Community Diversity of Nitrosobacteria in SBR Denitrified System for Treating the Livestock Wastewater

Short-cut nitrification and denitrification had achieved in this Sequencing Batch Reactor (SBR). At the aerating stage, nitrosobacteria had survived much better than nitrobacteria and the concentration ratio of [NO₂^--N]/[NO₃^--N] was exceed 50% .After one cycle running, the total ammonia was removed completely. We wished to discover if we could gain greater insights into the relationship between the community construction of nitrosobacteria and the accumulation of nitrite nitrogen in this reactor. This examination used the molecular biology technology by amplifying the target fragment of amoA gene from total DNA of activated sludge, by coupling the target gene with pGM-T vector and transforming them into E.coli DH5a competent cells. Randomly, picked some white clones out from the LB solid nutritive medium, and used RFLP markers to obtain the restriction patterns. RFLP analysis showed that there were 8 kinds of restriction patterns among these clones. After comparing homologies with standard strains, the results confirmed that there were 3 genera of nitrosobacteria in this reactor: Nitrosospira sp., Nitrosomomas sp. and Nitrosococcus sp., the distributing frequencies were 0.285, 0.392 and 0.035, respectively. Preliminary analysis, Nitrosolobus multiformis and Nitrosomomas europaea had played the predominant role in accumulating nitrite nitrogen.