Effects of Dietary Agavin on the Gut Microbiota of the Nile Tilapia (Oreochromis niloticus) Reared at High Densities.

High-density stress can lead to dysbiotic microbiota, affecting the organism's metabolic, and protective functions. Agavin is a fructan with prebiotic properties that regulate the gut microbiota by promoting the growth of beneficial bacteria. This study evaluated the effect of agavin on the gut microbiota using Next-Generation Sequencing (NGS) and its correlation with the growth parameters. Four groups of fish were fed different diets: a control diet (negative and positive control), without agavin supplementation, and two experimental diets supplemented with agavin at 20 g kg-1 and 40 g kg-1. Nile tilapias (1.04 g ± 0.01 g) were fed for 110 days. After 90 days of feeding, fish were subjected to high-density stress (63 kg m-3) for 20 days, except for the negative control. NGS detected 1579 different operational taxonomic units in the samples. In the correlation analysis of growth parameters, the families Vibrionaceae and Methyloligillaceae showed a positive correlation with fish growth parameters, these results may serve to know the relation of agavin and microbiota on the growth performance, as well as the metabolic activities of families in tilapia. Furthermore, high-density stress and agavin supplementation modify the gut microbiota in tilapia. At a low-density, supplementation with 20 g kg-1 agavin promoted the growth of the potentially beneficial families Sphingomonadaceae, Oxalobacteriaceae, and Chitinophagaceae; at high densities, reduced the abundance of pathogenic families (Vibrionaceae and Aeromonadaceae). These results suggest that, under stress conditions, agavin can stimulate the growth of potentially beneficial bacteria and reduce the growth of potentially pathogenic bacteria, suggesting its potential use as a prebiotic in aquaculture.

The effect of fiber supplementation with agave fructans or psyllium plantago in symptoms of constipation and its relation with whole and regional transit time and pH.

BACKGROUND: Supplementation with the Agave tequilana Weber blue variety fructans is a feasible treatment option for functional constipation (FC). However, its effects on colonic function have not yet been studied. This study assessed whole gut transit time (WGTT) and regional transit time using a wireless motility capsule (WMC) before and after supplementation with different fiber treatments in patients with FC. METHODS: A secondary analysis was performed on data collected from a randomized, double-blind clinical trial comparing agave fructans with psyllium plantago. WGTT, regional transit time, contractility, and pH were measured using WMC before and after fiber supplementation. Comparisons were performed using nonparametric tests. KEY RESULTS: Twenty patients with FC were evaluated, with a median age of 39 (25-54 years), and 18 (90%) were women. Five patients were included in each intervention group. There were no changes in WGTT or regional transit times between the groups (p > 0.05). Similarly, there were no differences in the changes experienced by regional or general contractility among the groups (p > 0.05). The cecal pH profile did not differ between the groups before and after fiber supplementation (p > 0.05). The percentages of clinical responses and consistency of bowel movements between the groups were similar. CONCLUSIONS & INFERENCES: FC presents a clinical response to a fiber challenge, regardless of the administered intervention. However, this response was not associated with improvement in contractility or regional transit time. We speculate that there are other mechanisms by which fiber consumption may improve FC.

Exploring the role of levan in plant immunity to pathogens: A review.

This review article delves into the intricate relationship between levan, a versatile polysaccharide, and its role in enhancing plant resistance against pathogens. By exploring the potential applications of levan in agriculture and biotechnology, such as crop protection, stress tolerance enhancement, and biotechnological innovations, significant advancements in sustainable agriculture are uncovered. Despite challenges in optimizing application methods and addressing regulatory hurdles, understanding the mechanisms of levan-mediated plant immunity offers promising avenues for future research. This review underscores the implications of utilizing levan to develop eco-friendly solutions, reduce reliance on chemical pesticides, and promote sustainable agricultural practices. Ultimately, by unraveling the pivotal role of levan in plant-pathogen interactions, this review sets the stage for transformative innovations in agriculture and highlights the path towards a more resilient and sustainable agricultural future.

A fructan-type garlic polysaccharide upregulates immune responses in macrophage cells and in immunosuppressive mice.

