 IVES 9 IVES Conference Series 9 Expanding the biotechnological potential of M. pulcherrima/fructicola clade for wine-related applications

Expanding the biotechnological potential of M. pulcherrima/fructicola clade for wine-related applications

Abstract

AIM: Strains belonging to M. pulcherrima/fructicola clade are frequently isolated from flowers, fruits and grape musts, and exhibit a broad spectrum of enzymatic activities and antimicrobial potential (Morata et al., 2019; Sipiczki, 2020; Vicente et al. 2020). By reason of these features, selected strains of this clade have been proposed as non-Saccharomyces starter cultures for winemaking. In this study, with a view to valorise the biotechnological potential of these strains, a new Metschnikowia sp. strain, DBT012, was selected for application in vinification trials of Valpolicella’s fresh and withered typical grapes for reduction of SO₂addition and increase of aromatic complexity. Further, in the framework of the investigation on the biodiversity of a collection of strains, distinct pulcherrimin-producing isolates from spontaneous fermentation and grapes were putatively recognized as Metschnikowia spp. and selected for genotypic and phenotypic characterisation.

METHODS: Lyophilised cultures of the reference strain DBT012 were tested in pilot-scale vinifications (mixed-cultures with S. cerevisiae). The isolates were characterised based on enzymatic activities (e.g., sulphite-reductase and beta-glucosidase activities) and growth under different wine-related stress conditions (e.g., ethanol, high sugar content). Genetic fingerprinting techniques (e.g., (GTG)5 and microsatellite) were performed for de-replication of isolates and strain typing. Whole-genome sequencing of the reference strain was carried out to analyse the correlation between genotype and phenotype, and comparative analyses with available type strains were performed to deepen the taxonomic aspects and molecularly identify this strain.

RESULTS: Use of Metschnikowia sp. DBT012 reduced the acetaldehyde content in wines, and positively influenced the wine aroma. About 50 Metschnikowia strains were characterised, which displayed a significant phenotypic diversity in terms of β-glucosidase and esterase activities, H2S production and growth at high sugar concentrations. The relationship of those features with genotypic and genomic distinctiveness of the reference strain was highlighted.

CONCLUSIONS:

The well-characterised thematic collection of strains belonging to M. pulcherrima/fructicola clade presented here constitutes an important reservoir of biodiversity for applications in different wine-related scenarios.

DOI:

Publication date: September 3, 2021

Issue: Macrowine 2021

Type: Article

Authors

Eleonora Troiano,Renato, LEAL BINATI, Ilaria, CHECCHIA, Ilaria, LARINI, Veronica, GATTO, Gianluca, VENERI, Giacomo, ZAPPAROLI, Vittorio, CAPOZZI, Elisa, SALVETTI, Sandra, TORRIANI, Giovanna, E., FELIS

Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy , Department of Biotechnology, University of Verona, Italy, Institute of Sciences of Food Production, National Research Council (CNR), Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy

Contact the author

;

Keywords

metschnikowia, wine microbiology, biodiversity, biotechnological potential

Citation

Mobile device to induce heat-stress on grapevine berries

Studying heat stress response of grapevine berries in the field often relies on weather conditions during the growing season. We constructed a mobile heating device, able to induce controlled heat stress on grapes in vineyards. The heater consisted of six 150 W infrared lamps mounted in a profile frame. Heating power of the lamps could be controlled individually by a control unit consisting of a single board computer and six temperature sensors to reach a pre-set temperature. The heat energy applied to individual berries within a cluster decreases by the squared distance to the heat source, enabling the establishment of temperature profiles within individual clusters. These profiles can be measured by infrared thermography once a steady state has been reached. Radiant flux density received by a berry depending on the distance was calculated based on a view factor and measured lamp surface temperature and resulted to 665 Wm-2 at 7cm. Infrared thermography of the fruit surface was in good agreement with measurements conducted with a thermocouple inserted at epidermis level. In combination with infrared thermography, the presented device offers possibilities for a wide range of applications like phenotyping for heat tolerance in the field to proceed in the understanding of the complex response of plants to heat stress. Sunburn necrosis symptoms were artificially induced with the aid of the device for cv. Bacchus and cv. Sylvaner in the 2020 and 2021 growing season. Threshold temperatures for sunburn induction (LT5030min) were derived from temperature data of single berries and visual sunburn assessment, applying logistic regression. A comparison of threshold temperatures for the occurrence of sunburn necrosis confirmed the higher susceptibility of cv. Bacchus. The lower susceptibility of cv. Sylvaner did not seem to be related to its phenolic composition, rendering a thermoprotective role of berry phenolic compounds unlikely.

Volatile organic compounds investigation in Müller Thurgau wines obtained from vineyard treated with biochar

Volatile Organic Compounds (VOCs) are responsible for the flavor and aroma of a wine. The sensory qualities of the wines depend not only on grape intrinsic characteristics, but also on extrinsic factors including the soil composition. Previous studies have shown that the application of pyrogenic carbon (biochar) can lead to a change in soil parameters. For that reason, one of the goals of the ERDF funded project «WoodUp» is the characterization and reutilization of the locally produced biochar for agricultural purposes.

Development of a standardized method for metabolite analysis by NMR to assess wine authenticity

The wine sector generates a considerable amount of wealth but is facing a growing problem of fraud. Wine counterfeiting is one of the oldest and most common cases of food fraud worldwide. Therefore, the authenticity and traceability of wine are major concerns for both the industry and consumers. To address these issues, robust and reliable analysis and control methods are necessary. Several methods have been developed, ranging from simple organoleptic tests to more advanced methodologies such as isotopic techniques or residual radioactivity measurements.

FLOW CYTOMETRY, A POWERFUL AND SUSTAINABLE METHOD WITH MULTIPLE APPLICATIONS IN ENOLOGY

Flow cytometry (FCM) is a powerful technique allowing the detection, characterization and quantification of microbial populations in different fields of application (medical environment, food industry, enology, etc.). Depending on the fluorescent markers and specific probes used, FCM provides information on the physiological state of the cell and allows the quantification of a microorganism of interest within a mixed population. For 15 years, the enological sector has shown growing interest in this technique, which is now used to determine the populations present (of interest or spoilage) and the physiological state of microorganisms at the different stages of winemaking.

Soil mineral nitrogen dynamics in cover-cropped irrigated vineyards with contrasting soil textures

Context and purpose of the study. Cover cropping in vineyards supports grape yield, quality, and soil health.