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Segregating metabolic processes into different microbial cells accelerates the consumption of inhibitory substrates. ISME JOURNAL 2016; 10:1568-78. [PMID: 26771930 DOI: 10.1038/ismej.2015.243] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 11/16/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022]
Abstract
Different microbial cell types typically specialize at performing different metabolic processes. A canonical example is substrate cross-feeding, where one cell type consumes a primary substrate into an intermediate and another cell type consumes the intermediate. While substrate cross-feeding is widely observed, its consequences on ecosystem processes is often unclear. How does substrate cross-feeding affect the rate or extent of substrate consumption? We hypothesized that substrate cross-feeding eliminates competition between different enzymes and reduces the accumulation of growth-inhibiting intermediates, thus accelerating substrate consumption. We tested this hypothesis using isogenic mutants of the bacterium Pseudomonas stutzeri that either completely consume nitrate to dinitrogen gas or cross-feed the intermediate nitrite. We demonstrate that nitrite cross-feeding eliminates inter-enzyme competition and, in turn, reduces nitrite accumulation. We further demonstrate that nitrite cross-feeding accelerates substrate consumption, but only when nitrite has growth-inhibiting effects. Knowledge about inter-enzyme competition and the inhibitory effects of intermediates could therefore be important for deciding how to best segregate different metabolic processes into different microbial cell types to optimize a desired biotransformation.
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Hassan J, Qu Z, Bergaust LL, Bakken LR. Transient Accumulation of NO2- and N2O during Denitrification Explained by Assuming Cell Diversification by Stochastic Transcription of Denitrification Genes. PLoS Comput Biol 2016; 12:e1004621. [PMID: 26731685 PMCID: PMC4701171 DOI: 10.1371/journal.pcbi.1004621] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/22/2015] [Indexed: 11/20/2022] Open
Abstract
Denitrifying bacteria accumulate NO2−, NO, and N2O, the amounts depending on transcriptional regulation of core denitrification genes in response to O2-limiting conditions. The genes include nar, nir, nor and nosZ, encoding NO3−-, NO2−-, NO- and N2O reductase, respectively. We previously constructed a dynamic model to simulate growth and respiration in batch cultures of Paracoccus denitrificans. The observed denitrification kinetics were adequately simulated by assuming a stochastic initiation of nir-transcription in each cell with an extremely low probability (0.5% h-1), leading to product- and substrate-induced transcription of nir and nor, respectively, via NO. Thus, the model predicted cell diversification: after O2 depletion, only a small fraction was able to grow by reducing NO2−. Here we have extended the model to simulate batch cultivation with NO3−, i.e., NO2−, NO, N2O, and N2 kinetics, measured in a novel experiment including frequent measurements of NO2−. Pa. denitrificans reduced practically all NO3− to NO2− before initiating gas production. The NO2− production is adequately simulated by assuming stochastic nar-transcription, as that for nirS, but with a higher probability (0.035 h-1) and initiating at a higher O2 concentration. Our model assumes that all cells express nosZ, thus predicting that a majority of cells have only N2O-reductase (A), while a minority (B) has NO2−-, NO- and N2O-reductase. Population B has a higher cell-specific respiration rate than A because the latter can only use N2O produced by B. Thus, the ratio BA is low immediately after O2 depletion, but increases throughout the anoxic phase because B grows faster than A. As a result, the model predicts initially low but gradually increasing N2O concentration throughout the anoxic phase, as observed. The modelled cell diversification neatly explains the observed denitrification kinetics and transient intermediate accumulations. The result has major implications for understanding the relationship between genotype and phenotype in denitrification research. Denitrifiers generally respire O2, but if O2 becomes limiting, they may switch to anaerobic respiration (denitrification) by producing NO3−-, NO2−-, NO- and/or N2O reductase, encoded by nar, nir, nor, and nosZ genes, respectively. Denitrification causes transient accumulation of NO2− and NO/N2O emissions, depending on the activity of the four reductases. Denitrifiers lacking nosZ produce ~100% N2O, whereas organisms with only nosZ are net consumers of N2O. Full-fledged denitrifiers are equipped with all four reductases, genetic regulation of which determines NO2− accumulation and NO/N2O emissions. Paracoccus denitrificans is a full-fledged denitrifying bacterium, and here we present a modelling approach to understand its gene regulation. We found that the observed transient accumulation of NO2− and N2O can be neatly explained by assuming cell diversification: all cells expressing nosZ, while a minority expressing nar and nir+nor. Thus, the model predicts that in a batch culture of this organism, only a minor sub-population is full-fledged denitrifier. The cell diversification is a plausible outcome of stochastic initiation of nar- and nir transcription, which then becomes autocatalytic by NO2−and NO, respectively. The findings are important for understanding the regulation of denitrification in bacteria: product-induced transcription of denitrification genes is common, and we surmise that diversification in response to anoxia is widespread.
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Affiliation(s)
- Junaid Hassan
- Department of Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway
- * E-mail:
| | - Zhi Qu
- Department of Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Linda L. Bergaust
- Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Lars R. Bakken
- Department of Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway
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Du R, Peng Y, Cao S, Li B, Wang S, Niu M. Mechanisms and microbial structure of partial denitrification with high nitrite accumulation. Appl Microbiol Biotechnol 2015; 100:2011-2021. [DOI: 10.1007/s00253-015-7052-9] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 09/23/2015] [Accepted: 09/29/2015] [Indexed: 10/22/2022]
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Comparative Analysis of Denitrifying Activities of Hyphomicrobium nitrativorans, Hyphomicrobium denitrificans, and Hyphomicrobium zavarzinii. Appl Environ Microbiol 2015; 81:5003-14. [PMID: 25979892 DOI: 10.1128/aem.00848-15] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/12/2015] [Indexed: 12/22/2022] Open
Abstract
Hyphomicrobium spp. are commonly identified as major players in denitrification systems supplied with methanol as a carbon source. However, denitrifying Hyphomicrobium species are poorly characterized, and very few studies have provided information on the genetic and physiological aspects of denitrification in pure cultures of these bacteria. This is a comparative study of three denitrifying Hyphomicrobium species, H. denitrificans ATCC 51888, H. zavarzinii ZV622, and a newly described species, H. nitrativorans NL23, which was isolated from a denitrification system treating seawater. Whole-genome sequence analyses revealed that although they share numerous orthologous genes, these three species differ greatly in their nitrate reductases, with gene clusters encoding a periplasmic nitrate reductase (Nap) in H. nitrativorans, a membrane-bound nitrate reductase (Nar) in H. denitrificans, and one Nap and two Nar enzymes in H. zavarzinii. Concurrently with these differences observed at the genetic level, important differences in the denitrification capacities of these Hyphomicrobium species were determined. H. nitrativorans grew and denitrified at higher nitrate and NaCl concentrations than did the two other species, without significant nitrite accumulation. Significant increases in the relative gene expression levels of the nitrate (napA) and nitrite (nirK) reductase genes were also noted for H. nitrativorans at higher nitrate and NaCl concentrations. Oxygen was also found to be a strong regulator of denitrification gene expression in both H. nitrativorans and H. zavarzinii, although individual genes responded differently in these two species. Taken together, the results presented in this study highlight the potential of H. nitrativorans as an efficient and adaptable bacterium that is able to perform complete denitrification under various conditions.
