Distinct Carbohydrate Research Articles

Relationship between pyrimidines, purines and fatty acids in milk of dairy cows fed distinct carbohydrate types: a metabolomic approach

The aim of this research was to evaluate changes in the milk metabolome of dairy cows fed different carbohydrate types from silages and concentrates, with special focus on purines and pyrimidines, likely associated with the microbial activity in the rumen. Furthermore, the relationship between the milk fatty acids and pyrimidine and purine metabolism retrieved in milk was investigated for potential correlations between these 2 groups of potential milk biomarkers. Twenty-four lactating dairy cows were used in a crossover design, where each cow received 2 of 4 diets. Diets were formulated based on a 2 by 2 factorial arrangement, using either grass-clover or corn silage as a forage source, and barley or dried beet pulp in the concentrate fraction. Fatty acids and LC-MS metabolome of the milk were analyzed. The milk metabolome and fatty acid concentration could differentiate the 4 diets used in the trial, while the milk metabolome alone could only differentiate the 2 silage types. Milk odd-chain fatty acids (C17:1 and C17:0) were correlated with pyrimidine and purine derivatives, with uric acid being significantly higher in milk samples associated with corn silage diets. Therefore, the results indicate potential differences in microbial protein synthesis between the diets, but a validation with actual ruminal microbial protein synthesis and investigation in digestive biofluids are necessary for further confirmation.

Trivalent Heteroglycoclusters as Focal Point Pseudoenantiomers: Synthesis and Preliminary Biological Evaluation

We describe the synthesis of the first heteroglycoclusters featuring three distinct carbohydrate ligands. The obtained pair of stereoisomeric glycoclusters were named “focal point enantiomers”, as the configuration of the focal point is the only varying stereogenic element in these molecules. The first pair of such diastereomeric heteroglycoclusters was accessible by an efficient sequence of protection and sequential glycosylation steps utilizing a mannosyl, a N‐acetylglucosaminyl, and a galactosyl donor, respectively, which was applied to a prototype azido‐functionalized tris(hydroxymethyl)aminomethane (TRIS) scaffold molecule. The stereoisomers could be distinguished based on an X‐ray structure of one of the isomeric key intermediates. As previously shown with divalent counterparts, such heterotrivalent cluster glycosides are useful tools for studying the fine‐tuning of carbohydrate recognition. The azido functional group at the focal point of the synthetic scaffold molecule was employed in a conjugation reaction with a linker for further immobilization on a gold surface in order to fabricate glyco‐SAMs (self‐assembled monolayers). A preliminary biological evaluation of the focal point enantiomers was performed in solution using the well‐known model lectin Concanavalin A and the important bacterial lectin FimH.

Mini-Review: The Distinct Carbohydrate Active Enzyme Secretome of Rhizopus spp. Represents Fitness for Mycelium Remodeling and Solid-State Plant Food Fermentation.

Rhizopus is a genus of filamentous fungi belonging to the Mucoromycota division. Rhizopus species produce a white, dense mycelium, which is used to create tempeh, a solid-state fermented Asian soybean product, that is gaining renewed attention as a proteinaceous plant food. The profile of carbohydrate-active enzymes (CAZymes) of a fungus or group of fungi, particularly the secretome CAZymes profile, reflects adaptation to different lifestyles and habitats, and has a significant impact on fermentative capacity. This review examines the CAZymes profiles of Rhizopus species focusing on their implication for carbohydrate utilization and solid-state fermentation of plant materials. Through comprehensive genomic assessments and comparisons with other filamentous fungi, we particularly highlight how the unique CAZymes secretome profile is closely correlated with the taxonomy and ecological niches of Rhizopus species. We discuss how the CAZymes secretome capacity of Rhizopus species differs from other fungi and summarize the current state of knowledge regarding the specific CAZymes involved in the modification of carbohydrates in the fungal cell wall and in plant cell walls. We foresee that advanced genomic and proteomic technologies will be used to expand the biotechnology applications of Rhizopus spp.

