Chemicals from Microbes
A sustainable method to make high-value chemicals from sugar was invented at Genomatica. In addition to refining crude oil into gasoline for automobiles, refineries “crack” or process crude oil into higher-value industrial chemicals such as 1,4-butanediol (BDO) and methyl ethyl ketone (MEK). Genomatica has discovered a way to make both these chemicals from sugar in microorganisms, bypassing the need for oil.
Started in 2000, Genomatica first created and sold computational software to model how cells function and their metabolic pathways. “In the past two to three years, we used our computational models to design microbes to make chemicals,” says Christophe Schilling, Ph.D., president.
In September 2008, Genomatica reported on a biomanufacturing process for BDO in Escherichia coli that starts with sucrose. With its computational modeling software, the company’s researchers examined all possible biological pathways for making BDO from sugar (about 40,000), then they selected the best pathway and enzymes. After genetically engineering six enzymes into E. coli, the microbe generated BDO within six months. “E. coli or any other organism was never known to make BDO before,” explains Dr. Schilling.
The microbe-based process is designed to make BDO at a lower cost than petroleum-based methods. Since the results were made public, three-quarters of BDO producers worldwide have contacted Genomatica to learn about the method, according to Dr. Schilling. “Producers find it appealing to start with a renewable source and like the environmentally friendly angle,” he adds. The method has been scaled up in the laboratory to 30 L volumes and a demonstration plant is planned for large-scale fermentation. BDO, a precursor of Spandex fibers and thermoplastics, has a worldwide annual production value of $4 billion.
A similar computational modeling method led to the generation of MEK from sugar in bacteria, which the company reported in February. MEK is a common solvent in paints and varnishes, and its global market is valued at $2 billion. Moreover, the sustainable chemical processes for making MEK can be readily transferred to equipment at bioethanol manufacturing facilities, some of which have been left idle by recent market contraction.
Enzyme Cocktails for Biofuels
Verenium, formed in 2007 by the merger of Diversa and Celunol, is building a demonstration plant in Louisiana, which the company says will produce 1.4 million gallons of cellulosic ethanol from agricultural waste yearly. The Louisiana location provides a steady supply of feedstocks, a long growing season, and access to gasoline-blending facilities. A partner in the endeavor is BP, which brings $90 million in funding.
According to the Energy Industry and Security Act of 2007, 16 million gallons of ethanol annually must be made from biomass by 2022. “Today, there are zero gallons of ethanol made from biomass, so this industry has to be created,” says Janet Roemer, GM of Verenium’s specialty enzyme business.
The enzyme expertise of former Diversa scientists is helping to maximize the breakdown of cellulosic biomass to sugars for fermentation into ethanol. Diversa scientists traveled the world in search of enzymes that thrive in hostile environments such as geysers in Yellowstone National Park. Now, those libraries are being screened to find enzyme cocktails to speed the production of ethanol from diverse feedstocks such as bagasse (sugar cane refuse) and energy cane.
Energy cane, a nonfood cousin of sugar cane, generates up to 1,830 gallons of ethanol per acre. In contrast, corn makes about 400 gallons of ethanol per acre and switchgrass about 700 gallons per acre. “The enzymes we are using at the demonstration plant are the best we know of today,” says Roemer. Verenium, however, continually looks for improved enzyme cocktails to drive costs down and raise its competitive edge.