Inhibition of quorum sensing in Chromobacterium violaceum by pigments extracted from Auricularia auricular

Abstract

This study aimed to search for a novel quorum-sensing inhibitor from some fungi and analyse its inhibitory activity. Chromobacterium violaceum CV026, a double mini-Tn5 mutant, was used as an indicator to monitor quorum-sensing inhibition. Auricularia auricular pigments from fruiting bodies were extracted using hydrochloric acid as an infusion, dissolved in alkaline dimethylsulfoxide (DMSO), sterilized by filtration through a 0·22-μm membrane filter and added to C. violaceum CV026 cultures. Inhibitory activity was measured by quantifying violacein production using a microplate reader. The results have revealed that the alkaline DMSO-soluble pigments significantly reduced violacein production in a concentration-dependent manner, a quorum-sensing-regulated behaviour in C. violaceum. Auricularia auricular pigments can inhibit bacterial quorum sensing. The results suggest the bioactive constituents from edible and medicinal fungi could interfere with bacterial quorum-sensing system, regulate its associate functions and prevent bacterial pathogenesis. Further studies were in process in our laboratory to isolate specific compounds from A. auricular pigments, evaluate them as quorum-sensing inhibitors and analyse the exact mechanism of action.