Our previous study showed that Lactiplantibacillus plantarum Y42 in the biofilm state can produce more exopolysaccharides and surface-layer proteins and showed a stronger promoting effect on ...intestinal barrier function than that in the planktonic state. In this study, oral administration of the live/pasteurized planktonic or biofilm L. plantarum Y42 and its metabolites (exopolysaccharides and surface-layer proteins) increased the expression of Occludin, Claudin-1, ZO-1, and MUC2 in the gut of the Balb/C mice after exposure to Listeria monocytogenes ATCC 19115 and inhibited the activation of the NLRP3 inflammasome pathway, which in turn reduced the levels of inflammatory cytokines IL-1β and IL-18 in the serum of the mice. Furthermore, oral administration of the live/pasteurized planktonic or biofilm L. plantarum Y42 and its metabolites increased the abundance of beneficial bacteria (e.g., Lachnospiraceae _NK4A136_group and Prevotellaceae _UCG-001) while reducing the abundance of harmful bacteria (e.g., norank_f__ Muribaculaceae) in the gut of the mice, in line with the increase of short-chain fatty acids and indole derivatives in the feces of the mice. Notably, biofilm L. plantarum Y42 exerted a better preventing effect on the intestinal barrier dysfunction of the Balb/C mice due to the fact that biofilm L. plantarumY42 expressed more exopolysaccharides and surface-layer proteins than the planktonic state. These results provide data support for the use of exopolysaccharides and surface-layer proteins extracted from biofilm-state L. plantarum Y42 as functional food ingredients in preventing intestinal barrier dysfunction.
The probiotic potential of lactic acid bacteria primarily point toward colonizing ability of Lactobacilli as the most important attribute for endowing all the known beneficial effects in a host. ...Lactobacillus species exert health-promoting function in the gastrointestinal tract through various mechanisms such as pathogen exclusion, maintenance of microbial balance, immunomodulation, and other crucial functions. It has been seen that many surface layer proteins are involved in host adhesion, and play significant role in the modification of some signaling pathways within the host cells. Interaction between different bacterial cell surface proteins and host receptor has been imperative for a better understanding of the mechanism through which Lactobacilli exert their health-promoting functions.
Highly butanol‐tolerant strains have always been attractive because of their potential as microbial hosts for butanol production. However, due to the amphiphilic nature of 1‐butanol as a solvent, the ...relationship between the cell surface hydrophobicity and butanol resistance remained ambiguous to date. In this work, the quantitatively estimated cell surface hydrophobicity of 74 Lactic acid bacteria strains were juxtaposed to their tolerance to various butanol concentrations. The obtained results revealed that the strains’ hydrophobicity was inversely proportional to their butanol tolerance. All highly butanol‐resistant strains were hydrophilic (cell surface hydrophobicity<1%), whereas the more hydrophobic the strains were, the more sensitive to butanol they were. Furthermore, cultivation at increasing butanol concentrations showed a clear tendency to decrease the level of hydrophobicity in all tested organisms, thus suggesting possible adaptation mechanisms. Purposeful reduction of cell surface hydrophobicity (by removal of S‐layer proteins from the cell envelope) also led to an increase of butanol resistance. Since the results covered 23 different Lactic acid bacteria species of seven genera, it could be concluded that regardless of the species, the lower degree of cells’ hydrophobicity clearly correlates with the higher level of butanol tolerance.
Lactobacillus acidophilus surface layer proteins (SLPs) self-assemble into a monolayer that is non-covalently bound to the outer surface of the cells. There they are in direct contact with the ...environment, environmental stressors and gut components of the host in which the organism resides. The role of L. acidophilus SLPs is not entirely understood, although SLPs seem to be essential for bacterial growth. We constructed three L. acidophilus L-92 strains, each expressing a mutant of the most abundant SLP, SlpA. Each carried a 12-amino acid c-myc epitope substitution at a different position in the protein. A strain was also obtained that expressed the SlpA paralog SlpB from an originally silent slpB gene. All four strains behaved differently with respect to growth under various stress conditions, such as the presence of salt, ox gall or ethanol, suggesting that SlpA affects stress tolerance in L. acidophilus L-92. Also, the four mutants showed differential in vitro binding ability to human host cell proteins such as uromodulin or dendritic cell (DC)-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN). Furthermore, co-culture of murine immature DCs with a mutant strain expressing one of the recombinant SlpA proteins changed the concentrations of the cytokines IL-10 and IL-12. Our data suggest that SlpA and SlpB of L. acidophilus participate in bacterial stress tolerance and binding to uromodulin or DC-SIGN, possibly leading to effective immune-modification.
