Molecular monitoring of the fecal microbiota of healthy human subjects during administration of lactulose and Saccharomyces boulardii

Enterococcus faecalis: implications for host health

The microbiota represents a crucial area of research in maintaining human health due to its potential for uncovering novel biomarkers, therapies, and molecular mechanisms relevant to population identification and experimental model characterization. Among these microorganisms, Enterococcus faecalis, a Gram-positive bacterium found in the gastrointestinal tract of humans and animals, holds particular significance. Strains of this bacterial species have sparked considerable debate in the literature due to their dual nature; they can either be utilized as probiotics in the food industry or demonstrate resistance to antibiotics, potentially leading to severe illness, disability, and death. Given the diverse characteristics of Enterococcus faecalis strains, this review aims to provide a comprehensive understanding of their impact on various systems within the host, including the immunological, cardiovascular, metabolic, and nervous systems. Furthermore, we summarize the bacterium-host interaction characteristics and molecular effects to highlight their targets, features, and overall impact on microbial communities and host health.

Regulatory effect of lactulose on intestinal flora and serum metabolites in colitis mice: In vitro and in vivo evaluation

Lactulose is a common component in foods. However, the effect of lactulose on intestinal flora and overall metabolic levels remains unclear. Therefore, this study aims to explore the regulative role of lactulose on intestinal flora and serum metabolites via in vitro simulated colonic fermentation model and in vivo colitis mouse model. The results showed that lactulose significantly enriched beneficial bacteria including Dubosiella and Bifidobacterium, and reduced pathogenic bacteria such as Fusobacterium. Moreover, lactulose significantly inhibited dextran sodium sulfate-induced body weight loss, colon shortening, colonic inflammatory infiltration, and pro-inflammatory cytokines IL-6, TNF-α, IL-17, and IL-1β. Lactulose significantly affected serum metabolome in colitis mice and total 24 metabolites representing a high inter-group difference were obtained. Correlation analysis revealed that the changes in serum metabolites were closely associated with the role of intestinal flora, and thus affected phenotypic indicators. Our study provides a reference for nutritional characteristics and application scenarios of dietary lactulose.

Recent developments in the production and utilization of photosynthetic microorganisms for food applications

The growing use of photosynthetic microorganisms for food and food-related applications is driving related biotechnology research forward. Increasing consumer acceptance, high sustainability, demand of eco-friendly sources for food, and considerable global economic concern are among the main factors to enhance the focus on the novel foods. In the cases of not toxic strains, photosynthetic microorganisms not only provide a source of sustainable nutrients but are also potentially healthy. Several published studies showed that microalgae are sources of accessible protein and fatty acids. More than 400 manuscripts were published per year in the last 4 years. Furthermore, industrial approaches utilizing these microorganisms are resulting in new jobs and services. This is in line with the global strategy for bioeconomy that aims to support sustainable development of bio-based sectors. Despite the recognized potential of the microalgal biomass value chain, significant knowledge gaps still exist especially regarding their optimized production and utilization. This review highlights the potential of microalgae and cyanobacteria for food and food-related applications as well as their market size. The chosen topics also include advanced production as mixed microbial communities, production of high-value biomolecules, photoproduction of terpenoid flavoring compounds, their utilization for sustainable agriculture, application as source of nutrients in space, and a comparison with heterotrophic microorganisms like yeast to better evaluate their advantages over existing nutrient sources. This comprehensive assessment should stimulate further interest in this highly relevant research topic.

Effect of Probiotic Fungi against Cognitive Impairment in Mice via Regulation of the Fungal Microbiota-Gut-Brain Axis

The fungal microbiota may be involved in the regulation of cognition and behavior, while the role of probiotic fungi against cognitive impairment is unclear. Here, we explored the idea that probiotic Saccharomyces boulardii could participate in the regulation of microglia-induced neuroinflammation in Alzheimer's disease (AD) model mice. Cognitive deficits, deposits of amyloid-β (Aβ) and phosphorylation of tau, synaptic plasticity, microglia activation, and neuroinflammatory reactions were observed. The expression levels of Toll-like receptors (TLRs) pathway-related proteins were detected. Meanwhile, intestinal barrier integrity and fungal microbiota composition were evaluated. Our results showed fungal microbiota dysbiosis in APP/PS1 mice, which might result in the neuroinflammation of AD. The increased levels of interleukin (IL)-6, IL-1β, and cluster of differentiation 11b (CD11b) were observed in APP/PS1 mice, which were associated with activation of microglia, indicative of a broader recognition of neuroinflammation mediated by fungal microbiota compared to hitherto appreciated. Probiotic S. boulardii treatment improved dysbiosis, alleviated the neuroinflammation as well as synaptic injury, and ultimately improved cognitive impairment. Moreover, S. boulardii therapy could inhibit microglia activation and the TLRs pathway, which were reversed by antifungal treatment. These findings revealed that S. boulardii actively participated in regulating the TLRs pathway to inhibit the neuroinflammation via the gut-brain axis.

Recovery of gut microbiota in mice exposed to tetracycline hydrochloride and their correlation with host metabolism

Antibiotics can disturb the gut microbial community and host metabolism. However, their recovery after antibiotics exposure needs to be characterized, and the correlation between gut microbiota and host metabolism remains unclear. In this study, mice were exposed to 0.5, 1.5 and 10 g/L tetracycline hydrochloride (TET) for 2 weeks, then recovered without TET for another 2 weeks. The results showed that 2-week TET exposure changed microbial community and functions in the mouse gut, and increased abundance of antibiotic resistance genes (ARGs), especially in the 10 g/L TET group. After a 2-week recovery, these changes could only be recovered to the control level in the 0.5 g/L TET exposure group, except for ARGs. Besides gut microbiota, TET exposure also changed metabolic profiles in mouse urine. The 2-week recovery significantly reduced changes in metabolic profiles. Some altered metabolites were found to have a very high correlation with gut microbial community and functions, indicating that TET exposure might induce certain changes in urinary metabolic profiles by altering the gut microbiota. The results from this study suggest that the influences of low-level TET exposure are reversible, except for ARGs, which should be paid more attention. During the application of TET, their dosage should be effectively considered and controlled.

Characterization of the blood and neutrophil-specific microbiomes and exploration of potential bacterial biomarkers for sepsis in surgical patients

Introduction

Recent studies have demonstrated the presence of a circulating microbiome in the blood of healthy subjects and chronic inflammatory patients. However, our knowledge regarding the blood microbiome and its potential roles in surgical patients remains very limited. The objective of this study was to determine the blood microbial landscape in surgical patients and to explore its potential associations with postoperative sepsis.

Materials and Methods

2825 patients who underwent surgical treatments were screened for enrollment and 204 cases were recruited in this study. The patients were sub‐grouped into noninfected, infected, sepsis, and septic shock according to postoperative clinical manifestations. A total of 222 blood samples were obtained for neutrophil isolation, DNA extraction and high‐throughput sequencing, quantitative proteomics analysis, and flow cytometric analyses.