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Palmer K, Horn MA. Denitrification activity of a remarkably diverse fen denitrifier community in finnish lapland is N-oxide limited. PLoS One 2015; 10:e0123123. [PMID: 25860353 PMCID: PMC4393310 DOI: 10.1371/journal.pone.0123123] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/21/2015] [Indexed: 11/23/2022] Open
Abstract
Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anoxic microcosms, fen soil produced N2O only when acetylene was added to block nitrous oxide reductase, suggesting complete denitrification. Nitrate and nitrite stimulated denitrification in fen soil, and maximal reaction velocities (vmax) of nitrate or nitrite dependent denitrification where 18 and 52 nmol N2O h-1 gDW-1, respectively. N2O was below 30% of total produced N gases in fen soil when concentrations of nitrate and nitrite were <500 μM. vmax for N2O consumption was up to 36 nmol N2O h-1 gDW-1. Denitrifier diversity was assessed by analyses of narG, nirK/nirS, and nosZ (encoding nitrate-, nitrite-, and nitrous oxide reductases, respectively) by barcoded amplicon pyrosequencing. Analyses of ~14,000 quality filtered sequences indicated up to 25 species-level operational taxonomic units (OTUs), and up to 359 OTUs at 97% sequence similarity, suggesting diverse denitrifiers. Phylogenetic analyses revealed clusters distantly related to publicly available sequences, suggesting hitherto unknown denitrifiers. Representatives of species-level OTUs were affiliated with sequences of unknown soil bacteria and Actinobacterial, Alpha-, Beta-, Gamma-, and Delta-Proteobacterial sequences. Comparison of the 4 gene markers at 97% similarity indicated a higher diversity of narG than for the other gene markers based on Shannon indices and observed number of OTUs. The collective data indicate (i) a high denitrification and N2O consumption potential, and (ii) a highly diverse, nitrate limited denitrifier community associated with potential N2O fluxes in a pH-neutral fen soil.
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Affiliation(s)
- Katharina Palmer
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Marcus A. Horn
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
- * E-mail:
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56
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A network biology approach to denitrification in Pseudomonas aeruginosa. PLoS One 2015; 10:e0118235. [PMID: 25706405 PMCID: PMC4338189 DOI: 10.1371/journal.pone.0118235] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 01/11/2015] [Indexed: 11/26/2022] Open
Abstract
Pseudomonas aeruginosa is a metabolically flexible member of the Gammaproteobacteria. Under anaerobic conditions and the presence of nitrate, P. aeruginosa can perform (complete) denitrification, a respiratory process of dissimilatory nitrate reduction to nitrogen gas via nitrite (NO2), nitric oxide (NO) and nitrous oxide (N2O). This study focuses on understanding the influence of environmental conditions on bacterial denitrification performance, using a mathematical model of a metabolic network in P. aeruginosa. To our knowledge, this is the first mathematical model of denitrification for this bacterium. Analysis of the long-term behavior of the network under changing concentration levels of oxygen (O2), nitrate (NO3), and phosphate (PO4) suggests that PO4 concentration strongly affects denitrification performance. The model provides three predictions on denitrification activity of P. aeruginosa under various environmental conditions, and these predictions are either experimentally validated or supported by pertinent biological literature. One motivation for this study is to capture the effect of PO4 on a denitrification metabolic network of P. aeruginosa in order to shed light on mechanisms for greenhouse gas N2O accumulation during seasonal oxygen depletion in aquatic environments such as Lake Erie (Laurentian Great Lakes, USA). Simulating the microbial production of greenhouse gases in anaerobic aquatic systems such as Lake Erie allows a deeper understanding of the contributing environmental effects that will inform studies on, and remediation strategies for, other hypoxic sites worldwide.
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Ponsin V, Mouloubou OR, Prudent P, Höhener P. Does phosphate enhance the natural attenuation of crude oil in groundwater under defined redox conditions? JOURNAL OF CONTAMINANT HYDROLOGY 2014; 169:4-18. [PMID: 24795042 DOI: 10.1016/j.jconhyd.2014.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/11/2014] [Accepted: 04/09/2014] [Indexed: 06/03/2023]
Abstract
After a crude oil spill caused by a broken pipeline in 2009 to a gravel aquifer in southern France, degradation processes under various redox conditions progressively established, but at rates that predict a long life-time of the source under natural attenuation after partial source removal. In this study, we aimed at identifying the rate-limiting factors for each redox condition, with special emphasis on phosphate as limiting nutrient. The study was conducted in laboratory microcosms assembled with material collected on site: sediments, water from monitoring wells, oil and microbial sludge. Redox conditions were promoted by adding electron acceptors (either oxygen, nitrate, limonite (FeO(OH)), cryptomelane (K(Mn(4+),Mn(2+))8O16), or sulfate). For each condition, the role of phosphate was studied by repeated additions for up to 290days. The results showed a very strong stimulation of aerobic and denitrifying rates of oil degradation by phosphate, provided that oxygen and nitrate were repeatedly supplied. Phosphate caused also a marked stimulation of methanogenic degradation, and a relatively small stimulation of metal reduction. These anaerobic processes started only after marked lag phases, and phosphate shortened the lag phase for methanogenic degradation. Degradation of aromatic and aliphatic hydrocarbons with less than 8 carbons, including benzene, was confirmed even under unstimulated conditions. It is concluded that degradation rates at the site are limited by both, availability of electron acceptors and availability of phosphate needed for promoting microbial growth.
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Affiliation(s)
- Violaine Ponsin
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France; French Environment and Energy Management Agency, 20 avenue de Grésillé-BP 90406 Angers Cedex 01, France
| | | | - Pascale Prudent
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France
| | - Patrick Höhener
- Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement, FRE 3416 Marseille, France.
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Vidal-Gavilan G, Carrey R, Solanas A, Soler A. Feeding strategies for groundwater enhanced biodenitrification in an alluvial aquifer: chemical, microbial and isotope assessment of a 1D flow-through experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 494-495:241-251. [PMID: 25051326 DOI: 10.1016/j.scitotenv.2014.06.100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/21/2014] [Accepted: 06/23/2014] [Indexed: 06/03/2023]
Abstract
Nitrate-removal through enhanced in situ biodenitrification (EISB) is an existing alternative for the recovery of groundwater quality, and is often suggested for use in exploitation wells pumping at small flow-rates. Innovative approaches focus on wider-scale applications, coupling EISB with water-management practices and new monitoring tools. However, before this approach can be used, some water-quality issues such as the accumulation of denitrification intermediates and/or of reduced compounds from other anaerobic processes must be addressed. With such a goal, a flow-through experiment using 100mg-nitrate/L groundwater was built to simulate an EISB for an alluvial aquifer. Heterotrophic denitrification was induced through the periodic addition of a C source (ethanol), with four different C addition strategies being evaluated to improve the quality of the denitrified water. Chemical, microbial and isotope analyses of the water were performed. Biodenitrification was successfully stimulated by the daily addition of ethanol, easily achieving drinking water standards for both nitrate and nitrite, and showing an expected linear trend for nitrogen and oxygen isotope fractionation, with a εN/εO value of 1.1. Nitrate reduction to ammonium was never detected. Water quality in terms of remaining C, microbial counts, and denitrification intermediates was found to vary with the experimental time, and some secondary microbial respiration processes, mainly manganese reduction, were suspected to occur. Carbon isotope composition from the remaining ethanol also changed, from an initial enrichment in (13)C-ethanol compared to the value of the injected ethanol (-30.6‰), to a later depletion, achieving δ(13)C values well below the initial isotope composition (to a minimum of -46.7‰). This depletion in the heavy C isotope follows the trend of an inverse fractionation. Overall, our results indicated that most undesired effects on water quality may be controlled through the optimization of the C/N ratio determined from the amounts of injected ethanol vs. the amount of nitrate in groundwater, with a smaller C/N ratio causing a lower level of undesired impurities. Furthermore, the authors suggest that the biofilm life-time has a direct effect on microbial population and hence affects biodenitrification performance, influencing the accumulation of nitrite over time.
