Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2001
Publication Date: 4/1/2001
Citation: MOYNE, A., SHELBY, R.A., CLEVELAND, T.E., TUZUN, S. BACILLOMYCIN D: AN ITURIN WITH ANTIFUNGAL ACTIVITY AGAINST ASPERGILLUS FLAVUS. JOURNAL OF APPLIED MICROBIOLOGY. 2001. V. 90. P. 622-629. Interpretive Summary: The fungus known as Aspergillus flavus can infect corn, cottonseed, peanut, and tree nuts and produce a poison known as aflatoxin, which presents health hazards to humans and animals consuming these crops, due to not only the toxic, but also carcinogenic properties of aflatoxin. Even very low levels of aflatoxins (greater than the FDA-imposed limit of 20 parts per billion) can lead to severe economic losses in susceptible crops. The control of this problem has been aimed primarily at restricting conditions conducive to fungal invasion of the crop or at incorporation of genetic factors into the crop that impede fungal growth. We are in the process of cloning genes encoding "antifungal" (inhibitory to fungi) "peptides" (small proteins) for use in the enhancement of resistance in plants to the fungus that produces aflatoxin and other fungal pathogens. As a basis for cloning these antifungal genes, two inhibitory peptides produced by a bacterium, Bacillus subtilis (designated AU 195), were completely purified, identified, and characterized. This accomplishment will provide the basis for cloning the gene(s) that govern the synthesis of the antifungal peptides for their ultimate use in biotechnology. Major impact to agriculture in the control of aflatoxin producing fungi and several other fungi causing plant diseases could result, if potent antifungal genes can be cloned and utilized in biotechnology to enhance resistance in crop plants to attack by fungal pathogens.
Technical Abstract: In a search for an antifungal peptide with a high activity against Aspergillus flavus, we selected a Bacillus subtilis AU195, from a collection of isolates, with antagonistic activity against A. flavus. To identify the antifungal peptides we developed a protein purification scheme based on the detection of the antifungal activity in purified fractions against A. flavus. Two lipopeptides were purified with anion exchange and gel filtration chromatography. Their masses were determined to be 1045 and 1059 with mass spectrometry and their peptide moiety was identical to bacillomycin D. AU195 synthesized a mixture of two antifungal bacillomycin D analogs with masses of 1045 and 1059, the 14 mass unit difference representing the difference between a C15 and a C16 lipid chain. The antifungal spectrum of bacillomycin D includes a wide range of plant pathogens. Both bacillomycin D analogues were active at the same concentration against A. flavus but the different lipid chain length apparently affected the activity of the lipopeptide against other fungi.