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Identification of multiple-derived peptides produced by Saccharomyces cerevisiae involved in malolactic fermentation
Ziad Rizk1, Youssef El Rayess2, Chantal Ghanem1
1Lebanese Agricultural Research Institute (LARI)- Fanar Station- P.O. Box 90-1965, Jdeidet El-Metn Fanar- Lebanon.
Abstract:
An oenological strain of Saccharomyces cerevisiae was previously shown to produce a 5-10 kDa peptidic fraction responsible for the inhibition of malolactic fermentation (MLF). In the present study, we aim to further purify the anti-MLF peptides of this fraction. The yeast fermented synthetic grape juice medium was fractionated by ammonium sulfate precipitation combined with ultrafiltration. The 5-10 kDa fraction recovered at a saturation degree of 60%-80% was the only fraction that inhibited both the bacterial growth and the malate consumption in vivo. It also inhibited the malolactic enzyme activity in vitro at a pH range between 3.5 and 6.7. Therefore, it was purified by both anion and cation exchange chromatography. The eluates that inhibited the malolactic enzyme activity in vitro were migrated on Tricine SDS-PAGE and the protein bands were excised and sequenced by LC-MS/MS. The sequencing revealed nine peptides originating from eight proteins of S. cerevisiae. Two GAPDH cationic fragments of 0.9 and 1.373 kDa having a pI of 10.5 and 11 respectively, Wtm2p and Utr2p anionic fragments of 2.42 kDa with a pI of 3.5 and 4 respectively were thought to contribute the most to the MLF inhibition.
Insights
Researchers identified specific yeast peptides that inhibit malolactic fermentation (MLF). These peptides, derived from Saccharomyces cerevisiae proteins like GAPDH, Wtm2p, and Utr2p, offer potential for controlling MLF in winemaking.
Area of Science:
- Oenology
- Microbiology
- Biochemistry
Background:
- A specific yeast peptide fraction from Saccharomyces cerevisiae inhibits malolactic fermentation (MLF).
- Further purification of these anti-MLF peptides is necessary to understand their mechanism.
Purpose of the Study:
- To purify and identify the specific peptides responsible for inhibiting malolactic fermentation (MLF).
- To characterize the inhibitory properties of these peptides on bacterial growth and malolactic enzyme activity.
Main Methods:
- Fractionation using ammonium sulfate precipitation and ultrafiltration.
- Purification via anion and cation exchange chromatography.
- Peptide identification using Tricine SDS-PAGE and LC-MS/MS sequencing.
Main Results:
- A 5-10 kDa fraction strongly inhibited bacterial growth and malate consumption in vivo.
- This fraction also inhibited malolactic enzyme activity across a broad pH range (3.5-6.7).
- LC-MS/MS identified nine peptides from eight S. cerevisiae proteins, with specific GAPDH, Wtm2p, and Utr2p fragments implicated in MLF inhibition.
Conclusions:
- Specific peptides from Saccharomyces cerevisiae, including fragments of GAPDH, Wtm2p, and Utr2p, are responsible for inhibiting malolactic fermentation (MLF).
- These identified peptides provide targets for controlling MLF in winemaking processes.
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