Research Institution Subcontractor: The Ohio State University Technical This SBIR project is to develop a novel bioprocess to produce chemicals and fuels from low-cost agricultural residues such as corn stalk economically and sustainably with no CO2 emission. Weaim to produce n-butanol an industrial solvent and advanced biofuel from agricultural residues and fermentation waste gases (CO and H ) in an integrated bioprocess using engineered2 2 clostridia in a "Linear Immobilized Bioreactor" (LIBR) with in-situ gas stripping for butanolrecovery. Biofuel production has been limited by low product yield productivity and titer;whereas biorefinery using lignocellulosic feedstocks suffers from high capital and operationalcosts associated with pretreatments and cellulose hydrolysis which also generate inhibitorsnegatively affecting fermentation performance. We have engineered a clostridia strain as asuperior cell factory that not only can produce n-butanol from both glucose and xylosesimultaneously with high yield and productivity but also has a high tolerance to hydrolysateinhibitors and can use biomass hydrolysates directly without detoxification. This novel cellfactory is robust for butanol production but has not been used in industrial fermentation. Inaddition a novel mixotrophic fermentation with acetogen to reassimilate formate derived fromCO2 released from sugars will also be developed to further increase butanol production. Phase Istudies will assess the feasibility of the proposed bioprocess involving two key fermentationsteps: 1) mixotrophic fermentation for converting glucose and formate to acetate with the co- cultures of a homolactic acid bacterium and acetogen and 2) butanol production from glucosexylose and acetate by engineered clostridia immobilized in LIBR with in-situ gas stripping. Fermentation kinetics and process performance data (titer rate and yield) will be collected andused in techno-economic analysis (TEA) of the integrated bioprocess which will also include biomass pretreatment/hydrolysis and pervaporation for final product purification. The proposed fermentation can achieve a 50% increase in butanol yield >10% (w/v) product titer for energy efficient purification and substantial cost reduction to less than $2.5/gal competitive for applications as industrial solvent and advanced biofuel. Anticipated results and
Potential Commercial Applications: Biobutanol is an advanced liquid fuel with an enormous potential to compete with ethanol if its production cost can be reduced to less than $2.5/gal by using low-cost renewable agricultural residues such as corn stalk. The proposed process can produce n-butanol at a high yield of ~0.5g/g from lignocellulose sugars (glucose and xylose). The proposed technology thus can providean economically competitive and superior biofuel to replace ethanol for blending in gasoline. This advanced biobutanol process can be readily adopted by the biofuels industry by retrofitting or adding onto existing bioethanol and/or corn-based acetone-butanol-ethanol (ABE)fermentation plants. It will thus enhance the economic viability of the rural area where substantial amounts of lignocellulosic wastes are generated and reduce the burden from waste biomass disposal. Successfully developing the proposed biobutanol fermentation technology will also satisfy the public interests especially in providing a safe renewable energy protecting natural resources and the environment and enhancing energy security economic opportunity and quality of life.
