Oral Administration of Heat-Killed Lactobacillus plantarum Strain b240 Protected Mice against Salmonella enterica Serovar Typhimurium

Concomitant Therapy of Inactivated Enterococcus faecalis CECT7121 with Fluoroquinolones in a Salmonella Enteritidis Murine Sepsis Model

Optimization of existing antimicrobial therapies is a strategy proposed for extending antimicrobial activity and delaying resistance development. This study aimed to assess the effect of inactivated E. faecalis CECT7121 (I-EFCECT7121) in a combined therapy with Enrofloxacin or Ciprofloxacin in a S. Enteritidis murine sepsis model. Firstly, dose titration studies were performed to set up: (a) Salmonella Enteritidis (SE) Lethal dose 99 (LD99) and (b) safety of I-EFCECT7121 (c) I-EFCECT7121 dosage scheme. Then, I-EFCECT7121 in combined therapy with 4 doses (5 mg/kg) per 12 h of CFX and EFX in an LD99 BALB/c infection, were evaluated. Survival rate was monitored for 20 days in order to estimate the treatment success. The efficacy of both drugs was improved by combining them with the inactivated bacteria. However, only a significant increase (p < 0.05) was observed after I-EFCECT7121 and CFX combined treatment (40% of survival rate). By contrast, each drug alone achieved a 10% of survival rate. These outcomes showed a potential therapeutic synergism when I-EFCECT7121 was concomitantly given with ciprofloxacin.

Heat-Killed Lactobacillus acidophilus Promotes Growth by Modulating the Gut Microbiota Composition and Fecal Metabolites of Piglets

Probiotics can improve animal growth performance and intestinal health. However, understanding the effects of paraprobiotics on the growth performance and gut microbiota of piglets and how the paraprobiotics exert their impact are still limited. The present study was conducted to investigate the effects of heat-killed Lactobacillus acidophilus IFFI 6005 supplementation on the growth performance, intestinal microbiota, and fecal metabolites of piglets. First, a feed-additive sample of heat-killed Lactobacillus acidophilus IFFI 6005 was prepared by culture. Second, 96 (initial BW = 14.38 ± 0.67 kg, weaning age of 40 days) healthy piglets were selected and randomized into four treatment groups. Each treatment group consisted of three replicates (n = 8). Pigs were fed a basal diet (NC), basal diet plus antibiotics (PC), basal diet plus Lactobacillus acidophilus IFFI 6005 at 600 g/t (LA, 1.0 × 1010 cfu/g), and basal diet plus heat-killed Lactobacillus acidophilus IFFI 6005 at 600 g/t (HKLA), respectively; the trial lasted for 30 days. The results showed that the ratios of feed to gain (F:G) and diarrhea rate of both the HKLA and PC groups were significantly lower compared with the NC and LA groups (p < 0.05); however, there was no significant difference between the HKLA and PC group (p > 0.05). In addition, the average daily weight gain (ADG) of the HKLA group was significantly higher (p < 0.05) than that of the other three groups in terms of growth performance. Finally, 16S rRNA sequencing and metabolome analysis based on fecal samples further elaborated that the addition of heat-killed Lactobacillus acidophilus IFFI 6005 to the feed improved the intestinal microbial diversity and abundance (p < 0.05) and reduced the abundance of pathogenic bacteria (p < 0.05), but it did not affect the abundance of Lactobacillus (p > 0.05). Through the comparison of microbial abundance and metabolite content between the two groups (NC_vs_HKLA), the largest differences were found in six microorganisms and 10 metabolites in the intestine (p < 0.05). These differential metabolites were involved in the digestion, absorption and utilization of protein and starch, as well as in oxidative stress. In summary, addition of heat-killed Lactobacillus acidophilus IFFI 6005 as a new feed additive in piglets has beneficial effects on the growth performance, intestinal bacteria and metabolites, and can be used as an alternative to antibiotics.

Immunomodulatory activity of heat-killed Lacticaseibacillus paracaseiMCC1849 based on the activation of plasmacytoid dendritic cells in the peripheral blood of healthy adults

Probiotics are widely used in food for their health benefits to the host. Inactivated probiotics also reportedly improve the intestinal environment and immune regulation. Our previous studies showed that heat-killed Lacticaseibacillus paracasei MCC1849 (hk-MCC1849) effectively induced IL-12 production in mouse spleen cells and significantly reduced cold symptoms in clinical trial subjects. To further elucidate the mechanism of host immune regulation by hk-MCC1849, human peripheral blood mononuclear cells (PBMCs) were cocultured with hk-MCC1849. The Toll-like receptor 9 ligands CpG-ODN 2216 and hk-MCC1849 and the heat-killed Lacticaseibacillus rhamnosus ATCC53103 were used as positive and negative controls, respectively. The results showed that, compared with the control, hk-MCC1849 significantly increased the expression of the plasmacytoid dendritic cell (pDC) marker CD86 (p < .0001) and the pDC marker HLA-DR (p < .001) in PBMCs. The expression levels of the IL-12p40, IFNα, IFNα1, IFNγ, and ISG15 genes were significantly increased after coculture with hk-MCC1849 (p < .05, p < .05, p < .05, p < .05, and p < .05, respectively, vs. control). Furthermore, to confirm whether hk-MCC1849 directly interacted with pDCs, DCs were enriched with PBMCs following 24 h of coculture with hk-MCC1849. Phagocytosis of fluorescently labeled hk-MCC1849 by pDCs was observed, and there were significant increases in CD86 (p < .05) and HLA-DR (p < .0001) expression in pDCs. These results suggest that hk-MCC1849 exerts a potential immunomodulatory effect on the host through the activation of peripheral pDCs.

