Fakultät Naturwissenschaften

Permanent URI for this communityhttps://hohpublica.uni-hohenheim.de/handle/123456789/1

Biologie, Ernährungs-wissenschaften und Lebensmittelwissenschaften sind die Schwerpunkte der Fakultät. Die Forschung befasst sich mit Schlüsselthemen der Life Sciences.

Homepage: https://natur.uni-hohenheim.de/

Browse

Now showing 1 - 18 of 18

Almond-like aroma formation of acid whey by Ischnoderma benzoinum fermentation: potential application in novel beverage development
(2025) Hannemann, Lea; Klauss, Raphaela; Gleissle, Anne; Heinrich, Patrick; Braunbeck, Thomas; Zhang, Yanyan
To address the sourish off-aroma of acid whey and enhance its upcycling, a new basidiomycete Ischnoderma benzoinum -mediated fermentation system was developed using pure acid whey as the sole substrate. A pleasant sweetish and marzipan-like odor was perceived after fermentation within 7 d at 24 °C in darkness, which was shaped from key contributors including 4-methoxybenzaldehyde (odor activity value (OAV) 878), 3-methylbutanal (OAV 511), 3,4-dimethoxybenzaldehyde (OAV 50), and benzaldehyde (OAV 28). The typical sweetish and almond-like odor persisted well after ultrahigh-temperature processing, though its intensity decreased slightly. Concurrently, the fermentation reduced lactose from 52 to 20 g/L but increased the contents of essential amino acids like threonine, leucine, and lysine. No significant cytotoxicity or genotoxicity differences were found between fermented and unfermented whey. Overall, the study highlights the capability of I. benzoinum fermentation to enhance the flavor of acid whey, offering a promising approach for creating nutritional and flavorful acid-whey-based products.
Construction and description of a constitutive plipastatin mono-producing Bacillus subtilis
(2020) Vahidinasab, Maliheh; Lilge, Lars; Reinfurt, Aline; Pfannstiel, Jens; Henkel, Marius; Morabbi Heravi, Kambiz; Hausmann, Rudolf
Background: Plipastatin is a potent Bacillus antimicrobial lipopeptide with the prospect to replace conventional antifungal chemicals for controlling plant pathogens. However, the application of this lipopeptide has so far been investigated in a few cases, principally because of the yield in low concentration and unknown regulation of biosynthesis pathways. B. subtilis synthesizes plipastatin by a non-ribosomal peptide synthetase encoded by the ppsABCDE operon. In this study, B. subtilis 3NA (a non-sporulation strain) was engineered to gain more insights about plipastatin mono-production. Results: The 4-phosphopantetheinyl transferase Sfp posttranslationally converts non-ribosomal peptide synthetases from inactive apoforms into their active holoforms. In case of 3NA strain, sfp gene is inactive. Accordingly, the first step was an integration of a repaired sfp version in 3NA to construct strain BMV9. Subsequently, plipastatin production was doubled after integration of a fully expressed degQ version from B. subtilis DSM10T strain (strain BMV10), ensuring stimulation of DegU-P regulatory pathway that positively controls the ppsABSDE operon. Moreover, markerless substitution of the comparably weak native plipastatin promoter (Ppps) against the strong constitutive promoter Pveg led to approximately fivefold enhancement of plipastatin production in BMV11 compared to BMV9. Intriguingly, combination of both repaired degQ expression and promoter exchange (Ppps::Pveg) did not increase the plipastatin yield. Afterwards, deletion of surfactin (srfAA-AD) operon by the retaining the regulatory comS which is located within srfAB and is involved in natural competence development, resulted in the loss of plipastatin production in BMV9 and significantly decreased the plipastatin production of BMV11. We also observed that supplementation of ornithine as a precursor for plipastatin formation caused higher production of plipastatin in mono-producer strains, albeit with a modified pattern of plipastatin composition. Conclusions: This study provides evidence that degQ stimulates the native plipastatin production. Moreover, a full plipastatin production requires surfactin synthetase or some of its components. Furthermore, as another conclusion of this study, results point towards ornithine provision being an indispensable constituent for a plipastatin mono-producer B. subtilis strain. Therefore, targeting the ornithine metabolic flux might be a promising strategy to further investigate and enhance plipastatin production by B. subtilis plipastatin mono-producer strains.
