Inhibition of Quorum Sensing and Biofilm Development by Walnut Rhizosphere Bacteria

Antibiotic resistance is a significant public health threat, and bacterial biofilms may play a role in the development of resistance to antibiotics. Natural biological agents hold promise for solving this problem due to their antibiofilm properties. In this study, extracts of walnut rhizosphere soil bacteria were used to investigate their anti-quorum sensing and antibiofilm characteristics. Four isolates (BT13, BT31, BT39 and BT40) from the walnut rizosphere demonstrated anti-quorum sensing action against Chromobacterium violaceum ATCC 12472 at dosages of 20 mg mL-1. The crude extracts of BT13 (E. mundtii) showed the highest zone diameter, while crude extracts from BT33 did not. The crude extract from the BT39 (E. faecium) isolate, S. aureus (88%), and L. monocytogenes (82%) have the best biofilm inhibition activity. The study identified two walnut rhizosphere bacteria (BT13 and BT39) that exhibited promising antibiofilm and anti-quorum sensing properties, which could serve as natural biological controls against antibiotic-resistant bacteria. In addition, these bacteria may protect both plant and public health by acting as effective antibiotics against resistant pathogenic organisms.