The Study On Ecology Of Cyanobacterial Bloom Based On Next-generation DNA Sequencing

Harmful cyanobacterial blooms cause many ecological disasters worldwide.During the development of cyanobacterial blooms,the secondary metabolic production produced by cyanobacteria is confirmed to be toxin and bad odor.Eating these fishes which has concentrated algal toxin,could threat the safe to human being.A set of efficient and comprehensive evaluating method of cyanobacteria is needed.Recently,Because of the development of high-throughput sequencing technology,it is possible now to harvest all genetic information environmental microorganism.However,some side effect is existed when study object became cyanobacteria.The relevant procedure is still not clear,the bioinformatic analysis process is not existed for now.In this study,a fast high-throughput sequencing method is developed for the studies under different scales study of cyanobacteria.Using this set of methods,we performed the following research:1.A total of 5,001 operational taxonomic units were obtained and clustered from filtered 16 S rDNA V3–V4 region sequences by a 97% threshold clustering.The cyanobacterial and microbial structures greatly differed in these two water areas.Microcystis was dominant in Yuqiao,whereas Synechococcus was dominant in Haihe.Proteobacteria species were dominant among all detected samples.The relative abundances of Bacteroidetes and Planctomycetes were higher in Yuqiao Reservoir than in Haihe River,whereas Firmicutes and Verrucomicrobia were relatively abundant in Haihe River.Further analyses indicated that the domination of both cyanobacteria was strongly related to several environmental factors.Applying high-throughput sequencing could offer a wide field of vision in analyzing microbial community structures.2.The Three Gorges reservoir is a strategic fresh water resource in China.In this study,the small river backwater area of the Three Gorges reservoir is used as the research area.Under the high throughput detection process,the cyanobacteria specific fragment CPC is amplified,and the annual dynamic composition of cyanobacteria bloom is studied.It is found that there are obvious seasonal succession rules of cyanobacteria in the Three Gorges small river backwater area.Microcystis,Synechococcus and Planktothrix are in alternate dominance throughout the year.The structure of cyanobacteria was significantly affected by environmental factors.This study verified the reliability of high throughput sequencing technology from the community structure scale of the whole cyanobacteria.3.The method for genotype detection based on traditional molecular cloning is expensive and time consuming and generates a limited number of sequences.In this study,a high-throughput sequencing(HTS)method was developed to detect the internal transcribed spacer(ITS)regions between 16 S to 23 S rRNA region of Microcystis populations along a typical water system in Yuqiao Reservoir–Haihe River in Tianjin,northern China.A total of 629,341 reads were obtained and clustered into 2005 Operational Taxonomic Units(OTUs).Analysis of alpha diversity indices showed that the Haihe River is more diverse than Yuqiao Reservoir.In general,the two water areas exhibit a clear differentiation pattern in OTU abundance,sharing genotypes from a small part of Yuqiao Reservoir with those in the Haihe River.Phylogenetic analysis further indicated the possible flexible evolution of Microcystis genotypes occurring in the research areas.