Sunday, July 29, 2007
P91

Enhancement of vanillin production by modulation of acetyl-CoA and coenzyme A in recombinant Escherichia coli

Eun-Gyeong Lee, Sang-Hwal Yoon, Sook-Hee Lee, Hee-Kyoung Ryu, Chong-Long Wang, Hee-Jung Jang, Ji-Seon Park, Amitabha Das, and Seon-Won Kim. Division of Applied Life Science, Gyeongsang National University, 900 Gajwadong, Jinju, 660-701, South Korea

The conversion of ferulic acid to vanillin was examined using E. coli which was metabolically engineered by the expression of the fcs and ech genes from Amycolaptopsis sp. encoding feruloyl-CoA synthetase and enoyl-CoA hydratase/aldolase. It was presumed that efficient supply of coenzyme A cofactor for feruloyl-CoA formation and efficient removal of acetyl-CoA for reduction of its feed-back regulation to ech would favor flow from ferulic acid to vanillin and thus increase vanillin production. Overexpression of gltA encoding citrate synthase initiates utilization of acetyl-CoA through TCA cycle with release of CoA. Glyoxylate bypass cycle is an alternative pathway to TCA cycle, which consumes more acetyl-CoA and releases more CoA (2 Acetyl-CoA and 2 CoA per cycle). The iclR or icdA genes were deleted to block the intermediate flow to TCA cycle and to direct it to glyoxylate bypass. The E. coli DH5α harboring pTAHEF-gltA produced 2.1 g/L vanillin from 3 g/L ferulic acid in comparison to only 1.0g/L of vanillin produced by E. coli DH5α (pTAHEF). The maximum amount of 2.4 g/L vanillin production was found in E. coli BW25113 DicdA harboring pTAHEF-gltA, while its wild type E. coli BW25113 (pTAHEF-gltA) produced much less amount of vanillin, 0.8g/L.

This work was supported by the EB-NCRC (Grant No. R15-2003-012-02001-0), Technology Development Program for Agriculture and Forestry (Ministry of Agriculture and Forestry), Brain Pool program and BK21 program of Korea.


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