Effct of Continuous Cropping of Different Vegetables on DNA Polymorphorism of Soil Bacterial

Soil bacterial communities were examined by culture-independent means, namely, 16S rDNA-nested PCR-DGGE profiling. Crude DNA was extracted from soil grown with different vegetables for different years, amplified with bacterial specific primers of 16S rDNA by PCR, and separated by denaturing gradient gel electrophoresis (DGGE). Subsequently, bands on DGGE gels were cloned, sequenced and the resultant information was used to infer the diversity of bacteria in different soils. The results showed that soil samples collected from same area had the high identity in DGGE bands patterns. Bacterial community structure was significantly influenced by continuous cropping system. The effects were closely related to the kind of vegetables and the history of continuous cropping. The sequence results showed that most of the bacteria belong to Proteobacteria; Acidobacteria, Sphingobacteria and Actinobacteria also appeared in the continuously cropped soils.