GENETICS AND PHYSIOLOGY OF AFLATOXIN BIOSYNTHESIS

TLDR

Aflatoxins are the most studied mycotoxins, with 17 genes cloned that encode 12 enzymatic steps, regulated by a Zn(II)2Cys6 transcription factor and linked to development, yet global regulatory and physiological factors remain poorly understood. This chapter aims to review the molecular biology and genetics of aflatoxin biosynthesis and to summarize the physiological factors that influence its formation. The review consolidates current knowledge and identifies key physiological determinants that modulate aflatoxin production.

Abstract

Aflatoxins are the most thoroughly studied mycotoxins. Elegant early research on the biosynthetic scheme of the pathway has allowed a molecular characterization of aflatoxin biosynthesis and its regulation. Genetic studies on aflatoxin biosynthesis in Aspergillus flavus and A. parasiticus, and sterigmatocystin biosynthesis in A. nidulans, led to the cloning of 17 genes responsible for 12 enzymatic conversions in the AF/ST pathways. Pathway-specific regulation is by a Zn(II)2Cys6 DNA-binding protein that regulates the transcription of all pathway genes. Less is known about the global factors that regulate aflatoxin biosynthesis, but there is a clear link between development and aflatoxin biosynthesis. There is also a large body of information on physiological factors involved in aflatoxin biosynthesis, but it has been difficult to understand their role in the regulation of this pathway. This chapter discusses current knowledge on the molecular biology and genetics of the pathway, and provides a summary of the physiological factors known to influence aflatoxin formation.