Interaction of cellulose and xyloglucan influences in vitro fermentation outcomes

A scalable, chromatography-free, biocatalytic method to produce the xyloglucan heptasaccharide XXXG

Xyloglucan oligosaccharides (XyGOs) are highly branched, complex carbohydrates with a variety of chemical and biotechnological applications. Due to the regular repeating pattern of sidechain substitution of the xyloglucan backbone, well-defined XyGOs are readily accessed for analytical and preparative purposes by specific hydrolysis of the polysaccharide with endo-glucanases. To broaden the application potential of XyGOs, we present here an optimized, scalable method to access large quantities of galactosylated XyGOs by treatment of the bulk agricultural by-product, tamarind kernel powder (TKP), with a highly specific endo-xyloglucanase at high-solids content. Subsequent β-galactosidase treatment reduced XyGO complexity to produce exclusively the branched heptasaccharide XXXG (Xyl3Glc4: [α-D-Xylp-(1 → 6)]-β-D-Glcp-(1 → 4)-[α-D-Xylp-(1 → 6)]-β-D-Glcp-(1 → 4)-[α-D-Xylp-(1 → 6)]-β-D-Glcp-(1 → 4)-D-Glcp). The challenge of removing the co-product galactose was overcome by fermentation with baker's yeast, thereby avoiding chromatography and other fractionation steps to yield highly pure XXXG. This simplified approach employs many of the core concepts of green chemistry and engineering, enables facile production of 100 g quantities of XyGOs and XXXG for laboratory use, and serves as a guide to further production scale-up for applications, including as prebiotics, plant growth effectors and elicitors, and building blocks for glycoconjugate synthesis.

Effect of Lacticaseibacillus paracasei K56 with galactooligosaccharide synbiotics on obese individuals: an in vitro fermentation model

BACKGROUND

The use of synbiotics is emerging as a promising intervention strategy for regulating the gut microbiota and for preventing or reducing obesity, in comparison with the use of probiotics or prebiotics alone. A previous in vivo study revealed that Lacticaseibacillus paracasei K56 (L. paracasei K56) could alleviate obesity induced in high-fat-diet mice; however, the effect of the synbiotic combination of L. paracasei K56 and prebiotics in obese individuals has not been explored fully.

RESULTS

The effect of prebiotics on the proliferation of L. paracasei K56 was determined by spectrophotometry. The results showed that polydextrose (PG), xylooligosaccharide (XOS), and galactooligosaccharide (GOS) had a greater potential to be used as substrates for L. paracasei K56 than three other prebiotics (melitose, stachyose, and mannan-oligosaccharide). An in vitro fermentation model based on the feces of ten obese female volunteers was then established. The results revealed that K56_GOS showed a significant increase in GOS degradation rate and short-chain fatty acid (SCFA) content, and a decrease in gas levels, compared with PG, XOS, GOS, K56_PG, and K56_XOS. Changes in these microbial biomarkers, including a significant increase in Bacteroidota, Bifidobacterium, Lactobacillus, Faecalibacterium, and Blautia and a decrease in the Firmicutes/Bacteroidota ratio and Escherichia-Shigella in the K56_GOS group, were associated with increased SCFA content and decreased gas levels.

CONCLUSION

This study demonstrates the effect of the synbiotic combination of L. paracasei K56 and GOS on obese individuals and indicates its potential therapeutic role in obesity treatment. © 2024 Society of Chemical Industry.

Recent advances in polysaccharide biomodification by microbial fermentation: production, properties, bioactivities, and mechanisms

Polysaccharides are natural chemical compounds that are extensively employed in the food and pharmaceutical industries. They exhibit a wide range of physical and biological properties. These properties are commonly improved by using chemical and physical methods. However, with the advancement of biotechnology and increased demand for green, clean, and safe products, polysaccharide modification via microbial fermentation has gained importance in improving their physicochemical and biological activities. The physicochemical and structural characteristics, biological activity, and modification mechanisms of microbially fermented polysaccharides were reviewed and summarized in this study. Polysaccharide modifications were categorized and discussed in terms of strains and fermentation techniques. The effects of microbial fermentation on the physicochemical characteristics of polysaccharides were highlighted. The impact of modification of polysaccharides on their antioxidant, immune, hypoglycemic, and other activities, as well as probiotic digestive enhancement, were also discussed. Finally, we investigated a potential enzyme-based process for polysaccharide modification via microbial fermentation. Modification of polysaccharides via microbial fermentation has significant value and application potential.

