THE MINERAL-WATER INTERFACE AFFECTS THE STABILITY OF POLYMERS IN THE ENVIRONMENT DIRECT IMPLICATIONS FOR THE EVOLUTION OF LIFE? (Invited Presentation)

Polymers adsorbed to minerals are more resistant to degradation and have higher longevity in the environment compared to adsorbed polymers. The nature of the mineral-water interface determines the adsorption and desorption capacity of the polymers as well as the stability of the polymer-mineral complex. The prolonged stability of DNA adsorbed to minerals is a key parameter for our newly proposed hypothesis of mineral facilitated evolution of life.

Free DNA (not part of a dead biomass) are, in general, degraded in a matter of weeks in aqueous solutions. However, the DNA stability is dramatically increased when adsorbed to minerals. Free DNA is found in the majority of Earth's surface ecosystems and up to 95% of it is estimated to be associated with minerals. On a global scale, there is currently ~0.4 Gt of free DNA in the uppermost 10 cm of marine sediments. DNA adsorbed to minerals can get transferred to organisms and incorporated in their genome through the process of horizontal gene transfer (HGT). We think that that once geologic processes start acting on such a vast “mineral archive of genes”, minerals can function as protective shuttles propagating DNA across environments and enabling transfer of the adsorbed genetic material to distant species in different ecologic niches.

We hypothesize that minerals hold an unrecognized potential for propagating adaptive traits across environments and timescales to distant organisms and that this process has significantly impacted the evolution of life. The hypothesis will be illustrated in the context of the evolution of early microbial life and emphasis will be placed on the role of the mineral-water-polymer interface for both adsorbing and preserving the DNA.