Environmental DNA (eDNA) is trace amounts of DNA released by organisms into water and sediments. It has recently attracted a lot of attention as it can be a valuable tool for detecting present and past organisms without the need to directly sample them. However, biotic and abiotic decay has severe effects on DNA survival. The adsorption of DNA to mineral surfaces in sediments as well as saline conditions have been shown to protect DNA molecules and decrease the DNA decay rate. Understanding which minerals and environmental conditions provide the best preservation of adsorbed DNA can thus allow us to: a) target such environments for paleoecological and palaeogenetic studies; b) serve as a quantitative tool for assessing DNA migration, i.e. is the recovered eDNA autochthonous?; and c) significantly advance eDNA extraction and analysis protocols by targeting and extracting eDNA from specific minerals.
Currently, we only have a qualitative understanding of the DNA-mineral adsorption/desorption at the bulk level and we have no quantitative insight into the DNA-mineral interactions and solution conditions that enhance DNA survival, nor the combined impact on DNA longevity in natural environments. With DENMARK I will (1) assess DNA-mineral associations and correlate with eDNA preservation state in sediments from terrestrial, freshwater and marine settings. Additionally, for a range of sedimentary minerals and a range of environmentally relevant solution compositions I will: (2) quantify the Gibbs free energy (ΔGbu) and kinetic bond parameters of in vitro DNA-mineral interactions; and (3) examine the nature, fraction and stability of interacting bonds of in vitro DNA-mineral associations at the bulk level. (4) Finally, I will link the sediment data to the in vitro single bond and bulk data to make a conceptual model for addressing the characteristics and longevity of different DNA-mineral systems, and improve eDNA extraction protocols.
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