Human Intestinal Flora Research Articles

Unveiling the Power of Flax Lignans: From Plant Biosynthesis to Human Health Benefits.

Flax (Linum usitatissimum L.) is the richest plant source of lignin secondary metabolites. Lignans from flax have been applied in the fields of food, medicine, and health due to their significant physiological activities. The most abundant lignan is secoisolariciresinol, which exists in a glycosylated form in plants. After ingestion, it is converted by human intestinal flora into enterodiol and enterolactone, which both have physiological roles. Here, the basic structures, contents, synthesis, regulatory, and metabolic pathways, as well as extraction and isolation methods, of flax lignans were reviewed. Additionally, the physiological activity-related mechanisms and their impacts on human health, from the biosynthesis of lignans in plants to the physiological activity effects observed in animal metabolites, were examined. The review elucidates that lignans, as phenolic compounds, not only function as active substances in plants but also offer significant nutritional values and health benefits when flax is consumed.

Simulated Gastrointestinal Digestion and Fecal Fermentation Characteristics of Exopolysaccharides Synthesized by Schleiferilactobacillus harbinensis Z171.

Exopolysaccharides (EPSs) produced by Lactobacillus have important physiological activities and are commonly used as novel prebiotics. A strain of Lactobacillus with high EPS yield was identified as Schleiferilactobacillus harbinensis (S. harbinensis Z171), which was isolated from Chinese sauerkraut. The objective of this study was to investigate the in vitro simulated digestion and fecal fermentation behavior of the purified exopolysaccharide fraction F-EPS1A from S. harbinensis Z171 and its influence on the human intestinal flora composition. The in vitro digestion results showed that the primary structural characteristics of F-EPS1A, such as morphology, molecular weight, and monosaccharide composition remained stable after saliva and gastrointestinal digestion. Compared with the blank group, the fermentation of F-SPS1A by fecal microbiota decreased the diversity of the bacterial communities, significantly promoted the relative abundance of Bifidobacterium and Faecalibacterium, and decreased the relative abundance of Lachnospiraceae_Clostridium, Fusobacterium, and Oscillospira. Reverse transcription polymerase chain reaction (RT-PCR) analysis also showed that the population of Bifidobacterium markedly increased. Furthermore, the total short-chain fatty acid levels increased significantly, especially for butyric acid. Gas chromatography-mass spectrometry (GC-MS) results showed that F-EPS1A could be fermented by the human gut microbiota to synthesize organic acids and derivative metabolites that are beneficial to gut health. Therefore, these findings suggest that F-EPS1A could be exploited as a potential prebiotic.

In vitro simulated digestion of different heat treatments sweet potato polysaccharides and effects on human intestinal flora

The aim of this study was to investigate the changes of untreated and steamed (100 °C, 20 min), fried (150 °C, 10 min), and baked (200 °C, 30 min) sweet potato polysaccharides during in vitro digestion and their effects on the intestinal flora. The results showed that the reducing sugar content of all four sweet potato polysaccharides increased significantly during digestion. During in vitro fecal fermentation, the content of reducing sugars and total carbohydrates decreased significantly. It indicated that all four polysaccharides showed degradation of polysaccharides during fermentation. Compared to the blank group, the total SCFAs content of the four polysaccharide sample groups was significantly increased. It was worth noting that sweet potato polysaccharides increased the percentage of Bacteroidetes and decreased the percentage of Proteobacteria in the intestinal flora. The findings provide evidence that sweet potato polysaccharides regulate intestinal flora and maintain intestinal health through interactions with intestinal flora.

Modulation effect of sulfated polysaccharide from Sargassum fusiforme on gut microbiota and their metabolites in vitro fermentation.

