Comparative genomic analysis of Lactobacillus rhamnosus GG reveals pili containing a human- mucus binding protein. Proc Natl Acad Sci U S A. 2009;106:17193-17198. [PMID: 19805152 DOI: 10.1073/pnas.0908876106]

Advanced microbiome therapeutics for oral delivery of peptides and proteins: Advances, challenges, and opportunities

Peptide and protein medicines have changed the therapeutic landscape for many diseases, yet oral delivery remains a significant challenge due to enzymatic degradation, instability, and poor permeability in the gastrointestinal tract. Advanced Microbiome Therapeutics (AMTs) could overcome some of these barriers by producing and releasing therapeutic peptides directly in the gastrointestinal tract. AMTs can localize peptide production at the site of absorption, providing either sustained or controlled release while potentially reducing side effects associated with systemic administration. Here, this review assesses the status of AMTs for oral peptide delivery and discusses the potential integration of enzyme inhibitors, permeation enhancers, and mucoadhesive to improve oral bioavailability further. Combining these approaches could pave the way for more widespread oral delivery strategies for peptide and protein medicines.

Effect of direct arginine supplementation on growth of Lacticaseibacillus rhamnosus GG

OBJECTIVES

The study aimed to examine the effect of direct arginine (Arg) supplementation on Lacticaseibacillus rhamnosus GG (LRG) growth.

METHODS

The probiotic LRG ATCC 53103 was routinely cultured in MRS broth and adjusted to 107 CFU/ml. l-Arg at 0.25 % and 0.5 % w/v. was directly supplemented to MRS broth containing LRG. Then, LRG with/without supplemented Arg was characterised to determine growth curves for 72 h under a CO2-driven, environment-controlled spectrophotometer. Whereas, end-point McFarland spectrophotometric, metabolic assays (XTT and WST-8), colony forming units (CFU) assessment, live/dead bacterial confocal imaging, and viable DNA quantification were undertaken after 24 h CO2 incubation to determine LRG growth with/without supplemented Arg.

RESULTS

Growth curve analysis revealed similar absorbance profiles with LRG and LRG+0.25 % Arg with no overlaps to LRG+0.5 % Arg; with a similar trend observed as per end-point McFarland spectrophotometric assessment. The % viability estimated by metabolic assays with LRG and LRG+0.25 % Arg was significantly lower than LRG+0.5 % Arg (p < 0.05). As per CFU assessment, CFU/ml for LRG+0.25 % Arg and LRG+0.5 % Arg was significantly higher than LRG control (p < 0.05). LRG live-dead proportions determined using confocal imaging denote no differences between the groups (p > 0.05), with live cell proportions significantly higher than the dead cells (p < 0.05). However, LRG cellular density appeared to increase with increasing concentrations of Arg. Additionally, the viable cells quantified with PMA-qPCR significantly increased with increasing concentrations of Arg (p < 0.05).

CONCLUSION

Direct supplementation of 0.5 % Arg to LRG enhances LRG growth, demonstrating a promising synbiotic potential. CLINICAL SIGNIFICANCE (48 WORDS): Primary caries prevention is initiated at biofilms using biotic strategies that modulate the microbiome matrix to maintain ecological homeostasis. The results of the present study establish a deliverable synbiotic of Arg and probiotic Lacticaseibacillus rhamnosus GG, demonstrating a promising synergism between interventions in the milieu targeted for high caries-risk individuals.

Effects of Oral Administration of the Probiotic Lactobacillus rhamnosus GG on the Proteomic Profiles of Cerebrospinal Fluid and Immunoregulatory Signaling in the Hippocampus of Adult Male Rats

INTRODUCTION

The microbiome-gut-brain axis, by modulating bidirectional immune, metabolic, and neural signaling pathways in the host, has emerged as a target for the prevention and treatment of psychiatric and neurological disorders. Oral administration of the probiotic bacterium Lactobacillus rhamnosus GG (LGG; ATCC 53103) exhibits anti-inflammatory effects, although the precise mechanisms by which LGG benefits host physiology and behavior are not known. The goal of this study was to explore the general effects of LGG on the cerebrospinal fluid (CSF) proteome and a biological signature of anti-inflammatory signaling in the central nervous system (CNS) of undisturbed, adult male rats.

METHODS

Liquid chromatography-tandem mass spectrometry-based proteomics were conducted using CSF samples collected after 21 days of oral treatment with live LGG (3.34 × 107 colony-forming units (CFU)/mL in the drinking water (resulting in an estimated delivery of ∼1.17 × 109 CFU/day/rat) or water vehicle. Gene enrichment analysis (using DAVID, v. 6.8) and protein-protein interactions (using STRING, v. 11) were used to explore physiological network changes in CSF. Real-time reverse transcription polymerase chain reaction (real-time RT-PCR) was performed to assess gene expression changes of anti-inflammatory cytokines in the hippocampus. Genes associated with anti-inflammatory signaling that were analyzed included Il10, Tgfb1, Il4, and IL-4-responsive genes, Cd200, Cd200r1, and Mrc1 (Cd206).

RESULTS

Oral LGG administration altered the abundance of CSF proteins, increasing the abundance of five proteins (cochlin, NPTXR, reelin, Sez6l, and VPS13C) and decreasing the abundance of two proteins (CPQ, IGFBP-7) in the CSF. Simultaneously, LGG increased the expression of Il10 mRNA, encoding the anti-inflammatory cytokine interleukin 10, in the hippocampus.

CONCLUSION

Oral LGG altered the abundance of CSF proteins associated with extracellular scaffolding, synaptic plasticity, and glutamatergic signaling. These data are consistent with the hypothesis that oral administration of LGG improves memory and cognition, and promotes a physiological resilience to neurodegenerative disease, by increasing glutamatergic signaling and promoting an anti-inflammatory environment in the brain.

Unlocking Probiotic Potential: Physicochemical Approaches to Evaluate Probiotic Bacterial Adhesion Potential to the Intestinal Tract

Bacterial adhesion in the gut is critical to evaluate their effectiveness as probiotics. Understanding the bacterial adhesion within the complex gut environment is challenging. This study explores the adhesion mechanisms and the adhesion potential of five selected bacterial strains (Escherichia coli, Lactiplantibacillus plantarum, Faecalibacterium duncaniae, Bifidobacterium longum, and Bifidobacterium longum subsp. infantis) at the initial stages when bacterial cells arriving in the gut, using different physicochemical approaches. Bacterial morphology, rheology, and surface properties were evaluated. Surprisingly, previous methods such as bacterial adhesion to hydrocarbon and the interfacial tension between bacterial suspensions and mineral oil did not fully capture the bacterial adhesion to intestinal mucus. Consequently, this study introduced a novel approach to assess bacterial adhesion to mucus, based on contact angle measurements, calculation of surface tension, and work of adhesion. Interestingly, both small and large intestinal mucus are rather hydrophilic, and thus highly hydrophilic bacteria such as E. coli and B. infantis tend to adhere better. Additionally, a multicriteria evaluation of bacterial adhesion to the gut, from the bulk liquid transport stage until the irreversible adhesion, was proposed. E. coli and B. infantis demonstrated the highest overall adhesion potential in the intestinal tract, followed by Lpb. plantarum, B. longum, and F. duncaniae, respectively. This work contributed original physicochemical approaches to comprehensively examine bacterial adhesion in the gut.

Probiotic Bacterium-Derived p40, p75, and HM0539 Proteins as Novel Postbiotics and Gut-Associated Immune System (GAIS) Modulation: Postbiotic-Gut-Health Axis

It is known that probiotics have direct and indirect effects on many systems in the body, especially the gastrointestinal system. Interest in using probiotic strain-derived cell components and metabolites has also increased as a result of the significant benefits of probiotics. Although many terminologies and definitions are used for these components and metabolites, the International Scientific Association of Probiotics and Prebiotics (ISAPP) recommended the use of the term postbiotic in 2021, which is defined as "a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host". Postbiotics are bioactive metabolites such as organic acids, peptides/proteins, cell wall components, functional enzymes, short-chain fatty acids, vitamins, and phenols. These molecules mediate many positive effects such as immunomodulatory, antimicrobial, and antioxidant effects. These positive effects on maintaining health have enabled the identification of many new postbiotic proteins such as p40, p75, and HM0539. In this review, the postbiotic proteins p40, p75, and HM0539 derived from lactobacilli and their functional effects are systematically summarized. The p40 protein, in particular, has been shown to support gut barrier activity and reduce inflammation, potentially through mechanisms involving epidermal growth factor receptor-dependent signaling. Additionally, p40 and p75 proteins exhibit protective effects on intestinal epithelial tight junctions, suggesting their therapeutic potential in preventing intestinal damage and diseases such as colitis. HM0539 enhances intestinal barrier integrity, exhibits antiinflammatory properties, and protects against bacterial infection, suggesting its possible as a therapeutic for inflammatory bowel disease. This review may contribute to future studies on the therapeutic use of p40, p75, and HM0539 postbiotic proteins in inflammatory gastrointestinal system diseases.

