Does simulated microgravity induce significant changes in human gut microbiota? New answers with dry immersion, an innovative ground-based model.

Abstract Background A new problematic on the gut microbiota of the astronauts and the effects of microgravity emerged recently as that bacteria community is sensitive to physical (in)activity which could be hampered during spaceflights. Therefore, the objective of our study was thus to determine the effects of dry immersion, an innovative ground-based human model of simulated microgravity, on human gut microbiota composition. We collected stools from 14 healthy men before and after 5 days of Dry Immersion to determine taxonomic profiles by 16S metagenomic.Results Our analyses show preservation of α–diversity through Observed, Chao1, Shannon and InvSimpson indices. β–diversity is also not impacted by Dry Immersion as represented by PCoA plots with Jaccard, Bray-Curtis and UniFrac indices. Phyla abundances for OTUs associated to BacteroidetesP, FirmicutesP, ProteobacteriaP and ActinobacteriaP are also preserved. Interestingly, metagenomics analysis of the 32 families and 44 associated genera underscored that OTUs associated to ClostridialesO order and LachnospiraceaeF family are increased (p < 0.01) belonging to FirmicutesP phylum.Conclusion The diversity and global composition of the gut microbiome remained unaltered in response to Dry Immersion confirming the robustness of gut microbiota. However, it’s sufficient to led to several significant changes at the lower taxonomy levels. This suggests that the human gut microbiota, with its known strong impact on human health and performance, is a potential biological target of microgravity and underscores the need to investigate further this new field of research on gut microbiota – microgravity.Trial registration: ClinicalTrials.gov Identifier NCT03915457- Registered 16 April 2019 - Retrospectively registered - https://clinicaltrials.gov/ct2/show/NCT03915457.

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Ramadan Fasting Leads to Shifts in Human Gut Microbiota Structured by Dietary Composition

Frontiers in Microbiology ◽

10.3389/fmicb.2021.642999 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ikram Ali ◽

Ke Liu ◽

Danfeng Long ◽

Shah Faisal ◽

Mian Gul Hilal ◽

...

Keyword(s):

Gut Microbiota ◽

Ethnic Groups ◽

Alpha Diversity ◽

Rrna Gene ◽

Dietary Composition ◽

Human Gut ◽

Ramadan Fasting ◽

Human Gut Microbiota ◽

Before And After ◽

Chinese Group

The structure and diversity of human gut microbiota are directly related to diet, though less is known about the influences of ethnicity and diet-related behaviors, such as fasting (intermittent caloric restriction). In this study, we investigated whether fasting for Ramadan altered the microbiota in Chinese and Pakistani individuals. Using high-throughput 16S rRNA gene sequencing and self-reported dietary intake surveys, we determined that both the microbiota and dietary composition were significantly different with little overlap between ethnic groups. Principal Coordinate Analyses (PCoA) comparison of samples collected from both groups before and after fasting showed partial separation of microbiota related to fasting in the Pakistani group, but not in the Chinese group. Measurement of alpha diversity showed that Ramadan fasting significantly altered the coverage and ACE indices among Chinese subjects, but otherwise incurred no changes among either group. Specifically, Prevotella and Faecalibacterium drove predominance of Bacteroidetes and Firmicutes in the Pakistani group, while Bacteroides (phylum Bacteroidetes) were the most prevalent among Chinese participants both before and after fasting. We observed significant enrichment of some specific taxa and depletion of others in individuals of both populations, suggesting that fasting could affect beta diversity. Notably, Dorea, Klebsiella, and Faecalibacterium were more abundant in the Chinese group after fasting, while Sutterella, Parabacteroides, and Alistipes were significantly enriched after fasting in the Pakistani group. Evaluation of the combined groups showed that genera Coprococcus, Clostridium_XlV, and Lachnospiracea were all significantly decreased after fasting. Analysis of food intake and macronutrient energy sources showed that fat-derived energy was positively associated with Oscillibacter and Prevotella, but negatively associated with Bacteroides. In addition, the consumption of sweets was significantly positively correlated with the prevalence of Akkermansia. Our study indicated that diet was the most significant influence on microbiota, and correlated with ethnic groups, while fasting led to enrichment of specific bacterial taxa in some individuals. Given the dearth of understanding about the impacts of fasting on microbiota, our results provide valuable inroads for future study aimed at novel, personalized, behavior-based treatments targeting specific gut microbes for prevention or treatment of digestive disorders.

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Longitudinal Analysis of Infant Stool Bacteria Communities Before and After Acute Febrile Malaria and Artemether-Lumefantrine Treatment

The Journal of Infectious Diseases ◽

10.1093/infdis/jiy740 ◽

2018 ◽

Vol 220 (4) ◽

pp. 687-698 ◽

Cited By ~ 4

Author(s):

Rabindra K Mandal ◽

Rosie J Crane ◽

James A Berkley ◽

Wilson Gumbi ◽

Juliana Wambua ◽

...

