IWBT Stellenbosch University 1 article published in JoVE Bioengineering Workflow Based on the Combination of Isotopic Tracer Experiments to Investigate Microbial Metabolism of Multiple Nutrient Sources Audrey Bloem1, Stephanie Rollero2, Pauline Seguinot1, Lucie Crépin3, Marc Perez1, Christian Picou1, Carole Camarasa1 1UMR SPO, INRA, SupAgroM, Université de Montpellier, 2IWBT Stellenbosch University, 3PILI, Toulouse White Biotechnology This protocol describes an experimental procedure to quantitatively and comprehensively investigate the metabolism of multiple nutrient sources. This workflow, based on a combination of isotopic tracer experiments and an analytical procedure, allows the fate of consumed nutrients and the metabolic origin of molecules synthetized by microorganisms to be determined.