Adhesion Properties and Pathogen Inhibition of Vaginal-Derived Lactobacilli

In the present study, twenty-seven (27) lactobacilli strains, isolated from the vagina of healthy Italian women of reproductive age, were screened for probiotic properties. The strains were evaluated for antagonistic activity against pathogens, adhesion abilities, and potential to displace and/or inhibit the adhesion of previously adhered pathogens as a primary strain selection criterion. Overall, all the tested lactobacilli inhibited at least three pathogens, and the majority of them exhibited antimicrobial activity against Enterobacter cloacae DSM 30054, Pseudomonas aeruginosa DSM 3227, and Pseudomonas aeruginosa DSM 1117. The complete neutralization of antimicrobial activity after cell-free supernatant (CFS) neutralization suggested a pivotal role for lactic acid or other organic acids secreted by the lactobacilli. The strains showed variability in their adhesion levels, but all tested strains adhered to both human colonic epithelial cells (HT-29) and vaginal cells (VK2/E6E7) with adhesion percentages exceeding 1%. The ability to displace or inhibit pathogens was dependent on the pathogen and the lactobacilli strain; the pathogen displacement levels ranged from 9 to 82%, while pathogen exclusion levels varied from 1 to 99%. In conclusion, this study demonstrates the protective effect of vaginal lactobacilli against pathogens and confirms the suitability of the vaginal microbiota as a source of potential probiotic strains. The selected lactobacilli hold promise for the formulation of supplements to enhance genitourinary tract health.

Wood hemicelluloses as protective materials for preserving the viability of probiotic Lacticaseibacillus rhamnosus GG during spray drying

Wood hemicelluloses from forest industry side-streams are promising economic and sustainable alternatives for encapsulating bioactive compounds. This study explores their suitability for probiotic encapsulation, specifically for maintaining cell viability and structure. The ability of galactoglucomannans (GGM) and glucuronoxylans (GX) to support the survival of Lacticaseibacillus rhamnosus GG (LGG) during spray drying at solid feed concentrations of 15 and 20 % and inlet air temperatures of 105 and 140 °C (outlet air temperature of 50 °C) was investigated and compared to the results obtained using maltodextrin (MD). Across all investigated conditions, LGG survival rates exceeded 85 % (>107 cfu/g) in GX and GGM microcapsule powders, which similar to that in MD microcapsules despite the differences in pH, particle size, and viscosity of their feed dispersions. The GX microcapsules demonstrated the highest process yield (50-58 %), followed by MD (39-51 %). All the microcapsule powders exhibited an amorphous structure consisting of spherical particles with an average diameter of 10 μm, sufficient for LGG accommodation. Atomic force microscopy analysis confirmed the encapsulation of LGG cells within microcapsules with intact rod-shaped chains post-spray drying. Overall, the spray-dried microencapsulation of probiotics using wood hemicelluloses maintains high probiotic viability and offers an eco-friendly, cost-effective alternative to traditional materials.

Lactobacillus rhamnosus modulates murine neonatal gut microbiota and inflammation caused by pathogenic Escherichia coli

BACKGROUND

Pathogenic Escherichia coli strains produce neonatal septicemia after colonizing the neonatal gut. While the probiotic Lactobacillus rhamnosus GG (LGG) effectively reduces neonatal sepsis, LGG's effects on the neonatal intestinal microbiota alterations and inflammation triggered by E. coli are incompletely understood. We hypothesized that LGG significantly modulates the specific neonatal gut microbial populations changes and the inflammatory response elicited by the enteral introduction of septicemia-producing E. coli. To test this hypothesis, newborn rats were pretreated orally with LGG or placebo prior to infection with the neonatal E. coli septicemia clinical isolate SCB34. Amplicon 16S rRNA gene sequencing was performed on intestinal samples. Intestinal injury and expression of inflammatory mediators and apoptosis were determined.

RESULTS

Alpha diversity of gut microbiota was greater in SCB34-infected pups in comparison to sham-infected pups, these changes were not modified by LGG pretreatment. Beta diversity analyses also showed differences between SCB34-infected vs. uninfected pups. LGG pretreatment before SCB34 infection did not result in significant beta diversity changes compared to placebo. Moreover, individual genera and species abundance analyses by linear discriminant analysis effect size (LEfSe) showed significant changes in Gram-negative, Gram-positive, and anaerobic populations resulting from LGG pretreatment and SCB34 infection. LGG significantly suppressed the expression of inflammatory cytokines but did not attenuate SCB34-induced apoptosis or histologic injury.

CONCLUSIONS

LGG modulates clinically significant microbiota features and inflammation triggered by pathogenic E. coli intestinal infection shortly after birth. This new knowledge can potentially be harnessed to design novel interventions against gut-derived neonatal sepsis.

Microbes as medicine

Over the last two decades, advancements in sequencing technologies have significantly deepened our understanding of the human microbiome's complexity, leading to increased concerns about the detrimental effects of antibiotics on these intricate microbial ecosystems. Concurrently, the rise in antimicrobial resistance has intensified the focus on how beneficial microbes can be harnessed to treat diseases and improve health and offer potentially promising alternatives to traditional antibiotic treatments. Here, we provide a comprehensive overview of both established and emerging microbe-centric therapies, from probiotics to advanced microbial ecosystem therapeutics, examine the sophisticated ways in which microbes are used medicinally, and consider their impacts on microbiome homeostasis and health outcomes through a microbial ecology lens. In addition, we explore the concept of rewilding the human microbiome by reintroducing "missing microbes" from nonindustrialized societies and personalizing microbiome modulation to fit individual microbial profiles-highlighting several promising directions for future research. Ultimately, the advancements in sequencing technologies combined with innovative microbial therapies and personalized approaches herald a new era in medicine poised to address antibiotic resistance and improve health outcomes through targeted microbiome management.

The effect of arginine on the growth of probiotics

OBJECTIVE(S)

The study objective was to examine the effect of arginine (Arg) supplementation on the growth of probiotics.

METHODS

Lacticaseibacillus rhamnosus GG, Lactiplantibacillus plantarum, and Lactobacillus acidophilus were identified as potential probiotics. L. rhamnosus GG and L. plantarum were selected for further experimentation. The probiotics were co-treated with 0.9 % NaCl (negative control), 0.5 % Arg, and 1.0 % Arg in a 1:1 ratio for 24 h at 5 % CO2, 37 °C. The probiotics were tested for growth profiles, spectroscopic turbidity assay, metabolic assays (XTT and WST-8), live/dead cell assessment using confocal laser scanning microscopy (CLSM), and colony forming units (CFU).

RESULTS

The growth profiles of L. rhamnosus GG and L. plantarum were found to be similar, whereas L. acidophilus showed minimal or no transition from the initial lag phase. In the turbidity assay, the end-point absorbance for L. rhamnosus GG with 1.0 % Arg was significantly lower than 0.9 % NaCl and 0.5 % Arg (p < 0.05). For metabolic assays and CFU, increasing concentrations of Arg increased the viable cells for L. rhamnosus GG (p < 0.05), but decreased viability for L. plantarum (p < 0.05). Metabolic assays with dual-species bacterial suspensions indicated that Arg co-treatment inhibited viable proportions compared to control (p < 0.05). The dead cell proportion was significantly lower than live cell proportion for all tested interventions and probiotics (p < 0.05).

CONCLUSION

Increasing concentrations of Arg promote the growth of L. rhamnosus GG, while conversely inhibiting the growth of L. plantarum. Therefore, the effect of prebiotic Arg on probiotics is concentration-dependent, leading to a selective promotion or inhibition of growth.

CLINICAL SIGNIFICANCE

The present study results show that Arg supplementation can selectively enhance the growth of L. rhamnosus GG while inhibit the growth of L. plantarum. This underscores the need to consider strain-specific responses in probiotic formulations when developing Arg-based synbiotics for modulating biofilms and creating ecologically homeostatic biofilm microenvironments.

Microencapsulated Lactobacillus plantarum promotes intestinal development through gut colonization of layer chicks

The effects of Lactobacillus plantarum in microencapsulation (LPM) on intestinal development in layer chicks were investigated in this study, as well as the colonization of L. plantarum in the gut. A total of 480 healthy Hy-Line Brown layer chicks at 0 d old were randomly divided into 4 groups (8 replicates each treatment), and the diets of these birds were supplemented with nothing (control), L. plantarum (0.02 g/kg feed; 109 CFU/kg feed), LPM (1.0 g/kg feed; 109 CFU/kg feed) and wall material of LPM (WM; 0.98 g/kg feed), respectively. Compared to control, LPM improved growth performance and intestinal development of layer chicks, evidenced by significantly increased body weight, average daily gain, average daily feed intake, villus height, villus height/crypt depth, as well as weight and length of the duodenum, jejunum and ileum (P < 0.05). These results could be attributed to the increased colonization of L. plantarum in the gut, which was verified by significant increases in lactic acid content, viable counts in chyme and mucosa (P < 0.05), as well as a visible rise in number of strains labeled with fluorescein isothiocyanate. Meanwhile, the relative abundances of Lactobacillus and Bifidobacterium significantly increased in response to microencapsulated L. plantarum supplementation (P < 0.05), accompanied by the significant up-regulation of colonization related genes (P < 0.05), encoding solute carrier family, monocarboxylate transporter, activin A receptor, succinate receptor and secretogranin II. To sum up, microencapsulated L. plantarum supplementation promoted intestinal development, which could be attributed to the enhancement of L. plantarum colonization in the intestine through the mutual assistance of Bifidobacterium and interactions with colonization related transmembrane proteins.

