Antagonistic effects of Lactobacillus plantarum 0612 on the adhesion of selected foodborne enteropathogens in various colonic environments

The Effects of Cellular Membrane Damage on the Long-Term Storage and Adhesion of Probiotic Bacteria in Caco-2 Cell Line

Adhesion is one of the main factors responsible for the probiotic properties of bacteria in the human gut. Membrane proteins affected by cellular damage are one of the key aspects determining adhesion. Fluid-bed-dried preparations containing probiotic bacteria were analyzed in terms of their stability (temperature of glass transition) and shelf life in different conditions (modified atmosphere, refrigeration). Imaging flow cytometry was utilized to determine four subpopulations of cells based on their physiological and morphological properties. Lastly, adhesion was measured in bacteria cultured in optimal conditions and treated with heat shock. The results show that the subpopulations with no or low levels of cell membrane damage exhibit the ability to adhere to Caco-2 cells. The temperature of protein denaturation in bacteria was recorded as being between 65 °C and 70 °C. The highest glass transition temperature (Tg) value for hydroxypropyl methylcellulose (used as a coating substance) was measured at 152.6 °C. Drying and coating can be utilized as a sufficient treatment, allowing a long shelf-life (up to 12 months). It is, however, worth noting that technological processing, especially with high temperatures, may decrease the probiotic value of the preparation by damaging the bacterial cells.

Antibacterial and anti-biofilm activities of probiotic Lactobacillus plantarum against Listeria monocytogenes isolated from milk, chicken and pregnant women

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that poses significant risks to public health and food safety. The present study aimed to identify the presence of Listeria spp. in various samples, including pasteurized milk, chicken fillets, and stool samples from pregnant women in Sharkia Governorate, Egypt. Additionally, the study identified the serotypes, virulence-associated genes, antimicrobial resistance patterns, and biofilm formation in L. monocytogenes isolates. Moreover, the antibacterial and anti-biofilm activity of Lactobacillus plantarum ATCC 14917 (L. plantarum) against L. monocytogenes isolates was investigated. A cross-sectional study was conducted from August 2021 to January 2022 to collect 300 samples of pasteurized milk, chicken fillets, and stool from pregnant women admitted to outpatient clinics of hospitals. The results showed that 32.7% of the samples were positive for Listeria spp., including L. innocua (48.9%), L. monocytogenes (26.5%), L. ivanovii (14.3%), L. grayi (5.1%), and L. welshimeri (5.1%). Among all L. monocytogenes isolates, hlyA, actA, inlC, and inlJ virulence-associated genes were detected. However, the virulence genes plcB, iap, and inlA were found in 10 (38.5%), 8 (30.8%), and 25 (96.2%) isolates, respectively. The L. monocytogenes isolates classified into four serotypes (1/2a, 1/2b, 1/2c, and 4b), with 1/2a and 4b each identified in 30.8% of the isolates, while 1/2b and 1/2c were identified in 19.2% of the isolates. All L. monocytogenes isolates showed 100% resistance to streptomycin, kanamycin, and nalidix acid, and 92.3% of isolates showed gentamicin resistance. However, all isolates were susceptible to ampicillin and ampicillin/sulbactam. Multidrug resistance (MDR) was observed in 20 (76.9%) L. monocytogenes isolates. The biofilm formation ability of 26 L. monocytogenes isolates was evaluated at different incubation temperatures. At 4°C, 25°C, and 37°C, 53.8, 69.2, and 80.8% of the isolates, respectively, were biofilm producers. Furthermore, 23.1% were strong biofilm producers at both 4°C and 25°C, while 34.6% were strong biofilm formers at 37°C. Treating L. monocytogenes isolates with L. plantarum cell-free supernatant (CFS) reduced the number of biofilm-producing isolates to 15.4, 42.3, and 53.8% at 4°C, 25°C, and 37°C, respectively. L. plantarum's CFS antibacterial activity was tested against six virulent, MDR, and biofilm-forming L. monocytogenes isolates. At a concentration of 5 μg/mL of L. plantarum CFS, none of the L. monocytogenes isolates exhibited an inhibition zone. However, an inhibition zone was observed against L. monocytogenes strains isolated from pasteurized milk and pregnant women's stools when using a concentration of 10 μg/mL. Transmission electron microscopy (TEM) revealed that L. plantarum CFS induced morphological and intracellular structural changes in L. monocytogenes. In conclusion, this study identified virulent MDR L. monocytogenes isolates with strong biofilm-forming abilities in food products in Egypt, posing significant risks to food safety. Monitoring the prevalence and antimicrobial resistance profile of L. monocytogenes in dairy and meat products is crucial to enhance their safety. Although L. plantarum CFS showed potential antibacterial and anti-biofilm effects against L. monocytogenes isolates, further research is needed to explore its full probiotic potential.

