A strictly anaerobic betaproteobacteriumGeorgfuchsia toluolicagen. nov., sp. nov. degrades aromatic compounds with Fe(III), Mn(IV) or nitrate as an electron acceptor

ABSTRACT Methanosarcina acetivorans, a strictly anaerobic methane-producing species belonging to the domain Archaea, contains a gene cluster annotated with homologs encoding oxidative stress proteins. One of the genes (MA3736) is annotated as a gene encoding an uncharacterized carboxymuconolactone decarboxylase, an enzyme required for aerobic growth with aromatic compounds by species in the domain Bacteria. Methane-producing species are not known to utilize aromatic compounds, suggesting that MA3736 is incorrectly annotated. The product of MA3736, overproduced in Escherichia coli, had protein disulfide reductase activity dependent on a C67XXC70 motif not found in carboxymuconolactone decarboxylase. We propose that MA3736 be renamed mdrA (methanosarcina disulfide reductase). Further, unlike carboxymuconolactone decarboxylase, MdrA contained an Fe-S cluster. Binding of the Fe-S cluster was dependent on essential cysteines C67 and C70, while cysteines C39 and C107 were not required. Loss of the Fe-S cluster resulted in conversion of MdrA from an inactive hexamer to a trimer with protein disulfide reductase activity. The data suggest that MdrA is the prototype of a previously unrecognized protein disulfide reductase family which contains an intermolecular Fe-S cluster that controls oligomerization as a mechanism to regulate protein disulfide reductase activity.

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6-Hydroxypseudooxynicotine Dehydrogenase Delivers Electrons to Electron Transfer Flavoprotein during Nicotine Degradation by Agrobacterium tumefaciens S33

Applied and Environmental Microbiology ◽

10.1128/aem.00454-19 ◽

2019 ◽

Vol 85 (11) ◽

Cited By ~ 3

Author(s):

Rongshui Wang ◽

Jihong Yi ◽

Jinmeng Shang ◽

Wenjun Yu ◽

Zhifeng Li ◽

...

Keyword(s):

Electron Transfer ◽

Agrobacterium Tumefaciens ◽

Electron Transport ◽

Electron Acceptor ◽

Aromatic Compounds ◽

Coenzyme Q ◽

Content Type ◽

Electron Transfer Flavoprotein ◽

Nicotine Degradation

ABSTRACT Agrobacterium tumefaciens S33 degrades nicotine via a novel hybrid of the pyridine and the pyrrolidine pathways. The hybrid pathway consists of at least six steps involved in oxidoreductive reactions before the N-heterocycle can be broken down. Collectively, the six steps allow electron transfer from nicotine and its intermediates to the final acceptor O2 via the electron transport chain (ETC). 6-Hydroxypseudooxynicotine oxidase, renamed 6-hydroxypseudooxynicotine dehydrogenase in this study, has been characterized as catalyzing the fourth step using the artificial electron acceptor 2,6-dichlorophenolindophenol. Here, we used biochemical, genetic, and liquid chromatography-mass spectrometry (LC-MS) analyses to determine that 6-hydroxypseudooxynicotine dehydrogenase utilizes the electron transfer flavoprotein (EtfAB) as the physiological electron acceptor to catalyze the dehydrogenation of pseudooxynicotine, an analogue of the true substrate 6-hydroxypseudooxynicotine, in vivo, into 3-succinoyl-semialdehyde-pyridine. NAD(P)+, O2, and ferredoxin could not function as electron acceptors. The oxygen atom in the aldehyde group of the product 3-succinoyl-semialdehyde-pyridine was verified to be derived from H2O. Disruption of the etfAB genes in the nicotine-degrading gene cluster decreased the growth rate of A. tumefaciens S33 on nicotine but not on 6-hydroxy-3-succinoylpyridine, an intermediate downstream of the hybrid pathway, indicating the requirement of EtfAB for efficient nicotine degradation. The electrons were found to be further transferred from the reduced EtfAB to coenzyme Q by the catalysis of electron transfer flavoprotein:ubiquinone oxidoreductase. These results aid in an in-depth understanding of the electron transfer process and energy metabolism involved in the nicotine oxidation and provide novel insights into nicotine catabolism in bacteria. IMPORTANCE Nicotine has been studied as a model for toxic N-heterocyclic aromatic compounds. Microorganisms can catabolize nicotine via various pathways and conserve energy from its oxidation. Although several oxidoreductases have been characterized to participate in nicotine degradation, the electron transfer involved in these processes is poorly understood. In this study, we found that 6-hydroxypseudooxynicotine dehydrogenase, a key enzyme in the hybrid pyridine and pyrrolidine pathway for nicotine degradation in Agrobacterium tumefaciens S33, utilizes EtfAB as a physiological electron acceptor. Catalyzed by the membrane-associated electron transfer flavoprotein:ubiquinone oxidoreductase, the electrons are transferred from the reduced EtfAB to coenzyme Q, which then could enter into the classic ETC. Thus, the route for electron transport from the substrate to O2 could be constructed, by which ATP can be further sythesized via chemiosmosis to support the baterial growth. These findings provide new knowledge regarding the catabolism of N-heterocyclic aromatic compounds in microorganisms.

