Adhesion of Lactobacillus plantarum 423 and Lactobacillus salivarius 241 to the intestinal tract of piglets, as recorded with fluorescent in situ hybridization (FISH), and production of plantaricin 423 by cells colonized to the ileum

Delivery of Probiotic-Loaded Microcapsules in the Gastrointestinal Tract: A Review

Probiotics are live microorganisms that inhabit the gastrointestinal tract and confer health benefits to consumers. However, a sufficient number of viable probiotic cells must be delivered to the specific site of interest in the gastrointestinal tract to exert these benefits. Enhanced viability and tolerance to sublethal gastrointestinal stress can be achieved using appropriate coating materials and food matrices for orally consumed probiotics. The release mechanism and interaction of probiotic microcapsules with the gastrointestinal tract have been minimally explored in the literature to date. To the authors' knowledge, no review has been published to discuss the nature of release and the challenges in the targeted delivery of probiotics. This review addresses gastrointestinal-related complications in the formulation of targeted delivery and controlled release of probiotic strains. It investigates the impacts of environmental stresses during the transition stage and delivery to the target region in the gastrointestinal tract. The influence of factors such as pH levels, enzymatic degradation, and redox conditions on the release mechanisms of probiotics is presented. Finally, the available methods to evaluate the efficiency of a probiotic delivery system, including in vitro and in vivo, are reviewed and assessed. The paper concludes with a discussion highlighting the emerging technologies in the field and emphasising key areas in need of future study.

Protective Effects of Novel Lactobacillaceae Strains Isolated from Chicken Caeca against Necrotic Enteritis Infection: In Vitro and In Vivo Evidences

The present study aimed to show the benefits of novel lactic acid bacteria (LAB) strains isolated from the caeca of healthy chickens. These novel strains, identified as Limosilactobacillus reuteri and Ligilactobacillus salivarius, displayed high levels of lactic acid production, capability of biofilm formation, high aggregation and adhesion scores, and significant survival rates under conditions mimicking the chicken gastrointestinal tract (GIT). In addition, these novel Lactobacillaceae isolates were neither hemolytic nor cytotoxic. In vivo trials were able to establish their ability to reduce necrotic enteritis. Notably, a significant weight gain was registered, on day 10 of treatment, in the group of chickens fed with a mixture of L. reuteri ICVB416 and L. salivarius ICVB430 strains, as compared with the control group. This group has also shown a reduced number of lesions in the gut compared with other infected chicken groups. This study provides in vitro and in vivo evidence supporting the benefits of these novel Lactobacillaceae isolates for their use in poultry livestock as protective cultures to control the bacterial necrotic enteritis (NE) Clostridium perfringens.

Heterologous Expression of the Class IIa Bacteriocins, Plantaricin 423 and Mundticin ST4SA, in Escherichia coli Using Green Fluorescent Protein as a Fusion Partner

The antilisterial class IIa bacteriocins, plantaricin 423 and mundticin ST4SA, have previously been purified from the cell-free supernatants of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA, respectively. Here, we present the fusions of mature plantaricin 423 and mundticin ST4SA to His-tagged green fluorescent protein (GFP) for respective heterologous expression in Escherichia coli. Fusion of plantaricin 423 and mundticin ST4SA to His-tagged GFP produced the fusion proteins GFP-PlaX and GFP-MunX, respectively. Both fusion proteins were autofluorescent, circumvented inclusion body formation and lowered the toxicity of class IIa bacteriocins during heterologous expression. Not only did GFP-class IIa fusion stabilize heterologous expression and boost yields, the fluorescent intensity of GFP-PlaX and GFP-MunX could be monitored quantitatively and qualitatively throughout expression and purification. This robust fluorometric property allowed rapid optimization of conditions for expression and bacteriocin liberation from GFP via the incorporated WELQut protease cleavage sequence. Incubation temperature and IPTG concentration had a significant effect on bacteriocin yield, and was optimal at 18°C and 0.1-0.2 mM, respectively. GFP-MunX was approximately produced at a yield of 153.30 mg/L culture which resulted in 12.4 mg/L active mundticin ST4SA after liberation and HPLC purification. While GFP-PlaX was produced at a yield of 121.29 mg/L culture, evidence suggests heterologous expression resulted in conformation isomers of WELQut liberated plantaricin 423.

