Occurrence of Toxigenic Fungi and Mycotoxins on Root Herbs from Chinese Markets

Abstract

Herbs derived from roots, leaves, flowers, or fruits of plants are unavoidably contaminated with fungi and mycotoxins during growth, harvest, and storage, thereby posing a health threat to humans. Especially, root herbs (RHs) are more easily contaminated with fungi and mycotoxins because the roots are in direct contact with the soil. Here, we investigated the occurrence of fungi, aflatoxins (AFs), and ochratoxin A (OTA) in eight RHs that are used as medicines, beverages, dietary supplements, and functional foods in China and other countries. Morphological observation and MultiGeneBlast (β-tubulin and calmodulin) were used to identify the potentially toxigenic fungi. Of the 48 samples tested, all were contaminated by fungi, and 1,844 isolates belonging to 25 genera were detected. The genera Aspergillus and Penicillium, which contain potentially toxigenic fungal species, represented a frequency of 10 and 25%, respectively. Thirty-three isolates of Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger, and Penicillium polonicum were arbitrarily selected for analysis of their toxigenic potential. Five of 13 isolates of A. flavus and 1 isolate of A. parasiticus produced AFs, whereas OTA production was not detected for any of the isolates of A. niger and P. polonicum. The occurrence of AFs and OTA in the 48 samples of eight RHs was tested by ultraperformance liquid chromatography-tandem mass spectrometry; 37.50% of samples from six RHs were contaminated with AFs and 16.67% of samples from four RHs were contaminated with OTA. Seven (14.58%) and four (8.33%) samples of ginseng, polygala, and liquorice exceeded the permissible limits of aflatoxin B and AFs, respectively. Because ginseng, polygala, and liquorice are widely used as herbs, dietary supplements, and functional foods, the high frequency of AF contamination of these herbs indicated by our current study warrant attention to raise public awareness.

Analysis of the Fungal Community in Ziziphi Spinosae Semen through High-Throughput Sequencing

“…Zheng et al [34] also showed the widespread fungal contamination in 15 medicinal herbs collected from China. Meanwhile, Su et al [35] found that 48 samples of eight root herbs from Chinese markets are all contaminated by fungi. In all these studies, Aspergillus and Penicillium are identified as the most common contaminants.…”

Quality of Dietary Supplements Containing Plant-Derived Ingredients Reconsidered by Microbiological Approach

“…Fungi of the types: Aspergillus , Penicillium , Fusarium and Alternaria , under favorable conditions, are capable of producing secondary metabolites—mycotoxins [ 7 , 42 , 44 , 45 , 46 , 47 , 48 ].…”

Mycotoxin Contamination Concerns of Herbs and Medicinal Plants

“…Therefore, the plant has been studied for mycotoxicological contamination. The results showed that sampled ginseng roots had significant levels of AFs which exceeded acceptable standards [38,65] (Table 5).…”

“…Other countries have set similar regulations, although the maximum tolerated levels can vary. For example, the maximum limit for aflatoxin in India appears to be much higher (30 µg/kg) than in other countries [37,38]. In China, 5 to 20 µg/kg is the maximum limit depending upon the classification of the medicinal herb under consideration [33,36,39].…”