Inhibition of in vitro growth of enteropathogens by new Lactobacillus isolates of human intestinal origin

Adjunctive efficacy of Bifidobacterium animalis subsp. lactis XLTG11 for functional constipation in children

Functional constipation (FC) can seriously affect the physical and mental health of children. The goal of this study is to assess the efficacy and safety of Bifidobacterium animalis subsp. lactis XLTG11 in treating FC in children through a randomized, double-blinded, placebo-controlled approach. Eligible children were randomized into either the intervention group (IG, n = 65, receiving conventional treatment with probiotics) or the control group (CG, n = 66, receiving conventional treatment without probiotics). The primary outcome measure was fecal frequency. Fecal gut microbiota analysis and PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) were used to predict gene family abundances based on 16S information. Over the course of treatment, the weekly frequency of feces within each group increased significantly (F = 41.97, p < 0.001). The frequency of feces (times/week (t/w)) in the IG was significantly higher than that in the CG (3.69 ± 2.62 t/w vs.3.18 ± 1.43 t/w, 4.03 ± 2.54 t/w vs. 2.89 ± 1.39 t/w and 3.74 ± 2.36 t/w vs. 2.94 ± 1.18 t/w and 3.45 ± 1.98 vs. 3.17 ± 1.41 t/w for the 1st, 2nd, 3rd, and 4th week after intervention, respectively) (F = 7.60, p = 0.0067). After the intervention, dominate species shifted to Bifidobacterium longum, Bifidobacterium breve, and Escherichia coli in the IG. Additionally, genes related to short-chain fatty acid (SCF) metabolism were upregulated, while methane metabolism was downregulated. Administration of XLTG11 at a dose of 1 × 1010 CFU/day to children increased fecal frequency, induced beneficial changes in gut microbiota, and regulated SCFs and methane metabolism-related genes.

Biopreservation of Fresh Sardines (Sardina pilchardus) Using Lactiplantibacillus plantarum OV50 Isolated from Traditional Algerian Green Olives Preparations

Lactiplantibacillus plantarum OV50 is a novel strain that was isolated from Algerian olives. Prior to its use as a natural biopreservative, OV50 underwent characterization for various functions. OV50 shows no proteolytic, lipolytic, or hemolytic activity. In addition, it is non-cytotoxic to eukaryotic cells and does not exhibit acquired antibiotic resistance. OV50 was tested with Pseudomonas aeruginosa ATCC 27835, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, and Vibrio cholerae ATCC 14035 in a sardine based-medium at 37 °C and 7 °C. At 37 °C, OV50 completely inhibited the growth of these foodborne pathogens for a maximum of 6 h. At 7 °C, it suppressed their growth for a maximum of 8 days, except for S. aureus ATCC 6538, whose growth was reduced from 4 to 2 log CFU/mL. Microbiological counts, total volatile basic nitrogen (TVB-N), and peroxide values (PV) concentrations were determined in fresh sardines inoculated with OV50 and kept at 7 °C for 12 days. The inoculated sardines showed a significant reduction in TVB-N levels at D8 (34.9 mg/100 g) compared to the control (59.73 mg/100 g) and in PV concentrations at D4 (6.67 meq/kg) compared to the control (11.44 meq/kg), as well as a significant reduction in the numbers of Enterobacterales, Coliforms, Pseudomonas spp., Vibrio spp., and S. aureus At D8 and D12 compared to the control. Taken together, these results indicate that OV50 can improve the microbiological safety, freshness, and quality of sardines.

Enhanced antimicrobial activity of lactic acid bacteria through genome shuffling and genetic variability among shuffled strains

In this investigation, lactic acid bacteria (LAB) isolated from milk were tested for their antibacterial properties and improved the antimicrobial activity of these isolates using genome shuffling. A total of sixty-one isolates were found in eleven samples, which were then tested using the agar diffusion method for their antibacterial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. Thirty-one strains exhibited antibacterial activity against at least one of the tested pathogens, with an inhibitory zone's diameter varying between 15.0 and 24.0 mm. Two isolates that showed the highest antimicrobial activity were identified as Lactobacillus plantarum CIP 103151 and Lactobacillus plantarum JCM 1149 according to 16S rRNA analysis. In the present study, applying genome shuffling approach significantly enhanced the antibacterial activity of L. plantarum. The initial populations were obtained via ultraviolet irradiation and were treated using the protoplast fusion method. The ideal condition for the production of protoplasts was 15 mg/ml of lysozyme and 10 μg/ml of mutanolysin. After two rounds of fusion, ten recombinants exhibited a significant increase in the inhibition zones versus S. aureus, S. typhimurium, P. aeruginosa, and E. coli, reaching up to 1.34, 1.31, 1.37, and 1.37-fold increase in inhibitory zone respectively. Random Amplified Polymorphic DNA results showed clear differences in DNA banding patterns among the wild strain of L. plantarum CIP 103151 and the three selected shuffled strains using primers 1283 & OPA09. On the other hand, no change was obtained using primers OPD03 neither among the wild strain and the three recombinant strains nor among the three shuffled strains.

Lactobacillus plantarum J9, a potential probiotic isolated from cereal/pulses based fermented batter for traditional Indian food and its microencapsulation

This work analyzed the probiotic properties of isolates from cereal-based Indian fermented food. The isolates were tested for lactic acid production, cell hydrophobicity, antibiotic sensitivity, sensitivity to acidic conditions, and increased salt concentration. This study also evaluated the ability of the probiotic isolates to ferment sugars and their antioxidant activity. The potential probiotic L. plantarum J9 isolated from jangri batter was encapsulated using 2.5% sodium alginate and CaCl2 by extrusion method with an encapsulation efficiency greater than 99%. After 2 h of incubation, in simulated gastric juice the encapsulated J9 cells reduced from 11.8 to 6.8 log10 CFU/ml however, free J9 cells reduced from 11.8 to 1.89 log10 CFU/ml. Similarly, encapsulated J9 cells reduced from 11.8 to 8.0 log10 CFU/ml but free J9 cells reduced from 11.6 to 0.890 log10 CFU/ml in simulated intestinal juice after 2 h incubation. The microencapsulation of L. plantarum J9 with alginate proves effective in delivering viable bacterial cells at required levels. Probiotic with antioxidant activity and antagonistic properties against food-borne pathogens is reported for the first time from jangri batter. The sodium alginate microencapsulation allows viable cells to reach a beneficial level, and hence this study aids in developing new probiotic products.

Antimicrobial Activities and Biopreservation Potential of Lactic Acid Bacteria (LAB) from Raw Buffalo (Bubalus bubalis) Milk

The aim of this study was to investigate the antimicrobial and biopreservation potential of lactic acid bacteria. The potential probiotic culture inhibited the growth of gram-positive and gram-negative foodborne pathogens in agar spot assay with inhibition zones ranging from 10 to 21 mm in diameter. The strains showed coaggregation capabilities ranging from 7 to 71% with tested food pathogens including Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica subsp. enterica serovar Typhimurium. The effect of cell-free supernatants on the release of 260 nm absorbing material, especially nucleic acids, was evaluated and indicated the antagonistic activity on foodborne pathogens, the highest being Lactobacillus paraplantarum against E. coli (3.77) and S. aureus (3.86) after 60 min. The effect of cell-free supernatant (CFS) on the growth of pathogens showed that Lactobacillus paraplantarum 11 and L. pentosus 93 had the highest inhibitory activity against tested strains. The biopreservation assay indicated that the potential probiotic strains Lactobacillus paraplantarum 11 (BT), Lactiplantibacillus plantarum 19, Lactobacillus pentosus 42, Limosilactobacillus fermentum 60, Lactobacillus pentosus 93, and Limosilactobacillus reuteri 112 were effective in reducing the Listeria monocytogenes population in raw buffalo milk. Complete Listeria monocytogenes inhibition was observed after 6-8 days. This study showed that probiotic LAB from buffalo milk have antimicrobial and biopreservation potential; these strains have the potential to be utilized as biopreservative agents in food products.

