Family Cytophagaceae Research Articles

Dyadobacter soli sp. nov., a starch-degrading bacterium isolated from farm soil

A Gram-negative, non-motile, aerobic bacterial strain, designated MJ20(T), was isolated from farm soil near Daejeon (South Korea) and was characterized taxonomically by using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain MJ20(T) belongs to the family Cytophagaceae, class Sphingobacteria, and was related most closely to Dyadobacter fermentans DSM 18053(T) (98.9 % sequence similarity), Dyadobacter beijingensis JCM 14200(T) (98.0 %) and Dyadobacter ginsengisoli KCTC 12589(T) (96.4 %). The G+C content of the genomic DNA of strain MJ20(T) was 48.5 mol%. The detection of MK-7 as the predominant menaquinone and a fatty acid profile with summed feature 4 (C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH), iso-C(15 : 0), C(16 : 0) and C(16 : 1)ω5c as major components supported the affiliation of strain MJ20(T) to the genus Dyadobacter. The new isolate exhibited relatively low levels of DNA-DNA relatedness with respect to D. fermentans DSM 18053(T) (mean±SD of three determinations, 47±7 %) and D. beijingensis JCM 14200(T) (38±8 %). On the basis of its phenotypic and genotypic properties together with phylogenetic distinctiveness, strain MJ20(T) (=KCTC 22481(T) =JCM 16232(T)) should be classified in the genus Dyadobacter as the type strain of a novel species, for which the name Dyadobacter soli sp. nov. is proposed.

Rhodocytophaga aerolata gen. nov., sp. nov., a new member of the family Cytophagaceae isolated from air

A strictly aerobic, Gram-staining-negative, oxidase- and catalase-positive, non-motile, rod-shaped bacterium, designated strain 5416T-29(T), was isolated from air and was characterized by using a polyphasic approach. Colonies were reddish pink and circular with entire margins. Flexirubin-type pigments were absent. The strain formed a distinct phylogenetic lineage within the family Cytophagaceae of the phylum Bacteroidetes. Strain 5416T-29(T) did not show more than 88 % 16S rRNA gene sequence similarity to the type strain of any recognized species. The major cellular fatty acids were C(16 : 1)omega5c, iso-C(17 : 0) 3-OH and iso-C(15 : 0). The polar lipids were phosphatidylethanolamine, one unknown amino lipid and several unknown polar lipids. Menaquinone-7 (MK-7) was the major respiratory quinone. The G+C content of the DNA of strain 5416T-29(T) was 45.5 mol%. Results of phenotypic and phylogenetic analyses clearly indicate that strain 5416T-29(T) represents a novel species of a new genus in the family Cytophagaceae, for which the name Rhodocytophaga aerolata gen. nov., sp. nov. is proposed. The type strain of Rhodocytophaga aerolata is 5416T-29(T) (=KACC 12507(T) =DSM 22190(T)).

Hongiella mannitolivorans gen. nov., sp. nov., Hongiella halophila sp. nov. and Hongiella ornithinivorans sp. nov., isolated from tidal flat sediment.

Three marine strains of the Cytophaga-Flavobacterium-Bacteroides group, designated JC2050T, JC2051T and JC2052T, were obtained from a single sediment sample of getbol, the Korean tidal flat. Comparative 16S rDNA sequence studies revealed that the test strains were not closely related to any validly published genera and that these strains were only distantly related to the genus Cyclobacterium (88.7-91.2%). Phylogenetic analyses demonstrated that the three getbol isolates formed a distinct monophyletic clade within the family Cytophagaceae. Physiological, biochemical and chemotaxonomic data also indicated that these three getbol isolates differed significantly from members of other genera and were sufficiently different from each other to be recognized as separate species. On the basis of polyphasic evidence, a new genus, Hongiella gen. nov., is proposed, with three novel species, Hongiella mannitolivorans sp. nov. (type strain JC2050T=IMSNU 14012T=DSM 15301T), Hongiella halophila sp. nov. (type strain JC2051T=IMSNU 14013T=DSM 15292T) and Hongiella ornithinivorans sp. nov. (type strain JC2052T=IMSNU 14014T=DSM 15282T). Hongiella mannitolivorans is the type species of the genus.

Role of Predatory Bacteria in the Termination of a Cyanobacterial Bloom.

