A strain of Pseudomonas sp. isolated from piggery wastewater treatment systems with heterotrophic nitrification capability in Taiwan

A high concentration of NH ₄ ⁺ in piggery wastewater is major problem in Taiwan. Therefore, in our study, we isolated native heterotrophic nitrifiers for piggery wastewater treatment. Heterotrophic nitrifier AS-1 was isolated and characterized from the activated sludge of a piggery wastewater system. Sets of triplicate crimp-sealed serum bottles were used to demonstrate the heterotrophic nitrifying capability of strain AS-1 in an incubator at 30°C. All serum bottles contained 80 mL medium, and the remainder of the bottle headspace was filled with pure oxygen. The experimental results showed that 2.5 ± 0.2 mmol L^-1 NH ₄ ⁺ was removed by 58 hours, and, eventually, 1.5 ± 0.5 mmol L^-1 N₂ and 0.2 ± 0.0 mmol L^-1 N ₂O were produced. The removal rate of NH ₄ ⁺ by the strain AS-1 was 1.75 mmol NH ₄ ⁺ g cell^-1 h^-1. This strain was then identified as Pseudomonas alcaligenes (97% identity) by sequencing its 16S rDNA and comparing it with other microorganisms. Thus, strain AS-1 displays high promise for future application for in situ NH ₄ ⁺ removal from piggery wastewater.