Comparison of in vitro models to study bacterial adhesion to the intestinal epithelium

Aims:  To evaluate the adhesion ability of intestinal bacteria to different in vitro models of intestinal epithelia, and to estimate the suitability of these models and the type of interactions involved.
Methods and results:  The adhesion of probiotic ( Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp . lactis Bb12), commensal ( B. animalis IATA-A2 and B. bifidum IATA-ES2) and potentially pathogenic bacteria ( E. coli and L. monocytogenes ) was determined. The adhesion models used were polycarbonate-well plates, with or without mucin, and different configurations of Caco-2 and/or HT29-MTX cell cultures. All bacteria adhered to wells without mucin (2·6–27·3%), the values being highly variable depending on the bacterial strain. Adhesion percentages of potentially probiotic bacteria to Caco-2 cultures were remarkably lower ( P  <   0·05) than those to mucin, and more similar to those of pathogenic strains. The lowest adhesion of different bacterial strains was detected on HT29-MTX (0·5–2·3%) cultures and Caco-2/HT29-MTX (0·6–3·2%) cocultures, while these values were increased in Caco-2 cultures plus mucin.
Conclusions:  The results suggested that bacterial strains exhibit different capacities to adhere to cellular components and several types of mucin present in different models, showing preferences for intestinal MUC2.
Significance and impact of the study:  The use of Caco-2 cells monolayer plus mucin (type II) better approaches the physiological characteristics of in vivo situation, providing a reliable and suitable in vitro model to evaluate bacterial adhesion.     

Adhesion properties of <Emphasis Type="Italic">Lactobacillus casei</Emphasis> strains to resected intestinal fragments and components of the extracellular matrix

Adhesion to intestinal epithelium is an outcome property for the selection of probiotic lactic acid bacteria strains. We have analyzed the adhesion properties of a collection of Lactobacillus casei strains from different origins, ranging from cheese isolates to commercial probiotics. Analysis of the surface characteristics of the strains by measuring adhesion to solvents (MATS test) showed that most of the strains have a basic and hydrophobic surface. The strains were able to bind ex vivo to human colon fragments at different levels and, in most cases, this adhesion correlated with the ability to in vitro binding of mucin. Attachment to this later substrate was not enhanced by growing the cells in the presence of mucin and was independent of proteinaceous factors. On the contrary, adhesion to other extracellular matrix components, such as collagen, fibronectin, or fibrinogen was partially or totally dependent on the presence of surface proteins. These results show that most of L. casei strains have in their surfaces factors that promote binding to intestinal epithelium, however, no clear correlation appears to exist between the origin of the strains and their adhesion capacities.     

Bovine Muc1 inhibits binding of enteric bacteria to Caco-2 cells

Inhibition of bacterial adhesion to intestinal epithelial receptors by the consumption of natural food components is an attractive strategy for the prevention of microbial related gastrointestinal illness. We hypothesised that Muc1, a highly glycosylated mucin present in cows’ milk, may be one such food component. Purified bovine Muc1 was tested for its ability to inhibit binding of common enteric bacterial pathogens to Caco-2 cells grown in vitro. Muc1 caused dose-dependent binding inhibition of Escherichia coli, Salmonella enterica serovar Typhimurium (S. Typhimurium), Staphylococcus aureus and Bacillus subtilis. This inhibition was more pronounced for the Gram negative compared with Gram positive bacteria. It was also demonstrated that Muc1, immobilised on a membrane, bound all these bacterial species in a dose-dependent manner, although there was greater interaction with the Gram negative bacteria. A range of monosaccharides, representative of the Muc1 oligosaccharide composition, were tested for their ability to prevent binding of E. coli and S. Typhimurium to Caco-2 cells. Inhibition was structure dependent with sialic acid, L(-) fucose and D(+) mannose significantly inhibiting binding of both Gram negative species. N-acetylglucosamine and N-acetylgalactosamine significantly inhibited binding of E. coli whilst galactose, one of the most abundant Muc1 monosaccharides, showed the strongest inhibition against S. Typhimurium. Treatment with sialidase significantly decreased the inhibitory properties of Muc1, demonstrating the importance of sialic acid in adhesion inhibition. It is concluded that bovine Muc1 prevents binding of bacteria to human intestinal cells and may have a role in preventing the binding of common enteropathogenic bacteria to human intestinal epithelial surfaces.     

