling of aerobic and anaerobic metabolic processes. In this study, laboratory-scale tidal-flow treatment systems were studied to determine how the frequency and duration of tidal cycling may impact reactor performance. Fluorescent in situ hybridization and epifluorescence microscopy were used to enumerate the key functional groups of bacteria responsible for nitrification and anaerobic ammonium oxidation (anammox, and N-removal efficiency was calculated via a mass-balance approach. When water was cycled (i.e., reactors were filled and drained at high frequencies (16–24 cycles day−1, nitrate accumulated in the columns—presumably due to inadequate periods of anoxia that limited denitrification. At lower frequencies, such as 4 cycles day−1, nearly complete N removal was achieved (80–90%. These fill-and-drain systems enriched heavily for nitrifiers, with relatively few anammox-capable organisms. The microbial community produced was robust, surviving well through short (up to 3 h anaerobic periods and frequent system-wide perturbation.

  11. Survival or revival: long-term preservation induces a reversible viable but non-culturable state in methane-oxidizing bacteria.

    Directory of Open Access Journals (Sweden)

    Sven Hoefman

    Full Text Available Knowledge on long-term preservation of micro-organisms is limited and research in the field is scarce despite its importance for microbial biodiversity and biotechnological innovation. Preservation of fastidious organisms such as methane-oxidizing bacteria (MOB has proven difficult. Most MOB do not survive lyophilization and only some can be cryopreserved successfully for short periods. A large-scale study was designed for a diverse set of MOB applying fifteen cryopreservation or lyophilization conditions. After three, six and twelve months of preservation, the viability (via live-dead flow cytometry and culturability (via most-probable number analysis and plating of the cells were assessed. All strains could be cryopreserved without a significant loss in culturability using 1% trehalose in 10-fold diluted TSB (TT as preservation medium and 5% DMSO as cryoprotectant. Several other cryopreservation and lyophilization conditions, all of which involved the use of TT medium, also allowed successful preservation but showed a considerable loss in culturability. We demonstrate here that most of these non-culturables survived preservation according to viability assessment indicating that preservation induces a viable but non-culturable (VBNC state in a significant fraction of cells. Since this state is reversible, these findings have major implications shifting the emphasis from survival to revival of cells in a preservation protocol. We showed that MOB cells could be significantly resuscitated from the VBNC state using the TT preservation medium.

  12. Inhibitory effect of self-generated extracellular dissolved organic carbon on carbon dioxide fixation in sulfur-oxidizing bacteria during a chemoautotrophic cultivation process and its elimination.

    Science.gov (United States)

    Wang, Ya-Nan; Tsang, Yiu Fai; Wang, Lei; Fu, Xiaohua; Hu, Jiajun; Li, Huan; Le, Yiquan

    2018-03-01

    The features of extracellular dissolved organic carbon (EDOC) generation in two typical aerobic sulfur-oxidizing bacteria (Thiobacillus thioparus DSM 505 and Halothiobacillus neapolitanus DSM 15147) and its impact on CO 2 fixation during chemoautotrophic cultivation process were investigated. The results showed that EDOC accumulated in both strains during CO 2 fixation process. Large molecular weight (MW) EDOC derived from cell lysis and decay was dominant during the entire process in DSM 505, whereas small MW EDOC accounted for a large proportion during initial and middle stages of DSM 15147 as its cytoskeleton synthesis rate did not keep up with CO 2 assimilation rate. The self-generated EDOC feedback repressed cbb gene transcription and thus decreased total bacterial cell number and CO 2 fixation yield in both strains, but DSM 505 was more sensitive to this inhibition effect. Moreover, the membrane bioreactor effectively decreased the EDOC/TOC ratio and improved carbon fixation yield of DSM 505. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Effect of γ-Aminobutyric Acid (GABA Producing Bacteria on Rumen Fermentation, Biogenic Amine Production and Anti-oxidation Using Corn Meal as Substrate

    Directory of Open Access Journals (Sweden)

    Bum Seung Ku

    2013-06-01

    Full Text Available The effects and significance of γ-amino butyric acid (GABA producing bacteria (GPB on in vitro rumen fermentation and reduction of biogenic amines (histamine, methylamine, ethylamine, and tyramine using corn meal as a substrate were determined. Ruminal samples collected from ruminally fistulated Holstein cows served as inoculum and corn was used as substrate at 2% dry matter (DM. Different inclusion rates of GPB and GABA were evaluated. After incubation, addition of GPB had no significant effect on in vitro fermentation pH and total gas production, but significantly increased the ammonia nitrogen (NH3-N concentration and reduced the total biogenic amines production (p<0.05. Furthermore, antioxidation activity was improved as indicated by the significantly higher concentration of superoxide dismutase (SOD and glutathione peroxidase (GSH-Px among treated samples when compared to the control (p<0.05. Additionally, 0.2% GPB was established as the optimum inclusion level. Taken together, these results suggest the potential of utilizing GPB as feed additives to improve growth performance in ruminants by reducing biogenic amines and increasing anti-oxidation.

  14. Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community

    Directory of Open Access Journals (Sweden)

    Parro Víctor

    2010-06-01

    Full Text Available Abstract Background Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy. Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers. In the Río Tinto (Spain, brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery and environmental applications (acid mine drainage, bioremediation. The aim of this study was to investigate the physiological differences between the free living (planktonic and the sessile (biofilm associated lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Results Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB, synthesis of cell wall structures (lnt, murA, murB, specific proteases (clpX/clpP, stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL, etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively in the acidic (pH 1.8 water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Conclusions Our results indicate that the

  15. Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community.

    Science.gov (United States)

    Moreno-Paz, Mercedes; Gómez, Manuel J; Arcas, Aida; Parro, Víctor

    2010-06-24

    Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). In the Río Tinto (Spain), brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum) and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery) and environmental applications (acid mine drainage, bioremediation). The aim of this study was to investigate the physiological differences between the free living (planktonic) and the sessile (biofilm associated) lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB), synthesis of cell wall structures (lnt, murA, murB), specific proteases (clpX/clpP), stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL), etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA) were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively) in the acidic (pH 1.8) water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Our results indicate that the acidophilic filaments are dynamic structures

  16. Nitrification is a primary driver of nitrous oxide production in laboratory microcosms from different land-use soils

    Directory of Open Access Journals (Sweden)

    Rui Liu

    2016-09-01

    Full Text Available Most studies on soil N2O emissions have focused either on the quantifying of agricultural N2O fluxes or on the effect of environmental factors on N2O emissions. However very limited information is available on how land-use will affect N2O production, and nitrifiers involved in N2O emissions in agricultural soil ecosystems. Therefore, this study aimed at evaluating the relative importance of nitrification and denitrification to N2O emissions from different land-use soils and identifying the potential underlying microbial mechanisms. A 15N-tracing experiment was conducted under controlled laboratory conditions on four agricultural soils collected from different land-use. We measured N2O fluxes, nitrate (NO3− and ammonium (NH4+ concentration and15N2O, 15NO3− and 15NH4+ enrichment during the incubation. Quantitative PCR was used to quantify ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB. Our results showed that nitrification was the main contributor to N2O production in soils from sugarcane, dairy pasture and cereal cropping systems, while denitrification played a major role in N2O production in the vegetable soil under the experimental conditions. Nitrification contributed to 96.7% of the N2O emissions in sugarcane soil followed by 71.3% in the cereal cropping soil and 70.9% in the dairy pasture soil, while only around 20.0% of N2O was produced from nitrification in vegetable soil. The proportion of nitrified nitrogen as N2O (PN2O value varied across different soils, with the highest PN2O value (0.26‰ found in the cereal cropping soil, which was around 10 times higher than that in other three systems. AOA were the abundant ammonia oxidizers, and were significantly correlated to N2O emitted from nitrification in the sugarcane soil, while AOB were significantly correlated with N2O emitted from nitrification in the cereal cropping soil. Our findings suggested that soil type and land-use might have strongly affected the

  17. Nitrification Is a Primary Driver of Nitrous Oxide Production in Laboratory Microcosms from Different Land-Use Soils.

    Science.gov (United States)

    Liu, Rui; Hu, Hangwei; Suter, Helen; Hayden, Helen L; He, Jizheng; Mele, Pauline; Chen, Deli

    2016-01-01

    Most studies on soil N2O emissions have focused either on the quantifying of agricultural N2O fluxes or on the effect of environmental factors on N2O emissions. However, very limited information is available on how land-use will affect N2O production, and nitrifiers involved in N2O emissions in agricultural soil ecosystems. Therefore, this study aimed at evaluating the relative importance of nitrification and denitrification to N2O emissions from different land-use soils and identifying the potential underlying microbial mechanisms. A (15)N-tracing experiment was conducted under controlled laboratory conditions on four agricultural soils collected from different land-use. We measured N2O fluxes, nitrate ([Formula: see text]), and ammonium ([Formula: see text]) concentration and (15)N2O, (15)[Formula: see text], and (15)[Formula: see text] enrichment during the incubation. Quantitative PCR was used to quantify ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Our results showed that nitrification was the main contributor to N2O production in soils from sugarcane, dairy pasture and cereal cropping systems, while denitrification played a major role in N2O production in the vegetable soil under the experimental conditions. Nitrification contributed to 96.7% of the N2O emissions in sugarcane soil followed by 71.3% in the cereal cropping soil and 70.9% in the dairy pasture soil, while only around 20.0% of N2O was produced from nitrification in vegetable soil. The proportion of nitrified nitrogen as N2O (PN2O-value) varied across different soils, with the highest PN2O-value (0.26‰) found in the cereal cropping soil, which was around 10 times higher than that in other three systems. AOA were the abundant ammonia oxidizers, and were significantly correlated to N2O emitted from nitrification in the sugarcane soil, while AOB were significantly correlated with N2O emitted from nitrification in the cereal cropping soil. Our findings suggested that soil

  18. Nitrogen-fixing methane-utilizing bacteria

    NARCIS (Netherlands)

    Bont, de J.A.M.

    1976-01-01

    Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in

  19. INFLUENCE OF ELEMENTAL SULFUR AND/OR INOCULATION WITH SULFUR OXIDIZING BACTERIA ON GROWTH, AND NUTRIENT CONTENT OF SORGHUM PLANTS GROWN ON DIFFERENT SOILS

    Directory of Open Access Journals (Sweden)

    Hala Kandil

    2011-12-01

    Full Text Available A pot experiment was conducted to study the effect of elemental sulfur(E.S rates (300 and 600 ppm and/or sulfur oxidizing bacteria (S.O.B. ATCC 8158 on growth and nutrients content of sorghum plants grown on different soils (sandy soils(I & II and clay loam soil.The obtained results could be summarized in the followings:Sorghum plants:Significant increases over the control were observed in fresh and dry weights of sorghum plant as well as its content of SO4=, N, P, K, Fe, Mn, Zn and Cu by using all the sulfur and/or the oxidizing bacteria treatments. Addition of E.S (300 & 600 ppm in combination with S.O.B. ATCC 8158 significantly increased both fresh and dry weights as well as SO4=, N, P, K, Fe, Mn, Zn and Cu contents of sorghum plants grown on the used soils as compared with either of them alone.E.S rates (300 & 600 ppm significantly increased the fresh and dry weights as well as all the studied nutrients content (SO4=, N, P, K, Fe, Mn, Zn and Cu of sorghum plants grown on the different soils as compared with S.O.B. ATCC 8158 treatment alone. The highest rate of E.S (600 ppm significantly increased all the previous parameters under study as compared with the lower rate (300 ppm. The highest values of fresh and dry weights as well as nutrients content (SO4=, N, P, K, Fe, Mn, Zn and Cu of sorghum plants grown on the used soils were obtained by 600 ppm E.S + S.O.B. ATCC 8158 treatment followed by 600 ppm E.S; 300 ppm E.S + S.O.B. ATCC 8158; 300 ppm E.S; S.O.B. ATCC 8158 and control treatments in decreasing order.The used soils:E.S rates (300 & 600 ppm and/or S.O.B. ATCC 8158 decreased pH values of the used soils after 3, 6 and 9 weeks from sowing as compared with their corresponding control treatments. The values of pH of sand soil (I and clay loam soil slightly decreased by time i.e they decreased from 3 weeks to 9 weeks from plantation. E.S rates (300 & 600 ppm with or without inoculation the used soils with S.O.B. ATCC 8158 significantly

  20. A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

    Directory of Open Access Journals (Sweden)

    Suzanne Caroline Marianne Haaijer

    2013-03-01

    Full Text Available Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite-oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB, a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifiying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (AOB and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmoles of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on FISH and metagenomic data converting a maximum of 3 mmoles of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity. Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted PCR analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species.

