Search

A strain of photosynthetic bacterium named psb1 capable of ammonia-nitrogen degradation was isolated from a swamp in Yunnan. The psb1 was similar to Rhodopseudomonas sp. according to its cell morphological properties and absorption spectrum analysis of living cells. The alignment result of 16S rDNA amplification sequence with specific primers of photosynthetic bacteria showed that the homology between strain psb1 and Rhodopseudomonas sp. was 99%, and the alignment results of protein sequences of bacterial chlorophyll Y subunit showed that the strain psb1 and Rhodopseudomonas palustris were the most similar, with a similarity of 99%. But there was a great difference in the biological properties of the strains psb1 and Rhodopseudomonas palustris according to physiological biochemical characteristics and main fatty acid analysis. For example, strain psb1 could not utilize glucose and mannitol as carbon source, and had specific fatty acid C 18:1ω6c . The results of single factor test showed that:the optimal growth was obtained at pH 7.0 and 40℃, the optimal nitrogen source was yeast extract. The optimal conditions for ammonia nitrogen biodegradation were as following:anaerobic, light, initial pH 6.0-7.0, temperature 30℃, inoculation volume 0.4%. Under that cultural condition, the degradation rate of ammonia nitrogen in wastewater could reach 99%. The results indicated that strain psb1 might be a novel bacterium in genus Rhodopseudomonas with high ammonia removal efficiency, and can be applied in the bioremediation of polluted landscape water.

High concentrations of ammonium, nitrate and nitrite nitrogen were employed to clarify the abilities of heterotrophic nitrification and aerobic denitrification of Arthrobacter arilaitensis strain Y-10. Meanwhile, by means of inoculating the strain suspension into the mixed ammonium and nitrate, ammonium and nitrite nitrogen simulated wastewater, we studied the simultaneous nitrification and denitrification ability of Arthrobacter arilaitensis strain Y-10. In addition, cell optical density was assayed in each nitrogen removal process to analyze the relationship of cell growth and nitrogen removal efficiency. The results showed that the hypothermia denitrification strain Arthrobacter arilaitensis Y-10 exhibited high nitrogen removal efficiency during heterotrophic nitrification and aerobic denitrification. The ammonium, nitrate and nitrite removal rates were 65.0%, 100% and 61.2% respectively when strain Y-10 was cultivated for 4 d at 15°C with initial ammonium, nitrate and nitrite nitrogen concentrations of 208.43 mg · L⁻¹, 201.16 mg · L⁻¹ and 194.33 mg · L⁻¹ and initial pH of 7.2. Nitrite nitrogen could only be accumulated in the medium containing nitrate nitrogen during heterotrophic nitrification and aerobic denitrification process. Additionally, the ammonium nitrogen was mainly removed in the inorganic nitrogen mixed synthetic wastewater. In short, Arthrobacter arilaitensis Y-10 could conduct nitrification and denitrification effectively under aerobic condition and the ammonium nitrogen removal rate was more than 80.0% in the inorganic nitrogen mixed synthetic wastewater.