The anti-inflammatory effects of plant polysaccharides are well known. However, the stimulatory effects of polysaccharides under immunosuppressive conditions and their link with the polysaccharide structure is underexplored. In this work, the immune modulatory effects of a garlic polysaccharide (GP) are investigated via in vitro and vivo methods. It is observed that GP enhance the immune response of macrophages (RAW264.7) as indicated by the elevated levels of nitric oxide, TNF-α and IL-6. The observation that GP are able to stimulate the immune response in vitro was then explored with the use of an immunosuppressed mouse model. Surprisingly, GP exhibited dose-dependent up-regulatory impacts on the cyclophosphamide (CTX) suppressed levels of cytokines such as IFN-γ and IL-6 and immunoglobulins (e.g. IgA and IgG). The GP intervention reversed histopathological damage to the small intestine and spleen and increased fecal short-chain fatty acid levels. Moreover, GP modulates the gut microbiota dysbiosis by increasing the abundance of immunogenic bacteria such as g__norank_f__Erysipelotrichaceae, while inhibiting the over-abundance of g_Bacteroides. Functional predictions indicated that gut biomarkers of GP possessed the functions of glycoside hydrolase family 32 (GH32) and ß-fructofuranosidase. It is concluded that GP is a promising immunostimulant for immune-compromised individuals.

Effects of fructan and gluten on gut microbiota in individuals with self-reported non-celiac gluten/wheat sensitivity-a randomised controlled crossover trial.

BACKGROUND: Individuals with non-celiac gluten/wheat sensitivity (NCGWS) experience improvement in gastrointestinal symptoms following a gluten-free diet. Although previous results have indicated that fructo-oligosaccharides (FOS), a type of short-chain fructans, were more likely to induce symptoms than gluten in self-reported NCGWS patients, the underlying mechanisms are unresolved. METHODS: Our main objective was therefore to investigate whether FOS-fructans and gluten affect the composition and diversity of the faecal microbiota (16S rRNA gene sequencing), faecal metabolites of microbial fermentation (short-chain fatty acids [SCFA]; gas chromatography with flame ionization detector), and a faecal biomarker of gut inflammation (neutrophil gelatinase-associated lipocalin, also known as lipocalin 2, NGAL/LCN2; ELISA). In the randomised double-blind placebo-controlled crossover study, 59 participants with self-reported NCGWS underwent three different 7-day diet challenges with gluten (5.7 g/day), FOS-fructans (2.1 g/day), and placebo separately (three periods, six challenge sequences). RESULTS: The relative abundances of certain bacterial taxa were affected differently by the diet challenges. After the FOS-fructan challenge, Fusicatenibacter increased, while Eubacterium (E.) coprostanoligenes group, Anaerotruncus, and unknown Ruminococcaceae genera decreased. The gluten challenge was primarily characterized by increased abundance of Eubacterium xylanophilum group. However, no differences were found for bacterial diversity (α-diversity), overall bacterial community structure (ß-diversity), faecal metabolites (SCFA), or NGAL/LCN2. Furthermore, gastrointestinal symptoms in response to FOS-fructans were generally not linked to substantial shifts in the gut bacterial community. However, the reduction in E. coprostanoligenes group following the FOS-fructan challenge was associated with increased gastrointestinal pain. Finally, correlation analysis revealed that changes in gastrointestinal symptoms following the FOS-fructan and gluten challenges were linked to varying bacterial abundances at baseline. CONCLUSIONS: In conclusion, while FOS-fructans induced more gastrointestinal symptoms than gluten in the NCGWS patients, we did not find that substantial shifts in the composition nor function of the faecal microbiota could explain these differences in the current study. However, our results indicate that individual variations in baseline bacterial composition/function may influence the gastrointestinal symptom response to both FOS-fructans and gluten. Additionally, the change in E. coprostanoligenes group, which was associated with increased symptoms, implies that attention should be given to these bacteria in future trials investigating the impact of dietary treatments on gastrointestinal symptoms. TRIAL REGISTRATION: Clinicaltrials.gov as NCT02464150.

Structure-anti-inflammatory activity relationship of garlic fructans in mice with dextran sulfate sodium-induced colitis: Impact of chain length.

