Researchers designed synthetic anaerobic bacteria to capture and convert methane

According to the U.
S.
Environmental Protection Agency, methane is a powerful greenhouse gas that damages 25 times
more damage to the environment per molecule than carbon dioxide.
Bacteria on the seafloor can remove methane from the surrounding environment in the complete absence of oxygen through a process called anaerobic methane
oxidation (AMO).
Researchers at Penn State and the University of Arizona will use a four-year, $3.
2 million grant from the National Science Foundation (NSF) to design a biotechnology foundation that uses synthetic versions of these bacteria in a system to capture and convert methane
from its source.

Thomas Wood, professor of chemical engineering at the Pennsylvania State College of Engineering, and Ingmar H.
Riedel-Kruse, associate professor of molecular, cell biology and biomedical engineering at the University of Arizona, have joined forces to create scalable bioreactors that harness methane before it
escapes into the atmosphere as a harmful greenhouse gas.
Wood's lab cloned enzymes
found on the seafloor that capture methane-trapping microbes.
The enzyme will be used to build on
Riedel-Kruse's previous success in engineering synthesis consortiums.

"These methane-absorbing bacteria are anaerobic bacteria," Wood said
.
"Even though they grow very slowly — doubling every 100 years — they capture methane gas very effectively
.
We can't grow them individually in the lab, but we've been able to clone their DNA
.
”

Wood said the main goal of the project is to add engineered bacteria to reactors that are practical and economical enough to make methane a resource rather than a pollutant
.

"These small, remote bioreactors will be used to capture methane at its sources — hydraulic fracturing sites, landfills and wastewater treatment plants — and immediately convert it into electricity or valuable base chemicals that can be used in other compounds such as alcohol, plastics and automotive fuel
," Wood said.
The anaerobic nature of bacteria is key
.
To replicate the process by which these bacteria ferment methane, the researchers had to create an oxygen-free region
.
They will use a biofilm — mucus — to control the spatial arrangement
of bacteria in the reactor.

"We're going to create space-defining balls
that are mostly made up of slime," Wood said.

The outer area of the mucus removes oxygen, allowing the anaerobic cells inside to capture methane and convert it into intermediate chemicals
.
The outer aerobic cells also convert the intermediate compounds into the final product
.

"The modular, easily scalable bioreactor provides a practical process that can be operated in
many different places," Wood said.
"It will be more efficient, more distributable and cheaper
than current methods of capturing and converting methane.
" We don't yet know what the process at a fracking site will look like, but at the municipal level, it's easy to see where we're headed next: stationary biofilm reactors
.
”

Existing refineries, such as those used by the fracking industry, convert methane into gasoline-like compounds, but cost tens of billions of dollars
to build.
Transporting methane from remote areas to these refineries is inefficient, with up to 20 percent of methane lost to the
atmosphere during transportation from source to refinery, Wood said.

"We want to stop releasing methane and start using it instead of burning it
," Wood said.
"Our simple bioreactor runs stationary at
room temperature.
You don't need to spend $20 billion and a lot of energy to capture methane and turn it into something
useful.
”

The researchers have assembled an interdisciplinary team that includes expertise in synthetic biology, chemically engineered bioreactor design, and social sciences, as well as potential future users
of new technologies.
The bioreactor will be tested at the relevant site, starting with a wastewater treatment facility
.

In addition to developing a new way to convert methane into chemicals, Riedel-Kruse said, researchers will also look at how to spread the technology
in a socially and environmentally responsible way.
The National Science Foundation has added $300,000 to researchers to increase their educational component
.