Assessment of the safety and probiotic properties of Roseburia intestinalis: A potential “Next Generation Probiotic”

Novel insights into carbohydrate utilisation, antimicrobial resistance, and sporulation potential in Roseburia intestinalis isolates across diverse geographical locations

Roseburia intestinalis is one of the most abundant and important butyrate-producing human gut anaerobic bacteria that plays an important role in maintaining health and is a potential next-generation probiotic. We investigated the pangenome of 16 distinct strains, isolated over several decades, identifying local and time-specific adaptations. More than 50% of the genes in each individual strain were assigned to the core genome, and 77% of the cloud genes were unique to individual strains, revealing the high level of genome conservation. Co-carriage of the same enzymes involved in carbohydrate binding and degradation in all strains highlighted major pathways in carbohydrate utilization and reveal the importance of xylan, starch and mannose as key growth substrates. A single strain had adapted to use rhamnose as a sole growth substrate, the first time this has been reported. The ubiquitous presence of motility and sporulation gene clusters demonstrates the importance of these phenotypes for gut survival and acquisition of this bacterium. More than half the strains contained functional, potentially transferable, tetracycline resistance genes. This study advances our understanding of the importance of R. intestinalis within the gut ecosystem by elucidating conserved metabolic characteristics among different strains, isolated from different locations. This information will help to devise dietary strategies to increase the abundance of this species providing health benefits.

Impact of Gut Microbiota and Probiotics on Rheumatoid Arthritis: A Potential Treatment Challenge

Over the past few decades, there has been a surge in global study on the relationship between gut microbiota and human health. Numerous human illnesses have been linked to dysbiosis. Gram-positive firmicutes and Gram-negative bacteroidetes are the two leading bacterial phyla that make up 90% of the gut microbiome. Many symbionts in the gut environment establish intricate relationships with host defense to stop both local and non-native dangerous bacteria from colonizing and invading. Dysbiosis alters the paracellular route and damages the epithelium, enabling them to penetrate the epithelium and come into contact with the immune cells. Impaired intestinal barrier function, immune regulation mediated by metabolites derived from the gut microbiota, posttranslational modification of host proteins such as increased citrullination, regulation of the gut microbiota's effect on immune cells, intestinal epithelial cell autophagy, interaction between the microbiome and human leukocyte antigen alleles, and interaction with microRNAs are some of the mechanisms involved in rheumatoid arthritis (RA). The gut microbiota, Prevotella copri, and Collinsella spp. were shown to be higher in the early/preclinical phases of RA, while Bacteroidetes, Bifidobacteria, and Eubacterium rectale were found to be lower. Probiotic-based early dietary intervention may reduce inflammation and slow the rate of joint deterioration, and such intervention can also aid in the restoration of gut microbiota equilibrium. This review article describes the gut microbial dysbiosis and role of probiotics in RA.

Anti-Inflammatory Effects of Weissella cibaria SDS2.1 Against Klebsiella pneumoniae-Induced Mammary Gland Inflammation

Dairy cows are highly susceptible to mastitis caused by Klebsiella pneumoniae, and treating these infections poses a challenge due to the resistance of the bacterium to common antibiotics. This study aimed to evaluate the safety of W. cibaria SDS2.1 and investigate its protective effects against K. pneumoniae-induced mastitis. The safety of W. cibaria SDS2.1 was assessed through comprehensive analyses, including antibiotic resistance profiling, hemolysis assays, cell cytotoxicity tests, and whole-genome sequencing. Furthermore, its ability to protect against cellular and tissue damage caused by K. pneumoniae-induced mastitis was evaluated using both in vitro and in vivo models. Our results revealed that W. cibaria SDS2.1 was non-hemolytic, non-cytotoxic, and significantly inhibited the growth of K. pneumoniae (p < 0.05). Additionally, W. cibaria SDS2.1 effectively reduced the adhesion and invasion of K. pneumoniae. In the K. pneumoniae-induced mouse mastitis model, W. cibaria SDS2.1 significantly reduced myeloperoxidase (MPO) activity, mammary tissue damage, and the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) (p < 0.05). In K. pneumoniae-infected bovine mammary epithelial cells (bMECs), W. cibaria SDS2.1 significantly decreased lactate dehydrogenase (LDH) release, indicating reduced cellular damage. These findings demonstrate that W. cibaria SDS2.1 exhibits anti-inflammatory properties in experimental models, suggesting its potential role in mitigating K. pneumoniae-induced mastitis.