Contribution of Surface Adhesins of Lacticaseibacillus paracasei S-NB to Its Intestinal Adhesion and Colonization

The intestinal retention and persistence of lactic acid bacteria (LAB) are strain-specific and affected by the bacterial surface components. However, the contribution of surface adhesins of LAB to intestinal adhesion and colonization remains unclear. In the present study, seven gene knockout mutants (genes related to surface adhesin synthesis) of Lacticaseibacillus paracasei S-NB were derived based on the Cre-lox-based recombination system. Results showed that the capsule layer appeared thinner in the cell wall of S-NBΔ7576, S-NBΔdlt, and S-NBΔsrtA mutants when compared with the wild-type (WT) S-NB. The effects of S-NB_7576 (wzd and wze genes, responsible for capsular polysaccharide synthesis) and S-NB_srtA (sortase A) mutation on the hydrophobicity, surface charge, and adhesion ability seem to vary strongly among seven mutant strains. In vivo colonization experiments showed a decrease in the colonization numbers of S-NBΔ7576 and S-NBΔsrtA in both the ileal and colon lumen from 2 to 8 days when compared with those of the WT S-NB. In conclusion, the synthesis of capsular polysaccharides and the transport of surface proteins are closely related to the adhesion ability and intestinal colonization of L. paracasei S-NB.

Repairing gut barrier by traditional Chinese medicine: roles of gut microbiota

Gut barrier is not only part of the digestive organ but also an important immunological organ for the hosts. The disruption of gut barrier can lead to various diseases such as obesity and colitis. In recent years, traditional Chinese medicine (TCM) has gained much attention for its rich clinical experiences enriched in thousands of years. After orally taken, TCM can interplay with gut microbiota. On one hand, TCM can modulate the composition and function of gut microbiota. On the other hand, gut microbiota can transform TCM compounds. The gut microbiota metabolites produced during the actions of these interplays exert noticeable pharmacological effects on the host especially gut barrier. Recently, a large number of studies have investigated the repairing and fortifying effects of TCM on gut barriers from the perspective of gut microbiota and its metabolites. However, no review has summarized the mechanism behand this beneficiary effects of TCM. In this review, we first briefly introduce the unique structure and specific function of gut barrier. Then, we summarize the interactions and relationship amidst gut microbiota, gut microbiota metabolites and TCM. Further, we summarize the regulative effects and mechanisms of TCM on gut barrier including physical barrier, chemical barrier, immunological barrier, and microbial barrier. At last, we discuss the effects of TCM on diseases that are associated gut barrier destruction such as ulcerative colitis and type 2 diabetes. Our review can provide insights into TCM, gut barrier and gut microbiota.

The crystal structure of the N-terminal domain of the backbone pilin LrpA reveals a new closure-and-twist motion for assembling dynamic pili in Ligilactobacillus ruminis

Sortase-dependent pili are long surface appendages that mediate attachment, colonization and biofilm formation in certain genera and species of Gram-positive bacteria. Ligilactobacillus ruminis is an autochthonous gut commensal that relies on sortase-dependent LrpCBA pili for host adherence and persistence. X-ray crystal structure snapshots of the backbone pilin LrpA were captured in two atypical bent conformations leading to a zigzag morphology in the LrpCBA pilus structure. Small-angle X-ray scattering and structural analysis revealed that LrpA also adopts the typical linear conformation, resulting in an elongated pilus morphology. Various conformational analyses and biophysical experiments helped to demonstrate that a hinge region located at the end of the flexible N-terminal domain of LrpA facilitates a new closure-and-twist motion for assembling dynamic pili during the assembly process and host attachment. Further, the incongruent combination of flexible domain-driven conformational dynamics and rigid isopeptide bond-driven stability observed in the LrpCBA pilus might also extend to the sortase-dependent pili of other bacteria colonizing a host.

Unlocking the genetic potential of Lacticaseibacillus rhamnosus strains: Medical applications of a promising probiotic for human and animal health

Lacticaseibacillus rhamnosus is a group of probiotic strains that have gained popularity for their potential health benefits such as promoting digestive health, boosting the immune system, improving lactose digestion, preventing and treating antibiotic-associated diarrhea, reducing the severity and duration of certain infections, and preventing the formation of dental plaque. In particular, L. rhamnosus strains SD4 and SD11 have promising human and animal health applications due to their ability to inhibit the growth of harmful pathogens. This study presents an in silico genomic analysis of L. rhamnosus strains SD4 and SD11. We analyzed draft genomes and conducted comparative genome analyses against several other probiotic strains, aiming to gain insights into the genomes of the two strains and to compare them to related strains isolated from other sources. We also aimed to clarify the functional mechanisms and adaptation of these strains to specific environments. Comprehensive insights into the genomes of L. rhamnosus SD4 and SD11 could enhance our understanding of their capacity to colonize, adapt, and exhibit probiotic properties after administration. This study holds significance in advancing our understanding of the potential health benefits associated with these strains and in elucidating the underlying mechanisms responsible for their effectiveness in humans and animals.

Molecular Mechanisms of Lacticaseibacillus rhamnosus, LGG® Probiotic Function

To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. Lacticaseibacillus rhamnosus LGG® is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG®, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified. In vitro and animal studies have revealed that specific LGG® effector molecules stimulate epithelial cell survival, preserve intestinal barrier integrity, reduce oxidative stress, mitigate excessive mucosal inflammation, enhance IgA secretion, and provide long-term protection through epigenetic imprinting. Pili on the cell surface of LGG® promote adhesion to the intestinal mucosa and ensure close contact to host cells. Extracellular vesicles produced by LGG® recapitulate many of these effects through their cargo of effector molecules. Collectively, the effector molecules of LGG® exert a significant influence on both the gut mucosa and immune system, which promotes intestinal homeostasis and immune tolerance.

Lactobacillus rhamnosus GG triggers intestinal epithelium injury in zebrafish revealing host dependent beneficial effects

Lactobacillus rhamnosus GG (LGG), the well-characterized human-derived probiotic strain, possesses excellent properties in the maintenance of intestinal homeostasis, immunoregulation and defense against gastrointestinal pathogens in mammals. Here, we demonstrate that the SpaC pilin of LGG causes intestinal epithelium injury by inducing cell pyroptosis and gut microbial dysbiosis in zebrafish. Dietary SpaC activates Caspase-3-GSDMEa pathways in the intestinal epithelium, promotes intestinal pyroptosis and increases lipopolysaccharide (LPS)-producing gut microbes in zebrafish. The increased LPS subsequently activates Gaspy2-GSDMEb pyroptosis pathway. Further analysis reveals the Caspase-3-GSDMEa pyroptosis is initiated by the species-specific recognition of SpaC by TLR4ba, which accounts for the species-specificity of the SpaC-inducing intestinal pyroptosis in zebrafish. The observed pyroptosis-driven gut injury and microbial dysbiosis by LGG in zebrafish suggest that host-specific beneficial/harmful mechanisms are critical safety issues when applying probiotics derived from other host species and need more attention.

Harnessing Vaginal Probiotics for Enhanced Management of Uterine Disease and Reproductive Performance in Dairy Cows: A Conceptual Review

Uterine disease in cattle impairs reproductive performance and profitability and increases antibiotic use and antimicrobial resistance. Thus, probiotics offer a promising alternative therapy. This review presents conceptual findings on the efficacy of probiotics in managing uterine diseases and fertility in cows. Probiotics containing Lactobacillus spp. and Bifidobacterium spp. individually or as composite formulations are known to improve fertility. Strategic intravaginal administration of these formulations would likely enhance uterine immunity, particularly during the postpartum period. While current findings on the benefits to uterine health are encouraging, there is still significant knowledge missing, including a lack of empirical information from large-scale field trials. This review underscores the need for evidence-based guidelines for probiotics, such as genomic selection of formulations, targeted delivery, or potential synergy with other interventions. Future research should address these gaps to maximize the potential of probiotics in managing uterine diseases and enhancing the reproductive health of dairy cattle.

A Self-Adaptive Pyroptosis Inducer: Optimizing the Catalytic Microenvironment of Nanozymes by Membrane-Adhered Microbe Enables Potent Cancer Immunotherapy

Pyroptosis has garnered increasing attention in cancer immunotherapy. Moreover, increasing plasma membrane damage by reactive oxygen species (ROS) is considered an effective strategy for promoting pyroptosis. However, the current tactics for enhancing membrane rupture in pyroptosis are limited by the inherent drawbacks of ROS and the immunosuppressive tumor microenvironment. Herein, a self-adaptive pyroptosis inducer (LPZ) is designed by integrating Lactobacillus rhamnosus GG (LGG) and an enzyme-like metal-organic framework to achieve potent pyroptosis immunotherapy. LPZ can adhere to cancer cell membranes through the interaction between the pili of LGG and the mucin of cancer cells. In particular, the adaptive formula can gradually enhance the ability of nanozymes to produce ROS by creating an acidic microenvironment through anaerobic respiration. These results verify that LPZ could generate high levels of ROS both on the membrane and within cancer cells, leading to pyroptotic cell death and strong antitumor immunity. Meanwhile, LGG are eventually killed by ROS in this process to halt their respiration and prevent potential biosafety concerns. Overall, this work provides new inspiration for the design of self-adaptive nanocatalytic drugs for cancer immunotherapy.