Impact of conjugation of whey protein concentrate with different carbohydrates: Monitoring structural and technofunctional variations

This study utilized whey protein concentrate (WPC) as the primary protein source, employing the Maillard reaction to link it with three distinct carbohydrates: lactose, maltodextrin, and gum Arabic. Mixtures were prepared with a 1:4 protein-to-carbohydrate ratio, and conjugation was performed using dry heating at a temperature of 60 °C, 50% relative humidity for 8 h processing time. Under the same conditions, native WPC was heated as a control group. The formation of conjugates was tracked by monitoring absorbance changes, browning index (BI), and reduction in free amino groups (FAG). All conjugates exhibited significant loss of FAG, correlating with an increase in BI. Shifts in protein fingerprint bands observed via Fourier Transform Infrared Spectroscopy suggested potential protein-carbohydrate interactions, while X-ray diffraction showed increased sample crystallinity post-conjugation. Solubility assessments across pH levels (3.0–8.0) indicated a 10–13% rise in solubility for conjugated samples compared to mixtures, broadening their potential applications. Moreover, the emulsion stability index demonstrated improved stability after conjugation. Overall, the Maillard reaction-mediated conjugation enhanced the solubility and stability of emulsions.

Comparative Genomic and Functional Analyses for Insights into Pantoea agglomerans Strains Adaptability in Diverse Ecological Niches.

Pantoea agglomerans inhabit diverse ecological niches, ranging from epiphytes and endophytes in plants, body of animals, and occasionally in the human system. This multifaceted bacterium contributes substantially to plant growth promotion, stress resilience, and biocontrol but can also act as a pathogen to its host. The genetic determinants underlying these diverse functions remain largely unfathomed and to uncover this phenomenon,nineteenstrains ofPantoea agglomeranswere selected and analyzed. Genome-to-Genome Distance Calculator (GGDC) which uses the Genome Blast Distance Phylogeny (GBDP) technique to calculate digital DDH values.Phylogenetic analysis via Genome-to-Genome distance, Average Nucleotide Identity, and Amino Acid Identity calculation revealed that all strains belonged to the genusPantoea. However, strain 33.1 had a lower value than the threshold for the same species delineation. Bacterial Pan Genome Analysis (BPGA) Pipeline and MinPath analysis revealed genetic traits associated with environmental resilience, such as oxidative stress, UV radiation, temperature extremes, and metabolism of distinct host-specific carbohydrates. Protein-protein interactome analysis illustrated osmotic stress proteins closely linked with core proteins, while heavy metal tolerance, nitrogen metabolism, and Type III and VI secretion systems proteins generally associated with pathogenicity formed a separate network, indicating strain-specific characteristics. These findings shed new light on the intricate genetic architecture ofPantoea agglomerans, revealing its adaptability to inhabit diverse niches and thrive in varied environments.

Dietary carbohydrate sources differently prime the microbial ecosystem but not the epithelial gene expression profile along the complete gut of young calves

BackgroundRecent data indicated similar growth performance of young calves fed solely high-quality hay instead of a starter diet based on starchy ingredients. Yet, providing exclusively such distinct carbohydrate sources during early life might specifically prime the microbiota and gene expression along the gut of young calves, which remains to be explored. We investigated the effects of starter diets differing in carbohydrate composition, that is medium- or high-quality hay and without or with 70% concentrate supplementation (on fresh matter basis), across the gastrointestinal tract (GIT) of weaned Holstein calves (100 ± 4 days of age) using 16 S rRNA gene sequencing and analyses of short-chain fatty acids and host epithelial gene expressions.ResultsThe concentrate supplementation drastically decreased microbial diversity throughout the gut, which was also true to a much lesser extent for high-quality hay when compared to medium-quality hay in the foregut. Similarly, the factor concentrate strongly shaped the diet-associated common core microbiota, which was substantially more uniform along the gut with concentrate supplementation. The fermentation profile shifted towards less acetate but more propionate with concentrate supplementation in almost all gut sections, corresponding with higher abundances of starch-utilizing bacteria, while major fibrolytic clusters declined. Noteworthy, the n-butyrate proportion decreased in the rumen and increased in the colon with concentrate, showing an opposite, gut site-dependent effect. Both dietary factors modestly influenced the host epithelial gene expression.ConclusionsConcentrate supplementation clearly primed the microbial ecosystem on a starch-targeted fermentation with characteristic genera occupying this niche along the entire GIT of calves, whereas the microbial differentiation due to hay quality was less distinct. Overall, changes in the microbial ecosystem were only marginally reflected in the targeted transcriptional profile of the host epithelium.

