Jan Claesen is an Assistant Staff faculty member at the Lerner Research Institute at Cleveland Clinic and an Assistant Professor of Molecular Medicine at Case Western Reserve University. Jan received his PhD in Molecular Microbiology in 2011 from the John Innes Centre and University of East Anglia, Norwich, United Kingdom. During his graduate studies, Jan was in the lab of Prof. Mervyn Bibb, where his main focus centered on the genetics and biosynthesis of Ribosomally synthesized and Post-translationally modified Peptides (RiPPs). Genetic and biochemical characterization of the biosynthetic gene cluster (BGC) for the anti-leukemia compound cypemycin led to the identification of the linaridins, a new class of RiPPs containing unique amino acid modifications. Near the end of his PhD, Jan was a finalist in the UK Microbiology Society’s ‘Young Microbiologist of the Year’ and he won the 2009 ‘John Innes Foundation Prize for Excellence in Science Communication’. After his graduate studies, Jan was a postdoctoral scholar in the lab of Dr. Michael Fischbach at the University of California, San Francisco. There, his research focused on the identification of novel biosynthetic pathways and characterization of bacterial metabolites that mediate microbiota interactions in the healthy human microbiome. He was involved in the functional validation of the ClusterFinder algorithm, an important resource for natural product drug discovery and secondary metabolism. ClusterFinder was used to generate an overview of bacterial biosynthetic diversity and Jan’s experimental validation led to the identification of aryl polyenes as products of the largest family of uncharacterized BGCs. A second major focus of Jan’s postdoctoral research was the characterization of bioactive molecules from the human skin microbiota. He identified porphyrins as mediators for biofilm formation by Staphylococcus aureus, implicated a cell-surface molecule from commensal Corynebacteria in interaction with the host immune system, and discovered a potent anti-S. aureus antibiotic produced by specific commensal strains of Propionibacterium acnes. In November 2017, Jan joined the Department of Cardiovascular and Metabolic Sciences at the Lerner Research Institute as an Assistant Professor. The Claesen lab uses a combination of genetic and biochemical techniques to elucidate the molecular mechanisms that drive community dynamics and microbe-host interactions in the human gut and skin microbiome, and to engineer commensal bacteria for fundamental and translational applications. Ongoing research projects in the lab include gut microbial conversions of dietary molecules, functional characterization of aryl polyenes in bacterial pathogenesis, and bacterial molecular signaling in the gut and skin microbiome.