Expanding the known diversity and environmental distribution of an uncultured phylogenetic division of bacteria

Abstract

Culture-independent molecular phylogenetic methods were used to explore the breadth of diversity and environmental distribution of members of the division-level "candidate" phylogenetic group WS6, recently discovered in a contaminated aquifer and with no cultivated representatives. A broad diversity of WS6-affiliated sequences were cloned from 7 of 12 environments investigated: mainly from anaerobic sediment environments. The number of sequences representing the WS6 candidate division was increased from 3 to 60 in this study. The extent of phylogenetic divergence (sequence difference) in this candidate division was found to be among the largest of any known bacterial division. This indicates that organisms representing the WS6 phylogenetic division offer a broad diversity of undiscovered biochemical and metabolic novelty. These results provide a framework for the further study of these evidently important kinds of organisms and tools, the sequences, with which to do so.

FIG. 1

Evolutionary distance dendrograms of the candidate division WS6 and selected bacterial divisions. Division designations are listed outside the brackets. Branch points supported (bootstrap values of >74%) by rate-corrected maximum likelihood, parsimony, and distance analyses are indicated by solid circles. Branch points without circles were not resolved (bootstrap values of <75%) as specific groups in different analyses, and at the division level, they were collapsed back to the next significant node. The bar represents 10% sequence divergence.