Consumption of yeast-fermented wheat and rye breads increases colitis and mortality in a mouse model of colitis
(2022) Zimmermann, Julia; De Fazio, Luigia; Kaden-Volynets, Valentina; Hitzmann, Bernd; Bischoff, Stephan C.
Background: Cereals are known to trigger for wheat allergy, celiac disease and non-celiac wheat sensitivity (NCWS). Inflammatory processes and intestinal barrier impairment are suspected to be involved in NCWS, although the molecular triggers are unclear. Aims: We were interested if different bread types influence inflammatory processes and intestinal barrier function in a mouse model of inflammatory bowel disease. Methods: Epithelial caspase-8 gene knockout (Casp8 ΔIEC ) and control (Casp8 fl ) mice were randomized to eight groups, respectively. The groups received different diets for 28 days (gluten-free diet, gluten-rich diet 5 g%, or different types of bread at 50 g%). Breads varied regarding grain, milling and fermentation. All diets were isocaloric. Results: Regardless of the diet, Casp8 ΔIEC mice showed pronounced inflammation in colon compared to ileum, whereas Casp8 fl mice were hardly inflamed. Casp8 fl mice could tolerate all bread types. Especially yeast fermented rye and wheat bread from superfine flour but not pure gluten challenge increased colitis and mortality in Casp8 ΔIEC mice. Hepatic expression of lipopolysaccharide-binding protein and colonic expression of tumor necrosis factor-α genes were inversely related to survival. The bread diets, but not the gluten-rich diet, also decreased colonic tight junction expression to variable degrees, without clear association to survival and inflammation. Conclusions: Bread components, especially those from yeast-fermented breads from wheat and rye, increase colitis and mortality in Casp8 ΔIEC mice highly susceptible to intestinal inflammation, whereas control mice can tolerate all types of bread without inflammation. Yet unidentified bread components other than gluten seem to play the major role.
Crop cultivation in the Talayotic settlement of Son Fornés (Mallorca, Spain): agricultural practices on the western Mediterranean islands in the first millennium bce
(2024) Stika, Hans-Peter; Neugebauer, Aleta; Rihuete-Herrada, Cristina; Risch, Roberto; Micó, Rafael; Voltas, Jordi; Amengual, Paula; Gelabert, Lara; Lull, Vicente
The Balearic Islands were colonised around the transition from the Chalcolithic to the Bronze Age, not earlier than 2300 cal bce and certainly much later than any central or eastern Mediterranean islands. The number of archaeobotanical records is low and consists mainly of cereals and a few pulses. We present here new results of our long-term study of Son Fornés, an archaeological site on Mallorca which was occupied since the beginning of the Iron Age Talayotic period (~ 850 cal bce ) and until Roman times (123 bce onwards), in the Balearic Islands. In the Talayotic period of Son Fornés Hordeum vulgare var. vulgare (hulled barley) and Triticum aestivum/durum/turgidum (free-threshing wheat) were the main cereals grown and Vicia faba (broad bean) was the main pulse, while Avena sp. (oats) is considered to have been a weed but was nonetheless consumed and was probably in an early phase of being domesticated. For the subsequent post-Talayotic (ca. 550 − 250 bce ), Classic I and Classic II, the Republican Roman occupation period (from 123 bce onwards) the databases are weak, displaying hulled barley as the main crop and broad bean as the main pulse. The archaeobotanical records of Ficus carica (fig), Olea europaea (olive) and Vitis vinifera (grapevine) represent wild or cultivated and domesticated forms. Prunus dulcis (almond) and Pinus pinea (stone pine) were found on Eivissa (Ibiza), pointing to a Phoenician introduction to the islands, while Phoenix dactylifera (date palm) and Castanea sativa (chestnut), found on Menorca, might have been brought in by the Romans. The number of crops being used on the Balearic Islands was limited when compared to sites of similar periods on the European mainland or the central and eastern Mediterranean islands. According to carbon isotope results of Δ 13 C, hulled barley grew under damper conditions than free-threshing wheat. The high δ 15 N values indicated that both crops were well-manured with animal dung during the entire occupation period.
