Microflora variability among grape musts in Languedoc: the case of two grape varieties during two years
Variabilité de la flore microbienne de mouts de raisins en Languedoc : Le cas de deux variétés durant deux millésimes
Résumé
Introduction and objectives
The wine fermentation ecosystem is very likely one of the most explored microbial ecosystem since the pioneer work of Pasteur. Microbiology has considerably evolved since these ancient, and recent metabarcoding based studies have renewed its vision. However, very few studies combine metabarcoding analyses to culture-based making as well these microbial genetic resources available. In addition, we many recent works suggested that the non-saccharomyces component of grape must microflora impacts wine quality. In this context, we undertook the characterization of two grape must varieties by combining metabarcoding analyses and cultural approach on two subsequent years.
Material and Methods
We analysed by metabarcoding approach (amplification and sequencing of the 16S rDNA V4 region for bacteria, and of the ITS1 region for fungi) microbial fraction of grape must microbiote. A total of 20 samples of two grape varieties, Sauvignon Blanc and Viognier were collected in South of France located close to Montpellier and Narbonne in 2015 and 2016 from 11 and 9 sites respectively. These samples were analyzed in parallel by culture-based approach with numeration of bacteria and yeast with selected medium and subsequent isolation and identification of microorganisms of interest.
Results and discussion
In this work, metabarcoding analysis showed the clear impact of millesime on both yeast and bacteria composition of grape must. We could not evidence a global regional factor from the grape must microflora. The culture-based approach did not enable us to highlight the influence of the different factors on the microflora, by the way it confirmed the prevalence of ubiquist of grape must species such as Lactobacillus plantarum and Kozakia baliensis for bacteria or Hanseniaspora uvarum for yeast. Moreover it allows us to constitute a free access reference collection for bacteria and yeast associated to grape must for more insightful studies. Strains are currently available at INRAE BRCs CIRM-BIA (https://collection-cirmbia.fr/) and CIRM-Levure (https://cirm-levures.bio-aware.com/) respectively.
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