Figure 3. Detection of xylose, xylonate and xylonolactone by ion chromatography.

A, 1 ppm xylose, corresponding to the retention time of 2.75 min; B, 200 ppm xylonolactone, corresponding to the retention time of 2.61 min; C, 100 ppm xylonate, corresponding to the retention time of 3.43 min; D, detection of the enzymatic product of xylose dehydrogenase; E, detection of the enzymatic product of xylonolactonase; F, ion chromatogram of the extracellular metabolites of strain BL21ΔxylAB/pA-xdhxylC after being induced for 12 h. Both the enzymatic reaction mixtures and culture broth supernatant were appropriately diluted for ion chromatography analysis.