Results

Blood and neutrophils in surgical patients and healthy controls contained highly diverse microbiomes, mainly comprising Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. The majority (80.7%–91.5%) of the microbiomes were composed of gut‐associated bacteria. The microbiomes in septic patients were significantly distinct from those of healthy controls, and marked differences in microbiome composition were observed between sepsis and septic shock groups. Several specific bacterial genera, including Flavobacterium, Agrococcus, Polynucleobacter, and Acidovorax, could distinguish patients with septic shock from those with sepsis, with higher area under curve values. Moreover, Agrococcus, Polynucleobacter, and Acidovorax were positively associated with the sequential (sepsis‐related) organ failure assessment scores and/or acute physiology and chronic health examination scores in septic shock patients. The proteins involved in bactericidal activities of neutrophils were downregulated in septic patients.

Conclusions

We present evidence identifying significant changes of blood and neutrophil‐specific microbiomes across various stages of sepsis, which might be associated with the progression of sepsis after surgical treatments. Several certain bacterial genera in blood microbiome could have potential as microbial markers for early detection of sepsis.

Saccharomyces boulardii ameliorates gut dysbiosis associated cognitive decline

Saccharomyces boulardii, a probiotic yeast is well prescribed for various gastrointestinal disorders accompanied by gut dysbiosis such as inflammatory bowel disease, bacterial diarrhea and antibiotic associated diarrhea. Gut dysbiosis has been associated with central nervous system via gut brain axis primarily implied in the modulation of psychiatric conditions. In the current study we use Saccharomyces boulardii as a therapeutic agent against gut dysbiosis associated cognitive decline. In mice, gut dysbiosis was induced by oral Ampicillin Na (250 mg/kg twice-daily) for 14 days. While in the treatment group S. boulardii (90 mg/kg once a day) was administered orally for 21 days along with 14 days of antibiotic treatment. Gene expression studies revealed antibiotic mediated decrease in the Lactobacillus, Bifidobacterium, Firmicutes and Clostridium which were restored by S. boulardii treatment. Cognitive behavioral studies showed a parallel reduction in fear conditioning, spatial as well as recognition memory which were reversed upon S. boulardii treatment in these animals. S. boulardii treatment reduced myeloperoxidase enzyme, an inflammatory marker, in colon as well as brain which was increased after antibiotic administration. Similarly, S. boulardii reduced the brain acetylcholine esterase, oxidative stress and inflammatory cytokines and chemokines which were altered due to antibiotic treatment. S. boulardii treatment also protected hippocampal neuronal damage and restored villus length and crypt depth thus normalizing gut permeability in antibiotic treated animals. Hence, we conclude that S. boulardii prevented antibiotic associated gut dysbiosis leading to reduced intestinal and brain inflammation and oxidative stress thus preventing hippocampal neuronal damage and eventually reversing gut dysbiosis associate cognitive decline in mice.

Lactulose ingestion causes an increase in the abundance of gut-resident bifidobacteria in Japanese women: a randomised, double-blind, placebo-controlled crossover trial

The genus Bifidobacterium comprises various bacterial species, and the complement of species within the human intestinal tract differs from individual to individual. The balance of these bifidobacterial species remains poorly understood, although it is known that the abundance of bifidobacteria increases following the ingestion of prebiotics. We previously conducted a randomised, placebo-controlled, double-blind, crossover study of 2 g/day lactulose ingestion for 2 weeks in 60 Japanese women. To study the effect of lactulose ingestion on each bifidobacterial species, here, we measured the abundance of each of the principal bifidobacterial species. After lactulose ingestion, the log cell counts of the Bifidobacterium adolescentis group (8.97±0.08 vs 9.39±0.08, P=0.0019), Bifidobacterium catenulatum group (9.45±0.10 vs 9.65±0.10, P=0.0032) and Bifidobacterium longum group (9.01±0.07 vs 9.29±0.07, P=0.0012) were significantly higher than in the placebo ingestion control group. However, the log cell counts were similar for Bifidobacterium breve (8.12±0.12 vs 8.33±0.12, P=0.20), Bifidobacterium bifidum (9.08±0.12 vs 9.42±0.14, P=0.095) and Bifidobacterium animalis subspecies lactis (8.65±0.53 vs 8.46±0.46, P=0.77). Cluster analysis of the log cell count data at the bifidobacterial species level revealed three distinct clusters, but the combinations and ratios of the constituent bifidobacteria were not affected by lactulose ingestion. Furthermore, principal coordinate analysis of the intestinal microbiota in the lactulose and placebo ingestion groups using Illumina MiSeq showed no significant differences in the intestinal microbiota as a whole. These results suggest that 2 g/day lactulose ingestion for 2 weeks significantly increases the abundance of intestinal bifidobacteria, but does not affect the intestinal microbiota as a whole.

Nonpharmacologic Management of Hepatic Encephalopathy: An Update

Research increasingly shows that the gut-liver-brain axis is a crucial component in the pathophysiology of hepatic encephalopathy (HE). Due to the limitations of current standard-of-care medications, non-pharmacological treatments that target gut dysbiosis, including probiotics, nutritional management, and fecal microbiota transplants, are being considered as alternative and adjunct therapies. Meta-analyses note that probiotics could offer benefits in HE treatment, but have not shown superiority over lactulose. Emerging literature suggests that fecal microbiota transplants could offer a novel strategy to treat gut dysbiosis and favorably impact HE. Finally, liver support devices and liver transplantation could offer a last-resort treatment option for persistent HE.

Yeasts as probiotics: Mechanisms, outcomes, and future potential

The presence of commensal fungal species in the human gut indicates that organisms from this kingdom have the potential to benefit the host as well. Saccharomyces boulardii, a yeast strain isolated about a hundred years ago, is the most well-characterized probiotic yeast. Though for the most part it genetically resembles Saccharomyces cerevisiae, specific phenotypic differences make it better suited for the gut microenvironment such as better acid and heat tolerance. Several studies using animal hosts suggest that S. boulardii can be used as a biotherapeutic in humans. Clinical trials indicate that it can alleviate symptoms from gastrointestinal (GI) tract infections to some extent, but further trials are needed to understand the full therapeutic potential of S. boulardii. Improvement on probiotic function using engineered yeast is an attractive future direction, though genome modification tools for use in S. boulardii have been limited until recently. However, some tools available for S. cerevisiae should be applicable for S. boulardii as well. In this review, we summarize the observed probiotic effect of this yeast and the state of the art for genome engineering tools that could help enhance its probiotic properties.

Evaluation of the Bacterial Diversity of Inner Mongolian Acidic Gruel Using Illumina MiSeq and PCR-DGGE

As a traditional fermented cereal, Inner Mongolian acidic gruel has a unique flavor and rich nutrition, but the microbial diversity of acidic gruel and the microbial differences among the products in different regions have not been reported. The bacterial diversity and the lactic acid bacteria species of 27 types of traditional handmade acidic gruel were evaluated using a combination of MiSeq high-throughput sequencing and PCR-DGGE. All 358,205 high-quality 16S rRNA reads were divided into 25,171 OTUs under the similarity of 97%. Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla, and the core dominant genera were Lactobacillus and Acetobacter with average relative abundances of 64.06% and 24.13%, respectively. The primary genera that caused the differences in the bacterial community structure between the Bayan Nur and Ordos acidic gruel samples were Pseudomonas, Leuconostoc, and Acinetobacter as revealed by redundancy analysis (RDA). PCR-DGGE analyses revealed that the lactic acid bacteria in both the Bayan Nur and Ordos samples of acidic gruel were Lactobacillus (L.) amylolyticus, L. alimentarius, L. fermentum, L. hamsteri, L. helveticus, L. panis, L. plantarum, L. pontis, and Leuconostoc lactis. In addition, L. hamsteri was the core strain detected among all the samples. The results deepened the understanding of the microbial community composition and the diversity of acidic gruel to provide a theoretical basis for the preservation and protection of microbial resources in acidic gruel in the Inner Mongolia area.

