Phylogenetic diversity of the genus Cytophaga revealed by 16S rRNA sequencing and menaquinone analysis

Abstract

To clarify the intra-and intergeneric relationships of the genus Cytophaga, 16s rRNA sequences and respiratory isoprenoid quinones were determined for the type strains of the 21 validly published species and one isolate in the genus Cytophaga. The sequence analysis revealed extreme heterogeneity of this genus, which diverged into nine distinct lines of descent. Each lineage of Cytophaga was characterized by possessing either menaquinone-6 (MK-6) or MK-7. The MK-6-possessing species were located in the two lineages that were remote from MK-7 species. One of the MK-6 lineages was composed only of terrestrial species and the other only of marine species. Flavobacterium aquatile, the type species of the genus Flavobacterium, was located in the MK-6 terrestrial lineage. The terrestrial Cytophaga species with MK-6 should be transferred to the genus Flavobacterium. The marine facultative anaerobes with MK-7 were located in the bacteroides branch, and possessed signature sequences with features intermediate between the bacteroides and the flavobacteria subdivisions. Cytophaga hutchinsonii, the type species of the genus Cytophaga, had a close relationship only with Cytophaga auvantiaca. The genus Cytophaga should be restricted to these two cellulose-degrading species. The genus Cytophaga is so heterogeneous that it should be divided into several genera and higher taxa in accordance with the phylogenetic relationships.

Anthropogenic impacts on water quality of the lagoonal coast of Fongafale Islet, Funafuti Atoll, Tuvalu

“…Q-8, Q-9 and Q-10 are assigned to the beta, gamma and alpha subclasses of Proteobacteria, respectively (Yokota et al 1992). MK-6, MK-7 and MK-8 are assigned to taxonomic groups including the Flavobacterium-Cytophaga group (Nakagawa and Yamasato 1993) and gram-positive bacteria with low G ? C contents (Collins and Jones 1981).…”

NOTES: New Perspectives in the Classification of the Flavobacteria: Description of Chryseobacterium gen. nov., Bergeyella gen. nov., and Empedobacter nom. rev.

“…One of the main conclusions of these studies is that the genera Flavobacterium, Cytophaga, and Flexibacter all are polyphyletic and should be redefined and subdivided into several genera. The relationships of these taxa to other members of this rRNA superfamily, such as the genera Capnocytophaga, Omithobacterium, Riemerella, and Weeksella, have been described in several papers (10,25,28,33) and are partially shown in Fig. 1 none of the four natural groups described above is closely related to F. aquatile.…”

“…Not surprisingly, these features have turned out to have limited taxonomic value, and genus delineation has remained troublesome (27). Recently, several phylogenetic analyses have provided new insights concerning the taxonomic relationships within this cluster of organisms, which is often referred to as the Flavobacterium-Cytophaga rRNA cluster (10,25,28). One of the main conclusions of these studies is that the genera Flavobacterium, Cytophaga, and Flexibacter all are polyphyletic and should be redefined and subdivided into several genera.…”

Meiothermus hypogaeus sp. nov., a moderately thermophilic bacterium isolated from a hot spring

“…Respiratory quinones were extracted from cells of strain AZM34c11 T by using the protocol described by Nakagawa & Yamasato (1993) and analysed with an LCMS-QP 8000alpha spectrometer (Shimadzu). This respiratory quinone was menaquinone-8, which has been found in all described members of the phylum Deinococcus-Thermus.…”