Bio-production of high-purity propionate by engineering l-threonine degradation pathway in Pseudomonas putida
Bio-production of high-purity propionate by engineering l-threonine degradation pathway in Pseudomonas putida
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DOI：
10.1007/s00253-020-10619-7
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发表时间：
2020-04-24
影响因子：
5
通讯作者：
Yu, Bo
中科院分区：
文献类型：
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作者：
Ma, Chao;Mu, Qingxuan;Yu, Bo
丙酸（PA）广泛用于食品、农业和制药工业。由于石化PA是不可持续的，从可再生基质中生物生产PA正受到关注。在这项研究中，我们工程菌株恶臭假单胞菌KT 2440转化L-苏氨酸PA与只有CO2释放作为副产物。通过异源L-苏氨酸脱氨酶、通透酶和酰基-CoA硫酯酶的染色体掺入、分支途径的缺失以及内源性支链α-酮酸脱氢酶复合物的过量产生来创建细胞工厂。在优化条件下，最终工程菌在48 h内可从400 mM L-苏氨酸转化399 mM PA，摩尔转化率为99.8%。PA滴度进一步达到50.3 g/L（679 mM），在补料分批转化过程中的生产率为0.6 g/L/h。在发酵液中没有检测到明显的副产物，如乙酸盐和琥珀酸盐，这将显著促进下游纯化步骤。因此，本研究为PA的生物生产提供了另一种途径。
Propionic acid (PA) is widely used in the food, agricultural, and pharmaceutical industries. Since the petrochemical PA is unsustainable, biological production of PA from renewable substrates is gaining attention. In this study, we engineered the strain Pseudomonas putida KT2440 to transform l-threonine to PA with only CO2 released as by-product. The cell factory was created by chromosomal incorporation of heterologous l-threonine deaminase, permease, and acyl-CoA thioesterase, deletion of branch pathways as well as overproduction of the endogenous branched-chain alpha-keto acid dehydrogenase complex. The final engineered strain could produce 399 mM PA from 400 mM l-threonine in a batch biotransformation process, with a molar yield of 99.8% under the optimized conditions in 48 h. The PA titer further reached to 50.3 g/L (679 mM) with a productivity of 0.6 g/L/h in a fed-batch conversion process. No obvious by-products, such as acetate and succinate, were detected in the broth, which would significantly facilitate downstream purification steps. Thus, this study offers an alternative route for biological production of PA.