Researchers from Egypt and Iraq have identified a powerful anti-virulence mechanism in an endophytic bacterium, Bacillus cereus AL1, capable of quenching quorum sensing in Pseudomonas aeruginosa — a notorious hospital-acquired pathogen. The study, published in BMC Microbiology (2025), explores how this plant-associated bacterium produces a lactonase enzyme that dismantles bacterial communication without killing the pathogen, thus avoiding the rise of antibiotic resistance.
Out of 52 bacterial isolates screened, B. cereus AL1 showed the strongest quorum-quenching potential, completely degrading the signaling molecule N-hexanoyl-L-homoserine lactone (C6-HSL). The partially purified lactonase enzyme significantly reduced P. aeruginosa biofilm formation, swarming motility, and pyocyanin production—three major virulence traits. Structural analyses confirmed close similarity of this enzyme to known Bacillus lactonases.
Crucially, the enzyme demonstrated protection in Galleria mellonella larvae infected with P. aeruginosa, highlighting its real-world potential as a bio-safe anti-virulence tool. The authors propose B. cereus AL1 lactonase as a promising candidate for novel biocontrol or therapeutic applications targeting multidrug-resistant Pseudomonas infections.
This study adds to the growing evidence that nature’s own endophytes—beneficial microbes living inside plants—may hold the key to combating antibiotic-resistant superbugs through quorum quenching rather than traditional antibiotics.
Reference
Fawzy, A. A., Raafat, M. M., Mahmoud, R., & Helmy, O. M. (2025). Quorum quenching by endophytic Bacillus cereus AL1: a lactonase-based anti-virulence strategy against Pseudomonas aeruginosa. BMC Microbiology, 25(1), 669. https://doi.org/10.1186/s12866-025-04396-4
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