Metabolism of acetylene and acetaldehyde by <i>Rhodococcus rhodochrous</i>

Germon, Jean-Claude; Knowles, Roger

doi:10.1139/m88-045

Cited by 14 publications

(9 citation statements)

References 17 publications

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“…Until recently, attempts to demonstrate this enzyme activity in cell extracts of P. acetylenicus have failed (27,36). Also the aerobic acetylene-degrading bacteria Mycobacterium lacticola, Nocardia rhodochrous, Rhodococcus strain A1, and Rhodococcus rhodochrous have been reported to convert acetylene to acetaldehyde (7,16,20,25); the reaction was proposed to be catalyzed by an acetylene hydratase activity. Yet acetylene hydratase activity could be demonstrated in cell extracts of Rhodococcus strain A1 only when the assay was performed under anoxic conditions (16).…”

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confidence: 99%

Purification and characterization of acetylene hydratase of Pelobacter acetylenicus, a tungsten iron-sulfur protein

1995

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Acetylene hydratase of the mesophilic fermenting bacterium Pelobacter acetylenicus catalyzes the hydration of acetylene to acetaldehyde. Growth of P. acetylenicus with acetylene and specific acetylene hydratase activity depended on tungstate or, to a lower degree, molybdate supply in the medium. The specific enzyme activity in cell extract was highest after growth in the presence of tungstate. Enzyme activity was stable even after prolonged storage of the cell extract or of the purified protein under air. However, enzyme activity could be measured only in the presence of a strong reducing agent such as titanium(III) citrate or dithionite. The enzyme was purified 240-fold by ammonium sulfate precipitation, anion-exchange chromatography, size exclusion chromatography, and a second anion-exchange chromatography step, with a yield of 36%. The protein was a monomer with an apparent molecular mass of 73 kDa, as determined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The isoelectric point was at pH 4.2. Per mol of enzyme, 4.8 mol of iron, 3.9 mol of acid-labile sulfur, and 0.4 mol of tungsten, but no molybdenum, were detected. The K m for acetylene as assayed in a coupled photometric test with yeast alcohol dehydrogenase and NADH was 14 M, and the V max was 69 mol ⅐ min ؊1 ⅐ mg of protein ؊1. The optimum temperature for activity was 50؇C, and the apparent pH optimum was 6.0 to 6.5. The N-terminal amino acid sequence gave no indication of resemblance to any enzyme protein described so far.The strictly anaerobic fermenting bacterium Pelobacter acetylenicus converts the unsaturated hydrocarbon ethine (trivial name, acetylene) to acetate and ethanol via acetaldehyde as an intermediate (36). The first step of the fermentation pathway, the hydration of acetylene to acetaldehyde, is catalyzed by the enzyme acetylene hydratase. The reaction is highly exergonic: C 2 H 2 ϩ H 2 O 3 CH 3 CHO (⌬GЊЈ ϭ Ϫ111.9 kJ/mol) (36). Until recently, attempts to demonstrate this enzyme activity in cell extracts of P. acetylenicus have failed (27,36). Also the aerobic acetylene-degrading bacteria Mycobacterium lacticola, Nocardia rhodochrous, Rhodococcus strain A1, and Rhodococcus rhodochrous have been reported to convert acetylene to acetaldehyde (7,16,20,25); the reaction was proposed to be catalyzed by an acetylene hydratase activity. Yet acetylene hydratase activity could be demonstrated in cell extracts of Rhodococcus strain A1 only when the assay was performed under anoxic conditions (16). Therefore, acetylene appears to be the only hydrocarbon that is converted in the presence and absence of molecular oxygen by the same type of enzyme (36).Tungsten-containing enzymes have been reported so far to catalyze redox reactions of a low reduction potential (E 0 Ј Ͻ Ϫ400 mV), such as those involving formate dehydrogenase of Clostridium thermoaceticum (51) and Clostridium formicoaceticum (13), aldehyde ferredoxin oxidoreductase of Pyrococcus furiosus (30), formaldehyde ferredoxin oxidoreductase of Thermococcus litoralis (31), carboni...

