Geisenheim University
  • Geisenheim, Hessen, Germany
Recent publications
Three major compounds, 2-acetyl-1-pyrroline (APY), 2-acetyltetrahydropyridine (ATHP) and 2-ethyltetrahydropyridine (ETHP), have been identified as responsible for the mousy off-flavor in wines, although to date quantification data reported in the literature are limited. A simple method for simultaneous quantitation, by SBSE-GC-MS, of these N-heterocyclic compounds was developed. Both previously reported tautomers of ATHP, 2-acetyl-1,4,5,6-tetrahydropyridine and 2-acetyl-3,4,5,6-tetrahydropyridine were identified. The limits of detection and quantification of the method were determined in white, rosé and red wines and are lower than previously published concentrations in spoiled wine. ETHP was detected in almost all wines produced with limited use of SO2. ATHP was detected in almost all wines suspected of mousiness whereas APY was only detected in few cases. This method will provide a support for further studies aimed at understanding the phenomena that influence the occurrence of mousy off-flavor and the oenological parameters that modulate its expression.
Promoting soil functioning by maintaining soil microbial diversity and activity is central for sustainable agriculture. In viticulture, soil management often includes tillage, which poses a multifaceted disturbance to the soil environment and has direct and indirect effects on soil microbial diversity and soil functioning. However, the challenge of disentangling the effects of different soil management practices on soil microbial diversity and functioning has rarely been addressed. In this study, we investigated the effects of soil management on soil bacterial and fungal diversity as well as soil functions (soil respiration and decomposition) using a balanced experimental design with four soil management types in nine vineyards in Germany. Application of structural equation modelling enabled us to investigate the causal relationships of soil disturbance, vegetation cover, and plant richness on soil properties, microbial diversity, and soil functions. We could show that soil disturbance by tillage increased bacterial diversity but decreased fungal diversity. We identified a positive effect of plant diversity on bacterial diversity. Soil respiration showed a positive response to soil disturbance, while decomposition was negatively affected in highly disturbed soils via mediated effects of vegetation removal. Our results contribute to the understanding of direct and indirect effects of vineyard soil management on soil life and aids designing targeted recommendations for agricultural soil management.
Globally, overuse of nitrogen (N) fertilizers in croplands is causing severe environmental pollution. In this context, Gu et al. suggest environmentally friendly and cost-effective N management practices and Hamani et al. highlight the use of microbial inoculants to improve crop yields, while reducing N-associated environmental pollution and N-fertilizer use.
Um die Geschäftseinbußen während der COVID-19-Krise auszugleichen, mussten die touristischen Weinbaubetriebe neue Strategien anwenden. Diese Strategien wurden in einer länderübergreifenden Studie im Jahr 2021 erfasst und verglichen. Die Studie basiert auf einer qualitativen Befragung von Entscheidungsträgern in 70 Weingütern aus den Ländern USA, Australien, Deutschland, Ungarn und Rumänien. Ziel war es, neue und nachhaltige Initiativen und Resilienz-Strategien zu identifizieren, die zur Bewältigung der durch die COVID-19-Pandemie verursachten Schäden umgesetzt wurden. Ebenso sollten die kulturellen Unterschiede in den Reaktionen der einzelnen Länder festgestellt sowie die Perspektiven des Weintourismus in der Zukunft analysiert werden. Die Ergebnisse machen deutlich, dass die Weingüter auf Kreativität und Flexibilität setzten und zeigen gleichzeitig kulturelle Unterschiede auf. Wir können schlussfolgern, dass die wichtigsten Initiativen in den Bereichen CRM-Datenbankmanagement, Förderung des Direktverkaufs und der Digitalisierung, Durchführung von virtuellen Veranstaltungen und Verkostungen sowie dem Angebot neuer Methoden der Produktlieferung lagen, wenn auch in sehr unterschiedlichem Ausmaß. Die Erkenntnisse liefern erste Vorschläge für Best-Practice-Strategien, die Unternehmen im Weintourismus in ihre zukünftige Geschäftsplanung einbeziehen können.
