Initial Sephadex G-15 column fractionation of an 85% ethanol extract of dried culture filtrate from Pseudomonas fluorescens SBW25. The solids from 840 mL of dried SBW25 culture filtrate were extracted with 85% ethanol as described in the Methods section. A portion of the extract equivalent to 800 mL of original culture filtrate was taken to dryness in vacuo and dissolved in 6 mL of deionized water for application to a Sephadex G-15 column equilibrated in the same solvent. The column was eluted with deionized water. Fractions (6 mL each) were collected and analyzed for reaction with the Fe- and Cu-CAS reagents as described in the Methods section. The fractions corresponding to the largest Cu-binding peak were pooled (as indicated by the double arrow) for concentration and further purification by preparative TLC fractionation.