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Influence of Different Electron Donors and Acceptors on Dehalorespiration of Tetrachloroethene byDesulfitobacterium frappieri TCE1

Applied and Environmental Microbiology ◽

10.1128/aem.65.12.5212-5221.1999 ◽

1999 ◽

Vol 65 (12) ◽

pp. 5212-5221 ◽

Cited By ~ 110

Author(s):

Jan Gerritse ◽

Oliver Drzyzga ◽

Geert Kloetstra ◽

Mischa Keijmel ◽

Luit P. Wiersum ◽

...

Keyword(s):

Electron Acceptor ◽

Reductive Dechlorination ◽

Electron Acceptors ◽

Electron Donors ◽

Strictly Anaerobic ◽

16S Rrna Sequence ◽

Selective Enrichment ◽

Chemostat Cultures ◽

16S Rrna Sequence Analysis ◽

Desulfitobacterium Hafniense

ABSTRACT Strain TCE1, a strictly anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved rod-shaped organism that is 2 to 4 by 0.6 to 0.8 μm and has approximately six lateral flagella. The pH and temperature optima for growth are 7.2 and 35°C, respectively. On the basis of a comparative 16S rRNA sequence analysis, this bacterium was identified as a new strain of Desulfitobacterium frappieri, because it exhibited 99.7% relatedness to the D. frappieri type strain, strain PCP-1. Growth with H2, formate,l-lactate, butyrate, crotonate, or ethanol as the electron donor depends on the availability of an external electron acceptor. Pyruvate and serine can also be used fermentatively. Electron donors (except formate and H2) are oxidized to acetate and CO2. When l-lactate is the growth substrate, strain TCE1 can use the following electron acceptors: PCE and TCE (to produce cis-1,2-dichloroethene), sulfite and thiosulfate (to produce sulfide), nitrate (to produce nitrite), and fumarate (to produce succinate). Strain TCE1 is not able to reductively dechlorinate 3-chloro-4-hydroxyphenylacetate. The growth yields of the newly isolated bacterium when PCE is the electron acceptor are similar to those obtained for other dehalorespiring anaerobes (e.g.,Desulfitobacterium sp. strain PCE1 andDesulfitobacterium hafniense) and the maximum specific reductive dechlorination rates are 4 to 16 times higher (up to 1.4 μmol of chloride released · min−1 · mg of protein−1). Dechlorination of PCE and TCE is an inducible process. In PCE-limited chemostat cultures of strain TCE1, dechlorination is strongly inhibited by sulfite but not by other alternative electron acceptors, such as fumarate or nitrate.

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Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds

Applied and Environmental Microbiology ◽

10.1128/aem.02597-14 ◽

2014 ◽

Vol 81 (2) ◽

pp. 587-596 ◽

Cited By ~ 36

Author(s):

Marlén Pöritz ◽

Christian L. Schiffmann ◽

Gerd Hause ◽

Ulrike Heinemann ◽

Jana Seifert ◽

...

Keyword(s):

