Abstract
Nowadays, the use of sulfur dioxide (SO2) during the winemaking process is a controversial societal issue. In order to reduce its use, various alternatives are emerging, in particular bioprotection by adding yeasts, with different impacts on yeast microbiota in early winemaking stages. In this study, quantitative-PCR and metabarcoding high-throughput sequencing (HTS) were combined with MALDI-TOF-MS to monitor yeast population dynamic and diversity in the early stages of red winemaking process without sulfites and with bioprotection by Torulaspora delbrueckii and Metschnikowia pulcherrima addition. By using standard procedures for yeast protein extraction and a laboratory-specific database of wine yeasts, identification at species level of 95% of the isolates was successfully achieved by MALDI-TOF-MS, thus confirming that it is a promising method for wine yeast identification. The different approaches confirmed the implantation and the niche occupation of bioprotection leading to the decrease of fungal communities (HTS) and Hanseniaspora uvarum cultivable population (MALDI-TOF MS). Yeast and fungi diversity was impacted by stage of maceration and, to a lesser extent, by bioprotection and SO2, resulting in a modification of the nature and abundance of the operational taxonomic units (OTUs) diversity.
Highlights
Yeast microbiota on the grape berry surface is the main source of the fermentative microbial community responsible for alcoholic fermentation and organoleptic quality of wine
Previous studies reported the impact of sulfur dioxide addition on wine microbial diversity [1,8,9,10] and the yeast population dynamic during alcoholic fermentation [11,12,13]
623 yeast clones isolated from the prefermentary stages and beginning of alcoholic fermentation were first identified using 26S rDNA sequencing
Summary
Yeast microbiota on the grape berry surface is the main source of the fermentative microbial community responsible for alcoholic fermentation and organoleptic quality of wine. Numerous studies have been carried out to characterize the yeast microbiota during the fermentation process. Different environmental factors (vintage, climate) [1] and technical parameters (temperature, carbon dioxide, inoculation with starters) can impact fungal diversity and population dynamics in grape must during the prefermentary stage [2,3,4]. Alcoholic fermentation [5,6,7]. Previous studies reported the impact of sulfur dioxide addition on wine microbial diversity [1,8,9,10] and the yeast population dynamic during alcoholic fermentation [11,12,13]. The impact of bioprotection, as an alternative to sulfites, on the microbial characteristics of wines has been considered [14,15]
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