Elimination of Pathogen Biofilms via Postbiotics from Lactic Acid Bacteria: A Promising Method in Food and Biomedicine

Pathogenic biofilms provide a naturally favorable barrier for microbial growth and are closely related to the virulence of pathogens. Postbiotics from lactic acid bacteria (LAB) are secondary metabolites and cellular components obtained by inactivation of fermentation broth; they have a certain inhibitory effect on all stages of pathogen biofilms. Postbiotics from LAB have drawn attention because of their high stability, safety dose parameters, and long storage period, which give them a broad application prospect in the fields of food and medicine. The mechanisms of eliminating pathogen biofilms via postbiotics from LAB mainly affect the surface adhesion, self-aggregation, virulence, and QS of pathogens influencing interspecific and intraspecific communication. However, there are some factors (preparation process and lack of target) which can limit the antibiofilm impact of postbiotics. Therefore, by using a delivery carrier and optimizing process parameters, the effect of interfering factors can be eliminated. This review summarizes the concept and characteristics of postbiotics from LAB, focusing on their preparation technology and antibiofilm effect, and the applications and limitations of postbiotics in food processing and clinical treatment are also discussed.

Horizon scanning the application of probiotics for wildlife

The provision of probiotics benefits the health of a wide range of organisms, from humans to animals and plants. Probiotics can enhance stress resilience of endangered organisms, many of which are critically threatened by anthropogenic impacts. The use of so-called 'probiotics for wildlife' is a nascent application, and the field needs to reflect on standards for its development, testing, validation, risk assessment, and deployment. Here, we identify the main challenges of this emerging intervention and provide a roadmap to validate the effectiveness of wildlife probiotics. We cover the essential use of inert negative controls in trials and the investigation of the probiotic mechanisms of action. We also suggest alternative microbial therapies that could be tested in parallel with the probiotic application. Our recommendations align approaches used for humans, aquaculture, and plants to the emerging concept and use of probiotics for wildlife.

Paraprobiotics: definition, manufacturing methods, and functionality

Probiotics are living microorganisms that are beneficial to the host, enhancing the immune response by promoting antibody production, regulating cytokine secretion, and stimulating T cells. However, probiotics have limitations in that they require viability control and have a short shelf life. Recently, the use of paraprobiotics has gained attention. These include dead bacterial cells, bacterial fractions, and cell lysate that have health benefits and are stable and safe for use. Paraprobiotics comprise molecules of bacterial cell wall compounds, such as peptidoglycans, teichoic acids, polysaccharides, and cell surface proteins. Paraprobiotics are manufactured by a diverse range of techniques, including thermal treatments, high pressure, ultraviolet rays, sonication, ionizing radiation, and pH modification. Their beneficial health effects include immunomodulatory, intestinal balancing, anticancer, and antimicrobial activities. Therefore, this review summarizes and discusses the manufacturing methods and bioavailability of paraprobiotics and suggests their potential health advantages.

Effects of dietary feed supplementation with heat-treated Lactobacillus sakei HS-1 on the health status, blood parameters, and fecal microbes of Japanese Black calves before weaning

Background and Aim

Our previous research suggested that heat-killed Lactobacillus sakei HS-1 (HK-LS HS-1) is potentially beneficial for improving intestinal microbes and reducing the number of medical treatments. This study aimed to investigate the effect of HK-LS HS-1 as a supplement in milk replacers (MRs) on clinical health during the 1-month preweaning period.

Materials and Methods

Eighteen female calves were randomly assigned to either a group receiving the HK-LS HS-1 supplement (n = 9) or a control group without it (n = 9). We then investigated the effect of including supplementary HK-LS HS-1; 0.2% in MRs twice daily at 09:00 and 16:00 on the health, serum biochemical parameters (measured using an automated biochemical analyzer), and fecal bacteriological changes of preweaning Japanese Black calves at the day of the start of supplementation (before HK-LS HS-1 supplementation; day 0), at weaning (day 30), and at 2 weeks (day 45) and 4 weeks (day 60) after weaning.

Results

During the supplementation period (0-30 days), (1) an increase (p = 0.023) was observed in albumin, and there was a tendency of increase in total cholesterol level in the HK-LS HS-1 group but not in the control group; (2) substantial differences were obtained after the weaning period (30-60 days), although no differences were observed from 0-30 days in both groups. The anti-Müllerian hormone (AMH) level was substantially increased after weaning in the control group. No differences were observed in the amounts of Coliform spp. and Staphylococcaceae spp. between the two groups; thus, HK-LS HS-1 supplementation had similar antibacterial effects. A significant reduction was observed in the time to weaning of the HK-LS HS-1 group in the field trial.

Conclusion

Supplementation with HK-LS HS-1 from an early stage after birth to weaning is a cost-effective treatment to improve the growth rate of preweaning calves. However, supplementation during only preweaning periods appears to have no beneficial effects on preventing weaning stress, especially in terms of AMH levels.

Oral intake of heat-killed Lactiplantibacillus pentosus ONRICb0240 partially protects mice against SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the ongoing coronavirus pandemic. Besides vaccines and antiviral drugs, probiotics have attracted attention for prevention of SARS-CoV-2 infection. Here, we examined the efficacy of heat-killed Lactiplantibacillus pentosus ONRICb0240 (b240) against SARS-CoV-2 infection in mice. We observed that oral intake of heat-killed b240 did not affect virus titers in the respiratory organs of SARS-CoV-2-infected mice, but did provide partial protection against SARS-CoV-2 infection. In addition, heat-killed b240 treatment suppressed the expression of IL-6, a key proinflammatory cytokine, on Day 2 post-infection. Our results highlight the promising protective role of heat-killed b240 and suggest a possible mechanism by which heat-killed b240 partially protects against SARS-CoV-2 infection by modulating host responses.

