1% between F. aquatile and Flavobacterium reichenbachii to 94.9% between F. xanthum and F. omnivorum. The phylogenetic trees based on the gyrB sequences (Figs 2 and S2) show that the groups found in the 16S rRNA gene dendrogram (Figs 1 and S1) were confirmed. The

Antarctic Flavobacterium groups generally showed lower gyrB gene sequence similarity to neighbouring groups and species, which confirmed their status as potentially new species. Flavobacterium sp. 13 and sp. 5, which, in the 16S rRNA gene phylogeny, were closely related to F. micromati and F. gelidilacus, respectively, also group with these species in the gyrB phylogeny. Both groupings are well supported; however, the gyrB similarity of Flavobacterium sp. 13 to F. micromati LMG 21919 (97.0%) is higher than that of Flavobacterium sp. 5 to F. gelidilacus LMG 21477 (91.9%). Flavobacterium sp. 13 probably belongs to F. micromati that was originally EPZ015666 isolated from microbial mats in Antarctic lakes (Van Trappen et al., 2004) as were the isolates of Flavobacterium sp. 13 (Table 1). Flavobacterium sp. 5 probably represents a new species in view of the rather low gyrB gene sequence

similarity to F. gelidilacus in comparison with the higher similarity values obtained between some type strains. Nevertheless, the precise relation to F. gelidilacus, selleck screening library another species from Antarctic microbial mats (Van Trappen et al., 2003), remains to be investigated further. The similarities within the delineated Flavobacterium groups are generally very high for the 16S rRNA gene sequences (Table 3). The gyrB sequences were mostly also very similar within groups and ranged from 97.2% to 100% (Table 3). In Flavobacterium sp. 2, sp. 8 and sp. 13 (Figs 2 and S2) subclusters

were observed with 97.2–99.0% sequence similarity. In other genera, comparable high intraspecies gyrB gene sequence similarities were observed, for example 98.5–100%gyrB gene sequence similarity within the genus Streptomyces (Actinobacteria) (Hatano et al., 2003), 97.4–100% within the genus Aeromonas Buspirone HCl (Gammaproteobacteria) (Yanez et al., 2003), 95.0–100% within the genus Bacillus (Firmicutes) (Wang et al., 2007) and 94.6–100% within the genus Helicobacter (Epsilonproteobacteria) (Hannula & Hanninen, 2007). It should be noted that all Flavobacterium groups studied here comprised several rep-types (Peeters et al., submitted) and the strains were chosen to represent this diversity. The topologies of the neighbour-joining and the maximum likelihood dendrogram were slightly different for the 16S rRNA gene compared with the gyrB gene (Figs 1, 2, S1 and S2), as has also been observed for other groups (Yamamoto & Harayama, 1996). However, overall, the phylogenies of the 16S rRNA (Figs 1 and S1) and gyrB (Figs 2 and S2) gene were similar and confirmed the division of the Antarctic strains into 15 groups, one probably belonging to F. micromati and one close to F. gelidilacus.