The Genus Magnetospirillum gen. nov. Description of Magnetospirillum gryphiswaldense sp. nov. and Transfer of Aquaspirillum magnetotacticum to Magnetospirillum magnetotacticum comb. nov.

A magnetotactic spirillum (strain MSR-1) was isolated from the mud of the eutrophic river Ryck near Greifswald. Its morphological, ultrastructural and biochemical characteristics were compared with those of Aquaspirillum magnetotacticum. A cell suspension of strain MSR-1 was used to amplify in vitro 16S rRNA genes (rDNA). The amplified 16S rDNA was cloned and sequenced. For comparison 16S rDNA was also directly amplified from a stock culture of Aquaspirillum magnetotacticum DSM 3856^T. It was cloned, sequenced and compared with the 16S rDNA sequences of strain MSR-1 and other bacteria. An oligonucleotide probe complementary to a 16S rRNA region unique to the two magnetic spirilla was synthesized. Specific hybridization of the fluorescent oligonucleotide to whole cells of both strains demonstrated that the 16S rDNA clones originated from strain MSR-1 and A. magnetotacticum. Aquaspirillum magnetotacticum and strain MSR-1 are related and belong to the alpha subclass of Proteobacteria, whereas Aquaspirillum serpens, the type species of the genus Aquaspirillum, is a member of the beta subclass of Proteobacteria. A new genus Magnetospirillum sp. gen. with the type species Magnetospirillum gryphiswaldense sp. nov., and the transfer of A. magnetotacticum to Magnetospirillum magnetotacticum comb. nov. are proposed. The type strain of M. gryphiswaldense is DSM 6361.