In this report, we present a draft sequence of the genome of Lactobacillus rhamnosus strain 2166, a potential novel probiotic. Genome annotation and read mapping onto a reference genome of L. rhamnosus strain GG allowed for the identification of the differences and similarities in the genomic contents and gene arrangements of these strains.

Lactobacillus rhamnosus LOCK908, a patented probiotic strain (Polish patent no. 209987), was isolated from the feces of a healthy 6-year-old girl. Here, we present the complete genome sequence of LOCK908 and identify genes likely to be involved in the biosynthesis of exopolysaccharides (EPSs).

Consumers are demanding healthier foods, and the increasing drawbacks associated with dairy-based products have driven efforts to find plant-based probiotic alternatives. Consequently, this study aimed to evaluate the suitability of a teff-based substrate for delivering the potential probiotics, Lactobacillus rhamnosus GG (LGG) and Lactobacillus plantarum A6 (LA6) with a view to developing probiotic functional beverages. Single-strain and mixed-strain fermentations were performed without any pH control. In single-strain fermentation, LA6 grew to 8.157-8.349 log cfu/mL. Titratable acidity (TA) and pH were measured between 0.513-1.360 g/L and 4.25-3.91, respectively. The explored optimum variables were fermentation time (15 h) and inoculum (6 log cfu/mL). As a result of fermentation, maltose and glucose decreased, but lactic and acetic acids increased. In mixed-strain fermentation, LGG and LA6 were able to grow to 8.247 and 8.416 log cfu/mL, respectively. The pH, TA, lactic, and acetic acids varied between 6.31-3.92, 0.329-1.501 g/L, 0-1672 mg/L, and 20-231.5 mg/L, respectively. In both fermentations, microbial growth reached the stationary phase close to a pH of 4.21-4.82 while sugars were not consumed completely. Less than 5% ethanol was detected, which indicated a non-alcoholic beverage. A combination of the two evaluated lactobacilli strains reduced fermentation time. In conclusion, a substrate made of whole grain teff flour without any supplement could be used as a substrate to produce functional probiotic beverages.

In colorectal cancer, approximately 95% of patients are refractory to immunotherapy because of low antitumor immune responses. Therefore, there is an exigent need to develop treatments that increase antitumor immune responses and decrease tumor burden to enhance immunotherapy.

Bacterial vaginosis (BV) and its recurrence are most commonly associated with the formation of Gardnerella species biofilm. Probiotics are typically used to treat BV; however, the optimal period of Lactobacillus probiotic application in BV treatment remains uncertain. The present study aimed to explore the effects of Lactobacillus rhamnosus and Lactobacillus casei on various stages of biofilm formation in Gardnerella species. The biofilm-forming ability of seven strains, including one Gardnerella vaginalis ATCC 14018 and six clinically isolated Gardnerella species, was determined via gentian violet staining assay. Moreover, the sensitivity of the planktonic and biofilm forms toward metronidazole and clindamycin was assessed via microdilution broth method. L. rhamnosus Xbb-LR-1 and L. casei Xbb-LC-1 were added during various stages of biofilm formation in Gardnerella species and were cocultured for 24 h. The biofilm thickness of each sample was determined via confocal laser scanning microscopy (CLSM). The absolute quantities of Gardnerella species in each sample was obtained via real time polymerase chain reaction method, and the pH value was obtained using a pH indicator paper. Biofilm formation by Gardnerella species in a medium with distinct pH values was observed via gentian violet staining, CLSM, and scanning electron microscopy (SEM). The biofilm increased the resistance of Gardnerella species toward metronidazole and clindamycin. L. rhamnosus added at the initial biofilm formation stage in Gardnerella species exhibited highest inhibitory effect, with a percentage inhibition of 38.17% ± 1.35%. When the pH value of the culture medium was <4.5 or >6.5, ATCC 14018 could hardly form a biofilm; however, at pH ≥4.5 and ≤6.5, it was able to form a stronger biofilm. The amount of biofilm attained maximum value at optical density of 3.29 ± 0.28 (595 nm), pH 5.5, and at 36 h. Biofilm formation increases the resistance of Gardnerella species toward antibiotics. Maintaining an acidic vaginal environment with pH <4.5 and a vaginal microbiota dominated by Lactobacillus remarkably prevents the formation of Gardnerella species biofilm at the initial stage, which further has a significant impact on the treatment and prevention of biofilm-related infections.