Identificación de Bacillus toyonensis en heces de ganado cebú en el Departamento de Sucre, Colombia

Se evaluaron las características probióticas de cepas nativas aisladas de ganado cebú y se realizó identificación molecular de una de estas cepas, para considerar su posterior aplicación como aditivos microbianos en la alimentación bovina. Se usaron muestras de estiércol de terneros de levante, se aislaron bacterias y levaduras, determinándose la capacidad probiótica de estas cepas mediante pruebas como; resistencia a sales biliares (0.05, 0.1, 0.15 y 0.3 %), resistencia a pH ácido (pH 3, 4, 5.6, 7), tolerancia a NaCl (2, 4, 6, 8,10 %), actividad antagónica (Salmonella spp., y Escherichia coli), producción de gas a partir de la glucosa, y crecimiento a diferentes temperaturas (37 y 40 °C). La identificación preliminar de las cepas se realizó mediante: tinción de Gram, tinción de endosporas (método de Wirtz), prueba de la catalasa, prueba de oxidasa. Se seleccionó una de las cepas que superó las pruebas probióticas para su identificación mediante métodos moleculares y se realizó el análisis filogenético de la misma utilizando la base de datos NCBI Reference Sequence (RefSeq). Los ensayos se organizaron en un diseño completamente al azar, los resultados obtenidos por triplicado se sistematizaron en el software Statgraphics Centurion XVI y el efecto de los diferentes tratamientos se analizó estadísticamente mediante análisis de varianza. Se aislaron 10 cepas nativas, identificándose molecularmente a Bacillus toyonensis. Esta investigación representa el primer reporte molecular de B. toyonensis en estiércol de terneros de levante cebú en el Departamento de Sucre, el cual ha sido ampliamente utilizado como probiótico en la nutrición animal.

Bacteriocin production and adhesion properties as mechanisms for the anti-listerial activity of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA

Probiotics play an important role in maintaining a healthy and stable intestinal microbiota, primarily by preventing infection. Probiotic lactic acid bacteria (LAB) are known to be inhibitory to many bacterial enteric pathogens, including antibiotic-resistant strains. Whilst the positive role that probiotics have on human physiology, specifically in the treatment or prevention of specific infectious diseases of the gastro-intestinal tract (GIT) is known, the precise mechanistic basis of these effects remains a major research goal. In this study, molecular evidence to underpin the protective and anti-listerial effect of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA against orally administered Listeria monocytogenes EGDe in the GIT of mice is provided. Bacteriocins plantaricin 423 and mundticin ST4SA, produced by L. plantarum 423 and E. mundtii ST4SA, respectively, inhibited the growth of L. monocytogenes in vitro and in vivo. Bacteriocin-negative mutants of L. plantarum 423 and E. mundtii ST4SA failed to exclude L. monocytogenes EGDe from the gastrointestinal tract (GIT) of mice. Furthermore, L. plantarum 423 and E. mundtii ST4SA failed to inhibit recombinant strains of L. monocytogenes EGDe in vivo that expressed the immunity proteins of the two bacteriocins. These results confirmed that bacteriocins plantaricin 423 and mundticin ST4SA acted as anti-infective mediators in vivo. Compared to wild type strains, mutants of L. plantarum 423 and E. mundtii ST4SA, in which the adhesion genes were knocked out, were less effective in the exclusion of L. monocytogenes EGDe from the GIT of mice. This work demonstrates the importance of bacteriocin and adhesion genes as probiotic anti-infective mechanisms.

In vivo bioluminescence imaging of the spatial and temporal colonization of lactobacillus plantarum 423 and enterococcus mundtii ST4SA in the intestinal tract of mice

Background

Lactic acid bacteria (LAB) are major inhabitants and part of the normal microflora of the gastrointestinal tract (GIT) of humans and animals. Despite substantial evidence supporting the beneficial properties of LAB, only a few studies have addressed the migration and colonization of probiotic bacteria in the GIT. The reason for this is mostly due to the limitations, or lack of, efficient reporter systems. Here we describe the development and application of a non-invasive in vivo bioluminescence reporter system to study, in real-time, the spatial and temporal persistence of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA in the intestinal tract of mice.