  1. Cable Bacteria in Freshwater Sediments

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus

    2015-01-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...

  2. Nitrifier-induced denitrification is an important source of soil nitrous oxide and can be inhibited by a nitrification inhibitor 3,4-dimethylpyrazole phosphate.

    Science.gov (United States)

    Shi, Xiuzhen; Hu, Hang-Wei; Zhu-Barker, Xia; Hayden, Helen; Wang, Juntao; Suter, Helen; Chen, Deli; He, Ji-Zheng

    2017-12-01

    Soil ecosystem represents the largest contributor to global nitrous oxide (N 2 O) production, which is regulated by a wide variety of microbial communities in multiple biological pathways. A mechanistic understanding of these N 2 O production biological pathways in complex soil environment is essential for improving model performance and developing innovative mitigation strategies. Here, combined approaches of the 15 N- 18 O labelling technique, transcriptome analysis, and Illumina MiSeq sequencing were used to identify the relative contributions of four N 2 O pathways including nitrification, nitrifier-induced denitrification (nitrifier denitrification and nitrification-coupled denitrification) and heterotrophic denitrification in six soils (alkaline vs. acid soils). In alkaline soils, nitrification and nitrifier-induced denitrification were the dominant pathways of N 2 O production, and application of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) significantly reduced the N 2 O production from these pathways; this is probably due to the observed reduction in the expression of the amoA gene in ammonia-oxidizing bacteria (AOB) in the DMPP-amended treatments. In acid soils, however, heterotrophic denitrification was the main source for N 2 O production, and was not impacted by the application of DMPP. Our results provide robust evidence that the nitrification inhibitor DMPP can inhibit the N 2 O production from nitrifier-induced denitrification, a potential significant source of N 2 O production in agricultural soils. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Big bacteria

    DEFF Research Database (Denmark)

    Schulz, HN; Jørgensen, BB

    2001-01-01

    A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria......, Thiomargarita namibiensis, with a diameter of 750 mum. All bacteria, including those that swim around in the environment, obtain their food molecules by molecular diffusion. Only the fastest and largest swimmers known, Thiovulum majus, are able to significantly increase their food supply by motility...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria...

  4. Big bacteria

    DEFF Research Database (Denmark)

    Schulz, HN; Jørgensen, BB

    2001-01-01

    A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria......, the 80 x 600 mum large Epulopiscium sp. from the gut of tropical fish, are presumably living in a very nutrient-rich medium. Many large bacteria contain numerous inclusions in the cells that reduce the volume of active cytoplasm. The most striking examples of competitive advantage from large cell size...

  5. Magnetic Bacteria.

    Science.gov (United States)

    Nelson, Jane Bray; Nelson, Jim

    1992-01-01

    Describes the history of Richard Blakemore's discovery of magnetotaxic organisms. Discusses possible reasons why the magnetic response in bacteria developed. Proposes research experiments integrating biology and physics in which students investigate problems using cultures of magnetotaxic organisms. (MDH)

  6. Characterization of 16S rRNA genes from oil field microbial communities indicates the presence of a variety of sulfate-reducing, fermentative, and sulfide-oxidizing bacteria.

    Science.gov (United States)

    Voordouw, G; Armstrong, S M; Reimer, M F; Fouts, B; Telang, A J; Shen, Y; Gevertz, D

    1996-05-01

    Oil field bacteria were characterized by cloning and sequencing of PCR-amplified 16S rRNA genes. A variety of gram-negative, sulfate-reducing bacteria was detected (16 members of the family Desulfovibrionaceae and 8 members of the family Desulfobacteriaceae). In contrast, a much more limited number of anaerobic, fermentative, or acetogenic bacteria was found (one Clostridium sp., one Eubacterium sp., and one Synergistes sp.). Potential sulfide oxidizers and/or microaerophiles (Thiomicrospira, Arcobacter, Campylobacter, and Oceanospirillum spp.) were also detected. The first two were prominently amplified from uncultured production water DNA and represented 28 and 47% of all clones, respectively. Growth on media containing sulfide as the electron donor and nitrate as the electron acceptor and designed for the isolation of Thiomicrospira spp. gave only significant enrichment of the Campylobacter sp., which was shown to be present in different western Canadian oil fields. This newly discovered sulfide oxidizer may provide a vital link in the oil field sulfur cycle by reoxidizing sulfide formed by microbial sulfate or sulfur reduction.

  7. Evidence for involvement of gut-associated denitrifying bacteria in emission of nitrous oxide (N(2)O) by earthworms obtained from garden and forest soils.

    Science.gov (United States)

    Matthies, C; Griesshammer, A; Schmittroth, M; Drake, H L

    1999-08-01

    Earthworms (Aporrectodea caliginosa, Lumbricus rubellus, and Octolasion lacteum) obtained from nitrous oxide (N(2)O)-emitting garden soils emitted 0.14 to 0.87 nmol of N(2)O h(-1) g (fresh weight)(-1) under in vivo conditions. L. rubellus obtained from N(2)O-emitting forest soil also emitted N(2)O, which confirmed previous observations (G. R. Karsten and H. L. Drake, Appl. Environ. Microbiol. 63:1878-1882, 1997). In contrast, commercially obtained Lumbricus terrestris did not emit N(2)O; however, such worms emitted N(2)O when they were fed (i.e., preincubated in) garden soils. A. caliginosa, L. rubellus, and O. lacteum substantially increased the rates of N(2)O emission of garden soil columns and microcosms. Extrapolation of the data to in situ conditions indicated that N(2)O emission by earthworms accounted for approximately 33% of the N(2)O emitted by garden soils. In vivo emission of N(2)O by earthworms obtained from both garden and forest soils was greatly stimulated when worms were moistened with sterile solutions of nitrate or nitrite; in contrast, ammonium did not stimulate in vivo emission of N(2)O. In the presence of nitrate, acetylene increased the N(2)O emission rates of earthworms; in contrast, in the presence of nitrite, acetylene had little or no effect on emission of N(2)O. In vivo emission of N(2)O decreased by 80% when earthworms were preincubated in soil supplemented with streptomycin and tetracycline. On a fresh weight basis, the rates of N(2)O emission of dissected earthworm gut sections were substantially higher than the rates of N(2)O emission of dissected worms lacking gut sections, indicating that N(2)O production occurred in the gut rather than on the worm surface. In contrast to living earthworms and gut sections that produced N(2)O under oxic conditions (i.e., in the presence of air), fresh casts (feces) from N(2)O-emitting earthworms produced N(2)O only under anoxic conditions. Collectively, these results indicate that gut

  8. Sulfur metabolism in phototrophic sulfur bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Dahl, Christiane

    2008-01-01

    Phototrophic sulfur bacteria are characterized by oxidizing various inorganic sulfur compounds for use as electron donors in carbon dioxide fixation during anoxygenic photosynthetic growth. These bacteria are divided into the purple sulfur bacteria (PSB) and the green sulfur bacteria (GSB......). They utilize various combinations of sulfide, elemental sulfur, and thiosulfate and sometimes also ferrous iron and hydrogen as electron donors. This review focuses on the dissimilatory and assimilatory metabolism of inorganic sulfur compounds in these bacteria and also briefly discusses these metabolisms...... in other types of anoxygenic phototrophic bacteria. The biochemistry and genetics of sulfur compound oxidation in PSB and GSB are described in detail. A variety of enzymes catalyzing sulfur oxidation reactions have been isolated from GSB and PSB (especially Allochromatium vinosum, a representative...

  9. Anaerobic bacteria that dechlorinate perchloroethene.

    Science.gov (United States)

    Fathepure, B Z; Nengu, J P; Boyd, S A

    1987-01-01

    In this study, we identified specific cultures of anaerobic bacteria that dechlorinate perchlorethene (PCE). The bacteria that significantly dechlorinated PCE were strain DCB-1, an obligate anaerobe previously shown to dechlorinate chlorobenzoate, and two strains of Methanosarcina. The rate of PCE dechlorination by DCB-1 compared favorably with reported rates of trichloroethene bio-oxidation by methanotrophs. Even higher PCE dechlorination rates were achieved when DCB-1 was grown in a methanogenic consortium. PMID:3426224

  10. Motility of electric cable bacteria

    DEFF Research Database (Denmark)

    Bjerg, Jesper Tataru; Damgaard, Lars Riis; Holm, Simon Agner

    2016-01-01

    Cable bacteria are filamentous bacteria that electrically couple sulfide oxidation and oxygen reduction at centimeter distances, and observations in sediment environments have suggested that they are motile. By time-lapse microscopy, we found that cable bacteria used gliding motility on surfaces...... with a highly variable speed of 0.50.3 ms1 (meanstandard deviation) and time between reversals of 155108 s. They frequently moved forward in loops, and formation of twisted loops revealed helical rotation of the filaments. Cable bacteria responded to chemical gradients in their environment, and around the oxic......-anoxic interface, they curled and piled up, with straight parts connecting back to the source of sulfide. Thus, it appears that motility serves the cable bacteria in establishing and keeping optimal connections between their distant electron donor and acceptors in a dynamic sediment environment....

  11. Cytochrome cd1-containing nitrite reductase encoding gene nirS as a new functional biomarker for detection of anaerobic ammonium oxidizing (Anammox) bacteria.

    Science.gov (United States)

    Li, Meng; Ford, Tim; Li, Xiaoyan; Gu, Ji-Dong

    2011-04-15

    A newly designed primer set (AnnirS), together with a previously published primer set (ScnirS), was used to detect anammox bacterial nirS genes from sediments collected from three marine environments. Phylogenetic analysis demonstrated that all retrieved sequences were clearly different from typical denitrifiers' nirS, but do group together with the known anammox bacterial nirS. Sequences targeted by ScnirS are closely related to Scalindua nirS genes recovered from the Peruvian oxygen minimum zone (OMZ), whereas sequences targeted by AnnirS are more closely affiliated with the nirS of Candidatus 'Kuenenia stuttgartiensis' and even form a new phylogenetic nirS clade, which might be related to other genera of the anammox bacteria. Analysis demonstrated that retrieved sequences had higher sequence identities (>60%) with known anammox bacterial nirS genes than with denitrifiers' nirS, on both nucleotide and amino acid levels. Compared to the 16S rRNA and hydrazine oxidoreductase (hzo) genes, the anammox bacterial nirS not only showed consistent phylogenetic relationships but also demonstrated more reliable quantification of anammox bacteria because of the single copy of the nirS gene in the anammox bacterial genome and the specificity of PCR primers for different genera of anammox bacteria, thus providing a suitable functional biomarker for investigation of anammox bacteria.

