Stable Isotope Tracing in Microbical Secretions to Capture Soil Carbon Cycling Dynamics

Carbon turnover in soils is a critical component of the global carbon cycle. Microbial metabolism, which is influenced by oxygen availability, drives carbon transformation in soils. Traditionally, stable isotope tracers in DNA have been used to identify active microbial players. Metabolic potentials for carbon turnover are then inferred based on gene-based predictions. However, to interpret or validate these predictions, direct annotation of metabolic activities remains a major challenge. Metabolomics, an emerging omics technique that profiles the chemical fingerprint of metabolic reactions, provides an instrumental approach to address this challenge. In this talk, I will present the first investigation of my postdoctoral work that explores the application of metabolomics analyses of soil water extracts. Specifically, 13C tracers in metabolites in soil solutions were used to capture microbial metabolic activities in soils subjected to different redox conditions. My findings show that such metabolomics measurements can provide insights to support or resolve DNA-based predictions of relevant metabolism involved in soil carbon cycling. In ongoing projects, I continue to implement metabolomics approaches to understand carbon transport in a watershed in relation to ecosystem metabolism.

Bahareh Hassanpour is currently a postdoctoral research associate in the Aristilde Research Group in the Department of Civil and Environmental Engineering Northwestern University. Her research interests are in nutrient cycling,fate, and transport. Prior to joining Northwestern, Bahar earned her Ph.D. degree at Cornell University, studying hydrological controls on non-point source pollution (nitrate and pesticides) removal by the edge-of-field techniques that utilize organic substrates. Interested in the molecular understanding of carbon cycling, she is working on applying metabolomics approaches to investigate carbon cycling in soil and riverine systems.