Identification of ochratoxin A producing fungi associated with fresh and dry liquorice

PLoS One. 2013 Oct 21;8(10):e78285. doi: 10.1371/journal.pone.0078285. eCollection 2013.

Abstract

The presence of fungi on liquorice could contaminate the crop and result in elevated levels of mycotoxin. In this study, the mycobiota associated with fresh and dry liquorice was investigated in 3 producing regions of China. Potential toxigenic fungi were tested for ochratoxin A (OTA) and aflatoxin B1 (AFB1) production using liquid chromatography/mass spectrometry/mass spectrometry. Based on a polyphasic approach using morphological characters, β-tubulin and RNA polymerase II second largest subunit gene phylogeny, a total of 9 genera consisting of 22 fungal species were identified, including two new Penicillium species (Penicillium glycyrrhizacola sp. nov. and Penicillium xingjiangense sp. nov.). The similarity of fungal communities associated with fresh and dry liquorice was low. Nineteen species belonging to 8 genera were detected from fresh liquorice with populations affiliated with P. glycyrrhizacola, P. chrysogenum and Aspergillus insuetus comprising the majority (78.74%, 33.33% and 47.06% of total) of the community from Gansu, Ningxia and Xinjiang samples, respectively. In contrast, ten species belonging to 4 genera were detected from dry liquorice with populations affiliated with P. chrysogenum, P. crustosum and Aspergillus terreus comprising the majority (64.00%, 52.38% and 90.91% of total) of the community from Gansu, Ningxia and Xinjiang samples, respectively. Subsequent LC/MS/MS analysis indicated that 5 fungal species were able to synthesize OTA in vitro including P. chrysogenum, P. glycyrrhizacola, P. polonicum, Aspergillus ochraceus and A. westerdijkiae, the OTA concentration varied from 12.99 to 39.03 µg/kg. AFB1 was absent in all tested strains. These results demonstrate the presence of OTA producing fungi on fresh liquorice and suggest that these fungi could survive on dry liquorice after traditional sun drying. Penicillium chrysogenum derived from surrounding environments is likely to be a stable contributor to high OTA level in liquorice. The harvesting and processing procedure needs to be monitored in order to keep liquorice free of toxigenic fungi.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aflatoxin B1 / chemistry
  • China
  • Chromatography, Liquid / methods
  • Food Contamination / analysis
  • Fungi / chemistry*
  • Glycyrrhiza / chemistry*
  • Glycyrrhiza / microbiology*
  • Mycotoxins / chemistry*
  • Ochratoxins / chemistry*
  • Phylogeny
  • RNA Polymerase II / chemistry
  • Tandem Mass Spectrometry / methods
  • Tubulin / chemistry

Substances

  • Mycotoxins
  • Ochratoxins
  • Tubulin
  • ochratoxin A
  • Aflatoxin B1
  • RNA Polymerase II

Grants and funding

This study was supported by the National Natural Science Foundations of China no. 30973882 and no 81274071. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.