The potential use of alkaline protease from Streptomyces albidoflavus as an eco-friendly wool modifier

Abstract

The main task of this study is to search for the proper conditions of the enzymatic treatment using an alkaline bacterial protease, as an eco-friendly option, to improve some performance properties and dyeability of grey wool fabric with acid dyes. The efficiency of the enzymatic treatment has been improved by prewashing in the presence of a nonionic wetting agent alone and in combination with H2O2. The enhancement in wool performance properties as well as in the extent of post-acid dyeing is determined by pretreatment regime, enzyme dosage, as well as enzymatic treatment conditions. For modified wool fabric samples, as the weight loss increases, the nitrogen content decreases, the whiteness index as well as the dyeability with the acid dye improves compared with the prewashed fabric samples. Proper conditions for maximising the efficiency of enzymatic treatment along with attaining better performance properties and minimal wool damage are: prewashing in the presence of a nonionic surfactant along with H2O2 followed by enzymatic treatment using the enzyme dosage (3 ml/g fabric), pH (9), incubation time (45 min), temperature (40 °C), LR (1/20) and rotational speed (40 rpm). The enzyme inactivation was performed at 100 °C for 5 min, followed by thoroughly rinsing, neutralising and air-drying before testing. SEM images also provide evidence that pretreatment of the wool substrate enhanced the proteolysis of cuticle layers, their degradation and potential removal by the subsequent protease treatment.