Isolation and performance evaluation of a heterotrophic nitrobacterium Micrococcus sp

By using nitrosobacterial selective medium, a heterotrophic nitrobacterium strain HB-1 with nitrification-denitrification capability was isolated from wetland surface sediment. The conventional staining analysis and the phylogenetic analysis based on 16S rDNA showed that the strain HB-1 had 99% similarity to Micrococcus sp. 16S rDNA, and was preliminarily identified as Micrococcus sp. Taking sodium acetate as the carbon source and ammonium chloride as the nitrogen source, an 8-day aerobic incubation test showed that the NH4-N removal rate by the strain was 49.2%, and trace of NO2-N was detected. Taking sodium nitrate as the sole N source, the strain could not remove N under aerobic incubation, but could remove 90.7% of N after 6-day anoxic incubation, reflecting its important role in denitrification.