Mascoma advances bacteria, yeast technology

By Ryan C. Christiansen | July 08, 2009
Researchers at Lebanon, N.H.-based Mascoma Corp. recently announced that they have made major advances in consolidated bioprocessing (CBP), using engineered microorganisms to produce cellulosic ethanol. According to the company, Mascoma's modified bacteria and yeast not only produce cellulase enzymes to break down cellulose into sugars, but they are also capable of converting those sugars into ethanol.

According to Jim Flatt, executive vice president of research, development, and operations at Mascoma, scientists have modified the thermophilic bacterium Clostridium thermocellum to produce nearly 60 percent more ethanol from cellulose than the strain was capable of producing just a year ago. He said Mascoma has also modified yeast to produce 3,000 times as much cellulase enzymes, eliminating the need for added enzymes to convert waste paper sludge to ethanol, for example.

"The potential to express small amounts of cellulase enzymes in yeast had been demonstrated previously by several of our collaborators," Flatt said, "but expression levels were relatively modestit was significant from a scientific standpoint, but not particularly commercially relevant."

Mascoma's recent breakthroughs are bringing CBP closer to a commercial reality, according to Alan Belcher, senior vice president of operations for Mascoma, who spoke in June at the Advanced Biofuels Workshop in Denver. "All cellulosic ethanol conversion technologies are legitimate technologies," Belcher said, "but CBP has been pie-in-the-sky' for the longest period of time."

Mascoma's technology could be used at existing corn starch-based ethanol plants to produce cellulosic ethanol from a variety of possible feedstocks, Flatt said. "We think the real advantage of this solution for retrofit applications is that it's very compatible with the existing equipment and infrastructure," he said, "thereby minimizing any additional capital required to run the process."

After Mascoma's organisms become commercially available, Belcher said Mascoma will continue to improve upon them. "We'll see improvements coming out like versions of Windows, eventually," he said. Belcher said Mascoma expects to be using its technology to produce ethanol at its 25,000 gallons per year pilot plant in Rome, N.Y. by early next year. Mascoma will also continue to utilize its pilot plant for testing CBP using both bacteria and yeast.

Flatt said Mascoma's yeast will most likely be the first of two organisms to be used in the production of ethanol at the commercial scale; however, the company's modified bacteria might be the preferred organism in the long run, he said. "We think [the bacteria] has potential to be a sort of ultimate, lowest-cost solution," Flatt said.