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For the settlement in Algeria, see M'Lili.
Scientific classification
Kingdom: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Bacillales
Genus: Gemella
Berger 1960

G. bergeri
G. cuniculi
G. haemolysans
G. morbillorum
G. palaticanis
G. sanguinis

Gemella is a genus of Gram-positive bacteria that thrive best at high partial pressure of CO2.


They are facultatively anaerobic and give negative reactions to both oxidase and catalase tests. They are obligately fermentative, producing either a mixture of acetic and lactic acids or an equimolar molar mixture of acetic acid and CO2. For example, G. haemolysans ferments glucose forming a mixture of acetic and lactic acids in the absence of oxygen, whereas when oxygen is present, it forms acetic acid and CO2.[2]

Clinical importance[edit]

Gemella bacteria are primarily found in the mucous membranes of humans and other animals, particularly in the oral cavity and upper digestive tract. Gemella haemolysans has been found to be involved in pulmonary exacerbations of cystic fibrosis patients.


  1. ^ Euzéby, J. P. "List of Prokaryotic Names with Standing in Nomenclature". Retrieved 2008-12-16. 
  2. ^ Stackebrandt, E., B. Wittek, E. Seewaldt, and K. H. Schleifer (1982). "Physiological, biochemical and phylogenetic studies on Gemella haemolysans". FEMS Microbiology Letters 13 (4): 361–365. doi:10.1111/j.1574-6968.1982.tb08288.x.