Research in the Department of Microbiology & Biochemistry

Project start: 01.06.2025
Project end: 31.05.2028
Sponsor: German Research Foundation

Our previous work on the mycoparasitism of Saccharomycopsis schoenii showed that the genes KIL1 and STE12 are required for the formation of penetration haustoria. Deletion mutants of these genes are avirulent. In a follow-up project, we will investigate other genes of the associated signal transduction cascade to examine their potential contribution to pathogenicity. Furthermore, we have discovered a family of cysteine-rich effector genes (CRE genes) in Saccharomycopsis. These genes are upregulated during a predation cycle and therefore appear to play a role in the pathogenicity of Saccharomycopsis. This set of genes will also be characterized. We use the model yeast Saccharomyces cerevisiae as prey cells because of its ease of molecular genetic manipulation. This allows us to gain molecular and cell biological insights into the responses of Saccharomyces cerevisiae cells during an attack by Saccharomycopsis schoenii.

Project start: 01.03.2024
Project end: 28.02.2026
Sponsor: Hessen State Ministry of Higher Education, Research and the Arts

Changing environmental conditions often trigger cellular adaptive responses. Deficiency conditions, such as the absence of amino acids or sulfur, lead to a starvation response in the yeast Saccharomyces cerevisiae that is also conserved in other systems, involving a reversible general repression of translation and the activation of amino acid biosynthesis pathways. tRNAs are part of the translation machinery. Defects in tRNA thiolation, a sulfur modification of the wobble uridine, also induce this starvation response in S. cerevisiae. The biocontrol potential of predator yeasts, i.e., their attack on other fungal pathogens, is based on a starvation signal, specifically the absence of the sulfur-containing amino acid methionine. Therefore, we will test the hypothesis that mutation-induced defects in the wobble uridine modification in predator yeasts trigger a starvation signal and lead to the activation of mycoparasitism. If this hypothesis is confirmed, efficient biocontrol yeasts could be generated. This could lead to improved use of predator yeasts against crop and food pests and contribute to a reduced use of chemical pesticides.

Project start: 01.01.2018
Project end: 31.12.2025

Project start: 01.03.2023
Project end: 31.08.2025
Sponsor: German Federation of Industrial Research Associations

Project start: 01.07.2021
Project end: 30.06.2024

Project start: 01.01.2021
Project end: 31.03.2024
Sponsor: German Research Foundation

We have started our work on predator yeasts funded by the EU Innovative Training Network Fungibrain. This resulted in one PhD thesis and two high profile papers (Scientific Reports and PLoS Pathogens) along with several other publications. Predator yeasts belong to the genus Saccharomycopsis. They are necrotrophic mycoparasites that invade and kill fungal prey cells via a penetration peg. We have started to develop molecular genetic tools to investigate the unique and fascinating biology of these yeasts. In this project we will characterize key virulence genes of Saccharomycopsis schoenii and analyze the contribution of these genes for predation and virulence. We will study the process of predation both from the viewpoint of the predator and the prey, for which we use the model eukaryote Saccharomyces cerevisiae as prey.

Project start: 01.01.2018
Project end: 31.12.2022
Sponsor: Hessen State Ministry of Higher Education, Research and the Arts

Many of the aromatic agents, fragrances and vitamins found in foods, cosmetics and pharmaceutical products are plant-based. The fruits of blackcurrant, for example, are not only healthy, but they are also valued for their aroma compounds and essential oils. These substances are becoming increasingly attractive for industrial applications, and sustainable production methods are becoming more and more important. In the LOEWE project "AROMAplus", the research team wants to extract or refine plant metabolites with the help of enzymes and microorganisms such as yeasts, fungi and bacteria. In this process, plant residues resulting from the cultivation of blackcurrants or grapes are used as biological raw materials.