Microbiological quality of probiotic products

Microorganisms used as probiotics should meet elementary safety aspects (non-toxicity, absence of antibiotic resistance genes and translocation) and functional/technological aspects (resistance and survival in the acid gastric environment, adhesiveness, stability, and cell viability). Probiotics with the health claim of being a dietary product or a pharmabiotic (drug category) should be clinically tested, validated, documented, and continuously controlled for quality. Important quality parameters include the identification of declared probiotic strains, the number of viable microorganisms (probiotic bacteria and/or fungi), and microbiological purity (absence of specified pathogenic/opportunistic pathogenic bacteria and fungi, and limitation of total unspecified contaminants such as aerobic bacteria, yeasts, and molds). Due to numerous reports of low-quality commercial probiotics marketed for human use, this review discusses the methods used to test the probiotic microorganism content, safety for the intended use, and proven health benefits of those probiotics whose microbiological quality deviates from the manufacturer's stated content, as well as the maintenance of cell viability, i.e., stability of the probiotic during the shelf life. In addition, the adverse effects of probiotics and the potential hazards to the health of the user are addressed.

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

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

Evaluation of Potential Probiotic Properties of a Strain of Lactobacillus plantarum for Shrimp Farming: From Beneficial Functions to Safety Assessment

In recent years the safety of probiotics has received increasing attention due to the possible transfer and spread of virulence factors (VFs) and antibiotic resistance genes (ARGs) among microorganisms. The safety of a strain of Lactobacillus plantarum named W2 was evaluated in phenotype and genotype in the present study. Its probiotic properties were also evaluated both in vivo and in vitro, including adherence properties, antibacterial properties and beneficial effects on the growth and immunity of Pacific white shrimp, Penaeus vannamei. Hemolysis tests, antibiotic resistance tests and whole genome sequence analysis showed that W2 had no significant virulence effects and did not carry high virulence factors. W2 was found to be sensitive to chloramphenicol, clindamycin, gentamicin, kanamycin and tetracycline, and to be resistant to ampicillin and erythromycin. Most ARGs have no transfer risk and a few have transfer risk but no significant enrichment in human-associated environments. The autoaggregation of W2 was 82.6% and the hydrophobicity was 81.0%. Coaggregation rate with Vibrio parahaemolyticus (24.9%) was significantly higher than Vibrio's autoaggregation rate (17.8%). This suggested that W2 had adhesion potential to mucosal/intestinal surfaces and was able to attenuate the adherence of V. parahaemolyticus. In addition, several adhesion-related protein genes, including 1 S-layer protein, 1 collagen-binding protein and 9 mucus-binding proteins were identified in the W2 genome. W2 had efficiently antagonistic activity against 7 aquatic pathogenic strains. Antagonistic components analysis indicated that active antibacterial substances might be organic acids. W2 can significantly promote the growth of shrimp when supplemented with 1 × 10¹⁰ cfu/kg live cells. Levels of 7 serological immune indicators and expression levels of 12 hepatopancreatic immune-related genes were up-regulated, and the mortality of shrimp exposed to V. parahaemolyticus was significantly reduced. Based on the above, L. plantarum W2 can be applied safely as a potential probiotic to enhance the growth performance, immunity capacity and disease resistance of P. vannamei.