The effect of Lactobacillus with prebiotics on KPC-2-producing Klebsiella pneumoniae

Objectives

This study investigated the inhibitory effect of Lactobacillus spp. with prebiotics against Klebsiella pneumoniae carbapenemase-2 (KPC-2)-producing Klebsiella pneumoniae using both in vitro experiments and animal models.

Methods

Thirty-three Lactobacillus spp. strains were confirmed by 16S rDNA sequencing, and four different PFGE genotyped KPC-2-producing K. pneumoniae strains were selected for investigation. In vitro studies, including broth microdilution assays, changes in pH values in lactobacilli cultures with different prebiotics, time-kill tests of Lactobacillus spp. against KPC-2-producing K. pneumoniae and further in vivo Lactobacillus alone or in combination with prebiotics against KPC-2-producing K. pneumoniae in an animal model, were performed.

Results

The lower pH value of the cell-free supernatant was associated with a lower minimal inhibitory percentage of the Lactobacillus strain against KPC-2-producing K. pneumoniae. Furthermore, lactulose/isomalto-oligosaccharide/inulin and fructo-oligosaccharide can enhance the inhibitory effect of all 10⁷ CFU/ml Lactobacillus strains against KPC001. Three Lactobacillus strains (LYC1154, LYC1322, and LYC1511) that could be persistently detected in the stool were tested for their ability to reduce the amount of KPC001 in the feces individually or in combination. A significantly better effect in reducing the amount of KPC001 was observed for the combination of three different Lactobacillus species than for each of them alone. Furthermore, their inhibitory effect was enhanced after adding lactulose or isomalto-oligosaccharide (both p < 0.05).

Conclusion

This study demonstrates the inhibitory effect of probiotic Lactobacillus, including LYC1154, LYC1322, and LYC1511, with prebiotics such as lactulose or isomalto-oligosaccharide against the colonization of KPC-2-producing K. pneumoniae.

Efficacy of Lactobacillus animalis and Propionibacterium freudenreichii-Based Feed Additives in Reducing Salmonella-Associated Health and Performance Effects in Commercial Beef Calves

Salmonella enterica, which causes typhoid fever, is one of the most prevalent food-borne pathogens. Salmonellosis in cattle can greatly impact a producer’s income due to treatment costs, decreased productivity of the herd, and mortality due to disease. Current methods of treatment and prevention for salmonellosis consist of antibiotics and vaccinations, but neither of these options are perfect. Probiotics, categorized as antibiotic alternatives, are living microorganisms that are added to animal feeds in appropriate quantities in order to benefit health and productivity in adult and newborn livestock. The objective of this study was to demonstrate that Lactobacillus animalis and Propionibacterium freudenreichii, when used as a direct-fed microbial, was effective in reducing the adverse effects of experimentally induced Salmonella infection in beef calves. We conducted a single site efficacy study with masking using a randomized design comprising two groups of ten beef calves allocated to two treatment groups (control and probiotic). Procedures such as determining general health scores and body weight and collecting fecal samples were carried out following the experimental challenge of calves with Salmonella Typhimurium. The presence of at least one CFU of bacteria in feces was significantly higher among animals in the control than in the probiotic group, which was higher on days 0 to 7 than on days 8 to 14 (p = 0.012). Animals in the control group had a significantly higher presence of abnormal diarrhea scores than animals in the probiotic group (p < 0.001). Most notably, other health benefits in probiotic-fed group calves were obviously better than those for control calves and further substantiates the potential economic and health benefits of feeding effective probiotics.

In vitro and in vivo activity of Lactobacillus sakei L14 strain against Campylobacter jejuni DC3 strain

Introduction

Domestic poultry is a natural reservoir of Campylobacter, the host–pathogen interaction being predominantly asymptomatic. This study investigated whether chickens remain asymptomatic partly because of lactic acid bacteria (LAB).

Material and Methods

Campylobacter spp. and LAB were isolated from the gut of poultry chickens using enrichment and screening assays and were identified via rDNA sequencing. The C. jejuni DC3 isolate was grown in different cell-free supernatants (CFS) generated from a priority LAB isolate. An in vivo challenge involving the C. jejuni and LAB isolates using a chicken model was performed to confirm the in vitro findings.

Results

Twelve presumptive LAB isolates had anti-C. jejuni activity based on cross-streak and agar plug assays, with Lactobacillus sakei L14 isolate exhibiting the highest activity. Inhibition by L. sakei L14 CFS of the growth of C. jejuni occurred in a dose-dependent manner. Campylobacter jejuni DC3 inhibition was most evident in CFS harvested at 72 h and produced by co-culture with the pathogen. Neutralisation of the CFS abrogated the observed inhibition. Co-infection with C. jejuni DC3 and L. sakei L14 in vivo, however, failed to inhibit C. jejuni colonisation in chickens.

Conclusion

The results suggest that the anti-C. jejuni effect of L. sakei L14 in chickens may be due to mechanisms other than direct inhibition of growth.

Impact of pH and removed filtrate on E. coli regrowth and microbial community during storage of electro-dewatered biosolids

Residual biosolids can be land applied if they meet microbiological requirements at the time of application. Electro-dewatering technology is shown to reduce biosolids bacterial counts to detection limits with little potential for bacterial regrowth during incubations. Here, we investigated the impacts on Escherichia coli regrowth and microbial communities of biosolids pH, removed nutrients via the filtrate, and inhibitory compounds produced in electro-dewatered biosolids. Findings suggest pH as the primary mechanism impacting E. coli regrowth in electro-dewatered biosolids. Propidium monoazide treatments were effective at removing DNA from dead cells, based on the removal of obligate anaerobes observed after anaerobic incubation. Analyses of high throughput sequenced data showed lower alpha-diversities associated with electro-dewatering treatment and incubation time. Moreover, biosolids pH and incubation period were the main factors contributing to the variations in microbial community compositions after incubation. Results highlight the role of electro-dewatered biosolids' low pH on inhibiting the regrowth of culturable bacteria as well as reducing the microbial community variance.

