Trophic Conversion of an Obligate Photoautotrophic Organism to Produce Isobutyraldehyde in the Absence of Light

摘要：atsumi Shota提案号：1132442学术价值全球气候变化刺激了减少二氧化碳（CO2）净排放的努力。减少二氧化碳净排放的一种方法是利用光合作用回收二氧化碳作为生产燃料或化学品的原料。在任何可扩展的过程中，在自然光条件下以昼夜循环连续生产生物燃料对于最大限度地提高产量和降低成本至关重要。拟议的研究旨在通过基因改造光合细菌（蓝藻），将二氧化碳和葡萄糖转化为异丁醛，异丁醛可以转化为丁醇，这是一种潜在的液体运输燃料。在光照条件下，蓝藻模型将通过代谢工程从二氧化碳中产生异丁醛。系统生物学方法将用于进一步设计从专性光自养蓝藻到异养蓝藻，以便在黑暗条件下从葡萄糖产生异丁醛。本研究的总体目标是构建一个在无光蓝藻中生产异丁醛的平台，了解专门光自养生物的复杂行为，并通过代谢工程和合成生物学的合理设计来设计其生物系统。本研究计划由三个部分组成：1)葡萄糖转运体和2-酮戊二酸脱氢酶在长聚藻中的异源表达；2)利用进化和基因组方法改善异养生长和生产；3)工程菌株的鉴定。该研究结果有可能阐明光合细菌专性光自养的关键机制。更广泛的影响拟议的教育活动将通过团队和同伴指导的方式培养代谢工程和合成生物学的本科生和研究生。拟议的外展活动将旨在激发K-12学生对生物能源主题的兴趣，利用加州大学戴维斯分校（UCD）现有的项目，包括青少年生物技术挑战（TBC）计划，美国化学学会（ACS）项目SEED夏季研究计划，以及UCD青年学者计划。

ABSTRACTPI: Shota AtsumiProposal Number: 1132442Intellectual MeritGlobal climate change has stimulated efforts towards a reduction of net carbon dioxide (CO2) emissions. One approach to reduce net CO2 emission is to recycle the CO2 as a feedstock for producing fuels or chemicals using photosynthesis. In any scalable process, continuous production of biofuel under natural light conditions with a dinural (light/dark) cycle is critical to maximize production and minimize costs. The proposed research aims to genetically modify photosynthetic bacteria (cyanobacteria) to convert both CO2 and glucose into isobutyraldehyde, which can be converted to butanol, a potential liquid transportation fuel. Under light conditions, model cyanobacteria will be metabolically engineered to produce isobutyraldehyde from CO2. Systems biology approaches will be used to further engineer the cyanbacteria from an obligate photoautotroph into a heterotroph to produce isobutyraldehyde from glucose under dark conditions as well.The overall goals of this proposed research are to construct a platform to produce isobutyraldehyde in a cyanobacterium without light, gain understanding of the complex behavior of obligate photoautotrophs, and engineer their biological systems through rational design enabled by metabolic engineering and synthetic biology. The research plan has three components: 1) Heterologous expression of glucose transporter and 2-ketoglutarate dehydrogenase in the cyanobacterium Synechococcus elongatus; 2) Improvement of heterotrophic growth and production using evolutionary and genomic approaches; and 3) Characterization the engineered strains. The research outcomes have the potential to elucidate the critical mechanisms that cause obligate photoautotrophy in photosynthetic bacteria.Broader ImpactsThe proposed education activities will train undergraduate and graduate students in metabolic engineering and synthetic biology through team and peer mentorship approaches. The proposed outreach activities will be designed to stimulate interest of K-12 students in bioenergy topics using existing programs at University of California at Davis (UCD), including the Teen Biotech Challenge (TBC) program, and American Chemical Society (ACS) project SEED summer research program, and the UCD Young Scholars program.