The Application of Bacillus subtilis for Adhesion Inhibition of Pseudomonas and Preservation of Fresh Fish

Inhibiting the growth of spoilage bacteria, such as Pseudomonas spp., is key to reducing spoilage in fish. The mucus adhesion test in vitro showed that the adhesion ability of Bacillus subtilis was positively correlated with its inhibition ability to Pseudomonas spp. In vivo experiments of tilapia showed that dietary supplementation with B. subtilis could reduce the adhesion and colonization of Pseudomonas spp. in fish intestines and flesh, as well as reduce total volatile basic nitrogen (TVB-N) production. High throughput and metabolomic analysis showed treatment with B. subtilis, especially C6, reduced the growth of Pseudomonas spp., Aeromonas spp., Fusobacterium spp., and Enterobacterium spp., as well as aromatic spoilage compounds associated with these bacteria, such as indole, 2,4-bis(1,1-dimethylethyl)-phenol, 3-methyl-1-butanol, phenol, and 1-octen-3-ol. Our work showed that B. subtilis could improve the flavor of fish by changing the intestinal flora of fish, and it shows great promise as a microecological preservative.

The Panda-Derived Lactobacillus plantarum G201683 Alleviates the Inflammatory Response in DSS-Induced Panda Microbiota-Associated Mice

Intestinal diseases are one of the main causes of captive giant panda death. Their special dietary habits and gastrointestinal tract structure often lead to intestinal epithelium damage and secondary intestinal infection. The captive giant panda is predisposed to suffer from microbiota dysbiosis due to long-term artificial feeding and antibiotic misuse. However, there are few reported probiotics to treat giant panda enteritis and the associated dysbiosis. This study aims to elucidate the mechanism by which Lactobacillus plantarum G201683 (L. plantarum G83), a promising panda-derived probiotic, exerts a protective effect on intestinal inflammation in the dextran sulfate sodium- (DSS) induced panda microbiota-associated (DPMA) mouse model. The DPMA mouse was generated by antibiotic treatment and 5% DSS drinking water administration to assess the effect of L. plantarum G83 on intestinal inflammation and microbiota in vivo. Our results demonstrated the successful generation of a DPMA mouse model with Enterobacteriaceae enrichment, consistent with the giant panda intestinal microbiota. L. plantarum G83 decreased clinical and histological severity of intestinal inflammation, enhanced intestinal tight junction protein expression (ZO-1, Occludin) and alleviated inflammatory cytokine production (TNF-) in the colon of DPMA mice. The administration of L. plantarum G83 altered the microbiota composition by decreasing pathogen associated taxa such as E. coli and increasing abundance of beneficial bacteria including Bifidobacterium spp. These changes in microbiota composition were associated with an increased concentration of short chain fatty acids (SCFA), reduced NF-κB signaling, and an altered balance of T helper cell subsets. Our findings support L. plantarum G83 as a promising probiotic to treat intestinal inflammation in the giant panda.

Lactiplantibacillus plantarum-Nomad and Ideal Probiotic

Probiotics are increasingly recognized as capable of positively modulating several aspects of human health. There are numerous attributes that make an ideal probiotic. Lactiplantibacillus plantarum (Lp) exhibits an ecological and metabolic flexibility that allows it to thrive in a variety of environments. The present review will highlight the genetic and functional characteristics of Lp that make it an ideal probiotic and summarizes the current knowledge about its potential application as a prophylactic or therapeutic intervention.

Safety Evaluation of Bifidobacterium lactis BL-99 and Lacticaseibacillus paracasei K56 and ET-22 in vitro and in vivo

Probiotics have been reported to play a major role in maintaining the balance of microbiota in host. Consumption of food with probiotics has increased with consumer concerns regarding healthy diets and wellness. Correspondingly, safety evaluation of probiotics for human consumption has become increasingly important in food industry. Herein, we aimed to test the safety of Bifidobacterium lactis BL-99 and Lacticaseibacillus paracasei K56 and ET-22 strains in vitro and in vivo. In results, these strains were found to be negative for mucin degradation and platelet aggregation test. Additionally, the three strains were susceptible to eight antibiotics. In accordance with bacterial reversion mutation (Ames) assay, the tested strains had no genetic mutagenicity. Finally, it was confirmed that there were no dose-dependent mortality and toxicity throughout multidose oral toxicity tests in rats. Our findings demonstrated that B. lactis BL-99 and L. paracasei K56 and ET-22 can achieve the generally recognized as safe (GRAS) status as probiotics in the future.

