A Novel ST1 Lactonase Reduces Virulence and Inhibits Biofilm Forma=on and Extends the Lifespan of Caenorhabdi9s elegans Infected with Pseudomonas aeruginosa MMA83

Abstract

Background: Bacterial biofilms represent a major challenge in clinical seNngs due to their resistance to an3bio3cs and immune responses. Pseudomonas aeruginosa is a significant opportunis3c pathogen responsible for chronic infec3ons, par3cularly in immunocompromised pa3ents. Quorum quenching (QQ) enzymes, such as lactonases, show promise in disrup3ng biofilm forma3on and reducing bacterial virulence. This study examines the effects of ST1-YtnP lactonase from thermophilic Bacillus licheniformis on biofilm forma3on and virulence of P. aeruginosa MMA83. Methods: The an3biofilm effect of recombinant ST1-YtnP lactonase on mul3-drug resistant P. aeruginosa MMA83 was analyzed using fluorescence microscopy. CaenorhabdiLs elegans infec3on model was used to evaluate the enzyme’s effect on virulence and host survival. The liquid killing assay was employed using the C. elegans AU37 mutant strain to quan3ta3vely evaluate host survival in response to ST1-YtnP lactonase treatment. Results: Fluorescence microscopy showed a significant reduc3on in P. aeruginosa MMA83 biofilm forma3on with ST1-YtnP lactonase, leading to a looser, less dense biofilm. Planktonic cell growth remained unaffected. In C. elegans, treatment resulted in an almost 100% survival rate, while untreated infected worms showed 0% survival within 24 hours. ST1-YtnP lactonase exhibited no toxicity, consistent with previous studies on QQ enzyme safety in eukaryo3c models. Conclusion: ST1-YtnP lactonase inhibits P. aeruginosa MMA83 biofilm forma3on and reduces virulence in C. elegans, indica3ng its poten3al as a safe and effec3ve an3virulence agent for biomedical applica3ons.Book of abstract: BIOFILMS 11, 13 – 15 May 2025, Mercure Cardiff Holland House Hotel & Spa, Cardiff, U