Lactulose drives a reversible reduction and qualitative modulation of the faecal microbiota diversity in healthy dogs

Hepatic encephalopathy is a frequent and debilitating complication of liver disorders. Lactulose is an established and reasonably effective treatment, yet with incompletely understood mechanisms of action. The aims of this study were to examine how the faecal microbiota composition changed before, during and after lactulose treatment in a large animal model. Healthy, privately owned dogs (n = 18) completed a prospective cohort study. Faecal samples were collected weekly, while the subjects were either on their usual diet (week 1), or a standardised diet (weeks 2-9), with added oral lactulose in weeks 6-7. DNA extraction and 16S rRNA gene sequencing were undertaken. Faecal samples from week 7 had a significantly lower microbiota richness/diversity, based on observed operational taxonomic units, Shannon/Chao1 indexes and Pielou's Evenness. Beta diversity based on UniFrac distances was significantly different in week 7 compared to weeks 1, 5 and 9. At the phylum level, week 7 was associated with a significant increase of Firmicutes and Actinobacteria, and a decrease of Bacteroidetes and Fusobacteria, when compared to weeks 5 and 9. In summary, we have shown that lactulose induces a reversible qualitative and quantitative change of the faecal microbiota, which may explain its clinical efficacy in the management of hepatic encephalopathy.

Targeting the Gut Microbiota to Investigate the Mechanism of Lactulose in Negating the Effects of a High-Salt Diet on Hypertension

SCOPE

High-salt diets (HSDs) are widely considered to cause health problems such as gut microecological imbalances, constipation, and hypertension. This study explores how lactulose as a safe molecule can stimulate bodily responses to alleviate salt-sensitive hypertension by regulating the gut microbiotas of HSD-fed mice.

METHODS AND RESULTS

After 4 weeks, the blood pressures of mice fed a high-salt plus lactulose diet (HSLD) are significantly lower than those of the HSD-fed mice. The HSD increases the abundances of Alistipes and Ruminococcaceae_UCG_009 and reduced the abundance of Lactobacillus in the gut, while lactulose supplementation increases the abundances of Bifidobacterium, Alloprevotella, and Subdoligranulum. Fecal metabolic profiling shows significant increases in metabolites involved in ATP-binding cassette transporter pathways, and tryptophan metabolism is significantly reduced in the HSLD group compared with the HSD group. Lactulose maintains the intestinal microenvironmental health in the HSD-fed mice by improving glycolipid metabolism, decreasing the small intestinal interleukin-17a (IL-17a) and interleukin-22 (IL-22) mRNA levels and serum IL-17a and IL-22 levels, relieving constipation, increasing fecal sodium, and reducing intestinal permeability.

CONCLUSION

Lactulose negates salt-sensitive hypertension. Regulating the gut microbiota is a potential treatment for salt-sensitive hypertension.

Altered Microbiome in Patients With Cirrhosis and Complications

In patients with cirrhosis, the gut microbiome are affected by multiple gut and systemic alterations. These changes lead to dysbiosis in the microbiota of different parts of the body, resulting in inflammation. The constant immune stimulation resulting in part from dysbiosis is associated with morbidity in patients with cirrhosis. Dysbiosis as a dynamic event worsens with decompensation such as with hepatic encephalopathy, infections or acute-on-chronic liver failure (ACLF). These microbial patterns could be applied as diagnostic and prognostic measures in cirrhosis in the outpatient and inpatient setting. Current therapies for cirrhosis have differing impacts on gut microbial composition and functionality. Dietary modifications and the oral cavity have emerged as newer targetable factors to modulate the microbiome, which could affect inflammation and, potentially improve outcomes. Additionally, fecal microbial transplant is being increasingly studied to provide compositional and functional modulation of the microbiome. Ultimately, a combination of targeted therapies may be needed to provide an optimal gut milieu to improve outcomes in cirrhosis.

A study of the prebiotic effect of lactulose at low dosages in healthy Japanese women

To investigate the prebiotic effect of lactulose at low dosages, we assessed changes in defaecation frequency following ingestion of 1, 2, or 3 g/day of lactulose for 2 weeks. Each test was carried out after a 2-week washout period. This was an open-label, before-after trial that enrolled 26 healthy Japanese women. The defaecation frequency, number of defaecation days, and number of faecal bifidobacteria increased significantly compared with before ingestion of 1, 2, and 3 g/day of lactulose. These results suggest that even 1 g/day of lactulose could have a prebiotic effect.

Microbiome and bile acid profiles in duodenal aspirates from patients with liver cirrhosis: The Microbiome, Microbial Markers and Liver Disease Study

AIM

Cirrhosis is a leading cause of death worldwide, yet there are no well-established risk stratifying tools for lethal complications, including hepatocellular carcinoma (HCC). Patients with liver cirrhosis undergo routine endoscopic surveillance, providing ready access to duodenal aspirate samples that could be a source for identifying novel biomarkers. The aim of this study was to characterize the microbiome and bile acid profiles in duodenal aspirates from patients with liver cirrhosis to assess the feasibility of developing biomarkers for HCC risk stratification.

METHODS

Thirty patients with liver cirrhosis were enrolled in the Microbiome, Microbial Markers, and Liver Disease study between May 2015 and March 2017. Detailed clinical and epidemiological data were collected at baseline and at 6-monthly follow-up visits. Duodenal aspirate fluid was collected at baseline for microbial characterization using 16S ribosomal RNA sequencing and bile acid quantification using mass spectroscopy.

RESULTS

Alcohol-related cirrhosis was associated with reductions in the Bacteroidetes phylum, particularly Prevotella (13-fold reduction), and expansion of Staphylococcus (13-fold increase), compared to hepatitis C virus-related cirrhosis. Participants with hepatic encephalopathy (HE) had less microbial diversity compared to patients without HE (P < 0.05), and were characterized by expansion of Mycobacterium (45-fold increase) and Gram-positive cocci including Granulicatella (3.1-fold increase), unclassified Planococcaceae (3.3-fold increase), and unclassified Streptococcaceae (4.5-fold increase). Non-Hispanic White patients had reduced microbial richness (P < 0.01) and diversity (P < 0.05), and increased levels of conjugated ursodeoxycholic acid (glycoursodeoxycholic acid and tauroursodeoxycholic acid, P < 0.05) compared to Hispanic patients.

CONCLUSION

Microbial profiles of duodenal aspirates differed by cirrhosis etiology, HE, and Hispanic ethnicity.

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).

Effect of lactulose intervention on gut microbiota and short chain fatty acid composition of C57BL/6J mice

Gut microbiota have strong connections with health. Lactulose has been shown to regulate gut microbiota and benefit host health. In this study, the effect of short‐term (3 week) intervention of lactulose on gut microbiota was investigated. Gut microbiota were detected from mouse feces by 16S rRNA high‐throughput sequencing, and short chain fatty acids (SCFAs) were detected by gas chromatography‐mass spectrometry (GC‐MS). Lactulose intervention enhanced the α‐diversity of the gut microbiota; increased the abundance of hydrogen‐producing bacteria Prevotellaceae and Rikenellaceae, probiotics Bifidobacteriaceae and Lactobacillaceae, and mucin‐degrading bacteria Akkermansia and Helicobacter; decreased the abundance of harmful bacteria Desulfovibrionaceae and branched‐chain SCFAs (BCFAs). These results suggest that lactulose intervention effectively increased the diversity and improved the structure of the intestinal microbiota, which may be beneficial for host health.