Evaluation of the Combined Administration of Chlorella fusca and Vibrio proteolyticus in Diets for Chelon labrosus: Effects on Growth, Metabolism, and Digestive Functionality

This study aimed to evaluate the combined effect of dietary Chlorella fusca and ethanol-inactivated Vibrio proteolyticus DCF12.2 (C + V diet) in Chelon labrosus juveniles, highlighting their nutritional, physiological, and morphological effects. The results showed that the combined dietary inclusion of C. fusca and V. proteolyticus significantly enhanced growth performance and feed utilization compared to the control group. The C + V diet increased the fish lipid quality index (FLQ), n-3 polyunsaturated fatty acids, and n-3/n-6 ratio, which might be beneficial in terms of human nutrition. The C + V diet considerably increased carbohydrate metabolic activity by statistically boosting plasma glucose. The dietary inclusion of C. fusca in conjunction with V. proteolyticus increased metabolic enzyme activity as well as intestinal absorption capacity compared to that found in the control group. In conclusion, the experimental diet was suitable for feeding C. labrosus, increasing their growth and the nutritional characteristics of the muscle and intestine, without causing tissue damage.

Antimicrobial Resistance and Recent Alternatives to Antibiotics for the Control of Bacterial Pathogens with an Emphasis on Foodborne Pathogens

Antimicrobial resistance (AMR) is one of the most important global public health problems. The imprudent use of antibiotics in humans and animals has resulted in the emergence of antibiotic-resistant bacteria. The dissemination of these strains and their resistant determinants could endanger antibiotic efficacy. Therefore, there is an urgent need to identify and develop novel strategies to combat antibiotic resistance. This review provides insights into the evolution and the mechanisms of AMR. Additionally, it discusses alternative approaches that might be used to control AMR, including probiotics, prebiotics, antimicrobial peptides, small molecules, organic acids, essential oils, bacteriophage, fecal transplants, and nanoparticles.

Bi-directional elucidation of Lactiplantibacillus plantarum (RTA 8) intervention on the pathophysiology of gut-brain axis during Salmonella brain infection

BACKGROUND

There have been reports of patients suffering from typhoid fever, particularly those involving infants and immunocompromised patients, which at times present with Salmonella induced brain infection. Although rare, it has frequently been associated with adverse neurological complications and increased mortality. In this context, the gut-brain axis, involving two-way communication between the gut and the brain, holds immense significance as various gut ailments have been associated with psychiatric complications. In turn, several neurodegenerative diseases have been associated with an altered gut microbiota profile. Given the paucity of effective antimicrobials and increasing incidence of multi-drug resistance in pathogens, alternate treatment therapies such as probiotics have gained significant attention in the recent past.

RESULTS

In the current study, prophylactic effect of Lactiplantibacillus plantarum (RTA 8) in preventing neurological complications occurring due to Salmonella brain infection was evaluated in a murine model. Along with a significant reduction in bacterial burden and improved histoarchitecture, L. plantarum (RTA 8) administration resulted in amelioration in the level of neurotransmitters such as serotonin, norepinephrine and dopamine in the gut as well as in the brain tissue. Simultaneously, increased gene expression of physiologically essential molecules such as mucin (MUC1 and MUC3) and brain-derived neurotrophic factor (BDNF) was also observed in this group.

CONCLUSION

Present study highlights the potential benefits of a probiotic supplemented diet in improving various aspects of host health due to their multi-targeted approach, thereby resulting in multi-faceted gains.

A Tentative Study of the Effects of Heat-Inactivation of the Probiotic Strain Shewanella putrefaciens Ppd11 on Senegalese Sole (Solea senegalensis) Intestinal Microbiota and Immune Response

Concerns about safety, applicability and functionality associated with live probiotic cells have led to consideration of the use of non-viable microorganisms, known as paraprobiotics. The present study evaluated the effects of dietary administration of heat-inactivated cells of the probiotic strain Shewanella putrefaciens Ppd11 on the intestinal microbiota and immune gene transcription in Solea senegalensis. Results obtained were evaluated and compared to those described after feeding with viable Pdp11 cells. S. senegalensis specimens were fed with basal (control) diet or supplemented with live or heat inactivated (60 °C, 1 h) probiotics diets for 45 days. Growth improvement was observed in the group receiving live probiotics compared to the control group, but not after feeding with a probiotic heat-inactivated diet. Regarding immune gene transcription, no changes were observed for tnfα, il-6, lys-c1, c7, hsp70, and hsp90aa in the intestinal samples based on the diet. On the contrary, hsp90ab, gp96, cd4, cd8, il-1β, and c3 transcription were modulated after probiotic supplementation, though no differences between viable and heat-inactivated probiotic supplemented diets were observed. Modulation of intestinal microbiota showed remarkable differences based on the viability of the probiotics. Thus, higher diversity in fish fed with live probiotic cells, jointly with increased Mycoplasmataceae and Spirochaetaceae to the detriment of Brevinemataceae, was detected. However, microbiota of fish receiving heat-inactivated probiotic cells showed decreased Mycoplasmataceae and increased Brevinemataceae and Vibrio genus abundance. In short, the results obtained indicate that the viable state of Pdp11 probiotic cells affects growth performance and modulation of S. senegalensis intestinal microbiota. On the contrary, minor changes were detected in the intestinal immune response, being similar for fish receiving both, viable and inactivated probiotic cell supplemented diets, when compared to the control diet.