Analysis of Aureobasidium pullulans LB83 secretome reveals distinct carbohydrate active enzymes for biomass saccharification

Aureobasidium pullulans LB83 is a versatile biocatalyst that produces a plethora of bioactive products thriving on a variety of feedstocks under the varying culture conditions. In our last study using this microorganism, we found cellulase activity (FPase, 2.27 U/ml; CMCase, 7.42 U/ml) and other plant cell wall degrading enzyme activities grown on sugarcane bagasse and soybean meal as carbon source and nitrogen, respectively. In the present study, we provide insights on the secretome analysis of this enzymatic cocktail. The secretome analysis of A. pullulans LB83 by Liquid Chromatography coupled to Mass Spectroscopy (LC-MS/MS) revealed 38 classes of Carbohydrate Active enZymes (CAZymes) of a total of 464 identified proteins. These CAZymes consisted of 21 glycoside hydrolases (55.26%), 12 glycoside hydrolases harboring carbohydrate-binding module (31.58%), 4 carbohydrate esterases (10.53%) and one glycosyl transferase (2.63%). To the best of our knowledge, this is the first report on the secretome analysis of A. pullulans LB83.

Comparative metabolomics analysis reveals dynamic changes in carbohydrate profiles of corms during the "relay growth" of konjac (Amorphophallus muelleri).

The type and content of carbohydrates in konjac corms are an essential factors in determining the quality of konjac; however, the pattern of carbohydrate changes and the mechanism regulating the development of mother and daughter corms in the "relay growth" process of Amorphophallus muelleri remain unclear. This study aimed to investigate changes in corm carbohydrates during the growth cycle of A. muelleri and to compare the carbohydrate composition and the expression of related genes between mother and daughter corms. Integrated metabolome and RNA-seq analyses identified 37 differential metabolites as well as 8074 genes that were differentially expressed between mother and daughter corms, the majority of which were involved in starch and sucrose metabolism. More than 80% of the differential metabolites, including sucrose and starch, tended to accumulate in the mother corms; however, konjac glucomannan (KGM), as one of the most important carbohydrates and its major component of the corm, accumulated in higher amounts in the daughter corms. In addition, the expression of invertase and alpha-amylase that promote the breakdown of sucrose and starch was 351.78- and 15.63-fold higher, respectively, in the daughter corm, whereas that of the starch synthesis gene AkWAXY was only 0.096 times as high as in the mother corms. Furthermore, the level of cellulose synthase-like protein G, which promotes KGM synthesis, was 3.85 times higher in daughter corms compared to mother corms. Thus, we inferred that the daughter and mother corms had two distinct carbohydrate utilization strategies. This study provides insights into temporal changes in carbohydrates during the growth cycle of A. muelleri.

Charting the solid-state NMR signals of polysaccharides: A database-driven roadmap.

Solid-state nuclear magnetic resonance (ssNMR) measurements of intact cell walls and cellular samples often generate spectra that are difficult to interpret due to the presence of many coexisting glycans and the structural polymorphism observed in native conditions. To overcome this analytical challenge, we present a statistical approach for analyzing carbohydrate signals using high-resolution ssNMR data indexed in a carbohydrate database. We generate simulated spectra to demonstrate the chemical shift dispersion and compare this with experimental data to facilitate the identification of important fungal and plant polysaccharides, such as chitin and glucans in fungi and cellulose, hemicellulose, and pectic polymers in plants. We also demonstrate that chemically distinct carbohydrates from different organisms may produce almost identical signals, highlighting the need for high-resolution spectra and validation of resonance assignments. Our study provides a means to differentiate the characteristic signals of major carbohydrates and allows us to summarize currently undetected polysaccharides in plants and fungi, which may inspire future investigations.

