NREL researchers develop cellulosic biofuels from CO2 with metabolic pathway

In Colorado, scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory made the surprise discovery that a metabolic pathway to take up CO₂ exists and functions in a microorganism capable of breaking down and fermenting cellulosic biomass to produce biofuels including hydrogen and hydrocarbons.

Clostridium thermocellum is among the most efficient bacteria in directly converting cellulosic materials into hydrogen and hydrocarbons biofuels. Most bacteria feeding upon organic carbon compounds, such as glucose or xylose, release CO₂ as a waste byproduct, decreasing the maximum amount of products the microorganism can produce per carbon atom measured as carbon efficiency.

Other scientists have found the addition of a form of CO₂, known as bicarbonate, into the medium containing the bacterium actually promotes the growth of C. thermocellum, yet its mechanistic details remained a puzzle. This enhanced growth implied the bacterium had the ability to use CO₂ and prompted NREL researchers to investigate the phenomena enhancing the bacterium’s growth.