Comparison of Unitrophic and Mixotrophic Substrate Metabolism by an Acetate-Adapted Strain of Methanosarcina barkeri

Krzycki, Joseph A.; Wolkin, Richard H.; Zeikus, J. G.

doi:10.1128/jb.149.1.247-254.1982

Cited by 117 publications

(53 citation statements)

References 30 publications

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“…In this pathway, CO-DH is the central enzyme of the catabolic pathway. This is in accord with the finding of Krzycki et al [83] that the activity of CO-DH is 5 × higher in cells grown on acetate than in cells grown on CO~ and H: or methanol. It has been proposed that ATP is generated by electron and proton phosphorylation [84].…”

Section: Catabolism Of Aceo'l-coa By Methanogenssupporting

confidence: 93%

The acetyl-CoA pathway of autotrophic growth

Wood

Ragsdale

Pezacka

1986

FEMS Microbiology Letters

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The most direct conceivable route for synthesis of multicarbon compounds from CO: is to join two molecules of CO 2 together to make a 2-carbon compound and then polymerize the 2-carbon compound or add CO 2 successively to the 2-carbon compound to make multicarbon compounds. Recently, it has been demonstrated that the bacterium, Clostridium thermoaceticum, grows autotrophically by such a process. The mechanism involves the reduction of one molecule of CO 2 to a methyl group and then its combination with a second molecule of CO2 and CoA to form acetyl-CoA. We have designated this autotrophic pathway the acetyl-CoA pathway [1]. Evidence is accumulating that this pathway is utilized by other bacteria that grow with CO 2 and H 2 as the source of carbon and energy. This group includes bacteria which, like C. thermoaceticum, produce acetate as a major end product and are called acetogens or acetogenic bacteria. It also includes the methaneproducing bacteria and sulfate-reducing bacteria.The purpose of this review is to examine critically the evidence that the acetyl-CoA pathway occurs in other bacteria by a mechanism that is the same or similar to that found in C. thermoaceticum. For this purpose, the mechanism of the acetyl-CoA pathway, as found in C. thermoaceticum, is described and hypothetical mecha-nims for other organisms are presented based on the acetyl-CoA pathway of C. thermoaceticum. The available data have been reviewed to determine if the hypothetical schemes are in accord with presently known facts. We conclude that the formation of acetyl-CoA by other acetogens, the methanogens and sulphate-reducing bacteria occurs by a mechanism very similar to that of C.therrnoaceticum.

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Section: Catabolism Of Aceo'l-coa By Methanogenssupporting

confidence: 93%

The acetyl-CoA pathway of autotrophic growth

Wood

Ragsdale

Pezacka

1986

FEMS Microbiology Letters

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“…Y XS 10·8 g mol −1 (D 0·046 h −1 , S 0 125 mmol l −1 ) from Table 2 and Y XS 4·0 g mol −1 (D 0·05 h −1 , S 0 150 mmol l −1 ) (Bainotti et al 1998), respectively. The latter value is comparable with that obtained for Methanosarcina barkeri (Y XS 3·9 g mol −1 , m 0·039 h −1 ) on methanol (Krzycki et al 1982).…”

Section: Discussionmentioning

confidence: 82%

“…Therefore, the cell yield coefficient (g mol −1 ) and specific growth rate of Acetobacterium sp. (Y XS 10·8, m 0·046 h −1 , on methanol-formate) are considerably higher than those reported for M. barkeri (Y XS 3·9, m 0·039 h −1 , on methanol) (Krzycki et al 1982).…”

Section: Discussionmentioning

confidence: 99%

Growth kinetics of Acetobacterium sp. on methanol-formate in continuous culture

Bainotti

Nishio

2000

J Appl Microbiol

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A .E . B A IN OT T I A ND N . N IS H IO . 2000.The fermentative metabolism of Acetobacterium sp. grown on methanol-formate in continuous culture is described. The reaction stoichiometry of methanol-formate, including cells, were as follows: CH 3 OH ¦ 1·13HCOOH : 0·87CH 3 COOH ¦ 0·47 cell C. Formate enhanced growth yields by approximately 60% compared with methanol-CO 2 -grown cultures. Comparison of yields on methanol-formate allowed calculation of an energy yield of 1·3 mol ATP per mol acetate formed during homoacetate fermentation. The magnitudes of Y EG , the theoretical maximum yield of Y E , and m, the maintenance coefficient, were determined by growing the organism in methanol-formate and resulted in 16·5 g cell (mol methanol catabolized) −1 and 0·674 mmol methanol catabolized (g cell) −1 h −1 , respectively. It is concluded that formate might replace CO 2 as a source of carboxyl donor.

