|
|
Screening and characteristics of an efficient nitrobacterium |
|
|
Abstract A nitrobacterium N4 was isolated from SBR activated sludge using selective media. Its nitrification rate reached (52.0±3.5)mg/(L·d) measured by analyzing the residual NO2- content in culture medium using both colorimetry and ion chromatography method. The N4 strain was identified to belong to the genus of Azoarcus based on its morphological, physiological, and biochemical characteristics, as well as 16S rDNA phylogenetic analysis. After acclimated under 15℃, the stain got the ability to transform NO2- to NO3- completely in 8 days at 15℃ when the inoculation amount was 10%, with a nitrification rate of more than 120.7mg/(L·d). Investigations about nitrification characteristics of the acclimated strain N4-L showed that it had the highest nitrification ability under the conditions of pH 8.0, 2g/L of glucose, and 1g/L of NaNO2. DGGE analysis of N4-L and activated sludge in winter was performed by extracting their total DNA followed by amplifying the V3 variable region of 16S rDNA respectively. The result showed that N4-L was not the dominant bacterium in the activated sludge, which suggested that making N4-L the dominant species in SBR system by some strategies may provide an effective way to improve the nitrogen removal efficiency of SBR system in winter.
|
Received: 07 April 2012
|
|
|
|
|
|
|