Vladimir Jiranek

Professor Vladimir Jiranek


School of Agriculture, Food and Wine

Faculty of Sciences, Engineering and Technology

Eligible to supervise Masters and PhD - email supervisor to discuss availability.

My work is largely linked to three questions:

  • How do yeast and bacteria interact with their environment and each other in high stress environments such as seen in winemaking?
  • How can this knowledge be exploited to produce superior strains and wine process outcomes?
  • What does this knowledge tells us about the evolution and ecology of these microbes in their ‘natural’ environment.

Our projects broadly fall under these headings:

Yeast Functional Genomics

Objectives: This project seeks to identify the genes that are responsible for the unique properties of individual wine yeast strains and to determine how these confer their effects. Background: It is widely recognised that strains of yeast can differ distinctly in terms of fermentation properties (e.g. speed, completeness, temperature optimum, etc) and production or modification of metabolites of sensory significance. In many cases the genetic basis for such differences is yet to be determined. Research approach: Using high-throughput screens of yeast mutant libraries, as well as comparative genome analysis, we are identifying genetic differences between strains that relate to specific phenotypes. Further, we seek to understand the adaptive mechanisms by which yeast are able to survive in grape must and successfully complete alcoholic fermentation. This information is being used to guide further strain development and build models of how yeasts function under extreme conditions. Benefit: The understanding behind the diversity exhibited by wine yeast will be exploited in future yeast optimisation. Such information also improves our understanding of the fundamentally important mechanisms by which a yeast copes with the ever-changing environments in which it finds itself.

Directed Evolution of Yeast & Lactic Acid Bacteria

Objectives: Generation of superior yeast and lactic acid bacteria by the non-recombinant approach of directed evolution. For yeast, the aim is to create more robust strains for fermentation in high sugar and low nutrient juice. For lactic acid bacteria, the aim is to create strains better adapted to the highly inhibitory conditions of grape juice and wine. Background & Research Approach: This research encompasses a broad range of microorganisms involved in the winemaking process. Our approach is to apply directed evolution (extended incubation under selective conditions) to the following organisms to improve their performance. Saccharomyces cerevisiae: Even though pure cultures of this robust yeast are frequently inoculated by winemakers, a significant percentage of fermentations are slow or prematurely arrest (‘stuck’), in part due to challenging grape must composition. Climate warming is producing shorter, drier vintages that can intensify these challenges by generating juices deficient in nutrients, high in sugar and yielding high alcohol wines. Directed evolution is being applied, targeting a number of oenological stressors including acidity, high sugar and ethanol content, in order to generate more robust strains. Additionally, other novel traits such as the metabolism of malic acid are being investigated. Non-Saccharomyces yeast: When used as a single culture inoculum, such strains often fail to complete alcoholic fermentation largely due to their sensitivity to ethanol and their ability to compete with S. cerevisiae. Directed evolution is being used to generate more robust non-Saccharomyces strains so as to allow these yeasts to persist longer in fermentation and make a more significant contribution to the chemical and sensory profile of the wine. Lactic acid bacteria: Lactic acid bacteria (LAB) have fastidious growth requirements and can be sensitive to the harsh conditions of winemaking (low pH, low temperature, high ethanol content and the presence of SO2). As a result they can be slow both to become established and to complete malolactic fermentation, thereby greatly extending the duration of the winemaking process. This project uses directed evolution to produce more efficient and reliable strains of LAB with higher tolerance to wine conditions. Benefit: Superior yeast and LAB generated using the non-recombinant method of directed evolution, will offer the industry greater reliability and predictability of alcoholic and malolactic fermentation. Reductions in processing times will enhance winemaking efficiency, winery throughput and reduce the risk of spoilage associate with unfinished wines being held in an unstabilised form for longer.

Characterisation of Fermentation Practices of Australian Aboriginal People

Objectives: To document and characterise fermentations of plant derived food and beverages of Aboriginal people as practiced historically or at present. Background & Research Approach: It is not widely recognised that Aboriginal people and Torres Strait Islanders practiced fermentations that resulted in alcoholic beverages, albeit likely of low alcohol strength. In fact fermented drinks were made from several plant materials and extracts including tree saps and roots, banksia flowers or roasted, ground nuts of the spiral pandanus. Other naturally sugar-rich materials may also have been used. A comprehensive survey of the knowledge of such processes, let alone a study of ongoing practices has not be conducted. This project seeks to capture details about the scope of fermentations conducted by Aboriginal people from across Australia. Of primary interest is the identification of such fermentation practices, the typical raw materials and their processing, the chemical composition of the pre-fermentation substrate, the mode of inoculation, the yeast and bacterial species responsible for the fermentation, and an analysis of the finished products in terms of their chemistry and sensory properties. Information about the cultural significance of production and consumption would also be of interest. 

