The UMB Nitrogen Group started as a microbial ecology group focusing on the regulatory biology and ecology of denitrifying prokaryotes and related functional groups. This is still the scientific core of the group, but new activities include studies of the N cycle at larger scales; field experiments and watersheds.
Our environmental rationale is that we need to improve our understanding of the biological and ecological control of the emissions of NO and N2O from biosphere to atmosphere. The ultimate scientific goal is to “bridge” from genotype to phenotype, both for single strains and microbial assemblages (communities). We are convinced that this will provide a more rational basis for formulation of biogeochemical models.
Denitrification Regulatory Phenotype We study the phenotypes of denitrifying prokaryotes with special emphasis on their translatoric and post translatoric regulation of the various enzymes involved in nitrogen redox reactions. These studies include paradigm strains (such as Paracoccus denitrificans) and suitable mutants, as well as prokaryotes isolated from environmental samples.
Genotype-phenotype / phylogeny-function The relationship between phylogeny and phenotypic traits within functional groups of prokaryotes is studied, primarily for denitrifying and nitrogen fixing organisms. We hypothesize the existence of some congruence between phylogeny and phenoypic traits, but preliminary results for denitrifying bacteria suggest that the oposite is the case for certain traits
Communities We also work along the same lines with microbial assemblages (communities) from environmental samples, identifying their patterns of response to environmental parameters (i.e. community phenotyping) as well as their genetic makeup (genotyping).
Intact soils and ecosystems
Contrasts We have found that denitrifying bacteria are profoundly different in their ability to perform a balanced transition from oxic to anoxic conditions, their emission of toxic intermediates (NO2- and NO), as well as their emission of the greenhouse gas N2O. Robotized incubation systems have allowed us to explore these characteristic response patterns with high resolution and with high throughput. We have found similar contrasts between microbial assemblages (communities) from soils.
