Evolution of bacterial surface exclusion against incompatible plasmids

Area of Science:

• Microbiology
• Evolutionary Biology
• Genetics

Background:

• Conjugative plasmids often possess surface exclusion systems to prevent the entry of incompatible plasmids.
• Understanding the evolutionary dynamics of these exclusion systems is crucial for plasmid biology.

Purpose of the Study:

• To determine the conditions under which surface exclusion systems can evolve in conjugative plasmids.
• To model the competitive dynamics between excluding and non-excluding plasmids.

Main Methods:

• Development of a mathematical model to simulate plasmid competition.
• Analysis of factors influencing the evolution of surface exclusion, including copy number, transfer rate, plasmid cost, and loss rate.

Main Results:

• Surface exclusion can evolve and outcompete non-excluding plasmids when plasmid copy number is low and transfer rates are high.
• The evolution of surface exclusion is favored by a low cost of plasmid possession and a low rate of plasmid loss.
• These conditions facilitate the expulsion of non-excluding plasmids from bacterial populations.

Conclusions:

• Plasmids with surface exclusion systems can be evolutionarily advantageous under specific ecological and genetic conditions.
• The findings provide insights into the maintenance and spread of conjugative plasmids in microbial communities.