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Dataset Information

Anaerobic Oxidation of Benzene by the Hyperthermophilic Archaeon Ferroglobus placidus (Phenol vs. Benzoate)

ABSTRACT: Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]-benzene to [14C]-carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism and [14C]-benzoate was produced from [14C]-benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not up-regulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- versus benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. A five-chip study using total RNA recovered from three separate cultures of Ferroglobus placidus DSM 10642 grown with 0.5 mM phenol (experimental condition) and two separate cultures of Ferroglobus placidus DSM 10642 grown on 1 mM benzoate (control condition). Each chip measures the expression level of 2,613 genes from Ferroglobus placidus DSM 10642 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

ORGANISM(S): Ferroglobus placidus DSM 10642

SUBMITTER: Dawn Holmes

PROVIDER: E-GEOD-28549 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Anaerobic oxidation of benzene by the hyperthermophilic archaeon Ferroglobus placidus.

Holmes Dawn E DE Risso Carla C Smith Jessica A JA Lovley Derek R DR

Applied and environmental microbiology 20110708 17

Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [(14)C]benzene to [(14)C]carbon dioxide, wa ...[more]

PMID: 21742914

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Project description:Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]-benzene to [14C]-carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism and [14C]-benzoate was produced from [14C]-benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not up-regulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- versus benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. A six-chip study using total RNA recovered from three separate cultures of Ferroglobus placidus DSM 10642 grown with 1 mM benzene (experimental condition) and three separate cultures of Ferroglobus placidus DSM 10642 grown on 0.5 mM phenol (control condition). Each chip measures the expression level of 2,613 genes from Ferroglobus placidus DSM 10642 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

Project description:Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]-benzene to [14C]-carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism and [14C]-benzoate was produced from [14C]-benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not up-regulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- versus benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. A five-chip study using total RNA recovered from three separate cultures of Ferroglobus placidus DSM 10642 grown with 1 mM benzene (experimental condition) and two separate cultures of Ferroglobus placidus DSM 10642 grown on 1 mM benzoate (control condition). Each chip measures the expression level of 2,613 genes from Ferroglobus placidus DSM 10642 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

Project description:Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]-benzene to [14C]-carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism and [14C]-benzoate was produced from [14C]-benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not up-regulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- versus benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. A six-chip study using total RNA recovered from three separate cultures of Ferroglobus placidus DSM 10642 grown with 1 mM benzene (experimental condition) and three separate cultures of Ferroglobus placidus DSM 10642 grown on 10 mM acetate (control condition). Each chip measures the expression level of 2,613 genes from Ferroglobus placidus DSM 10642 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

Project description:Insight into the mechanisms for the anaerobic metabolism of aromatic compounds by the hyperthermophilic archaeon Ferroglobus placidus is expected to improve understanding of the degradation of aromatics in hot (> 80 °C) environments and to identify enzymes that might have biotechnological applications. Analysis of the F. placidus genome revealed genes predicted to encode enzymes homologous to those previously identified as playing a role in benzoate and phenol metabolism in mesophilic bacteria. Surprisingly, F. placidus lacks genes for an ATP-independent class II benzoyl-CoA reductase found in all strictly anaerobic bacteria, but instead has two sets of genes for ATP-consuming class I benzoyl-CoA reductases, similar to those found in facultative bacteria. The lower portion of the benzoate degradation pathway appears to be more similar to that found in the phototroph Rhodopseudomonas palustris, than the pathway reported for all heterotrophic anaerobic benzoate degraders. Many of the genes predicted to be involved in benzoate metabolism were found in one of two gene clusters. Genes for a phenol carboxylation proceeding through a phenylphosphate intermediate and for conversion of p-hydroxybenzoate to benzoyl-CoA were identified in a single gene cluster. Analysis of transcript abundance with a whole-genome microarray and quantitative PCR demonstrated that most of the genes predicted to be involved in benzoate or phenol metabolism had higher transcript abundance during growth on those substrates versus growth on acetate. These results suggest that the general strategies for benzoate and phenol metabolism may be highly conserved between microorganisms living in moderate and hot environments, and that anaerobic metabolism of aromatic compounds might be analyzed in a wide range of environments with similar molecular targets. A four chip study using total RNA recovered from two separate cultures of Ferroglobus placidus DSM 10642 grown with 1 mM sodium benzoate (experimental condition) and two separate cultures of Ferroglobus placidus DSM 10642 grown on 10 mM acetate (control condition). Each chip measures the expression level of 2613 genes from Ferroglobus placidus DSM 10642 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

Project description:Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance but research into the mechanisms has been stymied by a lack of a genetically tractable pure culture which unequivocally does not use molecular oxygen to activate benzene. Geobacter metallireducens grew in a medium in which benzene was the sole electron donor and Fe(III) was the sole electron acceptor with a stoichiometry of benzene loss and Fe(III) reduction consistent with benzene oxidation to carbon dioxide coupled with Fe(III) reduction. Phenol labeled with 18O was produced when the medium was labeled with H218O, as expected for a true anaerobic conversion of benzene to phenol. Gene expression patterns indicated that benzene was metabolized through a phenol intermediate rather than benzoate or toluene. Deletion of ppcB, which encodes a subunit of the phenylphosphate carboxylase, an enzyme required for phenol metabolism, inhibited metabolism of benzene. Deleting genes specific for benzoate or toluene metabolism did not. Comparison of gene expression patterns in cells grown on benzene versus cells grown on phenol revealed genes specifically expressed in benzene-grown cells. Deletion of one of these, Gmet_3376, inhibited anaerobic benzene oxidation, but not the metabolism of phenol, benzoate, or toluene. The availability of a genetically tractable pure culture that can anaerobically convert benzene to phenol with oxygen derived from water should significantly accelerate elucidation of the mechanisms by which benzene can be activated in the absence of molecular oxygen. Total RNA from three separate cultures of G. metallireducens grown with 250 ÂµM benzene three separate cultures of G. metallireducens grown with 500 ÂµM phenol three separate cultures of G. metallireducens grown with 1 mM benzoate three separate cultures of G. metallireducens grown with 500 ÂµM toluene three separate cultures of G. metallireducens grown with 10 mM acetate were used to study [1] Anaerobic oxidation of benzene by G. metallireducens (Benzene vs. acetate, Benzene vs. benzoate, Benzene vs. phenol, Benzene vs. toluene) [2] Anaerobic oxidation of benzoate by G. metallireducens (Benzoate vs. acetate) [3] Anaerobic oxidation of phenol by G. metallireducens (Phenol vs. acetate) [4] Anaerobic oxidation of toluene by G. metallireducens (Toluene vs. acetate) Each chip measures the expression level of 3,627 genes from G. metallireducens DSM 7210 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.

Dataset Information

Anaerobic Oxidation of Benzene by the Hyperthermophilic Archaeon Ferroglobus placidus (Phenol vs. Benzoate)

Publications

Anaerobic oxidation of benzene by the hyperthermophilic archaeon Ferroglobus placidus.

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