Mechanisms of detoxification and transcriptional response of Pichia fermentans KCB21_L2 to mycotoxins

The presence of mycotoxins in food poses a significant risk to food safety, emphasizing the need for effective and safe detoxification strategies such as biological approaches. In this study, we demonstrate the strong ability of Pichia fermentans KCB21_L2, a yeast isolated from kefir, to detoxify AFB1, FB1 and OTA. Viable cells removed AFB1 and FB1 more efficiently than heat-inactivated cells, particularly at pH 5.5 and 7.0, suggesting the involvement of active detoxification processes. To explore this further, we evaluated the yeast's capacity to eliminate higher mycotoxin concentrations and investigated the underlying molecular and cellular responses. P. fermentans KCB21_L2 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 mycotoxin-degrading enzymes was observed, indicating that detoxification may involve multiple factors, including stress response pathways, possible production of organic acids, adsorption of mycotoxins to the cell wall and constitutively expressed enzymes capable of degrading mycotoxins. In general, these findings highlight the multifactorial nature of yeast-mediated mycotoxin detoxification and establish P. fermentans KCB21_L2 as a promising candidate for safe biological detoxification in food systems.