The present study identified the protective effects of garlic oligo/poly-saccharides of different chain lengths against dextran sulfate sodium (DSS)-induced colitis in mice and elucidated the structure-function relationships. The results showed that oral intake of garlic oligo/poly-saccharides decreased disease activity index, reduced colon shortening and spleen enlargement, and ameliorated pathological damage in the mouse colon. The dysregulation of colonic pro/anti-inflammatory cytokines was significantly alleviated, accompanied by up-regulated antioxidant enzymes, blocked TLR4-MyD88-NF-κB signaling pathway, enhanced intestinal barrier integrity, and restored SCFA production. Garlic oligo/poly-saccharides also reversed gut microbiota dysbiosis in colitic mice by expanding beneficial bacteria and suppressing the growth of harmful bacteria. High-molecular-weight polysaccharides exhibited stronger alleviating effects on DSS-induced colitic symptoms in mice than low-molecular-weight oligo/poly-saccharides did, probably due to their greater ability to be fermented in the colon. Taken together, this study demonstrated the anti-inflammatory effects of garlic oligo/poly-saccharides and revealed that high-molecular-weight polysaccharide fractions were more effective in alleviating DSS-induced colitis.

Exploring Levansucrase Operon Regulating Levan-Type Fructooligosaccharides (L-FOSs) Production in Priestia koreensis HL12.

Levan biopolymer and levan-type fructooligosaccharides (L-FOSs) are ß-2,6-linked fructans that have been used as non-digestible dietary fiber and prebiotic oligosaccharides in food and cosmeceutical applications. In this study, we explore the operon responsible for levan and L-FOSs production in Priestia koreensis HL12. Presented is the first genomic perspective on sucrose utilization and the levan biosynthesis pathway in this bacterium. Regarding sequence annotation, the putative levansucrase operon responsible for ß-2,6-linked fructan was identified in the genome of strain HL12, and comprises sacB levansucrase gene belonging to GH68, located adjacent to levB endo-levanase gene, which belongs to GH32. Importantly, sugars related with the levan biosynthesis pathway are proposed to be transported via 3 types of transportation systems, including multiple ABCSugar and glucose/H+ transporters, as well as glucose- and fructose-specific PTS systems. Based on product profile analysis, the HL12 strain exhibited high efficiency in levan production from high sucrose concentration (300 g/l), achieving the highest yield of 127 g/l (equivalent to 55% conversion based on sucrose consumption), together with short-chain L-FOSs (DP3-5) and long-chain L-FOSs with respective size larger than DP6 after 48 h incubation. These findings highlight the potential of P. koreensis HL12 as a whole-cell biocatalyst for producing levan and L-FOSs, and underscore its novelty in converting sugars into high-value-added products for diverse commercial and industrial applications.

Elucidation of the mechanism underlying the sequential catalysis of inulin by fructotransferase.

Glycoside hydrolase family 91 (GH91) inulin fructotransferase (IFTases) enables biotransformation of fructans into sugar substitutes for dietary intervention in metabolic syndrome. However, the catalytic mechanism underlying the sequential biodegradation of inulin remains unelusive during the biotranformation of fructans. Herein we present the crystal structures of IFTase from Arthrobacter aurescens SK 8.001 in apo form and in complexes with kestose, nystose, or fructosyl nystose, respectively. Two kinds of conserved noncatalytic binding regions are first identified for IFTase-inulin interactions. The conserved interactions of substrates were revealed in the catalytic center that only contained a catalytic residue E205. A switching scaffold was comprised of D194 and Q217 in the catalytic channel, which served as the catalytic transition stabilizer through side chain displacement in the cycling of substrate sliding in/out the catalytic pocket. Such features in GH91 contribute to the catalytic model for consecutive cutting of substrate chain as well as product release in IFTase, and thus might be extended to other exo-active enzymes with an enclosed bottom of catalytic pocket. The study expands the current general catalytic principle in enzyme-substrate complexes and shed light on the rational design of IFTase for fructan biotransformation.

Chasing the chill: Unveiling the dynamic flavors and textures of ice cream formulations.