Lactobacillus rhamnosus CNCM I-3698 is a commercially available probiotic that is used in animal feed as an additive. Here, we announce the draft genome sequence for this strain, consisting of 71 contigs corresponding to 2,966,480 bp and a G+C content of 46.69%.

An increasing body of evidence suggests that the use of probiotic bacteria is a promising intervention approach for the treatment of inflammatory diseases with a polymicrobial etiology. P. gingivalis has been noted to have a different way of interacting with the innate immune response of the host compared to other pathogenic bacteria, which is a recognized feature that inhibits CXCL8 expression.

Lactobacillus strains dominate the vaginal habitat and they are associated with a lower risk of genital infections. In addition, they contribute to the conservation of the vaginal microbiota by producing postbiotic agents. Previous studies have shown that their predominance involves antimicrobial activity against urogenital pathologies. In this context, probiotics may improve treatment outcomes. The aim of this study was to evaluate the probiotic properties of lactobacilli strains of vaginal origin using a multidisciplinary approach. For this purpose, safety criteria, ability to resist at low pH and bile salts, antimicrobial activity, ability to produce biofilm, capacity to produce hydrogen peroxide and more importantly, auto-aggregation, co-aggregation (with Candida spp.) and adhesion to human cells were evaluated. The strains belonged to the species of L. crispatus, L. gasseri, L. rhamnosus and L. delbruckii. Among these, a strain of L. rhamnosus named AD3 showed the best probiotic properties. As probiotics are already in use in many clinical practice and there are no major safety concerns, L. rhamnosus AD3 showed promise in becoming a prevention and complementary treatment option for urogenital diseases. Indeed, these results suggest that strain L. rhamnosus AD3 is non-pathogenic and likely to be safe for human consumption. This study revealed the great amensalistic properties of a new L. rhamnosus strain which can aim to be used as probiotic in pharmaceutical applications.

Probiotic bacteria belonging to Lactobacillus spp. are important producers of bioactive molecules, known as postbiotics, that play essential roles in the immunological support of the intestinal mucosa. In this study, the system of co-culture of intestinal epithelial cells with macrophage cells in vitro was used to study the potential effect of postbiotic fractions of L. rhamonosus and L. plantarum on the modulation of the immune response induced by pro-inflammatory stimuli. This study's results revealed that the presence of probiotic bacterial components on the mucosal surface in the early and late stage of inflammatory conditions is based on cellular interactions that control inflammation and consequent damage to the intestinal epithelium. In our studies, heat killed fractions of probiotic bacteria and their extracted proteins showed a beneficial effect on controlling inflammation, regardless of the strain tested, consequently protecting intestinal barrier damage. In conclusion, the presented results emphasize that the fractions of probiotic bacteria of L. plantarum and L. rhamnosus may play a significant role in the regulation of LPS-mediated cytotoxic activity in intestinal epithelial cells. The fractions of probiotic strains of L. rhamnosus and L. plantarum showed the potential to suppress inflammation, effectively activating the anti-inflammatory cytokine IL-10 and modulating the IL-18-related response.

