Magnetospirillum magneticum. A magnetotactic bacterium that could be the basis of growing computer memory organically. Image Source: Eff Yeah Microbiology!
The way computers become biological begins with expanded memory. The Economist reports that nanotechnologists have found a way to grow computer memories, thereby mimicking biological memories in cells, by manipulating tiny magnetic elements transmitted by proteins.
See the original research here.[T]here may be a cheaper option [for manufacturing tiny computer memory components]—namely to mimic Mother Nature, who has been building tiny devices, in the form of living cells and their components, for billions of years, and has thus got rather good at it. A paper published in Small, a nanotechnology journal, sets out the latest example of the technique. In it, a group of researchers led by Sarah Staniland at the University of Leeds, in Britain, describe using naturally occurring proteins to make arrays of tiny magnets, similar to those employed to store information in disk drives.
The researchers took their inspiration from Magnetospirillum magneticum, a bacterium that is sensitive to the Earth’s magnetic field thanks to the presence within its cells of flecks of magnetite, a form of iron oxide. Previous work has isolated the protein that makes these miniature compasses. Using genetic engineering, the team managed to persuade a different bacterium—Escherichia coli, a ubiquitous critter that is a workhorse of biotechnology—to manufacture this protein in bulk.
Next, they imprinted a block of gold with a microscopic chessboard pattern of chemicals. Half the squares contained anchoring points for the protein. The other half were left untreated as controls. They then dipped the gold into a solution containing the protein, allowing it to bind to the treated squares, and dunked the whole lot into a heated solution of iron salts. After that, they examined the results with an electron microscope. Sure enough, groups of magnetite grains had materialised on the treated squares, shepherded into place by the bacterial protein. In principle, each of these magnetic domains could store the “one” or the “zero” of a bit of information, according to how it was polarised.