Complex regulation of the aflatoxin biosynthesis gene cluster of Aspergillus flavus in relation to various combinations of water activity and temperature

Int J Food Microbiol. 2009 Nov 15;135(3):231-7. doi: 10.1016/j.ijfoodmicro.2009.07.026. Epub 2009 Jul 30.

Abstract

A microarray analysis was performed to study the effect of varying combinations of water activity and temperature on the activation of aflatoxin biosynthesis genes in Aspergillusflavus grown on YES medium. Generally A. flavus showed expression of the aflatoxin biosynthetic genes at all parameter combinations tested. Certain combinations of a(w) and temperature, especially combinations which imposed stress on the fungus resulted in a significant reduction of the growth rate. At these conditions induction of the whole aflatoxin biosynthesis gene cluster occurred, however the produced aflatoxin B(1) was low. At all other combinations (25 degrees C/0.95 and 0.99; 30 degrees C/0.95 and 0.99; 35 degrees C/0.95 and 0.99) a reduced basal level of cluster gene expression occurred. At these combinations a high growth rate was obtained as well as high aflatoxin production. When single genes were compared, two groups with different expression profiles in relation to water activity/temperature combinations occurred. These two groups were co-ordinately localized within the aflatoxin gene cluster. The ratio of aflR/aflJ expression was correlated with increased aflatoxin biosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aflatoxins / biosynthesis
  • Aflatoxins / genetics*
  • Aspergillus flavus / genetics*
  • Aspergillus flavus / growth & development
  • Aspergillus flavus / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Gene Expression
  • Gene Expression Profiling
  • Gene Expression Regulation, Fungal*
  • Genes, Fungal*
  • Microarray Analysis
  • Multigene Family
  • Stress, Physiological
  • Temperature*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Water / physiology*

Substances

  • AFLR protein, Aspergillus
  • Aflatoxins
  • DNA-Binding Proteins
  • Fungal Proteins
  • Transcription Factors
  • Water