The effect of cell surface components on adhesion ability of Lactobacillus rhamnosus

In vitro analysis on the adhesion potential of Lactiplantibacillus plantarum from infant faeces and its gastrointestinal localization, growth promotion, and immunomodulation in Wistar rats: a preliminary study

Lactic acid bacteria, found in heterogenous niches, are known for their health-endorsing properties and are in demand as prospective probiotics. Hence, the scientific community around the globe is in continuous search for novel and new potential strains with extensive applicability and minimum risk. In this context, the present study evaluated the efficiency of Lactiplantibacillus plantarum (P2F2) of human origin, a highly autoaggregating and coaggregating (with pathogens) strain, for its colonization, growth promotion, and immunomodulation. Results indicated moderate hydrophobicity on adhesion to xylene and n-hexadecane and weak electron-donating properties with chloroform. The biofilm of P2F2 formed on polystyrene was strong and highly correlated to exopolysaccharide production. The autoaggregation was moderately correlated with hydrophobicity and biofilm production. It was noted that the P2F2 strain modulated the gut microbiota and increased intestinal villi length in Wistar rats. The lipid and glucose profiles remained intact. P2F2 treatment increased the activity of reactive oxygen species-generating cells in the peritoneal cavity, besides augmenting the mitogen-induced splenocyte proliferation and maintained the immunoglobulins at the normal level. Results from this study conclusively suggest that the strain P2F2 adheres to the intestine and modulates the gut ecosystem besides enhancing cell-mediated immunity without altering the serological parameters tested.

Protective Effect of Probiotics against Pseudomonas aeruginosa Infection of Human Corneal Epithelial Cells

Probiotic therapy needs consideration as an alternative strategy to prevent and possibly treat corneal infection. This study aimed to assess the preventive effect of Lactobacillus reuteri and Bifidobacterium longum subsp. infantis on reducing the infection of human corneal epithelial (HCE) cells caused by Pseudomonas aeruginosa. The probiotics' preventive effect against infection was evaluated in cell monolayers pretreated with each probiotic 1 h and 24 h prior to P. aeruginosa challenge followed by 1 h and 24 h of growth in combination. Cell adhesion, cytotoxicity, anti-inflammatory, and antinitrosative activities were evaluated. L. reuteri and B. longum adhered to HCE cells, preserved occludin tight junctions' integrity, and increased mucin production on a SkinEthicTM HCE model. Pretreatment with L. reuteri or B. longum significantly protected HCE cells from infection at 24 h, increasing cell viability at 110% (110.51 ± 5.15; p ≤ 0.05) and 137% (137.55 ± 11.97; p ≤ 0.05), respectively. Each probiotic showed anti-inflammatory and antinitrosative activities, reducing TNF-α level (p ≤ 0.001) and NOx amount (p ≤ 0.001) and reestablishing IL-10 level (p ≤ 0.001). In conclusion, this study demonstrated that L. reuteri and B. longum exert protective effects in the context of corneal infection caused by P. aeruginosa by restoring cell viability and modulating inflammatory cytokine release.

Lactobacillus acidophilus JYLA-126 Ameliorates Obesity-Associated Metabolic Disorders by Positively Regulating the AMPK Signaling Pathway Through the Gut-Liver Axis

Obesity is a chronic metabolic disease worldwide and is considered a major health problem in contemporary society. Lactobacillus acidophilus have demonstrated beneficial effects on obesity, but the specific mechanism of how it exerts beneficial effects has not been elucidated. Here, we found that L. acidophilus JYLA-126 had good biological properties for intestinal health, such as antioxidation, acid tolerance, bile salt tolerance, antimicrobial activity, and gut colonization. We further identified that supplementation of L. acidophilus JYLA-126 obese mice possessed a dose-dependent amelioration of body weight, intestinal imbalance, and metabolic disorders compared to HFD-induced mice. Mechanistically, the excellent slimming effect of L. acidophilus JYLA-126 was achieved mainly by reversing HFD-induced gut dysbiosis, inhibiting inflammatory factors and balancing the homeostasis of the gut-liver axis. Specifically, L. acidophilus JYLA-126 improved hepatic glycogen synthesis, lowered oxidative stress, and facilitated lipid metabolism by regulating AMPK signaling pathway-related protein expression to restore the overall metabolic level. Accordingly, L. acidophilus JYLA-126 promoted energy uptake efficiency in obese mice, resulting in significant expression of uncoupling protein 1 (UCP1) protein in brown adipose tissue (BAT), and markedly reduced the size of adipocytes. These findings indicate that the anti-obesity activity of L. acidophilus JYLA-126 correlates with activation of the AMPK signaling pathway through improved gut-liver interactions.

The Impact in Intestines and Microbiota in BALB/c Mice Through Consumption of Milk Fermented by Potentially Probiotic Lacticaseibacillus casei SJRP38 and Limosilactobacillus fermentum SJRP43

The present study aimed to evaluate the effect of consumption of milk fermented by Lacticaseibacillus (Lc.) casei SJRP38 and Limosilactobacillus (Lm.) fermentum SJRP43 on bacterial translocation, stool analysis, and intestinal morphology of healthy BALB/c mice. Potentially probiotic lactic acid bacteria, Lc. casei SJRP38, and Lm. fermentum SJRP43 were evaluated and analyzed for translocation, fecal analysis, and intestinal morphology of four groups of mice: water control (WC), milk control (MC), milk fermented by Lc. casei SJRP38 (FMLC), and milk fermented by Lm. fermentum SJRP43 (FMLF), in co-culture with Streptococcus thermophilus ST080. The results of the animal assay indicate that the population of Lactobacilli and Bidobacterium sp. in the gastrointestinal tract of BALB/c mice was greater than 6.0 log10 CFU/g, and there was no evidence of bacteremia due to the low incidence of bacterial translocation. Ingesting fermented milk containing Lc. casei SJRP38 and Lm. fermentum SJRP43 was found to promote a healthier microbiota, as it led to a reduction in Clostridium sp. and an increase in Lactobacilli and Bifidobacterium sp. in feces. Furthermore, the dairy treatments (MC, FMLC, and FMLF) resulted in taller intestinal villi and an increase in the frequency of goblet cells in the intestines. Overall, the consumption of fermented milk containing Lc. casei SJRP38 and Lm. fermentum SJRP43 strains was deemed safe and demonstrated beneficial effects on the intestines of BALB/c mice.

Probiotic potentials of lactic acid bacteria isolated from Egyptian fermented food

Lactic acid bacteria (LAB) are of major concern due to their health benefits. Fermented food products comprise variable LAB demonstrating probiotic properties. Discovering and evaluating new probiotics in fermented food products poses a global economic and health importance. Therefore, the present work aimed to investigate and evaluate the probiotic potentials of LAB strains isolated from Egyptian fermented food. In this study, we isolated and functionally characterized 100 bacterial strains isolated from different Egyptian fermented food sources as probiotics. Only four LAB strains amongst the isolated LAB showed probiotic attributes and are considered to be safe for their implementation as feed or dietary supplements. Additionally, they were shown to exert antimicrobial activities against pathogenic bacteria and anticancer effects against the colon cancer cell line Caco-2. The Enterococcus massiliensis IS06 strain was exclusively reported in this study as a probiotic strain with high antimicrobial, antioxidant, and anti-colon cancer activity. Hitherto, few studies have focused on elucidating the impact of probiotic supplementation in vivo. Therefore, in the current study, the safety of the four strains was tested in vivo through the supplementation of rats with potential probiotic strains for 21 days. The results revealed that probiotic bacterial supplementation in rats did not adversely affect the general health of rats. The Lactiplantibacillus plantarum IS07 strain significantly increased the growth performance of rats. Furthermore, the four strains exhibited increased levels of antioxidants such as superoxide dismutase and glutathione in vivo. Consistently, all strains also showed high antioxidant activity of the superoxide dismutase enzyme in vitro. Overall, these findings demonstrated that these isolated potential probiotics harbor desirable characteristics and can be applied widely as feed additives for animals or as dietary supplements for humans to exert their health benefits and combat serious diseases.

