Forest soil bacterial and fungal communities response towards different mercury contamination levels

Mercury (Hg), present naturally on earth, can reach high concentrations in the environment due to anthropogenic activities, but little is known on its impact on the soil microbiome. The effect of increasing Hg contamination on bacterial and fungal communities were tested with 84 soil microcosms. Seven forest soils were spiked with increasing amounts of Hg (0, 0.32, 3.2 and 32 µg Hg2+ g-1 dry soil). Mercury concentration higher than 3.2 µg Hg g-1 dry soil was found to cause severe diversity loss, shifts in the bacterial and fungal community structures and changes in the relative abundances of bacterial and fungal taxa, whereas lower concentrations of Hg had only a limited effect on the soil microbiome.