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)氮通常是限制植物生长的营养物质。虽然多种细菌和古细菌已经进化出使用固氮酶将大气中的氮气固定为生物可用氨的能力，但生物固氮在农业中缺乏广泛的适用性。首先，这一过程耗费大量能源。其次，所有研究得很好的固氮酶都受到氧气的抑制，需要特殊的结构才能有效发挥作用。然而，有一份关于氧不敏感固氮酶系统的独特报告，它是从德国燃烧木炭的火上发现的一种热自养链霉菌中分离出来的。这种依赖于超氧化物的固氮酶只有部分特征，该菌株不再存在。本项目旨在培养原始菌株，并从可能含有相关固氮酶系统的类似恶劣环境中寻找其他菌株。特别是，该项目将针对一氧化碳水平升高的煤层火灾和活火山；按照最初的分离方法，将在高温下利用一氧化碳和二氧化碳丰富的大气培养菌株。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。分离它们的土壤也将被测序，以确定在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，该项目将寻求确定这些生物体中固氮酶系统的生化和生理特性，并试图将耐氧固氮酶转移到其他微生物中，用于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，并最终可能导致植物自身固氮的工程实现。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。项目成果和信息将通过美国(http://variationselectioninheritance.podbean.com/)和英国(http://wwwf.imperial.ac.uk/imedia/itunes_collections/view/special-lectures).的公开讲座和播客传播此外，还将维持一个项目博客，详细介绍实地收集旅行和研究结果。已鉴定的菌株将通过atcc：http://www.atcc.org/.获得。注释的基因组和元基因组序列将通过NCBI Genbank：http://www.ncbi.nlm.nih.gov/genbank/；获得。元基因组数据也将提供给地球微生物组计划：http://www.earthmicrobiome.org.质量控制的序列读数将被存入美国国家生物信息学研究所序列读数档案：http://www.ncbi.nlm.nih.gov/Traces/sra/，并在沉积时向公众提供。

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.