Different soybean products are considered as traditional functional food among the Mongolian population in Northeast India. In the present study, the effect of different flavours (mango, orange, vanilla and white rose), inoculation rates of Lactobacillus rhamnosus K4E (KX950834) and Lactobacillus helveticus K14 (KU644578), and mass fractions of skimmed milk and sugar on the acceptability of soy yoghurts was studied. Physicochemical (pH, titratable acidity) and microbial analyses (total bacterial, total coliform, yeast and mould count) were conducted, and organoleptic (aroma, taste, colour, mouthfeel, texture and overall acceptability) and biofunctional properties (angiotensin-converting enzyme (ACE) inhibitory activity, antioxidant and antimicrobial activities and biotransformation of isoflavones) were evaluated during storage up to 10 days under refrigeration conditions (6-8 °C). Panellists preferred white rose soy yoghurt more than other flavours. The pH was from 5.65 to 4.20, the titratable acidity (expressed as mass fraction of lactic acid) was from 0.33 to 0.51% and total Lactobacillus count ranged from 6.81 to 8.69 log CFU/mL during storage. The ACE inhibitory activity increased from 21.17% on day 0 to 81.03% on day 5, followed by a decrease of the activity after 10 days (38.85%). The antioxidant activity was the highest on day 5 (87%). White rose soy yoghurt had the highest antimicrobial activity against Listeria monocytogenes, followed by Bacillus subtilis, Staphylococcus aureus, Salmonella typhi and Escherichia coli. RP-HPLC analysis showed that after 18 h, the production of soy isoflavone aglycones genistein and daidzein in yoghurt was 87.3 and 58.4%, respectively.

Probiotics and probiotic-related nutritional interventions have been described to have beneficial effects on immune homeostasis and gut health. In previous studies, Lactobacillus rhamnosus GG (LGG) soluble mediators (LSM) have been demonstrated to exert beneficial effects in preclinical models of allergic sensitization, bacterial infection, and intestinal barrier function. In the context of allergic diseases, differentiation of dendritic cells (DCs) and their interactions with T cell populations are crucial for driving tolerogenic responses. In this study, we set out to evaluate whether these LSM can modulate DC maturation and have an impact on prompting protective and/or tolerogenic T cell responses. Monocytes were isolated from PBMC of healthy blood donors and cultured in the presence of GM-CSF, IL-4, and LSM or unconditioned bacterial culture medium control (UCM) during 6 days to induce DC differentiation. Subsequently, these DCs were matured in the presence of TNF-α for 1 day and analyzed for their phenotype and ability to induce autologous T cell activation and differentiation to model recall antigens. After 7 days of co-culture, T cells were analyzed for activation and differentiation by flow cytometry of intracellular cytokines (IFN-γ, IL-2, IL-10, and IL-17A), activation markers (CD25), and Foxp3+ expression. LSM did not alter DC numbers or maturation status. However, these DCs did show improved capacity to induce a T cell response as shown by increased IL-2 and IFN-γ producing T cell populations upon stimulation with recall antigens. These enhanced recall responses coincided with enhanced Foxp3+ expression that was not observed when T cells were cultured in the presence of UCM-treated DCs. By contrast, the number of activated T cells (determined by CD25 expression) was only slightly increased. In conclusion, this study reveals that LSM can influence adaptive immune responses as shown by the modulation of DC functionality. These mechanisms might contribute to previous observed effects in animal models in vivo. Altogether, these results suggest that LSM may provide an alternative to live probiotics in case life bacteria may not be used because of health conditions, although further clinical testing is needed.

The gut microflora is an important constituent in the intestinal mucosal barrier and has been introduced as the concept of probiotic therapy that beneficially affects the host by improving its intestinal microbial balance. Therefore, the main objective of the study was to explore the protective potential of various lactobacilli strains for murine giardiasis. By experimentation, it was found that the probiotic supplementation of either Lactobacillus casei, L. acidophilus, L. plantarum, or L. rhamnosus GG, 7 days prior to inoculation with G. lamblia trophozoites, reduced the rate of cyst excretion compared with Giardia-infected mice. Interestingly, L. GG was found to be the most effective probiotic in reducing the duration of giardia cycle and acts as an effective prophylactic probiotic for murine giardiasis but needs to be clinically correlated due to entirely different human microflora.

