Location: Bioenergy Research Unit
Title: Bioconversion of barley straw and corn stover to butanol (a biofuel) in integrated fermentation and simultaneous product recovery bioreactors Authors
Submitted to: Journal of Food and Bioproducts Processing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 5, 2013
Publication Date: N/A
Interpretive Summary: Butanol is an important transportation biofuel and chemical feedstock. It has superior fuel properties when compared to ethanol including higher energy content. It can also be mixed with gasoline in any proportion and can be transported in existing pipelines as it is not corrosive. This novel biofuel can be produced from renewable agricultural products such as corn, agricultural by-products including molasses and whey permeate using microbial cultures. However, to reduce the cost of butanol production, use of economically available raw materials such as agricultural wastes and residues or energy crops are recommended in combination with use of cutting edge conversion technology. In this report we produced butanol from barley straw and corn stover using novel technologies. Barley straw and corn stover were treated to release their component sugars (glucose, xylose, arabinose, galactose, and mannose), fermented, and butanol recovered (product) by a novel product separation technique. Successful production of butanol from these residues by fermentation benefits farmers, the butanol producing industry and the United States public. Development of such a transportation fuel by economically viable process is essential as the gasoline prices are rising steadily.
Technical Abstract: In these studies concentrated sugar solutions of barley straw and corn stover hydrolysates were fermented with simultaneous product recovery and compared with the performance of a control glucose batch fermentation process. The control glucose batch fermentation resulted in the production of 23.25 gL^-1^ ABE from 55.7 gL^-1^ glucose solution resulting in an ABE productivity and yield of 0.33 gL^-1^h^-1^ and 0.42, respectively. The control reactor was started with 62.5 gL^-1^ initial glucose and the culture left 6.8 gL^-1^ unused sugar due to butanol toxicity resulting in incomplete sugar utilization. Barley straw (BS) hydrolysate sugars (90.3 gL^-1^) resulted in the production of 47.20 gL^-1^ ABE with a productivity of 0.60 gL^-1^h^-1^ and a yield of 0.42. Fermentation of corn stover (CS) hydrolysate sugars (93.1 gL^-1^) produced 50.14 gL^-1^ ABE with a yield of 0.43 and a productivity of 0.70 gL^-1^h^-1^. These productivities are 182-212% higher than the control run. The culture was able to use 99.4 to 100% sugars (CS & BS respectively) present in these hydrolysates and improve productivities which were possible due to simultaneous product removal. Use of > 100 gL^-1^ hydrolysate sugars was not considered as it would have been toxic to the culture in the integrated (simultaneous fermentation and recovery) process.