Project start: 01.12.2017
Project end: 31.05.2022
Sponsor: European Commission

This project aims to train the next generation of researchers to provide knowledge and expertise for two major industries in the EU, namely the beer and wine industries. Yeasts belonging to the Saccharomyces stricto sensu group are the workhorses of these industries and an understanding of how yeasts contribute to the complex flavours and aromas of beer and wine is essential for the improvement of existing fermentation technology and for the development new flavoursome beverages. The research objectives of the consortium is to examine the biochemistry and genetics of the production of flavour compounds in yeasts used in wine and beer fermentations, to generate new strains of yeasts with improved or more varied flavour profiles and to develop novel approaches to expanding flavour profiles through co-fermentation of different yeasts. The network will provide a comprehensive education in yeast genetics, synthetic biology, flavour chemistry and fermentation technology for Early Stage Researchers through individual mentored research training in both academic and industrial institutions, through inter- and intra-sectoral exchanges and secondments and through academic workshops. The involvement of industry leaders in the consortium ensures that ESRs will be exposed to real challenges facing fermentation industries and through training in Innovation and Entrepreneurship, ESRs will develop the skills to provide solutions to these challenges. Scientific discourse and communication will be a cornerstone in the training network. ESRs will be encouraged to communicate their ideas with scientific peers and with the public at large to promote an understanding of the role scientific endeavor in the economic development of two of our most important EU industries. The research developed in this project will provide scientific innovation and new and exciting opportunities for the major fermentation industries and for emerging craft beer brewing SMEs.

Project start: 01.07.2016
Project end: 31.08.2018
Sponsor: Hessen State Ministry of Higher Education, Research and the Arts

Climate change cannot currently be ignored and impacts all fields of agriculture. IPCC reports forecast an increase of up to 700 ppm of atmospheric carbon dioxide concentration at the end of the 21st century. Parameters such as elevated global temperature, reduced precipitations in certain areas of the world and increase of atmospheric carbon dioxide concentration are modifying plants’ environment. Grapevine, which is a crop of economic and cultural importance, is very sensitive to climate modifications. The effects of temperature or water stress on grapevine has been widely investigated, and elevated carbon dioxide has been mainly studied in enclosed systems such as greenhouses. However, the impact of increased concentration of carbon dioxide on plants in open-field experiments remains scarcely studied because of the technical challenge that it represents. In this context, the aim of this PhD work was to investigate the impact of elevated carbon dioxide concentration using the set-up VineyardFACE located at Geisenheim University. This open field set-up enables to apply a moderate and gradual increase (+20%) of ambient carbon dioxide concentration on two grapevine cultivars, Riesling, and Cabernet Sauvignon. While knowing the impact of elevated carbon dioxide treatment on leaf physiology and vegetative growth from previous studies (Wohlfahrt et al., 2018), as well as on berry composition during the early years of fumigation, the goal of this study was to determine the effects of elevated carbon dioxide treatment on agronomical traits, primary metabolites (sugars, organic acids, amino acids) and secondary metabolites (anthocyanins, terpenes) on vines undergoing six years of fumigation, as well as monitoring berry development and following berry ripening for successive seasons. Intermediates from central metabolism were also studied for two years (2020 and 2021), and terpene analysis was realized on Riesling must 2021. Our results showed that although photosynthesis was still enhanced, little effects were found of

Project start: 01.11.2014
Project end: 31.05.2018
Sponsor: Forschungsring des Deutschen Weinbaus, Deutsche Landwirtschaftsgesellschaft

Project start: 15.10.2010
Project end: 14.05.2014
Sponsor: Federal Ministry of Food and Agriculture

Of the possibilities investigated for alcohol reduction by microbiological and biochemical means, positive results were found for the use of enzymes (glucose oxidase), the use of non-sSaccharomyces yeasts and the dosed addition of must sugar to a yeast suspension. In the case of enzyme utilisation using GOX as well as "non-sSaccharomyces", the application is relatively easy and entails a low to medium financial input. The use of current genetically modified yeast strains did not produce satisfactory results. Legal regulations are necessary for all the processes examined.

Project start: 01.06.2010
Project end: 31.03.2013
Sponsor: Federal Ministry of Food and Agriculture