INDUSTRIALLY ROBUST ENZYMES AND MICROORGANISMS FOR PRODUCTION OF SUGARS AND ETHANOL FROM AGRICULTURAL BIOMASS
Location: National Center for Agricultural Utilization Research
Title: Developing herbaceous energy crops as feedstocks for biofuel production
Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 12, 2007
Publication Date: November 1, 2007
Citation: Dien, B.S., Jung, H.G., Vogel, K.P., Casler, M.D., Lamb, J.F., Iten, L.B., Mitchell, R., Sarath, G. 2007. Developing herbaceous energy crops as feedstocks for biofuel production. In: Proceedings of the UJNR Food and Agricultural Panel, October 21-25, 2007, Tsukuba, Japan. p. 137-140.
Switchgrass, giant canary reed, and alfalfa stems were evaluated as feedstocks for biochemical conversion to biofuels. The sample set consisted of field-grown samples of each of these species harvested at multiple maturities. The samples were examined for chemical composition. All the samples contained over 50% carbohydrates, and the next largest fraction was Klasson lignin. The primary carbohydrate present was glucans followed by xylan. Soluble and storage sugar concentrations were significant and declined as the plants matured. The theoretical ethanol yields assuming 100% conversion of neutral carbohydrates were 270-380 l/tonne, which compares favorably with corn stover (385 l/tonne) or even corn kernels (420 l/tonne, starch only). The actual conversion efficiencies were measured by pretreating the samples with dilute acid at 150 deg C for 20 min followed by digesting the whole hydrolysates with commercial cellulases (50 FPU/g glucan) for 72 hr. Glucose yields were 60-90% and were lower for the alfalfa stems compared to the monocots and also declined with harvest maturity. Nonglucose sugar yields did not vary with maturity but did decline with fructose concentration, which was more liable to the dilute acid pretreatment than the other sugars present.