G20 Gene Diversity Of Cyanophage Community In The Yellow Sea Coastal Area Around Qingdao

Cyanophages are viruses that infect Synechococcus, Prochlorococcus and other unicellular cyanobacteria. Cyanophages, as an important part of the aquatic microbial community, play a key role in maintaining the stability of marine ecosystems, regulating the biological production and cycling of carbon and other nutrients in the sea, influencing the dynamics of cyanobacteria populations and so on. In addition, studies show that using cyanophages to prevent and control algal bloom displays considerable development prospects. Studies on cyanophage diversity in different locations and environment will help in our understanding of the rules of cyanophage distribution and their ecological status. And the knowledge of cyanophage diversity will help make a solid foundation for discussing the impact of human activities and environmental pollution on biological diversity and provide reference data and theoretical foundation for environmental assessment.Cyanophages that distribute widely in aquatic systems are considered as a diverse community. Up to date, most studies based on g20 gene focused on cyanophage diversity in the Southern Ocean, the Eastern Pacific, the Arctic and the North Atlantic, but no information about cyanophage diversity of the Western Pacific has been reported. While in China, researches about cyanophage diversity were focused on cyanophage isolations, whole genome sequencing and so on in the freshwater, no information about the genetic diversity of marine cyanophages has been reported. This article firstly revealed cyanophage structure and their affiliations in the Yellow Sea Coastal Area around Qingdao which belongs to the Western Pacific.The Yellow Sea Coastal Area around Qingdao(35-36.8°N,119-121.6°E), a part of the margin coastal area of the Western Pacific, is characteristic of the shelfsea and it is an important ocean research region of China. In this study, we examined marine cyanophage diversity in the Yellow Sea Coastal Area around Qingdao by RFLP analysis. We picked 600 positive clones randomly and found 16 distinct cyanophage g20 genotypes and its diversity lies among other marine areas, which shows that cyanophage community in this coastal area was genetically diverse. Phylogenetic analyses placed the 16 distinct g20 genotypes into two main clusters. One was previously designated as Cluster III, this cluster was determined to possibly represent lytic phages that infect WH7803 and WH7803-like Synechococcus, and cyanophages in this cluster were seen to adapt to widely differing marine environments.6 sequences of this cluster shared more than 97% nucleotide sequence similarity with P77. The other cluster was novel, it was firstly discovered in Qingdao Coastal Area and we named it Cluster W. The identities of the members in Cluster W were enigmatic due to their lack of grouping with other g20 sequences obtained from previous studies and their evolutionary distance were far away with other known clusters. Further studies are needed to determine the classification of their exact positions, and it will be a subject worthy of deep and inclusive research.