Professor Lars Bakken, Department of Plant and Environmental Sciences, Agricultural University of Norway, will give a talk on denitrifying bacteria with particular focus on gene regulation and phenotypic characterization.
 Lars Bakken Foto: Håkon Sparre |
Place: AUN, Biotechnology building, room BT3A-16
Denitrifying bacteria are excellent model organisms for studies of selective pressure on gene regulation in natural habitats.
- Partly because of functional “transparency”; the role of the denitrifying enzymes is so obvious (survival of nonfermenting organisms under anoxic conditions), the importance of regulation is equally obvious (costs of inefficient regulation are high).
- Partly because everything isn’t so transparent after all: bacteria appear to survive well without NOS, the gene which codes for the N2O reductase, which reduces N2O to N2
- Finally because the genetic makeup and the regulation of the denitrification genes has global implications: if the bacteria of “the day after tomorrow” decided to shut down NOS, UV radiation because of ozone depletion would become intolerable within reasonably short time (3 weeks in Hollywood, 3 millienna in real time). It takes a few sentences to explain why…
Lars Bakken and Åse Frostegård at AUN have worked for a while with the kinetics of reduction of NO3 via NO2, NO and N2O to N2, as determined by the composition of the microbial communities. They have found wide differences, apparently depending on the genetic makeup of the communities. Some are reducing NO3 all the way to N2, some simply stop the process at N2O. The differences are reflected in the genetic makeup of the communities.
The research is now embarking on a comparative study of denitrifying bacteria. Gene regulation and phenotypic characterization (kinetics of the reduction steps) are in focus. The two scientists hypothesize that natural selection on a short time scale works on gene regulation rather than the quality of the functional genes. And that a population’s regulatory system can change in response to stress; provided that the stress cause some mutations here and there…
For more information on Lars Bakken and his work, please see Bakken CV.doc
