Associations between the infant gut microbiota and the living environment

The human gut microbiota is central to the health and development of the host, and the early-life microbiota is affected by a range of factors that can alter the infant's development for years to come. The role of the external, natural environment in shaping the gut microbiota is still largely unknown. We examined how the environment surrounding the home postnatally is associated with the infant gut microbiota in the first 2 y of life. The study utilized 16 s rRNA data from 893 children's fecal samples from the longitudinal birth cohort HELMi. We show that the environment has a minimal overall association with microbiota development (R² < 1%). Air quality explained the greatest degree of variation in microbiota composition, while only forests, agriculture and inland wetlands near the home had any significant association with bacterial genera. The results suggest that the infant gut microbiota is not strongly dependent on the external natural environment, and that the impact of the environment is mostly due to exposure to air pollution that may affect the host's immune system and indirectly the gut microbiota.