Immobilised metal affinity chromatography (IMAC) is an aqueous-compatible separation technique that has recently been shown to have utility in the purification of metal-binding metabolites with important clinical applications, namely the siderophore desferrioxamine B (DFOB) and the anticancer agent bleomycin1,2. The IMAC resin consists of a matrix of solid beads, each covalently bound to a chelator which in turn coordinates a metal ion. Metal-binding compounds in a mixture coordinate to the metal ion via the remaining coordination sites and are isolated from other mixture components3.
Previous studies used a single IMAC column to capture a single class of metabolite from a bacterial culture1,2. The present study explores the potential of "multi-dimensional IMAC" (MD-IMAC) to capture more than one metabolite class from a single bacterial culture. MD-IMAC involves joining two single IMAC columns in sequence, with the goal of capturing a different metabolite on each resin. The selectivity of the IMAC resin for a particular metabolite is affected by the metal ion that the resin is charged with and the covalently-bound chelator attached to the resin beads. By varying these factors, we can tune each resin in the MD-IMAC setup to capture a different metabolite.
Streptomyces verticillus is a known producer of bleomycin4 and evidence has shown that this bacteria also produces siderophores (data unpublished). This study aimed to develop MD-IMAC for the simultaneous capture of these two metabolites. The first part of this study involved optimisation of the MD-IMAC setup, using commercial standards of bleomycin and DFOB, to find the optimal resin for the capture of each metabolite. The second part of this study involved culturing S. verticillus and using the optimised MD-IMAC setup to capture native bleomycin and siderophores.
This work has implications for green chemistry and streamlining pharmaceutics processing.