  12. Soil carbon content and relative abundance of high affinity H2-oxidizing bacteria predict atmospheric H2 soil uptake activity better than soil microbial community composition

    NARCIS (Netherlands)

    Khdhiri, Mondher; Hesse, Laura; Popa, Maria Elena; Quiza, Liliana; Lalonde, Isabelle; Meredith, Laura K.; Röckmann, Thomas; Constant, Philippe

    2015-01-01

    Soil-atmosphere exchange of H2 is controlled by gas diffusion and the microbial production and oxidation activities in soil. Among these parameters, the H2 oxidation activity catalyzed by soil microorganisms harboring high affinity hydrogenase is the most difficult variable to parameterize because

  13. Biomarker evidence for widespread anaerobic methane oxidation in Mediterranean sediments by a consortium of methanogenic archaea and bacteria : The Medinaut Shipboard Scientific Party

    NARCIS (Netherlands)

    Pancost, Richard D.; Sinninghe Damsté, Jaap S.; de Lint, Saskia; van der Maarel, Marc J.E.C.; Gottschal, JC

    Although abundant geochemical data indicate that anaerobic methane oxidation occurs in marine sediments, the linkage to specific microorganisms remains unclear, In order to examine processes of methane consumption and oxidation, sediment samples from mud volcanoes at two distinct sites on the

  14. A preliminary study of anaerobic thiosulfate-oxidising bacteria as denitrifiers in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Chandramohan, D.; Nair, S.

    Bacteria which oxidize thiosulfate and reduce nitrate (TONRB) and bacteria which oxidize thiosulfate and denitrify (TODB) sampled at 5-, 100-, 200-and 300-m depths were enumerated in agar shake cultures by colony counting and by applying MPN...

  15. Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions, and novel technologies

    Science.gov (United States)

    Schreiber, Frank; Wunderlin, Pascal; Udert, Kai M.; Wells, George F.

    2012-01-01

    Nitrous oxide (N2O) is an environmentally important atmospheric trace gas because it is an effective greenhouse gas and it leads to ozone depletion through photo-chemical nitric oxide (NO) production in the stratosphere. Mitigating its steady increase in atmospheric concentration requires an understanding of the mechanisms that lead to its formation in natural and engineered microbial communities. N2O is formed biologically from the oxidation of hydroxylamine (NH2OH) or the reduction of nitrite (NO−2) to NO and further to N2O. Our review of the biological pathways for N2O production shows that apparently all organisms and pathways known to be involved in the catabolic branch of microbial N-cycle have the potential to catalyze the reduction of NO−2 to NO and the further reduction of NO to N2O, while N2O formation from NH2OH is only performed by ammonia oxidizing bacteria (AOB). In addition to biological pathways, we review important chemical reactions that can lead to NO and N2O formation due to the reactivity of NO−2, NH2OH, and nitroxyl (HNO). Moreover, biological N2O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N2O build-up are key to understand mechanisms of N2O release. Here, we discuss novel technologies that allow experiments on NO and N2O formation at high temporal resolution, namely NO and N2O microelectrodes and the dynamic analysis of the isotopic signature of N2O with quantum cascade laser absorption spectroscopy (QCLAS). In addition, we introduce other techniques that use the isotopic composition of N2O to distinguish production pathways and findings that were made with emerging molecular techniques in complex environments. Finally, we discuss how a combination of the presented tools might help to address important open questions on pathways and controls of nitrogen flow through complex microbial communities that eventually lead to N2O build

  16. Comparative Genomics of Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Ussery, David; Davenport, C; Tümmler, B

    2010-01-01

    Eleven completely sequenced Chlorobi genomes were compared in oligonucleotide usage, gene contents, and synteny. The green sulfur bacteria (GSB) are equipped with a core genome that sustains their anoxygenic phototrophic lifestyle by photosynthesis, sulfur oxidation, and CO(2) fixation. Whole...... weight of 10(6), and are probably instrumental for the bacteria to generate their own intimate (micro)environment....

  17. Rumen bacteria

    International Nuclear Information System (INIS)

    McSweeney, C.S.; Denman, S.E.; Mackie, R.I.

    2005-01-01

    The rumen is the most extensively studied gut community and is characterized by its high population density, wide diversity and complexity of interactions. This complex, mixed microbial culture is comprised of prokaryote organisms including methane-producing archaebacteria, eukaryote organisms, such as ciliate and flagellate protozoa, anaerobic phycomycete fungi and bacteriophage. Bacteria are predominant (up to 10 11 viable cells per g comprising 200 species) but a variety of ciliate protozoa occur widely (10 4 -10 6 /g distributed over 25 genera). The anaerobic fungi are also widely distributed (zoospore population densities of 10 2 -10 4 /g distributed over 5 genera). The occurrence of bacteriophage is well documented (10 7 -10 9 particles/g). This section focuses primarily on the widely used methods for the cultivation and the enumeration of rumen microbes, especially bacteria, which grow under anaerobic conditions. Methods that can be used to measure hydrolytic enzymes (cellulases, xylanases, amylases and proteinases) are also described, along with cell harvesting and fractionation procedures. Brief reference is also made to fungi and protozoa, but detailed explanations for culturing and enumerating these microbes is presented in Chapters 2.4 and 2.5

  18. High potential oxidation-reduction titration of absorbance changes induced by pulsed laser and continuous light in chromatophores of photosynthesizing bacteria Rhodospirillum rubrum and Ectothiorhodospira shaposhnikovii

    International Nuclear Information System (INIS)

    Remennikov, S.M.; Chamorovsky, S.K.; Kononenko, A.A.; Venediktov, P.S.; Rubin, A.B.

    1975-01-01

    The photoreactions, activated both by pulsed laser and continuous light were studied in the membranes of isolated bacterial chromatophores poised at different oxidation-reduction potentials over a range of +200 mV to +500 mV. In Rhodospirillum rubrum a midpoint potential of oxidation-reduction curves for the laser-induced positive absorbance changes centred around 430 nm and carotenoid red shifts coincides with that for continuous light-induced absorbance changes, bleaching at 865 nm and blue shift at 800 nm, of the photosynthetic reaction centre bacteriochlorophyll. In Ectothiorhodospira shaposhnikovii the photosynthetic reaction centre bacteriochlorophyll, its photooxidation can be seen as light-induced absorbance changes, bleaching at 890 nm, blue shift at 800 nm and broad band appearance near 440 nm, has a midpoint oxidation-reduction potential of +390 mV at pH 7.4. The analysis of the oxidation-reduction titration curves for the high-potential c-type cytochrome absorbance changes induced both by pulsed laser and continuous light allowed to show that at least two haems of this cytochrome with a midpoint potential of +290 mV (pH 7.4), associated with each reaction centre bacteriochlorophyll, can donate electrons to the oxidized pigment directly

  19. Population Structure and Abundance of Arsenite-Oxidizing Bacteria along an Arsenic Pollution Gradient in Waters of the Upper Isle River Basin, France▿ †

    Science.gov (United States)

    Quéméneur, Marianne; Cébron, Aurélie; Billard, Patrick; Battaglia-Brunet, Fabienne; Garrido, Francis; Leyval, Corinne; Joulian, Catherine

    2010-01-01

    Denaturing gradient gel electrophoresis (DGGE) and quantitative real-time PCR (qPCR) were successfully developed to monitor functional aoxB genes as markers of aerobic arsenite oxidizers. DGGE profiles showed a shift in the structure of the aoxB-carrying bacterial population, composed of members of the Alpha-, Beta- and Gammaproteobacteria, depending on arsenic (As) and Eh levels in Upper Isle River Basin waters. The highest aoxB gene densities were found in the most As-polluted oxic surface waters but without any significant correlation with environmental factors. Arsenite oxidizers seem to play a key role in As mobility in As-impacted waters. PMID:20453153

  20. Changing of Bacteria Catalase Activity Under the Influence of Electro-Magnetic Radiation on a Frequency of Nitric Oxide Absorption and Radiation Molecular Spectrum

    Directory of Open Access Journals (Sweden)

    G.M. Shub

    2009-09-01

    Full Text Available The dynamics of catalase activity degree changing in Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa is described under the influence of electro-magnetic radiation on a frequency of nitric oxide absorption and radiation molecular spectrum. The panoramic spectrometric measuring complex, developed in Central Scientific Research Institute of measuring equipment Public corporation, Saratov, was used while carrying out the research. Electromagnetic vibrations of extremely high frequencies were stimulated in this complex imitating the structure of nitric oxide absorption and radiation molecular spectrum. The growth of activity of the mentioned enzyme of the strains under research was detected. The most significant changes were observed under 60-minutes exposure.

  1. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    Science.gov (United States)

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Sulphur oxidising bacteria in mangrove ecosystem: A review ...

    African Journals Online (AJOL)

    Sulphur-oxidizing bacteria such as photoautotrophs, chemolithotrophs and heterotrophs play an important role in the mangrove environment for the oxidation of the toxic sulphide produced by sulphur reducing bacteria and act as a key driving force behind all sulphur transformations in the mangrove ecosystem which is ...

  3. Modeling Nitrous Oxide Production during Biological Nitrogen Removal via Nitrification and Denitrification: Extensions to the General ASM Models

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Ruscalleda, Maël; Pellicer i Nàcher, Carles

    2011-01-01

    on N2O production from four different mixed culture nitrification and denitrification reactor study reports. Modeling results confirm that hydroxylamine oxidation by ammonium oxidizers (AOB) occurs 10 times slower when NO2– participates as final electron acceptor compared to the oxic pathway. Among......Nitrous oxide (N2O) can be formed during biological nitrogen (N) removal processes. In this work, a mathematical model is developed that describes N2O production and consumption during activated sludge nitrification and denitrification. The well-known ASM process models are extended to capture N2O...

  4. Antioxidant Properties of Probiotic Bacteria.

    Science.gov (United States)

    Wang, Yang; Wu, Yanping; Wang, Yuanyuan; Xu, Han; Mei, Xiaoqiang; Yu, Dongyou; Wang, Yibing; Li, Weifen

    2017-05-19

    Oxidative stress defines a condition in which the prooxidant-antioxidant balance in the cell is disturbed, resulting in DNA hydroxylation, protein denaturation, lipid peroxidation, and apoptosis, ultimately compromising cells' viability. Probiotics have been known for many beneficial health effects, and the consumption of probiotics alone or in food shows that strain-specific probiotics can present antioxidant activity and reduce damages caused by oxidation. However, the oxidation-resistant ability of probiotics, especially the underling mechanisms, is not properly understood. In this view, there is interest to figure out the antioxidant property of probiotics and summarize the mode of action of probiotic bacteria in antioxidation. Therefore, in the present paper, the antioxidant mechanisms of probiotics have been reviewed in terms of their ability to improve the antioxidant system and their ability to decrease radical generation. Since in recent years, oxidative stress has been associated with an altered gut microbiota, the effects of probiotics on intestinal flora composition are also elaborated.

