Regulation, ecophysiology, and kinetic parameters of uncultured N-gas flux associated anaerobic microbial communities in agricultural soils: Towards a microscale spatial resolution

农业土壤中与厌氧微生物群落相关的未培养氮气通量的调节、生态生理学和动力学参数：迈向微尺度空间分辨率

• 批准号: 290269431
• 负责人: Professor Dr. Marcus A. Horn
• 金额: --
• 依托单位: Institut für Mikrobiologie (ifmb)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/290269431?language=en
• 关键词: Regulation; ecophysiology; kinetic; parameters; uncultured

Denitrifiers (reducing N-oxides to N2O and/ or N2), non-denitrifying N2O-reducers (reduce N2O to N2), and dissimilatory nitrate reducers (DNRA; reduce N-oxides to NH4+) impact the emission of the greenhouse gas N2O as well as retention of nitrogen and thus plant nutrition. N2O-reducers and DNRA compete with denitrifiers. Ecophysiological traits determining their competitiveness and N-gas production capabilities and are essentially unknown for uncultured taxa. Thus, the following hypotheses will further be addressed: (i) Denitrification response to environmental factors is shaped by contrasting microbial communities including hitherto unknown species, and can be explained by their intrinsic ecophysiological properties. (ii) Gene expression and community structure associated with denitrification, N2O reduction and DNRA reflect metabolic states and potentials, thus increasing predictability of N2O and N2 fluxes. Outcomes from phase I were summarized in two publications and three submitted manuscripts or manuscripts in preparation (attached). High-throughput incubations under various conditions (including 15N-tracers) combined with functional gene expression, as well as gene and transcript based next generation sequencing will be applied to identify apparent Michaelis-Menten and physiological parameters. Functional genes of denitrifiers (nirK/S encoding nitrite reductases yielding NO; nosZ I and II encoding N2O reductase yielding N2), and DNRA (nrfA encoding nitrite reductases yielding NH4+), will be primarily analyzed. Phase II focuses on the effect of pH, temperature, plant roots and organic carbon on response patterns of target groups. Active root exudate fueled target organisms will be identified by RNA and DNA based stable isotope probing. Regulation of target groups in response to environmental control factors will be analyzed in mesocosms and field studies performed as central experiments. The spatial distribution of target groups will likewise be addressed. Such data will extend the denitrifier-regulatory-phenotype-concept and give insights into the ecophysiology and competition of target groups under various conditions. A molecular microbial community-based proxy for N2O to N2 ratio potentials based on denitrifiers, DNRA, and clade II N2O reducers will be developed. Various kinetic parameters, response function, and microbial community structure data will be provided for modelling of denitrification and N-gas fluxes.

反硝化菌（将N-氧化物还原为N2 O和/或N2）、非硝化N2 O还原剂（将N2 O还原为N2）和异化硝酸盐还原剂（DNRA;将N-氧化物还原为NH 4+）影响温室气体N2 O的排放以及氮的保留，从而影响植物营养。N2 O还原剂和DNRA与硝化剂竞争。生态生理特征决定其竞争力和N-气体生产能力，基本上是未知的未培养的类群。因此，以下假设将进一步解决：（一）反硝化反应的环境因素是由对比微生物群落，包括迄今未知的物种，并可以解释其内在的生理生态特性。(ii)与反硝化、N2 O还原和DNRA相关的基因表达和群落结构反映了代谢状态和潜力，从而增加了N2 O和N2通量的可预测性。第一阶段的成果摘要载于两份出版物和三份已提交的手稿或正在编写的手稿（见附件）。将应用各种条件下的高通量孵育（包括15 N-示踪剂）结合功能基因表达以及基于基因和转录本的下一代测序来鉴定表观Michaelis-Menten和生理参数。将主要分析固氮菌（nirK/S编码产生NO的亚硝酸盐还原酶; nosZ I和II编码产生N2的N2 O还原酶）和DNRA（nrfA编码产生NH 4+的亚硝酸盐还原酶）的功能基因。第二阶段侧重于pH值、温度、植物根系和有机碳对目标群体反应模式的影响。活性根分泌物燃料的目标生物体将通过基于RNA和DNA的稳定同位素探测来鉴定。将在围隔生态系统和作为中心实验进行的实地研究中分析目标群体对环境控制因素的反应。目标群体的空间分布也将得到处理。这样的数据将扩展酶调节表型的概念，并在各种条件下的目标群体的生理生态和竞争的见解。将开发一种基于微生物群落的分子代理，用于N2 O与N2比率潜力，其基于杀菌剂、DNRA和进化枝II N2 O还原剂。将提供各种动力学参数、响应函数和微生物群落结构数据，用于反硝化和氮气体通量的建模。