Preclinical Safety Assessment of the Oral Administration of Lactobacillus plantarum GUANKE in Animal Models

Probiotics have a long history as fermented food or food supplements. The health benefits and safety profiles of probiotics are strain-specific and should be evaluated individually. The aim of this study was to assess the safety of the Lactobacillus plantarum GUANKE (GUANKE) strain by conducting pharmacological studies, oral toxicity assessments, and investigating the colonization and translocation of GUANKE in experimental animal models. Three pharmacological studies were conducted to examine the effects of oral administration of GUANKE on gastric emptying, bile secretion, and gastric juice secretion. In an acute toxicity study, rats were orally administrated with different doses of GUANKE and monitored for 14 days. In the subacute toxicity study, both rats and beagles were administrated with varying doses of GUANKE for 28 consecutive days to evaluate hematologic, biochemical, and histological effects. The results showed that GUANKE administration did not result in any adverse effect on hematological parameters, biochemical parameters, urinary parameters, and organ indices. Importantly, no translocation of GUANKE to extra-intestinal organs or blood was observed following administration of the CFDA-SE labeled strain. In summary, this study demonstrated the safety of GUANKE intake, which encourages its potential application as a probiotic in clinical trials.

Roseburia intestinalis: A possible target for vascular calcification

With the advancement of metagenomics and metabolomics techniques, the crucial role of the gut microbiome in intestinal, cardiovascular, and metabolic disorders has been extensively explored. Vascular calcification (VC) is common in atherosclerosis, hypertension, diabetes mellitus, and chronic kidney disease. Moreover, it is a significant cause of cardiovascular diseases and mortality. Roseburia intestinalis, as a promising candidate for the next generation of probiotics, plays a substantial role in inhibiting the systemic inflammatory response and holds great potential in the treatment of intestinal diseases, cardiovascular diseases, and metabolic disorders. Its primary metabolite, butyrate, acts on specific receptors (GPR43, GPR41, GPR109a). It enters cells via transporters (MCT1, SMCT1), affecting gene expression through HDACs, PPARγ and Nrf2, promoting energy metabolism and changing the concentration of other metabolites (including AGEs, LPS, BHB) in the circulation to affect the body's life activities. In this paper, we focus on the possible mechanism of the primary metabolite butyrate of Roseburia intestinalis in inhibiting VC, which may become a potential therapeutic target for the treatment of VC and the ways to enhance its effect.

Probiotic and Postbiotic Potentials of Enterococcus faecalis EF-2001: A Safety Assessment

BACKGROUND

Probiotics, which are live microorganisms that, when given in sufficient quantities, promote the host's health, have drawn a lot of interest for their ability to enhance gut health. Enterococcus faecalis, a member of the human gut microbiota, has shown promise as a probiotic candidate due to its functional attributes. However, safety concerns associated with certain strains warrant comprehensive evaluation before therapeutic application.

MATERIALS AND METHODS

In this study, E. faecalis EF-2001, originally isolated from fecal samples of a healthy human infant, was subjected to a multi-faceted assessment for its safety and probiotic potential. In silico analysis, CAZyme, biosynthetic, and stress-responsive proteins were identified.

