In this work we use metabolomics and 13C-labeling data to refine central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotrophic bacterium. We demonstrate here that similar to non-methane utilizing methylotrophic alphaproteobacteria the core metabolism of the microbe is represented by several tightly connected metabolic cycles, such as the serine pathway, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle. Both in silico estimations and stable isotope labeling experiments combined with single cell (NanoSIMS) and bulk biomass analyses indicate that a significantly larger portion of the cell carbon (over 60%) is derived from CO2 in this methanotroph. Our13 C-labeling studies revealed an unusual topology of the assimilatory network in which phosph(enol) pyruvate/pyruvate interconversions are key metabolic switches. A set of additional pathways for carbon fixation are identified and discussed.
Keywords: methanotrophic proteobacteria, serine cycle, ethylmalonyl-CoA pathway in methanotrophs, metabolic fluxes labeling
Citation: Yang S, Matsen JB, Konopka M, Green-Saxena A, Clubb J, Sadilek M, Orphan VJ, Beck D and Kalyuzhnaya MG (2013) Global molecular analyses of methane metabolism in methanotrophic Alphaproteobacterium, Methylosinus trichosporium OB3b. Part II. metabolomics and 13C-labeling study. Front. Microbiol. 4:70. doi: 10.3389/fmicb.2013.00070
Received: 01 January 2013; Paper pending published: 28 January 2013;
Accepted: 12 March 2013; Published online: 03 April 2013.
Edited by:Amy V. Callaghan, University of Oklahoma, USA
Reviewed by:Alan A. DiSpirito, Ohio State University, USA
Copyright: © 2013 Yang, Matsen, Konopka, Green-Saxena, Clubb, Sadilek, Orphan, Beck and Kalyuzhnaya. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Marina G. Kalyuzhnaya, Department of Microbiology, University of Washington, Benjamin Hall IRB RM 455, 616 NE Northlake Place, Seattle, WA 98105, USA. e-mail: email@example.com