Results

This study reports on the application of the firefly luciferase gene (ffluc) from Photinus pyralis to develop luciferase-expressing L. plantarum 423 and E. mundtii ST4SA, using a Lactococcus lactis NICE system on a high copy number plasmid (pNZ8048) and strong constitutive lactate dehydrogenase gene promoters (Pldh and STldh). The reporter system was used for in vivo and ex vivo monitoring of both probiotic LAB strains in the GIT of mice after single and multiple oral administrations. Enterococcus mundtii ST4SA reached the large intestine 45 min after gavage, while L. plantarum 423 reached the cecum/colon after 90 min. Both strains predominantly colonized the cecum and colon after five consecutive daily administrations. Enterococcus mundtii ST4SA persisted in faeces at higher numbers and for more days compared to L. plantarum 423.

Conclusions

Our findings demonstrate the efficiency of a high-copy number vector, constitutive promoters and bioluminescence imaging to study the colonization and persistence of L. plantarum 423 and E. mundtii ST4SA in the murine GIT. The system allowed us to differentiate between intestinal transit times of the two strains in the digestive tract. This is the first report of bioluminescence imaging of a luciferase-expressing E. mundtii strain to study colonization dynamics in the murine model. The bioluminescence system developed in this study may be used to study the in vivo colonization dynamics of other probiotic LAB.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1315-4) contains supplementary material, which is available to authorized users.

The effects of feeding Lactobacillus pentosus on growth, immunity, and disease resistance in Haliotis discus hannai Ino

To study the effects of probiotic-added food on the survival and growth of abalone (Haliotis discus hannai Ino), the expression levels of nonspecific immune genes and the anti-Vibrio parahaemolyticus infection were examined. During an 8-week culturing experiment in an indoor aquarium and a 2-week V. parahaemolyticus artificial infection experiment, the control group was fed with untreated food once a day, while the experimental groups (L1, L2 and L3) were fed with Lactobacillus pentosus added food. The concentration of probiotics in the experimental food was 10³ cfu/g (L1), 10⁵ cfu/g (L2) and 10⁷ cfu/g (L3), respectively. The results showed that the survival rate, shell length-specific growth rate, and the food conversion rate (FCR) of abalones in L1 and L2 were significantly higher than the control group. The food intake of abalones in L3 was significantly lower than that in L1, L2 and the control group, but there was no significant difference in FCR identified between L1, L2 and L3. In the L. pentosus-added groups, the total number of blood lymphocytes, lysozyme activity, acid phosphatase, superoxide dismutase, and expression levels of Mn-superoxide dismutase (Mn-SOD) and thioredoxin peroxidase (TP_x) were significantly higher than the control group, while the malondialdehyde (MDA) content was significantly lower than the control group. The phagocytic activity of blood lymphocytes, catalase activity and the expression levels of heat shock protein 70 (HSP70) of abalones in the control group were significantly lower than that in L1 and L2, but there was no significant difference when compared with L3. The levels of O₂^-, NO produced by respiratory burst of blood lymphocytes and the expression levels of catalase (CAT) in L1 and L2 were significantly higher than both L3 and the control group. Seven days after infection with V. parahaemolyticus, all abalones in the control group were dead. After 14 days the cumulative mortality rate of abalones in the L. pentosus-added groups was significantly lower than that in the control group. Therefore, the 10³ cfu/g and 10⁵ cfu/g L. pentosus-added food not only promoted food intake and growth of abalones, but also improved their non-specific immunity and reduced V. parahaemolyticus infection, indicating that this strain is a good potential candidate for probiotic added food in the aquaculture industry.

Applications and safety considerations of Lactobacillus salivarius as a probiotic in animal and human health

The goals of this review are to summarize the current knowledge on the application of Lactobacillus salivarius as a probiotic in animals and humans, and to address safety concerns with its use on live hosts. Overall, several strains of L. salivarius are well established probiotics with multiple applications in animal health, particularly to reduce colonization by gastrointestinal pathogens, and to a lesser extent, as a production and quality aid. In humans, L. salivarius has been used to prevent and treat a variety of chronic diseases, including asthma, cancer, atopic dermatitis and halitosis, and to a much limited extent, to prevent or treat infections. Based on the results from primary research evidence, it seems that L. salivarius does not pose a health risk to animals or humans in the doses currently used for a variety of applications; however, there is a systematic lack of studies assuring the safety of many of the strains intended for clinical use. This review provides researchers in the field with up-to-date information regarding applications and safety of L. salivarius. Furthermore, it helps researchers identify knowledge gaps and potential opportunities for microbiological and clinical research.

