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Title: Isolation and characterization of Leu[7]-Surfactin from the endophytic bacterium Bacillus mojavensis RRC 101, a biocontrol agent for Fusarium verticillioides

Author
item Snook, Maurice
item Mitchell, Trevor
item Hinton, Dorothy
item Bacon, Charles

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2009
Publication Date: 7/1/2009
Citation: Snook, M.E., Mitchell, T.R., Hinton, D.M., Bacon, C.W. 2009. Isolation and characterization of Leu[7]-Surfactin from the endophytic bacterium Bacillus mojavensis RRC 101, a biocontrol agent for Fusarium verticillioides. Journal of Agricultural and Food Chemistry. 57:4287-4292.

Interpretive Summary: A patented endophytic bacterium, Bacillus mojavensis, has the potential to control corn and other plant fungal diseases as well as reduce the content of fungal toxins, particularly the fumonisin mycotoxins produced by Fusarium verticillioides of corn. However, the nature of this control is unknown. We report here on the chemical identity of the inhibitory substance as surfactin. This is first report for surfactin from this species of bacterium. This substance is very toxic to this fungus and similar plant pathogenic species, widening its use application. This plant friendly, environmentally safe and relatively non-mammalian compound belong to a chemical group of substances referred to as the biosurfactants whose chemical activity is similar to, but safer than household detergents. This finding is important since we now can proceed with the use of this bacterium without regards to environmental concerns and testing since its use is the subjects of numerous environmental studies.

Technical Abstract: Bacillus mojavensis is an endophytic bacterium patented for control of fungal diseases in maize and other plants. Culture extracts and filtrates from this bacterium were antagonistic to the pathogenic and mycotoxic fungus Fusarium verticillioides. However, the identity of the inhibitory substance from extracts of this bacterium has not been determined. An HPLC-MS analysis from the culture filtrate showed a major ion peak that was identified as a cyclic lipopeptide. Further CID analysis indicated that this lipopeptide was surfactin, a cyclic heptapeptide linked to a beta-hydroxy fatty acid. A CID analysis of the peptide moiety was established by deduction and indicated that the peptide sequence consisted of two acidic amino acids and five hydrophobic amino acids with a sequence of Leu-Leu-Asp-Val-Leu-Leu-Glu. These spectra indicated that this bacterium produced Leu[7]-surfactin, which was determined to be toxic to F. verticillioides. This cyclic lipopeptide is characteristic of several species of Bacillus, but this is the first report of this very powerful biosurfactant from this endophytic species.