Screening of probiotic activities of forty-seven strains of Lactobacillus spp. by in vitro techniques and evaluation of the colonization ability of five selected strains in humans

Distal gut colonization by oral bacteria during intensive chemotherapy: direct evidence from strain-level analysis of paired samples

Oral bacteria have been found in the colon in pathologies such as inflammatory bowel disease. To ascertain niche coalescence, 2 elements are essential: (i) paired oral/fecal samples and (ii) strain-level resolution. We profiled the microbiota in 283 samples from 39 patients undergoing intensive chemotherapy at baseline (saliva: 49, plaque: 51, stool: 43), week 2 (saliva: 18, plaque: 17, stool: 17), week 3 (saliva: 18, plaque: 21, stool: 21), and week 4 (saliva: 8, plaque: 10, stool: 10) of chemotherapy. Through strain-level analysis of paired samples, we demonstrate strong evidence for a breakdown of niche separation in most patients. The extent of overlap increased with time, particularly in patients with intestinal mucositis. Our findings provide definitive evidence for ectopic colonization of the distal gut by oral bacteria in a disease state, likely facilitated by intestinal mucositis. Microbiota contribution by the mouth to the colon may have consequences for the host.

Functional efficacy of Enterococcus faecium HN4 and Lactobacillus delbrueckii HN5 strains isolated from human milk

AIMS

The microbiota of human milk is described at length; however, variation in different bacterial genera in milk has been reported. Here, breast milk samples from Indian mothers were used to target bacterial species from the pool of microbial communities in human milk with probiotic potential.

MATERIALS AND METHODS

A culture-dependent technique was used to isolate bacterial cultures, and their physiological and functional properties were appraised.

RESULTS

Two bacterial cultures, E. faecium HN4 and L delbrueckii HN5, were identified as showing considerable tolerance to acid and bile conditions with 73.0-87.0% survival. The cultures showed other in vitro beneficial properties.

CONCLUSION

The study highlights the presence of potential probiotics in human milk that could be investigated for further use.

Comparison of Storage Stability and In Vitro Digestion of Rice Flour-Based Yogurt Alternatives Made with Lactobacillus rhamnosus Lgg to Milk-Based Yogurt

Production of plant-based products is still on the rise. There is a need for new plant-based dairy alternatives in the food market due to lactose intolerance, allergens to dairy and nuts and a rise in gluten-free products. Rice is a key source for these types of products because it is hypoallergenic. This study focused on the comparison storage stability and in vitro digestion of milk-based yogurt (MY) to yogurt alternatives (YA) made with four different rice flours. YAs and MY were prepared using L. delbrueckii and S. thermophilus for fermentation and L. rhamnosus (LGG) as a probiotic. Samples were stored refrigerated for up to 28 days and analyzed for titratable acidity, pH, color, syneresis, viscosity and bacterial counts every seven days. Probiotic survivability was tested under simulated gastric and intestinal conditions. YAs had lower syneresis than MY. There were few changes in color over time. Titratable acidity was lower in YAs (0.1 to 0.5%) than in MY (1%) while pH decreased in all samples during storage. Bacteria counts were stable throughout storage in all samples. MY had higher counts of LGG at the beginning of storage which significantly decreased during exposure to in vitro gastric conditions. Under in vitro intestinal conditions, both the white rice flour YAs and the MY retained the highest levels of LGG. This study indicated that it is possible for YAs made with rice flour to be stable overtime and with survivability of probiotic bacteria under gastric conditions.

Rosaceae Honey: Antimicrobial Activity and Prebiotic Properties

Background: Flowering members of the globally diffused Rosaceae family include popular plants, such as apple, almond, and cherry, which play a fundamental role as honeybee nectariferous and polleniferous agents. Through the production of honey, these plants can also play an indirect role in the prevention and treatment of many diseases, including infections, fighting the occurrence of resistant microorganisms, and concurrently stimulating the growth of beneficial bacteria. Objectives: This study focused on the effect of some Rosaceae plants' honey, including hawthorn, cherry, raspberry, almond, and apple, against the pathogens Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus. Results: Results demonstrated the honey's ability to impair swimming motility. A crystal violet test indicated that honey could inhibit the formation and stabilization of biofilms, with inhibition rates up to 59.43% for immature biofilms (showed by apple honey against A. baumannii) and 39.95% for sessile bacterial cells in mature biofilms (when we used cherry honey against S. aureus). In the test with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cherry and apple honey were the most effective in inhibiting sessile cell metabolism honey in both immature (56.47% cherry honey vs. K. pneumoniae) and mature biofilms (54.36% apple honey vs. A. baumannii). Honey stimulated the growth of Lactobacillus bulgaricus, Lacticaseibacillus casei Shirota, Lactobacillus gasseri, Lacticaseibacillus plantarum, and Lacticaseibacillus rhamnosus; hawthorn, raspberry, and almond honey significantly increased the in vitro adhesion capacity of L. bulgaricus and L. casei Shirota. Tests with probiotic supernatants demonstrated honey's ability to inhibit the biofilm formation and metabolism of the pathogens. Conclusions: Our results encourage further studies to assess the potential application of Rosaceae honey for food preservation and in the health field, as it could fight the antimicrobial resistance of food and clinical pathogens, and potentially enhance the host's gut wellness. The use of honey for nanotechnological and biotechnological approaches could be suggested too.

Harnessing the Power of Donkey's Milk and Homemade Pickles: Unveiling Oxalate-Degrading Probiotics and Their Heat-Killed Cells as Antiadipogenic Agents in 3T3-L1 Adipocytes

Gut microbial dysbiosis is associated with the development of critical clinical conditions of metabolic syndrome (obesity, type II diabetes), and calcium oxalate kidney stones. The human gut microbial eubiosis with functional probiotics and their heat-killed cells of lactic acid bacteria (LAB) is considered the current therapy for metabolic syndrome (MS). In accordance with this, our study aimed to isolate oxalate-degrading, cholesterol-lowering, and anti-adipogenic bacterial strains from raw donkey's milk and homemade fermented pickles. Nine LAB strains with potential in vitro oxalate degrading, α-glucosidase inhibiting, and cholesterol-lowering activities were pre-screened from fourteen isolates. Further, the heat-killed cells of selected strains were evaluated for anti-adipogenic activity in murine 3T3-L1 adipocytes. This activity was examined by studying the lipid storage, gene, and protein expression of adipogenic and lipogenic transcription factors. Subsequently, four potential isolates demonstrated a significant reduction in lipid storage by limiting adipogenesis (reducing C/EBPα, PPARγ expression), lipid transportation (downregulating aP2 expression), and lipogenesis (reducing PLIN-1 expression). These effective isolates were characterized using 16S rRNA molecular sequencing, and were identified as closest relatives to the Enterococcus (RRLA5, RRLA1, and RRLD6) and Lactobacillus (RRLM2) genera. Further, they displayed good survivability under in vitro gastric conditions and non-haemolytic activity. Taken together, the live cells of effective isolates depicted significant in vitro oxalate degradation, and their heat-killed cells demonstrated anti-adipogenic activity through downregulating the adipogenesis and lipogenesis. Moreover, future preclinical animal model studies on the synergistic role of probiotics and their heat-killed cells in disease prevention through gut microbial modulation could provide evidence as a biotherapeutic agent.

Probiotic, Paraprobiotic, and Postbiotic Activities of Lactiplantibacillus plantarum KUNN19-2 Against Non-Typhoidal Salmonella Serovars

Non-typhoidal salmonellosis (NTS) caused by multidrug-resistant (MDR) Salmonella enterica is a significant public health concern worldwide. Probiotics offer a potential alternative to antibiotics in many infectious diseases, including NTS. However, using living bacteria raises safety concerns in clinical settings, especially in the immunocompromised host. This study compared the anti-Salmonella and immunomodulatory effects between viable (probiotics) and heat-killed (paraprobiotics) lactic acid bacteria Lactiplantibacillus plantarum KUNN19-2 (KUNN19-2), isolated from Thai-style fermented pork (Nham), against several strains of MDR Salmonella. Only viable KUNN19-2 and its cell-free supernatant directly inhibited Salmonella growth by spot-on lawn and agar well diffusion assays. A significant reduction in Salmonella numbers in the co-culture assay with viable KUNN19-2 was observed at 12-14 h after the incubation. Viable and heat-killed KUNN19-2 exhibited moderate adhesion to human colonic epithelium (T84) cells. Pretreatment with either form of KUNN19-2 enhanced macrophage (RAW264.7) phagocytic activity against Salmonella and upregulated pro-inflammatory genes (Mip-2 and Nos2) and anti-inflammatory gene (IL10) expression, with viable KUNN19-2 showing a more potent effect. Collectively, viable KUNN19-2 can directly inhibit Salmonella growth. However, viable and heat-killed KUNN19-2 can modulate gut immunity against Salmonella infection, suggesting that paraprobiotic KUNN19-2 may serve as an alternative treatment against MDR Salmonella through host immune modulation.

