Comparison of Soil Bacterial Diversity in Rotation and Monocropping Soil in Tobacco Growing Area in Yuxi, Yunnan, China*

Abstract

To evaluate the responses of soil bacteria community to two different tobacco cropping systems(rotation and monocropping),soil bacteria were examined by culture-independent means,namely,16S rDNA PCR-DGGE profi ling.Crude DNA was extracted from the rotation and monocropping soil,amplied with bacterial specific primers of 16S rDNA by PCR,and separated by denaturing gradient gel electrophoresis(DGGE).Subsequently,bands on DGGE were used to infer the diversity of bacteria in the rotation and monocropping soil.Three duplications of each treatment in the DGGE profile had higher similarity,almost getting together,showing the experiment premise for operation method.From the DGGE profile,the bacterial community bands in the rotation soil were found about 13～29,with average of 21,but the bands in the monocropping soil about 4～20,with average of 12.The comparison of the electrophoretic bands and optical density value with each index of bacterial richness and diversity showed the richness of the bacterial community in the rotation soil was higher than that in the monocropping soil.The Shannon-wiener index and Simpson index(1/D) of the rotation soil were all higher than those of the monocropping soil,which indicates that the rotation farming system can improve the bacterial diversity of soil.