Limnohabitans curvus gen. nov., sp. nov., a planktonic bacterium isolated from a freshwater lake

Abstract

A chemo-organotrophic, aerobic, facultatively anaerobic, non-motile strain, MWH-C5T, isolated from the water column of the oligomesotrophic Lake Mondsee (Austria), was characterized phenotypically, phylogenetically and chemotaxonomically. The predominant fatty acids of the strain were C16 : 1 ω7c/ω6c, C16 : 0, C12 : 1 and C8 : 0-3OH, the major quinone was ubiquinone Q-8 and the G+C content of the DNA of the strain was 55.5 mol%. 16S rRNA gene similarity to the closest related type strains was 96.6 % (Curvibacter delicatus LMG 4328T) and 95.7 % (Rhodoferax fermentans FR3T). Phylogenetic analysis of 16S rRNA gene sequences revealed the affiliation of the strain with the family Comamonadaceae (Betaproteobacteria); however, the phylogenetic position of the strain did not support an affiliation to any previously described genus within this family. A family-wide comparison of traits revealed that the strain possesses a unique combination of DNA G+C content, major fatty acids and major 3-hydroxy fatty acid. Furthermore, the strain differs in several traits from the closest related genera. Based on the phylogeny of the strain and differences from closely related genera, we propose to establish the new genus and species Limnohabitans curvus gen. nov., sp. nov. to accommodate this strain. The type strain of Limnohabitans curvus is MWH-C5T (=DSM 21645T =CCUG 56720T). The type strain is closely related to a large number of uncultured bacteria detected by cultivation-independent methods in various freshwater systems.