Denitrification Linked to Methanol Oxidation in Methylotenera Mobilis: a New Paradigm of Methylotrophy

甲基软体中反硝化与甲醇氧化相关：甲基营养的新范式

• 批准号: 0950183
• 负责人: Ludmila Chistoserdova
• 金额: $ 53.99万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0950183&HistoricalAwards=false
• 关键词: Denitrification; Linked; Methanol; Oxidation; Methylotenera

Intellectual Merit:Methylotenera mobilis is a recently described bacterium that is a prominent member of the active methylotroph community in Lake Washington sediment. More recent experiments suggested that M. mobilis and related bacteria carry out denitrification linked to methanol oxidation, in the presence of oxygen, resulting in emission of N2O. This is a novel process that may be an important part of the nitrogen cycle in lakes. Genomic analysis of M. mobilis identified few traditional components of the classic denitrification pathway, suggesting involvement of alternative enzymes. The bacterium also lacks a traditional methanol dehydrogenase. This phenomenon is interesting for a number of reasons. First, this is the first case of denitrification by a member of the Methylophilaceae family; second, oxygen-dependent denitrification is unusual in the microbial world; third, denitrification by Methylotenera and related organisms may represent an important biogeochemical process that has been overlooked, accounting for a portion of N2O released into the atmosphere from the environments active in C1 metabolism, such as freshwater lakes. The major goal of this project is to understand the biochemistry and the physiology of denitrification by Methylotenera and to uncover the specific nature of coupling of denitrification to methanol oxidation. This work will present new paradigms of both methylotrophy and denitrification and will provide new insights into the connection between the global cycles of carbon and nitrogen. M. mobilis will be the model system. The specific objectives are 1) identification of genes, enzymes and pathways involved in denitrification and methanol oxidation, 2) testing the functions of the genes predicted to be involved in both methanol oxidation and denitrification, via mutation, and 3) purification and characterization of one or more key enzymes involved in denitrification by M. mobilis, the primary candidate being a novel periplasmic nitrate reductase. The intellectual merit of this proposal is in obtaining biochemical insights into methylotrophy linked to denitrification, transforming the paradigms of both processes and broadening the knowledge on energy-generating pathways in microbes in general. Broader Impacts:This project will involve graduate, undergraduate and high school students, with special emphasis on the members of underrepresented groups. Established partnerships with local schools and colleges will provide the public outreach. The data will be broadly disseminated via educational materials, conference presentations, scientific and popular publications and the dedicated web site. The societal impact will be in providing biochemical and genomic insights into a novel, previously overlooked biogeochemical process that potentially contributes to climate change.

智力上的优点：运动甲藻是一种最近被描述的细菌，它是华盛顿湖沉积物中活跃的甲硫氨酸群落的重要成员。最近的实验表明，运动分枝杆菌和相关细菌在氧气存在的情况下进行与甲醇氧化有关的反硝化作用，导致N2O的排放。这是一个新的过程，可能是湖泊氮循环的重要组成部分。运动分枝杆菌的基因组分析发现，经典的反硝化途径中几乎没有传统的成分，这表明参与了替代酶的参与。该细菌也缺乏传统的甲醇脱氢酶。这种现象之所以有趣，原因有很多。首先，这是甲基嗜热菌科成员的第一例反硝化作用；其次，氧气依赖的反硝化作用在微生物世界中是不常见的；第三，甲基木霉及其相关生物的反硝化作用可能代表了一个被忽视的重要生物地球化学过程，占了从淡水湖泊等活跃的C1代谢环境释放到大气中的N2O的一部分。该项目的主要目标是了解甲基洛格氏菌的反硝化作用的生化和生理学，并揭示反硝化作用与甲醇氧化耦合的具体性质。这项工作将提出甲基营养和反硝化的新范式，并将为全球碳和氮循环之间的联系提供新的见解。M.MOBILIS将成为模型系统。其具体目标是：1)鉴定参与反硝化和甲醇氧化的基因、酶和途径；2)通过突变测试预测参与甲醇氧化和反硝化的基因的功能；3)纯化和鉴定运动分枝杆菌参与反硝化作用的一个或多个关键酶，主要候选基因是一种新的周质硝酸还原酶。这一提议的学术价值在于获得了与反硝化作用有关的甲基营养的生化见解，改变了这两个过程的范式，并拓宽了一般微生物中产生能量的途径的知识。更广泛的影响：该项目将涉及研究生、本科生和高中生，特别强调代表性不足群体的成员。与当地学校和大学建立的合作伙伴关系将提供公众宣传。这些数据将通过教育材料、会议介绍、科学和大众出版物以及专门的网站广泛传播。其社会影响将是对一种以前被忽视的新的生物地球化学过程提供生化和基因组方面的见解，该过程可能会导致气候变化。