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.
International Journal of Food Microbiology, 2014, Vol 186, p. 14-21
Amazon Rain Forest South America Neotropical region; Dicotyledones Angiospermae Spermatophyta Plantae (Angiosperms, Dicots, Plants, Spermatophytes, Vascular Plants) - Lecythidaceae  Bertholletia excelsa species Brazil nut common host; Fungi Plantae (Fungi, Microorganisms, Nonvascular Plants, Plants) - Fungi Imperfecti or Deuteromycetes  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