Thermoresponsive hydrogels with sulfated polysaccharide-derived copolymers: the effect of carbohydrate backbones on the responsive and mechanical properties

Thermoresponsive hydrogels based on ionic cellulose/chitosan are widely used various fields, such as smart windows and tissue engineering, while the effect of carbohydrate backbones of cellulose/chitosan on the thermal response and mechanical properties of hydrogels has received less attention so far. Herein, poly(2(dimethylamino)ethyl methacrylate) (PDMAEMA)-grafted cellulose sulfate (P-CS) and PDMAEMA-grafted chitosan sulfate (P-CHS) as research models are successfully synthesized through multi-step reactions. The P-CS and P-CHS polymers are further applied in crosslinked polyacrylamide networks, resulting in the P-CS and P-CHS hydrogels. Compared to P-CS hydrogels, P-CHS hydrogels could obviously block the transmission of visible light when the temperature is changed from 25 to 42 °C. In contrast to P-CHS hydrogels, the P-CS hydrogels change easily from soft and weak state to stiff and strong state according to their mechanical behaviors. These results indicate that different carbohydrate backbones of cellulose and chitosan should have caused distinct aggregation behaviors of corresponding P-CS and P-CHS hydrogels, which are accompanied by different light transmittance and mechanical properties.Graphical abstract Thermoresponsive hydrogels using PDMAEMA-grafted ionic cellulose sulfate (P-CS) and chitosan sulfate (P-CHS) are successfully prepared. Distinct carbohydrate backbone displayed different effects on the thermoresponsive and mechanical properties of hydrogels.

PREVALENCE OF BLOOD GROUPA2 AMONG GROUPAAND AB DONORS

The ABO blood group antigens are clinically signicant and their discovery by Landsteiner in 1900 paved way for the performance of safe blood transfusions. These antigens are characterized by their distinct carbohydrate structures attached to the glycoprotein or glycolipid membranes of red blood cells (RBCs). Their expression can also be detected on various human cell and tissue surfaces including sensory neurons, vascular endothelium and platelets. [1] Subgroups of the ABO antigens occur and are characterized by reduced quantities of the antigens on the RBCs and saliva of secretors. [2] Landsteiner & Levine subdivided blood group A into their principal subgroups, A1 and A2. The presence of Asubgroups is due to genetic variations in the coding region which leads to diminished amounts of A substance and higher amounts of H substance on red blood cells. There are weaker subgroups than A2 which do not frequently occur but when present; they show a characteristic decreased Aantigen sites on their RBC and a corresponding increased H antigen activity. [3] The difference between subgroups A1 and A2 is seen in their reactivity with the Dolichos biflorus lectin. The Dolichos lectin specically agglutinates A1 cells, leaving the A2 cells unagglutinated. The ABO antibodies occur naturally in the sera of individuals who do not have the corresponding antigens and can cause haemolysis in-vivo. They are mostly immunoglobulin M (IgM). These antibodies through complement activation can cause severe, life-threatening transfusion reactions due to incompatible ABO blood transfusions. Anti-A1 antibody appears as an atypical cold agglutinin in the sera of few people with group A2 or A2B who do not have the corresponding antigen.[4] One to eight percent of persons with blood group A2 and about 22-35% of persons with group A2B have serum anti-A1. These antibodies may cause discrepancies in ABO blood grouping which can further result in HTR.[5] Rare cases of haemolytic transfusion reaction due to anti-A1 have been reported.[4] It is estimated that about 80% of individuals with antigen A are A1 while the remaining 20% are A2. [5] Among Indians, the frequency of subgroup A2 among group A individuals is 6.58% whiles that of A2B among group AB is 8.99%.[6] Knowledge of the frequency and distribution of blood subgroup A2 will help to enhance blood compatibility testing, population genetic studies, investigation of transfusion reactions, studying disease associations and resolving some medico-legal issues.[7]

Abstract 1588: Using glyco-engineered cells with flexible expression of tumor-associated carbohydrates for the generation of highly tumor-specific antibodies

