The Genus Wolinella
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The Genus Wolinella JÖ RG SIMON, ROLAND GROSS, OLIVER KLIMMEK AND ACHIM KRÖ GER
Introduction
Taxonomy
The genus Wolinella belongs to the family Helicobacteraceae (epsilon subclass of the Proteobacteria). There is only one species of the genus, W. succinogenes. The species formerly known as W. recta and W. curva have been re-classified as Campylobacter rectus and C. curvus (see [Phylogeny] and [Taxonomy]). W. succinogenes was isolated from bovine rumen fluid (see [Habitat and Isolation]) and can be identified and differentiated from other species by various morphological, biochemical and genetic methods (see [Identification]). The cells grow only by anaerobic respiration and do not ferment carbohydrates (see [Cultivation] and [Physiology]). Fumarate, nitrate, nitrite, nitrous oxide (N2O), polysulfide or dimethyl sulfoxide (DMSO) can serve as terminal electron acceptor with formate as the electron donor. Molecular hydrogen and, at least in fumarate respiration, sulfide are alternative electron donor substrates. The electron transport enzymes and the mechanism for generating the electrochemical proton potential across the membrane are described in the section [Physiology]. Most of the genes encoding the electron transport enzyme complexes are known and a system for site-directed mutagenesis in W. succinogenes was established for both the operons coding for the subunits of fumarate reductase and hydrogenase (see [Genetics]).
There is only one species of the genus, the type species Wolinella succinogenes (previously classified as Vibrio succinogenes by Wolin et al., 1961). Two oral species of Wolinella, W. recta and W. curva (Tanner et al., 1981), are now described as members of the genus Campylobacter, based on 16S rRNA sequence analysis (Paster and Dewhirst, 1988; Vandamme et al., 1991). The type strain of W. succinogenes is ATCC 29543T (FDC 602W; FDC: Forsyth Dental Center, Boston, MA, USA).
Phylogeny The overall phylogenetic position of Wolinella relative to other Gram-negative bacteria was determined from 16S rRNA sequencing. This indicated that the genus Wolinella falls in the family Helicobacteraceae, which belongs to the epsilon subclass of the Proteobacteria (Fig. 1). Other closely related bacteria are grouped within the family Campylobacteraceae, including the genera Sulfurospirillum, Arcobacter and Campylobacter.
Habitat Wolinella succinogenes was isolated from bovine rumen fluid (Wolin et al., 1961). Isolates resembling W. succinogenes have been isolated from sewage (Yoshinari, 1980; Tanner et al., 1984) and from humans (Radcliffe et al., 1979); however, no genetic information for these strains is available.
Isolation Wolinella succinogenes was originally isolated from an inoculum of bovine rumen fluid after serial transfer in an anaerobic methanogenic enrichment medium containing formate, sulfide, and inorganic salts. Secondary enrichment was made in a broth medium containing formate and fumarate (Wolin et al., 1961). Additional strains of W. succinogenes were recently
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