Abstract:
The isolation and selection of chemoautotrophic ammonia oxidizing bacteria and chemoautotrophic nitrite oxidizing bacteria were carried out from cultivated shrimp pond in different areas. Chemoautotrophic ammonia oxidizing bacteria strains A3, A4 and A7 were isolated. Bacterial strain A7 gave highest activity in capable to oxidize nitrite from ammonia. Chemoautotrophic ammonia oxidizing strain A7 is gram negative rod shape with 1.0 x 5.0 mum in size. In optimum condition for highest nitrite production of chemoautotrophic ammonia oxidizing strain A7 grown in liquid ammonium oxidizing medium, which contained 4 mM of ammonium sulfate and 10 g/l of sodium chloride at pH 7-8 incubated at 30-32 ํC with rotary agitation speed 300 rpm., chemoautotrophic nitrite oxidizing bacteria strains N1 and N2 were isolated. Chemoautotrophic nitrite oxidizing bacteria strain N1 produced nitrite higher than bacterial strain N2. Chemoautotrophic nitrite oxidizing bacteria strain N1 is gram negative, pear with size of (0.5-1.0) x (0.2-0.5) mum. The optimum conditions for highest nitrite production by chemoautotrophic nitrite oxidizing bacterial strain N1 grown in liquid nitrite oxidizing medium, contained 20 mM sodium nitrite and 10 g/l sodium chloride at pH 7 incubated at 30 C with rotary agitation speed 100 rpm. Comparing rate of ammonia removal and nitrite production in brackish water in recirculation system for 30 days by chemoautotrophic ammonia oxidizing bacteria strain A7 showed higher rate than control about 2 times and 3.5 times respectively. Comparing rate of nitrite removal and nitrate production in brackish water in recirculation system for 30 days by chemoautotrophic nitrite oxidizing bacteria strain N1 showed higher rate than control about 2 times and 8 times respectively. Comparing ammonia removal and nitrate production in brackish water in recirculation system for 60 days by mixed immobilized cell of chemoautotrophic ammonia oxidizing bacteria strain A7 and chemoautotrophic nitrite oxiding bacteria strain N1 showed higher activity than control about 3.5 times and 23 times respectively. There was no different in nitrite content between treatment and control.