Characterization and survival of broad-spectrum biocontrol agents against phytopathogenic fungi

The current study intended to isolate, characterize and identify biocontrol bacteria possessing broad-spectrum antifungal activity from the phyllosphere of different crops including maize, wheat and potato and to assess their growth-promoting activity. In this study 14/113 biocontrol bacteria showed antifungal activity. Bacterial isolates M11 and M33 from maize out of 113 were re-selected on the basis of their strong (more than 50%) broad spectrum antifungal activity after their assessment against four economically important phytopathogenic fungi including Alternaria alternata, Rhizoctonia solani, Fusarium oxysporum and Fusarium verticillioides. The isolates were further assessed for plant growth promoting traits, i.e., indole-3-acetic acid production, phosphate solubilization, production of cellulase, microbial volatile compounds, hydrogen cyanide and siderophores. All fourteen isolates showed positive results for the production of indole-3-acetic acid hormone and cellulase enzyme, 10 isolates were positive for hydrogen cyanide production; siderophores production was observed in 7 isolates while 5 isolates showed ability to solubilize inorganic phosphate. Microbial volatile compounds were only synthesized by M11 and M33, which were identified as Bacillus amyloliquefaciens and Bacillus subtilis respectively by 16S rRNA gene sequencing. The survival study revealed that biocontrol bacteria B. amyloliquefaciens and B. subtilis have the ability to survive in cost effective molasses containing carrier material up to a three-month period.