Efficacy of saprophytic yeasts on growth of Aspergillus flavus and aflatoxin production

Document Type: Original Article

Authors

1 Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

2 Pistachio Research Center, Horticultural Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Rafsanjan, Iran

3 Plant Protection Research Department, Yazd Agricultural and Natural Resources Research and Education Center, AREEO, Yazd, Iran

Abstract

Background: Contamination of pistachio nuts with aflatoxin, which produces strains of Aspergillus section Flavi, has been
a concern for the human and animal health and food safety.
Materials and Methods: Competitive ability of saprophytic yeasts in interfering with toxigenic strain of Aspergillus flavus
was assessed through different experiments. 186 soil samples were collected from different agro-ecological zones of pistachio
growing areas of Kerman province. A serial dilution method and YMA media were used to isolate yeast strains. Overall, 60
yeast isolates were screened for their ability to reduce the biomass of Aspergillus flavus via dual culture assays.
Results: The highest inhibition was achieved by five yeast isolates in the ranges 38 to 82%. Other investigations have
demonstrated the presence of significant interactions between saprophytic yeasts and A. flavus on biomass and aflatoxin
production. The highest rate of reduction belonged to the IPRIY-43 and IPRIY-39 which reduced the growth of A. flavusin
culture media.
Conclusions: Quantitative assessments showed the ability of five selected yeast isolates to reduce aflatoxin production by
85-98% in dual culture assays. More investigations are required to understand the ability of yeast isolates to reduce aflatoxin
production with toxigenic strains of A. flavus and withstand predominant abiotic stresses.

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