Thermodynamic electron equivalents model for bacterial yield prediction: modifications and comparative evaluations

Area of Science:

• Biochemical Engineering
• Microbial Physiology
• Thermodynamics

Background:

• Accurate prediction of microbial growth yields is crucial for biotechnology and environmental science.
• Earlier thermodynamic models like TEEM1 had limitations in predicting yields for specific metabolic pathways.
• Understanding energy transfer efficiency is key to refining these models.

Purpose of the Study:

• To revise and improve the thermodynamic model for predicting microbial growth yields (TEEM2).
• To correct for underestimations in yields involving oxygenase-mediated oxidations and single-carbon (C1) compounds.
• To evaluate the impact of energy transfer efficiency on model predictions.

Main Methods:

• Modified an existing thermodynamic model (TEEM1) to create TEEM2.
• Utilized reduction potential and Gibbs free energy calculations for energy release and consumption.
• Determined energy transfer efficiency using extensive literature data on aerobic heterotrophic yield.
• Validated TEEM2 predictions against experimental data for various organic compounds, including those metabolized via oxygenases and C1 compounds.

Main Results:

• Established an energy transfer efficiency of 0.37 for compounds following normal catabolic pathways, yielding 15%-20% prediction precision.
• TEEM2 showed improved, though slightly less accurate, predictions for oxygenase-involved oxidations (8% too high) and C1 compounds (17% too high) compared to TEEM1.
• The revised model demonstrated enhanced predictive capabilities over TEEM1 and other comparative models.

Conclusions:

• TEEM2 offers improved accuracy in predicting microbial growth yields across various conditions, including challenging substrates.
• Energy transfer efficiency is a critical parameter for accurate thermodynamic modeling of microbial growth.
• The refined model provides a valuable tool for optimizing bioprocesses and understanding microbial metabolism.