Disc mower versus bar mower: Evaluation of the direct effects of two common mowing techniques on the grassland arthropod fauna
(2025) von Berg, Lea; Frank, Jonas; Betz, Oliver; Steidle, Johannes L. M.; Böttinger, Stefan; Sann, Manuela
1. In Central Europe, species‐rich grasslands are threatened by intensive agriculture with frequent mowing, contributing to the reduction of arthropods such as insects and spiders. However, comprehensive and standardised studies on the direct effects of the two most agriculturally relevant mowing techniques, e.g., double‐blade bar mower versus disc mower, are lacking. 2. In a 2‐year experiment, we have investigated the direct effect of mowing on eight abundant arthropod groups in grassland, covering two seasonal mowing events in both years, using a randomised block design. We compared (a) an unmown control, (b) a double‐blade bar mower and (c) a disc mower. 3. For most of the taxonomic groups studied, a significantly lower number of individuals was found in the experimental plots immediately after mowing, regardless of the mowing technique, compared to an unmown control. This was not the case for Orthoptera and Coleoptera, which did not show a significant reduction in the number of individuals for both mowing techniques (Orthoptera) or only for the double‐blade bar mower (Coleoptera). 4. Between both mowing techniques, no significant differences were found for all taxonomic groups investigated. 5. Synthesis and applications: Our findings suggest that mowing in general has a negative impact on abundant arthropod groups in grassland, regardless of the method used. Tractor‐driven double‐blade bar mowers do not seem to be a truly insect‐friendly alternative to a conventional disc mower. Other factors such as cutting height and mowing regimes should be seriously considered to protect spiders and insects from the negative effects of mowing. In addition, we strongly recommend the maintenance of unmown refugia. Insects and spiders that are spared by mowing can take refuge in these unmown areas to avoid subsequent harvesting and thermally unfavourable conditions that arise on mown areas. Further, unmown refugia are basic habitat structures for a subsequent recolonisation of mown areas once the flora has recovered.
Food fermentation: an essential unit operation towards secure, sustainable, safe, and sustaining food systems
(2025) Gänzle, Michael G.; Seifert, Jana; Weiss, Jochen; Zijlstra, Ruurd T.
Food informatics - Review of the current state-of-the-art, revised definition, and classification into the research landscape
(2021) Krupitzer, Christian; Stein, Anthony
Background: The increasing population of humans, changing food consumption behavior, as well as the recent developments in the awareness for food sustainability, lead to new challenges for the production of food. Advances in the Internet of Things (IoT) and Artificial Intelligence (AI) technology, including Machine Learning and data analytics, might help to account for these challenges. Scope and Approach: Several research perspectives, among them Precision Agriculture, Industrial IoT, Internet of Food, or Smart Health, already provide new opportunities through digitalization. In this paper, we review the current state-of-the-art of the mentioned concepts. An additional concept is Food Informatics, which so far is mostly recognized as a mainly data-driven approach to support the production of food. In this review paper, we propose and discuss a new perspective for the concept of Food Informatics as a supportive discipline that subsumes the incorporation of information technology, mainly IoT and AI, in order to support the variety of aspects tangent to the food production process and delineate it from other, existing research streams in the domain. Key Findings and Conclusions: Many different concepts related to the digitalization in food science overlap. Further, Food Informatics is vaguely defined. In this paper, we provide a clear definition of Food Informatics and delineate it from related concepts. We corroborate our new perspective on Food Informatics by presenting several case studies about how it can support the food production as well as the intermediate steps until its consumption, and further describe its integration with related concepts.
