Two distinct pathways for anaerobic degradation of aromatic compounds in the denitrifying bacterium Thauera aromatica strain AR-1

Philipp, Bodo; Schink, Bernhard

doi:10.1007/s002039900112

Cited by 29 publications

(37 citation statements)

References 21 publications

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“…S1C in the supplemental material), suggesting that CO 2 and N 2 were end products (not quantified). Thauera spp., belonging to the betaproteobacteria, are known to reduce nitrate by denitrification (28). Strain N2 was able to oxidize a range of other organic compounds (not shown).…”

Section: Resultsmentioning

confidence: 98%

Oil Field Souring Control by Nitrate-Reducing Sulfurospirillum spp. That Outcompete Sulfate-Reducing Bacteria for Organic Electron Donors

Hubert

Voordouw

2007

Appl Environ Microbiol

279

178

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Nitrate injection into oil reservoirs can prevent and remediate souring, the production of hydrogen sulfide by sulfate-reducing bacteria (SRB). Nitrate stimulates nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) and heterotrophic nitrate-reducing bacteria (hNRB) that compete with SRB for degradable oil organics. Up-flow, packed-bed bioreactors inoculated with water produced from an oil field and injected with lactate, sulfate, and nitrate served as sources for isolating several NRB, including Sulfurospirillum and Thauera spp. The former coupled reduction of nitrate to nitrite and ammonia with oxidation of either lactate (hNRB activity) or sulfide (NR-SOB activity). Souring control in a bioreactor receiving 12.5 mM lactate and 6, 2, 0.75, or 0.013 mM sulfate always required injection of 10 mM nitrate, irrespective of the sulfate concentration. Community analysis revealed that at all but the lowest sulfate concentration (0.013 mM), significant SRB were present. At 0.013 mM sulfate, direct hNRB-mediated oxidation of lactate by nitrate appeared to be the dominant mechanism. The absence of significant SRB indicated that sulfur cycling does not occur at such low sulfate concentrations. The metabolically versatile Sulfurospirillum spp. were dominant when nitrate was present in the bioreactor. Analysis of cocultures of Desulfovibrio sp. strain Lac3, Lac6, or Lac15 and Sulfurospirillum sp. strain KW indicated its hNRB activity and ability to produce inhibitory concentrations of nitrite to be key factors for it to successfully outcompete oil field SRB.

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Section: Resultsmentioning

confidence: 98%

Oil Field Souring Control by Nitrate-Reducing Sulfurospirillum spp. That Outcompete Sulfate-Reducing Bacteria for Organic Electron Donors

Hubert

Voordouw

2007

Appl Environ Microbiol

279

178

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“…Cosmid R ؉ contains all of the genes involved in resorcinol degradation by A. anaerobius. A. anaerobius and T. aromatica belong to the class Betaproteobacteria and are capable of growing at the expense of aromatic compounds under denitrifying conditions (32,33,40). A cosmid library with A. anaerobius chromosomal DNA was constructed and heterologously expressed in two T. aromatica strains, AR1 and K172, that are unable to metabolize resorcinol.…”

Section: Resultsmentioning

confidence: 99%

“…A cosmid library with A. anaerobius chromosomal DNA was constructed and heterologously expressed in two T. aromatica strains, AR1 and K172, that are unable to metabolize resorcinol. Nevertheless, T. aromatica AR1 degrades ␣-resorcylate (3,5-dihydroxybenzoate) via the HHQ pathway (14,33) and can therefore be expected to harbor genes similar to those of A. anaerobius. T. aromatica K172 is known to degrade neither resorcinol nor ␣-resorcylate.…”

Section: Resultsmentioning

confidence: 99%

Heterologous Expression and Identification of the Genes Involved in Anaerobic Degradation of 1,3-Dihydroxybenzene (Resorcinol) in Azoarcus anaerobius