Abstract Introduction: Highly potent therapeutic approaches require clean targets. However, the majority of antibodies in clinical development or approved for cancer therapy address protein targets that are only over-expressed in cancer and yet often show significant expression in healthy organs. Besides protein expression, glycosylation is strongly altered in cancer, reflecting changes in tumor metabolism or genetic alterations. Mutated or mislocated glycosyltransferases, glycosidases, substrates and chaperones, give rise to tumor-associated, truncated O-glycans like Thomsen-Friedenreich (TF) or Thomsen novelle (Tn) which are expressed on proteins in different carcinomas, leukemias, lymphomas and their metastases. Due to the heterogeneous nature of glycan biosynthesis, variations of glycan-structure occur at a given site of a glycoprotein, making fine-tuning of antibodies against a specific glycoprotein challenging. Therefore, Glycotope developed a cell line based platform, able to express proteins carrying distinct tumor-related glycan-structures in order to generate highly tumor-specific protein/carbohydrate combined epitope binding antibodies, thus increasing tumor selectivity of protein targeting antibodies. Experimental procedures: The presence of tumor-associated carbohydrates in cancer tissues was demonstrated by immunohistochemistry analysis. A platform comprising different glyco-engineered cell lines capable to express proteins with distinct glycoforms was developed and fully characterized. The cells’ ability to express specific protein/carbohydrate combined epitopes (GlycoTargets) with distinct carbohydrates was shown by flow cytometry, ELISA and mass spectrometry experiments. The versatile use of the platform for i) recombinant expression of GlycoTargets for the use as immunogens, ii) screening tool in antibody discovery campaigns, iii) characterization of antibody lead candidates, was shown in ELISA and flow cytometry experiments. Results: Using our glyco-engineered cells, we showcase the potential of the platform as a tool for the generation of proteins with specific glycosylation and for screening of antibodies that bind to their target protein only in combination with a specific tumor-associated glycan structure. Conclusion: Our platform enables tailored immunization and screening approaches in order to generate antibodies against specific protein/carbohydrate combined epitopes. These antibodies bind their protein target only in presence of tumor-associated carbohydrates, thereby showing markedly reduced binding to the protein expressed in healthy tissues. This cell-based platform provides the basis for target validation, antigen production, immunization and screening for highly specific antibodies, opening the field for more effective therapeutic approaches. Citation Format: Patrik Kehler, Naomi Kast, Manon Weiske, Stephanie Gurka, Timo Lischke, Johanna Gellert, Antje Danielczyk. Using glyco-engineered cells with flexible expression of tumor-associated carbohydrates for the generation of highly tumor-specific antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1588.

Hybrid metagenome assemblies link carbohydrate structure with function in the human gut microbiome

Complex carbohydrates that escape small intestinal digestion, are broken down in the large intestine by enzymes encoded by the gut microbiome. This is a symbiotic relationship between microbes and host, resulting in metabolic products that influence host health and are exploited by other microbes. However, the role of carbohydrate structure in directing microbiota community composition and the succession of carbohydrate-degrading microbes, is not fully understood. In this study we evaluate species-level compositional variation within a single microbiome in response to six structurally distinct carbohydrates in a controlled model gut using hybrid metagenome assemblies. We identified 509 high-quality metagenome-assembled genomes (MAGs) belonging to ten bacterial classes and 28 bacterial families. Bacterial species identified as carrying genes encoding starch binding modules increased in abundance in response to starches. The use of hybrid metagenomics has allowed identification of several uncultured species with the functional potential to degrade starch substrates for future study.

Streptococcus oralis Employs Multiple Mechanisms of Salivary Mucin Binding That Differ Between Strains

Streptococcus oralis is an oral commensal and opportunistic pathogen that can enter the bloodstream and cause bacteremia and infective endocarditis. Here, we investigated the mechanisms of S. oralis binding to oral mucins using clinical isolates, isogenic mutants and glycoconjugates. S. oralis bound to both MUC5B and MUC7, with a higher level of binding to MUC7. Mass spectrometry identified 128 glycans on MUC5B, MUC7 and the salivary agglutinin (SAG). MUC7/SAG contained a higher relative abundance of Lewis type structures, including Lewis b/y, sialyl-Lewis a/x and α2,3-linked sialic acid, compared to MUC5B. S. oralis subsp. oralis binding to MUC5B and MUC7/SAG was inhibited by Lewis b and Lacto-N-tetraose glycoconjugates. In addition, S. oralis binding to MUC7/SAG was inhibited by sialyl Lewis x. Binding was not inhibited by Lacto-N-fucopentaose, H type 2 and Lewis x conjugates. These data suggest that three distinct carbohydrate binding specificities are involved in S. oralis subsp. oralis binding to oral mucins and that the mechanisms of binding MUC5B and MUC7 differ. Efficient binding of S. oralis subsp. oralis to MUC5B and MUC7 required the gene encoding sortase A, suggesting that the adhesin(s) are LPXTG-containing surface protein(s). Further investigation demonstrated that one of these adhesins is the sialic acid binding protein AsaA.

