P128: Metabolic engineering of Escherichia coli for itaconate production

With increased attention on sustainable production processes that are considered as one of the solutions for mitigating the environmental problems encountered today, the chemical industry has a strong interest in developing bio-refining processes as an alternative to petroleum-based chemical production schemes. Among basic chemicals, itaconic acid (IA), one of the top 12 building block chemicals identified by the U.S. Department of Energy in 2004, is a simple but structurally unique 5-carbon-unit organic acid with an exo-methylene group along with two carboxylic moieties. It can be converted into a variety of products including polyesters, artificial glass, as well as bioactive compounds used in agriculture, pharmaceutical industry, and medicine. Currently, more than 80,000 tons of IA is produced world-wide annually at a price of USD 3/Kg. Although IA is now commercially produced in large quantities using the native producer, Aspergillus terreus, the glucose-based medium for production is still deemed inappropriate socially and economically for its competition with the food market and the cost increase because of the high demand, respectively. In addition, the filamentous nature of the organism and the difficulty in genetic manipulation makes process improvement a challenge. Thus, a genetically engineered Escherichia coli that is capable of producing IA from glycerol, a renewable carbon source of bio-diesel by-product, is desirable. In this work, we metabolically engineered E. coli and have achieved IA production with a relatively high titer (70 g/L) and specificity productivity (1.5 g/L/h). Various aspects of metabolic engineering approach in this work will be discussed in this presentation.