Iron is an essential micronutrient for heterotrophic marine bacteria due to its role as a cofactor in enzymes involved in key metabolic processes such as respiration. However, iron is present at extremely low concentrations in the open ocean and most of it is bound in organic ligand complexes. The concentration and bioavailability of this ligand-bound iron is an important abiotic factor that can regulate the ability of marine bacteria to remineralize organic matter. In this study, we utilized a combination of lab model-based and field-based approaches to investigate the importance of different ligand substrates, primarily siderophores, as sources of bioavailable iron for marine bacteria and their impact on bacterial growth and turnover of organic matter. In the lab, we utilized functional genomics techniques to elucidate the iron-acquisition mechanisms associated with common marine siderophores (desferrioxamine B and petrobactin) for the marine copiotroph Alteromonas macleodii. The impact of Alteromonas macleodii’s ability to utilize these iron-siderophore complexes on its growth rate and biomass production was tested in artificial and natural seawater-based conditions. In addition, field-based incubations of microbial communities artificially enriched with iron in different productivity zones of the California current ecosystem were analyzed using metatranscriptomics. Overall, the results from these different approaches will highlight the role of various microbial genes/transcripts involved in iron-acquisition from the marine ligand pool, and the subsequent impact of these iron-acquisition strategies on the microbial turnover of organic matter in marine systems.

Primary Presenter: Adit Chaudhary, University of California San Diego (adchaudhary@ucsd.edu)

Authors:

Adit Chaudhary, Scripps Institution of Oceanography/University of California San Diego  (adchaudhary@ucsd.edu)

Jocelyn Macho,   ()

Erin Garza,   ()

Rob Lampe,   ()

Andrew Allen,   ()

Christopher Dupont,   ()

Katherine Barbeau, Scripps Institution of Oceanography/University of California San Diego  (kbarbeau@ucsd.edu)