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High-throughput Siderophore Screening from Environmental Samples: Plant Tissues, Bulk Soils, and Rhizosphere Soils
Published on: February 9, 2019
Siderophore Utilization by Bradyrhizobium japonicum
O Plessner1, T Klapatch, M L Guerinot
1Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755.
Applied and Environmental Microbiology
|May 1, 1993
Summary
Bradyrhizobium japonicum strains can use various siderophores, like ferrichrome and pseudobactin, to acquire iron. This ability to utilize external siderophores may provide a competitive edge in the plant root environment.
Area of Science:
- Microbiology
- Plant-Microbe Interactions
- Biochemistry
Background:
- Iron is essential for microbial growth, and its scarcity in the rhizosphere drives the evolution of iron acquisition strategies.
- Siderophores are high-affinity iron-chelating compounds produced by microorganisms to solubilize and scavenge environmental iron.
- Bradyrhizobium japonicum, a symbiotic bacterium, requires efficient iron uptake for its nitrogen-fixing functions.
Purpose of the Study:
- To investigate the ability of Bradyrhizobium japonicum USDA 110 and 61A152 strains to utilize different types of siderophores for iron acquisition.
- To determine if these strains can use hydroxamate-type and pyoverdin-type siderophores beyond their native iron uptake systems.
Main Methods:
- Bacterial growth assays were performed using various iron sources, including ferric citrate, ferrichrome, rhodotorulate, and pseudobactin St3.
- Iron-dependent growth was monitored to assess the utilization efficiency of each siderophore by the bacterial strains.
Main Results:
- Bradyrhizobium japonicum USDA 110 and 61A152 demonstrated the ability to utilize hydroxamate-type siderophores (ferrichrome and rhodotorulate) for growth under iron-limiting conditions.
- These strains also successfully utilized the pyoverdin-type siderophore, pseudobactin St3, indicating broad siderophore assimilation capabilities.
- Utilization of ferric citrate was confirmed as a viable iron source for both strains.
Conclusions:
- Bradyrhizobium japonicum strains possess versatile iron acquisition mechanisms, enabling them to utilize a range of exogenous siderophores.
- The capacity to assimilate siderophores from other organisms may confer a significant ecological advantage in the competitive rhizosphere environment.
- Understanding these mechanisms is crucial for optimizing symbiotic interactions and nitrogen fixation in legumes.
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