RESULTS

The genome lacked biogenic amine genes but contained some essential amino acid and vitamin synthetic genes, and carbohydrate-related enzymes essential for probiotic properties. The negligible difference of 0.03% between the 1st and 25th generations indicates that the genetic information of the E. faecalis EF-2001 genome remained stable. The live E. faecalis EF-2001 (E. faecalis EF-2001L) demonstrated low or no virulence potential, minimal D-Lactate production, and susceptibility to most antibiotics except some aminoglycosides. No bile salt deconjugation or biogenic amine production was observed in an in vitro assay. Hemolytic activity assessment showed a β-hemolytic pattern, indicating no red blood cell lysis. Furthermore, the EF-2001L did not produce gelatinase and tolerated simulated gastric and intestinal fluids in an in vitro study. Similarly, heat-killed E. faecalis EF-2001 (E. faecalis EF-2001HK) exhibits tolerance in both acid and base conditions in vitro. Further, no cytotoxicity of postbiotic EF-2001HK was observed in human colorectal adenocarcinoma HT-29 cells.

CONCLUSIONS

These potential properties suggest that probiotic and postbiotic E. faecalis EF-2001 could be considered safe and retain metabolic activity suitable for human consumption.

Gut microbiome and metabolome signatures in liver cirrhosis-related complications

BACKGROUND/AIMS

Shifts in the gut microbiota and metabolites are interrelated with liver cirrhosis progression and complications. However, causal relationships have not been evaluated comprehensively. Here, we identified complication-dependent gut microbiota and metabolic signatures in patients with liver cirrhosis.

METHODS

Microbiome taxonomic profiling was performed on 194 stool samples (52 controls and 142 cirrhosis patients) via V3-V4 16S rRNA sequencing. Next, 51 samples (17 controls and 34 cirrhosis patients) were selected for fecal metabolite profiling via gas chromatography mass spectrometry and liquid chromatography coupled to time-of-flight mass spectrometry. Correlation analyses were performed targeting the gut-microbiota, metabolites, clinical parameters, and presence of complications (varices, ascites, peritonitis, encephalopathy, hepatorenal syndrome, hepatocellular carcinoma, and deceased).

RESULTS

Veillonella bacteria, Ruminococcus gnavus, and Streptococcus pneumoniae are cirrhosis-related microbiotas compared with control group. Bacteroides ovatus, Clostridium symbiosum, Emergencia timonensis, Fusobacterium varium, and Hungatella_uc were associated with complications in the cirrhosis group. The areas under the receiver operating characteristic curve (AUROCs) for the diagnosis of cirrhosis, encephalopathy, hepatorenal syndrome, and deceased were 0.863, 0.733, 0.71, and 0.69, respectively. The AUROCs of mixed microbial species for the diagnosis of cirrhosis and complication were 0.808 and 0.847, respectively. According to the metabolic profile, 5 increased fecal metabolites in patients with cirrhosis were biomarkers (AUROC >0.880) for the diagnosis of cirrhosis and complications. Clinical markers were significantly correlated with the gut microbiota and metabolites.

CONCLUSION

Cirrhosis-dependent gut microbiota and metabolites present unique signatures that can be used as noninvasive biomarkers for the diagnosis of cirrhosis and its complications.

Microbially-produced folate forms support the growth of Roseburia intestinalis but not its competitive fitness in fecal batch fermentations

BACKGROUND

Folate (vitamin B9) occurs naturally mainly as tetrahydrofolate (THF), methyl-tetrahydrofolate (M-THF), and formyl-tetrahydrofolate (F-THF), and as dietary synthetic form (folic acid). While folate auxotrophy and prototrophy are known for several gut microbes, the specific folate forms produced by gut prototrophs and their impact on gut auxotrophs and microbiota remain unexplored.

METHODS

Here, we quantified by UHPLC-FL/UV folate produced by six predicted gut prototrophs (Marvinbryantia formatexigens DSM 14469, Blautia hydrogenotrophica 10507 T, Blautia producta DSM 14466, Bacteroides caccae DSM 19024, Bacteroides ovatus DSM 1896, and Bacteroides thetaiotaomicron DSM 2079 T) and investigated the impact of different folate forms and doses (50 and 200 µg/l) on the growth and metabolism of the gut auxotroph Roseburia intestinalis in pure cultures and during fecal anaerobic batch fermentations (48 h, 37 °C) of five healthy adults.