The biological activities of postbiotics in gastrointestinal disorders

According to outcomes from clinical studies, an intricate relationship occurs between the beneficial microbiota, gut homeostasis, and the host's health status. Numerous studies have confirmed the health-promoting effects of probiotics, particularly in gastrointestinal diseases. On the other hand, the safety issues regarding the consumption of some probiotics are still a matter of debate, thus to overcome the problems related to the application of live probiotic cells in terms of clinical, technological, and economic aspects, microbial-derived biomolecules (postbiotics) were introducing as a potential alternative agent. Presently scientific literature confirms that the postbiotic components can be used as promising tools for both prevention and treatment strategies in gastrointestinal disorders with less undesirable side-effects, particularly in infants and children. Future head-to-head trials are required to distinguish appropriate strains of parent cells, optimal dosages of postbiotics, and assessment of the cost-effectiveness of postbiotics compared to alternative drugs. This review provides an overview of the concept and safety issues regarding postbiotics, with emphasis on their biological role in the treatment of some important gastrointestinal disorders.

Growth and adhesion inhibition of pathogenic bacteria by live and heat-killed food-origin Lactobacillus strains or their supernatants

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products.

Effects of heat-killed Enterococcus faecalis T-110 supplementation on gut immunity, gut flora, and intestinal infection in naturally aged hamsters

Infectious diseases are a threat to elderly individuals, whose immune systems weaken with age. Among the various infectious diseases, Clostridium difficile infection is associated with a high rate of mortality in elderly individuals and is a serious health problem worldwide, owing to the increasing infection rates. Probiotic use has been proposed as an effective countermeasure for C. difficile infection. The aim of this study was to evaluate the effects of heat-killed Enterococcus faecalis T-110 on intestinal immunity, intestinal flora, and intestinal infections, especially C. difficile infections, in naturally ageing animals, for extrapolating the results to elderly human subjects. Twenty female hamsters were randomly distributed into two groups. Group 1 was fed a basal diet and group 2 was fed a basal diet supplemented with heat-killed E. faecalis for 7 days. Heat-killed E. faecalis T-110 improved the gut immunity and microflora, especially Clostridium perfringens and C. difficile, in naturally aged hamsters. Therefore, heat-killed E. faecalis T-110 use may be a countermeasure against age-related immune dysfunction and intestinal infections, especially C. difficile infection, in elderly humans. However, further investigation in this regard is needed in humans.

Current Perspectives and Potential of Probiotics to Limit Foodborne Campylobacter in Poultry

Poultry has been one of the major contributors of Campylobacter related human foodborne illness. Numerous interventions have been applied to limit Campylobacter colonization in poultry at the farm level, but other strategies are under investigation to achieve more efficient control. Probiotics are viable microbial cultures that can establish in the gastrointestinal tract (GIT) of the host animal and elicit health and nutrition benefits. In addition, the early establishment of probiotics in the GIT can serve as a barrier to foodborne pathogen colonization. Thus, probiotics are a potential feed additive for reducing and eliminating the colonization of Campylobacter in the GIT of poultry. Screening probiotic candidates is laborious and time-consuming, requiring several tests and validations both in vitro and in vivo. The selected probiotic candidate should possess the desired physiological characteristics and anti-Campylobacter effects. Probiotics that limit Campylobacter colonization in the GIT rely on different mechanistic strategies such as competitive exclusion, antagonism, and immunomodulation. Although numerous research efforts have been made, the application of Campylobacter limiting probiotics used in poultry remains somewhat elusive. This review summarizes current research progress on identifying and developing probiotics against Campylobacter and presenting possible directions for future research efforts.

Heat-Killed Lactobacillus brevis Enhances Phagocytic Activity and Generates Immune-Stimulatory Effects through Activating the TAK1 Pathway

There is an increasing interest in using inactivated probiotics to modulate the host immune system and protect against pathogens. As the immunomodulatory function of heat-killed Lactobacillus brevis KCTC 12777BP (LBB) and its mechanism is unclear, we investigated the effect of LBB on immune response based on the hypothesis that LBB might exert stimulatory effects on immunity. In the current study, we demonstrate that administration of LBB can exert immune-stimulatory effects and promote clearance of foreign matters through enhancing phagocytosis. Treatment with LBB induced the production of TNF-α, IL-6, and nitric oxide in macrophages. Importantly, LBB directly increased the phagocytic activity of macrophages against bacterial particles. LBB was able to promote the production of TNF-α in bone marrow-derived macrophages and splenocytes and also increase the proliferation rate of splenocytes, suggesting that the immune-stimulating activity of LBB can be observed in primary immune cells. Investigation into the molecular mechanism responsible revealed that LBB upregulates TAK1 activity and its downstream ERK, p38, and JNK signaling pathways. To further confirm the immunomodulatory capability of LBB in vivo, we orally administered LBB to mice and assessed the effect on primary splenocytes. Splenocytes isolated from LBB-treated mice exhibited higher TNF-α expression and proliferative capacity. These results show that heat-killed L. brevis, a wildly consumed probiotic, may provide protection against pathogens through enhancing host immunity.