Yeast Cell-Cell Communication

Objectives: This project aims to explore the cell-cell signalling known and/or suspected to occur between microbes involved in the wine fermentation, so as to understand the impact on population and fermentation dynamics and metabolite formation. Background: A yeast cell’s life is a dramatic sequence of feast and famine. Competition for nutrients can result in many cellular responses. The fate of an individual cell is not only determined by it’s own cellular machinery, but also by others in its vicinity. But how are these activities coordinated? Cell-cell communication via chemical signals is critical in this process and can result in altered growth and morphology and changes to core metabolic systems such as fermentation. A handful of signalling molecules are known, but are there others? Furthermore, do they affect fermentation dynamics or even quality of fermented products, like wine? Certainly one known signalling molecule, phenylethanol, contributes positive rose-like aromas to fermented beverages. Research Approach: We have been investigating the influence of known signalling molecules on wine yeast cell growth, morphology and fermentation. Novel fermentation-specific cell-cell signalling molecules are also being identified and their impacts on yeast rigorously examined. We are defining the functional relevance of these molecules to industrial fermentation. This approach will be aided with the use of yeast mutant libraries. Where appropriate, a fermentation-specific cell-cell signalling model will be generated to provide a holistic view of the impact on wine. Benefit: Application of the knowledge gained has the potential to improve industrial fermentation through new monitoring and management systems. Importantly, the findings will have relevance for how this organism interacts with its neighbours in a natural context.

Dissecting the Complexity and Contribution of Uninoculated Fermentation

Objectives: The elucidation of the numbers of species present in uninoculated wine fermentations at specific time points, their relative proportions during fermentation and the impact on final wine aroma and flavour. Background: Excellent winemaking outcomes and commercial success can occur for wines produced via uninoculated (indigenous) fermentations. During these, the often complex microbial populations of the grapes and winery conduct the fermentation. Much research has shown that different or more complex aroma profiles can result, but a number of key questions remain. Particularly, how and why do these populations vary from variety-to-variety and year-to-year? How are these populations interacting with each other and with the yeast or bacteria that are subsequently inoculated by the winemaker? Research approach: Analysis of uninoculated fermentations conducted at a commercial wineries has helped define the nature, diversity and dynamics of yeast and lactic acid bacterial populations. Sampling has occurred over several years across a number of grape varieties. Isolates are being identified via morphology and genotyping and their impact defined through chemical and sensory analysis. Benefit: The findings will help wineries define the extent to which the microflora and its contribution to wine composition represent a component of the unique terroir of the resulting wines. Recommendations will also be developed to help favour particular organisms over others. Ideally isolates of novel yeasts or bacteria will be identified for commercialisation by our partner yeast manufacturers.

Fermentation Technology - 'T-Bot'

Objectives: Develop a high-throughput fermentation phenotyping system i.e. a robotic platform enabling automated sampling of large numbers of laboratory scale fermentations.Background: Our research requires the screening of large numbers of yeast and lactic acid bacteria strains, to analyse their fermentation performance and associated properties (e.g. metabolite production). This is particularly the case when working with yeast deletion libraries (see project ‘Yeast Functional Genomics’) or when screening individual isolates from directed evolution studies (see project ‘Directed Evolution of Yeast & Lactic Acid Bacteria’). This usually involves replicated flask fermentations (~100 mL per flask) for each strain, which are manually sampled multiple times per day, for several days to several weeks. To minimise labour and maximise research efficiency, a robotic platform capable of maintaining 96, 100 mL fermentations, was developed including the ability to automatically sample on demand. Research approach: The T-Bot has been built around a Tecan Freedom EVO200 liquid handling machine. The EVO’s work deck has been fitted with jacketed carriers, holding 96 fermentation flasks fitted with a custom-designed air-lock to allow sampling at user-defined intervals. Automated systems for in-line monitoring of key metabolites (eg. sugar and alcohol) are being developed. Benefit: The T-Bot is delivering a robust, reliable and reproducible screening capacity that greatly accelerates the throughput of our strain evaluation work. 

