Toxin-producing fungi and exogenous fungi on Citri reticulatae pericarpium

Abstract:

[Background] Citri reticulatae pericarpium is a widely used Chinese medicinal material with both medical and edible values.The growing of fungi and the production of mycotoxins by fungi during storage at proper humidity and temperature pose a threat to the quality and safety of Citri reticulatae pericarpium.[Objective] In order to analyze the composition of exogenous fungi and the toxin-producing fungi on Citri reticulatae pericarpium.[Methods] The exogenous fungi were isolated by plate dilution method and identified based on the morphological characteristics and sequence analysis.The toxin-producing fungi were detected by ultra-high performance liquid chromatography coupled to tandem quadrupole mass spectrometry (UPLC-MS/MS).[Results] A total of 132 strains of exogenous fungi were isolated from Citri reticulatae pericarpium.They were identified to belong to Ascomycota(98.48%) and Mucoromycota(1.52%),including Eurotiomycetes(95.45%),Dothideomycetes(3.03%) and Mucoromycetes(1.52%).Seventy-seven strains belonged to Aspergillus spp.,which was dominant on Citri reticulatae pericarpium,followed by Penicillium spp.The strains of Aspergillus spp.and Penicillium spp.were detected by UPLC-MS/MS.One strain of toxin-producing fungi was screened out and identified as A.flavus JXCP1-3,which can produce 1.52 ng/mL aflatoxin B₁.[Conclusion] We comprehensively analyzed the exogenous fungi and toxin-producing fungi on the surface of Citri reticulatae pericarpium,which provided a basis for the prevention and control of the toxin-producing fungi.

Key words:Citri reticulatae pericarpium;exogenous fungi;Aspergillus flavus;aflatoxins