Relations between transit time, fermentation products, and hydrogen consuming flora in healthy humans.

Oufir, L El; Flourié, Bernard; Varannes, Stanislas Bruley des; Barry, J.-L.; Cloarec, D; Bornet, Francis; Jp, Galmiche

doi:10.1136/gut.38.6.870

Cited by 147 publications

(104 citation statements)

References 49 publications

(16 reference statements)

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“…or greater, the percentage of methane producers varies significantly in humans of different ethnic groups, ranging from 34% to 87% (summarized in Levitt et al, 2006). Although breath methane reliably reflects the abundance of colonic methanogens, non-methanogenic subjects, as thereby defined, often harbor a relatively lower number of stool MA (El Oufir et al, 1996). One study, based on a fortuitous measurement of colonic gases, suggested that methane was predominantly produced in the left colon (Bond et al, 1971).…”

Section: Discussionmentioning

confidence: 99%

Abundance and diversity of mucosa-associated hydrogenotrophic microbes in the healthy human colon

et al. 2011

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Hydrogenotrophic microbiota have a significant impact on colonic health; however, little is known about their diversity and ecology in situ. Here, molecular-based methods and multivariate analyses were used to examine the abundance and diversity of mucosa-associated hydrogenotrophic microbes in 90 biopsies collected from right colon, left colon and rectum of 25 healthy subjects. Functional genes of all three hydrogenotrophic groups were detected in at least one colonic region of all subjects. Methanogenic archaea (MA) constituted approximately one half of the hydrogenotrophic microbiota in each colonic region. Sulfate-reducing bacteria (SRB) were more abundant than acetogens in right colon, while acetogens were more abundant than SRB in left colon and rectum. MA genotypes exhibited low diversity, whereas SRB genotypes were diverse and generally similar across the three regions within subject but significantly variable among subjects. Multivariate cluster analysis defined subject-specific patterns for the diversity of SRB genotypes; however, neither subject-nor region-specific clusters were observed for the abundance of hydrogenotrophic functional genes. Sequence analyses of functional gene clones revealed that mucosa-associated SRB were phylogenetically related to Desulfovibrio piger, Desulfovibrio desulfuricans and Bilophila wadsworthia; whereas MA were related to Methanobrevibacter spp., Mb. smithii and the order Methanomicrobiales. Together these data demonstrate for the first time that the human colonic mucosa is persistently colonized by all three groups of hydrogenotrophic microbes, which exhibit segmental and interindividual variation in abundance and diversity.

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Section: Discussionmentioning

confidence: 99%

Abundance and diversity of mucosa-associated hydrogenotrophic microbes in the healthy human colon

et al. 2011

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“…The reasons for their absence or very low number in some colons are unknown. In methane-producing humans, methanogens number 1.6 ϫ 10 8 to 8 ϫ 10 9 /g feces (11,12), but less than 10 2 to 5 ϫ 10 6 /g feces in nonmethanogenic humans (12). The carriage of methanogens and methane production are remarkably stable over time.…”

Section: Introductionmentioning

confidence: 92%

Shared and unique environmental factors determine the ecology of methanogens in humans and rats

Florin

Zhu

Kirk

et al. 2000

The American Journal of Gastroenterology

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OBJECTIVE:This study ascertains the relative contributions of genetics and environment in determining methane emission in humans and rats. There is considerable interest in the factors determining the microbial species that inhabit the colon. Methanogens, which are archaebacteria, are an easily detected colonic luminal bacteria because they respire methane. They are present in some but not all human colons and lower animal hindguts. Opinion varies on the nature of the factors influencing this ecology with some studies proposing the existence of host genetic influences. METHODS:Methane emission was measured in human twin pairs by gas chromatography, and structural equation modeling was used to determine the proportion of genetic and environmental determinants. The importance of the timing of environmental effects and rat strain on the trait of methane emission were ascertained by experiments with cohabiting methanogenic and nonmethanogenic rats. RESULTS:Analysis of breath samples from 274 adolescent twin pairs and their families indicated that the major influences on the trait of methane emission are the result of shared (53%, 95% confidence interval 39 -61) and unique environmental (47%, 95% confidence interval 38 -56) effects. No significant autosomal genetic effects were detected, but as observed in other studies, men (37%) were less likely to excrete methane in their breath than women (63%). Investigation of methane emission in rats indicated that environmental effects in this animal are most potent during the weaning period, with stable gut microbial ecology thereafter for some but not all rat strains. CONCLUSIONS:These results are consistent with shared and unique environmental factors being the main determinants of the ecology of this colonic microbe. (Am J Gastroenterol 2000;95:2872-2879

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“…Results concerning transit time variations and their implications for in vivo fermentation parameters were reported in a previous publication (El Ou®r et al, 1996), but the main points are included here to ensure a better understanding of the relation of transit time modi®cations to other measured parameters.…”

Section: Mean Transit Timementioning

confidence: 99%

“…With a faster turnover rate, microbial growth is more ef®cient and a greater mass of bacteria is produced (Stephen et al, 1987). Conversely, with a lower turnover rate, the ef®ciency of microbial growth decreases (Stephen et al, 1987) while methanogenic bacteria as well as the pH of luminal contents increase (El Ou®r et al, 1996). Therefore, transit time through the colon could markedly in¯uence the extent of ®ber fermentation and the types of fermentation end-products.…”

Section: Introductionmentioning

confidence: 99%

“…All experiments were conducted in vitro in a batch system according to the general procedure described by Barry et al (1996), using serum bottles instead of vials so that gas could be collected. Fresh feces were mixed (1:5, wav) with a CO 2 -saturated nutritive buffer (Table 1), then ®ltered through six gauzes to remove undigested materials.…”

Section: In Vitro Fermentationmentioning

confidence: 99%

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Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria

et al. 2000

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Objective: To assess the effects of drug-induced changes in mean transit time (MTT) on the activity of human fecal¯ora in vitro. Methods: The activity of fecal¯ora was estimated by the ability of a fecal inoculum to ferment a substrate (beet ®ber) in vitro in a batch system for 24 h. The inoculum was collected from 8 healthy volunteers studied during three 3-week randomized periods, who received a controlled diet alone (control period) or the same diet with either cisapride or loperamide. Cisapride and loperamide were adjusted in order to halve and double MTT measured during the control period. At the end of each period, the percentage disappearance of the initial added substrate and the concentration and the pro®le of short-chain fatty acids (SCFAs), were determined. Results: In the control period, the pH of the inoculum and SCFA concentration were inversely related to MTT (P 0.0001). Individual SCFA production was also signi®cantly related to MTT (P`0.01). Cisapride-reduced transit time was associated with a signi®cant rise in the concentrations of total SCFAs (P`0.05), propionic and butyric acids (P`0.05) and the percentage substrate disappearance (P`0.05). Inverse relations were observed during the loperamide period. Moreover, MTT was inversely related to the percentage substrate disappearance (P`0.001), SCFA production (P`0.001) and butyrate production (P`0.0005). Conclusion: Changes in MTT alter bacterial activity and modify the bacterial pathways affecting the proportion of individual SCFAs. Sponsorship:

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Relations between transit time, fermentation products, and hydrogen consuming flora in healthy humans.

Abstract: Considering the effects of some fermentation products on intestinal morphology and finction, these variations may be relevant to the pathogenesis of colorectal diseases.

Cited by 147 publications

References 49 publications

Abundance and diversity of mucosa-associated hydrogenotrophic microbes in the healthy human colon

Abundance and diversity of mucosa-associated hydrogenotrophic microbes in the healthy human colon

Shared and unique environmental factors determine the ecology of methanogens in humans and rats

Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria

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