Lactobacillus reuteri and Enterococcus faecium from Poultry Gut Reduce Mucin Adhesion and Biofilm Formation of Cephalosporin and Fluoroquinolone-Resistant Salmonella enterica

Non-typhoidal Salmonella (NTS) can cause infection in poultry, livestock, and humans. Although the use of antimicrobials as feed additives is prohibited, the previous indiscriminate use and poor regulatory oversight in some parts of the world have resulted in increased bacterial resistance to antimicrobials, including cephalosporins and fluoroquinolones, which are among the limited treatment options available against NTS. This study aimed to isolate potential probiotic lactic acid bacteria (LAB) strains from the poultry gut to inhibit fluoroquinolone and cephalosporin resistant MDR Salmonella Typhimurium and S. Enteritidis. The safety profile of the LAB isolates was evaluated for the hemolytic activity, DNase activity, and antibiotic resistance. Based on the safety results, three possible probiotic LAB candidates for in vitro Salmonella control were chosen. Candidate LAB isolates were identified by 16S rDNA sequencing as Lactobacillus reuteri PFS4, Enterococcus faecium PFS13, and Enterococcus faecium PFS14. These strains demonstrated a good tolerance to gastrointestinal-related stresses, including gastric acid, bile, lysozyme, and phenol. In addition, the isolates that were able to auto aggregate had the ability to co-aggregate with MDR S. Typhimurium and S. Enteritidis. Furthermore, LAB strains competitively reduced the adhesion of pathogens to porcine mucin Type III in co-culture studies. The probiotic combination of the selected LAB isolates inhibited the biofilm formation of S. Typhimurium FML15 and S. Enteritidis FML18 by 90% and 92%, respectively. In addition, the cell-free supernatant (CFS) of the LAB culture significantly reduced the growth of Salmonella in vitro. Thus, L. reuteri PFS4, E. faecium PFS13, and E. faecium PFS 14 are potential probiotics that could be used to control MDR S. Typhimurium and S. Enteritidis in poultry. Future investigations are required to elucidate the in vivo potential of these probiotic candidates as Salmonella control agents in poultry and animal feed.

Anti-inflammatory Effect of Probiotic Limosilactobacillus reuteri KUB-AC5 Against Salmonella Infection in a Mouse Colitis Model

Acute non-typhoidal salmonellosis (NTS) caused by Salmonella enterica Typhimurium (STM) is among the most prevalent of foodborne diseases. A global rising of antibiotic resistance strains of STM raises an urgent need for alternative methods to control this important pathogen. Major human food animals which harbor STM in their gut are cattle, swine, and poultry. Previous studies showed that the probiotic Limosilactobacillus (Lactobacillus) reuteri KUB-AC5 (AC5) exhibited anti-Salmonella activities in chicken by modulating gut microbiota and the immune response. However, the immunobiotic effect of AC5 in a mammalian host is still not known. Here, we investigated the anti-Salmonella and anti-inflammatory effects of AC5 on STM infection using a mouse colitis model. Three groups of C57BL/6 mice (prophylactic, therapeutic, and combined) were fed with 10⁹ colony-forming units (cfu) AC5 daily for 7, 4, and 11 days, respectively. Then, the mice were challenged with STM compared to the untreated group. By using a specific primer pair, we found that AC5 can transiently colonize mouse gut (colon, cecum, and ileum). Interestingly, AC5 reduced STM gut proliferation and invasion together with attenuated gut inflammation and systemic dissemination in mice. The decreased STM numbers in mouse gut lumen, gut tissues, and spleen possibly came from longer AC5 feeding duration and/or the combinatorial (direct and indirect inhibitory) effect of AC5 on STM. However, AC5 attenuated inflammation (both in the gut and in the spleen) with no difference between these three approaches. This study demonstrated that AC5 confers both direct and indirect inhibitory effects on STM in the inflamed gut.

Effect of Echinostoma caproni on Presumptive Lactic Acid Bacteria Abundance and Salmonella enterica Serovar Typhimurium Colonization in the Mouse Gut

Co-infections of mammalian hosts with intestinal helminths and bacterial pathogens are common, especially in areas with inadequate sanitation. Interactions between co-infecting species and host microbiota can cause significant changes in host immunity, disease severity, and pathogen transmission, requiring unique treatment for each case. A greater understanding of the influences of parasite-bacteria co-infections will improve diagnosis and therapeutic approaches to control infectious diseases. To study the influence of the trematode parasite Echinostoma caproni on commensal and pathogenic bacteria in the mouse gut, we examined the abundance of intestinal lactic acid bacteria and Salmonella enterica serovar Typhimurium in control mice not exposed to E. caproni (P-) or S. Typhimurium (S-), E. caproni-infected (P+S-), S. Typhimurium-infected (P-S+), and E. caproni-S. Typhimurium co-infected (P+S+) mice, and determined bacterial burdens in the livers and spleens of the P-S+ and P+S+ mice. We also examined a subset of P+S- and P+S+ mice for survival and the relative location of E. caproni in the small intestine. The numbers of presumptive lactic acid bacteria were significantly higher in the P+S+ and P-S+ mice compared to the uninfected mice, and S. Typhimurium colonization in the liver and spleen was significantly reduced in the P+S+ mice compared to the P-S+ mice. Echinostoma caproni were located anteriorly in the intestine of P+S- mice, while in the P+S+ mice, the parasites were distributed more posteriorly. Survival of E. caproni was unaffected in either group. The results of our study suggest that E. caproni facilitates a higher abundance of presumptive lactic acid bacteria in the mouse intestine and reduces colonization of S. Typhimurium in the liver and spleen of the co-infected host.

In vitro properties of potential probiotic lactic acid bacteria originating from Ghanaian indigenous fermented milk products

Fermented milk products are a major source of health-promoting microorganisms known as probiotics. To characterize the probiotic properties of lactic acid bacteria isolated from Ghanaian traditionally fermented milk, thirty (30) isolates comprising Enterococcus faecium (1), Lactobacillus fermentum (14), Lb. plantarum (2) and Pediococcus acidilactici (13) identified by 16S rRNA gene sequencing, were tested for survival at low pH (2.5) and bile salts (0.3% (w/v)), hydrophobicity, co-aggregation, auto-aggregation and antimicrobial activities against selected pathogens. Safety of potential probiotic bacteria was assessed by hemolytic activity on blood agar and susceptibility to nine different antibiotics. Majority (90%) of the strains showed survival rates above 80% at pH (2.5) and in bile salts (0.3% (w/v)). Hydrophobicity ranged from 5 to 61% while cell auto-aggregation ranged from 41 to 80% after 24 h. Co-aggregation with E. coli (3.7-43.9%) and S. Typhimurium (1.3-49.5%) were similar for the LAB strains at 24 h. Cell- free supernatants of all LAB strains inhibited E. coli while S. Typhimurium was not sensitive to cell-free supernatants of five Pd. acidilactici strains: OS24h20, OS18h3, OY9h19, OS9h8 and 24NL38. None of the LAB strains showed β-hemolysis but 38% of strains showed α-hemolysis. Susceptibilities to antibiotics were strain-specific; only four strains, two Lb. fermentum and two Pd. acidilactici were susceptible to all nine antibiotics tested. Based on high survival rates in bile salts, low pH and generally good hydrophobicity, auto-aggregation, co-aggregation and inhibitory activities, 15 out of 30 strains tested were considered qualified candidates for development of probiotic cultures for fermented milk products in sub-Saharan Africa.

