Soil sample storage conditions impact extracellular enzyme activity and bacterial amplicon diversity metrics in a semi-arid ecosystem

Abstract

The analysis of microbiological and metabolic features of soils is an important aspect of soil ecology, but the results can be heavily impacted by sample storage conditions. Inconsistencies in storage methods and length of storage across studies reduce the ability to accurately collect field-based measures and compare results between projects. In this study, we examined the effects of various storage conditions and storage time on results of subsequent bacterial 16S rRNA amplicon sequencing and on activities of extracellular enzymes, using soil samples collected from three different land use types (annual cropping system, native rangeland, and riparian forest) in a semi-arid region of the Canadian Prairies. We found that when comparing enzyme activities and bacterial communities across different land use types, storage conditions may not have a significant impact. However, storage conditions were found to be important within a single land use type. Air-drying of soil samples caused significant shifts in enzyme activity and β-diversity from the controls. Storage at −80 °C was best for maintaining consistent enzyme activity and microbial α- and β-diversity compared to controls (i.e., freshly collected soil) across all three land use types and storage times. The results from this study provide useful information about the impact of sample storage conditions for researchers in similar climates and encourage further consideration and discussion of the impacts of sample storage, as well as the reporting of storage conditions used in future studies.