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 C18:1ω6c. 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.
Keywords: Rhodopseudomonas sp.; ammonia nitrogen; characteristics; identification; separation.