  5. Encouraging “K” strategy nitrifiers over “r” strategists in bioaugmentation reactor

    Directory of Open Access Journals (Sweden)

    Zięba Bartosz

    2017-01-01

    Full Text Available Bacteria responsible for ammonia oxidization (AOB can be differed into two groups which have different bio kinetic parameters. Those groups are slow growing bacteria with lower half saturation coefficient for NH4 (k -strategist and fast growing bacteria with higher half saturation coefficient for NH4 (r- strategist. By controlling operational conditions of process it is possible to create dominance of one of those colonies to enhance the nitrification rate. Therefore model of sequencing bath reactor was developed to study the correlation of bioaugmentation of the side stream breeder reactor and predominant AOB culture. The course of the study was to find the minimal bioaugmentation influent of AOB rich recycled sludge to create dominance of k-strategist in the side stream reactor with maintaining maximal possible increase of overall AOB load. In addition operating conditions like sludge retention time, NH4 concentration and loading regimes was investigated to determine the optimum for the process.

  6. Bio-transformation and stabilization of arsenic (As) in contaminated soil using arsenic oxidizing bacteria and FeCl3 amendment.

    Science.gov (United States)

    Karn, Santosh Kumar; Pan, Xiangliang; Jenkinson, Ian R

    2017-05-01

    A combination of biological and chemical methods was applied in the present study to evaluate the removal of arsenic (As) from contaminated soil. The treatment involved As-oxidizing microbes aimed of transforming the more toxic As (III) to less toxic As (V) in the soil. FeCl 3 was added at three different concentrations (1, 2, and 3%) to stabilize the As (V). Leaching of the treated soil was investigated by making a soil column and passing tap water through it to determine solubility. Experimental results indicated that the bacterial activity had a pronounced positive effect on the transformation of As, and decreased the soluble exchangeable fraction from 50 to 0.7 mg/kg as compared to control and from 50 to 44 mg/kg after 7 days of treatment. FeCl 3 also played an indispensable role in the adsorption/stabilization of As in the soil; 1 and 2% FeCl 3 strongly influenced the adsorption of As (V). The soil leachate contained negligible amount of As and trace metals, which indicates that combining an efficient microbe with a chemical treatment is very effective route for the removal and stabilization of As from contaminated soil in the environment.

  7. Different effectiveness of two pastas supplemented with either lipophilic or hydrophilic/phenolic antioxidants in affecting serum as evaluated by the novel Antioxidant/Oxidant Balance approach.

    Science.gov (United States)

    Laus, Maura N; Soccio, Mario; Alfarano, Michela; Pasqualone, Antonella; Lenucci, Marcello S; Di Miceli, Giuseppe; Pastore, Donato

    2017-04-15

    Effectiveness in improving serum antioxidant status of two functional pastas was evaluated by the novel Antioxidant/Oxidant Balance (AOB) parameter, calculated as Antioxidant Capacity (AC)/Peroxide Level ratio, assessed here for the first time. In particular, Bran Oleoresin (BO) and Bran Water (BW) pastas, enriched respectively with either lipophilic (tocochromanols, carotenoids) or hydrophilic/phenolic antioxidants extracted from durum wheat bran, were studied. Notably, BO pasta was able to improve significantly (+65%) serum AOB during four hours after intake similarly to Lisosan G, a wheat antioxidant-rich dietary supplement. Contrarily, BW pasta had oxidative effect on serum so as conventional pasta and glucose, thus suggesting greater effectiveness of lipophilic than hydrophilic/phenolic antioxidants under our experimental conditions. Interestingly, no clear differences between the two pastas were observed, when AC measurements of either serum after pasta intake or pasta extracts by in vitro assays were considered, thus strengthening effectiveness and reliability of AOB approach. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Prevalence of β-lactamase genes in domestic washing machines and dishwashers and the impact of laundering processes on antibiotic-resistant bacteria.

    Science.gov (United States)

    Rehberg, L; Frontzek, A; Melhus, Å; Bockmühl, D P

    2017-12-01

    To investigate the prevalence of β-lactamase genes in domestic washing machines and dishwashers, and the decontamination efficacy of laundering. For the first investigation, swab samples from washing machines (n = 29) and dishwashers (n = 24) were analysed by real-time quantitative PCR to detect genes encoding β-lactamases. To test the impact of laundering on resistant bacteria, cotton test swatches were artificially contaminated with susceptible and resistant strains of Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus within a second investigation. They were washed in a domestic washing machine with or without activated oxygen bleach (AOB)-containing detergent at 20-50°C. β-Lactamase genes (most commonly of the AmpC- and OXA-type) were detected in 79% of the washing machines and in 96% of the dishwashers and Pseudomonadaceae dominated the microbiota. The level of bacterial reduction after laundering was ≥80% for all Ps. aeruginosa and Kl. pneumoniae strains, while it was only 37-61% for the methicillin-resistant Staph. aureus outbreak strain. In general, the reduction was tendentially higher for susceptible bacteria than for the resistant outbreak strains, especially for Staph. aureus. β-Lactamase genes seem to be frequently present in domestic appliances and may pose a potential risk for cross-contamination and horizontal transfer of genes encoding resistance against clinically important β-lactams. In general, higher temperatures and the use of AOB can improve the reduction of antibiotic-resistant bacteria, including Staph. aureus which appears to be less susceptible to the decontamination effect of laundering. Data on the presence of antibiotic-resistant bacteria in the domestic environment are limited. This study suggests that β-lactamase genes in washing machines and dishwashers are frequent, and that antibiotic-resistant strains are generally more resistant to the used washing conditions. © 2017 The Society for

  9. Long-distance electron transport by cable bacteria in mangrove sediments

    NARCIS (Netherlands)

    Burdorf, L.D.; Hidalgo-Martinez, S.; Cook, P.L.M.C.; Meysman, F.

    2016-01-01

    Cable bacteria are long, filamentoussulphur-oxidizing bacteria that induce long-distanceelectron transport in aquatic sediments. They turnthe seafloor into an electro-active environment, characterizedby currents and electrical fields, and whenpresent, they exert a strong impact on the

  10. Bleach vs. Bacteria

    Science.gov (United States)

    ... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

  11. Bacteria and lignin degradation

    Institute of Scientific and Technical Information of China (English)

    Jing LI; Hongli YUAN; Jinshui YANG

    2009-01-01

    Lignin is both the most abundant aromatic (phenolic) polymer and the second most abundant raw material.It is degraded and modified by bacteria in the natural world,and bacteria seem to play a leading role in decomposing lignin in aquatic ecosystems.Lignin-degrading bacteria approach the polymer by mechanisms such as tunneling,erosion,and cavitation.With the advantages of immense environmental adaptability and biochemical versatility,bacteria deserve to be studied for their ligninolytic potential.

  12. degrading bacteria isolated from South African waste water

    African Journals Online (AJOL)

    Al

    2011-09-21

    Sep 21, 2011 ... biodiversity in which microorganisms co-exist as a dyna- mic community with ... elemental chlorine or chlorine oxide making this industry a major source of ... This two stage procedure ensured the selection of bacteria only ...

  13. Antioxidant Properties of Probiotic Bacteria

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2017-05-01

    Full Text Available Oxidative stress defines a condition in which the prooxidant–antioxidant balance in the cell is disturbed, resulting in DNA hydroxylation, protein denaturation, lipid peroxidation, and apoptosis, ultimately compromising cells’ viability. Probiotics have been known for many beneficial health effects, and the consumption of probiotics alone or in food shows that strain-specific probiotics can present antioxidant activity and reduce damages caused by oxidation. However, the oxidation-resistant ability of probiotics, especially the underling mechanisms, is not properly understood. In this view, there is interest to figure out the antioxidant property of probiotics and summarize the mode of action of probiotic bacteria in antioxidation. Therefore, in the present paper, the antioxidant mechanisms of probiotics have been reviewed in terms of their ability to improve the antioxidant system and their ability to decrease radical generation. Since in recent years, oxidative stress has been associated with an altered gut microbiota, the effects of probiotics on intestinal flora composition are also elaborated.

  14. Genomics of Probiotic Bacteria

    Science.gov (United States)

    O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd R.

    Probiotic bacteria from the Lactobacillus and Bifidobacterium species belong to the Firmicutes and the Actinobacteria phylum, respectively. Lactobacilli are members of the lactic acid bacteria (LAB) group, a broadly defined family of microorganisms that ferment various hexoses into primarily lactic acid. Lactobacilli are typically low G + C gram-positive species which are phylogenetically diverse, with over 100 species documented to date. Bifidobacteria are heterofermentative, high G + C content bacteria with about 30 species of bifidobacteria described to date.

  15. NC10 bacteria in marine oxygen minimum zones

    DEFF Research Database (Denmark)

    Padilla, Cory C; Bristow, Laura A; Sarode, Neha

    2016-01-01

    Bacteria of the NC10 phylum link anaerobic methane oxidation to nitrite denitrification through a unique O2-producing intra-aerobic methanotrophy pathway. A niche for NC10 in the pelagic ocean has not been confirmed. We show that NC10 bacteria are present and transcriptionally active in oceanic....... rRNA and mRNA transcripts assignable to NC10 peaked within the OMZ and included genes of the putative nitrite-dependent intra-aerobic pathway, with high representation of transcripts containing the unique motif structure of the nitric oxide (NO) reductase of NC10 bacteria, hypothesized...

  16. How honey kills bacteria

    NARCIS (Netherlands)

    Kwakman, Paulus H. S.; te Velde, Anje A.; de Boer, Leonie; Speijer, Dave; Vandenbroucke-Grauls, Christina M. J. E.; Zaat, Sebastian A. J.

    2010-01-01

    With the rise in prevalence of antibiotic-resistant bacteria, honey is increasingly valued for its antibacterial activity. To characterize all bactericidal factors in a medical-grade honey, we used a novel approach of successive neutralization of individual honey bactericidal factors. All bacteria

  17. FY1995 acquisition of useful and high ability genes for acidophilic bacteria; 1995 nendo kosansei saikin ni takai noryoku wo fuyosuru idenshi no kakutoku

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The purpose of this project is to obtain and to study useful and high ability genes which can use for gene engineering of acidophilic bacteria. 130 isolates of acidophilic bacteria (major species are iron-oxidizing bacteria) were isolated from various environment. 10 isolates of iron-oxidizing bacteria were selected in the point of high ferrous iron oxidizing ability and heavy metal tolerance. Mercury ion resistance genes of iron-oxidizing bacteria were identified and cloned in E.coli. Sequencing analysis and functional identification of gene products were performed. These genes are thought to be useful for selection marker of gen engineering of acidophilic bacteria. (NEDO)

  18. Elective culture of bacteria used in bioleaching on pyrrhotite

    Institute of Scientific and Technical Information of China (English)

    邱冠周; 覃文庆; 蓝卓越; 黎维中

    2003-01-01

    Elective culture of bacteria on pyrrhotite was researched, and the selected bacteria were tested on bi-oleaching of marmatite and zinc sulfide ore. The results show that the microorganism cultured on pyrrhotite with va-rious S/Fe ratios is a mixed culture of thiobacillus ferrooxidans and thiobacillus thiooxidans, of which the integral ac-tivity and the oxidation capability of Fe2+ and S are enhanced. With the high Fe and low S content of pyrrhotite, the oxida-tion capacity of ferrous ion is improved; on the contrary, the oxidation capacity of sulfur is advanced. The bioleaching ca-pacity of bacteria cultured on marmatite is better than that of the bacteria cultivated by conventional methods.

