Phylogenetic Analysis In Five Desert Cyanobacteria And Homology Analysis Of Microcystins Synthase Genes

In this study,five desert algae,from the Taklimakan Desert in Xinjiang,China,were isolated and purified cultured,and the microstructure of the algae cells was observed for morphological classification.The 16 S rDNA sequence analysis and 16S-23 S rDNA interval ITS region sequence phylogenetic analysis were carried out for molecular biology.Classification and identification.Furthermore,the mcy gene of desert cyanobacteria was analyzed to explore the homology between the microcystin gene of desert cyanobacteria and the microcystin gene of freshwater cyanobacteria.This study not only lays a foundation for the genetic diversity of desert cyanobacteria,but also systematically analyzes the microcystin gene of desert cyanobacteria for the first time,and discusses the high conservation of microcystins in different environments,cyanobacteria,and different genera.At the same time,it provides a theoretical basis for the rapid detection of microcystin genes in desert cyanobacteria and the safety of developing and applying desert cyanobacteria.Firstly,the morphological identification of five desert algae was carried out by optical microscopy and scanning electron microscopy.The results showed that the five desert algae samples were filamentous,the algae filaments were not clustered,and the algae were blue-green,and they all had no cap-like structure.Except for the algae species Y4,other algae species have obvious sub-nodes,and only the algae species Y5 has a tip-grading feature.From the morphological characteristics of five strains of algae,five desert algae were identified as Osillatoriales of the Cyanophyceae.Secondly,molecular phylogenetic identification of 5 desert cyanobacteria was carried out by 16 S rDNA gene sequence analysis and 16S-23 S rDNA gene interval ITS region sequence analysis.The 16 S rDNA gene sequence analysis showed that the gene sequence of algal species Y1 and Y2 was highly homologous with Leptolyngbya(AY493590.1)in Gen Bank,and the similarity rates were 95% and 98%,respectively.The gene sequence of algal species Y3 High homology with Oscillatoria sp.(KM019975.1),the similarity rate is 96%;algal species Y4 gene sequence and Planktothrix pseudagardhii(FM177501.1),algal species Y5 gene sequence is similar to Oscillatoria acuminata(KM019978.1)The rate is also 92%.The sequence analysis results of the ITS region were consistent with the results of the 16 S rDNA sequence analysis.Finally,the mcy gene of desert cyanobacteria was detected by PCR.The results showed that the five cyanobacteria were deleted from the mcy A and mcy G gene sequences,but other mcy genes(mcy B-mcy E)were present.The sequence was determined in the same database as the database.The source sequences were aligned.The results showed that the similarity rate of mcy B-mcy E gene sequence of desert cyanobacteria with the homologous sequence of mcy gene of freshwater cyanobacteria in the database was over 99%.The cyanobacteria mcy gene and freshwater cyanobacteria in the phylogenetic tree were drawn.The mcy gene is clustered into a cluster;the bioinformatic analysis of the most important mcy E gene sequence in the synthesis of the toxic site Adda of microcystins is performed.The results showed that the mcy E gene sequence of desert cyanobacteria was highly consistent with the mcy E gene sequence of freshwater cyanobacteria;there were very few irregular mutation sites in the multiple alignment results,but it did not affect the homologous evolutionary relationship between them.