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

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.