Probiotics: An alternative strategy for combating salmonellosis

Neutrophil recruitment during intestinal inflammation primes Salmonella elimination by commensal E. coli in a context-dependent manner

Foodborne bacterial diarrhea involves complex pathogen-microbiota-host interactions. Pathogen-displacing probiotics are increasingly popular, but heterogeneous patient outcomes highlighted the need to understand individualized host-probiotic activity. Using the mouse gut commensal Escherichia coli 8178 and the human probiotic E. coli Nissle 1917, we found that the degree of protection against the enteric pathogen Salmonella enterica serovar Typhimurium (S. Tm) varies across mice with distinct gut microbiotas. Pathogen clearance is linked to enteropathy severity and subsequent recruitment of intraluminal neutrophils, which differs in a microbiota-dependent manner. By combining mouse knockout and antibody-mediated depletion models with bacterial genetics, we show that neutrophils and host-derived reactive oxygen species directly influence E. coli-mediated S. Tm displacement by potentiating siderophore-bound toxin killing. Our work demonstrates how host immune factors shape pathogen-displacing probiotic efficiency while also revealing an unconventional antagonistic interaction where a gut commensal and the host synergize to displace an enteric pathogen.

Microbial Contamination of Food: Probiotics and Postbiotics as Potential Biopreservatives

Microbial contamination of food and alimentary toxoinfection/intoxication in humans are commonly caused by bacteria such as Salmonella spp., Escherichia coli, Yersinia spp., Campylobacter spp., Listeria monocytogenes, and fungi (Aspergillus, Fusarium). The addition of probiotic cultures (bacterial strains Lactobacillus and Bifidobacterium and the yeast Saccharomyces cerevisiae var. boulardii) to food contributes primarily to food enrichment and obtaining a functional product, but also to food preservation. Reducing the number of viable pathogenic microorganisms and eliminating or neutralizing their toxins in food is achieved by probiotic-produced antimicrobial substances such as organic acids (lactic acid, acetic acid, propionic acid, phenylacetic acid, and phenyllactic acid), fatty acids (linoleic acid, butyric acid, caproic acid, and caprylic acid), aromatic compounds (diacetyl, acetaldehyde, reuterin), hydrogen peroxide, cyclic dipeptides, bacteriocins, and salivabactin. This review summarizes the basic facts on microbial contamination and preservation of food and the potential of different probiotic strains and their metabolites (postbiotics), including the mechanisms of their antimicrobial action against various foodborne pathogens. Literature data on this topic over the last three decades was searched in the PubMed, Scopus, and Google Scholar databases, systematically presented, and critically discussed, with particular attention to the advantages and disadvantages of using probiotics and postbiotics as food biopreservatives.

In vitro and in vivo evaluation of tannic acid as an antibacterial agent in broilers infected with Salmonella Typhimurium

This study was conducted to evaluate tannic acid (TA) as an antibacterial agent against Salmonella Typhimurium in in vitro and in vivo chicken models. The TA formed an inhibitory zone against Salmonella enterica serotypes including S. Typhimurium, S. Enteritidis, and S. Infantis. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of TA against Salmonella Typhimurium nalidixic acid resistant strain (STNR) were determined as 40 and 700 μg/mL, respectively. Sublethal doses of TA (5, 10, and 20 μg/mL) restricted swimming and swarming motility and biofilm formation of STNR compared to the control group (0 μg/mL) (P < 0.05). The TA-bovine serum albumin (BSA) complex formed at simulated gastric pH (pH 3.75) was hydrolyzed at pH 6.75 and 7.25 (P < 0.05), and the hydrolysis of the TA-BSA complex was stronger at pH 7.25 compared to the pH 6.75 (P < 0.05). The inhibitory zone of the TA-BSA complex against STNR at pH 6.75 was lower than TA without BSA at 30 and 60 min (P < 0.05), but not at 120 min (P > 0.1). The inhibitory zone of the TA-BSA complex against STNR at pH 7.25 was not decreased at 0, 30, and 60 min compared to TA without BSA (P > 0.1). The recovery rate of TA was 83, 54.8, 10.5, and 19.6% in the gizzard, jejunum, ileum, and ceca, respectively, in broiler chickens. The STNR-infected broilers fed 0.25 g/kg of TA had significantly lower unweighted beta diversity distance compared to the sham-challenged control (SCC) and challenged controlled (CC) group on D 21. TA supplementation linearly (P < 0.05) and quadratically (tendency; P = 0.071) reduced relative abundance of the family Peptostreptococcaceae in broilers infected with STNR on D 7. TA supplementation linearly (P < 0.05) and quadratically (tendency; P = 0.06) increased the relative abundance of the family Erysipelotrichaceae in broilers infected with STNR on D 21. Therefore, TA has potential to be used as an antibacterial agent against the S. Typhimurium infection in broilers.

