The place of probiotics in human intestinal infections

Lytic Escherichia phage OSYSP acts additively and synergistically with gaseous ozone against Escherichia coli O157:H7 on spinach leaves

Bacteriophage and gaseous ozone are evolving as meritorious alternatives to conventional sanitizers in food postharvest applications. Here, we investigated the efficacy of sequential treatments of a lytic bacteriophage and gaseous ozone, during vacuum cooling of fresh produce, against Escherichia coli O157:H7. Spinach leaves were spot-inoculated with 10⁵-10⁷ CFU g^-1 E. coli O157:H7 B6-914 and treated with Escherichia phage OSYSP spray (10⁹ PFU g^-1), gaseous ozone, or their combination. Vacuum cooling, which preceded or followed phage application but ran concomitantly with ozone treatment, was performed in a custom-made vessel at the following process sequence: vacuum to 28.5 in. Hg, vessel pressurization to 10 psig with gas containing 1.5 g ozone/kg gas-mix, holding for 30 min, and vessel depressurization to ambient pressure. Bacteriophage or gaseous ozone inactivated E. coli O157:H7, applied at different initial populations on spinach leaves, by 1.7-2.0 or 1.8-3.5 log CFU g^-1, respectively. At the high inoculum levels tested (7.1 log CFU g^-1), sequential treatments of phage and ozone reduced E. coli O157:H7 population by 4.0 log CFU g^-1, but when treatment order was reversed (i.e., ozone followed by bacteriophage), the combination synergistically decreased pathogen's population on spinach leaves by 5.2 log CFU g^-1. Regardless the antibacterial application order, E. coli O157:H7 populations, applied initially at ~ 10⁵ CFU g^-1, were reduced below the enumeration method's detection level (i.e., < 10¹ CFU g^-1). The study proved that bacteriophage-ozone combination, applied in conjunction with vacuum cooling, is a potent pathogen intervention strategy in fresh produce post-harvest applications.

Efficacy of Lactobacillus fermentum Isolated from the Vagina of a Healthy Woman against Carbapenem-Resistant Klebsiella Infections In Vivo

Carbapenem-resistant Enterobacteriaceae (CRE) that produce Klebsiella pneumoniae carbapenemase are increasingly reported worldwide and have become more and more resistant to nearly all antibiotics during the past decade. The emergence of K. pneumoniae strains with decreased susceptibility to carbapenems, which are used as a last resort treatment option, is a significant threat to hospitalized patients worldwide as K. pneumoniae infection is responsible for a high mortality rate in the elderly and immunodeficient individuals. This study used Lactobacillus fermentum as a candidate probiotic for treating CRE-related infections and investigated its effectiveness. We treated mice with L. fermentum originating from the vaginal fluid of a healthy Korean woman and evaluated the Lactobacilli's efficacy in preventive, treatment, non-establishment, and colonization mouse model experiments. Compared to the control, pre-treatment with L. fermentum significantly reduced body weight loss in the mouse models, and all mice survived until the end of the study. The oral administration of L. fermentum after carbapenemresistant Klebsiella (CRK) infection decreased mortality and illness severity during a 2-week observation period and showed that it affects other strains of CRK bacteria. Also, the number of Klebsiella bacteria was decreased to below 5.5 log₁₀ CFU/ml following oral administration of L. fermentum in the colonization model. These findings demonstrate L. fermentum's antibacterial activity and its potential to treat CRE infection in the future.

Identification and in vitro evaluation of probiotic attributes of lactic acid bacteria isolated from fermented food sources

Consumer's vigilance towards health-promoting foods beyond only taste and nutrition has increased the recognition for probiotic products. In the present study, various parameters have been studied to define the probiotic properties of cultures isolated from different fermented products. Around 118 samples were selectively screened for antimicrobial compound (AMC) producing isolates by overlay-plate assay using Micrococcus luteus ATCC9341. Among 134 zone producing isolates, 48 cultures showing Gram-positive, catalase negative, non-spore forming and non-motile rods and cocci were selected. Subsequently, 18 strains were chosen based on non-hemolytic, absence of biogenic amine production, gelatinase and lecithinase negative trait for safer isolates. These were identified by biochemical assays and then subjected to RAPD-PCR. The selected cultures DB-1aa, DB-b2-15b, Cu2-PM7, Cu3-PM8 and IB-pM15 were identified by 16S rDNA sequencing as Enterococcus durans, Enterococcus faecium, Lactobacillus plantarum, and two Lactobacillus fermentum, respectively. Several in vitro experiments were carried out including acid and bile tolerance, survival under simulated gastrointestinal condition, adhesion assay to evaluate the probiotic potential of the isolates. In addition, the isolates were studied for competent properties such as antibacterial, antioxidant activity, and enzyme production for their functional application. The results of the study prove the efficiency of selected isolates as potential probiotic cultures and hence can be recommended for application in any functional food formulations.

Salmonella Strain Specificity Determines Post-typhoid Central Nervous System Complications: Intervention by Lactiplantibacillus plantarum at Gut-Brain Axis

Neurological complications occurring due to Salmonella infection in some typhoid patients remain a relatively unexplored serious complication. This study firstly aimed to explore whether disseminative ability of Salmonella from gut to brain is strain specific or not and on the basis of bacterial load, histopathology, and behavioral changes, it was observed that Salmonella enterica serovar Typhimurium NCTC 74 did not cause brain infection in murine model in contrast to Salmonella Typhimurium SL1344. Simultaneously, alarming escalation in antimicrobial resistance, making the existing antibiotics treatment inefficacious, prompted us to evaluate other bio-compatible strategies as a potential treatment option. In this context, the role of gut microbiota in influencing behavior, brain neurochemistry, and physiology by modulating key molecules associated with gut-brain axis has captured the interest of the scientific community. Followed by in vitro screening of potential probiotic strains for beneficial attributes, efficacy of the selected strain was systematically evaluated at various levels of gut-brain axis against Salmonella induced brain infection. Analysis of behavioral (depression, anxiety, and locomotor), neurochemical [gamma amino butyric acid and acetylcholinesterase (AChE)], neuropathological (brain and intestinal histology; bacterial burden), and immunohistochemical studies (tight junction proteins expression) revealed its role in preventing serious manifestations and proving its potential as "psychobiotic." To the best of our knowledge, this is the first report elaborating strain specificity of Salmonella in causing post-typhoidal neurological manifestations and simultaneous use of probiotic in managing the same by influencing the pathophysiology at gut-brain axis.

