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环境科学学报 2012
Identification and Hg2+-adaptation characteristics of an aerobic denitrifying bacterium
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Abstract:
A mercury resistant strain, X1, was screened out from efficient aerobic denitrifying bacteria. It was identified as Pseudomonas putida according to its physiological properties and the analysis of its 16S rRNA gene sequence. Study on its adaptive characteristics to Hg2+ showed that, for the experimental groups containing 2, 4, 6, 7 mg·L-1 of Hg2+, bacteria need to be delayed for 12, 18, 28, 40 h respectively to enter the logarithmic period, with the 8mg·L-1 group unable to enter the logarithmic period. In the process of aerobic denitrification, concentration change rate of NO3--N, accumulated peak of NO2--N and pH characteristic points had same change trend with concentration of Hg2+, while concentration of Hg2+ showed the same downward trend as NO3--N, and could be removed by 100% during logarithmic period. It can thus be concluded that the concentration limit was 7 mg·L-1 and the corresponding adaptive time was 40 h. Within the concentration limit, the growth and aerobic denitrification process would present a "Suppression-adaptation-stimulation" pattern. The pent-up time and stimulated degree would both increase with the increase of Hg2+ concentration, which was mainly reflected by longer adapting period and shorter logarithm period. In addition, during logarithm period, its growth rate, stabilization concentration and aerobic denitrification rate also increased with the increase of Hg2+ concentration and were all larger than blank group.
