Macrowine 2021
IVES 9 IVES Conference Series 9 Screening of soil yeasts with fermentative capacity from the antarctic continent for their application in the wine industry

Screening of soil yeasts with fermentative capacity from the antarctic continent for their application in the wine industry

Abstract

AIM: In the last years, many wineries are increasing experimentation to produce more distinguishable beverages. In this sense, the reduction of the fermentation temperature could be a useful tool because it preserves volatile compounds and prevents wines from browning, particularly in the case of white wines. However, low fermentation temperatures usually produce an early stop in the fermentation. Hence, the employment of new yeast strains able to operate at low temperatures could solve this problem, giving rise to different characteristics in wines. The Antarctic Continent is a crucial source for the isolation of new microorganisms and bioactive metabolites, given the competitive conditions of this environment with low temperatures, scarce carbon sources and high UV radiation. Considering this, the objective of this study was the isolation and characterization of fermentative yeast from the Antarctic Continent with potential for use in the wine industry.

METHODOLOGY: Six soil samples collected in Fildes Bay, west of King George Island and three soil samples from King George Island were processed for yeast isolation. Samples were suspended in sterile water and dilutions of each suspension were inoculated onto yeast medium (YM) agar plates with antibiotics, which were then incubated at 4, 10, and 18 °C until visible colony growth. Colonies with a non-filamentous appearance were selected, which were reseeded on YM agar without antibiotics. Alcohol tolerance was performed using concentrations of 3, 6, or 9% alcohol. Later on, sugar tolerance was analyzed using fructose and glucose in a 1:1 proportion; with 5, 10, 15, 20, or 25% of sugar in the medium. Those isolates with microscopic characteristics of interest were selected to determine fermentative activity in vitro using a simple colorimetric assay with phenol red, as a pH indicator. To differentiate the isolates, and discard replicates, a fingerprinting assay with arbitrary primers was performed. Identification of the isolates was carried out using PCR and ITS region primers with BLAST bioinformatics tools.

RESULTS: Nine soil samples collected from the Antarctica were processed for yeast isolation. We obtained 125 yeasts from the soil samples, with a growth temperature of 10ºC. Overall, 25 yeasts have fermentative activity and are able to tolerate a culture medium with at least 20% glucose and up to 6% of ethanol. The isolates were also characterized by optical microscopy and fingerprinting using PCR with arbitrary primers to discard identical strains and allowed us to discriminate 10 unique strains with fermentative capacity from the 25 isolates. To determine the identity of the isolated yeasts, the amplification and sequence of the 18S RNA was performed.

CONCLUSION:

The Antarctic continent has proven to be a source of fermentative yeasts with high potential for their use in the wine industry.

DOI:

Publication date: September 3, 2021

Issue: Macrowine 2021

Type: Article

Authors

Laura Navarro, Cristina Úbeda, Mariona Gil i Cortiella, Ana Gutierrez, Gino Corsini, Nancy Calisto

Biomedical Sciences Institute, Health Sciences Faculty, Autonomous University of Chile, Santiago, Chile., Nutrition and Food Sciences Department, Faculty of Pharmacy, University of Seville, Seville, Spain. Applied Chemical Sciences Institute, Autonomous University of Chile, Santiago, Chile. Biomedical Sciences Institute, Health Sciences Faculty, Autonomous University of Chile, Santiago, Chile. Biomedical Sciences Institute, Health Sciences Faculty, Autonomous University of Chile, Santiago, Chile. Chemical engineering department, Faculty of Engineering, Magallanes University, Punta Arenas, Chile. Biomedical Sciences Institute, Health Sciences Faculty, Autonomous University of Chile, Santiago, Chile.

Contact the author

Keywords

antarctic yeast, low temperature fermentation, yeast isolation, yeast characterization

Citation

Related articles…

austrianvineyards.com: online viewer of all designations of Austrian wine

To digitally record and present all the origins of Austrian wines in the same perfect and clear way was the motivation for the Austrian Wine Marketing Board (Austrian Wine) to start with the project in 2018. In June 2021 the results were presented to the public in an online viewer showing all the designations of Austrian wine, available at https://austrianvineyards.com in a largely barrier-free manner. The online viewer provides tailored individual maps fitted to the respective zoom level. The smallest unit of wine-origins in Austria is called Ried and is displayed in a plot-specific manner highlighting areas under vine. Information on the Ried include administrative district, winegrowing municipality, cadastral municipality, large collective vineyard site, specific winegrowing region, generic winegrowing region, winegrowing area and, in many cases, an illustrative picture. Complementary data on the size, elevation (minimum-maximum), orientation (in 8 sectors plus flat) and gradient (minimum, maximum, average) are based on the area under vine according to the EU’s Integrated Administration and Control System. Additional information covers climate data. The diagrams are taken from the monthly breakdown of data in the annals of the Central Institute for Meteorology and Geodynamics, Austria provide a display of values for air temperature, precipitation, and sunshine hours for the reference year and the long-term average. Seasonal aggregated data on temperature, precipitation, and sunshine hours complete the display. Short descriptions with emphasis on geology and soil, field name in historical maps, etymology of the denomination, and main planted variety complements the available information for the main designations in the online viewer. These descriptions are compiled by winegrowers, geologists, historians, and journalists. All the information and data can be extracted to a pdf-file. Printed vineyard maps are also available. Missing content regarding wine origins in Styria will be completed in winter 2021/22.

