ABSTRACT: This model is described in these articles:
Casini, I., McCubbin, T., Esquivel-Elizondo, S., Luque, G.G., Evseeva, D., Fink, C., Beblawy, S., Youngblut, N.D., Aristilde, L., Huson, D., Drager, A., Ley, R., Marcellin, E., Angenent, L.T., Molitor, B. 2023. An integrated systems biology approach reveals differences in formate metabolism in the genus Methanothermobacter. Iscience, 26(10).
Casini, I., McCubbin, T., Esquivel-Elizondo, S., Luque, G.G., Evseeva, D., Fink, C., Beblawy, S., Youngblut, N.D., Aristilde, L., Huson, D., Drager, A., Ley, R., Marcellin, E., Angenent, L.T., Molitor, B. 2022. An integrated systems-biology platform for power-to-gas technology. bioRxiv, 2022.12.30.522236.
Methanogenesis allows methanogenic archaea (methanogens) to generate cellular energy for their growth while producing methane. Hydrogenotrophic methanogens thrive on carbon dioxide and molecular hydrogen as sole carbon and energy sources. Thermophilic and hydrogenotrophic Methanothermobacter spp. have been recognized as robust biocatalysts for a circular carbon economy and are now applied in power-to-gas technology. Here, we generated the first manually curated genome-scale metabolic reconstruction for three Methanothermobacter spp.. We investigated differences in growth performance of three wild-type strains and one genetically engineered strain in two independent chemostat bioreactor experiments, first, with molecular hydrogen and carbon dioxide, and second, with sodium formate. In the first experiment, we found the highest methane production rate for Methanothermobacter thermautotrophicus ΔH, while Methanothermobacter marburgensis Marburg reached the highest biomass growth rate. Transcriptomics and proteomics data sets from these steady-state bioreactors, in combination with the implementation of a pan-model that contains combined reactions from all three microbes, allowed us to perform an interspecies comparison. While the observed differences in the growth behavior cannot be fully explained, the comparison enabled us to identify crucial differences in growth-related pathways such as formate anabolism. In the second experiment, we found stable growth with a M. thermautotrophicus ΔH plasmid-carrying strain on formate with similar performance parameters compared to wild-type Methanothermobacter thermautotrophicus Z-245. The results of the two studies demonstrate the advantages of an integrative approach combining fermentation and omics data with genome-scale modeling to reveal knowledge gaps of archaeal metabolisms and the biotechnological potential of Methanothermobacter spp. as production platform hosts.
Isabella Casini 
