Evaluation of soil storage methods for soil microbial community using genetic and metabolic fingerprintings

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Soil microbes are essential functional components in soil ecosystems, involved in diverse biogeochemical processes. Storage of soil samples for soil microbial community analysis is sometimes inevitable because of large quantity of samples. The effects of storage on soil microbial community, however, is less revealed, especially using denaturing gradient gel electrophoresis (DGGE) and community level physiological profiling (CLPP), the most widely used techniques for microbial ecology. We stored forest land (FL) soils and arable land (AL) soils at 4 °C after air drying (AirDrying) or at −20 °C with field moisture (Freezing) for two month, and then the microbial community structures and metabolic activities in the stored soils were compared to those in the fresh soils, using PCR-DGGE profiling and Biolog® microplate. Similarity coefficients indicate that both storage methods shifted microbial community structure depending on soil types and microbial types. Microbial community in AL soils is more stable than that in FL soils, and fungal community is more stable than bacterial community. Freezing changed microbial community less than AirDrying based on genetic fingerprinting, however, microbial metabolic activity was greatly decreased by both storage methods. Our results suggest that, fresh soils are the best choice if microbial metabolic activity is under investigation while freezing at −20 °C for less than two months is acceptable if microbial community is studied on the basis of genetic fingerprinting.