Analysis of Microbial Community Structure in the Denitrification-Dephosphorization System Based on PCR-DGGE Technique
|Keywords||16S rDNA PCR-DGGE Community Structure biological denitrification-dephosphorization activated sludge|
The microbial community structure of activated sludge from an anaerobic-anoxic-aerobic denitrification-dephosphorization system were investigated by the molecular biological technology—PCR-DGGE（polymerase chain reaction-denaturting gradient gel electrophoresis）. On the other hand, the effect of total DNA extraction methods from activated sludge, and the change in microbial community structure depending on pattern polymer/multimer were demonstrated by the analysis of results of PCR-DGGE.The removal efficiencies of A-A-O procedure on CODCr and TP were both high, 90% and 95%, respectively; and of TN was only 65%.Effects of total DNA extraction from activated sludge with/without pretreatment were compared by three kinds of cell lysis methods, i.e. sonication irradiation, glass bead shaking and freeze-thawing process in a denitrification-dephosphorization system. By detection of ultraviolet adsorption spectrum analysis and agarose gel electrophoresis, results showed the DNA samples with high yield and purity were obtained by TENP and PBS pretreated, and 2%SDS and freeze-thawing lyzed, and did PCR analysis directly without purification.Using PCR-DGGE technique, the microbial community structure of activated sludge in different reaction region of wastewater treatment system was investigated. The DGGE fingerprinting showed that there were abundant species of organism existing in the system, and the microbial community structure was stable. The microorganism was inevitably flowed by the flow of the sludge, so the bacteria distribution in the reactor was equable. So there were few changes in the community structure of different reaction region. The sequence was determined through comparison with GenBank（NCBl）: （1） 16S rDNA sequences corresponding to 6 excised bands from activated sludge samples were analyzed and classified into three lineages of the bacteria, including Proteobacteria; Actinobacterium; Nitrospira sp.; and the Proteobacteria and Actinobacterium were the domain bacteria. （2）The most differences of microbial communities in the anaerobic-anoxic-aerobic region of the wastewater biotreatment system were Actinobacterium andγ-Proteobacteria. The number of Actinobacterium was more in the anaerobic and anoxic region, ofγ-Proteobacteria in the aerobic region. And combined with the water quality, the ecology of the proeess, the microbes involved, their functions of the denitrification and dephosphorization were interpreted more which little is still known before. Distribution and transformation of molecular weight of organic matters in a wastewater treatment system was monitored by ultra-filtration membrane method. The characteristics of the molecular weight distribution of organic matters and the amounts of the organic fractions in different molecular weight ranges were measured. The results showed that the organics on the fraction of molecular weight less than 1k had the largest ratio in the total organics of the outlets in the anaerobic、anoxic and aerobic tank.The influence of pattern polymer/multimer for microbial community structure was investigated by the analysis of results of denaturing gradient gel electrophoresis （DGGE）. The results of DGGE were that the microbial community structure of activated sludge in different reaction region of wastewater treatment system was similar, and the quantity of only little microbial showed simple change of regularity, which exemplify the stability of the microbial ecology in the process of biological denitrification and dephosphorization.