Proteomic Analysis of the Hydrogen and Carbon Monoxide Metabolism of Methanothermobacter marburgensis

Martijn Diender, Ricardo Pereira, Hans J. C. T. Wessels, Alfons J. M. Stams, Diana Z. Sousa

Hydrogenotrophic methanogenic archaea are efficient H2 utilizers, but only a few are known to be able to utilize CO. Methanothermobacter thermoautotrophicus is one of the hydrogenotrophic methanogens able to grow on CO, albeit about 100 times slower than on H2 + CO2. In this study, we show that the hydrogenotrophic methanogen Methanothermobacter marburgensis, is able to perform methanogenic growth on H2/CO2/CO and on CO as a sole substrate. To gain further insight in its carboxydotrophic metabolism, the proteome of M. marburgensis, grown on H2/CO2 and H2/CO2/CO, was analyzed. Cultures grown with H2/CO2/CO showed relative higher abundance of enzymes involved in the reductive acetyl-CoA pathway and proteins involved in redox metabolism. The data suggest that the strong reducing capacity of CO negatively affects hydrogenotrophic methanogenesis, making growth on CO as a sole substrate difficult for this type of methanogens. M. marburgensis appears to partly deal with this by up-regulating co-factor regenerating reactions and activating additional pathways allowing for formation of other products, like acetate.