RESULTS

Our results confirmed the production of folate by all six gut strains, in the range from 15.3 ng/ml to 205.4 ng/ml. Different folate forms were detected, with THF ranging from 12.8 to 41.4 ng/ml and 5-MTHF ranging from 0.2 to 113.3 ng/ml, and being detected in all strains. Natural folate forms, in contrast to folic acid, promoted the growth and metabolism of the auxotroph R. intestinalis L1-82, with dose-dependent effects. During fecal batch fermentations, folate forms at both levels had no detectable effect on total bacteria concentration, on gut community composition and metabolic activity and on Roseburia spp. abundance, compared to the control without folate addition.

CONCLUSIONS

Our study demonstrates for the first time in vitro the production of different natural folate forms by predicted gut prototrophs and the stimulation on the growth of the folate auxotrophic butyrate-producing R. intestinalis L1-82. Surprisingly, folate did not impact fecal fermentations. Our data suggest that the dietary folate forms at the tested levels may only have limited effects, if any, on the human gut microbiota in vivo.

Correlation between intestinal flora and GLP-1 receptor agonist dulaglutide in type 2 diabetes mellitus treatment-A preliminary longitudinal study

GLP-1 receptor agonists (GLP-1 RA) are presently used as the first-line drugs for the clinical treatment of type 2 diabetes mellitus (T2DM). It can regulate blood glucose by stimulating insulin secretion and lowering glucagon levels. We used 16S rRNA amplicon sequencing to detect structural changes in the composition of the intestinal flora of newly diagnosed T2DM after 1 and 48 weeks of dulaglutide administration. Our research found no significant changes in the intestinal flora after the administration of dulaglutide for 1 week to subjects with newly diagnosed T2DM. Nevertheless, after 48 weeks of dulaglutide administration, the composition of the intestinal flora changed significantly, with a significant reduction in the abundance of intestinal flora. Furthermore, we found that fasting glucose levels, fasting c-peptide levels, HbA1c levels, and BMI are also closely associated with intestinal flora. This reveals that intestinal flora may be one of the mechanisms by which dulaglutide treats T2DM.

Assessment of the Safety and Probiotic Properties of Enterococcus faecium B13 Isolated from Fermented Chili

Enterococcus faecium B13, selected from fermentation chili, has been proven to promote animal growth by previous studies, but it belongs to opportunistic pathogens, so a comprehensive evaluation of its probiotic properties and safety is necessary. In this study, the probiotic properties and safety of B13 were evaluated at the genetic and phenotype levels in vitro and then confirmed in vivo. The genome of B13 contains one chromosome and two plasmids. The average nucleotide identity indicated that B13 was most closely related to the fermentation-plant-derived strain. The strain does not carry the major virulence genes of the clinical E. faecium strains but contains aac(6')-Ii, ant (6)-Ia, msrC genes. The strain had a higher tolerance to acid at pH 3.0, 4.0, and 0.3% bile salt and a 32.83% free radical DPPH clearance rate. It can adhere to Caco-2 cells and reduce the adhesion of E. coli to Caco-2 cells. The safety assessment revealed that the strain showed no hemolysis and did not exhibit gelatinase, ornithine decarboxylase, lysine decarboxylase, or tryptophanase activity. It was sensitive to twelve antibiotics but was resistant to erythromycin, rifampicin, tetracycline, doxycycline, and minocycline. Experiments in vivo have shown that B13 can be located in the ileum and colon and has no adverse effects on experiment animals. After 28 days of feeding, B13 did not remarkable change the α-diversity of the gut flora or increase the virulence genes. Our study demonstrated that E. faecium B13 may be used as a probiotic candidate.

