Study On The Diversity Of Cytophaga-Flavobacteria Cluster In Typical Areas Of The China Seas And The Bering Sea

Heterotrophic bacteria have high abundance and diversity in marine environments. As an important component of microbial food web, they play a vital role in marine biogeochemical cycling of carbon and other biogenic elements. The total abundance and diversity of heterotrophic bacteria have been well studied in the global oceans, as well as their contribution to the carbon cycle in the ocean. However, different heterotrophic bacterial groups exhibited extremely highly versatile metabolic diversity in the marine environments, and differed in the ability of carbon utilization. Current models about carbon cycling in the marine environments didn't evaluate the contributions of different bacterial groups separately. Under this background, this thesis firstly studied the diversity of an strictly chemoheterotrophic bacterial group - Cytophaga-Flavobacteria (CF) cluster, which plays an important role in marine carbon cycling, in typical China Seas and subarctic zone (Bering Sea) using culture independent molecular biological methods.Since current researches on diversity of marine CF cluster were largely limited by specific primers, we designed a new CF-specific primer pair, CF315-F and CF967-R, based on existing 16S rRNA gene sequences of CF cluster in RDP database. The whole design process included the multiple alignment of reference sequences, the analysis of conservative sites and a new approach to theoretically evaluating the amplification potential and robustness of the new primer pair. The results showed that this new primer pair could theoretically match 67 of all exsiting 69 genera in the RDP database. Compared with published CF primers or probes, this new primer pair remarkably increased the match ability to the two major CF families. The matches to family Flavobacteria increased from 3.8% to 95.6% with respect to total sequences in the database, and those to family Sphingobacteria increased from 44.1% to 89.6%. Meanwhile, analysis results on natural water samples also indicated this new primer pair's high reliability and specificity to marine CF cluster.Here we further used this newly designed primer pair to construct six CF clone libraries to investigate CF diversity and the composition of the major subgroups. The...