Research programmes in grapevine and wine biotechnology

Introduction

The IWBT is the only research institute in the country that is focused primarily on grapevine and wine biotechnology and it cooperates very closely with the wine and table grape industries of South Africa.

New trends in the beverage markets continue to call for a diversity of innovations: new grape cultivars, the modification of traditional wine yeast strains and the development of grape growing and winemaking practices that will be more cost-effective and environmentally friendly. A major source of variation is the genetic make-up of the grape variety and of the wine yeast strain used. In recent years the analysis and genetic improvement of wine yeasts and grapes has steadily become more effective and precise due to advances in molecular genetics and recombinant DNA technology. Genetically engineered organisms give rise to problems of statutory approval and negative public perceptions. These difficulties are giving way though, to a widening acknowledgement that risk arises primarily from the product's characteristics and not from the use of genetic modification. This means that gene cloning and gene transformations are likely to predominate in the future development of wine yeasts and grape cultivars. 

Approach to research

The research philosophy of the IWBT is the result of strategic decisions on how best to respond to five challenges:

• Balancing academic and industrial needs.
• Establishing know-how, knowledge and key support technologies.
• Identifying the most relevant industrial problems and how to translate them into relevant scientific questions.
• Optimising projects and train postgraduate students.
• Generating intellectual property and products.

Research portfolio

The IWBT's research theme is the improvement of grapevine cultivars, wine yeast and wine bacteria to promote sustainable, environmentally friendly and cost-effective production of quality grapes and wine. The research portfolio consists of three programmes (see Fig. 1). The first focuses on the molecular characterisation of metabolic and signalling pathways in yeasts and the genetic improvement of wine yeast strains. A second programme is concerned with lactic acid and other bacteria, including their impact on wine, metabolic characterisation and improvement of malolactic fermentation. The third programme focuses on the molecular biology and genetic improvement of grape cultivars. A below. In addition to these programmes, there is the newly established Wine Science RNA (Fig. B) which combines research groups from the Department of Chemistry and Polymer Science, the Department of Food Science, the Department of Viticulture and Oenology and the Institute for Wine Biotechnology, and in a scientific theme of Metabolomics and Metrics of vine, wine and wine organisms. The focus of the research will be to provide a fully integrated and controlled research chain starting with characterised model vineyards and ending with a comprehensive chemical, sensory and quality assessment of the final product. Each of these partners offers specific postgraduate opportunities within their degree structures.

Focus areas of research team

Grapevine molecular biology and biotechnology

Dr John Moore
Specialisation: Grapevine molecular biology and biotechnology
Focus area: Grapevine biochemistry and metabolism

His research area forms part of the Grapevine Biotechnology Programme (within the framework of the NRF supported Wine Science Research Niche Area (RNA)) of the IWBT in collaboration with Professor Melané Vivier. The goals of the programme are to improve the disease resistance, fruit quality and abiotic stress (i.e. drought) tolerance of Vitis vinifera (grapevine) cultivars utilising transgenic technology. His specific research aims are to understand the biochemical and metabolic aspects of berry development, plant pathology and abiotic stress tolerance in grapevine with a focus on the role of the cell wall. He also maintains an interest in the chemistry and biology of plant polyphenols with particular reference to their functional significance in planta as well as being key constituents of grapes and wine.

Prof Melané Vivier
Specialisation: Grapevine molecular and cellular biology
Focus area: Biotechnology product development and molecular biology of grapevine stress

Her research programme is focused on the biology of grapevine (Vitis vinifera). The genetic potential and molecular mechanisms underlying V. vinifera's reaction towards some of the biotic and abiotic stresses typically appearing in vineyards are studied. Two main themes form part of the programme: (i) Understanding and manipulating disease resistance and (ii) Metabolic engineering of grapevine towards enhanced abiotic stress resistance and improved quality parameters. The programme is supported by grapevine transformation and regeneration technologies, basic molecular biology and some systems biology technologies and an increasing list of analytical methods to evaluate grapevine and model plant tissues.