The present study demonstrated the digestion behavior and fermentation characteristics of a sulfated polysaccharide from Sargassum fusiforme (SFSP) in the simulated digestion tract environment. The results showed that the molecular weight of two components in SFSP could not be changed by simulated digestion, and no free monosaccharide was produced. This indicates that most of SFSP can reach the colon as prototypes. During the fermentation with human intestinal flora in vitro, the higher-molecular-weight component of SFSP was utilized, the total sugar content decreased by 16%, the reducing sugar content increased, and the galactose content in monosaccharide composition decreased relatively. This indicates that SFSP can be selectively utilized by human intestinal flora. At the same time, SFSP also changed the structure of intestinal flora. Compared with the blank group, SFSP significantly increased the abundance of Bacteroidetes and decreased the abundance of Firmicutes. At the genus level, the abundances of Bacteroides and Megamonas increased, while the abundances of Shigella, Klebsiella, and Collinsella decreased. Moreover, the concentrations of total short-chain fatty acids (SCFAs), acetic, propionic and n-butyric acids significantly increased compared to the blank group. SFSP could down-regulate the contents of trimethylamine, piperidone and secondary bile acid in fermentation broth. The contents of nicotinic acid, pantothenic acid and other organic acids were increased. Therefore, SFSP shows significant potential to regulate gut microbiota and promote human health.

Adsorption, in vitro digestion and human gut microbiota regulation characteristics of three Poria cocos polysaccharides

Poria cocos (PC) is a famous traditional Chinese medicine (TCM) and a widely used healthcare ingredient, which has antiobesity, enhancing immunity and improving sleep effects. Traditionally, only water-soluble poria polysaccharide (WSP) is extracted and applied for clinical application, while insoluble polysaccharide (alkali-soluble poria polysaccharide, ASP) is discarded as herb residue. However, the whole PC has also been historically utilized as functional herbal food. Considering the beneficial role of dietary fiber and the traditional use of PC, ASP may also contribute substantially to the therapy function of PC. Compared to WSP, little attention has been paid to ASP and ASP modified product carboxymethyl poria polysaccharide (CMP) which has been used as an antitumor adjuvant drug. In this study, the oil, cholesterol, metal ions and polyphenols adsorption ability, in vitro simulated digestive and the gut microbiota fermentation characteristics of WSP, ASP and CMP were studied to evaluate the functional values of three P. cocos polysaccharides (PCPs). The results showed that all three PCPs had good adsorption capacity on cholesterol, polyphenols and metal ions (Cd2+/Zn2+/Mg2+), among which ASP showed the highest capacity than WSP and CMP. The adsorption capacity of all three PCPs on heavy metal ions (Cd2+/Zn2+) was stronger than that of non-heavy metal ions (Mg2+); The in vitro digestibility of all three PCPs was very low, but WSP was slightly higher than ASP and CMP; Moreover, the indigestible residue of all three PCPs could improve the richness and diversity of gut microbiota, among which ASP had the greatest influence. In general, ASP and CMP could significantly promote the proliferation of some probiotics and inhibit the growth of some harmful bacteria. The gut microbiota diversity of CMP was reduced, but the richness of probiotics, especially Parabacteroides distasonis was significantly enhanced compared with the ASP group, and the growth of harmful bacteria Klebsiella pneumoniae was inhibited after CMP treatment. The short-chain fatty acids (SCFAs) analysis results showed that all three PCPs could significantly promote the production of acetic acid, propionic acid and the total acid content compared with blank control group, and SCFAs producing activity was positively correlated with the proliferative capacity of probiotics. Taken together, the good adsorption characteristics and gut microbiota regulatory activity of ASP may lay foundation for its lipid-lowering and immune-improving function. Additionally, the probiotic effect of CMP and ASP indicated that except for only use the water extract of PC in clinic, CMP and ASP also can be used in healthcare to take full advantage of this valuable medicine.

New Perspectives on the Risks of Hydroxylated Polychlorinated Biphenyl (OH-PCB) Exposure: Intestinal Flora α-Glucosidase Inhibition.