Nachhaltigkeit gewann in den letzten 15 Jahren an Bedeutung und wenn man sich die Tourismusbranche ansieht, ist nachhaltige Entwicklung in aller Munde. Um die Wichtigkeit von Nachhaltigkeit im Bereich Weintourismus und deren einzelne Maßnahmen zu bewerten, wurde eine internationale Studie mit 1,580 Weingütern aus 42 Ländern durchgeführt. Ziel war es, die Einstellung der Produzenten zu verstehen und allgemeine Informationen sowie konkrete Beispiele zur erfolgreichen Umsetzung von nachhaltigem Weintourismus zu erforschen. Darüber hinaus war auch die zukünftig erwartete Wichtigkeit des nachhaltigen Weintourismus ein wichtiger Aspekt der Studie. Die Ergebnisse zeigen, dass Nachhaltigkeit eine entscheidende Rolle für die Weingüter spielt. Ebenso sehen sie im Weintourismus ein wichtiges Werkzeug, ihr gesamtes Unternehmen nachhaltiger auszurichten. Jedoch ergab die Umfrage auch, dass die Winzer Verbesserungsmöglichkeiten bei ihren weintouristischen Angeboten in Bezug auf Nachhaltigkeit sehen. Die Förderung der Biodiversität (ökologisch), die Entwicklung einer langfristigen Unternehmensstrategie (ökonomisch) und ein offener und ehrlicher Umgang mit den Mitarbeitern (sozial) sind nach Ansicht der Produzenten die wirksamsten Maßnahmen, nachhaltigen Weintourismus zu fördern.
Nowadays, grape berries mature earlier due to climate change. Higher sugar contents are observed, whereas lower ones in organic acids, leading to increased pH values. Those biochemical changes have direct consequences on the balance and quality of wines made from such grapes. Chemical acidification, commonly used to compensate for the lack of acidity in musts or wines, includes tartaric, malic, lactic, and citric acids. Fumaric acid (FA), naturally present in the grape berries at low concentrations and already authorized in the member states of the OIV to inhibit malolactic fermentation in wines, seems to be a promising alternative to those acids to lower the pH. However, the evolution of FA levels added at bottling and its impact on wine quality during its conservation have not yet been studied. Therefore, the aim of the present study was to develop and validate a simple method using liquid chromatography coupled with a diode array detector, which can be used routinely for the determination of the added fumaric acid in wines. The proposed and validated method uses a ProntoSIL C-18 analytical column and an isocratic elution with water acidified at 0.1% formic acid. The run time, including column cleaning with acetonitrile and re-equilibration, was 40 minutes.
In conventional winemaking, sulfites have long been used to control oxidation and spoilage microorganisms. However, the current wine trends and growing consumer health concerns have increased the need to seek alternatives to this preservative. In this context, the present study investigated plant-phenolic concentrates and explored their potential to replace the useful properties of SO2 to control oxidations. The concentrates came from ten different plants and were provided by the company Biolethics Europe, from the Netherlands. Laccase activity control assays were performed using the syringaldazine chromogenic substratein must from botrytized grapes, and the oxygen consumption rate was measured using a non-invasive method based on luminescence in model wine solutions. Positive results were obtained in the two essays, which must be complemented with sensory analyzes and monitoring of the evolution of the wines.
De-alcoholized wines are currently experiencing an increasing demand, but are also being discussed very controversially at this time. The de-alcoholization process is usually carried out by distillation processes under vacuum. The treatment is accompanied by a series of changes in terms of analytical and sensory parameters of the wines. Ethanol has a very complex and far ranging influence on the wine sensory character. Even more, the de-alcoholization process goes along with certain losses of aroma components. Several strategies were assessed to buffer and balance the effect of de-alcoholizing wines below 0.5% v/v. Compared to the addition of tannins and mannoproteins, sweetening showed clearer results on the panelist’s preference. The assessment of a commercial resin treatment to recover aroma from de-alcoholization process showed promising results.
As a metaphor, lemons get a bad rap; however the proverb 'if life gives you lemons, make lemonade' is often used in a motivational context. The same could be said of Hanseniaspora in winemaking. Despite its predominance in vineyards and grape must, this lemon-shaped yeast is underappreciated in terms of its contribution to the overall sensory profile of fine wine. Species belonging to this apiculate yeast are known for being common isolates not just on grape berries, but on many other fruits. They play a critical role in the early stages of a fermentation and can influence the quality of the final product. Their deliberate addition within mixed-culture fermentations shows promise in adding to the complexity of a wine and thus provide sensorial benefits. Hanseniaspora species are also key participants in the fermentations of a variety of other foodstuffs ranging from chocolate to apple cider. Outside of their role in fermentation, Hanseniaspora species have attractive biotechnological possibilities as revealed through studies on biocontrol potential, use as a whole-cell biocatalyst and important interactions with Drosophila flies. The growing amount of 'omics data on Hanseniaspora is revealing interesting features of the genus that sets it apart from the other Ascomycetes. This review collates the fields of research conducted on this apiculate yeast genus.
