I. The Phylogeny of Bacteria • 17.1 Phylogenetic Overview of Bacteria II. Phototrophic, Chemolithotrophic, and Methanotrophic Proteobacteria • 17.2 Purple Phototrophic Bacteria • 17.3 The Nitrifying Bacteria • 17.4 Sulfur- and Iron-Oxidizing Bacteria • 17.5 Hydrogen-Oxidizing Bacteria • 17.6 Methanotrophs and Methylotrophs III. Aerobic and Facultatively Aerobic Chemoorganotrophic Proteobacteria • 17.7 Pseudomonas and the Pseudomonads • 17.8 Acetic Acid Bacteria • 17.9 Free-Living Aerobic Nitrogen-Fixing Bacteria • 17.10 Neisseria, Chromobacterium, and Relatives • 17.11 Enteric Bacteria • 17.12 Vibrio, Aliivibrio, and Photobacterium • 17.13 Rickettsias V. Delta- and Epsilonproteobacteria • 17.17 Myxobacteria • 17.18 Sulfate- and Sulfur-Reducing Proteobacteria • 17.19 The Epsilonproteobacteria