Nanomechanical changes in probiotic bacteria under antibiotics exposure: Implications on Lactobacillus biofilm formation

Recognition of the microbial cell's surface constituents' biophysical properties is an important research topic, allowing a better understanding of the cell's behaviour under different conditions. Atomic force microscopy (AFM) was employed in this study to analyse the basis of the nanomechanical changes in probiotic bacteria under nitrofurantoin, furazolidone, and nitrofurazone exposure. Recorded significant changes in the two Lactobacillus strains cells morphology, topography, and adhesion parameters resulted in the increase of the cells' longitude (up to 2.58 μm), profile height (by around 0.50 μm), and decrease in the adhesion force (up to 13.58 nN). Young's modulus and adhesion energy decreased within 96 h, however with no negative effect on the cells' morphology or loss of structural integrity. Observed modifications present the mode of action of the 5-nitrofuran derivative antibiotics on probiotic biofilm formation and suggest activation of the multilevel adaptation mechanisms to counteract unfavorable environments. A visual change in bacterial morphology such as an increased surface-to-volume ratio might be a link between molecular-level events and outcomes in individual cells and biofilms. This paper for the first time shows, that these antibiotics affect the properties of non-target microorganisms as lactobacilli, and might impair biofilm formation. However, the degree of such transformations depends on the delivered active substance.

Assessing the Effectiveness of Fermented Banana Peel Extracts for the Biosorption and Removal of Cadmium to Mitigate Inflammation and Oxidative Stress

This study identified 11 lactic acid bacteria (LAB) strains that exhibited tolerance to heavy metal cadmium concentrations above 50 ppm for 48 h. Among these strains, T126-1 and T40-1 displayed the highest tolerance, enduring cadmium concentrations up to 500 ppm while still inhibiting bacterial growth by 50%. Moreover, the fermentation of banana peel using LAB significantly enhanced the clearance rate of cadmium (p < 0.05) compared to nonfermented banana peel. Additionally, the LAB-fermented banana peel exhibited higher 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and reduced power values. Strain T40-1 exhibited a significant improvement in its ability to chelate ferrous ions (p < 0.05). Regarding antibiotic resistance, both the T40-1 and TH3 strains demonstrated high resistance with a third-level inhibition rate against ampicillin and tetracycline. Cell viability tests revealed that incubation with the T40-1 and TH3 strains for a duration of 24 h did not result in any cellular damage. Moreover, these LAB strains effectively mitigated oxidative stress markers, such as reactive oxygen species (ROS), glutathione (GSH), and lactate dehydrogenase (LDH), caused by 2 ppm cadmium on cells. Furthermore, the LAB strains were able to reduce the inflammatory response, as evidenced by a decrease in interleukin-8 (IL-8) levels (p < 0.05). The use of Fourier transform infrared (FT-IR) spectroscopy analysis provided valuable insight into the interaction between metal ions and the organic functional groups present on the cell wall of fermented banana peel. In summary, this study highlights the potential of the LAB strains T40-1 and TH3 in terms of their tolerance to the cadmium, ability to enhance cadmium clearance rates, and their beneficial effects on oxidative stress, inflammation, and cell viability.

Stress Response in Bifidobacteria

Bifidobacteria naturally inhabit diverse environments, including the gastrointestinal tracts of humans and animals. Members of the genus are of considerable scientific interest due to their beneficial effects on health and, hence, their potential to be used as probiotics. By definition, probiotic cells need to be viable despite being exposed to several stressors in the course of their production, storage, and administration. Examples of common stressors encountered by probiotic bifidobacteria include oxygen, acid, and bile salts. As bifidobacteria are highly heterogenous in terms of their tolerance to these stressors, poor stability and/or robustness can hamper the industrial-scale production and commercialization of many strains. Therefore, interest in the stress physiology of bifidobacteria has intensified in recent decades, and many studies have been established to obtain insights into the molecular mechanisms underlying their stability and robustness. By complementing traditional methodologies, omics technologies have opened new avenues for enhancing the understanding of the defense mechanisms of bifidobacteria against stress. In this review, we summarize and evaluate the current knowledge on the multilayered responses of bifidobacteria to stressors, including the most recent insights and hypotheses. We address the prevailing stressors that may affect the cell viability during production and use as probiotics. Besides phenotypic effects, molecular mechanisms that have been found to underlie the stress response are described. We further discuss strategies that can be applied to improve the stability of probiotic bifidobacteria and highlight knowledge gaps that should be addressed in future studies.

The Influence of the Degree of Thermal Inactivation of Probiotic Lactic Acid Bacteria and Their Postbiotics on Aggregation and Adhesion Inhibition of Selected Pathogens

The study aimed to evaluate the effect of thermal inactivation of potentially probiotic lactic acid bacteria (LAB) strains isolated from food on their ability to compete with pathogenic microorganisms. Five strains of LAB, previously isolated from food and characterized, one commercial reference strain of Lactiplantibacillus plantarum 299v, and two indicator strains of Staphylococcus aureus 25923 and Listeriamonocytogenes 15313 were used in the study. The experiment consisted in applying a stress factor (high temperature: 80 °C, at a different time: 5, 15, and 30 min) to the tested LAB cells to investigate the in vitro properties such as hydrophobicity abilities (against p-xylene and n-hexadecane), auto-aggregation, co-aggregation with pathogens, and inhibition of pathogens adhesion to the porcine gastric mucin. The bacterial strains showed various hydrophobicity to p-xylene (36-73%) and n-hexadecane (11-25%). The affinity for solvents expanded with increasing thermal inactivation time. All LAB isolates were able to auto-aggregate (ranging from 17 to 49%). Bacterial strains subjected to 5 and 15 min of thermal inactivation had the highest auto-aggregation ability in comparison to viable and heat-killed cells for 30 min. The LAB strains co-aggregated with pathogens to different degrees; among them, the highest scores of co-aggregation were observed for L. monocytogenes, reaching 27% (with 15 min of heat-killed LAB cells). All LAB strains reduced the adherence of pathogenic bacteria in the competition test, moreover, heat-killed cells (especially 15 min inactivated) were more efficient than viable cells. The properties of selected LAB strains as moderately heat-stressed forms analyzed in the study increased the prevention of colonization and elimination of pathogenic bacteria in the in vitro model of gastrointestinal tract. The thermal inactivation process may therefore preserve and modifies some characteristics of bacterial cells.

Parabacteroides distasonis Properties Linked to the Selection of New Biotherapeutics

Dysbiotic microbiota is often associated with health issues including inflammatory bowel disease or ulcerative colitis. In order to counterbalance host disorder caused by an alteration in the gut composition, numerous studies have focused on identifying new biotherapeutic products (NBPs). Among the promising NBPs is Parabacteroides distasonis, a gut microbiota member part of the core microbiome that recently has received much attention due to the numerous beneficial properties it brings to its host. In this study, the properties linked to the selection of NBPs were screened in 14 unrelated P. distasonis strains, including resistance to gastric conditions, adherence (Caco-2 model), transepithelial resistance (Caco-2 model), and immunomodulation, on nontreated and LPS-stimulated cells (HT-29 and peripheral blood mononuclear cells (PBMCs)). This approach allowed for the identification of five strains that combined almost all the in vitro biotherapeutic properties tested. However, all the P. distasonis strains induced the overproduction of proinflammatory cytokines on PBMCs, which was counteracted by the overproduction of the anti-inflammatory cytokines. Among these five strains, two particularly retained our attention as a potential NBP, by showing strong health-promoting function, the lowest overproduction of proinflammatory cytokines on PBMCs, and no detrimental effect on the host.

Characterization of autochthonous lactobacilli from goat dairy products with probiotic potential for metabolic diseases

The present study aimed to design functional fermented goat milk with probiotic potential for metabolic diseases. Thereby, autochthonous lactobacilli from goat dairy products that target improving the inflammatory, lipid, and glycemic profile were characterized. We designed fermented goat milk using Lactobacillus delbrueckii subsp. indicus CRL1447 as starter strain, supplemented with different probiotic consortia formed by Limosilactobacillus fermentum CRL1446, Lactiplantibacillus paraplantarum CRL1449, and CRL1472 strains. These lactobacilli were selected for their positive effects on inhibition of α-glucosidase, bile salts hydrolase activity, cholesterol assimilation, and decreased triglyceride percentage in Caenorhabditis elegans. Furthermore, the lactobacilli oral administration to obese mice caused a significant decrease in body weight gain and ameliorated hyperglycemia and hyperlipemia. These results reveal the potential of this goat dairy product as a functional food to prevent obesity and related pathologies. Goat milk-derived products stand out for their marketing potential. Hence, fermented goat milk incorporating novel probiotics represents a group of food products with broad prospects by their promising nutritive and therapeutic properties for metabolic diseases. The goat dairy product designed in this study could be used in the prevention of dyslipidemia and hyperglycemia in obese people.

