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Abstract When two or more bacterial species inhabit a shared niche, often, they must compete for limited nutrients. Iron is an essential nutrient that is especially scarce in the marine environment. Bacteria can use the production, release, and re‐uptake of siderophores, small molecule iron chelators, to scavenge iron. Siderophores provide fitness advantages to species that employ them by enhancing iron acquisition, and moreover, by denying iron to competitors incapable of using the siderophore–iron complex. Here, we show that cell‐free culture fluids from the marine bacteriumVibrio fischeriES114 prevent the growth of other vibrio species. Mutagenesis reveals the aerobactin siderophore as the inhibitor. Our analysis reveals a gene, that we nameaerE, encodes the aerobactin exporter, and LuxT is a transcriptional activator of aerobactin production. In co‐culture, under iron‐limiting conditions, aerobactin production allowsV. fischeriES114 to competitively excludeVibrio harveyi, which does not possess aerobactin production and uptake genes. In contrast,V. fischeriES114 mutants incapable of aerobactin production lose in competition withV. harveyi. Introduction ofiutA,encoding the aerobactin receptor, together withfhuCDB, encoding the aerobactin importer are sufficient to convertV. harveyiinto an “aerobactin cheater.”
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Petrobactin, a siderophore produced by Alteromonas , mediates community iron acquisition in the global ocean
Abstract It is now widely accepted that siderophores play a role in marine iron biogeochemical cycling. However, the mechanisms by which siderophores affect the availability of iron from specific sources and the resulting significance of these processes on iron biogeochemical cycling as a whole have remained largely untested. In this study, we develop a model system for testing the effects of siderophore production on iron bioavailability using the marine copiotroph Alteromonas macleodii ATCC 27126. Through the generation of the knockout cell line ΔasbB::kmr, which lacks siderophore biosynthetic capabilities, we demonstrate that the production of the siderophore petrobactin enables the acquisition of iron from mineral sources and weaker iron-ligand complexes. Notably, the utilization of lithogenic iron, such as that from atmospheric dust, indicates a significant role for siderophores in the incorporation of new iron into marine systems. We have also detected petrobactin, a photoreactive siderophore, directly from seawater in the mid-latitudes of the North Pacific and have identified the biosynthetic pathway for petrobactin in bacterial metagenome-assembled genomes widely distributed across the global ocean. Together, these results improve our mechanistic understanding of the role of siderophore production in iron biogeochemical cycling in the marine environment wherein iron speciation, bioavailability, and residence time can be directly influenced by microbial activities.
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- PAR ID:
- 10283047
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- The ISME Journal
- Volume:
- 16
- Issue:
- 2
- ISSN:
- 1751-7362
- Format(s):
- Medium: X Size: p. 358-369
- Size(s):
- p. 358-369
- Sponsoring Org:
- National Science Foundation
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