Taxonomic study of Cellvibrio strains and description of Cellvibrio ostraviensis sp. nov., Cellvibrio fibrivorans sp. nov. and Cellvibrio gandavensis sp. nov.

Thirty-one cellulolytic bacterial isolates from soils that were phenotypically very similar and phylogenetically highly related to Cellvibrio strains were further characterized using a polyphasic taxonomic approach. By using repetitive extragenic palindromic DNA-PCR fingerprinting, six different fingerprints could be recognized among the isolates. Representative strains and four reference strains of the genus Cellvibrio were used for DNA-DNA hybridization, which yielded eight DNA hybridization groups at a cut-off level of 70% DNA binding. One group was formed by three isolates and Cellvibrio vulgaris LMG 2848T and a second group consisted of Cellvibrio mixtus strains ACM 2601T and ACM 2603. Two isolates and Cellvibrio fulvus LMG 2847T constituted single-member groups. For the remaining groups, three novel species are proposed: Cellvibrio fibrivorans sp. nov. (six strains, type strain LMG 18561T =ACM 5172T), Cellvibrio ostraviensis sp. nov. (eight strains, type strain LMG 19434T =ACM 5173T) and Cellvibrio gandavensis sp. nov. (12 strains, type strain LMG 18551T =ACM 5174T). The novel Cellvibrio species could be differentiated from each other and from C. mixtus, C. vulgaris and C. fulvus on the basis of phenotypic features, their fatty acid compositions and the G + C content of their DNA.