The backstory to the motivation for launching Microbiome is a tale of two subdisciplines finding philosophical common ground fueled by substantial technological advancements in DNA sequencing and analysis. Until recently it was possible to neatly divide microbiology into two largely exclusive subdisciplines: clinical microbiology and environmental microbiology. Guided by Koch's postulates for more than a century, clinical microbiologists have excelled in connecting specific microorganisms with disease in animals and plants, and through basic research have suppressed infectious diseases - saving countless lives through disease treatment and prevention and greater food security. Motivated initially by the desire to exploit the biochemical capabilities of microorganisms, environmental microbiologists have uncovered the large diversity of physiological capabilities that allow microorganisms to thrive wherever there exists sufficient free energy to sustain a proton gradient and feed essential biochemical pathways with reducing power. Emergent from these research activities was the discovery of extraordinary diversity of microbial life on Earth that has forever altered our perception of the tree of life. A look back at the five-kingdoms tree illustrated on the inside cover of a circa 1984 freshman biology textbook is clear evidence of how far we have come in our appreciation of microbial diversity; new understanding made possible through basic environmental microbiology research.