Innovative Technologies To Control Mycotoxin Contamination

Cereal grains in most developing countries commonly are contaminated with mycotoxins produced primarily by fungi in the Aspergillus and Fusarium genera.  Aflatoxins, produced by several Aspergillus species, are the best known, while fumonisins, produced by several Fusarium species, also are a widespread, serious contaminant.  Both toxins are more common in maize than they are in indigenous African grains, e.g., sorghum and millet.  Sorghum and millets also thrive under hot, dry conditions, while maize yields poorly.  Encouraging maize cultivation on marginal lands under suboptimal conditions increases the likelihood and severity of the mycotoxin contamination in grain usually consumed by the poorest farmers in the region.  As global climate change pushes African climates to further extremes, this problem will increase.  Reevaluation of the native African cereals to address nutritional needs is seriously needed given their generally low level of mycotoxin contamination.  Many Fusarium spp. grow endophytically within the plant and produce toxin only when the host matures or becomes stressed.  Identifying signals that shift the fungus from endophyte to pathogen and/or trigger toxin biosynthesis could identify critical points for controlling disease and toxin production.  One approach to reducing aflatoxin levels is biocontrol with aflatoxin-nonproducing strains of Aspergillus.  A similar strategy for fumonisins is possible, but would require more significant strain development than is needed for Aspergillus.  This biocontrol method also may not reduce losses due to plant disease caused by the biocontrol strains.  Mycotoxin-contaminated grain has its biggest impact in rural areas.  Traders usually purchase only the best grain from rural farmers.  Rural inhabitants often eat a diet composed primarily of maize, perhaps as much as 500 g/person/day.  Thus, rural farmers in less developed countries are exposed to higher levels of toxins than almost anyone else on the planet.  They eat the most heavily contaminated grain available, and they eat more of it.  SPSS trade restrictions similarly concentrate contaminated foods in these countries, as only relatively uncontaminated foods are allowed into international commerce leaving highly contaminated foodstuffs concentrated in countries with the least ability to deal with it.  Policies that ensure food security in rural regions and that allow contaminated grain to be blended and used for other purposes are needed to remove this contaminated grain from the human food chain and enable its effective utilization.