Mycotoxins: Biosecurity and Food Safety

Non-Technical Summary: Mycotoxins are serious contaminates of agricultural products. We are trying to identify ways to control mycotoxin contamination. <P> Approach: All 18 MRB mutants will be examined for six characteristics: ability to produce ascospore and conidial pigment and penicillin and ability to grow on propionate, acetate and oleic acid medium. Spore pigmentation will be noted on each medium (the inhibition of conidial and ascospore pigment in the DmcsA strain is only noted on propionate amended medium). Loss or diminution of spore pigment(s) could indicate a broad affect on polyketide metabolism. Inability to grow well on any of the above media could indicate a defect in propionate metabolism (and identify other genes in the methylcitrate cycle), acetate and/or fatty acid metabolism or transport. Such acyl CoA utilization mutants have a greater probability to be affected in general polyketide metabolism (rather than specifically in ST biosynthesis). Loss of penicillin production would indicate a global effect on non-polyketide secondary metabolites. We expect that several of the mutants will show aberrances in one or more of these parameters. Our eventual goal will be to complement all such mutants but we will start with those that show defects in more than one characteristic. We will transform the mutants using an A. nidulans AMAI plasmid library. This library allows for the extraction of the transforming DNA in plasmid form that greatly facilitates identification of the mutated allele. We will follow standard procedures in our lab to then subclone and identify the responsible ORF for the mutation. Upon identification of the gene, we will delete the gene in a wild type background and look for loss of ST production as a confirmation of correct identity of the gene. Identify and characterize ppo genes in A. fumigatus and determine effects on gliotoxin production. As mentioned earlier, A. fumigatus is a human pathogen but also an agricultural concern as it grows in animal feed. This fungus produces gliotoxin, a potent apoptotic agent and immunosuppressant. We have identified 3 ppo genes in this spp. and will disrupt each gene to determine effect on gliotoxin production. Identify oxylipin receptor. The fungal oxylipins are secreted factors and hypothesized to act as ligands recognized by membrane receptors (Champe and el-Zayat 1989). We propose that G protein coupled receptors (GPCR) may be the oxylipin receptors based on the advances in identifying GPCR receptors for mammalian oxylipins.