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New probiotic consortium (CRL1449, CRL1472, and ​CRL1446) was selected.

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The probiotic consortium showed in vitro immuno and adipomodulatory properties.

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Lactobacillus delbrueckii subsp. indicus CRL1447 was selected as a starter culture for fermented milk elaboration.

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Manufacturing of a functional fermented goat milk with a new probiotic consortium.

The Detection of Potential Native Probiotics Lactobacillus spp. against Salmonella Enteritidis, Salmonella Infantis and Salmonella Kentucky ST198 of Lebanese Chicken Origin

Salmonella continues to be a major threat to public health, especially with respect to strains from a poultry origin. In recent years, an increasing trend of antimicrobial resistance (AMR) in Salmonella spp. was observed due to the misuse of antibiotics. Among the approaches advised for overcoming AMR, probiotics from the Lactobacillus genus have increasingly been considered for use as effective prophylactic and therapeutic agents belonging to the indigenous microbiota. In this study, we isolated lactobacilli from the ilea and ceca of hens and broilers in order to evaluate their potential probiotic properties. Four species were identified as Limosilactobacillusreuteri (n = 22, 45.8%), Ligilactobacillussalivarius (n = 20, 41.6%), Limosilactobacillus fermentum (n = 2, 4.2%) and Lactobacillus crispatus (n = 1, 2%), while three other isolates (n = 3, 6.25%) were non-typable. Eight isolates, including Ligilactobacillussalivarius (n = 4), Limosilactobacillusreuteri (n = 2), L. crispatus (n = 1) and Lactobacillus spp. (n = 1) were chosen on the basis of their cell surface hydrophobicity and auto/co-aggregation ability for further adhesion assays using the adenocarcinoma cell line Caco-2. The adhesion rate of these strains varied from 0.53 to 10.78%. Ligilactobacillussalivarius A30/i26 and 16/c6 and Limosilactobacillus reuteri 1/c24 showed the highest adhesion capacity, and were assessed for their ability to compete in and exclude the adhesion of Salmonella to the Caco-2 cells. Interestingly, Ligilactobacillussalivarius 16/c6 was shown to significantly exclude the adhesion of the three Salmonella serotypes, S. Enteritidis, S. Infantis and S. Kentucky ST 198, to Caco-2 cells. The results of the liquid co-culture assays revealed a complete inhibition of the growth of Salmonella after 24 h. Consequently, the indigenous Ligilactobacillussalivarius 16/c6 strain shows promising potential for use as a preventive probiotic added directly to the diet for the control of the colonization of Salmonella spp. in poultry.

Lactobacillus: Friend or Foe for Systemic Lupus Erythematosus?

The cause of Systemic Lupus Erythematosus (SLE) remains largely unknown, despite the fact that it is well understood that a complex interaction between genes and environment is required for disease development. Microbiota serve as activators and are essential to immune homeostasis. Lactobacillus is thought to be an environmental agent affecting the development of SLE. However, beneficial therapeutic and anti-inflammatory effects of Lactobacillus on SLE were also explored. The discovery of Lactobacillus involvement in SLE will shed light on how SLE develops, as well as finding microbiota-targeted biomarkers and novel therapies. In this review, we attempt to describe the two sides of Lactobacillus in the occurrence, development, treatment and prognosis of SLE. We also discuss the effect of different strains Lactobacillus on immune cells, murine lupus, and patients. Finally, we try to illustrate the potential immunological mechanisms of Lactobacillus on SLE and provide evidence for further microbiota-targeted therapies.

Biological Functions of Exopolysaccharides from Lactic Acid Bacteria and Their Potential Benefits for Humans and Farmed Animals

Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.

Strain-dependent effectivity, and protective role against enzymes of S-layers in Lactiplantibacillus plantarum strains

The present study investigated whether the surface layer (S-layer), which is known to have a varying effect from strain to strain on aggregation, adhesion ability, also has an effect on the resistance of bacteria to digestive enzymes, phenol, lysozymes. The effect of S-layers on the resistance against various enzymes, aggregation and adhesion abilities, and strain specificity were determined of eight Lactiplantibacillus plantarum strains. Strains were treated with 5 M lithium chloride (LiCl) to extract the S-layers, the presence of this layer in those microorganisms was demonstrated by polyacrylamide gel electrophoresis. Scanning electron microscopy was used to visualize the separation of the S-layer, which surrounds the microorganism, from the microorganism by the LiCl. The images were taken three times, once at the beginning, once 30 min later, and once at the end of this process, which took 2 h in total. The effect against enzymes varied depending on the strain, but it was determined that all the tested strains had a serious loss of viability against phenol in the absence of an S-layer. Lpb. plantarum DA100 showed a maximum decrease against gastrointestinal system enzymes after the LiCl (96.48 ± 0.03% before and 66.46 ± 0.01% after LiCl). Lpb. plantarum DA255 showed a significant decrease against lysozyme (99.11 ± 0.00% before and 62.80 ± 0.0% after LiCl). Removal of the S-layer greatly affected the adhesion ability of some strains, while for others there was hardly any change. The results showed that the role of the S-layer may be strain-specific, the rate of effect can vary. The primary function of S-layer proteins is thought to contribute to the adhesion ability of bacteria. There are limited studies that have reported the protective property of this layer against various enzymes, however, our results showed that S-layer could be one of the resistance strategies developed by bacteria against enzymes.

Exopolysaccharides synthesized by lactic acid bacteria: biosynthesis pathway, structure-function relationship, structural modification and applicability

Probiotics and their fermentation products are increasingly been focused on due to their health-boosting effects. Exopolysaccharides (EPS) synthetized by lactic acid bacteria (LAB) are widely applied as texture modifiers in dairy, meat and bakery products owning to their improved properties. Moreover, LAB-derived EPS have been confirmed to possess diverse physiological bioactivities including antioxidant, anti-biofilm, antiviral, immune-regulatory or antitumor. However, the low production and high acquisition cost hinder their development. Even though LAB-derived EPS have been extensively studied for their production-improving, there are only few reports on the systematic elucidation and summary of the relationship among biosynthesis pathway, strain selection, production parameter, structure-function relationship. Therefore, a detailed summary on biosynthesis pathway, production parameter and structure-function relationship of LAB-derived EPS is provided in this review, the structural modifications together with the current and potential applications are also discussed in this paper.

In vitro and genetic screening of probiotic properties of lactic acid bacteria isolated from naturally fermented cow-milk and yak-milk products of Sikkim, India

A total of 272 isolates of lactic acid bacteria (LAB) were isolated from 22 samples of naturally fermented milk products of Sikkim in India viz. dahi, soft-variety chhurpi, hard-variety chhurpi, mohi and philu, out of which, 68 LAB isolates were randomly grouped on the basis of phenotypic characteristics, and were identified by 16S rRNA gene sequence analysis. Leuconostoc mesenteroides was the most dominant genus, followed by Leuc. mesenteroides subsp. jonggajibkimchii, Lactococcus lactis subsp. cremoris, Lc. lactis, Lc. lactis subsp. hordniae, Lc. lactis subsp. tructae, Enterococcus faecalis, E. italicus and E. pseudoavium. LAB strains were tested for probiotics attributes by in vitro and genetic screening, based on marker genes. LAB strains showed tolerance to pH 3.0, bile salt, resistance to lysozyme and β-galactosidase activity. Enterococcus faecalis YS4-11 and YS4-14 and Lactococcus lactis subsp. cremoris SC3 showed more than 85% of hydrophobicity. Genes clp L and tdc encoding for low pH tolerance, agu A and Ir1516 encoding for bile tolerance, LBA1446 gene encoding for BSH activity, map A, apf, mub 1 and msa encoding for mucosal binding property were detected. Gene mesY for bacteriocin production was detected only in Leuconostoc spp. Based on the in vitro and genetic screening of probiotic attributes, Leuc. mesenteroides; Leuc. mesenteroides subsp. jonggajibkimchii and Lc. lactis subsp. cremoris were tentatively selected for possible probiotic candidates.

