Markus Hollmann

Publications

• Toxicity of Methylated Bismuth Compounds Produced by Intestinal Microorganisms to Bacteroides thetaiotaomicron, a Member of the Physiological Intestinal Microbiota.

  Beatrix Bialek, Roland A Diaz-Bone, Dominik Pieper, Markus Hollmann, Reinhard Hensel

  Journal of toxicology. 01/2011; 2011:608349.

  Methanoarchaea have an outstanding capability to methylate numerous metal(loid)s therefore producing toxic and highly mobile derivatives. Here, we report that the production of methylated bismuth species by the methanoarchaeum Methanobrevibacter smithii, a common member of the human intestine, impai... [more] Methanoarchaea have an outstanding capability to methylate numerous metal(loid)s therefore producing toxic and highly mobile derivatives. Here, we report that the production of methylated bismuth species by the methanoarchaeum Methanobrevibacter smithii, a common member of the human intestine, impairs the growth of members of the beneficial intestinal microbiota at low concentrations. The bacterium Bacteroides thetaiotaomicron, which is of great importance for the welfare of the host due to its versatile digestive abilities and its protective function for the intestine, is highly sensitive against methylated, but not against inorganic, bismuth species. The level of methylated bismuth species produced by the methanoarchaeum M. smithii in a coculture experiment causes a reduction of the maximum cell density of B. thetaiotaomicron. This observation suggests that the production of methylated organometal(loid) species in the human intestine, caused by the activity of methanoarchaea, may affect the health of the host. The impact of the species to reduce the number of the physiological intestinal microbiota brings an additional focus on the potentially harmful role of methanoarchaea in the intestine of a higher organism.

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• Nachweis der Biomethylierung von Bismut in humanen Leberzellen

  Markus Hollmann, Gabriele Zimmer, Jens Boertz, Jörg Hippler, Alfred Vitalis Hirner, Albert Wolfgang Rettenmeier, Elke Dopp

  Arbeitsmedizin, Sozialmedizin, Umweltmedizin. 01/2010; 45:349.

• Each metal species is different

  M. Hollmann

  Nachrichten Aus Der Chemie. 01/2010; 58(11):1148-1150.

• Parallel on-line detection of a methylbismuth species by hyphenated GC/EI-MS/ICP-MS technique as evidence for bismuth methylation by human hepatic cells.

  Markus Hollmann, Jens Boertz, Elke Dopp, Joerg Hippler, Alfred Vitalis Hirner

  Metallomics : integrated biometal science. 01/2010; 2(1):52-6.

  Methylation of metal(loid)s by bacteria or even mammals is a well known process that can lead to increased toxicity for humans. Nevertheless, reliable analytical techniques and tools are indispensable in speciation analysis of trace elements, especially since environmental or biological samples are ... [more] Methylation of metal(loid)s by bacteria or even mammals is a well known process that can lead to increased toxicity for humans. Nevertheless, reliable analytical techniques and tools are indispensable in speciation analysis of trace elements, especially since environmental or biological samples are usually characterised by complex matrices. Here the methylating capability of hepatic cells was observed in vitro. HepG2 cells were incubated with colloidal bismuth subcitrate, bismuth cysteine and bismuth glutathione, respectively for a period of 24 h. For identification the cell lysate was ethylated by sodium tetraethyl borate under neutral conditions. After cryo focussing by purge and trap, the bismuth speciation was carried out via GC/EI-MS/ICP-MS. Colloidal bismuth subcitrate and bismuth cysteine were methylated by HepG2 cells, while no methylated bismuth species was detected after incubation with bismuth glutathione.

• Investigation of bismuth metabolism via mass spectrometric techniques

  Jens Boertz, Markus Hollmann, Jörg Hippler, Frank Mosel, Margareta Sulkowski, Alfred Vitalis Hirner, Albert Wolfgang Rettenmeier

  Umweltmed Forsch Prax. 01/2009; 14(5):271-272.

• Synthesis and isolation of methyl bismuth cysteine and its definitive identification by high resolution mass spectrometry

  J. Hippler, M. Hollmann, H. Juerling, A. V. Hirner

  Chemical Papers. 01/2009; 63(6):742-744.

  After the synthesis and isolation of methylated bismuth cysteine, its initial identification by IR-spectroscopy was performed, whereas for definitive identification, high resolution mass spectrometry (ESI-TOF-MS and LTQ Orbitrap) was carried out.... [more] After the synthesis and isolation of methylated bismuth cysteine, its initial identification by IR-spectroscopy was performed, whereas for definitive identification, high resolution mass spectrometry (ESI-TOF-MS and LTQ Orbitrap) was carried out.

• Analysis of volatile arsenic compounds formed by intestinal microorganisms: rapid identification of new metabolic products by use of simultaneous EI-MS and ICP-MS detection after gas chromatographic separation

  R. A. Diaz-Bone, M. Hollmann, O. Wuerfel, D. Pieper

  Journal of Analytical Atomic Spectrometry. 01/2009; 24(6):808-814.

  For the investigation of biotransformation processes of heteroelements in the environment, both molecular and element-sensitive detection systems are used in hyphenation to chromatographic separation. In this work, we studied the potential of our recently developed gas chromatographic system with pa... [more] For the investigation of biotransformation processes of heteroelements in the environment, both molecular and element-sensitive detection systems are used in hyphenation to chromatographic separation. In this work, we studied the potential of our recently developed gas chromatographic system with parallel electron impact mass spectrometry and inductively coupled plasma mass spectrometry (GC/EI-MS/ICP-MS) for non-target screening and subsequent identification of volatile arsenic compounds formed by fecal microorganisms. By combining the strengths of element-sensitive detection by ICP-MS and molecular identification by EI-MS, it was possible to identify five mixed arsenic/sulfur species (Me2AsSH, dimethyl-mercapto-arsine, Me2AsSMe, dimethyl-methylthio-arsine, Me2AsSSMe, dimethyl-methyldithio-arsine, (Me2As)(2)S, thio-bis(dimethylarsine) and MeAs(SMe)(SEt), methyl-methylthio-ethylthio-arsine) as well as one mixed arsenic/selenium compound (Me2AsSeMe, dimethyl-methylseleno-arsine) in the headspace of fecal incubations. Identification of all compounds was verified by synthesis experiments. Three of these species, namely Me2AsSeMe, (Me2As)(2)S and MeAs(SMe)(SEt), have not been described in environmental or human matrices before. Finally, the advantages of elemental and molecular detection after gas chromatographic separation are discussed.