丙酮
运动发酵单胞菌
代谢工程
生物化学
乙酰乳酸合酶
辅因子
化学
生物
乙醇燃料
发酵
基因
酶
作者
Weiwei Bao,Wei Shen,Qiqun Peng,Jun Du,Shihui Yang
出处
期刊:Fermentation
[MDPI AG]
日期:2023-01-25
卷期号:9 (2): 113-113
被引量:8
标识
DOI:10.3390/fermentation9020113
摘要
Biorefinery to produce value-added biochemicals offers a promising alternative to meet our sustainable energy and environmental goals. Acetoin is widely used in the food and cosmetic industries as taste and fragrance enhancer. The generally regarded as safe (GRAS) bacterium Zymomonas mobilis produces acetoin as an extracellular product under aerobic conditions. In this study, metabolic engineering strategies were applied including redistributing the carbon flux to acetoin and manipulating the NADH levels. To improve the acetoin level, a heterologous acetoin pathway was first introduced into Z. mobilis, which contained genes encoding acetolactate synthase (Als) and acetolactate decarboxylase (AldC) driven by a strong native promoter Pgap. Then a gene encoding water-forming NADH oxidase (NoxE) was introduced for NADH cofactor balance. The recombinant Z. mobilis strain containing both an artificial acetoin operon and the noxE greatly enhanced acetoin production with maximum titer reaching 8.8 g/L and the productivity of 0.34 g∙L−1∙h−1. In addition, the strategies to delete ndh gene for redox balance by native I-F CRISPR-Cas system and to redirect carbon from ethanol production to acetoin biosynthesis through a dcas12a-based CRISPRi system targeting pdc gene laid a foundation to help construct an acetoin producer in the future. This study thus provides an informative strategy and method to harness the NADH levels for biorefinery and synthetic biology studies in Z. mobilis.
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