Background Perennial C4 grasses from the genus Miscanthus are widely regarded as leading and promising dedicated bioenergy crops due to their high biomass accumulation on marginal land with low environmental impacts and maintenance requirements over its productive life. There is an urgent socio-political and environmental need to ramp up the production of alternative, affordable and green bioenergy sources and to re-direct the net zero carbon emissions trajectory. Hence, up-scaling of Miscanthus cultivation as a source of biomass for renewable energy could play an important role to strategically address sustainable development goals for a growing bio-based economy. Certain Miscanthus sinensis genotypes are particularly interesting for their biomass productivity across a wide range of locations. As the aromatic biomass component lignin exhibits a higher energy density than cell wall polysaccharides and is generally used as an indicator for heating or calorific value, genetic engineering could be a feasible strategy to develop M. sinensis biomass with increased lignin content and thus improving the energetic value of the biomass. Results For this purpose, transgenic M. sinensis were generated by Agrobacterium-mediated transformation for expression of ZmMYB167, a MYB transcription factor known for regulating lignin biosynthesis in C3 and C4 grasses. Four independent transgenic ZmMYB167 Miscanthus lines were obtained. Agronomic traits such as plant height, tillering and above-ground dry weight biomass of the transgenic plants were not different to that of wild-type control plants. Total lignin content of the transgenic plants was ~ 15–24% higher compared with control plants. However, the structural carbohydrates, glucan and xylan, were decreased by ~ 2–7% and ~ 8–10%, respectively, in the transgenic plants. Moreover, expression of ZmMYB167 in transgenic plants did not alter lignin composition, phenolic compounds or enzymatic saccharification efficiency yields but importantly improved total energy levels in Miscanthus biomass, equivalent to 10% higher energy yield per hectare. Conclusions This study highlights ZmMYB167 as a suitable target for genetic lignin bioengineering interventions aimed at advancing and developing lignocellulosic biomass supply chains for sustainable production of renewable bioenergy.
Foliar anthocyanins, as well as other secondary metabolites, accumulate transiently under nutritional stress. A misconception that only nitrogen or phosphorus deficiency induces leaf purpling/reddening has led to over-use of fertilizers that burden the environment. Here we emphasize that several other nutritional imbalances induce anthocyanin accumulation, and nutrient-specific differences in this response have been reported for some deficiencies. A range of ecophysiological functions have been attributed to anthocyanins. We discuss the proposed functions and signalling pathways that elicit anthocyanin synthesis in nutrient-stressed leaves. Knowledge from the fields of genetics, molecular biology, ecophysiology, and plant nutrition are combined to deduce how and why anthocyanins accumulate under nutritional stress. Future research to fully understand the mechanisms and nuances of foliar anthocyanin accumulation in nutrient-stressed crops could be utilized to allow these leaf pigments to act as bio-indicators for demand-oriented application of fertilizers. This would benefit the environment, being timely due to the increasing impact of the climate crisis on crop performance.
Modeling cotton plant growth is an important aspect of improving cotton yields and fiber quality and optimizing land management strategies. High-throughput phenotyping (HTP) systems, including those using high-resolution imagery from unmanned aerial systems (UAS) combined with sensor technologies, can accurately measure and characterize phenotypic traits such as plant height, canopy cover, and vegetation indices. However, manual assessment of plant characteristics is still widely used in practice. It is time-consuming, labor-intensive, and prone to human error. In this study, we investigated the use of a data-processing pipeline to estimate cotton plant height using UAS-derived visible-spectrum vegetation indices and photogrammetric products. Experiments were conducted at an experimental cotton field in Aliartos, Greece, using a DJI Phantom 4 UAS in five different stages of the 2022 summer cultivation season. Ground Control Points (GCPs) were marked in the field and used for georeferencing and model optimization. The imagery was used to generate dense point clouds, which were then used to create Digital Surface Models (DSMs), while specific Digital Elevation Models (DEMs) were interpolated from RTK GPS measurements. Three (3) vegetation indices were calculated using visible spectrum reflectance data from the generated orthomosaic maps, and ground coverage from the cotton canopy was also calculated by using binary masks. Finally, the correlations between the indices and crop height were examined. The results showed that vegetation indices, especially Green Chromatic Coordinate (GCC) and Normalized Excessive Green (NExG) indices, had high correlations with cotton height in the earlier growth stages and exceeded 0.70, while vegetation cover showed a more consistent trend throughout the season and exceeded 0.90 at the beginning of the season.
