Expansion of the geographic distribution of a novel lineage of epsilon-Proteobacteria to a hydrothermal vent site on the Southern East Pacific Rise

The diversity associated with a microbial mat sample collected from a deep- sea hydrothermal vent on the Southern East Pacific Rise was determined usin g a molecular phylogenetic approach based on the comparison of sequences fr om the small subunit ribosomal RNA gene (16S rDNA). The DNA was extracted f rom the sample and the 16S rDNA was amplified by PCR. Sixteen different phy lotypes were identified by restriction fragment length polymorphism analysi s; four phylotypes were later identified as putative chimeras. Analysis of the 16S rDNA sequences placed all the phylotypes within the Proteobacteria. The majority of the sequences (98%) were most closely related to a new cla de of epsilon -Proteobacteria that were initially identified from an in sit u growth chamber deployed on a deep-sea hydrothermal vent on the Mid-Atlant ic Ridge in 1995. The similarity between phylotypes identified from Atlanti c and Pacific deep-sea hydrothermal vent sites indicates that this new clad e of Proteobacteria may be endemic to and widely distributed among deep-sea hydrothermal vents. (C) 2001 Federation of European Microbiological Societ ies. Published by Elsevier Science B.V. All rights reserved.