When we think about biorefining and biofuel production, the two types of raw materials that strikes our mind are carbohydrates and lipids. Biofuels like ethanol are derived from carbohydrate raw materials such as sugars and lignocellulose, while biodiesel is derived from lipids.

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. These proteins were overlooked as a resource for fuel or for chemicals because no one knew how to utilize them. Researchers at the UCLA Henry Samueli School of Engineering and Applied Science demonstrated the feasibility of using proteins—one of the most abundant biomolecules on earth—as a significant raw material for biorefining and biofuel production.

Protein is comprised of carbon and ammonia. Ammonia is primarily nitrogen, and the reason to incorporate so much nitrogen in system to make biomass is to facilitate the algae to make proteins. In order to utilize protein as a carbon source, complex cellular regulation in nitrogen metabolism had to be re organized. The researchers have been successful in engineering microbial cells to control their cellular nitrogen metabolism. In this case, the researchers developed a new pathway that makes a protein, then robs the ammonia and recycles the nitrogen back to make more protein. Leaving the carbon to be captured for biofuels and chemicals – and thereby creating a system which is, to an extent, nitrogen neutral.

In the world of microalgal production, a lipid content of 25 percent is considered a fair number for a strain that is accumulating biomass at the rate of, 25 grams per square meter per day. With carbohydrate making up some 10%, a lion’s share of 65% is nothing but just protein content. To date, almost every algae biofuels developer propose to use the high-value of the proteins as animal feed. For every million gallons of algal based biofuels made from algal oil, there would be more than 8 million tons of algal protein under disposal. Unless there is an equally strong demand, these proteins are just going to go unutilized. In such a scenario, this latest breakthrough innovation could very well alter the dynamics of the industry. The approach however, is at the proof of concept stage, since harvesting the protein biomass in an economically viable manner is a subject for future research.