Background Elevated carbon dioxide concentrations (eCO2), one of the main causes of climate change, have several consequences for both vine and cover crops in vineyards and potentially also for the soil microbiome. Hence soil samples were taken from a vineyard free-air CO2 enrichment (VineyardFACE) study in Geisenheim and examined for possible changes in the soil active bacterial composition (cDNA of 16S rRNA) using a metabarcoding approach. Soil samples were taken from the areas between the rows of vines with and without cover cropping from plots exposed to either eCO2 or ambient CO2 (aCO2). Results Diversity indices and redundancy analysis (RDA) demonstrated that eCO2 changed the active soil bacterial diversity in grapevine soil with cover crops (p-value 0.007). In contrast, the bacterial composition in bare soil was unaffected. In addition, the microbial soil respiration (p-values 0.04—0.003) and the ammonium concentration (p-value 0.003) were significantly different in the samples where cover crops were present and exposed to eCO2. Moreover, under eCO2 conditions, qPCR results showed a significant decrease in 16S rRNA copy numbers and transcripts for enzymes involved in N2 fixation and NO2⁻ reduction were observed using qPCR. Co-occurrence analysis revealed a shift in the number, strength, and patterns of microbial interactions under eCO2 conditions, mainly represented by a reduction in the number of interacting ASVs and the number of interactions. Conclusions The results of this study demonstrate that eCO2 concentrations changed the active soil bacterial composition, which could have future influence on both soil properties and wine quality.
In this comment, we scrutinize how research is being challenged by the 2030 Agenda and what may be required for research to contribute to transformative change toward sustainability. Building on the current debate and state of knowledge, we argue that we need a stronger engagement with norms and values within science. Conflicting goals, values and visions need to be made explicit and taken into account in the (co-)production of knowledge in a transparent way. This requires the ability for normative reflection on the part of scientists, both about the norms at play and their own role. To produce transformative-oriented knowledge needed for the implementation of the sustainable development goals, we argue, fundamental changes are required within the science system, from the production to the assessment of knowledge.
Although synthetic pesticides play a major role in plant protection, their application needs to be reduced because of their negative impact on the environment. This applies also to copper preparations, which are used in organic farming. For this reason, alternatives with less impact on the environment are urgently needed. In this context, we evaluated eight isolates of the genus Lysobacter (mainly Lysobacter enzymogenes) for their activity against plant pathogens. In vitro, the investigated Lysobacter isolates showed broad antagonistic activity against several phytopathogenic fungi, oomycetes and bacteria. Enzyme assays revealed diverse activities for the tested isolates. The most promising L. enzymogenes isolate (LEC) was used for further detailed analyses of its efficacy and effective working concentrations. The experiments included in vitro spore and sporangia germination tests and leaf disc assays as well as ad planta growth chamber trials against Alternaria solani and Phytophthora infestans on tomato plants, Pseudoperonospora cubensis on cucumbers and Venturia inaequalis on young potted apple trees. When applied on leaves, dilutions of a culture suspension of LEC had a concentration-dependent, protective effect against the tested pathogens. In all pathosystems tested, the effective concentrations were in the range of 2.5–5% and similarly efficacious to common plant protection agents containing copper hydroxide, wettable sulphur or fenhexamid. Thus, the isolate of L. enzymogenes identified in this study exhibits a broad activity against common plant pathogens and is therefore a promising candidate for the development of a microbial biocontrol agent.
Anthocyanins in red cabbage, sweet potato, and Tradescantia pallida leaves were characterised. A total of 18 non-, mono-, and diacylated cyanidins was identified in red cabbage by high performance liquid chromatography-diode array detection coupled to high-resolution and multi-stage mass spectrometry. Sweet potato leaves contained 16 different cyanidin- and peonidin glycosides being predominantly mono- and diacylated. In T. pallida leaves, the tetra-acylated anthocyanin tradescantin prevailed. The large proportion of acylated anthocyanins resulted in a superior thermal stability during heating of aqueous model solutions (pH 3.0) coloured with red cabbage and purple sweet potato extracts as compared to that of a commercial Hibiscus-based food dye. However, their stability was still outperformed by that of the most stable Tradescantia extract. Comparing vis spectra from pH 1-10, the latter had an additional, uncommon absorption maximum at approx. 585 nm at slightly acidic to neutral pH values, yielding intensely red to purple colours.
