Haloarcula

Haloarcula
	SEM image of Haloarcula quadrata.
Scientific classification
Domain:	Archaea
Kingdom:	Methanobacteriati
Phylum:	Methanobacteriota
Class:	Halobacteria
Order:	Halobacteriales
Family:	Haloarculaceae
Genus:	Haloarcula; Torreblanca et al. 1986 emend. Ma et al. 2024
Type species
	Haloarcula vallismortis; (Gonzalez, Gutierrez & Ramirez 1979) Torreblanca et al. 1986
Species
	See text
Synonyms
	Halomicroarcula Echigo et al. 2013;

Haloarcula (common abbreviation Har.) is a genus of extreme halophilic Archaea in the class of Halobacteria.^[2]

Cell structure

Haloarcula species can be distinguished from other genera in the family Halobacteriaceae by the presence of specific derivatives of TGD-2 polar lipids. H. quadrata has predominantly flat, square-shaped, somewhat pleomorphic cells.^[3]

Metabolism

Haloarcula quadrata was first isolated when researchers were attempting to culture Haloquadratum walsbyi, a haloarchaeon that was thought to be unculturable until 2004. Similar to other halophilic archaea, Haloarcula species grow optimally at 40–45 °C. Growth appears in sheets of up to 65 cells often in the shape of a square or triangle.

Taxonomy

The genus of Haloarcula was long grouped with other halophilic archaea such as Halobacterium until genomic analysis prompted to reorder this genus in the new family of Haloarculaceae.

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)^[4] and National Center for Biotechnology Information (NCBI).^[1]

16S rRNA based LTP_07_2026^[5]^[6]^[7]

53 marker proteins based GTDB 11-RS232^[8]^[9]^[10]

Haloarcula

	H. rara

	H. salinisoli

	H. laminariae

	H. sediminis

H. amylovorans

	H.limicola

	H. nitratireducens

H. salina

	H. mannanilytica

	H. terrestris

	H. sebkhae

	H. tradensis

H. salaria

	H. amylolytica

	H. japonica

H. brevis

H. hispanica

H. argentinensis

H. quadrata Oren et al. 1999

	H. marismortui

	H. vallismortis

Haloarcula~1

H. litorea

	H. halophila

	H. pelagica

Halomicroarcula

H. pellucida Echigo et al. 2013

	H. marina Ma et al. 2023

	H. rubra Durán-Viseras, Sánchez-Porro & Ventosa 2022

Haloarcula ordinaria

	Haloarcula halobia

	Haloarcula regularis

H. laminariae Ma et al. 2023

	H. onubensis Straková et al. 2024

	H. saliterrae Straková et al. 2024

Haloarcula

H. litorea Ma et al. 2024

	H. amylovorans Ma et al. 2024

	H. limicola (Zhang & Cui 2014) Ma et al. 2024

H. marina (Ma et al. 2023) Ma et al. 2024

	H. pellucida (Echigo et al. 2013) Ma et al. 2024

	H. rubra (Durán-Viseras, Sánchez-Porro & Ventosa 2022) Ma et al. 2024

H. onubensis (Straková et al. 2024) Straková et al. 2024

H. saliterrae (Straková et al. 2024) Straková et al. 2024

	H. laminariae (Ma et al. 2023) Ma et al. 2024

	H. sediminis Ma et al. 2025

	H. rara Ma et al. 2024

	H. salinisoli (Durán-Viseras, Sánchez-Porro & Ventosa) Ma et al. 2024

H. pelagica Ma et al. 2024

	H. halophila Ma et al. 2024

	"H. montana" Liu et al. 2025

H. ordinaria Ma et al. 2024

	H. halobia Ma et al. 2024

	H. regularis Ma et al. 2025

H. salina (Zhang & Cui 2015) Ma et al. 2023

H. brevis Ma et al. 2025

	"H. rubripromontorii" Sanchez-Nieves et al. 2016

	"H. taiwanensis" Chen et al. 2018

	H. amylolytica Yang et al. 2007

	H. hispanica Juez et al. 1986

	H. mannanilytica Enomoto et al. 2020

	H. terrestris Straková et al. 2023

H. vallismortis (Gonzalez, Gutierrez & Ramirez 1979) Torreblanca et al. 1986

H. marismortui Elazari-Volcani 1940 ex Oren et al. 1990
[H. quadrata]

H. japonica Takashina et al. 1991

	H. argentinensis Ihara et al. 1997

	H. sebkhae Barreteau et al. 2019

Unassigned Haloarcula

"H. ajinwuensis"
"H. algeriensis" Kharroub et al. 2005b
"H. altuensis"
"H. morrhuae" Torreblanca et al. 1986
"H. siamensis" Namwong et al. 2007

Ecology

Haloarcula species are found in neutral saline environments such as salt lakes, marine salterns, and saline soils. Like other members of the family Halobacteriaceae, Haloarcula requires at least 1.5 M NaCl for growth, but grow optimally in 2.0 to 4.5 M NaCl.^[1]