In this study, nine commercial ice creams and four prototypes were assessed. For the sensory analysis, quantitative descriptive analysis (QDA), and temporal dominance of sensations (TDS) methodology were used. According to the QDA results, full-composition ice cream showed significantly higher differences (p < .05) in terms such as vanilla and sweet flavors, brightness, creamy texture and appearance, and viscosity, exhibiting longer melting times. Functional ice creams showed significantly higher differences (p < .05) in terms like viscosity, creamy texture, and appearance. On the other hand, agave fructans in prototype ice creams were found to be able to reduce fat, but not fat and sugar simultaneously, showing a significant decrease (p < .05) in terms such as hardness, crystallized texture, gummy texture, and porosity. Based on the PCA results, the analysis accounted for 75.28% of data variability. Full-composition ice creams and one functional ice cream were related to terms such as viscosity, fatty sensation, creamy texture and appearance, dense, gummy, among others. The rest of the commercial ice creams were related to vanilla and caramel flavor and smell, artificial aftertaste, aerated, porosity, among others. Prototype ice creams were related to hard texture, salty and milk flavor, and crystallized texture. Based on the results of the TDS method, all formulations were found to be significantly dominant (5%) in terms such as vanilla flavor and sweet flavor at the beginning of the test. Formulations containing butyric fat and/or vegetable fat, or agave fructans were significantly dominant (5%) in fatty sensation.

Sucrose-Phosphate Synthase and Sucrose Synthase contribute to refoliation in ryegrass, a grassland fructan-accumulating species.

The perennity of grassland species such as Lolium perenne greatly depends on their ability to regrow after cutting or grazing. Refoliation largely relies on the mobilization of fructans in the remaining tissues and on the associated sucrose synthesis and transport towards the basal leaf meristems. However, nothing is known yet about the sucrose synthesis pathway. Sucrose Phosphate Synthase (SPS) and Sucrose Synthase (SuS) activities, together with their transcripts, were monitored during the first hours after defoliation along the leaf axis of mature leaf sheaths and elongating leaf bases (ELB) where the leaf meristems are located. In leaf sheaths, which undergo a sink-source transition, fructan and sucrose contents declined while SPS and SuS activities increased, along with the expression of LpSPSA, LpSPSD.2, LpSuS1, LpSuS2, and LpSuS4. In ELB, which continue to act as a strong carbon sink, SPS and SuS activities increased to varying degrees while the expression of all the LpSPS and LpSuS genes decreased after defoliation. SPS and SuS both contribute to refoliation but are regulated differently depending on the source or sink status of the tissues. Together with fructan metabolism, they represent key determinants of ryegrass perennity and, more generally, of grassland sustainability.

Innovative strategies in yacon drying: Ethanol pretreatment and intermittent microwave drying.

The yacon roots are rich in fructooligosaccharides (FOS) and highly perishable. Drying is crucial for food quality and extending shelf life. However, preserving thermosensitive compounds, such as FOS, poses a challenge in conventional drying methods. In this regard, microwave drying and ethanol pretreatment (ET) have emerged as promising solutions for maintaining nutrients and reducing drying time (DT). The objective of this study was to assess how ET and sample temperature affect quality and process parameters during intermittent microwave drying of yacon. Drying at 52°C treated with ethanol was the one that stood out for presenting the highest fructan retention (64.1%), low DT, lower energy consumption (EC) (364.00 ± 5.03 kWh kg water-1), higher retention of antioxidant capacity (73.9%) and total phenolic content (77.5%), and slight variation in color parameters. Therefore, microwave drying with a controlled temperature of yacon pretreated with ethanol effectively reduces DT and EC by maintaining quality parameters.

Agave Wilt Susceptibility by Reduction of Free Hexoses in Root Tissue of Agave tequilana Weber var. azul Commercial Plants in the Fructan Accumulation Process.

Agave tequilana stems store fructan polymers, the main carbon source for tequila production. This crop takes six or more years for industrial maturity. In conducive conditions, agave wilt disease increases the incidence of dead plants after the fourth year. Plant susceptibility induced for limited photosynthates for defense is recognized in many crops and is known as "sink-induced loss of resistance". To establish whether A. tequilana is more prone to agave wilt as it ages, because the reduction of water-soluble carbohydrates in roots, as a consequence of greater assembly of highly polymerized fructans, were quantified roots sucrose, fructose, and glucose, as well as fructans in stems of agave plants of different ages. The damage induced by inoculation with Fusarium solani or F. oxysporum in the roots or xylem bundles, respectively, was recorded. As the agave plant accumulated fructans in the stem as the main sink, the amount of these hexoses diminished in the roots of older plants, and root rot severity increased when plants were inoculated with F. solani, as evidence of more susceptibility. This knowledge could help to structure disease management that reduces the dispersion of agave wilt, dead plants, and economic losses at the end of agave's long crop cycle.