  19. The anammoxosome: an intracytoplasmic compartment in anammox bacteria

    NARCIS (Netherlands)

    Niftrik, L.A.M.P. van; Fuerst, J.A.; Damste, J.S.S.; Kuenen, J.G.; Jetten, M.S.M.; Strous, M.

    2004-01-01

    Anammox bacteria belong to the phylum Planctomycetes and perform anaerobic ammonium oxidation (anammox); they oxidize ammonium with nitrite as the electron acceptor to yield dinitrogen gas. The anammox reaction takes place inside the anammoxosome: an intracytoplasmic compartment bounded by a single

  20. The anammoxosome : An intracytoplasmic compartment in anammox bacteria

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Niftrik, L.A. van; Fuerst, J.A.; Kuenen, J.G.; Jetten, M.S.M.; Strous, M.

    2004-01-01

    Anammox bacteria belong to the phylum Planctomycetes and perform anaerobic ammonium oxidation (anammox); they oxidize ammonium with nitrite as the electron acceptor to yield dinitrogen gas. The anammox reaction takes place inside the anammoxosome: an intracytoplasmic compartment bounded by a single

  1. Complex community of nitrite-dependent anaerobic methane oxidation bacteria in coastal sediments of the Mai Po wetland by PCR amplification of both 16S rRNA and pmoA genes.

    Science.gov (United States)

    Chen, Jing; Zhou, Zhichao; Gu, Ji-Dong

    2015-02-01

    In the present work, both 16S rRNA and pmoA gene-based PCR primers were employed successfully to study the diversity and distribution of n-damo bacteria in the surface and lower layer sediments at the coastal Mai Po wetland. The occurrence of n-damo bacteria in both the surface and subsurface sediments with high diversity was confirmed in this study. Unlike the two other known n-damo communities from coastal areas, the pmoA gene-amplified sequences in the present work clustered not only with some freshwater subclusters but also within three newly erected marine subclusters mostly, indicating the unique niche specificity of n-damo bacteria in this wetland. Results suggested vegetation affected the distribution and community structures of n-damo bacteria in the sediments and n-damo could coexist with sulfate-reducing methanotrophs in the coastal ecosystem. Community structures of the Mai Po n-damo bacteria based on 16S rRNA gene were different from those of either the freshwater or the marine. In contrast, structures of the Mai Po n-damo communities based on pmoA gene grouped with the marine ones and were clearly distinguished from the freshwater ones. The abundance of n-damo bacteria at this wetland was quantified using 16S rRNA gene PCR primers to be 2.65-6.71 × 10(5) copies/g dry sediment. Ammonium and nitrite strongly affected the community structures and distribution of n-damo bacteria in the coastal Mai Po wetland sediments.

  2. Reducing gas content of coal deposits by means of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska-Lipowa, A A; Kozlowski, B

    1981-07-01

    This paper discusses the results of experiments carried out in Poland under laboratory conditions on efficiency of methane control using bacteria from Methanosarcina and Methanomonas groups. Malashenko and Whittenburry culture mediums were used. Bacteria growth in an atmosphere of air and methane (48.2%, 8.6% and 5.21%) was observed. Temperature ranged from 19 to 20 C. Investigations show that the bacteria are characterized by high oxidation activity. Depending on methane concentration in the air the bacteria consume from 75% to 100% of methane during biosynthesis. The bacteria reduce methane and oxygen content and increase carbon dioxide content in the air. Using bacteria methane concentration in the air was reduced from 48.2% to 12.3%, from 8.6% to 0.0% and from 5.21% to 0.01%. (7 refs.) (In Polish)

  3. Bacteria and Acidic Drainage from Coal Refuse: Inhibition by Sodium Lauryl Sulfate and Sodium Benzoate

    OpenAIRE

    Dugan, Patrick R.; Apel, William A.

    1983-01-01

    The application of an aqueous solution of sodium lauryl sulfate and sodium benzoate to the surface of high-sulfur coal refuse resulted in the inhibition of iron-and sulfur-oxidizing chemoautotrophic bacteria and in the decrease of acidic drainage from the refuse, suggesting that acid drainage can be abated in the field by inhibiting iron- and sulfur-oxidizing bacteria.

  4. Antibiotics from predatory bacteria

    Directory of Open Access Journals (Sweden)

    Juliane Korp

    2016-03-01

    Full Text Available Bacteria, which prey on other microorganisms, are commonly found in the environment. While some of these organisms act as solitary hunters, others band together in large consortia before they attack their prey. Anecdotal reports suggest that bacteria practicing such a wolfpack strategy utilize antibiotics as predatory weapons. Consistent with this hypothesis, genome sequencing revealed that these micropredators possess impressive capacities for natural product biosynthesis. Here, we will present the results from recent chemical investigations of this bacterial group, compare the biosynthetic potential with that of non-predatory bacteria and discuss the link between predation and secondary metabolism.

  5. Copper tolerance and virulence in bacteria

    Science.gov (United States)

    Ladomersky, Erik; Petris, Michael J.

    2015-01-01

    Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host. PMID:25652326

  6. Extracellular communication in bacteria

    DEFF Research Database (Denmark)

    Chhabra, S.R.; Philipp, B.; Eberl, L.

    2005-01-01

    molecules, in different Gram-positive and Gram-negative bacteria they control pathogenicity, secondary metabolite production, biofilm differentiation, DNA transfer and bioluminescence. The development of biosensors for the detection of these signal molecules has greatly facilitated their subsequent chemical...

  7. Do Bacteria Age?

    Indian Academy of Sciences (India)

    Bacteria are thought to be examples of organisms that do not age. They divide by .... carry genetic material to the next generation through the process of reproduction; they are also .... molecules, and modified proteins. This report revealed that ...

  8. Social Behaviour in Bacteria

    Indian Academy of Sciences (India)

    Administrator

    the recipient. • Social behaviours can be categorized according to the fitness ... is actually the flagella of symbiotic spirochete bacteria that helps it to swim around .... Normal population. Responsive switching. (Environmental stress). Stochastic.

  9. [Darwin and bacteria].

    Science.gov (United States)

    Ledermann D, Walter

    2009-02-01

    As in 2009 the scientific world celebrates two hundreds years from the birthday of Charles Darwin and one hundred and fifty from the publication of The Origin of Species, an analysis of his complete work is performed, looking for any mention of bacteria. But it seems that the great naturahst never took knowledge about its existence, something rather improbable in a time when the discovery of bacteria shook the medical world, or he deliberately ignored them, not finding a place for such microscopic beings into his theory of evolution. But the bacteria badly affected his familiar life, killing scarlet fever one of his children and worsening to death the evolution of tuberculosis of his favourite Annie. Darwin himself could suffer the sickness of Chagas, whose etiological agent has a similar level to bacteria in the scale of evolution.

  10. Lipopolysaccharides in diazotrophic bacteria

    OpenAIRE

    Serrato, Rodrigo V.

    2014-01-01

    Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are...

  11. Autotrophic and heterotrophic nitrification-anoxic denitrification dominated the anoxic/oxic sewage treatment process during optimization for higher loading rate and energy savings.

    Science.gov (United States)

    Zhang, Xueyu; Zheng, Shaokui; Zhang, Hangyu; Duan, Shoupeng

    2018-04-30

    This study clarified the dominant nitrogen (N)-transformation pathway and the key ammonia-oxidizing microbial species at three loading levels during optimization of the anoxic/oxic (A/O) process for sewage treatment. Comprehensive N-transformation activity analysis showed that ammonia oxidization was performed predominantly by aerobic chemolithotrophic and heterotrophic ammonia oxidization, whereas N 2 production was performed primarily by anoxic denitrification in the anoxic unit. The abundances of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria, and anaerobic AOB in activated sludge reflected their activities on the basis of high-throughput sequencing data. AOB amoA gene clone libraries revealed that the predominant AOB species in sludge samples shifted from Nitrosomonas europaea (61% at the normal loading level) to Nitrosomonas oligotropha (58% and 81% at the two higher loading levels). Following isolation and sequencing, the predominant culturable heterotrophic AOB in sludge shifted from Agrobacterium tumefaciens (42% at the normal loading level) to Acinetobacter johnsonii (52% at the highest loading level). Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Lipopolysaccharides in diazotrophic bacteria.

    Science.gov (United States)

    Serrato, Rodrigo V

    2014-01-01

    Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are found between associative diazotrophs and plants, resulting in plant infection and colonization of internal tissues. Independent of the type of ecological interaction, glycans, and glycoconjugates produced by these bacteria play an important role in the molecular communication prior and during colonization. Even though exopolysaccharides (EPS) and lipochitooligosaccharides (LCO) produced by diazotrophic bacteria and released onto the environment have their importance in the microbe-plant interaction, it is the lipopolysaccharides (LPS), anchored on the external membrane of these bacteria, that mediates the direct contact of the diazotroph with the host cells. These molecules are extremely variable among the several species of nitrogen fixing-bacteria, and there are evidences of the mechanisms of infection being closely related to their structure.

  13. Beneficial effects of antioxidative lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Hisako Nakagawa

    2017-01-01

    Full Text Available Oxidative stress is caused by exposure to reactive oxygen intermediates. The oxidative damage of cell components such as proteins, lipids, and nucleic acids one of the important factors associated with diabetes mellitus, cancers and cardiovascular diseases. This occurs as a result of imbalance between the generations of oxygen derived radicals and the organism’s antioxidant potential. The amount of oxidative damage increases as an organism ages and is postulated to be a major causal factor of senescence. To date, many studies have focused on food sources, nutrients, and components that exert antioxidant activity in worms, flies, mice, and humans. Probiotics, live microorganisms that when administered in adequate amounts provide many beneficial effects on the human health, have been attracting growing interest for their health-promoting effects, and have often been administered in fermented milk products. In particular, lactic acid bacteria (LAB are known to conferre physiologic benefits. Many studies have indicated the antioxidative activity of LAB. Here we review that the effects of lactic acid bacteria to respond to oxidative stress, is connected to oxidative-stress related disease and aging.

  14. Bacteria and plutonium in marine environments

    International Nuclear Information System (INIS)

    Carey, A.E.; Bowen, V.T.

    1978-01-01

    Microbes are important in geochemical cycling of many elements. Recent reports emphasize biogenous particulates and bacterial exometabolites as controlling oceanic distribution of plutonium. Bacteria perform oxidation/reduction reactions on metals such as mercury, nickel, lead, copper, and cadmium. Redox transformations or uptake of Pu by marine bacteria may well proceed by similar mechanisms. Profiles of water samples and sediment cores were obtained along the continental shelf off Nova Scotia and in the Gulf of St. Lawrence. Profiles of water samples, and sediment cores were obtained. Epifluorescent microscopy was used to view bacteria (from water or sediment) after concentration on membrane filters and staining with acridine orange. Radiochemical analyses measured Pu in sediments and water samples. Studies of 237 Pu uptake used a strain of Leucothrix mucor isolated from a macroalga. Enumeration shows bacteria to range 10 4 to 10 5 cells/ml in seawater or 10 7 to 10 8 cells/gram of sediment. These numbers are related to the levels and distrbution of Pu in the samples. In cultures of L. mucor amended with Pu atom concentrations approximating those present in open ocean environments, bacterial cells concentrated 237 Pu slower and to lower levels than did clay minerals, glass beads, or phytoplankton. These data further clarify the role of marine bacteria in Pu biogeochemistry

  15. Chemically enhanced sunlight for killing bacteria

    International Nuclear Information System (INIS)

    Block, S.S.; Goswami, D.Y.