Limiting the pathogenesis of Salmonella Typhimurium with berry phenolic extracts and linoleic acid overproducing Lactobacillus casei

The growing threat of emergent multidrug-resistant enteric bacterial pathogens, and their adopted virulence properties are directing to find alternative antimicrobials and/or development of dietaries that can improve host gut health and/or defense. Recently, we found that modified Lactobacillus casei (Lc + CLA) with increased production of conjugated linoleic acid has antimicrobial and other beneficial properties. Further, prebiotic alike products such as berry pomace extracts (BPEs), increase the growth of probiotics and inhibit the growth of certain bacterial pathogens. In this study, we evaluated the antibacterial effect of genetically modified Lc + CLA along with BPEs against major enteric pathogen Salmonella enterica serovar Typhimurium (ST). In mixed culture condition, the growth of ST was significantly reduced in the presence of Lc + CLA and/or BPEs. Bacterial cell-free cultural supernatant (CFCS) collected from wild-type Lc or modified Lc + CLA strains also inhibited the growth and survival of ST, and those inhibitory effects were enhanced in the presence of BPEs. We also found that the interaction of the pathogen with cultured host (HD-11 and INT-407) cells were also altered in the presence of either Lc or Lc + CLA strain or their CFCSs significantly. Furthermore, the relative expression of genes related to ST virulence and physicochemical properties of ST was altered by the effect of CFCSs of either Lc or Lc + CLA. These findings indicate that a diet containing synbiotic, specifically linoleic acid, over-produced Lc + CLA and prebiotic product BPEs, might have the potential to be effective in controlling ST growth and pathogenesis.

Fighting AMR in the Healthcare Environment: Microbiome-Based Sanitation Approaches and Monitoring Tools

Healthcare-associated infections (HAIs) affect up to 15% of all hospitalized patients, representing a global concern. Major causes include the persistent microbial contamination of hospital environment, and the growing antimicrobial-resistance (AMR) of HAI-associated microbes. The hospital environment represents in fact a reservoir of potential pathogens, continuously spread by healthcare personnel, visiting persons and hospitalized patients. The control of contamination has been so far addressed by the use of chemical-based sanitation procedures, which however have limitations, as testified by the persistence of contamination itself and by the growing AMR of hospital microbes. Here we review the results collected by a microbial-based sanitation system, inspired by the microbiome balance principles, in obtaining more effective control of microbial contamination and AMR. Whatever the sanitation system used, an important aspect of controlling AMR and HAIs relates to the ability to check any variation of a microbial population rapidly and effectively, thus effective monitoring procedures are also described.

Effects of probiotic supplements on insulin resistance in gestational diabetes mellitus: A double-blind randomized controlled trial

AIMS/INTRODUCTION

To evaluate the effect of probiotic supplements on insulin resistance in pregnant women with diet-controlled gestational diabetes mellitus.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled trial was carried out between June 2016 and February 2017. Pregnant women with diet-controlled gestational diabetes mellitus were enrolled in the study at 24-28 weeks-of-gestation and randomized to receive either probiotic supplements containing Bifidobacterium and Lactobacillus or a placebo daily for four consecutive weeks. Primary outcomes were mean differences in insulin resistance (homeostatic model assessment for insulin resistance), fasting insulin and fasting plasma glucose between the two groups. Secondary outcomes were changes in maternal weight after the intervention.

RESULTS

Data from 28 patients in the probiotic group and 29 in the placebo group were analyzed. The changes in metabolic parameters after randomization showed significant improvement in glucose metabolism in the probiotic group compared with the placebo group, including fasting plasma glucose (0.68 ± 5.88 vs 4.620 ± 7.78 mg/dL, mean difference -3.94 mg/dL, 95% confidence interval -7.62, -0.27, P = 0.034), fasting plasma insulin (1.11 ± 1.71 vs 3.77 ± 1.70 mIU/L, mean difference -2.67 mIU/L, 95% confidence interval -3.57, -1.76, P = 0.001) and homeostatic model assessment for insulin resistance (0.25 ± 0.37 vs 0.89 ± 0.46, mean difference -0.63, 95% confidence interval -0.86, -0.41, P = 0.001). Weight gain during randomization was similar between the two groups.

CONCLUSIONS

Four weeks of probiotic supplements in women with diet-controlled gestational diabetes in the late second and early third trimester lowered fasting glucose and increased insulin sensitivity. Probiotic supplements may be considered as an adjunct treatment for glycemic control in these patients.

Effects of Queso Blanco Cheese Containing Bifidobacterium longum KACC 91563 on the Intestinal Microbiota and Short Chain Fatty Acid in Healthy Companion Dogs

The effects of Queso Blanco cheese containing Bifidobacterium longum KACC 91563 was studied on the intestinal microbiota and short chain fatty acids (SCFAs) in healthy companion dogs. There were three experimental groups with five healthy dogs each: a control group, not fed with any cheese, and groups fed with Queso Blanco cheese with (QCB) or without B. longum KACC 91563 (QC) for 8 weeks. Fecal samples were collected 5 times before, during, and after feeding with cheese. Intestinal microbiota was analyzed using two non-selective agar plates (BL and TS) and five selective agar plates (BS, NN, LBS, TATAC, and MacConkey). SPME-GC-MS method was applied to confirm SCFAs and indole in dog feces. The six intestinal metabolites such as acetic, propionic, butyric, valeric, isovaleric acid and indole were identified in dog feces. Administration of B. longum KACC 91563 (QCB) for 8 weeks significantly increased the beneficial intestinal bacteria such as Bifidobacterium (8.4±0.55) and reduced harmful bacteria such as Enterobacteriaceae and Clostridium (p<0.05). SCFA such as acetic and propionic acid were significantly higher in the QCB group than in the Control group (p<0.05). In conclusion, this study demonstrates that administration of Queso Blanco cheese containing B. longum KACC 91563 had positive effects on intestinal microbiota and metabolites in companion dogs. These results suggest that Queso Blanco cheese containing B. longum KACC 91563 could be used as a functional food for companion animals and humans.

Rotavirus: Genetics, pathogenesis and vaccine advances

Since its discovery 40 years ago, rotavirus (RV) is considered to be a major cause of infant and childhood morbidity and mortality particularly in developing countries. Nearly every child in the world under 5 years of age is at the risk of RV infection. It is estimated that 90% of RV-associated mortalities occur in developing countries of Africa and Asia. Two live oral vaccines, RotaTeq (RV5, Merck) and Rotarix (RV1, GlaxoSmithKline) have been successfully deployed to scale down the disease burden in Europe and America, but they are less effective in Africa and Asia. In April 2009, the World Health Organization recommended the inclusion of RV vaccination in national immunization programs of all countries with great emphasis in developing countries. To date, 86 countries have included RV vaccines into their national immunization programs including 41 Global Alliance for Vaccines and Immunization eligible countries. The predominant RV genotypes circulating all over the world are G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8], while G12[P6] and G12[P8] are emerging genotypes. On account of the segmented genome, RV shows an enormous genetic diversity that leads to the evolution of new genotypes that can influence the efficacy of current vaccines. The current need is for a global RV surveillance program to monitor the prevalence and antigenic variability of new genotypes to formulate future vaccine development planning. In this review, we will summarize the previous and recent insights into RV structure, classification, and epidemiology and current status of RV vaccination around the globe and will also cover the status of RV research and vaccine policy in Pakistan.

Antimicrobial properties of lactic acid bacteria isolated from traditional yogurt and milk against Shigella strains

Background: Lactic acid bacteria (LAB) are normal flora of the mouth, intestines and the female genital tract. They are also frequently found in meat, vegetables, and dairy products. Most of probiotic bacteria belong to the LAB group. Some probiotic LAB are useful in prevention and treatment of diarrheal diseases. The aim of this study was to investigate the antimicrobial properties of LAB isolated from traditional yogurt and milk against Shigella strains.

