Thermomicrobium roseum DSM 5159

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   1 Classification
   2 Description and significance
   3 Genome structure
   4 Cell structure, metabolism & life cycle
   5 Ecology (including pathogenesis)
   6 Interesting feature
   7 References


Bacteria; Chloroflexi; Thermomicrobia (class); Thermomicrobiales; Thermomicrobiaceae; Thermomicrobium; Thermomicrobium roseum (3)

Description and significance

T. roseum is not a known human pathogen (1, 6). It was isolated from an alkaline siliceous hot spring, called Toadstool Spring, in Yellowstone National Park and has not been truly isolated from any other environment since (6). It is not a very well-dispersed organism and while the genome is known, the life cycle is still being studied (2). Because it is a relatively newly sequenced genome and has been found in only one true spot, there is still a lot to learn about this organism and many things are still being researched (5,6). For example, it remains unclear what its affect on the environment may be at this time because it was found in only one very specific area (6). It is proving useful in helping to understand other organisms on the ever-branching Tree of Life by serving as somewhat of a novel organism (5).

Genome structure

The complete genome is 2.92 Mb with the chromosome being just about 2 Mb and the megaplasmid just under 1 Mb (1, 5). The shape of the cells pleomorphic rods(1, 5). The rod shaped cells are arranged throughout the bacteria in singles or pairs, The genome of T. roseum consists of two circular chromosomes that have high G and C content, 64.3% of the genome(1, 5). T. roseum's entire genome sequence is known for T. roseum (1, 5).

Cell structure, metabolism & life cycle

The cell structure of T. roseum is pleomorphic rod-shaped (1, 5). The cells re non-motile. T. roseum is gram-negative bacteria that is extremely thermophilic with optimal temperatures being 70-75 degrees Celsius (6). It is a neutralophile, but a borderline alkaliphile, with its optimal pH ranging from 8.2-8.5 (4, 6). The bacterium is classified as an aerobic chemoheterotroph (5). Unlike most eubacterium, T. roseum has an unusual cell wall that lacks almost all peptidoglycan but instead is composed of many other proteins including carotenoids that give the cells their redish coloring (6). T. roseum utilizes CO as its major electron source and because it is aerobic, it oxidizes CO aerobically, something unlike any other gram-negative thermophilic bacteria. T. roseum has been sequenced to undergo glycolysis, the oxidative pentose phosphate pathway and the TCA pathway (also know as the Kreb's cycle) (1, 6). Also, it is sequenced that certain pars of the electron transport chain is used to undergo oxidative phosphorylation. The biochemical pathways for nitrogen acquisition remains unclear however it is understood that if nitrate were the source for inorganic nitrogen, then additional glutamate would be needed (6). There are no endospores found in the genome. There is evidence that if CO is present then there is a large increase in the growth of T. roseum and eventual oxidation of the CO to produce CO2 (6). There is also some evidence that T. roseum uses H2 as another source of energy (6). This is a possibility only if there is a Hox gene cluster that encodes for the utilization of hydrogen located in T. roseum (6). Energy from the oxidation of H2 and CO is captured by an electron transport chain and then utilized in the bacterial cells (6).


Thermomicrobium roseum DSM 5159 is theoretically found in very hot environments, however is specifically found in the alkaline hot spring, Toadstool spring, in Yellowstone national park (6). There is evidence that this bacterium has been found in two additional springs but the reports have not been verified yet (6). It is not a pathogenic bacterium (5,6). Because there is still a lot of research being done on this organism and also because it has only truly been found in one hot spring, its effect on symbiosis with the environment is not yet understood (5). The bacterium is not a pathogen(1, 6).

Interesting feature

The bacterium is a known non-motile organism however, the megaplasmid of T. roseum encodes something that seems to be a complete flagellar apparatus (1). There are three gene clusters located on the megaplasmid that encode all of the typical components of a flagella. Despite the lack of motility, there is evidence that one third of the two-component proteins are predicted to be involved in chemotaxis(1, 6). While no flagella has been found on T. roseum it is very likely that it has the potential to somehow gain a flagellum in the future. More research is needed to assess the likelihood of the development of a functional flagella (6).


1. 2. Merkel GJ, Durham Dr, Perry JJ. The atypical cell wall composition of Thermomicrobium roseum. Can J Microbiol. 1980;26(4):556–9. 3. 4. Pond JL, Langworthy TA. Effect of growth temperature on the long-chain diols and fatty acids of Thermomicrobium roseum. J Bacteriol. 1987;169:1328–1330. 5. 6. Wu D., Raymond J., Wu M., Chatterji S., Ren Q., Graham J. E., Bryant D. A., Robb F., Colman A., Tallon L. J., Badger J. H., Madupu R., Ward N. L., Eisen J. A. (2009). Complete genome sequence of the aerobic CO-oxidizing thermophile Thermomicrobium roseum. PLoS ONE 4, e4207. doi: 10.1371/journal.pone.0004207.