Microbial synthesis of 3-dehydroshikimic acid: A comparative analysis of D-xylose, L-arabinose, and D-glucose carbon sources

3-Dehydroshikimic acid is a hydroaromatic precursor to chemicals ranging fr om L-phenylalanine to adipic acid. The concentration and yield of 3-dehydro shikimic acid microbially synthesized from various carbon sources has been examined under fed-batch fermenter conditions. Examined carbon sources incl uded D-xylose, L-arabinose, and D-glucose. A mixture consisting of a 3:3:2 molar ratio of glucose/xylose/arabinose was also evaluated as a carbon sour ce to model the composition of pentose streams potentially resulting from t he hydrolysis of corn fiber. Escherichia coli KL3/pKL4.79B, which overexpre sses feedback-insensitive DAHP synthase, synthesizes higher concentrations and yields of 3-dehydroshikimic acid when either xylose, arabinose, or the glucose/xylose/arabinose mixture is used as a carbon source relative to whe n glucose alone is used as a carbon source. E. coli KL3/pKL4.124A, which ov erexpresses transketolase and feedback-insensitive DAHP synthase, synthesiz es higher concentrations and yields of 3-dehydroshikimic acid when the gluc ose/xylose/arabinose mixture is used as the carbon source relative to when either xylose or glucose is used as a carbon source. Observed high-titer, h igh-yielding synthesis of 3-dehydroshikimic acid from the glucose/xylose/ar abinose mixture carries significant ramifications relevant to the employmen t of corn fiber in the microbial synthesis of value-added chemicals.