Competition dynamics and evolutionary strategies of bacteriocin-encoding bacteriophages

Bacteriophages (phages) — viruses that infect bacteria — can encode compounds beneficial to their host bacteria, such as bacteriocins, i.e., antimicrobial peptides that kill similar bacterial strains. While encoding a bacteriocin can provide a competitive advantage to the host, it may also have a negative impact on phages' ecological fitness, as the bacteriocin can kill potential hosts for future infection. Therefore, it remains unclear under what conditions bacteriocin encoding is advantageous, and how such strategies have evolved.



To address these questions, we analyzed the competition dynamics between two types of phages: one encoding a bacteriocin and one lacking it. Based on experiments on the growth of Bacillus subtilis strains integrating SPβ prophage, which encodes a bacteriocin called sublancin, we constructed a mathematical model describing the population dynamics of bacteria and phages. Through model analysis, we investigated which phage strain dominates under serial dilution culture conditions.



Our results indicate key factors determining the outcome of the competition, including resource conditions and the availability of susceptible hosts. This work provides an important step towards understanding how phage strategies involving bacteriocin encoding have evolved in relation to host ecology.