Characteristics of surface layer protein from Lactobacillus kefiri HBA20 and the role in mediating interactions with Saccharomyces cerevisiae Y8

In this study, the surface layer protein (SLP) from Lactobacillus kefiri HBA20 was characterized. The SLP was extracted by 5 M LiCl. The molecular mass of the SLP was approximately 64 kDa as analyzed via SDS-PAGE. The surface morphology and the adhesion potential of L. kefiri HBA20 in the absence and presence of SLP were measured by AFM. Moreover, the protein secondary structure was evaluated by using circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. SLP had high β-sheet contents and low content of α-helix. Thermal analysis of SLP of Lactobacillus kefiri HBA20 exhibited one transition peak at 129.64 °C. Furthermore, SEM measurements were showed that after the SLP were removed from the cell surface, the coaggregation ability with Saccharomyces cerevisiae Y8 of the strain was significantly reduced. In conclusion, the SLP of Lactobacillus kefiri HBA20 has a stable structure and the ability of adhesion to yeast. Molecular docking study revealed that mannan bind with the hydrophobic residues of SLP. Our results will help further understanding of the new surface layer protein and the interaction between L. kefiri and S. cerevisiae.

Isolation and Identification of Potential Probiotic Bacteria from Human Milk

Breast milk was long considered a sterile environment, but now it is known to harbor many bacteria that will shape the newborn microbiota. The benefits of breastfeeding to newborn health are, on some level, related to the presence of beneficial bacteria in human milk. Therefore, this study aims to investigate and isolate potential probiotics present in human milk that might be associated with improved health in infants, being potential candidates to be used in simulated human milk formula. Milk samples of 24 healthy mothers were collected at three time points: 30 min (colostrum), 5-9 days (transitional milk), and 25-30 days (mature milk) postpartum. Samples were evaluated by culturing, and the isolated bacteria were identified by MALDI-TOF MS and 16S DNA sequencing. In vitro screening for probiotics properties was performed, and the potential probiotics were mono-associated with germ-free mice to evaluate their ability to colonize the gastrointestinal tract. The microorganisms were submitted to the spray-drying process to check their viability for a potential simulated milk formula production. Seventy-seven bacteria were isolated from breast milk pertaining to four bacterial genera (Staphylococcus, Streptococcus, Leuconostoc, and Lacticaseibacillus). Four potential probiotics were selected: Lacticaseibacillus rhamnosus (n = 2) and Leuconostoc mesenteroides (n = 2). Isolates were able to colonize the gastrointestinal tract of germ-free mice and remained viable after the spray-drying process. In conclusion, breast milk harbors a unique microbiota with beneficial microorganisms that will impact the newborn gut colonization, being an essential source of probiotic candidates to be used in a formula of simulated maternal milk.

Exopolysaccharides Producing Lactic Acid Bacteria in Wine and Other Fermented Beverages: For Better or for Worse?

Lactic acid bacteria (LAB) from fermented beverages such as wine, cider and beer produce a wide range of exopolysaccharides (EPS) through multiple biosynthetic pathways. These extracellular polysaccharides constitute key elements for bacterial species adaptation to such anthropic processes. In the food industry, LAB polysaccharides have been widely studied for their rheological, functional and nutritional properties; however, these have been poorly studied in wine, beer and cider until recently. In this review, we have gathered the information available on these specific polysaccharide structure and, biosynthetic pathways, as well as the physiology of their production. The genes associated with EPS synthesis are also presented and compared. Finally, the possible role of EPS for bacterial survival and spread, as well as the risks or possible benefits for the winemaker and the wine lover, are discussed.

Phospholipids and Fatty Acids Affect the Colonization of Urological Catheters by Proteus mirabilis

Proteus mirabilis-mediated CAUTIs are usually initiated by the adherence of bacteria to a urinary catheter surface. In this paper, three isolates of different origin and exhibiting different adhesion abilities were investigated in search of any changes in lipidome components which might contribute to P. mirabilis adhesion to catheters. Using GC-MS and LC-MS/MS techniques, 21 fatty acids and 27 phospholipids were identified in the examined cells. The comparison of the profiles of phospholipids and fatty acids obtained for catheter-attached cells and planktonic cells of the pathogens indicated C11:0 and PE 37:2 levels as values which could be related to P. mirabilis adhesion to a catheter, as well as cis C16:1, PE 32:0, PE 33:0, PE 38:2, PG 33:1, PG 34:0, PE 30:1, PE 32:1 and PG 30:2 levels as values which could be associated with cell hydrophobicity. Based on DiBAC₄ (3) fluorescence intensity and an affinity to p-xylene, it was found that the inner membrane depolarization, as well as strong cell-surface hydrophobicity, were important for P. mirabilis adhesion to a silicone catheter. A generalized polarization of Laurdan showed lower values for P. mirabilis cells attached to the catheter surface than for planktonic cells, suggesting lower packing density of membrane components of the adherent cells compared with tightly packed, stiffened membranes of the planktonic cells. Taken together, these data indicate that high surface hydrophobicity, fluidization and depolarization of P. mirabilis cell membranes enable colonization of a silicone urinary catheter surface.

Surface Properties of Parabacteroides distasonis and Impacts of Stress-Induced Molecules on Its Surface Adhesion and Biofilm Formation Capacities

The gut microbiota is a complex and dynamic ecosystem whose balance and homeostasis are essential to the host's well-being and whose composition can be critically affected by various factors, including host stress. Parabacteroides distasonis causes well-known beneficial roles for its host, but is negatively impacted by stress. However, the mechanisms explaining its maintenance in the gut have not yet been explored, in particular its capacities to adhere onto (bio)surfaces, form biofilms and the way its physicochemical surface properties are affected by stressing conditions. In this paper, we reported adhesion and biofilm formation capacities of 14 unrelated strains of P. distasonis using a steam-based washing procedure, and the electrokinetic features of its surface. Results evidenced an important inter-strain variability for all experiments including the response to stress hormones. In fact, stress-induced molecules significantly impact P. distasonis adhesion and biofilm formation capacities in 35% and 23% of assays, respectively. This study not only provides basic data on the adhesion and biofilm formation capacities of P. distasonis to abiotic substrates but also paves the way for further research on how stress-molecules could be implicated in P. distasonis maintenance within the gut microbiota, which is a prerequisite for designing efficient solutions to optimize its survival within gut environment.

Lactiplantibacillus plantarum strains isolated from spontaneously fermented cocoa exhibit potential probiotic properties against Gardnerella vaginalis and Neisseria gonorrhoeae

Background

Probiotics are important tools in therapies against vaginal infections and can assist traditional antibiotic therapies in restoring healthy microbiota. Recent research has shown that microorganisms belonging to the genus Lactobacillus have probiotic potential. Thus, this study evaluated the potential in vitro probiotic properties of three strains of Lactiplantibacillus plantarum, isolated during the fermentation of high-quality cocoa, against Gardnerella vaginalis and Neisseria gonorrhoeae. Strains were evaluated for their physiological, safety, and antimicrobial characteristics.

Results

The hydrophobicity of L. plantarum strains varied from 26.67 to 91.67%, and their autoaggregation varied from 18.10 to 30.64%. The co-aggregation of L. plantarum strains with G. vaginalis ranged from 14.73 to 16.31%, and from 29.14 to 45.76% with N. gonorrhoeae. All L. plantarum strains could moderately or strongly produce biofilms. L. plantarum strains did not show haemolytic activity and were generally sensitive to the tested antimicrobials. All lactobacillus strains were tolerant to heat and pH resistance tests. All three strains of L. plantarum showed antimicrobial activity against the tested pathogens. The coincubation of L. plantarum strains with pathogens showed that the culture pH remained below 4.5 after 24 h. All cell-free culture supernatants (CFCS) demonstrated activity against the two pathogens tested, and all L. plantarum strains produced hydrogen peroxide. CFCS characterisation in conjunction with gas chromatography revealed that organic acids, especially lactic acid, were responsible for the antimicrobial activity against the pathogens evaluated.

Conclusion

The three strains of L. plantarum presented significant probiotic characteristics against the two pathogens of clinical importance. In vitro screening identified strong probiotic candidates for in vivo studies for the treatment of vaginal infections.

