Hydrophobin purification based on the theory of CO₂-nanobubbles

ABSTRACT

Purification is a critical step to obtain hydrophobin HFBII for use in positive applications. In this study, hydrophobin HFBII was produced by Trichoderma reesei via submerged fermentation. Using the CO₂-foam fractionation method yielded a fourfold increase in protein concentration. The foamate (α_L-HFBII) was dried using a nano spray-dryer under optimal temperature. The gushing activity of the dried foamate (α_S-HFBII) decreased. Addition of Tween 80 to the foamate before the drying process partially prevented the deactivation of hydrophobin HFBII. The purity of the powder was enhanced based on the theory of CO₂-nanobubbles in a CO₂-rich environment. The collected CO₂-nanobubbles were added to an apolar–polar system and the interface of these two phases was collected. After evaporation of the apolar phase, the purity of the hydrophobins assembled on the surface of the liquid was significantly improved.

GRAPHICAL ABSTRACT

KEYWORDS:

• CO₂-nanobubbles
• foam fractionation
• gushing
• hydrophobin
• nano spray-drying
• purification

Acknowledgments

The authors are grateful to the Hydrophobin Chair 2 at KU Leuven and Iran National Elites Foundation (INEF)-International Department for supporting this work.