Aquatic Sciences Meeting, Albuquerque 2001

SS14 Microbial Diversity (Disciplinary Connections)

Date: Tuesday, February 13, 2001, Time: 11:45:00 AM

Location: Mesilla

Zehr, J, P, University of California, Santa Cruz, USA, zehrj@cats.ucsc.edu

Turner, P, J, University of California, Santa Cruz, USA, zehrj@cats.ucsc.edu

Omoregie, E, , University of California, Santa Cruz, USA, enomao@cats.ucsc.edu

Hansen, A, , University of Hawaii, Honolulu, USA, ahansen@hawaii.edu

Steward, G, F, University of California, Santa Cruz, USA, gsteward@cats.ucsc.edu

Waterbury, J, B, Woods Hole Oceanographic Inst., Woods Hole, USA, jwaterbury@whoi.edu

Montoya, J, P, Georgia Institute of Technology, Atlanta, USA, j.montoya@biology.gatech.edu

Tupas, L, , University of Hawaii, Honolulu, USA, ltupas@soest.hawaii.edu

Karl, D, M, University of Hawaii, Honolulu, USA, dkarl@soest.hawaii.edu

NITROGENASE GENE EXPRESSION IN THE NORTH PACIFIC GYRE

The availability of nitrogen is one of the crucial factors constraining oceanic primary productivity, and ultimately controlling global atmosphere-ocean carbon balances. Nitrogen-fixing organisms should be keystone microorganisms in nitrogen-limited waters, and yet only a few nitrogen-fixing microorganisms are generally believed to be important in oceanic nitrogen balances. Diverse gene sequences for nitrogenase have previously been found in the major oceans, primarily at the long-term monitoring sites BATS and ALOHA, but it was not clear that these microorganisms actively fix nitrogen. Nitrogenase gene transcripts (mRNA), indicative of active transcription of the nitrogenase genes, were detected by RT-PCR from surface waters at station ALOHA in the North Pacific Subtropical Gyre. Nitrogenase gene sequences recovered were similar to those previously recovered from DNA in different years and in different seasons at station ALOHA. Nitrogenase genes were expressed in a distinct diel pattern throughout the upper 150 m water column. The distribution of the different types of microorganisms was assessed by cloning and sequencing and by TRFLP analyses. Data supporting the biogeochemical significance of these microorganisms was obtained using stable isotopic and microscopic methods.

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Aquatic Sciences Meeting, Albuquerque 2001

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