Current understanding on aflatoxin biosynthesis and future perspective in reducing aflatoxin contamination

Abstract

Traditional molecular techniques have been used in research in discovering the genes and enzymes that are involved in aflatoxin formation and genetic regulation. We cloned most, if not all, of the aflatoxin pathway genes. A consensus gene cluster for aflatoxin biosynthesis was discovered in 2005. The factors that affect aflatoxin formation have been studied. In this report, the author summarized the current status of research progress and future possibilities that may be used for solving aflatoxin contamination.

Figure 1

Aflatoxin pathway gene cluster in A. flavus. This figure shows the order and location of the 30 aflatoxin pathway genes plus an aflR antisense gene clustered together in about 80 kb DNA region. The old gene names are labeled on top of the line and the new gene names sysmatically renamed according to gene convention are labeled below the line [81]. The transcripts of hypA, hypB, hypC, hypD, hypE and aflRas are identified through Aspergillus flavus EST. Arrows indicate the direction of gene transcription.

Figure 2

The schematic aflatoxin biosynthetic pathway is presented. The arrows indicate the pathway steps from previous precursor to the next intermediate towards the formation of aflatoxins. The abbreviations are shown on the right.