Ruminococcus
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| Sijpesteijn , 1948 |
Ruminococcus is a genus of bacteria that occurs mainly in the rumen ( rumen ) and in the large intestine of herbivores . These are spherical to oval cocci that occur in pairs or as chains and can onlylive in theabsence of oxygen (obligatorily anaerobic ). They are gram-positive and have great physiological importance as rumen bacteria in the digestion of cellulose in the digestive tract of herbivores.
Ruminococcus in the rumen
Two species of the genus, Ruminococcus flavefaciens and Ruminococcus albus , as well as the (alien) gram-negative bacterium Fibrobacter succinogenes are the most important bacteria for the dissolution of cellulose in the rumen.
The important enzyme to break down cellulose is cellulase . Fibrobacter cellulase is a periplasmic enzyme, which means that it sits in the periplasm between the two outer cell membranes. Fibrobacter is thus forced to attach to the cellulose fibrils. The Ruminococcus species, on the other hand, release this enzyme in the rumen; the cellulase of this bacterium is an exoenzyme . The polysaccharide cellulose is then dissolved by the enzyme, the result being glucose . Glucose is reabsorbed by the bacteria and used as a source of energy through fermentation ; the fermentation products excreted again are in turn absorbed by the animal as an energy source. The products used by the ruminant are mainly carboxylic acids . The carboxylic acids released by Ruminococcus are acetic acid (acetate) and formate , further end products of fermentation are carbon dioxide and hydrogen . In the case of Fibrobacter , there are acetate, formic acid (formate) and succinic acid (succinate).
Systematics
Current system
The genus Ruminococcus in the family Ruminococcaceae is placed in the order Clostridiales in the department of Firmicutes . The following species are known of the genus (status 2014):
- Ruminococcus albus Hungate 1957
- Ruminococcus bromii Moore et al. 1972
- Ruminococcus callidus Holdeman & Moore 1974
- Ruminococcus champanellensis Chassard et al. 2012
- Ruminococcus faecis Kim et al. 2011
- Ruminococcus flavefaciens Sijpesteijn 1948 (the type species of the genus)
- Ruminococcus gauvreauii Domingo et al. 2008
- Ruminococcus gnavus Moore et al. 1976
- Ruminococcus lactaris Moore et al. 1976
- Ruminococcus obeum Moore et al. 1976
- Ruminococcus torques Holdeman & Moore 1974
Several species that previously belonged to the genus Ruminococcus were assigned to the genus Blautia in 2008 , this concerns R. hansenii (now Blautia hansenii ), R. hydrogenotrophicus (now Blautia hydrogenotrophica ), R. luti (now Blautia luti ), R. productus ( now Blautia producta ) and R. schinkii (now Blautia schinkii ).
Synonyms
The two species R. pasteurii and R. palustris are also no longer included in this genus. R. pasteurii is now a basionym for Trichococcus pasteurii . R. palustris is a basionym for Trichococcus palustris (another synonym is Lactosphaera pasteurii ). Other synonyms for R. productus are Peptostreptococcus productus and Streptococcus productus , the synonym for R. hansenii is Streptococcus hansenii Holdeman and Moore, 1974.
Individual evidence
- ^ A b Jean Euzéby, Aidan C. Parte: Genus Ruminococcus. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved January 4, 2014 .
- ↑ National Center for Biotechnology Information (NCBI) (as of February 2007)
literature
- Michael T. Madigan, John M. Martinko, Jack Parker: Brock - Microbiology . 11th edition. Pearson Studium, Munich 2006, ISBN 3-8274-0566-1