Are zearalenone and fumonisins common Fusarium contaminants in cereal grains?

Zearalenone and fumonisins are established Fusarium mycotoxins of practical relevance in cereal-grain food chains, particularly maize. The claim is supported, with the storage relationship best understood as a contributor to toxin formation and persistence rather than the sole origin of contamination.

Occurrence in cereals

• Global raw-grain surveillance detected fumonisins in 61% and zearalenone in 46% of samples. Fumonisins are especially prominent in maize and maize-derived foods; fumonisin B1 (FB1) typically represents about 70–80% of fumonisins in culture, while FB3 is another recognized congener.
• Zearalenone occurs in maize as well as wheat, barley, oats, rye, and sorghum. EU commodity-specific maximum levels for zearalenone in cereals and for fumonisins B1+B2 in maize products reinforce their established food-contaminant status.

Fungal and mechanistic basis

• Zearalenone production is well characterized in Fusarium graminearum sensu lato and F. culmorum. In F. graminearum, PKS4, PKS13, ZEB1, and ZEB2 participate in its biosynthetic pathway.
• Fumonisins are principally produced by F. verticillioides and F. proliferatum, particularly in maize-associated environments. The FUM biosynthetic gene cluster—initiated by Fum1—supports fungal synthesis of the fumonisin backbone and congener diversity.

Storage implications

• Warm, humid storage promotes fungal growth and toxin production: fumonisins in maize were greatest under high water activity at 30°C, and maize stored for six months at 80% relative humidity accumulated substantially more zearalenone than grain at lower humidity.
• However, infection and contamination often begin preharvest; cool, dry storage may preserve rather than eliminate toxin already present. Drying, aeration, hygienic storage, and moisture/temperature monitoring are therefore central preventive measures.

Bottom line

• Zearalenone and fumonisins are commonly Fusarium-associated contaminants of cereal grains, especially maize; inadequate warm, humid storage can worsen contamination but is not its exclusive cause.