Integrated high-throughput sequencing and UFLC-MS/MS to explore the correlation between fungal diversity and mycotoxins in Coix seed

This study investigated the fungal profiles and the relationship between mycotoxins and fungal communities in Coix seed ( Coix lacryma-jobi L.) by using high-throughput sequencing and ultra-fast liquid chromatography-tandem mass spectrometry. Results showed that zearalenone (ZEN) was prone to contaminating Coix seeds. Among four groups of Coix seeds, only stir-fried samples stored at room temperature showed no significant fluctuations in ZEN content. The stir-frying process had a significant impact on the fungal community composition. Moreover, environmental humidity exerted a stronger effect on the fungal community of stir-fried Coix seeds than on that of raw samples. A total of 6 genera of fungi were negatively correlated with ZEN and Fusarium . These fungi possessed antibacterial properties or could potentially degrade ZEN. In the stir-fried samples stored at room temperature, the abundance of Rhizopus oryzae, which has been reported to possess ZEN-degrading potential and showed a strong negative correlation with ZEN content, was significantly different from the other three groups. This might be one of the crucial reasons why no increase in ZEN content was observed. Collectively, these results indicated that regardless of whether Coix seeds were stir-fried or not, the storage environment factors including the temperature, humidity, and water activity would affect the composition of the fungal community on their surface and the content of the harmful ZEN.