Siderophore production by heterotrophic bacterial isolates from the Costa Rica Upwelling Dome
Krey, Whitney B.
MetadataShow full item record
LocationCosta Rica Dome
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.
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.
Showing items related by title, author, creator and subject.
The ecology, life history, and phylogeny of the marine thecate heterotrophic dinoflagellates Protoperidinium and Diplopsalidaceae (Dinophyceae) Gribble, Kristin E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006-09)Marine thecate heterotrophic dinoflagellates likely play an important role in the consumption of primary productivity and in the trophic structure of the plankton, yet we know little about these species. This thesis ...
New insights on the ecology of free-living heterotrophic nanoflagellates based on the use of molecular biological approaches Lim, Ee Lin (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-03)Nanoplanktonic protists comprise a diverse assemblage of flagellate species responsible for various trophic processes in marine and freshwater ecosystems. Current methods for identifying small protists do not readily ...
Choi, Joon Won (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1988-09)The major role of heterotrophic nanoilagellates in the ocean is generally thought to be as grazers of bacteria, but they may also play an important role as grazers of photoautotrphs. The goal of the present study was ...