# Gemella

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Genus of bacteria

For the settlement in Algeria, see [M'Lili](/source/M'Lili). For the Roman colony in Hispania, see [Acci](/source/Acci).

Gemella Scientific classification Domain: Bacteria Kingdom: Bacillati Phylum: Bacillota Class: Bacilli Order: Caryophanales Family: Gemellaceae Chuvochina et al. 2024 Genus: Gemella Berger 1960[1] Type species Gemella haemolysans (Thjøtta & Bøe 1938) Berger 1960 Species[2] G. asaccharolytic G. bergeri G. cuniculi G. haemolysans G. massiliensis G. morbillorum G. palaticanis G. parahaemolysans G. sanguinis G. taiwanensis Synonyms Gemelliphila Bello et al. 2024

***Gemella*** is a genus of [Gram-positive](/source/Gram-positive) [bacteria](/source/Bacteria) that thrive best at high [partial pressure](/source/Partial_pressure) of [CO2](/source/Carbon_dioxide).

## Description

A *Gemella* species was first described as *Neisseria hemolysans* in 1938.[3] It was reclassified as a new genus in 1960 when strains were found to be distinct enough from Neisseria to require a new genus.[4] The name was suggested based on the organism being a [diplococcus](/source/Diplococcus) and gemellus is the diminutive of geminus, which is Latin for twin.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] They are [facultatively anaerobic](/source/Facultative_anaerobe) and give negative reactions to both [oxidase](/source/Oxidase) and [catalase](/source/Catalase) tests. They are obligately [fermentative](/source/Fermentation_(biochemistry)), producing either a mixture of [acetic](/source/Acetic_acid) and [lactic](/source/Lactic_acid) acids or an equimolar molar mixture of acetic acid and CO2. For example, *G. haemolysans* ferments [glucose](/source/Glucose) forming a mixture of acetic and lactic acids in the absence of [oxygen](/source/Oxygen), whereas when oxygen is present, it forms acetic acid and CO2.[5]

## Clinical importance

*Gemella* bacteria are primarily found in the [mucous membranes](/source/Mucous_membrane) of humans and other animals, particularly in the [oral cavity](/source/Oral_cavity) and upper [digestive tract](/source/Digestive_tract). *Gemella haemolysans* has been found to be involved in pulmonary exacerbations of [cystic fibrosis](/source/Cystic_fibrosis) patients.[6] As of the year 2000 it had been reported in 15 cases of human [endocarditis](/source/Endocarditis), mainly in men with underlying [valvular disease](/source/Valvular_heart_disease) and/or poor dentition or dental manipulation. Most cases were treated with a combination of penicillin and gentamicin with a favorable outcome.[7] Additionally, *Gemella asaccharolytica* in bacterial vaginosis is associated with increase risk of HIV infection in unprotected sex.

## Phylogeny

The currently accepted taxonomy is based on the [List of Prokaryotic names with Standing in Nomenclature](/source/List_of_Prokaryotic_names_with_Standing_in_Nomenclature) (LPSN)[1] and [National Center for Biotechnology Information](/source/National_Center_for_Biotechnology_Information) (NCBI).[2]

16S rRNA based LTP_10_2024[8][9][10] 120 marker proteins based GTDB 09-RS220[11][12][13] Gemella G. taiwanensis Hung et al. 2014 G. haemolysans (Thjøtta & Bøe 1938) Berger 1960 G. parahaemolysans Hung et al. 2014 G. sanguinis Collins et al. 1999 G. morbillorum (Prévot 1933) Kilpper-Bälz & Schleifer 1988 G. cuniculi Hoyles et al. 2000 G. bergeri corrig. Collins et al. 1998 G. massiliensis Mbogning Fonkou et al. 2023 G. asaccharolytic Ulger-Toprak et al. 2010 G. palaticanis Collins et al. 1999 Gemella G. asaccharolytic G. palaticanis G. bergeri G. massiliensis G. cuniculi G. sanguinis G. morbillorum G. haemolysans Gemelliphila Gemella s.s.

## References

1. ^ [***a***](#cite_ref-LPSN_1-0) [***b***](#cite_ref-LPSN_1-1) A.C. Parte; et al. ["Gemella"](https://lpsn.dsmz.de/genus/gemella). [List of Prokaryotic names with Standing in Nomenclature](/source/List_of_Prokaryotic_names_with_Standing_in_Nomenclature) (LPSN). Retrieved 2025-02-28.

1. ^ [***a***](#cite_ref-NCBI_2-0) [***b***](#cite_ref-NCBI_2-1) C.L. Schoch; et al. ["Gemella"](https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=1378&lvl=3&lin=f&keep=1&srchmode=1&unlock). [National Center for Biotechnology Information](/source/National_Center_for_Biotechnology_Information) (NCBI) taxonomy database. Retrieved 2025-02-28.

