Running on Microbes
“If it works, it’s really transformative. It changes the whole way you can go about making biofuels and commodities.”
Just as plants undergo photosynthesis, various bacteria use water and carbon dioxide to release oxygen and organic compounds. While plants get their energy from sunlight, these bacteria have evolved to obtain energy from decomposing plants in sediments and soils.
“They use carbon dioxide the same way we use oxygen,” Lovley explains.
In keeping with global efforts to reduce carbon dioxide emissions, the mastering of such a microbial process could have monumental impacts. To add to this utility, Lovley and his team are genetically modifying various bacteria so that different organic compounds can be created from the microbial electrosynthesis that each organism undergoes. The team has successfully engineered a strain of clostridium, bacteria found in sediment, that takes in carbon dioxide and water to produce butanol.
“We really had to start from scratch working on the basic biology to accomplish that,” Lovley says.
Lovley says that microbial electrosynthesis is vastly more efficient than existing technologies. Whereas biomass technologies require large quantities of water and agricultural land in order to grow plants for fuel conversion, microbial electrosynthesis is a compact process that requires very little material and effort. The bacteria happily attach to an electrode and directly produce the fuel molecule, which they excrete from the cell naturally with no need for extraction or conversion.
To power the bacteria, a solar panel is set up beside a body of water to harness light energy. The panel is then hooked to an electrode that is immersed in the water. The bacteria, naturally attracted to the metallic electrode, begin to latch on and microbial electrosynthesis begins. The process is versatile and the energy source does not have to be solar. Wind energy, hydrothermal energy and even traditional electricity can be used to power the microbes. As long as the bacteria are fed electricity, microbial electrosynthesis will take place.
“Our system can basically plug into whatever anyone else develops,” Lovley says.
Lovley and the research team have proven that microbial electrosynthesis works and now they are tasked by the Department of Energy to bring the model up-to-scale. The team has found that the bacteria grow more quickly and therefore reproduce more rapidly when acetic acid is dripped into their water source—one step in the right direction. The next phase of the project will involve a reactor thousands of meters in size to test how much fuel can be produced by these microorganisms.
“If it works, it’s really transformative. It changes the whole way you can go about making biofuels and commodities,” Lovley says.
Microbial electrosynthesis adds to the growing list of breakthrough technological applications borne of Lovley’s 1987 discovery of geobacter. He found that the bacteria can transport electrons to metals—a process which is now used in a host of applications, including the latest bioremediation techniques. In polluted rivers and streams, geobacter naturally seeks out and latches onto heavy metals such as uranium. It then transfers electrons onto the metal, oxidizing it. The metal turns insoluble and precipitates to the surface of the water to be skimmed out. Geobacter serves a similar function in removing petroleum contaminants and radioactive metals from hazardous waste sites across the country. Simply by supplying the bacterial population with acetic acid, the metals are rapidly oxidized and the contamination is removed.
The Department of Energy has been supportive of Lovley’s research for years, and now the Office of Naval Research (ONR) is showing interest in some of Lovley’s latest work. With funding from the ONR, Lovley and the team are studying the processes by which bacteria convert organic waste into methane gas.
“The microbial communities that are making the methane gas are using these direct electrical connections—well that changes the way people [have] thought those systems work for about 40 years,” Lovley says.
In their new work, the team is uncovering a vast network of electrical connectivity, which Lovley refers to as “bioelectronics.” Bacterial cells grow filaments, which turn out to have a metallic-like conductivity. These biological proteins actually function like wires that bacteria use to communicate with each other. Lovley says there are many practical applications for these electrical networks; mastering these connections could enable underwater devices to be powered through biological nanowires that are harnessing the electricity naturally present in underwater sediments.
“It’s really prevalent in the naturally world. I think life is a lot more electrically connected than we thought,” Lovley says.
Over the past decade, the Geobacter Project has drawn upwards of $100 million in external funding to the UMass Amherst campus and Lovley’s 50-person lab continues to attract national attention. His initial discovery revolutionized hazardous cleanup and unfolded immeasurable potential in the fields of microbial electrosynthesis and bioelectronics. The federal government is watching closely as the team sets out on the next two-year phase of the project with an additional $7 million. The results, put simply, could be huge.
Karen J. Hayes '85