No abstract

Increased gut permeability is suggested to be involved in the pathogenesis of a growing number of disorders. The altered intestinal barrier and the subsequent translocation of bacteria or bacterial products into the internal milieu of the human body induce the inflammatory state. Gut microbiota maintains intestinal epithelium integrity. Since dysbiosis contributes to increased gut permeability, the interventions that change the gut microbiota and correct dysbiosis are suggested to also restore intestinal barrier function. In this review, the current knowledge on the role of biotics (probiotics, prebiotics, synbiotics and postbiotics) in maintaining the intestinal barrier function is summarized. The potential outcome of the results from in vitro and animal studies is presented, and the need for further well-designed randomized clinical trials is highlighted. Moreover, we indicate the need to understand the mechanisms by which biotics regulate the function of the intestinal barrier. This review is concluded with the future direction and requirement of studies involving biotics and gut barrier.

Aims: The assessment of the bacterial viability of chlorine-and quaternary ammonium compounds (QACs)-treated Lactobacillus cells by culture-dependent and -independent methods. Methods and Results: Lactobacillus isolates (Lactobacillus plantarum G1, Lactobacillus plantarum B1, Lactobacillus brevis S1 and Lactobacillus paracasei W1) in biofilm and planktonic cell suspensions were treated with chlorine-based (0Á018 and 0Á18%) and QACs-based (0Á2 and 2Á0%) disinfectants for 5 min and then analysed by plate counting, flow cytometry (FCM) and fluorescence activated cell sorting (FACS). The reaction of sessile cells to disinfectants was assessed with the confocal laser scanning microscopy (CLSM). Plate counts revealed L. paracasei W1 to be substantially inactivated by both disinfectants, while counts of the other isolates to be significantly reduced only by QACs, with L. plantarum B1 and L. brevis S1 showing a greater difference between QACs concentrations and cell types. In several cases, the disinfectants caused slightly higher inactivation of planktonic than biofilm cells, with L. plantarum B1 being significantly less sensitive to QACs in biofilm cells (P < 0Á05). Following FCM with a Syto â 9/PI assay, which addresses cell membrane integrity, the emergence of damaged (Syto â 9 À PI + ) and injured (Syto â 9 + PI + ) subpopulations was often observed in cells when they were treated with QACs, whereas intact (Syto â 9 + PI À ) and unstained (Syto â 9 À PI À ) subpopulations were mostly encountered in chlorine-treated cells. Except Syto â 9 À PI + , all subpopulations were recovered on agar plates following FACS, with biofilm cells showing higher culturability irrespective of conditions, probably because of the residues of the biofilm matrix which serve as a protective cover for the bacteria. The CLSM revealed a substantial cell membrane damage within the QACs-treated biofilms, however, some cells deep in the biofilm were still intact and thus remained protected against this disinfectant. Conclusion: We found that FCM/FACS proved useful in the analysis of lactobacilli membrane integrity in disinfection experiments as well as in recovery evaluation of planktonic-biofilm cell subpopulations. In turn, CLSM was particularly useful in investigating the resistance mechanism when Lactobacillus cells were embedded in biofilms. Significance and Impact of the Study: This study highlights the need for treatment optimization on a case-by-case basis to avoid the emergence of cells in intermediate states with recovery potential and to reach and, thus, kill all bacteria in already developed lactobacilli biofilms.

pH stress is recognized as an important feature for Lactobacillus in relation to lifestyle and commercial utility. Hence, this study aims to investigate the cell function of Lactobacilli cells subjected to pHs between 7.0 and 2.0. For this purpose, the Lactobacilli isolates of vegetable origin were first hybridized with fluorescent oligonucleotide rRNA probes for detecting Lactobacillus species. Then, cells were exposed to pH stress and labelled with fluorescent probes, carboxyfluorescein diacetate (CFDA) and propidium iodine (PI), which provided the insight into esterase activity and membrane integrity of cells. Among isolates, fluorescence in situ hybridization (FISH) enabled us to specifically detect L. plantarum and L. brevis. Interestingly, FCM analysis revealed that at pHs between 7.0 and 4.0 the cell membrane was intact, while after the exposure at pH 3.0, and 2.0 became perturbed or impaired. Finally, L. brevis and L. plantarum differed from each other in fluorescence labeling behaviour and culturability. However, the results showed that the same standard protocol for labeling enables discrimination of subpopulations of tested species. Depending on the species, the substantial culturability loss was observed at pH 3.0 and 2.0. These results suggest that the taxonomic and physiological fluorescent probes could be suitable for in situ detection of specific bacteria and rapid assessment of the physiological status of cells.