Prebiotic effect of galacto-N-biose on the intestinal lactic acid bacteria as enhancer of acetate production and hypothetical colonization

Galacto-N-biose (GNB) is an important core structure of glycan of mucin glycoproteins in the gastrointestinal (GI) mucosa. Because certain beneficial bacteria inhabiting the GI tract, such as bifidobacteria and lactic acid bacteria, harbor highly specialized GNB metabolic capabilities, GNB is considered a promising prebiotic for nourishing and manipulating beneficial bacteria in the GI tract. However, the precise interactions between GNB and beneficial bacteria and their accompanying health-promoting effects remain elusive. First, we evaluated the proliferative tendency of beneficial bacteria and their production of beneficial metabolites using gut bacterial strains. By comparing the use of GNB, glucose, and inulin as carbon sources, we found that GNB enhanced acetate production in Lacticaseibacillus casei, Lacticaseibacillus rhamnosus, Lactobacillus gasseri, and Lactobacillus johnsonii. The ability of GNB to promote acetate production was also confirmed by RNA-seq analysis, which indicated the upregulation of gene clusters that catalyze the deacetylation of N-acetylgalactosamine-6P and biosynthesize acetyl-CoA from pyruvate, both of which result in acetate production. To explore the in vivo effect of GNB in promoting acetate production, antibiotic-treated BALB/cA mice were administered with GNB with L. rhamnosus, resulting in a fecal acetate content that was 2.7-fold higher than that in mice administered with only L. rhamnosus. Moreover, 2 days after the last administration, a 3.7-fold higher amount of L. rhamnosus was detected in feces administered with GNB with L. rhamnosus than in feces administered with only L. rhamnosus. These findings strongly suggest the prebiotic potential of GNB in enhancing L. rhamnosus colonization and converting L. rhamnosus into higher acetate producers in the GI tract.

IMPORTANCE

Specific members of lactic acid bacteria, which are commonly used as probiotics, possess therapeutic properties that are vital for human health enhancement by producing immunomodulatory metabolites such as exopolysaccharides, short-chain fatty acids, and bacteriocins. The long residence time of probiotic lactic acid bacteria in the GI tract prolongs their beneficial health effects. Moreover, the colonization property is also desirable for the application of probiotics in mucosal vaccination to provoke a local immune response. In this study, we found that GNB could enhance the beneficial properties of intestinal lactic acid bacteria that inhabit the human GI tract, stimulating acetate production and promoting intestinal colonization. Our findings provide a rationale for the addition of GNB to lactic acid bacteria-based functional foods. This has also led to the development of therapeutics supported by more rational prebiotic and probiotic selection, leading to an improved healthy lifestyle for humans.

Milk and Its Derivatives as Sources of Components and Microorganisms with Health-Promoting Properties: Probiotics and Bioactive Peptides

Milk is a source of many valuable nutrients, including minerals, vitamins and proteins, with an important role in adult health. Milk and dairy products naturally containing or with added probiotics have healthy functional food properties. Indeed, probiotic microorganisms, which beneficially affect the host by improving the intestinal microbial balance, are recognized to affect the immune response and other important biological functions. In addition to macronutrients and micronutrients, biologically active peptides (BPAs) have been identified within the amino acid sequences of native milk proteins; hydrolytic reactions, such as those catalyzed by digestive enzymes, result in their release. BPAs directly influence numerous biological pathways evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses. The addition of BPAs to food products or application in drug development could improve consumer health and provide therapeutic strategies for the treatment or prevention of diseases. Herein, we review the scientific literature on probiotics, BPAs in milk and dairy products, with special attention to milk from minor species (buffalo, sheep, camel, yak, donkey, etc.); safety assessment will be also taken into consideration. Finally, recent advances in foodomics to unveil the probiotic role in human health and discover novel active peptide sequences will also be provided.

Assessing probiotic viability in mixed species yogurt using a novel propidium monoazide (PMAxx)-quantitative PCR method

Viability is a prerequisite for any therapeutic benefits associated with the ingestion of probiotic bacteria. Current culture-based techniques are inadequate for the enumeration of probiotics in mixed-species food products. This study utilized a quantitative PCR (qPCR) method coupled with propidium monoazide (PMAxx), and novel species-specific tuf gene primers to selectively enumerate Lacticaseibacillus rhamnosus, Bifidobacterium spp., and yogurt starter cultures in mixed-species probiotic yogurt. The method was optimized for PMAxx concentration and specificity and evaluated for efficiency and applicability. PMAxx-qPCR showed high specificity to the target organisms in mixed-species yogurt, quantifying only viable cells. The linear dynamic ranges were established over five to seven orders of magnitude. The assay was reliable with an efficiency of 91-99%, R2 values > 0.99, and a good correlation to the plate count method (r = 0.882). The results of this study demonstrate the high selectivity, improved lead time, and reliability of PMAxx-qPCR over the culture-dependent method, making it a valuable tool for inline viability verification during processing and improving probiotic quality assurance for processors and consumers.

Novel Lactobacillaceae strains and consortia to produce propionate-containing fermentates as biopreservatives

Biopreservation refers to the use of natural or controlled microbial single strains or consortia, and/or their metabolites such as short-chain carboxylic acids (SCCA), to improve the shelf-life of foods. This study aimed at establishing a novel Lactobacillaceae-driven bioprocess that led to the production of the SCCA propionate through the cross-feeding on 1,2-propanediol (1,2-PD) derived from the deoxyhexoses rhamnose or fucose. When grown as single cultures in Hungate tubes, strains of Lacticaseibacillus rhamnosus preferred fucose over rhamnose and produced 1,2-PD in addition to lactate, acetate, and formate, while Limosilactobacillus reuteri metabolized 1,2-PD into propionate, propanol and propanal. Loigolactobacillus coryniformis used fucose to produce 1,2-PD and only formed propionate when supplied with 1,2-PD. Fermentates collected from batch fermentations in bioreactor using two-strain consortia (L. rhamnosus and L. reuteri) or fed-batch fermentations of single strain cultures of L. coryniformis with rhamnose contained mixtures of SCCA consisting of mainly lactate and acetate and also propionate. Synthetic mixtures that contained SCCA at concentrations present in the fermentates were more antimicrobial against Salmonella enterica if propionate was present. Together, this study (i) demonstrates the potential of single strains and two-strain consortia to produce propionate in the presence of deoxyhexoses extending the fermentation metabolite profile of Lactobacillaceae, and (ii) emphasizes the potential of applying propionate-containing fermentates as biopreservatives.

Safety Assessment and Probiotic Potential Comparison of Bifidobacterium longum subsp. infantis BLI-02, Lactobacillus plantarum LPL28, Lactobacillus acidophilus TYCA06, and Lactobacillus paracasei ET-66

Bifidobacterium longum subsp. infantis BLI-02, Lactobacillus paracasei ET-66, Lactobacillus plantarum LPL28, and Lactobacillus acidophilus TYCA06, isolated from healthy breast milk, miso, and the healthy human gut, were assessed for safety in this study. BLI-02, LPL28, TYCA06, and ET-66 exhibited no antibiotic resistance and mutagenic activity in the Ames test at the highest dosage (5000 μg/plate). No genotoxicity was observed in micronucleus and chromosomal aberration assays in rodent spermatogonia at the maximum dosage of 10 g/kg body weight (BW). No acute and sub-chronic toxicity occurred in mice and rats at the maximum tested dosage of 10 g/kg BW and 1.5 g/kg BW, respectively. The lyophilized powder of these strains survived a low pH and high bile salt environment, adhering strongly to Caco-2 cells. Unique antimicrobial activities were noted in these strains, with BLI-02 demonstrating the best growth inhibition against Vibrio parahaemolyticus, LPL28 exhibiting the best growth inhibition against Helicobacter pylori, and ET-66 showing the best growth inhibition against Aggregatibacter actinomycetemcomitans. Based on the present study, the lyophilized powder of these four strains appears to be a safe probiotic supplement at tested dosages. It should be applicable for clinical or healthcare applications.

HMO-primed bifidobacteria exhibit enhanced ability to adhere to intestinal epithelial cells

The ability of gut commensals to adhere to the intestinal epithelium can play a key role in influencing the composition of the gut microbiota. Bifidobacteria are associated with a multitude of health benefits and are one of the most widely used probiotics for humans. Enhanced bifidobacterial adhesion may increase host-microbe, microbe-nutrient, and/or microbe-microbe interactions, thereby enabling consolidated health benefits to the host. The objective of this study was to determine the ability of human milk oligosaccharides (HMOs) to enhance bifidobacterial intestinal adhesion in vitro. This study assessed the colonisation-promoting effects of HMOs on four commercial infant-associated Bifidobacterium strains (two B. longum subsp. infantis strains, B. breve and B. bifidum). HT29-MTX cells were used as an in vitro intestinal model for bacterial adhesion. Short-term exposure of four commercial infant-associated Bifidobacterium strains to HMOs derived from breastmilk substantially increased the adherence (up to 47%) of these probiotic strains. Interestingly, when strains were incubated with HMOs as a four-strain combination, the number of viable bacteria adhering to intestinal cells increased by >90%. Proteomic analysis of this multi-strain bifidobacterial mixture revealed that the increased adherence resulting from exposure to HMOs was associated with notable increases in the abundance of sortase-dependent pili and glycosyl hydrolases matched to Bifidobacterium bifidum. This study suggests that HMOs may prime infant gut-associated Bifidobacterium for colonisation to intestinal epithelial cells by influencing the expression of various colonization factors.

