The Characteristics Of Community Structure And Abundance Of Disimilatory Iron-reducing Microorganism In Paddy Soil During Flooding Process

Dissimilatory iron-reducing microorganism plays an important role on the decomposition of organic matter, the suppression of methane production, the bioremediation of heavy metal pollution with valence fluctuation, and the transformation of phosphorus, sulfur and other nutrient elements.In this study, total DNA was extracted from different treatments of flooding incubation. The changing characteristics of community diversity and succession of dissimilatory iron-reducing microorganism were analyzed by using denatured gradient gel electrophoresis (DGGE) based on16S rRNA gene(rDNA) of Dissimilatory iron(Ⅲ) reducer The influence factors on characteristics of community diversity and succession of dissimilatory iron-reducing microorganism in different flooding treatments were analyzed by PCA. The dynamic variation of community structure resulted from different flooding time will provide important theoretical foundation for soil remediation by the dissimilatory iron-reducing microorganism.The main results of HZ paddy soil were as follows:(1) The result of PCA based on digitized DGGE patterns and Quantity One showed that the changes of the community structure of Geobacteraceae and Bacillus were stable at the end of flooding incubation.(2) From the a diversity indices based on PCR-DGGE, We can find that in HZ paddy soil the Geobacteraceae have the highest differences between1h and Id. While the lowest between20d and30d. The Bacillus has the highest differences between1h and5d while the lowest between20d and30d.(3) The abundance by Real-time PCR showed that in HZ paddy soil the abundance of Bacillus and Geobacteraceae were the highest in flooding Id treatment, and the lowest in flooding10d.(4) The phylogenetic tree of preponderant DGGE bands showed that there are some generalities on Geobacteraceae and Bacillus in paddy soil in China. We can find that Geobacteraceae and Bacillus have the greateat potential for the soil bioremediation.The main results of GZ paddy soil were as follows: (1) The result of PC A based on digitized DGGE patterns and Quantity One showed that the changes of the community structure of Clostridium and Bacillus were stable at the end of flooding incubation.(2) Microbial reduction of iron(Ⅲ) changed greatly in early time and was stable after incubated for25d in GZ paddy soil, iron(Ⅲ) reduction potential was4.07mg/g and the Vmax was0.35mg/(g.d) at the time of3.97d and achieved plateau after20days flooding.(3) The relative abundance of Bacillus and Clostridium were the hightest at flooding1d treatment, and the lowest at flooding1h treatment.(4) The diversity indices of Clostridium were the hightest at20d while the lowest at1d. The diversity indices of Bacillus showed that the highest at lOd while the lowest at30d.(5) The phylogenetic tree of preponderant DGGE bands showed that there are some generalities on Bacillus and Clostridium in paddy soil. Also, we can find that the sequences of Bacillus and Clostridium can get together with the sequences from the soil bioremediation.We can conclude according to the above results that the dynamic variation of diversity, community structure and abundance are closely related to microbial iron(Ⅲ) reducing in flooding paddy soil.