Functionality of the Na+-translocating NADH:quinone oxidoreductase and quinol:fumarate reductase from Prevotella bryantii inferred from homology modeling
(2024) Hau, Jann-Louis; Schleicher, Lena; Herdan, Sebastian; Simon, Jörg; Seifert, Jana; Fritz, Günter; Steuber, Julia
Members of the family Prevotellaceae are Gram-negative, obligate anaerobic bacteria found in animal and human microbiota. In Prevotella bryantii , the Na + -translocating NADH:quinone oxidoreductase (NQR) and quinol:fumarate reductase (QFR) interact using menaquinone as electron carrier, catalyzing NADH:fumarate oxidoreduction. P. bryantii NQR establishes a sodium-motive force, whereas P. bryantii QFR does not contribute to membrane energization. To elucidate the possible mode of function, we present 3D structural models of NQR and QFR from P. bryantii to predict cofactor-binding sites, electron transfer routes and interaction with substrates. Molecular docking reveals the proposed mode of menaquinone binding to the quinone site of subunit NqrB of P. bryantii NQR. A comparison of the 3D model of P. bryantii QFR with experimentally determined structures suggests alternative pathways for transmembrane proton transport in this type of QFR . Our findings are relevant for NADH-dependent succinate formation in anaerobic bacteria which operate both NQR and QFR.
Integrating sensor data, laboratory analysis, and computer vision in machine learning-driven E-Nose systems for predicting tomato shelf life
(2025) Senge, Julia Marie; Kaltenecker, Florian; Krupitzer, Christian
Assessing the quality of fresh produce is essential to ensure a safe and satisfactory product. Methods to monitor the quality of fresh produce exist; however, they are often expensive, time-consuming, and sometimes require the destruction of the sample. Electronic Nose (E-Nose) technology has been established to track the ripeness, spoilage, and quality of fresh produce. Our study developed a freshness monitoring system for tomatoes, combining E-Nose technology with storage condition monitoring, color analysis, and weight-loss tracking. Different post-purchase scenarios were investigated, focusing on the influence of temperature and mechanical damage on shelf life. Support Vector Classifier (SVC) and k-Nearest Neighbor (kNN) were applied to classify storage scenarios and storage days, while Support Vector Regression (SVR) and kNN regression were used for predicting storage days. By using a data fusion approach with Linear Discriminant Analysis (LDA), the SVC achieved an accuracy of 72.91% in predicting storage days and an accuracy of 86.73% in distinguishing between storage scenarios. The kNN yielded the best regression results, with a Mean Absolute Error (MAE) of 0.841 days and a coefficient of determination of 0.867. The results highlight the method’s potential to predict storage scenarios and storage days, providing insight into the product’s remaining shelf life.
Das Land‐Atmosphäre‐System der Erde: die „Erdung“ von Wetter‐ und Klimaprozessen
(2025) Wulfmeyer, Volker; Jach, Lisa; Branch, Oliver; Breil, Marcus
Das System Land-Atmosphäre umfasst den Boden, die Landbedeckung und die untere Troposphäre. Die komplexen Prozesse in diesem System sind gekoppelt über den Austausch von Impuls, Energie und Masse. Unter anderem spielt der Pflanzenbewuchs eine zentrale Rolle. Daher ist ein tiefgreifendes Verständnis dieses Systems fundamental für die Genauigkeit von Wettervorhersagen, mittelfristige bis subsaisonale Vorhersagen und Klimaprognosen. Dazu gehört auch die Vorhersage von Extremereignissen wie Dürren.
Limitations of soil-applied non-microbial and microbial biostimulants in enhancing soil P turnover and recycled P fertilizer utilization: A study with and without plants
(2024) Herrmann, Michelle Natalie; Griffin, Lydia Grace; John, Rebecca; Mosquera-Rodríguez, Sergio F.; Nkebiwe, Peteh Mehdi; Chen, Xinping; Yang, Huaiyu; Müller, Torsten
Introduction: Phosphorus recovery from waste streams is a global concern due to open nutrient cycles. However, the reliability and efficiency of recycled P fertilizers are often low. Biostimulants (BS), as a potential enhancer of P availability in soil, could help to overcome current barriers using recycled P fertilizers. For this, a deeper understanding of the influence of BSs on soil P turnover and the interaction of BSs with plants is needed. Methods: We conducted an incubation and a pot trial with maize in which we testednon-microbial (humic acids and plant extracts) and microbial BSs (microbial consortia) in combination with two recycled fertilizers for their impact on soil P turnover, plant available P, and plant growth. Results and discussion: BSs could not stimulate P turnover processes (phosphatase activity, microbial biomass P) and had a minor impact on calcium acetate-lactate extractable P (CAL-P) in the incubation trial. Even though stimulation of microbial P turnover by the microbial consortium and humic acids in combination with the sewage sludge ash could be identified in the plant trial with maize, this was not reflected in the plant performance and soil P turnover processes. Concerning the recycled P fertilizers, the CAL-P content in soil was not a reliable predictor of plant performance with both products resulting in competitive plant growth and P uptake. While this study questions the reliability of BSs, it also highlights the necessity toimprove our understanding and distinguish the mechanisms of P mobilization in soil and the stimulation of plant P acquisition to optimize future usage.