Microbiome and Abdominopelvic Radiotherapy Related Chronic Enteritis: A Microbiome-based Mechanistic Role of Probiotics and Antibiotics

Chronic diarrhea and abdominal pain after radiotherapy continue to be a problem in cancer survivors. Gut microbiomes are essential for preventing intestinal inflammation, maintaining intestinal integrity, maintaining enterohepatic circulation, regulating bile acid metabolism, and absorption of nutrients, including fat-soluble vitamins. Gut microbiome dysbiosis is expected to cause inflammation, bile acid malabsorption, malnutrition, and associated symptoms. Postradiotherapy, Firmicutes and Bacteroidetes phylum are significantly decreased while Fusobacteria and other unclassified bacteria are increased. Available evidence suggests harmful bacteria Veillonella, Erysipelotrichaceae, and Ruminococcus are sensitive to Metronidazole or Ciprofloxacin. Beneficial bacteria lactobacillus and Bifidobacterium are relatively resistant to metronidazole. We hypothesize and provide an evidence-based review that short-course targeted antibiotics followed by specific probiotics may lead to alleviation of radiation enteritis.

Christensenella minuta, a new candidate next-generation probiotic: current evidence and future trajectories

Background

As the field of probiotic research continues to expand, new beneficial strains are being discovered. The Christensenellaceae family and its newly described member, Christensenella minuta, have been shown to offer great health benefits. We aimed to extensively review the existing literature on these microorganisms to highlight the advantages of their use as probiotics and address some of the most challenging aspects of their commercial production and potential solutions.

Methods

We applied a simple search algorithm using the key words "Christensenellaceae" and "Christensenella minuta" to find all articles reporting the biotherapeutic effects of these microorganisms. Only articles reporting evidence-based results were reviewed.

Results

The review showed that Christensenella minuta has demonstrated numerous beneficial properties and a wider range of uses than previously thought. Moreover, it has been shown to be oxygen-tolerant, which is an immense advantage in the manufacturing and production of Christensenella minuta-based biotherapeutics. The results suggest that Christensenellaceae and Christensenella munita specifically can play a crucial role in maintaining a healthy gut microbiome. Furthermore, Christensenellaceae have been associated with weight management. Preliminary studies suggest that this probiotic strain could have a positive impact on metabolic disorders like diabetes and obesity, as well as inflammatory bowel disease.

Conclusion

Christensenellaceae and Christensenella munita specifically offer immense health benefits and could be used in the management and therapy of a wide range of health conditions. In addition to the impressive biotherapeutic effect, Christensenella munita is oxygen-tolerant, which facilitates commercial production and storage.

Acetolactate Decarboxylase as an Important Regulator of Intracellular Acidification, Morphological Features, and Antagonism Properties in the Probiotic Lactobacillus reuteri

SCORE

This study identifies the coding gene (aldB) of acetolactate decarboxylase (ALDC) as an important regulatory gene of the intracellular pH in Lactobacillus reuteri (L. reuteri), uncovering the important role of ALDC in regulating intracellular pH, morphological features, and antagonism properties in the probiotic organism L. reuteri.

METHODS AND RESULTS

The aldB mutant (ΔaldB) of L. reuteri is established using the homologous recombination method. Compare to the wild-type (WT) strain, the ΔaldB strain shows a smaller body size, grows more slowly, and contains more acid in the cell cytoplasm. The survival rate of the ΔaldB strain is much lower in low pH and simulated gastric fluid (SGF) than that of the WT strain, but higher in simulated intestinal fluid (SIF). The antagonism test demonstrates the ΔaldB strain can inhibit Listeria monocytogenes (L. monocytogenes) and Salmonella more effectively than the WT strain. Additionally, there is a dramatic decrease in the adhesion rate of Salmonella to Caco-2 and HT-29 cells in the presence of the ΔaldB strain compared to the WT strain. Simultaneously analyze, the auto-aggregation, co-aggregation, cell surface hydrophobicity (CSH), hemolytic, temperature, NaCl, oxidative stress, and antibiotic susceptibility of the ΔaldB strain are consistent with the features of probiotics.

