Interactive mechanisms of mineral dissolution by a microbial consortia
EMSL Project ID
50403
Abstract
Essential metabolic functions within ecosystems are often partitioned among various members of microbial communities that each benefit the whole population. For example, nitrogen fixation is carried out by specific diazotrophic bacteria, while other microbes specialize in metal or phosphorous mobilization through the production of organic acids and chelating agents that solubilize minerals. Such interdependencies structure microbial communities and can increase energy utilization efficiency and nutrient availability. Defining these interactions is critical for understanding the relationship between metabolic rates and elemental cycles in terrestrial and aquatic environments. In this study, we aim to elucidate the genetic and molecular basis of a symbiotic relationship between heterotrophic bacteria and a photosynthetic diazotroph, Trichodesmium. One of the hallmarks of Trichodesmium is the formation of multicellular colonies of millimeter scale that associate with a diverse assemblage of microbes that are dominated by heterotrophic epibionts. Recent work has suggested that these colonies are highly specialized for obtaining solid-phase nutrients, such as Fe minerals and dust, which are typically not available to other microbes. When growing under iron or phosphate deficient conditions, Trichodesmium colonies capture and actively shuttle oxide minerals along their filaments from the colony periphery to its core. The shuttling of dust to the colony center not only prevents its loss to the surrounding, but also facilitates its chemical manipulation by the colonies that result in bio-enhanced dissolution of Fe oxides and dust and increase iron (and possibly phosphorus) availability to the microbial consortium via and unknown mechanism. While Trichodesmium itself is not known to produce chelators for mineral dissolution, such as siderophores, some of the epibiont bacteria associated with Trichodesmium can, potentially enabling them to release siderophores into their surroundings in order to dissolve mineral-bound nutrients. The goal of the proposed work is to elucidate the chemical pathways by which Trichodesmium/epibiont consortia solubilize and take up mineral- associated elements. This project relies on a combination of advanced molecular approaches available at EMSL as well as metagenomic analyses available at JGI. We will investigate the chemical composition and spatial localization of secreted metabolites within Trichodesmium colonies using multimodal mass spectrometry, with the goal of observing the accumulation of metal chelates within dust-rich cores. Using omic analyses, we will determine which organisms produce these siderophores and which siderophore pathways are actively transcribed during mineral dissolution. Finally, we will examine the transfer of Fe from isotopically labelled iron oxides into specific Trichodesmium and epibiont bacteria using microscopy and nanoSIMS. Success will provide a genetic and molecular basis for mineral dissolution mechanisms that can be represented in ecosystem models of elemental cycling or engineered to improve bioenergy production.
Project Details
Project type
FICUS Research
Start Date
2018-10-01
End Date
2022-01-31
Status
Closed
Released Data Link
Team
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