Effect of graded levels of dietary Bacillus toyonensis and Bifidobacterium bifidum supplementation on growth, carcass traits and ileal histomorphometry and microbiota of growing quails

This experiment investigated the role of graded dietary levels of two probiotic strains (Bacillus toyonensis; BT and Bifidobacterium bifidum; BB) on the growth rate, carcass traits, physiological and histological aspects of growing Japanese quail. One thousand and three hundred sixty one-day-old un-sexed Japanese quail chicks were distributed randomly into ten groups. The 1st group served as a control and fed the basal diet without supplement while the 2nd, 3rd, 4th and 5th groups received the control diet supplemented with 0.05, 0.075, 0.10 and 0.125% BT, respectively. The 6th group fed the control diet plus 0.10% BB while the remaining groups (7th to 10th) received the basal diet incorporated with the previous levels of BT rich with 0.05% BB. Dietary supplementation of BT and/or BB increased body weight and gain; however, feed intake and feed conversion were not affected. Amylase activity was significantly elevated in 5th, 7th and 9th groups, while lipase activity was improved in all treatment groups except 3rd and 6th groups. Results obtained concluded that dietary supplementation of BT with or without BB is useful for performance, digestive enzyme activities, blood cholesterols, antioxidant status and ileal histomorphometry and microbiota of growing Japanese quail.

In vitro growth performance, antioxidant activity and cell surface physiological characteristics of Pediococcus pentosaceus R1 and Lactobacillus fermentum R6 stressed at different NaCl concentrations

This study investigated the impact of NaCl concentrations on the growth performance, antioxidant activity, and cell surface physiological characteristics of Pediococcus pentosaceus R1 and Lactobacillus fermentum R6. The growth of the two strains was significantly inhibited by 4 and 6% NaCl and stagnated at 8% NaCl (P < 0.05). Compared with the control, both strains showed higher acid-producing activity, antioxidant activity and autoaggregation ability at 2 or 4% NaCl. A lower cell surface hydrophobicity of the two strains was observed with increased NaCl concentrations. High NaCl concentrations resulted in cell surface damage and deformation and even slowed the proliferation of the strains, and led to significant shifts in amide A and amide III groups in proteins and the C-H stretching of >CH2 in fatty acids (P < 0.05). In summary, appropriate NaCl concentrations (2 and 4%) improved the antioxidant activity of the two strains, while the higher NaCl concentrations (6%) decreased their antioxidant activity, which may be due to the associated changes in the cell surface structural properties of the two strains.

Probiotic properties of lactic acid bacteria isolated from traditionally prepared dry starters of the Eastern Himalayas

The Himalayan people prepare dry and oval to round-shaped starter cultures to ferment cereals into mild-alcoholic beverages, which contain lactic acid bacteria (LAB) as one of the essential microbiota. There is no report on probiotic characters of LAB isolated from dry starters. Hence, we screened the probiotic and some functional properties of 37 LAB strains isolated from dry starters of the Eastern Himalayas viz. marcha, phab, paa, pee and phut. About 38% of the LAB strains showed high survival rate (> 50%) at pH 3 and 0.3% bile salts. Enterococcus durans BPB21 and SMB7 showed the highest hydrophobicity percentage of 98%. E. durans DMB4 and SMB7 showed maximum cholesterol assimilation activity. About 65% of the LAB strains showed the ability to produce β galactosidase. Majority of the strains showed phytase activity, whereas none of the strain showed amylase activity. About 86% of LAB strains showed an optimum tolerance of 10% ethanol concentration. Genetic screening of some probiotic and functional marker genes have also been analysed. The occurrence of clp L gene, agu A gene (survival of gastrointestinal tract conditions), apf, mub1 and map A gene (adhesion genes) was higher compared to other genes. The occurrence of bsh gene (bile salt tolerance) was detected in Pediococcus pentosaceus SMB13-1 and Enterococcus faecium BPB11. Gene ped B for pediocin with amplicon size of 375 bp was detected in E. durans DMB13 and Pediococcus acidilactici AKB3. Detection of nutritional marker gene rib A and fol P in some strains showed the potential ability to synthesize riboflavin and folic acid. LAB with probiotic and functional properties may be explored for food industry in future.

Glyceraldehyde-3-Phosphate Dehydrogenase Increases the Adhesion of Lactobacillus reuteri to Host Mucin to Enhance Probiotic Effects

The ability to adhere to the intestinal mucus layer is an important property of probiotic bacteria. Lactobacillus reuteri strains ZJ615 and ZJ617 show low and high adhesion, respectively, to intestinal epithelial cells. In this study, we quantified bacterial cell wall-associated glyceraldehyde-3-phosphate dehydrogenases (cw-GAPDH) and bacterial cell membrane permeability in both strains using immunoblotting and flow cytometry, respectively. Highly adhesive L. reuteri ZJ617 possessed significantly more cw-GAPDH, higher cell membrane permeability, and significantly higher adhesive ability toward mucin compared with low-adhesive L. reuteri ZJ615. In vitro adhesion studies and analysis of interaction kinetics using the Octet, the system revealed significantly decreased interaction between L. reuteri and mucin when mucin was oxidized when bacterial surface proteins were removed when bacteria were heat-inactivated at 80 °C for 30 min, and when the interaction was blocked with an anti-GAPDH antibody. SWISS-MODEL analysis suggested intensive interactions between mucin glycans (GalNAcα1-O-Ser, GalNAcαSer, and Galβ3GalNAc) and GAPDH. Furthermore, in vivo studies revealed significantly higher numbers of bacteria adhering to the jejunum, ileum, and colon of piglets orally inoculated with L. reuteri ZJ617 compared with those inoculated with L. reuteri ZJ615; this led to a significantly decreased rate of diarrhea in piglets inoculated with L. reuteri ZJ617. In conclusion, there are strong correlations among the abundance of cw-GAPDH in L. reuteri, the ability of the bacterium to adhere to the host, and the health benefits of this probiotic.

Growth of Lactic Acid Bacteria on Gold-Influence of Surface Roughness and Chemical Composition

The main focus of this work was to establish a correlation between surface topography and chemistry and surface colonization by lactic acid bacteria. For this reason, we chose gold substrates with different surface architectures (i.e., smooth and nanorough) that were characterized by atomic force microscopy (AFM), electron scanning microscopy (SEM), and X-ray diffractometry (XRD). Moreover, to enhance biocompatibility, we modified gold substrates with polymeric monolayers, namely cationic dextran derivatives with different molar masses. The presence of those layers was confirmed by AFM, infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). In order to determine the adhesion abilities of non-modified and modified gold surfaces, we tested three lactic acid bacteria (LAB) strains (i.e., Lactobacillus rhamnosus GG, Lactobacillus acidophilus, and Lactobacillus plantarum 299v). We have shown that surface roughness influences the surface colonization of bacteria, and the most significant impact on the growth was observed for the Lactobacillus rhamnosus GG strain. What is more, covering the gold surface with a molecular polymeric film by using the layer-by-layer (LbL) method allows additional changes in the bacterial growth, independently on the used strain. The well-being of the bacteria cells on tested surfaces was confirmed by using selective staining and fluorescence microscopy. Finally, we have determined the bacterial metabolic activity by measuring the amount of produced lactic acid regarding the growth conditions. The obtained results proved that the adhesion of bacteria to the metallic surface depends on the chemistry and topography of the surface, as well as the specific bacteria strain.

Saccharomyces cerevisiae and Lactobacillus rhamnosus cell walls immobilized on nano-silica entrapped in alginate as aflatoxin M1 binders

Aflatoxins are common fungal toxins in foods that cause health problems for humans. The aim of this study was to use Saccharomyces cerevisiae and Lactobacillus rhamnosus cell walls immobilized on nano-silica entrapped in alginate as aflatoxin M₁ (AFM₁) binders. In this study, microbial walls were disrupted using a three-step mechanical technique including autoclave, thermal shock, and ultrasound. Dynamic light scattering (DLS) results proved size reduction in microbial walls ranging 75.8-91.4 nm. Disrupted walls were immobilized on nano-silica to enhance the efficiency of AFM₁ adsorption. Then, to prevent the release of the nano-silica or cell walls into the reaction medium, they were entrapped into alginate gel beads. Fourier transform infrared spectrometer (FT-IR) and scanning electron microscopy (SEM) micrographs confirmed the immobilization and entrapment process. Individual and mixtures of free cell walls, immobilized-entrapped walls, alginate bead and nano-silica were contacted with AFM₁ for 15 min and 24 h. AFM₁ reduction ability was evaluated using high performance liquid chromatography (HPLC). The results showed an AFM₁ reduction ranging 53-87% for free cell walls mixture at 15 min and alginate bead respectively. Also, it was possible to reuse immobilized-entrapped walls as binders with an efficiency of about 85%.