A Dual-Biotic System for the Concurrent Delivery of Antibiotics and Probiotics: In Vitro, Ex Vivo, In Vivo and In Silico Evaluation and Correlation

PURPOSE

A delayed release bio-polymeric Dual-Biotic system has been extensively evaluated in this study to overcome the therapeutic issue of probiotic killing due to incorrect administration with the antibiotic.

METHODS

In vitro and ex vivo release and characterization studies have been undertaken on the Dual-Biotic system. In vivo analyses utilizing a Large White pig model were also performed with commercial products used as a comparison. Intestinal fluid for probiotic quantification was aspirated using a surgically implanted intestinal cannula with Lactobacillus acidophilus cell counts determined through luminescence and inoculation onto Lactobacilli-specific agar. Plasma amoxicillin concentrations were determined through Ultra-Performance Liquid Chromatography. The reactional profile and crosslinking mechanism of ovalbumin and genipin was elucidated using molecular mechanic energy relationships in a vacuum system by exploring the spatial disposition of different concentrations of genipin with respect to ovalbumin with ovalbumin/genipin ratios of 1:1, 1:5 and 1:10.

RESULTS

In vivo evaluation of the Dual-Biotic system detailed maximum Lactobacillus viability (~455% baseline viability) 6 h after oral administration. Concurrent administration of the commercial products revealed a 75% decrease in bacterial viability when compared to the controls analyzed. A level A in vitro-in vivo correlation was also established with 96.9% predictability of amoxicillin release ascertained. The computational results achieved corroborated well with the experimental findings and physicochemical data.

CONCLUSIONS

Evaluation and correlation of the Dual-Biotic system has detailed the success of the formulation for the concurrent delivery of an antibiotic and probiotic.

Antioxidative effects in vivo and colonization of Lactobacillus plantarum MA2 in the murine intestinal tract

Lactobacillus plantarum MA2 was isolated from traditional Chinese Tibet kefir grains, which possess several excellent properties and functions. We previously demonstrated the antioxidant activities of this bacterium in vitro. However, the maintenance and survival of L. plantarum MA2 inside the murine intestinal tract, where it exerts its probiotic properties, and whether its effects are elicited directly on the host remain unknown. Therefore, this study investigated the mechanisms of L. plantarum MA2 in aging mice following D-galactose administration. The levels of malondialdehyde decreased significantly in the L. plantarum MA2 groups after oral ingestion compared to the D-galactose model group, and total antioxidant capacity and glutathione peroxidase and superoxide dismutase activities increased significantly in the serum and liver. We combined fluorescein isothiocyanate labeling and green fluorescent protein expression to dynamically monitor the colonization and distribution of L. plantarum MA2 in the murine intestinal tract. The results indicated that L. plantarum MA2 was detected in the ileum, colon, and feces after single and continuous oral administration at day 21 and was maintained at 10(4)-10(5) CFU/g. These results suggest that L. plantarum MA2 colonizes and survives in the murine intestinal tract to exert its antioxidative effects.

Encapsulation of Lactobacillus plantarum 423 and its Bacteriocin in Nanofibers

Plantaricin 423, produced by Lactobacillus plantarum 423, was encapsulated in nanofibers that were produced by the electrospinning of 18% (w/v) polyethylene oxide (200 000 Da). The average diameter of the nanofibers was 288 nm. Plantaricin 423 activity decreased from 51 200 AU/ml to 25 600 AU/ml and from 204 800 AU/ml to 51 200 AU/ml after electrospinning, as determined against Lactobacillus sakei DSM 20017 and Enterococcus faecium HKLHS, respectively. Cells of L. plantarum 423 encapsulated in nanofibers decreased from 2.3 × 10(10) cfu/ml before electrospinning to 4.7 × 10(8) cfu/ml thereafter. Cells entrapped in the nanofibers continued to produce plantaricin 423. This is the first report on the encapsulation of a bacteriocin and cells of L. plantarum in nanofibers. The method may be used to design a drug delivery system for bacteriocins and the encapsulation of probiotic lactic acid bacteria. The technology is currently being optimized.

