Correlation between water activity (aw) and microbial epiphytic communities associated with grapes berries

Guilherme Eduardo Martins,Isabelle Masneuf-Pomarède,Laurence Geny,Aline Lonvaud,Jean-Pierre Da Costa,Cosimo Casini

doi:10.20870/oeno-one.2020.54.1.2435

Abstract

Grape berries host a complex microbial community that plays a predominant role in grape quality prior to harvest and in the winemaking process. Like other carpospheric habitats, the epiphytic microbial community of grape berries is influenced by several factors. Climate plays an essential role in grape composition and quality, and its impact on berry microbiota was recently demonstrated. However, there is still a lack of information about how environmental conditions influence the system in grape berries.In this study, the microbial communities of grape berries from two wine appellations characterized by specific climatological conditions were analyzed. The results revealed that the size of cultivable communities (bacteria, yeast and filamentous fungi) and the diversity and richness of the microbial community profiles were higher in vineyards found to have lower temperatures. The metabolic activity (Community-Level Physiological Profiles) of the epiphytic microbial community was lower in warm climates. Water activity (aw) had a positive effect on the cultivable population, on metabolic activity, and on microbial diversity.The results showed that the microclimate affects the microbial population associated with grape berries through the aw of grape skins.

Highlights

Grape berries sustain a complex microbial ecosystem that harbors a diverse array of bacteria, yeast and filamentous fungi, as reviewed by (Barata et al, 2012)
As with other carpospheric habitats, it is affected by several factors, including maturity stage (Rementeria et al, 2003; Martins, 2012), phytosanitary products (Comitini and Ciani, 2008; Cordero-Bueso et al, 2011; Martins et al, 2012; Setati et al, 2012), geographical location (Li et al, 2010; Taylor et al, 2014), grape variety (Sabate et al, 2002; Raspor et al, 2006), grape berry composition (Martins et al, 2014), and biotic factors such as Botrytis cinerea (Barbe et al, 2001; Nisiotou et al, 2011)
Iii) Because the grape samples were collected in real field conditions, and each farming system has its specificities that may influence the microbial population of grape berries, we decided to

Summary

Introduction

Grape berries sustain a complex microbial ecosystem that harbors a diverse array of bacteria, yeast and filamentous fungi, as reviewed by (Barata et al, 2012). The impact of the climate on bacterial and fungal species associated with grape berysurfaces has been previously established (Querol et al, 1990; Combina et al, 2005; Brilli et al, 2014; Paterson et al, 2018). It is a key component of environmental conditions involved in the viticulture concept called terroir (Leeuwen and Seguin, 2006). The grape berry maturation process is highly linked to climate conditions, impacting the concentration of sugars and acids, the polyphenol content, and other quality determinants such as the fruit’s phytosanitary status (Martin et al, 2016)

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