Antimicrobial activity of Lactobacillus casei on Staphylococcus pseudintermedius isolates

BACKGROUND

Antimicrobial resistance is increasing each year. For example, in 2019 it was directly responsible for an estimated >1 million deaths. Additionally, the development of new drugs is much slower, generating enormous concerns about responses to infection in the future health scenario. Therefore, probiotics have emerged as an alternative to antibiotics.

OBJECTIVES

This study aimed to isolate and identify a Lactobacillus casei from healthy canine skin and investigate its antimicrobial effect on isolates of Staphylococcus pseudintermedius originating from dogs with pyoderma.

MATERIALS AND METHODS

L. casei was isolated from skin samples collected with a sterile cotton swab from the inner pinnae of healthy dogs. It was then cultured, identified using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry, and tested against 30 different clinical isolates and one American Type Culture Collection strain of S. pseudintermedius using the spot-on-the-lawn technique. Its safety was assessed through a modified Kirby-Bauer disc diffusion susceptibility test.

RESULTS

L. casei inhibited the growth of all isolates of S. pseudintermedius. The mean value of the inhibition halo of all isolates was 11.3 mm. A significant positive correlation (Pearson's linear correlation = 0.444; p = 0.014) was noted between the inhibitory halos formed by L. casei on the S. pseudintermedius isolates and the halos produced by the tested antimicrobial discs on the same isolates. The L. casei strain demonstrated sensitivity to all tested antimicrobials.

CONCLUSIONS AND CLINICAL RELEVANCE

The study indicates that using commensal bacteria from canine skin, specifically L. casei, to control bacterial infections caused by S. pseudintermedius can be a promising complementary or alternative therapy to antibiotics relevant to animal and human health.

Lower Cadmium Bioavailability and Toxicity in Japonica Rice than in Indica Rice: Mechanisms and Health Implications

Cadmium (Cd) is efficiently transferred from soil to food crops, notably rice. Research indicates that indica rice grains may accumulate more Cd than japonica cultivars; however, differences in Cd bioavailability (the fraction of ingested rice Cd absorbed into the systemic circulation) and toxicity remain unexplored, thus hindering a comprehensive understanding of exposure and health risks. To address this, a mouse bioassay was conducted to evaluate the relative bioavailability (RBA) of Cd in 35 samples each of japonica and indica rice, determining which type exhibits lower Cd bioavailability. The results revealed a significantly lower mean Cd-RBA in japonica rice (49.6 ± 7.8%) compared to indica rice (65.6 ± 12.2%). This disparity is attributed primarily to the 1.25- and 1.37-fold higher concentrations of calcium (Ca) and iron (Fe) in japonica rice, which enhanced Ca and Fe absorption from the intestine and reduced duodenal expression of Ca and Fe transporters by 1.8-5.9 times in mice consuming japonica rice, thereby decreasing Cd transcellular transport. Additionally, japonica rice consumption promoted beneficial gut probiotics (Bifidobacterium pseudolongum and Lactobacillus reuteri) and metabolites, particularly short-chain fatty acids and peptides, potentially increasing mineral absorption and reducing Cd uptake. Moreover, mice fed japonica rice exhibited 1.35-1.47 times higher gene expression of intestinal tight junctions, enhancing intestinal barrier function and reducing extracellular Cd transport. Consequently, consuming Cd-containing japonica rice was associated with lower oxidative stress, inflammation, and cancer risks in mice compared to indica rice consumption. This study significantly enhances our understanding on the health risks associated with Cd in different rice subspecies.

Screening of Lactic Acid Bacteria Isolated from Fermented Cowpea and Optimization of Biomass Production Conditions

Considering the four characteristics of strains, including acid production, acid tolerance, salt tolerance, and nitrite degradation rate, Pediococcus pentosaceus NCU006063 was selected as the fermentation agent, and the medium composition of Pediococcus pentosaceus NCU006063 was optimized using Plackett-Burman and central composite rotational design. Three of the seven factors studied in the Plackett-Burman design significantly affected the viable counts. A central composite rotational design was used to optimize the significant factors and generate response surface plots. Using these response surface plots and point predictions, the optimal factors were soy peptone (38.75 g/L), FeSO4 (0.10 g/L), and VB7 (20 g/L). In addition, the optimized incubation conditions were a temperature of 39 °C, an initial pH value of 7, and an inoculation volume of 3%. The optimized biomass production parameters were a constant pH (6.5), neutralizing agent types (25% NH3·H2O), and gas types (N2). Under these optimal conditions, Pediococcus pentosaceus NCU006063 exhibited a great viable bacterial count of up to 2.65 × 1010 CFU/mL, which is 9.71 times higher than that of MRS broth (2.73 × 109 CFU/mL). These results demonstrated that the Pediococcus pentosaceus NCU006063 strain has excellent potential as a fermentation agent and can provide a theoretical base for the in-depth exploration and promotion of fermented cowpea use in human diets.

Selection of Lactobacillus strains from native chicken feces for the fermentation of purple onion (Allium cepa L.) as an antibiotic alternative against Salmonella spp. in chickens

Background

The increasing prevalence of antibiotic resistance in poultry pathogens necessitates the development of sustainable alternatives to antibiotics. Probiotics, particularly Lactobacillus spp., have shown promise in combating bacterial infections in poultry. Purple onion extract (OE) possesses antibacterial properties and can potentially enhance the probiotic efficacy of Lactobacillus strains.

Aim

This study aimed to develop a biological product based on Lactobacillus-fermented OE (LFOE) as a sustainable alternative to antibiotics for the control of Salmonella-induced diarrhea in poultry.

Methods

Lactobacillus strains were isolated from native free-range chicken feces and screened for their antibacterial activity against Salmonella pullorum NCTC10705 and Salmonella typhimurium FC13827, as well as their survival rate in OE. Six promising strains were selected and further characterized for their ability to ferment OE and their co-aggregation ability against the pathogenic bacteria using scanning electron microscopy (SEM). 16S rRNA gene sequencing was performed for bacterial identification. The selected strain was used for fermentation in OE, and the resulting product was freeze-dried into a biological preparation. In vivo studies in chicks were conducted to assess the safety and intestinal persistence of LFOE.

Results

From an initial pool of 68 Lactobacillus strains, six promising candidates (L. plantarum 1582, L. plantarum WCFS1, L. plantarum JDM1, L. acidophilus NCFM, L. agilis DSM 20509, and L. agilis La3) were selected based on their antibacterial activity and high survival rate in OE. SEM confirmed the ability of these strains to ferment OE and co-aggregate with pathogenic bacteria. 16S rRNA gene sequencing confirmed their taxonomic identity as Lactobacillus. L. plantarum 1582, selected for its superior probiotic properties, was used to ferment LFOE, which proved safe for chicks and demonstrated the strain's ability to survive temporarily in the intestine.

Conclusion

This study successfully developed a biopreparation based on LFOE as a potential alternative to antibiotics for the control of Salmonella-induced diarrhea in poultry. However, regular re-supplementation is required to maintain probiotic efficacy due to the transient nature of intestinal colonization.

Probiotic Characteristics and the Anti-Inflammatory Effects of Lactiplantibacillus plantarum Z22 Isolated from Naturally Fermented Vegetables

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases.

Molecular characterization and multifunctional evaluation of lactic acid bacteria isolated from traditional sourdough

The primary objective of this study was to characterize lactic acid bacteria (LAB) strains derived from sourdough for possible utilization as functional starters to produce sourdough and various cereal-based fermented foods. A total of 350 autochthonous LAB strains were isolated from 65 Type I sourdough samples and characterized using six random amplified polymorphic DNA (RAPD) primers at intra- and interspecific levels. Species identification of selected strains representing distinct clusters from RAPD analysis was performed based on the 16S rRNA region. The LAB strains were identified as Companilactobacillus crustorum (n = 135), Levilactobacillus brevis (n = 125), Latilactobacillus curvatus (n = 40), Companilactobacillus paralimentarius (n = 32), and Lactiplantibacillus plantarum (n = 18). A total of 66 LAB strains were selected for technological characterization along with two commercial strains. The characterization involved acidity development, EPS production potential, leavening activity, and growth abilities under harsh conditions. Principle component analysis (PCA) identified 2 Lp. plantarum and 14 Lev. brevis strains as the most relevant technologically. Among them, Lp. plantarum L35.1 and Lev. brevis L37.1 were resistant to tetracycline. Evaluation of probiotic characteristics (survival in pH 2.5 and bile presence, auto aggregation capacity, hydrophobic activity, antioxidant activity, antimicrobial activity) by PCA identified four strains with relevance to Lactobacillus rhamnosus GG (LGG), which were further selected for in vitro digestion assays. Lactiplantibacillus plantarum L7.8, Lev. brevis L55.1, and L62.2 demonstrated similar viability indices to LGG, along with increased auto aggregation capacity and antioxidant activity. These strains are promising as candidate starters for producing sourdough and sourdough-related fermented food products.

