Cadmium (Cd) is a toxic heavy metal that influences soil ecosystems, especially the sensitive microorganisms.

Natural soils likely have different properties, and most studies have focused on a single soil type, making it difficult to generalize regarding the impact of metal bioavailability (relating to microbial activity) on microbial diversity and function.

To investigate the effect of Cd on bacterial abundance in different soil types, we collected five types of soil (OECD artificial soil, brown forest soil, andosol, sand, and gray lowland soil) that were not contaminated with cadmium, air-dried, and passed through a 2-mm sieve before use. The pre-moistened soils were incubated for 1 week with 25% of the water-holding capacity (WHC) of each soil; then, Cd (0, 5, 15, 50, 150, 400,1000 and 3000 mg/kg) were added to samples and incubated for 2 weeks at 50% WHC. The soil bacterial abundance after incubation with Cd was analyzed using a real-time pcr assay.

We found that adding Cd significantly reduced the bacterial abundance. Different soils also showed differences in abundance with increasing Cd concentration. The effect of Cd on bacterial abundance in different soil types is discussed.