Linking Carbon Source-Dependent Metabolism and the Chemical Diversity of Bacterially-Secreted Metal Scavenging Molecules.

Carbon cycling and metal acquisition strategies by soil microorganisms are tightly linked. Previous published studies have shown that both high- and low-affinity metal scavenging organic molecules mediate dissolution of minerals. We investigated the metabolic link between organic carbon utilization and secretion of these molecules in the ubiquitous soil bacterium Pseudomonas putida grown on three common carbon sources (glucose, succinate, and acetate) under high-iron and low-iron conditions. We applied liquid chromatography-high resolution mass spectrometry to characterize the structures of the siderophore pyoverdine and ten small carboxylic acids secreted in response to the different carbon sources. Our current progress on the use of stable isotope-assisted metabolomics to determine how intracellular carbon metabolism of the different carbon sources influences extracellular secretions will be presented. The relevance of the carbon-dependent bacterial secretions on metal scavenging from minerals was examined via dissolution experiments of Fe-, Mn-, Al-, and Si-bearing minerals. These findings shed light on the role of carbon metabolism in directing metal scavenging molecules produced by soil bacteria.