Hydrogenotrophic methanogens of the mammalian gut: functionally similar, thermodynamically different -A modelling approach
Abstract
Methanogenic archaea occupy a unique and functionally important niche in the microbial ecosystem inhabiting the gut of mammals. The purpose of this work was to quantitatively characterize the dynamics of methanogenesis by integrating microbiology, thermodynamics and mathematical modelling. For that, in vitro growth experiments were performed with key methanogens from the human and ruminant gut. Additional thermodynamic experiments to quantify the methanogenesis heat flux were performed in an isothermal microcalorimeter. A dynamic model with an energetic-based kinetic function was constructed to describe experimental data. The developed model captures efficiently the dynamics of methanogenesis with concordance correlation coefficients between observations and model predictions of 0.93 for CO2, 0.99 for H2 and 0.97 for CH4. Together, data and model enabled us to quantify species-specific metabolism kinetics and energetic patterns within the group of cytochrome-lacking methanogenic archaea. Using a theoretical exercise, we showed that kinetic information only cannot explain ecological aspects such as microbial coexistence occurring in gut ecosystems. Our results provide new information on the thermodynamics and kinetics of methanogens. This understanding could be useful to (i) construct novel gut models with enhanced prediction capabilities and (ii) devise feed strategies for promoting gut health in mammals and mitigating methane emissions from ruminants.
Origin : Files produced by the author(s)
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