Two types of raw materials are currently used for biorefining and biofuel production: carbohydrates and lipids. Biofuels like ethanol are derived from carbohydrate raw materials such as sugars and lignocellulose, while biodiesels are derived from another raw material, lipid-rich vegetable oil.
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.