Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2013
Publication Date: N/A
Interpretive Summary: Abstract - no summary required.
Technical Abstract: The endophytic bacterium, Bacillus mojavensis controls fungal diseases in maize and other plants. The bacterium and its cultural extracts have been shown to be antagonistic to a pathogenic and mycotoxic fungus, Fusarium verticillioides. Extracts prepared from cultures of B. mojavensis contained an antifungal lipopeptide subsequently identified as surfactin A, one of the most potent biosurfactants. The B. mojavensis strains were screened to determine the effects of media on antagonism to F. verticillioides and specific surfactant production. HPLC-MS spectra analyses indicated that strains of B. mojavensis produced Leu7-surfactin as the major surfactin. Further analysis indicated that normal, iso-, and anteiso isomers of surfactin A were produced that included the C-14 and C-15 isoforms. Theoretically, the order of biological activity is normal > -iso > anteiso. The data indicated that strains showed none to high levels of antagonisms, which were not correlated with specific isomers or total surfactin production, although some strains were antagonistical but negative for surfactin production. Thus, the data suggest that either there are synergistic effects from specific isoforms of surfactins produced on agar media or there are also some unidentified biosurfactants or other inhibitory compounds yet determined. Molecular and genetic analyses are underway to separate, distinguish and increase the activity in strains with the normal isomer of surfactin A, the most biologically active.