Complexity and dynamics of the winemaking bacterial communities in berries, musts, and wines from apulian grape cultivars through time and space

Currently, there is very little information available regarding the microbiome associated with the wine production chain. Here, we used an amplicon sequencing approach based on high-throughput sequencing (HTS) to obtain a comprehensive assessment of the bacterial community associated with the production of three Apulian red wines, from grape to final product. The relationships among grape variety, the microbial community, and fermentation was investigated. Moreover, the winery microbiota was evaluated compared to the autochthonous species in vineyards that persist until the end of the winemaking process. The analysis highlighted the remarkable dynamics within the microbial communities during fermentation. A common microbial core shared among the examined wine varieties was observed, and the unique taxonomic signature of each wine appellation was revealed. New species belonging to the genus Halomonas were also reported. This study demonstrates the potential of this metagenomic approach, supported by optimized protocols, for identifying the biodiversity of the wine supply chain. The developed experimental pipeline offers new prospects for other research fields in which a comprehensive view of microbial community complexity and dynamics is desirable.Peer ReviewedPostprint (published version

Ecology and technological capability of lactic acid bacteria isolated during Grillo grape vinification in the Marsala production area.

Grapes of “Grillo” variety, used to produce Marsala wine, were harvested from five vineyards different for climatic and agronomic parameters, in order to obtain a first mapping of lactic acid bacteria (LAB) inhabiting the production area. Marsala base wine production was followed at large-scale and two experimental vinifications, different for lysozyme and SO2 concentration and combination, were carried out at pilot-plant scale. LAB communities and conventional chemical parameters were periodically analysed. LAB were found on grapes at an average concentration of about 102 CFU g-1 which decreased during the transformation process. A total of 146 colonies were collected, but only 35 were recognized as presumptive LAB. On the basis of phenotypic differences and isolation source, 16 isolates were then subjected to genotypic identification and gathered into the following species: Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Enterococcus faecium, Leuconostoc fallax and Sporalactobacillus nakayamae subsp. nakayamae. Lactococcus lactis subsp. lactis strains was the species most frequently isolated during winemaking showing the highest resistance to SO2 and lysozyme

Détection de bactéries lactiques produisant du 3-hydroxypropionaldéhyde (précurseur d'acroléine) à partir du glycérol par tests moléculaires

National audienc

Hydroxycinnamic acid decarboxylase activity of Brettanomyces bruxellensis involved in volatile phenol production: Relationship with cell viability

International audienceBrettanomyces bruxellensis populations have been correlated with an increase in phenolic off-flavors in wine. The volatile phenols causing the olfactory defect result from the successive decarboxylation and reduction of hydroxycinnamic acids that are normal components of red wines. The growth of B. bruxellensis is preventable by adding sulfur dioxide (SO(2)), with variable effectiveness. Moreover, it was hypothesized that SO(2) was responsible for the entry of B. bruxellensis into a viable but non-culturable (VBNC) state. The aim of this project was to investigate the effects of SO(2) on the remaining enzyme activities of B. bruxellensis populations according to their viability and cultivability, focusing on the hydroxycinnamate decarboxylase enzyme, the first enzyme needed, rather than the metabolites produced. Enzyme activity was determined both in cell-free extracts and resting cells after various SO(2) treatments in synthetic media. After slight sulfiting (around 50 mg/L total SO(2)), the yeasts had lost part of their enzyme activity but not their cultivability. At higher doses (at least 75 mg/L total SO(2)) the majority of yeasts had lost their cultivability but still retained part of their enzyme activity. These results suggested that non culturable cells retained some enzyme activity

Détection de bactéries lactiques produisant du 3-hydroxypropionaldéhyde (précurseur d'acroléine) à partir du glycérol par tests moléculaires

National audienc

Development of a molecular method for the typing of Brettanomyces bruxellensis (Dekkera bruxellensis) at the strain level

International audienceIn recent years, Brettanomyces/Dekkera bruxellensis has caused increasingly severe quality problems in the wine industry. A typing method at the strain level is needed for a better knowledge of the dispersion and the dynamics of these yeasts from grape to wine. Three molecular tools, namely random-amplified polymorphic DNA, PCR fingerprinting with microsatellite oligonucleotide primers and SAU-PCR, were explored for their relevance to typing strains of Brettanomyces bruxellensis. The results indicated that discrimination of each individual strain was not possible with a single PCR typing technique. We described a typing method for B. bruxellensis based on restriction enzyme analysis and pulse field gel electrophoresis (REA-PFGE). Results showed that electrophoretic profiles were reproducible and specific for each strain under study. Consequently, REA-PFGE should be considered for the discrimination of B. bruxellensis strains. This technique allowed a fine discrimination of B. bruxellensis, as strains were identified by a particular profile. This study constitutes a prerequisite for accurate and appropriate investigations on the diversity of strains throughout the winemaking and ageing process. Such studies will probably give clearer and more up-to-date information on the origin of the presence of Brettanomyces in wine after vinification when they are latent spoilage agents