The Role of Supplemental Complex Dietary Carbohydrates and Gut Microbiota in Promoting Cardiometabolic and Immunological Health in Obesity: Lessons from Healthy Non-Obese Individuals

Dietary supplementation with complex carbohydrates is known to alter the composition of gut microbiota, and optimal implementation of the use of these so called "prebiotics" could be of great potential in prevention and possibly treatment of obesity and associated cardiometabolic and inflammatory diseases via changes in the gut microbiota. An alternative to this "microbiocentric view" is the idea that health-promoting effects of certain complex carbohydrates reside in the host, and could secondarily affect the diversity and abundance of gut microbiota. To circumvent this potential interpretational problem, we aimed at providing an overview about whether and how dietary supplementation of different complex carbohydrates changes the gut microbiome in healthy non-obese individuals. We then reviewed whether the reported changes in gut bacterial members found to be established by complex carbohydrates would benefit or harm the cardiometabolic and immunological health of the host taking into account the alterations in the microbiome composition and abundance known to be associated with obesity and its associated disorders. By combining these research areas, we aimed to give a better insight into the potential of (foods containing) complex carbohydrates in the treatment and prevention of above-mentioned diseases. We conclude that supplemental complex carbohydrates that increase Bifidobacteria and Lactobacilli, without increasing the deleterious Bacteroides, are most likely promoting cardiometabolic and immunological health in obese subjects. Because certain complex carbohydrates also affect the host's immunity directly, it is likely that host-microbiome interactions in determination of health and disease characteristics are indeed bidirectional. Overall, this review article shows that whereas it is relatively clear in which direction supplemental fermentable carbohydrates can alter the gut microbiome, the relevance of these changes regarding health remains controversial. Future research should take into account the different causes of obesity and its adverse health conditions, which in turn have drastic effects on the microbiome balance.

Prebiotics and synbiotics in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon with unclear pathogenesis. A dysbiotic intestinal microbiota is regarded as a key component in the disease process and there has been significant interest in developing new treatments which target the microbiota.

AIM

To give an overview of the studies to date investigating prebiotics and synbiotics for the treatment of UC.

METHODS

A literature search of PubMed and related search engines was carried out using the terms "ulcerative colitis" in combination with "prebiotic", "synbiotic" or "dietary fibre".

RESULTS

In total 17 studies on humans examining the effect of prebiotics in UC were found. Five major groups could be distinguished. Fructo-oligosaccharides were tried in six studies (mean 35 patients included, range 9-121). One study found a clinical response while two demonstrated indirect evidence of an effect. Germinated barley foodstuff was used in 8 studies (mean 38 patients, range 10-63). One study found an endoscopic response, while four noted a clinical response and two some indirect effects. Galacto-oligosaccharides, lactulose and resveratrol were used in one study each (mean 48 patients, range 41-52). One study found an endoscopic response and one a clinical response.

CONCLUSION

There is yet inadequate evidence - especially in humans - to support any particular prebiotic in the clinical management of UC. However, due to the bulk of evidence supporting the effect of the microbiota on colonic inflammation, there is enough potential to justify further high-quality clinical trials investigating this subject.

New insights into the pathogenesis and treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders (FGID), characterized by abdominal pain and a change in stool form that cannot be explained by structural abnormalities. Its prevalence ranges from 9 to 23% of the worldwide population. The pathophysiology of IBS is diverse and not well understood. Biopsychosocial concept assumes that the disease is a product of psychosocial factors and altered at multiple levels of gut physiology interactions. Some aetiological factors have been identified, yet. One of the most important is the disruption of brain-gut mutual communication that leads to visceral hypersensitivity. Also genetic and epigenetic factors are involved. Chronic stress may predispose to IBS as well as exacerbate its symptoms. Both quantitative and qualitative disorders of the gut microbiota are observed. There is also a relationship between the IBS symptoms and the intake of a specific type of food products. In the diarrhoea type of IBS the role of previous gastrointestinal infection is demonstrated. Recent studies have suggested that visceral hypersensitivity in patients with IBS may be secondary to the activation of the immune cells and low-grade inflammation. Clinical symptoms of IBS include abdominal pain and change in bowel habits as well as somatic and psychiatric comorbidities. IBS is diagnosed on the basis of Rome Diagnostic Criteria. Recently, their newest version (Rome IV) has been presented. The aim of this review is to summarize the past decade progress in IBS diagnosis, main pathophysiological aspects and therapeutic management strategy.

Intestinal Proportion of Blautia sp. is Associated with Clinical Stage and Histoprognostic Grade in Patients with Early-Stage Breast Cancer

Improving knowledge about breast cancer etiology is crucial in order to propose prevention strategies for this pathology. Gut microbiota is involved in numerous physiopathological situations including cancers. Although its potential involvement in breast cancer through the alteration of the enterohepatic circulation of estrogens and/or the metabolism of phytoestrogens has been discussed for some time, it remains to be demonstrated. The present study seeks to strengthen this hypothesis by identifying possible links between the fecal microbiota composition and clinical characteristics in breast cancer patients. Bacterial DNA was extracted from the feces of 31 patients with early-stage breast cancer and amplified by real-time polymerase chain reaction (qPCR), targeting 16S rRNA sequences specific to bacterial groups, and then analyzed in relation to clinical characteristics. The absolute numbers of total bacteria and of three bacterial groups (Firmicutes, Faecalibacterium prausnitzii, and Blautia) differed significantly according to the patient's body mass index. The percentage and the absolute numbers of certain bacterial groups, namely C. coccoides, F. prausnitzii, and Blautia, differed significantly according to the clinical stages and the histoprognostic grades. Our study highlighted that intestinal microbiota composition in these patients differs according to clinical characteristics and BMI. Further studies are required to clarify the link between breast cancer and intestinal microbiota.

Environmental Enteric Dysfunction Is Associated With Poor Linear Growth and Can Be Identified by Host Fecal mRNAs

OBJECTIVE

Environmental enteric dysfunction (EED) can be assessed by the lactulose:mannitol (L:M) test. Our objective was to determine if selected host fecal transcripts were correlated with EED, and whether transcripts and clinical characteristics could be used to predict EED in rural African children.

METHODS

Demographic and sanitation characteristics, along with L:M testing and host fecal transcript analyses from 798 asymptomatic Malawian children aged 12 to 61 months were compared with linear growth over the subsequent 3 months. Fecal host mRNA analysis included quantification of expression of 18 transcripts associated with L:M. Permeability was categorized as normal (L:M ≤ 0.15), moderate (0.15<L:M<0.45) and severe (L:M ≥ 0.45), and random forest predictive models were created.

RESULTS

L:M was inversely correlated with linear growth over the subsequent 3 months (r = -0.32, P < 0.001) and severe EED was associated with stunting (P < 0.0001). Age younger than 24 months, weight-for-height z score <0, domesticated animals in the child's sleep environment, lack of a pit latrine combined with a potentially contaminated water source, and a recent history of diarrhea were associated with severe EED. A random forest model using CD53, HLA-DRA, MUC12, and TNF was 84% sensitive for severe EED and 83% sensitive for no EED.