Functional enrichment of gut microbiome by early supplementation of Bacillus based probiotic in cage free hens: a field study

BACKGROUND

The chicken gut microbiota passes through different stages of maturation; therefore, strengthening it with well characterised probiotics increases its resilience required for optimum gut health and wellbeing. However, there is limited information on the interaction of Bacillus based probiotics with gut microbial community members in cage free laying chickens both in rearing and production phases of life. In the current study, we investigated the changes in the gut microbiome of free range hens in the field after Bacillus based probiotic supplementation.

RESULTS

Overall, at phylum level, probiotic supplementation increased the populations of Bacteroidetes and Proteobacteria mainly at the expense of Firmicutes. The population of Bacteroidetes significantly increased during the production as compared to the rearing phase, and its higher population in the probiotic-supplemented chickens reflects the positive role of Bacillus based probiotic in gut health. Core differences in the beta diversity suggest that probiotic supplementation decreased microbial compositionality. The non-significant difference in alpha diversity between the probiotic and control chickens showed that the composition of community structure did not change. No Salmonella spp. were isolated from the probiotic supplemented birds. Egg internal quality was significantly higher, while egg production and body weight did not differ. Functional prediction data showed that probiotic supplementation enriched metabolic pathways, such as vitamin B6 metabolism, phenylpropanoid biosynthesis, monobactam biosynthesis, RNA degradation, retinol metabolism, pantothenate and CoA biosynthesis, phosphonate and phosphinate metabolism, AMPK signaling pathway, cationic antimicrobial peptide (CAMP) resistance and tyrosine metabolism.

CONCLUSIONS

Overall, age was the main factor affecting the composition and diversity of gut microbiota, where probiotic supplementation improved the abundance of many useful candidates in the gut microbial communities. The generated baseline data in the current study highlights the importance of the continuous use of Bacillus based probiotic for optimum gut health and production.

Probiotic Properties of New Lactobacillus Strains Intended to Be Used as Feed Additives for Monogastric Animals

The study aimed to evaluate the safety and probiotic properties of selected Lactobacillus strains, which are intended to be fed to monogastric animals. The Lactobacillus spp. appeared to be safe since they did not degrade mucus and did not exhibit β-haemolysis. Moreover, the survival of Caco-2 cells in the presence of metabolites of the selected strains was high, which also indicated their safety. The analysed strains showed moderate or strong antagonistic activity against Salmonella spp., Listeria monocytogenes, Campylobacter jejuni and Campylobacter coli, which was tested with the usage of the agar slab method. Furthermore, the strains showed high survivability in an acidic environment and the presence of bile salts (~90%). High resistivity or moderate susceptibility to antibiotics was also observed, as a result of the disc diffusion method. The strains were mostly moderately hydrophilic (hydrophobicity: 10.43–41.14%); nevertheless, their auto-aggregation capability exceeded 50% and their co-aggregation with pathogens varied between 12.12 and 85.45%. The ability of the selected strains to adhere to Caco-2 cells was also analysed; they were found to be moderately adhesive (85.09–95.05%) and able to hinder pathogens attaching to the cells (up to 62.58%). The analysed strains exhibit probiotic properties, such as high survivability and adherence to epithelial cells; therefore, they are suitable for administration to monogastric animals. Since the overuse of antibiotic growth promoters in livestock leads to the spread of antibiotic-resistant pathogens and accumulation of chemotherapeutic residues in food of animal origin, it is of vital importance to introduce alternative feed additives.

