STTR Phase I: Engineering Clostritrial Fermentation for Biobutanol Production

STTR 第一阶段：用于生物丁醇生产的梭菌发酵工程

• 批准号: 0810568
• 负责人: I-Ching Tang
• 金额: --
• 依托单位: Bioprocessing Innovative Company, Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810568&HistoricalAwards=false
• 关键词: STTR; Phase; Engineering; Clostritrial; Fermentation

Intellectual Merit:This STTR project will develop novel engineered Clostridia strains for fermentation to economically produce butanol as a biofuel from sugars derived from starchy and lignocellulosic biomass. Butanol is an important industrial solvent and potentially a better transportation fuel than ethanol. Recent rising oil prices and limited petroleum resources have generated high interest in the production of biobutanol by anaerobic Clostridial fermentation. However, the conventional acetone-butanol-ethanol (ABE) fermentation has low butanol yield (20%), butanol concentration (16 g/L) and reactor productivity (0.5 g/L*h) due to a strong butanol inhibition, and the fermentation process is difficult to improve due to the complicated metabolic pathways and gene regulation involved in the production microorganisms, mainly Clostridium acetobutylicum. To develop a novel high-butanol producer, Clostridia mutant strains with inactivated ack (acetate kinase) and pta (phosphotransacetylase) will be cloned with an alcohol dehydrogenase gene in Phase I and the mutants will be further adapted in a fibrous bed bioreactor to attain a high butanol tolerance. Functional genomic studies of the mutants and further metabolic engineering and process development will be carried out in Phase II to evaluate the feasibility and advantages of producing butanol from glucose and xylose. The new fermentation process can double the butanol yield and concentration, thus reducing the product cost to an economically competitive level for fuel application.Broader Impact:Currently, butanol is almost exclusively produced via petrochemical routes. Its uses include industrial applications in solvent, rubber monomers and brake fluids. Butanol has also been shown to be a good alternative transportation fuel. Biobutanol will have a great potential to compete with ethanol as a transportation fuel when its production cost is reduced by using advanced fermentation technologies such as metabolically engineered butanol-tolerant mutants. By increasing the butanol yield from glucose and xylose from the current low of 20 % (w/w) to ~40%, the economics of biobutanol can be greatly improved. With the engineered mutants, the productivity and butanol product concentration can also be improved by at least 100%. Overall, the biobutanol product cost can be reduced to less than $2 per gallon. This technology thus can provide an economical and better biofuel than ethanol. This project will focus on generation of value-added products from industrial waste streams and low-cost biomass feedstocks to enhance the economic viability of the biorefinery industry. Successfully developing the proposed butanol fermentation technology will satisfy the public interest, especially in providing a safe, renewable energy, protecting natural resources and the environment, and enhancing economic opportunity and quality of life. There will be job creation throughout the commercial development and manufacturing phases. At least one postdoctoral scholar and one Ph.D. student will be trained in this project.

智力价值：该项目将开发用于发酵的新型工程梭状芽孢杆菌菌株，以经济的方式从淀粉和木质纤维生物质中提取的糖中生产丁醇作为生物燃料。丁醇是一种重要的工业溶剂，可能是比乙醇更好的运输燃料。最近不断上涨的油价和有限的石油资源引起了人们对厌氧梭菌发酵生产生物丁醇的极大兴趣。然而，传统的丙酮-丁醇-乙醇(ABE)发酵由于丁醇抑制作用较强，丁醇产率(20%)、丁醇浓度(16g/L)和反应器生产率(0.5g/L*h)较低，且生产微生物(主要是乙酰丁酸梭菌)涉及复杂的代谢途径和基因调控，难以改进发酵过程。为了开发一种新型的高丁醇生产菌，我们将在第一阶段克隆失活ACK(醋酸激酶)和PTA(磷酸转乙酰酶)的梭状芽孢杆菌突变株，这些突变株将在纤维床生物反应器中进一步适应，以获得对丁醇的高度耐受性。突变株的功能基因组研究以及进一步的代谢工程和工艺开发将在第二阶段进行，以评估从葡萄糖和木糖生产丁醇的可行性和优势。新的发酵工艺可以将丁醇的产量和浓度提高一倍，从而将产品成本降低到具有经济竞争力的燃料应用水平。广泛影响：目前，丁醇几乎完全通过石化路线生产。它的用途包括在溶剂、橡胶单体和制动液中的工业应用。丁醇也被证明是一种很好的替代交通燃料。当生物丁醇的生产成本通过代谢工程丁醇耐受突变体等先进发酵技术降低时，其作为运输燃料将具有与乙醇竞争的巨大潜力。通过将葡萄糖和木糖的丁醇产率从目前的20%(w/w)提高到~40%，可以极大地提高生物丁醇的经济性。利用工程菌株，生产效率和丁醇产品浓度也可以提高至少100%。总体而言，生物丁醇产品成本可以降至每加仑不到2美元。因此，这项技术可以提供比乙醇更经济、更好的生物燃料。该项目将侧重于从工业废液和低成本生物质原料中产生增值产品，以提高生物炼油业的经济可行性。成功开发丁醇发酵技术将满足公众利益，特别是在提供安全、可再生能源、保护自然资源和环境、提高经济机会和生活质量方面。在整个商业开发和制造阶段都将创造就业机会。至少有一名博士后学者和一名博士生将接受该项目的培训。