Collaborative Research: Metabolically Engineered Organisms for Conversion of Cellulose to Isobutanol

满足世界迅速增长的能源需求，同时保护地球日益受到威胁的气候和生态平衡，是社会面临的最大挑战之一。该项目将探索一条新的路线，通过构建一个嗜热微生物平台，将纤维素转化为异丁醇，从生物质生产先进的液体燃料。 异丁醇与现有发动机兼容且具有更高的能量密度，作为燃料优于乙醇上级。异丁醇可以取代日益减少和政治上不稳定的石油供应，而不会导致全球变暖，并且与乙醇不同，可以使用现有的技术和基础设施纳入能源经济。针对利用纤维素作为原料的先进生物燃料研究中的基本障碍，目标将是开发嗜热和（部分）纤维素分解的土芽孢杆菌宿主生物体以产生纤维素酶来增强天然纤维素分解活性。这种生物体在纤维素酶高度活性的适度升高的温度下生长并利用通常抑制纤维素酶的纤维素降解的糖产物的能力将提高性能并最小化在发酵过程中添加额外的昂贵酶以产生生物燃料的需要。本项目的具体目标是产生稳定的、有活性的细菌纤维素酶，并在土芽孢杆菌中表达这些新的酶。同时，异丁醇途径将在这种中度嗜热宿主中建立。最终目标是整合和优化纤维素降解和异丁醇生产途径。更广泛的影响：这项研究工作将培养一些最有才华的学生和博士后研究人员在蛋白质和代谢工程，这是在生物技术行业，特别是快速增长的生物燃料/化学品行业非常强劲的需求两项技术在世界上。该项目将支持广泛的本科生研究，同时与众多的外展计划接口。教育计划包括联合研究会议和研究生的共同建议，以及将研究项目的部分内容整合到实验室课程的模块中。该项目提出了一种解决社会最大挑战之一的新方法，即开发可再生的运输燃料和化学品。

Meeting the world's rapidly growing energy needs while protecting Earth's increasingly threatened climate and ecological balance is one of the greatest challenges facing society. This project will explore a new route to producing an advanced liquid fuel from biomass by constructing a thermophilic microbial platform to convert cellulose to isobutanol. Compatible with current engines and with higher energy density, isobutanol is superior to ethanol as a fuel. Isobutanol can replace dwindling and politically unstable petroleum supplies without contributing to global warming and, unlike ethanol, can be incorporated into the energy economy using current technology and infrastructure. To target the fundamental hurdle in advanced biofuel research of utilizing cellulose as the feedstock, the goal will be to develop a thermophilic and (partially) cellulolytic Geobacillus host organism to produce cellulase(s) to augment the native cellulolytic activity. The ability of this organism to grow at the moderately elevated temperatures where cellulases are highly active and to utilize the sugar products of cellulose degradation that normally inhibit the cellulases will enhance performance and minimize the need for additional expensive enzyme addition during fermentation to generate biofuels. Specific objectives of this project will be to generate stable, active bacterial cellulases and express those new enzymes in Geobacillus. Simultaneously, the isobutanol pathway will be established in this moderately thermophilic host. The final goal will be to integrate and optimize cellulose degradation and isobutanol production pathways. Broader impacts: This research effort will train some of the most talented students and postdoctoral researchers in the world in protein and metabolic engineering, two technologies that are in very strong demand in the biotechnology industry, particularly the rapidly-growing biofuels/chemicals industry. This project will support extensive undergraduate research while interfacing with numerous outreach programs. The educational plan includes joint research meetings and co-advising of graduate students as well as the integration of parts of the research project into modules for laboratory courses. This project proposes a novel approach to addressing one of society's greatest challenges, developing a renewable source of transportation fuels and chemicals.