Characterization of the probiotic properties of Lacticaseibacillus rhamnosus LR6 isolated from the vaginas of healthy Korean women against vaginal pathogens

The human microbiome exhibits intricate populations across the body, with the vaginal tract serving as an ecosystem characterized by the prevalence of the genus Lactobacillus. Disruptions in the vaginal microbiota, which are frequently linked to variables such as sexual activity, hormonal fluctuations, and excessive use of antibiotics, can result in vaginal dysbiosis and the development of diseases such as bacterial vaginosis (BV) and candidiasis. Lactobacillus species, owing to their capacity to create an acidic environment through the production of lactic acid, have a key function within this complex microbial community: they inhibit the growth of harmful microorganisms. This study aimed to investigate the genomic characteristics of L. rhamnosus LR6, a newly discovered strain isolated from the vaginal microbiota of 20 healthy women to assess its potential as a vaginal probiotic. We performed a comparative investigation of the genetic traits of L. rhamnosus using 45 publicly available genomes from various sources. We evaluated the genetic characteristics related to carbohydrate utilization, adhesion to host cells, and the presence of bacteriocin clusters. A comprehensive study was conducted by integrating in silico evaluations with experimental techniques to authenticate the physiological characteristics of strain LR6. We further used a rat model to assess the impact of L. rhamnosus LR6 administration on the changes in the gastrointestinal tract and the vaginal microbiome. The assessments revealed a significantly high inhibitory activity against pathogens, enhanced adherence to host cells, and high lactic acid production. Rat experiments revealed changes in both the fecal and vaginal microbiota; in treated rats, Firmicutes increased in both; Lactobacillaceae increased in the fecal samples; and Enterobacteriaceae decreased but Enterococcaceae, Streptococcaceae, and Morganellaceae increased in the vaginal samples. The study results provide evidence of the genetic characteristics and probiotic properties of LR6, and suggest that oral administration of L. rhamnosus LR6 can alter both gut and vaginal microbiome. Collectively, these findings establish L. rhamnosus LR6 as a highly promising candidate for improving vaginal health.

Characterization of potential probiotic starter cultures of lactic acid bacteria isolated from Ethiopian fermented cereal beverages, Naaqe, and Cheka

AIMS

To test the in vitro probiotic potential and starter culture capacity of lactic acid bacteria (LAB) isolated from Naaqe and Cheka, cereal-based Ethiopian traditional fermented beverages.

METHODS AND RESULTS

A total of 44 strains were isolated from spontaneously fermented Ethiopian cereal-based beverages, Naaqe and Cheka with 24 putatively identified as LAB and 14 identified up to the species level. The species Limosilactobacillus fermentum (6/12; 50%) and Weissella confusa (5/12, 41.67%) were the predominant species identified from Naaqe, while the two Cheka isolates were L. fermentum and Pediococcus pentosaceus. Six LAB strains inhibited eight of the nine gastrointestinal indicator key pathogens in Ethiopia, including Escherichia coli, Salmonella enterica subsp. enterica var. Typhimurium, Staphylococcus aureus, Shigella flexneri, and Listeria monocytogenes. Three of the LAB isolates exhibited strain-specific immunostimulation in human monocytes. Based on these probiotic properties and growth, six strains were selected for in situ evaluation in a mock fermentation of Naaqe and Cheka. During primary fermentations, L. fermentum 73B, P. pentosaceus 74D, L. fermentum 44B, W. confusa 44D, L. fermentum 82C, and Weissella cibaria 83E and their combinations demonstrated higher pH-lowering properties and colony-forming unit counts compared to the control spontaneous fermentation. The same pattern was also observed in the secondary mock fermentation by the Naaqe LAB isolates.

CONCLUSIONS

In this study, we selected six LAB strains with antipathogenic, immunostimulatory, and starter culture potentials that can be used as autochthonous probiotic starters for Naaqe and Cheka fermentations once their health benefit is ascertained in a clinical trial as a next step.

A large-scale comparative genomics study reveals niche-driven and within-sample intra-species functional diversification in Lacticaseibacillus rhamnosus

Lacticaseibacillus rhamnosus (L. rhamnosus) is widely recognized as a probiotic species, and it exists in a variety of environments including host gut and dairy products. This work aimed at conducting a large-scale comparative genomics analysis of 384 L. rhamnosus genomes (257 whole-sequence or metagenomic-assembled genomes from gut-associated isolates [122 and 135 retrieved from the UHGG and NCBI databases, respectively] and 127 genomes from dairy isolates [34 from the NCBI database; 93 isolated from a cheese sample and sequenced here]). Our results showed that L. rhamnosus had a large and open pan-genome (15,253 pan-genes identified from all 384 genomes; 15,028 pan-genes if the 93 cheese-originated isolates were excluded). The core-gene phylogenetic tree constructed from the 384 L. rhamnosus genomes comprised five phylogenetic branches, with a random distribution of dairy and gut-associated isolates/genomes across the tree. No significant difference was identified in the overall profile of metabolism-related genes between dairy and gut-associated genomes; however, notably, the gut-associated strains/isolates contained more genes coding for specific metabolic pathways and carbohydrate-active enzymes, e.g., lacto-N-biosidase (EC 3.2.1.140; GT20) and lacto-N-biose phosphorylase/galacto-N-biose phosphorylase (EC 2.4.1.211; GH112). Further, we found that there was obvious intra-species diversification of the 93 cheese-originated L. rhamnosus isolates, forming three clades (Clades A, B, and C) in the reconstructed core-gene phylogenetic tree. There were numerous single nucleotide variations (over 10,000) across the three clades. Moreover, significant differences were observed in the content of metabolism-related genes across clades (p < 0.05, Adonis test), characterized by the enrichment in glycoside hydrolases in Clade C and the possession of unique metabolic pathways in each clade. These results implicated genomics/functional diversification of L. rhamnosus in a single food matrix and niche-driven adaptive evolution of isolates from dairy and host gut-associated origins. Our study shed insights into the selection of candidate strains for food industry applications.

Mucosa-Mimetic Materials for the Study of Intestinal Homeostasis and Disease

Mucus is a viscoelastic hydrogel that lines and protects the epithelial surfaces of the body that houses commensal microbiota and functions in host defense against pathogen invasion. As a first-line physical and biochemical barrier, intestinal mucus is involved in immune surveillance and spatial organization of the microbiome, while dysfunction of the gut mucus barrier is implicated in several diseases. Mucus can be collected from a variety of mammalian sources for study, however, established methods are challenging in terms of scale and efficiency, as well as with regard to rheological similarity to native human mucus. Therefore, there is a need for mucus-mimetic hydrogels that more accurately reflect the physical and chemical profile of the in vivo human epithelial environment to enable the investigation of the role of mucus in human disease and interactions with the intestinal microbiome. This review will evaluate the material properties of synthetic mucus mimics to date designed to address the above need, with a focus toward an improved understanding of the biochemical and immunological functions of these biopolymers related to utility for research and therapeutic applications.

Promising application of probiotic microorganisms as Pickering emulsions stabilizers

The purpose of this work was to study the ability of nineteen food-grade microorganisms as Pickering emulsion (PE) stabilizers. Medium-chain triacylglycerol (MCT) oil-in-water (50:50) PEs were fabricated by 10 wt% or 15 wt% of thermally-inactivated yeast, cocci, Bacillus spp. and lactobacilli cells. The characteristics of microorganisms related to "Pickering stabilization" including morphology, surface charge, interfacial tension, and "contact angle" were firstly studied. After that, the cells-stabilized PEs were characterized from both kinetic and thermodynamic viewpoints, microstructure and rheological properties. The interfacial tension and "contact angle" values of various microorganisms ranged from 16.33 to 38.31 mN/m, and from 15° to 106°, respectively. The mean droplet size of PEs ranged from 11.51 to 57.69 µm. Generally, the physical stability of cell-stabilized PEs followed this order: lactobacilli > Bacillus spp. > cocci > yeast. These variations were attributed to the morphology and cell wall composition. Increasing the microorganism concentration significantly increased the physical stability of PEs from a maximum of 12 days at 10 wt% to 35 days at 15 wt% as a result of better interface coverage. Shear-thinning and dominant elastic behaviors were observed in PEs. Physical stability was affected by the free energy of detachment. Therefore, food-grade microorganisms are suggested for stabilizing PEs.

Bacterial biofilms in the human body: prevalence and impacts on health and disease

Bacterial biofilms can be found in most environments on our planet, and the human body is no exception. Consisting of microbial cells encased in a matrix of extracellular polymers, biofilms enable bacteria to sequester themselves in favorable niches, while also increasing their ability to resist numerous stresses and survive under hostile circumstances. In recent decades, biofilms have increasingly been recognized as a major contributor to the pathogenesis of chronic infections. However, biofilms also occur in or on certain tissues in healthy individuals, and their constituent species are not restricted to canonical pathogens. In this review, we discuss the evidence for where, when, and what types of biofilms occur in the human body, as well as the diverse ways in which they can impact host health under homeostatic and dysbiotic states.