Autochthonous buffalo-gut origin Pediococcus pentosaceus RM119 decreased diarrhea and enhanced gut health, immunity in neonatal Murrah calves

This study assessed the effect of autochthonous probiotic Pediococcus pentosaceus RM119 on gut health, growth, and nutrient utilization in calves. Twelve buffalo calves (<15 d) were divided into two groups, control without probiotics, and probiotic group with P. pentosaceus RM119 @ 108 CFU/calf/d. The probiotic group showed a reduction (p < 0.05) in fecal score, diarrhea episodes and duration of diarrhea. The fecal pH, fecal ammonia was lower, whereas lactate was higher in probiotic group than control. There was a significant increase (p < 0.01) in the concentration of fecal acetate, propionate and butyrate levels in the probiotic supplemented group. The fecal lactobacilli and bifidobacterium were higher (p < 0.01), whereas, fecal coliform and clostridial count were lower (p < 0.01) in P. pentosaceus RM119 supplemented group. There was an improvement in reduced glutathione anti oxidant. Overall, buffalo-gut origin P. pentosaceus RM119 reduced the frequency and severity of diarrhea in neonatal buffalo calves and improved the gut health.

Lactic acid bacteria: prominent player in the fight against human pathogens

INTRODUCTION

The human microbiome is a unique repository of diverse bacteria. Over 1000 microbial species reside in the human gut, which predominantly influences the host's internal environment and plays a significant role in host health. Lactic acid bacteria have long been employed for multiple purposes, ranging from food to medicines. Lactobacilli, which are often used in commercial food fermentation, have improved to the point that they might be helpful in medical applications.

AREAS COVERED

This review summarises various clinical and experimental evidence on efficacy of lactobacilli in treating a wide range of infections. Both laboratory based and clinical studies have been discussed.

EXPERT OPINION

Lactobacilli are widely accepted as safe biological treatments and host immune modulators (GRAS- Generally regarded as safe) by the US Food and Drug Administration and Qualified Presumption of Safety. Understanding the molecular mechanisms of lactobacilli in the treatment and pathogenicity of bacterial infections can help with the prediction and development of innovative therapeutics aimed at pathogens which have gained resistance to antimicrobials. To formulate effective lactobacilli based therapy significant research on the effectiveness of different lactobacilli strains and its association with demographic distribution is required. Also, the side effects of such therapy needs to be evaluated.

Influence of cow reproductive tract microbiota on formation of calf upper respiratory tract microbiota

Diagnosis of latent endometritis and predicting the effect of the inflammatory process on the course of pregnancy and its outcome is a necessary measure when conducting clinical examination of animals. Lack of diagnostic criteria, including microbiological one, cause difficulties for veterinarians in assessing latent endometritis. Often, animals suffering from latent inflammation of the reproductive tract are infertile and cannot be treated. And from cows with dysbiosis of the genital tract, sick young animals are born, lagging behind in growth and development. The aim of the work was to establish the relationship between the genital tract microbiome, the number and species composition of commensals and opportunistic microorganisms on the ability to carry pregnancy. Washes from the oral and nasal cavities were taken from the young born to study the microbiome: lactic acid microorganisms in combination with opportunistic pathogens. As a result of the research, it was found that animals with a low number of lactic acid microorganisms and an increased titer of opportunistic microorganisms were infertile, which led to their culling. In young animals, they are present in the respiratory tract in all samples, together with coccal microorganisms. The study of lactic acid microorganisms is advisable in the diagnosis of inflammatory processes of the reproductive tract and upper respiratory tract.

