Application Of DGGE To Monitor Microbial Community Structure And Succession Of SBR During Start Up And Deteriorate Period

Biological phosphorus removal system is a complex microbial community. It is significant to notice the microbes'species and composition for understand phosphorus removal process and keep a good operation. Pure culture presents the localization to catch the real-time and efficient information. Molecular biological methods such as PCR, DGGE, FISH etc. gets its application more and more extensively on this field. Parameter optimized DGGE protocol is used to analysis the microbial community structure and succession in start up and deteriorate period of a SBR phosphorus removal system.The period of start up lasted 30 days. In the former 15 days, it hadn't reached a good phosphorus removal effort. The reason was that Type 0803 filamentous bacterium and Uncultured alpha proteobacterium had competition on Polyphosphate Accumulating Organisms (PAOs). The quanatity of PAOs was relatively less. In the following time, phosphorus removal rate increased rapidly. Tetrasphaera elongate, Gemmatimonas aurantiaca and Uncultured gamma proteobacterium existed in a large amount as founctional microbes and Candidatus Competibacter phosphatis clone SBRQ22 are rather less, which led to rapid increase of phosphorus removal efficiency. After the achievement of stable phosphorus removal, Thauera sp., Uncultured gamma proteobacterium and Tetrasphaera elongate were dominant in reactor.Sludge samples of supernatant, discharge sludge and mixed liquid in the 81th day (deteriorate period) were chosen for DGGE analysis. The results showed that microbial groups of supernatant and discharge sludge were basically the same with the different quantity separately. The DGGE profiles of discharge sludge and mixed liquid were rather similar. Tetrasphaera elongate and Gemmatimonas aurantiaca were still the function microbes which can not lead to a higher phosphorus removal because of their less quantity. Uncultured bacterium clone SBRQ157,Uncultured actinobacterium clone GCP18,Tetrasphaera elongate and Candidatus Competibacter phosphatis clone SBRQ22 were dominant in deteriorate period. Candidatus Competibacter phosphatis clone SBRQ22 was in the largest quantity and responsible for worse operation effort. There was a larger difference between start up and deteriorate period of microbe community structure, but the functional microbes were the same (Tetrasphaera elongate and Gemmatimonas aurantiaca). At the end of the start up period, the amount of Candidatus Competibacter phosphatis clone SBRQ22 was less and caused less restraint to PAOs, while it accounted for the largest amount in deteriorate period.