Deep subsurface life from North Pond; enrichment, isolation, characterization and genomes of heterotrophic bacteria

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doi: 10.3389/fmicb.2016.00678
Author(s): Russell, Joseph A.; Leon-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F.
Author Affiliation(s): Primary:
University of Delaware, College of Earth, Ocean and Environment, Lewes, DE, United States
Ohio State University, United States
Volume Title: Frontiers in Microbiology
Source: Frontiers in Microbiology, Vol.7(Article 678). Publisher: Frontiers Research Foundation, Lausanne, Switzerland. ISSN: 1664-302X
Note: In English. 65 refs.; illus., incl. 2 tables, sketch map
Summary: Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic water-column west of the Mid-Atlantic Ridge at 22°N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. The cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Arthrobacter; Atlantic Ocean; Bacteria; Basalts; Expedition 336; Experimental studies; Genetics; Growth; IODP Site U1382; IODP Site U1383; IODP Site U1384; Igneous rocks; Integrated Ocean Drilling Program; Microorganisms; Mid-Atlantic Ridge; North Atlantic; North Pond; Ocean Drilling Program; Paracoccus; Pseudomonas; Volcanic rocks
Coordinates: N224521 N224521 W0460453 W0460453
N224808 N224808 W0460310 W0460310
N224843 N224843 W0460521 W0460521
Record ID: 2016083743
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