The evolution of short- and long-range weapons for bacterial competition

Area of Science:

• Microbiology
• Evolutionary Biology
• Computational Biology

Background:

• Bacteria employ various competitive strategies, including bacteriocins, tailocins, type VI secretion systems, and contact-dependent inhibition (CDI).
• The evolutionary advantage of possessing multiple bacterial weapon systems remains unclear.

Purpose of the Study:

• To compare the efficacy of short-range (contact-dependent) and long-range (diffusion-based) bacterial weapons using an agent-based model.
• To investigate the functional roles of different weapon types in bacterial competition.

Main Methods:

• Development of an agent-based model to simulate bacterial warfare.
• Experimental testing using the opportunistic pathogen *Pseudomonas aeruginosa*.
• Head-to-head competition assays comparing CDI and tailocins.

Main Results:

• Agent-based model predicted contact weapons are effective when attackers are outnumbered, while ranged weapons require numerical advantage.
• Experimental results with *Pseudomonas aeruginosa* confirmed CDI effectiveness at various frequencies and tailocin efficacy at high densities.
• Competition experiments showed tailocin attackers defeat CDI only when numerically dominant.

Conclusions:

• Short-range and long-range bacterial weapons have distinct ecological functions.
• Bacterial weapon systems allow for effective competition both individually and collectively.
• The strategic deployment of diverse weapons enhances bacterial survival and dominance.