A combination of three probiotic strains for treatment of acute diarrhoea in hospitalised children: an open label, randomised controlled trial

Acute diarrhoea continues to be a leading cause of morbidity, hospitalisation, and mortality worldwide, and probiotics have been proposed as a complementary therapy in the treatment of acute diarrhoea. The goal of this study is to assess the efficacy and safety of three combined probiotic strains, Bifidobacterium lactis Bi-07, Lactobacillus rhamnosus HN001, and Lactobacillus acidophilus NCFM, as an adjunct to rehydration therapy in treatment of acute watery diarrhoea in hospitalised children. Eligible diarrheal children were randomised into intervention group (IG, n=96, conventional treatment for diarrhoea in combination with probiotics) and control group (CG, n=98, conventional treatment for diarrhoea without probiotics). The primary assessments of this study were duration of diarrhoea and hospital stay and improvement in diarrhoea symptoms. Significantly more children in the IG showed improvements in diarrhoea (defined as a decrease of stool frequency to no more than four times per day and an improved stool consistency within 24-48 h after the treatment) than those in the CG (96.9 vs 79.6%, P<0.05). Children supplemented with the mixed strains had a 22.5 h shorter (121.4±13.7 h vs 143.9±19.8 h) mean duration of diarrhoea and 1.2 d shorter hospital stays (5.1±1.2 d vs 6.3±1.4 d) than children only receiving the rehydration therapy (P<0.05). The prevalence of constipation of children in the IG (3.1%) was markedly lower (P<0.05) than that of children in the CG (13.3%) after treatment. In conclusion, the mixture of three probiotic strains given to children aged 1-3 years resulted in shorter durations of diarrhoea and hospitalisation and a higher percentage of improved children.

Antimicrobial ability and mechanism analysis of Lactobacillus species against carbapenemase-producing Enterobacteriaceae

BACKGROUND

This study aims to investigate the antimicrobial ability and mechanism analysis of Lactobacillus species against carbapenemase-producing Enterobacteriaceae (CPE).

METHODS

Five Lactobacillus spp. strains and 18 CPE clinical isolates were collected. Their anti-CPE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test. Finally, the specific anti-CPE mechanism, especially for the effect of organic acids was determined using broth microdilution method.

RESULTS

All of five Lactobacilli isolates displayed the potent activity against most CPE isolates with mean zones of inhibition ranging 10.2-21.1 mm. The anti-CPE activity was not affected by heating, catalase, and proteinase treatment. Under the concentration of 50% LUC0180 cell-free supernatant (CFS), lactic acid, and mix acid could totally inhibit the growth of carbapenem-resistant Klebsiella pneumoniae (CPE0011), and acetic acid could inhibit 67.8%. In contrast, succinic acid and citric acid could not inhibit the growth of CPE0011. While we decreased the concentration to 25%, only lactic acid and mix acid displayed 100% inhibition. In contrast, succinic acid, citric acid and acetic acid did not show any inhibitory effect.

CONCLUSIONS

Lactobacillus strains exhibit potent anti-CPE activity, and lactic acid produced by Lactobacillus strains is the major antimicrobial mechanism.

Antimicrobial Activity of Lactobacillus Species Against Carbapenem-Resistant Enterobacteriaceae

Objective

This study aims to identify suitable lactobacilli that have anti-carbapenem-resistant Enterobacteriaceae (CRE) activity with in vitro tolerance to pepsin and bile salts.

Methods

Fifty-seven Lactobacillus spp. strains encompassing nine species were collected for investigation. Their viabilities in the presence of pepsin and bile salts were tested using tolerance tests. Their anti-CRE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test.

Results

Of the 57 Lactobacillus isolates collected, 31 had a less than 2-log reduction in their viability in both pepsin and bile salt tolerance tests. Of these 31 isolates, 5 (LUC0180, LUC0219, LYC0289, LYC0413, and LYC1031) displayed the greatest anti-CRE activity with a CRE zone of inhibition greater than 15 mm in agar well diffusion assays. The minimal inhibitory percentages of supernatants from these five strains against CREs ranged from 10 to 30%. With the exception of LUC0180, which had a minimal bactericidal percentage ≥ 40%, the bactericidal percentage of all the strains ranged from 20 to 40%. The inhibitory effect of the cell-free culture supernatants from these Lactobacillus strains did not change after heating but was abolished as the pH changed to 7.0. After a 24-h incubation, five of the Lactobacillus strains at a concentration of 10⁸ CFU/ml totally inhibited the growth of carbapenem-resistant Escherichia coli (CRE316) and Klebsiella pneumoniae (CRE632). After a 48-h incubation, the growth of CRE316 was completely inhibited under each concentration of lactobacilli based on time-kill test. Furthermore, when the concentration of lactobacilli was at 10⁸ CFU/ml, the decline in pH was faster than at other concentrations.

Conclusion

Some Lactobacillus strains exhibit anti-CRE activity, which suggests potential applications for controlling or preventing CRE colonization or infection.

Microbiota stability in healthy individuals after single-dose lactulose challenge-A randomized controlled study

BACKGROUND AND AIMS

Lactulose is a common food ingredient and widely used as a treatment for constipation or hepatic encephalopathy and a substrate for hydrogen breath tests. Lactulose is fermented by the colon microbiota resulting in the production of hydrogen (H2). H2 is a substrate for enteropathogens including Salmonella Typhimurium (S. Typhimurium) and increased H2 production upon lactulose ingestion might favor the growth of H2-consuming enteropathogens. We aimed to analyze effects of single-dose lactulose ingestion on the growth of intrinsic Escherichia coli (E. coli), which can be efficiently quantified by plating and which share most metabolic requirements with S. Typhimurium.

METHODS

32 healthy volunteers (18 females, 14 males) were recruited. Participants were randomized for single-dose ingestion of 50 g lactulose or 50 g sucrose (controls). After ingestion, H2 in expiratory air and symptoms were recorded. Stool samples were acquired at days -1, 1 and 14. We analyzed 16S microbiota composition and abundance and characteristics of E. coli isolates.

RESULTS

Lactulose ingestion resulted in diarrhea in 14/17 individuals. In 14/17 individuals, H2-levels in expiratory air increased by ≥20 ppm within 3 hours after lactulose challenge. H2-levels correlated with the number of defecations within 6 hours. E. coli was detectable in feces of all subjects (2 x 10(2)-10(9) CFU/g). However, the number of E. coli colony forming units (CFU) on selective media did not differ between any time point before or after challenge with sucrose or lactulose. The microbiota composition also remained stable upon lactulose exposure.

CONCLUSION

Ingestion of a single dose of 50 g lactulose does not significantly alter E. coli density in stool samples of healthy volunteers. 50 g lactulose therefore seems unlikely to sufficiently alter growth conditions in the intestine for a significant predisposition to infection with H2-consuming enteropathogens such as S. Typhimurium (www.clinicaltrials.gov NCT02397512).

Expanding the reach of probiotics through social enterprises

The rapid rise in microbiome and probiotic science has led to estimates of product creation and sales exceeding $50 billion within five years. However, many people do not have access to affordable products, and regulatory agencies have stifled progress. The objective of a discussion group at the 2017 meeting of the International Scientific Association for Probiotics and Prebiotics was to identify mechanisms to confer the benefits of probiotics to a larger portion of the world’s population. Three initiatives, built around fermented food, were discussed with different methods of targeting populations that face enormous challenges of malnutrition, infectious disease, poverty and violent conflict. As new candidate probiotic strains emerge, and the market diversifies towards more personalised interventions, manufacturing processes will need to evolve. Information dissemination through scientific channels and social media is projected to provide consumers and healthcare providers with rapid access to clinical results, and to identify the nearest location of sites making new and affordable probiotic food and supplements. This rapid translation of science to individual well-being will not only expand the beneficiaries of probiotics, but also fuel new social enterprises and economic business models.

