The application of dye-ligand expanded bed chromatography adsorption (EBA) of glucose-6-phosphate dehydrogenase (G6PDH) from unclarified yeast extract was undertaken by using a commercially available expanded bed column (20 mm. i.d.) and UpFront adsorbent (rho = 1.5 g/mL) from UpFront Chromatography. The influence of biomass concentration on the adsorption capacity was explored by employing yeast extracts containing various biomass concentrations (5-30%, w/v). It was demonstrated that the biomass concentration had little effect on G6PDH adsorption performance. Feedstock containing 15% (w/v) biomass gave a relatively high recovery yield (> 90%) of G6PDH compared to feedstock containing 30% (w/v) biomass, which gave a recovery of 75% G6PDH. Nevertheless, the enzyme specific activity of 7 U mg(-1) with a purification factor of 6 was achieved in the feedstock containing biomass concentration of 30% (w/v). The generic applicability of dye-ligand as an affinity tool in expanded bed chromatography is discussed. (c) 2006 Elsevier Ltd. All rights reserved.