|An engineered Escherichia coli strain (yellow) attaches to solid iron oxide (black). Scientists at the Molecular Foundry took the first step toward electronically interfacing microbes with inorganic materials, without disrupting cell viability. Credit: Image courtesy of Heather Jensen|
The Terminator. The Borg. The Six Million Dollar Man. Science fiction is ripe with biological beings armed with artificial capabilities. In reality, however, the clunky connections between living and non-living worlds often lack a clear channel for communication. Now, scientists with the Lawrence Berkeley National Laboratory (Berkeley Lab) have designed an electrical link to living cells engineered to shuttle electrons across a cell's membrane to an external acceptor along a well-defined path. This direct channel could yield cells that can read and respond to electronic signals, electronics capable of self-replication and repair, or efficiently transfer sunlight into electricity.
"Melding the living and non-living worlds is a canonical image in science fiction," said Caroline Ajo-Franklin, a staff scientist in the Biological Nanostructures Facility at Berkeley Lab's Molecular Foundry. "However, in most attempts to interface living and non-living systems, you poke cells with a sharp hard object, and the cells respond in a predictable way – they die. Yet, in Nature many organisms have evolved to interact with the rocks and minerals that are part of their environment. Here, we took inspiration from Nature's approach and actually grew the connections out of the cell."
"We were interested in finding a pathway that wouldn't kill the living systems we were studying," said Heather Jensen, a graduate student at University of California, Berkeley whose thesis work is part of this publication. "By using a living system in electronics, we can one day create biotechnologies that can repair and self-replicate."
…"This recent breakthrough is part of a larger Department of Energy project on domesticating life at the cellular and molecular level. By directly interfacing synthetic devices with living organisms, we can harness the vast capabilities of life in photo- and chemical energy conversion, chemical synthesis, and self-assembly and repair," said Jay Groves, a faculty scientist at Berkeley Labs and professor of chemistry at University of California, Berkeley.
The researchers plan to implement this genetic cassette in photosynthetic bacteria, as cellular electrons from these bacteria can be produced from sunlight—providing cheap, self-replicating solar batteries. These metal-reducing bacteria could also assist in producing pharmaceutical drugs, Ajo-Franklin adds, as the fermentation step in drug manufacturing requires energy-intensive pumping of oxygen. In contrast, these engineered bacteria breathe using rust, rather than oxygen, saving energy.