Investigation of the Potential of Heterophil/Lymphocyte Ratio as a Biomarker to Predict Colonization Resistance and Inflammatory Response to Salmonella enteritidis Infection in Chicken

Salmonella causes significant economic loss to the poultry industry and represents a real threat to human health. The region of difference 21 (ROD21) pathogenicity island removal is a genetic mechanism by which Salmonellaenteritidis (SE) invades the intestinal epithelium and induces systemic infection in mice. The heterophil/lymphocyte (H/L) ratio reflects the chicken’s robustness and immune system status. The H/L ratio is considered a disease resistance trait, and it could be used as a marker for selecting Salmonella resistance in live chickens. However, the association of the H/L ratio with Salmonella resistance and the inflammatory response remains to be elucidated. Moreover, the kinetics of ROD21 excision in the intestine and immune organs of chickens is unknown. Therefore, this study aimed to investigate the bacterial load, the ROD21 excision, the IL-1β, IL-8, and INF-γ blood serum concentration kinetics, and the association with the H/L ratio in chicken at 1, 3, 7, and 21 days post-SE infection. The results showed a significant correlation between the H/L ratio and the bacterial load in the ileum and caecum at 7 dpi. The ROD21 pathogenicity island absolute and relative excision in the caecum were positively correlated at 1 dpi but negatively correlated at 7 dpi with the H/L ratio. However, in the liver, we found the opposite tendency. The association of the H/L ratio with IL-1β, IL-8, and INF-γ blood serum concentrations showed that a low H/L ratio is correlated with increased IL-1β and INF-γ at 21 dpi. This study confirmed that the H/L ratio is associated with robustness and Salmonella-resistance in chicken. The methodology used in this study can separate individuals into susceptible and resistant and can help in the selection and breeding of Salmonella-resistant chickens.

Investigating the growth performance, meat quality, immune function and proteomic profiles of plasmal exosomes in Lactobacillus plantarum-treated broilers with immunological stress

Exosomes are extracellular membranous nanovesicles that carry functional molecules to mediate cell-to-cell communication. To date, whether probiotics improve the immune function of broilers by plasmal exosome cargo is unclear. In this study, 300 broilers were allocated to three treatments: control diet (CON group), control diet + dexamethasone injection (DEX group), and control diet containing 1 × 10⁸ cfu g^-1 P8 + DEX injection (P8 + DEX group). The growth performance, meat quality and immune function of plasma and jejunal mucosa were detected. Exosomes were isolated from the plasma and characterized. Then, the exosome protein profile was determined by proteomic analysis. Correlation analyses between the exosomal proteins and growth performance, meat quality, immune function were performed. Lastly, the related protein levels were verified by multiple reaction monitoring (MRM). Results showed that P8 treatment increased the growth performance, meat quality and immune function of DEX-induced broilers with immunological stress. Moreover, the average diameters, cup-shaped morphology and expressed exosomal proteins confirmed that the isolated extracellular vesicles were exosomes. A total of 784 proteins were identified in the exosomes; among which, 126 differentially expressed proteins (DEPs) were found between the DEX and CON groups and 102 DEPs were found between the P8 + DEX and DEX groups. Gene ontology analysis indicated that DEPs between the DEX and CON groups are mainly involved in the metabolic process, cellular anatomical entity, cytoplasm, etc. DEPs between the P8 + DEX and DEX groups are mainly involved in the multicellular organismal process, response to stimulus, cytoplasm, etc. Pathway analysis revealed that most of the DEPs between the DEX and CON groups participated in the ECM-receptor interaction, focal adhesion, regulation of actin cytoskeleton, etc. Most of the DEPs between the P8 + DEX and DEX groups participated in the ErbB and PPAR signaling pathways. Moreover, many DEPs were correlated with the altered parameters of growth performance, meat quality and immunity in P8-treated broilers. MRM further revealed that the upregulated FABP6 and EPCAM in the DEX group were decreased by P8 + DEX treatment, and the downregulated C1QTNF3 in the DEX group was increased by P8 + DEX treatment. In conclusion, our findings demonstrated that P8 may promote the immune function, growth performance and meat quality of broilers with immunological stress by regulating the plasma exosomal proteins, especially the proteins of FABP6, EPCAM and C1QTNF3 and the pathway of PPAR (ILK/FABP6).

