Taxonomic and phylogenetic studies on a new taxon of budding, hyphal Proteobacteria, Hirschia baltica gen. nov., sp. nov.

Four strains of budding, hyphal bacteria, which had very similar chemotaxonomic properties, were isolated from the Baltic Sea. The results of DNA-DNA hybridization experiments, indicated that three of the new isolates were closely related, while the fourth was only moderately related to the other three. Sequence signature and higher-order structural detail analyses of the 16S rRNA of strain IFAM 1418T (T = type strain) indicated that this isolate is related to the alpha subclass of the class Proteobacteria. Although our isolates resemble members of the genera Hyphomicrobium and Hyphomonas in morphology, assignment to either of these genera was excluded on the basis of their markedly lower DNA guanine-plus-cytosine contents. We propose that these organisms should be placed in a new genus, Hirschia baltica is the type species of this genus, and the type strain of H. baltica is strain IFAM 1418 (= DSM 5838).