Lactobacillus plantarum Strains Isolated from Polish Regional Cheeses Exhibit Anti-Staphylococcal Activity and Selected Probiotic Properties

Twenty-nine Lactobacillus plantarum strains isolated from different types of Polish regional cheeses (Oscypek and Korycinski) were assessed for selected probiotic properties and anti-staphylococcal activity. Most of the tested L. plantarum strains were considered safe. Whole bacterial cultures (WBC) and cell-free supernatants (CFSs) of L. plantarum strains inhibited growth of Staphylococcus aureus (average inhibition growth zones were 2.8 mm ± 1.2 and 2.8 mm ± 1.1 respectively). Moreover, almost all neutralized, catalase-treated cell-free supernatants (CFN) of L. plantarum cultures also exhibited slight anti-staphylococcal activity in vitro. The most promising strains Os4 and Kor14 were selected for further study. Both strains were able to survive during digestive gastro-intestinal passage model. Live cells of L. plantarum Os4 and Kor14 caused the strongest inhibition of S. aureus adhesion to Caco-2 cells comparing with CFN and heat-killed bacterial cells. S. aureus and L. plantarum (Os4 or Kor14) co-cultured in skim milk resulted in growth inhibition of S. aureus in both 8 °C and 37 °C incubation temperatures. Observed abilities, demonstrated for L. plantarum Os4 and Kor14, confirms that these strains could be used in the food industry as protective cultures.

Effects of dietary feed supplementation of heat-treated Lactobacillus sakei HS-1 on the health status, blood parameters, and fecal microbes of Japanese Black calves

This study investigated the effect of heat-killed Lactobacillus sakei HS-1 (HK-LS HS-1) on the health and fecal bacteriological change of suckling Japanese Black calves as a supplement in milk replacers. Twelve calves were separated from dams to calf-hatch after calving for milk replacers feeding. They were randomly assigned to an HK-LS HS-1 supplement or a control without HK-LS HS-1 group in milk replacers. HK-LS HS-1 was administered from separation day to 3 weeks. Blood and fecal samples were examined. Two calves with a haptoglobin concentration of >500 µg/ml on day 0 were excluded from the experiment, and 10 calves were finally included. Glucose and vitamin A levels on day 7 were significantly higher (P<0.05) in the supplement group than in the control group. No significant differences were observed in haptoglobin or serum amyloid A between the groups. The number of Escherichia coli in feces was lower in the control group than in the supplement group on day 21 (P=0.06). No difference was observed in the number of bifidobacteria, but that of lactic acid bacteria was significantly higher (P<0.05) in the supplement group on day 21. The number of medications administered was significantly lower (P<0.05) in the supplement group (5.2 ± 3.9) than in the control group (10.6 ± 5.9) during the experimental period. The results indicated that HK-LS HS-1 is potentially beneficial for improving intestinal microbes and reducing the number of medical treatments.

Molecular mechanisms of postbiotics in colorectal cancer prevention and treatment

The occurrence of colorectal cancer (CRC) has been rising expeditiously and anticipated that 2.4 million new occasions of CRC will be detected yearly around the world until the year 2035. Due to some side-effects and complications of conventional CRC therapies, bioactive components such as microbial-derived biomolecules (postbiotics) have been attaining great significance by researchers for adjuvant therapy in CRC patients. The term 'postbiotics' encompasses an extensive range of complex micro- and macro-molecules (<50, 50-100, and 100< kDa) such as inactivated microbial cells, cell fractions or metabolites, which confer various physiological health benefits to the host when administered in adequate amounts. Postbiotics modulate the composition of the gut microbiota and the functionality of the immune system, as well as promote the CRC treatment effectiveness and reduces its side-effects in CRC patients due to possessing anti-oxidant, anti-proliferative, anti-inflammatory, and anti-cancer activities. Presently scientific literature confirms that postbiotics with their unique characteristics in terms of clinical (safe origin), technological (stability), and economic (low production costs) aspects can be used as promising tools for both prevent and adjuvant treat strategies in CRC patients without any serious undesirable side-effects. This review provides an overview of the concept and safety issues regarding postbiotics, with emphasis on their biological role in the prevention and treatment of CRC.

Protective Effect of Potential Probiotic Strains from Fermented Ethiopian Food against Salmonella Typhimurium DT104 in Mice

Salmonella is one of the most harmful pathogens responsible for foodborne outbreaks, illnesses and deaths. The aim of this study was to evaluate the effect of potentially probiotic strains against Salmonella Typhimurium DT104 in mice. The compatibility test among the selected potential probiotic strains (Lactobacillus plantarum K132, Lactobacillus paracasei K114 and Lactococcus lactis E124) using the cross-streaking method showed the absence of antagonism. The anti-Salmonella activities of coculture of the isolated potential probiotics in the form of mixed or single culture showed a remarkable anti-Salmonella activity with 96.50 to 100% growth inhibition. The combination of strains, which showed the highest growth inhibition rates against Salmonella Typhimurium DT104, was used to test their effect on the colonization of mice by Salmonella Typhimurium DT104. White albino male mice were pretreated with the mixed potential probiotics for 7 days and infected with Salmonella Typhimurium DT104 for 1 day. A total of 3 treatments were applied, during which the negative control group was treated with phosphate-buffered saline (PBS); a positive control group (typ) was challenged with Salmonella Typhimurium DT104 alone. The treated group (pro-typ) was pretreated with mixed potential probiotic culture and then infected with Salmonella Typhimurium DT104. The survival rate of mice and counts of Salmonella in feces were recorded. The survival rate of mice on day 21 after the oral challenge with Salmonella Typhimurium DT104 was significantly (p < 0.05) higher in the experimental pro-typ group (100% survival) compared with the positive control group (20% survival). The counts (colony-forming unit per ml) of Salmonella in feces were significantly lower (p < 0.05) for the pro-typ group compared to the typ group. The combination of potential probiotic strains was able to protect mice against Salmonella Typhimurium DT104 infection that demonstrates their potential to be used as probiotic cultures for the production of functional fermented products.

Lactobacillus plantarum B7 attenuates Salmonella typhimurium infection in mice: preclinical study in vitro and in vivo

Background

Salmonella typhimurium is a cause of gastroenteritis including diarrhea. Lactobacillus plantarum is a probiotic widely used to prevent and treat diarrhea.

