Oxygen-Tolerant Nitrogenase

PI: Maren Friesen（密歇根州立大学）主要合作者：A. William Rutherford和Martin Buck（伦敦帝国理工学院）氮通常是植物生长的限制性养分。虽然多种细菌和古细菌已经进化出利用氮酶将大气中的二氮气体固定为生物可利用的氨的能力，但生物固氮在农业中缺乏广泛的适用性。首先，这个过程在能量上是昂贵的。其次，所有经过充分研究的氮酶都受到氧气的抑制，需要特殊的结构才能有效地发挥作用。然而，有一个氧不敏感的氮酶系统的单一报告，从热自养链霉菌细菌中分离出来，发现在德国燃烧木炭火。这种依赖超氧化物的氮酶仅被部分表征，该菌株已不再可用。目前的项目旨在培养原始菌株，并从类似的恶劣环境中寻找可能含有相关氮酶系统的其他菌株。特别是，该项目将针对一氧化碳含量升高的煤层火灾和活火山；按照最初的分离方法，菌株将在富含一氧化碳和二氧化碳的高温环境下培养。一旦确定，这些菌株将被确定其基因组序列并对基因进行注释。还将对分离它们的土壤进行测序，以确定这些恶劣环境中存在的所有可培养和不可培养微生物的总元基因组。然后，该项目将设法确定这些生物体中氮酶系统的生化和生理特性，并试图将耐氧氮酶转移到其他微生物中，以供未来的生物技术应用。该项目有可能极大地改变生物固氮研究，并最终导致植物自身固氮的工程。该项目将通过三名博士后和一名研究生的参与来促进培训。项目成果和信息将在美国（http://variationselectioninheritance.podbean.com/）和英国（http://wwwf.imperial.ac.uk/imedia/itunes_collections/view/special-lectures）通过公开讲座和播客传播。此外，将维持一个项目博客，详细介绍实地收集旅行和研究结果。特征菌株将通过ATCC: http://www.atcc.org/获得。带注释的基因组和元基因组序列可通过NCBI Genbank获取：http://www.ncbi.nlm.nih.gov/genbank/；元基因组数据也将贡献给地球微生物组计划：http://www.earthmicrobiome.org。质量控制的序列读取将存入NCBI序列读取档案：http://www.ncbi.nlm.nih.gov/Traces/sra/，并在存储时公开提供。

PI: Maren Friesen (Michigan State University)Key Collaborators: A. William Rutherford and Martin Buck (Imperial College London)Nitrogen is most often the limiting nutrient to plant growth. While multiple bacteria and archaea have evolved the ability to fix atmospheric dinitrogen gas into biologically available ammonia using the nitrogenase enzyme, biological nitrogen fixation lacks wide applicability in agriculture. First, the process is energetically expensive. Second, all well-studied nitrogenase enzymes are inhibited by oxygen and require special structures to function effectively. However, there is a singular report of an oxygen insensitive nitrogenase system, isolated from a Streptomyces thermoautotrophicus bacterium found above burning charcoal fires in Germany. This superoxide dependent nitrogenase was only partially characterized and the strain is no longer available. The present project seeks to culture the original strain, as well as search for additional strains from similarly harsh environments that may harbor related nitrogenase systems. In particular, the project will target coal-seam fires and active volcanoes that have elevated levels of carbon monoxide; following the original isolation methods, strains will be cultivated under high temperatures with a carbon monoxide and carbon dioxide enriched atmosphere. Once identified, these strains will have their genome sequences determined and genes annotated. The soils from which they are isolated will also be sequenced to determine the aggregate meta-genome of all culturable and non-culturable microbes present in these harsh environments. The project will then seek to determine the biochemical and physiological properties of the nitrogenase systems in these organisms and attempt to transfer the oxygen-tolerant nitrogenase into other microbes for future biotechnology applications. The project has the potential to dramatically alter biological nitrogen fixation research and could ultimately lead to the engineering of plants that fix their own nitrogen. This project will contribute to training through the involvement of three post-docs and one graduate student. Project outcomes and information will be disseminated through public lectures and through podcasts, both in the US (http://variationselectioninheritance.podbean.com/) and the UK (http://wwwf.imperial.ac.uk/imedia/itunes_collections/view/special-lectures). In addition, a project blog will be maintained that will detail field collection trips and research findings. Characterized strains will be available via the ATCC: http://www.atcc.org/. Annotated genome and meta-genome sequences will be available through NCBI Genbank: http://www.ncbi.nlm.nih.gov/genbank/; the meta-genome data will also be contributed to the Earth Microbiome Project: http://www.earthmicrobiome.org. Quality controlled sequence reads will be deposited into the NCBI Sequence Read Archive: http://www.ncbi.nlm.nih.gov/Traces/sra/ and made publically available upon deposition.