Photo courtesy of Iain Anderson, JGI

   Thermofilum pendens is a thermophile and moderate acidophile isolated from a solfataric hot spring in Iceland.   Like several other Archaea, it appears to respire with sulfur and utilize peptides as an energy source.   It has an unusual long filamentous structure, with a length of up to 100 mm.   Another unusual feature of T. pendens is its mode of reproduction.   It does not appear to form a septum in the middle of the cell.   Instead "golf club" shaped organisms are found with a spherical enlargement at one end of the cell, and these likely detach to become new cells.   T. pendens is almost always found associated with a related organism, Thermoproteus tenax .   Growth of T. pendens in the absence of T. tenax requires an unknown lipid growth factor from T. tenax to be present.

   The Archaea are divided into two kingdoms, Euryarchaeota and Crenarchaeota.   While twenty-one Archaeal genomes have been sequenced, only four of these are from Crenarchaeota.   The most important characteristic of T. pendens for genome sequencing is that it is the most deeply branching culturable member of the kingdom Crenarchaeota, thus it provides more phylogenetic breadth to the sequencing of this group.   T. pendens belongs to the order Thermoproteales as does Pyrobaculum aerophilum , one of the four Crenarchaeotes whose genome has been sequenced.   The genome of T. pendens will allow the first comparative genomics studies to determine what genes distinguish the Thermoproteales from other Crenarchaeotes.

References:

Zillig, W., Gierl, A., Schreiber, G., Wunderl, S., Janekovic, D., Stetter, K. O., and Klenk, H. P. 1983. The archaebacterium Thermofilum pendens represents a novel genus of the thermophilic, anaerobic sulfur respiring Thermoproteales . Syst. Appl. Microbiol. 4, 79-87.

Kjems, J., Leffers, H., Olesen, T., Ingelore, H., and Garrett, R. A.   1990.   Sequence, organization and transcription of the ribosomal RNA operon and the downstream tRNA and protein genes in the archaebacterium Thermofilum pendens .   Syst. Appl. Microbiol. 13, 117-127.

Kjems, J., Leffers, H., Olesen, T., and Garrett, R. A.   1989.   A unique tRNA intron in the variable loop of the extreme thermophile Thermofilum pendens and its possible evolutionary implications.   J. Biol. Chem. 264, 17834-17837.