Microbiological, immunological, and histological changes in the gut of Salmonella Enteritidis-challenged rats fed goat cheese containing Lactobacillus rhamnosus EM1107

Cheeses are able to serve as suitable matrices for supplying probiotics to consumers, enabling appropriate conditions for bacteria to survive gastric transit and reach the gut, where they are assumed to promote beneficial processes. The present study aimed to evaluate the microbiological, immunological, and histological changes in the gut of Salmonella Enteritidis-challenged rats fed goat cheese supplemented with the probiotic strain Lactobacillus rhamnosus EM1107. Thirty male albino Wistar rats were randomly distributed into 5 experimental groups with 6 animals each: negative (NC) and positive (PtC) control groups, control goat cheese (CCh), goat cheese added with L. rhamnosus EM1107 (LrCh), and L. rhamnosus EM1107 only (EM1107). All animals, except NC group were challenged with Salmonella Enteritidis (10⁹ cfu in 1 mL of saline through oral gavage). Microbial composition was assessed with high-throughput 16S rRNA sequencing by means of Illumina MiSeq (Illumina, San Diego, CA). Nuclear factor kappa B (NF-κB) from the animal cecum tissue was determined by real-time PCR and interleukins (TNF-α, IL-1β, IL-10, and IFN-γ) by means of ELISA. Myeloperoxidase and malondialdehyde levels were determined biochemically. The administration of the L. rhamnosus EM1107 probiotic strain, either as a pure culture or added to a cheese matrix, was able to reduce Salmonella colonization in the intestinal lumen and lessen tissue damage compared with rats from PtC group. In addition, the use of cheese for the probiotic strain delivery (LrCh) was associated with a marked shift in the gut microbiota composition toward the increase of beneficial organisms such as Blautia and Lactobacillus and a reduction in NF-κB expression. These findings support our hypothesis that cheeses might be explored as functional matrices for the efficacious delivery of probiotic strains to consumers.

Effects of inulin supplementation on intestinal barrier function and immunity in specific pathogen-free chickens with Salmonella infection

We investigated the effects of inulin on intestinal barrier function and mucosal immunity in Salmonella enterica serovar Enteritidis (SE)-infected specific pathogen-free (SPF) chickens. SPF chickens (n = 240, 1-d-old) were divided into 4 groups (6 replicates per group, 10 chickens per replicate): a control group (CON) fed a basal diet without inulin supplementation and 3 SE-infected groups fed a basal diet supplemented with inulin 0% (SE group), 0.5% (0.5% InSE group), and 1% (1% InSE group), respectively. At 28 d of age, the chickens in SE-infected groups were orally infected with SE and in CON group were administrated with phosphated-buffered saline (PBS). Intestinal morphology, mucosal immunity, and intestinal barrier function-related gene expression were analyzed at 1- and 3-d post-infection (dpi). SE challenge significantly increased the mucosal gene expression, such as interleukin-1β (IL-1β), lipopolysaccharide-induced tumor necrosis factor factor (LITAF), interferon-γ (IFN-γ), and interleukin-6 (IL-6), and increased serum IFN-γ, secretory IgA (sIgA), and IgG concentration, and significantly decreased the gene expression levels of mucin 2 (MUC2) and claudin-1 at 3 dpi compared with the CON group (P < 0.05). Inulin supplementation improved the expression levels of these immunity- and intestinal barrier function-related genes, increased villus height (VH), and decreased crypt depth (CD) in the duodenum, jejunum, and ileum at 1 and 3 dpi within the SE-challenged groups (P < 0.05). SE challenge significantly increased ileal Toll-like receptor 4 (TLR4) mRNA at 1 and 3 dpi, suppressor of cytokine signaling 3 (SOCS3) mRNA at 1 dpi, and phospho-signal transducer and activator of transcription 3 (p-STAT3) and Janus kinase1 (JAK1) protein expression at 3 dpi compared with the CON group (P < 0.05). Inulin supplementation suppressed p-STAT3 and JAK1 protein expression and promoted ileal TLR4 and SOCS3 mRNA expression at 3 dpi compared with SE group (P < 0.05). In conclusion, inulin alleviated SE-induced gut injury by decreasing the proinflammatory response and enhancing mucosal immunity in chickens.

