Background:
The trichothecene mycotoxin deoxynivalenol (DON) may be concentrated in dried distillers grains with solubles (DDGS), a co-product of fuel ethanol fermentation, when grain containing DON is used to produce fuel ethanol. Even low levels of DON ([less than or equal to] 5ppm) in DDGS sold as feed pose a significant threat to the health of monogastric animals. New and improved strategies to reduce DON in DDGS need to be developed and implemented to address this problem. Enzymes known as trichothecene 3-O-acetyltransferases convert DON to 3-acetyldeoxynivalenol (3ADON) and reduce its toxicity in plants and animals.
Results:
Two Fusarium trichothecene 3-O-acetyltransferases (FgTRI101 and FfTRI201) were cloned and expressed in yeast (Saccharomyces cerevisiae) during a series of small-scale barley (Hordeum vulgare) ethanol fermentations. DON was concentrated 1.6 to 8.2 times in DDGS compared to the starting ground grain. During the fermentation process, FgTRI101 converted 9.2% to 55.3% of DON to 3ADON, resulting in DDGS with reductions in DON and increases in 3ADON when Virginia winter barley cultivars Eve, Thoroughbred, and Price and experimental line VA06H-25 were used. Barley mashes from the barley line VA04B-125 showed that yeast expressing FfTRI201 were more effective at acetylating DON than FgTRI101; DON conversion for FfTRI201 ranged from 26.1% to 28.3%, while FgTRI101 ranged from 18.3% to 21.8% in VA04B-125 mashes. Ethanol yields were highest with the industrial yeast strain Ethanol Red (R), which also consumed galactose when present in the mash.
Conclusions:
This study demonstrates the potential of using yeast expressing a trichothecene 3-O-acetyltransferase to modify DON during commercial fuel ethanol fermentation.Source:
http://www.biotechnologyforbiofuels.com/rss/