et al. 2007

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Azoarcus anaerobius, a strictly anaerobic, gram-negative bacterium, utilizes resorcinol as a sole carbon and energy source with nitrate as an electron acceptor. Previously, we showed that resorcinol degradation by this bacterium is initiated by two oxidative steps, both catalyzed by membrane-associated enzymes that lead to the formation of hydroxyhydroquinone (HHQ; 1,2,4-benzenetriol) and 2-hydroxy-1,4-benzoquinone (HBQ). This study presents evidence for the further degradation of HBQ in cell extracts to form acetic and malic acids. To identify the A. anaerobius genes required for anaerobic resorcinol catabolism, a cosmid library with genomic DNA was constructed and transformed into the phylogenetically related species Thauera aromatica, which cannot grow with resorcinol. By heterologous complementation, a transconjugant was identified that gained the ability to metabolize resorcinol. Its cosmid, designated R ؉ , carries a 29.88-kb chromosomal DNA fragment containing 22 putative genes. In cell extracts of T. aromatica transconjugants, resorcinol was degraded to HHQ, HBQ, and acetate, suggesting that cosmid R ؉ carried all of the genes necessary for resorcinol degradation. On the basis of the physiological characterization of T. aromatica transconjugants carrying transposon insertions in different genes of cosmid R؉ , eight open reading frames were found to be essential for resorcinol mineralization. Resorcinol hydroxylase-encoding genes were assigned on the basis of sequence analysis and enzyme assays with two mutants. Putative genes for hydroxyhydroquinone dehydrogenase and enzymes involved in ring fission have also been proposed. This work provides the first example of the identification of genes involved in the anaerobic degradation of aromatic compounds by heterologous expression of a cosmid library in a phylogenetically related organism.

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“…Most experimental and recent theoretical evaluations of microbial growth with substrate mixtures are restricted to pure-culture phenomena (8,12,30). Further, relatively few studies have addressed the regulation of anaerobic aromatic compound metabolism in pure cultures (9,19,32,33,37). Repression of 3-CB reductive dehalogenation in D. tiedjei has been reported previously (28).…”

Section: Discussionmentioning

confidence: 86%

Effects of Endogenous Substrates on Adaptation of Anaerobic Microbial Communities to 3-Chlorobenzoate

Becker

Berardesco

Rittmann

et al. 2006

Appl Environ Microbiol

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Lengthy adaptation periods in laboratory studies evaluating the potential for contaminant biodegradation in natural or engineered environments may indicate that the native microbial communities are not metabolizing the contaminants in situ. In this study, we characterized the adaptation period preceding the biodegradation of 3-chlorobenzoate in anaerobic communities derived from lake sediment and wastewater sludge digesters. The importance of alternative mechanisms of adaptation of the anaerobic communities to 3-chlorobenzoate was evaluated by monitoring the concentrations of metabolic substrates and products as well as the levels of total small subunit (SSU) rRNA and SSU rRNA from populations thought to be important in 3-chlorobenzoate mineralization. The anaerobic environments from which the 3-chlorobenzoate-degrading communities were derived contained different levels of endogenous substrates. Increasing methane levels in the digester and sediment communities and decreasing chemical oxygen demand concentrations in the sediment community during the adaptation periods revealed that endogenous substrates were preferentially utilized relative to 3-chlorobenzoate. Methane and chemical oxygen demand concentrations leveled off concomitantly with the onset of 3-chlorobenzoate biodegradation, suggesting that depletion of the preferentially degraded endogenous substrates stimulated 3-chlorobenzoate metabolism. Consistent with these observations, adaptation to 3-chlorobenzoate occurred more rapidly in digester samples that were depleted of endogenous substrates compared to samples that contained high levels of these biodegradable compounds. Other potential adaptation mechanisms, e.g., genetic change or selective population enrichment, appeared to be less important based on the reproducibility and relative lengths of the adaptation events, trends in the SSU rRNA levels, and/or amplification of SSU rRNA genes from key populations.

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Two distinct pathways for anaerobic degradation of aromatic compounds in the denitrifying bacterium Thauera aromatica strain AR-1

Cited by 29 publications

References 21 publications

Oil Field Souring Control by Nitrate-Reducing Sulfurospirillum spp. That Outcompete Sulfate-Reducing Bacteria for Organic Electron Donors

Oil Field Souring Control by Nitrate-Reducing Sulfurospirillum spp. That Outcompete Sulfate-Reducing Bacteria for Organic Electron Donors

Heterologous Expression and Identification of the Genes Involved in Anaerobic Degradation of 1,3-Dihydroxybenzene (Resorcinol) in Azoarcus anaerobius

Effects of Endogenous Substrates on Adaptation of Anaerobic Microbial Communities to 3-Chlorobenzoate

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