Anti-inflammatory effects of Lactobacillus reuteri LM1071 via MAP kinase pathway in IL-1β-induced HT-29 cells

Lactic acid bacteria are well-known probiotics, conferring several health benefits. In this study, we isolated lactobacilli from human breast milk and identified Lactobacillus reuteri LM1071 (RR-LM1071) using 16S rDNA sequencing. We tested the hemolytic activity, biogenic amine production, and antibiotic susceptibility of this strain to assess its safety. RR-LM1071 was found to be negative for hemolytic activity and biogenic amine production, as well as was measured in susceptible level for antibiotics in the minimal inhibitory concentration (MIC) test. The adhesive properties of RR-LM1071 were higher than those of LGG in HT-29 cells, and showed a greater hydrophobicity than LGG in hexadecane solvent. Under inflammatory conditions, RR-LM1071 suppressed the mRNA expression of IL-6, TNF-α, and IL-4 produced in IL-1β-induced HT-29 cells. Our results suggest that RR-LM1071 is a safe and valuable probiotic that can be used for the treatment of inflammatory bowel disease.

Exopolysaccharide production by lactic acid bacteria: the manipulation of environmental stresses for industrial applications

Exopolysaccharides (EPSs) are biological polymers secreted by microorganisms including Lactic acid bacteria (LAB) to cope with harsh environmental conditions. EPSs are one of the main components involved in the formation of extracellular biofilm matrix to protect microorganisms from adverse factors such as temperature, pH, antibiotics, host immune defenses, etc.. In this review, we discuss EPS biosynthesis; the role of EPSs in LAB stress tolerance; the impact of environmental stresses on EPS production and on the expression of genes involved in EPS synthesis. The evaluation results indicated that environmental stresses can alter EPS biosynthesis in LAB. For further studies, environmental stresses may be used to generate a new EPS type with high biological activity for industrial applications.

Probiotic characteristics of Lactobacillus strains isolated from cheese and their antibacterial properties against gastrointestinal tract pathogens

In the present study, four Lactobacillus strains from the cheese were analyzed for its probiotic potential against enteropathogenic bacteria. The probiotic properties of the selected strains were also analyzed and the selected bacterial strains showed high tolerance in bile salts and organic acid. The strain L. plantarum LP049 showed maximum survival rate (92 ± 4.2% and 93.3 ± 2%) after 3 h of treatment at 0.25% (w/v) bile salts and 0.25% (w/v) organic acid concentrations. The ability of the Lactobacillus strains to adhere to human epithelial cells (HT-29 cell lines) was evaluated and L. plantarum LP049 showed maximum adhesion property (19.2 ± 1.1%) than other tested strains. The Lactobacillus strains produced lactic acid at various concentrations. Compared with other strains, maximum level of lactic acid (3.1 g/L), hydrogen peroxide (4.31 mM) and bacteriocin (31 AU/mg) was detected in LB049. The inhibitory activity of culture supernatant against various bacterial pathogens was observed. The zone of inhibition ranged between 6 ± 2 mm and 23 ± 2 mm. The cell free extract showed activity against, Escherichia coli (ATCC 10536), Salmonella enteritidis (ATCC 13076), Shigella flexneri (ATCC 29903), and Enterococcus faecium (ATCC 8459). Consequently, L. plantarum LP049 may be considered as a potential candidate for the production of novel bioactive metabolites for therapeutic and bio-protective applications.

Anti-adipogenic effect of Lactobacillus fermentum MG4231 and MG4244 through AMPK pathway in 3T3-L1 preadipocytes

This study evaluated the anti-adipogenic effects and mechanisms underlying the action of Lactobacillus fermentum MG4231 and MG4244 strains on adipogenesis and lipid accumulation in 3T3-L1 preadipocytes. Treatment with cell-free extracts (CFEs) from the two strains reduced lipid accumulation and intracellular triglyceride production in 3T3-L1 adipocytes by more than 50%. The inhibitory effects of L. fermentum on lipid accumulation were mediated by the downregulation of FAS and aP2 resulting from the inhibition of PPARγ and C/EBPα gene expression. Moreover, AMPK and HSL phosphorylation was upregulated by CFE treatment. These results indicated that the anti-adipogenic and lipolysis activities of L. fermentum strains were caused by increased AMPK and HSL phosphorylation. Both strains displayed high leucine arylamidase and β-galactosidase enzymatic activity, with excellent adhesion to epithelial cells. Therefore, we identified L. fermentum as potential new probiotics for the prevention of obesity.

In vitro studies of adhesion properties of six lactic acid bacteria isolated from the longevous population of China

Six lactic acid bacteria (LAB), isolated from the intestinal tract of the longevous population, were prominent for their strong bacteriostatic ability. In this study, the adhesion properties of the six strains were determined in vitro to explore their potential to be used as probiotics. The hydrophobicity and aggregation activity were firstly detected and were varied from 14.83% to 57.3% and 12.7% to 31%, respectively. Moreover, the adhesion activity to the intestinal crypt cells (IEC-6 cells) was proved to be varied from 5.4 to 21.7 bacteria numbers per cell. Furthermore, all the tested LAB samples could inhibit 3 Gram-positive and 3 Gram-negative indicator microorganisms to adhere to the IEC-6 cells. Meanwhile every sample was inclined to exclude rather than displace or compete to inhibit the indicator microorganisms to adhere to IEC-6 cells. Afterwards, the adhesion activities of the LAB were demonstrated to be highly affected by the surface proteins considering the treatments of heat, pepsin, trypsin and NaIO₄. The surface proteins (8–14 kDa) of every sample were isolated and proved to be helpful to regain more than 30% of the adhesion activity for the corresponding samples. This study will be beneficial to examine the characteristics of these strains especially L. casei g9 when used as probiotics in dairy food products.

Adhesion related activities of six lactic acid bacteria were detected. This study will be beneficial to examine the characteristics of these strains used as probiotics in dairy products.

Evaluation of the Inhibitory Effects of Lactobacillus gasseri and Lactobacillus crispatus on the Adhesion of Seven Common Lower Genital Tract Infection-Causing Pathogens to Vaginal Epithelial Cells

Background/Purpose: Lactobacillus colonization is important to maintain urogenital flora stability and prevent pathogenic infection. Different Lactobacillus species have distinct properties and effects on the urogenital flora. To select probiotics that colonize the vagina and provide protection against pathogenic infection, we evaluated the adhesion of five Lactobacillus strains and their inhibitory effects on the adhesion of pathogens to vaginal epithelial cells (VECs). Methods and Materials: (1) Lactobacillus adhesion experiments: VK2/E6E7 and primary VECs were used to evaluate the adhesion of two Lactobacillus gasseri and three Lactobacillus crispatus strains. The adhesion of these five Lactobacillus strains was compared. (2) Adhesion inhibition experiments: The inhibitory effects of the five Lactobacillus strains on the adhesion of pathogens (Gardnerella, Mobiluncus, Candida albicans, Streptococcus agalactiae, Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis) were evaluated by adhesion exclusion, displacement, and competition experiments. Results: (1) Lactobacillus adhesion was stronger in the primary VECs than in the VK2/E6E7 VECs (P < 0.05). The adhesion of the three L. crispatus strains was stronger than that of the two L. gasseri strains (P < 0.05). L. crispatus 4# showed the strongest adhesion. (2) The exclusion, displacement, and competition experiments showed that all five Lactobacillus strains significantly inhibited the adhesion of the seven pathogenic strains to the VECs (P < 0.05). The displacement effect was stronger than the exclusion and competition effects of each Lactobacillus strain. (3) The results of the exclusion, displacement, and competition experiments indicated that L. gasseri 1# showed the strongest adhesion inhibition of C. albicans and S. agalactiae. L. crispatus 3# showed the strongest adhesion inhibition of S. aureus, whereas L. crispatus 4# showed the strongest adhesion inhibition of Gardnerella, Mobiluncus, E. coli, and E. faecalis. Conclusion: The source of the VECs might not affect the selection of the most adhesive Lactobacillus strain. L. crispatus showed stronger VEC adhesion than L. gasseri. The degree of antagonism of the Lactobacillus strains toward the different pathogens varied. This result provides incentives for personalized clinical treatment.

