Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2014
Publication Date: 10/18/2014
Publication URL: http://handle.nal.usda.gov/10113/60448
Citation: Saha, B.C., Nichols, N.N., Qureshi, N., Kennedy, G.J., Iten, L.B., Cotta, M.A. 2015. Pilot scale conversion of wheat straw to ethanol via simultaneous saccharification and fermentation. Bioresource Technology. 175:17-22.
Interpretive Summary: Wheat straw can potentially be used for production of fuel ethanol. Generally, three steps are involved for its conversion to ethanol: pretreatment, enzymatic hydrolysis and fermentation. Pretreatment is crucial because wheat straw in its native state is resistant to enzymatic hydrolysis. In this research, we demonstrated the conversion of wheat straw to fuel ethanol at 100 L scale combining enzymatic hydrolysis and fermentation into a single step. The integrated process offers advantage for process simplication and total time required for conversion of wheat straw to ethanol. This research is important for development of an integrated commercially viable biomass to fuel ethanol conversion process technology.
Technical Abstract: The production of ethanol from wheat straw (WS) by dilute acid pretreatment, bioabatement of fermentation inhibitors by a fungal strain, and simultaneous saccharification and fermentation (SSF) of the bio-abated WS to ethanol using a mixed sugar utilizing ethanologenic recombinant bacterium was scaled up to 100 L. WS (124.2 g/L, dry basis) was pretreated with dilute H2SO4 (0.75%, v/v) in two parallel tube reactors (working volume, 10 L) for 20 min holding time. The inhibitors formed during pretreatment were bio-abated by growing the fungus Coniochaeta ligniaria NRRL 30616 aerobically at 30 oC and pH 6.5. The maximum ethanol produced by SSF of the bio-abated WS by the recombinant Escherichia coli FBR5 at pH 6.0 and 35 oC was 36.0 g/L in 83 h with a productivity of 0.43 g L-1 h-1 using a cocktail of cellulase and ß-glucosidase preparations. This value corresponds to an ethanol yield of 0.29 g/g of WS which is 86% of the theoretical ethanol yield from WS. This is the first report on the production of ethanol by the recombinant bacterium from a lignocellulosic biomass at 100 L scale.