2005 Annual Science Report

University of Hawaii, Manoa Reporting  |  JUL 2004 – JUN 2005

Integrated Characterization of Microbial Communities Associated With Aquatic Redox Gradients

Project Summary

Our investigations of oxic-anoxic transitions are focused on understanding the synergy between geochemical processes and microbial community and metabolic diversity. These studies not only further our understanding of geochemical cycles that have shaped the evolution of Earth but also have the potential to contribute to flight-related missions through the development of in situ measurement technologies.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Our investigations of oxic-anoxic transitions are focused on understanding the synergy between geochemical processes and microbial community and metabolic diversity. These studies not only further our understanding of geochemical cycles that have shaped the evolution of Earth but also have the potential to contribute to flight-related missions through the development of in situ measurement technologies.

(1) Subseafloor basement (basalt) biosphere studies:

Using UHNAI funds in 2004-2005, we have begun to acquire laboratory equipment and initiate the first environmental electrochemistry research effort at UH making use of solid-state voltammetric sensors (Figure 1).

{{ 1 }}

Voltammetric techniques provide simultaneous, real-time detection of O2, H2O2, HS, S(0), Sx2, S2O3, S4O6, Fe(II), Fe(III), FeS(aq), Mn(II), and Zn(II). We have leveraged the UHNAI funding with a grant awarded to Cowen and Glazer from NOAA Office of Exploration (NOAA-OE-2005-014) aimed at characterizing subseafloor hydrothermal fluids. We have already acquired and tested an in situ voltammetric analyzer capable of seafloor data-logging. A plumbing manifold has been designed and is being fabricated to attach to standard ODP borehole CORKs (Circulation Obviation Retrofit Kits). We are working with UH support engineers to mate the electrochemical analyzer to an in situ filtration unit and will deploy the unit from the manned submersible, DSV Alvin, during a cruise to the flanks of Juan de Fuca in September, 2005, targeting IODP borehole observatory 1301A, which is in Cascadia Basin. Another key development is that of wireless acoustic and optical communications between the submersible and our analyzer package. Figure 2 represents a scale schematic of our deployment package at the borehole.

{{ 2 }}

(2) Rapid response to remotely detected potential seafloor eruption:

Remote detection of seismic activity on the Endeavour Segment of the Juan de Fuca Ridge prompted a rapid response cruise aimed at detecting any large-scale hydrothermal plume that may have been released from seafloor magmatic events (March 2005). Although the team found no evidence for any seafloor eruption, we did successfully demonstrate evidence for the presence of partially-oxidized sulfur intermediates (S2O32-, Sx2-, S(0)) in discrete water samples collected from chronic hydrothermal plumes over the Endeavour Vent Field, Juan de Fuca Ridge (Figure 3).

{{ 3 }}

The coexistence of thiosulfate and sulfide could be an artifact of temporal changes between water sample collection, or could be a previously undetected signature for significant concentrations of thiosulfate in chronic hydrothermal plumes. We hope to utilize an in situ voltammetric analyzer deployed on a ctd to verify the presence of thiosulfate in the plumes.

(3) Geomicrobiology of near-shore porous sandy sediments:


Much of what we know today about sediment geochemistry and redox transitions is based on fine-grained sediments. Typically, studies using traditional wet chemistry methods report reduced concentrations of oxygen in porous sediments, but do not detect any sulfur species. Physical and biological processes are vastly different in porous sediments than in fine-grained sediments, and carbonate reef sediments, in particular, may be important in evolutionary terms, as reef sediments represent an ecological niche that did not exist prior to the rise of coral animals ~500mya. We duplicated an existing design and commissioned the construction of electrochemical flowcells primarily for porewater sampling from sediment microcosms (Gaidos) and natural sediments (Figure 4).

{{ 4 }}

These flowcells will also function in a number of other collaborative studies including microrespirometers (Gaidos), and gastight sampling of discrete water samples from ctd rosette bottles (Cowen). During a recent field expedition, we measured the presence of reduced sulfide and an aqueous form of FeS in natural carbonate sediments as little as 30cm below the sediment-water interface. We intend to follow up these preliminary results with the design of a method for profiling the sediments to map the vertical gradients, as opposed to taking measurements at only discrete vertical horizons. Collaboration with Gaidos & Sorenson has thus far produced clone libraries to describe the constituents of the corresponding microbial communities. We intend to continue with metabolic characterization of particularly the N & S cycle.

(4) A cross-platform software package for efficient data reduction of environmental electrochemical measurements:

Through collaboration with Kim Binsted, we are working toward an automated software package for voltammetric scan analysis, a web-oriented database of electrochemical calibration information, and ‘intelligent’ data acquisition software capable of making directed sampling decisions during long, unattended data-logging deployments. Binsted has provided summer research credit for two graduate students to work on this project. Kayo Fujiwara has utilized Matlab and is optimizing a peak-identifying and measuring algorithm. Bryan Norman is working on a Java-based graphical user interface. Binsted, Glazer, Fujiwara, and Norman have met weekly to improve design and track progress.

(5) Geomicrobiology of neutrophilic iron-oxidizing bacteria at Loihi Seamount:

Katrina Edwards (WHOI, MBL-NAI affiliate) is leading a team to study the microbiology of iron-oxidizing bacteria at Loihi (NSF Microbial Observatories) and has invited Glazer and Cowen to join their expeditions and efforts. We have just submitted a proposal to NASA to support our involvement. Integrating the team of Cowen (UH-NAI Co-I), Glazer (UH-NAI postdoc), and Binsted (UH-NAI Co-I) with a collaborative effort involving members of the Marine Biological Laboratory NAI (Edwards) and UC Berkeley NAI (Emerson) represents a potentially powerful inter-NAI collaboration.

  • PROJECT INVESTIGATORS:
    Brian Glazer Brian Glazer
    Postdoc
  • PROJECT MEMBERS:
    James Cowen
    Co-Investigator

    Eric Gaidos
    Co-Investigator

    Kimberly Binsted
    Collaborator

    Mark Brown
    Postdoc

    Ketil Sorensen
    Postdoc

    Kayo Fujiwara
    Doctoral Student

    Bryan Norman
    Doctoral Student

  • RELATED OBJECTIVES:
    Objective 5.1
    Environment-dependent, molecular evolution in microorganisms

    Objective 5.2
    Co-evolution of microbial communities

    Objective 5.3
    Biochemical adaptation to extreme environments

    Objective 6.1
    Environmental changes and the cycling of elements by the biota, communities, and ecosystems