Eco-friendly anti-felting treatment of wool top based on biosurfactant and enzymes

Abstract

Anti-felting processes with low environmental impacts are important for improving wool fiber attributes, especially if fiber is intended for the organic market. The aim of this study was to assess the potential of proteolytic enzymes, alone or in combination with Bacillus subtilis O9 biosurfactant (surfactin), to reduce felting of Merino wool top. Different concentrations of extracellular proteolytic extracts from Bacillus sp. G51 and Bacillus patagoniensis PATO5T were used to treat wool top. As indicated by the felt-ball test results, a significant decrease in wool felting tendency was achieved using 50 and 150 Enzyme Units (EU)/g wool of PATO5T and G51 proteases, respectively. Neither of these treatments caused a significant reduction in wool tensile strength. The addition of a pre-treatment step with biosurfactant surfactin, at a concentration above the Critical Micelle Concentration (CMC), further reduced felting tendency of wool. The combination of biosurfactant pre-treatment followed by B. patagoniensis PATO5T protease treatment rendered the significantly smallest felt-ball density (0.049 ± 0.004 g/cm3), without a significant loss in tensile strength. In PATO5T proteolytic extract, enzyme aggregates ≥100 kDa account for about 50% of the proteolytic activity. This could reduce the velocity of protease diffusion into wool fiber, promoting its action on wool surface. According to our knowledge, this is the first report that demonstrates the usefulness of a biosufactant in an environmental-friendly process aimed at reducing wool top felting.