Demand for sustainably produced biomass is expected to increase with the need to provide renewable commodities, improve resource security, and reduce greenhouse gas emissions in line with COP26 commitments. Studies have demonstrated additional environmental benefits of using perennial biomass crops (PBCs), when produced appropriately, as a feedstock for the growing bioeconomy, including utilisation for bioenergy (with or without carbon capture and storage). PBCs can potentially contribute to Common Agricultural Policy (CAP) (2023‐27) objectives provided they are carefully integrated into farming systems and landscapes. Despite significant research and development (R&D) investment over decades in herbaceous and coppiced woody PBCs, deployment has largely stagnated due to social, economic and policy uncertainties. This paper identifies the challenges in creating policies that are acceptable to all actors. Development will need to be informed by measurement, reporting and verification (MRV) of greenhouse gas emissions reductions and other environmental, economic and social metrics. It discusses interlinked issues that must be considered in the expansion of PBC production: i) available land; ii) yield potential; iii) integration into farming systems; iv) R&D requirements; v) utilisation options; and vi) market systems and the socio‐economic environment. It makes policy recommendations that would enable greater PBC deployment: 1) incentivise farmers and land managers through specific policy measures, including carbon pricing, to allocate their less productive and less profitable land for uses which deliver demonstrable greenhouse gas reductions; 2) enable GHG mitigation markets to develop and offer secure contracts for commercial developers of verifiable low carbon bioenergy and bio‐products; 3) support innovation in biomass utilisation value chains; and 4) continue long‐term, strategic R&D and education for positive environmental, economic and social sustainability impacts.
Soil tillage or herbicide applications are commonly used in agriculture for weed control. These measures may also represent a disturbance for soil microbial communities and their functions. However, the generality of response patterns of microbial communities and functions to disturbance have rarely been studied at large geographical scales. We investigated how a soil disturbance gradient (low, intermediate, high), realized by either tillage or herbicide application, affects diversity and composition of soil bacterial and fungal communities as well as soil functions in vineyards across five European countries. Microbial alpha-diversity metrics responded to soil disturbance sporadically, but inconsistently across countries. Increasing soil disturbance changed soil microbial community composition at the European level. However, the effects of soil disturbance on the variation of microbial communities were smaller compared to the effects of location and soil covariates. Microbial respiration was consistently impaired by soil disturbance, while effects on decomposition of organic substrates were inconsistent and showed positive and negative responses depending on the respective country. Therefore, we conclude that it is difficult to extrapolate results from one locality to others because microbial communities and environmental conditions vary strongly over larger geographical scales.
Wine is composed of multitudinous flavour components and volatile organic compounds that provide this beverage with its attractive properties of taste and aroma. The perceived quality of a wine can be attributed to the absolute and relative concentrations of favourable aroma compounds; hence, increasing the detectable levels of an attractive aroma, such as β-ionone with its violet and berry notes, can improve the organoleptic qualities of given wine styles. We here describe the generation of a new grape-must fermenting strain of Saccharomyces cerevisiae that is capable of releasing β-ionone through the heterologous expression of both the enzyme carotenoid cleavage dioxygenase 1 (CCD1) and its substrate, β-carotene. Haploid laboratory strains of S. cerevisiae were constructed with and without integrated carotenogenic genes and transformed with a plasmid containing the genes of CCD1. These strains were then mated with a sporulated diploid wine industry yeast, VIN13, and four resultant crosses—designated MQ01 to MQ04–which were capable of fermenting the must to dryness were compared for their ability to release β-ionone. Analyses of their fermentation products showed that the MQ01 strain produced a high level of β-ionone and offers a fermenting hybrid yeast with the potential to enhance the organoleptic qualities of wine.
In this study, the aroma-production profiles of seven different Hanseniaspora strains, namely H. guilliermondii, H. meyeri, H. nectarophila, H. occidentalis, H. opuntiae, H. osmophila and H. uvarum were determined in a simultaneous co-inoculation with the wine yeast Saccharomyces cerevisiae Champagne Epernay Geisenheim (Uvaferm CEG). All co-inoculated fermentations with Hanseniaspora showed a dramatic increase in ethyl acetate levels except the two (H. occidentalis and H. osmophila) that belong to the so-called slow-evolving clade, which had no meaningful difference, compared to the S. cerevisiae control. Other striking observations were the almost complete depletion of lactic acid in mixed-culture fermentations with H. osmophila, the more than 3.7 mg/L production of isoamyl acetate with H. guilliermondii, the significantly lower levels of glycerol with H. occidentalis and the increase in certain terpenols, such as citronellol with H. opuntiae. This work allows for the direct comparison of wines made with different Hanseniapora spp. showcasing their oenological potential, including two (H. meyeri and H. nectarophila) previously unexplored in winemaking experiments.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
609 members
Klaus Schaller
  • Department of Soil Fertility and Plant Nutrition
Kai Velten
  • Modeling and Simulation Group
Katrin Kahlen
  • Department of Modeling and Systems Analysis
Judith Kreyenschmidt
  • Department of Fresh Produce Logistics
Ernst Heinrich Ruehl
  • Department of Grapevine Breeding and Grafting
Von-Lade-Str.1, D-65366, Geisenheim, Hessen, Germany