CONCLUSIONS

Selected host fecal transcripts can be used in a random forest model as a noninvasive biomarker for categories of EED in rural African children.

Lactulose Differently Modulates the Composition of Luminal and Mucosal Microbiota in C57BL/6J Mice

In this study, C57BL/6J mice were fed diets supplemented with different proportions of lactulose (0%, 5%, and 15%) for 2 weeks to study its effects on the luminal and mucosal microbiota. The luminal and mucosal samples of cecum and colon were investigated. After high-lactulose treatment (15%), pH of the luminal contents decreased from 6.90-7.72 to 5.95-6.21 from the cecum to distal colon, and the amount of total short-chain fatty acids in the cecum was significantly increased. The luminal content was mostly dominated by Firmicutes, Actinobacteria, and Bacteroidetes, while the mucus was dominated by Firmicutes, Proteobacteria, and Bacteroidetes. The abundance of Actinobacteria was significantly increased in the content, and Proteobacteria was the most abundant phylum (∼50%) in the mucus after high-lactulose treatment. At the genus level, Bifidobacterium and Akkermansia were both significantly increased in the content, and Helicobacter was the most abundant in the mucus.

The effect of lactulose supplementation on fecal microflora of patients with chronic kidney disease; a randomized clinical trial

Introduction: Lactulose is a prebiotic with bifidogenic and urea reduction effects. It can improve Bifidobacteria and Lactobacilli counts in healthy humans and it may possibly have similar effects in chronic kidney disease (CKD) patients.

Objectives: To investigate the effect of lactulose on fecal microflora of patients with CKD.

Patients and Methods: Thirty-two patients with stages 3 and 4 of CKD (43.8% male with mean age of 58.09±12.75 years) were randomly assigned to intervention (n=16) and control (n=16) groups. Patients in intervention group received 30 mm lactulose syrup three times a day for an 8-week period. Control group received placebo 30 mm three times a day. A fecal sample was obtained from all patients at the beginning and at the end of the study and Bifidobacteria and Lactobacilli was counted.

Results: Creatinine (Cr) significantly decreased in intervention group (3.90±1.43 to 3.60±1.44, P=0.003) and increased in control group (3.87±2.08 to 4.11±1.99, P=0.03). Although Bifidobacterial and Lactobacilli counts were similar before intervention, they were significantly higher at the end of the study in lactulose group (P=0.01 and P=0.04, respectively). Lactulose led to significant increase in fecal Bifidobacterial counts (3.61±0.54 to 4.90±0.96, P<0.001) and Lactobacilli counts (2.79±1.00 to 3.87±1.13, P<0.001), while the change in placebo group was not significant.

Conclusion: Lactulose administration will increase Bifidobacteria and Lactobacillus counts in patients with CKD.

Importance of gut microbiota in health and diseases of new born infants

The multifarious assortment of microorganisms present in gut of humans is termed as gut microbiota. These include 1,000 species accompanied by approximately 2 million genes in an individual adult. The gut microbiota has multifactorial protective roles against allergic reactions, inflammation, cardiac pathological states and even in the state of malignant carcinogenesis existing in humans. By contrast, adverse alterations in the microbiota result in chronic pathological states, including autoimmune diseases, cancer and circulatory system obstructions. Gut bacteria also maintain sensitivity towards nutritional changes as well as antibiotics. The present review article focused on the importance of gut bacteria in newborn infants with special reference to their protective role in various pediatric pathological states linked with gut bacteria. In addition, the importance of probiotics in relation to gut microbiota are to be discussed.

Metagenomic insights into tetracycline effects on microbial community and antibiotic resistance of mouse gut

Antibiotics have been widely used for disease prevention and treatment of the human and animals, and for growth promotion in animal husbandry. Antibiotics can disturb the intestinal microbial community, which play a fundamental role in animals' health. Misuse or overuse of antibiotics can result in increase and spread of microbial antibiotic resistance, threatening human health and ecological safety. In this study, we used Illumina Hiseq sequencing, (1)H nuclear magnetic resonance spectroscopy and metagenomics approaches to investigate intestinal microbial community shift and antibiotic resistance alteration of the mice drinking the water containing tetracycline hydrochloride (TET). Two-week TET administration caused reduction of gut microbial diversity (from 194 to 89 genera), increase in Firmicutes abundance (from 24.9 to 39.8%) and decrease in Bacteroidetes abundance (from 69.8 to 51.2%). Metagenomic analysis showed that TET treatment affected the intestinal microbial functions of carbohydrate, ribosomal, cell wall/membrane/envelope and signal transduction, which is evidenced by the alteration in the metabolites of mouse serum. Meanwhile, in the mouse intestinal microbiota, TET treatment enhanced the abundance of antibiotic resistance genes (ARGs) (from 307.3 to 1492.7 ppm), plasmids (from 425.4 to 3235.1 ppm) and integrons (from 0.8 to 179.6 ppm) in mouse gut. Our results indicated that TET administration can disturb gut microbial community and physiological metabolism of mice, and increase the opportunity of ARGs and mobile genetic elements entering into the environment with feces discharge.

Dynamic In Vitro Models of the Human Gastrointestinal Tract as Relevant Tools to Assess the Survival of Probiotic Strains and Their Interactions with Gut Microbiota

The beneficial effects of probiotics are conditioned by their survival during passage through the human gastrointestinal tract and their ability to favorably influence gut microbiota. The main objective of this study was to use dynamic in vitro models of the human digestive tract to investigate the effect of fasted or fed state on the survival kinetics of the new probiotic Saccharomyces cerevisiae strain CNCM I-3856 and to assess its influence on intestinal microbiota composition and activity. The probiotic yeast showed a high survival rate in the upper gastrointestinal tract whatever the route of admistration, i.e., within a glass of water or a Western-type meal. S. cerevisiae CNCM I-3856 was more sensitive to colonic conditions, as the strain was not able to colonize within the bioreactor despite a twice daily administration. The main bacterial populations of the gut microbiota, as well as the production of short chain fatty acids were not influenced by the probiotic treatment. However, the effect of the probiotic on the gut microbiota was found to be individual dependent. This study shows that dynamic in vitro models can be advantageously used to provide useful insight into the behavior of probiotic strains in the human digestive environment.

