Similar weapons play different roles in bacterial competition
Abstract
Many bacteria are aggressive organisms that inhibit and kill their competitors using a diverse range of molecular weapon systems. Strikingly, strains commonly carry multiple similar weapons that appear to perform the same function. Here, we investigate the evolutionary benefits of this apparent functional duplication using the heavily armed opportunistic pathogen, Pseudomonas aeruginosa as a model species. We first use genomics to ask whether carrying multiple similar bacteriocins (S pyocins) increases the probability of inhibiting other strains. However, simply carrying a single uncommon S pyocin is typically as effective as carrying multiple pyocins. We then combine genome editing with competition experiments to study the effects of S pyocins alone and in combinations. S pyocins sometimes function better together than alone, which helps to explain their co-carriage. However, we also find evidence of specialization: pyocin S5 is much more effective than S2 in iron-limited conditions and vice versa when iron is available. We test the generality of our findings using a second class of weapon carried by P. aeruginosa, contact-dependent inhibition, which again reveals differing effectiveness as conditions change. Our work shows how similar weapons can be specialized for combat under different environmental conditions. We argue that functional specialization is key to understanding why bacteria carry so many weapons.
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BibTeX
@article{booth2026similar,
title = {{Similar weapons play different roles in bacterial competition}},
author = {Sean C Booth and Connor Sharp and Kevin R Foster},
journal = {The ISME Journal},
year = {2026},
month = sep,
doi = {10.1093/ismejo/wrag245},
url = {https://doi.org/10.1093/ismejo/wrag245},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Similar weapons play different roles in bacterial competition
AU - Sean C Booth
AU - Connor Sharp
AU - Kevin R Foster
PY - 2026
DA - 2026/09/29
JO - The ISME Journal
DO - 10.1093/ismejo/wrag245
UR - https://doi.org/10.1093/ismejo/wrag245
AB - Many bacteria are aggressive organisms that inhibit and kill their competitors using a diverse range of molecular weapon systems. Strikingly, strains commonly carry multiple similar weapons that appear to perform the same function. Here, we investigate the evolutionary benefits of this apparent functional duplication using the heavily armed opportunistic pathogen, Pseudomonas aeruginosa as a model species. We first use genomics to ask whether carrying multiple similar bacteriocins (S pyocins) increases the probability of inhibiting other strains. However, simply carrying a single uncommon S pyocin is typically as effective as carrying multiple pyocins. We then combine genome editing with competition experiments to study the effects of S pyocins alone and in combinations. S pyocins sometimes function better together than alone, which helps to explain their co-carriage. However, we also find evidence of specialization: pyocin S5 is much more effective than S2 in iron-limited conditions and vice versa when iron is available. We test the generality of our findings using a second class of weapon carried by P. aeruginosa, contact-dependent inhibition, which again reveals differing effectiveness as conditions change. Our work shows how similar weapons can be specialized for combat under different environmental conditions. We argue that functional specialization is key to understanding why bacteria carry so many weapons.
SN - 1751-7362
SN - 1751-7370
ER -