CONCLUSION

This study highlights that the aldB gene plays a significant role in the growth and antibacterial properties of L. reuteri.

Multiomics analysis reveals the biological effects of live Roseburia intestinalis as a high-butyrate-producing bacterium in human intestinal epithelial cells

Butyrate-producing bacteria play a key role in human health, and recent studies have triggered interest in their development as next-generation probiotics. However, there remains limited knowledge not only on the identification of high-butyrate-producing bacteria in the human gut but also in the metabolic capacities for prebiotic carbohydrates and their interaction with the host. Herein, it was discovered that Roseburia intestinalis produces higher levels of butyrate and digests a wider variety of prebiotic polysaccharide structures compared with other human major butyrate-producing bacteria (Eubacterium rectale, Faecalibacterium prausnitzii, and Roseburia hominis). Moreover, R. intestinalis extracts upregulated the mRNA expression of tight junction proteins (TJP1, OCLN, and CLDN3) in human intestinal epithelial cells more than other butyrate-producing bacteria. R. intestinalis was cultured with human intestinal epithelial cells in the mimetic intestinal host-microbe interaction coculture system to explore the health-promoting effects using multiomics approaches. Consequently, it was discovered that live R. intestinalis only enhances purine metabolism and the oxidative pathway, increasing adenosine triphosphate levels in human intestinal epithelial cells, but that heat-killed bacteria had no effect. Therefore, this study proposes that R. intestinalis has potentially high value as a next-generation probiotic to promote host intestinal health.

Phage-microbe dynamics after sterile faecal filtrate transplantation in individuals with metabolic syndrome: a double-blind, randomised, placebo-controlled clinical trial assessing efficacy and safety

Bacteriophages (phages) are bacterial viruses that have been shown to shape microbial communities. Previous studies have shown that faecal virome transplantation can decrease weight gain and normalize blood glucose tolerance in diet-induced obese mice. Therefore, we performed a double-blind, randomised, placebo-controlled pilot study in which 24 individuals with metabolic syndrome were randomised to a faecal filtrate transplantation (FFT) from a lean healthy donor (n = 12) or placebo (n = 12). The primary outcome, change in glucose metabolism, and secondary outcomes, safety and longitudinal changes within the intestinal bacteriome and phageome, were assessed from baseline up to 28 days. All 24 included subjects completed the study and are included in the analyses. While the overall changes in glucose metabolism are not significantly different between both groups, the FFT is well-tolerated and without any serious adverse events. The phage virion composition is significantly altered two days after FFT as compared to placebo, which coincides with more virulent phage-microbe interactions. In conclusion, we provide evidence that gut phages can be safely administered to transiently alter the gut microbiota of recipients.

Impact of dietary interventions on pre-diabetic oral and gut microbiome, metabolites and cytokines

Diabetes and associated comorbidities are a global health threat on the rise. We conducted a six-month dietary intervention in pre-diabetic individuals (NCT03222791), to mitigate the hyperglycemia and enhance metabolic health. The current work explores early diabetes markers in the 200 individuals who completed the trial. We find 166 of 2,803 measured features, including oral and gut microbial species and pathways, serum metabolites and cytokines, show significant change in response to a personalized postprandial glucose-targeting diet or the standard of care Mediterranean diet. These changes include established markers of hyperglycemia as well as novel features that can now be investigated as potential therapeutic targets. Our results indicate the microbiome mediates the effect of diet on glycemic, metabolic and immune measurements, with gut microbiome compositional change explaining 12.25% of serum metabolites variance. Although the gut microbiome displays greater compositional changes compared to the oral microbiome, the oral microbiome demonstrates more changes at the genetic level, with trends dependent on environmental richness and species prevalence in the population. In conclusion, our study shows dietary interventions can affect the microbiome, cardiometabolic profile and immune response of the host, and that these factors are well associated with each other, and can be harnessed for new therapeutic modalities.