Salivary microbiota reflects changes in gut microbiota in cirrhosis with hepatic encephalopathy

Altered gut microbiome is associated with systemic inflammation and cirrhosis decompensation. However, the correlation of the oral microbiome with inflammation in cirrhosis is unclear. Our aim was to evaluate the oral microbiome in cirrhosis and compare with stool microbiome. Outpatients with cirrhosis (with/without hepatic encephalopathy [HE]) and controls underwent stool/saliva microbiome analysis (for composition and function) and also systemic inflammatory evaluation. Ninety-day liver-related hospitalizations were recorded. Salivary inflammation was studied using T helper 1 cytokines/secretory immunoglobulin A (IgA), histatins and lysozyme in a subsequent group. A total of 102 patients with cirrhosis (43 previous HE) and 32 age-matched controls were included. On principal component analysis (PCA), stool and saliva microbiome clustered far apart, showing differences between sites as a whole. In salivary microbiome, with previous HE, relative abundance of autochthonous families decreased whereas potentially pathogenic ones (Enterobacteriaceae, Enterococcaceae) increased in saliva. Endotoxin-related predicted functions were significantly higher in cirrhotic saliva. In stool microbiome, relative autochthonous taxa abundance reduced in previous HE, along with increased Enterobacteriaceae and Enterococcaceae. Cirrhotic stool microbiota demonstrated a significantly higher correlation with systemic inflammation, compared to saliva microbiota, on correlation networks. Thirty-eight patients were hospitalized within 90 days. Their salivary dysbiosis was significantly worse and predicted this outcome independent of cirrhosis severity. Salivary inflammation was studied in an additional 86 age-matched subjects (43 controls/43 patients with cirrhosis); significantly higher interleukin (IL)-6/IL-1β, secretory IgA, and lower lysozyme, and histatins 1 and 5 were found in patients with cirrhosis, compared to controls.

CONCLUSIONS

Dysbiosis, represented by reduction in autochthonous bacteria, is present in both saliva and stool in patients with cirrhosis, compared to controls. Patients with cirrhosis have impaired salivary defenses and worse inflammation. Salivary dysbiosis was greater in patients with cirrhosis who developed 90-day hospitalizations. These findings could represent a global mucosal-immune interface change in cirrhosis.

Saccharomyces boulardii CNCM I-745 supports regeneration of the intestinal microbiota after diarrheic dysbiosis - a review

The probiotic medicinal yeast Saccharomyces cerevisiae HANSEN CBS 5926 (Saccharomyces boulardii CNCM I-745) is used for the prevention and treatment of diarrhea. Its action is based on multiple mechanisms, including immunological effects, pathogen-binding and antitoxinic effects, as well as effects on digestive enzymes. Correlated with these effects, but also due to its inherent properties, S. boulardii is able to create a favorable growth environment for the beneficial intestinal microbiota, while constituting extra protection to the host mucus layer and mucosa. This review focuses on the positive influence of S. boulardii on the composition of the intestinal microbiota. In a dysbiosis, as during diarrhea, the main microbial population (especially Lachnospiraceae, Ruminococcaceae, Bacteroidaceae, and Prevotellaceae) is known to collapse by at least one order of magnitude. This gap generally leads to transient increases in pioneer-type bacteria (Enterobacteriaceae, Bifidobacteriaceae, and Clostridiaceae). Several human studies as well as animal models demonstrate that treatment with S. boulardii in dysbiosis leads to the faster reestablishment of a healthy microbiome. The most relevant effects of S. boulardii on the fecal composition include an increase of short chain fatty acid-producing bacteria (along with a rise in short chain fatty acids), especially of Lachnospiraceae and Ruminococcaceae, as well as an increase in Bacteroidaceae and Prevotellaceae. At the same time, there is a suppression of pioneer bacteria. The previously observed preventive action of S. boulardii, eg, during antibiotic therapy or regarding traveler’s diarrhea, can be explained by several mechanisms, including a stabilizing effect on the healthy microbiota as well as possibly on the mucus layer. Several different dysbiotic situations could profit from the effects of S. boulardii CNCM I-745. Its additional potential lies in a general stabilization of the gut flora for at-risk populations. More studies are needed to explore the full potential of this versatile probiotic yeast.

New approaches for bacteriotherapy: prebiotics, new-generation probiotics, and synbiotics

The gut microbiota has a significant role in human health and disease. Dysbiosis of the intestinal ecosystem contributes to the development of certain illnesses that can be reversed by favorable alterations by probiotics. The published literature was reviewed to identify scientific data showing a relationship between imbalance of gut bacteria and development of diseases that can be improved by biologic products. The medical conditions vary from infectious and antibiotic-associated diarrhea to obesity to chronic neurologic disorders. A number of controlled clinical trials have been performed to show important biologic effects in a number of these conditions through administration of prebiotics, probiotics, and synbiotics. Controlled clinical trials have identified a limited number of prebiotics, probiotic strains, and synbiotics that favorably prevent or improve the symptoms of various disorders including inflammatory bowel disease, irritable bowel syndrome, infectious and antibiotic-associated diarrhea, diabetes, nonalcoholic fatty liver disease, necrotizing enterocolitis in very low birth weight infants, and hepatic encephalopathy. Studies have shown that probiotics alter gut flora and lead to elaboration of flora metabolites that influence health through 1 of 3 general mechanisms: direct antimicrobial effects, enhancement of mucosal barrier integrity, and immune modulation. Restoring the balance of intestinal flora by introducing probiotics for disease prevention and treatment could be beneficial to human health. It is also clear that significant differences exist between different probiotic species. Metagenomics and metatranscriptomics together with bioinformatics have allowed us to study the cross-talk between the gut microbiota and the host, furthering insight into the next generation of biologic products.

Dietary Enterococcus faecalis LAB31 improves growth performance, reduces diarrhea, and increases fecal Lactobacillus number of weaned piglets

Lactic acid bacteria (LAB) have been shown to enhance performance of weaned piglets. However, few studies have reported the addition of LAB Enterococcus faecalis as alternatives to growth promoting antibiotics for weaned piglets. This study evaluated the effects of dietary E. faecalis LAB31 on the growth performance, diarrhea incidence, blood parameters, fecal bacterial and Lactobacillus communities in weaned piglets. A total of 360 piglets weaned at 26 ± 2 days of age were randomly allotted to 5 groups (20 pens, with 4 pens for each group) for a trial of 28 days: group N (negative control, without antibiotics or probiotics); group P (Neomycin sulfate, 100 mg/kg feed); groups L, M and H (supplemented with E. faecalis LAB31 0.5×109, 1.0×109, and 2.5×109 CFU/kg feed, respectively). Average daily gain and feed conversion efficiency were found to be higher in group H than in group N, and showed significant differences between group H and group P (P0 < 0.05). Furthermore, groups H and P had a lower diarrhea index than the other three groups (P0 < 0.05). Denaturing gradient gel electrophoresis (DGGE) showed that the application of probiotics to the diet changed the bacterial community, with a higher bacterial diversity in group M than in the other four groups. Real-time PCR revealed that the relative number of Lactobacillus increased by addition of probiotics, and was higher in group H than in group N (P0 < 0.05). However, group-specific PCR-DGGE showed no obvious difference among the five groups in Lactobacillus composition and diversity. Therefore, the dietary addition of E. faecalis LAB31 can improve growth performance, reduce diarrhea, and increase the relative number of Lactobacillus in feces of weaned piglets.

Galacto-oligosaccharides and Colorectal Cancer: Feeding our Intestinal Probiome

Prebiotics are ingredients selectively fermented by the intestinal microbiota that promote changes in the microbial community structure and/or their metabolism, conferring health benefits to the host. Studies show that β (1-4) galacto-oligosaccharides [β (1-4) GOS], lactulose and fructo-oligosaccharides increase intestinal concentration of lactate and short chain fatty acids, and stool frequency and weight, and they decrease fecal concentration of secondary bile acids, fecal pH, and nitroreductase and β-glucuronidase activities suggesting a clear role in colorectal cancer (CRC) prevention. This review summarizes research on prebiotics bioassimilation, specifically β (1-4) GOS, and their potential role in CRC. We also evaluate research that show that the impact of prebiotics on host physiology can be direct or through modulation of the gut intestinal microbiome, specifically the probiome (autochtonous beneficial bacteria), we present studies on a potential role in CRC progression to finally describe the current state of β (1-4) GOS generation for industrial production.