Characterization and anti-salmonella activities of lactic acid bacteria isolated from cattle faeces

Background

Non typhoidal salmonellosis is one of the neglected zoonoses in most African countries. The use of sub-therapeutic doses of antibiotics as animal growth promoter enhances the emergence and dissemination of antimicrobial resistance in bacteria with food animal reservoirs and may also results in antibiotics residue in animal products. One promising alternative to antibiotics in animal feed is Lactic Acid Bacteria (LAB) as probiotics. This study was carried out to determine the anti-salmonella activities and suitability of LAB isolated from cattle faeces in Nigeria as potential probiotics in cattle feed.

Method

The test Salmonella enterica spp strains and LAB were isolated from cattle faeces and identified by MALDI-TOF MS and partial sequencing of 16S rRNA genes respectively. The anti-salmonella activities of the isolated LAB in co-culture, cell-free supernatant, inhibition of growth by viable LAB cells and quantification of organic acids were determined by standard techniques. The ability of the LAB strains to withstand gastric conditions, antibiotic susceptibility and their haemolytic ability on blood agar were also determined.

Results

A total of 88 LAB belonging to 15 species were isolated and identified from cattle faeces. The most abundant species were Streptococcus infantarius (26), Enterococcus hirae (12), Lactobacillus amylovorus (10), Lactobacillus mucosae (10) and Lactobacillus ingluviei (9). Most of the LAB strains showed good anti-salmonella activities against the test Salmonella enterica spp. with 2 Lactobacillus strains; Lactobacillus amylovorus C94 and Lactobacillus salivarius C86 exhibiting remarkable anti-salmonella activities with total inhibition of Salmonella spp after 18 hours of co-incubation. The selected strains were able to survive simultaneous growth at pH 3 and 7% bile concentration and are non hemolytic.

Conclusion

This study reports the vast diversity of culturable LAB in cattle faeces from Nigeria and their putative in-vitro antibacterial activity against Salmonella enterica spp isolated from cattle. Lactobacillus amylovorus C94 and Lactobacillus salivarius C86 demonstrated promising probiotic potentials in-vitro and will be further tested in-vivo in animal field trial.

Characterization of Bacteria in Nigerian Yogurt as Promising Alternative to Antibiotics in Gastrointestinal Infections

Gastrointestinal infections are endemic in Nigeria and several factors contribute to their continual survival, including bacterial resistance to commonly used antibiotics. Nigerian yogurts do not include probiotics, and limited information is available about the antimicrobial properties of the fermenters in the yogurt against gastrointestinal pathogens. Therefore, the antimicrobial potentials of bacteria in Nigeria-produced yogurts against intestinal pathogens were investigated in this study. Viable counts of lactic acid bacteria (LAB) in 15 brands of yogurt were enumerated and the bacteria identified by partial sequencing of 16S rRNA gene. Susceptibility of the gastrointestinal pathogens (Salmonella, Shigella and E. coli ) to antibiotics by disc diffusion method, to viable LAB by the agar overlay method, and to the cell-free culture supernatant (CFCS) of the LAB were investigated. Co-culture analysis of LAB and pathogens were also done. Viable counts of 1.5 × 10¹¹ cfu/ml were observed in some yogurt samples. Two genera were identified: Lactobacillus (70.7%) and Acetobacter (29.3%). The Lactobacillus species reduced multidrug-resistant gastrointestinal pathogens by 4 to 5 log while the zones of inhibition ranged between 11 and 23. The Lactobacillus and Acetobacter strains examined displayed good activities against the multidrug-resistant tested pathogens. This is the first report of antimicrobial activities of acetic acid bacteria isolated from yogurt in Nigeria.

A consumer's guide for probiotics: 10 golden rules for a correct use

Probiotics are used all over the world as their beneficial effects on the human organism have been widely demonstrated. Certain probiotics can down-regulate production of pro-inflammatory cytokines and promote intestinal epithelial barrier functions, increasing an anti-inflammatory response and contributing to the host's overall health. The main mechanisms by which probiotic microorganisms can interact with the host are by modulating the immune system and the epithelial cell functions and interacting with intestinal gut microbiota. To date, hundreds of different microorganisms are used for the formulation of numerous probiotic products; therefore, it is very difficult to choose the best probiotic product for specific or more general needs. Therefore, physicians are getting more and more confused due to the high number of commercial products which are often lacking healthy effects on the host. Therefore, the aim of this paper is to demonstrate the main characteristics that probiotic microorganisms and products should possess to have a positive impact on the host's health. To this purpose, this review suggests "10 golden rules" or "commandments" that clinicians should follow to properly select the optimal probiotic product and avoid misidentifications, mislabelling and "pie in the sky" stories.

Antagonistic and Quantitative Assessment of Indigenous Lactic acid Bacteria in Different Varieties of Ogi against Gastrointestinal Pathogens

Introduction

Ogi is a popular fermented cereal gruel consumed mainly in the western part of Nigeria. Traditionally, uncooked Ogi is normally administered to diarrhoea patients to reduce the frequency of stooling. This study was therefore undertaken to identify, quantify and determine the antimicrobial properties of lactic acid bacteria (LAB) isolated from Ogi.

Methods

The Ogi samples (Yellow, white, sorghum) were obtained from different market in Ibadan, Nigeria and Ogi control (cooked, uncooked and Omidun) were prepared with the viable counts of bacteria monitored over 5 days period. LAB were isolated from the varieties and identified by partial sequencing of 16S rRNA gene. The antimicrobial activities of the cell free supernatant (CFS) and the viable cells of the isolated LAB against Escherichia coli EC004, Salmonella sp. SS11, Shigella sp. SS10 were investigated by agar diffusion assay, agar overlay method, and coculture growth studies.

Results

Omidun had the highest LAB count while cooked ogi has the lowest LAB count. Weissella paramesenteroides , L. brevis, L. rossiae, L. fermentum, L. plantarum, Acetobacter pasteurianus, Paenibacillus sp. and Bacillus sp. were isolated from Ogi in this study. Large zone of inhibition (11≤x≤20) was observed with CFS against Salmonella sp. SS11 and Shigella sp. SS10 and also the overlay method. Coculture studies of Weissella paramesenteroides, Lactobacillus fermentum, and L. plantarum with Salmonella sp. SS11 showed a 5-8 log reduction of the pathogens' growth after 24 hours as compared with the control.

Conclusion

Ogi and its contents have antimicrobial properties against pathogenic organisms.

Influence of probiotics, included in peanut butter, on the fate of selected Salmonella and Listeria strains under simulated gastrointestinal conditions

AIMS

This study observed the behaviour of probiotics and selected bacterial pathogens co-inoculated into peanut butter during gastrointestinal simulation.

