Here’s some cool work out of Pacific Northwest National Laboratory. Scientists from the group of Dr. Thomas Squier isolated membrane electron transport protein from metal-reducing soil bacterium Shewanella oneidensis, and used the large quantity of these proteins to beget light!
Reporting in the current advance online edition of the Journal of the American Chemical Society, they suggest that proteins rendered portable from the organisms that spawned them could make miniature bioreactor cells feasible…
The feat is the bacterial equivalent of removing lungs and coaxing the disembodied tissue to breathe.
Squier and principal authors Yijia Xiong and Liang Shi, PNNL staff scientists, discovered that the proteins, outer membrane c-type cytochrome A, or OmcA, formed a dense coating on the iron-rich mineral hematite. The metal in the mineral acts as an “acceptor,” or dumping point, for thousands of trillions of electrons per square centimeter shuttled by the OmcA-donor. The function is a relic of respiration, in which the cell depends on the protein to dump electrons to maintain a steady flow of energy and prevent the organism-damaging accumulation of electrons…
The researchers supplied the protein with energy–directly as electrons or in the form of a natural cellular fuel called NADH–and only during binding detected charge-transfer from protein to mineral, through a combination of techniques that included FCS, or fluorescent correlation spectroscopy, and confocal microscopy. These yielded a “fluorescence intensity trace” whose brightness depended entirely on whether hematite was available to bind with OmcA in solution. No hematite, dim; hematite, bright.
“The peak current, or flux, doesn’t run long, just a few seconds,” Squier said, “but flux is at least as good as what you would find in the most efficient bioreactors, which rely on living bacteria…”
Using pure protein opens up the possibility of shrinking biofuel cells to power small electronic devices, Squier said.
Imagine pacemakers that do not require battery changes or pump-free penile implants! Now you hear us.