Electron Acceptor ◽

Aromatic Compounds ◽

Lag Phase ◽

Organohalide Respiration ◽

Content Type ◽

Reductive Dehalogenase ◽

Dehalococcoides Mccartyi ◽

Type Iv ◽

Transmission Electron ◽

Almost All

ABSTRACTPolyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments.Dehalococcoides mccartyistrain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds. Strain DCMB5 used hexachlorobenzenes, pentachlorobenzenes, all three tetrachlorobenzenes, and 1,2,3-trichlorobenzene as well as 1,2,3,4-tetra- and 1,2,4-trichlorodibenzo-p-dioxin as electron acceptors for organohalide respiration. In addition, 1,2,3-trichlorodibenzo-p-dioxin and 1,3-, 1,2-, and 1,4-dichlorodibenzo-p-dioxin were dechlorinated, the latter to the nonchlorinated congener with a remarkably short lag phase of 1 to 4 days following transfer. Strain DCMB5 also dechlorinated pentachlorophenol and almost all tetra- and trichlorophenols. Tetrachloroethene was dechlorinated to trichloroethene and served as an electron acceptor for growth. To relate selected dechlorination activities to the expression of specific reductive dehalogenase genes, the proteomes of 1,2,3-trichlorobenzene-, pentachlorobenzene-, and tetrachloroethene-dechlorinating cultures were analyzed. Dcmb_86, an ortholog of the chlorobenzene reductive dehalogenase CbrA, was the most abundant reductive dehalogenase during growth with each electron acceptor, suggesting its pivotal role in organohalide respiration of strain DCMB5. Dcmb_1041 was specifically induced, however, by both chlorobenzenes, whereas 3 putative reductive dehalogenases, Dcmb_1434, Dcmb_1339, and Dcmb_1383, were detected only in tetrachloroethene-grown cells. The proteomes also harbored a type IV pilus protein and the components for its assembly, disassembly, and secretion. In addition, transmission electron microscopy of DCMB5 revealed an irregular mode of cell division as well as the presence of pili, indicating that pilus formation is a feature ofD. mccartyiduring organohalide respiration.

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Geobacter soli sp. nov., a dissimilatory Fe(III)-reducing bacterium isolated from forest soil

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijs.0.066662-0 ◽

2014 ◽

Vol 64 (Pt_11) ◽

pp. 3786-3791 ◽

Cited By ~ 25

Author(s):

Shungui Zhou ◽

Guiqin Yang ◽

Qin Lu ◽

Min Wu

Keyword(s):

Forest Soil ◽

Electron Donor ◽

Electron Acceptor ◽

Type Species ◽

Geobacter Sulfurreducens ◽

Phenotypic Characterization ◽

Strictly Anaerobic ◽

Content Type ◽

Link Type ◽

Physiological Tests

A novel Fe(III)-reducing bacterium, designated GSS01T, was isolated from a forest soil sample using a liquid medium containing acetate and ferrihydrite as electron donor and electron acceptor, respectively. Cells of strain GSS01T were strictly anaerobic, Gram-stain-negative, motile, non-spore-forming and slightly curved rod-shaped. Growth occurred at 16–40 °C and optimally at 30 °C. The DNA G+C content was 60.9 mol%. The major respiratory quinone was MK-8. The major fatty acids were C16 : 0, C18 : 0 and C16 : 1ω7c/C16 : 1ω6c. Strain GSS01T was able to grow with ferrihydrite, Fe(III) citrate, Mn(IV), sulfur, nitrate or anthraquinone-2,6-disulfonate, but not with fumarate, as sole electron acceptor when acetate was the sole electron donor. The isolate was able to utilize acetate, ethanol, glucose, lactate, butyrate, pyruvate, benzoate, benzaldehyde, m-cresol and phenol but not toluene, p-cresol, propionate, malate or succinate as sole electron donor when ferrihydrite was the sole electron acceptor. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain GSS01T was most closely related to Geobacter sulfurreducens PCAT (98.3 % sequence similarity) and exhibited low similarities (94.9–91.8 %) to the type strains of other species of the genus Geobacter . The DNA–DNA relatedness between strain GSS01T and G. sulfurreducens PCAT was 41.4±1.1 %. On the basis of phylogenetic analysis, phenotypic characterization and physiological tests, strain GSS01T is believed to represent a novel species of the genus Geobacter , and the name Geobacter soli sp. nov. is proposed. The type strain is GSS01T ( = KCTC 4545T = MCCC 1K00269T).

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Growth of Campylobacter jejuni Supported by Respiration of Fumarate, Nitrate, Nitrite, Trimethylamine-N-Oxide, or Dimethyl Sulfoxide Requires Oxygen

Journal of Bacteriology ◽

10.1128/jb.184.15.4187-4196.2002 ◽

2002 ◽

Vol 184 (15) ◽

pp. 4187-4196 ◽

Cited By ~ 122

Author(s):

Michael J. Sellars ◽

Stephen J. Hall ◽

David J. Kelly

Keyword(s):

