Potential of simultaneous nitrogen and phosphorus removal by Pseudomonas stutzeri CM-11HN isolated from shrimp pond
Abstract
This study aims to isolate and select indigenous Pseudomonas strains that are capable of simultaneously removing nitrogen (N) and phosphorus (P) from extensive and improved extensive shrimp ponds. A total of 16 isolates were capable of reducing nitrate, but only 4 strains performed the NO3-‑N removal efficiency of above 80% in ADM-1 medium, of which strain CM-11HN possessed the highest efficiency. The 16S rRNA gene sequence analysis showed that strain CM-11HN shared a homology of up to 99.9% with Pseudomonas stutzeri. In aerobic denitrifying, over 90% of N concentrations were removed while NO3-‑N or NO2-‑N as the sole nitrogen, and the corresponding P removal efficiencies were 72.9% and 51.3%. When NH4+-N as the sole source, the maximum N and P removal efficiencies observed for this candidate were about 96.5% and 78%, respectively. Among nitrogen sources, NH4+‑N was preferentially utilized during the cell growth phase compared to NO3-‑N and NO2-‑N. Moreover, strain CM5.2N did not exhibit hemolytic activity and none of the dead shrimp Litopenaeus vannamei were found in the safety assays. Hence, Pseudomonas stutzeri strain CM-11HN has great potential in bioremediation for wastewater treatment and improving water quality in aquaculture systems.
