Probiotic potential of Lactobacilli with antagonistic activity against pathogenic strains: An in vitro validation for the production of inhibitory substances.
Ontology highlight
ABSTRACT: Probiotics, live cells with different beneficiary characteristics, have been extensively studied and explored commercially in many different products in the world. Their benefits to human and animal health have proven in hundreds of scientific studies. Based on rich bibliographic material, Curd is the potential source of probiotic Lactobacilli.The aim of the present study was to observe Lactobacilli with probiotic potential activities from different curd samples for isolation, identification and characterization of Lactobacillus species.Among the samples, thirty lactic acid bacterial strains were isolated, sixteen (16/30) best Lactobacillus isolates were selected by preliminary screening as potential probiotic for acid and bile tolerance, further confirmed using 16s rRNA identification. All the selected Lactobacillus isolates were then characterized in vitro for their probiotic characteristics and antimicrobial activities against pathogens and aggregation studies. The results indicated that selected potential probiotic isolates (T2, T4 and T16) were screened and confirmed as Lactobacillus. The isolates produced positive tolerance to excited pH, NaCl and bile salts, also revealed noticeable antimicrobial activities against pathogens. All the Lactobacillus isolates were susceptible to clinical antibiotics used. Besides, T2 isolate was constituted to retain stronger auto and co-aggregation and cell surface hydrophobicity capacity.Based on the drawn results, T2, T4 and T16 Lactobacillus isolates were recognised as ideal, potential in vitro antimicrobial probiotic isolates against pathogens and studies are needed further in-vivo assessment and human health benefits in their real-life situations.
Probiotic potential of Lactobacilli with antagonistic activity against pathogenic strains: An in vitro validation for the production of inhibitory substances.
<h4>Background</h4>Probiotics, live cells with different beneficiary characteristics, have been extensively studied and explored commercially in many different products in the world. Their benefits to human and animal health have proven in hundreds of scientific studies. Based on rich bibliographic material, Curd is the potential source of probiotic Lactobacilli.<h4>Method</h4>The aim of the present study was to observe Lactobacilli with probiotic potential activities from different curd samples ...[more]
Project description:Enterococcus cecorum is a commensal bacteria and opportunistic pathogen that can cause outbreaks of Enterococcal spondylitis ("kinky back") in poultry, with a growing concern worldwide. Numerous Bacillus-based probiotic strains are commercially available with proven effects in supporting gut health and growth performance, but efficacy against pathogenic E. cecorum is unknown. This study compared the in vitro inhibitory potential of cell-free supernatants (CFSs) of 18 Bacillus strains (14 commercial probiotic strains, 1 internal negative control and 3 type strains) on the growth of 9 clinical E. cecorum isolates. Standardized biomass cultures of live Bacillus were harvested and filtered to obtain CFSs. Inhibitory potential against E. cecorum isolates was assessed via a microdilution assay in which the final pathogen concentration was ? 104 CFU/mL. Absorbance (OD) was measured every 15 min for 15 h and used to calculate percentage growth inhibition at an OD equivalent to 0.4 in the positive control (PC) (pathogen but no CFS), and growth delay vs. PC. Growth kinetic responses of pathogen isolate-Bacillus strain combinations ranged from total pathogen inhibition to partial inhibition, lag in growth, no effect, or increased growth vs. PC. Percentage inhibition of individual isolates varied markedly among Bacillus strains, from 100% to -100% (growth promotion as recorded for the type strain) (B. amyloliquefaciens DSM7T). Five B. amyloliquefaciens CFSs produced higher average inhibition rates (>75%) than 2 out of 3 Bacillus licheniformis CFSs (-2.5, and -8.39% vs. PC, respectively) and 1 out of 2 Bacillus subtilis CFSs (7.3% vs. PC) (P < 0.05). Commercial strain 3AP4 exhibited the highest average percentage inhibition vs. PC (85.0% ± 7.9) and the most consistent inhibitory effect across pathogen isolates. The findings indicate that some commercially available poultry probiotic Bacillus strains are effective at inhibiting pathogenic E. cecorum in vitro, but effects are highly strain and pathogen isolate-dependent. Further work is required to confirm effects in vivo and isolate the inhibitory substances.
Project description:A molecular method for efficient and accurate detection and identification of two potential probiotic lactobacilli strains isolated from fermented olives, namely Lactobacillus pentosus B281 and Lb. plantarum B282, was developed in the present study. Random Amplified Polymorphic DNA (RAPD) analysis was performed, and strain specific primers were designed and applied in a multiplex polymerase chain reaction (PCR) assay. The specificity of the assay was tested and successfully confirmed in 27 and 22 lactobacilli strains for Lb. pentosus B281 and Lb. plantarum B282, respectively. Moreover, the two strains were used as starter cultures in yogurt production. Cell enumeration followed by multiplex PCR analysis demonstrated that the two strains were present in yogurt samples at levels ?6 log CFU/g even after 35 days of storage at 4 °C. Microbiological analysis showed that lactobacilli and streptococci were present within usual levels, whereas enterobacteriaceae and yeast/mold counts were not detected as expected. Although the pH values of the novel products were slightly lower than the control ones, the yogurt containing the probiotic cultures scored similar values compared to the control in a series of sensory tests. Overall, these results demonstrated the possible use of the two strains as starter adjuncts in the production of yogurt with potential probiotic properties.
