Abstract
The kinetics of inhibition of CH(inf4) oxidation by NH(inf4)(sup+), NO(inf2)(sup-), and NO(inf3)(sup-) in a humisol was investigated. Soil slurries exhibited nearly standard Michaelis-Menten kinetics, with half-saturation constant [K(infm(app))] values for CH(inf4) of 50 to 200 parts per million of volume (ppmv) and V(infmax) values of 1.1 to 2.5 nmol of CH(inf4) g of dry soil(sup-1) h(sup-1). With one soil sample, NH(inf4)(sup+) acted as a simple competitive inhibitor, with an estimated K(infi) of 8 (mu)M NH(inf4)(sup+) (18 nM NH(inf3)). With another soil sample, the response to NH(inf4)(sup+) addition was more complex and the inhibitory effect of NH(inf4)(sup+) was greater than predicted by a simple competitive model at low CH(inf4) concentrations (<50 ppmv). This was probably due to NO(inf2)(sup-) produced through NH(inf4)(sup+) oxidation. Added NO(inf2)(sup-) was inherently more inhibitory of CH(inf4) oxidation at low CH(inf4) concentrations, and more NO(inf2)(sup-) was produced as the CH(inf4)-to-NH(inf4)(sup+) ratio decreased and the competitive balance shifted. NaNO(inf3) was a noncompetitive inhibitor of CH(inf4) oxidation, but inhibition was evident only at >10 mM concentrations, which also altered soil pHs. Similar concentrations of NaCl were also inhibitory of CH(inf4) oxidation, so there may be no special inhibitory mechanism of nitrate per se.
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- Adamsen A. P., King G. M. Methane consumption in temperate and subarctic forest soils: rates, vertical zonation, and responses to water and nitrogen. Appl Environ Microbiol. 1993 Feb;59(2):485–490. doi: 10.1128/aem.59.2.485-490.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bédard C., Knowles R. Physiology, biochemistry, and specific inhibitors of CH4, NH4+, and CO oxidation by methanotrophs and nitrifiers. Microbiol Rev. 1989 Mar;53(1):68–84. doi: 10.1128/mr.53.1.68-84.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ferenci T., Strom T., Quayle J. R. Oxidation of carbon monoxide and methane by Pseudomonas methanica. J Gen Microbiol. 1975 Nov;91(1):79–91. doi: 10.1099/00221287-91-1-79. [DOI] [PubMed] [Google Scholar]
- Jollie D. R., Lipscomb J. D. Formate dehydrogenase from Methylosinus trichosporium OB3b. Purification and spectroscopic characterization of the cofactors. J Biol Chem. 1991 Nov 15;266(32):21853–21863. [PubMed] [Google Scholar]
- King G. M., Schnell S. Ammonium and Nitrite Inhibition of Methane Oxidation by Methylobacter albus BG8 and Methylosinus trichosporium OB3b at Low Methane Concentrations. Appl Environ Microbiol. 1994 Oct;60(10):3508–3513. doi: 10.1128/aem.60.10.3508-3513.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schnell S., King G. M. Mechanistic analysis of ammonium inhibition of atmospheric methane consumption in forest soils. Appl Environ Microbiol. 1994 Oct;60(10):3514–3521. doi: 10.1128/aem.60.10.3514-3521.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]