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Title: Surfactin A Production and Isoform Characterizations in Strains of Bacillus mojavensis for Potential Control of Fusarium verticillioides and Fumonisin in Maize

Author
item Bacon, Charles
item Hinton, Dorothy
item MITCHELL, TREVOR - University Of Georgia
item SNOOK, MAURICE - Retired ARS Employee

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2011
Publication Date: 2/20/2011
Citation: Bacon, C.W., Hinton, D.M., Mitchell, T.R., Snook, M.E. 2011. Surfactin A Production and Isoform Characterizations in Strains of Bacillus mojavensis for Potential Control of Fusarium verticillioides and Fumonisin in Maize. Genetics of Maize Disease Workshop Renaissance. February 20-23, 2011. Raleigh North Hills, NC.

Interpretive Summary:

Technical Abstract: Bacillus mojavensis, a species recently distinguished as a cryptic species within Bacillus subtilis, was discovered in maize kernels and later determined to possess endophytic characteristics. The bacterium was also determined to have biocontrol potential due to its strong antagonism to the fungus Fusarium verticillioides. Maize plants with endophytic bacterium also displayed a marked improvement in growth and development, disease protection, and reduction in the fumonisin mycotoxin. Recently, we reported that the patented strain B. mojavensis produced the biosurfactant Leu7-surfactin, one of several cyclic lipopeptides surfactin A, which was inhibitory to F. verticillioides and other maize pathogens. In an effort to understand further surfactin production, B. mojavensis strains were screened for surfactin production along with an analysis of specific structural analogs produced within this biosurfactant fraction, and to provide a measure of in vitro inhibition relative to growth of F. verticillioides. The results indicated that the strains produced a complex of surfactin A isoforms that were comprised of acyl chain length ranging from C-11 to C-17, and that the in vitro inhibition observed did not necessarily relate to total surfactin concentrations. These experiments indentified high producers of C-15 surfactin A, an isoform that is rated highly biologically active in terms of fungicidal toxicity. Further, this analysis revealed that there was genotypic diversity among strains from the great deserts, with an apparent random distribution. However, the data also suggests that there are additional inhibitors produced by these strains, or that perhaps specific ratios of isoforms are required for the inhibitory response observed in vitro.