Aflatoxins and ochratoxins in cereal grains: an open challenge

The environmental, physiological and molecular factors related with aflatoxin and ochratoxin production by fungal species are reviewed. Concerning aflatoxins, the main steps that have lead to the knowledge of their biosynthesis gene cluster are reported and the experimental work that has allowed to determine different control strategies is underlined. Concerning ochratoxins, the biosynthetic pathway and the main implications in animal and human toxicity are presented. The role played by lipoperoxides in the secondary metabolism and toxin production is emphasized. A view of the different control system through prevention, decontamination and detoxification is described. The importance of preventive strategies (physical, chemical, biological and genetic approaches) in the control of such widespread and toxic metabolites is pointed out.