Quorum quenching attenuation of rhizobacteria Chromobacterium violaceum virulence by Desmodium gangeticum root extract

Abstract

Quorum sensing signal molecules used amongst bacteria for communicating cell density can be interfered with through quenching of the signal molecule, a process known as quorum quenching. Several bacteria depend upon a mechanism generally called as quorum sensing to identify their population density and initiate its colonization. The goal of this research was to test and optimize an anti-quorum sensing chemical derived from Desmodium gangeticum root extract against the biosensor strain Chromobacterium violaceum, a rhizosphere bacterium with an opportunistic pathogenic ability. Desmodium gangeticum root extract contained a chemical known as 1,6-octadien, 3,5-dimethyl-, cis, which had a promising bacterial silencing action. The studies suggested that the extract have a downregulating effect upon bacterial virulence. Response surface modelling (RSM) and the Box-Behnken technique were used to investigate the optimization of dependent variables such as bacterial density, rate of administration, and extract concentration. ANOVA and Cook's distance table were used to verify the mathematical model that resulted. The chemical exhibited anti-quorum sensing activity that is dose dependent, peaking at 300 μg/ml extract three times per day. The findings imply that the extract has no bactericidal effect but does affect the quorum sensing system.