    1995-01-01

    Solar ultraviolet (UV) photocatalyzed oxidation of chemicals with titanium dioxide (TiO 2 ) has received considerable attention. Much less recognized, however, is the ability of the same system to destroy bacteria. This study examined this phenomenon and the conditions that affect it. Bacteria in aqueous solution were given solar exposure with titanium dioxide and their survival with time was determined. Lamps with a predominantly solar ultraviolet spectrum were also used in the experiments. Without exposure to UV light, TiO 2 had no deleterious effect on the bacteria. However, several common bacteria on solar exposure in the presence of TiO 2 were killed in just a few minutes, whereas without TiO 2 it took over an hour to destroy them. A concentration of 0.01% TiO 2 was most effective in killing bacteria and 10-fold concentrations lower or higher were successively less effective. Inorganic and organic compounds in solution, even in small amounts, interfered with the efficiency of killing. Alkaline solution also reduced the bactericidal activity. Circulation and agitation provided by stirring to keep the TiO 2 particles suspended reduced the time necessary to kill the bacteria. Time-intensity curves for killing bacteria were the same general shape with or without TiO 2 , indicating that TiO 2 served merely as a catalyst to increase the rate of the reaction but that the mechanism of action was not changed. The shape of the curves show that the organisms are sensitized with a minimum intensity of radiation and that an increase doesn't greatly increase the rate of kill. Below this critical intensity, however, the time required for killing markedly increases as the intensity is decreased

  16. A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions.

    Science.gov (United States)

    Wahman, David G; Speitel, Gerald E; Machavaram, Madhav V

    2014-09-01

    Drinking water monochloramine (NH2Cl) use may promote ammonia-oxidizing bacteria (AOB). AOB use (i) ammonia monooxygenase for biological ammonia (NH3) oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrite. NH2Cl and NH2OH may react, providing AOB potential benefits and detriments. The NH2Cl/NH2OH reaction would benefit AOB by removing the disinfectant (NH2Cl) and releasing their growth substrate (NH3), but the NH2Cl/NH2OH reaction would also provide a possible additional inactivation mechanism besides direct NH2Cl reaction with cells. Because biological NH2OH oxidation supplies the electrons required for biological NH3 oxidation, the NH2Cl/NH2OH reaction provides a direct mechanism for NH2Cl to inhibit NH3 oxidation, starving the cell of reductant by preventing biological NH2OH oxidation. To investigate possible NH2Cl/NH2OH reaction implications on AOB, an understanding of the underlying abiotic reaction is first required. The present study conducted a detailed literature review and proposed an abiotic NH2Cl/NH2OH reaction scheme (RS) for chloramination relevant drinking water conditions (μM concentrations, air saturation, and pH 7-9). Next, RS literature based kinetics and end-products were evaluated experimentally between pHs 7.7 and 8.3, representing (i) the pH range for future experiments with AOB and (ii) mid-range pHs typically found in chloraminated drinking water. In addition, a (15)N stable isotope experiment was conducted to verify nitrous oxide and nitrogen gas production and their nitrogen source. Finally, the RS was slightly refined using the experimental data and an AQUASIM implemented kinetic model. A chloraminated drinking water relevant RS is proposed and provides the abiotic reaction foundation for future AOB biotic experiments. Published by Elsevier Ltd.

  17. The fecal bacteria

    Science.gov (United States)

    Sadowsky, Michael J.; Whitman, Richard L.

    2011-01-01

    The Fecal Bacteria offers a balanced, integrated discussion of fecal bacteria and their presence and ecology in the intestinal tract of mammals, in the environment, and in the food supply. This volume covers their use in examining and assessing water quality in order to offer protection from illnesses related to swimming in or ingesting contaminated water, in addition to discussing their use in engineering considerations of water quality, modeling, monitoring, and regulations. Fecal bacteria are additionally used as indicators of contamination of ready-to-eat foods and fresh produce. The intestinal environment, the microbial community structure of the gut microbiota, and the physiology and genomics of this broad group of microorganisms are explored in the book. With contributions from an internationally recognized group of experts, the book integrates medicine, public health, environmental, and microbiological topics in order to provide a unique, holistic understanding of fecal bacteria. Moreover, it shows how the latest basic science and applied research findings are helping to solve problems and develop effective management strategies. For example, readers will discover how the latest tools and molecular approaches have led to our current understanding of fecal bacteria and enabled us to improve human health and water quality. The Fecal Bacteria is recommended for microbiologists, clinicians, animal scientists, engineers, environmental scientists, food safety experts, water quality managers, and students. It will help them better understand fecal bacteria and use their knowledge to protect human and environmental health. They can also apply many of the techniques and molecular tools discussed in this book to the study of a broad range of microorganisms in a variety of habitats.

  18. Kinetic models for nitrogen inhibition in ANAMMOX and nitrification process on deammonification system at room temperature.

    Science.gov (United States)

    De Prá, Marina C; Kunz, Airton; Bortoli, Marcelo; Scussiato, Lucas A; Coldebella, Arlei; Vanotti, Matias; Soares, Hugo M

    2016-02-01

    In this study were fitted the best kinetic model for nitrogen removal inhibition by ammonium and/or nitrite in three different nitrogen removal systems operated at 25 °C: a nitrifying system (NF) containing only ammonia oxidizing bacteria (AOB), an ANAMMOX system (AMX) containing only ANAMMOX bacteria, and a deammonification system (DMX) containing both AOB and ANAMMOX bacteria. NF system showed inhibition by ammonium and was best described by Andrews model. The AMX system showed a strong inhibition by nitrite and Edwards model presented a best system representation. For DMX system, the increased substrate concentration (until 1060 mg NH3-N/L) tested was not limiting for the ammonia consumption rate and the Monod model was the best model to describe this process. The AOB and ANAMMOX sludges combined in the DMX system displayed a better activity, substrate affinity and excellent substrate tolerance than in nitrifying and ANAMMOX process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Mycorrhiza helper bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Deveau, Aurelie [French National Insitute for Agricultural Research (INRA); Labbe, Jessy [ORNL

    2016-10-01

    This chapter focuses on the Mycorrhiza Helper Bacteria (MHB), a generic name given to bacteria which stimulate the formation of mycorrhizal symbiosis. By extension, some bacterial strains that positively impact the functioning of mycorrhizal symbiosis are also called MHB. These bacteria have applicative interests, as they indirectly improve the health and growth of tree seedlings. MHB are not restricted to a specific type of ecosystem, but are rather generalist in the way that they associate with both herbaceous and woody mycorrhizal plants from boreal, temperate, arid and tropical ecosystems. However, understanding the molecular mechanisms and their specificities will help us to know more about the ecology of the MHB. The process of acquisition varies between fungal species; while ectomycorrhizal fungi most probably recurrently acquire them from the environment, the association between bacterial endosymbionts and Glomeromycota probably dates back to very ancient times, and has since been vertically transmitted.

  20. Mechanistic modeling of biocorrosion caused by biofilms of sulfate reducing bacteria and acid producing bacteria.

    Science.gov (United States)

    Xu, Dake; Li, Yingchao; Gu, Tingyue

    2016-08-01

    Biocorrosion is also known as microbiologically influenced corrosion (MIC). Most anaerobic MIC cases can be classified into two major types. Type I MIC involves non-oxygen oxidants such as sulfate and nitrate that require biocatalysis for their reduction in the cytoplasm of microbes such as sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). This means that the extracellular electrons from the oxidation of metal such as iron must be transported across cell walls into the cytoplasm. Type II MIC involves oxidants such as protons that are secreted by microbes such as acid producing bacteria (APB). The biofilms in this case supply the locally high concentrations of oxidants that are corrosive without biocatalysis. This work describes a mechanistic model that is based on the biocatalytic cathodic sulfate reduction (BCSR) theory. The model utilizes charge transfer and mass transfer concepts to describe the SRB biocorrosion process. The model also includes a mechanism to describe APB attack based on the local acidic pH at a pit bottom. A pitting prediction software package has been created based on the mechanisms. It predicts long-term pitting rates and worst-case scenarios after calibration using SRB short-term pit depth data. Various parameters can be investigated through computer simulation. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    International Nuclear Information System (INIS)

    Peszke, Jerzy; Nowak, Anna; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena; Krzyściak, Paweł; Zygoń, Patrycja; Ratuszna, Alicja; Ostafin, Marek M.

    2016-01-01

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu 2 O/CuO nanoparticles.

  2. Effect of silver/copper and copper oxide nanoparticle powder on growth of Gram-negative and Gram-positive bacteria and their toxicity against the normal human dermal fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Peszke, Jerzy; Nowak, Anna, E-mail: ana.maria.nowak@gmail.com; Szade, Jacek; Szurko, Agnieszka; Zygadło, Dorota; Michałowska, Marlena [University of Silesia, A. Chelkowski Institute of Physics (Poland); Krzyściak, Paweł [Jagiellonian University Medical College, Department of Mycology Chair of Microbiology (Poland); Zygoń, Patrycja [Czestochowa University of Technology, Institute of Materials Engineering (Poland); Ratuszna, Alicja [University of Silesia, A. Chelkowski Institute of Physics (Poland); Ostafin, Marek M. [Department of Microbiology University of Agriculture (Poland)

    2016-12-15

    Engineered nanomaterials, especially metallic nanoparticles, are the most popular system applied in daily life products. The study of their biological and toxicity properties seems to be indispensable. In this paper, we present results of biological activity of Ag/Cu nanoparticles. These nanoparticles show more promising killing/inhibiting properties on Gram-negative bacteria than for Gram-positive ones. The Gram-negative bacteria show strong effect already at the concentration of 1 ppm after 15 min of incubation. Moreover, in vitro tests of toxicity made on normal human dermal fibroblast cultures showed that after 72 h of incubation with Ag/Cu nanoparticles, they are less toxic then Cu{sub 2}O/CuO nanoparticles.

  3. Exogenous fatty acid metabolism in bacteria.

    Science.gov (United States)

    Yao, Jiangwei; Rock, Charles O

    2017-10-01

    Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  4. Communication among Oral Bacteria

    Science.gov (United States)

    Kolenbrander, Paul E.; Andersen, Roxanna N.; Blehert, David S.; Egland, Paul G.; Foster, Jamie S.; Palmer, Robert J.

    2002-01-01

    Human oral bacteria interact with their environment by attaching to surfaces and establishing mixed-species communities. As each bacterial cell attaches, it forms a new surface to which other cells can adhere. Adherence and community development are spatiotemporal; such order requires communication. The discovery of soluble signals, such as autoinducer-2, that may be exchanged within multispecies communities to convey information between organisms has emerged as a new research direction. Direct-contact signals, such as adhesins and receptors, that elicit changes in gene expression after cell-cell contact and biofilm growth are also an active research area. Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ. Oral biofilms are readily accessible to microbiologists and are excellent model systems for studies of microbial communication. One attractive model system is a saliva-coated flowcell with oral bacterial biofilms growing on saliva as the sole nutrient source; an intergeneric mutualism is discussed. Several oral bacterial species are amenable to genetic manipulation for molecular characterization of communication both among bacteria and between bacteria and the host. A successful search for genes critical for mixed-species community organization will be accomplished only when it is conducted with mixed-species communities. PMID:12209001

  5. PATHOGENICITY OF BIOFILM BACTERIA

    Science.gov (United States)

    There is a paucity of information concerning any link between the microorganisms commonly found in biofilms of drinking water systems and their impacts on human health. For bacteria, culture-based techniques detect only a limited number of the total microorganisms associated wit...