Antibacterial Activity and Prebiotic Properties of Six Types of Lamiaceae Honey

Our work investigated the antimicrobial and prebiotic properties of basil, mint, oregano, rosemary, savory, and thyme honey. The potential antimicrobial action, assessed against the pathogens Acinetobacter baumannii, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus, evidenced the capacity of the honey to influence the pathogenic hydrophobicity and hemolytic activities. Honey inhibited pathogen biofilms, acting especially on the mature biofilms, with inhibition rates of up to 81.62% (caused by the presence of mint honey on L. monocytogenes). S. aureus biofilms were the most susceptible to the presence of honey, with inhibition rates up of to 67.38% in the immature form (caused by basil honey) and up to 80.32% in the mature form (caused by mint honey). In some cases, the amount of nuclear and proteic material, evaluated by spectrophotometric readings, if also related to the honey's biofilm inhibitory activity, let us hypothesize a defective capacity of building the biofilm scaffold or bacterial membrane damage or an incapability of producing them for the biofilm scaffold. The prebiotic potentiality of the honey was assessed on Lacticaseibacillus casei Shirota, Lactobacillus gasseri, Lacticaseibacillus paracasei subsp. paracasei, and Lacticaseibacillus rhamnosus and indicated their capacity to affect the whole probiotic growth and in vitro adhesive capacity, as well as the antioxidant and cytotoxic abilities, and to inhibit, mainly in the test performed with the L. casei Shirota, L. gasseri, and L. paracasei supernatants, the immature biofilm of the pathogens mentioned above.

Strain-Dependent Adhesion Variations of Shouchella clausii Isolated from Healthy Human Volunteers: A Study on Cell Surface Properties and Potential Probiotic Benefits

The probiotic potential of Shouchella clausii is widely recognized, but little is known about its adhesive properties. Hence, this study aims to investigate the adhesion potential and cell surface properties of four human-origin S. clausii strains (B619/R, B603/Nb, B106, and B637/Nm). We evaluated epithelial adhesion, Extracellular Matrix (ECM) binding, aggregation ability, and cell surface hydrophobicity and used genome analysis for validation. Our results demonstrate that adhesion capability is a strain-specific attribute, with significant variations observed among the four strains. B619/R, B603/Nb, and B106 displayed stronger adhesion properties than B637/Nm. Supplementary adhesion assays showed that B637/Nm displayed high hydrophobicity, significant auto-aggregation, and significant mucin-binding abilities. Conversely, B619/R, B603/Nb, and B106 had mildly hydrophobic surfaces and low aggregation abilities. Genome annotation revealed the presence of various adhesion proteins in four strains. Notably, the reduced adhesion potential of B637/Nm was supported by the absence of the cell wall surface anchor family protein (LPxTG motif), which is crucial for interactions with intestinal epithelial cells or mucus components. Further, docking studies provided insights into the interaction of adhesion proteins with gut mucins. These findings contribute to a better understanding of how S. clausii strains interact with the gut environment, facilitating the development of probiotic formulations tailored for improved gut health and well-being.

Restriction of growth and biofilm formation of ESKAPE pathogens by caprine gut-derived probiotic bacteria

The accelerated rise in antimicrobial resistance (AMR) poses a significant global health risk, necessitating the exploration of alternative strategies to combat pathogenic infections. Biofilm-related infections that are unresponsive to standard antibiotics often require the use of higher-order antimicrobials with toxic side effects and the potential to disrupt the microbiome. Probiotic therapy, with its diverse benefits and inherent safety, is emerging as a promising approach to prevent and treat various infections, and as an alternative to antibiotic therapy. In this study, we isolated novel probiotic bacteria from the gut of domestic goats (Capra hircus) and evaluated their antimicrobial and anti-biofilm activities against the 'ESKAPE' group of pathogens. We performed comprehensive microbiological, biochemical, and molecular characterizations, including analysis of the 16S-rRNA gene V1-V3 region and the 16S-23S ISR region, on 20 caprine gut-derived lactic acid bacteria (LAB). Among these, six selected Lactobacillus isolates demonstrated substantial biofilm formation under anaerobic conditions and exhibited robust cell surface hydrophobicity and autoaggregation, and epithelial cell adhesion properties highlighting their superior enteric colonization capability. Notably, these Lactobacillus isolates exhibited broad-spectrum growth inhibitory and anti-biofilm properties against 'ESKAPE' pathogens. Additionally, the Lactobacillus isolates were susceptible to antibiotics listed by the European Food Safety Authority (EFSA) within the prescribed Minimum Inhibitory Concentration limits, suggesting their safety as feed additives. The remarkable probiotic characteristics exhibited by the caprine gut-derived Lactobacillus isolates in this study strongly endorse their potential as compelling alternatives to antibiotics and direct-fed microbial (DFM) feed supplements in the livestock industry, addressing the escalating need for antibiotic-free animal products.

Investigating Safety and Technological Traits of a Leading Probiotic Species: Lacticaseibacillus paracasei

Lacticaseibacillus spp. are genetically close lactic acid bacteria species widely used in fermented products for their technological properties as well as their proven beneficial effects on human and animal health. This study, the first to include such a large collection of heterogeneous isolates (121) obtained from international collections belonging to Lacticaseibacillus paracasei, aimed to characterize the safety traits and technological properties of this important probiotic species, also making comparisons with other genetically related species, such as Lacticaseibacillus casei and Lacticaseibacillus zeae. These strains were isolated from a variety of heterogeneous sources, including dairy products, sourdoughs, wine, must, and human body excreta. After a preliminary molecular characterization using repetitive element palindromic PCR (Rep-PCR), Random Amplification of Polymorphic DNA (RAPD), and Sau-PCR, particular attention was paid to safety traits, evaluating antibiotic resistance profiles, biogenic amine (BA) production, the presence of genes related to the production of ethyl carbamate and diaminobenzidine (DAB), and multicopper oxidase activity (MCO). The technological characteristics of the strains, such as the capability to grow at different NaCl and ethanol concentrations and different pH values, were also investigated, as well as the production of bacteriocins. From the obtained results, it was observed that strains isolated from the same type of matrix often shared similar genetic characteristics. However, phenotypic traits were strain-specific. This underscored the vast potential of the different strains to be used for various purposes, from probiotics to bioprotective and starter cultures for food and feed production, highlighting the importance of conducting comprehensive evaluations to identify the most suitable strain for each purpose with the final aim of promoting human health.

Understanding the influence of the microbiome on childhood infections

INTRODUCTION

The microbiome is known to have a substantial impact on human health and disease. However, the impacts of the microbiome on immune system development, susceptibility to infectious diseases, and vaccine-elicited immune responses are emerging areas of interest.

AREAS COVERED

In this review, we provide an overview of development of the microbiome during childhood. We highlight available data suggesting that the microbiome is critical to maturation of the immune system and modifies susceptibility to a variety of infections during childhood and adolescence, including respiratory tract infections, Clostridioides difficile infection, and sexually transmitted infections. We discuss currently available and investigational therapeutics that have the potential to modify the microbiome to prevent or treat infections among children. Finally, we review the accumulating evidence that the gut microbiome influences vaccine-elicited immune responses among children.

EXPERT OPINION

Recent advances in sequencing technologies have led to an explosion of studies associating the human microbiome with the risk and severity of infectious diseases. As our knowledge of the extent to which the microbiome influences childhood infections continues to grow, microbiome-based diagnostics and therapeutics will increasingly be incorporated into clinical practice to improve the prevention, diagnosis, and treatment of infectious diseases among children.

Development of a single nucleotide polymorphism-based strain-identified method for Streptococcus thermophilus CICC 6038 and Lactobacillus delbrueckii ssp. bulgaricus CICC 6047 using pan-genomics analysis

The health benefits conferred by probiotics is specific to individual probiotic strains, highlighting the importance of identifying specific strains for research and production purposes. Streptococcus thermophilus CICC 6038 and Lactobacillus delbrueckii ssp. bulgaricus CICC 6047 are exceedingly valuable for commercial use with an excellent mixed-culture fermentation. To differentiate these 2 strains from other S. thermophilus and L. delbrueckii ssp. bulgaricus, a specific, sensitive, accurate, rapid, convenient, and cost-effective method is required. In this study, we conducted a pan-genome analysis of S. thermophilus and L. delbrueckii ssp. bulgaricus to identify species-specific core genes, along with strain-specific SNPs. These genes were used to develop suitable PCR primers, and the conformity of sequence length and unique SNPs was confirmed by sequencing for qualitative identification at the strain level. The results demonstrated that SNPs analysis of PCR products derived from these primers could distinguish CICC 6038 and CICC 6047 accurately and reproducibly from the other strains of S. thermophilus and L. delbrueckii ssp. bulgaricus, respectively. The strain-specific PCR method based on SNPs herein is universally applicable for probiotics identification. It offers valuable insights into identifying probiotics at the strain level that is fit-for-purpose in quality control and compliance assessment of commercial dairy products.

