Anaerobic Degradation of Acetone and Higher Ketones via Carboxylation by Newly Isolated Denitrifying Bacteria

Platen, Harald; Schink, Bernhard

doi:10.1099/00221287-135-4-883

Cited by 35 publications

(13 citation statements)

References 25 publications

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“…capsulatus suggests a metabolic route for acetone photocatabolism and is similar to the finding of Platen and Schink who described acetone-degrading, denitrifying, pseudomonads [7]. Because catabolism by Rb.…”

Section: Discussionsupporting

confidence: 84%

“…Acetone is a natural product of certain bacterial fermentations [7][8][9] and is also a major commodity chemical produced from petroleum. Acetone thus becomes available for microbial catabolism as a result of both natural biological processes and the activities of humans.…”

Section: Introductionmentioning

confidence: 99%

“…Acetone can be degraded aerobically by various bacteria [10], but anaerobically, acetone metabolism is more restricted. Acetone can be degraded by anaerobic consortia terminating in methanogenesis [8] and also by pure cultures of denitrifying bacteria [7]. Because of their nutritional versatility [1,11], nonsulfur purple bacteria must also be considered potential acetone degraders and it was the aim of the present work to examine this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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Photocatabolism of acetone by nonsulfur purple bacteria

Madigan

1990

FEMS Microbiology Letters

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SUMMARYTests for the capacity of nonsulfur purple bacteria to photocatabolize acetone revealed that certain strains of Rhodobacter (Rb.) capsulatus and Rhodomicrobium (Rm.) vannielii could grow on this organic compound. Phototrophic growth of R.capsulatus strain B10 on acetone was CO2 dependent, Dark anaerobic or dark aerobic growth of R. capsulatus on acetone was not observed, although microaerobic growth in the dark did occur. Of a total of 13 species of nonsulfur purple bacteria examined, only strains of Rb. capsulatus and Rm. vannielii were found capable of photoheterotrophic growth on acetone.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photocatabolism of acetone by nonsulfur purple bacteria

Madigan

1990

FEMS Microbiology Letters

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“…Schink and coworkers (5,10,11,27,28) have studied acetone metabolism in several anaerobic bacteria and obtained in vivo and in vitro data supporting the existence of CO 2 -dependent pathways in which acetone is carboxylated to acetoacetate or an acetoacetyl derivative (e.g., acetoacetyl-CoA). The enzymatic activity believed to be responsible for acetone carboxylation in a denitrifier designated strain BunN was studied in cell extracts.…”

Section: Discussionmentioning

confidence: 99%

Purification and characterization of acetone carboxylase from Xanthobacter strain Py2

Sluis

Ensign

1997

Proc. Natl. Acad. Sci. U.S.A.

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Acetone metabolism in the aerobic bacterium Xanthobacter strain Py2 proceeds by a carboxylation reaction forming acetoacetate as the first detectable product. In this study, acetone carboxylase, the enzyme catalyzing this reaction, has been purified to homogeneity and characterized. Acetone carboxylase was comprised of three polypeptides with molecular weights of 85,300, 78,300, and 19,600 arranged in an ␣ 2 ␤ 2 ␥ 2 quaternary structure. The carboxylation of acetone was coupled to the hydrolysis of ATP and formation of 1 mol AMP and 2 mol inorganic phosphate per mol acetoacetate formed. ADP was also formed during the course of acetone consumption, but only accumulated at low, substoichiometric levels (Ϸ10% yield) relative to acetoacetate. Inorganic pyrophosphate could not be detected as an intermediate or product of acetone carboxylation. In the absence of CO 2 , acetone carboxylase catalyzed the acetone-dependent hydrolysis of ATP to form both ADP and AMP, with ADP accumulating to higher levels than AMP during the course of the assays. Acetone carboxylase did not have inorganic pyrophosphatase activity. Acetone carboxylase exhibited a V max for acetone carboxylation of 0.225 mol acetoacetate formed min ؊1 ⅐mg ؊1at 30°C and pH 7.6 and apparent K m values of 7.80 M (acetone), 122 M (ATP), and 4.17 mM (CO 2 plus bicarbonate). These studies reveal molecular properties of the first bacterial acetone-metabolizing enzyme to be isolated and suggest a novel mechanism of acetone carboxylation coupled to ATP hydrolysis and AMP and inorganic phosphate formation.Acetone is a toxic molecule that is produced biologically by the fermentative metabolism of certain anaerobic bacteria and during mammalian starvation (1, 2). Acetone is known to undergo further metabolic transformations in microbes and higher organisms, and a variety of diverse bacteria have been found to grow using acetone as a source of carbon and energy (see refs. 3-5 and references cited therein). Studies of acetoneutilizing bacteria have provided evidence for the existence of two distinct pathways of acetone metabolism. For some aerobic bacteria, acetone metabolism has been proposed to proceed by an O 2 -dependent, monooxygenase-catalyzed oxidation producing acetol (hydroxyacetone) as the initial product (4, 6, 7). For other bacteria, including all anaerobes, acetone metabolism has been proposed to proceed by a CO 2 -dependent carboxylation-producing acetoacetate or an acetoacetyl derivative as the initial product (8-10). While in vivo and in vitro studies have provided some evidence supporting these proposed bacterial pathways (6-8, 11-13), the enzymes responsible for initiating acetone catabolism have not been purified to date. One bacterium capable of using acetone as a source of carbon and energy is Xanthobacter strain Py2, an obligately aerobic, Gram-negative bacterium (14). The metabolism of acetone by Xanthobacter Py2 was recently shown to proceed by a CO 2 -dependent pathway analogous to that discussed above (3). The carboxylation of acetone to...