Quantitative approach in the study of adhesion of lactic acid bacteria to intestinal cells and their competition with enterobacteria

To describe the phenomena of bacterial adhesion to intestinal cells and the competition for adhesion between bacteria, mathematical equations based on a simple dissociation process involving a finite number of bacterial receptors on intestinal cell surface were developed. The equations allow the estimation of the maximum number of Lactobacillus sp. and Escherichia coli cells that can adhere to Caco-2 cells and intestinal mucus; they also characterize the affinity of the bacteria to Caco-2 cells and intestinal and fecal mucus and the theoretical adhesion ratio of two bacteria present in a mixed suspension. The competition for adhesion between Lactobacillus rhamnosus GG and E. coli TG1 appeared to follow the proposed kinetics, whereas the competition between Lactobacillus casei Shirota and E. coli TG1 may involve multiple adhesion sites or a soluble factor in the culture medium of the former. The displacement of the adhered Lactobacillus by E. coli TG1 seemed to be a rapid process, whereas the displacement of E. coli TG1 by the Lactobacillus took more than an hour.     

Comparative detection of bacterial adhesion to Caco-2 cells with ELISA, radioactivity and plate count methods

Different methods are used to study bacterial adhesion to intestinal epithelial cells, which is an important step in pathogenic infection as well as in probiotic colonization of the intestinal tract. The aim of this study was to compare the ELISA-based method with more conventional plate count and radiolabeling methods for bacterial adhesion detection. An ELISA-based assay was optimized for the detection of Bifidobacterium longum and Escherichia coli O157:H7, which are low and highly adherent bacteria, respectively. In agreement with previous investigations, a percentage of adhesion below 1% was obtained for B. longum with ELISA. However, high nonspecific background and low positive signals were measured due to the use of polyclonal antibodies and the low adhesion capacity with this strain. In contrast, the ELISA-based method developed for E. coli adhesion detected a high adhesion percentage (15%). For this bacterium the three methods tested gave similar results for the highest bacterial concentrations (6.8 Log CFU added bacteria/well). However, differences among methods increased with the addition of decreased bacterial concentration due to different detection thresholds (5.9, 5.6 and 2.9 Log CFU adherent bacteria/well for radioactivity, ELISA and plate count methods, respectively). The ELISA-based method was shown to be a good predictor for bacterial adhesion compared to the radiolabeling method when good quality specific antibodies were used. This technique is convenient and allows handling of numerous samples.     

Quantitative Approach in the Study of Adhesion of Lactic Acid Bacteria to Intestinal Cells and Their Competition with Enterobacteria

To describe the phenomena of bacterial adhesion to intestinal cells and the competition for adhesion between bacteria, mathematical equations based on a simple dissociation process involving a finite number of bacterial receptors on intestinal cell surface were developed. The equations allow the estimation of the maximum number of Lactobacillus sp. and Escherichia coli cells that can adhere to Caco-2 cells and intestinal mucus; they also characterize the affinity of the bacteria to Caco-2 cells and intestinal and fecal mucus and the theoretical adhesion ratio of two bacteria present in a mixed suspension. The competition for adhesion between Lactobacillus rhamnosus GG and E. coli TG1 appeared to follow the proposed kinetics, whereas the competition between Lactobacillus casei Shirota and E. coli TG1 may involve multiple adhesion sites or a soluble factor in the culture medium of the former. The displacement of the adhered Lactobacillus by E. coli TG1 seemed to be a rapid process, whereas the displacement of E. coli TG1 by the Lactobacillus took more than an hour.     

The role of bacterial hydrophobicity in infection: bacterial adhesion and phagocytic ingestion

The role that bacterial surface hydrophobicity (surface tension) plays in determining the extent of adhesion of polymer substrates and phagocytic ingestion is reviewed. The early attachment phase in bacterial adhesion is shown to depend critically on the relative surface tensions of the three interacting phases; i.e., bacteria, substrate, and suspending liquid surface tension. When suspended in a liquid with a high surface tension such as Hanks balanced salt solution, the most hydrophobic bacteria adhere to all surfaces to the greatest extent. When the liquid surface tension (gamma LV) is larger than the bacterial surface tension (gamma BV), then for any single bacterial species the extent of adhesion decreases with increasing substrate surface tension (gamma SV). When gamma LV less than gamma BV then adhesion increases with increasing gamma SV. Bacterial surface tension also determines in part the extent of phagocytic ingestion and the degree to which antibodies specifically adsorb onto the bacterium resulting in opsonization. The nonspecific adsorption of antibodies results in a considerable modification in the surface properties of the bacteria. Bacterial surface hydrophobicity can be altered significantly through exposure to subinhibitory concentrations of antibiotics, surfactants, lectins, etc. The effect of these changes on subsequent phagocytic ingestion is discussed.     