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“…The P tet vht and P tet vht/ Δ ech mutants were not examined because they do not grow in any medium under non-inducing conditions. Similarly, we did not assay production of methane from acetate, because prior growth on acetate is required to induce the enzymes needed for this activity and most of the hydrogenase mutants are unable to grow under these conditions (20, 21).…”

Section: Resultsmentioning

confidence: 99%

Genetic, biochemical, and molecular characterization ofMethanosarcina barkerimutants lacking three distinct classes of hydrogenase

Mand

Kulkarni

Metcalf

2018

Preprint

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17The methanogenic archaeon Methanosarcina barkeri encodes three distinct 18 types of hydrogenase, whose functions vary depending on the growth substrate. 19These include the F420-dependent (Frh), methanophenazine-dependent (Vht), and 20 ferredoxin-dependent (Ech) hydrogenases. To investigate their physiological roles, 21we characterized a series of mutants lacking each hydrogenase in various 22 40 IMPORTANCE 41Methanogenic archaea are key players in the global carbon cycle due to their 42 ability to facilitate the remineralization of organic substrates in many anaerobic 43 environments. The consequences of biological methanogenesis are far reaching, 44 with impacts on atmospheric methane and CO2 concentrations, agriculture, energy 45 production, waste treatment and human health. The data presented here clarify the 46 in vivo function of hydrogenases during methanogenesis, which in turn deepens our 47 understanding of this unique form of metabolism. This knowledge is critical for a 48 variety of important issues ranging from atmospheric composition to human health. 49 50 Methanogens without cytochromes produce at least four types of 62 hydrogenase; including (i) the electron-bifurcating Mvh hydrogenase, which couples 63 oxidation of hydrogen to reduction of ferredoxin and a mixed coenzyme M-64 coenzyme B disulfide, (ii) the coenzyme F420-dependent hydrogenase, (iii) the [Fe] 65 hydrogenase, which couples hydrogen oxidation to reduction of 66 methenyltetrahydromethanopterin, and (iv) the ferredoxin-dependent, energy-67 converting hydrogenases (4). The first three are cytoplasmic enzymes, which supply 68 the electrons needed to reduce CO2 to methane. The last is a membrane bound 69 multi-subunit complex that couples hydrogenase activity to the 70 production/consumption of the ion-motive force across the cell membrane (hence 71 the designation as "energy-converting"). In non-cytochrome-containing 72 methanogens, these energy-converting hydrogenases are believed to provide low-73 potential electrons, in the form of reduced ferredoxin, needed for anaplerotic 74 reactions (6). 75Methanogens with cytochromes, typified by Methanosarcina barkeri, encode 76 a different set of hydrogenases that includes one cytoplasmic and two membrane-77 bound enzymes (Fig 1) (7). Like the non-cytochrome containing methanogens, M. 78 barkeri produces a cytoplasmic, three-subunit F420-dependent hydrogenase known 79 as Frh (for F420-reducing hydrogenase). Frh is encoded by the four-gene frhADGB 80 operon, which encodes the α, β and γ subunits (FrhA, FrhB and FrhG, respectively), 81 along with the maturation protease FrhD (8). A second locus, freAEGB, encodes 82 proteins that are 86-88% identical to FrhA, FrhB and FrhG, but lacks the gene for the 83 maturation protease FrhD, instead encoding a small protein of unknown function 84 (FrhE). It is not known whether the fre operon is capable of producing an active 85 hydrogenase (8)(9)(10)(11). A membrane-bound hydrogenase linked to the quinone-like 86 electron carrier methanophenazine has, to dat...

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Comparison of Unitrophic and Mixotrophic Substrate Metabolism by an Acetate-Adapted Strain of Methanosarcina barkeri

Cited by 117 publications

References 30 publications

The acetyl-CoA pathway of autotrophic growth

The acetyl-CoA pathway of autotrophic growth

Growth kinetics of Acetobacterium sp. on methanol-formate in continuous culture

Genetic, biochemical, and molecular characterization ofMethanosarcina barkerimutants lacking three distinct classes of hydrogenase

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