分离于河口区芦苇湿地1株好氧反硝化菌的鉴定及其反硝化特性

Identification and denitrification characteristics of an aerobic denitrifier in estuary phragmites wetland

摘要:

[目的] 筛选高效脱氮且N₂O释放量少的好氧反硝化细菌，并对菌株的反硝化特性进行研究，可为河口湿地富营养化水体的生物修复提供技术支撑。[方法] 经BTB培养基初筛和反硝化能力测定，从辽河河口区芦苇湿地土壤中分离得到1株具有较高反硝化能力的好氧反硝化菌C3。经形态观察、生理生化鉴定和16S rRNA序列分析，对菌株进行鉴定。研究温度、碳源、pH及C/N对其生长量、反硝化能力及N₂O释放的影响。[结果] 筛选得到的高效好氧反硝化细菌C3，经鉴定属于假单胞菌属（Pseudomonassp.）。反硝化特性研究结果表明，该菌最适碳源为柠檬酸三钠，在温度为30℃、pH为7.0、C/N为10时生长速率和脱氮效率最高且N₂O释放量较少。在此条件下，该菌在36 h内使NO₃^-由179.55 mg/L降至5.08 mg/L，脱氮率高达97.17%。该菌株在整个反硝化过程中中间产物N₂O的最大累积量较低，为0.22 mg/L。[结论] 从湿地土壤中分离所得好氧反硝化菌C3为假单胞菌属的1个种（Pseudomonas sp.），该菌株在高效除氮和低N₂O累积方面均具有明显优势，对后续河口湿地富营养化水体治理具有重要意义。

Abstract:

[Objective] We isolated an aerobic denitrifier with affinity for nitrogen removing and low accumulation of nitrous oxide, and analyzed its denitrification activity to provide technical support for controlling eutrophic wetland lakes.[Methods] An aerobic denitrifier named C3 was isolated from phragmites wetland soil in Liaohe estuary by BTB medium preliminary screening and denitrification activity analysis. We used morphological and physiological characteristics as well as sequence analysis of the 16S rRNA to identify the strain. Effects of culture conditions, such as temperature, carbon source, initial pH, C/N ratio were evaluated regarding removal of nitrite nitrogen and accumulation of nitrous oxide under aerobic condition.[Results] The highly effective strain C3 was identified as Pseudomonas sp., for which the best carbon source was sodium citrate, optimal growth and denitrification occurred at 30℃, pH 7.0, and a C/N ratio of 10. Under these conditions, the concentration of nitrate was reduced from 179.55 mg/L to 5.08 mg/L by strain C3 in 36 hours, a reduction in NO₃^- of more than 97.17%. In the process of denitrification, nitrous oxide as an intermediate accumulated at a level of 0.22 mg/L.[Conclusion] Strain C3, an aerobic denitrifying agent, was isolated from wetland soil and has obvious advantages in efficient removal of nutrients with low accumulation of nitrous oxide, representing a great potential to treat eutrophic wetland lakes.