Discovery and Activity Evaluation of Quorum-Sensing Inhibitors from an Endophytic Bacillus Strain W10-B1 Isolated from Coelothrix irregularis

This study focuses on discovering novel quorum-sensing inhibitors (QSIs) from endophytes of Coelothrix irregularis, aiming to develop new strategies against drug-resistant bacterial infections. From the endophytic bacterial strain Bacillus strain W10-B1, isolated from C. irregularis, twelve compounds were isolated and structurally identified. Subsequent screening against Serratia marcescens NJ01 revealed that compound (12), 3,3′-dibromo-4,4′-biphenyldiol, exhibited significant inhibitory activity against the quorum-sensing system of S. marcescens NJ01. It effectively suppressed biofilm formation, swimming, and swarming motilities of the bacterium. This work is the first to demonstrate that endophytes from C. irregularis are a novel source of potent QSIs, providing both material and theoretical foundations for combating pathogen virulence, drug resistance, and pathogenicity.