Kolinko, I. et al. Nat. Nanotechnol. 9, 193–197 (2014).

The synthesis of magnetic nanoparticles, which are important for various applications in biology and medicine, can be challenging. So why not conscript a microorganism to do the job? The magnetotactic bacterium Magnetospirillum gryphiswaldense produces uniformly sized magnetite nanocrystals, but cultivating this and other magnetotactic microbes in the laboratory is a challenge. Kolinko et al. took 29 genes that they identified as responsible for magnetosome synthesis in M. gryphiswaldense, stitched expression cassettes comprising these genes together using recombineering, and transferred the expression cassettes to an easy-to-handle, photosynthetic, nonmagnetic host, Rhodospirillum rubrum. With some optimizations, they achieved successful magnetosome synthesis, demonstrating a potential tool for sustainable production of magnetic nanoparticles.