Microbial therapies developer Commense has appointed Edward “Tad” Stewart to serve as the Boston company’s president and CEO. Stewart was most recently chief business officer of Cambridge, MA-based Crescendo Biologics. Before that, he spent 15 years at Merrimack Pharmaceuticals (NASDAQ: [[ticker:MACK]]) as senior vice president, business development. Commense emerged from Boston startup creator PureTech in 2016 to develop “therapeutic cocktails” of microbes intended to inoculate children against disease.