Differential Immune Response of Lactobacillus plantarum 286 Against Salmonella Typhimurium Infection in Conventional and Germ-Free Mice

We aimed at evaluating in vivo the probiotic potential of Lactobacillus plantarum 286 against Salmonella enterica serov. Typhimurium. Colonization capacity and antagonistic activity were determined in feces of gnotobiotic mice. Survival to infection, translocation, histopathology, IgA and cytokine levels (IL-10, IL-6, IFN-γ, TNF-α, TGF-β) were determined both in conventional and germ-free mice followed L. plantarum 286 administration and Salmonella infection. L. plantarum 286 colonized the intestine of gnotobiotic mice, where it produced antagonistic substances against S. Typhimurium. In conventional animals, the administration of this strain increased intestinal IgA levels and reduced the inflammatory response and the tissue damage caused by S. Typhimurium. Reduction of tissue damage in the intestine and liver of germ-free animals was also observed, however the immune response elicited was different in either model. L. plantarum 286 showed in vivo probiotic properties in both murine models. Probiotic capacity results may depend on the animal model chosen.

Development of Salmonellosis as Affected by Bioactive Food Compounds

Infections caused by Salmonella serovars are the leading cause of foodborne hospitalizations and deaths in Americans, extensively prevalent worldwide, and pose a considerable financial burden on public health infrastructure and private manufacturing. While a comprehensive review is lacking for delineating the role of dietary components on prevention of Salmonellosis, evidence for the role of diet for preventing the infection and management of Salmonellosis symptoms is increasing. The current study is an evaluation of preclinical and clinical studies and their underlying mechanisms to elaborate the efficacy of bioactive dietary components for augmenting the prevention of Salmonella infection. Studies investigating dietary components such as fibers, fatty acids, amino acids, vitamins, minerals, phenolic compounds, and probiotics exhibited efficacy of dietary compounds against Salmonellosis through manipulation of host bile acids, mucin, epithelial barrier, innate and adaptive immunity and gut microbiota as well as impacting the cellular signaling cascades of the pathogen. Pre-clinical studies investigating synergism and/or antagonistic activities of various bioactive compounds, additional randomized clinical trials, if not curtailed by lack of equipoise and ethical concerns, and well-planned epidemiological studies could augment the development of a validated and evidence-based guideline for mitigating the public health burden of human Salmonellosis through dietary compounds.

Lactobacillus plantarum ZS2058 and Lactobacillus rhamnosus GG Use Different Mechanisms to Prevent Salmonella Infection in vivo

Pathogen-induced infectious diseases pose great threats to public health. Accordingly, many studies have investigated effective strategies targeting pathogenic infections. We previously reported the preventive effects of Lactobacillus plantarum ZS2058 (ZS2058) and L. rhamnosus GG (LGG) against Salmonella spp. in a murine model. Here, we compared the mechanisms underlying the preventive effects of these Lactobacillus strains in vivo. Notably, reduced C-reactive protein levels were observed with both ZS2058 and LGG, which suggests abrogated anti-infection and inflammatory responses. ZS2058 more efficiently reduced the pathogenicity of Salmonella by increasing the level of propionic acid in feces and production of mucin 2 in the mouse colon and activity through the interleukin (IL)-23/IL-22 and IL-23/IL-17 pathways. Meanwhile, LGG more strongly alleviated gut inflammation, as indicated by changes in the levels of tissue necrosis factor (TNF)-α, IL-10 and myeloperoxidase (MPO) in infected mice. Moreover, both ZS2058 and LGG restored the levels of interferon (INF)-γ, a cytokine suppressed by Salmonella, albeit through different pathways. Our results demonstrate that ZS2058 and LGG prevent Salmonella infection via different mechanisms.

Variability in gut mucosal secretory IgA in mice along a working day

Objective

To assess the variability of secretory immunoglobulin A (S-IgA) in the lumen and feces of mice along a working day.

Results

Mice were maintained under a 12 h light–dark cycle, light period starting at 8 AM. S-IgA was determined in feces and intestinal content (after one or three washes) at three points along the day: at the beginning, in the middle and at the end of the light period (ELP). Significant reduction in the content of S-IgA in the small intestine fluid and in feces was observed at the end of the light cycle, which coincides with the end of a regular working day (8 PM) in any given animal facility. It was also observed that three washes of the small intestine were more effective than one flush to recover a significant higher amount of S-IgA, with the smallest coefficient of variation observed by the ELP. A smaller CV would imply a reduced number of animals needed to achieve the same meaningful results. The results may be useful when designing animal trials for the selection of probiotic candidates based on their capacity of activating S-IgA, since it would imply a more rational use of experimental animals.

