Searching for principles of microbial physiology

Area of Science:

• Microbiology
• Systems Biology
• Evolutionary Biology

Background:

• Investigates the widespread occurrence of similar physiological behaviors across evolutionarily distinct microorganisms.
• Addresses the prevalence of transitions to lower-ATP yield metabolisms and the inverse relationship between fast growth and stress tolerance.
• Explores whether common selective pressures and physicochemical constraints drive these microbial regularities.

Purpose of the Study:

• To present a broadly applicable theory that predicts common microbiological behaviors.
• To outline the foundations of this theory, integrating principles from evolutionary biology, enzyme biochemistry, metabolism, cell composition, and steady-state growth.
• To explain the current status of this theory for microbiologists, including its roots, predictions, and experimental evidence.

Main Methods:

• Development of a theoretical framework based on fundamental biological and physical principles.
• Integration of experimental data from microbial systems biology over the past two decades.
• Formulation of predictions regarding protein expression costs/benefits, growth constraints, and optimal metabolism for growth rate maximization.

Main Results:

• Microorganisms frequently optimize for growth rate maximization, even under stressful conditions.
• Microbes tend to express optimal metabolisms and metabolic proteins at concentrations that align with theoretical predictions.
• Comparisons between theoretical predictions and experimental data support the proposed framework.

Conclusions:

• A unified theory, grounded in basic biological principles, can explain common microbial behaviors and physiological regularities.
• The theory accurately predicts microbial strategies for growth and metabolism under various conditions, including stress.
• Future research directions involve further experimental validation and refinement of the theoretical model.