Identification of a moderately halophilic nitrifying bacterium and its applications in highsalinity sewage

Nitrogen removal characteristics and halotoleraney of strain gs2 were studied.The present paper is inclined to introduce our work on identifying a moderately halophilic nitrifying bacterium and its experimental application to high-salinity sewage treating process.As is known, a moderately halophilic nitrifying bacteria, short for gs2, can be screened from the activated sludge which can be used for treating high-salinity sewage.We have succeeded in isolating and identifying a strain of gs2, known as Halomonas sp, through our morphological observation, physiological-biochemical testing and the sequence analysis of 16S rDNA.In contrast to the most previously described heterotrophic nitrifying bacterium, the strain can grow under higher salinity (NaCl mass fraction of 0%-20%).It is also tolerant to a wide range of pH value (6-11) and temperature (25-35 ℃) , with its optimal condition for growth being at 30 ℃ and pH = 8.In proceeding with our research, we have also investigated the nitrification characteristics of the bacterium.We have also found that through a 24 h aerobic culture, it is possible lo make the removal rates of NH_4~+-N and COD by strain gs2 go up lo 81 % and 74.24% respectively. In addition, if nitrosifying culture medium and denitrifying culture medium were used, it is possible to make the removing rates of the NO_2~--N and NO_3~--N go over 90% after a 24 h aerobic culture with the help of strain gs2.Thus, it can be seen that this strain proves to be able lo perform the whole process of biological nitrogen removal independently.