Application Of PCR-DGGE Fingerprinting For Detection Of Shift In Microbial Genetic Diversity In Mn-contaminated Paddy Soils

Heavy metals in environment lead to great harm to organism and human being through discharging, transferring and gathering. Research on the effect of long-term exposure to heavy metals on structure and diversity of microbial community in soils could reveal the tolerance and adaptation of microbes and supply useful information for environment monitoring.Denaturing gradient gel electrophoresis (DGGE) is one kind of molecular biology methods for detecting mutation of DNA. Since traditional methods of cultivating require the use of media or substrates on which only 1.0-10% of soil microrganicsms can grow, applications of DGGE technique has been applied to soil ecosystem in recent years and has enabled the researchers to study microbial diversity at the molecular level.In this paper, the research findings and up-to-date research progress in here and abroad were introduced. It pointed out the importance of the microbial community structure and diversity in soil, and summarized the problems in the recent research. Furthermore, the developing trends of the technology were discussed in the end.Seven soil samples were collected from seven different sites near an abandoned manganese ore mine in Xiangtan. The contents of total manganese were 114~4611 mg/kg and the contents of extractable manganese were 61~1258 mg/kg. Manganese influenced the pH, organic C, total N and cation exchange capacity (CEC). The speciation of manganese in soil at different sites was studied. Bacteria were found being influenced negatively by manganese pollution.The profiles of amplified 16S rDNA sequences obtained from community DNA by denaturing gradient gel electrophoresis (DGGE) reflected the altered community structure and diversity along the manganese gradient as expressed in terms of the position and number of bands. Based on the profiles of DGGE, five bacterial populations were found in all of the soil-sampling sites. That observation may indicate that these five species are manganese resistant. Population and structure varied in bacterial richness among the low contamination sites, but with no sharp difference. The observed changes in the different soil microbial populations probably result from the combined direct and indirect effects of manganese contamination...