Study On The Diversity Of The Ulva Prolifera Epiphytic Bacteria In Green Tide And The Effect Of Important Co-bacteria On The Morphological Development

The green tide is a kind of harmful ecological phenomenon that some large green algae(such as Ulva prolifera,U.pertusa)in the sea water are proliferating or highly aggregated in a certain environment,it is regarded as a marine disaster like the red tide.There are more than a dozen species distributed along the coast of China,and the green tide that caused the green tide disaster in the Qingdao sea area in 2008 was U.prolifera.From 2008 to 2017,the East Sea and the Yellow Sea of China have consecutively suffered green tides in the summer for 10 years.Like the red tide,a large number of breeding U.prolifera can shade the sun and affect the growth of submarine algae;the dead alga also consumes oxygen in seawater;the corruption of Ulva alga produce harmful gas,destroying the coastal landscape and ecological system of the intertidal zone.These unfavorable factors have caused people all over the world to try their best to eliminate them.The surface of macroalgae U.prolifera in green tide,attached to a large number of bacteria,which is vital for the green tide——U.prolifera morphogenesis,some strains even on the morphology of U.prolifera is indispensable.The surface of adnascent U.prolifera bacterial community composition is a necessary prerequisite for understanding the relationship between algae and bacteria attached to the surface.This paper used methods of isolation,cultivation and molecular biology technology which had been outbreaking in the last 10 years in the summer of July and August in the East Sea and the Yellow Sea in China about the green tide——U.prolifera surface epiphytic bacteria were studied.The alga U.prolifera is bright green or light green,hollow tubular,membranous,composed of a single layer of cells,alga body length reach to 1-2 m,diameter up to2-3 mm.Isolation of 330 strains were obtained from a strain of U.prolifera sample in the green tide.Through the identification of their distribution,we find they are in four phylums of the 17 generas.The four phylums including Proteobacteria,Firmicutes,Bacteroidetes and Actinobacteria.Proteobacteria,especially the alpha Proteobacteria bacteria which is contain most of the Proteobacteria bacteria is the main bacterial on the surface of U.prolifera in green tide,other categories of bacteria contain few species.In 24 kinds of bacteria isolation and identification,there are ten kinds of bacteria belonging to the Rhodobacteraceae bacteria(belong to the alpha Proteobacteria),accounting for 41.67%.Interestingly,which in ten species of bacteria,four species belonging to the genus of Roseobacter,so Roseobacter bacteria also occupy a large proportion.Using the 16 strains of bacteria isolated from a single to induce callus of 2 kinds of U.prolifera in green tide,found no significant difference about the 2 kinds of callus of U.prolifera bacterial species play a key role on the induction.For example,four strains of bacteria(E68,E69,E104,E110)have great effects on the development of the callus organization form of U.prolifera(S3).There are also four strains of bacteria(E68,E69,E104,E110)have great effects on the development of the callus organization form of U.Prolifera(UP16).We were randomly selected two strains of bacteria(E68,E69)which play an important part on the callus induction of U.prolifera(S3)to explore the impact of different initial concentration gradient of bacteria on the callus ontogeny,the basic speculation of the two strains of bacteria to exert the leading function,strains must reach a certain concentration(10~8-10~9/ml).Below this concentration will lead to the deformity of callus formation and development or have no induced effect on the callus of U.Prolifera(S3).