Quorum quenching mediated biofilm impediment in Chromobacterium violaceum and Staphylococcus aureus by leaf extracts of Delonixelata

Abstract

Biofilms are complex communities of microorganisms that cause systemic infections, resistance development and delay in healing wounds. Biofilms can form in various parts of the human body, such as the teeth, lungs, urinary tract, and wounds. Biofilm complicates the effects of antibiotics in treating infections. In search of a cure, a plant-based phyto component was selected for this investigation as an anti-quorum-mediated biofilm restricting agent in Gram-negative Chromobacterium violaceum and Gram-positive Staphylococcus aureus. The bioactive components in Delonix elata (DE) ethyl acetate extract were identified using Gas chromatography and mass spectrometry. The extract was examined for toxicity using 3T3 cell lines and brine shrimp and ascertained to be non-toxic. Violacein was inhibited up to 68.81 % in C. violaceum at 0.6 mg/ml concentration. Hemolysin synthesis impediments in C. violaceum and S. aureus were 80 % and 51.35 %, respectively, at 0.6 mg/ml of DE extract. At 0.6 mg/ml, EPS was abated by up to 49 % in C. violaceum and 35.26 % in S. aureus. DE extract prevented biofilm formation in C. violaceum and S. aureus up to 76.45 % and 58.15 %, respectively, while associated eDNA was suppressed up to 67.50 % and 53.47 % at the respective sub-MIC concentrations. Expression of genes such as cviI, cviR, vioA, vioB, and vioE were dramatically reduced in C. violaceum, while genes such as agrA, sarA, fnbA, and fnbB were significantly reduced in S. aureus. Docking demonstrates that two or more DE molecules bind efficiently to the QS receptors of C. violaceum and S. aureus. Thus, DE extract can be investigated for therapeutic purposes against pathogenic microorganisms by rendering them less virulent through quorum quenching mediated action.