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J Biosci Bioeng. 2018 Aug;126(2):183-188. doi: 10.1016/j.jbiosc.2018.02.008. Epub 2018 Apr 22.

Metabolomics approach to reduce the Crabtree effect in continuous culture of Saccharomyces cerevisiae.

Author information

1
KOHJIN Life Sciences Co., Ltd., 1-6 Higashihama, Saiki, Oita 876-8580, Japan; Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: makoto.imura@kohjinls.com.
2
KOHJIN Life Sciences Co., Ltd., 1-6 Higashihama, Saiki, Oita 876-8580, Japan. Electronic address: ryo.iwakiri@kohjinls.com.
3
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Electronic address: bamba@bioreg.kyushu-u.ac.jp.
4
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: fukusaki@bio.eng.osaka-u.ac.jp.

Abstract

The budding yeast Saccharomyces cerevisiae is an important microorganism for fermentation and the food industry. However, during production, S. cerevisiae commonly uses the ethanol fermentation pathway for glucose utilization if excess sugar is present, even in the presence of sufficient oxygen levels. This aerobic ethanol fermentation, referred to as the Crabtree effect, is one of the most significant reasons for low cell yield. To weaken the Crabtree effect in fed-batch and continuous culture, sugar flow should be limited. In addition, in continuous culture, the dilution rate must be reduced to avoid washing out cells. However, under such conditions, production speed might be sacrificed. It is difficult to solve this problem with the tradeoff between cell yield and production speed by using conventional tactics. However, a metabolomics approach may be an effective way to search for clues regarding metabolic modulation. Therefore, the purpose of this study was to reduce ethanol production in continuous culture of S. cerevisiae at a higher dilution rate through a metabolomics approach. We used a metabolomics analysis to identify metabolites that were drastically increased or decreased in continuous culture when the dilution rate shifted from biomass formation to ethanol fermentation. The individual addition of two of the selected metabolites, fumaric acid and malic acid, reduced ethanol production at a higher dilution rate. This result demonstrates the potential for using metabolomics approaches to identify metabolites that reduce ethanol production in continuous culture at high dilution rates.

KEYWORDS:

Continuous culture; Crabtree effect; Ethanol reduction; Metabolomics; Saccharomyces cerevisiae

PMID:
29685822
DOI:
10.1016/j.jbiosc.2018.02.008
[Indexed for MEDLINE]

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