Fig. 1.

Microbiota composition throughout life. The human microbiota is influenced by various factors unique to an individual, including differences in diet, environment, and exposure to antibiotics resulting in increases and decreases in microbial diversity throughout life. However, certain bacterial species confer greater protection against age-related decline. At birth, the infant's microbiota is initially influenced by the mother's microbiota and by the mode of birth. Through adolescence and adult life, the microbiota is altered by environmental changes during an individual's life. The microbiota is stable throughout adulthood unless there is a pressure that causes dysbiosis. The later stages of aging correspond to a decrease in diversity within an individual, but an increased diversity between elderly individuals. Considering the gut-bone marrow axis, the composition of an aged microbiota may influence the onset of age-related decline within HSCs and the hematopoietic system. Figure made by Adobe Suite.