| Summary: | Sugarcane bagasse is an agricultural residue rich in xylose, which may be used as a feedstock for the production of high-value-added chemicals, such as xylonic acid, an organic acid listed as one of the top 30 value-added chemicals on a NREL report. Here, <i>Zymomonas mobilis</i> was engineered for the first time to produce xylonic acid from sugarcane bagasse hydrolysate. Seven coding genes for xylose dehydrogenase (XDH) were tested. The expression of XDH gene from <i>Paraburkholderia xenovorans</i> allowed the highest production of xylonic acid (26.17 ± 0.58 g L<sup>−1</sup>) from 50 g L<sup>−1</sup> xylose in shake flasks, with a productivity of 1.85 ± 0.06 g L<sup>−1</sup> h<sup>−1</sup> and a yield of 1.04 ± 0.04 g<sub>AX</sub>/g<sub>X.</sub> Deletion of the xylose reductase gene further increased the production of xylonic acid to 56.44 ± 1.93 g L<sup>−1</sup> from 54.27 ± 0.26 g L<sup>−1</sup> xylose in a bioreactor. Strain performance was also evaluated in sugarcane bagasse hydrolysate as a cheap feedstock, which resulted in the production of 11.13 g L<sup>−1</sup> xylonic acid from 10 g L<sup>−1</sup> xylose. The results show that <i>Z. mobilis</i> may be regarded as a potential platform for the production of organic acids from cheap lignocellulosic biomass in the context of biorefineries.
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