Characterization of broad-spectrum biocontrol efficacy of Bacillus velezensis against Fusarium oxysporum in Triticum aestivum L.

Fungi are the most important phytopathogens that cause yield losses. The mycotoxins released by fungi cause spoilage of stored food consumed by humans and feed supplied to animals. Fungi-antagonistic microbes are gaining attention as potential biocontrol agents (BCAs). This study was designed to isolate bacterial isolates from different crops and evaluate their in vitro antifungal assay against three phytopathogens, plant growth promoting (PGP) characteristics, molecular identification, and in vivo efficiency against the most devastating phytopathogenic fungus Fusarium oxysporum Schltdl. In the in vitro experiment, the 3 isolates BA, GL-1, and 5a out of 360 isolates showed more than 60% inhibitory activity against the selected fungi in this study. On the basis of 16S rRNA sequencing and phylogenetic analysis, BA isolate was identified as Bacillus velezensis. All three isolates produced indole acetic acid (IAA), hydrogen cyanide (HCN), and cellulase enzymes, while the BA and GL-1 isolates also produced siderophores and the BA isolate also produced ammonia. BA was selected on basis of not only Biocontrol efficacy but also maximum PGPR activity compared to GL-1 and 5a. In vivo assay, the isolate BA showed a significant decrease in disease severity caused by Fusarium oxysporum by 64.97% after 100 days of inoculation on wheat (FD-08) seedlings in a greenhouse assay and enhanced the shoot root height, fresh and dry mass. The wide-ranging antagonistic action of Bacillus velezensis isolated from the phyllosphere of wheat crops showed promising fungicidal and plant growth-promoting capabilities, suggesting it can be used as a biofungicide.