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“…Subsequently, evidence has been obtained that other anaerobic bacteria, including sulfate-reducers Janssen and Schink 1995b, c), denitrifiers (Bonnet-Smits et al 1988;Platen and Schink 1989), and fermentative enrichments (Platen and Schink 1987) metabolize acetone via carboxylation to form acetoacetate or an acetoacetyl derivative. Most evidence supporting CO 2 fixation in anaerobic acetone metabolism has been obtained from whole cell studies.…”

Section: Carbon Dioxide Fixation In Anaerobic Acetone Metabolismmentioning

confidence: 98%

New roles for CO 2 in the microbial metabolism of aliphatic epoxides and ketones

Ensign

Small

Allen

et al. 1998

Archives of Microbiology

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Short-chain aliphatic epoxides and ketones are two classes of toxic organic compounds formed biogenically and anthropogenically. In spite of their toxicity, these compounds are utilized as primary carbon and energy sources or are generated as intermediate metabolites in the metabolism of other compounds (e.g., alkenes, alkanes, and secondary alcohols) by a number of diverse bacteria. One bacterium capable of using both classes of compounds is the gram-negative aerobe Xanthobacter strain Py2. Studies of epoxide and ketone (acetone) metabolism by Xanthobacter strain Py2 have revealed a central role for CO2 in these processes. Both classes of compounds are metabolized by carboxylation reactions that produce beta-keto acids as products. The epoxide- and ketone-converting enzymes are distinct carboxylases with molecular properties and cofactor requirements unprecedented for other carboxylases. Epoxide carboxylase is a four-component multienzyme complex that requires NADPH and NAD+ as cofactors. In the course of epoxide carboxylation, a transhydrogenation reaction occurs wherein NADPH undergoes oxidation and NAD+ undergoes reduction. Acetone carboxylase is a multimeric (three-subunit) ATP-dependent enzyme that forms AMP and inorganic phosphate as ATP hydrolysis products in the course of acetone carboxylation. Recent studies have demonstrated that acetone metabolism in diverse anaerobic bacteria (sulfate reducers, denitrifiers, phototrophs, and fermenters) also proceeds by carboxylation reactions. ATP-dependent acetone carboxylase activity has been demonstrated in cell-free extracts of the anaerobic acetone-utilizers Rhodobacter capsulatus, Rhodomicrobium vannielii, and Thiosphaera pantotropha. These studies have identified new roles for CO2 as a cosubstrate in the metabolism of two classes of important xenobiotic compounds. In addition, two new classes of carboxylases have been identified, the investigation of which promises to reveal new insights into biological strategies for the fixation of CO2 to organic substrates.

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Anaerobic Degradation of Acetone and Higher Ketones via Carboxylation by Newly Isolated Denitrifying Bacteria

Cited by 35 publications

References 25 publications

Photocatabolism of acetone by nonsulfur purple bacteria

Photocatabolism of acetone by nonsulfur purple bacteria

Purification and characterization of acetone carboxylase from Xanthobacter strain Py2

New roles for CO 2 in the microbial metabolism of aliphatic epoxides and ketones

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