Fungi hijack a ubiquitous plant apoplastic endoglucanase to release a ROS scavenging β-glucan decasaccharide to subvert immune responses.

Plant pathogenic and beneficial fungi have evolved several strategies to evade immunity and cope with host-derived hydrolytic enzymes and oxidative stress in the apoplast, the extracellular space of plant tissues. Fungal hyphae are surrounded by an inner insoluble cell wall layer and an outer soluble extracellular polysaccharide (EPS) matrix. Here, we show by proteomics and glycomics that these two layers have distinct protein and carbohydrate signatures, and hence likely have different biological functions. The barley (Hordeum vulgare) β-1,3-endoglucanase HvBGLUII, which belongs to the widely distributed apoplastic glycoside hydrolase 17 family (GH17), releases a conserved β-1,3;1,6-glucan decasaccharide (β-GD) from the EPS matrices of fungi with different lifestyles and taxonomic positions. This low molecular weight β-GD does not activate plant immunity, is resilient to further enzymatic hydrolysis by β-1,3-endoglucanases due to the presence of three β-1,6-linked glucose branches and can scavenge reactive oxygen species. Exogenous application of β-GD leads to enhanced fungal colonization in barley, confirming its role in the fungal counter-defensive strategy to subvert host immunity. Our data highlight the hitherto undescribed capacity of this often-overlooked EPS matrix from plant-associated fungi to act as an outer protective barrier important for fungal accommodation within the hostile environment at the apoplastic plant–microbe interface.

Cerebral Organoids Maintain the Expression of Neural Stem Cell-Associated Glycoepitopes and Extracellular Matrix

During development, the nervous system with its highly specialized cell types forms from a pool of relatively uniform stem cells. This orchestrated process requires tight regulation. The extracellular matrix (ECM) is a complex network rich in signaling molecules, and therefore, of interest in this context. Distinct carbohydrate structures, bound to ECM molecules like Tenascin C (TNC), are associated with neural stem/progenitor cells. We have analyzed the expression patterns of the LewisX (LeX) trisaccharide motif and of the sulfation-dependent DSD-1 chondroitin sulfate glycosaminoglycan epitope in human cerebral organoids, a 3D model for early central nervous system (CNS) development, immunohistochemically. In early organoids we observed distinct expression patterns of the glycoepitopes, associated with rosette-like structures that resemble the neural tube in vitro: Terminal LeX motifs, recognized by the monoclonal antibody (mAb) 487LeX, were enriched in the lumen and at the outer border of neural rosettes. In contrast, internal LeX motif repeats detected with mAb 5750LeX were concentrated near the lumen. The DSD-1 epitope, labeled with mAb 473HD, was detectable at rosette borders and in adjacent cells. The epitope expression was maintained in older organoids but appeared more diffuse. The differential glycoepitope expression suggests a specific function in the developing human CNS.

Distinctive carbohydrate profiles of black ginseng revealed by IM-MS combined with PMP labeling and multivariate data analysis

Despite the widely recognized importance of ginseng carbohydrates, their structural analysis is still challenging due to structural complexity. This study presents the first ion mobility-mass spectrometry (IM-MS) combined with 1-phenyl-3-methyl-5-pyrazolone (PMP) labeling and multivariate data analysis for profiling carbohydrates in the seven ginseng products. 11 carbohydrates were tentatively annotated, including 5 first found in ginseng, and three of them were solely detected in black ginseng (BG) samples, speculated as monosaccharides bearing various groups based on MS2 analysis. Furthermore, 3D profiles of carbohydrates in IM-MS of the samples showed good discrimination between the varieties of ginseng which were classified into two groups utilizing carbohydrate contents by PLS-DA. The big difference between BG and the others may be ascribed to the repeated heating and steaming process for preparation of BG products. Our findings may provide insights into the differences in bioactivity of different ginseng varieties for future research and show a valuable methodology for discovering unknown carbohydrates.

