Replacement of the initial steps of ethanol metabolism in Saccharomyces cerevisiae by ATP-independent acetylating acetaldehyde dehydrogenase

Barbara U. Kozak, Harmen M. van Rossum, Matthijs S. Niemeijer, Marlous van Dijk, Kirsten Benjamin, Liang Wu, Jean Marc G Daran, Jack T. Pronk, Antonius J A van Maris

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
38 Downloads (Pure)

Abstract

In Saccharomyces cerevisiae ethanol dissimilation is initiated by its oxidation and activation to cytosolic acetyl-CoA. The associated consumption of ATP strongly limits yields of biomass and acetyl-CoA-derived products. Here, we explore the implementation of an ATP-independent pathway for acetyl-CoA synthesis from ethanol that, in theory, enables biomass yield on ethanol that is up to 40% higher. To this end, all native yeast acetaldehyde dehydrogenases (ALDs) were replaced by heterologous acetylating acetaldehyde dehydrogenase (A-ALD). Engineered Ald- strains expressing different A-ALDs did not immediately grow on ethanol, but serial transfer in ethanol-grown batch cultures yielded growth rates of up to 70% of the wild-type value. Mutations in ACS1 were identified in all independently evolved strains and deletion of ACS1 enabled slow growth of non-evolved Ald- A-ALD strains on ethanol. Acquired mutations in A-ALD genes improved affinity-Vmax/Km for acetaldehyde. One of five evolved strains showed a significant 5% increase of its biomass yield in ethanol-limited chemostat cultures. Increased production of acetaldehyde and other by-products was identified as possible cause for lower than theoretically predicted biomass yields. This study proves that the native yeast pathway for conversion of ethanol to acetyl-CoA can be replaced by an engineered pathway with the potential to improve biomass and product yields.

Original languageEnglish
Article numberfow006
Number of pages15
JournalFEMS Yeast Research
Volume16
Issue number2
DOIs
Publication statusPublished - 2016

Keywords

  • Acetyl-CoA
  • Energetics
  • Evolutionary engineering
  • Intracellular metabolites
  • Precursor supply
  • Yeast

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