Energy Conservation ◽

Dimethyl Sulfoxide ◽

Campylobacter Jejuni ◽

Electron Acceptor ◽

Electron Acceptors ◽

Anaerobic Growth ◽

Strictly Anaerobic ◽

Anaerobic Conditions ◽

Single Class ◽

Wide Range

ABSTRACT The human gastrointestinal pathogen Campylobacter jejuni is a microaerophilic bacterium with a respiratory metabolism. The genome sequence of C. jejuni strain 11168 reveals the presence of genes that encode terminal reductases that are predicted to allow the use of a wide range of alternative electron acceptors to oxygen, including fumarate, nitrate, nitrite, and N- or S-oxides. All of these reductase activities were present in cells of strain 11168, and the molybdoenzyme encoded by Cj0264c was shown by mutagenesis to be responsible for both trimethylamine-N-oxide (TMAO) and dimethyl sulfoxide (DMSO) reduction. Nevertheless, growth of C. jejuni under strictly anaerobic conditions (with hydrogen or formate as electron donor) in the presence of any of the electron acceptors tested was insignificant. However, when fumarate, nitrate, nitrite, TMAO, or DMSO was added to microaerobic cultures in which the rate of oxygen transfer was severely restricted, clear increases in both the growth rate and final cell density compared to what was seen with the control were obtained, indicative of electron acceptor-dependent energy conservation. The C. jejuni genome encodes a single class I-type ribonucleotide reductase (RNR) which requires oxygen to generate a tyrosyl radical for catalysis. Electron microscopy of cells that had been incubated under strictly anaerobic conditions with an electron acceptor showed filamentation due to an inhibition of cell division similar to that induced by the RNR inhibitor hydroxyurea. An oxygen requirement for DNA synthesis can thus explain the lack of anaerobic growth of C. jejuni. The results indicate that strict anaerobiosis is a stress condition for C. jejuni but that alternative respiratory pathways can contribute significantly to energy conservation under oxygen-limited conditions, as might be found in vivo.

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Changes of the Proteome and Acetylome during Transition into the Stationary Phase in the Organohalide-Respiring Dehalococcoides mccartyi Strain CBDB1

Microorganisms ◽

10.3390/microorganisms9020365 ◽

2021 ◽

Vol 9 (2) ◽

pp. 365

Author(s):

Franziska Greiner-Haas ◽

Martin von Bergen ◽

Gary Sawers ◽

Ute Lechner ◽

Dominique Türkowsky

Keyword(s):

Membrane Protein ◽

Stationary Phase ◽

Electron Acceptor ◽

Acetate Metabolism ◽

Strictly Anaerobic ◽

Uptake Hydrogenase ◽

Organohalide Respiration ◽

Dehalococcoides Mccartyi ◽

Protein Levels ◽

Twin Arginine Translocation

The strictly anaerobic bactGIerium Dehalococcoides mccartyi obligatorily depends on organohalide respiration for energy conservation and growth. The bacterium also plays an important role in bioremediation. Since there is no guarantee of a continuous supply of halogenated substrates in its natural environment, the question arises of how D. mccartyi maintains the synthesis and activity of dehalogenating enzymes under these conditions. Acetylation is a means by which energy-restricted microorganisms can modulate and maintain protein levels and their functionality. Here, we analyzed the proteome and Nε-lysine acetylome of D. mccartyi strain CBDB1 during growth with 1,2,3-trichlorobenzene as an electron acceptor. The high abundance of the membrane-localized organohalide respiration complex, consisting of the reductive dehalogenases CbrA and CbdbA80, the uptake hydrogenase HupLS, and the organohalide respiration-associated molybdoenzyme OmeA, was shown throughout growth. In addition, the number of acetylated proteins increased from 5% to 11% during the transition from the exponential to the stationary phase. Acetylation of the key proteins of central acetate metabolism and of CbrA, CbdbA80, and TatA, a component of the twin-arginine translocation machinery, suggests that acetylation might contribute to maintenance of the organohalide-respiring capacity of the bacterium during the stationary phase, thus providing a means of ensuring membrane protein integrity and a proton gradient.

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Phosphitispora fastidiosa gen. nov. sp. nov., a new dissimilatory phosphite-oxidizing anaerobic bacterium isolated from anaerobic sewage sludge

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.005142 ◽

2021 ◽

Vol 71 (12) ◽

Author(s):

Zhuqing Mao ◽

Fabian Gräßle ◽

Jasmin Frey ◽

Paolo Franchini ◽

David Schleheck ◽

...