Intestinal mucus and their glycans: A habitat for thriving microbiota

The colon mucus layer is organized with an inner colon mucus layer that is impenetrable to bacteria and an outer mucus layer that is expanded to allow microbiota colonization. A major component of mucus is MUC2, a glycoprotein that is extensively decorated, especially with O-glycans. In the intestine, goblet cells are specialized in controlling glycosylation and making mucus. Some microbiota members are known to encode multiple proteins that are predicted to bind and/or cleave mucin glycans. The interactions between commensal microbiota and host mucins drive intestinal colonization, while at the same time, the microbiota can utilize the glycans on mucins and affect the colonic mucus properties. This review will examine this interaction between commensal microbes and intestinal mucins and discuss how this interplay affects health and disease.

Exploring probiotic effector molecules and their mode of action in gut-immune interactions

Probiotics, live microorganisms that confer health benefits when consumed in adequate amounts, have gained significant attention for their potential therapeutic applications. The beneficial effects of probiotics are believed to stem from their ability to enhance intestinal barrier function, inhibit pathogens, increase beneficial gut microbes, and modulate immune responses. However, clinical studies investigating the effectiveness of probiotics have yielded conflicting results, potentially due to the wide variety of probiotic species and strains used, the challenges in controlling the desired number of live microorganisms, and the complex interactions between bioactive substances within probiotics. Bacterial cell wall components, known as effector molecules, play a crucial role in mediating the interaction between probiotics and host receptors, leading to the activation of signaling pathways that contribute to the health-promoting effects. Previous reviews have extensively covered different probiotic effector molecules, highlighting their impact on immune homeostasis. Understanding how each probiotic component modulates immune activity at the molecular level may enable the prediction of immunological outcomes in future clinical studies. In this review, we present a comprehensive overview of the structural and immunological features of probiotic effector molecules, focusing primarily on Lactobacillus and Bifidobacterium. We also discuss current gaps and limitations in the field and propose directions for future research to enhance our understanding of probiotic-mediated immunomodulation.

Homologous genes shared between probiotics and pathogens affect the adhesion of probiotics and exclusion of pathogens in the gut mucus of shrimp

Clarifying mechanisms underlying the selective adhesion of probiotics and competitive exclusion of pathogens in the intestine is a central theme for shrimp health. Under experimental manipulation of probiotic strain (i.e., Lactiplantibacillus plantarum HC-2) adhesion to the shrimp mucus, this study tested the core hypothesis that homologous genes shared between probiotic and pathogen would affect the adhesion of probiotics and exclusion of pathogens by regulating the membrane proteins of probiotics. Results indicated that the reduction of FtsH protease activity, which significantly correlated with the increase of membrane proteins, could increase the adhesion ability of L. plantarum HC-2 to the mucus. These membrane proteins mainly involved in transport (glycine betaine/carnitine/choline ABC transporter choS, ABC transporter, ATP synthase subunit a atpB, amino acid permease) and regulation of cellular processes (histidine kinase). The genes encoding the membrane proteins were significantly (p < 0.05) up-regulated except those encoding ABC transporters and histidine kinases in L. plantarum HC-2 when co-cultured with Vibrio parahaemolyticus E1, indicating that these genes could help L. plantarum HC-2 to competitively exclude pathogens. Moreover, an arsenal of genes predicted to be involved in carbohydrate metabolism and bacteria-host interactions were identified in L. plantarum HC-2, indicating a clear strain adaption to host's gastrointestinal tract. This study advances our mechanistic understanding of the selective adhesion of probiotics and competitive exclusion of pathogens in the intestine, and has important implications for screening and applying new probiotics for maintaining gut stability and host health.

Safety and Potential Role of Lactobacillus rhamnosus GG Administration as Monotherapy in Ulcerative Colitis Patients with Mild-Moderate Clinical Activity

Probiotics are microorganisms that confer benefits to the host, and, for this reason, they have been proposed in several pathologic states. Specifically, probiotic bacteria have been investigated as a therapeutic option in ulcerative colitis (UC) patients, but clinical results are dishomogeneous. In particular, many probiotic species with different therapeutic schemes have been proposed, but no study has investigated probiotics in monotherapy in adequate trials for the induction of remission. Lactobacillus rhamnosus GG (LGG) is the more intensively studied probiotic and it has ideal characteristics for utilization in UC patients. The aim of the present study is to investigate the clinical efficacy and safety of LGG administration in an open trial, delivered in monotherapy at two different doses, in UC patients with mild-moderate disease. The UC patients with mild-moderate disease activity (Partial Mayo score ≥ 2) despite treatment with oral mesalamine were included. The patients stopped oral mesalamine and were followed up for one month, then were randomized to receive LGG supplement at dose of 1.2 or 2.4 × 10¹⁰ CFU/day for one month. At the end of the study, the clinical activity was evaluated and compared to that at the study entrance (efficacy). Adverse events were recorded (safety). The primary end-point was clinical improvement (reduction in the Partial Mayo score) and no serious adverse events, while the secondary end-points were the evaluation of different efficacies and safeties between the two doses of LGG. The patients with disease flares dropped out of the study and went back to standard therapy. The efficacy data were analyzed in an intention-to-treat (ITT) and per-protocol (PP) analysis. Out of the 76 patients included in the study, 75 started the probiotic therapy (n = 38 and 37 per group). In the ITT analysis, 32/76 (42%) responded to treatment, 21/76 (28%) remained stable, and 23/76 (30%) had a worsening of their clinical condition; 55 (72%) completed the treatment and were analyzed in a PP analysis: 32/55 (58%) had a clinical response, 21 (38%) remained stable, and 2 (4%) had a light worsening of their clinical condition (p < 0.0001). Overall, 37% of the patients had a disease remission. No severe adverse event was recorded, and only one patient stopped therapy due to obstinate constipation. No difference in the clinical efficacy and safety has been recorded between groups treated with different doses of LGG. The present prospective clinical trial demonstrates, for the first time, that LGG in monotherapy is safe and effective for the induction of remission in UC patients with mild-moderate disease activity (ClinicalTrials.gov identifier: NCT04102852).

The effect of synbiotic-fluoride therapy on multi-species biofilm

OBJECTIVES

The study objective was to examine the effect of synbiotic-fluoride (SF) therapy within a multi-species cariogenic biofilm model system comprising of S. mutans, S. sanguinis, and S. gordonii.

METHODS

The SF therapy was prepared using 2% L-arginine (Arg), 0.2% NaF and probiotic L. rhamnosus GG (LRG). The 8 treatment groups were: Group 1: No treatment, Group 2: 2% Arg, Group 3: 0.2% NaF, Group 4: LRG, Group 5: 2% Arg+0.2% NaF, Group 6: 2% Arg+LRG, Group 7: 0.2% NaF+LRG, and Group 8: SF therapy (2% Arg+0.2% NaF +LRG). Multi-species biofilm model over 96 h comprising Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii was utilized. The biofilms received cariogenic challenge and SF therapy 2 × /day. The extracellular matrix components were analyzed for carbohydrates, proteins, and extra-cellular DNA (eDNA). The live/dead cells were imaged and quantified using confocal microscopy. The viable/dead bacterial concentrations were estimated using propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR). The gene expressions for gtfB, sagP, arcA, argG, and argH were measured using real-time reverse transcriptase qPCR.

RESULTS

Carbohydrates and protein content with SF therapy were higher than non-LRG containing groups, while eDNA content was lower than other groups (p<0.05). Live bacterial proportions determined using confocal imaging with SF therapy were the lowest (p<0.05). The 2% Arg+LRG and SF therapy showed higher viable L. rhamnosus GG than 0.2% NaF+LRG (p<0.05). The dead S. mutans with SF therapy were higher than the other groups (p<0.05) with no difference from 2% Arg+0.2% NaF and 2% Arg+LRG (p>0.05). The SF therapy significantly downregulates gtfB and upregulates sagP, arcA, argG, argH gene expression (p<0.05).

CONCLUSION

Synbiotic-fluoride therapy effectuates multi-fold changes in the multi-species biofilm matrix and cellular components leading to superior ecological homeostasis than its individual contents, prebiotics (arginine), probiotic (L. rhamnosus GG), and fluorides (NaF).

CLINICAL SIGNIFICANCE

The ecological-based synbiotic-fluoride caries-preventive therapy aids in maintaining biofilm homeostasis to preempt/restore dysbiosis thereby sustaining dynamic-diverse health-associated microbial stability significant as a preventive regimen for high caries-risk patients.

Prospective Use of Probiotics to Maintain Astronaut Health during Spaceflight

Maintaining an astronaut's health during space travel is crucial. Multiple studies have observed various changes in the gut microbiome and physiological health. Astronauts on board the International Space Station (ISS) had changes in the microbial communities in their gut, nose, and skin. Additionally, immune system cell alterations have been observed in astronauts with changes in neutrophils, monocytes, and T-cells. Probiotics help tackle these health issues caused during spaceflight by inhibiting pathogen adherence, enhancing epithelial barrier function by reducing permeability, and producing an anti-inflammatory effect. When exposed to microgravity, probiotics demonstrated a shorter lag phase, faster growth, improved acid tolerance, and bile resistance. A freeze-dried Lactobacillus casei strain Shirota capsule was tested for its stability on ISS for a month and has been shown to enhance innate immunity and balance intestinal microbiota. The usage of freeze-dried spores of B. subtilis proves to be advantageous to long-term spaceflight because it qualifies for all the aspects tested for commercial probiotics under simulated conditions. These results demonstrate a need to further study the effect of probiotics in simulated microgravity and spaceflight conditions and to apply them to overcome the effects caused by gut microbiome dysbiosis and issues that might occur during spaceflight.

