All studies of the microbial community of the gastrointestinal tract of salmon to date have employed culture-based approaches, typically on pond- or tank-raised, freshwater animals. We present a phylogenetic survey of the bacterial populations present in the distal intestine of salmon from three different marine locations in Europe. This was accomplished through PCR amplification, cloning, and sequencing of partial 16S rDNA genes from microbial community DNA isolated from the contents of the GI tract distal to the pyloric ceca. Using this approach, the intestinal microbial communities of wild salmon from Scotland and pen-raised salmon from Scotland and Norway were compared. The predominating bacterial populations detected were Acinetobacter junii and a novel Mycoplasma phylotype. This Mycoplasma phylotype apparently comprised approximately 96% of the total microbes in the distal intestine of wild salmon. Substantial differences in intestinal microbial community composition and diversity were observed between the two groups of pen-raised salmon, which, in addition to geographical separation, were raised on different feeds. The microbial profiles found in this study were substantially different from those indicated in earlier culture-based studies for several species of fish, presumably because of the culture-independent techniques employed. Further, analysis of short-chain fatty acids in the digestive tract indicated that the decreasing redox gradient from proximal to distal reaches common to homeothermic animals was absent in salmon, and that the bacterial fermentation levels were much lower than are reported in homeothermic animals.

A hypoenergetic diet with betaine supplementation (6 g daily for 12 wk) decreased the plasma homocysteine concentration but did not affect body composition more than a hypoenergetic diet without betaine supplementation did.

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With increasing age, a number of physiological changes take place which are reflected in immune and bowel function. These changes may relate to the commonly assumed age-related changes in intestinal microbiota; most noticeably a reduction in bifidobacteria. The current study aimed at modifying the intestinal microbiota with a potential synbiotic on selected immune and microbiota markers. Healthy elderly subjects were randomised to consume during 2 weeks either a placebo (sucrose) or a combination of lactitol and Lactobacillus acidophilus NCFM twice daily in a double-blind parallel trial. After the intervention, stool frequency was higher in the synbiotic group than in the placebo group and a significant increase in faecal L. acidophilus NCFM levels was observed in the synbiotic group, after baseline correction. In contrast to the generally held opinion, the study subjects had faecal Bifidobacterium levels that were similar to those reported in healthy young adults. These levels were, nevertheless, significantly increased by the intervention. Levels of SCFA were not changed significantly. Of the measured immune markers, PGE 2 levels were different between treatments and IgA levels changed over time. These changes were modest which may relate to the fact that the volunteers were healthy. Spermidine levels changed over time which may suggest an improved mucosal integrity and intestinal motility. The results suggest that consumption of lactitol combined with L. acidophilus NCFM twice daily may improve some markers of the intestinal microbiota composition and mucosal functions.

The effects of a high level of dietary fibre (DF) either as arabinoxylan (AX) or resistant starch (RS) on digestion processes, SCFA concentration and pool size in various intestinal segments and on the microbial composition in the faeces were studied in a model experiment with pigs. A total of thirty female pigs (body weight 63·1 (SEM 4·4) kg) were fed a low-DF, high-fat Western-style control diet (WSD), an AX-rich diet (AXD) or a RS-rich diet (RSD) for 3 weeks. Diet significantly affected the digestibility of DM, protein, fat, NSP and NSP components, and the arabinose:xylose ratio, as well as the disappearance of NSP and AX in the large intestine. RS was mainly digested in the caecum. AX was digested at a slower rate than RS. The digesta from AXD-fed pigs passed from the ileum to the distal colon more than twice as fast as those from WSD-fed pigs, with those from RSD-fed pigs being intermediate (P,0·001). AXD feeding resulted in a higher number of Faecalibacterium prausnitzii, Roseburia intestinalis, Blautia coccoides -Eubacterium rectale, Bifidobacterium spp. and Lactobacillus spp. in the faeces sampled at week 3 of the experimental period (P,0·05). In the caecum, proximal and mid colon, AXD feeding resulted in a 3-to 5-fold higher pool size of butyrate compared with WSD feeding, with the RSD being intermediate (P , 0·001). In conclusion, the RSD and AXD differently affected digestion processes compared with the WSD, and the AXD most efficiently shifted the microbial composition towards butyrogenic species in the faeces and increased the large-intestinal butyrate pool size.Key words: Arabinoxylan: Resistant starch: SCFA: Microbial composition: Pigs A dietary pattern characterised by a high intake of fat, proteins from meat, refined carbohydrates and a low intake of nondigestible carbohydrates (dietary fibre, DF), as is typical for many people in affluent societies, is regarded as a significant risk factor for the development of colorectal cancers(1) and for the onset and relapse of inflammatory bowel disease (2) . The low content of DF in a Western-style diet (WSD) is a limiting factor for maintaining a viable and diverse microbial community and for the production of small organic molecules such as SCFA, primarily acetate, propionate and butyrate (3) . Especially, butyrate has been suggested to be a main modulator of colonic health and function (4) , and SCFA has been mostly associated with protection against chemically and dietary-induced colorectal carcinogenic pre-stages in rats (5,6) . Apart from being the preferred energy source for colonic epithelial cells and the major regulator of cell proliferation and differentiation (3) , butyrate has been shown to exert important actions related to cellular homeostasis, such as anti-inflammatory (7) , antioxidant (8) and anti-carcinogenic (9) functions. Many of these effects have been related to its action as a histone deacetylase inhibitor (10,11) . Identification of DF types that can increase the production of colonic butyrate is therefore of great intere...