METHODS AND RESULTS

Peanut butter homogenates co-inoculated with Salmonella/Listeria strains (5 log CFU ml(-1) ) and lyophilized or cultured probiotics (9 log CFU ml(-1) ) were exposed to simulated gastrointestinal conditions for 24 h at 37°C. Sample pH, titratable acidity and pathogen populations were determined. Agar diffusion assay was performed to assess the inhibitory effect of probiotic culture supernatants with either natural (3·80 (Lactobacillus), 3·78 (Bifidobacteirum) and 5·17 (Streptococcus/Lactococcus)) or neutralized (6·0) pH. Antibacterial effect of crude bacteriocin extracts were also evaluated against the pathogens. After 24 h, samples with probiotics had lower pH and higher titratable acidity than those without probiotics. The presence of probiotics caused a significant reduction (P < 0·05) in pathogen populations. Supernatants of Bifidobacterium and Lactobacillus cultures inhibited pathogen growth; however, the elevation of pH diminished their antibacterial activities. Crude bacteriocin extracts had a strain-specific inhibitory effect only towards Listeria monocytogenes.

CONCLUSION

Probiotics in 'peanut butter' survived simulated gastrointestinal conditions and inhibited the growth of Salmonella/Listeria.

SIGNIFICANCE AND IMPACT OF THE STUDY

Peanut butter is a plausible carrier to deliver probiotics to improve the gastrointestinal health of children in developing countries.

Effect of fermented broth from lactic acid bacteria on pathogenic bacteria proliferation

In this study, the effect that 5 fermented broths of lactic acid bacteria (LAB) strains have on the viability or proliferation and adhesion of 7 potentially pathogenic microorganisms was tested. The fermented broth from Lactococcus lactis C660 had a growth inhibitory effect on Escherichia coli K92 that reached of 31%, 19% to Pseudomonas fluorescens, and 76% to Staphylococcus epidermidis. The growth of Staph. epidermidis was negatively affected to 90% by Lc. lactis 11454 broth, whereas the growth of P. fluorescens (25%) and both species of Staphylococcus (35% to Staphylococcus aureus and 76% to Staph. epidermidis) were inhibited when they were incubated in the presence of Lactobacillus casei 393 broth. Finally, the fermented broth of Lactobacillus rhamnosus showed an inhibitory effect on growth of E. coli K92, Listeria innocua, and Staph. epidermidis reached values of 12, 28, and 76%, respectively. Staphylococcus epidermidis was the most affected strain because the effect was detected from the early stages of growth and it was completely abolished. The results of bacterial adhesion revealed that broths from Lc. lactis strains, Lactobacillus paracasei, and Lb. rhamnosus caused a loss of E. coli K92 adhesion. Bacillus cereus showed a decreased of adhesion in the presence of the broths of Lc. lactis strains and Lb. paracasei. Listeria innocua adhesion inhibition was observed in the presence of Lb. paracasei broth, and the greatest inhibitory effect was registered when this pathogenic bacterium was incubated in presence of Lc. lactis 11454 broth. With respect to the 2 Pseudomonas, we observed a slight adhesion inhibition showed by Lactobacillus rhamnosus broth against Pseudomonas putida. These results confirm that the effect caused by the different LAB assayed is also broth- and species-specific and reveal that the broth from LAB tested can be used as functional bioactive compounds to regulate the adhesion and biofilm synthesis and ultimately lead to preventing food and clinical contamination and colonization of E. coli K92, B. cereus, and Ls. innocua.

Pichia pastoris X-33 has probiotic properties with remarkable antibacterial activity against Salmonella Typhimurium

Probiotics are live microorganisms which are beneficial for the host when ingested at high enough concentrations. The methylotrophic yeast Pichia pastoris is widely used as heterologous protein production platform. However, its use as probiotic is poorly studied. The objective of this study was to evaluate some probiotic properties of the P. pastoris strain X-33 wild type. The resistance to in vitro and in vivo gastrointestinal conditions, stability in feed, safety, and antibacterial activity against Salmonella Typhimurium were evaluated. The yeast remained viable and persisted at appropriate concentration in the diet for at least 2 months, survived the stresses of the gastrointestinal tract in vitro and in vivo, caused no behavioral changes or lesions when administered to mice, inhibited the growth of S. Typhimurium in culture media, and reduced adhesion of the bacteria to the intestinal cells HCT-116. In the challenge experiment with a LD50 of virulent S. Typhimurium strain, mice supplemented with the yeast had a higher survival rate (50 % when administered by gavage and 80 % via the diet, compared with 20 and 50 %, respectively, in the control group). In addition, the S. Typhimurium concentration in the intestine of the surviving mice was lower; the score of intestinal lesions, lower; and the pathogen, not detected in the liver, spleen, and feces when compared to the control group (p < 0.05). It was concluded that the yeast Pichia pastoris X-33 has probiotic properties with remarkable antibacterial activity against S. Typhimurium.

Cocktails of probiotics pre-adapted to multiple stress factors are more robust under simulated gastrointestinal conditions than their parental counterparts and exhibit enhanced antagonistic capabilities against Escherichia coli and Staphylococcus aureus

Background

The success of the probiotics in delivery of health benefits depends on their ability to withstand the technological and gastrointestinal conditions; hence development of robust cultures is critical to the probiotic industry. Combinations of probiotic cultures have proven to be more effective than the use of single cultures for treatment and prevention of heterogeneous diseases. We investigated the effect of pre- adaptation of probiotics to multiple stresses on their stability under simulated gastrointestinal conditions and the effect of their singular as well as their synergistic antagonistic effect against selected enteric pathogens.

Methods

Probiotic cultures were inoculated into MRS broth adjusted to pH 2 and incubated for 2 h at 37°C. Survivors of pH 2 were subcultured into 2% bile acid for 1 h at 37°C. Cells that showed growth after exposure to 2% bile acid for 1 h were finally inoculated in fresh MRS broth and incubated at 55°C for 2 h. The cells surviving were then used as stress adapted cultures. The adapted cultures were exposed to simulated gastrointestinal conditions and their non- adapted counterparts were used to compare the effects of stress adaptation. The combination cultures were tested for their antipathogenic effects on Escherichia coli and Staphylococcus aureus.

Results

Acid and bile tolerances of most of the stress-adapted cells were higher than of the non-adapted cells. Viable counts of all the stress-adapted lactobacilli and Bifidobacterium longum LMG 13197 were higher after sequential exposure to simulated gastric and intestinal fluids. However, for B. longum Bb46 and B. bifidum LMG 13197, viability of non-adapted cells was higher than for adapted cells after exposure to these fluids. A cocktail containing L. plantarum + B. longum Bb46 + B. longum LMG 13197 best inhibited S. aureus while E. coli was best inhibited by a combination containing L. acidophilus La14 150B + B. longum Bb46 + B. bifidum LMG 11041. A cocktail containing the six non- adapted cultures was the least effective in inhibiting the pathogens.

Conclusion

Multi-stress pre-adaptation enhances viability of probiotics under simulated gastrointestinal conditions; and formulations containing a mixture of multi stress-adapted cells exhibits enhanced synergistic effects against foodborne pathogens.

