Passionate about microorganisms, Marc St-Arnaud holds a doctorate in biological sciences from Université de Montréal. He has worked at the Jardin botanique de Montréal since 1984, where he is a researcher in the Division of Research and Scientific Development. He is also a researcher at the Institut de recherche en biologie végétale and adjunct professor at Université de Montréal. He is interested in biodiversity and in soil microbial ecology. With his team, he seeks to understand how plants select bacteria and fungi that are beneficial to them, and to use that understanding in order to promote crop health and growth as well as to rehabilitate polluted soils.