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Utilization of delactosed whey permeate for the synthesis of ethyl acetate with Kluyveromyces marxianus
Applied Microbiology and Biotechnology ( IF 3.9 ) Pub Date : 2023-02-14 , DOI: 10.1007/s00253-023-12419-1
Andreas Hoffmann 1 , Alexander Franz 1, 2 , Thomas Walther 1 , Christian Löser 1
Affiliation  

Abstract

Ethyl acetate is an important organic solvent and currently produced from fossil carbon resources. Microbial synthesis of this ester from sugar-rich waste could be an interesting alternative. Therefore, synthesis of ethyl acetate by Kluyveromyces marxinanus DSM 5422 from delactosed whey permeate (DWP) was studied in an aerated stirred bioreactor at 40 °C. DWP is mainly composed of residual lactose and minerals. The minerals inhibited yeast growth, as witnessed by an increased lag period, a reduced growth rate, and an extended process duration. All experiments were therefore carried out with diluted DWP. In a series of batch experiments, the pH of iron-deficient DWP medium varied between 4.8 and 5.9. The pH of the cultivation medium significantly influenced cell growth and product syntheses, with the highest ethyl acetate yield of 0.347 g g–1 and lowest by-product formation achieved at pH 5.1. It is likely that this effect is due to pH-dependent iron chelation, which affects the iron bioavailability and the intracellular iron content, thus affecting growth and metabolite synthesis. The viability of yeast cells was always high despite the harsh conditions in DWP medium, which enabled extended usage of the biomass in repeated-batch and fed-batch cultivations. These two culture techniques increased the volume of DWP processed per time by 32 and 84% for the repeated-batch and the fed-batch cultivation, respectively, without a drop of the ester yield.

Key points

• Delactosed whey permeate was converted to ethyl acetate with a high rate and yield.

• The formation of ethyl acetate in DWP medium at iron limitation is pH-dependent.

• Highly active yeasts from batch processes enabled extension as fed and repeated batch.

Graphical Abstract



中文翻译:

脱乳糖乳清渗透液在马克斯克鲁维酵母合成乙酸乙酯中的应用

摘要

乙酸乙酯是一种重要的有机溶剂,目前由化石碳资源生产。从富含糖分的废物中微生物合成这种酯可能是一种有趣的替代方法。因此,马克斯克鲁维酵母合成乙酸乙酯在 40 °C 的曝气搅拌生物反应器中研究了来自脱乳糖乳清渗透物 (DWP) 的 DSM 5422。DWP主要由残留的乳糖和矿物质组成。矿物质抑制酵母生长,表现为延迟期增加、生长速度降低和过程持续时间延长。因此,所有实验均使用稀释的 DWP 进行。在一系列分批实验中,缺铁 DWP 培养基的 pH 值在 4.8 和 5.9 之间变化。培养基的pH值显着影响细胞生长和产物合成,最高乙酸乙酯产量为0.347 g g –1在 pH 5.1 时副产物形成最少。这种效应很可能是由于 pH 依赖性铁螯合,影响铁的生物利用度和细胞内铁含量,从而影响生长和代谢物合成。尽管 DWP 培养基条件恶劣,但酵母细胞的活力始终很高,这使得生物质在重复分批和补料分批培养中的扩展使用成为可能。对于重复分批培养和补料分批培养,这两种培养技术将每次处理的 DWP 体积分别增加了 32% 和 84%,而酯产量没有下降。

关键点

• 脱乳糖乳清渗透物以高速率和产率转化为乙酸乙酯。

• 在铁限制条件下,DWP 培养基中乙酸乙酯的形成是pH 依赖性的。

• 来自分批过程的高活性酵母能够在补料和重复分批时进行延伸。

图形概要

更新日期:2023-02-14
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