Thermoleophilum album and Thermoleophilum minutum Richelle Moore
The Genus Thermoleophilum is a very unique Genus of eubacteria. Their unique feature is that they grow only on n-alkane chains of length C13 to C20. They cannot utilize any other type of substrate i.e. sugars, amino acids, or fatty acids as a carbon or energy source. They grow best in n-heptadecane. Ammonium chloride is their primary nitrogen source. Other nitrogen sources such as sodium nitrate and glycine can be utilized, but with less success. They are thermophilic, preferring temperatures averaging 60 degrees Celsius. However, they can be found in temperatures ranging from 45 to 70 degrees Celsius. They are strict aerobes, but cannot tolerate high concentrations of oxygen. They favor a neutral pH ranging from 6.5 to 7.5.
There are two species found in the Genus Thermoleophilum. T. album and T. minutum. Thermoleophilum are Gram negative. They have a long generation time exceeding 6 hours. They are very small rods, 1m m. They are nonmotile and do not have pigmentation. Colonies of Thermoleophilum are small, round, white, dry and flat. These organisms grow poorly on agar surfaces.
Thermoleophilum strains are found within a great geographical range. They have been isolated from mud samples in thermal and nonthermal, but generally moist environments. Both species have been found in Yellowstone National Park. They are also found in the hot springs of Arkansas and New Mexico. Nonthermal samples have been found in North Carolina. These samples are found in mud that is constantly exposed to the sun. Thermoleophilum grows sporadically in these nonthermal environments when temperatures rise to a tolerable level.
DNA hybridization studies support the designation of two different species of Thermoleophilum. They are not homologous with other thermophiles such as Thermomicrobium roseum. Analysis of 16S rRNA shows Thermoleophilum should be placed in a separate phylum from other eubacteria. This phylum diverged early in the eubacterial line of descent. The presence of a novel respiratory naphthoquinone distinguishes Thermoleophilum from other Gram-negative, thermophilic, aerobic Phyla. Thermoleophilum is a very unique Genus.
Balows, Albert, ed. et al. The Prokaryotes. 2nd ed. New York: Springer-Verlag, 1992. pp. 3780 – 3784.
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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