Testing of various environmental sample preservation methods for microbial ecology studies

Sampling for microbial DNA in remote locations is often limited due to the lack of access to a freezer to store the samples. Here, we tested the efficacy of various methods allowing to store samples at ambient temperature (desiccation, ethanol or commercial solutions) for up to three weeks and compared these methods to freezing at -20C and immediate extraction (i.e., the gold standard). The treatments were applied to various sample types: organic and mineral soils, roots and rhizosphere, and leaves of decideous and coniferous trees. Following the preservation treatment, DNA was extracted and used for metabarcoding analyses of bacterial (16S rRNA gene) and fungal communities (ITS2 region) to assess the efficacy of the various methods.