Proteobacteria

Abstract The Proteobacteria constitute one of the major lineages (phyla) within the domain of the Bacteria. Although these Gram‐negative bacteria are phylogenetically related, they are physiologically, morphologically and ecologically extremely diverse. They are of great biological importance because they include various pathogens of humans, animals and plants, as well as a number of taxa that play key roles in the carbon, sulfur and nitrogen cycles on our planet.