Materials and methods: Forty LAB strains were isolated from traditional yogurt and milk. The antimicrobial activity of LAB against Shigella strains (eight S. flexneri, four S. sonnei) was examined using the agar-well diffusion assay. LAB strains with antimicrobial effect against all Shigella strains were identified by 16S rRNA gene sequencing.

Results: Six LAB strains inhibited the growth of all 12 Shigella strains. Lb. paracasei Y1-3, Lb. paracasei Y8-1 and Lb. fermentum Y2-2 were isolated from yogurt. Lb. paracasei M18-1, Lb. parelimentarius M4-3 and Lb. plantarum M19-1 were isolated from milk.

Conclusion: This study showed that Lactobacillus strains with good inhibitory activity against S. flexneri and S. sonnei could be isolated from traditional yogurt and milk.

Probiotics and gastrointestinal conditions: An overview of evidence from the Cochrane Collaboration

Alterations in the composition of the gut microbiota are associated with a number of gastrointestinal (GI) conditions, including diarrhea, inflammatory bowel diseases (IBD), and liver diseases. Probiotics, live microorganisms that may confer a health benefit to the host when consumed, are commonly used as a therapy for treating these GI conditions by means of modifying the composition or activity of the microbiota. The purpose of this review was to summarize the evidence on probiotics and GI conditions available from Cochrane, a nonprofit organization that produces rigorous and high-quality systematic reviews of health interventions. Findings from this review will help provide more precise guidance for clinical use of probiotics and to identify gaps in probiotic research related to GI conditions.

Incidence and outcomes of bloodstream infections among hematopoietic cell transplant recipients from species commonly reported to be in over-the-counter probiotic formulations

BACKGROUND

Probiotic supplementation has been promoted for numerous health conditions; however, safety in immunosuppressed patients is unknown. We evaluated bloodstream infections (BSIs) caused by common probiotic organisms in hematopoietic cell transplant recipients.

METHODS

All blood culture (BC) results from a cohort of hematopoietic cell transplant recipients transplanted at Fred Hutchinson Cancer Research Center in Seattle, Washington, between 2002 and 2011 were reviewed. Patients with at least 1 positive BC for common probiotic organisms (Lactobacillus species, Bifidobacterium species, Streptococcus thermophilus, and Saccharomyces species) within 1 year post hematopoietic cell transplantation (HCT) were considered cases. Data were collected from center databases, which contain archived laboratory data, patient demographics, and clinical summaries.

RESULTS

A total of 19/3796 (0.5%) patients developed a BSI from one of these organisms within 1 year post HCT; no Bifidobacterium species or S. thermophilus were identified. Cases had a median age of 49 years (interquartile range [IQR]: 39-53), and the majority were allogeneic hematopoietic cell transplant recipients (14/19, 74%). Most positive BCs were Lactobacillus species (18/19) and occurred at a median of 84 days (IQR: 34-127) post transplant. The incidence rate of Lactobacillus bacteremia was 1.62 cases per 100,000 patient-days; the highest rate occurred within 100 days post transplant (3.3 per 100,000 patient-days). Eight patients (44%) were diagnosed with acute graft-versus-host disease of the gut prior to the development of bacteremia. No mortality was attributable to any of these infections.

CONCLUSION

Organisms frequently incorporated in available over-the-counter probiotics are infrequent causes of bacteremia after HCT. Studies evaluating the use of probiotics among high-risk patients are needed.

Cellular and molecular effects of yeast probiotics on cancer

The cancer is one of the main causes of human deaths worldwide. The exact mechanisms of initiation and progression of malignancies are not clear yet, but there is a common agreement about the role of colonic microbiota in the etiology of different cancers. Probiotics have been examined for their anti-cancer effects, and different mechanisms have been suggested about their antitumor functions. Nonpathogenic yeasts, as members of probiotics family, can be effective on gut microbiota dysbiosis. Generally safe yeasts have shown so many beneficial effects on human health. Probiotic yeasts influence physiology, metabolism, and immune homeostasis in the colon and contribute to cancer treatment due to possessing anti-inflammatory, anti-proliferative and anti-cancer properties. This study reviews some of the health-beneficial effects of probiotic yeasts and their biological substances like folic acid and β-glucan on cancer and focuses on the possible cellular and molecular mechanisms of probiotic yeasts such as influencing pathogenic bacteria, inactivation of carcinogenic compounds, especially those derived from food, improvement of intestinal barrier function, modulation of immune responses, antitoxic function, apoptosis, and anti-proliferative effects.

Probiotics for Antibiotic-Associated Diarrhoea (PAAD): a prospective observational study of antibiotic-associated diarrhoea (including Clostridium difficile-associated diarrhoea) in care homes

BACKGROUND

Antibiotic prescribing rates in care homes are higher than in the general population. Antibiotics disrupt the normal gut flora, sometimes causing antibiotic-associated diarrhoea (AAD). Clostridium difficile (Hall and O'Toole 1935) Prévot 1938 is the most commonly identified cause of AAD. Little is known either about the frequency or type of antibiotics prescribed in care homes or about the incidence and aetiology of AAD in this setting.

OBJECTIVES

The Probiotics for Antibiotic-Associated Diarrhoea (PAAD) study was designed as a two-stage study. PAAD stage 1 aimed to (1) prospectively describe antibiotic prescribing in care homes; (2) determine the incidence of C. difficile carriage and AAD (including C. difficile-associated diarrhoea); and (3) to consider implementation challenges and establish the basis for a sample size estimation for a randomised controlled trial (RCT) of probiotic administration with antibiotics to prevent AAD in care homes. If justified by PAAD stage 1, the RCT would be implemented in PAAD stage 2. However, as a result of new evidence regarding the clinical effectiveness of probiotics on the incidence of AAD, a decision was taken not to proceed with PAAD stage 2.

DESIGN

PAAD stage 1 was a prospective observational cohort study in care homes in South Wales with up to 12 months' follow-up for each resident.

SETTING

Recruited care homes had management and owner's agreement to participate and three or more staff willing to take responsibility for implementing the study.

PARTICIPANTS

Eleven care homes were recruited, but one withdrew before any residents were recruited. A total of 279 care home residents were recruited to the observational study and 19 withdrew, 16 (84%) because of moving to a non-participating care home.

MAIN OUTCOME MEASURES

The primary outcomes were the rate of antibiotic prescribing, incidence of AAD, defined as three or more loose stools (type 5-7 on the Bristol Stool Chart) in a 24-hour period, and C. difficile carriage confirmed on stool culture.

