Physical inactivity related changes in human fecal microbiotaŠket, Robert (Avtor) Stres, Blaž (Mentor) Debevec, Tadej (Komentor) human intestinal microbiotamicrobial communitiesBacteroideshypoxiainactivity inflammationconstipationgut metabolitesWe explored the assembly of intestinal microbiota in healthy male participants during the randomized crossover design of run-in (5 day) and experimental phases (21-day normoxic bed rest (NBR), hypoxic bed rest (HBR) and hypoxic ambulation (HAmb) (hypoxic ~4000 m simulated altitude)) in a strictly controlled laboratory environment, with balanced fluid and dietary intakes, controlled circadian rhythm, microbial ambiental burden and 24/7 medical surveillance. Intestinal transit spanning Bristol Stool Scale, defecation rates, zonulin, α1-antitrypsin, eosinophil derived neurotoxin, bile acids, reducing sugars, short chain fatty acids, total soluble organic carbon, water content, diet composition and food intake, intestinal electrical conductivity, sterol and polyphenol content and diversity, indole, aromaticity and spectral characteristics of dissolved organic matter, along with nuclear magnetic resonance metabolomics and trace metal makeup of intestinal environment were assessed. Furthermore (i) abundance, structure and diversity of intestinal butyrate producing microbial community sequencing butyrate pathway genes but and buk, (ii) structure and diversity of microbial community sequencing bacterial and archaeal 16S rRNA and (iii) taxonomic and functional description of bacteria, archaea and fungi using shot-gun metagenomics were investigated. Inactivity negatively affected fecal consistency and in combination with hypoxia aggravated the state of gut inflammation (p < 0.05). On the other hand many of the microbial parameters such as butyrate producing microbial community, the general bacterial and archaeal microbial community were shown to lag behind the changes in human physiology and intestinal environment, since significant changes in bacterial community were delayed until week four in HBR only, where members of the genus Bacteroides and proteins involved in iron acquisition and metabolism, cell wall, capsule, virulence and mucin degradation were enriched. This suggest a time-dependent and complex interplay between the host physiology (including apparent constipation), immunity (inflammation), controlled diet, intestinal environment variables and microbiome physiology during the acute cessation of exercise. Finally, yo-yo dieting and active/inactive lifestyle, along with its effects, seems not to be a human peculiarity but rather a common evolutionary adaptation of mammals to survive food shortage and seasons rotation.[R. Šket]20182018-04-12 07:45:14Doktorsko delo/naloga100755sl