Cereus jamacaru DC. (mandacaru) fruit as a source of lactic acid bacteria with in vitro probiotic-related characteristics and its protective effects on Pediococcus pentosaceus during lyophilization and refrigeration storage

This study isolated and identified autochthonous lactic acid bacteria (LAB) from mandacaru fruit and evaluated their potential probiotic and technological aptitudes in vitro, as well as the protective effects of freeze-dried mandacaru fruit on the most promising LAB isolate during lyophilization and refrigeration storage. Initially, 212 colonies were isolated from mandacaru fruit, and 34 were preliminarily identified as LAB. Thirteen isolates identified by 16S-rRNA sequencing as Pediococcus pentosaceus were negative for DNase, gelatinase, hemolytic, and biogenic amine production. The selected isolates showed proteolytic activity, diacetyl and exopolysaccharide production, and good tolerance to different NaCl concentrations while having low cellular hydrophobicity and antagonistic activity against pathogens. The survival of isolates sharply decreased after 3 h of exposure to pH 2 and had a good tolerance to 1 % bile salt. A principal component analysis selected P. pentosaceus 57 as the most promising isolate based on the examined technological and probiotic-related physiological properties. This isolate was lyophilized with mandacaru fruit and stored under refrigeration for 90 days. P. pentosaceus 57 lyophilized with mandacaru fruit had high viable cell counts (9.69 ± 0.03 log CFU/mL) and >50 % of physiologically active cells at 90 days of refrigeration storage. The results indicate that mandacaru fruit is a source of P. pentosaceus with aptitudes to be explored as potential probiotic and technological characteristics of interest for the food industry, besides being a good candidate for use in lyophilization processes and refrigeration storage of LAB due to its cryoprotective effects.

Woodfordia fruticosa fermented with lactic acid bacteria impact on foodborne pathogens adhesion and cytokine production in HT-29 cells

Introduction

The study into the interplay between foodborne pathogens and human health, particularly their effects on intestinal cells, is crucial. The importance of lactic acid bacteria (LAB) in promoting a healthy balance of gut microbiota, inhibiting harmful bacteria, and supporting overall gastrointestinal health is becoming more apparent.

Methods

Our study delved into the impact of fermenting Woodfordia fruticosa (WF), a plant known for its antimicrobial properties against gastrointestinal pathogens, with LAB. We focused on the influence of this fermentation process on the binding of foodborne pathogens to the gut lining and cytokine production, aiming to enhance gut health and control foodborne infections in HT-29 cells.

Results and discussion

Post-fermentation, the WF exhibited improved antimicrobial effects when combined with different LAB strains. Remarkably, the LAB-fermented WF (WFLC) substantially decreased the attachment of pathogens such as L. monocytogenes (6.87%  ±  0.33%) and V. parahaemolyticus (6.07%  ±  0.50%) in comparison to the unfermented control. Furthermore, WFLC was found to upregulate IL-6 production in the presence of pathogens like E. coli O157:H7 (10.6%) and L. monocytogenes (19%), suggesting it may activate immune responses. Thus, LAB-fermented WF emerges as a potential novel strategy for fighting foodborne pathogens, although additional studies are warranted to thoroughly elucidate WF's phytochemical profile and its contribution to these beneficial outcomes.

Detection of oxalyl-CoA decarboxylase (oxc) and formyl-CoA transferase (frc) genes in novel probiotic isolates capable of oxalate degradation in vitro

Oxalate degradation is one of lactic acid bacteria's desirable activities. It is achieved by two enzymes, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). The current study aimed to screen 15 locally isolated lactic acid bacteria to select those with the highest oxalate degradation ability. It also aimed to amplify the genes involved in degradation. MRS broth supplemented with 20 mM sodium oxalate was used to culture the tested isolates for 72 h. This was followed by an enzymatic assay to detect remaining oxalate. All isolates showed oxalate degradation activity to variable degrees. Five isolates demonstrated high oxalate degradation, 78 to 88%. To investigate the oxalate-degradation potential of the selected isolates, they have been further tested for the presence of genes that encode for enzymes involved in oxalate catabolism, formyl coenzyme A transferase (frc) and oxalyl coenzyme A decarboxylase (oxc). Three strains showed bands with the specific OXC and FRC forward and reverse primers designated as (SA-5, 9 and 37). Species-level identification revealed Loigolactobacillus bifermentans, Lacticaseibacillus paracasei, and Lactiplantibacillus plantarum. Preliminary results revealed that the tested probiotic strains harbored both oxc and frc whose products are putatively involved in oxalate catabolism. The probiotic potential of the selected strains was evaluated, and they showed high survival rates to both simulated gastric and intestinal fluids and variable degrees of antagonism against the tested Gram-positive and negative pathogens and were sensitive to clarithromycin but resistant to both metronidazole and ceftazidime. Finally, these strains could be exploited as an innovative approach to establish oxalate homeostasis in humans and prevent kidney stone formation.

Loss of Bacteroides thetaiotaomicron bile acid-altering enzymes impacts bacterial fitness and the global metabolic transcriptome

IMPORTANCE

Recent work on bile salt hydrolases (BSHs) in Gram-negative bacteria, such as Bacteroides, has primarily focused on how they can impact host physiology. However, the benefits bile acid metabolism confers to the bacterium that performs it are not well understood. In this study, we set out to define if and how Bacteroides thetaiotaomicron (B. theta) uses its BSHs and hydroxysteroid dehydrogenase to modify bile acids to provide a fitness advantage for itself in vitro and in vivo. Genes encoding bile acid-altering enzymes were able to impact how B. theta responds to nutrient limitation in the presence of bile acids, specifically carbohydrate metabolism, affecting many polysaccharide utilization loci. This suggests that B. theta may be able to shift its metabolism, specifically its ability to target different complex glycans including host mucin, when it comes into contact with specific bile acids in the gut.

Lactobacilli and Klebsiella: Two Opposites in the Fight for Human Health

The problem of antibiotic resistance is currently very acute. Numerous research and development of new antibacterial drugs are being carried out that could help cope with various infectious agents. One of the promising directions for the search for new antibacterial drugs is the search among the probiotic strains present in the human gastrointestinal tract. This review is devoted to characteristics of one of these probiotic strains that have been studied to date: Limosilactobacillus reuteri. The review discusses its properties, synthesis of various compounds, as well as role of this strain in modulating various systems of the human body. The review also examines key characteristics of one of the most harmful among the currently known pathogenic organisms, Klebsiella, which is significantly resistant to antibiotics existing in medical practice, and also poses a great threat of nosocomial infections. Discussion of characteristics of the two strains, which have opposite effects on human health, may help in creation of new effective antibacterial drugs without significant side effects.

Screening for Lactic Acid Bacterial Strains as Probiotics Exhibiting Anti-inflammatory and Antioxidative Characteristic Via Immune Modulation in HaCaT Cell

In this study, the basic probiotic characteristics and functional properties of lactic acid bacteria (LAB) were investigated using two in vitro models of inflammation induced by lipopolysaccharide (LPS) and H2O2. Fifteen strains were prescreened out of 60 LAB candidates based on their radical scavenging activity to determine the antioxidant capacity of the strains. The top 15 candidates were further investigated to evaluate their survival rate under low pH and bile salt conditions that mimic the intestinal environment. Three strains, Levilactobacillus brevis D70 (Levilact), Lactiplantibacillus pentosus S16 (Lactipla), and Limosilactobacillus fermentum MF10 (Limosilact), were capable of scavenging free radicals and survived under artificial intestinal conditions. Therefore, Levilact. brevis D70, Lactipla. pentosus S16, and Limosilact. fermentum MF10 were selected for further antioxidant, anti-inflammation, and mitochondrial activity examinations via cell models of inflammation and oxidative stress. Among the three strains, Limosilact. fermentum MF10 showed the highest anti-inflammatory activities by significantly downregulating the relative mRNA expression levels of inflammatory biomarkers such as interleukin 8 (IL-8) and interferon-gamma (IFN-γ) induced by LPS (P < 0.05). Moreover, Limosilact. fermentum MF10 was also capable of upregulating the gene expression levels of antioxidative mediator glutathione peroxidase 4 (GPX4) induced by reactive oxygen species (ROS) in both human HT-29 epithelial cells and human HaCaT keratinocytes. Limosilact. fermentum MF10 was also capable of regulating mitochondrial membrane potential (MMP), which plays a key role in the mitochondrial activity of HaCaT cells. As a result, Limosilact. fermentum MF10 showed the highest potential for probiotic properties and impacts the immune-related gut-skin axis by altering proinflammatory cytokines, antioxidative biomarkers, and MMP.

