Effect of soil sample preservation, compared to the effect of other environmental variables, on bacterial and eukaryotic diversity

Archived soil samples are a valuable source for retrospective ecological studies, and their recent analysis using molecular ecological approaches has drawn significant attention within the scientific community. However, the possibility of addressing ecological questions regarding detectable microbiota in dried and extensively stored soils has not yet been fully evaluated. To achieve this, soil samples collected from two long-term grassland experiments in the United Kingdom and The Netherlands were subjected to air-drying at 40–42 °C and stored at room temperature. Total bacterial, Bacillus benzoevorans-related and eukaryotic communities associated with these samples were analyzed by DGGE-fingerprinting of PCR-amplified ribosomal RNA gene fragments. Changes in microbial community structure due to drying and storage were evaluated by multivariate analysis in relation to changes caused by other environmental conditions, such as soil pH, type of fertilizer and vegetation. Soil drying and storage affected the detectable community structure, but did not materially impair our capacity to identify the effect of soil parameters studied in long-term grassland experiments. Although, in some cases, the amplitude of the influence of a given parameter changed due to sample preservation, analyses revealed that pH, fertilization and soil type significantly influenced microbial community structure in the analyzed samples.