Occurrence of fungi and mycotoxins in herbal medicines and rapid detection of toxin-producing fungi*

Contamination from external hazardous materials may greatly influence the safety and efficacy of herbal medicines. This paper aimed to evaluate the levels of contamination by mycotoxins and toxigenic fungi in herbal medicines and establish a rapid method for detecting toxin-producing fungi. Herein, 62.92%, 36.25%, and 64.17% of herbal medicines were contaminated by aflatoxins (AFs), ochratoxins, and fumonisins, respectively. Aspergillus (43.77%), Fusarium (5.17%), and Cladosporium (4.46%) were the three predominant genera. Spearman's correlation results showed that Aspergillus and Fusarium were significantly and positively correlated with mycotoxin content (R > 0.5, P < 0.05). In addition, 323 fungal strains were isolated from herbal medicines, and 20 species were identified, mainly belonging to Aspergillus and Penicillium. Analysis of potential mycotoxinproducing fungi showed that Aspergillus flavus can produce AFs, and Aspergillus ochraceus and Aspergillus niger can produce ochratoxin A (OTA). Multiplex real-time polymerase chain reaction showed that A. flavus harbored AF synthesis genes (aflR), and A. ochraceus and A. niger harbored OTA synthesis genes (aoksl). With these synthesis genes, 67.07% and 37.20% of 164 herbal medicines were positive for toxigenic genes. Furthermore, an excellent correlation was found between the above gene copies and mycotoxin content (R2 = 0.99). Our results confirmed the high detection rate of mycotoxins in herbal medicines and identified pivotal AF- and OTAproducing fungi. In conclusion, this paper provided the contamination status of fungi and mycotoxins in herbal medicines and established a rapid method for detecting toxigenic fungi.

Automated summary

This study aimed to evaluate the contamination levels of mycotoxins and toxigenic fungi in herbal medicines and establish a rapid method for detecting toxin-producing fungi. The results showed high contamination rates of aflatoxins (AFs), ochratoxins, and fumonisins in herbal medicines. Several species of Aspergillus were identified as key toxin-producing fungi. Using multiplex real-time polymerase chain reaction, toxin synthesis genes were successfully detected. This study provided valuable insights into the contamination status of fungi and mycotoxins in herbal medicines and developed a rapid method for detecting toxigenic fungi.