In silico evolution of diauxic growth

Area of Science:

• Microbiology
• Systems Biology
• Evolutionary Biology

Background:

• The glucose effect describes diauxic growth, a two-phase growth pattern cells exhibit with multiple carbon sources.
• Diauxic growth is hypothesized to maximize biomass production in nutrient-rich environments.
• The conjecture that diauxic growth enhances overall cellular growth remains unconfirmed.

Purpose of the Study:

• To investigate the evolutionary conditions favoring diauxic growth.
• To test the hypothesis that diauxic growth is a strategy for increased cellular growth.
• To model bacterial nutrient uptake and metabolism under artificial evolution.

Main Methods:

• Developed a minimal mathematical model of bacterial nutrient uptake and metabolism.
• Employed artificial evolution to simulate the emergence of growth patterns.
• Analyzed the conditions under which sequential nutrient uptake evolves.

Main Results:

• Sequential nutrient uptake emerges under conditions of nutrient competition and capacity-limited metabolism.
• Diauxic growth was identified as a secondary consequence of the system's dynamics.
• A significant speed-up in nutrient uptake was observed, exceeding the effect of diauxic growth.

Conclusions:

• Cells competing for nutrients evolve rapid but inefficient growth strategies.
• The simulated models did not show substantial lag-phase evolution, suggesting stochastic gene expression as a cause.
• Rapid nutrient uptake, while beneficial for speed, can lead to reduced overall metabolic efficiency.