Biodiversity Of Diatom From Different Environments Based On DNA Barcoding

Diatom is the primary producer in Marine ecosystem as well as is the main group of Marine phytoplankton.It plays an essential role in the marine ecosystem energy flow and materials circulation.There are many variously forms diatoms,which were composed by several or many individual cells into different groups,it is a class of chromatophore single-celled and light energy autotrophic plant,has a wide distribution.Diatom is not only able to assess environmental quality,but also can refine bio-diesel,has a promising prospect in the fields of biological energy and environmental protection.However,the classification of diatom identification has been in a state of chaos,different researchers have different classification methods,which prevents the development of diatoms identifications.The application of diatom depends on the accurate identification of algae resources.Biodiversity research has always been a concerned question of scientists,accurate identification has been the pursuited goals of taxonomists.Classical identification is mainly based on morphological method,but morphology of species is easily effected by many factors.With the development of molecular biology,DNA barcoding has been proposed as a method that will make species identification faster and more accessible using a small fragment of DNA sequence,particularly in species with complex accessible morphology,and has been successfully used in animals,plants and microorganism.DNA barcode has become an important tool for ecological studies,used for species identification,promoted the development of biological taxonomy.Meanwhile,DNA barcode helps biologists to further understand the relationships of interaction in ecological system.In this study,the algae resources were collected through wild field acquisition,were separated and purified by experimental cultivating,which were further identified using DNA barcode technology and determined its classification status and evolutionary relationships.The main conclusions of this study were obtained as follows:Algae resources were collected from different sample sites,several methods were used such as flat line method,flat membrane filter method,dilution method step by step and micro pipette separation purification,together to separate and purify them,a total of 92 strains of purified micro algae were obtained finally.DNA barcode method was applied to classify identifications of 92 strains purified micro algae.The sequences of rbcL,COI,SSU and LSU four genetic loci of 92 strains purified micro algae,were sequenced and compared with the identified sequences from different species in the NCBI database website and then got the classification information of them.After sequencing,all sequences of 92 strains purified micro algae were uploaded to NCBI database,got the GenBank accession number.Calculating the genetic distance,combining adjacency method,maximum likelihood and bayesian method were used for constructing phylogenetic tree,together with analysis of haploid type and ABDG method.Found rbcL and COI is suitable for marking diatom DNA barcode loci position.rbcL,SSU,LSU bar code gene loci are effective and can be used to identify the diatom species,but the three sequences cannot be used to distinguish close relationships of diatoms.NCBI databases rbcL site resources are full filled,COI resources is least,but has high variously areas of sequences,can distinguish the close relationships of different diatom.Combination of rbcL and COI sequences can be applied to rapid identification of diatoms,which is better method for molecular markers.In this study,92 strains of diatoms were collected in the different ecological environment which were accurately characterized at molecular levels from three levels of families,genera and species classification using DNA barcode Most of the diatoms can be accurately identified,and can further revise the wrong information of diatoms that have been published in NCBI.The discovery of hidden cryptic have a great significance in practical application of diatoms and diversity protection as well as remind us to pay more attention to the hidden cryptic biodiversity ignored in marine life.