The outermost constituent of many bacterial cells is represented by an S-layer, i.e., a semiporous lattice-like layer composed of self-assembling protein subunits called S-layer proteins (Slps). ...These proteins are involved in several processes, such as protecting against environmental stresses, mediating bacterial adhesion to host cells, and modulating gut immune response. Slps may also act as a scaffold for the external display of additional cell surface proteins also named S-layer associated proteins (SLAPs). Levilactobacillus brevis is an S-layer forming lactic acid bacterium present in many different environments, such as sourdough, milk, cheese, and the intestinal tract of humans and animals. This microorganism exhibits probiotic features including the inhibition of bacterial infection and the improvement of human immune function. The potential role of Slps in its probiotic and biotechnological features was documented. A shotgun proteomic approach was applied to identify in a single experiment both the Slps and the SLAPs pattern of five different L. brevis strains isolated from traditional sourdoughs of the Southern Italian region. This study reveals that these closely related strains expressed a specific pattern of surface proteins, possibly affecting their peculiar properties.
Aims: To investigate aggregation and adhesiveness of Lactobacillus acidophilus M92 to porcine ileal epithelial cells in vitro, and the influence of cell surface proteins on autoaggregation and ...adhesiveness of this strain.
Methods and Results: Lactobacillus acidophilus M92 exhibits a strong autoaggregating phenotype and manifests a high degree of hydrophobicity determined by microbial adhesion to xylene. Aggregation and hydrophobicity were abolished upon exposure of the cells to pronase and pepsin. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of cell surface proteins revealed the presence of potential surface layer (S‐layer) proteins, approximated at 45 kDa, in L. acidophilus M92. The relationship between autoaggregation and adhesiveness to intestinal tissue was investigated by observing the adhesiveness of L. acidophilus M92 to porcine ileal epithelial cells. Removal of the S‐layer proteins by extraction with 5 mol l−1 LiCl reduced autoaggregation and in vitro adhesion of this strain.
Conclusions: These results demonstrate that there is relationship between autoaggregation and adhesiveness ability of L. acidophilus M92, mediated by proteinaceous components on the cell surface.
Significance and Impact of the Study: This investigation has shown that L. acidophilus M92 has the ability to establish in the human gastrointestinal tract, which is an important determinant in the choice of probiotic strains.
We report investigations on the use of film bulk acoustic resonators for the label-free, multiplexed biosensing of DNA and proteins. The used acoustic resonators were operated in shear mode at about ...800
MHz. From the measured changes of frequency and in dissipation, the mass and the viscoelasticity of biomolecular films formed at the top electrode of the device could be derived, respectively. A mass sensitivity of ∼2
kHz
cm
2/ng and a minimum detectable mass of ∼1
ng/cm
2 were achieved. To demonstrate the highly sensitive detection of the time evolution of protein adsorption, the adsorption kinetics and recrystallisation of bacterial surface layer proteins on gold surfaces were investigated.
Clostridium difficile is a major causative agent of antibiotic-associated diarrhea and has become the most common pathogen of healthcare-associated infection worldwide. The pathogenesis of C. ...difficile infection (CDI) is mediated by many factors such as colonization involving attachment to host intestinal epithelial cells, sporulation, germination, and toxin production. Bacterial cell surface components are crucial for the interaction between the bacterium and host cells. C. difficile has two distinct surface layer proteins (SLPs): a conserved high-molecular-weight SLP and a highly variable low-molecular-weight SLP. Recent studies have shown that C. difficile SLPs play roles not only in growth and survival, but also in adhesion to host epithelial cells and induction of cytokine production. Sequence typing of the variable region of the slpA gene, which encodes SLPs, is one of the methods currently used for typing C. difficile. SLPs have received much attention in recent years as vaccine candidates and new therapeutic agents in the treatment of C. difficile-associated diseases. Gaining mechanistic insights into the molecular functions of C. difficile SLPs will help advance our understanding of CDI pathogenesis and the development of vaccines and new therapeutic approaches. In this review, we summarize the characteristics and immunological roles of SLPs in C. difficile.
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