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Solventogenic Clostridium species can efficiently produce n -butanol and other valuable chemicals via acetone–butanol–ethanol (ABE) fermentation from plant-based feedstocks. For economic and ecological sustainability, cheap and abundant substrates such as lignocellulosic and hemicellulosic residues from agricultural or forestry side streams are preferable. Cereal brans, rich in hemicellulose, represent a promising substrate. However, for direct fermentation of this material, only low product titers are reported. In this study, we characterized the utilization of arabinoxylan, the main polysaccharide component of cereal bran, by the industrial ABE producer Clostridium saccharobutylicum DSM 13864 T and report inefficient degradation of the substrate. Supplementation with hemicellulolytic enzyme mixtures derived from the thermophilic organism Thermoclostridium stercorarium subsp. stercorarium DSM 8532 T significantly enhanced substrate utilization. The best improvement was achieved by the addition of the arabinofuranosidase Axh43A, which reduced the residual sugar content in the fermentation broth from 48.2 to 17.8%. Analysis of the remaining oligosaccharides after growth on arabinoxylan showed that C. saccharobutylicum cannot remove O -2 and O -3 α-L-arabinofuranosyl groups from double-substituted xyloses, creating a key bottleneck in arabinoxylan degradation that is overcome by Axh43A addition. Plasmid-based expression of Axh43A in C. saccharobutylicum DSM 13864 T replicated the enzymatic supplementation effects, confirming the enzyme’s role in overcoming this limitation. This underscores the potential of genetic engineering to enhance the valorization of lignocellulosic biomass in biotechnological fermentation processes. Key Points C. saccharobutylicum DSM 13864 T insufficiently utilizes cereal arabinoxylan. Inability to cleave double-arabinosylated xylose moieties limits degradation. Heterologous expression of Axh43A strongly increases arabinoxylan utilization. Graphical Abstract

The gut microbiota, crucial for human health, is significantly modulated by dietary components, such as AX and CA; however, their combined synergistic effects remain poorly understood. Using in vitro fermentation, we examined individual and combined impacts of AX and CA on microbiota composition, metabolic activity, and the functional characteristics of Bifidobacterium longum. AX treatment enhanced short-chain fatty acid production, enriched beneficial genera, suppressed pathogens. In contrast, CA elevated the relative abundance of Megasphaera and upregulated bile acid pathways, while inhibiting Enterococcus. The combined AX-CA treatment amplified these beneficial shifts and enhanced pathogen suppression. Transcriptomic analysis revealed that AX upregulated B. longum genes associated with carbohydrate/amino acid metabolism, whereas CA stimulated lipid metabolism but exhibited dose-dependent growth inhibition. Furthermore, AX promoted the microbial biotransformation of CA to dihydrocaffeic acid. These results demonstrated AX and CA function as complementary prebiotics with significant potential to optimize gut microbial ecology and health-related metabolic functions.

Arabinoxylan is a polysaccharide with film-forming properties, present in corn fiber, and a low-value by-product. The extract has a deep brown color, producing films of the same shade, which may not be appealing. This study addresses, for the first time, the adsorption of colored compounds present in an arabinoxylan extract using resin MN102. The resin successfully adsorbed the colored compounds from the arabinoxylan extract. After four consecutive adsorption/desorption cycles, the efficiency of the resin was similar, only decreasing from 63.3% to 52.9%. Langmuir and Freundlich models were fitted to the results of adsorption isotherm experiments, with the Freundlich model demonstrating the best fit to the experimental results. A fixed-bed column loaded with the resin was used for the removal of the colored compounds from the arabinoxylan extract, and the effect of the volumetric flow rate was investigated. The Yan and log-Gompertz models showed the best fit to the experimental breakthrough curves. This study systematically evaluated the adsorption conditions, providing a comprehensive analysis of the performance of the resin in the removal of the colored compounds. Additionally, the ability of the extract to maintain its film-forming properties after decolorization was evaluated, and some of the film’s key characteristics were evaluated, namely its color, solubility in water and mechanical properties.

Increasing dietary fibre (DF) intake is an important target to improve health. An attractive strategy for this is to increase DF in wheat which is derived principally from the endosperm cell wall polysaccharide arabinoxylan (AX). The water‐extractable form of this (WE‐AX) accounts for most soluble dietary fibre (SDF), which is believed to confer particular health benefits. A region of chromosome 6B in some wheat varieties confers high SDF and here we show that the cause is an allele encoding a peroxidase family protein with a single residue change (PER1‐v) associated with high WE‐AX, compared to the more common form (PER1). Both wheat lines carrying this natural PER1‐v variant and those with an induced knockout mutation of PER1 showed reduced dimerization of endosperm ferulate consistent with a mechanism of decreased cross‐linking in the cell wall that increases WE‐AX. Transiently expressed PER1_RFP fusion protein driven by the native promoter in wheat endosperm was shown to localise to cell walls, whereas PER1‐v_RFP did not. We therefore propose that PER1‐v lacks the capacity to dimerise AX ferulate in vivo due to mis‐localisation caused by the missense single‐nucleotide polymorphism (SNP) in the PER1‐v allele, so that the SNP acts as a perfect marker. This marker can be used to identify current wheat varieties with high WE‐AX to be used by processors and by breeders to ensure future varieties have high WE‐AX to make healthier wheat‐based foods.

