Conversion of deoxynivalenol to 3-acetyldeoxynivalenol in barley-derived fuel ethanol co-products with yeast expressing trichothecene 3-O-acetyltransferases

<p>Abstract</p> <p>Background</p> <p>The trichothecene mycotoxin deoxynivalenol (DON) may be concentrated in distillers dried 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 (≤ 5 ppm) 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-<it>O-</it>acetyltransferases convert DON to 3-acetyldeoxynivalenol (3ADON), and may reduce its toxicity in plants and animals.</p> <p>Results</p> <p>Two <it>Fusarium </it>trichothecene 3-<it>O-</it>acetyltransferases (FgTRI101 and FfTRI201) were cloned and expressed in yeast (<it>Saccharomyces cerevisiae</it>) during a series of small-scale ethanol fermentations using barley (<it>Hordeum vulgare</it>). DON was concentrated 1.6 to 8.2 times in DDGS compared with the starting ground grain. During the fermentation process, FgTRI101 converted 9.2% to 55.3% of the DON to 3ADON, resulting in DDGS with reductions in DON and increases in 3ADON in the Virginia winter barley cultivars Eve, Thoroughbred and Price, and the experimental line VA06H-25. Analysis of barley mashes prepared from the barley line VA04B-125 showed that yeast expressing FfTRI201 were more effective at acetylating DON than those expressing FgTRI101; DON conversion for FfTRI201 ranged from 26.1% to 28.3%, whereas DON conversion for FgTRI101 ranged from 18.3% to 21.8% in VA04B-125 mashes. Ethanol yields were highest with the industrial yeast strain Ethanol Red^®, which also consumed galactose when present in the mash.</p> <p>Conclusions</p> <p>This study demonstrates the potential of using yeast expressing a trichothecene 3-<it>O</it>-acetyltransferase to modify DON during commercial fuel ethanol fermentation.</p

Valorization of coffee byproducts for bioethanol production using lignocellulosic yeast fermentation and pervaporation

Industrial residue management is a critical element of sustainable development. The aim of this research was to investigate the potential of different coffee waste fractions for bioethanol fermentation and its purification by pervaporation; these fractions and the role of pervaporation in this application have not been studied before. Bioethanol production from different coffee waste fractions has now been studied by acid or acid and enzymatic hydrolysis. The fermentation was conducted using two different yeasts (baker’s yeast and lignocellulosic yeast). By using the cellulolytic enzymes and lignocellulosic yeast, a higher bioethanol yield was achieved. Further purification of the fermented filtrate was carried out by an alcohol selective pervaporation membrane at four temperatures (23, 30, 40 and 50 °C). Hydrolysis of the samples using cellulose complex and β-glucosidase enzymes and fermentation with lignocellulosic yeast, followed by purification using pervaporation resulted a superior bioethanol yield of 51.7 ± 7.4 g/l for spent coffee and 132.2 ± 40 g/l for husk. Husk hydrolysis using cellulolytic enzymes and fermentation with lignocellulosic yeast, followed by product recovery through pervaporation membrane, was found to be the optimal procedure, producing ethanol at a concentration of 132.2 ± 40 g/l. In general, husk hydrolysis using acid and cellulolytic hydrolysis and fermentation with lignocellulosic yeast GSE16-T18 followed by pervaporation was found to be the best process for producing the highest ethanol yield compared to the other fractions of coffee waste samples

Anaerobes in industrial- and environmental biotechnology

Anaerobic microorganisms present in diverse ecological niches employ alternative strategies for energy conservation in the absence of oxygen which enables them to play a key role in maintaining the global cycles of carbon, nitrogen, and sulfur, and the breakdown of persistent compounds. Thereby they become useful tools in industrial and environmental biotechnology. Although anaerobes have been relatively neglected in comparison to their aerobic counterparts, with increasing knowledge about their diversity and metabolic potential and the development of genetic tools and process technologies to utilize them, we now see a rapid expansion of their applications in the society. This chapter summarizes some of the developments in the use of anaerobes as tools for biomass valorization, in production of energy carriers and chemicals, wastewater treatment, and the strong potential in soil remediation. The ability of several autotrophic anaerobes to reduce carbon dioxide is attracting growing attention as a means for developing a platform for conversion of waste gases to chemicals, materials, and biofuels