Physiological And Biochemical And Phylogenetic Studies Of Different Strains Of Dunaliella

Dunaliella is a single-cell halophilic microalgae distributed in the ocean,salt lakes,salt water and wetlands.It is one of the reported salt-tolerant eukaryotes.Dunaliella salina is an industrial model of microalgae that is commercially available for the production of bioactive substances such as beta-carotenol,glycerol,sugars,and phytosterols.The structure of Dunaliella is simple,and the cell morphology and physiological and biochemical indexes vary greatly in different environments.In this study,the morphological,physiological and biochemical indexes of 20 strains of Dunaliella were determined.On the basis of this,morphological and molecular biology techniques were used to identify Dunaliella.This study combines cell biology,biochemistry and molecular biology techniques to study the Dunaliella resources of 20 different strains.The results are as follows:1.Morphological observation and physiological and biochemical indicators of Dunaliella showed that: Dunaliella is single-celled,with 1 to 2terminal flagella,pigmented cups,a large protein nucleus near the base,a few eye points,no Cellulose cell wall,in the shape of pear,ellipse,long neck,and the like.The D13 algae strain was the largest,D4 and D14 were the smallest,and there was no significant correlation between the Dunaliella algae and its biochemical indicators.D6 has the strongest growth ability and can be used for large-scale production of Dunaliella.D18 has the strongest salt tolerance and can be used for further excavation of algae salt-tolerant genes.D1 and D11 have the strongest accumulation of ?-carotene and can be used in industrial production.?-carotene;D18 has the strongest oil accumulation ability and can be used for in-depth study of biodiesel;D8 has the strongest activity of 3-phosphoglycerate phosphatase and can be used for the study of the enzyme mechanism of Dunaliella cells.2.The molecular phylogenetic results of Dunaliella showed: thereplacement rate between guanine(G)and adenine(A),thymine(T)and cytosine(C)in the maximum likelihood estimation of the replacement matrix.Both are high.From the genomic level of Dunaliella,the GA and CT substitutions are significant in the genetic evolution of Dunaliella.The genetic distance value of Dunaliella showed that the genetic distance between each algae strain was close.The phylogenetic results of ITS and COX2-3 sequences show that the Dunaliella species can be divided into two branches,and the phylogenetic trees constructed by the two genes have higher similarity.In the first branch,D1,D2,D3,D4,D9,and D10 are grouped together(ITS support rate: 100/0.51/100;COX2-3 support rate:99/-/77),in the first Among the two branches,D11,D15,and D18 are grouped together(ITS support rate: 100/1/100;COX2-3 support rate:89/1/65).As a kind of high value-added industrial microalgae,the excavation and utilization of Dunaliella algae resources is very necessary.The research results of this paper not only have important enlightenment for the in-depth study of the morphological,physiological and genetic characteristics of different Dunaliella algae resources,but also lay a foundation for the excavation and utilization of salt-tolerant algae resources.