Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars.
Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars.
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DOI：
10.1186/s13068-017-0920-z
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发表时间：
2017
影响因子：
6.3
通讯作者：
Jin L
中科院分区：
文献类型：
--
作者：
Li C;Gai Z;Wang K;Jin L
地衣芽孢杆菌MW 3是一株具有GRAS活性的嗜热菌，是一种很有前途的化工和生物燃料生产微生物。然而，它的能力，共同利用葡萄糖和木糖，在木质纤维素生物质中发现的主要糖，是严重受损的葡萄糖介导的碳代谢产物阻遏（CCR）。本研究以L-乳酸为目标产物，采用“双通道”工艺对MW 3菌株进行工程改造，使其同时利用葡萄糖和木糖。通过缺失葡萄糖转运蛋白基因ptsG和引入半乳糖通透酶基因galP激活非磷酸转移酶系统（PTS）葡萄糖摄取途径。将葡萄糖激酶基因glck的启动子替换为强启动子Pals后，工程菌恢复了对葡萄糖的消耗，并同时利用葡萄糖和木糖。同时，为提高该菌株的木糖消耗速率，采取了解除木糖阻遏物XylR的调控、减少代谢产物响应元件、优化限速步骤等措施。敲除乙醇和乙酸途径基因进一步增加了6.2%的乳酸产量。该菌株发酵40 h后，L-乳酸产量可达121.9 g/L，产率达95.3%。以木质纤维素水解液为底物，在40 h内产L-乳酸99.3 g/L，比生产率为2.48 g/[L·h]，产率为94.6%。我们的工程菌株B.地衣芽孢杆菌RH 15能从木质纤维素水解液中以较高的浓度和产率产L-乳酸，其产率与大多数已报道的L-乳酸生产菌具有竞争力。因此，工程菌株可能被用作生产其他化学品的平台。除了设计B。地衣菌菌株，“双通道”过程可以作为工程化多种其他菌株的替代方法。本文的在线版本（doi：10.1186/s13068-017-0920-z）包含补充材料，可供授权用户使用。
Bacillus licheniformis MW3 as a GRAS and thermophilic strain is a promising microorganism for chemical and biofuel production. However, its capacity to co-utilize glucose and xylose, the major sugars found in lignocellulosic biomass, is severely impaired by glucose-mediated carbon catabolite repression (CCR). In this study, a “dual-channel” process was implemented to engineer strain MW3 for simultaneous utilization of glucose and xylose, using l-lactic acid as a target product. A non-phosphotransferase system (PTS) glucose uptake route was activated via deletion of the glucose transporter gene ptsG and introduction of the galactose permease gene galP. After replacing the promoter of glucokinase gene glck with the strong promoter P als, the engineered strain recovered glucose consumption and utilized glucose and xylose simultaneously. Meanwhile, to improve the consumption rate of xylose in this strain, several measures were undertaken, such as relieving the regulation of the xylose repressor XylR, reducing the catabolite-responsive element, and optimizing the rate-limiting step. Knockout of ethanol and acetic acid pathway genes further increased lactic acid yield by 6.2%. The resultant strain, RH15, was capable of producing 121.9 g/L l-lactic acid at high yield (95.3%) after 40 h of fermentation from a mixture of glucose and xylose. When a lignocellulosic hydrolysate was used as the substrate, 99.3 g/L l-lactic acid was produced within 40 h, with a specific productivity of 2.48 g/[L h] and a yield of 94.6%. Our engineered strain B. licheniformis RH15 could thermophilically produced l-lactic acid from lignocellulosic hydrolysate with relatively high concentration and productivity at levels that were competitive with most reported cases of l-lactic acid-producers. Thus, the engineered strain might be used as a platform for the production of other chemicals. In addition to engineering the B. licheniformis strain, the “dual-channel” process might serve as an alternative method for engineering a variety of other strains. The online version of this article (doi:10.1186/s13068-017-0920-z) contains supplementary material, which is available to authorized users.
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影响因子：
6.3
作者：
Demeke MM;Dumortier F;Li Y;Broeckx T;Foulquié-Moreno MR;Thevelein JM
通讯作者：
Thevelein JM
影响因子：
2.7
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
11.4
作者：
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通讯作者：
Fan, Zhiliang
影响因子：
4.4
作者：
Lee, Sun-Mi;Jellison, Taylor;Alper, Hal S.
通讯作者：
Alper, Hal S.