Iron Acquisition by Bdellovibrio bacteriovorus

Abstract

To advance the understanding of the gram-negative, obligate aerobic bacterium Bdellovibrio bacteriovorus, we investigated how this unique predator acquires iron, a nutrient essential to the survival of all living organisms. Our current research into this bacterium follows two broad inquiries. The first question asks how B. bacteriovorus responds to a prey containing a large repository of Fe. One such prey is Magnetospirillum magnetotacticum, a gram-negative, microaerophilic bacterium containing a string of iron magnetite magnetosomes. To address this question, we first needed to formulate a technique to propagate B. bacteriovorus on M. magnetotacticum. We successfully developed this method in our laboratory this summer, confirming for the first time the ability of B. bacteriovorus to grow solely on M. magnetotacticum. Experiments continue to determine if B. bacteriovorus takes up prey magnetosomes during predation on M. magnetotacticum. Our second question considers whether B. bacteriovorus makes siderophores to acquire Fe during the attack phase or growth phase of its lifecycle. Siderophores are bacterial complexes efficient at binding to iron. In order to determine whether B. bacteriovorus produces siderophores to attain Fe, we turned to a published siderophore assay. The assay is a colorimetric test that indicates the removal of iron by siderophores from a solution. In this assay, results show that attack-phase B. bacteriovorus do not produce siderophores. We continue with experiments to address how the predator obtains Fe during its growth phase within the prey.