Analysis Of The Bacterial Diversity And Screening Of An Efficiently Heterotrophic Nitrifier From Xixi Wetland In Hang Zhou

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. Overall,74905 optimized reads obtained from six sediment samples. Bacterial diversity was very high in these samples, since a total of 4274 OTUs were identified which could be assigned into 30 different phyla and 252 different genus.The dominant group belonged to Proteobacteria, accounting for 31.55%-62.67% of total sequences. Among Proteobacteria, the beta-, delta-and gamma-subdivisions were dominant classes, which related to N and S metabolism.The ordination analysis showed that there were 3.25%-5.61% sequences belonged to the unclassified group, which meant that there may be some undiscovered species in sediments. By comparing the six sediment samples, we found that the similarity of No. land 4, No.2 and 3, No.5and 6 is higher, and they clustered into the same branch in phylogenetic tree.A total of 191 bacteria strains were isolated from sediment samples collected from Xixi wetland by culture-dependent method based on four different medium. The phylogenetic analyses data of 16S rRNA gene sequencing suggested that the 191 strains belong to the 13 genera.The dominant group belonged to Rhizobium, accounting for 39.27% of total sequences. Bacterial species isolated from R2A medium was the most, accounting for 11 different species, followed by NB medium, accounting for 8 species, M1 and DNB medium were 7 species.By preliminary screening, we found five strains had a better nitrogen removal efficiency of which M307 strain had a highest removal rate of 78.5%. After study the heterotrophic nitrification characteristics of M307 strain, the results showed that it can reduce all the ammonia nitrogen within 36h when the ammonia nitrogen concentration was 180mg/L in medium without the accumulation of nitrate nitrogen.The M307 strain was identified based on morphological characteristics, physiological tests and 16S rRNA gene sequencing The results showed that M307 strain was closely related to the member of Pseudomonas.