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Pretreatment of Corn Stover by Low Moisture Anhydrous Ammonia (LMAA) in a Pilot-Scale Reactor and Bioconversion to Fuel Ethanol and Industrial Chemicals

Nghiem, Nhuan P., Senske, Gerard E., Kim, Tae Hyun
Applied biochemistry and biotechnology 2016 v.179 no.1 pp. 111-125
Clostridium tyrobutyricum, Escherichia coli, anhydrous ammonia, biotransformation, butyric acid, corn, corn stover, endo-1,4-beta-glucanase, ethanol fermentation, ethanol fuels, hydrolysates, hydrolysis, mash, storage time, succinic acid, sugars, xylanases
Corn stover (CS) adjusted to 50, 66, and 70 % moisture was pretreated by the low moisture anhydrous ammonia (LMAA) process in a pilot-scale ammoniation reactor. After ammoniation, the 70 % moisture CS was treated at 90 and 100 °C whereas the others were treated at 90 °C only. The 70 % moisture pretreated CS then was subjected to a storage study under non-sterile conditions for 3 months. It was found that storage time did not have significant effects on the compositions of the pretreated materials and their hydrolysis by commercial enzymes. The 70 % moisture CS treated at 90 °C was used for preparation of a mix sugar hydrolysate (MSH) using combination of cellulase and xylanase. The MSH was used to prepare a corn mash at 9.5 wt% solid then subjected to ethanol fermentation by Escherichia coli KO11. The 66 % moisture CS treated at 90 °C was hydrolyzed with xylanase to make a xylose-rich hydrolysate (XRH), which was subsequently used for butyric acid fermentation by Clostridium tyrobutyricum. The resultant cellulose-enriched residue was hydrolyzed with cellulase to make a glucose-rich hydrolysate (GRH), which was subsequently used for succinic acid fermentation by E. coli AFP184.