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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. The team's approach uses thermodynamics and biochemical kinetics to link the dominant controlling factors on these rates, including their temperature dependencies.

Summary
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. The researchers 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, the team accurately predicted observed glucose fermentation and ammonium nitrification dynamics across a wide temperature range with a minimal number of thermodynamics parameters, and the scientists 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 Program Manager
Daniel Stover  
Terrestrial Ecosystem Science, SC-23.1
DanielStover@science.doe.gov

Principal Investigator
William J. Riley
Lawrence Berkeley National Laboratory
Berkeley, CA 94720
wjriley@lbl.gov

Funding
This research was supported by the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science, under contract no. DE-AC02- 05CH11231 as part of the Lawrence Berkeley National Laboratory's Terrestrial Ecosystem Science Scientific Focus Area (SFA) project.

Publications
Maggi, F.M., F.H.M. Tang, and W.J. Riley. "The thermokinetic link between substrate, enzyme and microbial dynamics in Michaeli-Menten-Monod kinetics." International Journal of Chemical Kinetics 50(5), 343–356 (2018). [DOI:10.1002/kin.21163]

 

Topic Areas:

  • Research Area: Terrestrial Ecosystem Science

Division: SC-33.1 Earth and Environmental Sciences Division, BER

 

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