Genomics, physiology, and ecology of microbial nitrogen metabolism

微生物氮代谢的基因组学、生理学和生态学

• 批准号: 371544-2009
• 负责人: Stein, Lisa
• 金额: $ 3.64万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=528260
• 关键词: Genomics; physiology; ecology; microbial; nitrogen

The microbial nitrogen cycle evolved early on Earth to provide usable forms of nitrogen to all of life. However, massive human inputs of nitrogen from agriculture and industry have severely altered the balance of the nitrogen cycle. Rather than returning unassimilated nitrogen to the atmosphere as inert dinitrogen, some N-cycling microorganisms favorably produce and release reactive nitrogen intermediates (RNI) like nitrite, nitrate, nitric oxide and nitrous oxide as a function of increased N-loading. RNI have significant negative effects on the environment including eutrophication of surface water, destruction of stratospheric ozone, and global warming. The proposed research focuses on the microbial production of nitrous oxide, a greenhouse gas that is ca. 300 times more potent than carbon dioxide in global warming potential. In anaerobic metabolism, i.e. denitrification, nitrous oxide is readily consumed to produce dinitrogen as a terminal product. In contrast, the aerobic ammonia-oxidizing bacteria produce and release nitrous oxide as a terminal product when N-loads are high and oxygen concentrations are low. For instance, ammonia-oxidizers are significant global producers of nitrous oxide in agricultural soils and water bodies impacted by agricultural runoff. Interestingly, the genes and pathways for nitrous oxide production by ammonia-oxidizers remain largely uncharacterized, and nearly all of what we know is from work with a single ammonia-oxidizing isolate. Based on our vital need to further understand the workings of, and our continued impact on the microbial nitrogen cycle, objectives of the proposed research are to: 1) broadly identify and characterize microbial genes for RNI production and metabolism, 2) determine the physiological role of RNI metabolism genes in ammonia-oxidizing bacteria, and 3) detect the presence and expression levels of genes from ammonia oxidizers in environmental samples. This multifaceted approach from the bioinformatics, to the organism, to the environmental scales will further our understanding of the microbial nitrogen cycle, pathways for RNI production and metabolism, and sources of nitrous oxide to the atmosphere.

微生物氮循环早在地球上演变，为所有生命提供了可用的氮形式。但是，农业和工业的大量人类投入已严重改变了氮循环的平衡。一些N周期的微生物并没有将毫位的氮返回到大气中，而是有利地产生并释放反应性氮中间体（RNI）（RNI），例如亚硝酸盐，硝酸盐，一氮氧化物和二氮氧化物和二氮氧化物。 RNI对环境有显着的负面影响，包括地表水的富营养化，平流层臭氧的破坏和全球变暖。拟议的研究重点是一氧化二氮的微生物生产，这是一种温室气体。在全球变暖潜力中，二氧化碳的效力比二氧化碳高300倍。在厌氧代谢中，即反硝化，一氧化二氮很容易消耗以产生二氮作为末端产物。相反，当N载很高并且氧气浓度较低时，有氧氨氧化细菌作为末端产物产生并释放一氧化二氮。例如，氨氧化剂是农业土壤和受农业径流影响的水体中一氧化二氮的重要全球生产者。有趣的是，氨氧化剂产生一氧化二氮的基因和途径在很大程度上仍然没有表征，几乎所有我们所知道的都是与单个氨氧化分离株一起工作的。基于我们至关重要的需求，需要进一步理解对微生物氮周期的工作和持续的影响，拟议研究的目标是：1）广泛识别和表征RNI生产和代谢的微生物基因，2）确定RNI代谢基因在氨基化细菌和表达中的生理作用，并确定基因在ammonia-Ommonia-Ommonia-Ommonia-Omiganized Captre和3）中的生理作用。样品。从生物信息学到有机体，再到环境尺度的这种多方面方法将进一步了解我们对微生物氮循环，RNI产生和代谢的途径以及一氧化氮的来源到大气。