Health-Promoting Role of Lactiplantibacillus plantarum Isolated from Fermented Foods

Fermentation processes have been used for centuries for food production and preservation. Besides the contribution of fermentation to food quality, recently, scientific interest in the beneficial nature of fermented foods as a reservoir of probiotic candidates is increasing. Fermented food microbes are gaining attention for their health-promoting potential and for being genetically related to human probiotic bacteria. Among them, Lactiplantibacillus (Lpb.) plantarum strains, with a long history in the food industry as starter cultures in the production of a wide variety of fermented foods, are being investigated for their beneficial properties which are similar to those of probiotic strains, and they are also applied in clinical interventions. Food-associated Lpb. plantarum showed a good adaptation and adhesion ability in the gastro-intestinal tract and the potential to affect host health through various beneficial activities, e.g., antimicrobial, antioxidative, antigenotoxic, anti-inflammatory and immunomodulatory, in several in vitro and in vivo studies. This review provides an overview of fermented-associated Lpb. plantarum health benefits with evidence from clinical studies. Probiotic criteria that fermented-associated microbes need to fulfil are also reported.

Antimicrobial and anti-biofilm effects of probiotic Lactobacillus plantarum KU200656 isolated from kimchi

The probiotic properties and anti-pathogenic effects of Lactobacillus plantarum KU200656 (KU200656) isolated from Korean fermented kimchi against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella Typhimurium were investigated. KU200656 showed high tolerance to artificial gastric acid (99.48%) and bile salts (102.40%) and this strain was safe according to antibiotic sensitivity test; it could not produce harmful enzymes, including β-glucuronidase. KU200656 exhibited high adhesion (4.45%) to intestinal cells, HT-29 cells, with high cell surface hydrophobicity (87.31% for xylene and 81.11% for toluene). Moreover, KU200656 co-aggregated with pathogenic bacteria and exhibited antibacterial activity and anti-adhesion properties against pathogens. The cell-free supernatant (CFS) of KU200656 inhibited biofilm formation by pathogenic bacteria. In addition, half of the minimum inhibitory concentration of the KU200656 CFS downregulated the expression of biofilm-related genes, as determined by quantitative real-time PCR. Therefore, KU200656 was demonstrated to possess anti-pathogenic effects and have potential for use as probiotics in the food industry.

Cytotoxicity, apoptosis, and IL-8 gene expression induced by some foodborne pathogens in presence of Bacillus coagulans in HT-29 cells

Food poisoning caused by bacteria is one of the most important concerns in food hygiene. The use of probiotics in prevention, control, and treatment of these infections has been considerably increased in recent years. This study evaluated the effect of B. coagulans cell free supernatant (CFS) on growth of Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, non-pathogenic Escherichia coli, and Escherichia coli 0157:H7 by the broth dilution method. The cytotoxicity, and apoptosis induced by pathogens alone and in co-culture with B. coagulans or its CFS were measured by trypan blue, and fluorescence staining methods. The expression level of interleukin-8 (IL-8) cytokine-encoding genes was also investigated by a qRT-PCR assay in all pathogens and co-cultured groups in HT-29 cells. Our results showed that 4% B. coagulans CFS reduced pathogen growth. The highest rate of growth inhibition was observed in L. monocytogenes. We also found that B. coagulans, and its 4% CFS reduced the cytotoxic effects of pathogens, with the exception of S. aureus. Non-pathogenic E. coli also had no significant cytotoxic effect on the cells. Examination of the treated cells with acridine orange/ethidium bromide staining showed reductions in the rate of cell damage (including early apoptosis, late apoptosis, and necrosis) in pathogen-probiotic co-cultures. Furthermore, we showed that co-culture of pathogens with B. coagulans significantly down-regulated IL-8 gene expression (P < 0.05). The greatest down-regulation compared with pathogen alone was observed in S. aureus. Hence, B. coagulans can be considered as an appropriate probiotic to diminish cytotoxicity, and inflammatory response of enteropathogenic bacteria.

