Antagonistic Potential of N-acyl-homoserine Lactone Degrading Bacillus Species for Controlling Pectobacterium Based Infections in Potato

Abstract

Interference with quorum sensing (QS) naturally through quorum quenching is an established bio-control approach. In the present study, quorum quenching strategy was employed against Pectobacterium atrosepticum causing blackleg disease of potato. N-acyl-homoserine lactone (NAHL) degrading bacteria were isolated from potato rhizosphere using serial dilutions on different growth mediums and their ability to degrade NAHLs was evaluated using Chromobacterium violaceum (CV026) and Agrobacterium tumefaciens (NTLR-4) biosensor strains. Six rhizospheric isolates, capable of degrading NAHLs extracted from Pectobacterium atrosepticum were molecularly identified as belonging to genus, Bacillus. NAHL degradation ability of all these 6 Bacillus strains was also assessed using plate streak and thin layer chromatography assays. Resultantly, these strains remarkably degraded both short and long chain synthetic NAHLs. Furthermore, these Bacillus species also acted as potential bio-control agents when co-inoculated under quorum quenching tuber assay and have shown effective results in reducing QSregulated soft rot tuber maceration in potatoes. Overall, all six Bacillus strains showed substantial capability in controlling Pectobacterium based infections through quenching of the NAHL signals; however, Bacillus cereus SSB1 was determined as the most efficient quencher strain. This work highlights a promising strategy for the bio-control and prevention of infectious plant diseases through quenching of the QS signals.