메타게놈 연구를 통한 해양미생물 다양성의 추정과 이용

Abstract

Recent studies on marine environments have led to significant discoveries of unusual microbial diversity, genetic potential and metabolic activity in a variety of marine habitats; cold waters, sinking particles, sediments, and animal guts or other biological surfaces (at temperatures from -1.7℃ in polar oceans to ~4℃ at temperate and tropical latitudes); hydrothermal vent environments that encompass a wide range of temperatures (2-350℃) and nutritional conditions (organic compounds, reduced chemicals, heavy metals); and seafloor habitats in deeply buried sediments (>500m below the seafloor). Among the various microbial habitats, the marine sediment of coastal area and deep sea are considered to be eutrophic habitats rich in nutrients which may contain higher level of microbial diversity. The access of microbial diversity by culture techniques has been limited due to low cultivability less than 1%. An alternative procedure for the obtaining of the collective microbial genome in a given habitat (termed as metagenome) has been extensively studied; i.e. extracting total DNA and cloning it into proper vector systems.We have collected samples from various sediments of deep-sea clam beds community (depth, 1,400 m) in low-temperature venting area located in western Pacific area, intertidal zone of Ganghwa-island, and coasts of Korean Arctic Station, Dasan in Svalbard, Norway. The environmental DNAs of high quality and long size (>30 kb) were cloned into a fosmid vector system. The library contained 220,000 clones with average size of 31 kb, which equivalent to 6,820 Mb in total. The individual clone in the metagenomic library from a special microbial community of clam beds area has been analyzed by end-sequencing and useful enzymatic activity was screened. The end-sequences (~500 bp in length) of 223 clones were obtained and sequence analysis was accomplished. The sequences of 101 clones (45%) have showed similarity to proteins from γ-Proteobacteria (32%), α-Proteoba