Influence of surface energy of modified surfaces on bacterial adhesion

There are a number of contrary reports on the effect of surface energy of substrates on bacterial adhesion. Some reports showed that bacterial adhesion decreased with decreasing surface energy of substrates; while other reports showed that bacterial adhesion decreased with increasing surface energy of substrates. In this study Escherichia coli adhesion on the Ni--P--PTFE coatings with various surface energies was investigated and the extended DLVO theory was used to calculate the interaction energy between bacteria and the substrates in water. The theory explained the effect of surface energy of substrates on bacterial adhesion.     

Wettability of polymers by mucin aqueous solutions

The wettability of poly(methyl methacrylate) and polyethylene by water and aqueous mucin solutions have been studied by sessile drop and under-water captive air bubble contact angles, respectively. From the sessile drop and octane under-water contact angles the polymer-water interfaces have been characterized in terms of works of adhesion and acid-base (polar) interactions. A large water-air contact angle hysteresis observed with poly(methyl methacrylate) surfaces has been attributed to side-chain beta relaxations of polymer ester methyl groups. The wettabilities of the polymers by mucin aqueous solutions have been studied as a function of protein concentration and related to the surface tensions. A positive slope of adhesion tension vs surface tension line, characteristic of polar surfaces, was found with poly(methyl methacrylate). By contrast, a change in the slope, explained as a change in mucin relative adsorption densities at solid/liquid and solid/vapour interfaces, was observed with polyethylene. This adhesion tension behavior appeared to be in agreement with previous data we have published concerning the quantity and state of mucin which are adsorbed to polymers characterized by different surface properties.     

Adhesive Property of <Emphasis Type="Italic">Bifidobacterium lactis</Emphasis> LKM512 and Predominant Bacteria of Intestinal Microflora to Human Intestinal Mucin

The adhesive property to the intestinal mucin of Bifidobacterium lactis LKM512, B. longum, B. breve, B. bifidum, B. adolescentis, B. infantis, Bacteroides vulgatus, Bacteroides distasonis, Eubacterium aerofaciens, Clostridium perfringens, Escherichia coli, and Lactobacillus acidophilus were examined. Adhesive rate of LKM512 to the mucin was significantly (p < 0.05, 0.01, or 0.001) stronger than the other strains from 2 to 100 time. Though the adhesive property of many strains was almost same to the mucin of 20-year-old and 50-year-old generations, in case of 4-month-old was different. Adhesive inhibitory effect of C. perfringens to the mucin by LKM512 was examined. Under the condition that LKM512 was 10⁸/ml and that C. perfringens was 10⁶/ml, adhesion of C. perfringens to the mucin was inhibited at 99.6%, when LKM512 adhered in advance. There was the strong inhibition of adhesion at 74.0%, when C. perfringens adhered to mucin in advance. Thus, LKM512 can inhibit the adhesion of harmful bacteria to the intestinal mucin, the possibility of using as a probiotic strain has to be verified.     

Bacillus cereus NVH 0500/00 Can Adhere to Mucin but Cannot Produce Enterotoxins during Gastrointestinal Simulation

Adhesion to the intestinal epithelium could constitute an essential mechanism of Bacillus cereus pathogenesis. However, the enterocytes are protected by mucus, a secretion composed mainly of mucin glycoproteins. These may serve as nutrients and sites of adhesion for intestinal bacteria. In this study, the food poisoning bacterium B. cereus NVH 0500/00 was exposed in vitro to gastrointestinal hurdles prior to evaluation of its attachment to mucin microcosms and its ability to produce nonhemolytic enterotoxin (Nhe). The persistence of mucin-adherent B. cereus after simulated gut emptying was determined using a mucin adhesion assay. The stability of Nhe toward bile and pancreatin (intestinal components) in the presence of mucin agar was also investigated. B. cereus could grow and simultaneously adhere to mucin during in vitro ileal incubation, despite the adverse effect of prior exposure to a low pH or intestinal components. The final concentration of B. cereus in the simulated lumen at 8 h of incubation was 6.62 ± 0.87 log CFU ml⁻¹. At that point, the percentage of adhesion was approximately 6%. No enterotoxin was detected in the ileum, due to either insufficient bacterial concentrations or Nhe degradation. Nevertheless, mucin appears to retain B. cereus and to supply it to the small intestine after simulated gut emptying. Additionally, mucin may play a role in the protection of enterotoxins from degradation by intestinal components.     

