环境条件对1株假交替单胞菌脱氮效果的影响

Effect of Environmental Conditions on Denitrification of Pseudomonas sp.

关键词:  假交替单胞菌  C/N  盐度  pH  碳源  氨氮  脱氮效率

Key words:  Pseudoalteromonas sp.  C/N  Salinity  pH  Carbon source  NH4+-N  Denitrification efficacy

摘要:

从对虾养殖池中分离得到1株具有高效脱氨氮能力的菌株(2906)，根据菌株2906的16S rRNA序列分析，该菌与假交替单胞菌属Pseudoalteromonas tetraodonis的亲缘关系最近，命名为假交替单胞菌(Pseudoalteromonas sp.)2906。利用不同C/N、pH、盐度的脱氮培养基，分析了环境条件对该菌株脱氮效率的影响，研究了葡萄糖、蔗糖、麦芽糖、丁二酸钠、柠檬酸钠、乳糖和可溶性淀粉等不同碳源对菌株2906脱氮效果的影响。结果显示，菌株2906在C/N为15~20、pH为7~8、盐度为5~15时，具有良好的脱氨氮效果。应用柠檬酸钠为碳源，氨氮去除率达100%。在脱氮培养过程中，细菌生长与脱氮效率呈强相关性(相关系数R=0.94)。采用浸泡攻毒方法测试了该菌对幼虾的生物安全性，结果显示，该菌对幼虾的LC50为2.8107 CFU/ml，表明该菌对对虾不具致病力。研究结果可为该菌的开发利用提供技术支持。

Abstract:

A bacterial strain with high denitrification activity isolated from a shrimp pond was designated strain 2906. The effects on denitrification efficacy of environmental conditions including carbon/nitrogen (C/N) ratio, pH, and salinity were determined using sucrose and ammonia as carbon and nitrogen sources, respectively. The effects of carbon sources (glucose, sucrose, maltose, sodium succinate, sodium citrate, lactose and soluble starch) on the denitrification efficacy of strain 2906 were assessed. The maximal NH4+-N removal rate of strain 2906 was achieved at a C/N ratio1520, an initial pH of 78, and salinity of 515. Sodium citrate was the optimal carbon source, with which the NH4+-N removal rate reached 100%. In the process of denitrification, there was a strong correlation between bacterial density and denitrification efficiency (R=0.94). A sequencing and phylogenetic analysis of the 16S rRNA of strain 2906 showed it was closely related to Pseudoalteromonas spp. The biosafety of strain 2906 was also tested on juvenile shrimp through an immersion challenge, with the result showing that the 50% lethal concentration of strain 2906 for juvenile shrimp was 2.8×107 CFU/ml, which indicates that strain 2096 has no virulence to shrimp. The results provide a theoretical basis for the development and utilization of the bacterium.