Gemella

Gemella
Systematics
Domain :	Bacteria (bacteria)
Department :	Firmicutes
Class :	Bacilli
Order :	Bacillales
	incertae sedis
Genre :	Gemella
Scientific name
	Gemella
	Berger 1960

Gemella is a genus of bacteria . It belongs to the Firmicutes department . The species Gemella haemolysans and G. morbillorum can be pathogenic for humans.

features

The species of Gemella are gram positive . However, some colonies discolor slightly with Gram staining and thus give Gram-negative or Gram-variable reactions. The cell walls are relatively thin (10-20 nm), which is probably responsible for their gram-variable character. The cells are egg-shaped, the individual cells are arranged in pairs, tetrads and in cluster-shaped clusters of cells. Short chains are also rare. Pleomorphic cells with elongated and rod-shaped shapes can also occur. The size of the cells can vary widely. The diameter varies from about 0.5 mm to more than 1 mm and "giant cells" have been observed. In the species Gemella morbillorum the pleomorphism can be very pronounced; the cocci can be slightly elongated and the cells can be of unequal size. Elongated cells are mostly 0.5 × 1.2 μm in size, but longer cells (up to 2-3 μm) have also been reported.

The genus Gemella is facultatively anaerobic and shows the best growth rates with a high CO ₂ content. The oxidase test and catalase test are negative. Gemella uses fermentation as a metabolic pathway . G. haemolysans and G. morbillorum ferment glucose to acetic acid and lactic acid in the absence of oxygen .

Gemella as a pathogen

Gemella haemolysans and G. morbillorum inhabit the mucous membranes of humans and other mammals. Gemella haemolysans has been found in the oral cavity and upper digestive tract of healthy people. However, Gemella haemolysans can also be pathogenic and cause endocarditis . Gemella morbillorum can cause sepsis , abscesses and wound infections and infections in the urogenital area . However, infections rarely occur. The two species can be distinguished from the enterococci by the tolerated sodium chloride content; in contrast to enterococci, they no longer show any growth at an NaCl content of 6.5%. The antibiotic penicillin G can be used against infections of Gemella .

Systematics

The genus Gemella was originally placed in the Neisseriaceae family , but further investigation showed too many inconsistencies with the characteristics of this family. In 1974 it was assigned to the Staphylococcaceae family, but at that time the family was not yet recognized in terms of the bacterial systematics. It was later shown that Gemella differs so much from the other genera due to some characteristics that the allocation to a common family in 2009 no longer seemed justifiable. The reasons for this are in particular the negative catalase and oxidase test and the composition of the lipids in the cell membrane . Currently (August 2019) it is not assigned to any family, but as Incertae sedis only placed in the order Bacillales .

The following is a list of some species of the genus (as of August 2019)

Gemella asaccharolytica Ulger-Toprak et al. 2010
Gemella bergeri corrig. Collins et al. 1998
Gemella cuniculi, Hoyles et al. 2000
Gemella haemolysans (Thjøtta and Bøe 1938) Berger 1960 (the type species of the genus)
Gemella morbillorum (Prévot 1933) Kilpper-Bälz and Schleifer 1988
Gemella palaticanis Collins et al. 1999
Gemella parahaemolysans Hung et al. 2014
Gemella sanguinis Collins et al. 1999
Gemella taiwanensis Hung et al. 2014

swell

literature

Martin Dworkin (Ed.): The prokaryotes. A handbook on the biology of bacteria. Volume 4: Firmicutes, Cyanobacteria. 3rd edition, Springer, New York 2006, ISBN 0-387-25494-3 .
Paul de Vos et al. (Ed.): Bergey's Manual of Systematic Bacteriology . 2nd edition, Volume 3: The Firmicutes . Springer, New York 2009, ISBN 0-387-95041-9 .

Individual evidence

^ ^A ^b ^c Wolfgang Ludwig, Karl-Heinz Schleifer, William B. Whitman: Revised road map to the phylum Firmicutes . In: Paul de Vos et al. (Ed.): Bergey's Manual of Systematic Bacteriology . 2nd edition, Volume 3: The Firmicutes . Springer, New York 2009, ISBN 978-0-387-95041-9 , pp. 1–13 , doi : 10.1007 / 978-0-387-68489-5_1 .
↑ Martin Dworkin (Ed.): The prokaryotes. A handbook on the biology of bacteria. Volume 4: Firmicutes, Cyanobacteria. 3rd edition, Springer, New York
↑ ^a ^b ^c Dieter Adam and others: The infectious disease . Springer, Berlin / Heidelberg 2004, ISBN 978-3-540-00075-4 .
^ ^A ^b Jean Euzéby, Aidan C. Parte: Genus Gemella. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved August 15, 2019 .

[bergey-1] A ^b ^c Wolfgang Ludwig, Karl-Heinz Schleifer, William B. Whitman: Revised road map to the phylum Firmicutes . In: Paul de Vos et al. (Ed.): Bergey's Manual of Systematic Bacteriology . 2nd edition, Volume 3: The Firmicutes . Springer, New York 2009, ISBN 978-0-387-95041-9 , pp. 1–13 , doi : 10.1007 / 978-0-387-68489-5_1 .

[Dworkin-2] Martin Dworkin (Ed.): The prokaryotes. A handbook on the biology of bacteria. Volume 4: Firmicutes, Cyanobacteria. 3rd edition, Springer, New York

[Infektiologie-3] Dieter Adam and others: The infectious disease . Springer, Berlin / Heidelberg 2004, ISBN 978-3-540-00075-4 .

[lpsn-4] A ^b Jean Euzéby, Aidan C. Parte: Genus Gemella. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved August 15, 2019 .