Keyword(s):

Sewage Sludge ◽

Electron Donor ◽

Electron Acceptor ◽

Anaerobic Bacterium ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Optimal Growth ◽

Rrna Gene ◽

Strictly Anaerobic

A new strictly anaerobic bacterium, strain DYL19T, was enriched and isolated with phosphite as the sole electron donor and CO2 as a single carbon source and electron acceptor from anaerobic sewage sludge sampled at a sewage treatment plant in Constance, Germany. It is a Gram-positive, spore-forming, slightly curved, rod-shaped bacterium which oxidizes phosphite to phosphate while reducing CO2 to biomass and small amounts of acetate. Optimal growth is observed at 30 °C, pH 7.2, with a doubling time of 3 days. Beyond phosphite, no further inorganic or organic electron donor can be used, and no other electron acceptor than CO2 is reduced. Sulphate inhibits growth with phosphite and CO2. The G+C content is 45.95 mol%, and dimethylmenaquinone-7 is the only quinone detectable in the cells. On the basis of 16S rRNA gene sequence analysis and other chemotaxonomic properties, strain DYL19T is described as the type strain of a new genus and species, Phosphitispora fastidiosa gen. nov., sp. nov.

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Syntrophic Degradation of Cadaverine by a Defined Methanogenic Coculture

Applied and Environmental Microbiology ◽

10.1128/aem.00342-09 ◽

2009 ◽

Vol 75 (14) ◽

pp. 4821-4828 ◽

Cited By ~ 11

Author(s):

Julia Roeder ◽

Bernhard Schink

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Electron Acceptor ◽

Rrna Gene ◽

Strictly Anaerobic ◽

16S Rrna Gene Analysis ◽

Sulfate Reducing ◽

Cell Extracts ◽

Syntrophic Degradation ◽

Acetate Butyrate

ABSTRACT A novel, strictly anaerobic, cadaverine-oxidizing, defined coculture was isolated from an anoxic freshwater sediment sample. The coculture oxidized cadaverine (1,5-diaminopentane) with sulfate as the electron acceptor. The sulfate-reducing partner could be replaced by a hydrogenotrophic methanogenic partner. The defined coculture fermented cadaverine to acetate, butyrate, and glutarate plus sulfide or methane. The key enzymes involved in cadaverine degradation were identified in cell extracts. A pathway of cadaverine fermentation via 5-aminovaleraldehyde and crotonyl-coenzyme A with subsequent dismutation to acetate and butyrate is suggested. Comparative 16S rRNA gene analysis indicated that the fermenting part of the coculture belongs to the subphylum Firmicutes but that this part is distant from any described genus. The closest known relative was Clostridium aminobutyricum, with 95% similarity.

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Retentive Memory of Bacteria: Long-Term Regulation of Dehalorespiration in Sulfurospirillum multivorans

Journal of Bacteriology ◽

10.1128/jb.00597-08 ◽

2008 ◽

Vol 191 (5) ◽

pp. 1650-1655 ◽

Cited By ~ 35

Author(s):

Markus John ◽

Raffael Rubick ◽

Roland P. H. Schmitz ◽

Jana Rakoczy ◽

Torsten Schubert ◽

...

Keyword(s):

Electron Acceptor ◽

Initial Level ◽

Transcript Level ◽

Strictly Anaerobic ◽

Terminal Electron Acceptor ◽

Catalytically Active ◽

Gain Energy ◽

Pce Dehalogenase ◽

Dehalogenase Gene

ABSTRACT The gram-negative, strictly anaerobic epsilonproteobacterium Sulfurospirillum multivorans is able to gain energy from dehalorespiration with tetrachloroethene (perchloroethylene [PCE]) as a terminal electron acceptor. The organism can also utilize fumarate as an electron acceptor. Prolonged subcultivation of S. multivorans in the absence of PCE with pyruvate as an electron donor and fumarate as an electron acceptor resulted in a decrease of PCE dehalogenase (PceA) activity. Concomitantly, the pceA transcript level equally decreased as shown by reverse transcriptase PCR. After 35 subcultivations (approximately 105 generations), a pceA transcript was not detectable and the PceA protein and activity were completely absent. In such long-term subcultivated S. multivorans cells, the biosynthesis of catalytically active PceA was restored to the initial level within about 50 h (approximately three generations) by the addition of PCE or trichloroethene. Single colonies obtained from PceA-depleted cultures were able to induce PCE dechlorination, indicating that long-term subcultured cells still contained the functional pceA gene. The results point to a novel type of long-term regulation of PCE dehalogenase gene expression in S. multivorans.

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