  6. Bacteria-surface interactions.

    Science.gov (United States)

    Tuson, Hannah H; Weibel, Douglas B

    2013-05-14

    The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

  7. Antifreeze Proteins of Bacteria

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 12. Antifreeze Proteins of Bacteria. M K Chattopadhyay. General Article Volume 12 Issue 12 December 2007 pp 25-30. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/012/12/0025-0030 ...

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

    Directory of Open Access Journals (Sweden)

    Yuan Liu

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

  9. Identification of marine methanol-utilizing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, M; Iwaki, H; Kouno, K; Inui, T

    1980-01-01

    A taxonomical study of 65 marine methanol-utilizing bacteria is described. They were Gram-negative, non-spore-forming rods with a polar flagellum and had marine bacterial properties and required vitamin B/sub 12/ for growth. All of them assimilated fructose in addition to C/sub 1/-compounds and produced acid oxidatively from fructose. Twenty-four strains assimilated only C/sub 1/-compounds. They were resistant to penicillin, oxytetracycline and 0/129 substance (Vibrio stat), and tolerant to 12% NaCl. Guanine-cytosine contents of deoxyribonucleic acid in typical strains fell in the range of 43.8 to 47.6%. Other morphological and physiological properties were almost the same as those of terrestrial methanol-utilizers. Bacteria in the first group (41 strains) were facultative methylotrophs and were divided into three subgroups by the assimilation of methylated amines, that is, subgroup I (30 strains) assimilated mono-, di- and tri-methylamine, subgroup II (9 strains) assimilated only mono-methylamine, the bacteria of subgroups I and II were named Alteromonas thalassomethanolica sp. nov. and subgroup III (2 strains) did not assimilate methylated amines, and was tentatively assigned as Alteromonas sp. The second group of bacteria (24 strains) was obligate methylotrophs, named Methylomonas thalassica sp. nov. and was divided into subgroup IV (15 strains) which assimilated mono-, di and tri-methylamine and subgroup V (9 strains) which assimilated mono-methylamine.

  10. Staphylococcal response to oxidative stress

    Directory of Open Access Journals (Sweden)

    Rosmarie eGaupp

    2012-03-01

    Full Text Available Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria’s interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host.

  11. The friendly bacteria within us Commensal bacteria of the intestine ...

    Indian Academy of Sciences (India)

    Balance of bacterial species in the gut · Immunosensory detection of intestinal bacteria · Pathogenic bacteria release interleukin-8 from HT-29 cells · Lactobacillus GG prevents the IL-8 release in response to pathogens · Effect of probiotic bacteria on chemokine response of epithelia to pathogens · PCR array studies in colon ...

  12. Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria.

    Science.gov (United States)

    Beltran-Garcia, Miguel J; White, James F; Prado, Fernanda M; Prieto, Katia R; Yamaguchi, Lydia F; Torres, Monica S; Kato, Massuo J; Medeiros, Marisa H G; Di Mascio, Paolo

    2014-11-06

    Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its seed-transmitted endophyte Bacillus tequilensis to elucidate organic nitrogen transfer from (15)N-labeled bacteria to plants. Bacillus tequilensis cells grown in a minimal medium with (15)NH4Cl as the nitrogen source were watered onto plants growing in sand. We traced incorporation of (15)N into tryptophan, deoxynucleosides and pheophytin derived from chlorophyll a. Probes for hydrogen peroxide show its presence during degradation of bacteria in plant tissues, supporting involvement of reactive oxygen in the degradation process. In another experiment to assess nitrogen absorbed as a result of endophytic colonization of plants we demonstrated that endophytic bacteria potentially transfer more nitrogen to plants and stimulate greater biomass in plants than heat-killed bacteria that do not colonize plants but instead degrade in the soil. Findings presented here support the hypothesis that some plants under nutrient limitation may degrade and obtain nitrogen from endophytic microbes.

  13. Trait-based representation of biological nitrification: Model development, testing, and predicted community composition

    Directory of Open Access Journals (Sweden)

    Nick eBouskill

    2012-10-01

    Full Text Available Trait-based microbial models show clear promise as tools to represent the diversity and activity of microorganisms across ecosystem gradients. These models parameterize specific traits that determine the relative fitness of an ‘organism’ in a given environment, and represent the complexity of biological systems across temporal and spatial scales. In this study we introduce a microbial community trait-based modeling framework (MicroTrait focused on nitrification (MicroTrait-N that represents the ammonia-oxidizing bacteria (AOB and ammonia-oxidizing archaea (AOA and nitrite oxidizing bacteria (NOB using traits related to enzyme kinetics and physiological properties. We used this model to predict nitrifier diversity, ammonia (NH3 oxidation rates and nitrous oxide (N2O production across pH, temperature and substrate gradients. Predicted nitrifier diversity was predominantly determined by temperature and substrate availability, the latter was strongly influenced by pH. The model predicted that transient N2O production rates are maximized by a decoupling of the AOB and NOB communities, resulting in an accumulation and detoxification of nitrite to N2O by AOB. However, cumulative N2O production (over six month simulations is maximized in a system where the relationship between AOB and NOB is maintained. When the reactions uncouple, the AOB become unstable and biomass declines rapidly, resulting in decreased NH3 oxidation and N2O production. We evaluated this model against site level chemical datasets from the interior of Alaska and accurately simulated NH3 oxidation rates and the relative ratio of AOA:AOB biomass. The predicted community structure and activity indicate (a parameterization of a small number of traits may be sufficient to broadly characterize nitrifying community structure and (b changing decadal trends in climate and edaphic conditions could impact nitrification rates in ways that are not captured by extant biogeochemical models.

  14. Manufacture of Probiotic Bacteria

    Science.gov (United States)

    Muller, J. A.; Ross, R. P.; Fitzgerald, G. F.; Stanton, C.

    Lactic acid bacteria (LAB) have been used for many years as natural biopreservatives in fermented foods. A small group of LAB are also believed to have beneficial health effects on the host, so called probiotic bacteria. Probiotics have emerged from the niche industry from Asia into European and American markets. Functional foods are one of the fastest growing markets today, with estimated growth to 20 billion dollars worldwide by 2010 (GIA, 2008). The increasing demand for probiotics and the new food markets where probiotics are introduced, challenges the industry to produce high quantities of probiotic cultures in a viable and stable form. Dried concentrated probiotic cultures are the most convenient form for incorporation into functional foods, given the ease of storage, handling and transport, especially for shelf-stable functional products. This chapter will discuss various aspects of the challenges associated with the manufacturing of probiotic cultures.

  15. Fermentative Bacteria Influence the Competition between Denitrifiers and DNRA Bacteria

    Directory of Open Access Journals (Sweden)

    Eveline M. van den Berg

    2017-09-01

    Full Text Available Denitrification and dissimilatory reduction to ammonium (DNRA are competing nitrate-reduction processes that entail important biogeochemical consequences for nitrogen retention/removal in natural and man-made ecosystems. The nature of the available carbon source and electron donor have been suggested to play an important role on the outcome of this microbial competition. In this study, the influence of lactate as fermentable carbon source on the competition for nitrate was investigated for varying ratios of lactate and nitrate in the influent (Lac/N ratio. The study was conducted in an open chemostat culture, enriched from activated sludge, under strict anoxia. The mechanistic explanation of the conversions observed was based on integration of results from specific batch tests with biomass from the chemostat, molecular analysis of the biomass enriched, and a computational model. At high Lac/N ratio (2.97 mol/mol both fermentative and respiratory nitrate reduction to ammonium occurred, coupled to partial oxidation of lactate to acetate, and to acetate oxidation respectively. Remaining lactate was fermented to propionate and acetate. At a decreased Lac/N ratio (1.15 mol/mol, the molar percentage of nitrate reduced to ammonium decreased to 58%, even though lactate was supplied in adequate amounts for full ammonification and nitrate remained the growth limiting compound. Data evaluation at this Lac/N ratio suggested conversions were comparable to the higher Lac/N ratio, except for lactate oxidation to acetate that was coupled to denitrification instead of ammonification. Respiratory DNRA on acetate was likely catalyzed by two Geobacter species related to G. luticola and G. lovleyi. Two Clostridiales members were likely responsible for lactate fermentation and partial lactate fermentation to acetate coupled to fermentative DNRA. An organism related to Propionivibrio militaris was identified as the organism likely responsible for denitrification. The

  16. Pepsin homologues in bacteria

    Directory of Open Access Journals (Sweden)

    Bateman Alex

    2009-09-01

    Full Text Available Abstract Background Peptidase family A1, to which pepsin belongs, had been assumed to be restricted to eukaryotes. The tertiary structure of pepsin shows two lobes with similar folds and it has been suggested that the gene has arisen from an ancient duplication and fusion event. The only sequence similarity between the lobes is restricted to the motif around the active site aspartate and a hydrophobic-hydrophobic-Gly motif. Together, these contribute to an essential structural feature known as a psi-loop. There is one such psi-loop in each lobe, and so each lobe presents an active Asp. The human immunodeficiency virus peptidase, retropepsin, from peptidase family A2 also has a similar fold but consists of one lobe only and has to dimerize to be active. All known members of family A1 show the bilobed structure, but it is unclear if the ancestor of family A1 was similar to an A2 peptidase, or if the ancestral retropepsin was derived from a half-pepsin gene. The presence of a pepsin homologue in a prokaryote might give insights into the evolution of the pepsin family. Results Homologues of the aspartic peptidase pepsin have been found in the completed genomic sequences from seven species of bacteria. The bacterial homologues, unlike those from eukaryotes, do not possess signal peptides, and would therefore be intracellular acting at neutral pH. The bacterial homologues have Thr218 replaced by Asp, a change which in renin has been shown to confer activity at neutral pH. No pepsin homologues could be detected in any archaean genome. Conclusion The peptidase family A1 is found in some species of bacteria as well as eukaryotes. The bacterial homologues fall into two groups, one from oceanic bacteria and one from plant symbionts. The bacterial homologues are all predicted to be intracellular proteins, unlike the eukaryotic enzymes. The bacterial homologues are bilobed like pepsin, implying that if no horizontal gene transfer has occurred the duplication

  17. The interaction of bacteria and metal surfaces

    International Nuclear Information System (INIS)

    Mansfeld, Florian

    2007-01-01

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E corr became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V)-current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions

  18. The interaction of bacteria and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mansfeld, Florian [Corrosion and Environmental Effects Laboratory (CEEL), The Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States)

    2007-10-10

    This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E{sub corr} became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V) - current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions. (author)

  19. Evaluating the potential for dissimilatory nitrate reduction by anammox bacteria for municipal wastewater treatment.

    Science.gov (United States)

    Castro-Barros, Celia M; Jia, Mingsheng; van Loosdrecht, Mark C M; Volcke, Eveline I P; Winkler, Mari K H

    2017-06-01

    Anammox bacteria can perform dissimilatory nitrate reduction to ammonium (DNRA) with nitrite as intermediate coupled to the oxidation of volatile fatty acids (VFA). Batch tests with enriched anammox and a co-culture of anammox and heterotrophic bacteria showed the capacity of Candidatus 'Brocadia fulgida' to perform the DNRA coupled to the anammox reaction (DNRA-anammox) at a high rate although the culture was not previously adapted to VFA. From thermodynamic calculations it could be stated that low COD/N influent ratios favour the DNRA-anammox transformation over heterotrophic conversions since more free energy is gained. A process scheme is proposed for an innovative nitrogen removal system in which the nitrate produced by nitrite oxidizing bacteria and/or anammox bacteria is converted during DNRA-anammox pathway, resulting in a sustainable nitrogen removal from municipal wastewater while circumventing the troublesome out-selection of nitrite oxidizing bacteria encountered in mainstream applications. Copyright © 2017. Published by Elsevier Ltd.

