June 30, 2009

ARS scientists have found a key bacterial compound that inhibits the growth of plant pathogen Fusarium verticillioides, and it could help protect plants, livestock and poultry from fusarium infection.

The compound, Leu-7-surfactin, is produced by Bacillus mojavensis strain RRC101. Finding better controls for the pathogen is important because fumonisin mycotoxins, especially fumonisin B1, are toxic to livestock and poultry.

B. mojavensis is a plant-residing bacterium that can be used to control fungal diseases in corn and other plants. The Leu7-surfactin was isolated from growing the bacterium in liquid culture, and the compound has proved effective in inhibiting growth of the fungus in lab tests.

Surfactin has a detergent-like activity that dissolves the lipid membranes inside the fungus, eventually killing it.

Leu7-surfactin was found to be effective at controlling F.verticillioides at very low concentrations of 20 microgrammes per litre of liquid, making it more efficient to use.

The research team examined all currently available strains of B. mojavensis and found that all of the strains live within the plant and all were active against F.verticillioides and other fungi in lab tests.

The genus Bacillus is known for the production of more than 24 antibiotics, several of which are fungicidal with the potential to control plant diseases.