Effects of dietary supplementation of cobiotic based on Agave fructans on growth performance, blood parameters, oxidative damage and immune status of broiler.

This study evaluated the effect of cobiotic (CO) composed of organic fructans powder of Agave tequilana and turmeric powder of Curcuma longa L. as an alternative of antibiotic growth promoters (AGPs) on growth performance, blood parameters, intestinal pH, oxidative stress, and cytokines serum levels of broiler chickens. A total of 135 one-day-old Ross 308 broilers distributed to five experimental groups, which included starter or finisher standard diets without AGPs (CON), CON + 0.25 COLI-ZIN g/kg feed (AGP), CON + 0.1 g Agave fructans/kg feed (AF), CON + 0.5 g turmeric powder/kg feed (TP) and CON + 0.1 g AF + 0.5 g TP /kg feed (CO), for 49 days. AF followed by TP, decreased feed intake, obtaining the best FCR. AGP increased the heterophil-lymphocyte ratio compared to other groups. CO significantly decreased the pH of the cecal content. AF increased IL-10 levels, while TP decreased it. AF decreased the IL-1ß levels. The present study showed that including a cobiotic based on AF and TP or components separately in a broilers diet improved growth performance, modified intestinal and cecum pH, and stimulated the immune system, which suggests CO as a safe alternative to AGP.

Weight, habitual fibre intake, and microbiome composition predict tolerance to fructan supplementation.

Fructans are commonly used as dietary fibre supplements for their ability to promote the growth of beneficial gut microbes. However, fructan consumption has been associated with various dosage-dependent side effects. We characterised side effects in an exploratory analysis of a randomised trial in healthy adults (n = 40) who consumed 18 g/day inulin or placebo. We found that individuals weighing more or habitually consuming higher fibre exhibited the best tolerance. Furthermore, we identified associations between gut microbiome composition and host tolerance. Specifically, higher levels of Christensenellaceae R-7 group were associated with gastrointestinal discomfort, and a machine-learning-based approach successfully predicted high levels of flatulence, with [Ruminococcus] torques group and (Oscillospiraceae) UCG-002 sp. identified as key predictive taxa. These data reveal trends that can help guide personalised recommendations for initial inulin dosage. Our results support prior ecological findings indicating that fibre supplementation has the greatest impact on individuals whose baseline fibre intake is lowest.

Thermostabilization of a fungal laccase by entrapment in enzymatically synthesized levan nanoparticles.

In this work, we present a comprehensive investigation of the entrapment of laccase, a biotechnologically relevant enzyme, into levan-based nanoparticles (LNPs). The entrapment of laccase was achieved concomitantly with the synthesis of LNP, catalyzed by a truncated version of a levansucrase from Leuconostoc mesenteroides. The study aimed to obtain a biocompatible nanomaterial, able to entrap functional laccase, and characterize its physicochemical, kinetic and thermal stability properties. The experimental findings demonstrated that a colloidal stable solution of spherically shaped LNP, with an average diameter of 68 nm, was obtained. An uniform particle size distribution was observed, according to the polydispersity index determined by DLS. When the LNPs synthesis was performed in the presence of laccase, biocatalytically active nanoparticles with a 1.25-fold larger diameter (85 nm) were obtained, and a maximum load of 243 µg laccase per g of nanoparticle was achieved. The catalytic efficiency was 972 and 103 (µM·min)-1, respectively, for free and entrapped laccase. A decrease in kcat values (from 7050 min-1 to 1823 min-1) and an increase in apparent Km (from 7.25 µM to 17.73 µM) was observed for entrapped laccase, compared to the free enzyme. The entrapped laccase exhibited improved thermal stability, retaining 40% activity after 1 h-incubation at 70°C, compared to complete inactivation of free laccase under the same conditions, thereby highlighting the potential of LNPs in preserving enzyme activity under elevated temperatures. The outcomes of this investigation significantly contribute to the field of nanobiotechnology by expanding the applications of laccase and presenting an innovative strategy for enhancing enzyme stability through the utilization of fructan-based nanoparticle entrapments.