Bacterial Interactions in Early Life Stages of Marine Cold Water Fish

Abstract The intensive rearing of various fish species in aquaculture has revealed intimate relationships between fish and bacteria that eventually may affect establishment of a ``normal' mucosal microflora or result in disease epizootics. Interactions between bacteria and mucosal surfaces play important roles both at the egg and larval stages of marine fish. Bacterial adhesion and colonization of the egg surface occur within hours after fertilization. The diverse flora which eventually develops on the egg appears to reflect the bacterial composition and load of the ambient water, but species-specific adhesion at the egg surface may also play a role in development of the egg epiflora. Proteolytic enzymes produced by members of the adherent epiflora may cause serious damage to the developing egg and may also affect further adhesion of the epiflora. Ingestion of bacteria at the yolk sac stage results in establishment of a primary intestinal microflora which seems to persist beyond first feeding. Establishment of a gut microflora is likely to undergo several stages, resulting in an ``adult' microflora weeks to months after first feeding. Ingested bacteria may serve as an exogenous supply of nutrients or essential factors at an early life stage. Early exposure to high bacterial densities is probably important for immune tolerance, and thus for the establishment of a protective intestinal microflora. Successful rearing of early life stages of several marine fish species depends on knowledge of the complex interactions among the cultured organisms and the bacterial communities which develop at the mucosal surfaces and in the ambient water and rearing systems. The routine use of antibiotics during rearing of fish larvae is not advisable, since it may increase the risk of promoting antibiotic resistance and adversely affect the indigenous microflora of the larvae. The use of probiotics has proven advantageous in domestic animal production, and the search for effective probiotics may have a great potential in aquaculture of marine organisms. Bacteria with antagonistic effects against fish pathogens have been successfully administered to several fish species, resulting in decreased mortality or increased growth rate. Received: 14 December 1998; Accepted: 7 April 1999     

Dependence of the initial adhesion of biofilm forming Pseudomonas putida mt2 on physico-chemical material properties

Bacterial adhesion is strongly dependent on the physico-chemical properties of materials and plays a fundamental role in the development of a growing biofilm. Selected materials were characterized with respect to their physico-chemical surface properties. The different materials, glass and several polymer foils, showed a stepwise range of surface tensions (γ_s) between 10.3 and 44.7 mN m^?1. Measured zeta potential values were in the range between ?74.8 and ?28.3 mV. The initial bacterial adhesion parameter q _max was found to vary between 6.6 × 10⁶ and 28.1 × 10⁶ cm^?2. By correlation of the initial adhesions kinetic parameters with the surface tension data, the optimal conditions for the immobilization of Pseudomonas putida mt2 were found to be at a surface tension of 24.7 mN m^?1. Both higher and lower surface tensions lead to a smaller number of adherent cells per unit surface area. Higher energy surfaces, commonly termed hydrophilic, could constrain bacterial adhesion because of their more highly ordered water structure (exclusion zone) close to the surface. At low energy surfaces, commonly referred to as hydrophobic, cell adhesion is inhibited due to a thin, less dense zone (depletion layer or clathrate structure) close to the surface. Correlation of q _max with zeta potential results in a linear relationship. Since P. putida carries weak negative charges, a measurable repulsive effect can be assumed on negative surfaces.     

