Many species of bacteria possess multiple weapons to attack competitors. These include both short-range weapons that require direct contact with neighbouring cells, and long-range weapons, such as toxins that are released into the environment. Up to now, why bacteria have evolved to carry such a wide array of weapons has been a mystery.
Study co-author Professor Kevin Foster (Departments of Biology and Biochemistry, University of Oxford), said: ‘Unlike animals, which tend to carry a single weapon type such as horns, antlers, or tusks, bacterial species commonly carry multiple weapons. But it was unclear what the evolutionary basis for this was – why not just invest in a single type? One theory was that bacteria carry multiple weapons because they serve different functions during competition.’
The researchers tested this using the opportunistic pathogen Pseudomonas aeruginosa, a priority one pathogen by the World Health Organization, due to the rapid emergence of multidrug-resistant strains. P. aeruginosa possesses diverse weapons, including the ability to produce various toxic molecules (a long-range weapon), and toxin-loaded filaments anchored to its outer membrane (a short-range weapon).