Oenococcus oeni Exopolysaccharide Biosynthesis, a Tool to Improve Malolactic Starter Performance

Area of Science:

• Enology
• Food Microbiology
• Wine Science

Background:

• Oenococcus oeni is crucial for malolactic fermentation (MLF) in wine, impacting microbial stability and sensory profiles.
• Controlling MLF remains challenging despite O. oeni's adaptation mechanisms.
• Previous studies linked polysaccharides to improved starter survival and shelf-life.

Purpose of the Study:

• To investigate the impact of wine-relevant stressors on O. oeni exopolysaccharide (EPS) production.
• To analyze the transcriptional regulation of EPS synthesis genes.
• To optimize conditions for EPS production for improved malolactic starter cultures and MLF efficiency.

Main Methods:

• Exposure of O. oeni to individual wine stressors (pH, ethanol).
• Measurement of specific exopolysaccharide (EPS) production rates.
• Quantitative analysis of EPS gene transcription in different O. oeni strains.
• Evaluation of optimized conditions for freeze-dried starter production, acclimation, and MLF performance.
• Sensory analysis of wines produced using optimized starters.

Main Results:

• Exopolysaccharide (EPS) production rates significantly increased under stress conditions (pH, ethanol).
• Differential transcription of EPS synthesis genes was observed across various O. oeni strains.
• Identified optimal conditions for EPS stimulation were applied to starter culture production and acclimation.
• Enhanced starters demonstrated improved malolactic fermentation (MLF) efficiency.

Conclusions:

• Wine stressors like pH and ethanol positively regulate EPS production in O. oeni.
• Understanding and manipulating EPS synthesis can lead to more robust malolactic starters.
• Optimized EPS production contributes to enhanced MLF performance and potentially improved wine sensory characteristics.