Prevalence and Antimicrobial Resistance of Salmonella Isolates from Chicken Carcasses in Retail Markets in Yangon, Myanmar

A cross-sectional investigation was conducted concerning prevalence, antimicrobial resistance, multidrug resistance patterns, and serovar diversity of Salmonella in chicken meat sold at retail in Yangon, Myanmar. The 141 chicken meat samples were collected at 141 retail markets in the Yangon Region, Myanmar, 1 November 2014 to 31 March 2015. Information on hygienic practices (potential risk factors) was retrieved via checklists. Salmonella was isolated and identified according to International Organization for Standardization methods (ISO 6579:2002) with minor modifications. Twelve antimicrobial agents belonging to eight pharmacological groups were used for antimicrobial susceptibility testing (disk diffusion method). Salmonella was recovered from 138 (97.9%) of the 141 samples. The isolates were most frequently resistant to trimethoprim-sulfamethoxazole (70.3% of isolates), tetracycline (54.3%), streptomycin (49.3%), and ampicillin (47.1%). Resistance was also found to chloramphenicol (29.7%), amoxicillin-clavulanic acid (17.4%), ciprofloxacin (9.4%), tobramycin (8.7%), gentamicin (8%), cefazolin (7.2%), lincomycin-spectinomycin (5.8%), and norfloxacin (0.7%). Among the 138 Salmonella isolates, 72 (52.2%) were resistant to three or more antimicrobial agents. Twenty-four serovars were identified among the 138 Salmonella-positive samples; serovars Albany, Kentucky, Braenderup, and Indiana were found in 38, 11, 10, and 8% of samples, respectively. None of the potential risk factors were significantly related to Salmonella contamination of chicken carcasses. This study provides new information regarding prevalence and antimicrobial resistance and Salmonella serovar diversity in retail markets in Yangon, Myanmar.

Selection of new lactic acid bacteria strains bearing probiotic features from mucosal microbiota of healthy calves: Looking for immunobiotics through in vitro and in vivo approaches for immunoprophylaxis applications

From the birth, since their mucosal microbiota and immune system are not fully developed, newborn calves are susceptible to several mucosal pathogenic microorganisms. Operating through humoral and non-humoral mechanisms in the host, several lactic acid bacteria strains bearing probiotic features are often employed in livestock as food supplement, improving animal production performance, promoting health and reducing the severity of mucosal infections. Accordingly, we isolated, species-level identified and screened for their probiotic potentials seventy lactic acid bacteria strains from upper airway, vaginal and intestinal mucosa of healthy calves. Based on in vitro approaches, we selected three strains: Lactobacillus fermentum V3B-08 isolated from upper airway mucosa, Weissella hellenica V1V-30 isolated from vaginal mucosa and Lactobacillus farciminis B4F-06 isolated from intestinal mucosa were used to mono-colonize germ-free mice in the same site in which these strains were isolated, aiming to characterize their immunomodulatory features. These strains were able to colonize germ-free mice mucosa and trigger sIgA synthesis at a local level, in addition to stimulating, in different ways, adaptive immune responses at a systemic level.

Selection of a candidate probiotic strain of Pediococcus pentosaceus from the faecal microbiota of horses by in vitro testing and health claims in a mouse model of Salmonella infection

AIMS

The aim of this study was to verify the suitable use of candidate 'probiotics' selected by in vitro tests and the importance of in vivo assays to nominate micro-organisms as probiotics and alternative prophylactic treatments for Salmonella Typhimurium infection.

METHODS AND RESULTS

Thirty-three lactic acid bacteria (LAB) isolated from foal's faeces were assessed based on the main desirable functional in vitro criteria. Based on these results, Pediococcus pentosaceus strain 40 was chosen to evaluate its putative probiotic features in a mouse model of Salmonella infection. Daily intragastric doses of Ped. pentosaceus 40 for 10 days before and 10 days after Salmonella challenge (10⁶ CFU of Salm. Typhimurium per mouse) led to a significant aggravation in mouse health by increasing weight loss, worsening clinical symptoms and anticipating the time and the number of deaths by Salmonella. Pediococcus pentosaceus modulated cell-mediated immune responses by up-regulation of the gene expression of the proinflammatory cytokines IFN-γ and TNF-α in the small intestine.

