甲基杆菌天然色素蛋白复合体的重塑及甲醇微氧发酵转化

甲醇高值转化是生物化工的前沿研究热点。具有工业应用前景的甲基杆菌面临同化甲醇过程能量与还原力消耗巨大，好氧呼吸耗散电子多的困扰，限制生长与还原度产品有效合成。研究表明甲基杆菌具有光合作用潜能，为构建不同于单纯改造同化过程提供一种新的思路，然而天然光合产能效率低。提高甲基杆菌光合效率要解决如何优化构筑色素蛋白复合体和打破光合系统利用惰性的核心问题。本项目拟利用基因及元件优化和蛋白酶空间骨架聚集技术，梯度量化合成细菌叶绿素，并借助血红素生物传感器动态协同调控叶绿素代谢与光合蛋白组装的进程，重塑光合物质基础；进而整合进化生物学和电子阱策略，减少氧供给作为适应性压力，驱动电子传递链更有效用于光合磷酸化，溢出甲醇电子迅速传入还原力并耦联3-羟基丙酸发酵生产。本项目独辟蹊径构建兼具光合产能与甲醇微氧发酵转化的细胞工厂，也为甲烷等含电子少的有机碳一绿色转化提供理论与技术参考。

The bioconversion of methanol to value-added products is a frontier and hot topic for biochemical engineering. Methylobacterium extorquens which has great prospects of industrial application, consumes a lot of energy and reducing equivalent when it assimilates methanol. And aerobic respiration dissipates too many electrons. All of these restrict the cell growth and efficient biosynthesis of high value and reductive chemicals. Recent researches have shown that M. extorquens has photosynthetic potential, providing a new idea for reconstructing the microbial chassis that is different from simply engineering assimilation pathway. However, native photosynthetic efficiency is quite low. To improve the photosynthesis of M. extorquens, it is important to solve the core problems of how to optimize the reconstruction of pigment-protein complexes and how to enhance the efficiency of photosynthetic systems. To this end, we propose to utilize the optimized genes and elements with protein scaffold technology to obtain gradient synthesis of bacteriochlorophyll. A heme biosensor will be further applied to dynamically and cooperatively regulate the process of bacteriochlorophyll metabolism and protein assembly to reshape the photosynthetic material foundation. Moreover, the combined approaches of adaptive laboratory evolution and electron sink will be used to drive electron transfer chain more effectively for photosynthetic phosphorylation during the decrease of oxygen supply. The electrons derived from methanol will be quickly transferred into the reducing equivalent with coupling to microoxic fermentation of 3-hydroxypropionic acid. This proposal constructs the methylotrophic chassis with photosynthetic capacity and methanol bioconversion by microoxic fermentation. Ultimately, the proposed strategy provides theoretical and technical references for the green bioconversion of other organic one carbon with low electrons such as methane.