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Affiliation(s)
- G Vidal-Gavilan
- D D'ENGINY BIOREM S.L., Madrazo 68, bxs., 08006 Barcelona, Spain; Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal·lografia, Mineralogia i Dipòsits MInerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain.
| | - R Carrey
- Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal·lografia, Mineralogia i Dipòsits MInerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain.
| | - A Solanas
- Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain.
| | - A Soler
- Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal·lografia, Mineralogia i Dipòsits MInerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain.
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59
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Lotti T, Kleerebezem R, Lubello C, van Loosdrecht MCM. Physiological and kinetic characterization of a suspended cell anammox culture. WATER RESEARCH 2014; 60:1-14. [PMID: 24813505 DOI: 10.1016/j.watres.2014.04.017] [Citation(s) in RCA: 246] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/05/2014] [Accepted: 04/07/2014] [Indexed: 05/21/2023]
Abstract
Anammox related technologies are currently widely applied for nitrogen removal from sewage sludge digester rejection water. Nevertheless, many aspects of the anammox process like the kinetic characteristics and the reaction stoichiometry are still subject of debate. Parameter values reported in literature are often hampered by mass transfer limitation or by the presence of a significant side population. In this study a membrane bioreactor (MBR) based method for growing a highly enriched anammox microbial community is described. The almost pure free-cells suspension of highly active anammox bacteria was used for detailed kinetic and stoichiometric analysis of the anammox process. The anammox culture enriched during this study had a biomass specific maximum growth rate of 0.21 d(-)(1) which is higher than ever reported before in literature. Using an experimental methodology based on imposing dynamic process conditions combined with process modeling and parameter estimation, the intrinsic nitrite half saturation constant was identified to be as low as 35 μg-N L(-)(1). This was confirmed to be an accurate estimation in the pH range of 6.8-7.5.
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Affiliation(s)
- T Lotti
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, the Netherlands.
| | - R Kleerebezem
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, the Netherlands
| | - C Lubello
- Department of Civil and Environmental Engineering, University of Florence, Via di S.Marta 3, 50139 Florence, Italy
| | - M C M van Loosdrecht
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, the Netherlands.
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Holzem RM, Stapleton HM, Gunsch CK. Determining the ecological impacts of organic contaminants in biosolids using a high-throughput colorimetric denitrification assay: a case study with antimicrobial agents. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:1646-1655. [PMID: 24410196 DOI: 10.1021/es404431k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Land application accounts for ∼ 50% of wastewater solid disposal in the United States. Still, little is known regarding the ecological impacts of nonregulated contaminants found in biosolids. Because of the myriad of contaminants, there is a need for a rapid, high-throughput method to evaluate their ecotoxicity. Herein, we developed a novel assay that measures denitrification inhibition in a model denitrifier, Paracoccus denitrificans Pd1222. Two common (triclosan and triclocarban) and four emerging (2,4,5 trichlorophenol, 2-benzyl-4-chlorophenol, 2-chloro-4-phenylphenol, and bis(5-chloro-2-hydroxyphenyl)methane) antimicrobial agents found in biosolids were analyzed. Overall, the assay was reproducible and measured impacts on denitrification over 3 orders of magnitude exposure. The lowest observable adverse effect concentrations (LOAECs) were 1.04 μM for triclosan, 3.17 μM for triclocarban, 0.372 μM for bis-(5-chloro-2-hydroxyphenyl)methane, 4.89 μM for 2-chloro-4-phenyl phenol, 45.7 μM for 2-benzyl-4-chorophenol, and 50.6 μM for 2,4,5-trichlorophenol. Compared with gene expression and cell viability based methods, the denitrification assay was more sensitive and resulted in lower LOAECs. The increased sensitivity, low cost, and high-throughput adaptability make this method an attractive alternative for meeting the initial testing regulatory framework for the Federal Insecticide, Fungicide, and Rodenticide Act, and recommended for the Toxic Substances Control Act, in determining the ecotoxicity of biosolids-derived emerging contaminants.
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Affiliation(s)
- R M Holzem
- Department of Civil and Environmental Engineering, Duke University , Durham, North Carolina 27708, United States
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Hu BL, Shen LD, Zheng P, Hu AH, Chen TT, Cai C, Liu S, Lou LP. Distribution and diversity of anaerobic ammonium-oxidizing bacteria in the sediments of the Qiantang River. ENVIRONMENTAL MICROBIOLOGY REPORTS 2012; 4:540-547. [PMID: 23760899 DOI: 10.1111/j.1758-2229.2012.00360.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Anaerobic ammonium oxidation (anammox) is an important process in the marine nitrogen cycle. However, little is known about the distribution, diversity and abundance of anammox bacteria in inland river ecosystems. Here, we found the presence of diverse anammox bacteria in a freshwater river - the Qiantang River, Zhejiang Province (China). The phylogenetic analysis of 16S rRNA genes showed that Brocadia genus, Kuenenia genus, Scalindua genus and three new anammox bacterial clusters could be detected together in Qiantang River sediments, suggesting a higher anammox bacterial diversity in the Qiantang River ecosystem than in open ocean environments where only Scalindua genus was detected. Brocadia and Kuenenia appeared to be the most common anammox bacterial genera in the Qiantang River. Redundancy analysis showed that the sediment organic carbon (OrgC) content had significant influence on the distribution of anammox bacteria in Qiantang River sediments. Pearson correlation analyses showed that OrgC content significantly influenced the anammox bacterial diversity. The results of real-time quantitative PCR showed spatial variations of anammox bacterial abundances which were highly correlated with the sediment total inorganic nitrogen content. These results demonstrated the distribution of diverse anammox bacteria and the influences of environmental factors on anammox bacterial communities in Qiantang River sediments.
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Affiliation(s)
- Bao-Lan Hu
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China
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62
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Pan Y, Ye L, Ni BJ, Yuan Z. Effect of pH on N₂O reduction and accumulation during denitrification by methanol utilizing denitrifiers. WATER RESEARCH 2012; 46:4832-4840. [PMID: 22749904 DOI: 10.1016/j.watres.2012.06.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 06/05/2012] [Indexed: 05/27/2023]
Abstract
Acidic pH has previously been found to increase nitrous oxide (N₂O) accumulation during heterotrophic denitrification in biological wastewater treatment. However, the mechanism of this phenomenon still needs to be clarified. By using an enriched methanol utilizing denitrifying culture as an example, this paper presents a comprehensive study on the effect of pH (6.0-9.0) on N₂O reduction kinetics with N₂O as the sole electron acceptor, as well as the effect of pH on N₂O accumulation with N₂O as an intermediate of nitrate reduction. The pH dependency of nitrate and nitrite reduction was also investigated. The maximum biomass-specificN₂O reduction rate is higher than the corresponding maximum nitrate and nitrite reduction rates in the entire pH range studied. However, the maximum biomass-specific N₂O reduction rate is much more sensitive to pH variation outside of the optimal range (pH 7.5 to pH 8.0) than the maximum biomass-specific nitrate and nitrite reduction rates. The half-saturation coefficient of the N₂O reductase increased from 0.10 mg N₂O-N/L to 0.92 mg N₂O-N/L as pH increased from pH 6.0 to 9.0. At pH 6.0, approximately 20% and 40% of the denitrified nitrate accumulated as N₂O in the presence and absence of methanol (as an exogenous carbon source), respectively. However, at pH 6.5, these fractions decreased to 0% and 30%, respectively. No N₂O accumulation occurred at pH 7.0 to 9.0 independent of the availability of methanol. These results suggest that the competition for electrons among different nitrogen oxides reductases likely plays a role in N₂O accumulation at low pH conditions.
