Are ultra-low temperatures required for transporting soil samples for microbial sequencing?

Proper preservation and transport of freshly collected soil samples provides initial fidelity for microbial sequencing, but has been overlooked. We selected and tested four transport conditions: dry ice, frozen, refrigerated, and room temperature, and conducted a detailed DNA-based analysis of the microbial communities in an undisturbed forest soil sampled in a remote area. Compared to storage for 6 h on dry ice, the microbial and genetic compositions had changed significantly under other conditions for 6 h, while they maintained relatively stable when preserved on dry ice for 48 h. Thus, transporting soil samples from the field for microbial sequencing and analysis strictly requires ultra-low temperatures, such as generated by dry ice.