Microbial Diversity in Sediments Collected from the Deepest Cold-Seep Area, the Japan Trench |
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Authors: | Lina Li Chiaki Kato Koki Horikoshi |
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Institution: | (1) The DEEPSTAR Group, Japan Marine Science and Technology Center, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan, JP |
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Abstract: | The Japan Trench land slope at a depth of 6,400 m is the deepest cold-seep environment with Calyptogena communities. Sediment samples from inside and beside the Calyptogena communities were collected, and the microbial diversity in the sediment samples was studied by molecular phylogenetic techniques.
From DNA extracted directly from the sediment samples, 16S rDNAs were amplified by the polymerase chain reaction method. The
sequences of the amplified 16S rDNAs selected by restriction fragment length polymorphism analysis were determined and compared
with sequences in DNA databases. The results showed that 33 different bacterial 16S rDNA sequences from the two samples analyzed
fell into similar phylogenetic categories, the α-, γ-, δ-, and ɛ-subdivisions of Proteobacteria, Cytophaga, and gram-positive
bacteria; some of the 16S rDNA sequences were common to both samples. δ- and ɛ-Proteobacteria-related sequences were abundant
in both sediments. These sequences are mostly related to sulfate-reducing or sulfur-reducing bacteria and epibionts, respectively.
Eight different archaeal 16S rDNA sequences were cloned from the sediments. The majority of the archaeal 16S rDNA sequences
clustered in Crenarchaeota and showed high similarities to marine group I archaeal rDNA. A Methanococcoides burtonii–related sequence obtained from the sediment clustered in the Euryarchaeota indicating that M. burtonii–related strains in the area of Calyptogena communities may contribute to production of methane in this environment. From these results, we propose a possible model
of sulfur circulation within the microbial community and that of Calyptogena clams in the cold-seep environment.
Received June 15, 1998; accepted November 10, 1998. |
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Keywords: | : Cold-seep environment microbial diversity Calyptogena Japan Trench sulfur-reducing bacteria sediment |
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