Unveiling the microbiota-mediated impact of different dietary proteins on post-digestive processes: A simulated in vitro approach

Protein digestion and microbial metabolism play crucial roles in overall health. However, the mechanisms that differentiate the digestion and metabolism of dietary proteins from different sources in the organism remain poorly understood. This study investigated the digestive properties and microbial fermentation of various animal proteins (chicken, pork, beef, and casein) and plant proteins (soy bean, mung bean, kidney bean, rice, and wheat) in an in vitro simulation. The results indicated that animal-derived proteins had higher essential amino acid content (33.97-37.12 g/100 g) and digestibility levels (49.15-60.94 %), and provided more small molecule peptides upon digestion. Nevertheless, soy bean and wheat proteins also exhibited higher digestibility (54.70 % and 60.94 %), probably due to the extraction process. The fermentation results showed that distinct metabolic profiles that emerged for different protein sources. Plant-derived proteins (especially kidney bean, rice and wheat) promoted the proliferation of beneficial bacteria and microbial diversification and stimulated short-chain fatty acids (SCFA) production. Conversely, meat proteins (pork, chicken, beef) had significantly lower microbial diversity and SCFA than these plant proteins. These findings provide valuable insights into the effects of dietary protein sources on digestion and gut microbiome, and offer scientific guidance for optimizing dietary choices to improve health.

Polysaccharide from Boletus aereus ameliorates DSS-induced colitis in mice by regulating the MANF/MUC2 signaling and gut microbiota

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions characterized by disruptions in the colonic mucus barrier and gut microbiota. In this study, a novel soluble polysaccharide obtained from Boletus aereus (BAP) through water extraction was examined for its structure. The protective effects of BAP on colitis were investigated using a DSS-induced mice model. BAP was found to promote the expression of intestinal mucosal and tight junction proteins, restore the compromised mucus barrier, and suppress the activation of inflammatory signaling. Moreover, BAP reshape the gut microbiota and had a positive impact on the composition of the gut microbiota by reducing inflammation-related microbes. Additionally, BAP decreased cytokine levels through the MANF-BATF2 signaling pathway. Correlation analysis revealed that MANF was negatively correlated with the DAI and the level of cytokines. Furthermore, the depletion of gut microbiota using antibiotic partially inhabited the effect of BAP on the activation of MANF and Muc2, indicating the role of gut microbiota in its protective effect against colitis. In conclusion, BAP had an obvious activation on MANF under gut inflammation. This provides new insights into the prospective use of BAP as a functional food to enhance intestinal health.

New Horizons in Probiotics: Unraveling the Potential of Edible Microbial Polysaccharides through In Vitro Digestion Models

In vitro digestion models, as innovative assessment tools, possess advantages such as speed, high throughput, low cost, and high repeatability. They have been widely applied to the investigation of food digestion behavior and its potential impact on health. In recent years, research on edible polysaccharides in the field of intestinal health has been increasing. However, there is still a lack of systematic reviews on the application of microbial-derived edible polysaccharides in in vitro intestinal models. This review thoroughly discusses the limitations and challenges of static and dynamic in vitro digestion experiments, while providing an in-depth introduction to several typical in vitro digestion models. In light of this, we focus on the degradability of microbial polysaccharides and oligosaccharides, with a particular emphasis on edible microbial polysaccharides typically utilized in the food industry, such as xanthan gum and gellan gum, and their potential impacts on intestinal health. Through this review, a more comprehensive understanding of the latest developments in microbial polysaccharides, regarding probiotic delivery, immobilization, and probiotic potential, is expected, thus providing an expanded and deepened perspective for their application in functional foods.

