Experimental study on screening and some characterization of an ammonia nitrogen transformation strain used for water pollution control
可用于水体污染控制的氨氮转化菌筛选及部分降解特性的实验研究

A sludge sample was obtained from a pond in freshwater fish aquaculture base of Lukou, Nanjing. The sample was later analyzed for isolating strains capable of degrading ammonia nitrogen. Seven strains were isolated by selective enrichment culture, and were separated by using ammonium sulfate as nitrogen source.The ammonia nitrogen conversion rates of seven strains were 14.8% , 19.7% , 53.4% , 94. 2% , 29. 1% ,63.5% and 41.7% , respectively. Conversion rate of strain AN-4 was highest up to 94.2%. Strain AN-4 was identified as Klebsiella sp. by means of 16S rRNA gene sequence analysis and morphological and physical-biochemical methods. The ammonia nitrogen degradation characteristics of strain AN-4 and effect factors on ammonia nitrogen degradation rate, such as temperature, pH, initial concentration of ammonia nitrogen and the inoculum size, were studied. The results showed that the optimum degradation conditions for AN-4 were 30℃ and pH 8.0,respectively. It could grow in a media with ammonia nitrogen up to 200 mg/L. Strain AN-4 could degrade ammonia nitrogen of 30 mg/L up to 85% in 24 hours. Concentration of activated strain AN-4 was 10~8 cfu/mL. It could degrade ammonia nitrogen up to 87.75% in 24 hours with 3% inoculum size. In conclusion, the research showed that the strain AN-4 could be used in freshwater aquaculture. In addition, this research provided a theoretical basis of the strain AN-4, which was used in aquaculture environmental remediation by identification of the strain AN-4 and exploration of degradation rule of ammonia.