The low mutational flexibility of the EPSP synthase in Bacillus subtilis is due to a higher demand for shikimate pathway intermediates
(2023) Schwedt, Inge; Schöne, Kerstin; Eckert, Maike; Pizzinato, Manon; Winkler, Laura; Knotkova, Barbora; Richts, Björn; Hau, Jann-Louis; Steuber, Julia; Mireles, Raul; Noda‐Garcia, Lianet; Fritz, Günter; Mittelstädt, Carolin; Hertel, Robert; Commichau, Fabian M.
Glyphosate (GS) inhibits the 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase that is required for aromatic amino acid, folate and quinone biosynthesis in Bacillus subtilis and Escherichia coli. The inhibition of the EPSP synthase by GS depletes the cell of these metabolites, resulting in cell death. Here, we show that like the laboratory B. subtilis strains also environmental and undomesticated isolates adapt to GS by reducing herbicide uptake. Although B. subtilis possesses a GS-insensitive EPSP synthase, the enzyme is strongly inhibited by GS in the native environment. Moreover, the B. subtilis EPSP synthase mutant was only viable in rich medium containing menaquinone, indicating that the bacteria require a catalytically efficient EPSP synthase under nutrient-poor conditions. The dependency of B. subtilis on the EPSP synthase probably limits its evolvability. In contrast, E. coli rapidly acquires GS resistance by target modification. However, the evolution of a GS-resistant EPSP synthase under non-selective growth conditions indicates that GS resistance causes fitness costs. Therefore, in both model organisms, the proper function of the EPSP synthase is critical for the cellular viability. This study also revealed that the uptake systems for folate precursors, phenylalanine and tyrosine need to be identified and characterized in B. subtilis.
Market-based instruments for biodiversity in agricultural landscapes: An evaluation of quality criteria in a German case study
(2025) Streit, Lea; Feuerbacher, Arndt; Röhl, Markus
Market-based instruments (MBIs) for the protection and promotion of biodiversity have gained significant importance in recent years. The success of MBIs depends largely on the transparent presentation of their actual effects, which rely on the quality of implementation. Quality criteria can be used to evaluate this. To date, few studies have examined whether and how these criteria are applied. This study seeks to address this gap, by using MBIs in the German agricultural landscape as a case study. Quality criteria were defined on the basis of a literature review; then applied to MBIs identified through an internet search and finally analyzed. Quality criteria related to methodological approaches (implementation, maintenance, used seed mixtures) and quality control (monitoring, localization) are presented less frequently than information on rights and obligations or the use of financial funds. Among the 151 MBIs analyzed, 70% lack control mechanisms and monitoring systems, indicating unverified effectiveness. Additionally, MBIs financed through program approaches are more likely to have control mechanisms and include perennial measures than MBIs funded by direct payments of sponsors or consumers purchasing a product. The development of MBI offerings suggests that there is persistent and growing demand, as some programs have been running for several decades. However, without ecological monitoring, it is not possible to ascertain whether these measures benefit biodiversity. To establish standardized methods for comparing MBIs for biodiversity, policymakers must consider official guidelines and, where appropriate, implement regulatory frameworks.