Microbial Diversity in African Foods and Beverages: A Systematic Assessment

This article provides a comprehensive and in-depth examination of the microbial diversity inherent in African food and beverages, with a particular emphasis on fermented products. It identifies and characterizes the dominant microorganisms, including both prokaryotes and yeasts, prevalent in these foods, and furthermore, critically analyzes the health benefits of these microbial strains, especially their probiotic properties, which could potentially improve digestion and contribute to human health. Notably, it underscores the vital role these microorganisms play in bolstering food security across Africa by enhancing and preserving food quality and safety. It also delves into the potential applications of microbial products, such as metabolites, in the food industry, suggesting their possible use in food processing and preservation. Conclusively, with a summarization of the key findings, emphasizing the importance of gaining a deep understanding of microbial diversity in African beverages and foods. Such knowledge is crucial not only in promoting food security but also in advancing public health.

Anti-cancer Properties of Potential Probiotics and Their Cell-free Supernatants for the Prevention of Colorectal Cancer: an In Vitro Study

This study aimed to characterize the anti-cancer properties of potential probiotics (Lacticaseibacillus paracasei SD1, Lacticaseibacillus rhamnosus SD4, Lacticaseibacillus rhamnosus SD11, and Lacticaseibacillus rhamnosus GG) and their cell-free supernatants (CFS) for the prevention of colorectal cancer (CRC), which including anti-bacterial and anti-inflammation activities against pathogens associated with CRC (Fusobacterium nucleatum, Porphyromonas gingivalis, ETEC, and Salmonella enterica). The expression of human β-defensin (2-4) and IL-10 after being stimulated with probiotics was also examined. In addition, anti-cancer activity of CFS and probiotic growth under intestinal conditions were determined. An in vitro study was conducted in the Caco-2 and HIEC-6 cells. Results showed that probiotic cells and their CFS displayed different antibacterial activity, and L. rhamnosus SD11 showed the strongest inhibition of the growth of pathogens. Additionally, both probiotic cell walls and their CFS suppressed pro-inflammatory cytokines after being stimulated with pathogens in Caco-2 and HIEC-6 cells. L. paracasei SD1 and L. rhamnosus SD11 showed significantly higher suppression levels than others and also both strains can stimulate highly expression of hBD (2-4) and IL-10. The CFS of L. paracasei SD1 and L. rhamnosus SD11 inhibited significantly high growth of Caco-2 cells but not much in HIEC-6 cells. Furthermore, all probiotics adhered to Caco-2 and HIEC-6 cells, and L. rhamnosus SD4 showed the highest adhesion to both cells. They could survive more than 70% in intestinal conditions. In conclusion, results indicate that potential probiotics tested exhibited various anti-cancer properties, which may be good candidates used as biotherapy for the prevention or to delay the progression of CRC.

Antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. against cariogenic Streptococcus mutans in vitro and viability when added to chewing gum during storage

The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

Bioprotective potential of lactic acid bacteria for Salmonella biocontrol in vitro

Lactic acid bacteria (LAB) are an important option for Salmonella control in animal production, resulting in lower antibiotic use. The objective of this research was to isolate LAB from meat products and from commercial probiotics sold as nutritional supplements for in vitro verification of their bioprotective potential. Eleven bacteria were identified as Pediococcus acidilactici, two as Lacticaseibacillus rhamnosus, one as Lacticaseibacillus paracasei paracasei, one as Limosilactobacillus fermentum, and one as a consortium of Lactobacillus delbrueckii bulgaricus and L. fermentum. All bacteria showed inhibitory activity against Salmonella, with emphasis on the inhibition of P. acidilactici PUCPR 011 against Salmonella Enteritidis 33SUSUP, S. Enteritidis 9SUSP, S. Enteritidis 56301, S. Enteritidis CRIFS 1016, Salmonella Typhimurium ATCC™ 14,028®, and Salmonella Gallinarum AL 1138, with inhibition halos of 7.3 ± 0.5 mm, 7.7 ± 1.0 mm, 9.0 ± 1.8 mm, 7.3 ± 0.5 mm, 7.7 ± 1.0 mm, and 7.3 ± 0.5, respectively. The isolates P. acidilactici PUCPR 011, P. acidilactici PUCPR 012, P. acidilactici PUCPR 014, L. fermentum PUCPR 005, L. paracasei paracasei PUCPR 013, and L. rhamnosus PUCPR 010 showed inhibition greater than 2 mm against at least 3 Salmonella and were used for encapsulation and in vitro digestion. The encapsulation efficiency ranged from 76.89 ± 1.54 to 116.48 ± 2.23%, and the population after 12 months of storage was from 5.31 ± 0.17 to 9.46 ± 0.09 log CFU/g. When simulating swine and chicken digestion, there was a large reduction in bacterial viability, stabilizing at concentrations close to 2.5 log CFU/mL after the analyses. The analyzed bacteria showed strong in vitro bioprotective potential; further analyses are required to determine in vivo effectiveness.

Investigating the Effectiveness of Exopolysaccharide-Producing Lactic Acid Bacteria in Biosorbing Lead (II), Attaching to Caco-2 Cells, and Provoking Antiinflammatory Responses

Lead is a common toxic heavy metal with harmful effects on the human body and is widely used in several industries. It can contaminate the environment by air and water emissions and can enter the human body through the respiratory tract, ingestion, or skin contact. Lead is considered as a persistent environmental pollutant, with a half-life of 30 days in the blood, and exists in the skeletal system for decades and causes damage to other systems. Biosorption is receiving increasing attention. Due to its high efficiency and economic value in removing heavy metals from the environment, a variety of biosorption methods can be used for the removal of heavy metals. Lactic acid bacteria (LAB) strains were capable of attaching to both human skin stratum corneum HaCaT cells and human rectal cancer Caco-2 cells. NBM-04-10-001 and NBM-01-07-003 significantly reduced the secretion of IL-6 and IL-8 after coculture with HaCaT cells. In the immune response of RAW264.7 mouse macrophages, high bacterial counts reduced the concentrations of IL-6 and TNF-α in a dose-dependent manner. The results of animal experiments revealed that feeding lead solution exerted no effect on the animal's food intake, and feeding PURE LAC NBM11 powder could effectively remove lead content in the blood. The group fed with PURE LAC NBM11 powder showed significantly less damage and lesions to liver cells. The LAB powder developed in this study has the potential to bind metals, preventing them from entering the body and protecting the host. LAB can be an ideal strain for future bioadsorption chelators.

Cytotoxic effect of potential probiotic Lactiplantibacillus plantarum KUMS-Y8 isolated from traditional dairy samples on the KB and OSCC human cancer cell lines

Oral cancer is one of the leading causes of death worldwide, and its prevalence is especially high in developing countries. As an oral cancer treatment, traditional therapies are commonly used. Nonetheless, these treatments frequently result in a variety of side effects. As a consequence, there is an urgent need to enhance oral cancer therapies. Probiotics have recently demonstrated intriguing properties as therapeutic options for cancer treatment. Thus, the purpose of this study was to investigate the anticancer effect of probiotic Lactobacillus strains on the mouth epidermal carcinoma cells (KB) and oral squamous cell carcinoma (OSCC) cell lines. In this study, we looked at 21 Lactobacillus strains isolated from traditional dairy products in the Kermanshah province of western Iran to see if they had any inhibitory effects on oral cancer cell lines in vitro. We isolated and characterized Lactobacillus strains before assessing and comparing their probiotic potential and safety. Using the MTT assay, the bacterial extract was then prepared and used as an anti-proliferative agent on oral cancer (KB and OSCC) and normal (fibroblast and human umbilical vein endothelial cells (HUVEK) cell lines. Finally, acridine orange/ethidium bromide staining was used to determine whether cell death was caused by apoptosis. Four Lactobacillus isolates (C14, M22, M42, and Y8) were shown to have beneficial probiotic qualities. Lactobacillus extracts (of a protein nature) decreased the survival and proliferation of the KB and OSCC cancer cell lines (dose- and time-dependent) by inducing apoptosis, with no basic damaging effects on normal cells. The staining with acridine orange/ethidium bromide revealed that the cell death was caused by apoptosis. Furthermore, of the four Lactobacillus strains examined, isolate Y8 (Lactiplantibacillus plantarum) showed the strongest probiotic potential for suppressing KB and OSCC cell proliferation when compared to anticancer medicines (doxorubicin and paclitaxel). The current research found that Lactobacillus extract might reduce the growth and viability of the KB and OSCC cancer cell lines by inducing apoptosis, increasing the survival rate of oral cancer patients.