The importance of the S-layer on the adhesion and aggregation ability of Lactic acid bacteria

S-layer proteins in Lactic acid bacteria are not the only cell surface structures used for aggregation, but also plays significant role for intestinal tissue adhesion along with some other functional elements. In addition, it was determined that the properties of S-layer proteins differs not only between species but also the strains which belong to same species. In this work, presence and some functions of S-layer in lactic acid bacteria were determined, its effect on resistance to gastrointestinal enzymes, aggregation and adhesion ability were investigated as well. For this purpose S-layers of microorganisms were removed by 5 M LiCl treatment and size of the proteins were determined by SDS-PAGE analysis. The removal of S-layer proteins caused a change in the resistance of microorganisms to GIS enzymes. After the S-layer removal, two strains considerably lost their resistance to GIS enzymes. The strains mostly lost their aggregation ability in the absence of S-layer. The results showed that S-layer proteins are not the only structures involved in aggregation processes but, is a major mediator in Lactobacilli. Removal of S-layer had no effect on adhesion ability of W. cibaria DA28, the effect on L. casei DA4, L. coryniformis DA263 and L. plantarum DA140 was moderate, but the effect was high on L. plantarum DA100. The study showed that S-layer proteins play limited protection against GIS enzymes. In addition, absence of S-layer adversely affected aggregation and adhesion ability of strains.

Characterization and evaluation of lactic acid bacteria from indigenous raw milk for potential probiotic properties

Raw milk contains wide microbial diversity, composed mainly of lactic acid bacteria (LAB), which are used as probiotics in both human and animal husbandry. We isolated, characterized, and evaluated LAB from indigenous Bangladeshi raw milk to assess probiotic potential, including antagonistic activity (against Escherichia coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, Salmonella Enteritidis, and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto- and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. The 4 most promising LAB strains showed probiotic potential and were identified as Lactobacillus casei, Lactobacillus plantarum (which produced plantaricin EF), Lactobacillus fermentum, and Lactobacillus paracasei. These strains inhibited all pathogens tested at various degrees, and competitively excluded pathogens with viable counts of 3.0 to 6.0 log cfu/mL. Bacteriocin, organic acids, and low-molecular-weight substances were mainly responsible for antimicrobial activity by the LAB strains. All 4 LAB strains were resistant to oxacillin and 3 were resistant to vancomycin and streptomycin, with multiple antibiotic resistance indices >0.2. After further in vivo evaluation, these LAB strains could be considered probiotic candidates with application in the food industry.

Isolation, characterization, and assessment of lactic acid bacteria toward their selection as poultry probiotics

BACKGROUND

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are now accepted as suitable alternatives to antibiotics in the control of animal infections and improving animal production. Lactic acid bacteria (LAB) with remarkable functional properties have been evaluated in different studies as possible probiotic candidates. The purpose of this study was to isolate, characterize and assess the potentials of LAB from poultry gastrointestinal tract as potential poultry probiotics.

RESULTS

Potential LAB probiotics were isolated from broilers, characterized and evaluated for probiotic properties including antagonistic activity (against Escherichia coli, E. coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, S. Enteritidis and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. Most promising LAB strains with excellent probiotic potentials were identified by API 50 CHL and 16S rRNA sequencing as Lactobacillus reuteri I2, Pediococcus acidilactici I5, P. acidilactici I8, P. acidilactici c3, P. pentosaceus I13, and Enterococcus faecium c14. They inhibited all the pathogens tested with zones of inhibition ranging from 12.5 ± 0.71 to 20 ± 0 mm, and competitively excluded (P < 0.05) the pathogens examined while adhering to ileum epithelial cells with viable counts of 3.0 to 6.0 Log CFU/ml. The selected LAB strains also showed significant (P < 0.005) auto and co-aggregation abilities with α-glucosidase inhibitory activity ranging from 12.5 to 92.0%. The antibiotic susceptibility test showed 100.00% resistance of the LAB strains to oxacillin, with multiple antibiotic resistance indices above 0.5.

CONCLUSION

The selected LAB strains are ideal probiotic candidates which can be applied in the field for the improvement of poultry performance and control of pathogens in poultry, hence curtailing further transmission to humans.

Partial rpoB Gene Sequencing Identification and Probiotic Potential of Floricoccus penangensis ML061-4 Isolated from Assam Tea (Camellia sinensis var. assamica)

Assam tea or Miang is a local name of Camellia sinensis var. assamica in northern Thailand. By the local wisdom, Assam tea leaves are used as the raw material in tea fermentation to produce “Fermented Miang” consumed by people in northern Thailand and the countries nearby. In this study, twenty-eight bacterial isolates were obtained from Assam tea leaf samples collected from Nan province, Thailand. Bacterial isolates were identified within 6 genera including Bacillus, Floricoccus, Kocuria, Lysinibacillus, Micrococcus and Staphylococcus. Among these, the strain ML061-4 shared 100.0 and 99.4% similarity of 16S rRNA and rpoB gene sequence with F. penangensis JCM 31735^T, respectively. This is the first discovery of F. penangensis in Thailand. F. penangensis ML061-4 exhibited probiotic characteristics including lactic acid production (9.19 ± 0.10 mg/ml), antibacterial activities (Escherichia coli ATCC 25922 and E. coli O157:H7 DMST 12743), acid and bile salt tolerance (71.1 and 54.9%, respectively), autoaggregation (97.0%), coaggregation (66.0% with E. coli O157:H7), cell surface hydrophobicity (90.0%), bacterial adhesion (82.9% with Lactobacillus plantarum FM03-1), competitive inhibition (17.8% with E. coli O157:H7) and competitive exclusion (34.9% with E. coli O157:H7). Overall, the data suggested that F. penangensis ML061-4 had a great potential to be a probiotic.

Production of Dextran from Locally Lactobacillus Spp. Isolates

BACKGROUND

Dextran is a commercially available bacterial exopolysaccharide (EPS) with several industrial applications in the food industry and in the biomedical industry as an adjuvant, emulsifier, carrier, and stabilizer. The production of dextran at the industrial level occurs through the fermentation of a sucrose-rich medium. Research to optimize dextran production has found that the yield of dextran varies depending the specific conditions for production. The aim of this study was to produce dextran and establish the optimal conditions for dextran biosynthesis from different Lactobacillus species isolated from healthy vaginal and infant stool samples.

METHODS

Lactobacillus spp. were isolated and identified from vaginal and infant stool samples via the VITEK 2 system. The presence of dextran biosynthesis from the different Lactobacillus spp. isolates was determined by a screening test for mucoid colonies and confirmed via the ethanol precipitation method. To optimize for the maximum yield of dextran, the effects of various parameters such as temperature, incubation time, pH, inoculum size, aeration, and sucrose concentration were examined.

RESULTS

All Lactobacillus spp. isolates were able to produce dextran. The optimal conditions for dextran production was at 24 hours of incubation at 30 °C with 15% sucrose, 4% inoculation size at pH 7.0 in aerobic conditions. This yielded a dextran dry weight of 580 mg/100 mL.

CONCLUSION

Dextran production from Lactobacillus species isolates vagina and infant stool had the ability to produce dextran.

