Mycotoxin Removal and Transcriptional Response of Pichia fermentans KCB21_L2

The presence of mycotoxins in food poses a significant risk to food safety, and it is essential to develop effective and safe detoxification strategies. In this study, we demonstrate the strong ability of <i>Pichia fermentans</i> KCB21_L2, a yeast isolated from kefir, to eliminate aflatoxin B₁, fumonisin B₁ and ocratoxin A. Viable cells removed aflatoxin B₁ and fumonisin B₁ more efficiently than heat-inactivated cells, particularly at pH values of 5.5 and 7.0, suggesting the involvement of an active removal process. Subsequently, we evaluated the capacity of <i>P. fermentans</i> KCB21_L2 to remove mycotoxins at high concentrations and investigated the underlying molecular and cellular responses. The yeast effectively eliminated high levels of all three mycotoxins. Transcriptional analysis revealed the activation of metabolic pathways related to amino acid catabolism and fatty acid metabolism, likely reflecting an adaptive stress response. However, no significant upregulation of specific genes related to mycotoxin-degrading enzymes was observed. In conclusion, the reduction process may involve multiple factors, including stress response pathways, possible production of organic acids, adsorption of mycotoxins into the cell wall, and constitutively expressed enzymes capable of degrading mycotoxins. In general, these findings highlight the multifactorial nature of yeast-mediated mycotoxin removal and establish <i>P. fermentans</i> KCB21_L2 as a promising candidate for safe biological decontamination in food systems.