Acetogenic and Acid-Producing Clostridia

Ljungdahl, Lars G.; Hugenholtz, Jeroen; Wiegel, Juergen

doi:10.1007/978-1-4757-9718-3_5

Cited by 33 publications

(25 citation statements)

References 196 publications

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“…It is interesting that cells reduced aromatic carboxyl groups to the methyl level even when both preformed methyl and carbonyl groups were available for the synthesis of acetyl-CoA (Table 5, cultures E and F). This fact indicates that, even under conditions that allow the total synthesis of acetate from preexisting methyl-and carbonyl-level precursors (40), cells are still obligately dependent upon electron transport-dependent phosphorylation coupled to the reduction of CO2 (which, in this case, is derived from aromatic carboxyl groups) via the tetrahydrofolate pathway (25,30). Although these findings indicate that environmental conditions influence the use of aromatic carboxyl groups in acetogenesis, decarboxylation per se apparently is not obligately integrated into acetogenesis, since the aromatic carboxyl group went to free CO2 in short-term assays (Table 3).…”

Section: Discussionmentioning

confidence: 99%

Expression of an aromatic-dependent decarboxylase which provides growth-essential CO2 equivalents for the acetogenic (Wood) pathway of Clostridium thermoaceticum

1990

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: 1990). By using 4-hydroxybenzoate as a model substrate, an assay was devel9ped to study the expression apd activity of the decarboxylase involved in the activa'tion of aromatic carboxyl groups. The aromatic-dppendent decarboxylase was induced by carboxylated aromatic compounds in the early'stages of'growth and was not repressed by glucose or. other acetogenic substrates; nonutilizable carboxylated aromatic compounds did not induce the decarboxylase. The decarboxylase activity displayed saturation kinetics at both whole-cell and cell extract levels, was sensitive to oxidation, and was not affected by exogenous energy sources. However, at the whole-cell level, metabolic inhibitors decreased the decarboxylase activity. Supplemental biotin or avidin did not significantly affect decarboxylation. The aromatic-dependent decarboxylase was specific for benzoates with a hydroxyl group in the para position of the aromatic ring; the meta position could bie occupied by various substituent groups (-H, -OH, -OCH3, -Cl, or -F). The carboxyl carbon from [carboxyl-'4C]vaniliate went primarily to 14C02 in short-term decarboxylase assays. During growth, the aromatic carboxyl group went primarily to CO2 under C02-enriched conditions. However, under C02-limited conditions, the aromatic carboxyl carbon went nearly totally to acetate, with equal distribution between the carboxyl and methyl carbons, thus demonstrating that acetate could be totally synthesized from aromatic carboxyl groups. In contrast, when cocultivated (i.e., supplemented) with CO under C02-limited conditions, the aromatic carboxyl group went primarily to the methyl carbon of acetate.

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Section: Discussionmentioning

confidence: 99%

Expression of an aromatic-dependent decarboxylase which provides growth-essential CO2 equivalents for the acetogenic (Wood) pathway of Clostridium thermoaceticum

1990

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“…Many facets of this topic have been the subject of extensive reviews: namely, acid production or acidogenesis (90); solvent production or solventogenesis (14,69,70); proteolytic and purinolytic fermentations (9); and acetate production via multiple substrates or homoacetogenesis (90). Readers are guided to these publications for detailed discussions on specific topics.…”

Section: Overview Of Clostridial Metabolismmentioning

confidence: 99%

“…However, some are capable of autotrophic metabolism (90,110). Examples of such species are C. aceticum and C. thermoaceticum.…”

Section: Autotrophic Metabolismmentioning

confidence: 99%

“…This autotrophic pathway ( Figure 5) is mediated by the enzyme carbon monoxide dehydrogenase (CO-DH). The reducing power for the pathway is directly generated via the uptake of molecular hydrogen by hydrogenase or reduced ferredoxins formed from the fermentation of an electron donor (90). Reactions for both the acidogenic phase (acetate and butyrate products) and the solventogenesis phase (acetone, butanol, and ethanol products) are shown; however, major products formed during the solventogenic phase are highlighted with boxes.…”

Section: Autotrophic Metabolismmentioning

confidence: 99%

“…4S] clusters (90). The CO electron donor directly forms a complex with the nickel in the redox center.…”

Section: The Highly Reducing Redox Center Of Co-dh Contains Nickel Atmentioning

confidence: 99%

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Novel Pathways of Nitroaromatic Metabolism: Hydroxylamine Formation, Reactivity and Potential for Ring Fission for Destruction of TNT-CU1214

Hughes¹

2005

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Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE15 SERDP SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release, distribution unlimited SUPPLEMENTARY NOTESThe original document contains color images. ABSTRACTBioremediation has come into favor as the treatment of choice for munitions contamination because of the prohibitively high cost of the treatment alternative, incineration. To this end, this research was designed to provide information required for development of bioremediation systems to treat TNT contamination. This research investigated biological transformation of TNT with the primary goal of furthering the understanding of the fundamental biochemical mechanisms responsible for transformation of TNT and its fate in the environment. This research explored the products of novel TNT transformation pathways and determined the mechanisms of TNT transformation and identified the enzymes responsible. Prescribed by This report was prepared under contract to the Department of Defense Strategic Environmental Research and Development Program (SERDP). The publication of this report does not indicate endorsement by the Department of Defense, nor should the contents be construed as reflecting the official policy or position of the Department of Defense. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the Department of Defense.ii Table of Contents Table of Contents ii List of Acronyms iv List of Figures vList of Tables vii Acknowledgements viii Executive Summary 1Objective 7Background 8 Aerobic Biodegradation 11Reductive Cometabolism 17Anaerobic-Aerobic Treatment of TNT 21 Materials and Methods 23Bacteria and culture methods 23Transformation of TNT 23 Analytical Methods 24Metabolite purification 24 Preparation of DHANT 25Protein extraction and fractionation 25Enzyme assays 26 Results and Accomplishments 27Novel metabolic products in TNT transformation pathway 27Transformation of TNT by Clostridium acetobutylicum 27Transformation of TNT by P. pseudoalcaligenes JS52 28Characterization of mechanism and enzymes responsible for TNT trans...

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General Biology and Physiology

Mitchell

2001

Clostridia

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Acetogenic and Acid-Producing Clostridia

Cited by 33 publications

References 196 publications

Expression of an aromatic-dependent decarboxylase which provides growth-essential CO2 equivalents for the acetogenic (Wood) pathway of Clostridium thermoaceticum

Expression of an aromatic-dependent decarboxylase which provides growth-essential CO2 equivalents for the acetogenic (Wood) pathway of Clostridium thermoaceticum

Novel Pathways of Nitroaromatic Metabolism: Hydroxylamine Formation, Reactivity and Potential for Ring Fission for Destruction of TNT-CU1214

General Biology and Physiology

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