In 2004, the U.S. DOE released a report identifying 12 chemicals that could be produced from sugars, most through microbial fermentation. These building blocks were of interest because they could be converted into various high-value biobased chemicals and materials. At the top of the list was succinic acid, a four-carbon molecule with a chemical structure similar to maleic anhydride. Maleic anhydride is a petroleum-derived substance that provides a chemical feedstock for food and pharmaceutical products, surfactants and detergents, plastics, clothing fibers, and biodegradable solvents. Because the two chemicals are so much alike and succinic acid is made by all living things through a natural fermentation of sugars, biomass-derived succinic acid could serve as an attractive replacement for maleic anhydride and a platform chemical for the synthesis of a multitude of compounds. “That is the beauty of succinic acid,” explains Susanne Kleff, senior scientist for MBI International, formerly Michigan Biotechnology Institute. “First you want that four-carbon platform,” she says. “Second, any chemical you can make that is part of the central metabolism of an organism always implies that you can make lots of it and that you can make it easily.” Although currently elusive, a competitively priced route for the “green” production of succinic acid could open a menagerie of new markets for the chemical.

Much of the research into biobased succinic acid originated in government agencies, particularly the DOE, however, the attention of these institutions is now consumed with meeting fuel standards. “Some government agencies’ emphasis on biobased products has lessened because of more pressing energy and fuel mandates,” explains Gene Petersen, DOE project officer and chemist. “The question is will the private sector step up to the plate?”

The answer is yes, say representatives from two companies who agreed to speak with Biomass Magazine about each company’s quest to make competitively priced, biobased succinic acid a reality.

The Prize
As quests go, this one may not be as dramatic as destroying a ring and ridding war-torn Middle-Earth of a supernatural evil as in the “Lord of the Rings” epic. However, the eventual reward reaped by the potential heroes—a market estimated at more than $1.3 billion per year—is not too shabby a prize for overcoming the challenges to commercialize the means to produce green succinic acid. Although currently available succinic acid, which is made from butane, a four-carbon petrochemical, serves a relatively small world market of about 15,000 metric tons per year, the potential market for a biobased form of the chemical could be well over 100 times that amount. “The extent of market penetration depends mainly on the price competitiveness of biobased succinic acid relative to the petrochemical alternatives,” Kleff says. “There is also more interest in producing polymers from monomers produced via a green route.”

The bounty from this potential gold mine lies in the usefulness of succinic acid as a building block for a plethora of secondary chemicals. Kleff outlines three major potential markets for green succinic acid. The greatest of these is as a biobased replacement for maleic anhydride, which currently serves a global market of about 1.65 million tons per year. Second is the more than 1.6 million pounds per year global market for polymers currently derived from butane. The smallest market of about 100 million pounds per year is for pyrrolidinones, which are used to make green solvents and eco-friendly chemicals for water treatment.

“There are all kinds of derivative markets where right now succinic acid is not used because it’s too expensive compared with petrochemicals,” explains Dilum Dunuwila, vice president of business development at Diversified Natural Products Inc. (DNP) an industrial biotechnology company. “As a business we have to get to the point where we are economically competitive with petrochemical pricing,” he says. “We are getting there.”

The final prize and incentives for action are well defined but how will they be achieved?

The Journey
MBI, established in 1981 by the Michigan High Technology Task Force, has a history of developing biobased chemicals and agricultural feedstocks into chemicals derived from fermentation processes. In 1996, the company patented the unique bacterium it isolated for production of succinic acid from sugars. MBI scientists—knowing that the rumen, one of the four compartments of the bovine stomach, was a warm, voluminous holding vat devoid of oxygen and brimming with microbes that digest and ferment an endless supply of well-masticated feedstuffs—collected rumen samples and isolated a novel succinic acid producer. “The rumen is an environment where you would expect to find an organism that produces succinic acid,” Kleff explains. In addition to conditions prime for fermentation, “the environment is high in carbon dioxide, which we incorporate into our product,” she adds. “So, in contrast to almost everything else other than photosynthesis, we make a product in which we incorporate CO2 (carbon dioxide).” Because carbon dioxide is a byproduct of ethanol production, the synthesis of biobased succinic acid could be linked to ethanol plants.

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