Probiotics promote and help to maintain beneficial microbiota composition of the gastrointestinal tract ecosystem and have a positive impact on the host's health. Production of exopolysaccharides is an important feature of probiotic lactobacilli. It increases the chance of their survival in the gastrointestinal tract and promotes adhesion to the epithelium; therefore, exopolysaccharides are important for the process of colonization. Two lactic acid bacteria strains were used in this study: Lactobacillus rhamnosus KL 53A and Lactobacillus casei Fyos. Exopolysaccharides were isolated from bacterial cells and their monosaccharide composition was examined using liquid chromatography. The influence of exopolysaccharides on lactobacilli adhesion to enterocytes was studied after deglycosylation of the bacterial cells and incubation with the selected intestinal microbiota strains that metabolize polysaccharides - Faecalibacterium prausnitzii DSM 17677 and Blautia luti DSM 14534. Both deglycosylation and incubation with polysaccharide metabolizing strains influenced the ability of probiotic strains to adhere to enterocytes. Enzymatic deglycosylation decreased adhesion efficiency of L. rhamnosus KL 53A; however, co-incubation of both lactobacillus strains with F. prausnitzii DSM 17677 resulted in an increase of their adhesion efficiency. Exopolysaccharides are important adhesins of Lactobacillus spp. that influence their ability to colonize gut epithelium. Other members of gut microbiota can modify the adhesion property in situ ; therefore the composition and metabolic state of commensal bacteria may influence their probiotic action.

Lactobacillus rhamnosus is a non-starter lactic acid bacterium that plays a significant role during cheese ripening, leading to the formation of flavor. In long-ripened cheeses it persists throughout the whole time of ripening due to its capacity to adapt to changing environmental conditions. The versatile adaptability of L. rhamnosus to different ecosystems has been associated with the capacity to use non-conventional energy sources, regulating different metabolic pathways. However, the molecular mechanisms allowing the growth of L. rhamnosus in the cheese dairy environment are still poorly understood. The aim of the present study was to identify genes potentially contributing to the growth ability of L. rhamnosus PR1019 in cheese-like medium (CB) using a transcriptomic approach, based on cDNA-amplified fragment length polymorphism (cDNA-AFLP) and quantitative real-time reverse transcription-PCR (qPCR).

The preservation of the viability of microorganisms in probiotic formulations is the most important parameter ensuring the adequate concentration of live microorganisms at the time of administration. The formulation and processing techniques used to produce these probiotic formulations can influence the preservation of the microbial viability. However, it is also required that the bacteria maintain their key probiotic capacities during processing, formulation and shelf life. In this study, we investigated the impact of spray-drying on different cell wall properties of the model probiotic strain Lactobacillus rhamnosus GG, including its adherence to intestinal epithelial cells. The dltD gene knock-out mutant, L. rhamnosus GG CMPG5540, displaying modified cell wall lipoteichoic acids, showed significantly increased colony-forming units after spray-drying and subsequent storage under standard conditions compared to wild-type L. rhamnosus GG. In contrast, disruption of the biosynthesis of exopolysaccharides or pili expression did not impact survival. However, spray-drying did significantly affect the adherence capacity of L. rhamnosus GG. Scanning electron microscopy confirmed that the pili, key surface factors for adherence to intestinal cells and mucus, were sheared off during the spray-drying process. These data thus highlight that both the functionality and viability of probiotics should be assessed during the spray-drying process and subsequent storage.