In vitro evaluation of probiotic properties and selenium bioaccumulation of lactic acid bacteria isolated from poultry gastrointestinal, as an organic selenium source

The purpose of this study was to examine the probiotic characteristics and selenium (Se) bioaccumulation potential of five Lactobacillus strains in vitro. Lactobacillus acidophilus, L. delbrueckii subsp. lactis, L. reuteri, L. gallinarum, and L. animalis were among the strains employed. As significant aspects of probiotics, identification, and evaluation of their survival potential in the gastrointestinal system were undertaken. Although all experimental Lactobacillus strains bioaccumulated Se (IV) concentrations in media culture, three Lactobacillus strains (L. animalis, L. gallinarum, and L. acidophilus) bioaccumulated the highest Se concentrations (23.08, 8.62, and 8.51 mg/g, respectively) after culture in the presence of 1.5 mg/ml sodium selenite. By disc diffusion, all isolates were evaluated for antibiotic susceptibility against six antibiotics, including ciprofloxacin, ampicillin, methicillin, streptomycin, tetracycline, and trimethoprim-sulfamethoxazole. Many of the isolates tested positive for resistance to some of the antibiotics utilized. The L. reuteri and L. gallinarum were found to be resistant to about 50% of the antibiotics that were tested. In terms of acid tolerance, L. animalis showed significant resistance at acidic pH by 1.72 log unit reduction whereas L. delbrueckii and L. galliinarum showed significant sensitivity at acidic pH (P > 0.05). Bile tolerance was addressed as an important aspect of the safety assessment for probiotics. There were variances in acid and bile tolerance among species, although all of them tolerated stress conditions to an acceptable degree. Upon comparing the various species, it was observed that L. gallinarum exhibited a significant decline in growth, as evidenced by a decrease of 1.39 log units in cell viability. On the other hand, L. acidophilus and L. animalis demonstrated remarkable bile tolerance, with 0.09 and 0.23 log unit reduction respectively (P < 0.05). These results suggest that L. animalis, L. gallinarum, and L. acidophilus, can be good candidates to evaluate them in vivo in further investigations due to their tolerance to acid, and bile, antibiotic resistance, and strong ability to bioaccumulate Se in chickens.

Screening of lactic acid bacteria with anti-adipogenic effect and potential probiotic properties from grains

A total of 187 lactic acid bacteria were isolated from four types of grains collected in South Korea. The bacterial strains were assigned as members of Levilactobacillus brevis, Latilactobacillus curvatus, Lactiplantibacillus plantarum, Lactococcus taiwanensis, Pediococcus pentosaceus, and Weissella paramesenteroides based on the closest similarity using 16S rRNA gene sequence analysis. The strains belonging to the same species were analyzed using RAPD-PCR, and one or two among strains showing the same band pattern were selected. Finally, 25 representative strains were selected for further functional study. Inhibitory effects of lipid accumulation were observed in the strains tested. Pediococcus pentosaceus K28, Levilactobacillus brevis RP21 and Lactiplantibacillus plantarum RP12 significantly reduced lipid accumulation and did not show cytotoxicity in C3H10T1/2 cells at treatment of 1-200 μg/mL. The three LAB strains decreased significantly expression of six adipogenic marker genes, PPARγ, C/EBPα, CD36, LPL, FAS and ACC, in C3H10T1/2 adipocytes. The three strains survived under strong acidity and bile salt conditions. The three strains showed adhesion to Caco-2 cells similar to a reference strain LGG. The resistance of the three strains to several antibiotics was also assessed. Strains RP12 and K28 were confirmed not to produce harmful enzymes based on API ZYM kit results. Based on these results, strains K28, RP21 and RP12 isolated from grains had the ability to inhibit adipogenesis in adipocytes and potentially be useful as probiotics.

Loss of Bacteroides thetaiotaomicron bile acid altering enzymes impact bacterial fitness and the global metabolic transcriptome

Bacteroides thetaiotaomicron (B. theta) is a Gram-negative gut bacterium that encodes enzymes that alter the bile acid pool in the gut. Primary bile acids are synthesized by the host liver and are modified by gut bacteria. B. theta encodes two bile salt hydrolases (BSHs), as well as a hydroxysteroid dehydrogenase (HSDH). We hypothesize that B. theta modifies the bile acid pool in the gut to provide a fitness advantage for itself. To investigate each gene's role, different combinations of genes encoding bile acid altering enzymes (bshA, bshB, and hsdhA) were knocked out by allelic exchange, including a triple KO. Bacterial growth and membrane integrity assays were done in the presence and absence of bile acids. To explore if B. theta's response to nutrient limitation changes due to the presence of bile acid altering enzymes, RNASeq analysis of WT and triple KO strains in the presence and absence of bile acids was done. WT B. theta is more sensitive to deconjugated bile acids (CA, CDCA, and DCA) compared to the triple KO, which also decreased membrane integrity. The presence of bshB is detrimental to growth in conjugated forms of CDCA and DCA. RNA-Seq analysis also showed bile acid exposure impacts multiple metabolic pathways in B. theta, but DCA significantly increases expression of many genes in carbohydrate metabolism, specifically those in polysaccharide utilization loci or PULs, in nutrient limited conditions. This study suggests that bile acids B. theta encounters in the gut may signal the bacteria to increase or decrease its utilization of carbohydrates. Further study looking at the interactions between bacteria, bile acids, and the host may inform rationally designed probiotics and diets to ameliorate inflammation and disease.

Importance

Recent work on BSHs in Gram-negative bacteria, such as Bacteroides, has primarily focused on how they can impact host physiology. However, the benefits bile acid metabolism confers to the bacterium that performs it is not well understood. In this study we set out to define if and how B. theta uses its BSHs and HSDH to modify bile acids to provide a fitness advantage for itself in vitro and in vivo. Genes encoding bile acid altering enzymes were able to impact how B. theta responds to nutrient limitation in the presence of bile acids, specifically carbohydrate metabolism, affecting many polysaccharide utilization loci (PULs). This suggests that B. theta may be able to shift its metabolism, specifically its ability to target different complex glycans including host mucin, when it comes into contact with specific bile acids in the gut. This work will aid in our understanding of how to rationally manipulate the bile acid pool and the microbiota to exploit carbohydrate metabolism in the context of inflammation and other GI diseases.

Characterization of Leuconostoc mesenteroides MJM60376 as an oral probiotic and its antibiofilm activity

Lactic acid bacteria have been widely used as probiotics for improving gut health. However, studies on oral probiotics were very limited. In this study, 67 lactic acid bacteria (LAB) were isolated from fermented food and screened for antagonistic activity against Streptococcus mutans, the causative pathogen of dental caries. Leuconostoc mesenteroides MJM60376 showed the highest antagonistic activity against S. mutans KCTC3065. L. mesenteroides MJM60376 also showed oral probiotic characteristics including weak acid production, lysozyme tolerance, adhesion to oral epithelial cell (YD-38), antibiotic susceptibility, and good coaggregation ability with S. mutans. Furthermore, the biofilm formation of S. mutans was significantly reduced when cocultured with L. mesenteroides. Scanning electron microscopy analysis showed that amounts of attached bacteria of S. mutans and network-like structures were significantly reduced by L. mesenteroides MJM60376. Cell-free supernatant (CFS) of L. mesenteroides MJM60376 also greatly inhibited biofilm formation of S. mutans from the adherent stage, the activity remained even after it was treated with catalase, trypsin, or pH neutralized. Expression levels of biofilm formation-related genes were significantly reduced in S. mutans when it was treated with the CFS of L. mesenteroides MJM60376. Therefore, L. mesenteroides MJM60376 has great potential to be used as a multifunctional ingredient.

Bile salt hydrolases shape the bile acid landscape and restrict Clostridioides difficile growth in the murine gut

Bile acids (BAs) mediate the crosstalk between human and microbial cells and influence diseases including Clostridioides difficile infection (CDI). While bile salt hydrolases (BSHs) shape the BA pool by deconjugating conjugated BAs, the basis for their substrate selectivity and impact on C. difficile remain elusive. Here we survey the diversity of BSHs in the gut commensals Lactobacillaceae, which are commonly used as probiotics, and other members of the human gut microbiome. We structurally pinpoint a loop that predicts BSH preferences for either glycine or taurine substrates. BSHs with varying specificities were shown to restrict C. difficile spore germination and growth in vitro and colonization in pre-clinical in vivo models of CDI. Furthermore, BSHs reshape the pool of microbial conjugated bile acids (MCBAs) in the murine gut, and these MCBAs can further restrict C. difficile virulence in vitro. The recognition of conjugated BAs by BSHs defines the resulting BA pool, including the expansive MCBAs. This work provides insights into the structural basis of BSH mechanisms that shape the BA landscape and promote colonization resistance against C. difficile.

