Metabolic engineering of the L-phenylalanine pathway in Escherichia coli for the production of S- or R-mandelic acid.

Zhoutong Sun, Yuanyuan Ning, Lixia Liu, Yingmiao Liu, Bingbing Sun, Weihong Jiang, Chen Yang, Sheng Yang

Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

Microbial cell factories 2011

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Mandelic acid (MA), an important component in pharmaceutical syntheses, is currently produced exclusively via petrochemical processes. Growing concerns over the environment and fossil energy costs have inspired a quest to develop alternative routes to MA using renewable resources. Herein we report the first direct route to optically pure MA from glucose via genetic modification of the L-phenylalanine pathway in E. coli. The introduction of hydroxymandelate synthase (HmaS) from Amycolatopsis orientalis into E. coli led to a yield of 0.092 g/L S-MA. By combined deletion of competing pathways, further optimization of S-MA production was achieved, and the yield reached 0.74 g/L within 24 h. To produce R-MA, hydroxymandelate oxidase (Hmo) from Streptomyces coelicolor and D-mandelate dehydrogenase (DMD) from Rhodotorula graminis were co-expressed in an S-MA-producing strain, and the resulting strain was capable of producing 0.68 g/L R-MA. Finally, phenylpyruvate feeding experiments suggest that HmaS is a potential bottleneck to further improvement in yields. We have constructed E. coli strains that successfully accomplished the production of S- and R-MA directly from glucose. Our work provides the first example of the completely fermentative production of S- and R-MA from renewable feedstock.

Citation

Zhoutong Sun, Yuanyuan Ning, Lixia Liu, Yingmiao Liu, Bingbing Sun, Weihong Jiang, Chen Yang, Sheng Yang. Metabolic engineering of the L-phenylalanine pathway in Escherichia coli for the production of S- or R-mandelic acid. Microbial cell factories. 2011;10:71