Malolactic fermentation is far more than an acid adjustment. As lactic acid bacteria consume malic acid, they also release a cascade of metabolic byproducts that shape a wine’s aroma, mouthfeel, and stability. Diacetyl contributes buttery notes, esters modulate fruit expression, and the bacteria’s enzymatic machinery can either enhance or strip away desirable volatile compounds. The choice of which bacterium performs this transformation is therefore one of the most consequential decisions a winemaker makes, and the industry’s reliance on a narrow genetic pool has long struck researchers as both a limitation and an opportunity.

The research team, led by Carla Vargas-Luna of the Pontificia Universidad Católica de Chile, focused on two indigenous strains: Levilactobacillus brevis BCV-46 and Levilactobacillus brevis C18, both isolated from Chilean grapes. They compared these against a commercial Lactiplantibacillus plantarum strain, a species that has emerged in recent years as the leading alternative to Oenococcus oeni. The experiments were conducted at microvinification scale, using four-liter fermentations of Chardonnay must, with each bacterial strain co-inoculated alongside Saccharomyces cerevisiae, the yeast responsible for the primary alcoholic fermentation. This co-inoculation strategy, in which yeast and bacteria are introduced together rather than sequentially, is gaining favor because it shortens production schedules and reduces the risk of spontaneous bacterial growth between fermentations.

A central concern in any such experiment is whether the bacteria will interfere with the yeast’s work. Alcoholic fermentation depends on Saccharomyces cerevisiae converting sugars to ethanol efficiently and completely, and some lactic acid bacteria produce compounds that inhibit yeast metabolism. The researchers found encouraging news on this front: co-inoculation did not impair alcoholic fermentation in any of the treatments. The yeast completed its task regardless of which bacterial companion was present, confirming that these native strains are compatible with standard winemaking yeast at the timing and conditions tested.

The malolactic conversion itself, however, proved more uneven. Only partial malolactic fermentation occurred across the trials, and the degree of malic acid degradation varied substantially by strain. The commercial Lactiplantibacillus plantarum achieved the highest level of malic acid breakdown, demonstrating why it has become the benchmark alternative starter. Among the native strains, Levilactobacillus brevis BCV-46 outperformed its compatriot C18 in acid conversion. The incomplete fermentation suggests that these strains, while viable, may require further optimization of inoculation timing, cell density, or nutritional conditions to fully complete the acid conversion in white wines, which are generally a harsher environment for lactic acid bacteria than reds due to lower pH, higher acidity, and fewer nutrients.

Despite the partial conversion, the chemical differences among the wines were measurable and meaningful. The researchers documented variations in chemical composition across the treatments, though all wines remained within acceptable enological limits, meaning none of the bacterial interventions pushed the wines outside the ranges considered sound and stable for commercial production. This is a nontrivial finding, because lactic acid bacteria can consume residual sugars, produce acetic acid, or alter pH in ways that compromise wine integrity. The native strains passed this basic quality threshold, establishing their fundamental suitability for further development.

The safety dimension of the study produced the sharpest contrast between the two native isolates. Biogenic amines, including histamine, tyramine, and putrescine, are nitrogen-containing compounds that some lactic acid bacteria generate by decarboxylating amino acids. At elevated concentrations, these amines can trigger headaches, flushing, and blood pressure changes in sensitive individuals, and histamine in particular is regulated in some markets. Using molecular screening, the researchers searched for the amino acid decarboxylase genes that confer the ability to produce these compounds. The genes were detected only in L. brevis C18, and correspondingly, wines fermented with that strain showed higher concentrations of tyramine and putrescine. The other strains, including BCV-46 and the commercial L. plantarum, did not carry the decarboxylase genes and did not elevate these amines.

This single genetic distinction transforms the practical outlook for the two native strains. BCV-46 emerges as a candidate worth pursuing: it degraded malic acid respectably, left the wine chemically sound, and carried no detectable amine-producing potential. C18, by contrast, would require careful evaluation before any commercial use, since its amine production represents a genuine food safety consideration. The finding underscores a principle that wine microbiologists have emphasized repeatedly: safety and quality traits are strain-dependent rather than species-dependent, and each candidate starter must be individually characterized before deployment.

