酶-菌协同转化甲醇合成1,3-丙二醇

Enzyme-bacteria synergistic conversion of methanol to 1,3-propanediol

摘要:

目的 1,3-丙二醇(1,3-propanediol, PDO)是一种重要的化工单体，其生物合成主要依赖甘油或葡萄糖等碳源，存在碳原子经济性差、依赖粮食资源等问题。甲醇作为非粮可再生碳源，具有还原度高、价格低廉的优势，但现有甲醇生物转化合成PDO的效率较低，面临甲醇利用效率差、细胞毒性等瓶颈。方法 本研究设计了一条酶-菌协同转化甲醇合成PDO的新路线：首先，采用体外多酶级联体系将甲醇转化为甘油，催化体系包含醇氧化酶(alcohol oxidase, AOX)、过氧化氢酶(catalase, CAT)、甲醛裂合酶(formaldehyde lyase, FLS)、甘油脱氢酶(glycerol dehydrogenase, GldA)及甲酸脱氢酶(formate dehydrogenase, FDH)，反应4 h后甘油浓度达63.3 mmol/L，甲醇至甘油的碳转化率为95.0%；其次，在谷氨酸棒杆菌(Corynebacterium glutamicum)中引入甘油转运蛋白GlpF、甘油脱水酶DhaB123及其激活因子GdrAB、NADPH依赖型醇脱氢酶YqhD，构建重组菌株并建立全细胞反应体系，将生成的甘油转化为PDO。在优化条件下，甘油至PDO的碳转化率达到96.0%。结果 为实现甲醇直接合成PDO，将上述2个过程偶联，最终PDO产量达30.4 mmol/L，甲醇至PDO的碳转化率为90.2%。结论 本研究实现了甲醇高效转化合成PDO，为甲醇基高值化学品的绿色生物制造提供了新策略。

Abstract:

Objective 1,3-propanediol (PDO) is an important chemical monomer. Its biosynthetic routes mainly rely on carbon sources such as glycerol or glucose, which suffer from low carbon efficiency or reliance on food-based resources. Methanol, as a non-food renewable carbon source, offers advantages of a high reduction degree and low costs. However, the existing bioconversion of methanol to PDO is limited by low methanol utilization efficiency and cytotoxicity.Methods In this study, a novel route combining enzymatic and whole-cell catalysis for the conversion of methanol to PDO was designed. First, an in vitro multi-enzyme cascade system was used to convert methanol to glycerol, comprising alcohol oxidase (AOX), catalase (CAT), formaldehyde lyase (FLS), glycerol dehydrogenase (GldA), and formate dehydrogenase (FDH). After 4 h of reaction, the glycerol concentration reached 63.3 mmol/L, with a carbon conversion efficiency of 95.0% from methanol to glycerol. Second, the glycerol transporter GlpF, glycerol dehydratase DhaB123 and its activator GdrAB, and the NADPH-dependent aldehyde reductase YqhD were introduced into Corynebacterium glutamicum to construct a recombinant strain, enabling the whole-cell conversion of glycerol to PDO. Under optimized conditions, the carbon conversion efficiency from glycerol to PDO reached 96.0%.Results To convert methanol to PDO, we coupled the two processes, which achieved a final PDO titer of 30.4 mmol/L and the overall carbon conversion efficiency of 90.2% from methanol to PDO.Conclusion This study achieves efficient conversion of methanol to PDO and provides a new strategy for the green biomanufacturing of methanol-based high-value chemicals.