Dr Philip Young
Specialisation: Grapevine molecular biology and biotechnology
Focus area: Molecular biology of grapevine with the focus on carotenoid biosynthesis

The main focus of the grapevine biotechnology research programme is on the development of genetically improved grape cultivars with outstanding fruit quality, reduced susceptibility to diseases, pests and other stress conditions and an increased nutritive value (in the case of table grapes). The specific focus of this research is the contribution of the carotenoid biosynthetic pathway to these grape quality aspects, especially with reference to their role in flavour and aroma development and abiotic stress tolerance.

Wine biotechnology

Prof Florian Bauer
Specialisation: Wine biotechnology
Focus area: Yeast molecular and cellular biology

His research portfolio is focused on the yeast Saccharomyces cerevisiae and investigates the molecular processes that regulate gene expression, carbon flux (ethanol yield and transfer of activated acyl-residues), aroma compound production and cellular adhesion properties. The research projects make use of all standard microbiological and molecular biology techniques, as well as genomics-, transcriptomics- and metabolomics-based approaches. Insights gained from these projects are applied to improve wine yeast strains through the use of traditional breeding, mutagenesis, directed evolution and genetic engineering.

Dr Benoit Divol
Specialisation: Wine microbiology and biotechnology
Focus area: Enzymes production by wine yeasts and bacteria; microorganisms interactions with each other and with the environment

Microbial populations play an essential role in winemaking. Apart from the species responsible for completing fermentations (i.e. mainly Saccharomyces cerevisiae and Oenococcus oeni), several others occur throughout the vinification process and somehow influence the final chemical composition of the wines to various extents. Dr Divol’s research focuses on survival strategies and stress response (in particular those of spoilage microorganisms), wine ecology, population dynamics and impact of these microorganisms on the organoleptic quality of wines. Specific attention is given to key enzymes of non-Saccharomyces yeasts as well as those of lactic acid bacteria involved in various intracellular metabolisms or secreted into the wine. Antimicrobial peptides and proteins secreted by these microorganisms are also studied in order to evaluate their impact on spoilage microbes.

 

Prof Maret du Toit
Specialisation: (i) Wine microbiology (oenology) and (ii) wine biotechnology
Focus area: (i) lactic acid bacteria, microbial spoilage, MLF and (ii) Lactic acid bacterial molecular biology

Microorganisms form an integral part of the winemaking process and can have a positive or negative influence on wine quality. Lactic acid bacteria (LAB) is responsible for malolactic fermentation in wine, especially O. oeni . Apart of performing this fermentation they can also contribute to wine aroma compounds that will improve wine quality. The focus is on the following enzymes ß-glucosidases, esterases, glucunases, proteases and phenolic acid decarboxylases. LAB is also regarded as a spoilage microorganism and the focus is on bitterness, biogenic amines and volatile sulphur compounds. LAB also produce bacteriocins that can be used as alternative to chemical preservatives, which is investigated, and we also focus on lysozyme that is allowed to be used in winemaking. Research is currently being conducted on the omics of wine LAB, especially the metabolome produced by commercial MLF starter cultures. Furthermore infrared spectroscopy is evaluated as rapid tool to identify wine microbes with.

Prof Pierre van Rensburg
Specialisation: Wine biotechnology
Focus area: Yeast molecular biology and enzymes

Wine yeasts ( Saccharomyces cerevisiae ) cannot degrade/utilise polysaccharides and certain grape must proteins and is also not able to destroy contaminating spoilage organisms. For these reasons, most wine makers add enzyme preparations (pectinases, glucanases, hemicellulases, proteases) and bentonite to remove filter-blocking, polysaccharide-rich particles and haze-forming proteins from the must, as well as chemical preservatives to prevent wine spoilage. However, these practices are cost-ineffective, time-consuming and contrary to the principle of environmental friendliness. Therefore, attempts are made in this laboratory to isolate new yeasts, prepare mutants and generate hybrids that will secrete these polysaccharide-degrading enzymes during fermentation. In addition, heterologous pectinase, cellulase, xylanase, protease and chitinase genes are cloned from other microorganisms, manipulated and then expressed in wine yeasts. In all of these projects, sophisticated recombinant DNA techniques are finely interwoven with the strong genetic system of S. cerevisiae in the search for answers to questions in basic biology, but also with the aim of establishing industrially applicable and improved processes.