  20. Model-Based Feasibility Assessment of Membrane Biofilm Reactor to Achieve Simultaneous Ammonium, Dissolved Methane, and Sulfide Removal from Anaerobic Digestion Liquor

    Science.gov (United States)

    Chen, Xueming; Liu, Yiwen; Peng, Lai; Yuan, Zhiguo; Ni, Bing-Jie

    2016-01-01

    In this study, the membrane biofilm reactor (MBfR) is proposed to achieve simultaneous removal of ammonium, dissolved methane, and sulfide from main-stream and side-stream anaerobic digestion liquors. To avoid dissolved methane stripping, oxygen is introduced through gas-permeable membranes, which also from the substratum for the growth of a biofilm likely comprising ammonium oxidizing bacteria (AOB), anaerobic ammonium oxidation (Anammox) bacteria, denitrifying anaerobic methane oxidation (DAMO) microorganisms, aerobic methane oxidizing bacteria (MOB), and sulfur oxidizing bacteria (SOB). A mathematical model is developed and applied to assess the feasibility of such a system and the associated microbial community structure under different operational conditions. The simulation studies demonstrate the feasibility of achieving high-level (>97.0%), simultaneous removal of ammonium, dissolved methane, and sulfide in the MBfRs from both main-stream and side-stream anaerobic digestion liquors through adjusting the influent surface loading (or hydraulic retention time (HRT)) and the oxygen surface loading. The optimal HRT was found to be inversely proportional to the corresponding oxygen surface loading. Under the optimal operational conditions, AOB, DAMO bacteria, MOB, and SOB dominate the biofilm of the main-stream MBfR, while AOB, Anammox bacteria, DAMO bacteria, and SOB coexist in the side-stream MBfR to remove ammonium, dissolved methane, and sulfide simultaneously. PMID:27112502

  1. Influence of water quality on nitrifier regrowth in two full-scale drinking water distribution systems.

    Science.gov (United States)

    Scott, Daniel B; Van Dyke, Michele I; Anderson, William B; Huck, Peter M

    2015-12-01

    The potential for regrowth of nitrifying microorganisms was monitored in 2 full-scale chloraminated drinking water distribution systems in Ontario, Canada, over a 9-month period. Quantitative PCR was used to measure amoA genes from ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), and these values were compared with water quality parameters that can influence nitrifier survival and growth, including total chlorine, ammonia, temperature, pH, and organic carbon. Although there were no severe nitrification episodes, AOB and AOA were frequently detected at low concentrations in samples collected from both distribution systems. A culture-based presence-absence test confirmed the presence of viable nitrifiers. AOB were usually present in similar or greater numbers than AOA in both systems. As well, AOB showed higher regrowth potential compared with AOA in both systems. Statistically significant correlations were measured between several water quality parameters of relevance to nitrification. Total chlorine was negatively correlated with both nitrifiers and heterotrophic plate count (HPC) bacteria, and ammonia levels were positively correlated with nitrifiers. Of particular importance was the strong correlation between HPC and AOB, which reinforced the usefulness of HPC as an operational parameter to measure general microbiological conditions in distribution systems.

  2. Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Franck, Stephanie; Gülay, Arda

    2014-01-01

    Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration...... (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r......-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal....

  3. Nicotinoprotein methanol dehydrogenase enzymes in Gram-positive methylotrophic bacteria

    NARCIS (Netherlands)

    Hektor, Harm J.; Kloosterman, Harm; Dijkhuizen, Lubbert

    2000-01-01

    A novel type of alcohol dehydrogenase enzyme has been characterized from Gram-positive methylotrophic (Bacillus methanolicus, the actinomycetes Amycolatopsis methanolica and Mycobacterium gastri) and non-methylotrophic bacteria (Rhodococcus strains). Its in vivo role is in oxidation of methanol and

  4. Applications of Magnetosomes Synthesized by Magnetotactic Bacteria in Medicine

    International Nuclear Information System (INIS)

    Alphandéry, Edouard

    2014-01-01

    Magnetotactic bacteria belong to a group of bacteria that synthesize iron oxide nanoparticles covered by biological material that are called magnetosomes. These bacteria use the magnetosomes as a compass to navigate in the direction of the earth’s magnetic field. This compass helps the bacteria to find the optimum conditions for their growth and survival. Here, we review several medical applications of magnetosomes, such as those in magnetic resonance imaging (MRI), magnetic hyperthermia, and drug delivery. Different methods that can be used to prepare the magnetosomes for these applications are described. The toxicity and biodistribution results that have been published are summarized. They show that the magnetosomes can safely be used provided that they are prepared in specific conditions. The advantageous properties of the magnetosomes compared with those of chemically synthesized nanoparticles of similar composition are also highlighted.

  5. Biophysical properties of membrane lipids of anammox bacteria : I. Ladderane phospholipids form highly organized fluid membranes

    NARCIS (Netherlands)

    Boumann, Henry A.; Longo, Marjorie L.; Stroeve, Pieter; Poolman, Bert; Hopmans, Ellen C.; Stuart, Marc C. A.; Damste, Jaap S. Sinninghe; Schouten, Stefan

    Anammox bacteria that are capable of anaerobically oxidizing ammonium (anammox) with nitrite to nitrogen gas produce unique membrane phospholipids that comprise hydrocarbon chains with three or five linearly condensed cyclobutane rings. To gain insight into the biophysical properties of these

  6. Mossbauer and magnetic study of solid phases formed by dissimilatory iron-reducing bacteria

    Czech Academy of Sciences Publication Activity Database

    Chistyakova, N.I.; Rusakov, V.S.; Shapkin, A.A.; Pigalev, P.A.; Kazakov, A.P.; Zhilina, T.N.; Zavarzina, D.G.; Lančok, Adriana; Kohout, J.; Greneche, J. M.

    2012-01-01

    Roč. 190, JUNE (2012), s. 721-724 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z40320502 Keywords : Mossbauer spectroscopy * dissimilatory iron-reducing bacteria * iron oxides * biomagnetism Subject RIV: CA - Inorganic Chemistry

  7. Treatment of antimony mine drainage: challenges and opportunities with special emphasis on mineral adsorption and sulfate reducing bacteria.

    Science.gov (United States)

    Li, Yongchao; Hu, Xiaoxian; Ren, Bozhi

    2016-01-01

    The present article summarizes antimony mine distribution, antimony mine drainage generation and environmental impacts, and critically analyses the remediation approach with special emphasis on iron oxidizing bacteria and sulfate reducing bacteria. Most recent research focuses on readily available low-cost adsorbents, such as minerals, wastes, and biosorbents. It is found that iron oxides prepared by chemical methods present superior adsorption ability for Sb(III) and Sb(V). However, this process is more costly and iron oxide activity can be inhibited by plenty of sulfate in antimony mine drainage. In the presence of sulfate reducing bacteria, sulfate can be reduced to sulfide and form Sb(2)S(3) precipitates. However, dissolved oxygen and lack of nutrient source in antimony mine drainage inhibit sulfate reducing bacteria activity. Biogenetic iron oxide minerals from iron corrosion by iron-oxidizing bacteria may prove promising for antimony adsorption, while the micro-environment generated from iron corrosion by iron oxidizing bacteria may provide better growth conditions for symbiotic sulfate reducing bacteria. Finally, based on biogenetic iron oxide adsorption and sulfate reducing bacteria followed by precipitation, the paper suggests an alternative treatment for antimony mine drainage that deserves exploration.

  8. Bacteria and Acidic Drainage from Coal Refuse: Inhibition by Sodium Lauryl Sulfate and Sodium Benzoate

    Science.gov (United States)

    Dugan, Patrick R.; Apel, William A.

    1983-01-01

    The application of an aqueous solution of sodium lauryl sulfate and sodium benzoate to the surface of high-sulfur coal refuse resulted in the inhibition of iron-and sulfur-oxidizing chemoautotrophic bacteria and in the decrease of acidic drainage from the refuse, suggesting that acid drainage can be abated in the field by inhibiting iron- and sulfur-oxidizing bacteria. PMID:16346347

  9. Isolation and Partial Characterization of Bacteria in an Anaerobic Consortium That Mineralizes 3-Chlorobenzoic Acid †

    OpenAIRE

    Shelton, Daniel R.; Tiedje, James M.

    1984-01-01

    A methanogenic consortium able to use 3-chlorobenzoic acid as its sole energy and carbon source was enriched from anaerobic sewage sludge. Seven bacteria were isolated from the consortium in mono- or coculture. They included: one dechlorinating bacterium (strain DCB-1), one benzoate-oxidizing bacterium (strain BZ-2), two butyrate-oxidizing bacteria (strains SF-1 and NSF-2), two H2-consuming methanogens (Methanospirillum hungatei PM-1 and Methanobacterium sp. strain PM-2), and a sulfate-reduci...

  10. Functional amyloids in bacteria.

    Science.gov (United States)

    Romero, Diego; Kolter, Roberto

    2014-06-01

    The term amyloidosis is used to refer to a family of pathologies altering the homeostasis of human organs. Despite having a name that alludes to starch content, the amyloid accumulations are made up of proteins that polymerize as long and rigid fibers. Amyloid proteins vary widely with respect to their amino acid sequences but they share similarities in their quaternary structure; the amyloid fibers are enriched in β-sheets arranged perpendicular to the axis of the fiber. This structural feature provides great robustness, remarkable stability, and insolubility. In addition, amyloid proteins specifically stain with certain dyes such as Congo red and thioflavin-T. The aggregation into amyloid fibers, however, it is not restricted to pathogenic processes, rather it seems to be widely distributed among proteins and polypeptides. Amyloid fibers are present in insects, fungi and bacteria, and they are important in maintaining the homeostasis of the organism. Such findings have motivated the use of the term "functional amyloid" to differentiate these amyloid proteins from their toxic siblings. This review focuses on systems that have evolved in bacteria that control the expression and assembly of amyloid proteins on cell surfaces, such that the robustness of amyloid proteins are used towards a beneficial end. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  11. Immunomodulatory properties of probiotic bacteria

    DEFF Research Database (Denmark)

    Fink, Lisbeth Nielsen

    2007-01-01

    Certain lactic acid bacteria (LAB) are part of the commensal intestinal flora and considered beneficial for health, as they compete with pathogens for adhesion sites in the intestine and ferment otherwise indigestible compounds. Another important property of th