articles epidemiology led to the hypothesis that Methanobrevibacter smithii may be a therapeutic target for the reduction of energy harvest in obese humans (25,26), as M. smithii is the major representative of the human gut methanogens (27).The purpose of this study was to investigate whether the proposed role of SCFA and microbiota composition in obesity, which was based on proof of principle experiments, can be confirmed in a larger study which did not exclude all confounding factors. Methods and Procedures Volunteer recruitmentLean and obese volunteers of both sexes were recruited from the Institute of Microecology and from the obesity consultation hours at the University of Giessen and Marburg. In total 98 volunteers (34 males and 64 females) took part in the study. All of the samples collected were analysed. The volunteers were aged 47 ± 13 year (mean ± s.e.m.: range 14-74 year). The BMI in kg/m 2 of 30 volunteers was within the normal range (18.5-24.9), while 35 were overweight (25.0-29.9) and 33 were obese (≥30.0). Of the latter, 17 were classified as obesity class 1 (30-35), 11 as class 2 (35-40), and 5 as class 3 (>40). No antibiotics had been taken in the 6 months prior to the study. All participants subsisted primarily on a western diet and all volunteers provided informed, signed consent.

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The gut microbiota not only influences host metabolism but can also affect brain function and behaviour through the microbiota-gut-brain axis. To explore the potential role of the intestinal microbiota in anorexia nervosa (AN), we comprehensively investigated the faecal microbiota and short-chain fatty acids in these patients before (n = 55) and after weight gain (n = 44) in comparison to normal-weight participants (NW, n = 55) along with dietary intake and gastrointestinal complaints. We show profound microbial perturbations in AN patients as compared to NW participants, with higher levels of mucin-degraders and members of Clostridium clusters I, XI and XVIII and reduced levels of the butyrate-producing Roseburia spp. Branched-chain fatty acid concentrations, being markers for protein fermentation, were elevated. Distinct perturbations in microbial community compositions were observed for individual restrictive and binge/purging AN-subtypes. Upon weight gain, microbial richness increased, however perturbations in intestinal microbiota and short chain fatty acid profiles in addition to several gastrointestinal symptoms did not recover. These insights provide new leads to modulate the intestinal microbiota in order to improve the outcomes of the standard therapy.

Background/Objectives: Consisting of B10 14 microbial cells, the intestinal microbiota represents the largest and the most complex microbial community inhabiting the human body. However, the influence of regular diets on the microbiota is widely unknown. Subjects/Methods: We examined faecal samples of vegetarians (n ¼ 144), vegans (n ¼ 105) and an equal number of control subjects consuming ordinary omnivorous diet who were matched for age and gender. We used classical bacteriological isolation, identification and enumeration of the main anaerobic and aerobic bacterial genera and computed absolute and relative numbers that were compared between groups. Results: Total counts of Bacteroides spp., Bifidobacterium spp., Escherichia coli and Enterobacteriaceae spp. were significantly lower (P ¼ 0.001, P ¼ 0.002, P ¼ 0.006 and P ¼ 0.008, respectively) in vegan samples than in controls, whereas others (E. coli biovars, Klebsiella spp., Enterobacter spp., other Enterobacteriaceae, Enterococcus spp., Lactobacillus spp., Citrobacter spp. and Clostridium spp.) were not. Subjects on a vegetarian diet ranked between vegans and controls. The total microbial count did not differ between the groups. In addition, subjects on a vegan or vegetarian diet showed significantly (P ¼ 0.0001) lower stool pH than did controls, and stool pH and counts of E. coli and Enterobacteriaceae were significantly correlated across all subgroups. Conclusions: Maintaining a strict vegan or vegetarian diet results in a significant shift in the microbiota while total cell numbers remain unaltered.

The establishment and succession of bacterial communities in hospitalized preterm infants has not been extensively studied. Because earlier studies depended on classical cultural techniques, their results were limited. This study monitored the establishment and succession of the neonatal microbiota in the first weeks of life by analyzing the 16S rDNA variety in fecal samples applying PCR-denaturing gradient gel electrophoresis (PCR-DGGE). Fecal samples from 29 preterm infants hospitalized in a neonatal intensive care unit, including samples from antibiotic-treated infants and one with neonatal necrotizing enterocolitis, were subjected to PCR-DGGE analysis. Daily DGGE profiles from all preterm infants during the first 4 wk were obtained and analyzed. In addition, feces of 15 breast-fed, full-term infants and a variety of clinical bacterial isolates were examined and compared with the PCR-DGGE profiles of the preterm infants. During the first days of life, the DGGE profiles were rather simple but increased in their complexity over time. It became obvious that not only the intraindividual band-pattern similarity increased over time, but also the interindividual. During the observation period, similarity values (C s ) increased in each preterm infant from 0 to 80%, whereas interindividual C s increased from 18.1 to 57.4%, revealing the acquisition of a highly similar bacterial community in these infants. In contrast, C s -values obtained for breast-fed, full-term infants were rather low (11.2%). Escherichia coli, Enterococcus sp., and Klebsiella pneumoniae were the bacteria most commonly found in all preterm infants. The interindividual bacterial composition in hospitalized preterm infants is more similar in comparison with breast-fed, full-term infants and is not necessarily influenced by birth weight, diet, or antibiotic treatment. The GI tract of a normal fetus is sterile. During the birth process and rapidly thereafter, microbes from the mother and the surrounding environment colonize the gastrointestinal tract of the infant until a dense, complex bacterial community is established. This enteric flora contributes not only to health by facilitating carbohydrate assimilation (1) and interaction with the developing immune system (2, 3), it also plays a significant role in disease (4 -6). A dynamic balance exists between the GI bacterial community, host physiology, and diet, all of which influence the initial acquisition, developmental succession, and eventual stability of the gut ecosystem (7). In the birth process and soon thereafter, bacterial colonization starts and facultative anaerobic bacteria such as enterobacteria appear in feces. Because at this stage the composition of the gut bacterial community is strongly influenced by the diet, a shift in the bacterial composition can be observed (3,8). A breast-fed, full-term infant shows a fecal bacterial composition in which bifidobacteria predominate over potentially harmful bacteria, whereas, in formula-fed infants, coliforms, enterococci, and bacteroides predomi...