Analytical chemistry

Dr Helénè Nieuwoudt
Specialisation: Analytical chemistry
Focus area: Advanced chemical-analytical techniques in viticulture, oenology and biotechnology with the focus on rapid analytical techniques and data processing

Her research focuses on both the quantitative and qualitative profiling of grape- and wine composition. The development and optimisation of rapid analytical techniques, particularly Fourier transform mid- infrared and near-infrared spectroscopy, form the cornerstone of the work. Multivariate data analysis, also referred to as "chemometrics", is applied to spectroscopic, chemical analytical and sensory data in order to establish profiles of South African grape cultivars and wine styles.

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Research collaboration

The IWBT's research is conducted in collaboration with local research institutions, as well as several international laboratories.

National

• Departments of Chemistry, Food Science, Genetics, Microbiology and Viticulture and Oenology, Stellenbosch University
• Department of Biochemistry and Microbiology, Rhodes University
• Department of Cellular and Molecular Biology, University of Cape Town
• Agricultural Research Council - Infruitec/Nietvoorbij, Stellenbosch
• South African Sugar Research Institute; Distell and Elsenburg Agricultural College

International

• The Australian Wine Research Institute, Adelaide, Australia
• CSIRO Plant Industry, Australia
• Forschungsanstalt Geisenheim, Germany
• nstitut für Hygiene und Toxikologie, Germany
• Centrum Gruene Gentechnik, Germany
• Universidad de Castilla La Mancha, Ciudad Real, Spain
• Catholic University of Louvain, Belgium
• University of Bordeaux, Bordeaux, France
• Instituto Agrario San Michele all'Adige, Italy
• Universität Roviri i Virgili, Tarragona, Spain
• Instituto de fermentaciones Industriales (CSIC), Madrid, Spain
• University of Lund, Sweden
• Matforsk, Centre for Biospectroscopy and Data Modeling, Norway
• Swiss Wine Research Institute, Wädenswil, Switzerland
• Department of Viticulture and Oenology, University of California, Davis, USA
• Complex Carbohydrate Research Center, Athens, USA
• Ryerson University, Toronto, Canada, University of Cuyo, Mendoza, Argentina

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Publications

Publications from 1995 - 2008 : See complete list here

1. Bauer, F.F, P. Govender & M.C. Bester. 2010. Yeast flocculation and its biotechnological relevance. Applied Microbiology and Biotechnology. 88: 31-39.
2. Bauer, R., M. du Toit & J. Kossmann. 2010. Influence of environmental parameters on production of the acrolein precursor 3-hydroxypropionaldehyde by Lactobacillus reuteri DSMZ 20016 and its accumulation by wine lactobacilli. International Journal of Food Microbiology 137: 28-31.
3. Bester, L., M. Cameron, M. du Toit & R.C. Witthuhn. 2010. PCR and DGGE detection limits for wine spoilage microbes. South African Journal of Enology and Viticulture 31(1): 26-33.
4. Du Toit, M. 2010. Malolactic fermentation in wine. Encyclopedia of Biotechnology in Agriculture and Food 1 (1): 387-389.
5. Franken, J. & F.F. Bauer. 2010. Carnitine supplementation has protective and detrimental effects in Saccharomyces cerevisiae that are genetically mediated. FEMS Yeast Research 10: 270-281.
6. Govender, P., M.C. Bester & F.F. Bauer. 2010. FLO gene dependent phenotypes in industrial wine yeast strains. Applied Microbiology and Biotechnology 86: 931-945.
7. Lashbrooke, J.G., P.R. Young, A.E. Strever, C. Stander & M.A. Vivier. 2010. The development of a method for the extraction of carotenoids and chlorophylls from grapevine leaves and berries for HPLC profiling. Australian Journal of Grape and Wine Research 16: 349-360.
8. Louw, C.T., P.R. Young, P. van Rensburg & B.T. Divol. 2010. Epigenetic regulation of PGU1 transcription in Saccharomyces cerevisiae. FEMS Yeast Research 10: 158-167.
9. Louw, C.T., P.R. Young, P. van Rensburg & B.T. Divol. 2010. Regulation of endo-polygalacturonase activity in Saccharomyces cerevisiae. FEMS Yeast Research 10: 44-57.
10. Mtshali, P.S., B.T. Divol, P. van Rensburg & M. du Toit. 2010. Genetic screening of wine-related enzymes in Lactobacillus species isolated from South African wines. Journal of Applied Microbiology 108: 1389-1397.
11. Oelofse, A., S. Malherbe, I.S. Pretorius & M. du Toit. 2010. Preliminary evaluation of infrared spectroscopy for the differentiation of Brettanomyces bruxellensis strains isolated from red wines.International Journal of Food Microbiology.DOI: 10.1016/j.ijfoodmicro.2010.08.004
12. Rossouw, D., A.H. van den Dool, D. Jacobson & F.F. Bauer. 2010. Comparative transcriptomic and proteomic profiling of industrial wine yeast strains. Applied and Environmental Microbiology 76(12): 3911-3923.
13. Rudnitskaya, A., H.H. Nieuwoudt, N. Muller, A. Legin, M. du Toit & F.F. Bauer. 2010. Instrumental measurement of bitter taste in red wine using an electronic tongue. Analytical and Bioanalytical Chemistry. 397: 3051–3060
14. Van Wyk, H. & B.T. Divol. 2010. Recovery of endo-polygalacturonase activity in wine yeast and its effect on wine aroma. FEMS Yeast Research, 10: 58-71.

