Compositional changes in human gut microbiota reveal a putative role of intestinal mycobiota in metabolic and biological decline during aging

BACKGROUND: Age-related alterations in the composition and function of gut microbiota may influence human health and disease mechanisms. However, connections between compositional changes in gut bacterial and fungal communities, and their role in the aging process, remain poorly understood. OBJECTIVE: Compare the gut microbiota and mycobiota composition in different age groups and evaluate the functionality. METHODS: In this study, we performed 16S rRNA and ITS2 gene-based microbial profiling analysis and shotgun metagenomics using the NextSeq platform. RESULTS: We observed a shift in compositional changes of human gut microbiota with age. Older individuals revealed a significantly different gut microbiota profile compared to younger individuals. For example, gut microbiota composition of the older individuals showed increase in genera Bacteroides, Blautia, Ruminococcaceae, and Escherichia coli. Additionally, older individuals had significant reduction in fungi belonging to saccharomyces cerevisiae and candida albicans in comparison to their younger counterparts. Moreover, metagenomics functional profiling analysis using shotgun metagenomics sequencing data showed substantial differences in the enrichment of 48 pathways between the young and older age groups. Metabolic pathways such as amino acid biosynthesis, carbohydrate metabolism, cell structure biosynthesis and vitamin biosynthesis were declined in the older age group, in comparison with the younger individuals. CONCLUSIONS: The identified differences provide a new insight to enrich our understanding of age-related changes in gut microbiota, their metabolic capabilities, and potential impact on health and disease conditions.