Studying the uninvited guests

Mitchell has been working with samples collected by a local biotech company developing biotherapeutics for the gut. Its probiotic products, which are used to treat recurrent C. diff infections, contain eight closely related microbial strains belonging to the order known as Clostridiales. The company gave one of its products to 56 human subjects and collected stool samples over time. Mitchell is using genetic sequencing techniques to track how three of the microbial species evolved in 21 of the subjects. Identifying person-specific differences and similarities might reveal insights about the host environment and could help explain why some types of mutations allow some microbes to survive and thrive. The project is still in its early phases, but Mitchell has a working hypothesis. “The model that I have in my mind is that people have different [gut] environments, and microbes are either compatible with them or not,” she says. “And there’s a window in which, if you’re a microbe, you migh ... Read full article.