CONCLUSION

The usual criteria were used for in vitro screening of a large number of LAB for desirable probiotic functional properties. However, the best candidate probiotic strain identified, Ped. pentosaceus #40, aggravated the experimental disease in mice.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings emphasize the need for prophylactic or therapeutic effectiveness to be demonstrated in in vivo models to make precise health claims.

Modulation of intestinal barrier function to ameliorate Salmonella infection in mice by oral administration of fermented milks produced with Lactobacillus plantarum MTCC 5690 - a probiotic strain of Indian gut origin

Probiotic Lactobacillus plantarum MTCC 5690, a probiotic strain of Indian gut origin, and milk formulations produced with the same were explored in this study as biotherapeutics by evaluating their functional efficacy against Salmonella infection in mice. The efficacy of milk formulations (fermented/unfermented) of MTCC 5690 for enhancement of intestinal barrier function was determined by monitoring the permeability and histopathology of the intestine. Infected mice fed with probiotic Dahi, fermented probiotic drink and sweetened fermented probiotic drink maintained the health and integrity of the intestinal epithelium as compared to those fed with PBS, milk, unfermented probiotic milk and Dahi. Our relative expression data revealed that the changes caused by MTCC 5690 in intestinal barrier function components were established through modulation of the key regulatory receptors Toll-like receptor 2 and Toll-like receptor 4. The results suggest that fermented milks of MTCC 5690 could enhance the defences of the intestinal barrier in enteric infection condition and, therefore, can be explored as a dietary-based strategy to reduce Salmonella infection in the human gut.

Biofilm Forming Lactobacillus: New Challenges for the Development of Probiotics

Probiotics are live bacteria, generally administered in food, conferring beneficial effects to the host because they help to prevent or treat diseases, the majority of which are gastrointestinal. Numerous investigations have verified the beneficial effect of probiotic strains in biofilm form, including increased resistance to temperature, gastric pH and mechanical forces to that of their planktonic counterparts. In addition, the development of new encapsulation technologies, which have exploited the properties of biofilms in the creation of double coated capsules, has given origin to fourth generation probiotics. Up to now, reviews have focused on the detrimental effects of biofilms associated with pathogenic bacteria. Therefore, this work aims to amalgamate information describing the biofilms of Lactobacillus strains which are used as probiotics, particularly L. rhamnosus, L. plantarum, L. reuteri, and L. fermentum. Additionally, we have reviewed the development of probiotics using technology inspired by biofilms.

In vitro assessment of the gastrointestinal tolerance and immunomodulatory function of Bacillus methylotrophicus isolated from a traditional Korean fermented soybean food

AIMS

This study aimed to investigate the potential of Bacillus methylotrophicus as a probiotic.

METHODS AND RESULTS

A Bacillus isolate designated strain C14 was isolated from Korean traditional fermented soybean paste (doenjang). The strain was identified, and its physiological and biochemical properties were characterized. The gastrointestinal tolerance and immunomodulatory function of strain C14 were also investigated. Strain C14 was identified as B. methylotrophicus by analysis of its biochemical properties using the API 50CHB system and by phylogenetic analysis of the 16S rDNA sequence. Strain C14 showed >80% and >75% of survival for artificial gastric juices (pH 2.5 and 1% pepsin) and 0.5% (w/v) bile salt, respectively. Heat-killed B. methylotrophicus C14 inhibited the adhesion of various pathogens and enhanced the adhesion of probiotic bacteria to Caco-2 cells. The heat-killed cells also induced high levels of immune cell proliferation compared with the control and stimulated interleukin-6 and tumour necrosis factor-α production in mouse macrophages.

CONCLUSIONS

Bacillus methylotrophicus C14 could be used as a probiotic.

SIGNIFICANCE AND IMPACT OF THE STUDY

Recently identified B. methylotrophicus is a new potential probiotic with high gastrointestinal tolerance.