Quorum sensing inhibition properties of lichen forming fungi extracts from Cetrelia species against Pseudomonas aeruginosa

Communication among bacterial cells through quorum sensing (QS) system in Pseudomonas aeruginosa is responsible for antibiotic resistant infections in hospitals. This bacterium can regulate its virulence gene expressions through its QS systems. It is now known that inhibiting QS can leave bacteria vulnerable. Therefore, it is necessary to determine natural sources to obtain potential quorum sensing inhibitors. This study aims to investigate the QS inhibitor (QSI) bioactivity of the culture extracts obtained from lichen-forming fungi (LFF) of five Cetrelia species against P. aeruginosa. Extracts were applied to monitor strains and all samples have shown varying amounts of QS inhibition activity. Our study demonstrates that LFF cultures can be utilized to produce QSI compounds instead of collecting slow growing natural lichen thalli. We believe that this research will cast a new light on identification and isolation of active compounds from the extracts and assessment of their compatibility for future drug research.