1. **[^](#cite_ref-3)** Thjøtta, T; Bøe, J (1938). "Neisseria hemolysans. A Hemolytic Species of Neisseria trevisan". *Acta Pathologica et Bacteriologica Scandinavica Supplement*. **37**: 527–531.

1. **[^](#cite_ref-4)** BERGER, U. (1961-01-01). ["A proposed new genus of gram-negative cocci: Gemella"](https://doi.org/10.1099%2F0096266x-11-1-17). *International Bulletin of Bacteriological Nomenclature and Taxonomy*. **11** (1): 17–19. [doi](/source/Doi_(identifier)):[10.1099/0096266x-11-1-17](https://doi.org/10.1099%2F0096266x-11-1-17).

1. **[^](#cite_ref-5)** Stackebrandt, E.; B. Wittek; E. Seewaldt & K. H. Schleifer (1982). ["Physiological, biochemical and phylogenetic studies on *Gemella haemolysans*"](https://doi.org/10.1111%2Fj.1574-6968.1982.tb08288.x). *FEMS Microbiology Letters*. **13** (4): 361–365. [doi](/source/Doi_(identifier)):[10.1111/j.1574-6968.1982.tb08288.x](https://doi.org/10.1111%2Fj.1574-6968.1982.tb08288.x).

1. **[^](#cite_ref-6)** Carmody, Lisa A.; Zhao, Jiangchao; Schloss, Patrick D.; Petrosino, Joseph F.; Murray, Susan; Young, Vincent B.; Li, Jun Z.; LiPuma, John J. (2013-06-01). ["Changes in Cystic Fibrosis Airway Microbiota at Pulmonary Exacerbation"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960905). *Annals of the American Thoracic Society*. **10** (3): 179–187. [doi](/source/Doi_(identifier)):[10.1513/AnnalsATS.201211-107OC](https://doi.org/10.1513%2FAnnalsATS.201211-107OC). [ISSN](/source/ISSN_(identifier)) [2329-6933](https://search.worldcat.org/issn/2329-6933). [PMC](/source/PMC_(identifier)) [3960905](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960905). [PMID](/source/PMID_(identifier)) [23802813](https://pubmed.ncbi.nlm.nih.gov/23802813).

1. **[^](#cite_ref-7)** Mosquera, J.D.; Zabalza, M.; Laniero, M.; Blanco, J.R. (2000). ["Endocarditis due to Gemella haemolysans in a patient with hemochromatosis"](https://doi.org/10.1046%2Fj.1469-0691.2000.00136.x). *Clinical Microbiology and Infection*. **6** (10): 566–568. [doi](/source/Doi_(identifier)):[10.1046/j.1469-0691.2000.00136.x](https://doi.org/10.1046%2Fj.1469-0691.2000.00136.x). [PMID](/source/PMID_(identifier)) [11168056](https://pubmed.ncbi.nlm.nih.gov/11168056).

1. **[^](#cite_ref-8)** ["The LTP"](https://imedea.uib-csic.es/mmg/ltp/#LTP). Retrieved 10 December 2024.

1. **[^](#cite_ref-9)** ["LTP_all tree in newick format"](https://imedea.uib-csic.es/mmg/ltp/wp-content/uploads/ltp/LTP_all_10_2024.ntree). Retrieved 10 December 2024.

1. **[^](#cite_ref-10)** ["LTP_10_2024 Release Notes"](https://imedea.uib-csic.es/mmg/ltp/wp-content/uploads/ltp/LTP_10_2024_release_notes.pdf) (PDF). Retrieved 10 December 2024.

1. **[^](#cite_ref-about_11-0)** ["GTDB release 09-RS220"](https://gtdb.ecogenomic.org/about#4%7C). *[Genome Taxonomy Database](/source/Genome_Taxonomy_Database)*. Retrieved 10 May 2024.

1. **[^](#cite_ref-tree_12-0)** ["bac120_r220.sp_labels"](https://data.gtdb.ecogenomic.org/releases/release220/220.0/auxillary_files/bac120_r220.sp_labels.tree). *[Genome Taxonomy Database](/source/Genome_Taxonomy_Database)*. Retrieved 10 May 2024.

1. **[^](#cite_ref-taxon_history_13-0)** ["Taxon History"](https://gtdb.ecogenomic.org/taxon_history/). *[Genome Taxonomy Database](/source/Genome_Taxonomy_Database)*. Retrieved 10 May 2024.

Taxon identifiers Gemella Wikidata: Q3209512 Wikispecies: Gemella CoL: 4MP8 EoL: 98099 GBIF: 3227646 IRMNG: 1298108 ITIS: 957235 LPSN: gemella NCBI: 1378 NZOR: c5ec1dcd-2872-48ec-bffd-51ec036c0b59 Open Tree of Life: 533518 SeqCode Registry: 8189 Gemellaceae Wikidata: Q124624533 LPSN: gemellaceae SeqCode Registry: 34414

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