Metatranscriptomics Insights Into The Analysis Of Cyanob Acterial Aggregates During Cyanobacterial Bloom Period In Lake Taihu,China

Cyanobacterial bloom in eutrophic water is the main factor of water pollution,which caused water crisis and seriously affecting urban production and residents' living.In recent years,the intensification of eutrophication leads to biodiversity loss and ecosystem service decrease in Lake Taihu.The control methods about cyanobacterial bloom of Lake Taihu have attracted people's widespread attention.However,the mechanism of cyanobacterial bloom was not clear and the effective methods of eutrophication control need studied deeply.The metatranscriptome was used to insight into the analysis of cyanobacterial bloom in Lake Taihu,which would have an important reference to research and management of cyanobacterial bloom.In this study,cyanobacteria aggregates that were formed on the surface of the lake during bloom period as the objective.By studying the four different periods of cyanobacterial aggregates samples in Lake Taihu with metatranscriptome,the complete set of bioinformatics.analysis program of metatranscriptome and the taxonomic classification of the active components in this microenvironment was acquired.Meanwhile,the functional classification and whole metabolism pathway analysis of the cyanobacterial aggregates community was also studied in this study.Besides,the differentially expressed genes of four samples were analyzed.The main content of the article include the following aspects:1.Total RNA extraction quality control.The total RNA was extracted by cyanobacterial aggregates samples with TRIzol Reagent.The quantity and quality of extracted total RNA were checked strictly.Integrity and purity of total RNA were the key to the quality of library construction and sequencing.2.Library construction.The most rRNA was removed before libraries construction to obtain the purpose of high-quality sequences.The quantified and qualitied libraries which conformed with Illumina sequencing platform were sequenced to get valid information.3.Bioinformatic analyses of cyanobacterial aggregates community.The taxonomy of active organisms was analyzed,which provided insight into the cyanobacterial aggregates community of Lake Taihu.acteria were the dominant domain in this microenvironment of cyanobacterial aggregates,accounting for more than 96.66%of total sequences,and Microcystis aeruginosa was the most active specie.The functional classification and whole metabolism pathway analysis of the cyanobacterial aggregates community were also studied in this study.What's more,the different gene encoding enzymes and active species relating to nitrogen metabolism and phosphonate and phosphinate metabolism pathways which associated with eutrophication was obtained,which played a key role in eutrophication and cyanobacterial bloom.4.The analysis of differentially expressed genes in four periods.Comparative analysis of the four cyanobacterial aggregates samples was studied,and the differential expression genes were analyzed by metabolic pathway enrichment.The genes which participated in the process of denitrification in nitrogen metabolism during the death period of cyanobacteria were highly expressed by analyzed the differentially expressed genes involved in the nitrogen metabolism pathway.It has played a very important role in reducing the nitrogen concentration in freshwater environments.5.Conclusion.The enzymes(genes)and the organisms were discovered in the process of denitrification during cyanobacteria bloom period.And these genes in the death period of cyanobacteria were highly expressed,which will provide a breakthrough in the control of cyanobacteria bloom.