8-18: Partial or complete inclusion of Zygomycetes fungi in biorefineries

Zygomycetes fungi were evaluated for production of high-nutritional value biomass, ethanol, or both products from four compositionally different industrial streams; spent sulphite liquor, thin stillage, wheat-based liquefied mash, and cheese whey. Cultivation in 50% spent sulphite liquor using a 2 m high airlift reactor led to the production of up to 8 g/L of biomass containing up to 50% protein, 5% lipids, and 9% glucosamine. Thin stillage, a byproduct from a wheat-based ethanol facility with a solid content of 10%, was successfully used for Zygomycetes cultivation at 30-40°C and pH 4.5. During the fermentation, up to 15 g/L of biomass could be produced and the final effluent content had been decreased by 25% total solids, 80% lactic acid, and 80% glycerol. An additional 2 g/L ethanol was produced. Wheat starch-containing liquefied mash was also successfully utilized resulting in production of ethanol without addition of glucoamylases or any other medium supplementation at 37°C. In the range of liquefied mash concentrations tested (5, 10, 15, and 20%) the Zygomycetes performed well even at 15% in a batch process. Finally, Zygomycetes were evaluated for production of biomass and ethanol using cheese-whey as cultivation medium. After enzymatic hydrolysis of lactose, Zygomycetes could produce ethanol in SHF or SSF. Ethanol yields of ca 0.40 g/g were obtained.