Characterization of lactic acid bacteria isolated from the poultry intestinal environment with anti-Salmonella activity in vitro

The purpose of this research was the genotypic identification of lactic acid bacteria (LAB), isolated from the gastrointestinal tract (GIT) of healthy adult birds, and the study of their safety regarding antibiotic resistance, physiological and functional properties involved in the colonization of the GIT of poultry, and Salmonella exclusion, as members of a potential mixed probiotic supplement for poultry. The nucleotidic sequence from Lactobacillus crispatus P1, L. animalis L3, and Enterococcus faecium CRL 1385 (ex-J96) showed 100, 99.8, and 99.3% identity with L. crispatus DSM 20584 T, Ligilactobacillus salivarius ATCC 11741 T, and E. faecium ATCC 19434 T, respectively. These strains showed no resistance to relevant antibiotics usually administered to animals proposed by the European Food Safety Authority. They could endure the detrimental conditions of the gastrointestinal tract (pH 2.6 and oxgall 0.1 and 0.4% w/v). In an ex vivo assay, the LAB showed high adherence to the three sections of the GIT, reaching values higher than 70%. The adhesion to mucus was strain-dependent: L. crispatus CRL 1453 evidenced the highest adhesion (> 19%) while Lig. salivarius subsp. salivarius CRL 1417 and E. faecium CRL 1385 adhered to a lower extent (> 9 and 2%, respectively). Moreover, the LAB elicited remarkable anti-Salmonella activity, taking into account that they could inhibit elevated counts of different Salmonella serovars, especially the host-specific serovars S. Gallinarum and S. Pullorum (up to 8 log CFU/mL decrease in Salmonella counts).

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent, this study aimed to characterize the probiotic properties and investigate the gastrointestinal protective effects of nine novel L. plantarum strains isolated from Bahia, Brazil. The probiotic functionality was first evaluated in vitro by characterizing bile salt and acidic tolerance, antibacterial activity, and adhesion to Caco-2 cells. Antibiotic resistance profile, mucin degradation, and hemolytic activity assays were also performed to evaluate safety features. In vivo analyses were conducted to investigate the anti-inflammatory effects of the strains on a mouse model of 5-Fluorouracil-induced mucositis. Our results suggest that the used L. plantarum strains have good tolerance to bile salts and low pH and can inhibit commonly gastrointestinal pathogens. Lp2 and Lpl1 strains also exhibited high adhesion rates to Caco-2 cells (13.64 and 9.05%, respectively). Phenotypical resistance to aminoglycosides, vancomycin, and tetracycline was observed for most strains. No strain showed hemolytic or mucolytic activity. Seven strains had a protective effect against histopathological and inflammatory damage induced by 5-FU. Gene expression analysis of inflammatory markers showed that five strains upregulated interleukin 10 (Il10), while four downregulated both interleukin 6 (Il6) and interleukin 1b (Il1b). Additionally, all strains reduced eosinophilic and neutrophilic infiltration; however, they could not prevent weight loss or reduced liquid/ food intake. Altogether, our study suggests these Brazilian L. plantarum strains present good probiotic characteristics and safety levels for future applications and can be therapeutically adjuvant alternatives to prevent/treat intestinal mucositis.

Membrane vesicles released by Lacticaseibacillus casei BL23 inhibit the biofilm formation of Salmonella Enteritidis

Biofilms represent a major concern in the food industry and healthcare. The use of probiotic bacteria and their derivatives as an alternative to conventional treatments to fight biofilm development is a promising option that has provided convincing results in the last decades. Recently, membrane vesicles (MVs) produced by probiotics have generated considerable interest due to the diversity of roles they have been associated with. However, the antimicrobial activity of probiotic MVs remains to be studied. In this work, we showed that membrane vesicles produced by Lacticaseibacillus casei BL23 (LC-MVs) exhibited strong antibiofilm activity against Salmonella enterica serovar Enteritidis (S. Enteritidis) without affecting bacterial growth. Furthermore, we found that LC-MVs affected the early stages of S. Enteritidis biofilm development and prevented attachment of bacteria to polystyrene surfaces. Importantly, LC-MVs did not impact the biomass of already established biofilms. We also demonstrated that the antibiofilm activity depended on the proteins associated with the LC-MV fraction. Finally, two peptidoglycan hydrolases (PGHs) were found to be associated with the antibiofilm activity of LC-MVs. Overall, this work allowed to identify the antibiofilm properties of LC-MVs and paved the way for the use of probiotic MVs against the development of negative biofilms.

The probiotic and immunomodulation effects of Limosilactobacillus reuteri RGW1 isolated from calf feces

Introduction

Limosilactobacillus reuteri is a gut symbiont with multiple remarkable beneficial effects on host health, and members of L. reuteri are valuable probiotic agents. However, L. reuteri showed obvious host specificity.

Methods

In our study, a novel L. reuteri RGW1 was isolated from feces of healthy calves, and its potential as a probiotic candidate were assessed, by combining in vitro, in vivo experiments and genomic analysis.

Results and discussion

RGW1 was sensitive to all the antibiotics tested, and it did not contain any virulence factor-coding genes. This isolate showed good tolerance to acid (pH 3.0), 0.3% bile salt, and simulated gastric fluid. Moreover, this isolate showed a high hydrophobicity index (73.7 ± 4.6%) and was able to adhere to Caco-2 cells, and antagonize Escherichia coli F5. Treatment of LPS-induced mice with RGW1 elevated TGF-β and IL-10 levels, while RGW1 cell-free supernatant (RCS) decreased TNF-α levels in the sera. Both RGW1 and RCS increased the villus height and villus height/crypt depth ratio of colon. Genomic analysis revealed the mechanism of the probiotic properties described above, and identified the capacity of RGW1 to biosynthesize L-lysine, folate, cobalamin and reuterin de novo. Our study demonstrated the novel bovine origin L. reuteri RGW1 had multiple probiotic characteristics and immunomodulation effects, and provided a deeper understanding of the relationship between these probiotic properties and genetic features.

Expression of heterologous heparan sulphate binding protein of Helicobacter pylori on the surface of Lactobacillus rhamnosus GG

Helicobacter pylori (H. pylori) is one of most commonly found pathogen in the stomach. In spite of emergence of different treatment strategies, H. pylori infection remains difficult to treat. The bioengineered probiotic lactobacilli that could displace H. pylori and simultaneously present immunogenic peptides such as heparan sulphate binding protein (Hsbp) to elicit immune response could emerge as a potential therapeutic agent. The aim of this study was to discover the anti-H. pylori activities and faster exclusion of H. pylori from host cells by the recombinant strain of Lactobacillus expressing the immunogenic Hsbp protein. The results were promising and showed a 65% reduction in H. pylori adhesion after two hours of pre-incubation with recombinant-LGG and HeLa S3 cells, followed by the adhesion of H. pylori pathogen (P < 0.002). Additionally, 36% and 39% reduction were examined in co-incubation and post-incubation with recombinant-LGG, respectively. When challenged with H. pylori, the proinflammatory cytokine expression was also down regulated in recombinant-LGG treated HeLa S3 cells. This promising result provides a new insight of bioengineered probiotic lactobacilli which could displace H. pylori and simultaneously has immunogenic properties thereby may be useful to prevent H. pylori infection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03428-4.

Potential oral probiotic Lactobacillus pentosus MJM60383 inhibits Streptococcus mutans biofilm formation by inhibiting sucrose decomposition

Streptococcus mutans is known as a contributor to dental caries. In this work, Lactobacillus pentosus MJM60383 was selected for its strong antagonistic activity against S. mutans and was characterized by good oral probiotic properties including lysozyme tolerance, adhesive ability to oral cells, good aggregation (auto-aggregation, co-aggregation) ability, hydrogen peroxide production and inhibition of biofilm formation of S. mutans. L. pentosus MJM60383 also exhibited safety as a probiotic characterized by no hemolytic activity, no D-lactate production, no biogenic amine production, and susceptibility to antibiotics. Furthermore, the biofilm formation of S. mutans was also significantly inhibited by the supernatant of L. pentosus MJM60383. An anti-biofilm mechanism study revealed that sucrose decomposition and the production of water-insoluble exopolysaccharides by S. mutans were inhibited by the treatment with L. pentosus MJM60383 supernatant. Real-time PCR analysis indicated that the supernatant of L. pentosus MJM60383 significantly inhibited the mRNA expression of S. mutans glycosyltransferases, which synthesize glucan to construct biofilm architecture and mediate bacterial adherence. Our study demonstrated L. pentosus MJM60383 as a potential oral probiotic and revealed its anti-biofilm mechanism.

