Regulation of Diurnal Physiology through Integration of Circadian and Environmental Signals

被称为蓝藻的产氧光合细菌具有许多特性，使它们成为生产绿色燃料和化学品的极佳候选者。它们需要很少的营养投入，可以在饮用或养殖质量较差的水中生长，并且可以很容易地通过基因工程进行操作。蓝藻细长聚球藻PCC7942已经成功地被改造成生产一些有用的化学品，如酒精和油。然而，第一代蓝藻基因工程策略只产生了适度的化学生产率，并且没有考虑到室外细菌在昼夜循环中的生长将如何影响这些生产率。为了更有效地将蓝藻用于工业目的，需要进行基础研究，解决这些细菌如何整合与外部环境条件相关的信息，以及细胞内的计时程序，以决定何时运行其新陈代谢的各个方面。本项目将利用细长聚球藻PCC7942作为模型来解决三个问题：(1)当聚球藻从光照过渡到黑暗时，是否存在特定的信号通路来检测这种变化并改变生物体的基因表达和新陈代谢？(2)聚球藻的内部生物钟是否会影响决定是立即使用碳生长还是储存碳以供以后使用？以及(3)细胞如何整合外部环境信号和内部生物钟信息，从而对新陈代谢施加控制？更好地了解这些信号网络将扩大对蓝藻如何控制其新陈代谢的基本了解，并促进更有效的基因工程努力，考虑到细菌将如何对修饰和外部环境条件做出反应。更广泛的影响：这项研究将回答基本的科学问题，即碳在模型蓝藻系统中何时以及如何被利用和储存；这些信息对于成功设计非光合作用细菌，如大肠杆菌，是必不可少的。在这样做的过程中，该项目将使光合作用微生物工程能够生产燃料和工业化学品，减少对石油产品的依赖。生物燃料领域的成功将通过开发碳中性燃料来提高环境的可持续性，并产生一种新的家庭燃料来源，将加强经济和国土安全。该项目将生成基因工具、菌株和网络地图数据，供生物燃料研究社区使用。此外，这些工具和菌株中的许多将使生物技术公司感兴趣，以便直接商业化。该项目将直接培训两名博士生研究生和一些本科生的系统生物学，这是一个不断增长的领域，需要训练有素的人员。反过来，博士生将利用从该项目中收集的知识和实际数据，作为当地生物能源认证项目EDGE(教育和发展绿色经济工作者)的教学工具。该项目的毕业生积极并成功地为圣地亚哥日益增长的绿色生物技术产业做出了贡献。

Oxygen-producing photosynthetic bacteria, known as cyanobacteria, have many properties that make them excellent candidates for the production of green fuels and chemicals. They require few nutrient inputs, can grow in water that is of poor quality for drinking or farming, and can easily be manipulated through genetic engineering. The cyanobacterium Synechococcus elongatus PCC7942 has already been successfully engineered to produce a number of useful chemicals such as alcohols and oils. However, first generation strategies to genetically engineer cyanobacteria resulted in only modest chemical production rates, and did not consider how these rates would be affected by growing bacteria outdoors in a day/night cycle. More effective engineering of cyanobacteria for industrial purposes requires basic research that addresses how these bacteria integrate information related to conditions in the external environment and timing programs inside their cells to make decisions on when to run various aspects of their metabolism. This project will utilize Synechococcus elongatus PCC7942 as a model to address three questions: (1) When Synechococcus transitions from being in light to darkness, is there a specific signaling pathway that detects this change and alters the organism's gene expression and metabolism? (2) Does the internal circadian clock of Synechococcus influence the decision of whether to use carbon immediately for growth or to store it for later use? and (3) How does the cell integrate external environmental signals and internal circadian clock information to subsequently exert control over metabolism? Better understanding of these signaling networks will both expand basic understanding of how cyanobacteria control their metabolism and facilitate more effective genetic engineering efforts that take into account how the bacteria will respond to modifications and external environmental conditions. Broader Impacts:This research will answer basic scientific questions about when and how carbon is utilized and stored in a model cyanobacterial system; such information has been essential in the successful engineering of non-photosynthetic bacteria such as Escherichia coli. In doing so this project will enable the engineering of photosynthetic microorganisms to produce fuel and industrial chemicals, decreasing dependence on petroleum for these products. Success in the biofuels arena will improve environmental sustainability through the development of carbon neutral fuels, and produce a new domestic fuel source that will strengthen economic and homeland security. This project will generate genetic tools, strains, and network map data that will be made available to the biofuels research community. Further, many of these tools and strains will be of interest to biotechnology companies for direct commercialization. The project will directly train two doctoral graduate students and a number of undergraduate students in systems biology, a growing field with a need for trained personnel. In turn the doctoral students will utilize knowledge and actual data gleaned from this project as a teaching tool in a local bioenergy certificate program known as EDGE (Educating and Developing workers for the Green Economy). Graduates of this program have actively and successfully contributed to the growing green biotechnology industry of San Diego.