U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Thermodynamic Links Between Substrate, Enzyme, and Microbial Dynamics
Published: February 21, 2018
Posted: June 22, 2018

A research team from Lawrence Berkeley National Laboratory (LBNL) presented a mechanistic approach linking temperature dependencies of microbial reactions important in soil biogeochemistry.

The Science
The team introduced a simple but comprehensive mechanistic approach that uses thermodynamics and biochemical kinetics to link reaction rates, Michaelis-Menten constants, biomass yields, mortality rates, and temperature for soil microbes.

The Impact
Accurate prediction of microbially-mediated reaction rates is critical for soil biogeochemical models. Our approach uses thermodynamics and biochemical kinetics to link the dominant controlling factors on these rates, including their temperature dependencies.

A research team from LBNL introduced a simple but comprehensive mechanistic approach that uses thermodynamics and biochemical kinetics to describe and link microbial reaction rates, Michaelis-Menten constants, biomass yields, mortality rates, and temperature. The temperature control is exerted by catabolic enthalpy at low temperatures and catabolic entropy at high temperatures, whereas changes in cell and enzyme-substrate heat capacity shift the anabolic electron use efficiency and the maximum reaction velocity. We show that cells have optimal growth when the catabolic (differential) free energy of activation decreases the cell free energy harvest required to duplicate their internal structures if electrons for anabolism are available. With the described approach, we accurately predicted observed glucose fermentation and ammonium nitrification dynamics across a wide temperature range with a minimal number of thermodynamics parameters, and we highlight how kinetic parameters are linked to each other using first principles. These results can inform new microbe-explicit biogeochemistry models, such as those being developed in E3SM.

Contacts (BER PM)
Daniel Stover  

(PI Contact)
William J. Riley
Lawrence Berkeley National Laboratory

This research was supported by the Office of Science, Office of Biological and Environmental Research of the US Department of Energy under contract no. DE-AC02- 05CH11231 as part of the LBNL TES Scientific Focus Area project.

Maggi, F. M., F. H. M. Tang, and W. J. Riley. “The thermodynamic links between substrate, enzyme, and microbial dynamics in Michaelis-Menten-Monod kinetics.” International J. of Chemical Kinetics 50(5): 343-356 (2018). [DOI:10.1002/kin.21163]

Topic Areas:

  • Research Area: Terrestrial Ecosystem Science

Division: SC-23.1 Climate and Environmental Sciences Division, BER


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