Sustained soil-to-soil contact as a new approach to experimental microbiome transfer

The reproducible transfer of microbiomes between soils would greatly facilitate controlled investigations of soil microbial ecology, microbiome impacts on soil function and health, and plant-microbiome interactions. Although a variety of approaches to soil microbiome transfer are described in the literature, a common method involves directly diluting the source soil into a sterile recipient soil at various concentrations. In addition to transferring microorganisms, this approach also transfers soils particles and compounds from the source soil, proportional to the amount of soil transferred, which can make it difficult to determine the impact of soil characteristics on the resulting microbiome structure or plant-microbiome interactions. Transferring a low percentage of source soil also results in low microbial diversity in the recipient soil. In this study, we used 16s rRNA amplicon sequencing to explore the use of prolonged contact between source and recipient soils across membrane filters as an approach to microbiome transfer, and contrast this with the direct transfer of soil at two concentrations from three different source soils.