title: Phylogenetic and enzymatic diversity of deep subseafloor aerobic microorganisms in organics- and methane-rich sediments off Shimokita Peninsula.
abstract: "A meta-enzyme approach" is proposed as an ecological enzymatic method to explore the potential functions of microbial communities in extreme environments such as the deep marine subsurface. We evaluated a variety of extra-cellular enzyme activities of sediment slurries and isolates from a deep subseafloor sediment core. Using the new deep-sea drilling vessel "Chikyu", we obtained 365 m of core sediments that contained approximately 2% organic matter and considerable amounts of methane from offshore the Shimokita Peninsula in Japan at a water depth of 1,180 m. In the extra-sediment fraction of the slurry samples, phosphatase, esterase, and catalase activities were detected consistently throughout the core sediments down to the deepest slurry sample from 342.5 m below seafloor (mbsf). Detectable enzyme activities predicted the existence of a sizable population of viable aerobic microorganisms even in deep subseafloor habitats. The subsequent quantitative cultivation using solid media represented remarkably high numbers of aerobic, heterotrophic microbial populations (e.g., maximally 4.4x10(7) cells cm(-3) at 342.5 mbsf). Analysis of 16S rRNA gene sequences revealed that the predominant cultivated microbial components were affiliated with the genera Bacillus, Shewanella, Pseudoalteromonas, Halomonas, Pseudomonas, Paracoccus, Rhodococcus, Microbacterium, and Flexibacteracea. Many of the predominant and scarce isolates produced a variety of extra-cellular enzymes such as proteases, amylases, lipases, chitinases, phosphatases, and deoxyribonucleases. Our results indicate that microbes in the deep subseafloor environment off Shimokita are metabolically active and that the cultivable populations may have a great potential in biotechnology.
authors: Extremobiosphere Research Center of Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka, 237-0061, Japan. kobayashit@jamstec.go.jp
authors: Tohru
authors: T
authors: Kobayashi
authors: Osamu
authors: O
authors: Koide
authors: Kozue
authors: K
authors: Mori
authors: Shigeru
authors: S
authors: Shimamura
authors: Takae
authors: T
authors: Matsuura
authors: Takeshi
authors: T
authors: Miura
authors: Yoshihiro
authors: Y
authors: Takaki
authors: Yuki
authors: Y
authors: Morono
authors: Takuro
authors: T
authors: Nunoura
authors: Hiroyuki
authors: H
authors: Imachi
authors: Fumio
authors: F
authors: Inagaki
authors: Ken
authors: K
authors: Takai
authors: Koki
authors: K
authors: Horikoshi
mesh_terms: D001419:Bacteria / Q000201:enzymology; D004798:Enzymes / Q000235:genetics*; D005798:Genes, Bacterial; D014644:Genetic Variation; D019015:Geologic Sediments; D007564:Japan; D008697:Methane / Q000737:chemistry*; D008957:Models, Genetic; D009930:Organic Chemicals; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology
chemical_list: D004798:Enzymes; D009930:Organic Chemicals; D012336:RNA, Ribosomal, 16S; D008697:Methane