Higher order taxa
Bacteria; Bacteroidetes; Bacteroidetes (phylum); Bacteroidetes (class); Bacteroidales (order); Prevotellaceae (family); Prevotella (genus)
The genus Prevotella was named after the French microbiologist A. R. Prévot, a pioneer in anaerobic microbiology. Formerly classified within the genus Bacteroides, the species of Prevotella represent a group of unique phenotypic and phylogenetic qualities that can be readily distinguished from genus Bacteriodes. For example, unlike Bacteroides, Prevotella are sensitive to bile, moderately saccharolytic and lack the enzyme of the pentose phosphate pathway-hexose monophosphate shunt . Prevotella are characterized as gram-negative, obligately anaerobic, nonsporeforming, nonmotile, rods. Members of this genus are typically isolated from the oral cavity, upper respiratory and urogenital tract . The type species of the genus is Prevotella melaninogenica.
je.ju′ni. L. gen. n. jejuni of or from the jejunum, referring to the isolation of the type strain from the jejunum.
Jejunum is the mid section of the small intestine.
Compared with other species in Prevotella, such as the type species Prevotella melaninogenica, Prevotella jejuni uniquely was isolated from the human epithelial cells of the small intestine. The typical Prevotella habitat in the human body is the oral cavity. Other habitats or sources for isolation include feces, female genital tract, respiratory tract and from the rumen and hindgut of non-human mammals.  The type strain is CD3:28.
Genome size of 3.81×106bp for type strain CD3:28. Phylogenetic analysis based on comparative 16S rRNA gene sequence analysis revealed close relationships between CD3 : 27, CD3 : 28T and CD3 : 33, between CD3 : 32 and Prevotella histolica CCUG 55407T, and between CD3 : 34 and Prevotella melaninogenica CCUG 4944BT. 
Cell Structure and Metabolism
Prevotella species are anaerobes, and more specifically, P. jejuni cells are obligate anaerobes. Their cell structure is Gram-negative bacilli about 0.7×0.8–2 µm in size. The optimum conditions for growth are at 37 °C and pH 6–7. The cells are non-motile. 
Prevotella jejuni was isolated from the epithelial cells of the human small intestine of a child with celiac disease. Another microbe typically found there includes, Campylobacter jejuni, also named after the jejunum of the small intestine. C. jejuni is considered a pathogen that invades the human epithelial cells, rather than an inhabitant like Prevotella jejuni. Unlike P. jejuni, C.jejuni relies on motility, through use of its flagella, during the course of infection. C. jejuni is also recognized as a leading cause of gastroenteritis .
Generally considered nonpathogenic or opportunistic pathogens, species of Prevotella have been associated with serious infections. Strains of other species have demonstrated virulence factors such as hemolysins, hemagglutinins, fimbrial adhesins, proteases and phospholipases . Until now, no species of genus Prevotella has been characterized from the human small intestine. The new taxa study focuses on the isolation of the bacteria from the small intestine of a child with celiac disease (CD), and discusses its potential pathogenicity related to that disease. The purpose of the study is to further study the microbiota of the small intestine of children with CD, especially those born during first epidemic in Sweden . The jejunal microbiota is considered to play a role in the pathogenesis of CD as CD is associated with bacterial overgrowth of the small intestine, which can worsen malabsorption or cause malabsorption despite adherence to treatment . Rod-shaped bacteria constituted a significant fraction of the proximal small intestine microbiota in children born during the Swedish CD epidemic and may have been an important risk factor for CD contributing to the fourfold increase in disease incidence in children below 2 years of age during that time . From this study, the indicated species of rod-shaped bacteria of the microbiotas were from the genuses: Clostridium, Prevotella, and Actinomyces. Additionally, bacteria of all three of these genera were isolated from children born during the Swedish CD epidemic and new Prevotella species were tentatively identified.
Additional studies suggest that the genus Prevotella may contribute to cystic fibrosis, the most common lethal genetic disorder in Caucasians in the U.S. where airway infection accounts for 90% of morbidity and mortality observed in CF patients .
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Edited by Marisa Crommett, student of Rachel Larsen at the University of Southern Maine