| The Illumina MiSeq sequencing-based analysis of the V3-V4 16S rRNA gene region was used to detect bacterial diversity and community structure in Xixi wetland,Hangzhou.Bacterial diversity was very high in five soil samples obtained from Xixi wetland,since a total of 28 different phyla and 346 different genus were assigned.The dominant group belonged to Proteobacteria,accounting for 23.16%-39.19%of total sequences.Among Proteobacteria,the alpha-,beta-,and delta-subdivisions were dominant classes,which related to N and S metabolism.By comparing the five soil samples,we found that the similarity of NT and TJ is higher,and they clustered into the same branch in phylogenetic tree.A high efficiency heterotrophic nitrifying bacteria TT1 was isolated from the soil of Xixi Wetland by enrichment culture and plate separation.The isolate was identified as Pseudomonas sp.through morphological feature,biochemical characteristics and 16SrRNA sequence analysis.The factors including carbon source,C/N and cultivation temperature were important for the removal of nitrogen.The optimum condition for heterotrophic nitrification was as follows:sodium acetate as the carbon source,C/N ratio of 11,shaking speed of 140r/min,pH of 7-9,culture temperature of 35 ℃.After 24h-cultivation under the optimum condition,the removal rate of ammonia nitrogen reached 100%.By enrichment culture and BTB plate separation,an aerobic denitrifying bacterium CD1 was screened.The microscope observation demonstrated that the CD1 was a gram-negative bacillus.Phylogenetic analysis showed that the strain was closely related to the member of Pseudomonas plecoglossicida,with which they shared 92.9%similarity.The characteristic of nitrogen removal of strain CD1 was investigated.The results showed that the CD1 could get into the stable period of growth around 22h;its denitrificationrate reached 100%with three citric acid sodiumas carbon source,C/N of 15,temperature of 35℃,pH of 7-8,rotation speed of 160r/min,after 24h-cultivation. |
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