Lactobacillus acidophilus attenuates toxin production by Vibrio cholerae and shigella dysenteriae following intestinal epithelial cells infection

AIMS

The main objective of the present study was to assess and compare the safety and inhibitory efficacy of Lactobacillus acidophilus against cholera toxin and shigatoxin production by measuring CTX-B and Stx1 expression level in Caco-2 cells exposed to Vibrio cholerae (as a non-invasive small intestine pathogens and Shigella dysenteriae (as an invasive colon pathogen).

METHODS

Caco-2 cells were incubated with L. acidophilus 2 h before infection by V. cholerae and S. dysenteriae. Following RNA extraction and cDNA synthesis, relative toxins mRNA levels were determined according to a comparative critical threshold (Ct) real-time PCR. L. acidophilus didn't show any cytotoxic effect on Caco-2 cells.

RESULTS

L. acidophilus revealed a protective effect for Caco-2 cells against S. dysenteriae and V. cholera by 51% and 57%, respectively, which was determined by MTT assay and further confirmed by morphological examination. Pretreatment of Caco-2 cells with L. acidophilus prior to exposure to V. cholerae, attenuated the CTX-B expression in V. cholerae to about 1.76 folds. Expression of Stx1 by S. dysenteriae was also down-regulated to 1.6 folds following pretreatment of Caco-2 cells by L. acidophilus. No significant difference was observed in the attenuator role of L. acidophilus in toxin production by S. dysenteriae as a colon-invasive bacterium, compared with V. cholerae, the non-invasive pathogen of small intestine.

CONCLUSIONS

The results of the present study suggest that L. acidophilus is safe with protective effect for human epithelial colorectal cells, and is effective enough to be applied as a supplementary treatment for attenuation of toxin production in acute infectious diarrhea caused by V. cholerae and S. dysenteriae.

Determination of competition and adhesion abilities of lactic acid bacteria against gut pathogens in a whole-tissue model

In an intestinal system with a balanced microbial diversity, lactic acid bacteria (LAB) are the key element which prevents the colonization and invasion of gut pathogens. Adhesion ability is important for the colonization and competition abilities of LAB. The aim of this study was to determine the adhesion and competition abilities of LAB by using a whole-tissue model. Indigenous strains were isolated from spontaneously fermented foods like cheese and pickles. The aggregation and competition abilities of the isolates were determined, as well as their resistance to gastrointestinal conditions. Four Lactobacillus strains and one Weissella strain were found to be highly competitive against three major gut pathogens, namely Clostridium difficile, Listeria monocytogenes and Salmonella Enteritidis. Tested strains decreased the number of pathogens to below their disease-causing levels. According to the results, the numbers of C. difficile and L. monocytogenes bacteria decreased by an average of 3 log, and their adhesion rates decreased by approximately 50%. However, the number of S. Enteritidis bacteria was decreased by only 1 log compared with its initial number. We thought that the weak effect on Salmonella was due to its possession of many virulence factors. The results showed that natural isolates from sources other than human specimens like the Weissella strain in this study were quite competent when compared with the human isolates in terms of their adhesion to intestines and resistance to gastrointestinal tract conditions. It was also revealed that a whole-tissue model with all-natural layers can be successfully used in adhesion and competition tests.

In Vitro Studies on Therapeutic Potential of Probiotic Yeasts Isolated from Various Sources

