A Magnetospirillum strain WM-1 from a freshwater sediment with intracellular magnetosomes

A helical shaped bacterium capable of producing magnetosomes, designated WM-1, was isolated from freshwater sediment through an improved isolated method that combined magnetic separation and the race track method. The strain WM-1 was Gram-negative, 0.2-0.4 mu m in diameter and 3-4 mu m in length. The strain WM-1 was identified as genus Magnetospirillum in the alpha-Proteobacteria according to the sequence analysis of the 16S rDNA, the morphology and physiological characteristics. The shape of the magnetosomes in WM-1was cuboidal by electron microscopy. Statistical analysis of WM-1 magnetosome crystals showed that the average number of magnetosomes in a WM-1 bacterium was 8 +/- 3.4, and the average length was 54 +/- 12.3 nm, and the average width was 43 +/- 10.9 nm.