Azotobacter vinelandii is a microorganism with biotechnological potential because its ability to produce alginate and polyhydroxybutyrate. Large-scale biotechnological processes are oriented to sustainable production by using biomass hydrolysates that are mainly composed by glucose and xylose. In the present study, it was observed that A. vinelandii was unable to consume xylose as the sole carbon source and that glucose assimilation in the presence of xylose was negatively affected. Adaptive Laboratory Evolution (ALE) was used as a metabolic engineering tool in A. vinelandii, to improve both carbohydrate assimilation. As a result of ALE process, the CT387 strain was obtained. The evolved strain (CT387) grown in shaken flask cultivations with xylose (8 g L-1) and glucose (2 g L-1), showed an increase of its specific growth rate (µ), as well as of its glucose and xylose uptake rates of 2, 6.45 and 3.57-fold, respectively, as compared with the parental strain. At bioreactor level, the µ, the glucose consumption rate and the relative expression of gluP that codes for the glucose permease in the evolved strain were also higher than in the native strain (1.53, 1.29 and 18-fold, respectively). Therefore, in the present study, we demonstrated the potential of ALE as a metabolic engineering tool for improving glucose and xylose consumption in A. vinelandii.

中文翻译：

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通过适应性实验室进化改善 Azotobacter vinelandii 中葡萄糖和木糖的同化

Azotobacter vinelandii 是一种具有生物技术潜力的微生物，因为它能够产生藻酸盐和聚羟基丁酸盐。通过使用主要由葡萄糖和木糖组成的生物质水解物，大规模生物技术过程以可持续生产为导向。在本研究中，观察到 A. vinelandii 无法消耗木糖作为唯一的碳源，并且木糖存在下的葡萄糖同化受到负面影响。适应性实验室进化 (ALE) 被用作 A. vinelandii 中的代谢工程工具，以改善碳水化合物的同化。作为ALE过程的结果，获得了CT387菌株。用木糖 (8 g L-1) 和葡萄糖 (2 g L-1) 在摇瓶培养中生长的进化菌株 (CT387) 显示出其比生长速率 (μ) 的增加，以及与亲本菌株相比，其葡萄糖和木糖摄取率分别是 2、6.45 和 3.57 倍。在生物反应器水平上，进化菌株中编码葡萄糖通透酶的 μ、葡萄糖消耗率和 gluP 的相对表达也高于天然菌株（分别为 1.53、1.29 和 18 倍）。因此，在本研究中，我们证明了 ALE 作为代谢工程工具的潜力，可改善 A. vinelandii 中葡萄糖和木糖的消耗。分别）。因此，在本研究中，我们证明了 ALE 作为代谢工程工具的潜力，可改善 A. vinelandii 中葡萄糖和木糖的消耗。分别）。因此，在本研究中，我们证明了 ALE 作为代谢工程工具的潜力，可改善 A. vinelandii 中葡萄糖和木糖的消耗。