Probiotic Properties and Proteomic Analysis of Pediococcus pentosaceus 1101

Pediococcus pentosaceus 1101 was identified by using 16S rRNA and MALDI-Biotyper. The strain was exposed to conditions that resemble the gastrointestinal tract (GT) to evaluate its probiotic properties. That included the growth kinetics, proteolytic and inhibitory activities within a pH range, survival at low pH and in the presence of bile salts, antagonistic activity, cell-adhesion properties, and antibiotic resistance. The evaluation was followed by a genomic and proteomic analysis that involved the identification of proteins obtained under control and gastrointestinal conditions. The strain showed antagonistic activity against Gram-negative and Gram-positive bacteria, high resistance to acidity (87% logarithmic survival rate, pH 2) and bile salts (99% logarithmic survival rate, 0.5% w/v), and hydrophobic binding, as well as sensitivity to penicillin, amoxicillin, and chloramphenicol. On the other hand, P. pentosaceus 1101 has a genome size of 1.76 Mbp, with 1754 coding sequences, 55 rRNAs, and 33 tRNAs. The proteomic analysis showed that 120 proteins were involved in mechanisms in which the strain senses the effects of acid and bile salts. Moreover, the strain produces at least one lytic enzyme (N-acetylmuramoyl-L-alanine amidase; 32 kDa) that may be related to the antimicrobial activity. Therefore, proteins identified might be a key factor when it comes to the adaptation of P. pentosaceus 1101 into the GT and associated with its technological and probiotic properties.

Antibacterial and antibiofilm activity of Lactobacillus strains secretome and extraction against Escherichia coli isolated from urinary tract infection

The purpose of this study was to antibacterial, and antibiofilm activity of two Lactobacillus strains secretome and extraction against E. coli isolated from women with urinary tract infection (UTI). We isolated 100 E. coli samples from women with UTI. Lactobacillus acidophilus and Lactobacillus casei characteristics were evaluated, and their secretome and extraction were prepared. The antibacterial and antibiofilm activity of secretome and extraction of both Lactobacillus strains were evaluated against isolated E. coli samples. L. acidophilus and L. casei were able to tolerate pH 3, bile salts, and pancreatic enzymes. Both probiotics were not resistant to antibiotics and demonstrated an appropriate ability to adhere to the intestinal epithelial cells. Secretome and extraction of L. acidophilus and L. casei strains showed a good antibacterial and antibiofilm against E. coli isolates. Generally, present study suggested that the secretome and extraction of L. acidophilus and L. casei strains exhibits a good antimicrobial activity.

Honeybee-associated lactic acid bacteria and their probiotic potential for human use

This study aims to identify lactic acid bacteria (LAB) isolated from honeybees (Apis mellifera workers and larvae) in detail and to determine their functional probiotic properties. A total of 11 strains were classified based on morphological and biochemical characteristics. Preliminary probiotic properties of strains, that were molecularly identified using 16 S rRNA, such as antimicrobial activity, tolerance to digestive conditions, aggregation ability, were investigated. The antimicrobial properties of strains were tested against a wide range of human pathogens. All strains that showed γ-hemolysis and did not contain bacteriophages were considered safe. The strains' survivability checked for 0.3% bile and 3.0-7.8 pH contents was promising. The highest autoaggregation ranged from 14.7 to 30.76% after 4 h. Tested LAB strains markedly exhibited coaggregation with Listeria monocytogenes and Escherichia coli. According to the results, tested bacteria showed significant antagonistic effects against pathogens, and positive probiotic characteristics compatible with in vitro gastrointestinal tract conditions. The results suggest that Apis mellifera LAB symbionts may have a probiotic potential, and be effective and safe candidates for human use. This study provides an addition to the development of the current knowledge by defining in detail honeybee-associated bacteria and determining their probiotic potential.

Enterococcus faecium GEFA01 alleviates hypercholesterolemia by promoting reverse cholesterol transportation via modulating the gut microbiota-SCFA axis

This study aimed to identify cholesterol-lowering commensal strains from healthy lean individuals and to evaluate the cholesterol-lowering capacity of Enterococcus faecium GEFA01 in mice fed a high-cholesterol and high-fat diet. E. faecium GEFA01 was isolated from the feces of a healthy lean individual in a selective basal salt medium supplemented with cholesterol. E. faecium GEFA01 exhibited a cholesterol removal rate (CRR) of 46.13% by coprecipitation, assimilation, and degradation of cholesterol. Moreover, E. faecium GEFA01 significantly decreased the body weight of mice and the levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), hepatic TC, triglycerides (TG), and LDL-C, and increased serum high-density lipoprotein cholesterol (HDL-C) levels in mice fed a high-cholesterol diet compared with the HCD group. We also observed that E. faecium GEFA01 significantly downregulated the gene expression of HMG-CoA reductase (Hmgcr), Srebp-1c, Fxr, Shp, and Fgf 15, upregulated the gene expression of low-density lipoprotein receptor (Ldlr), Abcg5/8, Abca1, cholesterol 7 alpha-hydroxylase (Cyp7a1), and Lxr in the liver of mice in relative to the HCD group, markedly increased the relative abundance of Lactobacillus, Akkermansia, Bifidobacterium, and Roseburia, and decreased the abundance of Helicobacter in the feces. Collectively, we confirmed that E. faecium GEFA01 exhibited cholesterol-lowering effects in mice fed a high-cholesterol diet, which was achieved through assimilation, coprecipitation, and degradation of cholesterol, and through modulation of the gut microbiota short-chain fatty acid (SCFA) axis that promoted reverse cholesterol transport and bile acid excretion. Our study demonstrated that E. faecium GEFA01 may be used as a probiotic candidate to lower cholesterol levels in the future.

Lactobacillus reuteri MJM60668 Prevent Progression of Non-Alcoholic Fatty Liver Disease through Anti-Adipogenesis and Anti-inflammatory Pathway

Non-alcoholic fatty liver disease (NALFD) is a disease characterized by liver steatosis. The liver is a key organ involved in the metabolism of fat, protein, and carbohydrate, enzyme activation, and storage of glycogen, which is closely related to the intestine by the bidirectional relation of the gut-liver axis. Abnormal intestinal microbiota composition can affect energy metabolism and lipogenesis. In this experiment, we investigated the beneficial effect of Lactobacillus reuteri MJM60668 on lipid metabolism and lipogenesis. C57BL/6 mice were fed a high-fat diet (HFD) and orally administrated with MJM60668. Our results showed that mice treated with MJM60668 significantly decreased liver weight and liver/body weight ratio, without affecting food intake. Serum levels of ALT, AST, TG, TCHO, and IL-1β in mice fed with MJM60668 were decreased compared to the HFD group. Investigation of gene and protein expression on the lipogenesis and lipid metabolism showed that the expression of ACC, FAS, and SREBP was decreased, and PPARα and CPT was increased. Furthermore, an increase of adiponectin in serum was shown in our experiment. Moreover, serum IL-1β level was also significantly decreased in the treated mice. These results suggested that MJM60668 can strongly inhibit lipogenesis, enhance fatty acid oxidation, and suppress inflammation. Additionally, supplementation of MJM60668 increased the proportion of Akkermansiaceae and Lachnospiracea, confirming a potential improvement of gut microbiota, which is related to mucus barrier and decrease of triglycerides levels.

Probiotic Property and Anti-Obesity Effect of Lactiplantibacillus plantarum KC3

Lactic acid bacteria are representative probiotics that have beneficial effects on humans. Nineteen strains among the 167 single strains from kimchi was selected and their physiological features were investigated. The selection of a strain was based on strong enzyme (lipase, α-amylase, and α-glucosidase) inhibitory activities and anti-obesity effects in the adipocytes. For the final selection, the strain Lactiplantibacillus plantarum KC3 was tested for its potential as a starter. To assess its functionality, a freeze-dried culture of L. plantarum KC3 was administered to a diet-induced obese mouse model receiving a high-fat diet. The animal group administered with L. plantarum KC3 showed significant body weight loss during the 12-week feeding period compared to the high-fat control group. This study investigated the physiological characteristics of selected strain and evaluated its potential as an anti-obesity probiotic in mice.

Bile Acid and Gut Microbiota in Irritable Bowel Syndrome

Gut microbiota and their metabolites like bile acid (BA) have been investigated as causes of irritable bowel syndrome (IBS) symptoms. Primary BAs are synthesized and conjugated in the liver and released into the duodenum. BA biotransformation by gut microbiota begins in the intestine and results in production of a broad range of secondary BAs. Deconjugation is considered the gateway reaction for further modification and is mediated by bile salt hydrolase, which is widely expressed by the gut microbiota. However, gut bacteria that convert primary BAs to secondary BAs belong to a limited number of species, mainly Clostridiales. Like gut microbiota modify BA profile, BAs can shape gut microbiota via direct and indirect actions. BAs have prosecretory effects and regulates gut motility. BAs can also affect gut sensitivity. Because of the vital role of the gut microbiota and BAs in gut function, their bidirectional relationship may contribute to the pathophysiology of IBS. Individuals with IBS have been reported to have altered microbial profiles and modified BA profiles. A significant increase in fecal primary BA and a corresponding decrease in secondary BA have been observed in IBS with predominant diarrhea. In addition, primary BA was positively correlated with IBS symptoms. In IBS with predominant diarrhea, bacteria with reduced abundance mainly belonged to the genera in Ruminococcaceae and exhibited a negative correlation with primary BAs. Integrating the analysis of the gut microbiota and BAs could better understanding of IBS pathophysiology. The gap in this field needs to be further filled in the future.