Project description:IntroductionHuman health is deemed to be maintained by the crosstalk among the body and probiotic bacteria. Disruptions in this composition are associated with the pathogenesis of numerous diseases. Through modernization, traditional foods consumption has been abandoned and native food starters have been substituted with industrial products. Hence, we aimed to isolate and evaluate probiotic bacteria from traditional fermented foods which can be used as probiotics as well as starter cultures in food industry and in medicine against antibiotic resistant pathogenes. To this end, an intact village was recognized in the Republic of Azerbaijan with traditional dairy products, yielding a variety of potential probiotics.MethodsIn this study, tvorog as a traditional dairy product from Dashkasan, Ismailli and khachmaz regions in Azerbaijan was characterized for the isolation of Lactobacilli with probiotic potentiality. The bacteria were tested for the resistance to the acid, bile, and the antagonistic effect of human pathogenic bacteria. The isolates were identified by 16s rDNA sequencing with a blast to the databank.ResultsThree species with higher homology to the L. planetarium, L. rhamnosus, and L. casei with high probiotic potentiality and antibacterial effects were isolated.ConclusionHomemade tvorog curd cheese in Azerbaijan harbor a variety of probiotics with industrial applications as well as potentiality to be preserved in a biobank for the future medicinal applications especially against antibiotic resistant pathogenes.
Project description:The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits.
Project description:In animal nutrition, probiotics are considered as desirable alternatives to antibiotic growth promoters. The beneficial effects of probiotics primarily depend on their viability in feed, which demands technical optimization of biomass production, since processing and storage capacities are often strain-specific. In this study, we optimized the production parameters for two broiler-derived probiotic lactobacilli (L. salivarius and L. agilis). Carbohydrate utilization of both strains was determined and preferred substrates that boosted biomass production in lab-scale fermentations were selected. The strains showed good aerobic tolerance, which resulted in easier scale-up production. For the freeze-drying process, the response surface methodology was applied to optimize the composition of cryoprotective media. A quadratic polynomial model was built to study three protective factors (skim milk, sucrose, and trehalose) and to predict the optimal working conditions for maximum viability. The optimal combination of protectants was 0.14g/mL skim milk/ 0.08 g/mL sucrose/ 0.09 g/mL trehalose (L. salivarius) and 0.15g/mL skim milk/ 0.08 g/mL sucrose/ 0.07 g/mL (L. agilis), respectively. Furthermore, the in-feed stabilities of the probiotic strains were evaluated under different conditions. Our results indicate that the chosen protectants exerted an extensive protection on strains during the storage. Although only storage of the strains at 4 °C retained the maximum stability of both Lactobacillus strains, the employed protectant matrix showed promising results at room temperature.
Project description:The vaginal microbiota of healthy women is dominated by lactobacilli, which exerts important health-promoting effects to the host. In the present study, 261 lactobacilli isolated from vagina of healthy women were screened for their potential probiotic characteristics. Safety features (haemolytic activity, antibiotic susceptibility, bile salt hydrolase activity) and functional properties (resistance to low pH and bile salts, lysozyme tolerance, gastrointestinal survival, antagonistic activity against pathogens, hydrophobicity, auto-aggregation, and co-aggregation abilities, hydrogen peroxide production, biofilm formation, exopolysaccharide production, adhesion capacity to both normal human vagina epithelial cells and Caco-2 epithelial cells, and lactic acid production) were in depth evaluated. Seven strains, identified as Lactobacillus rhamnosus, Lactobacillus helveticus and Lactobacillus salivarius fulfilled the criteria described above. Therefore, the vaginal ecosystem represents a suitable source of probiotic candidates that could be used in new functional formulates for both gastrointestinal and vaginal eubiosis.
Project description:Probiotic Lactobacillus can be used to reduce the colonization of pathogenic bacteria in food animals, and therefore reduce the risk of foodborne illness to consumers. As a model system, we examined the mechanism of protection conferred by Lactobacillus species to inhibit C. jejuni growth in vitro and reduce colonization in broiler chickens. Possible mechanisms for the reduction of pathogens by lactobacilli include: 1) stimulation of adaptive immunity; 2) alteration of the cecal microbiome; and, 3) production of inhibitory metabolites, such as organic acids. The Lactobacillus species produced lactic acid at concentrations sufficient to kill C. jejuni in vitro. We determined that lactic acid produced by Lactobacillus disrupted the membrane of C. jejuni, as judged by biophotonics. The spectral features obtained using Fourier-transform infrared (FT-IR) and Raman spectroscopy techniques were used to accurately predict bacterial viability and differentiate C. jejuni samples according to lactic acid treatment. FT-IR spectral features of C. jejuni and Lactobacillus grown in co-culture revealed that the metabolism was dominated by Lactobacillus prior to the killing of C. jejuni. Based on our results, the development of future competitive exclusion strategies should include the evaluation of organic acid production.
