ABSTRACT
Horizontal gene transfer is the one of the most important drivers of bacterial evolution. Transformation by uptake of extracellular DNA is traditionally not considered to be an effective mode of gene acquisition, simply because extracellular DNA are considered to degrade in a matter of days when it is suspended in e.g. seawater. Mineral surfaces are, however, known to preserve DNA in the environment, and sedimentary ancient DNA studies have solidified there are considerable amounts of fragmented DNA stored in sediments world-wide. Recently the age of stored DNA was increased to at least 2 ma highlighting that sediments represent a rich resource of past traits. It is well established that bacteria can acquire large kilobase DNA molecules adsorbed to mineral surfaces. Here we show that Acinetobacter baylyi can incorporate 60 bp DNA fragments adsorbed to a wide range of common sedimentary minerals. Our recorded transformation frequencies vary with mineral types and scales inversely with mineral surface charge and the ability of the mineral to immobilize the DNA in a liquid environment. We argue that the influence of mineral surface properties introduces interfacial geochemical processes as drivers for evolution and provide sedimentologic processes a central role in the evolutionary avenue of selection.
Competing Interest Statement
The authors have declared no competing interest.
