Identification of bacteria with beta-galactosidase activity in faeces from lactase non-persistent subjects

Previous studies suggest that, besides the maldigestion of lactose in the small intestine, the colonic processing of lactose might play a role in lactose intolerance. beta-Galactosidase is the bacterial enzyme which catalyzes the first step of lactose fermentation in the colon. We propose a practical method to differentiate and identify bacteria with beta-galactosidase activity in faeces which combines a colony-lift filter assay with X-gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside) as substrate for differentiation and the fluorescent in situ hybridization technique for identification. The method was applied to faeces from lactase non-persistent subjects. After 28 subjects had undergone one glucose and two lactose challenges, consistent intolerant (n=5) and tolerant (n=7) groups were defined according to their symptom scores. Of the 28 faecal samples, 80.6% (mean, SD: 12.1, range: 47.8-100%) of the total cultured bacteria were found to possess beta-galactosidase activity, which indicates that the bacterial beta-galactosidase is abundant in the colon. The tolerant and intolerant groups did not differ in the percentage or composition of the bacteria with beta-galactosidase activity or beta-galactosidase activity in faeces. Results suggest that the percentage or composition of the bacteria with beta-galactosidase activity in faeces do not play a role in lactose intolerance.     

Low species diversity and high interindividual variability in faeces of preterm infants as revealed by sequences of 16S rRNA genes and PCR-temporal temperature gradient gel electrophoresis profiles

Little information regarding the composition of the gut microbiota in preterm infants is available. The purpose of this study was to investigate the bacterial diversity in faeces of preterm infants, using analysis of randomly cloned 16S rRNA genes and PCR-TTGE (temporal temperature gradient gel electrophoresis) profiles, to determine whether noncultivated bacteria represented an important part of the community. The 288 clones obtained from faecal samples of 16 preterm infants were classified into 25 molecular species. All but one molecular species had a cultivated representative in public databases: molecular tools did not reveal any unexplored diversity. The mean number of molecular species per infant was 3.25, ranging from one to eight. There was a high interindividual variability. The main groups encountered were the Enterobacteriaceae family and the genera Enterococcus, Streptococcus and Staphylococcus. Seven preterm infants were colonized by anaerobes and only four by bifidobacteria. TTGE profiles were composed of one to nine bands (mean value: 4.3). Furthermore, 51 of 59 clones (86%) comigrated with a band of the corresponding faecal sample. This study will form a comparative framework for other studies, e.g. on the faecal microbiota of preterm infants with different pathologies or the impact of diet on colonization.     

Marine sponges as microbial fermenters

The discovery of phylogenetically complex, yet highly sponge-specific microbial communities in marine sponges, including novel lineages and even candidate phyla, came as a surprise. At the same time, unique research opportunities opened up, because the microorganisms of sponges are in many ways more accessible than those of seawater. Accordingly, we consider sponges as microbial fermenters that provide exciting new avenues in marine microbiology and biotechnology. This review covers recent findings regarding diversity, biogeography and population dynamics of sponge-associated microbiota, and the data are discussed within the larger context of the microbiology of the ocean.     

Vibrio cholerae/mimicus in fecal microbiota of healthy children in a cholera endemic urban slum setting in Kolkata,India

During a double‐blind, randomized, placebo‐controlled probiotic trial among 3758 children residing in an urban slum in Kolkata, India, Vibrio cholerae/mimicus was detected in fecal microbiota of healthy children. The importance of this finding in the local, regional and global transmission of cholera is discussed.     

High-level resistance to gentamicin: genetic transfer between Enterococcus faecalis isolated from food of animal origin and human microbiota

Aims: To investigate the in vivo gene transfer of high‐level gentamicin resistance (HLRG) from Enterococcus faecalis isolated from the food of animal origin to a human isolate, using a mouse model of intestinally colonized human microbiota. Methods and Results: In vitro study: The presence of plasmids involved in HLRG coding was investigated. After the conjugation experiment, the recipient strain, Ent. faecalis JH2‐SS, acquired a plasmid responsible for HLRG [minimal inhibitory concentration (MIC) >800 μg ml^?1], in a similar position to the donor cells. In vivo study: Seven BALB/c mice were dosed with ceftriaxone (400 mg kg^?1) and then inoculated with a dilution of 1/100 of human faeces (HFc). After 72 h, Ent. faecalis JH2‐SS (recipient) was inoculated and then, after a further 72 h, the animals were given Ent. faecalis CS19, isolated from the food of animal origin, involved in HLRG (donor). The presence of transconjugant strains in HFc was subsequently recorded on a daily basis until the end of the experiment. The clonal relationship between Ent. faecalis and Escherichia coli in faeces was assessed by RAPD‐PCR. Both the in vitro and in vivo studies showed that the receptor strain acquired a plasmid responsible for HLRG (MICs >800 μg ml^?1), which migrated with a similar relative mobility value. Transconjugant strains were detected from 24 h after the donor strain inoculation and persisted until the end of the experiment. Conclusions: The in vivo gene transfer of HLRG from Ent. faecalis strains, isolated from the food of animal origin, to human microbiota has been demonstrated in a mouse model. Significance and Impact of the Study: The complexity found on the therapeutic responses of invasive infectious diseases caused by Ent. faecalis facilitates the assessment of food of animal origin as a resistant pathogen reservoir. In addition, this study may contribute to the understanding of antimicrobials’ resistance gene transfer between Ent. faecalis strains from food and human GI tract.     