Determination of prebiotic activity and probiotic encapsulation ability of inulin type fructans obtained from Inula helenium roots.

Inulin, a prebiotic utilized in the food and pharmaceutical industries, promotes the growth of beneficial bacteria in the colon, thereby enhancing human health. Although inulin is commercially produced from chicory and artichoke, Inula helenium roots offer a high potential for inulin production. The aim of this study is to investigate the prebiotic activity of inulin (inulin-P) from I. helenium roots on Lactobacillus rhamnosus, as well as its ability to produce synbiotic microcapsules and the effects on probiotic viability during freeze-drying, in vitro gastrointestinal (GI) digestion, and storage. First, the effect of inulin-P on L. rhamnosus viability and short-chain fatty acid (SCFA) production was compared to other commonly utilized prebiotics. The findings revealed that inulin-P remarkably promoted the growth and SCFA yield of L. rhamnosus for 48 h of fermentation and 28 days of storage. Then, L. rhamnosus was encapsulated with inulin-P and commercial inulin to compare its survival throughout storage and the GI tract. Inulin-P microcapsules outperformed in terms of viability during storage (7.98 log CFU/g after 30 days at 4°C). Furthermore, inulin-P microcapsules were heat-resistant and protected L. rhamnosus from GI conditions, resulting in a high survival rate (89.52%) following large intestine simulation, which is ideal for increasing customer benefits. Additionally, inulin-P microcapsules exhibited similar physical characteristics to commercial inulin. Consequently, this study revealed that inulin-P, which is easy to produce, low-cost, and has industrial application potential, could be used as a good carrier for the synbiotic encapsulation of L. rhamnosus. PRACTICAL APPLICATION: Inulin is a prebiotic that promotes the activity and growth of beneficial bacteria in the human gut. Although commercial inulin is currently produced from chicory root and artichoke, Inula helenium root is a potential raw material for inulin production. In this study, inulin was produced from I. helenium roots with a low-cost and easy production method, and it was determined that this inulin was an effective carrier in the synbiotic encapsulation of L. rhamnosus. This inulin exhibits superior prebiotic activity and encapsulation efficiency compared to commercial inulins like Orafti® GR and HPX and can be easily integrated into industrial production.

A graminan type fructan from Achyranthes bidentata prevents the kidney injury in diabetic mice by regulating gut microbiota.

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease, and few therapeutic options are available. The root of Achyranthis bidentatae (AB) is commonly used for DKD treatment in Traditional Chinese medicine. However, its mechanisms are still unclear. Here, a graminan type fructan ABPW1 with molecular weight of 3998 Da was purified from AB. It was composed of ß-1,2-linked Fruf, ß-2,6-linked-Fruf and ß-1,2,6-linked-Fruf backbone, and terminated with T-Glcp and 2-Fruf residues. ABPW1 protected against kidney injuries and intestinal barrier disruption in Streptozotocin (STZ)/High fat diet (HFD) mice. It could modulate gut microbiota composition, evidenced by a rise in the abundance of Bacteroide and decreases of Rikenella, Alistipes, Laedolimicola and Faecalibaculum. ABPW1 intervention promoted short chain fatty acids (SCFAs) production in STZ/HFD mice, especially propionate and isobutyric acid. Antibiotic treatment further demonstrated the key role of gut microbiota in the renal protective action of ABPW1. In addition, in vitro simulated digestion and fermentation together with in vivo fluorescent labeling studies demonstrated ABPW1 was indigestible in upper digestive tract but could reach the colon and be degraded into SCFAs by gut microbiota there. Overall, these data suggested ABPW1 has the potential application on DKD prevention.

Evaluation of the anti-atherosclerotic effect for Allium macrostemon Bge. Polysaccharides and structural characterization of its a newly active fructan.

