Bioengineering and Biotechnological Applications of Bacterial Magnetic Particles

Abstract

Magnetotactic bacteria synthesize nano-sized magnetic particles in the cells. The bacterial magnetic particles have a core of magnetite (Fe3O4) and are surrounded by a lipid bilayer membrane containing a number of proteins, referred to as magnetosome. Since the bioengineering methodology for magnetotactic bacteria was established, expression of a wide range of functional proteins onto magnetic particles has successfully been performed in which the native proteins in the lipid membrane can serve as anchors for the protein display. The expression system, here we call “magnetosome-display system,” has enabled us to reduce the cost of production of protein-magnetic particle complexes. These advantages lead to creation of a variety of magnetic particles displaying functional proteins, including membrane proteins and disulfide-bonded proteins, which the basic approach cannot match. This review provides an overview of the developmental status of magnetic particles in the field of bioassays, summarizes magnetosome display system by magnetotactic bacteria, and discusses their usefulness and prospects in the medical and environmental fields. The novel system has shown considerable promise for improving the display efficiency of the difficult-to-express proteins and thus is expected to contribute to further development of functional magnetic particles toward biotechnological applications.