Antibiofilm potential of Chlorococcum dorsiventrale extracts against Pseudomonas aeruginosa: Biochemical and molecular insights.

Biofilms formed by Pseudomonas aeruginosa pose major challenges in both clinical and environmental settings, highlighting the need for effective control strategies. This study investigates the anti-biofilm activity of the green microalga Chlorococcum dorsiventrale against Pseudomonas aeruginosa PAO1 and the clinical isolate MUC-N1 under Luria-Bertani (LB) and Modified Biofilm Broth (MBB) conditions. Extracts prepared with acetone, cyclohexane, ethanol, methyl tetrahydrofuran (MTHF), and distilled water (50 μg/mL) were tested for their ability to inhibit biofilm formation. Acetone and ethanol extracts showed the highest activity against PAO1 in LB (63.1% and 68.6% inhibition), whereas MTHF and acetone were the most effective in MBB. For MUC-N1, aqueous and ethanol extracts inhibited biofilm formation by 86.9% and 66.3% in LB, while cyclohexane and MTHF extracts showed the highest activity in MBB. CFU counts confirmed a significant reduction in bacterial adhesion, reaching up to 84.4%. qPCR analysis revealed downregulation of the quorum sensing genes rhlI, rhlR, and mvfR in both strains, with lasI and lasR downregulated in PAO1 but overexpressed in MUC-N1. These findings suggest that C. dorsiventrale extracts disrupt bacterial communication, thereby modulating biofilm formation and the production of virulence factors.