Dietary fibres, especially non-starch polysaccharides including β-glucan and arabinoxylan from cereal grains, are vital for human health due to their role in lowering cholesterol, regulating glycaemic index, and reducing the risk of chronic diseases like type II diabetes. A daily intake containing 2% or more β-glucan is often associated with health benefits. Wheat ( Triticum aestivum L.), a staple crop and major source of dietary carbohydrates, contains limited variability for these fibre components compared with its wild relatives. To explore genetic resources for fibre biofortification, we evaluated a panel of 478 wheat genotypes including 37 wild relatives, 6 tetraploid, and 435 hexaploid wheat accessions for β-glucan, arabinoxylan, alongside protein, and starch content. The panel showed wide variation, with mean values of 0.93% for β-glucan, 5.77% for arabinoxylan, 13.37% for protein, and 68.51% for starch. Among wild relatives, Aegilops peregrina and Aegilops kotschyi emerged as superior sources of high β-glucan and arabinoxylan, whereas modern cultivars generally exhibited lower values. Significant positive correlations were observed between β-glucan and protein, and negative associations with starch and thousand-grain weight, indicating potential trade-offs in grain composition. These findings highlight the untapped potential of wild genetic resources for enhancing the nutritional quality of wheat and provide promising candidates for pre-breeding and biofortification strategies aimed at improving dietary fibre in staple foods.

Understanding how dietary nutrients modulate the gut microbiome is of great interest for the development of food products and eating patterns for combatting the global burden of non-communicable diseases. In this narrative review we assess scientific studies published from 2005 to 2019 that evaluated the effect of micro- and macro-nutrients on the composition of the gut microbiome using in vitro and in vivo models, and human clinical trials. The clinical evidence for micronutrients is less clear and generally lacking. However, preclinical evidence suggests that red wine- and tea-derived polyphenols and vitamin D can modulate potentially beneficial bacteria. Current research shows consistent clinical evidence that dietary fibers, including arabinoxylans, galacto-oligosaccharides, inulin, and oligofructose, promote a range of beneficial bacteria and suppress potentially detrimental species. The preclinical evidence suggests that both the quantity and type of fat modulate both beneficial and potentially detrimental microbes, as well as the Firmicutes/Bacteroides ratio in the gut. Clinical and preclinical studies suggest that the type and amount of proteins in the diet has substantial and differential effects on the gut microbiota. Further clinical investigation of the effect of micronutrients and macronutrients on the microbiome and metabolome is warranted, along with understanding how this influences host health.

The aim of this study is to review the innovative techniques based on bioprocessing, thermal or physical treatments which have been proposed during the last few decades to convert rice bran into a valuable food ingredient. Rice bran (Oryza sativa) is the main by-product of rice grain processing. It is produced in large quantities worldwide and it contains a high amount of valuable nutrients and bioactive compounds with significant health-related properties. Despite that, its application in food industry is still scarce because of its sensitivity to oxidation processes, instability and poor technological suitability. Furthermore, the health-related effects of pretreated rice bran are also presented in this review, considering the up-to-date literature focused on both in vivo and in vitro studies. Moreover, in relation to this aspect, a brief description of rice bran arabinoxylans is provided. Finally, the application of rice bran in the food industry and the main technology aspects are concisely summarized.

The consumption of whole grain products is often related to beneficial effects on consumer health. Dietary fibre is an important component present in whole grains and is believed to be (at least partially) responsible for these health benefits. The dietary fibre composition of whole grains is very distinct over different grains. Whole grains of cereals and pseudo-cereals are rich in both soluble and insoluble functional dietary fibre that can be largely classified as e.g., cellulose, arabinoxylan, β-glucan, xyloglucan and fructan. However, even though the health benefits associated with the consumption of dietary fibre are well known to scientists, producers and consumers, the consumption of dietary fibre and whole grains around the world is substantially lower than the recommended levels. This review will discuss the types of dietary fibre commonly found in cereals and pseudo-cereals, their nutritional significance and health benefits observed in animal and human studies.

This review article revises the sustainable practices and applications to valorize valuable components recovered from cereal processing by-products. After introducing cereal processing by-products, their healthy compounds, and corresponding functional properties, the article explores reutilization opportunities of by-products emphasizing specific sources (e.g., oat and wheat bran, distillers’ dried grains, etc.) and the biorefinery approach. Proteins and soluble dietary fibers such as arabinoxylans are of particular interest due to their content in the cereal processing by-products and their easy extraction based on conventional technologies such as enzyme-assisted extraction and membrane filtration. Non-thermal technologies have also been suggested to improve sustainability recovery approaches. Finally, the article discusses the different applications for the recovered high-added value compounds that span across biotechnology, foods, and bakery products.

The selection of wheat varieties with high arabinoxylan (AX) levels could effectively improve the daily consumption of dietary fiber. However, studies on the selection of markers for AX levels are scarce. This study analyzed AX levels in 562 wheat genotypes collected from 46 countries using a GWAS with the BLINK model in the GAPIT3. Wheat genotypes were classified into eight subpopulations that exhibited high genetic differentiation based on 31,926 SNP loci. Eight candidate genes were identified, among which those encoding F-box domain-containing proteins, disease resistance protein RPM1, and bZIP transcription factor 29 highly correlated with AX levels. The AX level was higher in the adenine allele than in the guanine alleles of these genes in the wheat collection. In addition, the AX level was approximately 10% higher in 3 adenine combinations than 2 guanine, 1 adenine, and 3 guanine combinations in genotypes of three genes (F-box domain-containing proteins, RPM1, and bZIP transcription factor 29). The adenine allele, present in 97.46% of AX-95086356 SNP, exhibited a high correlation with AX levels following classification by country. Notably, the East Asian wheat genotypes contain high adenine alleles in three genes. These results highlight the potential of these three SNPs to serve as selectable markers for high AX content.