RESULTS

Stool samples were obtained at study entry from 81% of participating residents. Over half of the samples contained antibiotic-resistant isolates, with Enterobacteriaceae resistant to ciprofloxacin in 47%. Residents were prescribed an average of 2.16 antibiotic prescriptions per year [95% confidence interval (CI) 1.90 to 2.46]. Antibiotics were less likely to be prescribed to residents from dual-registered homes. The incidence of AAD was 0.57 (95% CI 0.41 to 0.81) episodes per year among those residents who were prescribed antibiotics. AAD was more likely in residents who were prescribed co-amoxiclav than other antibiotics and in those residents who routinely used incontinence pads. AAD was less common in residents from residential homes.

CONCLUSIONS

Care home residents, particularly in nursing homes, are frequently prescribed antibiotics and often experience AAD. Antibiotic resistance, including ciprofloxacin resistance, is common in Enterobacteriaceae isolated from the stool of care home residents. Co-amoxiclav is associated with greater risk of AAD than other commonly prescribed antibiotics.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN 7954844.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 63. See the NIHR Journals Library website for further project information.

Efficacy of probiotic use in acute rotavirus diarrhea in children: A systematic review and meta-analysis

BACKGROUND

Probiotic therapies with different strains demonstrated some beneficial effects, although some studies did not show any significant effects. This study assessed systematically the current knowledge on the effect of probiotic bacteria on duration of acute rotavirus diarrhea in children compared with control.

METHODS

The PubMed, Cochrane Controlled Trial Register (CCTR) and Ovid (Wolters Kluwer Health) were searched between 1980 to June 15, 2013. Randomized controlled trials including the administration of probiotics for treatment of rotavirus diarrhea in infants and children were reviewed.

RESULTS

A total number of 1244 articles were found through the aforementioned search. 203 articles were selected after the first screening of title and abstract. The intervention group included subjects who received probiotic strains and dosage in any conditions. Placebo or any similar vehicle without probiotic was used in the controlled trials. Finally, 14 articles were selected. The outcomes from each study were considered in the duration of diarrhea. Statistical analyses were performed with Stata software. The pooled estimate of efficacy of probiotics in prevention or treatment of disease yielded in all studies a mean difference of 0.41 (CI 95%: -0.56 to -0.25; p<0.001). The pooled estimate of efficacy of lactobacillus rhamnosus GG and other probiotics significantly reduced the duration of diarrhea. Among trials, the overall reduction of LGG was 0.47 (CI 95%: -0.80 to -0.14; P= 0.020).

CONCLUSION

In conclusion, probiotics exert positive effect in reducing the duration of acute rotavirus diarrhea compared with control.

Lack of correlation between in vitro antibiosis and in vivo protection against enteropathogenic bacteria by probiotic lactobacilli

Increased resistance to infection is one of the beneficial effects attributed to probiotic microorganisms. This effect may be due to several mechanisms: production of inhibitory substances, blocking of adhesion sites on the intestinal surface, competition for nutrients and stimulation of mucosal and systemic immunity. The present study aimed to investigate the correlation between in vitro and in vivo antimicrobial activity of probiotic lactobacilli. The agar spot test was used to show that twenty Lactobacillus strains were able to inhibit the enteropathogenic bacterium Yersinia enterocolitica. This inhibition was mainly attributable to a decrease in pH resulting from dextrose fermentation by lactobacilli. The inhibition of Y. enterocolitica, Salmonella enterica serovar Typhimurium and Listeria monocytogenes by two probiotic strains, Lactobacillus casei C1 and Lactobacillus plantarum C4, was also associated with the pH decrease. However, both strains lacked protective effects in mouse experimental infection models, with the exception of long-lasting pre-treatment with L. plantarum C4, which exerted a partial protective effect against S. Typhimurium that was attributable to an immunostimulatory mechanism. Our results show that in vitro antibiosis tests do not provide useful information on the probiotic potential of Lactobacillus strains.

Probiotic yeast inhibits VEGFR signaling and angiogenesis in intestinal inflammation

Background and Aims

Saccharomyces boulardii (Sb) can protect against intestinal injury and tumor formation, but how this probiotic yeast controls protective mucosal host responses is unclear. Angiogenesis is an integral process of inflammatory responses in inflammatory bowel diseases (IBD) and required for mucosal remodeling during restitution. The aim of this study was to determine whether Sb alters VEGFR (vascular endothelial growth factor receptor) signaling, a central regulator of angiogenesis.

Methods

HUVEC were used to examine the effects of Sb on signaling and on capillary tube formation (using the ECMatrix™ system). The effects of Sb on VEGF-mediated angiogenesis were examined in vivo using an adenovirus expressing VEGF-A(164) in the ears of adult nude mice (NuNu). The effects of Sb on blood vessel volume branching and density in DSS-induced colitis was quantified using VESsel GENeration (VESGEN) software.

Results

1) Sb treatment attenuated weight-loss (p<0.01) and histological damage (p<0.01) in DSS colitis. VESGEN analysis of angiogenesis showed significantly increased blood vessel density and volume in DSS-treated mice compared to control. Sb treatment significantly reduced the neo-vascularization associated with acute DSS colitis and accelerated mucosal recovery restoration of the lamina propria capillary network to a normal morphology. 2) Sb inhibited VEGF-induced angiogenesis in vivo in the mouse ear model. 3) Sb also significantly inhibited angiogenesis in vitro in the capillary tube assay in a dose-dependent manner (p<0.01). 4) In HUVEC, Sb reduced basal VEGFR-2 phosphorylation, VEGFR-2 phosphorylation in response to VEGF as well as activation of the downstream kinases PLCγ and Erk1/2.

Conclusions

Our findings indicate that the probiotic yeast S boulardii can modulate angiogenesis to limit intestinal inflammation and promote mucosal tissue repair by regulating VEGFR signaling.

Potential role of probiotics on colorectal cancer prevention

Background

Colorectal cancer represents the most common malignancy of the gastrointestinal tract. Owing to differences in dietary habits and lifestyle, this neoplasm is more common in industrialized countries than in developing ones. Evidence from a wide range of sources supports the assumption that the link between diet and colorectal cancer may be due to an imbalance of the intestinal microflora.

Discussion

Probiotic bacteria are live microorganisms that, when administered in adequate amounts, confer a healthy benefit on the host, and they have been investigated for their protective anti-tumor effects. In vivo and molecular studies have displayed encouraging findings that support a role of probiotics in colorectal cancer prevention.

Summary

Several mechanisms could explain the preventive action of probiotics against colorectal cancer onset. They include: alteration of the intestinal microflora; inactivation of cancerogenic compounds; competition with putrefactive and pathogenic microbiota; improvement of the host’s immune response; anti-proliferative effects via regulation of apoptosis and cell differentiation; fermentation of undigested food; inhibition of tyrosine kinase signaling pathways.

