Aflatoxin and fumonisin contamination in corn smut (Ustilago maydis) galls in the field and in the grocery store
H. K. ABBAS (1), M. A. Weaver (1), W. T. Shier (2), R. M. Zablotowicz (3), J. D. Plasencia (4). (1) USDA ARS, Biological Control of Pests Research Unit, Stoneville, MS, U.S.A.; (2) University of Minnesota, Department of Medicinal Chemistry, College of Pharmacy, Minneapolis, MN, U.S.A.; (3) USDA ARS, Crop Production Systems Research Unit, Stoneville,
Corn infected with <i>Ustilago maydis</i>, causal agent of common smut, produces galls that are used as food in certain cultures, but may be contaminated with mycotoxins. The objective of this study was to determine mycotoxin levels in common smut galls (CSG) collected at corn ear reproductive stages R1 through R6 and in commercial CGS products. A total of 108 CSG samples were collected in 2012 from corn fields and 14 CSG commercial products were purchased from grocery stores in Minnesota. All commercial products and 41 field samples were analyzed for cyclopiazaonic acid, deoxynivalenol, and zearalenone. Aflatoxin was detected in 5% of CSG field samples R3 or older (up to 15 ppb) and 63% of CGS samples R2 or older contained fumonisin (up to 150.7 ppm). Sixteen field samples R3 or older contained deoxynivalenol at levels ranging from 0.1 to 1.3 ppm. Twenty field samples R3 or older contained zearalenone at levels ranging from 0.6 to 41.7 ppb. Cyclopiazaonic acid was not detected in any of the field samples. Two commercial CSG products were positive for fumonisin (0.04 to 0.24 ppm) and zearalenone (6.1 to 15.1 ppb). <i>Aspergillus flavus</i> and <i>Fusarium verticillioides</i> were isolated from selected CSG field samples at 3.5 x 10<sup>6</sup> and 4.2 x 10<sup>6</sup> cfu/g, respectively. These results indicate that CSGs can be infected with mycotoxigenic fungi and contaminated with mycotoxins. The incidence of mycotoxins in commercially available products warrants further study.
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