Isolation and identification of fungi from a meju contaminated with aflatoxins

J Microbiol Biotechnol. 2012 Dec;22(12):1740-8. doi: 10.4014/jmb.1207.07048.

Abstract

A home-made meju sample contaminated naturally with aflatoxins was used for isolation of fungal strains. Overall, 230 fungal isolates were obtained on dichloran rosebengal chloramphenicol (DRBC) and dichloran 18% glycerol (DG18) agar plates. Morphological characteristics and molecular analysis of a partial beta-tubulin gene and the internal transcribed spacer (ITS) of rDNA were used for the identification of the isolates. The fungal isolates were divided into 7 genera: Aspergillus, Eurotium, Penicillium, Eupenicillium, Mucor, Lichtheimia, and Curvularia. Three strains from 56 isolates of the A. oryzae/flavus group were found to be aflatoxigenic A. flavus, by the presence of the aflatoxin biosynthesis genes and confirmatory aflatoxin production by high-performance liquid chromatography (HPLC). The predominant isolate from DRBC plates was A. oryzae (42 strains, 36.2%), whereas that from DG18 was A. candidus (61 strains, 53.5%). Out of the 230 isolates, the most common species was A. candidus (34.3%) followed by A. oryzae (22.2%), Mucor circinelloides (13.0%), P. polonicum (10.0%), A. tubingensis (4.8%), and L. ramosa (3.5%). A. flavus and E. chevalieri presented occurrence levels of 2.2%, respectively. The remaining isolates of A. unguis, P. oxalicum, Eupenicillium cinnamopurpureum, A. acidus, E. rubrum, P. chrysogenum, M. racemosus, and C. inaequalis had lower occurrence levels of < 2.0%.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aflatoxins / chemistry*
  • Aflatoxins / genetics
  • Chromatography, High Pressure Liquid
  • Culture Media
  • DNA, Fungal / analysis
  • DNA, Fungal / chemistry
  • DNA, Fungal / genetics
  • Fermentation
  • Food Microbiology
  • Fungi / classification*
  • Fungi / genetics
  • Fungi / isolation & purification*
  • Glycine max / chemistry
  • Glycine max / microbiology*
  • Phylogeny

Substances

  • Aflatoxins
  • Culture Media
  • DNA, Fungal