Effect of structural characteristics of resistant starch prepared by various methods on microbial community and fermentative products

Resistant starch (RS) has been extensively studied because of its beneficial effects on gut microbiota. In this study, four RSs obtained through various preparation processes were utilized for in vitro fermentation, and their structural characteristics before and after fermentation were determined using chromatography, Fourier infrared spectroscopy, and scanning electron microscopy (SEM). It was observed that these RSs can be classified into two categories based on their fermentation and structural features. The autoclaving RS (ARS) and extruding RS (ERS) were classified as Class I Microbiome Community (MC-I), characterized by a higher proportion of butyrate and its producers, including unclassified_g_Megasphaera and Megasphaera elsdenii. While microwaving RS (MRS) and ultrasound RS (URS) belonged to Class II Microbiome Community (MC-II), marked by a higher proportion of acetate and its producer, Bifidobacterium pseudocatenulatum DSM 20438. MC-I had a lower molecular weight, shorter chain length, more chains with degree of polymerization (DP) 36-100, and a more ordered structure than MC-II. Furthermore, SEM observations revealed distinct degradation patterns between MC-I and MC-II, which may be attributed to their surface structural characteristics. These findings imply that the preparation methods employed for RS can determine its multilevel structural characteristics, and consequently influence its physiological properties.

Effects of dietary Clostridium butyricum on the growth performance, digestion, and intestinal health of spotted sea bass (Lateolabrax maculatus)

Clostridium butyricum (CB) is known to promote growth, enhance immunity, promote digestion, and improve intestinal health. In this study, we investigated the effects of CB in the feed on growth performance, digestion, and intestinal health of juvenile spotted sea bass. To provide a theoretical basis for the development and application of CB in the feed of spotted sea bass, a total of 450 spotted sea bass with an initial body weight of (9.58 ± 0.05) g were randomly divided into six groups. Gradient levels with 0, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% of CB (1×10⁹ cfu/g) were supplemented into diets, designated as CC, CB1, CB2, CB3, CB4, and CB5, respectively. Each group was fed for 54 days. Our results suggest that dietary 0.2% and 0.3% of CB can significantly increase the weight gain (WG) and specific growth rate (SGR) of spotted sea bass. The addition of CB significantly increased intestinal amylase activity, intestinal villus length, intestinal villus width, and intestinal muscle thickness. Similarly, CB supplementation increased the expression of tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8). Sequence analysis of the bacterial 16S rDNA region showed that dietary CB altered the intestinal microbiota profile of juvenile spotted sea bass, increasing the dominant bacteria in the intestine and decreasing the harmful bacteria. Overall, dietary addition of CB can improve growth performance, enhance intestinal immunity, improve intestinal flora structure, and comprehensively improve the health of spotted sea bass.

Regulatory Effects of the Probiotic Clostridium butyricum on Gut Microbes, Intestinal Health, and Growth Performance of Chickens

Clostridium butyricum is an important probiotic for chickens and exerts various biological activities, including altering the composition of the intestinal microbiota, competing with other microorganisms for nutrients, improving the integrity of the intestinal mucosal system, changing the intestinal barrier, and improving overall host health. Intestinal microbes also play vital roles in maintaining the intestinal barrier, regulating intestinal health, and promoting chicken growth. During chicken production, chickens are vulnerable to various stressors that have detrimental effects on the intestinal barrier with significant economic consequences. C. butyricum is a known probiotic that promotes intestinal health and produces the short-chain fatty acid butyric acid, which is beneficial for the growth performance of chickens. This review elucidates the development and utilization of C. butyricum to improve intestinal barrier function and growth performance in chickens through its probiotic properties and interactions with intestinal microbes.

Functional oligosaccharide fermentation in the gut: Improving intestinal health and its determinant factors-A review

The human intestine is characterized by an abundance of nutrients and a complex microbiota that make crucial contributions to overall health. These nutrients facilitate the adaptation of resident commensals to extreme environments and the development of a robust ecological network in host species. Long-term deprivation of microbiota-accessible carbohydrates (MACs) in the gut results in a loss of bacterial diversity, disruption of intestinal barrier function, and inflammatory diseases. Functional oligosaccharides are excellent MACs possessing important prebiotic properties for intestinal health through their fermentation in the gut. Its mechanism of action is predominantly attributed to acting as carbon sources for specific probiotics, promoting short-chain fatty acids production, and regulating the gut microbiota. In this review, we describe the source and structural characteristics of functional oligosaccharides, provide a framework for strategies to improve intestinal health by oligosaccharide fermentation and discuss structural determinants influencing the functional properties of oligosaccharides.

