Defining the human microbiome.

Rapidly developing sequencing methods and analytical techniques are enhancing our ability to understand the human microbiome, and, indeed, how the microbiome and its constituents are defined. This review highlights recent research that expands our ability to understand the human microbiome on different spatial and temporal scales, including daily time series datasets spanning months. Furthermore, emerging concepts related to defining operational taxonomic units, diversity indices, core versus transient microbiomes, and the possibility of enterotypes are discussed. Additional advances in sequencing technology and in our understanding of the microbiome will provide exciting prospects for exploiting the microbiota for personalized medicine.