Use of probiotics to correct dysbiosis of normal microbiota following disease or disruptive events: a systematic review

OBJECTIVE

To assess the evidence for the claim probiotics can correct dysbiosis of the normal microbiota resulting from disease or disruptive events.

SETTING

Systematic review of published clinical trials of patients receiving a probiotic intervention for the prevention or treatment of various diseases.

DATA SOURCES

Sources searched (1985-2013): PubMed, EMBASE, Cochrane Database of Systematic Reviews, CINAHL, AMED and ISI Web of Science. Three on-line clinical trial registries were searched: Cochrane Central Register of Controlled trials, MetaRegister of Controlled Trials and National Institutes of Health.

REVIEW METHODS

Included studies were randomised clinical trials of probiotic interventions having microbiological assays. Studies were evaluated following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for specific probiotic strains. A standard data extraction form was used to collect the raw data.

OUTCOME MEASURES

The primary outcome is the degree of microbiota correction by specific probiotic strains. Secondary outcome was the association between the degree of dysbiosis correction and clinical efficacy.

RESULTS

The review of the literature found three distinct study designs: model A (restoration) assayed patients enrolled with a healthy, undisturbed microbiota and then assayed postdisruptive event and probiotic therapy; model B (alteration) assayed patients with pre-existing disrupted microbiota and then postprobiotic therapy; model C (no dysbiosis) assayed volunteers with no disruptive event prebiotic and postprobiotic. From a total of 63 trials, 83% of the probiotic products using model A restored the microbiota, 56% using model B improved the microbiota and only 21% using model C had any effect on microbiota. Clinical efficacy was more commonly associated with strains capable of restoration of the normal microbiota.

CONCLUSIONS

The ability to assess the degree of dysbiosis improvement is dependent on the enrolled population and the timing of microbiological assays. The functional claim for correcting dysbiosis is poorly supported for most probiotic strains and requires further research.

TRIAL REGISTRATION NUMBER

PROSPERO (CRD42014007224).

Effects of Bacillus subtilis KN-42 on Growth Performance, Diarrhea and Faecal Bacterial Flora of Weaned Piglets

This research focused on the effects of different doses of Bacillus subtilis KN-42 on the growth performance, diarrhea incidence, faecal bacterial flora, and the relative number of Lactobacillus and Escherichia coli in faeces of weaned piglets to determine whether the strain can serve as a candidate antimicrobial growth promoter. A total of 360 piglets (initial body weight 7.14±0.63 kg) weaned at 26±2 days of age were randomly allotted to 5 treatment groups (4 pens per treatment with 18 pigs per pen) for a 28-day trial. Dietary treatments were basal diet without any antimicrobial (negative control; NC), basal diet supplemented with 120 mg/kg feed of neomycin sulfate (positive control; PC) and basal diet supplemented with 2×10⁹ (L), 4×10⁹ (M) and 20×10⁹ (H) CFU/kg feed of B. subtilis KN-42. During the overall period, average daily gain and feed efficiency of piglets were higher in groups PC, M, and H than those in group NC (p<0.05), and all probiotics and antibiotics groups had a lower diarrhea index than group NC (p<0.05). The 16S rDNA gene-based methods were used to analyze faecal bacterial flora on day 28 of experiment. The result of denaturing gradient gel electrophoresis analysis showed that supplementation of B. subtilis KN-42 to the diet changed the bacterial communities, with a higher bacterial diversity and band number in group M than in the other four groups. Real-time polymerase chain reaction analysis showed that the relative number of Lactobacillus were higher in groups PC and H than in group NC (p<0.05), and the supplemented B. subtilis KN-42 to the diet also reduced the relative number of E. coli (p<0.05). These results suggest that dietary addition of B. subtilis KN-42 can improve the growth performance and gastrointestinal health of piglets.

Long-term monitoring of the human intestinal microbiota from the 2nd week to 13 years of age

Microbial contact begins prior to birth and continues rapidly thereafter. Few long term follow-up studies have been reported and we therefore characterized the development of intestinal microbiota of ten subjects from the 2nd week of life to 13 years of age. PCR-denaturing gradient gel electrophoresis combined with several bacterial group-specific primer sets demonstrated the colonization steps of defined bacterial groups in the microbiota. Bifidobacterium species were seen throughout the test period in all subjects. Bacteroides fragilis group and Blautia coccoides-Eubacterium rectale group species were not detected in several subjects during the first 6 months of life but were commonly seen after 12 months of life. Streptococcus group appeared during early life but was not seen in several subjects at the age of 13 years. Although a few species were linked with the increasing age, major bacterial species in the groups did not change dramatically. Rather considerable changes were found in the relative abundances of each bacterial species. Clustering analysis of total bacterial flora indicated that the microbiota changed considerably between 6 months and 12 months of life, and, at the age of 12 months, the intestinal microbiota was already converted toward a profile characteristic of an adult microbiota. Probiotic supplementation in the beginning of life did not have major impacts on later microbiota development.

The role of microbiota in hepatic encephalopathy

Hepatic encephalopathy (HE), which consists of minimal (MHE) and overt (OHE) stages, is a model for impaired gut-liver-brain axis in cirrhosis. Microbiota changes in both stages have been associated with impaired cognition, endotoxemia, and inflammation. There is dysbiosis (reduced autochthonous taxa [Lachnospiraceae, Ruminococcaceae, and Clostridiales XIV] and increased Enterobacteriaceae and Streptococcaceae) with disease progression. In MHE, there is an increased abundance of Streptococcus salivarius linked to cognition and ammonia. In OHE, stool Alcaligenaceae and Porphyromonadaceae are associated with poor cognition. Colonic mucosal microbiome in cirrhosis is significantly different compared with stool and independently related to cognition. HE treatment can affect microbial composition and function; cognitive improvement in MHE after rifaximin, a non-absorbable antibiotic, occurred without significant stool microbiota composition change but improved metabolic linkages. Similarly, there are only modest lactulose and rifaximin-associated changes on microbiota composition in OHE. HE represents an important model to study microbiome-brain interactions.

Probiotics, prebiotics, synbiotics in prevention and treatment of inflammatory bowel diseases

Probiotics, prebiotics, and synbiotics are functional components able to exert positive effects on human health. Numerous medical conditions lack effective and safe approaches for prevention or treatment, thus usage of probiotics, prebiotics, and synbiotics is an alternative. Further, the benefit related to the consumption of these compounds is associated with lower morbidity of chronic diseases and reduced health-care costs. Various types of mediums to deliver probiotics/synbiotics to the human GIT are used. Although capsules and tablets are frequently applied as delivery systems for probiotics, the major challenge of the commercial sector is to market new functional foods containing probiotics and/or prebiotics. Discovering of new probiotic/synbiotic functional foods is connected to the interest of the food industry to revitalize continuously through introduction of products with improved nutritional value and pleasant taste, but also with health benefit for the consumers. The review provides insights and new perspectives in respect to usage of functional components and foods in prevention and treatment of inflammatory bowel diseases (IBD) that are highly correlated with the modern lifestyle. The therapeutic and safety properties of probiotics and prebiotics, their role in pathogenesis of IBD, potential to prevent and treat these diseases as well as postulated mechanisms of action will be discussed, highlighting the main areas in which further research is an emergence.

