The Road Map to the Manual

The Second Edition of Bergey’s Manual of Systematic Bacteriology represents a major departure from the First Edition, as well as from the Eighth and Ninth Editions of the Manual of Determinative Bacteriology , in that the organization of content follows a phylogenetic framework, based on analysis of the nucleotide sequence of the ribosomal small subunit RNA , rather than a phenotypic structure. The principal objective was to devise a classification that reflected the phylogeny of procaryotes based upon 16S rDNA sequence analysis and to place all validly named taxa into the classification at a single point, based on the sequence data derived from the type strain, type species, or type genus. The technique ( 16S rDNA sequencing) is universal in applicability and will soon provide a single type of data that will be available for all validly named species. Given the rapid advancements in sequencing technology, we expect that other gene sequences (e.g., 23S rRNA gene) will follow in the near future and help in placement of “problem taxa”. Therefore, readers must recognize that the current classification is fluid and as each new “road map” is published there will be changes in the placement of some taxa. It is assumed that this current “natural history” approach will provide the basis for a more meaningful and predictive classification of procaryotes in the future.