Aflatoxins: Occurrence, Biosynthesis Pathway, Management, and Impact on Health

Abstract

Fungi produce several types of mycotoxins such as aflatoxin, ochratoxin, and zearalenone in agriculture products, foods and feeds as a part of their normal growth. Although mycotoxins are not essentially required for normal fungal growth, they cause various complications, including toxicity and diseases, when ingested by livestock and humans. Aspergillus, Penicillium, and Fusarium are some of the examples of mycotoxin producers. Agricultural and food products such as maize, wheat, and soybean used as animal feed are usually contaminated with aflatoxins. Bioaccumulation of toxins in tissues is fatal to livestock. Aspergillus species such as aflatoxin producing A. flavus are ubiquitous, and heat-stable aflatoxin makes it resistant to destruction by physical or industrial processes. Thus, preventive measures must be taken during production and storage. Some toxins, known as modified mycotoxins, may remain undetected during testing. These may form in plants as a part of the defense mechanism against fungi or during food processing and can be converted to parent mycotoxins in the digestive tract causing fatality. Aflatoxins can be eliminated by enzymatic transformation, microbial biodegradation, or by the use of phytochemicals including antioxidants like gallic acid and quercetin that suppress aflatoxin biosynthesis. Many strains of Rhodococcus sp. are known to cause multi-mycotoxin degradation. Microbial mycotoxin degrading enzymes can be used as food additives or to decontaminate agricultural commodities. Plants can be genetically engineered to express detoxification genes to prevent pre-harvest contamination. This chapter focuses on aflatoxin contamination and methods to control it.