Application of directed evolution to develop ethanol tolerant Oenococcus oeni for more efficient malolactic fermentation
Application of directed evolution to develop ethanol tolerant Oenococcus oeni for more efficient malolactic fermentation
Malolactic fermentation (MLF) is an important step in winemaking, which can be notoriously unreliable due to the fastidious nature of Oenococcus oeni. This study aimed to use directed evolution (DE) to produce a more robust strain of O. oeni having the ability to withstand high ethanol concentrations. DE involves an organism mutating and potentially adapting to a high stress environment over the course of extended cultivation. A continuous culture of O. oeni was established and exposed to progressively increasing ethanol content such that after approximately 330 generations, an isolate from this culture was able to complete MLF in high ethanol content medium earlier than its parent. The ethanol tolerance of a single isolate, A90, was tested to confirm the phenotype and its fermentation performance in wine. In order to investigate the genotypic differences in the evolved strain that led to the ethanol tolerance phenotype, the relative expression of a number of known stress response genes was compared between SB3 and A90. Notably, there was increase in hsp18 expression in 20% (v/v) ethanol by both strains with A90 exhibiting a higher degree of expression. This study is the first to use directed evolution for O. oeni strain improvement and confirms that this technique can be used successfully for the development of new candidate strains for the wine industry. This study also adds to the current knowledge on the genetic basis of ethanol tolerance in this bacterium.
Directed evolution, Ethanol, Malolactic fermentation, Oenococcus, Stress response, Wine
921-932
Betteridge, Alice L.
8e9ccdb9-e0b4-4ec3-81cb-522409ecf7c1
Sumby, Krista M.
f54b8f1c-c29e-488b-ab5e-dbb9b2576ba9
Sundstrom, Joanna F.
6c6b3452-dfb3-4b5c-aa42-c721eed7b9bb
Grbin, Paul R.
e1cce428-cbfc-4cd2-aef0-c0e3a076a955
Jiranek, Vladimir
8e5a8dfd-f5b2-43e3-928b-11dff324abc7
1 January 2018
Betteridge, Alice L.
8e9ccdb9-e0b4-4ec3-81cb-522409ecf7c1
Sumby, Krista M.
f54b8f1c-c29e-488b-ab5e-dbb9b2576ba9
Sundstrom, Joanna F.
6c6b3452-dfb3-4b5c-aa42-c721eed7b9bb
Grbin, Paul R.
e1cce428-cbfc-4cd2-aef0-c0e3a076a955
Jiranek, Vladimir
8e5a8dfd-f5b2-43e3-928b-11dff324abc7
Betteridge, Alice L., Sumby, Krista M., Sundstrom, Joanna F., Grbin, Paul R. and Jiranek, Vladimir
(2018)
Application of directed evolution to develop ethanol tolerant Oenococcus oeni for more efficient malolactic fermentation.
Applied Microbiology and Biotechnology, 102 (2), .
(doi:10.1007/s00253-017-8593-x).
Abstract
Malolactic fermentation (MLF) is an important step in winemaking, which can be notoriously unreliable due to the fastidious nature of Oenococcus oeni. This study aimed to use directed evolution (DE) to produce a more robust strain of O. oeni having the ability to withstand high ethanol concentrations. DE involves an organism mutating and potentially adapting to a high stress environment over the course of extended cultivation. A continuous culture of O. oeni was established and exposed to progressively increasing ethanol content such that after approximately 330 generations, an isolate from this culture was able to complete MLF in high ethanol content medium earlier than its parent. The ethanol tolerance of a single isolate, A90, was tested to confirm the phenotype and its fermentation performance in wine. In order to investigate the genotypic differences in the evolved strain that led to the ethanol tolerance phenotype, the relative expression of a number of known stress response genes was compared between SB3 and A90. Notably, there was increase in hsp18 expression in 20% (v/v) ethanol by both strains with A90 exhibiting a higher degree of expression. This study is the first to use directed evolution for O. oeni strain improvement and confirms that this technique can be used successfully for the development of new candidate strains for the wine industry. This study also adds to the current knowledge on the genetic basis of ethanol tolerance in this bacterium.
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Published date: 1 January 2018
Additional Information:
Funding Information:
VJ conceived the project. ALB performed the DE, screening of isolates and fermentation experiments, and analysed the data. KMS performed qPCR experiments, and analysed and interpreted the data. JFS performed strain passaging and phenotype stability experiments and analysed the data. ALB, KMS and JFS wrote and edited the manuscript. PRG and VJ revised and edited the manuscript. ALB was supported by scholarships from AGWA (UA1101/P3102/GWR Ph 0901) and the University of Adelaide. KMS and JFS are supported by Wine Australia project funding (UA1302). The authors declare that they have no conflicts of interest.
Publisher Copyright:
© 2017, Springer-Verlag GmbH Germany.
Keywords:
Directed evolution, Ethanol, Malolactic fermentation, Oenococcus, Stress response, Wine
Identifiers
Local EPrints ID: 482628
URI: http://eprints.soton.ac.uk/id/eprint/482628
ISSN: 0175-7598
PURE UUID: 4f2020c5-d548-41f4-b61e-bcd167e292af
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Date deposited: 10 Oct 2023 17:01
Last modified: 18 Mar 2024 04:12
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Contributors
Author:
Alice L. Betteridge
Author:
Krista M. Sumby
Author:
Joanna F. Sundstrom
Author:
Paul R. Grbin
Author:
Vladimir Jiranek
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