Anti-obesity effects of gut microbiota are associated with lactic acid bacteria

The prevalence of obesity is rapidly becoming endemic in industrialized countries and continues to increase in developing countries worldwide. Obesity predisposes people to an increased risk of developing metabolic syndrome. Recent studies have described an association between obesity and certain gut microbiota, suggesting that gut microbiota might play a critical role in the development of obesity. Although probiotics have many beneficial health effects in humans and animals, attention has only recently been drawn to manipulating the gut microbiota, such as lactic acid bacteria (LAB), to influence the development of obesity. In this review, we first describe the causes of obesity, including the genetic and environmental factors. We then describe the relationship between the gut microbiota and obesity, and the mechanisms by which the gut microbiota influence energy metabolism and inflammation in obesity. Lastly, we focus on the potential role of LAB in mediating the effects of the gut microbiota in the development of obesity.

The Dynamic Interactions between Salmonella and the Microbiota, within the Challenging Niche of the Gastrointestinal Tract

Understanding how Salmonella species establish successful infections remains a foremost research priority. This gastrointestinal pathogen not only faces the hostile defenses of the host's immune system, but also faces fierce competition from the large and diverse community of microbiota for space and nutrients. Salmonella have solved these challenges ingeniously. To jump-start growth, Salmonella steal hydrogen produced by the gastrointestinal microbiota. Type 3 effector proteins are subsequently secreted by Salmonella to trigger potent inflammatory responses, which generate the alternative terminal electron acceptors tetrathionate and nitrate. Salmonella exclusively utilize these electron acceptors for anaerobic respiration, permitting metabolic access to abundant substrates such as ethanolamine to power growth blooms. Chemotaxis and flagella-mediated motility enable the identification of nutritionally beneficial niches. The resulting growth blooms also promote horizontal gene transfer amongst the resident microbes. Within the gastrointestinal tract there are opportunities for chemical signaling between host cells, the microbiota, and Salmonella. Host produced catecholamines and bacterial autoinducers form components of this chemical dialogue leading to dynamic interactions. Thus, Salmonella have developed remarkable strategies to initially shield against host defenses and to transiently compete against the intestinal microbiota leading to successful infections. However, the immunocompetent host is subsequently able to reestablish control and clear the infection.

Physiological Characteristics and Production of Folic Acid of Lactobacillus plantarum JA71 Isolated from Jeotgal, a Traditional Korean Fermented Seafood

Folic acid, one of the B group of vitamins, is an essential substance for maintaining the functions of the nervous system, and is also known to decrease the level of homocysteine in plasma. Homocysteine influences the lowering of the cognitive function in humans, and especially in elderly people. In order to determine the strains with a strong capacity to produce folic acid, 190 bacteria were isolated from various kinds of jeotgal and chungkuk-jang. In our test experiment, JA71 was found to contain 9.03μg/mL of folic acid after 24 h of incubation in an MRS broth. This showed that JA71 has the highest folic acid production ability compared to the other lactic acid bacteria that were isolated. JA71 was identified as Lactobacillus plantarum by the result of API carbohydrate fermentation pattern and 16s rDNA sequence. JA71 was investigated for its physiological characteristics. The optimum growth temperature of JA71 was 37℃, and the cultures took 12 h to reach pH 4.4. JA71 proved more sensitive to bacitracin when compared with fifteen different antibiotics, and showed most resistance to neomycin and vancomycin. Moreover, it was comparatively tolerant of bile juice and acid, and displayed resistance to Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus with restraint rates of 60.4%, 96.7%, and 76.2%, respectively. These results demonstrate that JA71 could be an excellent strain for application to functional products.

Phenotypic and genotypic characterization of some lactic Acid bacteria isolated from bee pollen: a preliminary study

In the present work, five hundred and sixty-seven isolates of lactic acid bacteria were recovered from raw bee pollen grains. All isolates were screened for their antagonistic activity against both Gram-positive and Gram-negative pathogenic bacteria. Neutralized supernatants of 54 lactic acid bacteria (LAB) cultures from 216 active isolates inhibited the growth of indicator bacteria. They were phenotypically characterized, based on the fermentation of 39 carbohydrates. Using the simple matching coefficient and unweighted pair group algorithm with arithmetic averages (UPGMA), seven clusters with other two members were defined at the 79% similarity level. The following species were characterized: Lactobacillus plantarum, Lactobacillus fermentum, Lactococcus lactis, Pediococcus acidilactici, Pediococcus pentosaceus, and unidentified lactobacilli. Phenotypic characteristics of major and minor clusters were also identified. Partial sequencing of the 16S rRNA gene of representative isolates from each cluster was performed, and ten strains were assigned to seven species: Lactobacillus plantarum, Lactobacillus fermentum, Lactococcus lactis, Lactobacillus ingluviei, Pediococcus pentosaceus, Lactobacillus acidipiscis and Weissella cibaria. The molecular method used failed to determine the exact taxonomic status of BH0900 and AH3133.

Antagonistic activity of Lactobacillus isolates against Salmonella typhi in vitro

Background. Enteric fever is a global health problem, and rapidly developing resistance to various drugs makes the situation more alarming. The potential use of Lactobacillus to control typhoid fever represents a promising approach, as it may exert protective actions through various mechanisms. Methods. In this study, the probiotic potential and antagonistic activities of 32 Lactobacillus isolates against Salmonella typhi were evaluated. The antimicrobial activity of cell free supernatants of Lactobacillus isolates, interference of Lactobacillus isolates with the Salmonella adherence and invasion, cytoprotective effect of Lactobacillus isolates, and possibility of concurrent use of tested Lactobacillus isolates and antibiotics were evaluated by testing their susceptibilities to antimicrobial agents, and their oxygen tolerance was also examined. Results. The results revealed that twelve Lactobacillus isolates could protect against Salmonella typhi infection through interference with both its growth and its virulence properties, such as adherence, invasion, and cytotoxicity. These Lactobacillus isolates exhibited MIC values for ciprofloxacin higher than those of Salmonella typhi and oxygen tolerance and were identified as Lactobacillus plantarum. Conclusion. The tested Lactobacillus plantarum isolates can be introduced as potential novel candidates that have to be subjected for in vivo and application studies for treatment and control of typhoid fever.

Toward an Alternative Therapeutic Approach for Skin Infections: Antagonistic Activity of Lactobacilli Against Antibiotic-Resistant Staphylococcus aureus and Pseudomonas aeruginosa

The wide spread of antimicrobial resistance has urged the need of alternative therapeutic approach. In this context, probiotic lactobacilli have been reported for the prevention and treatment of many gastrointestinal and urogenital infections. However, very little is known about their antagonistic activity against skin pathogens. Accordingly, the present study aimed to investigate the potential of lactobacilli to interfere with pathogenesis features of two antibiotic-resistant skin pathogens, namely methicillin-resistant Staphylococcus aureus and multiple-resistant Pseudomonas aeruginosa. A total of 49 lactobacilli were recovered, identified and tested for their antagonistic activities against the aforementioned pathogens. Of these, eight isolates were capable of blocking the adherence of pathogens to mammalian cells independent of the skin pathogen tested or model adopted. Moreover, three Lactobacillus isolates (LRA4, LC2 and LR5) effectively prevented the pathogen internalization into epithelial cells in addition to potentiating phagocyte-mediated pathogen killing. Interestingly, the lactobacilli LC2, LF9 and LRA4 markedly inhibited the growth of P. aeruginosa and S. aureus isolates in coculture experiments. Besides, the lactobacilli LRA4, LC2, LR5 and LF9 have counteracted pathogen cytotoxicity. Taken together, the present study revealed some inhibitory activities of lactobacilli against two antibiotic-resistant skin pathogens. Moreover, it revealed two lactobacilli, namely LC2 and LRA4, with antagonistic capacity against different virulence determinants of skin pathogens. These lactobacilli are considered promising probiotic candidates that may represent an alternative therapeutic approach for skin infections.