Caecal fermentation, putrefaction and microbiotas in rats fed milk casein, soy protein or fish meal

To clarify the effect of soy protein (SP) and fish meal (FM), compared to milk casein (MC), on the intestinal environment, we examined caecal environment of rats fed the test diets. Four-week-old rats were fed AIN-76-based diet containing 20 %, w/w MC, SP or FM for 16 days. Caecal organic acids were analysed by HPLC. Caecal putrefactive compounds (indole, phenol, H2S and ammonia) were analysed by colorimetric assays. Caecal microflora was determined by 16S rRNA gene-DGGE and pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. n-Butyric and lactic acid levels were high in rats fed SP and FM, respectively. Butyrate-producing bacteria, such as Oscillibacter, and lactate-producing bacteria, such as Lactobacillus, were detected in each diet group. Also, the putrefactive compound contents were high in rats fed SP and FM. In this study, both DGGE and pyrosequencing analyses were able to evaluate the dynamics of the intestinal microbiota. The results indicate that dietary proteins can alter the intestinal environment, affecting fermentation by the intestinal microbiota and the generation of putrefactive compounds.

Honeybees and beehives are rich sources for fructophilic lactic acid bacteria

Fructophilic lactic acid bacteria (FLAB) are a specific group of lactic acid bacteria (LAB) characterized and described only recently. They prefer fructose as growth substrate and inhabit only fructose-rich niches. Honeybees are high-fructose-consuming insects and important pollinators in nature, but reported to be decreasing in the wild. In the present study, we analyzed FLAB microbiota in honeybees, larvae, fresh honey and bee pollen. A total of 66 strains of LAB were isolated from samples using a selective isolation technique for FLAB. Surprisingly, all strains showed fructophilic characteristics. The 66 strains and ten FLAB strains isolated from flowers in a separate study were genotypically separated into six groups, four of which being identified as Lactobacillus kunkeei and two as Fructobacillus fructosus. One of the L. kunkeei isolates showed antibacterial activity against Melissococcus plutonius, a causative pathogen of European foulbrood, this protection being attributable to production of an antibacterial peptide or protein. Culture-independent analysis suggested that bee products and larvae contained simple Lactobacillus-group microbiota, dominated by L. kunkeei, although adult bees carried a more complex microbiota. The findings clearly demonstrate that honeybees and their products are rich sources of FLAB, and FLAB are potential candidates for future bee probiotics.

Dynamics of fecal microbial communities in children with diarrhea of unknown etiology and genomic analysis of associated Streptococcus lutetiensis

BACKGROUND

The sequences of the 16S rRNA genes extracted from fecal samples provide insights into the dynamics of fecal microflora. This potentially gives valuable etiological information for patients whose conditions have been ascribed to unknown pathogens, which cannot be accomplished using routine culture methods. We studied 33 children with diarrhea who were admitted to the Children's Hospital in Shanxi Province during 2006.

RESULTS

Nineteen of 33 children with diarrhea could not be etiologically diagnosed by routine culture and polymerase chain reaction methods. Eleven of 19 children with diarrhea of unknown etiology had Streptococcus as the most dominant fecal bacterial genus at admission. Eight of nine children whom three consecutive fecal samples were collected had Streptococcus as the dominant fecal bacterial genus, including three in the Streptococcus bovis group and three Streptococcus sp., which was reduced during and after recovery. We isolated strains that were possibly from the S. bovis group from feces sampled at admission, which were then identified as Streptococcus lutetiensis from one child and Streptococcus gallolyticus subsp. pasteurianus from two children. We sequenced the genome of S. lutetiensis and identified five antibiotic islands, two pathogenicity islands, and five unique genomic islands. The identified virulence genes included hemolytic toxin cylZ of Streptococcus agalactiae and sortase associated with colonization of pathogenic streptococci.

CONCLUSIONS

We identified S. lutetiensis and S. gallolyticus subsp. pasteurianus from children with diarrhea of unknown etiology, and found pathogenic islands and virulence genes in the genome of S. lutetiensis.

Effect of feeding a selected combination of galacto-oligosaccharides and a strain of Bifidobacterium pseudocatenulatum on the intestinal microbiota of cats

OBJECTIVE

To evaluate the growth kinetics of a strain of Bifidobacterium pseudocatenulatum (BP) on 4 oligo- or polysaccharides and the effect of feeding a selected probiotic-prebiotic combination on intestinal microbiota in cats.

ANIMALS

10 healthy adult cats.

PROCEDURES

Growth kinetics of a strain of cat-origin BP (BP-B82) on fructo-oligosaccharides, galacto-oligosaccharides (GOS), lactitol, or pectins was determined, and the combination of GOS and BP-B82 was selected. Cats received supplemental once-daily feeding of 1% GOS-BP-B82 (10(10) CFUs/d) for 15 days; fecal samples were collected for analysis the day before (day 0) and 1 and 10 days after the feeding period (day 16 and 25, respectively).

RESULTS

Compared with the prefeeding value, mean fecal ammonia concentration was significantly lower on days 16 and 25 (288 and 281 μmol/g of fecal dry matter [fDM], respectively, vs 353 μmol/g of fDM); fecal acetic acid concentration was higher on day 16 (171 μmol/g of fDM vs 132 μmol/g of fDM). On day 16, fecal concentrations of lactic, n-valeric, and isovaleric acids (3.61, 1.52, and 3.55 μmol/g of fDM, respectively) were significantly lower than on days 0 (5.08, 18.4, and 6.48 μmol/g of fDM, respectively) and 25 (4.24, 17.3, and 6.17 μmol/g of fDM, respectively). A significant increase in fecal bifidobacteria content was observed on days 16 and 25 (7.98 and 7.52 log(10) CFUs/g of fDM, respectively), compared with the prefeeding value (5.63 log(10) CFUs/g of fDM).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that feeding 1% GOS-BP-B82 combination had some positive effects on the intestinal microbiota in cats.

Reciprocal interaction between intestinal microbiota and mucosal lymphocyte in cynomolgus monkeys after alemtuzumab treatment

It has been known that the gut microbiota plays a central role in shaping normal mucosal immunity, however, little information is available whether the variability of mucosal lymphocytes impacts the commensal flora. Here, we applied a cynomolgus monkey model to characterize the structure and composition of the gut microbiota in response to lymphocyte depletion and to determine their potential association. Molecular profiling of 16S rDNA showed that the intestinal microbiota composition was perturbed after the depletion of mucosal lymphocytes and were recovered following the repopulation. Some specific bacteria from the orders Lactobacillales, Enterobacteriales and Clostridiales, and the genus Prevotella and Faecalibacterium, were primarily responsible for the variations of the gut microbiota after lymphocyte depletion. Interestingly, the species richness of the ileal mucosal microbiota was associated the proportions of TCRαβ+ or TCRγδ+ T cells (p<0.01). We demonstrate for the first time the feature of intestinal microbiota composition after lymphocyte depletion and provide novel evidence that the perturbation of gut microbiota is associated with lymphocyte depletion. It may contribute to understand the relationship between gut commensal microbiota and mucosal immune system. Study results provide insight into biological activity of alemtuzumab in intestinal barrier in organ transplantation.