Contributions to the following Degree Programs and Courses

Bachelor of Viticulture and Oenology

  • Microbiology for Viticulture and Oenology II (Level 2)
  • Fermentation Technology (Level 3)
  • Advances in Wine Science (Level 4)

Bachelor of Science (Biotechnology)

  • Biotechnology Practice III (Level 3)
  • Current Higher Degree by Research Supervision (University of Adelaide)

    Date Role Research Topic Program Degree Type Student Load Student Name
    2023 Principal Supervisor Novel microbes from Australian plants: Characterisation and industrial potential Doctor of Philosophy Doctorate Full Time Miss Tea Knezevic
    2022 Principal Supervisor Selection of lactic acid bacteria for efficient malolactic fermentation in the presence of sulfur dioxide Doctor of Philosophy Doctorate Full Time Ms Yingxin Liu
    2021 Principal Supervisor Exploring the diversity of bacteriophage in wine production Doctor of Philosophy Doctorate Full Time Miss Zhecun Xu
    2020 Co-Supervisor Defining and Exploiting the Indigenous Microflora of Grapes Doctor of Philosophy Doctorate Full Time Miss Natalia Soledad Caliani
    2020 Principal Supervisor The influence of sulfur compounds on yeast, bacteria and mixed cultures of these in oenology Doctor of Philosophy Doctorate Full Time Emily Hocking
    2019 Principal Supervisor Bioprospecting for Lactic Acid Bacteria in Novel Australian Niches Doctor of Philosophy Doctorate Full Time Mr Scott Allen Oliphant
    2018 Principal Supervisor Mutual Evolutionary Advantage of Traits in Yeast and their Insect Vector, Drosophila Melanogaster Doctor of Philosophy Doctorate Part Time Mrs Shailja Mishra
  • Past Higher Degree by Research Supervision (University of Adelaide)

