The optimization of thermostable recombinant α-amylase for efficient fabric desizing using response surface...

A thermostable α-amylase gene (Amyk4) from Bacillus licheniformis k4cm (or similar thermophilic Bacillus), isolated from a Himalayan hot spring in Sikkim, India, was successfully cloned and expressed in Escherichia coli BL21(DE3). The purified recombinant α-amylase (Amyk4) exhibited maximal activity (153.2 ± 1.05 U/mL) at 80 °C and pH 6.0, with a half-life of 30.39 h and enhanced stability in the presence of Ca²⁺, indicating its suitability for high-temperature industrial applications. The cotton fabric desizing was optimized using Response Surface Methodology (Box-Behnken design). Optimal conditions (pH 6.9, 80 °C, enzyme dosage of 190 U/g, and treatment time of 95 min) achieved a TEGEWA rating of 8 and a weight loss of 6.6%. The quadratic model showed strong statistical validity (R² = 0.9205 for TEGEWA and 0.9168 for weight loss). Among the evaluated variables, pH, enzyme concentration, and reaction time significantly influenced desizing efficiency. Non-ionic surfactants slightly improved desizing efficiency compared to ionic surfactants. Scanning electron microscopy (SEM) analysis confirmed effective starch removal without fibre damage. These findings demonstrate the potential of recombinant Amyk4 as a thermostable, eco-friendly candidate for sustainable textile desizing applications.