Morphological and Phylogenetic Diversity of Magnetotactic Bacteria in Pond Lianhua,~Beijing

Magnetotactic bacteria (MTB) biomineralize intracellular magnetite (Fe3O4) and/or greigite (Fe3S4) magnetosomes. They are widely distributed in aquatic environments and play important roles in the biogeochemical cycles of Fe, S, C, N and P. Due to their difficulty of cultivation our knowledge on the diversity and environmental function of MTB remains very limited. Here, we have characterized a group of uncultivated MTB from Pond Lianhua in Beijing, China. Light and scanning electron microscopy shows coccoid and vibrioid in cell morphologies. Transmission electron microscopy and energy dispersive spectroscopy indicate that the mineral phase of magnetosomes is magnetite and that some cells of MTB contain large amount of intracellular sulfur and magnesium. 16S rRNA gene-based cultivation-independent analysis has identified seven operational taxonomic units (OTUs) belonging to the Alphaproteobacteria and Gammaproteobacteria in the Proteobacteria phylum. Taken together, our results highlight a high diversity of MTB in environment that may contribute to the geochemical cycling of iron and other~elements.