Outer membrane changes enable evolutionary escape from bacterial predation.

E. coli K-12 evolves genetic resistance to predatory bacterium B. bacteriovorus through outer membrane modifications, with resistance emerging after just two predator exposure cycles.

• Why it matters: Understanding how prey bacteria develop resistance to predatory bacteria is crucial for assessing the long-term effectiveness of predatory bacteria as alternative antimicrobial agents against resistant pathogens.
• What they did: The study used experimental evolution, genetic analysis, and proteomics to identify mutations—particularly down-regulation of outer membrane porin OmpF and mutations in WaaF—that confer resistance, despite associated fitness costs.
• The result: Findings reveal that resistance mechanisms impose significant fitness trade-offs, suggesting that exploiting these costs could enhance the sustainability of predatory bacteria as "living antibiotics" in combating antimicrobial resistance.