Growth-dependent surface characteristics of Hansenula Polymorpha: implications for expanded bed adsorption chromatography

Abstract

The cell surface characteristics of a methylotrophic wild-type strain of yeast, Hansenula polymorpha, was investigated at different growth stages (early log, late log, stationary and death) of the biomass under different conditions (low and high salt in intact and disrupted forms) using extended DLVO theory. Biomass was characterized by contact angle measurements as well as zeta potential determinations. These measurements were used to describe the hydrophobic, polar, and electrostatic behavior of the biomass in its growth stages. Consequently, interaction free energy vs. distance profiles of the biomass with anion-exchange and HIC adsorbents were conveniently generated. A strong interaction was calculated between cells and the adsorbents in the stationary and death phases of the biomass illustrated by the striking correlation between theoretical predictions and biomass deposition experiments. The physico-chemical properties of biomass in different growth phases have important implications for expanded bed adsorption chromatography, where unfavorable biomass-adsorbent interactions adversely affect process efficiency.