The Genera Flavobacterium, Sphingobacterium and Weeksella
The name Flavobacterium was proposed in 1923 for a genus of the family Bacteriaceae encompassing the rod-shaped, nonendosporeforming, chemoorganotrophic bacteria (Bergey et al., 1923 ). Most of the pigmented bacteria of the family were segregated in the t
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The Genera Flavobacterium, Sphingobacterium and Weeksella BARRY HOLMES
The name Flavobacterium was proposed in 1923 for a genus of the family Bacteriaceae encompassing the rod-shaped, nonendosporeforming, chemoorganotrophic bacteria (Bergey et al., 1923). Most of the pigmented bacteria of the family were segregated in the tribe Chromobactereae, which contained four genera of aerobic bacteria separated from each other by differences in color. These genera were Chromobacterium, Flavobacterium, Pseudomonas, and Serratia, for the purple, yellow, green fluorescent, and red strains, respectively. This emphasis on pigmentation (a character shared by genetically diverse bacteria [Weeks, 1969]) for taxonomic assignment to Flavobacterium has given the genus a dubious reputation in the past (McMeekin et al., 1972; Weeks, 1969), and as a consequence the genus has served too frequently as a repository for pigmented bacteria that possess the general attributes of Flavobacterium but had not been subjected to detailed classification studies. Taxonomic heterogeneity and general uncertainty have characterized Flavobacterium from its inception, and its history is a record of proposals to achieve credibility for the genus. Stanier (1947) recognized that the cytophagas have more than a casual phenetic resemblance to pigmented, Gram-negative eubacteria such as Flavobacterium and the relationship to the cytophagas has dominated the taxonomic consideration of Flavobacterium. Differentiation of flavobacteria from cytophagas has depended primarily upon demonstration of the gliding movement and colonial translocation characteristic of the latter bacteria, but absence of these features has not deterred assignment of flavobacterial species to Cytophaga (Mitchell et al., 1969). Freshly isolated cytophagas have the unusual ability to use a great variety of complex natural polymers, e.g., agar, alginates, cell walls, cellulose, chitin, DNA, keratins, lipids, pectin, porphyrins, proteins, RNA, and starch, as nutrients. This ability is not a general property of flavobacterial species, although strains of some species may hydrolyze casein, chitin, gelatin, or starch. This chapter was taken unchanged from the second edition.
The problem of differentiating Flavobacterium from Cytophaga has been discussed extensively (Christensen, 1977a; McMeekin et al., 1972; Mitchell et al., 1969; Weeks, 1969). An outcome would be more nearly possible if two issues were resolved. These are the heterogeneity of Flavobacterium and the differentiation of nonmotile flavobacteria from cytophagas. A primary requirement for the resolution of both issues is an acceptable definition of Flavobacterium. The concept of Flavobacterium was hardly altered in successive editions of Bergey’s Manual of Determinative Bacteriology until the fifth (Bergey et al., 1939), which eliminated from the genus the least well-described species and the polarly flagellated strains. Those known to be Gram-positive were
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