Carbon Monoxide, Hydrogen, and Formate Metabolism during Methanogenesis from Acetate by Thermophilic Cultures of Methanosarcina and Methanothrix Strains.

Section of Microbiology, Wing Hall, Cornell University, Ithaca, New York 14853.
Applied and Environmental Microbiology (Impact Factor: 3.67). 11/1992; 58(10):3323-9.
Source: PubMed


CO and H(2) have been implicated in methanogenesis from acetate, but it is unclear whether they are directly involved in methanogenesis or electron transfer in acetotrophic methanogens. We compared metabolism of H(2), CO, and formate by cultures of the thermophilic acetotrophic methanogens Methanosarcina thermophila TM-1 and Methanothrix sp. strain CALS-1. M. thermophila accumulated H(2) to partial pressures of 40 to 70 Pa (1 Pa = 0.987 x 10 atm), as has been previously reported for this and other Methanosarcina cultures. In contrast, Methanothrix sp. strain CALS-1 accumulated H(2) to maximum partial pressures near 1 Pa. Growing cultures of Methanothrix sp. strain CALS-1 initially accumulated CO, which reached partial pressures near 0.6 Pa (some CO came from the rubber stopper) during the middle of methanogenesis; this was followed by a decrease in CO partial pressures to less than 0.01 Pa by the end of methanogenesis. Accumulation or consumption of CO by cultures of M. thermophila growing on acetate was not detected. Late-exponential-phase cultures of Methanothrix sp. strain CALS-1, in which the CO partial pressure was decreased by flushing with N(2)-CO(2), accumulated CO to 0.16 Pa, whereas cultures to which ca. 0.5 Pa of CO was added consumed CO until it reached this partial pressure. Cyanide (1 mM) blocked CO consumption but not production. High partial pressures of H(2) (40 kPa) inhibited methanogenesis from acetate by M. thermophila but not by Methanothrix sp. strain CALS-1, and 2 kPa of CO was not inhibitory to M. thermophila but was inhibitory to Methanothrix sp. strain CALS-1. Levels of CO dehydrogenase, hydrogenase, and formate dehydrogenase in Methanothrix sp. strain CALS-1 were 9.1, 0.045, and 5.8 mumol of viologen reduced min mg of protein. These results suggest that CO plays a role in Methanothrix sp. strain CALS-1 similar to that of H(2) in M. thermophila and are consistent with the conclusion that CO is an intermediate in a catabolic or anabolic pathway in Methanothrix sp. strain CALS-1; however, they could also be explained by passive equilibration of CO with a metabolic intermediate.

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    • "As discussed previously, heterotrophic respiration with TEAs likely played a minor role in C mineralization in the present study and hence was not a significant source of acetate production. Acetate can also be produced through the process of homoacetogenesis (i.e., acetate formation from CO 2 and H 2 ), but thermodynamics suggests that hydrogenotrophic methanogens should outcompete homoacetogens for their common substrate, H 2 (Zinder and Anguish, 1992), except possibly at low temperature when H 2 is sufficient (Hoehler et al., 1999; Kotsyurbenko et al., 2001). In the present study, we did not measure H 2 concentrations , but we did determine rates of homoacetogenesis in samples near their native pHs by quantifying the incorporation of 14 CO 3 À into acetate (unpublished data). "
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    Soil Biology and Biochemistry 11/2012; 54:36–47. DOI:10.1016/j.soilbio.2012.05.015 · 3.93 Impact Factor
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    • "In addition, CO is consumed by both aerobic (Bartholomew and Alexander 1979; King 1999a, 2003; Rich and King 1999; King and Hungria 2002) and anaerobic (Zinder and Anguish 1992; Davidova et al. 1994; Rich and King 1999) microbial processes in soils and sediments. Furthermore, some soil bacteria, including human pathogens of the genus Mycobacterium, are capable of growth on CO as a carbon and energy source (King 2003). "
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    ABSTRACT: Dissolved carbon monoxide (CO) is present in ground water produced from a variety of aquifer systems at concentrations ranging from 0.2 to 20 nanomoles per liter (0.0056 to 0.56 microg/L). In two shallow aquifers, one an unconsolidated coastal plain aquifer in Kings Bay, Georgia, and the other a fractured-bedrock aquifer in West Trenton, New Jersey, long-term monitoring showed that CO concentrations varied over time by as much as a factor of 10. Field and laboratory evidence suggests that the delivery of dissolved oxygen to the soil zone and underlying aquifers by periodic recharge events stimulates oxic metabolism and produces transiently high CO concentrations. In between recharge events, the aquifers become anoxic and more substrate limited, CO is consumed as a carbon source, and CO concentrations decrease. According to this model, CO concentrations provide a transient record of oxic metabolism affecting ground water systems after dissolved oxygen has been fully consumed. Because the delivery of oxygen affects the fate and transport of natural and anthropogenic contaminants in ground water, CO concentration changes may be useful for identifying predominantly anoxic ground water systems subject to periodic oxic or microaerophilic conditions.
    Ground Water 05/2007; 45(3):272-80. DOI:10.1111/j.1745-6584.2007.00284.x · 2.31 Impact Factor
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    • "M. thermophila has a rapid growth rate (12-h doubling time), which allows synthesis to proceed more rapidly than isotope exchange. The culture also produces little hydrogen (H 2 ) as a metabolic byproduct (Zinder and Anguish, 1992), avoiding any problems with H 2 oxidation confusing the CH 4 oxidation rate measurements. M. thermophila is also capable of utilizing acetate more completely (10 –20 ␮M threshold) than other aceticlastic methanogens (Min and Zinder, 1989), which allows the synthesis to be performed with small quantities of radioactivity, but at high specific activity. "
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