Polychlorinated biphenyls (PCBs) are a group of colorless and odorless environmental pollutants with a wide range of toxic effects. Some PCBs, especially less chlorinated ones, will rapidly undergo phase I metabolism after entering the body, and hydroxylated polychlorinated biphenyls (OH-PCBs) are the main metabolites of PCBs. Intestinal flora α-glucosidase is a common carbohydrate-active enzyme which is ubiquitous in human intestinal flora. It can convert complex dietary polysaccharides into monosaccharides, assisting the body in degrading complex carbohydrates and providing energy for the survival and growth of bacterial flora. The present study aims to investigate the inhibition of the activity of intestinal flora α-glucosidase by OH-PCBs. 4-Nitrophenyl-α-D-glucopyranoside (PNPG) was used as a probe substrate for α-glucosidase, and in vitro incubation experiments were conducted to study the inhibition of 26 representative OH-PCBs on α-glucosidase. Preliminary screening of in vitro incubation was performed with 100 μM of OH-PCBs. The results showed that 26 OH-PCBs generally exhibited strong inhibition of α-glucosidase. The concentration-dependent inhibition and half inhibition concentrations (IC50s) of OH-PCBs on α-glucosidase were determined. 4'-OH-PCB 86 and 4'-OH-PCB 106 were chosen as representative OH-PCBs, and the inhibition kinetic parameters (Kis) of inhibitors for α-glucosidase were determined. The inhibition kinetic parameters (Kis) of 4'-OH-PCB 86 and 4'-OH-PCB 106 for α-glucosidase are 1.007 μM and 0.538 μM, respectively. The silico docking method was used to further analyze the interaction mechanism between OH-PCBs and α-glucosidase. All these results will help us to understand the risks of OH-PCB exposure from a new perspective.

A Comparative Study of The Effects of Sumac Aqueous and Ethanol Extracts on Candida Albicans in Laboratory Conditions

Background and purpose: Candida albicans is an opportunistic pathogenic fungus that is considered a member of the human intestinal flora that can survive outside the human body. This fungus is usually a harmless organism, but it can become pathogenic in immunocompromised people under various conditions. For oral infections, treatment with topical clotrimazole or nystatin is usually effective. In case of failure, oral or intravenous fluconazole, itraconazole or amphotericin B may be used. Several topical antifungal medications may be used for vaginal infections, including clotrimazole. This study was conducted to investigate the effect of sumac aqueous and ethanol extracts on Candida albicans. Methods: In this experimental study, aqueous and alcoholic sumac extracts were prepared and different concentrations were prepared to investigate their effect on Candida albicans. The negative control included the culture medium without mushrooms and the positive control included mushrooms without extract. Candida albicans fungus was cultured after 24, 48 and 72 hours, and control drug concentrations for fluconazole were 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32 on Candida albicans. The effect was given. Methods: In this experimental study, aqueous and alcoholic sumac extracts were prepared and different concentrations were prepared to investigate their effect on Candida albicans. The negative control included the culture medium without mushrooms and the positive control included mushrooms without extract. Candida albicans fungus was cultured after 24, 48 and 72 hours, and control drug concentrations for fluconazole were 32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.125 millilitres per milligram on Candida albicans. The effect was given. Results: After the cultivation of Candida albicans mushroom and examination, it was found that this mushroom can grow in all concentrations of aqueous extract of the sumac plant and none of the tested concentrations can prevent its growth, and the alcoholic extract at a concentration of 60 mg/ml can inhibit growth. MIC) of Candida albicans fungus, but the fungus was able to grow in other concentrations. The concentration of 0.5 mg/ml of the commercial antibiotic fluconazole could inhibit the growth (MIC) of this fungus. Conclusion: While different concentrations of aqueous and alcoholic extracts of the sumac plant were investigated and it was found that aqueous extract has no effect and alcoholic extract is effective in the same concentration, more and more comprehensive studies are suggested in laboratory scale and living organisms.

