Development of an Escherichia coli whole cell biocatalyst for the production of hyperoside.

OBJECTIVE: To produce high concentrations of hyperoside from quercetin using recombinant Escherichia coli with in situ regeneration of UDP-galactose. RESULTS: Sucrose synthase from Glycine max (GmSUS) was co-expressed with UDP-glucose epimerase from E. coli (GalE) in E. coli for regenerating UDP-galactose from UDP and sucrose. Glycosyltransferase from Petunia hybrida (PhUGT) was introduced to synthesize hyperoside from quercetin through the regeneration system of UDP-galactose. Co-expressing with molecular chaperones GroEL/ES successfully enhanced the catalytic efficiency of the recombinant strain, which assisted the soluble expression of PhUGT. By using a fed-batch approach, the production of hyperoside reached 863.7 mg L-1 with a corresponding molar conversion of 93.6% and a specific productivity of 72.5 mg L-1 h-1. CONCLUSION: The method described herein for hyperoside production can be widely applied for the synthesis of isorhamnetin-3-O-galactoside, kaempferol-3-O-galactoside and other flavonoids.

Engineering a heterologous synthetic pathway in Escherichia coli for efficient production of biotin.

OBJECTIVE: To enhance biotin production in Escherichia coli by engineering a heterologous biotin synthetic pathway. RESULTS: Biotin operon genes from Pseudomonas putida, which consisted of a bioBFHCD cluster and a bioA gene, was engineered into Escherichia coli for biotin production. The introduction of bioW gene from Bacillus subtilis, encoding pimeloyl-CoA synthetase and sam2 gene from Saccharomyces cerevisiae, encoding S-adenosyl-L-methionine (SAM) synthetase contributed to the heterologous production of biotin in recombinant E. coli. Furthermore, biotin production was efficiently enhanced by optimization of the fermentation compositions, especially pimelic acid and L-methionine, the precursor related to the pimeloyl-CoA and SAM synthesis, respectively. The combination of overexpression of the heterologous biotin operon genes and enhanced supply of key intermediate pimeloyl-CoA and SAM increased biotin production in E. coli by more than 121-fold. With bioprocess engineering efforts, biotin was produced at a final titer of 92.6 mg/L in a shake flask and 208.7 mg/L in a fed-batch fermenter. CONCLUSION: Through introduction of heterologous biotin synthetic pathway, increasing the supply of precursor pimeloyl-CoA and cofactor SAM can significantly enhance biotin production in E. coli.