BACKGROUND The GRAS and oleaginous yeast Yarrowia lipolytica (Y. lipolytica) is an attractive cell factory for the production of chemicals and biofuels. The production of many natural products of commercial interest have been investigated in this cell factory by introducing heterologous biosynthetic pathways and by modifying the endogenous pathways. However, since natural products anabolism involves long pathways and complex regulation, re-channelling carbon into the product of target compounds is still a cumbersome work, and often resulting in low production performance. RESULTS In this work, the carotenogenic genes contained carB and bi-functional carRP from Mucor circinelloides and carotenoid cleavage dioxygenase 1 (CCD1) from Petunia hybrida were introduced to Y. lipolytica and led to the low production of β-ionone of 3.5 mg/L. To further improve the β-ionone synthesis, we implemented a modular engineering strategy for the construction and optimization of a biosynthetic pathway for the overproduction of β-ionone in Y. lipolytica. The strategy involved the enhancement of the cytosolic acetyl-CoA supply and the increase of MVA pathway flux, yielding a β-ionone titer of 358 mg/L in shake-flask fermentation and approximately 1 g/L (~ 280-fold higher than the baseline strain) in fed-batch fermentation. CONCLUSIONS An efficient β-ionone producing GRAS Y. lipolytica platform was constructed by combining integrated overexpressed of heterologous and native genes. A modular engineering strategy involved the optimization pathway and fermentation condition was investigated in the engineered strain and the highest β-ionone titer reported to date by a cell factory was achieved. This effective strategy can be adapted to enhance the biosynthesis of other terpenoids in Y. lipolytica.

中文翻译：

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脂解耶氏酵母中β-紫罗兰酮高产的模块化途径工程策略。

背景技术GRAS和油性酵母解脂耶氏酵母（Y. lipolytica）是用于生产化学物质和生物燃料的有吸引力的细胞工厂。通过引入异源生物合成途径和修饰内源途径，已经在该细胞工厂中研究了许多具有商业价值的天然产物的生产。然而，由于天然产物的合成代谢涉及长的路径和复杂的调节，所以将碳重新引导到目标化合物的产物中仍然是繁琐的工作，并且常常导致生产性能低下。结果在这项工作中，致龋基因包含来自Mucor circinelloides的carB和双功能carRP，并将来自矮牵牛的类胡萝卜素裂解双加氧酶1（CCD1）引入解脂耶氏酵母中，导致β-紫罗兰酮的低产量3.5 mg / L 。为了进一步改善β-紫罗兰酮的合成，我们实施了模块化工程策略，以构建和优化解脂耶氏酵母中β-紫罗兰酮过量生产的生物合成途径。该策略涉及增加胞质乙酰辅酶A的供应和MVA途径通量的增加，在摇瓶发酵中产生358 mg / L的β-紫罗兰酮滴度，约为1 g / L（约是280倍）。分批补料发酵。结论通过整合过量表达的异源基因和天然基因，构建了高效的产β-紫罗兰酮的解脂耶氏酵母。涉及优化途径的模块化工程策略，并在工程菌株中研究了发酵条件，并达到了迄今为​​止由细胞工厂报告的最高β-紫罗兰酮滴度。