Itaconate, a C 5 unsaturated dicarboxylic acid, is an important chemical building block that is used in manufacturing high-value products, such as latex and superabsorbent polymers. Itaconate is produced by fermentation of sugars by the filamentous fungus Aspergillus terreus. However, fermentation by A. terreus involves a long fermentation period and the formation of various byproducts, resulting in high production costs. E. coli has been developed as an alternative for producing itaconate. However, fermentation of glucose gives low conversion yields and low productivity. Here, we report the whole-cell bioconversion of citrate to itaconate with enhanced aconitase and cis-aconitate decarboxylase activities by controlling the expression of multiple cadA genes. In addition, this bioconversion system does not require the use of buffers, which reduces the production cost and the byproducts released during purification. Using this whole-cell bioconversion system, we were able to catalyze the conversion of 319.8 mM of itaconate (41.6 g/L) from 500 mM citrate without any buffer system or additional cofactors, with 64.0% conversion in 19 h and a productivity of 2.19 g/L/h. Our bioconversion system suggests very high productivity for itaconate production.
Bibliographical noteFunding Information:
This study was supported by the National Research Foundation of Korea ((NRF-2015R1A2A2A04006014, NRF-2016R1D1A1B03932301, NRF-2015M1A5A1037196) and by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20163010092150). Consulting service from the Microbial Carbohydrate Resource Bank (MCRB, Seoul, Korea) was kindly appreciated.
© The Author(s) 2017.