Metagenomic sequencing reveals altered gut microbiota of sojourners at high altitude: a longitudinal study

Human microbial alterations are associated with environmental stress, nutrition, genetic, and triggering de-novo variations. Nevertheless, the human gut microbiome at extreme altitude (> 5800 m) remains unexplored. We aimed to demonstrate the microbial predominance in individuals with the same ethnicity and dietary pattern at extreme altitude with unique challenges like cold, hypoxia, radiation, etc. Different analysis pipelines were used for fecal whole genome sequencing at 210 m, 3500 m, 4420 m and 5805 m, and 16S rRNA V3-V4 regions amplification sequencing of 19 individuals belonging to the same ethnicity and dietary pattern for the presence of taxonomy and functional potential and confirming the prediction up to the strain level within the same cohort. Principal component analysis revealed distinct microbiome changes at different altitudes, with varied and higher Bacteroides and Prevotella ratio. There was a predominance of genus Prevotella at altitudes 4420 m and 5805 m than at 210 m and 3500 m. The appearance of species Prevotella copri strain 61,740 increased significantly at extreme altitude, whereas co-occurrence of other bacterial strains had a different pattern than Prevotella. The extensive strain-level analysis indicated alteration in the metabolic pathways. This study under the stressful and hypoxic environment of extreme altitudes, associated microbial variation with altered metabolic pathways, reveals the influence of extreme environment on human gut microbiota with the predominance of Prevotella.