Utilization of delactosed whey permeate for the synthesis of ethyl acetate with Kluyveromyces marxianus

Research output: Contribution to journalResearch articleContributedpeer-review



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: [Figure not available: see fulltext.]


Original languageEnglish
Pages (from-to)1635-1648
Number of pages14
JournalApplied Microbiology and Biotechnology
Issue number5-6
Publication statusPublished - Feb 2023

External IDs

PubMed 36786916
PubMed PMC10006051
Scopus 85148019590
WOS 000933429000001
Mendeley ef740c78-29d0-3b9d-acca-250b9ed13f69



  • Delactosed whey permeate, Ethyl acetate, Fed-batch cultivation, Iron limitation, Repeated-batch cultivation, Whey Proteins/metabolism, Lactose/metabolism, Kluyveromyces/metabolism, Whey/metabolism, Iron/metabolism, Fermentation

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