Monodopsis subterranea is a source of α‐tocomonoenol, and its concentration, in contrast to α‐tocopherol, is not affected by nitrogen depletion
(2024) Montoya‐Arroyo, Alexander; Muñoz‐González, Alejandra; Lehnert, Katja; Frick, Konstantin; Schmid‐Staiger, Ulrike; Vetter, Walter; Frank, Jan
α-Tomonoenols (αT1) are tocochromanols structurally related to tocopherols (T) and tocotrienols (T3), the bioactive members of the vitamin E family. However, limited evidence exists regarding the sources and biosynthesis of tocomonoenols. Nitrogen depletion increases the content of α-tocopherol (αT), the main vitamin E congener, in microalgae, but little is known regarding its effect on other tocochromanols, such as tocomonoenols and tocotrienols. We therefore quantified the concentrations of T, T1, and T3, in freeze-dried biomass from nitrogen-sufficient, and nitrogen-depleted Monodopsis subterranea (Eustigmatophyceae). The identities of isomers of αT1 were confirmed by LC–MS and GC–MS. αT was the predominant tocochromanol (82% of total tocochromanols). αT1 was present in higher quantities than the sum of all T3 (6% vs. 1% of total tocochromanols). 11′-αT1 was the main αT1 isomer. Nitrogen depletion increased αT, but not αT1 or T3 in M. subterranea. In conclusion, nitrogen depletion increased the content of αT, the biologically most active form of vitamin E, in M. subterranea without affecting αT1 and T3 and could potentially be used as a strategy to enhance its nutritional value but not to increase αT1 content, indicating that αT1 accumulation is independent of that of αT in microalgae.
Multidisciplinary study of the health and nutritional status of persons living in households at risk of poverty with children in Germany (MEGA_kids): study design and methods
(2024) Simmet, Anja; Ehret, Janine; Schleicher, Romy; Teut, Michael; Hummel, Gerrit; Bschaden, Andreas; Stroebele-Benschop, Nanette
Background: In Germany, the nutritional situation of adults and children living in households at risk of poverty has been insufficiently studied so far. Aim: The aim of the mixed-methods study MEGA_kids is to gain a deeper understanding of the nutritional situation including socioeconomic, behavioral, and attitudinal factors and health characteristics among persons living in families at risk of poverty. Method: MEGA_kids is a mixed-methods cross-sectional study consisting of four modules combining quantitative and qualitative methods. The first module (A) applies self-administered questionnaires to assess the individual's diet, household food insecurity, and several other factors among adults and children of 500 households. Cash receipts are used to assess household's food expenses. For the second module (B), a semistructured interview guide is used to identify factors influencing food security and nutritional quality from the perspective of a subsample of module A (n = 20). The third module (C) applies the participatory World Café technique to explore experiences and generate ideas for tailored support measures for a healthy diet from the perspective of 40 parents participating in module A. Finally, the fourth module (D) investigates the knowledge and usage of existing nutrition-related preventive measures among 200 parents at risk of poverty by using an online questionnaire. Conclusion: By providing a comprehensive picture of nutritional aspects of families living at risk of poverty, MEGA_kids will guide officials to target and prioritize public health nutrition measures, inform policy makers to implement and improve healthy policies and, finally, identify research gaps to be prioritized.
Potentially beneficial effects on healthy aging by supplementation of the EPA-rich microalgae phaeodactylum tricornutum or its supernatant - a randomized controlled pilot trial in elderly individuals
(2022) Stiefvatter, Lena; Frick, Konstantin; Lehnert, Katja; Vetter, Walter; Montoya-Arroyo, Alexander; Frank, Jan; Schmid-Staiger, Ulrike; Bischoff, Stephan C.
