북극 척치해 심층수의 원생미생물 다양성

Abstract

The microbial diversity of deep-seawater from Chuchi Sea in Arctic Ocean was analyzed by using pyrosequencing method. Marine samples were collected from the first expedition of ice breaker ARAON from a cold deep-sea (depth: 2,400 m; temp.: - 0.375℃) in August 2010. The total 8,774 bacterial reads and 3,335 Archaeal reads were obtained from the pyrosequencing analysis, and all sequences were assigned in 97% similarity level. Among the bacteria, Proteobacteria was the most dominant phylum (89.8%), and followed by Bacteroidetes (7.9%). The most frequent bacterial sequence was assigned as Pelagibacter ubique (30.1%) belonged to the order SAR11of the class Alpha-proteobacteria. The SAR 11, of which Pelagibacter ubique is a representative, are found throughout the world's oceans and dominant aerobic heterotrophs in marine surface waters. Pelagibacter ubique plays a key role in the oxidation of the oceanic dissolved organic carbon pool. In Archaea, Thaumarchaeota was the most dominant phylum (92.2%), and followed by Euryarchaeota (6.9%). In the case of Archaea, almost sequences of the Thaumarchaeota were assigned as an order of Cenarchaeales (91.3%), which consists of genera AY316120 (79.3%) and Nitrosopumilus (11.6%). The major sequences of AY316120 were described as "uncultured crenarchaeote DeepAnt EC39". The DeepAnt EC39 appears to represent a lineage specific to deep-sea waters. These sequences are closely related to other mesophilic or psychrophilic crenarchaeotes. The aim of this study is to understand the prokaryotic microbial diversity in Arctic ocean, and the marine microbial diversity can be readily monitored by pyrosequencing of 16S rRNA gene.