Antibacterial and Immunostimulatory Activity of Potential Probiotic Lactic Acid Bacteria Isolated from Ethiopian Fermented Dairy Products

Lactic acid bacteria (LAB) form a group of bacteria to which most probiotics belong and are commonly found in fermented dairy products. Fermented foods and beverages are foods made through desired microbial growth and enzymatic conversions of food components. In this study, 43 LAB were isolated from Ethiopian traditional cottage cheese, cheese, and yogurt and evaluated for their functional and safety properties as candidate probiotics. Twenty-seven isolates, representative of each fermented food type, were selected and identified to the species level. Limosilactobacillus fermentum was found to be the predominant species in all samples studied (70.4%), while 11.1% of isolates were identified as Lactiplantibacillus plantarum. All 27 isolates tested showed resistance to 0.5% bile salt, while 26 strains were resistant to pH 3. The LAB isolates were also evaluated for antagonistic properties against key pathogens, with strain-specific features observed for their antimicrobial activity. Five strains from cottage cheese (Lactiplantibacillus plantarum 54B, 54C, and 55A, Lactiplantibacillus pentosus 55B, and Pediococcus pentosaceus 95E) showed inhibitory activity against indicator pathogens that are key causes of gastrointestinal infections in Ethiopia, i.e., Escherichia coli, Salmonella enterica subsp. enterica var. Typhimurium, Staphylococcus aureus, Shigella flexneri, and Listeria monocytogenes. Strain-specific immunomodulatory activity monitored as nuclear factor kappa B (NF-κB) and interferon regulatory factor (IRF) activation was documented for Lactiplantibacillus plantarum 54B, 55A and P. pentosaceus 95E. Antibiotic susceptibility testing confirmed that all LAB isolates were safe concerning their antibiotic resistance profiles. Five isolates (especially Lactiplantibacillus plantarum 54B, 54C, and 55A, Lactiplantibacillus pentosus 55B, and P. pentosaceus 95E) showed promising results in all assays and are novel probiotic candidates of interest for clinical trial follow-up.

Bioinformatics and its role in the study of the evolution and probiotic potential of lactic acid bacteria

Due to their numerous well-established applications in the food industry, there have been many studies regarding the adaptation and evolution of lactic acid bacteria (LAB) in a wide variety of hosts and environments. Progress in sequencing technology and continual decreases in its costs have led to the availability of LAB genome sequence data. Bioinformatics has been central to the extraction of valuable information from these raw genome sequence data. This paper presents the roles of bioinformatics tools and databases in understanding the adaptation and evolution of LAB, as well as the bioinformatics methods used in the initial screening of LAB for probiotic potential. Moreover, the advantages, challenges, and limitations of employing bioinformatics for these purposes are discussed.

In Silico Evidence of the Multifunctional Features of Lactiplantibacillus pentosus LPG1, a Natural Fermenting Agent Isolated from Table Olive Biofilms

In recent years, there has been a growing interest in obtaining probiotic bacteria from plant origins. This is the case of Lactiplantibacillus pentosus LPG1, a lactic acid bacterial strain isolated from table olive biofilms with proven multifunctional features. In this work, we have sequenced and closed the complete genome of L. pentosus LPG1 using both Illumina and PacBio technologies. Our intention is to carry out a comprehensive bioinformatics analysis and whole-genome annotation for a further complete evaluation of the safety and functionality of this microorganism. The chromosomic genome had a size of 3,619,252 bp, with a GC (Guanine-Citosine) content of 46.34%. L. pentosus LPG1 also had two plasmids, designated as pl1LPG1 and pl2LPG1, with lengths of 72,578 and 8713 bp (base pair), respectively. Genome annotation revealed that the sequenced genome consisted of 3345 coding genes and 89 non-coding sequences (73 tRNA and 16 rRNA genes). Taxonomy was confirmed by Average Nucleotide Identity analysis, which grouped L. pentosus LPG1 with other sequenced L. pentosus genomes. Moreover, the pan-genome analysis showed that L. pentosus LPG1 was closely related to the L. pentosus strains IG8, IG9, IG11, and IG12, all of which were isolated from table olive biofilms. Resistome analysis reported the absence of antibiotic resistance genes, whilst PathogenFinder tool classified the strain as a non-human pathogen. Finally, in silico analysis of L. pentosus LPG1 showed that many of its previously reported technological and probiotic phenotypes corresponded with the presence of functional genes. In light of these results, we can conclude that L. pentosus LPG1 is a safe microorganism and a potential human probiotic with a plant origin and application as a starter culture for vegetable fermentations.

Antimicrobial potential of known and novel probiotics on in vitro periodontitis biofilms

Several oral diseases are characterized by a shift within the oral microbiome towards a pathogenic, dysbiotic composition. Broad-spectrum antimicrobials are often part of patient care. However, because of the rising antibiotic resistance, alternatives are increasingly desirable. Alternatively, supplying beneficial species through probiotics is increasingly showing favorable results. Unfortunately, these probiotics are rarely evaluated comparatively. In this study, the in vitro effects of three known and three novel Lactobacillus strains, together with four novel Streptococcus salivarius strains were comparatively evaluated for antagonistic effects on proximal agar growth, antimicrobial properties of probiotic supernatant and the probiotic's effects on in vitro periodontal biofilms. Strain-specific effects were observed as differences in efficacy between genera and differences within genera. While some of the Lactobacillus candidates were able to reduce the periodontal pathobiont A. actinomycetemcomitans, the S. salivarius strains were not. However, the S. salivarius strains were more effective against periodontal pathobionts P. intermedia, P. gingivalis, and F. nucleatum. Vexingly, most of the Lactobacillus strains also negatively affected the prevalence of commensal species within the biofilms, while this was lower for S. salivarius strains. Both within lactobacilli and streptococci, some strains showed significantly more inhibition of the pathobionts, indicating the importance of proper strain selection. Additionally, some species showed reductions in non-target species, which can result in unexpected and unexplored effects on the whole microbiome.

Assessing the Safety and Probiotic Characteristics of Lacticaseibacillus rhamnosus X253 via Complete Genome and Phenotype Analysis

Lacticaseibacillus rhamnosus is a generalist that can adapt to different ecological niches, serving as a valuable source of probiotics. The genome of L. rhamnosus X253 contains one chromosome and no plasmids, with a size of 2.99 Mb. Both single-copy orthologous gene-based phylogenetic analysis and average nucleotide identity indicated that dairy-derived L. rhamnosus X253 was most closely related to the human-intestine-derived strain L. rhamnosus LOCK908, rather than other dairy strains. The adaptation of L. rhamnosus X253 and the human-intestine-derived strain L. rhamnosus GG to different ecological niches was explained by structural variation analysis and COG annotation. Hemolytic assays, API ZYM assays, and antimicrobial susceptibility tests were performed to validate risk-related sequences such as virulence factors, toxin-encoding genes, and antibiotic-resistance genes in the genomes of L. rhamnosus X253 and GG. The results showed that L. rhamnosus GG was able to use L-fucose, had a higher tolerance to bile salt, and adhered better to CaCo-2 cells. In contrast, L. rhamnosus X253 was capable of utilizing D-lactose, withstood larger quantities of hydrogen peroxide, and possessed excellent antioxidant properties. This study confirmed the safety and probiotic properties of L. rhamnosus X253 via complete genome and phenotype analysis, suggesting its potential as a probiotic.

Iron in infectious diseases friend or foe?: The role of gut microbiota

Iron is a trace element involved in metabolic functions for all organisms, from microorganisms to mammalians. Iron deficiency is a prevalent health problem that affects billions of people worldwide, and iron overload could have some hazardous effect. The complex microbial community in the human body, also called microbiota, influences the host immune defence against infections. An imbalance in gut microbiota, dysbiosis, changes the host's susceptibility to infections by regulating the immune system. In recent years, the number of studies on the relationship between infectious diseases and microbiota has increased. Gut microbiota is affected by different parameters, including mode of delivery, hygiene habits, diet, drugs, and plasma iron levels during the lifetime. Gut microbiota may influence iron levels in the body, and iron overload and deficiency can also affect gut microbiota composition. Novel researches on microbiota shed light on the fact that the bidirectional interactions between gut microbiota and iron play a role in the pathogenesis of many diseases, especially infections. A better understanding of these interactions may help us to comprehend the pathogenesis of many infectious and metabolic diseases affecting people worldwide and following the development of more effective preventive and/or therapeutic strategies. In this review, we aimed to present the iron-mediated host-gut microbiota interactions, susceptibility to bacterial infections, and iron-targeted therapy approaches for infections.

