16S Ribosomal ribonucleic acid sequence analyses of lactococci and related taxa. Description of Vagococcus fluvialis gen. nov., sp. nov.

Abstract

The phylogenetic status of members of the genus Lactococcus and some motile strains which react with Lancefield group N antiserum was examined by reverse transcriptase sequencing of 16S ribosomal ribonucleic acid. In agreement with earlier nucleic acid hybridization and immunological studies of superoxide dismutase the 16S sequence data clearly demonstrate that the lactococci represent a distinct phylogenetic group equivalent in rank to the genera Enterococcus and Streptococcus. The motile group N strains from chicken faeces and river water, however, were found to be phylogenetically unrelated to lactococci but displayed a closer, albeit loose, association with members of the genus Enterococcus. On the basis of the present sequence data and earlier chemotaxonomic studies it is proposed that the motile group N strains be classified in a new genus Vagococcus, as Vagococcus fluvialis sp. nov. The type strain of V. fluvialis is NCDO 2497.

How Close Is Close: 16S rRNA Sequence Identity May Not Be Sufficient To Guarantee Species Identity

“…In such cases the 16s rRNA data would be sufficient to identify any strains that were clear outsiders but could never convincingly establish that the remaining genetic diversity was consistent with the existence of only one species. This interpretation has already been recognized and implemented by Collins and coworkers (1,6,27). In recent studies of Lactobacillus lactis (6), Streptococcus parasanguis (27), and Mycobacterium intracellulare (4) strains, less than 10 sequence differences were encountered in each case.…”

“…This interpretation has already been recognized and implemented by Collins and coworkers (1,6,27). In recent studies of Lactobacillus lactis (6), Streptococcus parasanguis (27), and Mycobacterium intracellulare (4) strains, less than 10 sequence differences were encountered in each case. Since the strains had been assigned to their respective species on the basis of other criteria, the authors attributed the differences to possible interspecies diversity rather than create a new species.…”

Identification and Classification of Lactobacillus Acidophilus, L. Gasseri and L. Johnsonii Strains by SDS-PAGE and rRNA-Targeted Oligonucleotide Probe Hybridization

“…These procedures are not only time-consuming, but owing to an increasing number of LAB species, are also very ambiguous. rRNA sequencing and DNA : DNA hybridization studies have improved our taxonomic knowledge on the generic and suprageneric relationships of LAB (Collins et al, 1989(Collins et al, , 1991KilpperBalz et al, 1982;Ludwig et al, 1985;Martinez-Murcia & Collins, 1990;Schleifer et al, 1985;). Identification to the species level, however, is still time-consuming, requires the back-up of a large database of rRNA sequences and *Author for correspondence.…”

Vagococcus fessus sp. nov., isolated from a seal and a harbour porpoise.

“…The genus Vagococcus was proposed (Collins et al, 1989) to accommodate a phylogenetically distinct group of Gram-positive, motile, coccus-shaped organisms which resembled lactococci in reacting with Lancefield group N antisera. The genus was originally monospecific, containing the species Vagococcus fluvialis, isolated from chicken faeces and river water (Hashimoto et al, 1974).…”