Peter J. Turnbaugh (born c. 1981) is a microbiologist and an Associate Professor at University of California, San Francisco. He is known for his research on the metabolic activities performed by the trillions of microbes that colonize humans' adult bodies. Turnbaugh and his research group use interdisciplinary approaches in preclinical models and human cohorts to study the mechanisms through which the gut microbiome influences nutrition and pharmacology.