(B) Colorimetric iron-binding assay. Glucan from diverse source binds Fe2+ iron. Extracellular (ECG) or periplasmic (PPG) glucan isolated from the wild type Xcc8004 or the ndvB (pHM1J); commercial glucan from yeast, barley and Euglena purchased from Sigma Aldrich. Glucans from various sources were incubated with FeSO4 at room temperature for 15 min, amount of free iron was determined using the standard concentration of ferrozine-Fe2+ complex. 