what is CAS assay
Chrome azurol S (CAS) is a method that can be used to detect the mobilization of iron. In many soils iron is not often in an abundant form that plants can readily uptake and use.Siderophores are produced by rhizosphere bacteria to help enhance plant growth by increasing the availability of iron near the root (1).o perform CAS analysis a strong ligand (e.g. siderophore) is added to a highly colored iron dye complex. When the iron ligand complex is formed the release of the free dye is accompanied with a color change (7). Since CAS assay is high in sensitivity it is able to be used on agar plates.