Pathogen-induced infectious diseases pose great threats to public health. Accordingly, many studies have investigated effective strategies targeting pathogenic infections. We previously reported the preventive effects of Lactobacillus plantarum ZS2058 (ZS2058) and L. rhamnosus GG (LGG) against Salmonella spp. in a murine model. Here, we compared the mechanisms underlying the preventive effects of these Lactobacillus strains in vivo. Notably, reduced C-reactive protein levels were observed with both ZS2058 and LGG, which suggests abrogated anti-infection and inflammatory responses. ZS2058 more efficiently reduced the pathogenicity of Salmonella by increasing the level of propionic acid in feces and production of mucin 2 in the mouse colon and activity through the interleukin (IL)-23/IL-22 and IL-23/IL-17 pathways. Meanwhile, LGG more strongly alleviated gut inflammation, as indicated by changes in the levels of tissue necrosis factor (TNF)-α, IL-10 and myeloperoxidase (MPO) in infected mice. Moreover, both ZS2058 and LGG restored the levels of interferon (INF)-γ, a cytokine suppressed by Salmonella, albeit through different pathways. Our results demonstrate that ZS2058 and LGG prevent Salmonella infection via different mechanisms.

Intestinal epithelial cells (IECs) provide the frontline responses to the gut microbiota for maintaining intestinal homeostasis. Our previous work revealed that IEC-derived components promote the beneficial effects of a commensal and probiotic bacterium, Lactobacillus rhamnosus GG (LGG). This study aimed to elucidate the regulatory effects of IEC-derived components on LGG at the molecular level.

A total of 22 Lactobacillus strains, which were isolated from infant feces were evaluated for their probiotic potential along with resistance to low pH and bile salts. Eight isolates (L. reuteri 3M02 and 3M03, L. gasseri 4M13, 4R22, 5R01, 5R02, and 5R13, and L. rhamnosus 4B15) with high tolerance to acid and bile salts, and ability to adhere to the intestine were screened from 22 strains. Further, functional properties of 8 Lactobacillus strains, such as anti-oxidation, inhibition of α-glucosidase activity, cholesterol-lowering, and anti-inflammation were evaluated. The properties were strain-specific. Particularly, two strains of L. rhamnosus, 4B15 (4B15) and L. gasseri 4M13 (4M13) showed considerably higher anti-oxidation, inhibition of α-glucosidase activity, and cholesterol-lowering, and greater inhibition of nitric oxide production than other strains. Moreover, the two selected strains substantially inhibited the release of inflammatory mediators such as TNF-α, IL-6, IL-1β, and IL-10 stimulated the treatment of RAW 264.7 macrophages with LPS. In addition, whole genome sequencing and comparative genomic analysis of 4B15 and 4M13 indicated them as novel genomic strains. These results suggested that 4B15 and 4M13 showed the highest probiotic potential and have an impact on immune health by modulating pro-inflammatory cytokines.

Cysteine, a critical residue for catalytic process but also vulnerable to oxidative damage, was conventionally expressed as a buried catalytic site in most redox enzymes. In the present work, specific surface-exposed sites of a NADH oxidase from Lactobacillus rhamnosus (LrNox) were selected and mutated to cysteine to investigate its effects on catalytic function because LrNox has a buried catalytic cysteine but no surface-exposed one. The results showed that exception of the sites on dimer interface, the activities of LrNox mutants were improved to vary degrees when the polar uncharged and alanine residues were mutated to cysteine. But the cysteine mutations of polar charged and nonpolar residues except alanine showed obvious decline in catalytic activity. Substituting of Ala85 and Thr96 with other residues suggested that the cysteine mutation showed the highest activity. Structural analysis suggested that even a single cysteine mutation on the specific non-conserved surface area of LrNox could induce changes on the conformation of catalytic cysteine and lower the activation free energy to improve the catalytic activity.

Lactobacillus rhamnosus GG (LGG) is the most widely used probiotic, but the mechanisms underlying its beneficial effects remain unresolved. Previous studies typically inoculated LGG in hosts with established gut microbiota, limiting the understanding of specific impacts of LGG on host due to numerous interactions among LGG, commensal microbes, and the host. There has been a scarcity of studies that used gnotobiotic animals to elucidate LGG-host interaction, in particular for gaining specific insights about how it modifies the metabolome. To evaluate whether LGG affects the metabolite output of pathobionts, we inoculated with LGG gnotobiotic mice containing Propionibacterium acnes, Turicibacter sanguinis, and Staphylococcus aureus (PTS).