Bacteroides
Bacteroides fragilis in the Gram stain
In the genus Bacteroides (syn. Bacteroidacea ) is obligately anaerobic, pleomorphic, Gram-negative rod-shaped bacteria belonging to the normal flora of the mucous membranes of the intestinal tract.
Features
The members of the genus Bacteroides are obligate anaerobes, they grow only in the absence of oxygen. They do not form spores and their metabolic pathway is the fermentation. They utilize various sugars in fermentation, forming a v. acetate and succinate. Some Bacteroides species can also utilize citrate as fermentation products are formed, inter alia, acetate and formate.
A special feature to mention that many species of the genus Bacteroides high to predominant proportion of branched fatty acid chains have in their lipid membranes. A further important feature is the production of sphingolipids.
Occurrence
In the large intestine can be found approximately 1011 copies per gram of stool, so are Bacteroides species there the numerically dominant bacteria. The incidence of Bacteroides species in the faeces is in some species recorded in their name, such as Bacteroides faecis, Bacteroides caccae or Bacteroides coprophilus.
System
Some species of the genus:
- Bacteroides caccae Johnson et al. 1986
- Bacteroides coprophilus Hayashi et al. 2007
- Bacteroides faecichinchillae Kitahara et al. 2012
- Bacteroides faecis Kim et al. 2010
- Bacteroides fragilis ( Veillon and Zuber 1898) Castellani and Chalmers 1919 ( type species )
- Bacteroides intestinalis Bakir et al. 2006
- Bacteroides pectinophilus Jensen and Canale - Parola 1987
- Bacteroides thetaiotaomicron ( Distaso 1912) Castellani and Chalmers 1919
- Bacteroides vulgatus Eggert and Gagnon 1933
- Bacteroides xylanolyticus Scholten- Koerselman et al. 1988
Been numerous types, are involved in inflammation of the tooth root or members of the oral flora and have previously been assigned to the genus Bacteroides, the genus Prevotella ( in the family of Prevotellaceae ) are associated (as in 2013 ), such as Bacteroides oralis is now Prevotella oralis, Bacteroides denticola is now correctly identified as Prevotella denticola.
Medical importance
By Bacteroides species also infections are caused, they are mainly under the anaerobic pathogens of importance. It is almost exclusively endogenous infections, since these bacteria have only low pathogenicity. They mainly cause peritonitis, intra-abdominal abscesses and liver abscesses.