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Affiliation(s)
- Yuting Pan
- Advanced Water Management Centre-AWMC, The University of Queensland, Gehrmann Building 60, Research Road, St Lucia, Brisbane, QLD 4072, Australia
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Mangimbulude JC, van Straalen NM, Röling WFM. Microbial nitrogen transformation potential in surface run-off leachate from a tropical landfill. WASTE MANAGEMENT (NEW YORK, N.Y.) 2012; 32:77-87. [PMID: 21880479 DOI: 10.1016/j.wasman.2011.07.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 07/21/2011] [Accepted: 07/28/2011] [Indexed: 05/31/2023]
Abstract
Ammonium is one of the major toxic compounds and a critical long-term pollutant in landfill leachate. Leachate from the Jatibarang landfill in Semarang, Indonesia, contains ammonium in concentrations ranging from 376 to 929mgNL(-1). The objective of this study was to determine seasonal variation in the potential for organic nitrogen ammonification, aerobic nitrification, anaerobic nitrate reduction and anaerobic ammonium oxidation (anammox) at this landfilling site. Seasonal samples from leachate collection treatment ponds were used as an inoculum to feed synthetic media to determine potential rates of nitrogen transformations. Aerobic ammonium oxidation potential (<0.06mgNL(-1)h(-1)) was more than a hundred times lower than the anaerobic nitrogen transformation processes and organic nitrogen ammonification, which were of the same order of magnitude. Anaerobic nitrate oxidation did not proceed beyond nitrite; isolates grown with nitrate as electron acceptor did not degrade nitrite further. Effects of season were only observed for aerobic nitrification and anammox, and were relatively minor: rates were up to three times higher in the dry season. To completely remove the excess ammonium from the leachate, we propose a two-stage treatment system to be implemented. Aeration in the first leachate pond would strongly contribute to aerobic ammonium oxidation to nitrate by providing the currently missing oxygen in the anaerobic leachate and allowing for the growth of ammonium oxidisers. In the second pond the remaining ammonium and produced nitrate can be converted by a combination of nitrate reduction to nitrite and anammox. Such optimization of microbial nitrogen transformations can contribute to alleviating the ammonium discharge to surface water draining the landfill.
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Affiliation(s)
- Jubhar C Mangimbulude
- Faculty of Biology, Universitas Kristen Satya Wacana, Jl Diponegoro 52-60, Salatiga 50711, Indonesia
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Zhou Y, Oehmen A, Lim M, Vadivelu V, Ng WJ. The role of nitrite and free nitrous acid (FNA) in wastewater treatment plants. WATER RESEARCH 2011; 45:4672-82. [PMID: 21762944 DOI: 10.1016/j.watres.2011.06.025] [Citation(s) in RCA: 237] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/17/2011] [Accepted: 06/21/2011] [Indexed: 05/06/2023]
Abstract
Nitrite is known to accumulate in wastewater treatment plants (WWTPs) under certain environmental conditions. The protonated form of nitrite, free nitrous acid (FNA), has been found to cause severe inhibition to numerous bioprocesses at WWTPs. However, this inhibitory effect of FNA may possibly be gainfully exploited, such as repressing nitrite oxidizing bacteria (NOB) growth to achieve N removal via the nitrite shortcut. However, the inhibition threshold of FNA to repress NOB (∼0.02 mg HNO2-N/L) may also inhibit other bioprocesses. This paper reviews the inhibitory effects of FNA on nitrifiers, denitrifiers, anammox bacteria, phosphorus accumulating organisms (PAO), methanogens, and other microorganisms in populations used in WWTPs. The possible inhibition mechanisms of FNA on microorganisms are discussed and compared. It is concluded that a single inhibition mechanism is not sufficient to explain the negative impacts of FNA on microbial metabolisms and that multiple inhibitory effects can be generated from FNA. The review would suggest further research is necessary before the FNA inhibition mechanisms can be more effectively used to optimize WWTP bioprocesses. Perspectives on research directions, how the outcomes may be used to manipulate bioprocesses and the overall implications of FNA on WWTPs are also discussed.
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Affiliation(s)
- Yan Zhou
- Advanced Environmental Biotechnology Centre (AEBC), Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, School of Biological Science, Level N-B2-01, 60 Nanyang Avenue, Singapore 639798, Singapore.
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65
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Jin Q, Roden EE. Microbial physiology-based model of ethanol metabolism in subsurface sediments. JOURNAL OF CONTAMINANT HYDROLOGY 2011; 125:1-12. [PMID: 21652106 DOI: 10.1016/j.jconhyd.2011.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/11/2011] [Accepted: 04/14/2011] [Indexed: 05/30/2023]
Abstract
A biogeochemical reaction model was developed based on microbial physiology to simulate ethanol metabolism and its influence on the chemistry of anoxic subsurface environments. The model accounts for potential microbial metabolisms that degrade ethanol, including those that oxidize ethanol directly or syntrophically by reducing different electron acceptors. Out of the potential metabolisms, those that are active in the environment can be inferred by fitting the model to experimental observations. This approach was applied to a batch sediment slurry experiment that examined ethanol metabolism in uranium-contaminated aquifer sediments from Area 2 at the U.S. Department of Energy Field Research Center in Oak Ridge, TN. According to the simulation results, complete ethanol oxidation by denitrification, incomplete ethanol oxidation by ferric iron reduction, ethanol fermentation to acetate and H(2), hydrogenotrophic sulfate reduction, and acetoclastic methanogenesis: all contributed significantly to the degradation of ethanol in the aquifer sediments. The assemblage of the active metabolisms provides a frame work to explore how ethanol amendment impacts the chemistry of the environment, including the occurrence and levels of uranium. The results can also be applied to explore how diverse microbial metabolisms impact the progress and efficacy of bioremediation strategies.
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Affiliation(s)
- Qusheng Jin
- Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA.
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66
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Comparison of Denitrification Between Paracoccus sp. and Diaphorobacter sp. Appl Biochem Biotechnol 2011; 165:260-9. [DOI: 10.1007/s12010-011-9248-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 04/04/2011] [Indexed: 10/18/2022]
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67
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Vacková L, Srb M, Stloukal R, Wanner J. Comparison of denitrification at low temperature using encapsulated Paracoccus denitrificans, Pseudomonas fluorescens and mixed culture. BIORESOURCE TECHNOLOGY 2011; 102:4661-4666. [PMID: 21306891 DOI: 10.1016/j.biortech.2011.01.024] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 01/06/2011] [Accepted: 01/11/2011] [Indexed: 05/30/2023]
Abstract
The aim of this work was to compare denitrification activity of three types of encapsulated biomass containing pure culture of Paracoccus denitrificans or Pseudomonas fluorescens or mixed culture of psychrophilic denitrifiers cultivated at 5 °C from activated sludge. The experiments were held with synthetic wastewater containing 50 mg L(-1) N-NO(3)(-) under the temperature 15, 10, 8 and 5 °C. Specific denitrification rates related to the weight of pellets and to the protein content were calculated and the temperature coefficients describing the dependence of denitrification rate on the temperature were determined. Although the mixed culture showed the highest denitrification rate at the temperatures below 10 °C, using of pellets containing pure culture is recommended as the mixed culture has slow growth rate and its activity at temperatures above 10 °C is very low.
