Impacts of earthworm introduction and cadmium on microbial communities composition and function in soil

•Earthworm introduction could favor the survival of aerobic bacteria.•Cd exposure increased the Cd-tolerant bacteria, reduced the Cd-sensitive bacteria.•Earthworm introduction and Cd exposure could shift soil microbial communities.•Cd exposure had a negative effect on functional pathways of soil microorganisms.•Soil tolerance to Cd can be improved by the increased Cd-tolerant microorganisms.