Sarkis Mazmanian is a professor of microbiology at the California Institute of Technology. Research in his laboratory has provided evidence that bacteria in the intestines play important roles in the normal development and function of the immune and nervous systems. His findings suggest roles for certain gut bacteria in the pathogenesis of autoimmune disorders and Parkinson’s disease. He discovered that one species of gut bacteria can improve immune function and can ameliorate behavioral abnormalities in an animal model of autism.