Assessing the impact of heavy metal residues in food and drug packaging on the standard bacterial strains: a biofilm perspective

ABSTRACT The presence and migration of heavy metals from food and drug packaging materials into consumables pose significant health concerns. This study explored the effects of vanadium, arsenic, cadmium, and mercury contained in the digest of packaging materials on biofilms formed by standard strains of Escherichia coli ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70063, and Enterococcus faecalis ATCC 29212. Results showed that vanadium at 1.2 µg/ml promoted strong biofilm formation in all tested bacteria, while cadmium (1 µg/ml) and mercury (6.6 µg/ml) supressed biofilm formation. Arsenic at 0.6 µg/ml initially facilitated biofilm formation, but its effectiveness decreased with higher concentrations. This interference of heavy metals digests on biofilm formation in the gut microbiota is a concern, as leached heavy metals into food when consumed could disrupt the balance of human intestinal flora and homeostasis.

Effects of Hypoxemia by Acute High-Altitude Exposure on Human Intestinal Flora and Metabolism.

This study examined the effects of hypoxemia caused by acute high-altitude hypoxia (AHAH) exposure on the human intestinal flora and its metabolites. The changes in the intestinal flora, metabolism, and erythropoietin content in the AHAH population under altitude hypoxia conditions were comprehensively analyzed using 16S rRNA sequencing, metabonomics, and erythropoietin content. The results showed that compared with those in the control group (C group), the flora and metabolites in the hypoxemia group (D group) were altered. We found alterations in the flora according to the metabolic marker tyrosine through random forest and ROC analyses. Fecal and serum metabonomics analyses revealed that microbial metabolites could be absorbed into the blood and participate in human metabolism. Finally, a significant correlation between tyrosine and erythropoietin (EPO) content was found, which shows that human intestinal flora and its metabolites can help to confront altitude stress by regulating EPO levels. Our findings provide new insights into the adaptive mechanism and prevention of AHAH.

Intervention study of tai chi training on the intestinal flora of college student basketball players.

In recent years, the interactions between host and host-associated gut flora have received increasingly widespread attention. Tai chi is a traditional Chinese exercise, which can significantly benefit adults with health condition. But the studies on the function of intestinal flora and its correlation with tai chi exercise, are limited. In addition, the influence of tai chi on intestinal flora has largely been understudied. In this study, we investigated the changes in intestinal microflora by 16S rRNA sequencing to clarify the specific mechanism of tai chi on the regulation of intestinal flora and seek to formulate a reasonable "exercise prescription." Design: randomized controlled trial. Participants: thirty college basketball players randomly divided into control (n = 15) and test (n = 15) groups. Intervention: experimental group practiced 24-style simplified tai chi ≥ 6 times/week for 20 weeks. Outcomes: serum biochemical markers, blood pressure, and intestinal microbial composition measured post-intervention. Analysis: intent-to-treat analysis. Primary outcomes: after tai chi intervention, the level of high-density lipoprotein cholesterol (1.22 mmol/L) and triglycerides (0.64 mmol/L) were significantly decreased. Secondary outcomes: aspartate transaminase, alanine aminotransferase, total cholesterol, and low-density lipoprotein remained unchanged. Microbiota: α-diversity index significantly increased, particularly with increased Blautia. Blood pressure: test group showed significantly lower diastolic blood pressure (83-95 mm Hg) compared to control. Considering other markers, increased gut flora diversity during exercise may imply a healthier gut environment. Physical exercise promotes a decrease in the inflammatory process by reducing the levels of bacteria associated with pro-inflammation, such as Proteobacteria. Further research is required to understand the nuanced link between gut flora diversity and exercise intensity. 24-style simplified tai chi enhances human intestinal flora diversity. Improvements observed in blood lipid profiles and blood pressure levels.

