Oenococcus oeni in Chilean Red Wines: Technological and Genomic Characterization

Area of Science:

• Microbiology
• Enology
• Genomics

Background:

• Lactic acid bacteria (LAB), particularly Oenococcus oeni, play a crucial role in malolactic fermentation (MLF) in winemaking.
• Understanding the diversity and characteristics of indigenous LAB is essential for optimizing wine quality and developing novel starter cultures.

Purpose of the Study:

• To investigate the presence, load, and genetic diversity of LAB, with a focus on Oenococcus oeni, in Chilean wineries.
• To characterize autochthonous O. oeni isolates based on technological performance and genomic traits for potential use as starter cultures.

Main Methods:

• PCR-RFLP and quantitative PCR (qPCR) were used to detect and quantify LAB species, especially O. oeni.
• Multilocus sequence typing (MLST) and whole-genome sequencing were employed for genetic and genomic analyses.
• Technological characterization included tests for ethanol tolerance, SO2 resistance, pH tolerance, and malic acid reduction.

Main Results:

• Oenococcus oeni was dominant (>85% bacterial load) in 80% of samples from Chilean wineries.
• Autochthonous O. oeni strains exhibited distinct genetic clusters compared to commercial strains.
• Three selected autochthonous isolates demonstrated robust technological performance, including malic acid reduction under challenging conditions (low pH, high ethanol, and SO2).
• Genomic analysis revealed high conservation of the malolactic enzyme and unique genes in autochthonous strains, differentiating them from commercial strains like VP41 and PSU-1.

Conclusions:

• Local Oenococcus oeni strains in Chile are genetically and genomically distinct from commercial starter cultures.
• These autochthonous strains possess favorable technological and genomic traits, indicating their significant potential for use as starter cultures in winemaking.
• Further research into the genomic contributions of these strains to wine's organoleptic properties is warranted.