Single Phototrophic Bacterium-Mediated Iron Cycling in Aquatic Environments

Area of Science:

• Environmental microbiology
• Biogeochemical cycles
• Microbial iron metabolism

Background:

• Iron redox cycling is crucial for aquatic nutrient and elemental cycles.
• Microbial processes, including Fe(II)-oxidation and Fe(III)-reduction, mediate natural iron cycling.
• Understanding microbial roles in iron transformation is key to aquatic geochemistry.

Purpose of the Study:

• To investigate iron cycling mediated by a single phototrophic species, Rhodobacter ferrooxidans SW2.
• To identify the mechanisms and components involved in Fe(III) reduction by this bacterium.
• To explore the broader implications of anoxygenic photoferrotrophs in iron redox transformations.

Main Methods:

• Bacterial cultivation of Rhodobacter ferrooxidans SW2 under specific conditions.
• Identification and characterization of a c-type cytochrome involved in Fe(III) reduction.
• Analysis of iron redox transformation capabilities influenced by light and organic substrates.

Main Results:

• Rhodobacter ferrooxidans SW2 demonstrated Fe(III) reduction during cultivation.
• A c-type cytochrome was identified as a key component in the Fe(III)-reducing pathway.
• Iron redox transformation by R. ferrooxidans SW2 is dependent on light and/or organic substrate availability.

Conclusions:

• Rhodobacter ferrooxidans SW2 actively participates in iron redox cycling.
• The identified cytochrome links Fe(III) reduction to the bacterium's electron transport system.
• Anoxygenic photoferrotrophs play significant, multifaceted roles in aquatic iron cycling, relevant to modern and ancient environments.