IMPACT OF SURFACE ADSORPTION ON DNA STRUCTURE AND STABILITY: IMPLICATIONS FOR ENVIRONMENTAL DNA (EDNA) INTERACTIONS WITH MINERAL SURFACES

Environmental DNA (eDNA) contains to large extent DNA present outside organisms and cells. Thus, eDNA can interact with various geochemical interfaces. Interactions of DNA with mineral surfaces may alter their structure, stability, and reactivity, thus affecting their retention time and genetic information cycling in the environment, and the reliability of eDNA-based detection and monitoring tools. However, our current understanding of these eDNA-surface interactions is poor, suggesting further studies are necessary to better understand the fate and transport of eDNA. Here, we have utilized spectroscopic probes, attenuated total reflection Fourier-transform (ATR-FTIR) spectroscopy and UV-Vis spectroscopy to investigate the interactions of herring testes DNA, a model system for eDNA, adsorption and stability on two commonly found iron oxides in natural environments, goethite and hematite. We found that DNA strongly adsorbs onto both goethite and hematite surfaces and the spectroscopic data suggest the common B-form structure is retained. However, due to additional interactions between the nitrogenous-bases of DNA and hematite surfaces, a distortion of B-form is observed on this surface. Furthermore, the stability of adsorbed DNA at different pH and temperature shows that specific surface interactions play a role in eDNA desorption and melting. Overall, our study underscores the importance of understanding mineral-specific eDNA-interface interactions in the environment and differences in eDNA stability, measured here in the melting kinetics, for different mineral phases.