Professor Dr Ruth Ley

Research Priorities: Ecology and evolution of the human gut microbiome 
Ruth Ley is a developmental biologist and microbiologist. She is researching the ecology and evolution of the human gut microbiome and its links to health. 
The gut microbiome is made up of trillions of microbial cells. Together they perform services for the host ranging from food digestion to protection against pathogens. Interpersonal differences in microbiome composition and function are emerging as important for differences in various health and disease states, raising questions about how the microbiome interacts with its host to impact health and other aspects of host biology. Ley and her lab are working on fundamental questions about the evolutionary origins of the human gut microbiome and how it influences host physiology and evolution. 
Her group was the first to identify specific members of the human gut microbiome whose relative abundance in the gut microbiome is explained in part by the genotype of the host (so-called ‘heritable’ microbiota). They now use this list to guide their studies: what is special about the heritable microbes? What is it about human genetic variation that they respond to? 
For instance, within the human gut microbiome, bacteria of the little-studied family Christensenellaceae are highly heritable. Ley and her team showed that these bacteria are also, along with a suite of other microbiota, enriched in lean versus obese individuals, and could demonstrate causality in germfree mice. Currently, they are delving into the multi-part symbiosis of these bacteria and archaea. The aim is to elucidate how they interact with each other and with the host to impact phenotype.