Spatial Localization and Binding of the Probiotic Lactobacillus farciminis to the Rat Intestinal Mucosa: Influence of Chronic Stress

The present study aimed at detecting the exogenously applied probiotic Lactobacillus farciminis in rats, after exposure to IBS-like chronic stress, based on 4-day Water Avoidance Stress (WAS). The presence of L. farciminis in both ileal and colonic mucosal tissues was demonstrated by FISH and qPCR, with ileum as the preferential niche, as for the SFB population. A different spatial distribution of the probiotic was observed: in the ileum, bacteria were organized in micro-colonies more or less close to the epithelium whereas, in the colon, they were mainly visualized far away from the epithelium. When rats were submitted to WAS, the L. farciminis population substantially decreased in both intestinal regions, due to a stress-induced increase in colonic motility and defecation, rather than a modification of bacterial binding to the intestinal mucin Muc2.

Use of the mCherry Fluorescent Protein To Study Intestinal Colonization by Enterococcus mundtii ST4SA and Lactobacillus plantarum 423 in Mice

Lactic acid bacteria (LAB) are natural inhabitants of the gastrointestinal tract (GIT) of humans and animals, and some LAB species receive considerable attention due to their health benefits. Although many papers have been published on probiotic LAB, only a few reports have been published on the migration and colonization of the cells in the GIT. This is due mostly to the lack of efficient reporter systems. In this study, we report on the application of the fluorescent mCherry protein in the in vivo tagging of the probiotic strains Enterococcus mundtii ST4SA and Lactobacillus plantarum 423. The mCherry gene, encoding a red fluorescent protein (RFP), was integrated into a nonfunctional region on the genome of L. plantarum 423 by homologous recombination. In the case of E. mundtii ST4SA, the mCherry gene was cloned into the pGKV223D LAB/Escherichia coli expression vector. Expression of the mCherry gene did not alter the growth rate of the two strains and had no effect on bacteriocin production. Both strains colonized the cecum and colon of mice.

Analysis of biofilm formation by intestinal lactobacilli

In this study, the biofilm-forming potential of intestinal Lactobacillus reuteri strains under different culture conditions was characterized by microtiter plate biofilm assays. Moreover, the spatial organization of exogenously applied L. reuteri L2/6 (a pig isolate) at specific locations in gastrointestinal tract of monoassociated mice was investigated by fluorescence in situ hybridization. We did not detect biofilm formation by tested strains in nutrient-rich de Man–Rogosa–Sharpe (MRS) medium. On the contrary, a highly positive biofilm formation was observed in medium with lower accessibility to the carbon sources and lack of salts. The results obtained confirmed the significant role of Tween 80 and the quantity and nature of the sugars in the growth medium in biofilm formation. The omission of Tween 80 in MRS medium favored the formation of biofilm. Abundant biofilm formation was detected in the presence of lactose, galactose, and glucose. However, a gradual increase in sugar concentration triggered a significant decrease in biofilm formation. In addition, conditions related to the gastrointestinal environment, such as low pH and the presence of bile and mucins, highly modulated biofilm production. This effect seems to be dependent on the specificity and properties of the medium used for cultivation. From the evidence provided by this study we conclude that the biofilm formation capacity of L. reuteri is strongly dependent on the environmental factors and culture medium used.

A review of the advancements in probiotic delivery: Conventional vs. non-conventional formulations for intestinal flora supplementation

Probiotic delivery systems are widely used nutraceutical products for the supplementation of natural intestinal flora. These delivery systems vary greatly in effectiveness to exert health benefits for a patient. Probiotic delivery systems can be categorized into conventional, pharmaceutical formulations, and non-conventional, mainly commercial food-based, products. The degree of health benefits provided by these probiotic formulations varies in their ability to deliver viable, functional bacteria in large enough numbers (effectiveness), to provide protection against the harsh effects of the gastric environment and intestinal bile (in vivo protection), and to survive formulation processes (viability). This review discusses the effectiveness of these probiotic delivery systems to deliver viable functional bacteria focusing on the ability to protect the encapsulated probiotics during formulation process as well as against harsh physiological conditions through formulation enhancements using coatings and polymer enhancements. A brief overview on the health benefits of probiotics, current formulation, patient and legal issues facing probiotic delivery, and possible recommendations for the enhanced delivery of probiotic bacteria are also provided. Newer advanced in vitro analyses that can accurately determine the effectiveness of a probiotic formulation are also discussed with an ideal probiotic delivery system hypothesized through a combination of the two probiotic delivery systems described.

