Magnetotactic bacteria make magnetosomes (small membrane-encapsulated magnetites with 30-50nm diameter) in the cells, and swim along the external magnetic field. They are found in both fresh water and seawater sediments, and have various cell shapes such as vibrio, cocci, and spillum. On the other hand, sulfate-reducing bacteria such as those of the genus Desulfovibrio are known to be gram-negative, obligately anaerobic bacteria. They produce hydrogen sulfide by the reduction of sulfate and other oxidized sulfur compounds along with the oxidation of organic compounds, thus playing an important role in the sulfur cycle.
Desulfovibrio magneticus RS-1 (= NBRC 104933) is so far the only magnetotactic bacterium isolated from the group of sulfate-reducing bacteria belonging to delta-proteobacteria, while most of the other characterized magnetotactic bacteria belong to alpha-proteobacteria. It was isolated from the sediment of a waterway near the Kameno river in the Wakayama prefecture.
Genome analysis revealed that the genome of Desulfovibrio magneticus RS-1 consists of a circular chromsome (5,248,049bp) and two circular plasmids (pDMC1: 58,704bp, pDMC2: 8,867bp). Detailed comparison with other sequenced genomes of magnetotactic bacteria, which all belong to alpha-proteobacteria, will elucidate the molecular and evolutionary mechanisms of magnetosome synthesis. The genomic data may also facilitate the utilization of this bacterium in various fields of biotechnology such as the production of industrially useful magnetic materials and the exploitation of the characteristics of sulfate-reducing bacteria in bioremediation.