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Affiliation(s)
- Lenka Vacková
- Institute of Chemical Technology Prague, Faculty of Environmental Technology, Department of Water Technology and Environmental Engineering, Technická 5, 166 28 Praha 6, Czech Republic.
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68
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Xie WM, Ni BJ, Zeng RJ, Sheng GP, Yu HQ, Song J, Le DZ, Bi XJ, Liu CQ, Yang M. Formation of soluble microbial products by activated sludge under anoxic conditions. Appl Microbiol Biotechnol 2010; 87:373-82. [DOI: 10.1007/s00253-010-2563-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Revised: 03/09/2010] [Accepted: 03/14/2010] [Indexed: 11/30/2022]
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69
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Ma J, Yang Q, Wang S, Wang L, Takigawa A, Peng Y. Effect of free nitrous acid as inhibitors on nitrate reduction by a biological nutrient removal sludge. JOURNAL OF HAZARDOUS MATERIALS 2010; 175:518-523. [PMID: 19910113 DOI: 10.1016/j.jhazmat.2009.10.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 09/13/2009] [Accepted: 10/10/2009] [Indexed: 05/28/2023]
Abstract
Nitrite has been commonly thought to have a broad inhibitory effect on bacterial metabolism. Little is known about the impact of nitrite on nitrate reduction with pH considered as an important factor. This study investigates the nitrite inhibition on nitrate reduction during denitrification under various pH conditions by using a biological nutrient removal (BNR) sludge. The results showed that nitrate reduction performance had a much stronger relationship with the free nitrous acid (FNA) than that of nitrite concentration, implying that FNA, rather than nitrite, is likely the real inhibitor on nitrate reduction. The nitrate reduction activity of the biomass was observed to be inhibited about 60% in the range of 0.01-0.025 mg HNO(2)-N/L and was totally inhibited when FNA level was greater than the threshold concentration (0.2mg HNO(2)-N/L). Moreover, the recovery rate from inhibitory effect was found to be dependent much more strongly on the concentration of FNA, of which the biomass was exposed to during the inhibition period, than on the duration of the inhibition and the feeding mode of inhibitor. It was also found that nitrite reduction was significantly inhibited by FNA and the nitrite reduction rate was linear to nitrate reduction rate due to the inhibitory mechanism under which FNA may react with the enzymes involved in the denitrification process.
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Affiliation(s)
- Juan Ma
- Key Laboratory of Beijing Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China
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70
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Elmén J, Pan W, Leung SY, Magyarosy A, Keasling JD. Kinetics of toluene degradation by a nitrate-reducing bacterium isolated from a groundwater aquifer. Biotechnol Bioeng 2009; 55:82-90. [PMID: 18636447 DOI: 10.1002/(sici)1097-0290(19970705)55:1<82::aid-bit10>3.0.co;2-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Groundwater from a xylene-contaminated acquifer was enriched in the laboratory in the presence of toluene, xylenes, ethylbenzene, and benzene. A pure culture that degrades toluene and m-xylene under nitrate-reducing conditions was isolated. Fatty acid analysis, 16S rRNA sequencing, and morphological traits indicate that the isolate was a strain of Azoarcus tolulyticus. The kinetics of toluene degradation under nitrate-reducing conditions by this isolate was determined. Nitrate reduction does not proceed beyond nitrite. Nitrate and toluene are substrate limiting at low concentrations, whereas toluene, nitrate, and nitrite are inhibitory at high concentrations. Several inhibition models were compared to experimental data to represent inhibition by these substrates. A kinetic model for toluene and nitrate degradation as well as for cell growth and nitrite production was developed and compared to experimental data. The results of this work may find important application in the remediation of groundwater aquifers contaminated with aromatic hydrocarbons.
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Affiliation(s)
- J Elmén
- Department of Chemical Engineering, University of California, Berkeley, California 94720-1462, USA
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71
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Enhanced biological denitrification of high concentration of nitrite with supplementary carbon source. Appl Microbiol Biotechnol 2009; 85:773-8. [DOI: 10.1007/s00253-009-2265-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/12/2009] [Accepted: 09/14/2009] [Indexed: 10/20/2022]
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72
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Sulfide persistence in oil field waters amended with nitrate and acetate. J Ind Microbiol Biotechnol 2009; 36:1499-511. [PMID: 19789900 DOI: 10.1007/s10295-009-0639-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Accepted: 09/09/2009] [Indexed: 10/20/2022]
Abstract
Nitrate amendment is normally an effective method for sulfide control in oil field-produced waters. However, this approach has occasionally failed to prevent sulfide accumulation, despite the presence of active nitrate-reducing bacterial populations. Here, we report our study of bulk chemical transformations in microcosms of oil field waters containing nitrate-reducing, sulfide-oxidizing bacteria, but lacking denitrifying heterotrophs. Amendment with combinations of nitrate, acetate, and phosphate altered the microbial sulfur and nitrogen transformations. Elemental sulfur produced by chemotrophic nitrate-reducing bacteria was re-reduced heterotrophically to sulfide. Ammonification, rather than denitrification, was the predominant pathway for nitrate reduction. The application of nitrite led to transient sulfide depletion, possibly due to higher rates of nitrite reduction. The addition of molybdate suppressed both the accumulation of sulfide and the heterotrophic reduction of nitrate. Therefore, sulfidogenesis was likely due to elemental sulfur-reducing heterotrophic bacteria, and the nitrate-reducing microbial community consisted mainly of facultatively chemotrophic microbes. This study describes one set of conditions for continued sulfidogenesis during nitrate reduction, with important implications for nitrate control of sulfide production in oil fields.
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73
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Fu Z, Yang F, An Y, Xue Y. Characteristics of nitrite and nitrate in situ denitrification in landfill bioreactors. BIORESOURCE TECHNOLOGY 2009; 100:3015-3021. [PMID: 19231168 DOI: 10.1016/j.biortech.2008.12.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/15/2008] [Accepted: 12/16/2008] [Indexed: 05/27/2023]
Abstract
The objective of this research was to investigate the macroscopical effect of high concentration nitrite and nitrate denitrification on waste decomposition and to evaluate the kinetics of NO(3)(-)-N and NO(2)(-)-N removal. Two reactors loaded fresh refuse were fed 4000 mg NO(3)(-)-N/L or 4000 NO(2)(-)-N/L every 48 h, respectively. Results showed that NO(3)(-)-N addition was more effective on promotion of the waste degradation process as compared to NO(2)(-)-N addition. In the initial stage, NO(x)(-)-N removal was mainly contributed by adsorption rather than denitrification. NO(x)(-)-N reduction rate data obtained from microcosm experiment were fit to Monod kinetics, with specific removal rates of 1.625 mg NO(3)(-)-N/(g dry waste d) and 1.125 mg NO(2)(-)-N/(g dry waste d) and nitrogen removal half-saturation constants of 1250.5 NO(3)(-)-N/L and 125.5 NO(2)(-)-N/L, respectively.