The present study investigates the therapeutic properties of probiotic yeasts viz. Yarrowia lipolytica VIT-MN01, Kluyveromyces lactis VIT-MN02, Lipomyces starkeyi VIT-MN03, Saccharomycopsis fibuligera VIT-MN04 and Brettanomyces custersianus VIT-MN05. The antimutagenic activity of probiotic yeasts against the mutagens viz. Benzo[a]pyrene (B[a]P), and Sodium azide (SA) was tested. S. fibuligera VIT-MN04 showed highest antimutagenicity (75%). Binding ability on the mutagen acridine orange (AO) was tested and L. starkeyi VIT-MN03 was able to bind AO effectively (88%). The probiotic yeasts were treated with the genotoxins viz. 4-Nitroquinoline 1-Oxide (NQO) and Methylnitronitrosoguanidine (MNNG). The prominent changes in UV shift confirmed the reduction in genotoxic activity of S. fibuligera VIT-MN04 and L. starkeyi VIT-MN03, respectively. Significant viability of probiotic yeasts was noted after being exposed to mutagens and genotoxins. The adhesion capacity and anticancer activity were also assessed using Caco-2 and IEC-6 cell lines. Adhesion ability was found to be more in IEC-6 cells and remarkable antiproliferative activity was noted in Caco-2 cells compared to normal cells. Further, antagonistic activity of probiotic yeasts was investigated against S. typhimurium which was found to be more in S. fibuligera VIT-MN04 and L. starkeyi VIT-MN03. The inhibition of α-glucosidase and α-amylase activity confirmed the antidiabetic activity of probiotic yeasts. Antioxidant activity was also tested using standard assays. Therefore, based on the results, it can be concluded that probiotic yeasts can serve as potential therapeutic agents for the prevention and treatment of colon cancer, type 2 diabetes and gastrointestinal infections.

Yeasts isolated from Brazilian fermented foods in the protection against infection by pathogenic food bacteria

The consumption of probiotics has increased due to the reported health benefits, mainly in preventing or treating gastrointestinal pathology. This study investigated the antimicrobial capacity of yeasts, Saccharomyces cerevisiae and Pichia kluyveri, previously isolated from fermented foods (indigenous beverage, kefir and cocoa) against the adhesion of foodborne pathogens to Caco-2 cells. Co-aggregation of yeasts with pathogens and were evaluated by quantitative analysis and using scanning electron and laser confocal microscopies. All yeasts strains were able to co-aggregate with the tested pathogens, however, this activity was strain-dependent. The inhibition tests showed that the adhesion of Escherichia coli EPEC, Listeria monocytogenes and Salmonella Enteritidis to Caco-2 was reduced by all the yeasts studied. Most of the evaluated yeasts showed inhibition rates equal to or greater than the commercial probiotic Saccharomyces boulardii. The yeasts were able to reduce up to 50% of the bacterial infection, as observed for CCMA0615 towards EPEC in exclusion assay; CCMA0731, CCMA0732 and CCMA0615 towards L. monocytogenes in exclusion and competition assays; and CCMA0731 in exclusion and CCMA0731, CCMA0732, CCMA0615 in competition assay towards S. Enteritidis. No antimicrobial compounds were produced by the yeasts, showing that competition for nutrients and/or receptors in the intestinal mucosa was the mechanism to bacterial inhibition.

A novel universal nano-luciferase-involved reporter system for long-term probing food-borne probiotics and pathogenic bacteria in mice by in situ bioluminescence imaging

Food-borne bacteria have received increasing attention due to their great impact on human health. Bioimaging makes it possible to monitor bacteria inside the living body in real time and in situ. Nano-luciferase (NLuc) as a new member of the luciferase family exhibits superior properties than the commonly used luciferases, including small size, high stability and improved luminescence. Herein, NLuc, CBRLuc and FLuc were well expressed in varied food-borne bacteria. Results showed that the signal intensity of E. coli-NLuc was about 41 times higher than E. coli-CBRLuc, L. plantarum-NLuc was nearly 227 times that of L. plantarum-FLuc in vitro. Moreover, NLuc was applied to trace L. plantarum and E. coli in vivo through the whole body and separated digestive tract imaging, as well as the feces bacterium counting and probing. The persistence of bioluminescent strains was predominantly localized in colon and cecum of mice after oral administration. The NLuc system showed its incomparable superiority, especially in the application of intestinal imaging and the universality for food-borne bacteria. We demonstrated that the NLuc system was a brilliant alternative for specific application of food-borne bacteria in vivo, aiming to collect more accurate and real-time information of food-borne bacteria from the living body for further investigation of their damage mechanism and nutrition effect.

Schematic illustration of the preparation of bioluminescent bacteria and the experimental design of tracing of the foodborne bacteria in vivo.

