We studied the interactions between natural colonies of the ecologically significant nitrogen fixing marine cynaobacterium Trichodesmium and their associated bacteria during mineral and dust-iron utilization. Dust is a significant potential iron source to phytoplankton in the open ocean, but its biological use is restricted by rapid sinking of particles and low dust-Fe solubility. Many marine bacteria have the genetic knowhow of excreting siderophores, strong iron chelators capable of solubilizing dust and mineral iron. We hypothesize that bacteria associated with Trichodesmium play a role in solubilizing dust-iron by releasing siderophores. Using advanced separation and identification techniques we detected and partially quantified large array of siderophores from naturally occurring Trichodesmium blooms of Red Sea and Arabian Sea. We examined the differential ability of the colony members to acquire iron from minerals by incubating fresh natural populations with radiolabelled ferrihydrite and separating Trichodesmium from its associated bacteria. By adding active and inactivated siderophores (extracted from bacterial isolate) to paired experiments, we probed for the effect of siderophores on Ferrihydrite solubilization and uptake. The added siderophores enhanced ferrihydrite solubilization and iron uptake by both Trichodesmium and its associated bacteria, suggesting that their quest for dust-iron is mutual.