Keyword(s):

Gut Microbiota ◽

Bacterial Species ◽

Enteric Bacteria ◽

Malaria Episode ◽

Sequence Variant ◽

Human Gut ◽

Human Gut Microbiota ◽

Significant Difference ◽

Before And After ◽

Stool Samples

Abstract Background Gut microbiota were recently shown to impact malaria disease progression and outcome, and prior studies have shown that Plasmodium infections increase the likelihood of enteric bacteria causing systemic infections. Currently, it is not known whether Plasmodium infection impacts human gut microbiota as a prelude to bacteremia or whether antimalarials affect gut microbiota. Our goal was to determine to what degree Plasmodium infections and antimalarial treatment affect human gut microbiota. Methods One hundred Kenyan infants underwent active surveillance for malaria from birth to 10 months of age. Each malaria episode was treated with artemether-lumefantrine (AL). Any other treatments, including antibiotics, were recorded. Stool samples were collected on an approximately biweekly basis. Ten children were selected on the basis of stool samples having been collected before (n = 27) or after (n = 17) a malaria episode and without antibiotics having been administered between collections. These samples were subjected to 16S ribosomal ribonucleic acid gene (V3–V4 region) sequencing. Results Bacterial community network analysis revealed no obvious differences in the before and after malaria/AL samples, which was consistent with no difference in alpha and beta diversity and taxonomic analysis at the family and genus level with one exception. At the sequence variant (SV) level, akin to bacterial species, only 1 of the top 100 SVs was significantly different. In addition, predicted metagenome analysis revealed no significant difference in metagenomic capacity between before and after malaria/AL samples. The number of malaria episodes, 1 versus 2, explained significant variation in gut microbiota composition of the infants. Conclusions In-depth bioinformatics analysis of stool bacteria has revealed for the first time that human malaria episode/AL treatment have minimal effects on gut microbiota in Kenyan infants.

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In vitro study of the interaction between human gut microbiota and herbal extracts using willow bark extract as an example

Planta Medica ◽

10.1055/s-0036-1596386 ◽

2016 ◽

Vol 81 (S 01) ◽

pp. S1-S381

Author(s):

EM Pferschy-Wenzig ◽

K Koskinen ◽

C Moissl-Eichinger ◽

R Bauer

Keyword(s):

Gut Microbiota ◽

In Vitro Study ◽

Vitro Study ◽

Bark Extract ◽

Herbal Extracts ◽

Human Gut ◽

Human Gut Microbiota ◽

Willow Bark

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Metabolization of the herbal combination STW-5 by human gut microbiota in vitro

10.1055/s-0037-1608399 ◽

2017 ◽

Author(s):

EM Pferschy-Wenzig ◽

A Roßmann ◽

K Koskinen ◽

H Abdel-Aziz ◽

C Moissl-Eichinger ◽

...

Keyword(s):

Gut Microbiota ◽

Human Gut ◽

Human Gut Microbiota

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Substrate use prioritization by a coculture of five species of gut bacteria fed mixtures of arabinoxylan, xyloglucan, β-glucan, and pectin

10.26686/wgtn.12585620.v1 ◽

2020 ◽

Author(s):

Y Liu ◽

AL Heath ◽

B Galland ◽

N Rehrer ◽

L Drummond ◽

...

Keyword(s):

Gut Microbiota ◽

Dietary Fiber ◽

Plant Cell Wall ◽

Bacterial Species ◽

Short Chain ◽

Emergent Properties ◽

Human Gut ◽

Fermentation Products ◽

Plant Polysaccharides ◽

Human Gut Microbiota

© 2020 American Society for Microbiology. Dietary fiber provides growth substrates for bacterial species that belong to the colonic microbiota of humans. The microbiota degrades and ferments substrates, producing characteristic short-chain fatty acid profiles. Dietary fiber contains plant cell wall-associated polysaccharides (hemicelluloses and pectins) that are chemically diverse in composition and structure. Thus, depending on plant sources, dietary fiber daily presents the microbiota with mixtures of plant polysaccharides of various types and complexity. We studied the extent and preferential order in which mixtures of plant polysaccharides (arabinoxylan, xyloglucan, β-glucan, and pectin) were utilized by a coculture of five bacterial species (Bacteroides ovatus, Bifidobacterium longum subspecies longum, Megasphaera elsdenii, Ruminococcus gnavus, and Veillonella parvula). These species are members of the human gut microbiota and have the biochemical capacity, collectively, to degrade and ferment the polysaccharides and produce short-chain fatty acids (SCFAs). B. ovatus utilized glycans in the order β-glucan, pectin, xyloglucan, and arabinoxylan, whereas B. longum subsp. longum utilization was in the order arabinoxylan, arabinan, pectin, and β-glucan. Propionate, as a proportion of total SCFAs, was augmented when polysaccharide mixtures contained galactan, resulting in greater succinate production by B. ovatus and conversion of succinate to propionate by V. parvula. Overall, we derived a synthetic ecological community that carries out SCFA production by the common pathways used by bacterial species for this purpose. Systems like this might be used to predict changes to the emergent properties of the gut ecosystem when diet is altered, with the aim of beneficially affecting human physiology. This study addresses the question as to how bacterial species, characteristic of the human gut microbiota, collectively utilize mixtures of plant polysaccharides such as are found in dietary fiber. Five bacterial species with the capacity to degrade polymers and/or produce acidic fermentation products detectable in human feces were used in the experiments. The bacteria showed preferential use of certain polysaccharides over others for growth, and this influenced their fermentation output qualitatively. These kinds of studies are essential in developing concepts of how the gut microbial community shares habitat resources, directly and indirectly, when presented with mixtures of polysaccharides that are found in human diets. The concepts are required in planning dietary interventions that might correct imbalances in the functioning of the human microbiota so as to support measures to reduce metabolic conditions such as obesity.

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