Extreme canopy management for vineyard adaptation to climate change: is it a good idea?

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.

Revealing the Barossa zone sub-divisions through sensory and chemical analysis of Shiraz wine

The Barossa zone is arguably one of the most well-recognised wine producing regions in Australia and internationally; known mainly for the production of its distinct Shiraz wines. However, within the broad Barossa geographical delimitation, a variation in terroir can be perceived and is expressed as sensorial and chemical profile differences between wines. This study aimed to explore the sub-division classification across the Barossa region using chemical and sensory measurements. Shiraz grapes from 4 different vintages and different vineyards across the Barossa (2018, n = 69; 2019, n = 72; 2020, n = 79; 2021, n = 64) were harvested and made using a standardised small lot winemaking procedure. The analysis involved a sensory descriptive analysis with a highly trained panel and chemical measurement including basic chemistry (e.g. pH, TA, alcohol content, total SO2), phenolic composition, volatile compounds, metals, proline, and polysaccharides. The datasets were combined and analysed through an unsupervised, clustering analysis. Firstly, each vintage was considered separately to investigate any vintage to vintage variation. The datasets were then combined and analysed as a whole. The number of sub-divisions based on the measurements were identified and characterised with their sensory and chemical profile and some consistencies were seen between the vintages. Preliminary analysis of the sensory results showed that in most vintages, two major groups could be identified characterised with one group showing a fruit-forward profile and another displaying savoury and cooked vegetables characters. The exploration of distinct profiles arising from the Barossa wine producing region will provide producers with valuable information about the regional potential of their wine assisting with tools to increase their target market and reputation. This study will also provide a robust and comprehensive basis to determine the distinctive terroir characteristics which exist within the Barossa wine producing region.

Combining effect of leaf removal and natural shading on grape ripening under two irrigation strategies in Manto negro (Vitis vinifera L.)

The increasingly frequent heat waves during grape ripening pose challenges for high quality wine grape production. Defoliation is a common practice that can improve the control of diseases in bunches, but also it increases the exposure to sunlight. Grapes exposed to solar radiation reach temperatures over the optimum for berry development and maturation. This makes the development of irrigation and canopy management techniques of great importance to maximize yield and grape quality. A field experiment was carried out during 2021 using Manto negro wine grapes to study the effect of applied irrigation and different light exposure levels on grape quality. Two irrigation treatments were imposed based on the frequency and amount of water doses in a four-block experimental vineyard at Bodega Ribas (Mallorca). Three light exposure treatments were randomly applied in each irrigation plot. The light treatments included exposed clusters from pea size, non-exposed clusters, and shaded clusters after softening. Leaf area index and canopy porosity was estimated every 2 weeks. Midday leaf water potential was measured weekly. Additionally, apparent electrical conductivity was measured between rows to estimate the soil water content variability. Light and temperature sensors were installed at the bunch level to quantify the differences in bunch temperature and light intensity among treatments. The effect of irrigation and cluster light exposure on berry weight, TSS, TA, malic acid, tartaric acid, K+, and pH were analysed at 5 moments along grape ripening. During different heat waves, the natural shading technique decreased the maximum bunch temperature around 10 °C respect to the exposed bunches in both irrigation strategies. The combination of defoliation and shading techniques after softening decreased TSS at harvest and affected most of the quality parameters during the last stages of ripening, showing an interesting technique to delay ripening in warm viticulture areas.

The plantation frame as a measure of adaptation to climate change

The mechanization of vineyard work originally led to a reduction in planting densities due to the lack of machinery adapted to the vineyard. The current availability of specific machinery makes it possible to establish higher planting densities. In this work, three planting densities (1.40×0.80 m, 1.80×1 m and 2.20×1.20 m, corresponding to 8928, 5555 and 3787 plants/ha respectively) were studied with four varieties autochthonous of Galicia (northwestern Spain): Albariño and Treixadura (white), Sousón and Mencía (red). The vines were trained in a vertical shoot positioning system using a single Royat cordon, and pruned to spurs with two buds each. Agronomic data (yield, pruning wood weight, Ravaz index) and oenological data in must were collected. The higher planting density (1.40×0.80 m) had no significant effect on grape yield per vine in white varieties, although production per hectare was much higher due to the greater number of plants. In red varieties, this planting density resulted in a significantly lower production per vine, compensated by the greater number of plants. In addition, it significantly reduced the Brix degree in the must of the Albariño, Treixadura and Sousón varieties, and increased the total acidity in the latter two and Mencía. It also caused an increase in extractable and total anthocyanins and IPT in red grapes. The effects of high planting density on grapes are of great interest for the adaptation of varieties in the context of climate change. In the future, it could be advisable to modify the limits imposed by the appellations of origin on the planting density of these varieties in order to obtain more balanced wines.