Plant cell wall composition modulates the gut microbiota and metabolites in in-vitro fermentation

This research investigated the effect of different types of plant cell wall fibres, including cereal (i.e., barley, sorghum, and rice), legume (i.e., pea, faba bean, and mung bean), and tuber (potato, sweet potato, and yam) cell wall fibres on in vitro faecal fermentation profiles and gut microbiota composition. The cell wall composition, specifically the content of lignin and pectin, was found to have a significant influence on the gut microbiota and fermentation outcomes. Compared with type I cell walls (legume and tuber) which have high pectin content, the type II cell walls (cereal) which are high in lignin but low in pectin had a lower fermentation rates and less short-chain fatty acid production. The redundancy analysis showed samples with similar fibre composition and fermentation profiles clustered together, and the principal coordinate analysis revealed separation among different types of cell walls and closer proximity among the same cell wall types. These findings emphasize the importance of cell wall composition in shaping the microbial community during fermentation and contribute to a better understanding of the relationship between plant cell walls and gut health. This research has practical implications for the development of functional foods and dietary interventions.

Food biopolymer behaviors in the digestive tract: implications for nutrient delivery

Biopolymers are prevalent in both natural and processed foods, serving as thickeners, emulsifiers, and stabilizers. Although specific biopolymers are known to affect digestion, the mechanisms behind their influence on the nutrient absorption and bioavailability in processed foods are not yet fully understood. The aim of this review is to elucidate the complex interplay between biopolymers and their behavior in vivo, and to provide insights into the possible physiological consequences of their consumption. The colloidization process of biopolymer in various phases of digestion was analyzed and its impact on nutrition absorption and gastrointestinal tract was summarized. Furthermore, the review discusses the methodologies used to assess colloidization and emphasizes the need for more realistic models to overcome challenges in practical applications. By controlling macronutrient bioavailability using biopolymers, it is possible to enhance health benefits, such as improving gut health, aiding in weight management, and regulating blood sugar levels. The physiological effect of extracted biopolymers utilized in modern food structuring technology cannot be predicted solely based on their inherent functionality. It is essential to account for factors such as their initial consuming state and interactions with other food components to better understand the potential health benefits of biopolymers.

Configured for the Human Gut Microbiota: Molecular Mechanisms of Dietary β-Glucan Utilization

The β-glucans are a disparate group of structurally diverse polysaccharides, whose members are widespread in human diets as components of the cell walls of plants, algae, and fungi (including yeasts), and as bacterial exopolysaccharides. Individual β-glucans from these sources have long been associated with positive effects on human health through metabolic and immunological effects. Remarkably, the β-configured glucosidic linkages that define these polysaccharides render them inaccessible to the limited repertoire of digestive enzymes encoded by the human genome. As a result, the various β-glucans become fodder for the human gut microbiota (HGM) in the lower gastrointestinal tract, where they influence community composition and metabolic output, including fermentation to short chain fatty acids (SCFAs). Only recently, however, have the specific molecular systems that enable the utilization of β-glucans by select members of the HGM been fully elucidated by combined genetic, biochemical, and structural biological approaches. In the context of β-glucan structures and their effects on human nutrition and health, we summarize here the functional characterization of individual polysaccharide utilization loci (PULs) responsible for the saccharification of mixed-linkage β(1→3)/β(1→4)-glucans, β(1→6)-glucans, β(1→3)-glucans, β(1→2)-glucans, and xyloglucans in symbiotic human gut bacteria. These exemplar PULs serve as well-defined biomarkers for the prediction of β-glucan metabolic capability in individual bacterial taxa and across the global human population.