Abstract: Microbes and minerals play a critical role as catalysts in the cycling of carbons and nutrients in natural soils and waters. For instance, microbes in soils and rivers are involved in catalyzing the degradation of plant matter and contaminants, contributing to the carbon cycle and the fate of contaminants. Minerals in soils and sediments can catalyze organic matter transformation, contributing to the release of available nutrients for plants and microbes. In my group, we seek to understand the mechanisms underlying these natural catalytic reactions mediated by microbes and minerals. Our research objectives are to (1) advance accurate prediction of these processes in the face of current human activities and projected climate change and (2) advance new avenues in nutrient recycling and carbon waste conversion important to a sustainable circular economy. In this talk, I will highlight two of our recent research accomplishments. First, I will present on the mechanisms of plastics degradation and metabolism by Comamonas bacteria that are associated with microplastics in wastewaters and urban rivers. Second, I will present on the enzyme-like catalysis of natural iron oxide minerals in organic phosphorus recycling, highlighting a missing piece in the phosphorus cycle important to agricultural productivity and food security. These two examples will be discussed within the context of their importance in natural cycling processes and their potential to innovate engineered recycling processes.

Bio: Ludmilla Aristilde is an Associate Professor in the Department of Civil and Environmental Engineering at Northwestern University. She holds courtesy appointments in the Department of Chemical and Biological Engineering, and the Department of Earth, Environmental, and Planetary Sciences. Dr Aristilde is affiliated with the Center for Synthetic Biology, the International Institute of Nanotechnology, and the Trienens Institute for Sustainability and Energy. The Aristilde Research Group applies has developed a reputation in combining experimental and theoretical approaches to unravel the (bio)chemical mechanisms that control environmental organic processes. Research findings have led to new understanding of the biogeochemical pathways in microbial carbon cycling, enzymatic and mineralmediated phosphorus recycling, and for rationale engineering in biotechnology for lignin and plastic recycling. Dr Aristilde received her B.S. and B.F.A at Cornell University, both M.S. and Ph.D. degrees at the University of CaliforniaBerkeley, followed by a Fulbright fellowship in France and training as a NSF postdoc Fellow at Princeton University. Dr Aristilde started her academic career as an Assistant Professor at Cornell University and was promoted to Associate Professor with tenure in 2018. In 2019, Dr Aristilde and her group moved to Northwestern University. Dr Aristilde has authored 70 publications, is an Editor on several academic journals, and is on the Advisory Board of several research centers, including the Delaware Environment Institute and the Center for Chemical Currencies of a Microbial Planet at the Woods Hole Oceanographic Institute.