Regulation of Diurnal Physiology through Integration of Circadian and Environmental Signals

产生氧气的光合细菌，被称为蓝藻，具有许多特性，使它们成为生产绿色燃料和化学品的绝佳候选者。它们需要很少的营养投入，可以在饮用或农业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纵。蓝藻长聚球菌PCC7942已经被成功地改造成能产生许多有用的化学物质，如醇和油。然而，第一代基因工程蓝藻的策略只产生了适度的化学物质生产速率，并且没有考虑这些速率如何受到在白天/夜晚循环的户外生长的细菌的影响。为了工业目的，更有效的蓝藻工程需要基础研究，解决这些细菌如何整合与外部环境条件相关的信息，以及细胞内的定时程序，以决定何时运行新陈代谢的各个方面。本项目将以长聚球菌PCC7942为模型，解决以下三个问题：(1)当聚球菌从光照状态过渡到黑暗状态时，是否存在特定的信号通路检测到这种变化，从而改变生物体的基因表达和代谢？(2)聚珠球菌体内的生物钟是否会影响其决定是立即利用碳进行生长还是将其储存起来以备后用？(3)细胞如何整合外部环境信号和内部生物钟信息，进而对代谢进行控制？更好地了解这些信号网络将扩大对蓝藻如何控制其代谢的基本理解，并促进更有效的基因工程努力，考虑到细菌将如何对修改和外部环境条件作出反应。更广泛的影响：这项研究将回答关于碳何时以及如何利用和储存在蓝藻系统模型的基本科学问题；这些信息对于成功改造非光合细菌（如大肠杆菌）至关重要。在这样做的过程中，这个项目将使光合微生物的工程生产燃料和工业化学品，减少对石油的依赖。生物燃料领域的成功将通过开发碳中性燃料提高环境的可持续性，并生产一种新的国内燃料来源，从而加强经济和国土安全。该项目将生成遗传工具、菌株和网络地图数据，这些数据将提供给生物燃料研究界。此外，生物技术公司将对这些工具和菌株中的许多感兴趣，以便进行直接商业化。该项目将直接培养系统生物学领域的两名博士研究生和一些本科生，这是一个不断发展的领域，需要训练有素的人才。反过来，博士生将利用从该项目中收集到的知识和实际数据，作为当地生物能源证书项目EDGE（绿色经济教育和发展工人）的教学工具。该项目的毕业生积极并成功地为圣地亚哥不断发展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.