Mycotoxins present in cereals are a worldwide problem and are a result of the presence of mycotoxin producing fungi. A strategy to reduce these fungi and mycotoxin levels in contaminated grains is with the use of lactic acid bacteria (LAB) or Bacillus spp., which can degrade or bind toxins. In this study, LAB and Bacillus spp. were isolated from mycotoxin contaminated wheat grains and, together with additional plant-derived strains, an antifungal screening against Fusarium graminearum was performed. Furthermore, these strains were screened for their ability to reduce zearalenone (ZEA) and deoxynivalenol (DON). Finally, the mode of action of the most promising microorganisms was investigated by analyzing toxin reduction with viable and dead cells, cell extracts and supernatants. Out of 212 tested strains, 70 showed high antifungal activity and 42 exhibited the ability to detoxify more than 90% ZEA, i.e., Bacillus licheniformis (19), B. megaterium (13), and Levilactobacillus brevis (10). None of the tested strains were able to decrease DON. The mode of action of ZEA reduction could not be fully elucidated. Neither dead cells (<20%), nor cell extracts nor supernatants could reduce ZEA in high amounts, which exclude high binding capacity and the involvement of extra- or intra-cellular enzymes.

Wheat is one of the world’s key staple foods, but it is often contaminated with mycotoxin-producing microorganisms, resulting in a large amount of food waste every year. The contamination of wheat grains harvested in 2020 and 2021 in Switzerland, as well as of wheat flours bought in local stores with the two mycotoxins zearalenone (ZEA) and enniatin B (ENB) was investigated. The quantification was performed using LC–MS/MS. ZEA, the level in different cereals and food products of which is regulated by law, was detected in half of the grain samples at levels below 100 µg/kg, except for one sample contaminated with 147 µg/kg. No ZEA was detected in the commercial wheat flours. The emerging mycotoxin ENB was detected in all samples of wheat grains and flours, at levels between 3 and 938 µg/kg. The harvest year was shown to affect the ENB content (p value < 0.01), and in particular the humid weather conditions encountered in 2021 during the month of harvest. The refining grade of the flours showed no influence on the contamination by ENB, indicating that the contamination with ENB can occur not only on the surface layers but also on the inner layers on the wheat grain. As chronic exposure to ENB can therefore not be excluded, decontamination solutions are needed to prevent food waste and further improve the food safety of wheat-based products.