The preservation of bacterial community legacies in archived agricultural soils

Archived soils are immensely valuable and irreplaceable samples for microbial ecological research, allowing reanalysis of published data and direct comparison across studies using the latest technologies. However, comparatively few studies have explored the influences of prolonged archived soil on the preservation of soil microbial community. Here, archived fertilized soils (DS) and frozen soils (FS) stored at − 80 ℃ for as long as 7-year were sequenced for reconstructing soil bacterial communities. The archived soils treated with propidium monoazide (PMA) to remove extracellular and dead microbes DNA (relic DNA) were also considered (DSP). The results showed that the prolonged desiccation had strong impacts on bacterial diversity and community structure. Removal of relic DNA improved the accuracy of bacterial diversity by 13.3% and total taxonomic turnover by 4.27%, and reduced the differences of bacterial community structure between archived and frozen soils. Archived soils preserved over 90% sequences of bacterial phyla, while bacterial genera exhibited various life-strategies to desiccation stress. Nevertheless, prolonged desiccation did not significantly distort the fertilization legacies on bacterial diversity, community structure and resistance. Moreover, soil archives destabilized bacterial co-occurrence pattern with higher node degree and lower path distance relative to frozen soil, while the relic DNA removal from archived soils improve these properties. Together, these findings revealed that the effects of desiccation on soil bacterial communities could be improved by removal of relic DNA, and the fertilization legacies of bacterial communities were still identified using the archived soils even stored as long as 7-year. This provided the great value of worldwide archived soils that might be applied in microbial ecology research.