Proteobacteria

The Proteobacteria kingdom is the largest and most diverse in the domain Bacteria. As a group, these organisms show extreme metabolic diversity and represent the majority of known gram-negative bacteria of medical, industrial, and agricultural significance. This is an evolutionarily, geologically, and environmentally important group.  May have gas vesicles, flagella, or can move by gliding; they may have stalks, or other appendages. Some species are able to carry out photosynthesis, others deposit sulphur within the cells or outside. The subgroups are defined on the basis of rRNA sequences.