Preface to Volume Two of the Second Edition of Bergey's Manual of Systematic Bacteriology -- Preface to the First Edition of Bergey's Manual of Systematic Bacteriology -- Preface to the First Edition of Bergey's Manual of Determinative Bacteriology -- Contributors -- Betaproteobacteria -Burkholderiaceae -- Oxalobacteraceae -- Alcaligenaceae -- Comamonadaceae -- Genera incertae sedis -- Hydrogenophilales -- Methylophilales -- Neisseriales -- Genera incertae sedis -- Nitrosomonadales -- Spirillaceae -- Gallionellaceae -- Rhodocyclales -- Class IV. Deltaproteobacteria -- Desulfovibrionales -- Desulfomicrobiaceae -- Desulfobacterales -- Desulfarcales -- Desulfuromonales -- Peolobacter -- Syntrophobacterales -- Syntrophaceae -- Bdellovibrionales -- Myxococcales -- Sorangineae -- Nannocystineae -- Class V.: Epsilonproteobacteria -- Campylobacterales -- Helicobacteraceae -- Index. Includes a description of the Alpha-, Beta-, Delta-, and Epsilonproteabacteria (1256 pages, 512 figures, and 371 tables). This large taxa include many well known medically and environmentally important groups. Especially notable are Acetobacter, Agrobacterium, Aquospirillum, Brucella, Burkholderia, Caulobacter, Desulfovibrio, Gluconobacter, Hyphomicrobium, Leptothrix, Myxococcus, Neisseria, Paracoccus, Propionibacter, Rhizobium, Rickettsia, Sphingomonas, Thiobacillus, Xanthobacter and 268 additional genera.