Characterization of polysaccharide from Pleurotus eryngii during simulated gastrointestinal digestion and fermentation

Pleurotus eryngii is a valuable new edible mushroom variety cultivated on a large scale in China. The polysaccharides found in this mushroom are strong bioactive. This study used simulated digestion and fermentation model to study the digestion and fermentation characteristics of Pleurotus eryngii polysaccharide (PEP) and its effect on gut microbiota. The results showed that the molecular weight of PEP remained unchanged after simulated digestion, and the overall structure of PEP was not destroyed, indicating that PEP was not decomposed during digestion. However, during fermentation, PEP was degraded and utilized by intestinal flora to produce a variety of short-chain fatty acids (SCFAs), which reduced the pH value in fecal cultures. Meanwhile, PEP regulated the composition of intestinal flora, and the relative abundance of Firmicutes increased significantly. These suggests that PEP can be used as a functional food to promote intestinal health and prevent disease.

Comparison of Different Soluble Dietary Fibers during the In Vitro Fermentation Process

Soluble dietary fibers being fermented by gut microbiota constitute a pivotal prerequisite for soluble dietary fibers exhibiting physiological functions. However, the relationship between fiber type and gut microbiota metabolism remains unclear. The purpose of this study was to investigate and compare the effect of fiber types on short-chain fatty acid (SCFA) biosynthesis in a simulated colon. Results showed that different soluble dietary fibers caused distinct metabolic profiles both in SCFAs and organic acids. Further analysis revealed that the SCFA biosynthesis pathway was related to the chain structure of fiber polysaccharides. Moreover, the microbial community structure showed substantial difference among experimental groups. Parabacteroides was substantially elevated in the resistant starch group, while Lactobacillus was the predominant genus in other groups. Correlation analysis further revealed that SCFA biosynthesis was correlated with microbial taxa at different taxonomic levels. Totally, the present study provided an insight into targeted intervention of gut microorganisms for dictating SCFA and organic acid production.

Systematic assessment of oat β-glucan catabolism during in vitro digestion and fermentation

β-Glucan as a component of grain cell walls is consumed daily. However, little is known about whether β-glucan is influenced by the gastrointestinal environment. In this study, we aim to investigate the integrated metabolic process of cereal β-glucan. In vitro simulated digestion and fermentation combined with microbiome and metabolome analysis were used to profile the metabolism of β-glucan. Intriguingly, we found that β-glucan was not hydrolyzed by digestive enzymes but partially degraded by gastric acid environment during in vitro digestion. Moreover, β-glucan was utilized by gut microbiota to produce acetate, propionate and butyrate, concurrently, the relative abundance of Lactobacillus significantly increased and Escherichia-Shigella significantly decreased. The correlation analysis between metabolomics datasets and microorganisms revealed that β-glucan catabolism was also accompanied by amino acid catabolism and linoleic acid biosynthesis. Our study offered a forceful basis for the further exploration of the role of β-glucan and gut microbiota in host health.

Nondigestible carbohydrates, butyrate, and butyrate-producing bacteria

Nondigestible carbohydrates (NDCs) are fermentation substrates in the colon after escaping digestion in the upper gastrointestinal tract. Among NDCs, resistant starch is not hydrolyzed by pancreatic amylases but can be degraded by enzymes produced by large intestinal bacteria, including clostridia, bacteroides, and bifidobacteria. Nonstarch polysaccharides, such as pectin, guar gum, alginate, arabinoxylan, and inulin fructans, and nondigestible oligosaccharides and their derivatives, can also be fermented by beneficial bacteria in the large intestine. Butyrate is one of the most important metabolites produced through gastrointestinal microbial fermentation and functions as a major energy source for colonocytes by directly affecting the growth and differentiation of colonocytes. Moreover, butyrate has various physiological effects, including enhancement of intestinal barrier function and mucosal immunity. In this review, several representative NDCs are introduced, and their chemical components, structures, and physiological functions, including promotion of the proliferation of butyrate-producing bacteria and enhancement of butyrate production, are discussed. We also describe the strategies for achieving directional accumulation of colonic butyrate based on endogenous generation mechanisms.