ABSTRACT
Studies on the human microbiome usually focus on bacteria, which are considered the most important in terms of both biomass and function. A goal of human microbiome analyses is the identification of organisms that are associated with, and potentially contributing to, a specific host state, such as disease, geographic origin, diet, and medical treatment. In the first years of life, a healthy human gut microbiome changes in composition and shows an increase in complexity as it matures. A veritable industry has blossomed around direct-to-consumer microbiome sequencing. Fecal microbiota transplantation to treat recurrent infection with the bacterium Clostridium difficile represents a major success story in microbiome manipulation with clinical consequences. Microbiome composition also influences the efficacy of cancer immunotherapy. Targeting gut microbiome function is showing potential in addressing the long-term consequences of early childhood malnutrition, where development is impaired despite subsequent increased caloric intake.
