Collective peroxide detoxification determines microbial mutation rate plasticity in E. coli

Area of Science:

• Microbial genetics and evolution
• Environmental microbiology
• Systems biology

Background:

• Mutagenesis is influenced by environmental factors, impacting evolutionary processes.
• Microbial populations exhibit an inverse relationship between mutation rates and population density.
• The underlying mechanism for this density-associated mutation rate plasticity (DAMP) remains largely unexplored.

Purpose of the Study:

• To elucidate the mechanism driving the inverse relationship between microbial population density and mutation rates.
• To investigate the role of hydrogen peroxide in mediating density-dependent mutation rate changes.

Main Methods:

• Dynamical computational modeling of microbial populations.
• In-culture estimation of mutation rates in Escherichia coli.
• Experimental manipulation of hydrogen peroxide degradation pathways.

Main Results:

• The negative correlation between mutation rate and population density is attributed to the collective regulation of hydrogen peroxide concentrations.
• Escherichia coli populations lacking peroxide degradation exhibit a loss of DAMP.
• Co-culturing peroxide-degradation-deficient cells with wild-type cells restores density-dependent mutation rate reduction.

Conclusions:

• A mechanistic explanation for DAMP is provided, demonstrating the role of collective hydrogen peroxide control.
• Mutation rate is presented as a dynamic trait influenced by microbial community composition and environmental factors.
• The findings have implications across all domains of life, highlighting environmental modulation of evolutionary variation.