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Purification and characterization of acetylene hydratase of Pelobacter acetylenicus, a tungsten iron-sulfur protein

1995

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“…Nocardia rhodochrous can utilize acetylene gas [22], but our isolate did not utilize it. Rosner et al [23] and Germon et al [24] reported the utilization of acetylene by Rhodococcus ruber and Rhodococcus rhodochrous E5, respectively, but our other isolate, R. opacus NK0506, did not utilize acetylene as a sole carbon source (data not shown). Usually nitrogenase can degrade acetylene to ethylene, and it has been applied to the analysis of nitrogenase activity on root nodules.…”

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confidence: 54%

Isolation and properties of a 2-chlorovinylarsonic acid-degrading microorganism

Nakamiya

Nakayama

Ito

et al. 2009

Journal of Hazardous Materials

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“…In aerated soils, net C mic was negative in the entire range of consumed C 2 H 2 , while in flooded soils, net C mic showed positive values when the utilized acetylene was greater than 0.33 mg C 2 H 2 -C g −1 , i.e., about 13 mmol C 2 H 2 kg −1 (y=0.498x−0.123, R 2 =0.85; see Fig. In the experiment with isolated soil bacterium (Rodococcus rhodochrous), Germon and Knowles (1988) observed that acetylene was quantitatively transformed to acetaldehyde, ethanol, acetate, CO 2 , and biomass in proportions which varied with culture age and temperature. Reduction of the microbial biomass (net C mic <0) occurred when net respiration was lower than 22 mmol CO 2 kg −1 and 13 mmol O 2 kg −1 , but in flooded variants increased with more intensive respiration (see Fig.…”

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confidence: 95%

“…Smith et al (1973) reported that moist, but not sterilized soils have the capacity to sorb small amounts of C 2 H 2 . (Kanner and Bartha 1979;de Bont and Peck 1980;Germon and Knowles 1988;Tam et al 1983) and anaerobic Pelobacter acetylenicus (Schink 1985). (Kanner and Bartha 1979;de Bont and Peck 1980;Germon and Knowles 1988;Tam et al 1983) and anaerobic Pelobacter acetylenicus (Schink 1985).…”

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How much oxygen is needed for acetylene to be consumed in soil?

et al. 2011

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Purpose Acetylene (C 2 H 2 ) is employed for the quantification of important biological processes such as nitrogen fixation, nitrous oxide reduction, ammonium and methane oxidation, and methanogenesis. Although acetylene is not a natural product, the ability of bacteria to grow on C 2 H 2 is a phenomenon common to soils and sediments. Our experiment was designed to study the modification of CO 2 production, O 2 uptake and microbial biomass (C mic ) in soil in response to the consumption of added acetylene. Materials and methods Two soils (peat-muck and Eutric Cambisol) were incubated under well aerated (60% water holding capacity [WHC]) or flooded conditions, and enriched with C 2 H 2 in the range 0.1-10 kPa (initially, 0.434-63.4 mmol C 2 H 2 kg −1 ) at a constant temperature of 20°C. Gases were measured chromatographically, while C mic was measured by the physiological SIR (substrate-induced respiration) method based on the initial response of microorganisms to glucose amendment. We used a simple calculation of net CO 2 , net O 2 and net C mic (as differences between amended and not amended soils) to estimate the contribution of C 2 H 2 to the total respiration and microbial growth during the incubation. Results and discussion Peat-muck soil consumed more C 2 H 2 than Cambisol (maximum 54.03 vs. 19.25 mmol kg −1 , p<0.001). Acetylene utilization was faster and larger in flooded than in wet soils (16.2 and 7.81 mmol kg −1 , respectively, p<0.05), and followed the tendency observed for C mic . Depending on C 2 H 2 enrichment, air-water conditions, and soil tested, both reduction and stimulation of measured activities were observed in response to acetylene consumption. Low C 2 H 2 uptake, especially in Cambisol incubated at 60% WHC, resulted in the reduction of soil respiration and biomass (by 1-29%). Large C 2 H 2 consumption in flooded soils stimulated CO 2 production, O 2 uptake and C mic , even by 78%, 72% and 43%, respectively. Net CO 2 , net O 2 , and net C mic were linearly positively related to the quantity of consumed C 2 H 2 (p<0.001).Conclusions Acetylene utilization was a combined effect of initial C 2 H 2 , soil properties, and air-water status. The amount of consumed C 2 H 2 was the highest in flooded peat-muck soil enriched with 10 kPa, and lowest in Cambisol at 60% WHC with 0.1 kPa C 2 H 2 . Consumption of 1 mol acetylene induced production of 0.5 mol CO 2 , and uptake of 0.4 mol O 2 . Low acetylene consumption (<6 mmol kg −1 ) resulted in reduction of both soil respiration and microbial biomass.

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Metabolism of acetylene and acetaldehyde by Rhodococcus rhodochrous

Cited by 14 publications

References 17 publications

Purification and characterization of acetylene hydratase of Pelobacter acetylenicus, a tungsten iron-sulfur protein

Purification and characterization of acetylene hydratase of Pelobacter acetylenicus, a tungsten iron-sulfur protein

Isolation and properties of a 2-chlorovinylarsonic acid-degrading microorganism

How much oxygen is needed for acetylene to be consumed in soil?

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