[Effects of cadmium stress on the microbial biodiversity in purple soil and alluvial soil potted with a poplar (Populus deltoides x Populus nigra)].

Effects of current Cd contamination levels on microbial biodiversity were studied under the typical Cd contaminated soils in the Yangtze Basin. Purple soil and alluvial soil potted with a poplar (Populus deltoides x Populus nigra) were selected, and the culturable soil microbial amounts by flat method, microbial biomass and bacterial community structure by PCR-DGGE were investigated. Cd supplies significantly increased the culturable amounts of bacteria and actinomyces in purple soil, but decreased the culturable amounts of fungi and the content of microbial biomass N. Fingerprint of DGGE also showed that bacterial community structure have obviously changed under different Cd supplies. In contrast, the lower Cd supplies slightly increased the culturable amounts of bacteria and fungi in alluvial soil, but higher Cd supply treatment decreased the culturable amounts of bacteria, actinomyces and fungi, and the content of microbial biomass N. However, only a slight change was observed under different Cd supplies by DGGE fingerprint. Additionally, there were few effects of Cd supplies on the content of microbial biomass C in both purple soil and alluvial soil. The results provided basic data to understand the effects of present Cd contamination levels on soil microbial characteristics.