Behavior of lactobacilli isolated from fermented slurry (ben-saalga) in gnotobiotic rats

Most bacterial strains, which have been studied so far for their probiotic functions, are extensively used by manufacturers in developed countries. In our work, we sought to study a mix (called BSL) comprising three strains belonging to Lactobacillus fermentum, L. paraplantarum and L. salivarius, that were isolated from a traditional African pearl millet based fermented slurry. Our objective was to study this BSL cocktail in gnotobiotic rats, to evaluate their survival and their behavior in the digestive tract conditions. After a single oral inoculation of germfree rats with BSL, the species established stably in the digestive tract with the following hierarchy of abundance: L. salivarius> L. plantarum> L. fermentum. BSL cocktail was metabolically active since it produced 50 mM lactate and it expressed genes involved in binding mechanism in the caecum. Furthermore, the global morphology of the colon epithelium was not disturbed by the BSL cocktail. BSL cocktail did not modify mucus content and host mucus-related genes (MUC1, MUC2, MUC3 or resistin-like molecule β). The cocktail of lactobacilli enhanced the proliferating cell nuclear antigen (PCNA) at a level comparable to what was observed in conventional rats. PCNA was involved in proliferation and DNA repair, but the presence of the cocktail did not provoke proliferative events (with Ki67 as indicator), so we suppose BSL may help gut preservation. This work is the first step towards the selection of strains that are derived from traditional fermented food to formulate new probiotic mixture.

Class IIa bacteriocins: diversity and new developments

Class IIa bacteriocins are heat-stable, unmodified peptides with a conserved amino acids sequence YGNGV on their N-terminal domains, and have received much attention due to their generally recognized as safe (GRAS) status, their high biological activity, and their excellent heat stability. They are promising and attractive agents that could function as biopreservatives in the food industry. This review summarizes the new developments in the area of class IIa bacteriocins and aims to provide uptodate information that can be used in designing future research.

Microencapsulation of probiotics for gastrointestinal delivery

The administration of probiotic bacteria as nutraceuticals is an area that has rapidly expanded in recent years, with a global market worth $32.6 billion predicted by 2014. Many of the health promoting claims attributed to these bacteria are dependent on the cells being both viable and sufficiently numerous in the intestinal tract. The oral administration of most bacteria results in a large loss of viability associated with passage through the stomach, which is attributed to the high acid and bile salt concentrations present. This loss of viability effectively lowers the efficacy of the administered supplement. The formulation of these probiotics into microcapsules is an emerging method to reduce cell death during GI passage, as well as an opportunity to control release of these cells across the intestinal tract. The majority of this technology is based on the immobilization of bacteria into a polymer matrix, which retains its structure in the stomach before degrading and dissolving in the intestine, unlike the diffusion based unloading of most controlled release devices for small molecules. This review shall provide an overview of progress in this field as well as draw attention to areas where studies have fallen short. This will be followed by a discussion of emerging trends in the field, highlighting key areas in which further research is necessary.

Distinct adhesion of probiotic strain Lactobacillus casei ATCC 393 to rat intestinal mucosa

Adhesion to the intestine represents a critical parameter for probiotic action. In this study, the adhesion ability of Lactobacillus casei ATCC 393 to the gastrointestinal tract of Wistar rats was examined after single and daily administration of fermented milk containing either free or immobilized cells on apple pieces. The adhesion of the probiotic cells at the large intestine (cecum and colon) was recorded at levels ≥6 logCFU/g (suggested minimum levels for conferring a probiotic effect) following daily administration for 7 days by combining microbiological and strain-specific multiplex PCR analysis. Single dose administration resulted in slightly reduced counts (5 logCFU/g), while they were lower at the small intestine (duodenum, jejunum, ileum) (≤3 logCFU/g), indicating that adhesion was a targeted process. Of note, the levels of L. casei ATCC 393 were enhanced in the cecal and colon fluids both at single and daily administration of immobilized cells (6 and 7 logCFU/g, respectively). The adhesion of the GI tract was transient and thus daily consumption of probiotic products containing the specific strain is suggested as an important prerequisite for retaining its levels at an effective concentration.