The Step of Incorporation of Bacillus coagulans GBI-30 6086 Into "requeijão cremoso" Processed Cheese Does Not Affect Metabolic Homeostasis of Rats

Dairy product consumption is a common habit in Brazil. These products present a good matrix for probiotic incorporation. Thus, in this study the feasibility of producing a probiotic “requeijão cremoso” incorporated with Bacillus coagulans GBI-30 6086 in three different steps and its metabolic effect in an animal model for 2 weeks has been evaluated. Wistar adult health rats were randomized into one to five groups (n = 8 for each group): Control (C); “requeijão cremoso” without probiotic (RC); probiotic inoculated in the milk before pasteurization at 65°C/30 min (RPP); “requeijão cremoso” inoculated before the fusion step and consequently exposed to 90°C/5 min (RPF); and “requeijão cremoso” inoculated after fusion step, i.e., once the product temperature reached 50°C (RPAF). At the end of treatment, analysis of molecular markers of proteins of stress and antioxidant system, HSP 25, 60, 70 and 90, SOD and catalase were performed in the animals’ muscles by Western Blot technique. The HSP25, HSP90 and catalase levels of C, RPP, RPF, and RPAF were similar, indicating that the homeostasis remained unchanged. The incorporation of B. coagulans GBI-30 6086 in the “requeijão cremoso” was shown to be stable and the microorganism remained viable in all steps tested. The incorporation of the probiotic strain in the fusion stage facilitated the technological process, since it allowed a better homogenization of the product and did not affect the maintenance of the metabolic homeostasis of rats.

Adhesion mechanisms mediated by probiotics and prebiotics and their potential impact on human health

Adhesion ability to the host is a classical selection criterion for potential probiotic bacteria that could result in a transient colonisation that would help to promote immunomodulatory effects, as well as stimulate gut barrier and metabolic functions. In addition, probiotic bacteria have a potential protective role against enteropathogens through different mechanisms including production of antimicrobial compounds, reduction of pathogenic bacterial adhesion and competition for host cell binding sites. The competitive exclusion by probiotic bacteria has a beneficial effect not only on the gut but also in the urogenital tract and oral cavity. On the other hand, prebiotics may also act as barriers to pathogens and toxins by preventing their adhesion to epithelial receptors. In vitro studies with different intestinal cell lines have been widely used along the last decades to assess the adherence ability of probiotic bacteria and pathogen antagonism. However, extrapolation of these results to in vivo conditions still remains unclear, leading to the need of optimisation of more complex in vitro approaches that include interaction with the resident microbiota to address the current limitations. The aim of this mini review is to provide a comprehensive overview on the potential effect of the adhesive properties of probiotics and prebiotics on the host by focusing on the most recent findings related with adhesion and immunomodulatory and antipathogenic effect on human health.

Production of a Potentially Synbiotic Pomegranate Beverage by Fermentation with Lactobacillus plantarum ATCC 14917 Adsorbed on a Prebiotic Carrier

A probiotic biocatalyst was prepared through Lactobacillus plantarum ATCC 14917 immobilization on a prebiotic carrier (delignified wheat bran) and was used for fermentations of pomegranate juice. Initially, pomegranate juice was fermented for 24 h and then was stored for 28 days at 4 °C. The obtained results regarding sugar and organic acid analysis revealed that the probiotic biocatalyst was effective. Ethanol was produced in small amounts (0.4-1% v/v). Total phenolic content and antioxidant activity was greater in the fermented pomegranate juice than in unfermented juice after 24 h of fermentation and over the time span of 28 days. Viability of probiotic cells was well maintained (above 8.65 log cfu/mL) after 24 h of fermentation and during 4 weeks of storage at 4 °C, and it is noteworthy that no pathogens were observed. The strength of viability of probiotic cells can be attributed to the immobilization carrier (delignified wheat bran) that exhibits prebiotic properties providing a protective effect to the cells. Finally, the proposed bioprocess of employing the proposed synbiotic biocatalyst for pomegranate juice fermentation shows great potential for commercialization while sensory evaluation highlights the degree of quality of the produced functional pomegranate beverages.