Diversity of deep-sea hydrothermal vent Archaea from Loihi seamount, Hawaii

Through an examination of SSU rDNA (genes coding for SSU rRNA), the molecular phylogeny of the domain Archaea (e.g. one of the three major lineages of life) was analyzed from a microbial mat at an active, deep-sea hydrothermal vent ecosystem located at Pele's Vents on the summit of Loihi Seamount, Hawaii. These SSU rDNAs were amplified from extracted microbial mat genomic DNA by PCR, cloned into a plasmid vector, and sequenced. The derived archaeal sequences were then used to infer the evolutionary relationships between these microbial mat community members and their closest known relatives. Of the four clones initially chosen for sequence analysis, a cluster of three phylogenetically similar PVA (Pele's Vents Archaea) clones all contained in the archaeal group I lineage of the marine Crenarchaeota were detected. A single PVA clone was contained in the archaeal group II lineage of the marine Euryarchaeota. All four of the PVA clones are novel and constitute the discovery of new archaeal taxa, From further rarefaction results of 75 archaeal SSU rDNA clones, we estimate the organismal diversity of this domain from the microbial mats located at Pele's Vents to be significantly greater than that of the bacterial domain from this same ecosystem, Analyses of archaeal diversity at both the organismal (i.e, rarefaction) and phylogenetic level suggest that hydrothermal vents, such as Pele's Vents, are intimately linked with marine archaeoplankton (a recently discovered component of marine picoplankton) detected from oceans around the world. (C) 1998 Elsevier Science Ltd. All rights reserved.