Improvement of 1,3-propanediol production in Klebsiella sp. by co-expressing Vitreoscilla hemoglobin and formate dehydrogenase genes

Abstract

An efficient and flexible protocol was developed for simultaneous detection of the ginsenosides Rg1, Re, Rf, Rh1, and Rg2 in ginseng extract. In the analysis of white ginseng that contains no ginsenoside Rf, separation of the remaining ginsenosides was achieved within just 10 min under isocratic chromatographic conditions. For the analysis of red ginseng that contains ginsenoside Rf as a characteristic constituent, the gradient elution conditions were optimized. The method is based on high-pressure liquid chromatography employing a Shiseido UG 80 Capcell Pak NH2(4.6 mm I.D. × 250 mm, 5 μm)column and isocratic elution using acetonitrile (A) and water(B) in a ratio of 76: 24 (v/v), The optimal gradient elution conditions are as follows: 0–3 min, 89% A, 3–25 min, 89–84% A, 25–30 min, 84–82% A, 30–35 min, 82-76% A, then returning to 89% solvent A in 5 min. The flow rate was 0.80 mL min−1. The column temperature was set at 25℃ and the detection wavelength was at 203 nm. The working concentration ranges for ginsenoside Re, Rh1, Rg2, Rg1, and Rf were 0.23−1450.0 mg• L−1, 0.05−1130.0 mg• L−1, 0.11−687.0 mg• L−1, 0.051−1325 mg• L−1, and 0.55−800.0 mg• L−1, respectively. The method was validated for linearity, precision, and accuracy. And the further confirmation of five ginsenosides was conducted by QTOF-MS. Analysis of raw extracts of ginseng, white ginseng, and red ginseng for the five components showed satisfactory recovery.