Pyrodictium

Pyrodictium is a genus in the family Pyrodictiaceae. It is a genus of submarine hyperthermophilic Archaea whose optimal growth temperature range is 80 to 105 °C. They have a unique cell structure involving a network of cannulae and flat, disk-shaped cells. Pyrodictium are found in the porous walls of deep-sea vents where the temperatures inside get as high as 400 °C, while the outside marine environment is typically 3 °C. Pyrodictium is apparently able to adapt morphologically to this type of hot–cold habitat.

Pyrodictium
Scientific classification
Domain:	Archaea
Phylum:	Thermoproteota
Class:	Thermoprotei
Order:	Desulfurococcales
Family:	Pyrodictiaceae
Genus:	Pyrodictium Stetter, König & Stackebrandt 1984
Type species
Pyrodictium occultum Stetter, König & Stackebrandt 1984
Species
P. abyssi P. brockii P. delaneyi P. occultum

Genome structure

Much research has been done on the genetics of Pyrodictium in order to understand its ability to survive and even thrive in such extreme temperatures. The thermal stability of Pyrodictum occultum's isolate tRNA has been analyzed, indicating that modifications in the nucleosides allow the organism to withstand temperatures well over 100 °C.

Cell structure and metabolism

Pyrodictium cells have been studied by scientists in part because they are a model of thermal stability. The cells' structure is a flat, irregular disk, 300 to 2500 nanometres in diameter and up to 300 nanometres in width. The cells grow in unique flake-like shapes held together by a network of hollow cannulae (tubules). The cannulae branch out and connect with other cells, greatly extending their range. While the exact reason for this morphology is unknown, it is likely that the range of motion provided by the cannulae allow the cells to move freely when by the thermal energy from the extreme heat of the organisms's environment. The large size range of the cells may allow Pyrodictium to inhabit a variety of pores in the deep-sea vent walls.

Ecology

Members of Pyrodictium are located in deep-sea hydrothermal vents, first discovered in 1979. Their ecological significance remains a mystery because of the difficulty in collecting samples which may yield data on the abundance and diversity of these extremophile.

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)

16S rRNA based LTP_06_2022	53 marker proteins based GTDB 08-RS214
Pyrolobus fumarii Blöchl et al. 1999 Pyrodictium brockii Stetter et al. 1984 Hyperthermus butylicus Zillig et al. 1991 Pyrodictium P. occultum Stetter et al. 1984 P. abyssi Pley and Stetter 1991 P. delaneyi Lin et al. 2016	Pyrolobus fumarii Hyperthermus butylicus Pyrodictium P. delaneyi P. occultum

See also

• List of Archaea genera

Further reading

Scientific journals

• Goodsell DS, Haas D (July 2014). "Visualising microorganisms from molecules to cells". FEMS Microbiology Letters. 356 (1): 1–7. doi:10.1111/1574-6968.12485. PMID 25039917.
• Burggraf S, Huber H, Stetter KO (July 1997). "Reclassification of the crenarchael orders and families in accordance with 16S rRNA sequence data". International Journal of Systematic Bacteriology. 47 (3): 657–60. doi:10.1099/00207713-47-3-657. PMID 9226896.
• Stetter KO, König H, Stackebrandt E (1983). "Pyrodictium gen. nov., a New Genus of Submarine Disc-Shaped Sulphur Reducing Archaebacteria Growing Optimally at 105°C". Systematic and Applied Microbiology. 4 (4): 535–51. doi:10.1016/s0723-2020(83)80011-3. PMID 23194811.