Objectives

To determine the protective effects of L. plantarum B7 on diarrhea in mice induced by S. typhimurium.

Methods

Inhibition of S. typhimurium growth by L. plantarum B7 was determined using an agar spot method. Mice were divided into 3 groups (n = 8 each): a control group, an S group administered 3 × 109 CFU/mL S. typhimurium, and an S + LP group administered 1 × 109 CFU/mL L. plantarum B7 and 3 × 109 CFU/mL S. typhimurium daily for 3 days. Counts of S. typhimurium and percentage of fecal moisture content (%FMC) were determined from stool samples. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and CXCL1 were determined.

Results

L. plantarum B7 produced a clear zone on S. typhimurium. There were significantly less S. typhimurium in the feces from mice in the S+LP group than in the S group. Serum levels of TNF-α, IL-6, and CXCL1 in mice from the S group were significantly higher than levels in the S+LP and control groups. Feces from mice in the S group were soft and loose, whereas in the S+LP group they were hard and rod shaped. The %FMC in the S+LP group was significantly less than in the S group.

Conclusions

L. plantarum B7 can inhibit growth of S. typhimurium, decrease levels of proinflammatory cytokines, and attenuate symptoms of diarrhea induced in mice by S. typhimurium.

Health Benefits of Heat-Killed (Tyndallized) Probiotics: An Overview

Nowadays, the oral use of probiotics is widespread. However, the safety profile with the use of live probiotics is still a matter of debate. Main risks include: Cases of systemic infections due to translocation, particularly in vulnerable patients and pediatric populations; acquisition of antibiotic resistance genes; or interference with gut colonization in neonates. To avoid these risks, there is an increasing interest in non-viable microorganisms or microbial cell extracts to be used as probiotics, mainly heat-killed (including tyndallized) probiotic bacteria (lactic acid bacteria and bifidobacteria). Heat-treated probiotic cells, cell-free supernatants, and purified key components are able to confer beneficial effects, mainly immunomodulatory effects, protection against enteropathogens, and maintenance of intestinal barrier integrity. At the clinical level, products containing tyndallized probiotic strains have had a role in gastrointestinal diseases, including bloating and infantile coli-in combination with mucosal protectors-and diarrhea. Heat-inactivated probiotics could also have a role in the management of dermatological or respiratory allergic diseases. The reviewed data indicate that heat-killed bacteria or their fractions or purified components have key probiotic effects, with advantages versus live probiotics (mainly their safety profile), positioning them as interesting strategies for the management of common prevalent conditions in a wide variety of patients´ characteristics.

Strain-specific properties of Lactobacillus plantarum for prevention of Salmonella infection

Salmonella is a common food-borne pathogen; since lactobacilli show great potential for protecting against Salmonella infections, they are used as dietary supplements in functional foods. The aim of this study is to investigate the strain-specific properties and the involved mechanisms of action of Lactobacillus plantarum towards prevention of Salmonella infection. Mice were pretreated with mixed strains or single strain of Lactobacillus plantarum for 10 d prior to infection with Salmonella typhimurium SL1344, and the survival rates showed that lactobacilli exhibited strain-specific properties for preventing Salmonella infection. Then, in vitro and in vivo studies were carried out to investigate the involved mechanism of the strain-specific properties. The results showed that different Lactobacillus plantarum strains had different effects on inhibiting Salmonella growth, thus preventing adhesion to and invasion of epithelial cells by pathogens and enhancing immune responses. The present study demonstrated strain-specific properties of probiotics to prevent Salmonella infection and elucidated their underlying mechanisms.

Investigating the Effect of Different Treatments with Lactic Acid Bacteria on the Fate of Listeria monocytogenes and Staphylococcus aureus Infection in Galleria mellonella Larvae

The use of Galleria mellonella as a model host to elucidate microbial pathogenesis and search for novel drugs and therapies has been well appreciated over the past years. However, the effect of microorganisms with functional appeal in the specific host remains scarce. The present study investigates the effect of treatment with selected lactic acid bacteria (LAB) with probiotic potential, as potential protective agents by using live or heat-killed cells at 6 and 24 h prior to infection with Listeria monocytogenes and Staphylococcus aureus or as potential therapeutic agents by using cell-free supernatants (CFS) after infection with the same pathogens. The employed LAB strains were Lactobacillus pentosus B281 and Lactobacillus plantarum B282 (isolated from table olive fermentations) along with Lactobacillus rhamnosus GG (inhabitant of human intestinal tract). Kaplan-Meier survival curves were plotted while the pathogen's persistence in the larval hemolymph was determined by microbiological analysis. It was observed that the time (6 or 24 h) and type (live or heat-killed cells) of challenge period with LAB prior to infection greatly affected the survival of infected larvae. The highest decrease of L. monocytogenes population in the hemolymph was observed in groups challenged for 6 h with heat-killed cells by an average of 1.8 log units compared to non challenged larvae for strains B281 (p 0.0322), B282 (p 0.0325), and LGG (p 0.0356). In the case of S. aureus infection, the population of the pathogen decreased in the hemolymph by 1 log units at 8 h post infection in the groups challenged for 6 h with heat-killed cells of strains B281 (p 0.0161) and B282 (p 0.0096) and by 1.8 log units in groups challenged with heat-killed cells of LGG strain (p 0.0175). Further use of CFS of each LAB strain did not result in any significant prolonged survival but interestingly it resulted in pronounced decrease of L. monocytogenes in the hemolymph at 24 h and 48 h after infection by more than 1 log unit (p < 0.05) depending on the strain. The results of the present work support the broader use of G. mellonella larvae as a low cost in vivo tool for screening for probiotic properties.

