Structure, functions, and diversity of the healthy human microbiome.

Taxonomic composition and functional potency of microbes associated with different parts of the human body have largely been explored by culture-independent metagenome sequencing. The diverse microbiota living throughout the human body is made up of thousands of microbial taxa from all three domains of life: Archaea, Bacteria, and Eukarya. Microbial load and functional potency in different body sites are well distinct and have minimal resemblance at higher taxonomic levels between the two habitats. The highest microbial load, diversity, and functional potency including biosynthesis of essential nutrients, chemical modifications of dietary components, and sources of immunomodulatory molecules, are found in the gut microbiome. However, the inter-individual diversity and dynamics of the human microbiome in a given body habitat vary greatly over time. Both environmental factors and host genetics contribute significantly to shaping microbial community structure and its stability. A basic understanding of native microbial compositions and their functional potency and stability in different parts of healthy humans living across geography will help us to identify disease-specific microbiota and develop potential microbiome-based therapeutics. Here, we updated our current understanding of the diversity, dynamics, and functional potency of microbiomes associated with different parts of the human body.