The effect of oxygen on methanol oxidation by an obligate methanotrophic bacterium studied by in vivo (13)C nuclear magnetic resonance spectroscopy.
13C NMR was used to study the effect of oxygen on methanol oxidation by a type II methanotrophic bacterium isolated from a bioreactor in which methane was used as electron donor for denitrification. Under high (35-25%) oxygen conditions the first step of methanol oxidation to formaldehyde was much faster than the following conversions to formate and carbon dioxide. Due to this the accumulation of formaldehyde led to a poisoning of the cells. A more balanced conversion of (13)C-labelled methanol to carbon dioxide was observed at low (1-5%) oxygen concentrations. In this case, formaldehyde was slowly converted to formate and carbon dioxide. Formaldehyde did not accumulate to inhibitory levels. The oxygen-dependent formation of formaldehyde and formate from methanol is discussed kinetically and thermodynamically.
Costa
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Chemical Engineering Department, University of Salamanca, Plaza de la Merced s/n, 37008 Salamanca, Spain, and Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, 6703 CT Wageningen, Netherlands.
Vecherskaya
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Dijkema
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Stams
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