New topics and limits related to the use of beneficial microbes in pig feeding

Reports highlighting the positive effects of probiotics on the performance of pigs or on in vitro traits are now quite frequent, but the use of probiotics in feed compounds has not been widespread. Prerequisites for the healthy and efficient growth of young pigs are the rapid maturation of the gut mucosa and the mucosa-associated lymphoid tissue, and the formation of a local stable and complex bacterial community. In neonatal pigs, suckling and the maternal environment shape the gut microbiota. Later, when weaning stress causes a transient drop in favourable bacteria, the oral supply of microbes could contribute to re-establish the microbiota balance. Some strains isolated from piglets were tested for their ability to settle in the intestine. After weaning, piglets experience new and often unfavourable bacteria. Probiotics have been investigated to contrast the enteropathogens, owing to their properties (production of antibacterial molecules, competition on adhesion sites, stimulation of immune response, etc.). Data in general show that their oral administration can be favourable or, at least, innocuous. However, two cases are presented here, where a probiotic given to pigs already combating enteropathogens impaired pig health, and this could be explained by their effect on the immune response. A more tolerogenic response of the host is expected when beneficial bacteria directly contrast the pathogens, probiotics are claimed to directly modulate or even activate the immune system. For one probiotic divergent effects on growth and health are presented, and these differences may be due to different experimental details or different starting microbiological environments. Scarce data are available on specific immune responses induced by commensal microbes in pigs, and on the interaction of resident microbiota with orally supplied probiotics. Increased knowledge of the role of commensal microbiota in the gut and in the pig metabolism, helps in selecting the best bacteria and in designing the best feeding strategies for improving the efficacy and the reliability of their oral use.

Probiotic properties of Lactobacillus salivarius and closely related Lactobacillus species

Lactobacillus salivarius has been frequently isolated from the mammalian digestive tract and has been studied as a candidate probiotic. Research to date has described the immunomodulatory properties of the species in cell-lines, mice, rats and humans for the alleviation of intestinal disease and the promotion of host well-being. The ability of L. salivarius to inhibit pathogens and tolerate host antimicrobial defenses demonstrates the adaptation of this species to the gastrointestinal niche. L. salivarius is the best characterized of 25 species in the L. salivarius clade of the genus Lactobacillus. Several other species of this clade are candidate probiotics; however, their probiotic potential has not yet been exploited. This review summarizes the research defining the probiotic nature of L. salivarius, by focusing in particular on L. salivarius UCC118 as a representative strain. The emergent research detailing the probiotic potential of other species in this phylogenetic clade will also be discussed.

Surface and adhesion properties of lactobacilli

The surface properties of lactobacilli are of significant technological importance as they determine the interaction of the bacterial cells with the gastrointestinal mucosa, and therefore influence their location in the gut and their functionality. Studying the surface of the bacteria is critical for understanding the adhesion process better. This review compiles the knowledge from studies on the characterization Lactobacillus surfaces and evaluates the potential relationship between the cells' physicochemical characteristics and their adhesive abilities. It also discusses the effect that the production processes, such as fermentation and drying, can exert on the surface properties and adhesion abilities of lactobacilli.

Safety Assessment of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA Determined in Trials with Wistar Rats

Colonization of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA in the gastro-intestinal tract was determined by using Wistar rats as model. The strains were administered through intragastric gavage over 14 days. FISH with strain-specific oligonucleotide probes indicated that Lact. plantarum 423 adhered to the surfaces of the ileum and the cecum. Enterococcus mundtii ST4SA, on the other hand, adhered to the surfaces of the cecum and colon. Results obtained by DGGE have shown that strains 423 and ST4SA excluded Enterobacteriaceae, but not lactic acid bacteria, from the cecum and colon. No signs of perforation of epithelial cells by strains 423 and ST4SA were detected. The spleen and liver appeared healthy and blood counts were normal, suggesting that the strains are not pathogenic. Both strains produce antimicrobial peptides active against a number of pathogens and may be considered as probiotics.