Role of Healthy Human Gut Microbiota in the Emergence and Dissemination of Extended-Spectrum \(\beta\)-lactamase-Producing Enterobacteriaceae and Genes Associated with \(\beta\)-lactam Resistance in Community Settings in Abidjan, Côte d'Ivoire

Overuse of β-lactam antibiotics in communities in developing countries has transformed healthy human intestinal flora into a reservoir of antibiotic-resistant organisms. The prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in community settings remains undetermined. In order to obtain data on ESBL enterobacteria, 265 stool samples were collected from August 2019 to February 2020 from individuals residing in the urban districts of Abidjan and attending medical consultations at the Institut Pasteur de Côte d'Ivoire. Isolates belonging to family Enterobacteriaceae were isolated on MacConkey and identified using the API 20E galerie and antibiotic susceptibility was determined using Clinical Laboratory Standard Institute disc diffusion method. Detection of extended spectrum β-lactamases (TEM, SHV, GES, PER, VEB, CTXM 1, CTXM 2, CTXM 8 and CTXM 9) was done by simplex and multiplex PCR. The human stools strains consisted of 513 species of Enterobacteria multidrug resistants. Among the 513 strains, 75 (14.6%) of the enterobacterial strains produced ESBLs, while 438 (85.4%) produced high-level cephalosporinases. Enterobacteria producing extended-spectrum β-lactamase we dominated by the species Escherichia coli (46.7%), Klebsiella pneumoniae (17.3%), Enterobacter cloacae (13.3%), Enterobacter aerogenes (6.7%), Proteus mirabilis (6.7%), Klebsiella oxytoca (4%), Proteus vulgaris (2.7%), Citrobacter koseri (1.3%), and Citrobacter freundii (1.3%). Strains were resistant (100%) to antibiotics from beta-lactam family (penicillin with inhibitor, monobactam, cephalosporin) but low level resistant (1,3%) was observed to carbapenem (imipénème, méropénème, Ertapenem). The rate of resistance to quinolones and aminoglycosides were respectively between 22.9% - 43.3% and 7.9-35.1%. The resistance genes TEM, SHV, CTXM 1, CTXM 2, CTXM 8 and CTXM 9 were detected. No GES and PER genes were not detected. The high fecal carriage rate of ESBL-PE associated with genes in community settings of Ivory Coast highlights the risk for transmission and dissemination because healthy people are potential patients on borrowed time.

Discovery of 1,2-diaryl-3-oxopyrazolidin-4-carboxamides as a new class of MurA enzyme inhibitors and characterization of their antibacterial activity

The cytoplasmic steps of peptidoglycan synthesis represent an important targeted pathway for development of new antibiotics. Herein, we report the synthesis of novel 3-oxopyrazolidin-4-carboxamide derivatives with variable amide side chains as potential antibacterial agents targeting MurA enzyme, the first committed enzyme in these cytosolic steps. Compounds 15 (isoindoline-1,3-dione-5-yl), 16 (4-(1H-pyrazol-4-yl)phenyl), 20 (5-cyanothiazol-2-yl), 21 and 31 (5-nitrothiazol-2-yl derivatives) exhibited the most potent MurA inhibition, with IC50 values of 9.8–12.2 μM. Compounds 15, 16 and 21 showed equipotent inhibition of the C115D MurA mutant developed by fosfomycin–resistant Escherichia coli. NMR binding studies revealed that some of the MurA residues targeted by 15 also interacted with fosfomycin, but not all, indicating an overlapping but not identical binding site. The antibacterial activity of the compounds against E. coli ΔtolC suggests that inhibition of MurA accounts for the observed effect on bacterial growth, considering that a few potent MurA inhibitors could not penetrate the bacterial outer membrane and were therefore inactive as proven by the bacterial cell uptake assay. The most promising compounds were also evaluated against a panel of Gram-positive bacteria. Remarkably, compounds 21 and 31 (MurA IC50 = 9.8 and 10.2 μM respectively) exhibited a potent activity against Clostridioides difficile strains with MIC values ranging from 0.125 to 1 μg/mL, and were also shown to be bactericidal with MBC values between 0.25 and 1 μg/mL. Furthermore, both compounds were shown to have a limited activity against human normal intestinal flora and showed high safety towards human colon cells (Caco-2) in vitro. The thiolactone derivative (compound 5) exhibited an interesting broad spectrum antibacterial activity despite its weak MurA inhibition. Altogether, the presented series provides a promising class of antibiotics that merits further investigation.

