Characterization of nitrous oxide reduction by sp. HJ23 isolated from advanced wastewater treatment sludge.

A new nitrous oxide (NO)-reducing bacterium was isolated from a consortium that was enriched using advanced wastewater treatment sludge as an inoculum and NO as the sole nitrogen source. The isolated facultative anaerobe was identified as sp. HJ23. sp. HJ23 exhibited optimum NO-reducing activity with a C/N ratio of 62 at pH 6 in the temperature range of 37 °C to 40 °C. The optimum carbon source for NO reduction was a mixture of glucose and acetate. The maximum rate of NO reduction by sp. HJ23 was 4.8 mmol·g-dry cell·h, and its NO-reducing activity was higher than other known NO reducers. sp. HJ23 possessed several functional genes for denitrification. These included (NO reductase), (NO reductase), (NO reductase), and (NO reductase) genes. These results suggest that sp. HJ23 can be applied in the denitrification process to minimalize NO emission.