The Family Bifidobacteriaceae
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The Family Bifidobacteriaceae BRUNO BIAVATI AND PAOLA MATTARELLI
Family Bifidobacteriaceae Family Bifidobacteriaceae fam. nov., Stackebrandt, Rainey and Ward-Rainey. Bifidobacteriaceae (Bi.fi.do.bac.teri.a’ce.ae. ending to denote a family; M.L. fem. pl. n. Bifidobacteriaceae, the Bifidobacterium family). The pattern of 16S rDNA signatures consists of nucleotides at positions 122-239 (G-U), 128-233 (C-G), 450-483 (C-G), 602-636 (C-G), 681-709 (C-G), 688-699 (A-U), 823-877 (A-U), 1118-1155 (C-G) and 1311-1326 (A-U; Stackebrandt et al., 1997). The family contains the type genus Bifidobacterium (Orla-Jensen, 1924) with 32 species (type species Bifidobacterium bifidum, Tissier; OrlaJensen, 1924) as well as Gardnerella (Greenwood and Pickett, 1980) with Gardnerella vaginalis as the only species. A phylogenetic structure of the genera Bifidobacterium and Gardnerella has been published (Maidak et al., 1994; LeblondBourget et al., 1996).
Characteristics of the Family The family consists of pleomorphic rods that occur singly or in many-celled chains or clumps. Cells have no capsule and they are nonsporeforming, nonmotile, and nonfilamentous. They are Gram positive except for G. vaginalis, which is Gram variable. They are anaerobic (some Bifidobacterium species can tolerate O2 only in presence of CO2) or facultatively anaerobic (Gardnerella). They are negative for the following: indole, gelatin hydrolysis, catalase (except for B. indicum and B. asteroides when grown in presence of air), and oxidase. Optimum growth temperature is 35–39°C. They possess fructose6-phosphoketolase (EC 4.1.2.2), which cleaves fructose-6-phosphate into acetylphosphate and erythrose-4-phosphate. The G+C content varies from 42–67 mol%. They are chemoorganotrophs having a fermentative type of metabolism. They produce acid but no gas from a variety of carbohydrates. They occur in animal and human habitats. They are nonpathogenic except for
bifidobacteria isolated from dental caries (and probably involved in caries pathology) and for G. vaginalis that often assumes pathogenic character (such as in bacterial vaginosis and in urogenital tract infections of both sexes).
Genus Bifidobacterium Phylogeny Tissier discovered bifidobacteria in infant feces and called them “Bacillus bifidus” (Tissier, 1899; Tissier, 1900). In 1924, Orla-Jensen recognized the existence of the genus Bifidobacterium as a separate taxon, but given their similarities to the genus Lactobacillus, bifidobacteria were included in the genus Lactobacillus as listed in the seventh edition of Bergey’s Manual of Determinative Bacteriology (Breed et al., 1957). In the eighth edition of Bergey’s Manual of Determinative Bacteriology (Buchanan et al., 1974) bifidobacteria were classified in the genus Bifidobacterium, the name initially adopted by Orla-Jensen. The genus comprised eight species and was included in the family Actinomycetaceae of the order Actinomycetales of the Actinomycetes and related organisms, although with regard to the murein structure of the cel
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