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Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria

Proceedings of the National Academy of Sciences of the United States of America

By:
, , , , , , ,
DOI: 10.1073/pnas.101129798

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Abstract

The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as ???70???) shifts in ??13C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70???) occurs during oxidation of methyl halides by methylotrophic bacteria. We have demonstrated biological fractionation with whole Cells of three methylotrophs (strain IMB-1, strain CC495, and strain MB2) and, to a lesser extent, with the purified cobalamin-dependent methyltransferase enzyme obtained from strain CC495. Thus, the genetic similarities recently reported between methylotrophs, and methanogens with respect to their pathways for C1-unit metabolism are also reflected in the carbon isotopic fractionations achieved by these organisms. We found that only part of the observed fractionation of carbon isotopes could be accounted for by the activity of the corrinoid methyltransferase enzyme, suggesting fractionation by enzymes further along the degradation pathway. These observations are of potential biogeochemical significance in the application of stable carbon isotope ratios to constrain the tropospheric budgets for the ozone-depleting halocarbons, methyl bromide and methyl chloride.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria
Series title:
Proceedings of the National Academy of Sciences of the United States of America
DOI:
10.1073/pnas.101129798
Volume
98
Issue:
10
Year Published:
2001
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Proceedings of the National Academy of Sciences of the United States of America
First page:
5833
Last page:
5837
Number of Pages:
5