    Date Role Research Topic Program Degree Type Student Load Student Name
    2019 - 2022 Principal Supervisor Isolation and Characterisation of Yeasts with Biotechnological Properties Doctor of Philosophy Doctorate Full Time Miss Mandy Man-Hsi Lin
    2016 - 2021 Principal Supervisor Yeast Strain Construction Using CRISPR/Cas9: A Tool for Research and Strain Optimisation Doctor of Philosophy Doctorate Part Time Mr Tom Angus Lang
    2016 - 2021 Principal Supervisor Biological Solutions to 3-Isobutyl-2-Methoxypyrazine Remediation in Wine Doctor of Philosophy Doctorate Full Time Ms Jin-Chen Li
    2016 - 2020 Principal Supervisor Identification and Understanding of Saccharomyces and Oenococcus Interactions in Wine Fermentation Doctor of Philosophy Doctorate Full Time Miss Louise Joyce Bartle
    2015 - 2019 Co-Supervisor Exploration of Using Cyclodextrins as Novel Additives and Fining Agents in Wine Doctor of Philosophy Doctorate Full Time Mr Chao Dang
    2014 - 2017 Principal Supervisor Identification of Yeast Genes Enabling Efficient Oenological Fermentation under Nitrogen-limited Conditions Doctor of Philosophy Doctorate Full Time Mrs Josephine Jasmine Peter
    2014 - 2018 Co-Supervisor Selective Use of Winemaking Supplements to Modulate the Chemical Composition and Sensory Properties of Shiraz Wine Doctor of Philosophy Doctorate Full Time Miss Sijing Li
    2014 - 2018 Principal Supervisor Managing Ethanol and Sensory Compounds by Non-Saccharomyces Yeasts Doctor of Philosophy Doctorate Full Time Dr Ana Hranilovic
    2014 - 2019 Principal Supervisor Impact of High Sugar Content on Metabolism and Physiology of Indigenous Yeasts Doctor of Philosophy Doctorate Full Time Mr Federico Alessandro Tondini
    2014 - 2017 Principal Supervisor Identification of Yeast Genes Affecting Production of Hydrogen Sulfide and Volatile Thiols from Cysteine Treatment during Fermentation Doctor of Philosophy Doctorate Full Time Mr Chien-Wei Huang
    2014 - 2018 Co-Supervisor Preparation and application of new sorptive polymers applied to wine with a focus on removal of 3-isobutyl-2-methoxypyrazine Doctor of Philosophy Doctorate Full Time Ms Chen Liang
    2014 - 2017 Principal Supervisor Phenotypic Investigation of Biofilm Formation and Transcriptional Analysis of Invasive Growth of Commercial Wine Saccharomyces cerevisiae Doctor of Philosophy Doctorate Full Time Ms Ee Lin Tek
    2013 - 2017 Principal Supervisor Use of Directed Evolution to Generate Multiple-stress Tolerant Oenococcus oeni for Enhanced Malolactic Fermentation Doctor of Philosophy Doctorate Full Time Miss Jiao Jiang
    2010 - 2015 Principal Supervisor A multipronged approach to encouraging proline utilisation by wine yeast Doctor of Philosophy Doctorate Full Time Ms Danfeng Long
    2010 - 2016 Co-Supervisor Characterisation of the wine meta-metabolome: linking aroma profiles to yeast genotype Doctor of Philosophy Doctorate Full Time Mrs Jade Joyce Haggerty
    2010 - 2014 Principal Supervisor Determination of the genetic basis for successful fermentation in high sugar media Doctor of Philosophy Doctorate Full Time Dr Trung Dung Nguyen
    2010 - 2014 Principal Supervisor Investigation and Characterisation of Highly Nitrogen Efficient Wine Yeast Doctor of Philosophy Doctorate Full Time Dr Jin Zhang
    2009 - 2015 Co-Supervisor Enhanced winemaking efficiency through foolproof malolactic fermentation: Evolution of superior lactic acid bacteria Doctor of Philosophy Doctorate Full Time Dr Alice Livingston Betteridge
    2007 - 2012 Principal Supervisor Genes and Mechanisms Responsible for Beta-Glucose Metabolism in the Oenologically Important Lactic Acid Bacterium Oenococcus Oeni Doctor of Philosophy Doctorate Part Time Dr Alana Seabrook
    2007 - 2013 Principal Supervisor Molecular and Biochemical Characterisation of Esterases from Oenococcus oeni and Their Potential For Application In Wine. Doctor of Philosophy Doctorate Part Time Dr Krista Sumby
    2007 - 2011 Principal Supervisor Improving fructose utilization in wine yeast using adaptive evolution Doctor of Philosophy Doctorate Full Time Dr Tommaso Watson
    2004 - 2009 Co-Supervisor Physiological, Biochemical and Molecular Characterisation of Hydroxycinnamic Acid Catabolism by Dekkera and Brettanomyces Yeasts Doctor of Philosophy Doctorate Part Time Miss Victoria Harris
    2002 - 2006 Principal Supervisor Development of Novel Wine Yeast Strains Using Adaptive Evolution Doctor of Philosophy Doctorate Full Time Mr Colin McBryde
    2002 - 2007 Principal Supervisor Biochemical and Molecular Characterisation of Oenologically Important Enzymes Identified in Lactic Acid Bacteria Doctor of Philosophy Doctorate Full Time Miss Angela Matthews
    2001 - 2007 Principal Supervisor Characterisation of Glycosidase Enzymes of Wine Lactic Acid Bacteria Doctor of Philosophy Doctorate Full Time Mr Antonio Grimaldi
    2000 - 2006 Principal Supervisor Identification of Genomic Differences Between Laboratory and Commercial Strains of Saccharomyces Cerevisiae Doctor of Philosophy Doctorate Full Time Mr Anthony Heinrich
    1999 - 2006 Principal Supervisor Identification of Genes affecting Glucose Catabolism in Nitrogen-limited Fermentation Doctor of Philosophy Doctorate Full Time Dr Jennifer Gardner
    1998 - 2002 Principal Supervisor Enhancing yeast performance under oenological conditions by enabling proline utilisation Doctor of Philosophy Doctorate Full Time Ms Kathryn Poole
    1998 - 2003 Principal Supervisor CHARACTERISATION OF CARBOHYDRATE METABOLISM BY INDUSTRIAL STRAINS OF SACCHAROMYCES CEREVISIAE YEAST Doctor of Philosophy Doctorate Part Time Mr Florante Jon Meneses
  • Editorial Boards

    Date Role Editorial Board Name Institution Country
    2012 - ongoing Associate Editor Australian Journal of Grape and Wine Research - Australia
  • Offices Held

    Date Office Name Institution Country
    2016 - ongoing Commissioner (Australia) International Commission on Yeast - Australia
    2015 - ongoing Member Editorial Board FEMS Yeast Research - -
    2013 - 2016 Board Member (SA Rep), Australian Society of Viticulture and Oenology - -
    2012 - 2014 Convenor, Wine Science and Business Research Group University of Adelaide -
    2012 - 2014 Chair, National Wine Researchers Network - -
    2007 - 2012 Editor-in-Chief, Australian Journal of Grape and Wine Research - -
  • Position: Professor
  • Phone: 83136651
  • Email: vladimir.jiranek@adelaide.edu.au
  • Fax: 83137415
  • Campus: Waite
  • Building: Wine Innovation Central, floor 3
  • Org Unit: Agricultural Science

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