Sodium alginate-sodium hyaluronate-hydrolyzed silk for microencapsulation and sustained release of kidney tea saponin: The regulation of human intestinal flora in vitro

Kidney tea saponin (KTS) exhibits considerable efficacy in lowering glucose levels; however, it does not have widespread applications owing to its low intestinal utilization. Therefore, in the present study, we prepared sodium alginate (SA)/sodium hyaluronate (HA)/hydrolyzed silk (SF) gel beads for the effective encapsulation and targeted intestinal release of KTS. The gel beads exhibited an encapsulation rate of 90.67 % ± 0.27 % and a loading capacity of 3.11 ± 0.21 mg/mL; furthermore, the release rate of KTS was 95.46 % ± 0.02 % after 8 h of simulated digestion. Fourier transform infrared spectroscopy revealed that the hydroxyl in SA/HA/SF–KTS was shifted toward the strong peak; this was related to KTS encapsulation. Furthermore, scanning electron microscopy revealed that the gel bead space network facilitates KTS encapsulation. In addition, the ability of KTS and the gel beads to inhibit α-amylase (IC50 = 0.93 and 1.37 mg/mL, respectively) and α-glucosidase enzymes (IC50 = 1.17 and 0.93 mg/mL, respectively) was investigated. In vitro colonic fermentation experiments revealed that KTS increased the abundance of Firmicutes/Bacteroidetes and butyric acid-producing bacteria. The study showed that the developed gel-loading system plays a vital role in delivering bioactive substances, achieving slow release, and increasing the abundance and diversity of intestinal flora.

Bioavailability of Coix Seed Polyphenols in a MKN28/Caco-2 Continuous Transport Model and Their Lipid-Lowering Effects via Modulating Adipocyte Differentiation of 3T3-L1 Cells

At present, most of the research on coix seed polyphenols (CSPs) focuses on the separation, purification, structure analysis, and biological functions of specific components, and few studies have considered the overall bioavailability and the metabolites that play a role after digestion and absorption and their biological functional activities. In this study, we constructed a MKN28 and Caco-2 cell monolayer continuous transport model (MCTM) to study the bioavailability of CSPs in the digestion and absorption stages of the stomach and small intestine. Using this model, we innovatively divided CSPs into easy-to-digest and hard-to-digest polyphenols and studied their intracellular lipid-lowering function and their influence on human intestinal flora. Transwell experiments showed that ferulic acid, rutin, naringin, arbutin, and syringetin had high transmembrane transport efficiency, especially syringetin. The methylation reaction in the monolayer membrane of Caco-2 cells may be the reason for the higher transport rate of syringetin. Further experiments showed that CPL reduced TG accumulation by more than 50% during 3T3-L1 differentiation and promoted the transformation of adipocytes into brown cells (p < 0.05). Finally, in vitro fermentation experiments showed that CSP_AP can increase the abundance of Lactobacillus and Bifidobacterium of human gut microbiota at the genus level (p < 0.05).

BLAB2CancerKD: a knowledge graph database focusing on the association between lactic acid bacteria and cancer, but beyond.

In a broad sense, lactic acid bacteria (LAB) is a general term for Gram-positive bacteria that can produce lactic acid by utilizing fermentable carbohydrates. It is widely used in essential fields such as industry, agriculture, animal husbandry and medicine. At the same time, LAB are closely related to human health. They can regulate human intestinal flora and improve gastrointestinal function and body immunity. Cancer, a disease in which some cells grow out of control and spread to other body parts, is one of the leading causes of human death worldwide. In recent years, the potential of LAB in cancer treatment has attracted attention. Mining knowledge from the scientific literature significantly accelerates its application in cancer treatment. Using 7794 literature studies of LAB cancer as source data, we have processed 16 543 biomedical concepts and 23 091 associations by using automatic text mining tools combined with manual curation of domain experts. An ontology containing 31 434 pieces of structured data is constructed. Finally, based on ontology, a knowledge graph (KG) database, which is called Beyond 'Lactic acid bacteria to Cancer Knowledge graph Database' (BLAB2CancerKD), is constructed by using KG and web technology. BLAB2CancerKD presents all the relevant knowledge intuitively and clearly in various data presentation forms, and the interactive system function also makes it more efficient. BLAB2CancerKD will be continuously updated to advance the research and application of LAB in cancer therapy. Researchers can visit BLAB2CancerKD at. Database URL http://110.40.139.2:18095/.

