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

Culture-independent molecular phylogenetic methods were used to explore the breadth of diversity and environmental distribution of members of the divi sion-level "candidate" phylogenetic group WS6, recently discovered in a con taminated aquifer and with no cultivated representatives. A broad diversity of WS6-affiliated sequences were cloned from 7 of 12 environments investig ated: 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 e vidently important kinds of organisms and tools, the sequences, with which to do so.