Diversity and ecology of and biomineralization by magnetotactic bacteria

Magnetotactic bacteria (MTB) biomineralize intracellular, membrane-bounded crystals of magnetite (Fe₃ O₄ ) and/or greigite (Fe₃ S₄ ) called magnetosomes. MTB play important roles in the geochemical cycling of iron, sulfur, nitrogen and carbon. Significantly, they also represent an intriguing model system not just for the study of microbial biomineralization but also for magnetoreception, prokaryotic organelle formation and microbial biogeography. Here we review current knowledge on the ecology of and biomineralization by MTB, with an emphasis on more recent reports of unexpected ecological and phylogenetic findings regarding MTB. In this study, we conducted a search of public metagenomic databases and identified six novel magnetosome gene cluster-containing genomic fragments affiliated with the Deltaproteobacteria and Gammaproteobacteria classes of the Proteobacteria phylum, the Nitrospirae phylum and the Planctomycetes phylum from the deep subseafloor, marine oxygen minimum zone, groundwater biofilm and estuary sediment, thereby extending our knowledge on the diversity and distribution of MTB as well deriving important information as to their ecophysiology. We point out that the increasing availability of sequence data will facilitate researchers to systematically explore the ecology and biomineralization of MTB even further.