Project description:Table olives are increasingly recognized as a vehicle as well as a source of probiotic bacteria, especially those fermented with traditional procedures based on the activity of indigenous microbial consortia, originating from local environments. In the present study, we report characterization at the species level of 49 Lactic Acid Bacteria (LAB) strains deriving from Nocellara del Belice table olives fermented with the Spanish or Castelvetrano methods, recently isolated in our previous work. Ribosomal 16S DNA analysis allowed identification of 4 Enterococcus gallinarum, 3 E. casseliflavus, 14 Leuconostoc mesenteroides, 19 Lactobacillus pentosus, 7 L. coryniformis, and 2 L. oligofermentans. The L. pentosus and L. coryniformis strains were subjected to further screening to evaluate their probiotic potential, using a combination of in vitro and in vivo approaches. The majority of them showed high survival rates under in vitro simulated gastro-intestinal conditions, and positive antimicrobial activity against Salmonella enterica serovar Typhimurium, Listeria monocytogenes and enterotoxigenic Escherichia coli (ETEC) pathogens. Evaluation of antibiotic resistance to ampicillin, tetracycline, chloramphenicol, or erythromycin was also performed for all selected strains. Three L. coryniformis strains were selected as very good performers in the initial in vitro testing screens, they were antibiotic susceptible, as well as capable of inhibiting pathogen growth in vitro. Parallel screening employing the simplified model organism Caenorhabditis elegans, fed the Lactobacillus strains as a food source, revealed that one L. pentosus and one L. coryniformis strains significantly induced prolongevity effects and protection from pathogen-mediated infection. Moreover, both strains displayed adhesion to human intestinal epithelial Caco-2 cells and were able to outcompete foodborne pathogens for cell adhesion. Overall, these results are suggestive of beneficial features for novel LAB strains, which renders them promising candidates as starters for the manufacturing of fermented table olives with probiotic added value.
Project description:We report on the isolation and characterization of an acid- and bile-tolerant bacterial strain, Bacillus sp. YB1701 with antibacterial and quorum-quenching activity. Strain YB1701 was isolated from coastal sediment samples and characterized by biochemical tests and 16S rRNA sequencing. In vitro study indicated that strain YB1701 can survive at pH 2.0 for up to 3 h and tolerate bile up to 2.0% concentration even after 12 h of exposure. Strain YB1701 showed antimicrobial activity against fish pathogens Aeromonas hydrophila and Vibrio parahemolyticus using an agar well diffusion assay. The trial test showed dietary supplementation of YB1701 significantly improved the resistance of Carassius auratus gibelio against A. hydrophila challenge. The safety assessment revealed that the isolate Bacillus sp. YB1701 was not cytotoxic to Carassius auratus gibelio or mice and did not exhibit hemolytic activity on rabbit blood agar plate. Disc-diffusion assays using a panel of antibiotics listed by the European Food Safety Authority (EFSA) showed that YB1701 was susceptible to selected antibiotics. Under laboratory conditions, the degradation rate of organic waste (predominately fish excrement) for 14 days by YB1701 was 79.69%. Results from the present study suggest that strain YB1701 is a potential probiotic strain and can be used in aquaculture for degrading organic waste and improving disease resistance of fish against bacterial infection. Further study is needed to assess the utility of strain YB1701 on a commercial scale.
Project description:The prebiotic activity of a commercially available oat product and a novel oat ingredient, at similar β-glucan loads, was tested using a validated in vitro gut model (M-SHIME®). The novel oat ingredient was tested further at lower β-glucan loads in vitro, while the commercially available oat product was assessed in a randomised, single-blind, placebo-controlled, and cross-over human study. Both approaches focused on healthy individuals with mild hypercholesterolemia. In vitro analysis revealed that both oat products strongly stimulated Lactobacillaceae and Bifidobacteriaceae in the intestinal lumen and the simulated mucus layer, and corresponded with enhanced levels of acetate and lactate with cross-feeding interactions leading to an associated increase in propionate and butyrate production. The in vitro prebiotic activity of the novel oat ingredient remained at lower β-glucan levels, indicating the prebiotic potential of the novel oat product. Finally, the stimulation of Lactobacillus spp. was confirmed during the in vivo trial, where lactobacilli abundance significantly increased in the overall population at the end of the intervention period with the commercially available oat product relative to the control product, indicating the power of in vitro gut models in predicting in vivo response of the microbial community to dietary modulation.