''Caldicellulosiruptor bescii'' is a species of

thermophilic A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bact ...

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

. It was isolated from a geothermally heated freshwater pool in the Valley of Geysers on the

Kamchatka Peninsula The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

in 1990. The species was originally named ''Anaerocellum thermophilum'', but reclassified in 2010, based on genomic data.

Biofuel production

C. bescii is commonly used to generate microbiofuel. Although growth at temperatures up to 85 degrees Celsius have been noted, the optimum growth temperature is 75 degrees Celsius. ''C. bescii'' was originally grouped in the ''Anaerocellum thermophilum'' because of growth physiology, cell wall type and morphology. 16S rRNA sequencing later showed distinguishable differences that are responsible for placement in the ''Caldicellulosiruptor'' clade. ''C. besci'' is a Gram-positive, rod-shaped bacterium notable for its ability use a variety of polymeric carbohydrates and di- and monosaccharides to produce H₂, acetate, lactate, and trace amounts of ethanol. ''C. bescii'' has been selected for study by

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a federally funded research and development centers, federally funded research and development center in Oak Ridge, Tennessee, United States. Founded in 1943, the laboratory is sponsored by the United Sta ...

and the

University of Georgia The University of Georgia (UGA or Georgia) is a Public university, public Land-grant university, land-grant research university with its main campus in Athens, Georgia, United States. Chartered in 1785, it is the oldest public university in th ...

's Department of Genetics for its ability to degrade

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

. Through plasmid recombination the region for the gene encoding production of lactate dehydrogenase has been deleted causing the microbe to produce elevated levels of acetate and H2. Bi-functional acetaldehyde/alcohol dehydrogenase genes from ''Clostridium thermocellum'' allow for the conversion of sugars to ethanol. This genetically modified strain is able to convert biomass composed of switch-grass to ethanol.

Diversity

''C. bescii'' has the highest growth temperature out of nine different isolates in the genus of ''

Caldicellulosiruptor ''Caldicellulosiruptor'' is a genus of thermophilic, anaerobic, Gram-positive, non-spore forming bacteria. Originally placed within the highly polyphyletic class Clostridia, order Thermoanaerobacterales and family Thermoanaerobacterales Family ...

''. It can grow at temperatures up to 90°C with an optimum growth temperature of 75°C. In 1990, ''C. bescii'' was described formally and the type strain was deposited as DSM 6725. Shortly after, ''C. bescii'' was classified as a member of a new genus ''Anaerocellum'' and named ''Anaerocellum thermophilum'', strain Z-1320. Studies were conducted to compare and contrast the strains. A study on the DSM 6725 strain with hemicellulose, cellulose and pectin showed notable differences compared to what was reported with strain Z-1320. The tests showed that DSM 6725 was able to grow on pectin and xylose, while it was previously shown that strain Z-1320 could not utilize xylose and pectin. Another notable difference was in the growth temperature of DSM 6725. DSM 6725 strain could grow up to 90°C while Z-1320 can grow up to 83°C. These differences in the strains lead to the grouping of C. bescii.

References

External links

Type strain of ''Caldicellulosiruptor bescii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q5019084 Thermoanaerobacterales Bacteria described in 2010 Thermophiles Anaerobes