Existing technology to produce ethanol from cellulosic sources involves a multistep process: plant material such as paper pulp and switchgrass are first pretreated, to separate cellulose from the rest of the plant matter. Cellulose is then mixed with enzymes that break it down into sugars. Yeast then takes over to ferment the sugars into ethanol.
As a less costly alternative, Mascoma researchers are engineering microbes to combine the last two steps of the process: breaking down cellulose, and converting sugars into ethanol. They say that if they can get microorganisms to make ethanol at sufficiently high rates, they can reduce the amount of expensive enzymes needed to break down cellulose, which can normally take up half of ethanol's production costs.
In experiments with paper sludge, the engineered yeast broke down and converted 85 percent of cellulose into sugars and produced ethanol without the help of added enzymes.
"There's still optimization for these microbes that remain, and we want to improve their cellulolytic performance, and the rate at which they hydrolize sugars, which speeds up the overall production process," says Jim Flatt, the Mascoma's executive vice president of research and development. "They perform, they're reliable, but we can improve them further, and that's what we intend to do."
The company has begun to test all three engineered microbes at a pilot plant in Rome, NY, and it plans to have a commercial scale-up by 2010.
Mascoma Corporation today announced that the company has made major research advances in consolidated bioprocessing, or CBP, a low-cost processing strategy for production of biofuels from cellulosic biomass. CBP avoids the need for the costly production of cellulase enzymes by using engineered microorganisms that produce cellulases and ethanol at high yield in a single step.
"This is a true breakthrough that takes us much, much closer to billions of gallons of low cost cellulosic biofuels," said Michigan State University's Dr. Bruce Dale, who is also Editor of the journal Biofuels, Bioproducts and Biorefineries. "Many had thought that CBP was years or even decades away, but the future just arrived. Mascoma has permanently changed the biofuels landscape from here on."
Consolidated bioprocessing, or CBP, harnesses the power of nature’s best cellulose utilizing and ethanol fermenting microbes and allows nature to do the majority of the work resulting in a simpler process consisting of a mild pretreatment followed by the introduction of microbes that both hydrolyze and ferment the sugars into ethanol;
-- Production of nearly 6% wt/vol ethanol by an engineered thermophilie, an increase of 60% over what was reported just a year ago;
-- The first report of targeted metabolic engineering of a cellulose-fermenting thermophile, Clostridium thermocellum, leading to a reduced production of unwanted organic acid byproducts; and
-- Selected strains of C. thermocellum that can rapidly consume cellulose with high conversion and no added cellulase, and grow on cellulose in the presence of commercial levels of ethanol.
Recombinant, Cellulolytic Yeast
-- 3,000-fold increase in cellulase expression;
-- A significant 2.5-fold reduction in the added cellulase required for conversion of pretreated hardwood to ethanol; and
-- Complete elimination of added cellulase for conversion of waste paper sludge to ethanol.
In February 2009, Mascoma announced that its pilot facility in Rome, NY had begun producing cellulosic ethanol. The demonstration facility, which was constructed with the generous support from the State of New York through the NYS Department of Agriculture & Markets and the New York State Energy Research and Development Authority, has the flexibility to run on numerous biomass feedstocks including wood chips, tall grasses, corn stover (residual corn stalks) and sugar cane bagasse. The facility will provide process performance engineering data sufficient to support construction of 1/10th scale and commercial scale biorefineries in Kinross, MI, with support from the Department of Energy and State of Michigan.
Mascoma Corporation has the world’s largest research team focused on the commercial development of Consolidated Bio-Processing or CBP. We are harnessing the power of nature’s best cellulose-utilizing and ethanol-fermenting microbes; simplifying the process and allowing nature to do most of the work. CBP is widely recognized as the simplest, lowest cost configuration for producing cellulosic ethanol.