Perhaps the most appealing results came from the sensory analysis. The wines produced with different bacterial strains developed significantly different sensory profiles, and the selected native strains enhanced floral, fruity, and creamy attributes in the Chardonnay. These are precisely the aromatic dimensions that white wine consumers prize, and the fact that indigenous Latin American strains could amplify them hints at a strategy for producing wines with a genuine sense of place. Regional microbial biodiversity, long dismissed as a source of unpredictable spoilage, may instead be a reservoir of distinctive flavor signatures that commercial starter cultures cannot replicate.

The broader significance of the work lies in its demonstration that the next generation of malolactic starter cultures may come from vineyards far removed from the traditional wine heartlands of Europe. As climate change alters growing conditions and winemakers worldwide seek to differentiate their products, native bacterial strains offer a dual advantage: adaptation to local conditions and the potential for unique sensory contributions. The Chilean and Mexican research groups behind this study have shown that careful screening, combining fermentation performance testing, chemical analysis, sensory evaluation, and genetic safety checks, can identify which native strains deserve investment and which should be left in the vineyard. For now, the commercial Lactiplantibacillus plantarum still leads in acid conversion, but the native BCV-46 strain has staked its claim as a safe, flavor-enhancing alternative, and the race to domesticate Latin America’s wine microbiome has only begun.

Subject of Research: Non-Oenococcus lactic acid bacteria as malolactic fermentation starters in Chardonnay wine

Article Title: Latin-American non-Oenococcus lactic acid bacteria in Chardonnay wine: effects on chemical composition, sensory profile, and biogenic amine production

Article References: Vargas-Luna, C., Franco, W., Arvizu-Medrano, S., Cortés-Herrera, C., Redondo-Solano, M., Barboza-Vargas, N., Godoy-Olivares, L., & Miranda-Castilleja, D. (2026). Latin-American non-Oenococcus lactic acid bacteria in Chardonnay wine: effects on chemical composition, sensory profile, and biogenic amine production. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02330-6

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02330-6

Keywords: malolactic fermentation, Chardonnay, lactic acid bacteria, Lactiplantibacillus plantarum, Levilactobacillus brevis, biogenic amines, wine microbiology, co-inoculation, Saccharomyces cerevisiae, sensory profile, food safety, Latin America

The research team set out to answer a question that has long frustrated plant pathologists and viticulturists alike: why do some grapevine cultivars tolerate infection by trunk disease fungi while others succumb, even though no grapevine genotype is fully resistant? Tolerance in this context is measured by the expression of foliar symptoms, which varies considerably among cultivars, yet the biochemical mechanisms underlying this variation have remained poorly understood. To probe the question, the researchers chose two cultivars with well-documented contrasting responses to Botryosphaeria dieback: Chardonnay, which shows greater tolerance, and Gewurztraminer, which is more susceptible. By comparing how these two cultivars reconfigure their chemistry after infection, the team hoped to identify the metabolic signatures that separate a resilient vine from a vulnerable one.

The experimental design was ambitious in scope. Rather than examining only the infection site in the woody stem, as most earlier studies have done, the researchers conducted whole-plant metabolomic analyses, sampling wood, leaves and roots at different times after inoculation. They used untargeted liquid chromatography coupled with mass spectrometry, a technique that allows scientists to detect and measure thousands of small molecules simultaneously without knowing in advance which ones will prove important. This unbiased approach is critical when studying complex plant-pathogen interactions, because defense chemistry often involves unexpected compounds and pathways that a targeted analysis would miss entirely.

A key feature of the study was the use of two different N. parvum isolates that differ in aggressiveness. Pathogen colonization assays confirmed that the two isolates possessed contrasting wood invasion capacities, with one spreading more extensively through the host tissue than the other. This distinction mattered: it allowed the researchers to separate the effects of the plant cultivar from the effects of the fungal strain, revealing that the outcome of infection depends on the specific pairing of host and pathogen rather than on a generic interaction between grapevine and wood-decay fungus. The two isolates used in the work were designated Np.Bt67 and Np.Bourgogne, and their differing behavior in the wood provided a natural experiment in fungal virulence.

When the team analyzed the resulting metabolomic data using principal component analysis, a statistical method that reveals the dominant sources of variation in large datasets, a clear pattern emerged. The cultivar of the vine and the identity of the fungal isolate were the main factors structuring metabolic variation across the experiment, with additional contributions from the organ being sampled and the time elapsed since inoculation. In other words, the chemical state of a vine after infection is not determined by the fungus alone or the plant alone, but by the interplay between a particular cultivar and a particular fungal isolate, modulated by where in the plant one looks and how long the infection has had to develop.

