Abstract：
Biosensor-based high-throughput screening is efficient for improving industrial microorganisms. There is a severe shortage of human milk oligosaccharides (HMOs) biosensors. This study established a 3-fucosyllactose (3-FL, a kind of HMOs) whole-cell biosensor by coupling cell growth with production. To construct and optimize the biosensor, an Escherichia coli 3-FL producer was engineered by deleting the manA, yihS and manX genes, directing the mannose flux solely to 3-FL synthesis. Then, an α-L-fucosidase was introduced to hydrolyze 3-FL to fucose which was used as the only carbon source for cell growth. Using the biosensor, the 3-FL production of a screened mutant was improved by 25 % to 42.05 ± 1.28 g/L. The productivity reached 1.17 g/L/h, the highest level reported by now. The csrB mutant obtained should be a new clue for the 3-FL overproduction mechanism. In summary, this study provided a novel approach to construct HMOs biosensors for strain improvement.
摘要：
基于生物传感器的高通量筛选对于改善工业微生物是有效的。人乳寡糖(HMO)生物传感器严重短缺。本研究建立了3-岩藻糖基乳糖（3-FL，一种HMO）通过将细胞生长与生产耦合起来的全细胞生物传感器。为了构建和优化生物传感器，大肠杆菌3-FL生产者是通过删除manA来设计的，yihS和manX基因，将甘露糖通量仅引导至3-FL合成。然后，引入α-L-岩藻糖苷酶以将3-FL水解成岩藻糖,其用作细胞生长的唯一碳源。使用生物传感器，筛选的突变体的3-FL产量提高了25％，达到42.05±1.28g/L。生产率达到1.17g/L/h，目前报告的最高水平。获得的csrB突变体应该是3-FL过量产生机制的新线索。总之,本研究提供了一种构建HMOs生物传感器的新方法，用于菌株改良。