CsbD, a Novel Group B Streptococcal Stress Response Factor That Contributes to Bacterial Resistance against Environmental Bile Salts.

Group B Streptococcus (GBS) can cause many serious infections and result in severe symptoms depending on the infected organs. To survive and initiate infection from the gastrointestinal tract, GBS must resist physiochemical factors, such as bile salts, a potent antibacterial compound in the intestine. We found that GBS isolated from diverse sources all possess the capability to defend bile salts and permit survival. By constructing the GBS A909 transposon mutant library (A909Tn), we identified several candidate genes that might participate in the bile salt resistance of GBS. The rodA and csbD genes were validated as relevant to bile salt resistance. The rodA gene was anticipated to be related to peptidoglycan synthesis and influence the bile salt resistance of GBS by cell wall construction. Notably, we found that the csbD gene worked as a bile salt resistance response factor and influenced several ABC transporter genes, specifically at the later growth period of GBS under bile salt stress. We further detected the marked intracellular bile salt accumulation in ΔcsbD by hydrophilic interaction chromatography-liquid chromatography/mass spectrometry (HILIC-LC/MS). Collectively, we showed a novel GBS stress response factor, csbD, contributes to bacterial survival in bile salts by sensing bile salt stress and subsequently induces transcription of transporter genes to excrete bile salts. IMPORTANCE GBS, a conditional pathogenetic colonizer of the human intestinal flora, can cause severe infectious diseases in immunocompromised patients. Therefore, it is critical to understand the factors that contribute to the resistance to bile salts, which are abundant in the intestine but harmful to bacteria. We identified rodA and csbD genes involved in bile salt resistance using a transposon insertion site sequencing (TIS-seq) based screen. The rodA gene products might be involved in peptidoglycan synthesis as important contributors to stress resistance including bile salts. However, the csbD gene conferred bile salt resistance by promoting transporter genes transcription at the later growth period of GBS in response to bile salts. These findings developed a better understanding of the stress response factor csbD on the bile salt resistance of GBS.

In vitro fermentation of seaweed polysaccharides and tea polyphenol blends by human intestinal flora and their effects on intestinal inflammation.

A combination of polysaccharides and tea polyphenols can enhance immune activity synergistically, depending on the type and structure of polysaccharides, but the mechanism remains unknown. This study is aimed to investigate the regulating effects of different seaweed polysaccharide (ι-carrageenan, agarose) and tea polyphenol blends on intestinal flora and intestinal inflammation using an in vitro ascending-transverse-descending colon fermentation system and RAW264.7 cell model. The results showed that seaweed polysaccharides in the presence of tea polyphenol were almost completely degraded at transverse colon fermentation for 36 h. Agarose significantly enhanced the butyric acid production content by increasing the abundance of Lachnospiraceae, whereas agarose and tea polyphenol blends did not have a synergistic effect. On the contrary, ι-carrageenan and tea polyphenol blends synergistically increased the abundance of beneficial bacteria (e.g., Bacteroidetes and Bifidobacterium) and promoted the production of short-chain fatty acids (SCFAs), such as isobutyric acid. Such changes tended to alter the impacts of different seaweed polysaccharides and tea polyphenol blends on intestinal inflammation. Among them, ι-carrageenan and tea polyphenol blends were the most effective in inhibiting lipopolysaccharide-induced NO, ROS, IL-6, and TNF-α production in RAW264.7 cells, indicating the alleviated intestinal inflammation. The results suggest that the seaweed polysaccharide and tea polyphenol blends have prebiotic potential and can benefit intestinal health.

