ARS | Publication request: Surfactin A production and isoforms characterizations in strains of <i>Bacillus mojavensis</i> for control of a maize pathogen, <i>Fusarium verticillioides</i>

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2011
Publication Date: August 6, 2011
Citation: Bacon, C.W., Hinton, D.M., Mitchell, T., Snook, M.E. 2011. Surfactin A production and isoforms characterizations in strains of Bacillus mojavensis for control of a maize pathogen, Fusarium verticillioides. American Phytopathological Society and the International Association for the Plant Protection Sciences, Joint Meeting. August 6-10,2011. Honolulu, HI.

Technical Abstract: The endophytic bacterium, Bacillus mojavensis, RRC 101 controls fungal diseases in maize and other plants. The bacterium and its cultural extracts have been shown to be antagonistic to the pathogenic and mycotoxic fungus, Fusarium verticillioides. An antifungal cyclic lipopeptide produced by B. mojavensis 29 strains in culture was identified as surfactin A, a potent biosurfactant. HPLC-MS spectra analyses indicated that several stains of B. mojavensis produced Leu7-surfactin A as a major surfactin, although other isoforms ranging from C-11 to C-15 were also identified. However, the data suggested that the in vitro antagonism observed on media is not correlated with total surfactin production, but may be related to amounts of specific isoforms of this biosurfactant. In this investigation, these B. mojavensis strains were screened on two media to determine the titer of isoforms produced and the antagonism induced by specific commercial surfactins A, B and C, as well as their biological relationship to antagonism to F. verticillioides. Data indicated that there was a significant level of surfactin A produced by most of the surfactin producing strains during the first twenty-four hours. The results identified several stains as high producers of surfactin A, as well as high producers of C-15 surfactin A, the most biologically active isoforms for fungal toxicity, suggesting that it is these strains that should be used as biocontrol agents.