Regulation of anoxic respiration in endosymbiotic bacteria, implications for N2O emission - Emilio Bueno Romero - Spain

The project draws on complementary skills and knowlege of the two groups; UMB Nitrogen Group (UMBNG) and Maria Delgado Group (MDG). MDG has established in depth knowlege of the genetic makeup of the regulatory network controlling anoxic respiration in B . japonicum, and has constructed several mutants (in regulatory genes). UMBNG has developed a unique robotized incubation systems that allows indepth studies of regulatory phenotypes of such strains. The system is particularly suited to study gas kineti cs and gene transcription during transition from oxic to anoxic respiration. The project will inaugurate a collaboration between the two groups that holds a potential to break barriers in the understanding of the regulation of denitrification in this ec onomically and ecologically important symbiotic bacterium. The concrete research tasks outlined for the project is to run a series of experiments with wild type and mutants where the organisms are monitored for gene transcription and anoxic respiration ( NO2, NO, N2O and N2-production) during oxygen depletion. A core question here is to assess the organisms' ability to control the accumulation of the toxic intermediates (NO2, NO) and the non toxic but environmentally harmfull intermediate N2O. Such pheno typic traits of mutants are usefull to assess the quantititive effect of the various elements of the complex regulatory network that controls the anoxic respiration in such bacteria. The study of this regulation is implicitly a study of the regulation of NO and N2O-emission to the atmosphere from such biological systems. The range of experiments will be extended to a variety of environmental conditions to test the robustness of the observation under standard conditions. The ultimate aim of these studi es are to provide a basis for systems biology approahces to anoxic respiration in these bacteria, and to provide a knowlege base for reducing the emission of N2O from the globally important soybean pro