Endophytic Bacteria from Salt Marsh Plants as Potential Agents for Heavy Metal Bioremediation: A Preliminary Investigation of Siderophore Production and Metal Removal Efficiency

Siderophores are low molecular weight compounds widely produced by microorganisms. These molecules exhibit a high affinity for iron, a crucial metal involved in many microbial metabolic activities. In addition to iron, siderophores have also been found to chelate other metal ions such as chromium (Cr), zinc (Zn), cobalt (Co), and cadmium (Cd). In recent years, their potential in the bioremediation of heavy metals has been extensively studied, as they can effectively chelate a variety of metal ions, including toxic heavy metals. Among siderophore producing microbes, those originating from the saline environment remains less explored. Therefore, in the present study, halophilic endophytes from salt marsh plants were studied for its potential to produce siderophores and analysed for its efficacy in remediating heavy metals. From our previous study six endophytes designated as SR, IR, IS, CL, SS, SL from four halophytes of two different saline environments Rhizophora mucoronata, Ceriops decandra, Ipomea pes-caprae and Spinifex littoreus were identified as potential siderophore producers. Among them, three isolates SR, IS, IR with highest Siderophore Production Index (SPI) in CAS agar plates were further selected for optimization and remediation studies. Optimization by Response Surface methodology revealed the model fits best for isolate IR, while it showed lack of fit for both SR and IS. Bioremediation studies of these isolates by FTIR revealed that these organisms were capable of removing copper, chromium and lead making it a potential candidate for bioremediation of heavy metals and water treatment.