Comparison of steaming and boiling of root vegetables for enhancing carbohydrate content and sensory profile

Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke ( Helianthus tuberosus L.), parsnip ( Pastinaca sativa ), and beetroot ( Beta vulgaris ). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties. • Steaming and boiling increase dietary fibre in Jerusalem artichoke and parsnip. • Steamed vegetables are softer, have larger cell shrinkage and loss of cell adhesion. • Textural changes in processed beetroot are not related to total carbohydrates. • Flavour and in-mouth sensory attributes scores are higher for steamed vegetables. • Results give insights to use root vegetable pieces in processed foods.

Inoculation of tomato (Solanum lycopersicum) roots with growth promoting Pseudomonas strains induces distinct local and systemic metabolic biosignatures

The genus Pseudomonas harbours numerous strains that positively affect plant growth and defence through diverse mechanisms such as nutrient solubilisation and production of phytohormones or secondary metabolites. The aim of this study was to compare the impact of six plant-beneficial Pseudomonas strains on tomato (Solanum lycopersicum) growth and holobiont physiology. The physiological impact was determined by profiling the activities of key enzymes in the central carbohydrate and antioxidant metabolism. Root inoculation of tomato seedlings with Pseudomonas strains in a greenhouse experiment induced plant growth, measured as biomass and plant height promotion. The bacterial strains also increased leaf chlorophyll content and caused distinct carbohydrate and antioxidative metabolism enzyme activity profiles in leaf and root tissue respectively. For the carbohydrate metabolism, the activities of several key enzymes involved in assimilate partitioning from source to sink and processing of the transport sugar sucrose for catabolism and anabolism were stimulated. For the antioxidative metabolism, both enzymes involved in detoxification of reactive oxygen species and redox buffering were increased. These increased enzyme activities in response to bacterial inoculation could contribute to balancing plant growth and defence. Importantly, positive correlations between plant growth parameters and distinct enzyme activities suggest that host plant biosignatures may be predicting bacteria with plant growth-promoting potential. These findings offer new perspectives for integrating physiological fingerprinting in the screening of microbes during early developmental stages of the host plant. In addition, determining plant metabolic biosignatures could be a rapid tool for predicting the potential and improvement of stress resiliency.

Exploration of Galectin Ligands Displayed on Gram-Negative Respiratory Bacterial Pathogens with Different Cell Surface Architectures.

Galectins bind various pathogens through recognition of distinct carbohydrate structures. In this work, we examined the binding of four human galectins to the Gram-negative bacteria Klebsiella pneumoniae (Kpn) and non-typeable Haemophilus influenzae (NTHi), which display different surface glycans. In particular, Kpn cells are covered by a polysaccharide capsule and display an O-chain-containing lipopolysaccharide (LPS), whereas NTHi is not capsulated and its LPS, termed lipooligosacccharide (LOS), does not contain O-chain. Binding assays to microarray-printed bacteria revealed that galectins-3, -4, and -8, but not galectin-1, bind to Kpn and NTHi cells, and confocal microscopy attested binding to bacterial cells in suspension. The three galectins bound to array-printed Kpn LPS. Moreover, analysis of galectin binding to mutant Kpn cells evidenced that the O-chain is the docking point for galectins on wild type Kpn. Galectins-3, -4, and -8 also bound the NTHi LOS. Microarray-assisted comparison of the binding to full-length and truncated LOSs, as well as to wild type and mutant cells, supported LOS involvement in galectin binding to NTHi. However, deletion of the entire LOS oligosaccharide chain actually increased binding to NTHi cells, indicating the availability of other ligands on the bacterial surface, as similarly inferred for Kpn cells devoid of both O-chain and capsule. Altogether, the results illustrate galectins’ versatility for recognizing different bacterial structures, and point out the occurrence of so far overlooked galectin ligands on bacterial surfaces.