Changes in cyanobacterial abundance and in the occurrence of bacteria capable of lysing cyanobacteria were monitored over a period of 6 months (May to October 1998) in eutrophic Brome Lake (Quebec, Canada), in which dense cyanobacterial blooms recur regularly. By screening lake water, we isolated two strains of lytic bacteria from the family Cytophagaceae. When tested on 12 cyanobacteria and 6 heterotrophic bacteria, strain 1 lysed only Anabaena flos-aquae and strain 2 lysed only Synechococcus cedorum, Synechococcus leopoliensis, Synechococcus elongatus, and Anacystis nidulans: both liquid and agar-grown cultures of these cyanobacteria were lysed. The number of plaque-forming units of bacteria increased dramatically during the decline of the bloom. The results are consistent with an important role for these host-specific lytic bacteria in control and elimination of cyanobacterial blooms in this lake.

Phenotypic and genetic relationships of so-called Moraxella (Pasteurella) anatipestifer to the Flavobacterium/cytophaga group

So-called Moraxella (or Pasteurella) anatipestifer and members of the Flavobacterium/ Cytophaga group exhibit remarkable common features: lack of flagellation, low guanine + cytosine content of the chromosomal DNA, production of menaquinones and branched-chain fatty acids, absence of carbohydrate fermentation, and similar patterns of hydrolytic enzymes. Using the renaturation method of DNA:DNA hybridization two urease-negative European isolates and the urease-positive type strain (which was isolated in the United States) of M. P. anatipestifer were shown to have about 85% of their genome DNA base sequences in common; they may represent two subspecies. The type strain of this species was neither measurably related to the type species of the genus Moraxella nor to selected members of the family Pasteurellaceae (Pohl 1981). On the other hand, low but significant degrees of DNA binding between selected strains of so-called M. anatipestifer, Cytophaga marinoflava, Flavobacterium meningosepticum, F. odoratum and F. pectinovorum were observed. On the basis of these findings the transfer of the so-called M. anatipestifer to the Flavobacterium/Cytophaga group (family Cytophagaceae) is proposed. More detailed investigations are required to establish its relationship at the genus level.

Capnocytophaga: new genus of gram-negative gliding bacteria. IV. DNA base composition and sequence homology.

Isolates of Gram-negative fermentative gliding bacteria which are prominantly cultivated from the subgingival sulcus in association with periodontal lesions have been the subject of a collaborative taxonomic study. Thirty-five oral strains, isolated from various states of periodontal health and disease, were examined for DNA base composition and patterns of DNA sequence homology. The phentotypically similar organism, Bacteroides ochraceus ATCC 27872, as well as two representatives of gliding bacteria in the family Cytophagaceae, Myxococcus fulvus and Sporocytophaga myxococcoides, were included in these comparisons. Mol-percent guanine and cytosine (% G+C) was determined by thermal denaturation. Relatedness was also assessed by interspecific reassociation of DNA measured by the use of a single-strand specific S1 endonuclease. DNA purified from oral gliders, B. ochraceus ATCC27872 and S. myxococcoides contained 33–41% G+C as compared with 67% in DNA from M. fulvus. Three homology groups (designated as 25, 4 and 27) were delineated by DNA homology. Homology at the 77% level was demonstrated between B. ochraceus ATCC 27872 and the oral reference strain 25. Homology group 4 comprised four strains, all of which were isolated from cases of rapidly advancing periodontal disease. The relatively high degree of genetic divergence, observed as intergroup homology levels of less than 25%, supports the naming of three species of Capnocytophaga, C. ochracea, C. sputigena and C. gingivalis by Leadbetter et al. (1979) corresponding to DNA homology groups 25, 4 and 27, respectively.

The history, biology, and taxonomy of the Cytophaga group

The first section of this review covers the important characteristics of the genera Cytophaga and Sporocytophaga. The topics discussed include vegetative cell structure, the spreading habit, and degradation of macromolecules. A historical account of these two genera follows, together with a discussion on the definition of, and species differentiation with the genus Cytophaga, and on the taxonomy of Sporocytophaga. The third section deals with the relationships of the cytophagas with the flavobacteria and includes a brief history of Flavobacterium, reassignation of some species to Cytophaga, differentiation from Cytophaga, and a discussion on the definition of the genus Flavobacterium. This is followed by a section dealing with the relationship of Cytophaga with the flexibacteria, starting with an introduction to the diversity of flexing organisms and taxonomic developments, and proceeding with the differentiation within the family Cytophagaceae, and species differentiation in Flexibacter. The concluding section includes a proposed redefinition of Cytophaga, a proposal regarding species conservation in this genus, and discussions on the relationship between the cytophagas and the myxobacteria and on the significance of cytophagas in the environment. The characteristics of all described species of Cytophaga, Flexibacter, and relevant flavobacteria are tabulated and a bibliography is presented.