title: Metagenomic analysis of 0.2-μm-passable microorganisms in deep-sea hydrothermal fluid.
abstract: We pyrosequenced the bulk DNA extracted from microorganisms that passed through 0.2-μm-pore-size filters and trapped by 0.1-μm-pore-size filters in the hydrothermal fluid of the Mariana Trough. Using the 454-FLX sequencer, we generated 202,648 sequences with an average length of 173.8 bases. Functional profiles were assigned by the SEED Annotation Engine. In the metagenome of the 0.2-μm-passable microorganisms, genes related to membrane function, including potassium homeostasis classified as membrane transport, and multidrug-resistance efflux pumps classified as virulence, were dominant. There was a higher proportion of genes pertinent to the subsystem of membrane transport in our metagenomic library than in other oceanic and hydrothermal vent metagenomes. Genes associated with a RND-type efflux transporter for exogenous substances were specifically identified in the present study. After a comparative analysis with the genome of the known ultramicrobacterium Sphingopyxis alaskensis RB2256, we discovered 1,542 cases of significant hits (E < 1 × 10(-2)) in our metagenome, and 1,172 of those were related to the DNA repair protein RadA. In this way, the microbial functional profile of 0.2-μm-passable fraction in the present study differs from oceanic metagenomes in the 0.2-μm-trapped fractions and hydrothermal vent metagenomes reported in previous research.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Nakai
authors.forename: Takashi
authors.initials: T
authors.lastname: Abe
authors.forename: Haruko
authors.initials: H
authors.lastname: Takeyama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Naganuma
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics*; D023281:Genomics / Q000379:methods*; D060086:Hydrothermal Vents; D010802:Phylogeny; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial