scholarly journals Impact of Electron Acceptor Availability on Methane-Influenced Microorganisms in an Enrichment Culture Obtained From a Stratified Lake

2020 ◽  
Vol 11 ◽  
Author(s):  
Sigrid van Grinsven ◽  
Jaap S. Sinninghe Damsté ◽  
John Harrison ◽  
Laura Villanueva
Keyword(s):  
Electron Acceptor ◽  
Enrichment Culture ◽  
Stratified Lake

Enrichment and characterization of an anaerobic methyl ethyl ketoxime degrading culture from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 95-98 ◽  
Author(s):  
Nancy G. Love ◽  
Mary E. Rust ◽  
Kathy C. Terlesky
Keyword(s):  
Energy Source ◽  
Activated Sludge ◽  
Electron Acceptor ◽  
Sequencing Batch Reactor ◽  
Enrichment Culture ◽  
Batch Reactor ◽  
Nitrification Inhibitor ◽  
Time Frame ◽  
Methyl Ethyl

An anaerobic enrichment culture was developed from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor using methyl ethyl ketoxime (MEKO), a potent nitrification inhibitor, as the sole carbon and energy source in the absence of molecular oxygen and nitrate. The enrichment culture was gradually fed decreasing amounts of biogenic organic compounds and increasing concentrations of MEKO over 23 days until the cultures metabolized the oxime as the sole carbon source; the cultures were maintained for an additional 41 days on MEKO alone. Turbidity stabilized at approximately 100 mg/l total suspended solids. Growth on selective media plates confirmed that the microorganisms were utilizing the MEKO as the sole carbon and energy source. The time frame required for growth indicated that the kinetics for MEKO degradation are slow. A batch test indicated that dissolved organic carbon decreased at a rate comparable to MEKO consumption, while sulfate was not consumed. The nature of the electron acceptor in anaerobic MEKO metabolism is unclear, but it is hypothesized that the MEKO is hydrolyzed intracellularly to form methyl ethyl ketone and hydroxylamine which serve as electron donor and electron acceptor, respectively.

scholarly journals Isolation of a Multiheme Protein with Features of a Hydrazine-Oxidizing Enzyme from an Anaerobic Ammonium-Oxidizing Enrichment Culture

2006 ◽  
Vol 73 (4) ◽  
pp. 1065-1072 ◽  
Author(s):  
Munetaka Shimamura ◽  
Takashi Nishiyama ◽  
Hiroyuki Shigetomo ◽  
Takeshi Toyomoto ◽  
Yuka Kawahara ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Electron Acceptor ◽  
Enrichment Culture ◽  
Critical Role ◽  
Reduced Form ◽  
Anammox Bacterium ◽  
Ammonium Oxidation ◽  
Metagenomic Dna ◽  
Bacterium Strain

ABSTRACT A multiheme protein having hydrazine-oxidizing activity was purified from enriched culture from a reactor in which an anammox bacterium, strain KSU-1, was dominant. The enzyme has oxidizing activity toward hydrazine but not hydroxylamine and is a 130-kDa homodimer composed of a 62-kDa polypeptide containing eight hemes. It was therefore named hydrazine-oxidizing enzyme (HZO). With cytochrome c as an electron acceptor, the Vmax and Km for hydrazine are 6.2 � 0.3 μmol/min � mg and 5.5 � 0.6 μM, respectively. Hydrazine (25 μM) induced an increase in the proportion of reduced form in the spectrum, whereas hydroxylamine (500 μM) did not. Two genes coding for HZO, hzoA and hzoB, were identified within the metagenomic DNA from the culture. The genes encode the same amino acid sequence except for two residues. The sequences deduced from these genes showed low-level identities (<30%) to those of all of the hydroxylamine oxidoreductases reported but are highly homologous to two hao genes found by sequencing the genome of “Candidatus Kuenenia stuttgartiensis” (88% and 89% identities). The purified enzyme might therefore be a novel hydrazine-oxidizing enzyme having a critical role in anaerobic ammonium oxidation.

scholarly journals Anaerobic growth of the haloalkaliphilic denitrifying sulfur-oxidizing bacterium Thialkalivibrio thiocyanodenitrificans sp. nov. with thiocyanate

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2435-2442 ◽  
Author(s):  
Dimitry Yu. Sorokin ◽  
Tat'yana P. Tourova ◽  
Alexey N. Antipov ◽  
G. Muyzer ◽  
J. Gijs Kuenen
Keyword(s):  
Lake Sediments ◽  
G Protein ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Novel Species ◽  
Enrichment Culture ◽  
Soda Lake ◽  
Anaerobic Growth ◽  
Growth Yields ◽  
Sulfur Oxidizing

Two strains of obligate chemolithoautotrophic sulfur-oxidizing bacteria were isolated from soda-lake sediments by enrichment culture with thiocyanate and nitrate at pH 9·9. The isolates were capable of growth with thiocyanate or thiosulfate as electron donor, either aerobically or anaerobically, and with nitrate or nitrite as electron acceptor. Cyanate was identified as an intermediate of thiocyanate oxidation, while sulfate, ammonia and dinitrogen gas were the final products. The anaerobic growth on thiocyanate plus nitrate was much slower (μ max=0·006 h−1) than on thiosulfate plus nitrate (μ max=0·02 h−1), while growth yields were similar (4·8 and 5·1 g protein mol−1, respectively). On the basis of their phenotypic and genetic properties, strains ARhD 1T and ARhD 2 are described as a novel species of the genus Thialkalivibrio, with the highest similarity to Thialkalivibrio denitrificans. The name Thialkalivibrio thiocyanodenitrificans sp. nov. is proposed for this novel species.

Etude physiologique et taxonomique du genre Alcaligenes: A. denitrificans, A. odorans et A. faecalis

1978 ◽  
Vol 24 (6) ◽  
pp. 743-753 ◽  
Author(s):  
F. Pichinoty ◽  
M. Véron ◽  
M. Mandel ◽  
M. Durand ◽  
C. Job ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Minimal Medium ◽  
Enrichment Culture ◽  
Point Of View ◽  
The Other ◽  
Lower Percentage ◽  
Hydroxybutyric Acid ◽  
Clinical Specimens ◽  
Alcaligenes Denitrificans ◽  
Strain Type

We have studied 43 strains of the species Alcaligenes denitrificans, A. odorans, and A. faecalis. Twenty-five of them were isolated by enrichment culture on minimal medium containing an organic acid (L-malate, succinate, tartrate, adipate, or itaconate) and N2O as a respiratory electron acceptor. These constitute a single phenon with the A. denitrificans strain type and 9 other strains isolated from clinical specimens. However, strain 4 differs from the other 34 strains in 12 nutritional characters, in its ability to effect a meta cleavage of diphenols, and by the absence of tetrathionate reductase. The percentages of G + C are the following: strains isolated from soil, 66.4 ± 1.1; collection strains, 67.0 ± 1.3. The 5 strains of A. odorans differ from the 34 strains of A. denitrificans (not including strain 4) in their inability to denitrify nitrate and use D-saccharate, adipate, pimelate, suberate, β-hydroxy-β-methylglutarate, meso-tartrate, azelate, and itaconate. Their percentage of G + C is much lower: 56.1 ± 0.4. From the nutritional point of view the 3 strains of A. faecalis resemble A. denitrificans. However, they differ from the latter by their inability to grow anaerobically on NO3−, NO2−, N2O, and S4O62−, and by a slightly lower percentage of G + C: 64.3 ± 0.0. The 43 strains synthesize poly-β-hydroxybutyric acid. None of them is chemolithotrophic.

Potential role of the Fe(III)-reducing bacteriaGeobacterandGeothrixin controlling arsenic solubility in Bengal delta sediments

2005 ◽  
Vol 69 (5) ◽  
pp. 865-875 ◽  
Author(s):  
F. S. Islam ◽  
C. Boothman ◽  
A. G. Gault ◽  
D. A. Polya ◽  
J. R. Lloyd
Keyword(s):  
Electron Acceptor ◽  
Enrichment Culture ◽  
Anaerobic Bacteria ◽  
Defined Medium ◽  
Geobacter Sulfurreducens ◽  
Close Relative ◽  
Bengal Delta ◽  
Delta Sediments ◽  
Reducing Bacteria ◽  
Geothrix Fermentans

AbstractPrevious studies from our laboratory have suggested a role for indigenous metal-reducing bacteria in the reduction of sediment-bound As(V), and have also shown that a stable enrichment culture of Fe(III)-reducing bacteria was able to mobilize arsenic (as As(III)) from sediments collected from West Bengal (Islamet al., 2004). To identify the Fe(III)-reducing bacteria that may play a role in the reduction of As(V) and mobilization of As(III), we made a detailed molecular analysis of this enrichment culture. It was dominated by a close relative ofGeothrix fermentans, but the type strain of this organism was unable to conserve energy for growth via the dissimilatory reduction of As(V), or reduce As(V) present in a defined medium containing fumarate as the electron acceptor. Furthermore, when the cells were grown using soluble Fe(III)-citrate as an electron acceptor in the presence of As(V), bacterial Fe(III) reduction resulted in the precipitation of the Fe(II)-bearing mineral vivianite in 2 weeks. This was accompanied by the efficient removal of As from solution. These results demonstrate thatGeothrix fermentans, in common with other key Fe(III)-reducing bacteria such asGeobacter sulfurreducens, does not reduce As(V) enzymatically, but can capture arsenic in Fe(II) minerals formed during respiration using Fe(III) as an electron acceptor. Thus, the reduction of arsenic-bearing Fe(III) oxide minerals is not sufficient to mobilize arsenic, but may result in the formation of Fe(II) biominerals that could potentially act as sinks for arsenic in sediments. Additional mechanisms, including dissimilatory As(V) reduction by other specialist anaerobic bacteria, are implicated in the mobilization of arsenic from sediments.

scholarly journals Isolation and Characterization of Alicycliphilus denitrificans Strain BC, Which Grows on Benzene with Chlorate as the Electron Acceptor

2008 ◽  
Vol 74 (21) ◽  
pp. 6672-6681 ◽  
Author(s):  
Sander A. B. Weelink ◽  
Nico C. G. Tan ◽  
Harm ten Broeke ◽  
Corn� van den Kieboom ◽  
Wim van Doesburg ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Enrichment Culture ◽  
Pcr Primers ◽  
Chlorite Dismutase ◽  
Benzene Degradation ◽  
Isolation And Characterization ◽  
Cell Extracts ◽  
Genes Encoding ◽  
Dioxygenase Enzymes ◽  
Chlorate Reductase

ABSTRACT A bacterium, strain BC, was isolated from a benzene-degrading chlorate-reducing enrichment culture. Strain BC degrades benzene in conjunction with chlorate reduction. Cells of strain BC are short rods that are 0.6 μm wide and 1 to 2 μm long, are motile, and stain gram negative. Strain BC grows on benzene and some other aromatic compounds with oxygen or in the absence of oxygen with chlorate as the electron acceptor. Strain BC is a denitrifying bacterium, but it is not able to grow on benzene with nitrate. The closest cultured relative is Alicycliphilus denitrificans type strain K601, a cyclohexanol-degrading nitrate-reducing betaproteobacterium. Chlorate reductase (0.4 U/mg protein) and chlorite dismutase (5.7 U/mg protein) activities in cell extracts of strain BC were determined. Gene sequences encoding a known chlorite dismutase (cld) were not detected in strain BC by using the PCR primers described in previous studies. As physiological and biochemical data indicated that there was oxygenation of benzene during growth with chlorate, a strategy was developed to detect genes encoding monooxygenase and dioxygenase enzymes potentially involved in benzene degradation in strain BC. Using primer sets designed to amplify members of distinct evolutionary branches in the catabolic families involved in benzene biodegradation, two oxygenase genes putatively encoding the enzymes performing the initial successive monooxygenations (BC-BMOa) and the cleavage of catechol (BC-C23O) were detected. Our findings suggest that oxygen formed by dismutation of chlorite can be used to attack organic molecules by means of oxygenases, as exemplified with benzene. Thus, aerobic pathways can be employed under conditions in which no external oxygen is supplied.

Anaerobic transformation of tetrachloroethane, perchloroethylene, and their mixtures by mixed-cultures enriched from contaminated soils and sediments

2005 ◽  
Vol 52 (1-2) ◽  
pp. 357-362 ◽  
Author(s):  
F. Aulenta ◽  
A. Fina ◽  
M. Potalivo ◽  
M. Petrangeli Papini ◽  
S. Rossetti ◽  
...  
Keyword(s):  
Vinyl Chloride ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Contaminated Soils ◽  
Enrichment Culture ◽  
Mixed Cultures ◽  
Soil Enrichment ◽  
Soils And Sediments

The focus of this research was to investigate the anaerobic transformation of tetrachloroethane (TeCA), perchloroethylene (PCE), and their mixtures by mixed cultures enriched from contaminated soils or sediments. Batch transformation studies were conducted using TeCA (60 μM), PCE (60 μM), or TeCA + PCE (each added at 60 μM) as electron acceptor(s) and H2+acetate (each added at 3 mM) or butyrate (3 mM) as electron donor(s). A Dehalococcoides spp.-containing, sediment-enrichment dechlorinated PCE rapidly to ethene (ETH) but slowly and incompletely dechlorinated TeCA. Moreover, when present in mixture with PCE, TeCA disrupted the ability of Dehalococcoides to dechlorinate vinyl chloride. In contrast, the soil-enrichment culture was able to completely dechlorinate TeCA and PCE to ETH, both when added as single contaminants and when added as a mixture.

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

2011 ◽  
Vol 197 ◽  
pp. 204-210 ◽  
Author(s):  
Vijai Elango ◽  
Harry D. Kurtz ◽  
Christina Anderson ◽  
David L. Freedman
Keyword(s):  
Electron Acceptor ◽  
Enrichment Culture ◽  
Terminal Electron Acceptor

scholarly journals Anaerobic Sulfide Oxidation with Nitrate by a Freshwater Beggiatoa Enrichment Culture

2006 ◽  
Vol 72 (7) ◽  
pp. 4755-4760 ◽  
Author(s):  
Anja Kamp ◽  
Peter Stief ◽  
Heide N. Schulz-Vogt
Keyword(s):  
Electron Acceptor ◽  
Enrichment Culture ◽  
Sulfide Oxidation ◽  
Chemotactic Response ◽  
Vertical Gradients

ABSTRACT A lithotrophic freshwater Beggiatoa strain was enriched in O2-H2S gradient tubes to investigate its ability to oxidize sulfide with NO3 − as an alternative electron acceptor. The gradient tubes contained different NO3 − concentrations, and the chemotactic response of the Beggiatoa mats was observed. The effects of the Beggiatoa sp. on vertical gradients of O2, H2S, pH, and NO3 − were determined with microsensors. The more NO3 − that was added to the agar, the deeper the Beggiatoa filaments glided into anoxic agar layers, suggesting that the Beggiatoa sp. used NO3 − to oxidize sulfide at depths below the depth that O2 penetrated. In the presence of NO3 − Beggiatoa formed thick mats (>8 mm), compared to the thin mats (ca. 0.4 mm) that were formed when no NO3 − was added. These thick mats spatially separated O2 and sulfide but not NO3 − and sulfide, and therefore NO3 − must have served as the electron acceptor for sulfide oxidation. This interpretation is consistent with a fourfold-lower O2 flux and a twofold-higher sulfide flux into the NO3 −-exposed mats compared to the fluxes for controls without NO3 −. Additionally, a pronounced pH maximum was observed within the Beggiatoa mat; such a pH maximum is known to occur when sulfide is oxidized to S0 with NO3 − as the electron acceptor.

scholarly journals Reductive Dechlorination of Tetrachloroethene tocis-1,2-Dichloroethene by a Thermophilic Anaerobic Enrichment Culture

1999 ◽  
Vol 65 (6) ◽  
pp. 2312-2316 ◽  
Author(s):  
Servé W. M. Kengen ◽  
Caroline G. Breidenbach ◽  
Andreas Felske ◽  
Alfons J. M. Stams ◽  
Gosse Schraa ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Electron Acceptor ◽  
Reductive Dechlorination ◽  
Dominant Species ◽  
Enrichment Culture ◽  
Microscopic Analysis ◽  
Dry Weight ◽  
Anaerobic Biodegradation ◽  
Optimum Temperature ◽  
Grown Culture

ABSTRACT Thermophilic anaerobic biodegradation of tetrachloroethene (PCE) was investigated with various inocula from geothermal and nongeothermal areas. Only polluted harbor sediment resulted in a stable enrichment culture that converted PCE via trichloroethene tocis-1,2-dichloroethene at the optimum temperature of 60 to 65°C. After several transfers, methanogens were eliminated from the culture. Dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor but not by H2, formate, or acetate. Fumarate and l-malate led to the highest dechlorination rate. In the absence of PCE, fumarate was fermented to acetate, H2, CO2, and succinate. With PCE, less H2 was formed, suggesting that PCE competed for the reducing equivalents leading to H2. PCE dechlorination, apparently, was not outcompeted by fumarate as electron acceptor. At the optimum dissolved PCE concentration of ∼60 μM, a high dechlorination rate of 1.1 μmol h−1mg−1 (dry weight) was found, which indicates that the dechlorination is not a cometabolic activity. Microscopic analysis of the fumarate-grown culture showed the dominance of a long thin rod. Molecular analysis, however, indicated the presence of two dominant species, both belonging to the low-G+C gram positives. The highest similarity was found with the genus Dehalobacter (90%), represented by the halorespiring organism Dehalobacter restrictus, and with the genus Desulfotomaculum(86%).

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