1. Malherbe, S., V.A. Watts, H.H. Nieuwoudt, F.F. Bauer & M. du Toit. 2009. Analysis of volatile profiles of fermenting must by Headspace Solid-phase Dynamic Extraction coupled to Gas Chromatography-Mass Spectrometry (HS-SPDE GC-MS): Novel application to investigate problem fermentations. Journal of Agricultural and Food Chemistry 57: 5161-5166.
2. Moore, J.P., N.T. Le, W.F. Brandt, A. Driouich & J.M. Farrant. 2009. Towards a systems-based understanding of plant desiccation tolerance. Trends in Plant Science 14(2): 110-117.
3. Niu, D., Z. Zuo, G. Shi & Z. Wang. 2009. High yield recombinant thermostable α-amylase production using an improved Bacillus licheniformis system. Microbial Cell Factories 8: 58 DOI: 10.1186/1475-2859-8-58.
4. Oelofse, A., M. du Toit & A. Lonvaud-Funel. 2009. Molecular identification of Brettanomyces bruxellensis strains isolated from red wines and volatile phenol production. Food Microbiology 26: 377-385.
5. Rossouw, D. & F.F. Bauer. 2009. Comparing the transcriptomes of wine yeast strains: toward understanding the interaction between environment and transcriptome during fermentation. Applied Microbiology and Biotechnology 84:937-954.
6. Rossouw, D. & F.F. Bauer. 2009. Wine science in the omics era: The impact of systems biology on the future of wine research. South African Journal of Enology and Viticulture 30(2): 101-109.
7. Rossouw, D., R. Olivares-Hernández, J. Nielsen & F.F. Bauer. 2009. Comparative transcriptomic approach to investigate differences in wine yeast physiology and metabolism during fermentation. Applied and Environmental Microbiology75(20): 6600-6612.
8. Schoeman, H., G.M. Wolfaardt, A. Botha, P. van Rensburg & I.S. Pretorius. 2009. Establishing a risk-assessment process for release of genetically modified wine yeast into the environment. Canadian Journal of Microbiology 55(8): 990-1002.

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Patents

Enquiries: E-mail:

901996 Amylolytic Yeast Strains
907246 Biological Control Agent
907246 Wine Yeast Strains*
901903 Biological Control Agent
925949 Pectolytic Yeast Strains
93/4435 Amylolytic Cassette
96/3971 Malolactic Yeast
2005/8194 Resveratrol
2007/04132 Carnitine-synthesising

*The University of Stellenbosch has licensed Anchor Yeast to manufacture and market the VIN13 wine yeast and has received royalties on the 80 tons that have been sold over the last eleven years.