Production of D-Xylonate from Corn Cob Hydrolysate by a Metabolically Engineered Escherichia coli Strain
Production of D-Xylonate from Corn Cob Hydrolysate by a Metabolically Engineered Escherichia coli Strain
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通过代谢工程大肠杆菌菌株从玉米芯水解产物中生产 D-木糖酸
DOI：
10.1021/acssuschemeng.8b04839
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发表时间：
2019
影响因子：
8.4
通讯作者：
Ma Cuiqing
中科院分区：
文献类型：
--
作者：
Zhang Yipeng;Guo Shiting;Wang Yuxian;Liang Xiao;Xu Ping;Gao Chao;Ma Cuiqing
玉米芯是一种很容易被水解成富含木糖的二次农用残渣。除木糖外，D-葡萄糖和1-阿拉伯糖也是玉米芯水解液中可利用的糖。在此，我们建立了重组大肠杆菌利用葡萄糖和阿拉伯糖支持其生长，并将玉米芯水解液中的木糖转化为木糖的转化体系。首先，过量表达了d-木酸的生物合成途径，并敲除了两个木酸脱水酶。ColiW3110转化D-木糖生产强化木糖。然后，在重组菌株的生长过程中，剔除负责乙酸盐、乙醇和乳酸合成的基因，以减少这些副产品的产生。三个连续的策略被用来提高木酸乙酯的产量--使用乳糖作为诱导剂，消除碳分解代谢的抑制，以及抑制乳糖的降解。以D-木糖为底物，D-葡萄糖为碳源，分批补料发酵生产108.2 g/d-木糖，d-木酸酯产量为1.09 g/g d-木糖。以玉米芯水解液为原料，发酵产量为91.2g/LD-木酸，比产率为1.52g/[L·h]。本研究不仅对生产D-木酸具有一定的参考价值，而且为从玉米芯水解液中提取其他重要化学物质提供了一种新的利用体系。
Corn cob is the secondary agricultural residue that can be easily hydrolyzed into hydrolysate with abundantd-xylose. Besidesd-xylose,d-glucose, andl-arabinose are also utilizable sugars in corn cob hydrolysate. Here, we established a coutilization system through which recombinantEscherichia colican used-glucose andl-arabinose supporting its growth and convertd-xylose in corn cob hydrolysate intod-xylonate. First, biosynthetic pathway ofd-xylonate was overexpressed and two xylonate dehydratases were knocked out inE. coliW3110 to enhanced-xylonate production fromd-xylose. Then, the genes responsible for acetate, ethanol, and lactate synthesis were knocked out to decrease these byproducts production during the growth of the recombinant strain. Three successive strategies were employed to enhance thed-xylonate production—using lactose as the inducer, eliminating carbon catabolite repression, and inactivating the lactose degradation. Finally, 108.2 g/Ld-xylonate was produced with a yield of 1.09 g ofd-xylonate/g ofd-xylose usingd-xylose as the substrate andd-glucose as the carbon source through fed-batch fermentation. When corn cob hydrolysate was used, 91.2 g/Ld-xylonate was produced with a specific productivity of 1.52 g/[L·h]. This study is valuable not only for producingd-xylonate but also for providing a coutilization system to obtain other important chemicals from corn cob hydrolysate.