Expression and one-step purification of a β-galactosidase by fusion with elastin-like polypetides

► Inverse transition cycling was applied for purifying halophilic β-galactosidase. ► High-level expression of the fusion was achieved. ► A quick activity measurement was designed for the optimal purification conditions. ► ELP fusion obtained over 90% activity recovery and 95% purity by one cycle.