Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: August 16, 2000
Publication Date: May 1, 2001
Interpretive Summary: Modern day corn cultivars co-exists with a fungus Fusarium moniliforme, which produces a series of mammalian toxins call the fumonisins. These toxins are known to cause toxicity in swine, poultry, cattle and horses. Corn infected with the fungus is associated with human esophageal cancer, primarily in areas where corn is a major food staple. The fungus is associated with the corn plant internally and is called an endophyte, and as such it is very difficult to control. Scientists at RRC discovered a bacterium that is also an endophyte and can exclude the fungus from growth in corn, reducing the potential for future toxin production both in storage and on the plant. The bacterium is in the process of being patented by ARS. Scientists at RRC were invited by a multi-agency task force to present the biological control potential of this bacterium. This chapter discusses the major aspects of biological control using this bacterium in corn, including reduction of toxin by the fungus. The work was presented at the international conference on the Toxicology of Fumonisin, June 28-30, 1999 sponsored by FDA, ARS, National Institute of Environmental Health Sciences, and the International Life Sciences Institute (ILSI) North America Technical Committee on Food Toxicology and Safety Assessment. The chapter will be published in a book by ILSI North America.
Technical Abstract: Fusarium moniliforme Sheldon., a biological species of the mating populations within the Gibberella fujikuroi species complex, i.e. population A (=G. moniliformis (Sheld.) Wineland, mating types matA-2, and matA-1, is an example of a fungal endophyte. During the biotrophic endophytic association with maize, as well as during saprophytic growth, F. moniliforme produces the fumonisins. The fungus is vertically and horizontally transmitted to the next generation of plants via clonal infection of seeds. A biological control system utilizing an endophytic bacterium, Bacillus subtilis, has been developed that shows great promise for the reduction in mycotoxin accumulation during the endophytic (vertical transmission) growth phase. Since this bacterium occupies the identical ecological niche within the plant, it is considered an ecological homologue to F. moniliforme, and the inhibitory mechanism operates on the competitive exclusion principle. In addition to this bacterium, an isolate of a species of the fungus Trichoderma shows promise in the post-harvest control of the growth and toxin accumulation from F. moniliforme in storage.