基于双工程菌的“锁扣”生物活材料构建及其体内肠道滞留应用

生物活材料的研究主要集中在利用单一细菌生产生物膜、水塑料等体外应用。由于菌株尺寸较小，当其应用于体内时，容易发生逃逸，导致滞留效果较差。为解决这一难题，本研究借助大肠杆菌(Escherichia coli)表面展示系统(Neae)，在两个菌株表面分别展示SpyTag和SpyCatcher，构建一种双菌“锁扣”型生物活材料生产系统。两菌株之间通过SpyTag和SpyCatcher的结合，发生原位交联，从而长时间滞留在肠道部位。体外实验表明两菌株混合几分钟后，会发生明显的沉降。此外，利用共聚焦成像和微流控平台进一步证明了该系统在流动状态下的粘附效果。最后，为了验证该系统在体内应用的可行性，小鼠连续3d口服A菌(p15A-Neae-SpyTag/sfGFP)和B菌(p15A-Neae-SpyCatcher/mCherry)，收集肠道组织进行冷冻切片染色。结果表明，相较于未结合菌株，该双菌系统能更多滞留在小鼠肠道，为生物活材料进一步的体内应用奠定了基础。     

Separate oligosaccharide determinants mediate interactions of the low-molecular-weight salivary mucin with neutrophils and bacteria.

The low-molecular-weight human salivary mucin (MG2) coats oral surfaces, where it is in a prime location for governing cell adhesion. Since oligosaccharides form many of the interactive facets on mucin molecules, we examined MG2 glycosylation as it relates to the molecule's adhesive functions. Our previous study of MG2 oligosaccharide structures showed that the termini predominantly carry T, sialyl-T, Lewisx (Lex), sialyl Lex (sLex), lactosamine, and sialyl lactosamine determinants [Prakobphol, A., et al. (1998) Biochemistry 37, 4916-4927]. In addition, we showed that sLex determinants confer L-selectin ligand activity to this molecule. Here we studied adhesive interactions between MG2 and cells that traffic in the oral cavity: neutrophils and bacteria. Under flow conditions, neutrophils tethered to MG2-coated surfaces at forces between 1.25 and 2 dyn/cm2, i.e., comparable to the shear stress generated at the tooth surface by salivary flow ( approximately 0.8 dyn/cm2). MG2 was also found in association with neutrophils isolated from the oral cavity, evidence that the cells interact with this mucin in vivo. Since MG2 serves as an adhesion receptor for bacteria, the MG2 saccharides that serve this function were also identified. Seven of 18 oral bacteria strains that were tested adhered to MG2. Importantly, six of these seven strains adhered via T antigen, sialyl-T antigen, and/or lactosamine sequences. No adherence to Lex and sLex epitopes was detected in all the strains that were tested. Together, these results suggest that distinct subsets of MG2 saccharides function as ligands for neutrophil L-selectin and receptors for bacterial adhesion, a finding with interesting implications for both oral health and mucin function.     

Bacterial adhesion to a model surface with self-generated protection coating of mucin via jacalin

Using a mechanism of `self-generation', polymer surfaces were coated with ocular mucin-type glycoproteins that were extracted from tear fluid and immobilized through specific interaction with a lectin, jacalin. Separately, jacalin affinity chromatography of tear fluid showed the main retained components had molecular weights higher than 200 kDa. In evaluations of bacterial adhesion, a model surface with jacalin-immobilized ocular mucins took up a significantly smaller number of adhered Staphylococcus epidermidis (0.041×10⁶ cells cm^–2) than a bare surface of the same polymer (1.202×10⁶ cells cm^–2). The lectin-mediated ocular mucin coating reduced the bacteria uptake by about 95% showing that the presence of mucin on surfaces may afford a general protection against bacterial colonization.     

The VSL#3 probiotic formula induces mucin gene expression and secretion in colonic epithelial cells

Several studies have stressed the importance of the microbiota in the maintenance of the gastrointestinal epithelium. Administration of probiotic bacteria, supplements composed of microbiota constituents, was previously shown to diminish symptoms in patients suffering from inflammatory bowel diseases. This raises the possibility that probiotics may play an active role in enhancing the intestinal barrier at the mucosal surface. In this study, we investigated whether the clinically tested VSL#3 probiotic formula and/or its secreted components can augment the protective mucus layer in vivo and in vitro. For in vivo studies, Wistar rats were orally administered the probiotic mixture VSL#3 on a daily basis for seven days. After treatment, basal luminal mucin content increased by 60%. In addition, we exposed isolated rat colonic loops to the VSL#3 probiotic formula, which significantly stimulated colonic mucin (MUC) secretion and MUC2 gene expression; however, MUC1 and MUC3 gene expression were only slightly elevated. The effect of the VSL#3 mucin secretagogue was also tested in vitro by use of LS 174T colonic epithelial cells. In contrast to the animal studies, cultured cells incubated with VSL#3 bacteria did not exhibit increased mucin secretion. However, the bacterial secreted products contained in the conditioned media stimulated a remarkable mucin secretion effect. Among the three bacterial groups (Lactobacilli, Bifidobacteria, and Streptococci) contained in VSL#3, the Lactobacillus species were the strongest potentiator of mucin secretion in vitro. A preliminary characterization of the putative mucin secretagogue suggested that it was a heat-resistant soluble compound, which is not sensitive to protease and DNase treatment. These findings contribute to a better understanding of the complex and beneficial interaction between colonic epithelial cells and intestinal bacteria.     