Survival of Lactobacillus rhamnosus GG as influenced by storage conditions and product matrixes

Mortality resulting from diarrhea especially that occurs in children younger than 5 y of age ranks 3rd among all deaths caused by infectious diseases worldwide. Probiotics such as Lactobacillus rhamnosus GG are clinically shown to effectively reduce the incidence of diarrhea in children. A food substrate is one of the major factors regulating the colonization of microorganisms in human gastrointestinal tracts. Peanut butter is a nutritious, low-moisture food that could be a carrier for probiotics. In this study, we observed the influence of storage conditions and product matrixes on the survival of L. rhamnosus GG. Cells of L. rhamnosus GG were inoculated into full fat or reduced fat peanut butter at 10(7) CFU/g. Inoculated peanut butter was stored at 4, 25, or 37 °C for 48 wk. Samples were drawn periodically to determine the populations of L. rhamnosus GG. Results showed that there was no significant decrease in the viable counts of L. rhamnosus GG in products stored 4 °C. The survivability of L. rhamnosus GG decreased with increasing storage temperature and time. Product matrixes did not significantly affect the survival of L. rhamnosus GG except at 37 °C. Populations of L. rhamnosus GG were preserved at >6 logs in products stored at 4 °C for 48 wk and at 25 °C for 23 to 27 wk. At 37 °C, the 6-log level could not be maintained for even 6 wk. The results suggest that peanut butter stored at 4 and 25 °C could serve as vehicles to deliver probiotics.

Effect of Fructo-Oligosaccharide, Isomalto-Oligosaccharide, Inulin and Xylo-Oligosaccharide on Survival of B. Bifidum during Freeze-Drying

Four different prebiotics including fructo-oligosaccharide isomalto-oligosaccharide, inulin and xylo-oligosaccharide were screened for their effects on survival of Bifidobacterium bifidum during freeze-drying. The additions of prebiotics (v/v) were all 4%, 8%, 12%, 16% and 20%. The results showed that prebiotics could act on Bifidobacterium Bifidum. The optimum concentration of fructo-oligosaccharides (FOS) in samples for surival of Bifidobacterium bifidum was 12% and for viable count was 20％. Addition of xylo-oligosaccharides (XOS) played a significant role in promoting cell viablity when it was in low level. The optimum concentration of isomalto-oligosaccharides (IMO) for surival of Bifidobacterium bifidum was 16% and for viable count was 12％, while inulin in samples for surival and viable cell of Bifidobacterium bifidum both was 4％.

The insect peptide coprisin prevents Clostridium difficile-mediated acute inflammation and mucosal damage through selective antimicrobial activity

Clostridium difficile-associated diarrhea and pseudomembranous colitis are typically treated with vancomycin or metronidazole, but recent increases in relapse incidence and the emergence of drug-resistant strains of C. difficile indicate the need for new antibiotics. We previously isolated coprisin, an antibacterial peptide from Copris tripartitus, a Korean dung beetle, and identified a nine-amino-acid peptide in the α-helical region of it (LLCIALRKK) that had antimicrobial activity (J.-S. Hwang et al., Int. J. Pept., 2009, doi:10.1155/2009/136284). Here, we examined whether treatment with a coprisin analogue (a disulfide dimer of the nine peptides) prevented inflammation and mucosal damage in a mouse model of acute gut inflammation established by administration of antibiotics followed by C. difficile infection. In this model, coprisin treatment significantly ameliorated body weight decreases, improved the survival rate, and decreased mucosal damage and proinflammatory cytokine production. In contrast, the coprisin analogue had no apparent antibiotic activity against commensal bacteria, including Lactobacillus and Bifidobacterium, which are known to inhibit the colonization of C. difficile. The exposure of C. difficile to the coprisin analogue caused a marked increase in nuclear propidium iodide (PI) staining, indicating membrane damage; the staining levels were similar to those seen with bacteria treated with a positive control for membrane disruption (EDTA). In contrast, coprisin analogue treatment did not trigger increases in the nuclear PI staining of Bifidobacterium thermophilum. This observation suggests that the antibiotic activity of the coprisin analogue may occur through specific membrane disruption of C. difficile. Thus, these results indicate that the coprisin analogue may prove useful as a therapeutic agent for C. difficile infection-associated inflammatory diarrhea and pseudomembranous colitis.

Longitudinal analysis and genotyping of infant dominant bifidobacterial populations

Bifidobacterial population dynamics were investigated by the longitudinal analysis of the dominant population isolated from the feces of young infants. After molecular identification and fingerprinting comparison, clone identity of the consecutive strains belonging to the same species for one individual was performed by pulsed-field gel electrophoresis. The results, obtained from 15 individuals sampled four times over a five-week period suggested a turnover of the dominant bifidobacteria in the population not only at the species but also at its species representative levels. This study provides new insights of the in vivo dynamics of commensal bifidobacteria. It highlights the need to take into consideration the fluctuation of bifidobacterial populations that may occur in one individual in order to investigate reliably the impact of dietary components, such as probiotics or prebiotics, on the intestinal ecosystem.

Selective growth inhibitory effect of biochanin A against intestinal tract colonizing bacteria

Both bifidobacteria and clostridia are part of the natural gut microflora and while clostridia may be responsible for severe intestinal infections, bifidobacteria are probiotic microorganisms belonging to the most important prospective bacteria in the bowel. The antimicrobial activity of biochanin A was tested in vitro against six Bifidobacterium spp., and eight Clostridium spp. using the broth microdilution method. Biochanin A showed an inhibition against all clostridia in the range of minimum inhibitory concentrations (MIC) from 64 microg/mL (for Cl. clostridioforme, strains DSM 933 and I3) to 1,024 microg/mL (for Cl. perfringens, DSM 11778). No bifidobacteria were suppressed at four-fold higher concentration (MICs > 4,096) than MIC of Cl. perfringens. These results indicate selective growth inhibition of biochanin A and its potential use in antimicrobial prevention and/or protection.

Proteomic comparison of the cytosolic proteins of three Bifidobacterium longum human isolates and B. longum NCC2705

Background

Bifidobacteria are natural inhabitants of the human gastrointestinal tract. In full-term newborns, these bacteria are acquired from the mother during delivery and rapidly become the predominant organisms in the intestinal microbiota. Bifidobacteria contribute to the establishment of healthy intestinal ecology and can confer health benefits to their host. Consequently, there is growing interest in bifidobacteria, and various strains are currently used as probiotic components in functional food products. However, the probiotic effects have been reported to be strain-specific. There is thus a need to better understand the determinants of the observed benefits provided by these probiotics. Our objective was to compare three human B. longum isolates with the sequenced model strain B. longum NCC2705 at the chromosome and proteome levels.

Results

Pulsed field electrophoresis genotyping revealed genetic heterogeneity with low intraspecies strain relatedness among the four strains tested. Using two-dimensional gel electrophoresis, we analyzed qualitative differences in the cytosolic protein patterns. There were 45 spots that were present in some strains and absent in others. Spots were excised from the gels and subjected to peptide mass fingerprint analysis for identification. The 45 spots represented 37 proteins, most of which were involved in carbohydrate metabolism and cell wall or cell membrane synthesis. Notably, the protein patterns were correlated with differences in cell membrane properties like surface hydrophobicity and cell agglutination.

Conclusion

These results showed that proteomic analysis can be valuable for investigating differences in bifidobacterial species and may provide a better understanding of the diversity of bifidobacteria and their potential use as probiotics.