1. In this study the effect of a blend of essential oils (EO) comprising 15 g/tonne thymol and 5 g/tonne cinnamaldehyde on the performance and intestinal microbiota of broilers was investigated. 2. A total of 720 male Ross broilers were divided into two dietary treatments with 12 replicate pens per treatment. Broilers were given a control soybean-wheat-based diet with or without added EO in two diet phases (0-21 d and 22-42 d). 3. The blend of EO increased body weight gain of broilers from 0 to 42 d by 45%. 4. Caecal microbiota were affected by the EO blend; in particular increases in the proportions of Lactobacillus and Escherichia coli at 41 d was observed. 5. The EO blend had major effects on caecal metabolites. The proportion of caecal butyrate at 20 and 41 d of age increased, whereas the proportion of caecal acetic acid at 20 d, and propionic acid and isovaleric acid at 41 d, decreased with the EO blend. In addition, the caecal proportion of spermine increased and tyramine decreased at 41 d of age with the EO treatment. 6. The present study shows that EO supplementation exerts a positive effect on intestinal microbiota with a concomitant enhancement in growth performance. The study suggests that modulation of broiler gut microbiota composition and activity through the administration of EO offers an effective means for improving broiler performance.

BackgroundThe gut microbiota is interlinked with obesity, but direct evidence of effects of its modulation on body fat mass is still scarce. We investigated the possible effects of Bifidobacterium animalisssp. lactis 420 (B420) and the dietary fiber Litesse® Ultra polydextrose (LU) on body fat mass and other obesity-related parameters.Methods225 healthy volunteers (healthy, BMI 28–34.9) were randomized into four groups (1:1:1:1), using a computer-generated sequence, for 6 months of double-blind, parallel treatment: 1) Placebo, microcrystalline cellulose, 12 g/d; 2) LU, 12 g/d; 3) B420, 1010 CFU/d in microcrystalline cellulose, 12 g/d; 4) LU + B420, 12 g + 1010 CFU/d. Body composition was monitored with dual-energy X-ray absorptiometry, and the primary outcome was relative change in body fat mass, comparing treatment groups to Placebo. Other outcomes included anthropometric measurements, food intake and blood and fecal biomarkers. The study was registered in Clinicaltrials.gov (NCT01978691).FindingsThere were marked differences in the results of the Intention-To-Treat (ITT; n = 209) and Per Protocol (PP; n = 134) study populations. The PP analysis included only those participants who completed the intervention with > 80% product compliance and no antibiotic use. In addition, three participants were excluded from DXA analyses for PP due to a long delay between the end of intervention and the last DXA measurement. There were no significant differences between groups in body fat mass in the ITT population. However, LU + B420 and B420 seemed to improve weight management in the PP population. For relative change in body fat mass, LU + B420 showed a − 4.5% (− 1.4 kg, P = 0.02, N = 37) difference to the Placebo group, whereas LU (+ 0.3%, P = 1.00, N = 35) and B420 (− 3.0%, P = 0.28, N = 24) alone had no effect (overall ANOVA P = 0.095, Placebo N = 35). A post-hoc factorial analysis was significant for B420 (− 4.0%, P = 0.002 vs. Placebo). Changes in fat mass were most pronounced in the abdominal region, and were reflected by similar changes in waist circumference. B420 and LU + B420 also significantly reduced energy intake compared to Placebo. Changes in blood zonulin levels and hsCRP were associated with corresponding changes in trunk fat mass in the LU + B420 group and in the overall population. There were no differences between groups in the incidence of adverse events.DiscussionThis clinical trial demonstrates that a probiotic product with or without dietary fiber controls body fat mass. B420 and LU + B420 also reduced waist circumference and food intake, whereas LU alone had no effect on the measured outcomes.

The gut microbiota contributes to host energy metabolism, and altered gut microbiota has been associated with obesity-related metabolic disorders. We previously reported that a probiotic alone or together with a prebiotic controls body fat mass in healthy overweight or obese individuals in a randomised, double-blind, placebo controlled clinical study (ClinicalTrials.gov NCT01978691). We now aimed to investigate whether changes in the gut microbiota may be associated with the observed clinical benefits. Faecal and plasma samples were obtained from a protocol compliant subset (n=134) of participants from a larger clinical study where participants were randomised (1:1:1:1) into four groups: (1) placebo, 12 g/d microcrystalline cellulose; (2) Litesse® Ultra™ polydextrose (LU), 12 g/day; (3) Bifidobacterium animalis subsp. lactis 420™ (B420), 1010 cfu/d in 12 g microcrystalline cellulose; (4) LU+B420, 1010 cfu/d of B420 in 12 g/d LU for 6 months of intervention. The faecal microbiota composition and metabolites were assessed as exploratory outcomes at baseline, 2, 4, 6 months, and +1 month post-intervention and correlated to obesity-related clinical outcomes. Lactobacillus and Akkermansia were more abundant with B420 at the end of the intervention. LU+B420 increased Akkermansia, Christensenellaceae and Methanobrevibacter, while Paraprevotella was reduced. Christensenellaceae was consistently increased in the LU and LU+B420 groups across the intervention time points, and correlated negatively to waist-hip ratio and energy intake at baseline, and waist-area body fat mass after 6 months treatment with LU+B420. Functional metagenome predictions indicated alterations in pathways related to cellular processes and metabolism. Plasma bile acids glycocholic acid, glycoursodeoxycholic acid, and taurohyodeoxycholic acid and tauroursodeoxycholic acid were reduced in LU+B420 compared to Placebo. Consumption of B420 and its combination with LU resulted in alterations of the gut microbiota and its metabolism, and may support improved gut barrier function and obesity-related markers.