Dietary supplements that promote healthy aging are mostly warranted in an aging society. Because of age-related risks, anti-inflammatory and anti-oxidative agents such as microalgae are potential candidates for intervention. In a randomized controlled trial, we tested Phaeodactylum tricornutum (PT), a microalgae rich in eicosapentaenoic acid (EPA), carotenoids, vitamins, and β-glucans, cultured in bioreactors. In this pilot trial, 19 healthy elderly received supplements for two weeks based on either the whole PT (A), the β-1,3-glucan-rich PT supernatant (SupB), the combination thereof (A+SupB), or a Comparator product (Comp). The primary outcome variable plasma interleukin-6 was reduced after treatment with A+SupB compared to the Comp group (p = 0.04). The mobility parameters 5 s sit-to-stand test (p = 0.04 in the A group) and by trend gait speed (p = 0.08 in the A+SupB diet) were improved compared to Comp. No treatment effects were observed for fatty acids, compared to Comp but omega-6 to -3 fatty acid ratio (p = 0.006) and arachidonic acid/EPA ratio (p = 0.006) were reduced within group A+SupB. Further, the SupB study product reduced faecal zonulin (p = 0.03) compared to the Comp. The data revealed an anti-inflammatory and potentially anti-oxidative effect of particular PT preparations, suggesting that they might be suitable for effects in healthy elderly.
Recombinant production of bovine αS1-casein in genome-reduced Bacillus subtilis strain IIG-Bs-20-5-1
(2025) Biermann, Lennart; Tadele, Lea Rahel; Benatto Perino, Elvio Henrique; Nicholson, Reed; Lilge, Lars; Hausmann, Rudolf; Fouillaud, Mireille
Background: Cow’s milk represents an important protein source. Here, especially casein proteins are important components, which might be a promising source of alternative protein production by microbial expression systems. Nevertheless, caseins are difficult-to-produce proteins, making heterologous production challenging. However, the potential of genome-reduced Bacillus subtilis was applied for the recombinant production of bovine αS1-casein protein. Methods: A plasmid-based gene expression system was established in B. subtilis allowing the production of his-tagged codon-optimized bovine αS1-casein. Upscaling in a fed-batch bioreactor system for high cell-density fermentation processes allowed for efficient recombinant αS1-casein production. After increasing the molecular abundance of the recombinant αS1-casein protein using immobilized metal affinity chromatography, zeta potential and particle size distribution were determined in comparison to native bovine αS1-casein. Results: Non-sporulating B. subtilis strain BMV9 and genome-reduced B. subtilis strain IIG-Bs-20-5-1 were applied for recombinant αS1-casein production. Casein was detectable only in the insoluble protein fraction of the genome-reduced B. subtilis strain. Subsequent high cell-density fed-batch bioreactor cultivations using strain IIG-Bs-20-5-1 resulted in a volumetric casein titer of 56.9 mg/L and a yield of 1.6 mgcasein/gCDW after reducing the B. subtilis protein content. Comparative analyses of zeta potential and particle size between pre-cleaned recombinant and native αS1-casein showed pH-mediated differences in aggregation behavior. Conclusions: The study demonstrates the potential of B. subtilis for the recombinant production of bovine αS1-casein and underlines the potential of genome reduction for the bioproduction of difficult-to-produce proteins.
Stable isotope analysis confirms substantial changes in the fatty acid composition of bacteria treated with antimicrobial random peptide mixtures (RPMs)
(2022) Wiedmaier-Czerny, Nina; Schroth, Dorothee; Krauß, Stephanie; Topman-Rakover, Shiri; Brill, Aya; Burdman, Saul; Hayouka, Zvi; Vetter, Walter
Resistance of plant-pathogenic bacteria to classic antibiotics has prompted the search for suitable alternative antimicrobial substances. One promising strategy could be the use of purposely synthesized random peptide mixtures (RPMs). Six plant-pathogenic bacteria were cultivated and treated with two RPMs previously found to show antimicrobial activity mainly by bacterial membrane disruption. Here, we show that bacteria treated with RPMs showed partly remarkable changes in the fatty acid pattern while those unaffected did not. Quantitative changes could be verified by compound specific isotope analysis of δ 13 C values (‰). This technique was employed due to the characteristic feature of stronger bonds between heavier isotopes in (bio)chemical reactions. As a proof of concept, the increase in abundance of a fatty acid group after RPM treatment was accompanied with a decrease in the 13 C content and vice versa. We propose that our findings will help designing and synthesizing more selective antimicrobial peptides.

Browse

Browsing Fakultät Naturwissenschaften by Sustainable Development Goals "2"