What is a “Microbiome” and How Does it Relate to Wine?

What exactly is a microbiome?

The terms “microbiome” and “microbiota” are often used interchangeably, but they refer to different aspects of microbial communities in specific environments, such as the human body or the soil of a vineyard.

Microbiota refers to the totality of microorganisms, including bacteria, fungi, yeasts, and viruses, that inhabit a specific ecological niche. It focuses on the organisms themselves rather than their genetic material.

Microbiome, on the other hand, refers to the collective genetic material of all microorganisms in a particular environment. This encompasses not just the microorganisms themselves, but also their genes and their interactions within their host environment. The microbiome offers a broader perspective of microbial communities by incorporating their genetic diversity and ecological functions.

Microbiomics is the science that deals with the collective characterization and quantification of molecules responsible for the structure, function, and dynamics of a microbial community. It employs techniques such as high-throughput sequencing, bioinformatics, and systems biology approaches to study microbial communities and their interactions with their hosts. The field has wide applications, including in human health, agriculture, and environmental sciences.

How is this related to wine?

The vineyard microbiome plays a crucial role in shaping the unique characteristics of wines. The microbiome of the soil, vine, and grapes influences the health and growth of the vine, as well as the composition of the grapes. The grape microbiome determines the fermentation microbiome and the character of what ultimately lands in your glass.

Vineyard soils, the foundation of wine character

Soils host some of the most diverse microbiomes on Earth. Studies show that different microbiomes in vineyard soils contribute to variations in grape composition and wine terroir. This occurs through the reaction of vines to the soil microbiome or through the soil microbiome affecting the grape microbiome and thus fermentation. An example is an Australian study showing differences in bacterial and fungal communities in various zones of the same vineyard correlated with high and low concentrations of Rotundone in grape berries. Rotundone is an aroma compound often found in cool climate Shiraz.

Different abiotic factors such as geographical origin, climatic conditions, soil composition, and cultivation methods can influence the vineyard soil microbiome. Interestingly, certain biotic factors also play a significant role, with certain soil fungi exerting strong selection on bacteria through the production of antimicrobial compounds.

The health of the soil is paramount, not only for viticulture but for all agricultural systems. The soil microbiome is a critical component of soil health. Understanding how agricultural systems, including viticulture, impact the soil microbiome is vital for sustainable agriculture.

Vines, guardians of wine character

Various factors can influence the microbiome of the vines. Vineyard location, cultivation systems, and grape variety are among these factors. A study on Cabernet Sauvignon grapes across four countries with different climates suggested that grape varieties may have unique microbial signatures. Beneficial microorganisms can promote vine health by suppressing the growth of pathogenic organisms and enhancing plant disease resistance.

Studying the microbiome in vineyards

Investigating the grape and fermentation microbiome, along with the factors influencing it, can provide winemakers with tools to positively steer fermentation and prevent issues such as stuck fermentations.

Diversity for a sustainable future

The agricultural sector faces significant challenges in feeding a growing global population. Intensive farming systems based on mineral fertilizers negatively affect biodiversity, and wine production is no exception. Studying microorganisms in vineyards reveals their essential contribution to the function and sustainability of viticultural systems. Microorganisms play a key role in promoting optimal outcomes, influencing soil health, vine vitality, fermentation, and the sensory profile of a wine. Their complex interplay with the surrounding environment brings several benefits, including enhanced product quality and vineyard resilience to adverse conditions. Understanding the factors that influence microbiome distribution and microbial diversity is crucial for leveraging natural ecosystems in quality wine production.

By Karien O’Kennedy