Abstract
Methane utilizing bacteria (methanotrophs) are important in both environmental and biotechnological applications, due to their ability to convert methane to multicarbon compounds. However, systems-level studies of methane metabolism have not been carried out in methanotrophs. In this work we have integrated genomic and transcriptomic information to provide an overview of central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotroph. Particulate methane monooxygenase, PQQ-dependent methanol dehydrogenase, the H4MPT-pathway, and NAD-dependent formate dehydrogenase are involved in methane oxidation to CO2. All genes essential for operation of the serine cycle, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle were expressed. PEP-pyruvate-oxaloacetate interconversions may have a function in regulation and balancing carbon between the serine cycle and the EMC pathway. A set of transaminases may contribute to carbon partitioning between the pathways. Metabolic pathways for acquisition and/or assimilation of nitrogen and iron are discussed.
Highlights
Aerobic methanotrophic bacteria are a highly specialized group of microbes utilizing methane as a sole source of carbon and energy (Hanson and Hanson, 1996; Murrell and Jetten, 2009)
GENE EXPRESSION STUDIES Gene expression studies were carried out with M. trichosporium OB3b cultures grown on methane at N (10 mM), Cu (9 μM), and Fe (9 μM) sufficiency conditions
We propose that M. trichosporium OB3b uses the EMC variant of the serine cycle for carbon assimilation
Summary
Aerobic methanotrophic bacteria (methanotrophs) are a highly specialized group of microbes utilizing methane as a sole source of carbon and energy (Hanson and Hanson, 1996; Murrell and Jetten, 2009). Several genomes of methanotrophic bacteria have been sequenced opening new dimensions in characterization of methane metabolism (Ward et al, 2004; Dunfield et al, 2007; Hou et al, 2008; Chen et al, 2010; Stein et al, 2010, 2011; Dam et al, 2012b). Initial genome-based reconstructions of methane metabolism in methanotrophic proteobacteria and Verrucomicrobia have been performed (Ward et al, 2004; Kelly et al, 2005; Hou et al, 2008; Khadem et al, 2011)
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