Lars Reier Bakken
Norwegian University of Life Sciences
LB used to be a “jack of all trades” in soil biology, but since 2004 his research has narrowed down to nitrogen transformations in general, and anoxic respiration in particular. LB formed the NMBU Nitrogen Group
together with Åsa Frostegård and Peter Dörsch. The research of NMBUNG spans from field experiments and process studies to pure culture investigations of the physiology and regulatory biology of nitrifying and denitrifying prokaryotes.
Link to personal webpage.
Keynote: Denitrification – ecophysiology ruminations
The current escalation of the nitrogen cycle (fertilization and combustion) cause accumulation of N2O in the atmosphere, primarily through denitrification. To mitigate N2O emissions, we must improve our understanding of the mechanisms that control the N2O emissions at different scales: enzyme-, cellular-, community- and systems-level. Thus, progress in combatting N2O emission from denitrification demands trans-disciplinary communication and collaboration, which is the explicit aim of this very timely conference. The point of departure for my introductory talk will be the “physiology of denitrification”, as studied at the enzyme and cellular level. I will summarize some recent progress in understanding the regulatory networks of the denitrification genes, and the role of denitrification in sustaining respiratory metabolism, both in heterotrophic and autotrophic prokaryotes.
I will speculate about the reasons for the ubiquity of truncated denitrifiers, i.e. organisms that conduct only one or two steps the entire pathway from nitrite to N2, and extend this to a speculative discussion about the selective advantage of reducing N2O to N2, hopefully inspiring someone to invent new integrative approaches to shed light on this crucial question.
Finally, I will discuss the prospects for progress through studies of the biochemistry and regulatory biology of model organism versus process studies in complex systems. The study of model organisms provides essential “scaffolds” for understanding complex systems, and useful hypotheses that can be tested in whole-system experiments. And vice versa: explorative whole-system investigations, harnessed with advanced isotope methods to trace specific transformations, may unravel novel phenomena, that should be tested and understood by investigating model organisms.