Assessments of the Effects of Organophosphorus Flame Retardants on Human Intestinal Health from the Aspects of Cytotoxicity to Human Cells and Intestinal Flora Changes

Assessments of the Effects of Organophosphorus Flame Retardants on Human Intestinal Health from the Aspects of Cytotoxicity to Human Cells and Intestinal Flora Changes

Effects of Adding Probiotics on Food and the Human Body

The normal growth and reproduction activities of probiotics have beneficial effects on the human body: regulating the human intestinal flora, promoting digestion and absorption, forming a barrier to protect the intestinal mucosa, reducing blood sugar and cholesterol, enhancing human immunity, scavenging free radicals to delay aging, etc. In addition, the active metabolites secreted by it also play an important role in the human body: decomposing cholesterol to produce acids to inhibit pathogenic bacteria, breaking down fats to produce short-chain fatty acids to promote the self-regulation of gastrointestinal mucosal cells, and metabolizing macromolecular substances (proteins, polysaccharides) to produce nutrients (amino acids, monosaccharides). And it is also widely used in food processing, human health and aquaculture. Probiotics also play an important role in food processing, where can change the pH value of food, extend the shelf life of food, improve the flavor of food, as a substitute for additives and increase the nutritional value of food. Although the traditional concept is that only live probiotics can exert their probiotic effects, more and more studies have shown that some of the probiotic effects of probiotics are closely related to their active metabolites, and some of the active metabolites produced by probiotics can stimulate tissue development and affect the body’s nutritional level and physiological functions. At present, the more studied probiotic active metabolites mainly include extracellular polysaccharides, bacteriocins, organic acids, short-chain fatty acids, vitamins, which has been shown to play an antibacterial, where can prevent and treat diseases, regulate and improve the state of the gastrointestinal tract, promote digestion and absorption and other effects. In this paper, two effects of probiotics on the human body are analyzed, including the effects of growth and reproduction and active secretions on human health, and the research progress of probiotics on dairy products and plant products. In addition, the relevant mechanisms of action are highly summarized. The effect of the clinical effective dose of probiotics on functional foods and improving physical health is elaborated, as well as the influencing factors of probiotic intake on intestinal health, and the recommendations of current international standard regulations on probiotic intake are introduced. Through the analysis of the effect of probiotic intake on human intestinal health, the types, functions and applications of probiotic active metabolites are reviewed, and the current existing problems are proposed, and it is hoped to provide practical reference for the industrialization and R&amp;D application of food processing, health care, livestock breeding and other fields, as well as the formulation of probiotic-related standards and regulations.

Enterococcus faecalis thrives in dual-species biofilm models under iron-rich conditions.

Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) are pathogenic strains that often coexist in intestinal flora of humans and are prone to cause biofilm-associated infections, such as gastrointestinal tract and urinary tract infections. Earlier studies have demonstrated that E. faecalis biofilm can metabolize ferrous ions in iron-rich environments and promote biofilm growth under in-vivo conditions. However, the influence of iron transporters on dual-species biofilm growth and the nature of molecular-level interactions between iron transporter proteins and Fe2+ remains unknown. Therefore, in this work, co-culture studies were performed and the study indicates that Fe2+ at concentrations of 50-150µM promotes the colonization of E. coli, and Fe2+ concentrations of 50-200µM promote the growth of E. faecalis and dual-species colonies. Atomic absorption spectroscopy results reveal that Fe2+ ion augmentation in bacterial cells was increased to 4 folds in the single-species model and 11 folds in the dual-species model under iron-supplemented conditions. Furthermore, Fe2+ augmentation increased the antibiotic resistance of E. faecalis in both single- and dual-species bacterial cultures. In addition, in-silico docking were performed to determine a three-dimensional (3D) structure of ferrous iron-transporter proteins FeoB of E. faecalis and its affinity to extracellular Fe2+. Our model suggests that the FeoB facilitates the Fe2+ uptake in E. faecalis cells in the absence of iron chelator, 2,2-bipyridyl.