Quorum Sensing-Linked agrA Expression by Ethno-Synthesized Gold Nanoparticles in Tilapia Streptococcus agalactiae Biofilm Formation

The inevitable occurrence of diseases caused by bacterial pathogens is one of the main constraints in tilapia industry that has resulted in major economic losses. The study reveals the advantages of quorum sensing inhibition through nanotechnology in developing antivirulence drugs to control aquaculture pathogens using scientifically untapped medicinal plants, the ethnobotanicals. The ethnobotanical crude extracts (CEs) and biologically synthesized gold nanoparticles (CEs + AuNPs) of the Ilongot-Eǵongot community exhibit quorum sensing inhibition (QSI) activity through inhibition of the biofilm formation against gram-positive Streptococcus agalactiae. Furthermore, ethnobotanical CEs + AuNPs show much greater activity than its counterpart CEs in antibacterial and biofilm formation assay in S. agalactiae which is molecularly confirmed by gene expression analysis. The results indicate the potential of these ethnobotanicals for therapeutic approach in which it showed minimal expression of agrA gene linked in biofilm formation and connotes maximal inhibition of QS in S. agalactiae thereby can possibly inhibit bacterial resistance and virulence.