Research

Brazil nuts are subject to infection with B and G aflatoxin-producing fungus, Aspergillus pseudonomius

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Abstract

The exploitation of the Brazil nut is one of the most important activities of the extractive communities of the Amazon rainforest. However, its commercialization can be affected by the presence of aflatoxins produced by fungi, namely Aspergillus section Flavi. In the present study, we investigated a collection of Aspergillus nomius strains isolated from Brazil nuts using different approaches, including morphological characters, RAPD and AFLP profiles, partial beta-tubulin and calmodulin nucleotide sequences, aflatoxin patterns, as well as tolerance to low water activity in cultured media. Results showed that most of the isolates do belong to A. nomius species, but a few were re-identified as Aspergillus pseudonomius, a very recently described species. The results of the analyses of molecular variance, as well as the high pairwise F-ST values between A. nomius and A. pseudonomius suggested the isolation between these two species and the inexistence of gene flow. Fixed interspecific nucleotide polymorphisms at beta-tubulin and calmodulin loci are presented. All A. pseudonomius strains analyzed produced aflatoxins AFB1, AFB2, AFG1 and AFG2. This study contains the first-ever report on the occurrence in Brazil nuts of A. pseudonomius. The G-type aflatoxins and the mycotoxin tenuazonic acid are reported here for the first time in A. pseudonomius.

Amazon Rain Forest South America Neotropical region Dicotyledones Angiospermae Spermatophyta Plantae (Angiosperms Dicots Plants Spermatophytes Vascular Plants) - Lecythidaceae [26250] Bertholletia excelsa species Brazil nut common host Fungi Plantae (Fungi Microorganisms Nonvascular Plants Plants) - Fungi Imperfecti or Deuteromycetes [15500] Aspergillus nomius species pathogen Aspergillus pseudonomius species pathogen Aspergillus pseudonomius benA gene [Fungi Imperfecti or Deuteromycetes] polymorphism Aspergillus pseudonomius cmd gene [Fungi Imperfecti or Deuteromycetes] polymorphism aflatoxin B-1 1162-65-8 synthesis aflatoxin B2 7220-81-7 aflatoxin G-1 1165-39-5 aflatoxin G2 7241-98-7 beta-tubulin calmodulin tenuazonic acid 75652-74-3 toxin mycotoxin 03502 Genetics - General 03504 Genetics - Plant 10060 Biochemistry studies - General 10062 Biochemistry studies - Nucleic acids purines and pyrimidines 10064 Biochemistry studies - Proteins peptides and amino acids 13502 Food technology - General and methods 13504 Food technology - Fruits nuts and vegetables 22501 Toxicology - General and methods 22502 Toxicology - Foods food residues additives and preservatives 36001 Medical and clinical microbiology - General and methods Foods Infection Molecular Genetics Toxicology Brazil nut infection Infection (MeSH) infectious disease etiology Biochemistry and Molecular Biophysics