In a study published online March 6 in the journal Nature Biotechnology, researchers at the UCLA Henry Samueli School of Engineering and Applied Science demonstrate for the first time the feasibility of using proteins — one of the most abundant biomolecules on earth — as a significant raw material for biorefining and biofuel production.
"Proteins had been completely ignored as a potential biomaterial because they've been thought of mainly as food. But in fact, there are a lot of different proteins that cannot be used as food," said James C. Liao, the Chancellor's Professor of Chemical and Biomolecular Engineering at UCLA and senior author of the study. "These proteins were overlooked as a resource for fuel or for chemicals because people did not know how to utilize them or how to grow them. We've solved these problems."
"This research is the first attempt to utilize protein as a carbon source for energy production and biorefining," said Kwang Myung Cho, a UCLA Engineering research scientist and an author of the study. "To utilize protein as a carbon source, complex cellular regulation in nitrogen metabolism had to be rewired. This study clearly showed how to engineer microbial cells to control their cellular nitrogen metabolism."
In nutrient-rich conditions, proteins are the most abundant component in fast-growing microorganisms. The accumulation rate of proteins is faster than that of any other raw materials, including cellulose or lipids. In addition, protein does not have the recalcitrance problems of lignocellulose or the de-watering problem of algal lipids. Protein biomass can be much more easily digested to be used for microorganisms than cellulosic biomass, which is very difficult to break down.
Further, cellulose and lipids don't contribute to the process of photosynthesis. But proteins are the major component of fast-growing photosynthetic microorganisms.
The challenge in protein-based biorefining, the researchers say, lies in the difficulties of effectively converting protein hydrolysates to fuels and chemicals.
"Microorganisms tend to use proteins to build their own proteins instead of converting them to other compounds," said Yi-xin Huo, a UCLA postdoctoral researcher and lead author of the study. "So to achieve the protein-based biorefining, we have to completely redirect the protein utilization system, which is one of the most highly regulated systems in the cell."
Liao's team created an artificial metabolic system to dump reduced nitrogen out of cells and tricked the cells to degrade proteins without utilizing them for growth. Proteins contain both ammonia and carbon; Liao's team took away the ammonia and recycled it back for the growth of the algae they worked with. Algae with rich ammonia fertilizers grow quickly and were used only as a carrier to assimilate carbon dioxide and produce protein, which results in more CO2 fixation and growth. With this strategy, expensive photo-bioreactors can be eliminated.
"Today, nitrogen fertilizers used in agriculture and biofuel production have become a major threat to many of the world's ecosystems, and the nitrogen-containing residuals in biofuel production can eventually turn into nitrous oxide, which is about 300 times worse than CO2 as a greenhouse gas," Liao said. "Our strategy effectively recycles nitrogen back to the biofuel production process, thus approaching nitrogen neutrality.
"Growing algae to produce protein is like putting the interest back into the principal," he said.
According to Liao's team, the culture area needed to produce 60 billion gallons of biofuels (30 percent of the United States' current transportation fuel) based on the new technology could be as little as 24,600 square kilometers — equivalent to 1.9 percent of the agricultural land in the U.S.
"Developing large-scale systems is our next step," Huo said. "Harvesting of the protein biomass economically is a bottleneck of advancing our technology."
The research was partially supported by the UCLA–Department of Energy Institute for Genomics and Proteomics.
The UCLA Henry Samueli School of Engineering and Applied Science, established in 1945, offers 28 academic and professional degree programs and has an enrollment of almost 5,000 students. The school's distinguished faculty are leading research to address many of the critical challenges of the 21st century, including renewable energy, clean water, health care, wireless sensing and networking, and cybersecurity. Ranked among the top 10 engineering schools at public universities nationwide, the school is home to seven multimillion-dollar interdisciplinary research centers in wireless sensor systems, nanoelectronics, nanomedicine, renewable energy, customized computing, and the smart grid, all funded by federal and private agencies.
For more news, visit the UCLA Newsroom and follow us on Twitter.
Wileen Wong Kromhout | EurekAlert!
New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego
Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Ecology, The Environment and Conservation
17.01.2018 | Physics and Astronomy
17.01.2018 | Awards Funding