Mycotoxin degradation mechanisms in mealworms (Tenebrionidae)

A major task is the establishment of defined conditions for cultivation of several species of mealworms (larvae of darkling beetles, Tenebrionidae) allowing the study of mechanisms of mycotoxin metabolism. The goal of WP 1 (at BOKU-DAGZ) is to produce axenic mealworms in order to determine whether or not the microbiome provides a major contribution to mycotoxin detoxification. In WP 2 experiments with the 13C-labelled toxins deoxynivalenol, zearalenone and aflatoxin B1 will be performed. Prior to application of the expensive labelled toxins it will be critical to find conditions where the mycotoxins are reproducibly consumed by the mealworms. In case uptake by feed is insufficient, toxins will be directly injected into the insect’s abdominal tract, for subsequent analysis by LC-HRMS(/MS) and MetExtract. At the Center for Analytical Chemistry at IFA-Tulln it will also be determined how much of the intake can be explained by known metabolites. First pilot experiments and literature reports indicate that about up to 90% of deoxynivalenol remain unaccounted. Using the isotope-assisted LC-HRMS(/MS) workflow and MetExtract data processing it should be possible to find new derivatives, and to assign sum formulas and tentative structures to the detected derivatives of the parent toxins. This should allow to postulate biochemical reactions and corresponding enzymes catalyzing the formation of mycotoxin metabolites. Utilizing the fully sequenced genome of Tribolium castaneum (rice flour beetle) it should be possible to identify candidate genes, which in the remaining project time will be tested by heterologous expression. There is preliminary evidence that detoxification may be inducible in mealworms. Therefore, the main task of the WP 3 at the FH Tulln is to use proteomics methods to search for differences in the proteome of mealworms raised on toxin free compared to artificially contaminated feed, and to determine by peptide sequencing which genes may be responsible for the differentially formed proteins.