A study on the prevention of salmonella infection by using the aggregation characteristics of lactic Acid bacteria

Salmonella is one of the major pathogenic bacteria that cause food poisoning. This study investigated whether heat-killed as well as live Lactobacillus protects host animal against Salmonella infection. Live and heat-killed Lactobacillusacidophilus was administered orally to Sprague-Dawley rats for 2 weeks before the rats were inoculated with Salmonella. Rise in body temperature was moderate in the group that was treated with heat-killed bacteria as compared to the Salmonella control group. The mean amount of feed intake and water consumption of each rat in the heat-killed bacteria group were nearly normal. The number of fecal Salmonellae was comparable between the live and the heat-killed L. acidophilus groups. This finding shows that L. acidophilus facilitates the excretion of Salmonella. Moreover, the levels of pro inflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta, in the heat-killed L. acidophilus group were significantly lower when compared to the levels in the Salmonella control group. These results indicate that nonviable lactic acid bacteria also could play an important role in preventing infections by enteric pathogens such as Salmonella.

Protective efficacy of orally administered, heat-killed Lactobacillus pentosus b240 against influenza A virus

Influenza A(H1N1)pdm virus caused the first human pandemic of the 21st century. Although various probiotic Lactobacillus species have been shown to have anti-microbial effects against pneumonia-inducing pathogens, the prophylactic efficacy and mechanisms behind their protection remain largely unknown. Here, we evaluated the prophylactic efficacy of heat-killed Lactobacillus pentosus b240 against lethal influenza A(H1N1)pdm virus infection in a mouse model. To further define the protective responses induced by b240, we performed virologic, histopathologic, and transcriptomic analyses on the mouse lungs. Although we did not observe an appreciable effect of b240 on virus growth, cytokine production, or histopathology, gene expressional analysis revealed that oral administration of b240 differentially regulates antiviral gene expression in mouse lungs. Our results unveil the possible mechanisms behind the protection mediated by b240 against influenza virus infection and provide new insights into probiotic therapy.

In vitro characterization of aggregation and adhesion properties of viable and heat-killed forms of two probiotic Lactobacillus strains and interaction with foodborne zoonotic bacteria, especially Campylobacter jejuni

Bacterial aggregation and/or adhesion are key factors for colonization of the digestive ecosystem and the ability of probiotic strains to exclude pathogens. In the present study, two probiotic strains, Lactobacillus rhamnosus CNCM-I-3698 and Lactobacillus farciminis CNCM-I-3699, were evaluated as viable or heat-killed forms and compared with probiotic reference Lactobacillus strains (Lb. rhamnosus GG and Lb. farciminis CIP 103136). The autoaggregation potential of both forms was higher than that of reference strains and twice that of pathogenic strains. The coaggregation potential of these two beneficial micro-organisms was evaluated against several pathogenic agents that threaten the global safety of the feed/food chain: Escherichia coli, Salmonella spp., Campylobacter spp. and Listeria monocytogenes. The strongest coaggregative interactions were demonstrated with Campylobacter spp. by a coaggregation test, confirmed by electron microscopic examination for the two forms. Viable forms were investigated for the nature of the bacterial cell-surface molecules involved, by sugar reversal tests and chemical and enzymic pretreatments. The results suggest that the coaggregation between both probiotic strains and C. jejuni CIP 70.2(T) is mediated by a carbohydrate-lectin interaction. The autoaggregation potential of the two probiotics decreased upon exposure to proteinase, SDS or LiCl, showing that proteinaceous components on the surface of the two lactobacilli play an important role in this interaction. Adhesion abilities of both Lactobacillus strains were also demonstrated at significant levels on Caco-2 cells, mucin and extracellular matrix material. Both viable and heat-killed forms of the two probiotic lactobacilli inhibited the attachment of C. jejuni CIP 70.2(T) to mucin. In conclusion, in vitro assays showed that Lb. rhamnosus CNCM-I-3698 and Lb. farciminis CNCM-I-3699, as viable or heat-killed forms, are adherent to different intestinal matrix models and are highly aggregative in vitro with pathogens, especially Campylobacter spp., the most commonly reported zoonotic agent in the European Union. This study supports the need for further in vivo investigations to demonstrate the potential food safety benefits of Lb. rhamnosus CNCM-I-3698 and Lb. farciminis CNCM-I-3699, live or heat-killed, in the global feed/food chain.

Use of culture-independent analysis to reveal alteration of intestinal microflora by heat-killed Lactobacillus pentosus in a mouse model of endogenous sepsis

In this study we evaluated alteration of intestinal microflora by terminal-restriction fragment length polymorphism (T-RFLP) analysis and quantitative PCR (qPCR) for specific microbes. The effects of orally administered heat-killed Lactobacillus pentosus strain b240 (HK-b240) in immunosuppressed mice with endogenous Pseudomonas aeruginosa sepsis was estimated. By T-RFLP analysis, 5 dominant operational taxonomic units (OTUs) including Bacteroides spp. (OTU460) and Lactobacillus spp. (OTU657) were consistently observed, irrespective of treatment, at all time points. A significantly higher population of segmented filamentous bacteria (SFB) was observed by qPCR after 3 weeks of HK-b240 administration; thereafter, the difference was not sustained during immunosuppression and progression of sepsis. Although not significant, Lactobacillus spp. accounted for a larger population in the HK-b240-treated group. In conclusion, this study demonstrated successful application of culture-independent assays for evaluating biological agents by detecting changes in microflora even if the protection was not sufficient to result in significant survival change.