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Affiliation(s)
- Zhimin Fu
- Key Laboratory of Industrial Ecology and Environmental Engineering, MOE, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, PR China
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74
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Ghafari S, Hasan M, Aroua MK. Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria. JOURNAL OF HAZARDOUS MATERIALS 2009; 162:1507-1513. [PMID: 18639979 DOI: 10.1016/j.jhazmat.2008.06.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 06/12/2008] [Accepted: 06/12/2008] [Indexed: 05/26/2023]
Abstract
Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO(2) and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO(2), (II) bicarbonate plus continuous sparging of CO(2), and (III) only bicarbonate. The pH-reducing nature of CO(2) showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO(3)(-)-N/g MLVSS/h for degrading 20 and 30 mg NO(3)(-)-N/L and 9.09 mg NO(3)(-)-N/g MLVSS/h for degrading 50mg NO(3)(-)-N/L.
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Affiliation(s)
- Shahin Ghafari
- Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
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75
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Li YM, Li J, Zheng GH, Luan JF, Fu QS, Gu GW. Effects of the COD/NO3(-)-N ratio and pH on the accumulation of denitrification intermediates with available pyridine as a sole electron donor and carbon source. ENVIRONMENTAL TECHNOLOGY 2008; 29:1297-1306. [PMID: 19149351 DOI: 10.1080/09593330802379672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Batch experiments were conducted to investigate the effects of COD/NO3(-)-N ratio and pH on the accumulation of the denitrification intermediates - nitrite and nitrous oxide - with pyridine as the sole electron donor and carbon source. Significant transient accumulation of nitrite was observed at COD/NO3(-)-N ratios in the range of 2-13 and pH in the range of 6.5-9.5. The optimal pH was 7.5 and the minimum COD/NO3(-)-N ratio was 4 for complete denitrification. The pH had a significant effect on denitrification. At a lower pH of 6.5, the reaction was severely inhibited whereas at a higher pH of 8.5 and 9.5, nitrate was completely reduced, but a high concentration of nitrite remained in the reactors while pyridine was almost completely degraded after one hour, even at the COD/NO3(-)-N ratio of 4. While the specific nitrate reduction rate and nitrite reduction rate in the absence of nitrate remained constant at different COD/NO3(-)-N ratios, they increased with the increase in pH. The nitrite reduction was inhibited in the presence of nitrate because of the faster rate of nitrate reduction over nitrite reduction. Nitrous oxide accumulation was also observed with a COD/NO3(-)-N ratio below 3 in the pH range of 7.5-8.5. At a COD/NO3(-)-N ratio of 4 and pH of 6, the production of nitrous oxide was much higher than that at pH 7 and 8.
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Affiliation(s)
- Y-M Li
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
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76
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Morgan-Sagastume F, Nielsen JL, Nielsen PH. Substrate-dependent denitrification of abundant probe-defined denitrifying bacteria in activated sludge. FEMS Microbiol Ecol 2008; 66:447-61. [DOI: 10.1111/j.1574-6941.2008.00571.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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77
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van der Star WR, Miclea AI, van Dongen UG, Muyzer G, Picioreanu C, van Loosdrecht MC. The membrane bioreactor: A novel tool to grow anammox bacteria as free cells. Biotechnol Bioeng 2008; 101:286-94. [DOI: 10.1002/bit.21891] [Citation(s) in RCA: 369] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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78
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Huiliñir C, Martí MC, Aspé E, Roeckel M. Organic and nitrogenous matter effects on the denitrification of saline and protein-rich effluents. ENVIRONMENTAL TECHNOLOGY 2008; 29:881-890. [PMID: 18724643 DOI: 10.1080/09593330802015466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The separate effect of protein concentration, nitrate concentration and carbon/nitrogen (C/N) ratio on the rate and efficiency of nitrate reduction was studied in batch reactors fed with a mixture of a synthetic substrate and a saline protein-rich salmon-plant effluent. At a constant nitrate concentration (40 mg L(-1)), the specific rate of nitrate removal decreased by 60% with increasing initial protein concentration (392 to 1900 mg L(-1)) and ammonification prevailed under these conditions; meanwhile at a constant protein concentration (1104 mg L(-1)), the specific rate of nitrate removal increased 58 times with increasing nitrate concentrations (0.5 to 78 mg L(-1)) and denitrification was the main route for nitrate reduction. The C/N ratio had an inverse effect on the specific rate of denitrification; the latter ranged from 227 to 563 [mg NO3(-)-N (g VSS d)(-1)] for a C/N ratio of 163 to 16 [mg TOC (total organic carbon) (mg NO3(-)-N)(-1)], respectively. On the other hand, the ammonia production rate was proportional up to a C/N ratio of 150.
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Affiliation(s)
- C Huiliñir
- Departamento de Ingeniería Química, Fac. de Ingeniería, Universidad de Concepción, Concepción, Chile
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79
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Alinsafi A, Adouani N, Béline F, Lendormi T, Limousy L, Sire O. Nitrite effect on nitrous oxide emission from denitrifying activated sludge. Process Biochem 2008. [DOI: 10.1016/j.procbio.2008.02.008] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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80
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Mahmood Q, Zheng P, Hayat Y, Islam E, Wu D, Ren-cun J. Effect of pH on anoxic sulfide oxidizing reactor performance. BIORESOURCE TECHNOLOGY 2008; 99:3291-6. [PMID: 17702569 DOI: 10.1016/j.biortech.2007.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 07/02/2007] [Accepted: 07/03/2007] [Indexed: 05/16/2023]
Abstract
The effects of pH on the performance of anoxic sulfide oxidizing (ASO) reactor were evaluated. Performance was investigated under various operational conditions at influent pH range of 4-11. At the influent pH of 7-7.5 during loading tests and HRT tests, the sulfide oxidation was partial. In general, the amount of sulfate formed decreased with the increasing sulfide and nitrite loadings. The bacterial communities in ASO reactors were more sensitive to acidic pH compared with alkaline pH, as nitrite and sulfide removal rates dropped significantly when exposed to acidic pH 3. High dissolved bisulfide ions, nitrite and excess of sulfate (>300 mg/L) might have inhibited the sulfide oxidation under highly acidic and alkaline conditions in the ASO reactor. Based on sulfide and nitrite removal efficiencies, the ASO reactor can be operated in a wide range of pH, i.e. 5-11.
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Affiliation(s)
- Qaisar Mahmood
- Department of Environmental Engineering, Zhejiang University, Hangzhou 310029, China
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81
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82
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83
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Carvalho G, Lemos PC, Oehmen A, Reis MAM. Denitrifying phosphorus removal: linking the process performance with the microbial community structure. WATER RESEARCH 2007; 41:4383-96. [PMID: 17669460 DOI: 10.1016/j.watres.2007.06.065] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 06/26/2007] [Accepted: 06/29/2007] [Indexed: 05/16/2023]
Abstract
This study investigated the link between the process performance of two denitrifying phosphorus (P) removal systems and their microbial community structure. Two sequencing batch reactors (SBRs) were operated with either acetate or propionate as the sole carbon source, and were gradually acclimatised from anaerobic-aerobic to anaerobic-anoxic conditions. It was found that the propionate SBR was able to sustain denitrifying P removal after acclimatisation, while the enhanced biological phosphorus removal (EBPR) activity in the acetate reactor collapsed after the aerobic phase was eliminated. The results suggested that the anoxic glycogen production rate in the acetate SBR was insufficient to support the anaerobic glycogen demand for acetate uptake. The chemical transformations in each SBR suggested that different types of polyphosphate-accumulating organisms (PAOs) were present in each system, possessing different affinities for nitrate. Microbial characterisation with fluorescence in situ hybridisation (FISH) revealed that Accumulibacter was the dominant organism in each reactor, although different cell morphotypes were observed. A coccus morphotype was predominant in the acetate SBR while the propionate SBR was enriched in a rod morphotype. It is hypothesised that the coccus morphotype corresponds to an Accumulibacter strain that is unable to use nitrate as electron acceptor but is able to use oxygen, and possibly nitrite. The rod morphotype is proposed to be a PAO able to use nitrate, nitrite and oxygen. This hypothesis is in agreement with literature studies focussed on the identity of denitrifying PAOs (DPAOs), as well as a recent metagenomic study on Accumulibacter.