CO2 -dependent growth of Succinatimonas hippei YIT 12066T isolated from human feces

Succinatimonas hippei is a new bacterial species isolated from human feces. Here we report that the growth of S. hippei YIT 12066(T) depends on CO(2) or bicarbonate and the headspace gas produced by microbiota. Genetic defect for carbonic anhydrase in this bacterium suggested a reason for the syntrophic property of CO(2) dependency and may suggest an adaptation to its habitat.     

The impact of Helicobacter pylori on atopic disorders in childhood

Background: The prevalence of Helicobacter pylori in Western populations has steadily decreased. This has been suggested as one of the factors involved in the recent increase of asthma and allergy. Some studies have reported a negative association between H. pylori and asthma and allergy, but data are inconsistent and there are a few studies in children. Aim: We investigated whether the prevalence of H. pylori was associated with asthma symptoms, allergic rhinitis, and atopic dermatitis in childhood. Methods: We determined IgG anti‐H. pylori and CagA antibodies in serum of Dutch children, who took part in the PIAMA birth cohort study. Serum was collected from 545 children, aged 7–9 years (Dutch ethnicity 91.5%). Symptoms of asthma and atopy were assessed by yearly questionnaires. Chi‐square tests and logistic regression were used. Results: We found 9%H. pylori and 0.9% CagA seropositivity. Twelve (5.9%) children with reported wheezing ever were H. pylori positive, compared to 37 (10.9%) of the non‐wheezers (p = .05). No significant differences in H. pylori prevalence were found between children with or without allergic rhinitis (8.5% vs 9.5%), atopic dermatitis (8.7% vs 9.2%), and physician‐diagnosed asthma (7.1% vs 9.4%). Multivariate analysis showed no significant associations between H. pylori seropositivity and wheezing (OR 0.52; 95% CI 0.25–1.06), allergic rhinitis (OR 0.96; 95% CI 0.51–1.81), atopic dermatitis (OR 1.05; 95% CI 0.56–1.98) or physician‐diagnosed asthma (OR 0.87; 95% CI 0.37–2.08). Conclusion: We found a borderline significantly lower H. pylori seropositivity in children with wheezing compared to non‐wheezers, but no association between H. pylori serum‐antibody status and allergic rhinitis, atopic dermatitis, or asthma.     

Experience matters: prior exposure to plant toxins enhances diversity of gut microbes in herbivores

For decades, ecologists have hypothesised that exposure to plant secondary compounds (PSCs) modifies herbivore‐associated microbial community composition. This notion has not been critically evaluated in wild mammalian herbivores on evolutionary timescales. We investigated responses of the microbial communities of two woodrat species (Neotoma bryanti and N. lepida). For each species, we compared experienced populations that independently converged to feed on the same toxic plant (creosote bush, Larrea tridentata) to naïve populations with no exposure to creosote toxins. The addition of dietary PSCs significantly altered gut microbial community structure, and the response was dependent on previous experience. Microbial diversity and relative abundances of several dominant phyla increased in experienced woodrats in response to PSCs; however, opposite effects were observed in naïve woodrats. These differential responses were convergent in experienced populations of both species. We hypothesise that adaptation of the foregut microbiota to creosote PSCs in experienced woodrats drives this differential response.     

Gut bacteria in health and disease: a survey on the interface between intestinal microbiology and colorectal cancer

A healthy human body contains at least tenfold more bacterial cells than human cells and the most abundant and diverse microbial community resides in the intestinal tract. Intestinal health is not only maintained by the human intestine itself and by dietary factors, but is also largely supported by this resident microbial community. Conversely, however, a large body of evidence supports a relationship between bacteria, bacterial activities and human colorectal cancer. Symbiosis in this multifaceted organ is thus crucial to maintain a healthy balance within the host-diet-microbiota triangle and accordingly, changes in any of these three factors may drive a healthy situation into a state of disease. In this review, the factors that sustain health or drive this complex intestinal system into dysbiosis are discussed. Emphasis is on the role of the intestinal microbiota and related mechanisms that can drive the initiation and progression of sporadic colorectal cancer (CRC). These mechanisms comprise the induction of pro-inflammatory and pro-carcinogenic pathways in epithelial cells as well as the production of (geno)toxins and the conversion of pro-carcinogenic dietary factors into carcinogens. A thorough understanding of these processes will provide leads for future research and may ultimately aid in development of new strategies for CRC diagnosis and prevention.