Multiple factor analysis of genetic and metabolite profiles as an improved strategy for potential Bacillus biocontrol agent selection to control crown gall and fire blight diseases

Abstract

We aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall and fire blight diseases caused by Agrobacterium tumefaciens and Erwinia amylovora, respectively. The relationship between the strain biocontrol ability and the secondary metabolites biosynthetic gene profile, the production of antibacterial compounds, the thin layer chromatography, and Rep-PCR profiles was investigated. The Bacillus strains showed variability in their antibacterial activity as well as their lipopeptide, polyketide, and bacilysin biosynthetic gene profiles. The thin layer chromatography of the methanolic extracts and the Rep-PCR banding patterns showed relatively low heterogeneity. The study of the relationship between variables was performed using the multiple-factor analysis differentiating strains according to their biocontrol ability. Interestingly, the most efficient biocontrol strains against both phytopathogens could be identified by the use of specific profiles. New screening procedures of Bacillus biocontrol agents against both diseases relying on the use of the antibacterial compound gene profile, the thin layer chromatography profile, or the Rep-PCR profile could be proposed. These markers are specific for Bacillus biocontrol agents, which may prove useful for the isolation and identification of new and effective biocontrol strains.