Siderophore production by heterotrophic bacterial isolates from the Costa Rica Upwelling Dome
Citable URI
https://hdl.handle.net/1912/2394Location
Costa Rica DomeDOI
10.1575/1912/2394Abstract
An increased understanding of heterotrophic bacterial strategies for acquiring nutrients
and trace elements is critical for elucidating their impact on biogeochemical cycling in
the ocean. It is estimated that iron is a limiting nutrient for phytoplankton growth in over
30% of the open ocean, but still little is known about bacterial strategies for iron
acquisition. Siderophore (Fe ligand) production by bacteria may play a major role in
influencing the bioavailability of iron in the ocean. Despite the importance of
siderophores in the environment, only limited information from a select group of bacteria
is available. On a cruise through the Costa Rica Dome (CRD) upwelling region in July
2005, a library of 867 isolates from five depth profiles inside and outside of the dome
was obtained and screened for siderophore production using the Chrome Azurol-S (CAS)
assay. Phylogenetic affiliation of 134 isolates was determined by sequencing the 16s
rDNA gene, and determined that gamma proteobacteria such as Alteromonas,
Pseudoalteromonas, Halomonas, and Marinobacter dominated the collection, while
alpha-proteobacteria such as Roseobacter were also represented. The isolates obtained
from stations in the CRD showed greater siderophore-producing capabilities between
55m and 100m while strains isolated from outside the CRD had shallower peak (~8-35m)
production. Functional group determination showed that hydroxamate production
dominated from 50-150m, while hydroxamate and catechol production is roughly equal
in shallower waters. By characterizing the siderophores produced by these isolates and
determining the genetic make-up of the population, these findings further our
understanding of how heterotrophic microbes affect biogeochemical processes and the
competitive nature of nutrient acquisition.
Description
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2008.
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Suggested Citation
Thesis: Krey, Whitney B., "Siderophore production by heterotrophic bacterial isolates from the Costa Rica Upwelling Dome", 2008-06, DOI:10.1575/1912/2394, https://hdl.handle.net/1912/2394Related items
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