Denitrification regulatory phenotype, a new term for the characterization of denitrifying bacteria

Current knowledge of denitrification is based on detailed studies of a limited number of organisms. In most cases the importance of these paradigm species in natural ecosystems is questionable. Detailed phenotypic studies of a wider range of prokaryotes, both type strains and dominant denitrifiers isolated from complex systems, will aid the generation of more sophisticated mathematical models for the prediction of NO and N₂O emission to the environment. However, in order to facilitate the comparison of a vast range of prokaryotes, phenotypic experiments and functional characteristics included should be standardized. In the present paper, we discuss the term DRP (denitrification regulatory phenotype) for describing a set of phenotypic traits and experimental conditions for the characterization of denitrifying organisms. This is exemplified by the contrasting DRP characteristics of the two well-studied denitrifiers Paracoccus denitrificans and Agrobacterium tumefaciens.