A team at Rice University has engineered E. coli bacteria to produce succinate (an ester of succinic acid) from soybean mash. A paper describing their work was published in the journal Bioresource Technology.
In 2004, the US Department of Energy (DOE) named succinic acid one of 12 “platform” chemicals that could be produced from sugars by biological means and turned into high-value materials.
Several years ago, Rice patented a process by Rice chemists George Bennett and Ka-Yiu San for the bio-based production of succinic acid that employed genetically modified E. coli bacteria to convert glucose into succinic acid in a way that would be competitive with petroleum-based production.
The new succinate process developed by Bennett, San and Chandresh Thakker promises to make even better use of a cheap and plentiful feedstock—primarily the indigestible parts of the soybean.
We are trying to find a cheaper, renewable raw material to start with so the end product will be more profitable. The challenge has been to make this biomass process cost-competitive with the petrochemical methods people have been using for many years.—Chandresh Thakker
The new microbes are engineered to metabolize a variety of sugars found in soybean meal. The theoretical ideal is a 1:1 ratio of feedstock (the extracted sugars) to product. In the lab, under less controlled conditions, the team found the process highly efficient.
In the published study, two different strains consumed 160 mM and 187 mM hexose and produced 158 mM and 183 mM succinate, respectively. Maximum succinate production of 312 mM with a molar yield of 0.82 mol/mol hexose was obtained using soy solubles hydrolysate by one of the strains.
The United Soybean Board and the National Science Foundation supported the research.
Chandresh Thakker, George N. Bennett, Ka-Yiu San (2012) Production of succinic acid by engineered E. coli strains using soybean carbohydrates as feedstock under aerobic fermentation conditions, Bioresource Technology doi: 10.1016/j.biortech.2012.10.154