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Affiliation(s)
- Gilda Carvalho
- REQUIMTE/CQFB, Chemistry Department, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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84
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Nitrate removal with bacterial cells attached to quartz sand and zeolite from salty wastewaters. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9405-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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85
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Soto O, Aspé E, Roeckel M. Kinetics of cross-inhibited denitrification of a high load wastewater. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2006.11.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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86
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Ni BJ, Yu HQ. Storage and growth of denitrifiers in aerobic granules: Part I. model development. Biotechnol Bioeng 2007; 99:314-23. [PMID: 17614332 DOI: 10.1002/bit.21555] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A mathematical model, based on the Activated Sludge Model No.3 (ASM3), is developed to describe the storage and growth activities of denitrifiers in aerobic granules under anoxic conditions. In this model, mass transfer, hydrolysis, simultaneous anoxic storage and growth, anoxic maintenance, and endogenous decay are all taken into account. The model established is implemented in the well-established AQUASIM simulation software. A combination of completely mixed reactor and biofilm reactor compartments provided by AQUASIM is used to simulate the mass transport and conversion processes occurring in both bulk liquid and granules. The modeling results explicitly show that the external substrate is immediately utilized for storage and growth at feast phase. More external substrates are diverted to storage process than the primary biomass production process. The model simulation indicates that the nitrate utilization rate (NUR) of granules-based denitrification process includes four linear phases of nitrate reduction. Furthermore, the methodology for determining the most important parameter in this model, that is, anoxic reduction factor, is established.
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Affiliation(s)
- Bing-Jie Ni
- Laboratory of Environmental Biotechnology, School of Chemistry, University of Science & Technology of China, Hefei 230026, China
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87
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Ni BJ, Yu HQ, Xie WM. Storage and growth of denitrifiers in aerobic granules: Part II. model calibration and verification. Biotechnol Bioeng 2007; 99:324-32. [PMID: 17614331 DOI: 10.1002/bit.21554] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A mathematical model to describe the simultaneous storage and growth activities of denitrifiers in aerobic granules under anoxic conditions has been developed in an accompanying article. The sensitivity of the nitrate uptake rate (NUR) toward the stoichiometric and kinetic coefficients is analyzed in this article. The model parameter values are estimated by minimizing the sum of squares of the deviations between the measured and model-predicted values. The model is successfully calibrated and a set of stoichiometric and kinetic parameters for the anoxic storage and growth of the denitrifiers are obtained. Thereafter, the model established is verified with three set of experimental data. The comparison between the model established with the ASM1 model and ASM3 shows that the present model is appropriate to simulate and predict the performance of a granule-based denitrification system.
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Affiliation(s)
- Bing-Jie Ni
- Laboratory of Environmental Biotechnology, School of Chemistry, University of Science & Technology of China, Hefei 230026, China
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88
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Peng Y, Zhu G. Biological nitrogen removal with nitrification and denitrification via nitrite pathway. Appl Microbiol Biotechnol 2006; 73:15-26. [PMID: 17028876 DOI: 10.1007/s00253-006-0534-z] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 06/01/2006] [Accepted: 06/05/2006] [Indexed: 10/24/2022]
Abstract
Presently, the wastewater treatment practices can be significantly improved through the introduction of new microbial treatment technologies. To meet increasingly stringent discharge standards, new applications and control strategies for the sustainable removal of ammonium from wastewater have to be implemented. Partial nitrification to nitrite was reported to be technically feasible and economically favorable, especially when wastewater with high ammonium concentrations or low C/N ratios is treated. For successful implementation of the technology, the critical point is how to maintain partial nitrification of ammonium to nitrite. Partial nitrification can be obtained by selectively inhibiting nitrite oxidizing bacteria through appropriate regulation of the system's DO concentration, microbial SRT, pH, temperature, substrate concentration and load, operational and aeration pattern, and inhibitor. The review addressed the microbiology, its consequences for their application, the current status regarding application, and the future developments.
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Affiliation(s)
- Yongzhen Peng
- School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
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89
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Laurin V, Labbé N, Juteau P, Parent S, Villemur R. Long-term storage conditions for carriers with denitrifying biomass of the fluidized, methanol-fed denitrification reactor of the Montreal Biodome, and the impact on denitrifying activity and bacterial population. WATER RESEARCH 2006; 40:1836-40. [PMID: 16624369 DOI: 10.1016/j.watres.2006.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 02/28/2006] [Accepted: 03/02/2006] [Indexed: 05/08/2023]
Abstract
The Montreal Biodome has a denitrification system to stabilize the nitrate concentration in its 3 million liter seawater aquarium. However, this microbial process has failed periodically due to various technical problems. The system can take several weeks to recover its full denitrification capacity. In order to provide the denitrification system with a backup of active biomass, different freezing conditions for the denitrifying biomass were tested. The biomass was conserved for 1 week-17 months at -20 degrees C with and without glycerol or at -80 degrees C with and without glycerol, and the denitrifying activity was tested in batch culture for 140 h periods at various intervals. Our results showed that glycerol was required for fast recovery of the microbial community's denitrifying activity. The -20 degrees C and -80 degrees C conservation temperatures with glycerol gave similar results although there was a short period of nitrite accumulation in the -20 degrees C sample. There were no substantial changes in the microbial community of any of the frozen samples after 17 months of conservation as monitored by denaturing gradient gel electrophoresis. This is the first report on the long-term conservation of a complex denitrifying population by freezing.
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Affiliation(s)
- Véronique Laurin
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Canada H7V 1B7
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90
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Walter B, Haase C, Räbiger N. Combined nitrification/denitrification in a membrane reactor. WATER RESEARCH 2005; 39:2781-8. [PMID: 16000209 DOI: 10.1016/j.watres.2005.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 03/15/2005] [Accepted: 03/22/2005] [Indexed: 05/03/2023]
Abstract
An ever stricter legislation regulating wastewater leads to an increasing demand for biological treatment plants which are able to selectively eliminate nitrogen from wastewaters with a high influent concentration, even when operating in partial influent mode. A membrane-tube-module (MSM) reactor (Membran-Schlauch-Modul-Reaktor) was constructed and realized in the IUV at the University of Bremen. The present approach makes use of all the various layers of the whole biofilm, enabling nitrification and denitrification processes to run simultaneously in one and the same biofilm under optimized conditions. The biological degradation capacity of the system was first successfully tested with synthetic wastewater, and subsequently in a real application with effluents from a recycling of animal carcasses plant and from a coke-oven plant. A mathematical model was devised which describes this biofilm system. The resulting equations were solved by means of the simulation software AQUASIM.
