Role of the EDTA Chelating Agent in Bioscouring of Cotton

Our previous work demonstrated that ethylenediamine-tetra-acetic acid (EDTA) markedly enhances the apparent activity of commercial xylanase and pectinase enzymes in cotton bioscouring, accelerating degradation and removal of impurities. In this study, we explore how EDTA can improve the efficiency of the enzyme process in cotton bioscouring. The effects of EDTA on the enzyme action and degradation of seed-coat fragments—the most resistant natural impurities of cotton to be degraded in bioscouring—are investigated. Results show that application of EDTA in different concentrations does not inhibit the main activities of the enzymes investigated. Thus, the pectinase activity of Viscozyme 120L and the xylanase activity of Pulpzyme HC remain almost unchanged. On the other hand, EDTA modifies the substrate structure by removing the calcium ions from the cross bridges that link the macromolecules in pectin to one another or pectin to other polysaccharides. While EDTA pretreatment significantly decreases the efficiency of enzymatic hydrolysis monitored by reducing sugar liberation, simultaneous application of EDTA and enzyme in one treatment bath largely accelerates the degree of hydrolysis, indicating a synergistic effect of enzyme and EDTA.