Saccharomyces boulardii inhibits EGF receptor signaling and intestinal tumor growth in Apc(min) mice

BACKGROUND & AIMS

Saccharomyces boulardii (Sb) is a probiotic yeast with anti-inflammatory and anti-microbial activities and has been used for decades in the prevention and treatment of a variety of human gastrointestinal disorders. We reported previously that Sb modulates host inflammatory responses through down-regulation of extracellular signal-regulated kinase (Erk)1/2 activities both in vitro and in vivo. The aim of this study was to identify upstream mediators responsible for extracellular signal-regulated kinase (Erk)1/2 inactivation and to examine the effects of Sb on tumor development in Apc(Min) mice.

METHODS

Signaling studies of colon cancer cells were done by western blot. Cell proliferation was measured by MTS and BrdU assay. Apoptosis was examined by flow cytometry, tunel assay and caspase assay. Apc(Min) mice were orally given Sb for 9 weeks before sacrifice for tumor analysis.

RESULTS

We found that the epidermal growth factor receptor (EGFR) was deactivated upon exposure to Sb, leading to inactivation of both the EGFR-Erk and EGFR-Akt pathways. In human colonic cancer cells, Sb prevented EGF-induced proliferation, reduced cell colony formation, and promoted apoptosis. HER-2, HER-3, and insulin-like growth factor-1 receptor were also found to be inactivated by Sb. Oral intake of Sb reduced intestinal tumor growth and dysplasia in C57BL/6J Min/+ (Apc(Min)) mice.

CONCLUSIONS

Thus, in addition to its anti-inflammatory effects, Sb inhibits EGFR and other receptor tyrosine kinase signaling and thereby may also serve a novel therapeutic or prophylactic role in intestinal neoplasia.

The use of customised probiotics in the cultivation of western king prawns (Penaeus latisulcatus Kishinouye, 1896)

This study presents a comprehensive review of probiotics usage in aquaculture with a specific emphasis on our research series on the effectiveness of the customised probiotics, Pseudomonas synxantha and Pseudomonas aeruginosa on the cultivation of western king prawns, Penaeus latisulcatus. These customised probiotics resulted from tests using five inhibition test methods between the bacteria isolated from two commercial probiotic products and Vibrio spp. isolated from western king prawns and other aquatic animals. The results proved the suitability and safety of these probiotics in the cultivation of western king prawns as they conclusively met all the essential requirements for appropriate probiotics. These probiotics have shown similar beneficial effects as the common prebiotics, Bio-Mos and beta-1,3-d-glucan on the growth, survival and immune responses of the prawns. The supplementation of probiotics with the formulated feed was more efficacious and more practical than direct application into the rearing media. The prawns exposed to the combined probiotics were healthier than those exposed to the individual probiotics. P. aeruginosa was more effective for improving prawn health than P. synxantha. The probiotic-fed prawns were not influenced by Vibrio harveyi at 10(3) CFU ml(-1) for 36 h of challenge. In conclusion, these customised probiotics can be used as appropriate probiotics and as a suitable replacement of antibiotics, for disease control in western king prawn aquaculture.

Fate and effects of Camembert cheese micro-organisms in the human colonic microbiota of healthy volunteers after regular Camembert consumption

The objective of this study was to determine i) if Camembert cheese micro-organisms could be detected in fecal samples after regular consumption by human subjects and ii) the consequence of this consumption on global metabolic activities of the host colonic microbiota. An open human protocol was designed where 12 healthy volunteers were included: a 2-week period of fermented products exclusion followed by a 4-weeks Camembert ingestion period where 2x40 g/day of Camembert cheese was consumed. Stools were collected from the volunteers before consumption, twice during the ingestion period (2nd and 4th week) and once after a wash out period of 2 weeks. During the consumption of Camembert cheese, high levels of Lactococcus lactis and Leuconostoc mesenteroides were measured in fecal samples using real-time quantitative PCR, reaching median values of 8.2 and 7.5 Log(10) genome equivalents/g of stool. For Ln. mesenteroides, persistence was observed 15 days after the end of Camembert consumption. The survival of Geotrichum candidum was also assessed and the fecal concentration reached a median level of 7.1 Log(10) CFU/g in stools. Except a decreasing trend of the nitrate reductase activity, no significant modification was shown in the metabolic activities during this study.

Lactobacillus rhamnosus R11 consumed in a food supplement survived human digestive transit without modifying microbiota equilibrium as assessed by real-time polymerase chain reaction

The aim of this study was to evaluate the survival of Lactobacillus rhamnosus R11 and Lactobacillus acidophilus R52 in the human digestive tract and their effects on the microbiota homeostasis. We designed an open human trial including 14 healthy volunteers. A 3-week exclusion period of fermented products was followed by a 12-day consumption period of 4 capsules daily containing 2 x 10(9)L. rhamnosus R11 and 1 x 10(8)L. acidophilus R52, and a 12-day wash-out period. The 2 strains and dominant bacterial groups of the microbiota were quantified by real-time polymerase chain reaction. At the end of the capsule consumption period, high levels of L. rhamnosus R11 were detected in faecal samples from all volunteers, reaching a mean value of 7.1 log(10) colony-forming unit (CFU) equivalents/g of stool. L. acidophilus R52 was detected in the stools of only 1 volunteer, reaching a maximum level of 6.1 log(10) CFU equivalents/g of stool. Dilution plating enumerations performed in parallel provided less consistent and generally lower levels. No significant effect of capsule consumption was observed on microbiota homeostasis for the dominant faecal populations. Mean values of 8.8, 9.2, 9.9 and 10.6 log(10) CFU equivalents/g of stool were obtained for the Clostridium coccoides, Bifidobacterium sp., Bacteroides sp. and Clostridium leptum groups, respectively.

Probiotics affect virulence-related gene expression in Escherichia coli O157:H7

The attachment of enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) to host intestinal epithelial cells is essential for the development of hemorrhagic colitis and hemolytic-uremic syndrome in humans. Genes involved in attachment are carried within a pathogenicity island named the locus of enterocyte effacement (LEE), known to be directly activated by quorum sensing (QS). In the present study, we investigated autoinducer-2 (AI-2) production and the expression of several virulence-related genes in EHEC O157 grown in the absence and presence of a Lactobacillus acidophilus-secreted molecule(s). Transcription of important EHEC O157 virulence-related genes was studied by constructing promoter-reporter fusions and reverse transcriptase PCR. Shiga toxin (Stx) production was assayed by an enzyme immunoassay. When EHEC O157 was grown in the presence of chromatographically selected fractions of L. acidophilus La-5 cell-free spent medium, we observed a significant reduction of both extracellular AI-2 concentration and the expression of important virulence-related genes, although no significant difference in Stx production was observed. We show here that L. acidophilus La-5 secretes a molecule(s) that either acts as a QS signal inhibitor or directly interacts with bacterial transcriptional regulators, controlling the transcription of EHEC O157 genes involved in colonization.

