Aflatoxin Contamination, Its Impact and Management Strategies: An Updated Review

Abstract

Aflatoxin, a type of mycotoxin, is mostly produced by Aspergillus flavus and Aspergillus parasiticus. It is responsible for the loss of billions of dollars to the world economy, by contaminating different crops such as cotton, groundnut, maize, and chilies, and causing immense effects on the health of humans and animals. More than eighteen different types of aflatoxins have been reported to date, and among them, aflatoxins B1, B2, G1, and G2 are the most prevalent and lethal. Early detection of fungal infection plays a key role in the control of aflatoxin contamination. Therefore, different methods, including culture, chromatographic techniques, and molecular assays, are used to determine aflatoxin contamination in crops and food products. Many countries have set a maximum limit of aflatoxin contamination (2-20 ppb) in their food and agriculture commodities for human or animal consumption, and the use of different methods to combat this menace is essential. Fungal infection mostly takes place during the pre- and post-harvest stage of crops, and most of the methods to control aflatoxin are employed for the latter phase. Studies have shown that if correct measures are adopted during the crop development phase, aflatoxin contamination can be reduced by a significant level. Currently, the use of bio-pesticides is the intervention employed in many countries, whereby atoxigenic strains competitively reduce the burden of toxigenic strains in the field, thereby helping to mitigate this problem. This updated review on aflatoxins sheds light on the sources of contamination, and the on occurrence, impact, detection techniques, and management strategies, with a special emphasis on bio-pesticides to control aflatoxins.

Keywords: Aspergillus; aflatoxins; control measures; detection.

Figure 1

Cultures of Aspergillus flavus after exposure to ammonia vapors. (a) Cultures showing a highly toxigenic strain, based on their change in color to dark plum after exposure, (b–d) cultures showing moderately toxigenic stains based on their change in color to light reddish to pinkish color after exposure, (e,f) cultures showing atoxigenic strains with no change in color (Saba and Atif, unpublished data).

Figure 2

Schematic diagram showing the principle of biocontrol pesticides. During normal environmental conditions, usually ratios of toxigenic spores are higher than the atoxigenic spores present in the field. After the application of bio-pesticide, the atoxigenic spores are increased and competitively exclude naturally occurring toxigenic strains.

Figure 3

Map showing the countries where bio-pesticide is under the process of being developed. It includes Pakistan, China, Iran, and Thailand in Asia; Senegal, Ghana and Nigeria in Africa; Italy, Romania, Serbia, and Spain in Europe; U.S.A and Cost Rica in North America; Brazil and Argentina in South America; and in Australia.