Questioning the fetal microbiome illustrates pitfalls of low-biomass microbial studies

Whether the human fetus and the prenatal intrauterine environment (amniotic fluid and placenta) are stably colonized by microbial communities in a healthy pregnancy remains a subject of debate. Here we evaluate recent studies that characterized microbial populations in human fetuses from the perspectives of reproductive biology, microbial ecology, bioinformatics, immunology, clinical microbiology and gnotobiology, and assess possible mechanisms by which the fetus might interact with microorganisms. Our analysis indicates that the detected microbial signals are likely the result of contamination during the clinical procedures to obtain fetal samples or during DNA extraction and DNA sequencing. Furthermore, the existence of live and replicating microbial populations in healthy fetal tissues is not compatible with fundamental concepts of immunology, clinical microbiology and the derivation of germ-free mammals. These conclusions are important to our understanding of human immune development and illustrate common pitfalls in the microbial analyses of many other low-biomass environments. The pursuit of a fetal microbiome serves as a cautionary example of the challenges of sequence-based microbiome studies when biomass is low or absent, and emphasizes the need for a trans-disciplinary approach that goes beyond contamination controls by also incorporating biological, ecological and mechanistic concepts.

Food-Grade Bacteria Combat Pathogens by Blocking AHL-Mediated Quorum Sensing and Biofilm Formation

Disrupting bacterial quorum sensing (QS) signaling is a promising strategy to combat pathogenic biofilms without the development of antibiotic resistance. Here, we report that food-associated bacteria can interfere with the biofilm formation of a Gram-negative pathogenic bacterium by targeting its AHL (acyl-homoserine lactone) QS system. This was demonstrated by screening metabolic end-products of different lactobacilli and propionibacteria using Gram-negative and biofilm-forming Chromobacterium violaceum as the QS reporter and our anti-QS microscale screening platform with necessary modifications. The method was optimized in terms of the inoculation technique and the concentrations of D-glucose and L-tryptophan, two key factors controlling the synthesis of violacein, a purple pigment indicating the activation of the QS system in C. violaceum. These improvements resulted in ca. 16-times higher violacein yields and enabled revealing anti-QS effects of Lactobacillus acidophilus, Lentilactobacillus kefiri, Lacticaseibacillus rhamnosus and Propionibacterium freudenreichii, including new cheese-associated strains. Our findings also suggest that acetate and propionate excreted by these species are the main factors that interrupt the QS-mediated signaling and subsequent biofilm growth without affecting the cell viability of the C. violaceum reporter. Thus, the present study reports a revised anti-QS screening method to accurately define new bacteria with an ability to combat pathogens in a safe and sustainable way.

Designs and methodologies to recreate in vitro human gut microbiota models

The human gut microbiota is widely considered to be a metabolic organ hidden within our bodies, playing a crucial role in the host’s physiology. Several factors affect its composition, so a wide variety of microbes residing in the gut are present in the world population. Individual excessive imbalances in microbial composition are often associated with human disorders and pathologies, and new investigative strategies to gain insight into these pathologies and define pharmaceutical therapies for their treatment are needed. In vitro models of the human gut microbiota are commonly used to study microbial fermentation patterns, community composition, and host-microbe interactions. Bioreactors and microfluidic devices have been designed to culture microorganisms from the human gut microbiota in a dynamic environment in the presence or absence of eukaryotic cells to interact with. In this review, we will describe the overall elements required to create a functioning, reproducible, and accurate in vitro culture of the human gut microbiota. In addition, we will analyze some of the devices currently used to study fermentation processes and relationships between the human gut microbiota and host eukaryotic cells.

Graphic abstract

The Bioavailability of Glycyrrhizinic Acid Was Enhanced by Probiotic Lactobacillus rhamnosus R0011 Supplementation in Liver Fibrosis Rats

Glycyrrhizinic acid (GL) is clinically applied to treat liver injury, and the bioavailability of orally administered GL is closely related to the gut microbiota. Therefore, the dysbiosis of gut flora in liver injury could significantly influence GL bioavailability. Still, less is known about the impact of probiotic supplementation on the bio-absorption process of oral medication, especially under a pathological state. Herein, probiotic L. rhamnosus R0011 (R0011) with a high viability in the harsh gastrointestinal environment was selected, and the effect of R0011 on the GL bioavailability in rats was investigated. Four groups of rats (n = 6 per group) were included: the normal group (N group), the normal group supplemented with R0011 (NLGG group), CCl4-induced chronic liver injury model (M group), and the model group supplemented with R0011 (MLGG group). Our results showed that liver injury was successfully induced in the M and MLGG groups via an intraperitoneal injection of 50% (v/v) CCl4 solution. Healthy rats supplemented with R0011 could increase the bioavailability of GL by 1.4-fold compared with the normal group by plasma pharmacokinetic analysis. Moreover, the GL bioavailability of MLGG group was significantly increased by 4.5-fold compared with the model group. R0011 directly improved gut microbial glucuronidase and downregulated the host intestinal drug transporter gene expression of multidrug resistance protein 2 (MRP2). More critically, R0011 restored the gut microbiota composition and regulated the metabolic function, significantly enhancing the microbial tryptophan metabolic pathway compared with the pathological state, which may indirectly promote the bioavailability of GL. Overall, these data may provide possible strategies by which to address the low bioavailability of traditional medicine through probiotic intervention.

A review on pilus assembly mechanisms in Gram-positive and Gram-negative bacteria

The surface of Gram-positive and Gram-negative bacteria contains long hair-like proteinaceous protrusion known as pili or fimbriae. Historically, pilin proteins were considered to play a major role in the transfer of genetic material during bacterial conjugation. Recent findings however elucidate their importance in virulence, biofilm formation, phage transduction, and motility. Therefore, it is crucial to gain mechanistic insights on the subcellular assembly of pili and the localization patterns of their subunit proteins (major and minor pilins) that aid the macromolecular pilus assembly at the bacterial surface. In this article, we review the current knowledge of pilus assembly mechanisms in a wide range of Gram-positive and Gram-negative bacteria, including subcellular localization patterns of a few pilin subunit proteins and their role in virulence and pathogenesis.

Bacteriocin: A natural approach for food safety and food security

The call to cater for the hungry is a worldwide problem in the 21st century. Food security is the utmost prime factor for the increasing demand for food. Awareness of human health when using chemical preservatives in food has increased, resulting in the use of alternative strategies for preserving food and enhancing its shelf-life. New preservatives along with novel preservation methods have been instigated, due to the intensified demand for extended shelf-life, along with prevention of food spoilage of dairy products. Bacteriocins are the group of ribosomally synthesized antimicrobial peptides; they possess a wide range of biological activities, having predominant antibacterial activity. The bacteriocins produced by the lactic acid bacteria (LAB) are considered to be of utmost importance, due to their association with the fermentation of food. In recent times among various groups of bacteriocins, leaderless and circular bacteriocins are gaining importance, due to their extensive application in industries. These groups of bacteriocins have been least studied as they possess peculiar structural and biosynthetic mechanisms. They chemically possess N-to-C terminal covalent bonds having a predominant peptide background. The stability of the bacteriocins is exhibited by the circular structure. Up till now, very few studies have been performed on the molecular mechanisms. The structural genes associated with the bacteriocins can be combined with the activity of various proteins which are association with secretion and maturation. Thus the stability of the bacteriocins can be used effectively in the preservation of food for a longer period of time. Bacteriocins are thermostable, pH-tolerant, and proteolytically active in nature, which make their usage convenient to the food industry. Several research studies are underway in the domain of biopreservation which can be implemented in food safety and food security.

Infant behavioral state and stool microbiome in infants receiving Lactocaseibacillus rhamnosus GG in formula: randomized controlled trial

Background

Our aim was to evaluate infant behavioral state, stool microbiome profile and calprotectin in infants with infantile colic receiving a partially hydrolyzed protein formula with or without added Lacticaseibacillus (formerly Lactobacillus) rhamnosus GG (LGG).

Methods

In this single-center, double-blind, controlled, parallel, prospective study, term infants (14–28 days of age) identified with colic (using modified Wessel’s criteria: cried and/or fussed ≥ 3 h/day for ≥ 3 days/week, in a one-week period) were randomized to receive one of two formulas over a three-week feeding period: marketed partially hydrolyzed cow’s milk-based infant formula (PHF, n = 35) or a similar formula with added LGG (PHF-LGG, n = 36). Parent-reported infant behavior was recorded at three time points (Study Days 2–4, 10–12, and 18–20). Duration (hours/day) of crying/fussing (averaged over each three-day period) was the primary outcome. Stool samples were collected at Baseline and Study End (Days 19–21) to determine stool LGG colonization (by qPCR) and microbial abundance (using 16S rRNA gene sequencing) and calprotectin (μg/g).

Results

Duration of crying/fussing (mean ± SE) decreased and awake/content behavior increased over time with no significant group differences over the course of the study. There were no group differences in the percentage of infants who experienced colic by study end. Colic decreased by Study End vs Baseline in both groups. Change in fecal calprotectin also was similar between groups. Comparing Study End vs Baseline, LGG abundance was greater in the PHF-LGG group (P < 0.001) whereas alpha diversity was greater in the PHF group (P = 0.022). Beta diversity was significantly different between PHF and PHF-LGG at Study End (P = 0.05). By study end, relative abundance of L. rhamnosus was higher in the PHF-LGG vs PHF group and vs Baseline.

Conclusions

In this pilot study of infants with colic, both study formulas were well tolerated. Crying/fussing decreased and awake/content behavior increased in both study groups over the course of the study. Study results demonstrate a successful introduction of the probiotic to the microbiome. The partially hydrolyzed protein formula with added LGG was associated with significant changes in the gut microbiome.

Trial registration

ClinicalTrials.gov, ClinicalTrials.gov Identifier: NCT02340143. Registered 16/01/2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03647-x.