The Research On The Diversity And Cultivation Of Anammox From Sediments In North Yellow Sea

Anammox (anaerobic ammonium oxidation) bacteria have a wide distribution in all kinds of ecological environments. Especially in marine ecosystem, anammox process was estimated to account for30%～50%of the oceanic N2production. Anammox bacteria have the abililty of oxidizing ammonium to nitrogen gas with nitrite as electron acceptor under anoxic or anaerobic conditions. It can reduce the ammonia nitrogen content in the sea and maintain the normal operation in the N cycle of marine environment. In order to intense research the diversity of anammox bacterial communities in the sediment of North Yello Sea (NYS), molecular biology techniques were used to study the diversity, phylogeny and abundant of anammox bacteria. The relationship betweent the anmmox bacterial communities and environmental factors was explored by statistical methods. Because marine anammox bacteria had a special characteristic of salt tolerance, it could be used to treat salinity wastewater. Through adding MnO2powder to reactor, it may accelerate the cultivation of marine anammox bacteria.This topic selected three stations (J, D and C) including7sites (J1、J2、D1、D2、C1、 C2and C3) as sampling points in NYS. A total of69anammox bacterial16S rRNA gene clones were achieved based on anammox bacterial16S rRNA gene cloning libraries, and they were subjected to BLAST search in the GenBank database. The BLAST result showed that56(81.7%) clones were closely similar with the anammox bacteria which were originally retrieved from marine sediments or anoxic and anaerobic sea-water. Marine anammox bacterial sequences were detected from every sampling sites and it may suggest that marine anammox bacteria exist in NYS. The amounts of anammox bacteria in sediments of North Yellow Sea were quantified by RT-PCR analysis of16S rRNA genes. The maximum anammox bacterial16S rRNA gene copy number was4.31×106copies-(g sediments)-1in site Dl, while the minimum anammox bacterial gene copy number was1.07×106copies·(g sediments)-1in site C3. The result of the Spearman’s rank correlation coefficients revealed that dissolved inorganic nitrogen (DIN)、NH4+-N and NO2--N concentrations of sediments pore water had a large influence on the numbers of anammox bacterial16S rRNA copies. Redundancy analysis (RDA) results proved that the major factors influencing on the numbers of anammox bacterial16S rRNA copies were different at each station. It illustrated that the distribution of anammox bacteria was affected by many environmental factors. This study showed that the distribution characterisitics of anammox bacteria in NYS and the distribution of anammox bacteria were affected by many environmental factors.According to the result of the diversity anaysis, the reactors inoculated with marine sediment from D1site. This study examined effects of MnO2powder on cultivation of marine anammox bacteria under room temperature. Two lab-scale anammox reactors were operated for nearly150days, one with MnO2powder addition (R1reactor) and the other one (R2reactor) without. The experiments showed that the maximum nitrogen removal rate of R1reactor reached137.82g-N/(m3-d). This value was20g-N/(m3-d) higher than that of R2reactor. During the period when two reactors operated under the low temperature conditions (10～15℃), the nitrite and ammonium removal rate of R1reactor was10%higher than those of R2reactor. The experiment results demonstrated that MnO2promoted cultivation of marine anammox bacteria and improved the temperature adaptability, which enabled the reactor to operate in a wider temperature range. It may provide a new method for treating salinity wastewater.