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Affiliation(s)
- B Walter
- IUV-Institute of Environmental Process Engineering, University of Bremen, P.O. Box 33 04 40, 28334 Bremen, Germany
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91
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Foglar L, Briski F, Sipos L, Vuković M. High nitrate removal from synthetic wastewater with the mixed bacterial culture. BIORESOURCE TECHNOLOGY 2005; 96:879-888. [PMID: 15627558 DOI: 10.1016/j.biortech.2004.09.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 05/27/2004] [Accepted: 09/02/2004] [Indexed: 05/24/2023]
Abstract
The applicability of the mixed bacterial culture, originated from two-stage anaerobic-aerobic industrial yeasts production wastewater treatment plant for high rate denitrification processes was investigated. After acclimation to nitrate, the dominant strains were Pseudomonas and Paracoccus sp. Complete denitrification with low accumulation of nitrite-N (0.1 mg/l) was found in synthetic wastewater, obeying a zero-order reaction with respect to nitrate and a first-order reaction with respect to biomass concentration. Denitrification was then monitored in the continuous-flow stirred reactor at different hydraulic retention time, HRT (62-28 h) in order to achieve the optimal HRT. Nitrate was completely removed during following 45 days, at 25 degrees C with HRT, which we reduced from 62 to 28 h. Yet still, at 28 h HRT, high average specific denitrification rate of 142 mg NO3- -N/g VSS h was obtained.
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Affiliation(s)
- Lucija Foglar
- Division of Industrial Ecology, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, HR-10000 Zagreb, Croatia.
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92
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Rezania B, Cicek N, Oleszkiewicz JA. Kinetics of hydrogen-dependent denitrification under varying pH and temperature conditions. Biotechnol Bioeng 2005; 92:900-6. [PMID: 16116656 DOI: 10.1002/bit.20664] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is important to determine the effect of changing environmental conditions on the microbial kinetics for design and modeling of biological treatment processes. In this research, the kinetics of nitrate and nitrite reduction by autotrophic hydrogen-dependent denitrifying bacteria and the possible role of acetogens were studied in two sequencing batch reactors (SBR) under varying pH and temperature conditions. A zero order kinetic model was proposed for nitrate and nitrite reduction and kinetic coefficients were obtained at two temperatures (25 +/- 1 and 12 +/- 1 degrees C), and pH ranging from 7 to 9.5. Nitrate and nitrite reduction was inhibited at pH of 7 at both temperatures of 12 +/- 1 and 25 +/- 1 degrees C. The optimum pH conditions for nitrate and nitrite reduction were 9.5 at 25 +/- 1 degrees C and 8.5 at 12 +/- 1 degrees C. Nitrate and nitrite reduction rates were compared, when they were used separately as the sole electron acceptor. It was shown that nitrite reduction rates consistently exceeded nitrate reduction rates, regardless of temperature and pH. The observed transitional accumulation of nitrite, when nitrate was used as an electron acceptor, indicated that nitrite reduction was slowed down by the presence of nitrate. No activity of acetogenic bacteria was observed in the hydrogenotrophic biomass and no residual acetate was detected, verifying that the kinetic parameters obtained were not influenced by heterotrophic denitrification and accurately represented autotrophic activity.
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Affiliation(s)
- B Rezania
- Department of Civil Engineering, University of Manitoba, Winnipeg, Manitoba R3T 5V6, Canada.
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93
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94
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95
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Lee KC, Rittmann BE. Effects of pH and precipitation on autohydrogenotrophic denitrification using the hollow-fiber membrane-biofilm reactor. WATER RESEARCH 2003; 37:1551-1556. [PMID: 12600383 DOI: 10.1016/s0043-1354(02)00519-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Experiments carried out in a hollow-fiber, membrane-biofilm reactor (HFMBR) showed that the optimum pH for autotrophic denitrification was in the range 7.7-8.6, with the maximum efficiency at 8.4. Increasing the pH above 8.6 caused a significant decrease in nitrate removal rate and a dramatic increase in nitrite accumulation. The pH rose by 1.2 units when a large buffer was not added, suggesting that some field applications may require pH control. Precipitation of Ca(2+) occurred in every experiment. Precipitation was the largest sink for carbonate, and it also offset alkalinity production by denitrification. Although the alkalinity increased in most cases, systems with a high carbonate buffer and high pH accentuated precipitation, and the net change in alkalinity was negative. The long-term success of field applications of the HFMBR may depend upon the interactions among calcium concentration, total carbonate concentration, pH, and alkalinity changes.
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Affiliation(s)
- Kuan-Chun Lee
- Department of Civil Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3109, USA.
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96
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97
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Abstract
As we are entering the post-genomic era, models-of-data, such as mining and filtering methods for gene sequences and microarrays and the clustering of co-expressed genes, must be complemented with models-of-processes that explain relationships between genomic information and phenomena at biochemical and physiological levels. Many of these models will have the structure of compartment models, whose conceptualization, identification and analysis will fundamentally benefit from the seminal work of John Jacquez. The article indicates with three vignettes that non-linear compartment models in the formulation of biochemical systems theory are viable candidates for post-genomic models-of-processes.
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Affiliation(s)
- Eberhard O Voit
- Department of Biometry and Epidemiology, Medical University of South Carolina, 135 Rutledge Avenue, Charleston, SC 29425, USA.
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98
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Weon SY, Lee CW, Lee SI, Koopman B. Nitrite inhibition of aerobic growth of Acinetobacter sp. WATER RESEARCH 2002; 36:4471-4476. [PMID: 12418649 DOI: 10.1016/s0043-1354(02)00185-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nitrite inhibition of Acinetobacter sp. growing under aerobic conditions was studied. Specific growth rates under non-limiting concentrations of acetate and dissolved oxygen averaged 0.62h(-1). Growth and phosphate uptake by Acinetobacter sp. were both inhibited by increasing nitrite concentrations. The median inhibitory concentration (IC50) of free nitrous acid (FNA) was 0.10 mg/L and the IC10 of FNA was 0.05 mg/L. Removing nitrite from cultures reversed the inhibitory effect. Comparison of the IC10 of FNA for Acinetobacter sp. to inhibitory concentrations for other wastewater heterotrophic bacteria suggests that Acinetobacter sp. are relatively sensitive to this compound.
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Affiliation(s)
- Seung-Yeon Weon
- Department of Environment Engineering Sciences, University of Florida, Gainesville 32611, USA
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99
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Effects of electron donors on nitrate removal by nitrate and nitrite reductases. BIOTECHNOL BIOPROC E 2002. [DOI: 10.1007/bf02935889] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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100
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Barak Y, Yarmus M, Shapira R, van Rijn J. Nitrite reduction in Paracoccus sp. is affected by a novel plasmid pYR1. FEMS Microbiol Lett 2002; 208:111-6. [PMID: 11934503 DOI: 10.1111/j.1574-6968.2002.tb11069.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Two relatively low-copy plasmids of 9 and 16 kb were found to comprise the extrachromosomal DNA of a Paracoccus strain. Reduction of nitrate by plasmid-cured cells resulted in a significant intermediate nitrite accumulation as compared to wild-type cells. By examining nitrate reduction by transformants containing one of the two plasmids, it was found that nitrite accumulation was influenced by the 9.0-kb plasmid, designated as pYR1. Subcloning analysis showed that a 1.8-kb fragment of this plasmid affected nitrite accumulation. Sequence analysis of this fragment revealed the presence of five open reading frames. One of the six deduced proteins showed a strong homology to ABC transporters.
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Affiliation(s)
- Yoram Barak
- Department of Animal Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, 76100, Rehovot, Israel
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