Allium Macrostemon Bge. (AMB) is a well-known homology of herbal medicine and food that has been extensively used for thousands of years to alleviate cardiovascular diseases. It contains a significant amount of polysaccharides, yet limited research exists on whether these polysaccharides are responsible for its cardiovascular protective effects. In this study, the anti-atherosclerosis effect of the crude polysaccharides of AMB (AMBP) was evaluated using ApoE-/- mice fed a high-fat diet, along with ox-LDL-induced Thp-1 foam cells. Subsequently, guided by the inhibitory activity of foam cells formation, a major homogeneous polysaccharide named AMBP80-1a was isolated and purified, yielding 11.1 % from AMB. The molecular weight of AMBP80-1a was determined to be 10.01 kDa. AMBP80-1a was firstly characterized as an agavin-type fructan with main chains consisting of →1)-ß-d-Fruf-(2→ and →1,6)-ß-d-Fruf-(2→ linked to an internal glucose moiety, with →6)-ß-d-Fruf-(2→ and ß-d-Fruf-(2→ serving as side chains. Furthermore, the bio-activity results indicated that AMBP80-1a reduced lipid accumulation and cholesterol contents in ox-LDL-induced Thp-1 foam cell. These findings supported the role of AMBP in alleviating atherosclerosis in vivo/vitro. AMBP80-1a, as the predominant homogeneous polysaccharide in AMB, was expected to be developed as a functional agent to prevent atherosclerosis.

Potential of fructans as natural cryoprotectant agents in plant cryopreservation: concept validation on Arabidopsis thaliana L.

BACKGROUND: Today, synthetic chemicals are used in vitrification solutions for cryopreservation studies to mimic natural cryoprotectants that supply tolerance to organisms in nature against freezing stress. In the case of plants, PVS2, containing glycerol, dimethyl sulfoxide (Me2SO), ethylene glycol and sucrose, is considered as the golden standard for successful cryopreservation. However, Me2SO can generally cause toxicity to certain plant cells, adversely affecting viability after freezing and/or thawing. Hence, the replacement (or substantial reduction) of Me2SO by cheap, non-toxic and natural cryoprotectants became a matter of high priority to vitrification solutions or reducing their content gained escalating importance for the cryopreservation of plants. Fructans, sucrose derivatives mainly consisting of fructose residues, are candidate cryoprotectants. OBJECTIVE: Inspired by their protective role in nature, we here explored, for the first time, the potential of an array of 8 structurally different fructans as cryoprotectants in plant cryopreservation. MATERIALS AND METHODS: Arabidopsis thaliana L. seedlings were used as a model system with a one-step vitrification method. PVS2 solutions with different Me2SO and fructan contents were evaluated. RESULTS: It was found that branched low DP graminan, extracted from milky stage wheat kernels, led to the highest recovery (85%) among tested fructans with 12.5% Me2SO after cryopreservation, which was remarkably close to the viability (90%) observed with the original PVS2 containing 15% Me2SO. Moreover, its protective efficacy could be further optimized by addition of vitamin C acting as an antioxidant. CONCLUSION: Such novel formulations offer great perspectives for cryopreservation of various crop species. Doi.org/10.54680/fr24410110512.

Endo- and exo-levanases from Bacillus subtilis HM7: Catalytic components, synergistic cooperation, and application in fructooligosaccharide synthesis.

Levan-type fructooligosaccharides (LFOS) exhibit significant biological activities and selectively promote the growth of certain beneficial bacteria. Levanase is an important enzyme for LFOS production. In this study, two isoforms of levanases, exo- and endo-type depolymerizing enzymes, from Bacillus subtilis HM7 isolated from Dynastes hercules larvae excrement were cloned, expressed, and characterized. The synergistic effect on the levan hydrolysis and kinetic properties of both isoforms were evaluated, indicating their cooperation in levan metabolism, where the endo-levanase catalyzes a rate-limiting step. In addition, homology models and molecular dynamics simulations revealed the key amino residues of the enzymes for levan binding and catalysis. It was found that both isoforms possessed distinct binding residues in the active sites, suggesting the importance of the specificity of the enzymes. Finally, we demonstrated the potential of endo-type levanase in LFOS synthesis using a one-pot reaction with levansucrase. Overall, this study fills the knowledge gap in understanding levanase's mechanism, making an important contribution to the fields of food science and biotechnology.