Yeasts in foods and beverages: impact on product quality and safety

The role of yeasts in food and beverage production extends beyond the well-known bread, beer and wine fermentations. Molecular analytical technologies have led to a major revision of yeast taxonomy, and have facilitated the ecological study of yeasts in many other products. The mechanisms by which yeasts grow in these ecosystems and impact on product quality can now be studied at the level of gene expression. Their growth and metabolic activities are moderated by a network of strain and species interactions, including interactions with bacteria and other fungi. Some yeasts have been developed as agents for the biocontrol of food spoilage fungi, and others are being considered as novel probiotic organisms. The association of yeasts with opportunistic infections and other adverse responses in humans raises new issues in the field of food safety.

The effect of ingestion of milk supplemented with salivaricin A-producing Streptococcus salivarius on the bacteriocin-like inhibitory activity of streptococcal populations on the tongue

The colonization efficacies of salivaricin A (SalA)-producing Streptococcus salivarius strains 20P3 and 5 were compared when given in milk to 219 children, using either 2-day or 9-day dosing regimens. Colonization levels overall were superior for strain 5, and the 9-day dosing schedule resulted in higher levels of both initial colonization and strain persistence. The indigenous streptococcal tongue populations of 20 (10.9%) of the 189 children in the 2-day trial showed markedly increased SalA-like inhibitory activity following use of the S. salivarius-supplemented milk. All 20 of these children were found to have had relatively small (<5% of total S. salivarius) indigenous tongue populations of SalA-producing S. salivarius, and the relative proportions and/or inhibitory activity of these SalA producers on the childrens' tongues increased following ingestion of the S. salivarius-supplemented milk. Because SalA is known to be strongly inhibitory to Streptococcus pyogenes, an important implication of this study is that the consumption of SalA-producing probiotic S. salivarius could potentially help to effect a sustained increase in SalA-mediated protection against S. pyogenes infection.

Effects of spent culture supernatant of Lactobacillus acidophilus on intestinal flora in mice with antibiotic-associated diarrhoea

AIM: To study the effects of the spent culture supernatant (SCS) of Lactobacillus acidophilus strain LA14 on the intestinal flora in mice with antibiotic-associated diarrhoea.

METHODS: Sixty mice were randomly and averagely divided into 6 groups: normal control group, model group, SCS group, living bacteria group, SCS plus living bacteria group, and spontaneous recovery group. The animal model of the intestinal flora imbalance was made by intraperitoneal administration of ampicillin 2000 mg/(kg•d) for 3 d. Then the mice in normal control group and model group were killed, while the mice in the other groups were administered (ig) with the corresponding drugs or normal saline (30 mL/kg per day, the adopted concentration of living bacteria was 3×10⁹ CFU/kg per day) for another 3 d. At the end of the 3^rd day, all the mice were killed and the floras in the contents of the caecum were analyzed.

RESULTS: Intestinal flora imbalance occurred in the mice administered with ampicillin and the numbers (lgCFU/L) of four main intestinal floras changed obviously. In comparison with those in normal control group, the numbers of Escherichia coli andEnterococcus were significantly increased (10.13 ± 0.10 vs 9.03 ± 0.11, P < 0.01; 10.52 ± 0.11 vs 9.11 ± 0.09, P < 0.01), while the numbers of Lactobacillus and Bifidobacterium were remarkably decreased (10.51 ± 0.07 vs 11.88 ± 0.10, P < 0.01; 10.38 ± 0.31 vs 11.61 ± 0.13, P < 0.05). After the mice were administered with SCS, living bacteria and SCS plus living bacteria, the numbers (compared with those in spontaneous recovery group) of Lactobacillus and Bifidobacterium were remarkably increased (Lactobacillus: 11.53 ± 0.17 vs 9.74 ± 0.37, P < 0.01; 11.54 ± 0.05, 11.45 ± 0.07 vs 9.74 ± 0.37, P < 0.05; Bifidobacterium: 11.54 ± 0.22, 11.30 ± 0.99 vs 9.51 ± 0.52, P < 0.05; 11.13 ± 0.16 vs 9.51 ± 0.52, P < 0.01), while the numbers of Escherichia coli and Enterococcus were significantly decreased again (Escherichia coli: 9.42 ± 0.22, 9.50 ± 0.06, 9.22 ± 0.39 vs 9.97 ± 0.61, P< 0.05; Enterococcus: 9.48 ± 0.20, 9.45 ± 0.16, 9.37 ± 0.21 vs 9.89 ± 0.43, P < 0.05).

CONCLUSION: Both living bacteria and SCS of Lactobacillus acidophilus can regulate the intestinal flora imbalance in mice with antibiotic-associated diarrhoea, and help to recover the numbers of Lactobacillus and Bifidobacterium in the intestinal tract.

Saccharomyces boulardii inhibits ERK1/2 mitogen-activated protein kinase activation both in vitro and in vivo and protects against Clostridium difficile toxin A-induced enteritis

Saccharomyces boulardii (Sb), a probiotic yeast, protects against intestinal injury and inflammation caused by a wide variety of enteric pathogens, including Clostridium difficile. Given the broad range of protective effects of Sb in multiple gastrointestinal disorders, we hypothesize that Sb modulates host signaling pathways involved in intestinal inflammatory responses. In this study, we found that Sb culture supernatant (SbS) inhibits interleukin-8 production induced by C. difficile toxin A or IL-1beta in human colonocyte NCM460 cells in a dose-dependent fashion. Furthermore, SbS inhibited IL-1beta and toxin A induced Erk1/2 and JNK/SAPK but not p38 activation in NCM460 cells. To test whether this inhibition also occurs in vivo, we used a previously established mouse ileal loop model. On its own, SbS had no significant effect on basal fluid secretion or intestinal histology. However, Erk1/2 activation was significantly inhibited by SbS in toxin A exposed mouse ileal mucosa. In control loops, toxin A increased fluid secretion (2.2-fold), histological score (3.3-fold), and levels of the chemokine KC (4.5-fold). SbS pretreatment completely normalized toxin A mediated fluid secretion (p < 0.01), and histopathologic changes (p < 0.01) and substantially inhibited toxin A-associated KC increases (p < 0.001). In summary, the probiotic yeast S. boulardii inhibits C. difficile toxin A-associated enteritis by blocking the activation of Erk1/2 MAP kinases. This study indicates a new mechanism whereby Sb protects against intestinal inflammation and supports the hypothesis that Sb modulates host inflammatory signaling pathways to exert its beneficial effects.

