Media type: E-Article Title: Biomethylation of bismuth by the methanogen Methanobacterium formicicum Contributor: Michalke, Klaus; Meyer, Jörg; Hirner, Alfred V.; Hensel, Reinhard imprint: Wiley, 2002 Published in: Applied Organometallic Chemistry Language: English DOI: 10.1002/aoc.288 ISSN: 0268-2605; 1099-0739 Keywords: Inorganic Chemistry ; General Chemistry Origination: Footnote: Description: <jats:title>Abstract</jats:title><jats:p>In this study the bioconversion of bismuth to volatile derivatives was investigated in cultures of the common sewage sludge methanogen <jats:italic>Methanobacterium formicicum</jats:italic>. The production of volatile bismuth compounds was analysed during growth of <jats:italic>M. formicicum</jats:italic> with respect to the concentration and chemical formulation of the applied bismuth. The main volatile bismuth compound detected in the culture headspace was trimethylbismuth (TMBi), with a maximum conversion rate of up to 2.6 ± 1.8% from spiked 1 µ<jats:sc>M</jats:sc> bismuth nitrate [Bi(NO<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub>] in the culture media. This main compound proved to be stable under the incubation conditions in a CO<jats:sub>2</jats:sub>–H<jats:sub>2</jats:sub> atmosphere. Bismuthine and the partially methylated bismuthines monomethylbismuth hydride and dimethylbismuth hydride were additionally detected in the late exponential growth phase, but only in the presence of low concentrations of spiked Bi(NO<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub> (10 n<jats:sc>M</jats:sc>, 100 n<jats:sc>M</jats:sc>). The conversion of bismuth to TMBi from the bismuth‐containing pharmaceuticals Bismofalk® [containing bismuth subgallate and Bi(NO<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub>] and Noemin® (containing bismuth aluminate) could also be observed, however, with a lower rate than found for Bi(NO<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub>. <jats:italic>In vitro</jats:italic> experiments with crude extracts of <jats:italic>M. formicicum</jats:italic> suggest that the methylation of bismuth is mainly catalysed by enzyme‐catalysed reactions with methylcobalamin as methyl donor. Copyright © 2002 John Wiley & Sons, Ltd.</jats:p>