Metallosphaera hakonensis

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Metallosphaera hakonensis
Scientific classification
M. hakonensis
Binomial name
Metallosphaera hakonensis
(Takayanagi et al., 1996)
Kurosawa et al., 2003

Sulfolobus hakonensis[1][2]

Metallosphaera hakonensis is a gram-negative, thermoacidophilic archaea discovered in the hot springs of Hakone National Park, Kanagawa, Japan.[1]


Metallosphaera hakonensis was isolated in 1996 by Takayanagi et al. from a hot spring in the Hakone National Park in Kanagawa, Japan.[1] Originally classified as a member of the genus Sulfolobus,[1] Kurosawa et al. determined through genetic testing that the organism belongs to the Metallosphaera genus in 2003.[2] Takayanagi et al. determined a 92% similarity with Sulfolobus species; however, Kurosawa et al. determined a 98% similarity with Metallosphaera species.[1][2] Using the more accurate high-performance liquid chromatography method, Kurosawa et al. also determined a new G+C content (43.29%) that is characteristic of Metallosphaera species.[2]


Takayanagi et al. collected a water sample from a hot spring in the Hakone National Park in Kanagawa, Japan, with a pH 1.5 and a temperature of 91.5 °C.[1] A 1:10 mL dilution of the sample and modified Allen’s medium, a media known to sustain Sulfolobus species, was made and incubated at 70 °C for about one week.[1] This sample was then used to form a 1:9 mL dilution with Allen’s media, and a portion streaked onto 1.0% Geltrite plates containing Allen’s media during exponential growth.[1] After incubation at 70 °C, an isolated colony of M. hakonensis was used to inoculate fresh broth, incubated, and plated.[1] This procedure was performed an additional time to isolate the archaea.[1]

Growth and physiology[edit]

M. hakonensis can grow in temperatures between 50 °C and 80 °C and between pH values 1.0 and 4.0.[1] M. hakonensis's optimal growth conditions are 70 °C and pH 3.0.[1] Some Metallosphaera species, such as M. prunae, are mobile by means of flagella; however, M. hakonensis does not have a flagella.[2] M. hakonensis is gram-negative and has either spherical or irregular polyhedron-shaped cells (lobe-shaped cells), that are 0.9 to 1.1 m in diameter.[1]

Genomics and ecology[edit]

M. hakonensis has genome that is about 2.3 Mbps long and has a G+C content of 43.29% determined through Ion Torrent Sequencing and assembled using the Newbler v. 2.8 software.[3][4] M. hakonensis’s genome contains 3,357 protein coding genes and 57 RNA genes determined using the Joint Genome Institute's gene calling methods and IMG's annotation pipeline[3] Near neighbors include Metallosphaera prunae, M. sedula, and M. yellowstonensis.[2] M. hakonensis has a 98% similarity in the 16S rRNA sequence to the other members of the genus Metallosphaera'.[2]

Genome sequencing of M. hakonensis has revealed the presence of genes coding for enzyme Urease, with genes present for subunits A and B.[3] Urease catalyzes the degradation of urea to ammonia and bicarbonate.[5] Sequences also revealed the presence of genes for haloacetate dehalogenase.[3] Haloacetate dehalogenase catalyzes the conversion of haloacetate to glycolate and the halide ion(e.g. fluoride).[3] M. hakonensis also contains the gene for maleylacetate reductase, a key component in biological degradation of halogenated aromatic organic compounds.[6][3]

Organisms belonging to the genus Metallosphaera are found in extreme environments such as volcanic fields[7] and hot waste material in mines.[8]


M. hakonensis is an obligate aerobic chemolithoautotroph that utilizes sulfur oxidation as its main source of energy.[1] M. hakonensis is capable of utilizing yeast extract (excluding sugars), L-glutamic acid, L-tryptophan, maltose, and sulfur compounds such as elemental sulfur and hydrogen sulfide as energy sources, similar to other Metallosphaera species.[1][2] M. hakonensis exhibits poor growth in media containing L-glutamic acid, L-tryptophan, and maltose.[1] One unique feature of M. hakonensis is its ability to utilize FeS clusters and the sulfur anion, tetrathionate (O6S42-).[2]


M. hakonensis is an extremophile, exhibiting characteristics of both thermophiles and acidophiles.[1] The advancement in the research of M. hakonensis is important because extremophiles are widely thought to be more closely related to the "universal ancestor" on the tree of life than most organisms.[9] Sequencing data of this organism contributes to the attempt to reconstruct a genome similar to the last universal common ancestor (LUCA).[9] Future research into extremophiles will allow for advancements in the field of evolutionary biology and further insight into the last universal common ancestor (LUCA) and it’s developmental environment.[9] Furthermore, astrobiology also places great importance on the study of extremophiles.[9] It is believed that life began on Earth when the environment was anoxic and had a thin atmosphere with extreme temperatures, similar to Mars.[9] Due to the vastness of the universe and millions of planetary systems, it is plausible to believe that life exists outside of Earth. With many planets displaying extreme surface environments, the study of extremophiles (including M. hakonensis) allows scientists to develop hypotheses about environmental conditions required for the development of life, as well as the role of this new life on the evolution of other planets.[10]