Beneficial Bacteria Isolated from Food in Relation to the Next Generation of Probiotics

Recently, probiotics are increasingly being used for human health. So far, only lactic acid bacteria isolated from the human gastrointestinal tract were recommended for human use as probiotics. However, more authors suggest that probiotics can be also isolated from unconventional sources, such as fermented food products of animal and plant origin. Traditional fermented products are a rich source of microorganisms, some of which may have probiotic properties. A novel category of recently isolated microorganisms with great potential of health benefits are next-generation probiotics (NGPs). In this review, general information of some "beneficial microbes", including NGPs and acetic acid bacteria, were presented as well as essential mechanisms and microbe host interactions. Many reports showed that NGP selected strains and probiotics from unconventional sources exhibit positive properties when it comes to human health (i.e., they have a positive effect on metabolic, human gastrointestinal, neurological, cardiovascular, and immune system diseases). Here we also briefly present the current regulatory framework and requirements that should be followed to introduce new microorganisms for human use. The term "probiotic" as used herein is not limited to conventional probiotics. Innovation will undoubtedly result in the isolation of potential probiotics from new sources with fascinating new health advantages and hitherto unforeseen functionalities.

Genetic and Probiotic Characteristics of Urolithin A Producing Enterococcus faecium FUA027

Enterococcus faecium FUA027 transforms ellagic acid (EA) to urolithin A (UA), which makes it a potential application in the preparation of UA by industrial fermentation. Here, the genetic and probiotic characteristics of E. faecium FUA027 were evaluated through whole-genome sequence analysis and phenotypic assays. The chromosome size of this strain was 2,718,096 bp, with a GC content of 38.27%. The whole-genome analysis revealed that the genome contained 18 antibiotic resistance genes and seven putative virulence factor genes. E. faecium FUA027 does not contain plasmids and mobile genetic elements (MGEs), and so the transmissibility of antibiotic resistance genes or putative virulence factors should not occur. Phenotypic testing further indicated that E. faecium FUA027 is sensitive to clinically relevant antibiotics. In addition, this bacterium exhibited no hemolytic activity, no biogenic amine production, and could significantly inhibit the growth of the quality control strain. In vitro viability was >60% in all simulated gastrointestinal environments, with good antioxidant activity. The study results suggest that E. faecium FUA027 has the potential to be used in industrial fermentation for the production of urolithin A.

Gut microbiota-derived short-chain fatty acids regulate gastrointestinal tumor immunity: a novel therapeutic strategy?

Tumor immune microenvironment (TIME), a tumor-derived immune component, is proven to be closely related to the development, metastasis, and recurrence of tumors. Gut microbiota and its fermented-metabolites short-chain fatty acids (SCFAs) play a critical role in maintaining the immune homeostasis of gastrointestinal tumors. Consisting mainly of acetate, propionate, and butyrate, SCFAs can interact with G protein-coupled receptors 43 of T helper 1 cell or restrain histone deacetylases (HDACs) of cytotoxic T lymphocytes to exert immunotherapy effects. Studies have shed light on SCFAs can mediate the differentiation and function of regulatory T cells, as well as cytokine production in TIME. Additionally, SCFAs can alter epigenetic modification of CD8⁺ T cells by inhibiting HDACs to participate in the immune response process. In gastrointestinal tumors, the abundance of SCFAs and their producing bacteria is significantly reduced. Direct supplementation of dietary fiber and probiotics, or fecal microbiota transplantation to change the structure of gut microbiota can both increase the level of SCFAs and inhibit tumor development. The mechanism by which SCFAs modulate the progression of gastrointestinal tumors has been elucidated in this review, aiming to provide prospects for the development of novel immunotherapeutic strategies.