Inhibitory Assessment of Centella asiatica-based Endophytic Bacillus pumilus Extract on Biofilm and Quorum Sensing of Pseudomonas aeruginosa

Abstract

Endophytes are ubiquitous across nearly all plant species, exhibit rich biodiversity, and serve as a vital source of natural bioactive compounds that can be used as alternatives to antibiotics. In this study, Centella asiatica-based endophyte MM02, identified as Bacillus pumilus, was examined for antimicrobial activity against various pathogens and for its potential to inhibit Pseudomonas aeruginosa biofilm formation and quorum-sensing (QS)-regulated virulence. The compositional analysis of the MM02 crude extract revealed the presence of diverse bioactive compounds, as validated by biochemical and chromatographic analyses with potential plant-growth-promoting, antimicrobial, anti-biofilm, and anti-QS properties. The extract inhibits biofilm and exopolysaccharide formation in a dose-dependent manner, up to 87.8%, and various QS-dependent and virulence activities, up to 85.3%. Microscopy, virulence gene expression, and in-silico analyses successfully validated biofilm and QS inhibition in P. aeruginosa. These findings demonstrate that a novel endophytic B. pumilus extract enriched in biomolecules can be used to treat P. aeruginosa as a sustainable alternative to antibiotics.