Oral infection with enteropathogenic Escherichia coli triggers immune response and intestinal histological alterations in mice selected for their minimal acute inflammatory responses

Enteropathogenic Escherichia coli (EPEC), a leading cause of infant diarrhea, is an important public health problem in Brazil and other developing countries. In vitro assays of bacterial adhesion to cultured cells are important tools for studying bacterial pathogenicity but do not reproduce all the events that occur in natural infections. In this study, the effects of oral infection with EPEC on mice selected for their minimal acute inflammatory response (AIRmin) were evaluated. Mice were orally infected with EPEC and variations in body weight, bacterial shedding and antibody production observed. The infected animals developed seric and secretory anti‐EPEC antibodies; however, neither mortality nor diarrhea was observed. Light microscopy of their intestines demonstrated histological modifications that were not present in controls. However, electron microscopy did not show bacteria attached to the intestinal epithelia to form attaching and effacing lesions, characteristic of EPEC in humans. The bacteria were detected in Peyer's patches and intestinal contents up to 5 hr post‐infection. When human anti‐EPEC secretory immunoglobulin A or avian immunoglobulin Y antibodies were administered to infected animals, they developed minor histological alterations compared with non‐treated animals. In summary, it was found that EPEC triggers immune responses and intestinal histological alterations but does not produce evidence of diarrheal disease in mice infected by the oral route. This study of EPEC experimental infection provides a better understanding of the effects of antibodies on bacterial infections and may provide a suitable model for the design and testing of immunobiological products for active or passive immunization.     

Alteration of bacterial surface electrostatic potential and pH upon adhesion to a solid surface and impacts to cellular bioenergetics

In our previous study [Hong Y, Brown DG (2009) Appl Environ Microbiol 75(8):2346–2353], the adenosine triphosphate (ATP) level of adhered bacteria was observed to be 2–5 times higher than that of planktonic bacteria. Consequently, the proton motive force (Δp) of adhered bacteria was approximately 15% greater than that of planktonic bacteria. It was hypothesized that the cell surface pH changes upon adhesion due to the charge‐regulated nature of the bacterial cell surface and that this change in surface pH can propagate to the cytoplasmic membrane and alter Δp. In the current study, we developed and applied a charge regulation model to bacterial adhesion and demonstrated that the charge nature of the adhering surface can have a significant effect on the cell surface pH and ultimately the affect the ATP levels of adhered bacteria. The results indicated that the negatively charged glass surface can result in a two‐unit drop in cell surface pH, whereas adhesion to a positively charged amine surface can result in a two‐unit rise in pH. The working hypothesis indicates that the negatively charged surface should enhance Δp and increase cellular ATP, while the positively charged surface should decrease Δp and decrease ATP, and these results of the hypothesis are directly supported by prior experimental results with both negatively and positively charged surfaces. Overall, these results suggest that the nature of charge on the solid surface can have an impact on the proton motive force and cellular ATP levels. Biotechnol. Bioeng. 2010;105: 965–972. © 2009 Wiley Periodicals, Inc.     

Surface displaced alfa-enolase of Lactobacillus plantarum is a fibronectin binding protein

Background  

Lactic acid bacteria of the genus Lactobacillus and Bifidobacterium are one of the most important health promoting groups of the human intestinal microbiota. Their protective role within the gut consists in out competing invading pathogens for ecological niches and metabolic substrates. Among the features necessary to provide health benefits, commensal microorganisms must have the ability to adhere to human intestinal cells and consequently to colonize the gut. Studies on mechanisms mediating adhesion of lactobacilli to human intestinal cells showed that factors involved in the interaction vary mostly among different species and strains, mainly regarding interaction between bacterial adhesins and extracellular matrix or mucus proteins. We have investigated the adhesive properties of Lactobacillus plantarum, a member of the human microbiota of healthy individuals.