Unveiling the Evolution and Mystery of Bacteria's Weaponry

Bacteria commonly evolve weapons to compete with other organisms. Pseudomonas aeruginosa, an opportunistic pathogen, produces multiple bacteriocins and toxic small molecules as long-range weapons, and can deploy contact-dependent inhibition (CDI) systems and type VI secretion systems (T6SSs) as short-range weapons. A study using an agent-based model and experiments with P. aeruginosa found that short- and long-range weapons serve different functions during competition. Contact weapons are effective even when attackers are outnumbered, facilitating invasion and establishment, while ranged weapons are most effective when attackers are abundant. These findings highlight the evolutionary basis for the prevalence of multiple weapons in bacteria.