Electricity-eating microbes could make bioplastics

Scientists have figured out a way to feed electricity to microbes to grow truly green, biodegradable bioplastics, according to a new study.

The research comes from the idea that engineers can use electricity harvested from the sun or wind interchangeably with power from coal or petroleum sources. Or they can turn sustainably produced electricity into something physical and useful.

“As our planet grapples with rampant, petroleum-based plastic use and plastic waste, finding sustainable ways to make bioplastics is becoming more and more important,” says Arpita Bose, assistant professor of biology at Washington University in St. Louis. “We have to find new solutions.”

Renewable energy currently accounts for about 11 percent of total US energy consumption and about 17 percent of electricity generation.

One of the main issues with renewable electricity is energy storage—how to collect power generated during the sunny and windy hours, and hold it for when it is dark and still. Bioplastics are a good use for that “extra” power from intermittent sources, Bose suggests—as an alternative to battery storage, and instead of using that energy to make a different type of fuel.

Bose’s laboratory is among the first to use microbial electrosynthesis to wrangle a polymer called polyhydroxybutyrate (PHB) from electricity-eating microbes. The plastic they are making is “sustainable, carbon-neutral, and low-cost,” Bose says.

“One of the major challenges in bioplastic production is the substrate input, which affects cost,” says first author Tahina Ranaivoarisoa, a research technician in the Bose laboratory.

“A versatile bacterium such as R. palustris TIE-1—which can effectively use just carbon dioxide, light, and electrons from electricity or iron for bioplastic production—broadens the substrates that could be used in bioplastic production.”

In a related paper in Bioelectrochemistry, Bose’s research team illustrates how TIE-1 interacts with various forms of iron while also using electricity as a source of electrons. The researchers manually coating electrodes that the microbes used with a special kind of rust to improve production rates for PHB, which increased their electricity uptake.

Bose believes that microbially derived bioplastics have a future role to play in space, where astronauts could use 3D printer technology to manufacture their own tools instead of transporting everything ready-made from Earth.

“Our observations open new doors for sustainable bioplastic production not only in resource-limited environments on Earth, but also during space exploration and for in situ resource utilization on other planets,” Bose says.

The Department of Energy, the Department of Defense, the Army Research Office, and the David and Lucile Packard Foundation funded the work, which appears in the Journal of Industrial Microbiology and Biotechnology.

Source: Washington University in St. Louis