Enhancing ethanol production from cellulosic sugars using Scheffersomyces (Pichia) stipitis

Authors: OKONKWO, C - The Ohio State University; AZAM, M - The Ohio State University; EZEJI, T - The Ohio State University; Qureshi, Nasib

Submitted to: Bioprocess and Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2016
Publication Date: 3/10/2016
Citation: Okonkwo, C.C., Azam, M.M., Ezeji, T.C., Qureshi, N. 2016. Enhancing ethanol production from cellulosic sugars using Scheffersomyces (Pichia) stipitis. Bioprocess and Biosystems Engineering. 39(7):1023-1032. doi: 10.1007/s00449-016-1580-2.

Interpretive Summary: Economic production of ethanol, a biofuel, depends on use of cellulosic sugars or cellulosic biomass hydrolyzates, increased ethanol concentration, and improved productivity. In these studies we improved ethanol concentration in the fermentation beer and ethanol productivity by supplementation with ethanol enhancing chemicals (calcium carbonate and calcium chloride). Both ethanol concentration and productivity was improved to 229%. Also for this fermentation a mixture of cellulosic sugars such as glucose and xylose was used. It is estimated that such an improvement in ethanol concentration and productivity would economize ethanol production. This research would benefit US farmers that grow corn, wheat, barley, and energy crops and transportation industry and the United States public.

Technical Abstract: Studies were performed on the effect of CaCO3 and CaCl2 supplementation to fermentation medium for ethanol production from xylose, glucose, or their mixtures using Scheffersomyces (Pichia) stipitis. Both of these chemicals were found to improve maximum ethanol concentration and ethanol productivity. Use of xylose alone resulted in the production of 20.68 ± 0.44 g L-1 ethanol with a productivity of 0.17 ± 0.00 g L-1h-1, while xylose plus 3 g L-1 CaCO3 resulted in the production of 24.68 ± 0.75 g L-1 ethanol with a productivity of 0.21 ± 0.01 g L-1h-1. Use of xylose plus glucose in combination with 3 g L-1 CaCO3 resulted in the production of 47.37 ± 0.55 g L-1 ethanol thus resulting in an ethanol productivity of 0.39 ± 0.00 g L-1h-1. These values are 229% of that achieved in xylose medium. Supplementation of xylose and glucose medium with 0.40 g L-1 CaCl2 resulted in the production of 44.84 ± 0.28 g L-1 ethanol with a productivity of 0.37 ± 0.02 g L-1h-1. These results indicate that supplementation of cellulosic sugars in the fermentation medium with CaCO3 and CaCl2 would improve economics of ethanol production from agricultural residues.