Lactobacillus pentosus strain b240 suppresses pneumonia induced by Streptococcus pneumoniae in mice

AIMS

Oral administration of probiotics has been known to improve inflammatory responses against infectious diseases. Here, we describe the inhibitory effect of oral intake of heat-killed Lactobacillus pentosus strain b240 (b240) on pneumococcal pneumonia in a murine experimental model.

METHOD AND RESULTS

 The mice treated with oral b240 for 21 days before Streptococcus pneumoniae infection exhibited prolonged survival time and less body weight loss, compared with saline-treated control mice. Mild pneumonia with significantly reduced secretion of inflammatory cytokines/chemokines according to related mitogen-activated protein kinase signalling molecules (phosphorylated c-Jun N-terminal kinase) was found in b240-treated mice, whereas severe pneumonia with hypercytokinemia was evident in control mice. Prominent reduction in the number of pneumococci and elevated expression of Toll-like receptor 2 and 4 in the lung tissues was concomitantly noted in b240-treated mice.

CONCLUSIONS

These findings indicate that b240 has inhibitory effects on pneumococcal pneumonia induced by Strep. pneumoniae infection and improves inflammatory tissue responses, resulting in reduced damages to the respiratory tissues.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results demonstrate that oral administration of b240 might protect host animals from Strep. pneumoniae infection by augmentation of innate immune response.

Influence of Lactobacillus pentosus S-PT84 Ingestion on the Mucosal Immunity of Healthy and Salmonella Typhimurium-Infected Mice

Lactobacillus pentosus (L. pentosus) strain S-PT84, isolated from Kyoto pickles, enhances splenic natural killer (NK) cell activity, and has high T-helper1 (Th1) cytokine and type 1-IFN (IFN-α) inducing activity. In the present study, we investigated the influence of S-PT84 ingestion on the mucosal immunity of healthy and Salmonella Typhimurium (S. Typhimurium)-infected mice. In the S. Typhimurium infection model, numbers of S. Typhimurium in feces and the spleen were significantly decreased, and body weight loss and deterioration in the general health score of S. Typhimurium-infected mice were improved by S-PT84 ingestion. Oral administration of S-PT84 enhanced IL-5 and IL-6 production from Peyer’s patch cells in vitro, with a concomitant significant increase in IgA production from Peyer’s patch cells, which may explain the mechanism of enhanced IgA production in the small intestine in vivo. These results suggest that S-PT84 ingestion is useful for the maintenance of health or the improvement of certain symptoms during pathogen infection.

Heat-killed Lactobacillus acidophilus La205 enhances NK cell cytotoxicity through increased granule exocytosis

Heat-killed lactic acid bacteria (LAB) are known to be important immunomodulators that stimulate tumor necrosis factor-α (TNF-α) and nitric oxide (NO) production as well as increase phagocytic activity in macrophages. NK cells play a critical role in innate immune response and induce spontaneous killing of tumor cells and virus-infected cells. However, the effect of heat-killed LAB on NK cells is still unclear. In this study, we investigated the effect of heat-killed Lactobacillus acidophilus La205 (La205) on NK cytolytic activity. We found that heat-killed La205 directly stimulated NK cytolytic activity in dose- and time-dependent manners. To determine the mechanism underlying heat-killed La205-enhanced NK cytotoxicity, the expression of NK activating receptors was tested. Heat-killed La205 did not affect the expression of NK activating receptors. To investigate whether NK degranulation is related to heat-killed La205-enhanced NK cytotoxicity, NK degranulation inhibitor concanamycin A (CMA) was used. CMA effectively blocked heat-killed La205-induced NK cytotoxicity, and an assay for detection of a degranulation marker, CD107a, showed that heat-killed La205 increased granule exocytosis approximately 2-fold in comparison to non-treated NK cells. In addition, heat-killed La205 dramatically elevated mRNA expression of granulysin, a component of the cytolytic granule contents, in NK cells. However, other granule contents, including perforin and granzymes, were not changed by heat-killed La205. From these data, we concluded that heat-killed La205 stimulated NK cytolytic activity through enhancement of granule exocytosis, and granulysin may be a critical mediator in heat-killed La205-induced granule exocytosis.

Oral administration of heat-killed Lactobacillus pentosus strain b240 augments protection against influenza virus infection in mice

Host-defense mechanisms against influenza virus (IFV) infection involve both innate and acquired immunities. Among other components, secretory immunoglobulin A (SIgA) in the airway mucosa plays a particularly pivotal role in preventing IFV infection. Among 150 strains of lactic acid bacteria, Lactobacillus pentosus strain b240 (b240) has the highest IgA-inducing potency in mouse Peyer's patch cells. We previously reported a practical new finding that oral ingestion of nonviable heat-killed b240 elevates salivary IgA secretion in humans. The present study aimed to determine if nonviable b240 can prevent IFV infection in mice. In a BALB/c mouse model infected with lethal levels of IFV A/PR8/34 (H1N1), oral administration of b240 for 3 weeks by gavage prior to IFV infection significantly prolonged the survival period. For IFV infection at nonlethal levels, the infectious titers of IFV in the lungs 7 days after infection were significantly reduced after similar b240 administration. Both anti-IFV IgA and immunoglobulin G titers in bronchoalveolar lavage fluid and plasma on day 7 were significantly higher in the b240-treated group than the control group. The augmentation of the anti-IFV immune response by b240 application was preliminarily confirmed by the elevated production of IFV-driven T-cell factors during mixed lymphocyte reactions with b240-primed splenocytes. These results suggest that oral nonviable heat-killed b240 intake can facilitate protection against IFV infection.