Interfungal Volatile Signals Regulate Growth and Mycotoxin Production of Aspergillus parasiticus and Fusarium...

Fusarium verticillioides and Aspergillus parasiticus are typical fungi of stored maize. To prevail over other organisms when competing for a substrate, fungi emit volatile organic compounds (VOCs) with different bioactivities. The aim of this study was to evaluate A. parasiticus and F. verticillioides interaction in maize grains stored in silo bags at different initial humidities (iH; 7.5% or 28%) for 28 days. For each treatment, dry grain weight loss, maize fungal infection, filamentous fungi count, ergosterol content, FB₁ and AFB₁ content, and VOCs were determined. In silo bags, A. parasiticus caused greater surface infection of the grains compared to F. verticillioides, both individually and in co-infection. In co-infection, the number of colony forming units (CFU/ g) of both fungi decreased at 28% of iH, while at 7.5% there was only a decrease in F. verticillioides. There was greater weight loss at 28% iH and in the presence of A. parasiticus. Fumonisin B₁ decreased in co-infection. The ergosterol content increased at 28% iH. Qualitative and quantitative changes in VOCs profile were observed at different iH and according to the presence of fungi. 1-octen-3-ol, 3-octanone, methoxybenzene and 2-pentyl furan were the main VOCs identified. Of these compounds, 1-octen-3-ol reduced the growth and mycotoxin production of both fungi. The 1-octen-3-ol, along with other major VOCs, may support the natural regulatory mechanism between fungi during their interaction in maize stored in silo bags.