Researchers Discover the Ability of Clostridium thermocellum to Consume both Cellulosic Materials for Biofuel Production

Researchers from 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.

Clostridium thermocellum directly converts cellulosic materials into biofuels and release CO₂ as a byproduct, decreasing the maximum amount of products the microorganism can produce. The scientists found the addition of a form of CO₂, known as bicarbonate, into the bacteria medium promotes the growth of C. thermocellum. This enhanced growth implies the bacterium can consume CO₂.

The researchers tracked how CO₂ enters the cell, and identified the enzymes critical to CO₂ fixation, and how it is incorporated into products thereby discovering a new metabolic route unknown to the scientific community. The pathway enables the bacterium to use both CO₂ and organic carbons during its growth.

These findings pave the way to future engineering of this bacterium to consume cellulose and CO₂ simultaneously to improve carbon yield.