Saccharomyces boulardii produces a soluble anti-inflammatory factor that inhibits NF-κB-mediated IL-8 gene expression

Saccharomyces boulardii (Sb) is a non-pathogenic yeast that ameliorates intestinal injury and inflammation caused by a wide variety of enteric pathogens. We hypothesized that Sb may exert its probiotic effects by modulation of host cell signaling and pro-inflammatory gene expression. Human HT-29 colonocytes and THP-1 monocytes were stimulated with IL-1beta, TNFalpha or LPS in the presence or absence of Sb culture supernatant (SbS). IL-8 protein and mRNA levels were measured by ELISA and RT-PCR, respectively. The effect of SbS on IkappaB alpha degradation was studied by Western blotting and on NF-kappaB-DNA binding by EMSA. NF-kappaB-regulated gene expression was evaluated by transient transfection of THP-1 cells with a NF-kappaB-responsive luciferase reporter gene. SbS inhibited IL-8 protein production in IL-1beta or TNFalpha stimulated HT-29 cells (by 75% and 85%, respectively; P<0.001) and prevented IL-1beta-induced up-regulation of IL-8 mRNA. SbS also inhibited IL-8 production, prevented IkappaB alpha degradation, and reduced both NF-kappaB-DNA binding and NF-kappaB reporter gene up-regulation in IL-1beta or LPS-stimulated THP-1 cells. Purification and characterization studies indicate that the S. boulardii anti-inflammatory factor (SAIF) is small (<1 kDa), heat stable, and water soluble. The probiotic yeast Saccharomyces boulardii exerts an anti-inflammatory effect by producing a low molecular weight soluble factor that blocks NF-kappaB activation and NF-kappaB-mediated IL-8 gene expression in intestinal epithelial cells and monocytes. SAIF may mediate, at least in part, the beneficial effects of Saccharomyces boulardii in infectious and non-infectious human intestinal disease.

Fermentation of fructooligosaccharides and inulin by bifidobacteria: a comparative study of pure and fecal cultures

The utilization of fructooligosaccharides (FOS) and inulin by 55 Bifidobacterium strains was investigated. Whereas FOS were fermented by most strains, only eight grew when inulin was used as the carbon source. Residual carbohydrates were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection after batch fermentation. A strain-dependent capability to degrade fructans of different lengths was observed. During batch fermentation on inulin, the short fructans disappeared first, and then the longer ones were gradually consumed. However, growth occurred through a single uninterrupted exponential phase without exhibiting polyauxic behavior in relation to the chain length. Cellular beta-fructofuranosidases were found in all of the 21 Bifidobacterium strains tested. Four strains were tested for extracellular hydrolytic activity against fructans, and only the two strains which ferment inulin showed this activity. Batch cultures inoculated with human fecal slurries confirmed the bifidogenic effect of both FOS and inulin and indicated that other intestinal microbial groups also grow on these carbon sources. We observed that bifidobacteria grew by cross-feeding on mono- and oligosaccharides produced by primary inulin intestinal degraders, as evidenced by the high hydrolytic activity of fecal supernatants. FOS and inulin greatly affected the production of short-chain fatty acids in fecal cultures; butyrate was the major fermentation product on inulin, whereas mostly acetate and lactate were produced on FOS.

Separation of growth-stimulating peptides for Bifidobacterium from soybean conglycinin

AIM

To isolate and identify the soybean conglycinin peptides that selectively stimulates the growth of bifidobacteria in vitro, and to investigate the effect of soybean conglycinin peptides on intestinal ecosystem in vivo.

METHODS

Soybean conglycinin was purified from soybean seeds by gel filtration (Sepharose-CL-6B). These proteins were submitted to hydrolysis by pepsin. Several growth-stimulating peptides for bifidobacteria were isolated chromatographically from pepsin hydrolysis of soybean conglycinin and identified by means of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Parallel to in vitro study, in vivo experiments with soybean conglycinin peptides were performed in mice. Ninety male KM mice were randomly assigned into five groups of 16 mice each, and each group was administered for 21d intragastrically with physiological saline (control), conglycinin, pepsin-treated conglycinin (PTC), the most active fraction which isolated from pepsin-treated conglycinin (P2-PTC) and HCl-full hydrolysis of conglycinin (HCl-FHC), respectively. Intestinal microflora were evaluated by standard microbiologic methods and biochemical assays of cecal content samples after treatment.

RESULTS

The results showed that the peptides which were isolated from soybean conglycinin could stimulate the growth of bifidobacteria in vitro, and the molecular mass of purified peptides with MALDI-TOF-MS ranged from 693.32 to 1829.55. Compared with control group, in vivo experiments showed that P2-PTC group decreased cecal pH (7.08+/-0.08 vs 7.21+/-0.09, P<0.05) and enterococci counts (5.38+/-0.26 log10CFU/g vs 5.78+/-0.19 log10CFU/g, P<0.05), significantly increased sIgA level (172.08+/-35.40 ng/g vs 118.27+/-33.93 ng/g, P<0.01) and beta-galactosidase activity (1.28+/-0.23 U/g vs 1.82+/-0.58 U/g, P<0.05).

CONCLUSION

The results have shown that conglycinin is good source for enzyme-mediated production of peptides which stimulate the growth of bifidobacteria. These peptides are inactive within the sequence of the parent protein but can be released during enzymatic hydrolysis, and in vivo experiments demonstrate that conglycinin peptides may be beneficial for improving gastrointestinal health.

Effect of feeding live yeast products to calves with failure of passive transfer on performance and patterns of antibiotic resistance in fecal Escherichia coli

Fifty-two newborn Holstein calves with serum IgG concentrations less than 0.73 g.dL(-1) were randomly assigned to one of four treatments: no added live yeast (control), 0.5 g of live yeast added to the grain for 84 d (SC; Saccharomyces cerevisiae), 0.5 g of live yeast added to the milk for 42 d (SB; S. cerevisiae, spp. boulardii), and 0.5 g of live yeast added to the grain for 84 d and to the milk for 42 d (SCSB). Calves were offered 440 g of milk replacer DM for the first 42 d and grain for ad libitum intake throughout the study. Plasma was analyzed weekly for concentrations of glucose and beta-hydroxybutyrate. Escherichia coli isolated from fecal samples collected every 2 weeks were used for determination of antibiotic resistance patterns. Calves receiving SC consumed more grain DM, had increased weight gain prior to weaning, and increased plasma glucose concentrations compared to controls. Days with diarrhea were reduced by feeding live yeast to calves. Antibiotic resistance in fecal E. coli was associated with the age of calves with highest levels of resistance observed in the 3 d calves. While calves receiving SCSB had higher levels of antibiotic resistance than controls, this effect was not associated with any of the other treatments. Improvements in performance of calves with failure of passive transfer were observed when live yeast was added only to the grain.

Molecular and microbiological analysis of caecal microbiota in rats fed with diets supplemented either with prebiotics or probiotics

The potential health-improving effects of both a prebiotic and a probiotic infant formula have been evaluated in a rat model. Two groups of 10 rats were fed with either prebiotics containing fructo-oligosaccharides or probiotics containing viable Bifidobacterium lactis and Streptococcus thermophilus. The composition of their caecal microbiota was analyzed both by classical plate count of the main bacterial groups and by PCR amplification of a V3 fragment of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE). Both diets induced a significant reduction of clostridia and Bacteroides spp. compared to a control diet, whereas prebiotics were also able to reduce the number of coliforms and to increase the presence of bifidobacteria. DGGE analysis showed a significant increase of 16S rRNA gene fragments in rats fed with either probotics or prebiotics. Nineteen bands were sequenced and most of them showed similarity to cultured bacteria. Detection of Bifidobacterium spp. by this technique using genus-specific primers only permitted these bacteria to be detected in prebiotics-fed rats, whereas the use of Lactobacillus group-specific primers gave similar results in rats fed with any diet, in agreement with the plate count results.