Preliminary cultivation and characteristics of the ammonium oxidation of anammox bacteria in freshwater sediments
淡水水体底泥厌氧氨氧化菌的初步富集培养与氨氧化特性

Anammox bacteria were detected in the sediment samples from Xinyi River in Jiangsu Province using 16S rRNA gene approach in previous studies. In this paper the samples were cultivated continuously in anaerobic biological reactors to study the growth rate of the bacteria and the characteristics of anaerobic ammonium oxidation. The bacteria were cultivated for 49 days. After an adaptation period of 25 days, the concentration of both ammonium and nitrite in the reactors started to decrease simultaneously according to the anammox stoichiometry. Afterwards the nitrogen conversion rate showed an increasing trend, and its maximal value was up to 0.17kg·m-3·d-1. After cultivation, the original anammox bacteria in the sediment samples were enriched and the percentage of the bacteria in the total bacteria was increased from lower than 1% to 5.6%, indicating that the doubling time of the amount of the bacteria is about 12 days. In addition, it was found that the biomass of the samples was lost from reactors during cultivation since the bacterial cells in the effluent were hybridized with the anammox-specific gene probes. Further study of the biological characteristics of the bacteria is needed.