The Human Microbiome

Abstract

Humans have coevolved with the trillions of microorganisms that inhabit their body, namely human microbiome. The human microbiome, especially gut microbiome, has gained an extensive interest over the last decades due to state-of-the-art technology and large-scale metagenomics studies that attempt to unravel the mystery of this complex, heterogenous ecosystem and its repercussions to host physiology. Bacteria have been the center of attention across research literature, but here an overview of the role of fungi, archaea, viruses, and protozoa is addressed as well. The aim of this chapter is to explore the diversity of taxonomic composition of human microbiota and their pivotal role in regulating host metabolism, immune system, and protection against invading pathogens. The chapter also focuses on the potential external factors (initial colonization, diet, lifestyle) prompting variable configurations of human microbiota that lead to imbalance of homeostasis (dysbiosis) and result in a broad spectrum of pathological diseases, such as obesity, inflammatory bowel disease, and Clostridium difficile-induced diarrhea.