Metabolic engineering of Bacillus subtilis for production of para-aminobenzoic acid - unexpected importance of carbon source is an advantage for space application
Metabolic engineering of Bacillus subtilis for production of para-aminobenzoic acid - unexpected importance of carbon source is an advantage for space application
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DOI：
10.1111/1751-7915.13403
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发表时间：
2019-07-01
影响因子：
5.7
通讯作者：
Rothschild, Lynn J.
中科院分区：
文献类型：
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作者：
Averesch, Nils J. H.;Rothschild, Lynn J.
高强度聚合物，例如芳纶纤维，是空间技术中的重要材料。为了在火星等偏远地区获取这些材料，生物生产很有意义。芳香族聚合物前体对氨基苯甲酸（pABA）可以通过枯草芽孢杆菌（一种适合空间合成生物学的生物体）的代谢工程从莽草酸途径衍生而来。我们的工程策略包括修复有缺陷的吲哚-3-甘油磷酸合酶（trpC）、敲除一种分支酸变位酶同工酶（aroH）以及分别从细菌callunae和Xenorhabdus bovienii中过量表达氨基脱氧分支酸合酶（pabAB）和氨基脱氧分支酸裂合酶（pabC）。此外，还创建了一种融合蛋白酶（pabABC）来引导碳通量。利用适应性进化，创建了能够代谢木糖的生产菌株突变体，以探索和比较不同碳源的 pABA 生产能力。总体限制因素似乎不是底物的效率或生化途径的性能，而是强烈依赖于 pH 值的产物毒性。摇瓶中获得的最高滴度为 3.22 g l(-1)，氨基糖的碳产率为 12.4% [C-mol/C-mol]。这保证了该系统适用于空间生物技术中的原位资源利用（ISRU），其中来自蓝藻细胞裂解物的原料发挥了作用。
High-strength polymers, such as aramid fibres, are important materials in space technology. To obtain these materials in remote locations, such as Mars, biological production is of interest. The aromatic polymer precursor para-aminobenzoic acid (pABA) can be derived from the shikimate pathway through metabolic engineering of Bacillus subtilis, an organism suited for space synthetic biology. Our engineering strategy included repair of the defective indole-3-glycerol phosphate synthase (trpC), knockout of one chorismate mutase isozyme (aroH) and overexpression of the aminodeoxychorismate synthase (pabAB) and aminodeoxychorismate lyase (pabC) from the bacteria Corynebacterium callunae and Xenorhabdus bovienii respectively. Further, a fusion-protein enzyme (pabABC) was created for channelling of the carbon flux. Using adaptive evolution, mutants of the production strain, able to metabolize xylose, were created, to explore and compare pABA production capacity from different carbon sources. Rather than the efficiency of the substrate or performance of the biochemical pathway, the product toxicity, which was strongly dependent on the pH, appeared to be the overall limiting factor. The highest titre achieved in shake flasks was 3.22 g l(-1) with a carbon yield of 12.4% [C-mol/C-mol] from an amino sugar. This promises suitability of the system for in situ resource utilization (ISRU) in space biotechnology, where feedstocks that can be derived from cyanobacterial cell lysate play a role.