Based on sequencing data, M. hakonensis contains the gene for maleylacetate reductase, a key component in biological degradation of halogenated aromatic organic compounds.[3][6] Based on recent studies, halogenated aromatic compounds have become a pollutant of food products.[11] Other benzene derivatives have been known to pollute many environments including the air; these compounds are known as BTEX pollutants.[12] The study of the gene for and enzyme maleylacetate reductase can play a role in control of future pollution by aromatic organic compounds. Sequencing data of M. hakonensis also revealed the presence of the gene for Urease, a common virulence factor found in gastro-pathogenic bacteria such as Helicobacter pylori, a common infection causing about 14,500 deaths per year.[13][3] Urease catalyzes the degradation of urea to ammonia and bicarbonate, increasing the pH of the stomach, which allows for survival and manifestation of the pathogens.[14] Recent studies have revealed that Urease also plays a role in fungal virulence, found in organisms such as C. neoformans and Co. posadasii.[14] Urease causes a shift in immune response from a Type 1 (Th1 cells) immune response to a Type 2 (Th2 cells) immune response, reducing the ability of the host immune response to prevent infection.[14] The knockout of Urease has also proven to decrease virulence capabilities of the fungi.[14] With its wide role in both fungal and bacterial infections, Urease has become an emerging target for current pharmaceutical advancements.[15]


  1. ^ a b c d e f g h i j k l m n o p q TAKAYANAGI, SHINNOSUKE; KAWASAKI, HIROKO; SUGIMORI, KENJI; YAMADA, TAKESHI; SUGAI, AKIHIKO; ITO, TOSHIHIRO; YAMASATO, KAZUHIDE; SHIODA, MASAKI (1996). "Sulfolobus hakonensis sp. nov., a Novel Species of Acidothermophilic Archaeon". International Journal of Systematic and Evolutionary Microbiology. 46 (2): 377–382. doi:10.1099/00207713-46-2-377. PMID 8934897.
  2. ^ a b c d e f g h i Kurosawa, Norio; Itoh, Yuko H.; Itoh, Takashi (2003). "Reclassification of Sulfolobus hakonensis Takayanagi et al. 1996 as Metallosphaera hakonensis comb. nov. based on phylogenetic evidence and DNA G+C content". International Journal of Systematic and Evolutionary Microbiology. 53 (5): 1607–1608. doi:10.1099/ijs.0.02716-0. PMID 13130056.
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  4. ^ "Metallosphaera hakonensis JCM 8857, whole genome shotgun sequencing pr - Nucleotide - NCBI". October 2015. Retrieved 2018-05-01.
  5. ^ Konieczna, Iwona; Żarnowiec, Paulina; Kwinkowski, Marek; Kolesińska, Beata; Frączyk, Justyna; Kamiński, Zbigniew; Kaca, Wiesław (2012). "Bacterial Urease and its Role in Long-Lasting Human Diseases". Current Protein & Peptide Science. 13 (8): 789–806. doi:10.2174/138920312804871094. PMC 3816311. PMID 23305365.
  6. ^ a b Kaschabek, S. R.; Reineke, W. (1993-10-01). "Degradation of chloroaromatics: purification and characterization of maleylacetate reductase from Pseudomonas sp. strain B13". Journal of Bacteriology. 175 (19): 6075–6081. doi:10.1128/jb.175.19.6075-6081.1993. ISSN 0021-9193. PMC 206699. PMID 8407778.
  7. ^ Huber, Gertrud; Spinnler, Carola; Gambacorta, Agata; Stetter, Karl O. (July 1989). "Metallosphaera sedula gen, and sp. nov. Represents a New Genus of Aerobic, Metal-Mobilizing, Thermoacidophilic Archaebacteria" (PDF). Systematic and Applied Microbiology. 12 (1): 38–47. doi:10.1016/s0723-2020(89)80038-4. ISSN 0723-2020.
  8. ^ Fuchs, Tanja; Huber, Harald; Teiner, Kristina; Burggraf, Siegfried; Stetter, Karl O. (January 1995). "Metallosphaera prunae, sp. nov., a Novel Metal-mobilizing, Thermoacidophilic Archaeum, Isolated from a Uranium Mine in Germany". Systematic and Applied Microbiology. 18 (4): 560–566. doi:10.1016/s0723-2020(11)80416-9. ISSN 0723-2020.
  9. ^ a b c d e Giulio, Massimo Di (2013-10-01). "The Origin of the Genetic Code: Matter of Metabolism or Physicochemical Determinism?". Journal of Molecular Evolution. 77 (4): 131–133. Bibcode:2013JMolE..77..131D. doi:10.1007/s00239-013-9593-9. ISSN 0022-2844. PMID 24162920.
  10. ^ Rampelotto, Pabulo Henrique (2013-08-07). "Extremophiles and Extreme Environments". Life. 3 (3): 482–485. doi:10.3390/life3030482. PMC 4187170. PMID 25369817.
  11. ^ Cajka, Tomas; Hajslova, Jana (2011). Mass Spectrometry in Food Safety. Methods in Molecular Biology. 747. Humana Press. pp. 373–410. doi:10.1007/978-1-61779-136-9_15. ISBN 9781617791352. PMID 21643916.
  12. ^ "Pollutant Fact Sheet". Retrieved 2018-04-18.
  13. ^ Development, Institute of Medicine (US) Committee to Study Priorities for Vaccine; Stratton, Kathleen R.; Durch, Jane S.; Lawrence, Robert S. (2000). Helicobacter pylori. National Academies Press (US).
  14. ^ a b c d Rutherford, Julian C. (2014-05-15). "The Emerging Role of Urease as a General Microbial Virulence Factor". PLoS Pathogens. 10 (5): e1004062. doi:10.1371/journal.ppat.1004062. PMC 4022740. PMID 24831297.
  15. ^ Kafarski, Paweł; Talma, Michał (2018-01-31). "Recent advances in design of new urease inhibitors: A review". Journal of Advanced Research. 13: 101–112. doi:10.1016/j.jare.2018.01.007. ISSN 2090-1232. PMC 6077125. PMID 30094085.

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