Skin-associated lactic acid bacteria from North American bullfrogs as potential control agents of Batrachochytrium dendrobatidis

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis and has been a key driver in the catastrophic decline of amphibians globally. While many strategies have been proposed to mitigate Bd outbreaks, few have been successful. In recent years, the use of probiotic formulations that protect an amphibian host by killing or inhibiting Bd have shown promise as an effective chytridiomycosis control strategy. The North American bullfrog (Lithobates catesbeianus) is a common carrier of Bd and harbours a diverse skin microbiota that includes lactic acid bacteria (LAB), a microbial group containing species classified as safe and conferring host benefits. We investigated beneficial/probiotic properties: anti-Bd activity, and adhesion and colonisation characteristics (hydrophobicity, biofilm formation and exopolysaccharide-EPS production) in two confirmed LAB (cLAB-Enterococcus gallinarum CRL 1826, Lactococcus garvieae CRL 1828) and 60 presumptive LAB (pLAB) [together named as LABs] isolated from bullfrog skin.We challenged LABs against eight genetically diverse Bd isolates and found that 32% of the LABs inhibited at least one Bd isolate with varying rates of inhibition. Thus, we established a score of sensitivity from highest (BdGPL AVS7) to lowest (BdGPL C2A) for the studied Bd isolates. We further reveal key factors underlying host adhesion and colonisation of LABs. Specifically, 90.3% of LABs exhibited hydrophilic properties that may promote adhesion to the cutaneous mucus, with the remaining isolates (9.7%) being hydrophobic in nature with a surface polarity compatible with colonisation of acidic, basic or both substrate types. We also found that 59.7% of LABs showed EPS synthesis and 66.1% produced biofilm at different levels: 21% weak, 29% moderate, and 16.1% strong. Together all these properties enhance colonisation of the host surface (mucus or epithelial cells) and may confer protective benefits against Bd through competitive exclusion. Correspondence analysis indicated that biofilm synthesis was LABs specific with high aggregating bacteria correlating with strong biofilm producers, and EPS producers being correlated to negative biofilm producing LABs. We performed Random Amplified Polymorphic DNA (RAPD)-PCR analysis and demonstrated a higher degree of genetic diversity among rod-shaped pLAB than cocci. Based on the LAB genetic analysis and specific probiotic selection criteria that involve beneficial properties, we sequenced 16 pLAB which were identified as Pediococcus pentosaceus, Enterococcus thailandicus, Lactobacillus pentosus/L. plantarum, L. brevis, and L. curvatus. Compatibility assays performed with cLAB and the 16 species described above indicate that all tested LAB can be included in a mixed probiotic formula. Based on our analyses, we suggest that E. gallinarum CRL 1826, L. garvieae CRL 1828, and P. pentosaceus 15 and 18B represent optimal probiotic candidates for Bd control and mitigation.

Putative Adhesion Factors in Vaginal Lactobacillus gasseri DSM 14869: Functional Characterization

Lactobacilli play an important role in the maintenance of a healthy vaginal microbiota, and some select species are widely used as probiotics. Vaginal isolates of Lactobacillus gasseri DSM 14869 and Lactobacillus rhamnosus DSM 14870 were previously selected to develop the probiotic EcoVag capsules and showed therapeutic effects in women with bacterial vaginosis (BV). However, the molecular mechanisms involved in their probiotic activity are largely unknown. In this study, we identified three cell surface molecules in L. gasseri DSM 14869 that promote adhesion to vaginal epithelial cells (VEC) by constructing dedicated knockout mutants, including exopolysaccharides (EPSs), a protein containing MucBP-like domains (N506_1778), and a putative novel adhesin (N506_1709) with rib/alpha-like domain repeats. EPS knockout mutants revealed 20-fold and 14-fold increases in adhesion to Caco-2 and HeLa cells, respectively, compared with wild type, while the adhesion to VEC was reduced 30% by the mutation, suggesting that EPSs might mediate tissue tropism for vaginal cells. A significant decrease in adhesion to Caco-2 cells, HeLa cells, and VEC was observed in the N506_1778 knockout mutant. The N506_1709 mutant showed no significant difference for the adhesion to Caco-2 and HeLa cells compared with wild type (WT); in contrast, the adhesion to VEC revealed a significant decrease (42%), suggesting that N506_1709 might mediate specific binding to stratified squamous epithelial cells, and this putative novel adhesin was annotated as Lactobacillus vaginal epithelium adhesin (LVEA). Thus, we have discovered an important role for EPSs and a novel adhesin, LVEA, in the adhesive capacity of a vaginal probiotic Lactobacillus strain.IMPORTANCE Lactobacilli are known to contribute to the maintenance of a healthy vaginal microbiota and some are selected as probiotics for the prevention or treatment of urogenital diseases, such as bacterial vaginosis. However, the molecular mechanisms for these health-promoting effects are not fully understood. Here, we functionally identified three cell surface factors of a Lactobacillus gasseri strain potentially involved in its adhesion to vaginal epithelial cells, including exopolysaccharides (EPSs) and two sortase-dependent proteins (N506_1778 and N506_1709). We could demonstrate the tissue-specific adhesion of EPSs to vaginal cells and that N506_1709 might be a novel adhesin specifically mediating bacterial binding to stratified squamous epithelial cells. The results provide important new information on the molecular mechanisms of vaginal Lactobacillus spp. adhesion.

Probiotic properties and immunomodulatory activity of gastrointestinal tract commensal bacterial strains isolated from the edible farmed snail Cornu aspersum maxima

The aim of this study was to determine the in vitro probiotic properties as well as the immunomodulatory activity of bacterial strains isolated from the gastrointestinal tract of the edible-farmed land snail Cornu aspersum maxima. Forty lactic acid bacterial strains (named Sgs1-40) were isolated from the intestinal tract and eight strains (named SgmA-H) from the oesophagus-crop of snails. Several criteria were used to examine whether they may be applied as snail-specific for the screening of the presumptive probiotic bacterial strains. Principal Component Analysis using criteria such as the tolerance of these strains to the pedal mucus, gastric mucus, gastric juices and low pH, as well as the expression of the cell surface traits of hydrophobicity, biofilm formation and autoaggregation capacity revealed discrimination of twelve strains exhibiting presumptive in vitro probiotic properties. Injection of eight of these strains, which were identified as Lactobacillus plantarum, in snail haemocoel increased the recruitment and phagocytic activity of amoebocytes in snail haemolymph. The Sgs14 and SgmB strains, exhibiting the highest immunostimulatory activity in haemolymph, were FITC-labelled and orally administrated to snails for ten days. The Sgs14 strain was able to adhere to intestinal mucosa of snails and stimulate the chemotactic and phagocytic activity of amoebocytes in haemolymph as well as the bactericidal activity of haemolymph serum. These responses are potentially mediated by the regulation of TLRs expression in the gut mucosa. These data indicate that the determination of properties such as snail mucus and gastric juice tolerance, cell surface traits for adhesion as well as increased chemotactic and phagocytic activity in snail haemolymph are eligible criteria to screen for snail-specific probiotics. To the best of our knowledge, this is the first work that investigates the probiotic properties of gastrointestinal microflora of the terrestrial farmed snail Cornu aspersum maxima.

Functional Characterization of Probiotic Potential of Novel Pigmented Bacterial Strains for Aquaculture Applications

The bioprospecting proficient of novel pigmented probiotic strains with respect to aquaculture industry was unexplored hitherto. In this study, we investigated the probiotic potential of novel pigmented bacterial strains isolated from the indigenous soil sediments in their vicinal habitats, which were screened for their antimicrobial activity against aquatic pathogens using agar well diffusion assay. The strains namely Exiguobacterium acetylicum (S01), Aeromonas veronii (V03), and Chryseobacterium joostei (V04) were phenotypically identified and confirmed by 16S rRNA gene sequence analysis. Further characterization revealed that strains S01 and V03 survive relatively in lower pH and higher bile salt concentrations and possess good adherence ability and broad-spectrum antibiotic susceptibility. The isolate S01 exhibited the higher adhesion ability to hydrocarbons (82%) and mannose-specific adhesion (msa) gene expression. Additionally, the probiotic effects were evaluated in Artemia nauplii fed with algae supplemented with S01, V03, and V04 strains (2.7 × 10⁷ cfu/mL) for 3 days under axenic environment. We observed a significant increase (p < 0.05) in the survival rate of Artemia nauplii treated with S01 (83 ± 5%) and V03 (55 ± 5%), whereas the survival rate was only 30 ± 0% in the untreated group. Moreover, the individual length (IL) was increased in treated group S01 (156.7 ± 2.2 μm), V03 (146.1 ± 3.4 μm), and V04 (134.4 ± 2.5 μm) compared with untreated group (116.0 ± 4.8 μm). Our results revealed that E. acetylicum S01 exhibits desirable functional probiotic attributes compared to A. veronii and C. joostei and it would be a promising probiotic strain, which can be efficiently used in the aquaculture applications.