A microbial community is a complex, dynamic system composed of hundreds of species and their interactions. They are found in oceans, soil, animal guts and plant roots. Each system feeds the Earth's ecosystem and its own growth, as each has its own metabolism that underpins biogeochemical cycles, according to an announcement from the University of Warwick.

The same community-level metabolic rates are exploited in biotechnology for water treatment and bioenergy production from organic waste. Thus, the ability to capture microbial growth rates and metabolic activities within the communities is key for modeling planetary ecosystem dynamics, animal and plant health and biotechnological waste valorization, the university said.

Models of such systems should account for both kinetic and thermodynamic constraints inherent in microbial growth, which is a challenge due to the complexity of these systems.

In "Thermodynamic Modelling of Synthetic Communities Predicts Minimum Free Energy Requirements for Sulfate Reduction & Methanogenesis," a paper published May 6 in the Journal of the Royal Society Interface, researchers from the University of Warwick School of Life Sciences have produced an extendable thermodynamic model for simulating the dynamics of microbial communities.

To develop and calibrate a thermodynamic model of microbial growth and metabolite dynamics in a microbial context, researchers focused on defined anaerobic synthetic communities; these communities break down biodegradable material in the absence of oxygen.

They used a recently developed experimental model system for studying syntrophic (the relationship between individuals of different species, especially bacteria, in which one or both benefit nutritionally from the presence of the other) interactions among sulfate reducers and methanogens, which make up a key part of anaerobic microbial communities.

Researchers found the minimum energy requirement for a given metabolic pathway, providing evidence that experimental data can be used to estimate the energy requirements of microbial pathways and such estimates for methanogenesis (the production of methane) and sulfate reduction, the university said.

"Microbes are crucial in mediating biochemical conversions in the environment. These conversions ultimately allow higher organisms like us and plants to obtain the metabolites they need for living and underpin biogeochemical cycles that make Earth a habitable planet," professor Orkun Soyer with the University of Warwick School of Life Sciences said. "Better understanding these processes requires modeling the biochemical conversions mediated by microbes.

"Our recent work creates a generalizable platform for this purpose and introduces a thermodynamic model of microbial conversions. This model better captures dynamics of metabolic conversions and provides estimates of minimal energy requirements of such conversions from experimental data," he explained.