Ecophysiology of the developing total bacterial and lactobacillus communities in the terminal small intestine of weaning piglets

Weaning of the pig is generally regarded as a stressful event which could lead to clinical implications because of the changes in the intestinal ecosystem. The functional properties of microbiota inhabiting the pig's small intestine (SI), including lactobacilli which are assumed to exert health-promoting properties, are yet poorly described. Thus, we determined the ecophysiology of bacterial groups and within genus Lactobacillus in the SI of weaning piglets and the impact of dietary changes. The SI contents of 20 piglets, 4 killed at weaning (only sow milk and no creep feed) and 4 killed at 1, 2, 5, and 11 days post weaning (pw; cereal-based diet) were examined for bacterial cell count and bacterial metabolites by fluorescence in situ hybridization (FISH). Lactobacilli were the predominant group in the SI except at 1 day pw because of a marked reduction in their number. On day 11 pw, bifidobacteria and E. coli were not detected, and Enterobacteriaceae and members of the Clostridium coccoides/Eubacterium rectale cluster were only found occasionally. L. sobrius/L. amylovorus became dominant species whereas the abundance of L. salivarius and L. gasseri/johnsonii declined. Concentration of lactic acid increased pw whereas pH, volatile fatty acids, and ammonia decreased. Carbohydrate utilization of 76 Lactobacillus spp. isolates was studied revealing a shift from lactose and galactose to starch, cellobiose, and xylose, suggesting that the bacteria colonizing the SI of piglets adapt to the newly introduced nutrients during the early weaning period. Identification of isolates based on partial 16S rRNA gene sequence data and comparison with fermentation data furthermore suggested adaptation processes below the species level. The results of our study will help to understand intestinal bacterial ecophysiology and to develop nutritional regimes to prevent or counteract complications during the weaning transition.

Cell surface Lactobacillus plantarum LA 318 glyceraldehyde-3-phosphate dehydrogenase (GAPDH) adheres to human colonic mucin

AIMS

To characterize the adhesion molecule of Lactobacillus plantarum LA 318 that shows high adhesion to human colonic mucin (HCM).

METHODS AND RESULTS

The adhesion test used the BIACORE assay where PBS-washed bacterial cells showed a significant decrease in adherence to HCM than distilled water-washed cells. A component in the PBS wash fraction adhered to the HCM and a main protein was detected as a c. 40-kDa band using SDS-PAGE. Using homology comparisons of the N-terminal amino acid sequences compared with sequence databases, this protein was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The DNA sequence of LA 318 GAPDH was 100% identical to the GAPDH (gapB) of L. plantarum WCFS1. The purified GAPDH adhered to HCM.

CONCLUSIONS

We found the adhesin of L. plantarum LA 318 to HCM in its culture PBS wash fraction. The molecule was identified as GAPDH. Because LA 318 possesses the same adhesin as many pathogens, the lactobacilli GAPDH may compete with pathogens infecting the intestine.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report showing GAPDH expressed on the cell surface of lactobacilli adheres to mucin suggesting L. plantarum LA 318 adheres to HCM using GAPDH binding activity to colonize the human intestinal mucosa.

Adherence factors of Lactobacillus in the human gastrointestinal tract

Despite the increasing number of scientific reports describing adhesion of Lactobacillus to components of the human intestinal mucosa, information on the surface molecules mediating this adhesion and their corresponding receptors is fragmentary. This MiniReview compiles present knowledge of the genetically and functionally characterized Lactobacillus factors responsible for mediating adhesion to different components of the human gastrointestinal tract. In addition, for the proteins among these factors, the domain structure is discussed, and where appropriate the results of in silico analyses are reported.

Fate of the two-component lantibiotic lacticin 3147 in the gastrointestinal tract

The component peptides of lacticin 3147 were degraded by alpha-chymotrypsin in vitro with a resultant loss of antimicrobial activity. Activity was also lost in ileum digesta. Following oral ingestion, neither of the lacticin 3147 peptides was detected in the gastric, jejunum, or ileum digesta of pigs, and no lacticin 3147 activity was found in the feces. These observations suggest that lacticin 3147 ingestion is unlikely to have adverse effects, since it is probably inactivated during intestinal transit.