The most striking differences appeared in the wood, the primary battleground between vine and pathogen. In response to the most aggressive isolate, the two cultivars mounted clearly distinct metabolic responses, particularly in their profiles of stilbenes and oxylipins. Stilbenes are a family of phenolic compounds, including the famous resveratrol, that grapevines synthesize as antifungal weapons, and their production is governed by enzymes such as stilbene synthase and the upstream phenylalanine ammonia-lyase, both central players in plant defense. Oxylipins, by contrast, are oxygenated derivatives of fatty acids produced through the lipoxygenase pathway, and they serve as both antimicrobial compounds and signaling molecules that coordinate defense responses across the plant.

Here the tolerant cultivar revealed its hand. Compared with Gewurztraminer, Chardonnay showed a faster and stronger induction of stilbene and fatty acid synthesis in its wood, especially of oxylipins, compounds that could be involved in both direct defense and long-distance signaling. This rapid chemical mobilization suggests that the tolerant vine does not simply produce more of the right compounds at the end of the battle; it activates its defensive chemistry earlier and more vigorously, potentially slowing the pathogen before it can establish a firm foothold. Notably, the study found that pathogen growth was similar between the two cultivars, meaning that the difference in tolerance cannot be explained by the fungus simply growing more slowly in Chardonnay. Instead, the two cultivars are characterized by specific metabolite signatures, especially in the wood, pointing to fundamentally different interaction mechanisms rather than a common response to wood decay.

Perhaps the most surprising finding came from beyond the infection site. The researchers observed that leaves and roots also exhibited early metabolic adjustments after the fungus was introduced into the wood, and these systemic changes were more pronounced in Chardonnay than in Gewurztraminer. This indicates that the tolerant cultivar mounts a rapid whole-plant response, reprogramming its metabolism far from where the pathogen is actually attacking. Such systemic metabolic reprogramming may reduce the overall impact of infection on host tissues, priming distant organs to cope with the physiological disruption that trunk disease causes as it progresses. The finding challenges the conventional focus on the wood alone and suggests that the fate of an infected vine is decided, in part, by how quickly the entire plant can reorganize itself.

The broader implications of this work extend into viticulture and breeding. Grapevine trunk diseases are increasingly concerning in the context of climate change, and with no fully resistant genotypes available, growers currently rely on costly and labor-intensive management practices, including the surgical removal of infected wood and the replanting of dead vines. Understanding the metabolic basis of tolerance could eventually help breeders select for cultivars with the rapid stilbene and oxylipin responses seen in Chardonnay, or guide the development of treatments that stimulate these pathways in susceptible varieties. The study also underscores that fungal isolate matters as much as host cultivar, which means that breeding and protection strategies may need to account for the local diversity of Botryosphaeriaceae populations in vineyards.

By integrating pathogen colonization data with untargeted metabolomics across three organs, two cultivars, two fungal isolates and multiple time points, the research provides a more integrated view of grapevine responses to Botryosphaeriaceae infection than has previously been available. The work, conducted at the Université de Haute Alsace with plants supplied by INRAE UMR SVQV in Colmar, France, and supported by the French Ministry of Higher Education and Research, demonstrates that tolerance to trunk disease is not a single trait but a dynamic, system-wide chemical performance. As vineyards face mounting pressure from a warming climate and evolving pathogen communities, studies like this one bring the field closer to understanding why some vines endure what destroys others, and how that resilience might one day be engineered or bred into the varieties the wine world depends on.

Subject of Research: Metabolomic responses of tolerant and susceptible grapevine cultivars to infection by the trunk disease fungus Neofusicoccum parvum

Article Title: Whole plant metabolomic analysis reveals contrasted responses in tolerant and susceptible grapevine cultivars to infection with different isolates of Neofusicoccum parvum, a major trunk disease fungus

Article References: Grau, A. L., Lacrampe, N., Goddard, M.-L., & Chong, J. (2026). Whole plant metabolomic analysis reveals contrasted responses in tolerant and susceptible grapevine cultivars to infection with different isolates of Neofusicoccum parvum, a major trunk disease fungus. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09951-3

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09951-3

Keywords: grapevine, Neofusicoccum parvum, Botryosphaeria dieback, grapevine trunk diseases, metabolomics, stilbenes, oxylipins, plant defense, Chardonnay, Gewurztraminer, fungal pathogen, viticulture