报告题目：New Perspectives On A Key Process of the Nitrogen Cycle
主讲嘉宾：Prof. Holger Daims（University of Vienna）
主持人：李 猛 特聘教授
Nitrogen is an essential chemical element for all life on Earth, and the biogeochemical conversions of nitrogen compounds belong to the key processes in all ecosystems. Nitrification, the oxidation of ammonia to nitrite and further to nitrate, is one of these crucial steps of the nitrogen cycle that is catalyzed exclusively by microorganisms. Nitrification is the only biological process that converts nitrogen from its most reduced state (in ammonia) stoichiometrically to its most oxidized state (in nitrate), providing a plethora of plants and microbes with nitrate as a source of nitrogen and as a terminal electron acceptor for respiration. In addition, nitrification plays a pivotal role in wastewater treatment but also causes severe problems in agriculture and contributes to global greenhouse gas emissions.
Since more than a century, research on the microbiology of nitrification has been hampered by difficulties to culture nitrifying microorganisms (nitrifiers) in the laboratory. Nowadays, molecular methods and “omics” approaches enable us to study these organisms in much more detail than ever before. Genomic and post-genomic studies of nitrifiers have led to surprising discoveries, which have dramatically changed our picture of nitrification in nature and engineered systems. Such findings include comammox bacteria, which can perform complete nitrification in a single cell, as well as alternative energy metabolisms and novel microbe-microbe interactions. This talk will give an overview of the recent discoveries, discuss what they mean for our fundamental understanding of the nitrogen cycle, and provide an outlook on some of the remaining mysteries in nitrification research.
Holger Daims is Full Professor at the Centre for Microbiology and Environmental Systems Science at the University of Vienna, Austria. He investigates the genomics, physiology, ecology, and evolution of nitrogen-cycling microorganisms with focus on nitrification and nitrite-oxidizing bacteria. His research group has played a key role in the recent discovery of complete ammonia oxidizers (comammox). In addition, he develops molecular and imaging methods for studying uncultured microorganisms in natural and engineered ecosystems, in situ and at the single-cell level.