发酵产泡性能降低的解脂耶氏酵母菌株的获得及其评价

Construction and characterization of Yarrowia lipolytica strain with reduced foaming ability

摘要:

微生物发酵过程中泡沫的产生是发酵领域遇到的共性问题。在不影响发酵性能的前提下抑制菌株的产泡，对简化操作以及降低发酵成本具有较为重要的意义。解脂耶氏酵母(Yarrowia lipolytica，之前称为Candida lipolytica)是一种常用的合成生物学底盘，也是合成赤藓糖醇等功能糖醇的生产菌株。但在发酵合成赤藓糖醇的过程中会产生大量的泡沫，需要添加消泡剂以消除泡沫。【目的】本研究旨在开发一种产泡能力显著降低的解脂耶氏酵母新菌株，以减少赤藓糖醇发酵过程中消泡剂的添加。【方法】本研究利用解脂耶氏酵母中非同源靶向重组占支配地位的原理，采用一段外源DNA随机插入基因组的手段，随机突变基因组，改变菌株的发酵产泡性能，使突变株在发酵过程中不产泡或者降低其产泡的能力。【结果】通过筛选，获得一株在发酵过程中产泡性能显著降低的工程菌株，该菌株在保留高效合成赤藓糖醇性能的同时，显著降低了泡沫的产生。【结论】所获得的菌株对工业发酵合成赤藓糖醇具有较为重要的意义，也为控制其他微生物发酵过程中泡沫的生成提供了思路。

Abstract:

Foaming is a common problem during fermentation. Inhibiting foaming is of great significance for simplifying operation and reducing fermentation cost. Yarrowia lipolytica is a commonly used starting yeast in synthetic biology and for the synthesis of erythritol and other functional sugar alcohols. However, massive foam is produced in the fermentation for the production of erythritol, which needs to be eliminated by defoamers. [Objective] To develop a Y. lipolytica strain with significantly reduced foaming ability, so as to reduce the addition of defoamer in erythritol production. [Methods] According to the principle that non-homologous end joining (NHEJ) is dominant in Y. lipolytica genome recombination, we randomly inserted an artificial DNA fragment into the genome to produce the mutants with reduced or no foaming ability in the fermentation for erythritol production. [Results] After screening, we obtained a mutant without foaming during the fermentation in flask, 50 L pilot reactor, and industrial 75 m³ fermentor. [Conclusion] This mutant obtained can efficiently synthesize erythritol from high-concentration glucose as does the parental strain while producing less foam. The method to obtain defoaming mutant can provide valuable reference for the engineering of other microorganisms.