Bifidobacterium infantis 35624 protects against salmonella-induced reductions in digestive enzyme activity in mice by attenuation of the host inflammatory response

OBJECTIVES:

Salmonella-induced damage to the small intestine may decrease the villi-associated enzyme activity, causing malabsorption of nutrients and diarrhea, and thus contribute to the symptoms of infection. The objective of this study was to determine the mechanism by which different doses and durations of Salmonella infection and lipopolysaccharide (LPS) affect brush border enzyme activity in the mouse, and to determine if the probiotic Bifidobacterium longum subspecies infantis 35624 could attenuate the intestinal damage.

METHODS:

BALB/c mice were challenged with Salmonella enterica serovar Typhimurium UK1 at various doses (10²–10⁸ colony-forming unit (CFU)) and durations (10⁶ CFU for 1–6 days). Mice were also treated with B. longum subsp. infantis 35624 for 2 weeks before and during a 6-day S. Typhimurium challenge (10⁶ CFU), or before injection of LPS. The small intestine was assessed for morphological changes, mRNA expression of cytokines, and activity of the brush border enzymes sucrase–isomaltase, maltase, and alkaline phosphatase.

RESULTS:

S. Typhimurium infection significantly reduced the activity of all brush border enzymes in a dose- and time-dependent manner (P<0.05). This also occurred following injection of LPS. Pre-treatment with B. longum subsp. infantis 35624 prevented weight loss, protected brush border enzyme activity, reduced the small intestinal damage, and inhibited the increase in interleukin (IL)-10 and IL-8 expression due to Salmonella challenge.

CONCLUSIONS:

Salmonella infection reduces the small intestinal brush border enzyme activity in mice, with the level of reduction and associated weight loss increasing with dose and duration of infection. B. longum subsp. infantis 35624 treatment attenuated the effect of Salmonella infection on brush border enzyme activity and weight loss, which may be due to modulation of the host immune response.

Development of marine probiotics: prospects and approach

The term probiotics stands for bacterial strain acting for the upliftment of beneficial gut microflora as well as restricting the growth of decay or disease causing bacteria and other agents. They protect us from disease causing microorganisms and are vital for the digestion of nutrients and food. Researchers are now trying to explore the possibilities of therapeutic applications of probiotics in inflammatory bowel disease, treating diarrhea, eczema prevention in children, and reducing bladder cancer recurrence and urinary tract infections. The best known probiotic strains are Bifidobacteria, Lactobacilli, and Streptococcus thermophilus and can be found in food products such as yoghurts, fermented and unfermented milk, miso, tempeh, and some juices and soy beverages. Thus, as a substitute to the use of antibiotics, the dietary supplementation with probiotic bacteria is being widely employed in the aquaculture industry. This chapter is an attempt to shift the paradigm of research in probiotic area to the marine environment and to find ways of expanding the research in marine probiotics development.

Anti-infective properties of Lactobacillus fermentum against Staphylococcus aureus and Pseudomonas aeruginosa

Surgical wounds and implant-associated Staphylococcus aureus and Pseudomonas aeruginosa infections are often difficult to treat because of limited susceptibility of several of these strains to conventional antibiotics. As a result, there is a constant need for new alternative drugs. The aim of this study was to investigate the antimicrobial properties of Lactobacillus fermentum, a probiotic bacterium, which we have isolated from colonic biopsies. The inhibition of S. aureus and P. aeruginosa growth was evaluated by coincubating with L. fermentum strains. Growth inhibition was tested for several of their clinical isolates using agar well diffusion assays. For biofilm assay S. aureus and P. aeruginosa were grown on the glass slides and in 96-well plates in presence of 2.5 μg/ml culture filtrate of L. fermentum. Biofilms were photographed using confocal microscope or stained with 0.1% crystal violet. Reduction in the cytotoxicity of S. aureus and P. aeruginosa was observed in presence of 2.5 μg/ml L. fermentum-spent media. Using in vitroexperiments, we showed that L. fermentum-secreted compound(s) inhibits the growth, cytotoxicity and biofilm formation of several S. aureus and P. aeruginosa strains. Compound(s) present in the culture supernatant of L. fermentum may have promising applications in treating hospital-acquired infections.

Roadblocks in the gut: barriers to enteric infection

This review discusses the barriers an enteric pathogen encounters when establishing an infection in the intestinal tract. There are potential barriers in the lumen that increase competition for nutrients and space. The role of mucus layer, and the antimicrobial peptides and secretory IgA sequestered within it, are also significant barriers. After overcoming these defences, the pathogen encounters the epithelial layer. This layer can be broken down into various protective components including enterocytes, Paneth cells, goblet cells, M cells and pathogen recognition receptors. Collectively, these intestinal defences constitute significant barriers that pathogens must overcome to successfully colonize this important mucosal surface.

Health benefits of probiotics: are mixtures more effective than single strains?

PURPOSE

Most studies on probiotics utilise single strains, sometimes incorporated into yoghurts. There are fewer studies on efficacy of mixtures of probiotic strains. This review examines the evidence that (a) probiotic mixtures are beneficial for a range of health-related outcomes and (b) mixtures are more or less effective than their component strains administered separately.

RESULTS

Mixtures of probiotics had beneficial effects on the end points including irritable bowel syndrome and gut function, diarrhoea, atopic disease, immune function and respiratory tract infections, gut microbiota modulation, inflammatory bowel disease and treatment of Helicobacter pylori infection. However, only 16 studies compared the effect of a mixture with that of its component strains separately, although in 12 cases (75%), the mixture was more effective.

CONCLUSION

Probiotic mixtures appear to be effective against a wide range of end points. Based on a limited number of studies, multi-strain probiotics appear to show greater efficacy than single strains, including strains that are components of the mixtures themselves. However, whether this is due to synergistic interactions between strains or a consequence of the higher probiotic dose used in some studies is at present unclear.

Putative probiotic Lactobacillus spp. from porcine gastrointestinal tract inhibit transmissible gastroenteritis coronavirus and enteric bacterial pathogens

A total of 310 bacterial strains isolated from the porcine gastrointestinal tract were tested for their activity against transmissible gastroenteritis (TGE) coronavirus and other enteric pathogens. Based on activity, the strains Probio-38 and Probio-37 were selected as potential probiotics and identified as Lactobacillus plantarum Probio-38 and Lactobacillus salivarius Probio-37 respectively by 16S rRNA gene sequencing. Supernatants of these strains inhibited TGE coronavirus in vitro in ST cells, without any cytopathic effect even after 72 h of incubation. Both the strains exhibited high survival in synthetic gastric juice. The strains were resistant to 5% porcine bile and exhibited antimicrobial activity against all the 13 enteric bacterial pathogens tested. These strains also exhibited resistance to most of the antibiotics analyzed. The inhibition of transmissible gastroenteritis coronavirus and enteric bacterial pathogens as well as the bile tolerance, high survival in gastric juice, and the antibiotic resistance indicate that the two isolated bacterial strains are ideal probiotic candidates for animal application after proper in vivo experiments.