References

1 2 3 C.L. Schoch. "Haloarcula". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2026-08-01.
↑ Oren, Aharon (2014), "The Family Halobacteriaceae", in Rosenberg, Eugene; DeLong, Edward F.; Lory, Stephen; Stackebrandt, Erko (eds.), The Prokaryotes: Other Major Lineages of Bacteria and The Archaea, Berlin, Heidelberg: Springer, pp. 41–121, Bibcode:2014prok.book...41O, doi:10.1007/978-3-642-38954-2_313, ISBN 978-3-642-38954-2, retrieved 2021-11-17
↑ Oren, A.; Ventosa, A.; Gutierrez, M. C.; Kamekura, M. (1999). "Haloarcula quadrata sp. nov., a square, motile archaeon isolated from a brine pool in Sinai (Egypt)". International Journal of Systematic Bacteriology. 49 (3): 1149–1155. doi:10.1099/00207713-49-3-1149. PMID 10425773.
↑ Haloarcula in LPSN; Freese, H. M.; Meier-Kolthoff, J. P.; Sardà Carbasse, J.; Afolayan, A. O.; Göker, M. (2026). "TYGS and LPSN in 2025: a Global Core Biodata Resource for genome-based classification and nomenclature of prokaryotes within DSMZ Digital Diversity". Nucleic Acids Research. 54 (D1): D884–D891. doi:10.1093/nar/gkaf1110.
↑ "The LTPlus". The All-Species Living Tree Project. Retrieved 1 August 2026.
↑ "LTP_all tree in newick format". The All-Species Living Tree Project. Retrieved 1 August 2026.
↑ Rossello-Mora, Ramon; Viver, Tomeu; Palmer-Rodríguez, Pere; Westram, Ralf; Bustos-Caparros, Esteban; Gago, Joan Francisco; Gonzalez-Mendez, Jaime; Llabrés, Mercè; Ludwig, Wolfgang; Amann, Rudolf (22 April 2026). "A pipeline for improved 16S rRNA gene-based phylogeny and diversity analyses of Bacteria and Archaea". Nature Portfolio. doi:10.21203/rs.3.rs-9370187/v1.
↑ "GTDB release 11-RS232". Genome Taxonomy Database. Retrieved 1 May 2026.
↑ "ar53_r232.sp_label". Genome Taxonomy Database. Retrieved 1 May 2026.
↑ "Taxon History". Genome Taxonomy Database. Retrieved 1 May 2026.

External links

Haloarcula at BacDive - the Bacterial Diversity Metadatabase

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[NCBI-1] 1 2 3 C.L. Schoch. "Haloarcula". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2026-08-01.

[:0-2] Oren, Aharon (2014), "The Family Halobacteriaceae", in Rosenberg, Eugene; DeLong, Edward F.; Lory, Stephen; Stackebrandt, Erko (eds.), The Prokaryotes: Other Major Lineages of Bacteria and The Archaea, Berlin, Heidelberg: Springer, pp. 41–121, Bibcode:2014prok.book...41O, doi:10.1007/978-3-642-38954-2_313, ISBN 978-3-642-38954-2, retrieved 2021-11-17

[3] Oren, A.; Ventosa, A.; Gutierrez, M. C.; Kamekura, M. (1999). "Haloarcula quadrata sp. nov., a square, motile archaeon isolated from a brine pool in Sinai (Egypt)". International Journal of Systematic Bacteriology. 49 (3): 1149–1155. doi:10.1099/00207713-49-3-1149. PMID 10425773.

[LPSN-4] Haloarcula in LPSN; Freese, H. M.; Meier-Kolthoff, J. P.; Sardà Carbasse, J.; Afolayan, A. O.; Göker, M. (2026). "TYGS and LPSN in 2025: a Global Core Biodata Resource for genome-based classification and nomenclature of prokaryotes within DSMZ Digital Diversity". Nucleic Acids Research. 54 (D1): D884–D891. doi:10.1093/nar/gkaf1110.

[5] "The LTPlus". The All-Species Living Tree Project. Retrieved 1 August 2026.

[6] "LTP_all tree in newick format". The All-Species Living Tree Project. Retrieved 1 August 2026.

[7] Rossello-Mora, Ramon; Viver, Tomeu; Palmer-Rodríguez, Pere; Westram, Ralf; Bustos-Caparros, Esteban; Gago, Joan Francisco; Gonzalez-Mendez, Jaime; Llabrés, Mercè; Ludwig, Wolfgang; Amann, Rudolf (22 April 2026). "A pipeline for improved 16S rRNA gene-based phylogeny and diversity analyses of Bacteria and Archaea". Nature Portfolio. doi:10.21203/rs.3.rs-9370187/v1.

[about-8] "GTDB release 11-RS232". Genome Taxonomy Database. Retrieved 1 May 2026.

[tree-9] "ar53_r232.sp_label". Genome Taxonomy Database. Retrieved 1 May 2026.

[taxon_history-10] "Taxon History". Genome Taxonomy Database. Retrieved 1 May 2026.

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