Microbe Produces Ethanol from Switchgrass Without Pretreatment

Genetic engineering allows biomass-degrading bacterium to make fuel in a single process

The Science

The conventional strategy for producing ethanol from plant biomass requires costly pretreatment and enzyme-driven reactions. Refining another strategy known as consolidated bioprocessing (CPB) could reduce costs. In second-generation CPB, a microorganism splits of water and ferments the products to ethanol, reducing the cost. Now, scientists engineered a strain of a CBP bacterium calledCaldicellulosiruptor bescii that efficiently breaks down biomass without pretreatment. The microbe produces ethanol, demonstrating the successful conversion of switchgrass cellulosic biomass.

The Impact

Direct conversion of biomass to ethanol without pretreatment represents a new paradigm for CPB, offering the potential for carbon-neutral, cost-effective, and sustainable biofuel production.

Summary

Producing ethanol from plant biomass typically requires three major steps: physicochemical pretreatment, enzymatic breakdown of biomass into its constituent sugars, and fermentation. Pretreatment and enzymatic hydrolysis are costly steps in the process. CBP could reduce costs. In CBP, unpretreated cellulosic biomass is converted to a biofuel in a single process by a microbe that breaks down the biomass and ferments the resulting sugars.Caldicellulosiruptor bescii had been shown to ferment untreated switchgrass, but it lacked the genes to make ethanol.

Read more: Microbe Produces Ethanol from Switchgrass Without Pretreatment