An Overview of the Human Microbiome

The human body exists in a close, mutually beneficial relationship with its resident microorganisms: bacteria, archaea, fungi, and viruses. Methods that enable the study of the human microbiome have developed over the past several centuries—from Antonie van Leeuwenhoek's discovery of single-celled microorganisms, to Koch's innovations in isolating and studying bacterial cultures, to Woese and colleagues' pioneering work on sequencing small subunit ribosomal RNAs. In the current era, metagenomics techniques enable researchers to identify the bacteria that exist in an entire population and the functions encoded by the bacterial genes. Several large-scale projects have begun to characterize the range of variation of the human microbiome in healthy individuals: in particular, the Human Microbiome Project and the Metagenomics of the Human Intestinal Tract project (MetaHIT). Researchers continue to investigate aspects of the human microbiome in further large-scale projects around the world.